NASA / TP--2000-210481

A Comparison of Quasi-Static Indentation

to Low-Velocity Impact

A. T. Nettles

Marshall Space Flight Center, Marshall Space Flight Center, Alabama

M.J. Douglas

Old Dominion University, Norfolk, Virginia

IIIII

August 2000
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NASA / TP--2000-210481

A Comparison of Quasi-Static Indentation

to Low-Velocity Impact

A. T. Nettles

Marshall Space Flight Center, Marshall Space Flight Center, Alabama

M.J. Douglas

Old Dominion University, Norfolk, Virginia

National Aeronautics and

Space Administration

Marshall Space Flight Center

August 2000
NASA Center for AeroSpace Information

7121 Standard Drive

Hanover, MD 21076--1320

(301) 62 !-0390

Available from:

ii

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TABLE OF CONTENTS

°

2.

o

INTRODUCTION ............................................ •.......................................................................

PREVIOUS WORK ..................................................................................................................

2.1 Background ........................................................................................................................

2.2 Impact Versus Quasi-Static Testing ...................................................................................

2.3 Conclusions From Past Studies .........................................................................................

EXPERIMENTAL PROCEDURE ...........................................................................................

3.1 Introduction .......................................................................................................................

3.2 Boundary Conditions .........................................................................................................

3.3 Flexural Rigidity of Specimens .........................................................................................

3.4 Materials ............................................................................................................................

3.5 Mathematical Foundation ..................................................................................................

3.6 Impact Testing Procedure ..................................................................................................

3.7 Static Indentation Testing Procedure .................................................................................

3.8 Nondestructive Analysis ....................................................................................................

4. RESULTS AND DISCUSSION ...............................................................................................

4.1 Introduction .......................................................................................................................

4.2 Drop-Weight Impact Testing .............................................................................................

4.3 Quasi-Static Indentation Testing ........................................................................................

4.4 Nondestructive Analysis ....................................................................................................

4.5 Crack Length .....................................................................................................................

4.6 Delamination Area .............................................................................................................

4.7 Comparison of Quasi-Static Indentation Testing and Drop-Weight

Impact Testing .....................................................................................................................

5. CONCLUSIONS ......................................................................................................................

APPENDIX A--IMPACT SPECIMEN IDENTIFICATION NUMBERS .......................................

APPENDIX B--LOAD VERSUS DEFLECTION PLOTS FOR IMPACT SPECIMENS ..............

APPENDIX C--LOAD VERSUS DEFLECTION PLOTS FOR QUASI-STATIC

INDENTATION TESTS ........................................................................................

APPENDIX D--NONDESTRUCTIVE EVALUATION ANALYSIS DATA ...................................

REFERENCES ...............................................................................................................................

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LIST OF FIGURES

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Test platen used for simply supported testing ..................................................................

Modifications to test platen for clamped test ...................................................................

Impactor/laminate failure mode .......................................................................................

Typical cure cycle for IM7/8552 prepreg laminate ..........................................................

Schematic of an 8-ply laminate stacking sequence ..........................................................

Typical time versus load plot ...........................................................................................

Typical load versus displacement plot for impact testing ................................................

Test fixture for quasi-static indentation testing ................................................................

Typical load versus displacement plot for quasi-static indentation testing ......................

X-ray of impact specimen with 4 mm 2 grid superimposed .............................................

Impact duration versus stiffness ratio for clamped boundary conditions .........................

Impact duration versus stiffness ratio for simply supported

boundary conditions .........................................................................................................

Crack length versus dent depth clamped boundary conditions ........................................

Crack length versus dent depth simply supported boundary conditions ..........................

Delamination area versus dent depth clamped boundary conditions ...............................

Delamination area versus dent depth simply supported boundary conditions .................

Delamination area versus maximum load for 8-ply specimens

over 6-in. opening ............................................................................................................

Delamination area versus maximum load for 16-ply specimens

over 12-in. opening ..........................................................................................................

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LIST OF FIGURES (Continued)

Delamination area versus maximum load for 8-ply specimens

over 2-in. opening ............................................................................................................

Delamination area versus maximum load for 16-ply specimens

over 4-in. opening ............................................................................................................

Delamination area versus maximum load for 48-ply specimens

over 12-in. opening ..........................................................................................................

Delamination area versus maximum load for 16-ply specimens

over 2-in. opening ............................................................................................................

Delamination area versus maximum load for 32-ply specimens

over 4-in. opening ............................................................................................................

Delamination area versus maximum load for 48-ply specimens

over 6-in. opening ............................................................................................................

Static indentation data supenmposed over impact data for 8-ply

clamped specimens over a 6-in. opening .........................................................................

Static indentation data superimposed over impact data for 16-ply

simply supported specimens over a, 12-in. opening .........................................................

Static indentation data supenmposed over impact data for 16-ply

clamped specimens over a 4-in. opening .........................................................................

Static indentation data supenmposed over impact data for 48-ply

clamped specimens over a 12-in. opening .......................................................................

Static indentation data supenmposed over Impact data for 48-ply

clamped specimens over a 6-in. opening .........................................................................

Static indentation data supenmposed ovei impact data for 32-ply

clamped specimens over a 4-in. opening .........................................................................

Static indentation data supenmposed over Impact data for 32-ply

simply supported specimens over a 4-in. opening ...........................................................

Load versus deflection specimen 727-06f .......................................................................

Load versus deflection specimen 727-07f .......................................................................

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LIST OF FIGURES (Continued)

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Load versus deflection specimen 727--08f .......................................................................

Load versus deflection specimen 727-09f .......................................................................

Load versus deflection specimen 727-1 Of .......................................................................

Load versus deflection specimen 728-05f .......................................................................

Load versus deflection specimen 728-06f .......................................................................

Load versus deflection specimen 728-02m .....................................................................

Load versus deflection specimen 728-03m .....................................................................

Load versus deflection specimen 728-04m .....................................................................

Load versus deflection specimen 727-1 lm .....................................................................

Load versus deflection specimen 727-12m .....................................................................

Load versus deflection specimen 727-13m .....................................................................

Load versus deflection specimen 727-14m .....................................................................

Load versus deflection specimen 727-15m .....................................................................

Load versus deflection specimen 61599-02m .................................................................

Load versus deflection specimen 61599-03m .................................................................

Load versus deflection specimen 727-20s .......................................................................

Load versus deflection specimen 727-21 s .......................................................................

Load versus deflection specimen 727-22s .......................................................................

Load versus deflection specimen 728-01s .......................................................................

Load versus deflection specimen 727-16s .......................................................................

Load versus deflection specimen 727-17s .......................................................................

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LIST OF FIGURES (Continued)

Load versus deflection specimen 727-18s .......................................................................

Load versus deflection specimen 727-19s .......................................................................

Load versus deflection specimen 727-02s .......................................................................

Load versus deflection specimen 616-15f .......................................................................

Load versus deflection specimen 6|6-16f .......................................................................

Load versus deflection specimen 616-17f .......................................................................

Load versus deflection specimen 616-18f .......................................................................

Load versus deflection specimen 616-01 f .......................................................................

Load versus deflection specimen 616-02f .......................................................................

Load versus deflection specimen 6 | 6-03f .......................................................................

Load versus deflection specimen 616-04f .......................................................................

Load versus deflection specimen 616-37m .....................................................................

Load versus deflection specimen 616-38m .....................................................................

Load versus deflection specimen 728-09m .....................................................................

Load versus deflection specimen 728-11 m .....................................................................

Load versus deflection specimen 616-25m .....................................................................

Load versus deflection specimen 616-26m .....................................................................

Load versus deflection specxmen 616-27m .....................................................................

Load versus deflection specimen 616-28m .....................................................................

Load versus deflection specimen 61599-04m .................................................................

Load versus deflection specimen 61599-05m .................................................................

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97.

LIST OF FIGURES (Continued)

Load versus deflection specimen 616-29s .......................................................................

Load versus deflection specimen 616-30s .......................................................................

Load versus deflection specimen 616-31s .......................................................................

Load versus deflection specimen 616-32s .......................................................................

Load versus deflection specimen 616-20s .......................................................................

Load versus deflection specimen 616-2 Is .......................................................................

Load versus deflection specimen 616-22s .......................................................................

Load versus deflection specimen 708-10f .......................................................................

Load versus deflection specimen 708-1 If .......................................................................

Load versus deflection specimen 1018-02f .....................................................................

Load versus deflection specimen 708-03m .....................................................................

Load versus deflection specimen 708-02m .....................................................................

Load versus deflection specimen 708-04m .....................................................................

Load versus deflection specimen 708-05m .....................................................................

Load versus deflection specimen 708-06m .....................................................................

Load versus deflection specimen 1015-01 m ...................................................................

Load versus deflection specimen 1015-02s .....................................................................

Load versus deflection specimen 708-07s .......................................................................

Load versus deflection specimen 708-08s .......................................................................

Load versus deflection specimen 1015-03s .....................................................................

Load versus deflection specimen I018-03s .....................................................................

Load versu s deflection spec lmen 706-0 1s .......................................................................

VIII

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LIST OF TABLES

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20.

Conclusions from previous studies

................. ..... •..... ..............................,................ ..... . 6

Material properties .......................................................................................................... 10

Opening and laminate thickness ratio calculations ......................................................... 12

Maximum load and drop height for the clamped boundary conditions .......................... 13

Maximum load and drop height for the simply supported boundary conditions ............ 13

5,000- and lO,O00-1b load ceil comparison .................................................................... 14

Identification numbers and maximum loads for clamped specimens ............................. 19

Identification numbers and maximum loads for simply supported specimens .............. 20

Clamped flex ................................................................................................................... 37

Clamped medium ............................................................................................................ 38

Clamped stiff

......... •................. """'"'"".. ....... .................., ....... ............ ..... .................... 39

Simply supported flex ..................................................................................................... 39

Simply supported medium ............... "'''''''''°''°°''°' .... *'',*,,, ................... ,I,,,oo.°o,o, ..... °**,0°°,,°° 40

Simply supported stiff

Simply supported flex ...................... •........ •..... .... ....... •............. .... ....... •........ .....,...,.,,...... 76

Simply supported medium ....... °....... "--"'".......................,..,.......... ............. .................... 77

Simply supported stiff

..................... • ,*,,,,*,oo°,,,,, ..... ,,,o°,,,,,,oo,o,o,,,,,,.., .... ,oo°,,,,, ........... *...,,o 78

Clamped flex ................................................................................................................... 79

Clamped medium ............................................................................................................ 80

Clamped stiff

................... • ................ "*''''*'°°°**'*'°*'''''''''' .... * .... *°*°°°'**"'''''''''''',*,,,,*,,,,,,,,,,° 81

ix
LIST OF ACRONYMS

LaRC

LVDT

MSFC

NDE

TP

Langley Research Center

linear voltage displacement transducer

Marshall Space Flight Center

nondestructive evaluation

technical publication
TECHNICALPUBLICATION

A COMPARISON OF QUASI-STATIC INDENTATION TO LOW-VELOCITY IMPACT

1. INTRODUCTION

Low-velocity impact events are expected to occur during the manufacturing and service life of

composite parts and/or structures. Foreign body impact can occur during manufacturing, routine maintenance, or use of a laminated composite part. By dropping a 5-1b handtool less than 4 ft, an impact force

anywhere between 100 to 1,500 Ibf can occur, depending mainly on the transverse stiffness (flexural rigidity) of the impacted part at the site of the impact. Low-velocity impact events can occur during the service

life of a composite in such forms as hail, runway debris, and collisions with other vehicles or animals.

Impact events such as these can damage the integrity of the composite while leaving little or no visible

damage.

There are two very distinct aspects to consider when designing composite structures/components--

damage resistance and damage tolerance of composite materials. Damage resistance is the measure of a

material's ability to resist damage, while damage tolerance measures the ability of a structure/component

to carry service loads (or function as designed) with the presence of damage. Damage tolerance of carbon/

epoxy composites is a very important aspect in the design criteria of composite structures. This is due to

the relatively low strength of a carbon/epoxy laminate transverse to the fiber direction (through-the-thickness direction). The principal toad-carrying mechanism in this direction is the epoxy matrix. The primary

structural role of the matrix material is to provide stability to the fibers. During an impact event, the matrix

will fail first, causing microcracks within a layer (lamina) and then delamination between the lamina

layers. This can lead to the structure's inability to carry designed service loads, especially in compression.

This has led to much research on impact damage to laminated composite plates. Typically, laminated plates are impacted either by a "drop-weight" or "projectile" method. Drop-weight impacts usually

consist of an instrumented striker (tup) that is secured to a carriage that falls along guideposts and collides

with the plate. Projectile tests typically consist of firing a small spherical projectile at a composite plate

with the use of a light gas gun. After an impact event has been performed, ultrasonic c-scans, x-radiography, and cross-sectional photomicroscopy are some of the common techniques used to document the damage area. Postimpact strength testing (mostly compression) is often performed to evaluate a material's or

structure's damage tolerance.

It would be very beneficial to simulate an impact event using a "quasi-static" loading test. By using

this test, damage initiation and propagation can be more easily detected, deflection can be directly measured with great accuracy, and maximum transverse force can be better controlled. Thus, the focus of the

work in this technical publication (TP) was to examine if drop-weight impact tests and quasi-static loading

tests give the same size, shape, and location of damage for a given maximum transverse load.
In thepresentstudy,all testswereconductedonlaminatedplatesmadefromIM7/8552prepreg.

Theplatestestedwerequasi-isotropicwithastackingsequenceof [+45,90,-45,0]ns,withn equal to 1,2,4,

and 6. This is known as a r_/4 quasi-isotropic stacking sequence.
2. PREVIOUS WORK

2.1 Background

The need for a static (or more commonly referred to as quasi-static) test method for modeling lowvelocity foreign object impact events would prove to be very beneficial to researchers since much more

data can be obtained from a quasi-static test than from an impact test. An American Standard Testing

Materials standard has been proposed for transverse quasi-static loading of composite laminates, although

the standard stops short of claiming to represent low-velocity impacts. 1 Since a "low-velocity" impact

event lasts approximately 6-10 ms, there is debate as to whether or not a quasi-static indentation test truly

represents a low-velocity impact event.

The first order of business is to determine whether or not an impact event is considered low velocity and can thus be subjected to further analysis as a quasi-static event. It has been clearly shown that

projectile-type impacts in the ballistic range are governed by dynamic events and therefore could never be

represented by a quasi-static test. 2-4 Some research efforts have been focused on defining the boundary

between "low-velocity" and "dynamic" impact events. One study suggested that the impactor-to-target

frequency ratio governs the type of event with a low (much less than unity) ratio, implying a quasi-static

event. 5 A simpler method was obtained by Swanson 6 in which a rule has been established that if the

impactor mass is more than 10 times the "lumped mass" of the target, then the impact event will be quasistatic in nature. The "lumped mass" is a function of the target shape and boundary conditions but is generally about one-half the mass of the entire target. However, for most practical purposes, it is fairly clear if an

impact event is "low velocity" High-velocity/large-mass impacts are of little concern since the part will be

so heavily damaged by such an event that an analysis is not needed and conversely a low-velocity/lowmass impact is of little concern since no damage will form.

Once an impact event is deemed to be "low velocity," the question remains as to whether or not a

static indentation test can be performed that will duplicate certain aspects of the impact. Some of these

aspects include permanent indentation, maximum displacement, and most importantly, amount and type of

damage formed. All of these parameters must be compared against an independent variable that will be

common to both tests. It has been suggested that this independent variable be the maximum transverse

load.4,7, 8

Permanent indentation after an impact or quasi-static loading test has been examined in a few

studies.9-11 The one common feature in all of these studies is the large amount of scatter in indentation

depth data, to the point of rendering this measurement useless. Nevertheless, it was decided to examine this

parameter in this study to see how much scatter would exist.

For load/deflection correlation it is imperative to have an instrumented impact apparatus. The interpretation of the signals has been greatly simplified with the use of commercially available systems that

filter the load signals to reduce unwanted noise. Care must be taken to ensure that the filter being used does
notmaskimportant load events. A complete analysis of instrumented impact testing is beyond the scope of

this paper, but two excellent references are noted for the reader. 12,13

The amount of damage formed by an impact event can be measured in a number of ways. Destructively, the impacted specimen can be sectioned and examined under high magnification, or a residual

property can be measured (termed "damage tolerance"). Nondestructively, ultrasonic or x-radiography can

give a planar indication of the type and extent of damage. Ultimately, the amount of damage formed by an

impact event is the greatest concern to the engineer investigating such an occurrence, and since the

impacted part may still be useable, nondestructive techniques are preferred. Thus the major portion of this

paper will deal with the resulting damage as detected via nondestructive evaluation and whether or not the

damage formed for a given transverse load is similar in low-velocity impact and quasi-static testing. Specific studies that have examined this are featured in section 2.2.

2.2 Impact Versus Quasi-Static Testing

Several studies 4,7,9,14,15 show a similarity between quasi-static indentation and drop-weight

impact testing, while other studies 8,16,17 have shown a limit to the applicability of using quasi-static indentation to represent impact events. It must be noted that there are many variables involved in these tests such

as boundary conditions, specimen size, specimen thickness, stacking sequence, impactor size, impactor

shape, and type of fiber/resin system. The amount of impact damage formed in a laminated composite has

been shown to be very sensitive to stacking sequence, regardless of thickness. 18 As plies are grouped

together, larger areas of delaminations tend to form. It has been conventional wisdom in the aircraft industry to disperse the ply orientations in order to increase damage resistance. For example, a stacking

sequence of [+45,0,-45,9012s is preferable to one of [+452,02,_52,902] s in order to increase the damage

resistance of the laminate.

Jackson and Poe 4 used 48-ply specimens with dispersed plies (a layup of [45,0,-45,9016s) in order

to examine if a low-velocity impact event was similar to a quasi-static transverse loading event. The quasistatic indentation specimens were clamped over a 10.2-cm diameter circular opening and the impacted

specimens were clamped over a 12.7-cm-square opening. Although these two boundary conditions are

different, it was deemed not to be of a magnitude of difference to compare the delamination area of the

results. The support size-to-specimen thickness ratio was =20 for these tests, which indicates a stiff impact

target. For fiber/resin systems of both IM7/8551-7 and AS4/3506-6, no appreciable difference between

the damage diameters as seen by c-scans were evident between the quasi-static and impact tests. In these

tests, as a barely visible crater became more visible, the delamination results became more similar due to

the elimination of scatter.

Kwon and Sankar 7 used 24- and 32-ply laminates with dispersed plies supported over a 2-in.-

diameter circular opening. These specimens had an opening-to-thickness ratio of 17 and 12.5, respectively,

indicating very stiff impact targets. For a limited amount of data, the static indentation and impact tests

gave approximately the same delamination radius for a given transverse load.

Despite the title of a paper by Kaczmarek and Maison, 9 little information is obtained about damage

area versus transverse load for impact and static indentation testing. What little information is given indicates that static and low-velocity impact testing gave "good similarity" when based on damage area as
detectedby ultrasonicc-scans.Thespecimenswere16pliesthickwith doublegroupingsof all orientations.Thelayupsequencewas[452,02,-452,902]sandthespecimensweresupportedovera 12.5-by7.5-

cmopening.Thisgivesaspecimenopening-to-thicknessratioof'50, whichisof moderatestiffnessfor an

impacttarget.

LeeandZahuta14used16-plyquasi-isotropicpanelswithdispersedpliesclampedovera2.2-by5-

in.opening.Thisgivesaspecimensupport-to-thicknessratioof =45,whichindicatesamoderatelystiff to

stiff impacttarget.Thespecimenswerecomparedonadamagewidthratherthanonadamageareabasis.

Theresultsshowedagoodamountof scatterintheimpactresultswith thestaticindentationtestsyielding

aslightlyhigherdamagewidthforagiventransverseload.Onalostenergybasis,theresultsbetweenstatic

indentationandimpacttestinggavevastlydifferentresultswiththeimpacttestslosingmuchmoreenergy

for agivendamagesize.Thiswasattributedto vibrationsin thedrop-weightcrossheadabsorbingmuchof

theenergy.ThishasalsobeenaconcernforresearchersatNASAMarshallSpaceFlight Center(MSFC)

where"lost energy"is deemedadubiousresultatbest.19

In a studyat theUniversityof Dayton Research Institute 15 a comparison between low-velocity

impact and static indentation tests was based on load/deflection curves. The specimens were 48 plies thick

with dispersed plies simply supported over a 12.3-cm-diameter ring. This gives a specimen support-tothickness ratio of 20, which indicates a stiff target. The impact curve had the typical oscillations associated

with an impact event but the static indentation curve superimposed over the impact curve fairly well, with

incipient damage occurring at the same load and displacement for both. As far as damage is concerned,

some of the specimens were cross sectioned and examined under magnification. There was no apparent

difference in the type or extent of damage to the impacted specimens and the statically indented ones.

In a study at the Massachusetts Institute of Technology, 8 a slight difference in static indentation and

impact testing was found. This study used panels fabricated with 12 plies grouped in sets of two. The

panels were supported in a clamped-clamped/free-free configuration with a span of 25.2 cm and a width of

13 cm. These boundary conditions create a test specimen with a support size-to-thickness ratio of 170, a

much more flexible specimen than those examined in previous studies thus far. For a given transverse load,

the impacted panels showed more damage area as determined from x-ray analysis than the statically

indented specimens. Numbers are not given, but the differences are within =50 percent; not huge, but

different nonetheless. A plot of force versus deflection showed a vast (>100 percent) difference between

static indentation and impact testing. This study also examined sandwich panels and it was found that the

static indentation and impact tests were nearly identical. This was due to the extremely rigid support condition that a honeycomb panel gives its face sheets.

Elber 16 found some differences in maximum delamination length for a given transverse load

between low-velocity impact and static indentation. In this study, 8-ply quasi-isotropic plates supported

over a 2-in. circular opening were used. This gives a specimen support-to-thickness ratio of =50, which is

between a stiff and flexible impact target. Load/deflection data were given and the two match well. However, for a given transverse load, those that were loaded statically had consistently longer delaminations

than those that were impacted. This difference was between 15 and 40 percent for tests at four different

load levels.
Thelargestdifferencebetweenstaticindentationandimpacttestingin theliteraturesurveyedwas

foundby Highsmith.17This studyemployed20-plyspecimenswith alayupof [+_60,04,_+60,02]s supported over a 2.5-in.-diameter circular opening, which gives a specimen support to thickness ratio of =25,

representing a stiff target. Three different transverse load levels were selected and the resulting damage

was evaluated using x-ray techniques. The lowest load level chosen in this study was just at the point of

damage initiation; therefore, there is so much scatter in the data that a comparison cannot be made. At the

two higher load levels, the specimens that were impacted showed about half as much delamination area for

a given transverse load than the impacted specimens.

2.3 Conclusions From Past Studies

A summary of the results from past studies that compared quasi-static loading to impact loading

based on a given transverse load is given in table 1.

From the studies examined thus far, it appears that a quasi-static indentation test can be used to

simulate a low-velocity impact event in most cases; however, a more detailed study varying more parameters is needed. Most of the studies thus far have been on fairly stiff specimens. Larger ranges of stiffness

need to be tested to draw a conclusion. The one study that did show a large difference in delamination

area 17 has the most group plies with four zero-degree plies grouped together. It would be a rare case for an

actual engineering laminate to have this kind of grouping. Thus it will be the intent of this study to examine

laminates most commonly used in structures, those of the class [45,90,-45,0]nS.

Table 1. Conclusions from

Specimen

Support/

Thickness

Ratio1

9revious studies.

Reference Layup Conclusions

4 20 [45,0,-45,9016s No difference in c-scan diameter

14

15

16

17

12.5

5O

45

2O

170

5O

25

[0,45,90,-4514s

[0,22.5,45,67.5,--45,-22.512s

[452,02,-452,902]S

[45,0,-45,9012s

[0,45,-45,9016s

[-+452,02]s

[0,45,-45,90]s

17 [-+60, 04, _460,02]s

C-scanradiusapprox,sameforlimiteddata

C-scan area shows no difference. Very little

data

C-scan damage width showed static cases

slightly higher than impact

Load/deflection curves similar

Impact showed more damage from x rays--

load/deflection curves much different.

From x rays, static specimens had a

15 -40 percent longer delamination length

than impact specimens

Delaminationareasof staticspecimenstwice

aslargeasimpactspecimensasdetermined

fromx rays

Thehigherthenumber,themoreflexibletheplate.

6
3. EXPERIMENTAL PROCEDURE

3.1 Introduction

The intent of this study was to compare quasi-static indentation testing to drop-weight impact

testing based on the maximum transverse load. In order to ensure a complete analysis of the two events,

testing was divided into several different categories based on boundary conditions. These two categories

were then subdivided into three additional groups based on plate stiffness. To ensure the repeatability of the

experimental procedure, each impact test was performed on approximately four different specimens, while

the quasi-static indentation test was performed on two different specimens. A decision was made to repeat

the drop-weight impact testing numerous times because of the inherent data scatter. However, the repeatability became so constant during the latter stages of the testing that the number of impacted specimens for

repeatability assurance was reduced.

Finally, the rate of the quasi-static indentation test was also investigated to find if there was any

time dependency involved in quasi-static indentation testing. The two rates used were 0.05 in./min and

1 in./min.

3.2 Boundary Conditions

The two main categories of tests were dependent on the boundary conditions. Specimens were

either clamped on all four edges or simply supported on all four edges. For simplicity, the specimens that

were clamped on all four edges will be referred to as clamped and those simply supported on all four edges

will be referred to as simply supported for the remainder of this TP. This was done to determine if the

boundary conditions would have a major influence on the damage introduced for the same impact force.

Since an impact event does not always occur directly in the center of two ribs in a grid-stiffened aircraft

component nor on top of a rib, the boundary conditions will change. For example, if an impact event

occurred somewhere between the center point of a grid and on top of a rib, the actual boundary conditions

would be simulated more accurately in the lab as a combination of the clamped and simply supported.

To perform the simply supported test, the specimens were placed on the machined platen shown in

figure 1. The platen was machined from a 5.08-cm-thick (2-in.-thick) aluminum plate with an outside

square dimension of 40.64 cm (16 in.). A total of four platens were made with the square opening, N,

shown in figure 1, machined to 5.08 cm (2 in.), 60.96 cm (4 in.), 15.24 cm (6 in.), and 30.48 cm (12 in.).

This was done to explore the flexural/rigidity properties of the composite panels.

In order to perform the test with clamped boundary conditions, the platen in figure 1 was modified

as shown in figure 2. A series of 0.64-cm (0.25-in.) holes were drilled and tapped into the aluminum plate

3.81 cm (1.50 in.) from the edge of the opening. The bolt holes were spaced 2.54 cm (1 in.) on center. The

1.27-cm-thick (0.50-in.-thick) plate shown in figure 2 was machined from a steel plate with holes placed in

the same physical location as those in the platen.
The exterior dimension, M, in figure 2, was dependent on the opening size of the platen. For

example, the platen with the 15.24-cm (6-in.) opening required a steel plate with exterior dimension (M) of

25.4 cm (10 in.). The laminated composite panel was placed between the 5.08-cm-thick (2-in.-thick) aluminum platen and the 1.27-cm (0.5-in.) steel plate. Allen-head bolts were then used to secure the specimen

and a uniform torque of 5.65 J (50 in.-lbf) was applied to each bolt.

Figure 1. Test platen used for simply supported testing.

0.25-20 UNC

J _ A. _ 1.5 in. FromInternalEdge

___. ***__on Ceoter

Y __ /dI z'".

Figure 2. Modifications to test platen for clamped test.
3.3 Flexural Rigidity of Specimens

The three subgroups of tests involved the stiffness of the composite plate. It was decided that the

stiffness was a function of the support opening versus the laminate plate thickness. The specimens were

divided into three categories under this assumption: (1) Flex: ratio of 150, (2) medium: ratio of 50, and

(3) stiff: ratio of 25.

During an impact event, this flex/stiff characteristic changes the mode of damage propagation as

shown in figure 3. Figure 3 shows that for stiff laminates the contact forces caused the mode of failure,

while for flexible laminates the failure propagates from the side opposite the impact site. This was characteristic of the brittle properties of the matrix materials used in advanced composites.

StiffLaminate

,% /

1

I

FlexibleLaminate

Figure 3. Impactor/laminate failure mode.

3.4 Materials

The plates used for this study were manufactured from Hexcel TM IM7/8552 prepreg. The epoxy

resin, 8552, is a high-performance matrix that is used primarily in the aerospace industry for structural

components. It offers exceptional toughness and damage tolerance. IM7 is an intermediate modulus carbon

fiber with a tensile modulus of =27,580 MPa (40 msi). The manufacture's tensile strength and tensile

modulus values for a unidirectional laminate of this fiber/resin system are listed in table 2.

9
Table2.Materialproperties.

Manufacturer'sValue

Property MPa(ksi)

Tensilestrength 5,378 (780)

Tensilemodulus 27,580(40,000)

The quasi-isotropic laminated panels were layed up by hand, placed in a vacuum bag, and cured

using the manufacturer's cure cycle shown in figure 4. The panels were fabricated into 61 ×91.4 cm (24 ×36

in.) plates. In order to obtain a large variety of flexural stiffnesses of carbon/epoxy laminates, the following

four thicknesses were used: 8-, 16-, 32-, and 48-ply. The panels were fabricated utilizing the quasiisotropic rd4 stacking sequence of [+45,90,-45,0]ns, where n, was given the value of 1, 2, 4, and 6, respectfully.

Figure 5 is a schematic of an 8-ply laminate stacking sequence. From these panels, the test specimens were then machined into 10.16 cm (4 in.), 15.24 cm (6 in.), 20.32 cm (8 in.), and 35.56 cm (14 in.)

squares. Appendix A lists all specimens, layups, and sizes. The specimens were machined using a tungsten

carbide saw blade.

80psiThroughout Cycle

8O

,,o /

so

E -

E"

70

0 93 213 269

Time(min)

Figure 4. Typical cure cycle for IM7/8552 prepreg laminate.

10
+45

9O

--45

0

0

-45

9O

+45

Figure 5. Schematic of an 8-ply laminate stacking sequence.

3.5 Mathematical Foundation

The impact tester measures the initial velocity by an electronic trip placed as close as possible to the

surface of the impact specimen. By double-integrating the time versus load curve, deflection versus load

plot was calculated. Although the computer software (GRC 930-1) performed this evaluation, the actual

numbers were checked to ensure accuracy. The following equations were used:

where

d2x

F(t) = m dt--- T , (1)

F(t) is the force of the load cell (lbm*ft/sec 2)

m is the mass of the impactor (Ibm)

dZx/dt 2 is the acceleration (ft/sec2).

From eq. (1), velocity was calculated numerically using eq. (2):

V(t) = _m _ F(t)dt + co .

(2)

11
where

Usinginitialboundaryconditions:

att=O

co= Vo ,

V(t) is the velocity of the load cell (ft/sec)

co is a constant of integration

Vo is the initial velocity (ft/sec).

From eq. (2), deflection was calculated numerically using eq. (3):

where

(3)

X(t) is the transverse deflection of the load cell as a function of time.

These numerical integrations were performed using the software package Kaledigraph TM.

3.6 Impact Testing Procedure

The impact testing was performed at MSFC using a Dynatup 8200 drop-weight impact tester. The

specimens were placed on the platen shown in figures 1 and 2, depending on boundary conditions, with the

desired opening size (N). Table 3 lists the opening size used, dependent on the laminate plate thickness.

This divided the test into the proper flexural/rigidity ratio being examined.

Table 3. Opening and laminate thickness ratio calculations.

Flex:Ratioof150

LaminateThicknessOpeningSize(N)

NumberPlies mm(in.) mm(in.)

8 0.102(0.04) I52.4 (6)

I6 0.204(0.08) 304.8(12)

Medium:Ratioof50

8 0.102(0.04) 50.8 (2)

16 0.204(0.08) 101.6 (4)

48 6.096(0.24) 304.8(12)

Stiff:Ratioof25

16 0.204(0.08) 50.8 (2)

32 4.064(0.16) 101.6 (4)

48 6.096(0.24) 152.4 (6)

12
Specimens were then impacted with a hemispherical-tipped steel tup. The drop-height and mass of

the impactor was adjusted to give the desired damage mode. The damage desired was very little visual

damage to the top of the specimen while achieving a measurable crack on the bottom surface. This level of

damage was chosen since the onset of visual damage is such a critical state for an impact event. If penetration is allowed, boundary conditions and rate effects will not be as noticeable and if too low of an impact

level is used, damage may not form at all. Tables 4 and 5 list the height, maximum load, and mass for each

subgroup that was finally chosen before proceeding to the quasi-static indentation testing. Table 4 is for the

clamped boundary conditions and table 5 is for the simply supported boundary conditions. Appendix A has

a complete listing of the drop-height and maximum loads for each specimen tested.

Table 4. Maximum load and drop height for the clamped boundary conditions.

Clamped

Flex:Ratioo1150

Specimen MaximumImpactForce DropHeight

NumberPlies ID No. N (Ibf) cm (in.)

8

16

616-15f

616-04f

1,930 (434)

7,1o8(1,598)

30.48 (12)

121.92 (48)

Medium:Ratioof 50

8 728-11m 1,036 (233) 12.70 (5)

16 616-28m 3,728 (838) 35.56 (14)

48 61599-04m 26,823 (6,030) 119.38 (47)

Stiff:Ralio of25

16 616-32s 3,100 (697) 33.02 (13)

32 616-20s 7,268 (1,634) 71.12 (28)

48 727-05s 23,100 (5,193) 63.50 (25)

Table 5. Maximum load and drop height for the simply supported boundary conditions.

SimplySupported

Flex:Ratioo1150

Specimen MaximumImpactForce DropHeight

NumberPlies ID No. N tiM) cm (in.)

8

16

Medium:Ratioof 50

8

16

48

Stiff:Ratioof25

16

32

48

727-1 Of

728--06f

728-03m

727-11m

61599--02m

727-20s

727-18s

727-02s

1,873 (421)

5,400 (1,214)

974 (219)

3,728 (837)

23,562 (5,297)

2,922 (657)

9,853 (2,215)

22,121 (4,973)

44.45 (17.50)

148.6 (58.50)

5.72 i2.25)

49.53 (19.50)

119.38 (47.00)

52.71 (20.75)

124.46 (49.00)

63.18 (24.88)

13
Time versus load data were measured and collected using the software package GRC 930--I. Figure 6 shows a typical time versus load plot for an impact test. From this data the load displacement graphs

were calculated as discussed in section 3.5.

TypicalLoadVersusTime ImpactPlol

5OO

2

400

0.5

300

2OO

100 0.5

0 0

0 2 4 6 8 10

Time (msec)

Figure 6. Typical time versus load plot.

In order to achieve the desired impact force on the 48-ply specimens, two different load cells were

required. These specimens required an impact force >5,000 lbf; therefore, a 10,000-1bf load cell was used.

To ensure the compatibility of the load cells, four drop-weight impact tests were performed. Both loads'

cells were placed on the crosshead with an equal amount of weights placed at the same height, and then

composite panels were impacted to compare maximum loads. The results of these tests are tabulated in

table 6.

Table 6. 5,000- and 10,000-1b load cell comparison.

Specimen Initial Energy InitialVelocity MaximumLoad

ID No. J (ft-lb) M/sec(ft]sec) N (Ibf) LoadCell

614E-1

614E-2

614E-3

614E-4

15.89(11.72)

15.68(11.57)

15.82(11.67)

16.00(11.80)

4.3 (14.11)

4.27 (14.02)

4.29 (14.08)

4.32 (14.16)

5,449 (1,225)

5,453 (1,226)

5,351 (1,203)

5,63I (1,266)

10,000

10,000

5,000

5,000

From these data it was concluded that both load cells were properly calibrated and giving good

force values.

14
Figure 7 shows a typical load versus displacement plot. All load versus displacement plots for the

impact test can be found in appendix B.

m

v

o

..J

400

350

300

250

200

150

100

50

0

LoadVersusDeflectionSpecimen616-18f

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

1 III [llll_lllll III I_lllllllll [11111 I I I I It111-

1

8-Ply,6-in.Opening /"1

_ ClampedImpact /f t 1.4

1.2

1

¢1.

_ 0.6

0.4

0.2

Ilrj_,.._,.#'_ _, _ t l t. , _ I_ I , , , , I , , i _ 0

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Deflection(in.)

Figure 7. Typical load versus displacement plot for impact testing.

3.7 Static Indentation Testing Procedure

Once the impact testing was completed, the maximum impact force obtained for each of the different subgroups was used as the independent variable in the quasi-static indentation test. This was done

primarily due to the ease of reproducing this value on a servohydraulic test frame. However, it did not turn

out to be as easy as thought when the loading rate was increased to 1 in./min. Therefore, a small amount of

scatter was introduced into the experimental data from the beginning. The majority of the quasi-static

indentation tests were performed at NASA Langley Research Center (LaRC) on a 100-kip servohydraulic

load frame. Figure 8 shows the test fixture used for all of the quasi-static indentation tests performed at

LaRC. In order to perform a few tests at MSFC, a slight modification to the way the fixture was mounted in

the load frame had to be accomplished. The platen shown in figure 8 was the same platen used for the

impact test. For simplicity, the platen without the bolt holes is shown. The platen rested on top of the 5.08-

cm-thick (2-in.-thick) aluminum uprights and could be removed without taking the fixture out of the test

frame. The aluminum uprights were bolted to a 5.08-cm-thick (2-in.-thick) steel plate. The tang shown in

figure 8 was also machined out of steel and was bolted to the underside of the steel plate. The impactor was

placed in the upper crosshead of the servohydraulic load frame. In a limited number of tests, transverse

deflection of the center point of the laminate, directly under the hemispherical tup, was measured using a

linear voltage displacement transducer (LVDT). Figure 8 shows the location of the LVDT. The tests were

run in stroke control at the two different load rates previously mentioned.

15

m
..,,.._.----- With UpperHemispherical Steel Tang

Tipped Impactor

DT

ifPlate

Figure 8. Test fixture for quasi-static indentation testing.

Load and transverse deflection data were collected using the WIN5000 TM data acquisition system.

Although the quasi-static indentation tests were repeated, it was not repeated to the magnitude of the

impact testing. Each series of tests was performed twice. Since the dynamics of the quasi-static testing was

not an issue, this was assumed an adequate number to ensure repeatability. Figure 9 is a typical load

deflection plot for a quasi-static indentation test. Appendix C contains all of the load deflection plots from

the quasi-static indentation testing.

Load Versus Deflection Specimen 708-03m

Deflection (cm)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

1,000 | '' ,I .... t .... I .... i .... t .... t .... t, '- L

16-Ply, 4-in. Opening Clamped Static

Max Load = 827 Ibf - 4

800 Rate = 0.05 in./min ...,p.J 3.5

?

3 60O

__ /., 2.5g

400 j. ,,._' •

,,/ ./ 1.5

f.," ,.,...j"

200/ .,/ _1

0 _,I, ,_,,, _,, I, ,I,[J i 0

0 0.05 0.1 0.15

Deflection (in.)

Figure 9. Typical load versus displacement plot for quasi-static indentation testing.

16
3.8 Nondestructive Analysis

Once the impact and quasi-static testing were completed, the specimen underwent three types of

nondestructive analysis to document internal and external damage. These consisted of measuring dent

depth on the impacted surface, crack lengths on the nonimpacted surface, and internal damage as determined from x-radiography.

After the specimens were impacted or subjected to quasi-static indentation testing, they were set

aside for at least 24 hr so that the resulting dent would have time to relax to its equilibrium state. It was felt

that this would be appropriate since a postflight inspection would be performed at least 24 hr after a flight.

The dent depths were measured using a Starrett TM Model 644-441 dial depth gauge with an accuracy of

0.0254 mm (0.001 in.).

Any visible cracks on the nonimpacted surface of the specimens were measured.

After all the dent depths and crack lengths were measured, the specimens were then subjected to

radiographic techniques to document the internal damage areas. The specimens were soaked on both sides

with a zinc iodide penetrant solution for 24 hr and then x rayed using a Faxitron TM x-ray machine. A piece

of photographic film was placed directly under the specimen to capture the image of the internal damage in

the form of a negative. The exposure length and focal film distance was varied, depending on the specimens

being x rayed. For example, specimens 61599-02 through 61599-05 (48-ply specimens) were exposed at

35 kV for 2 min with a focal length of 46 in. While the specimens with identification numbers 616-20

through 616-24 (32-ply specimens) were exposed at 35 kV for 1 min 15 sec at a focal length of 46 in. From

the negatives, positives were made so that the planar damage area could be calculated. This was accomplished by superimposing a grid of 4 mm 2 (0.0062 in. 2) squares over the picture and then counting squares

that were within the damage area. Figure 10 illustrates the process used. The specimen shown in figure 10

was a 16-ply clamped impact specimen, 616-04f, supported over the 30.48-cm (12-in.) opening. From this

photo 192 squares were counted, which gives a planar delamination area of 768 mm 2 (1.19 in.2). It should

be noted that this is only a planar calculation and does not take into consideration the thickness of the

specimen. The strain gauge that appears in the bottom righthand corner of figure 10 was put on the specimen after it had been impacted so the x ray could be oriented with the specimen if needed.

The planar area of delamination was the most important variable used in this study and was the

main factor in determining if an impact event can be represented by a quasi-static indentation test.

, .. 7' r

i I ]'._Pk_,"12_L_i_'l_ t I il II I

: "' . , .1'1

] I I /t I [1,_, .... /' . .

"-"_° q [ I I i I I I i I I I I t t lmlhl'*l

Figure 10. X-ray of impact specimen with 4 mm 2 grid superimposed.

17
4. RESULTS AND DISCUSSION

4.1 Introduction

Since the main purpose of the research being presented was to establish if quasi-static indentation

testing was a true representation of a low-velocity impact event, this chapter will address this issue by

comparing the experimental results obtained in the low-velocity impact testing to that of the quasi-static

indentation testing. The impact testing will be discussed and then a comparison of the damage resistance of

the material subjected to the two different events will be presented. Tables 7 and 8 list the specimens and

the maximum loads used for comparison between impact and quasi-static testing. Once the specimens

were tested, comparisons were made on the dent depth, crack length, and delamination area. From these

comparisons, an understanding and analysis of the two types of testing procedures was achieved.

4.2 Drop-Weight Impact Testing

All of the load versus deflection plots for the drop-weight impact tests document the nonlinear

characteristics inherent to large deflection of plates. This can be seen in appendix B. This nonlinear characteristic behavior makes it very difficult to accurately predict mathematically how the material will behave

when subjected to a transverse load. For that reason, none of the classical laminate plate theories has been

introduced for comparison in this paper.

The impact duration versus stiffness ratio plots shown in figures 11 and 12 show that the stiffness

ratio has a direct effect on the duration of the impact. The impact duration increased as the stiffness ratio

increased (i.e., the specimen became more "flexible") for both boundary conditions. All stiffness ratios had

overlap in the duration of impact data and little difference can be noted between the two sets of boundary

conditions. It is apparent from the data that the duration of impact is dependent upon much more than

simply the support-to-thickness ratios of the plates, otherwise the data for ratios of 25, 50, and 150 would

be clustered together in well-defined groups. The only noticeable trend between the two boundary conditions occurs on the most flexible specimens with a stiffness ratio of 150. For these data, the simply supported boundary condition gives a slightly longer duration of impact than the clamped boundary condition

as long as all other parameters are held equal.

4.3 Quasi-Static Indentation Testing

Appendix C presents the load/deflection data generated for a limited number of the static indentation tests. The quasi-static test plots have very different behavior characteristics, depending on the stiffness

ratio. For clarification, specimens ending in "f" indicaie "flex" or a stiffness ratio of 150. Specimens ending in "m" indicate "medium" or a stiffness ratio of 50, and "s" indicates "stiff" or a stiffness ratio of 25.

For the "flex" specimens, the load/deflection curves demonstrate the extreme nonlinearity associated with large deflections of plates. The initial portion of the curve shows very little resistance to bending

as a small load causes a large amount of deflection. However, as the membrane stresses begin to dominate,

18
Table 7. Identification numbers and maximum loads for clamped specimens.

MaximumLoad

Typeof Event SpecimenID No. N (Ibf)

Flex:Supporl/ThicknessRatioof 150

8-ply, Impact 616-15f 1,930 (434)

6-in. opening Static0.05 in./min 708--10f 1,735 (390)

Static 1 in./min 720-08f 1,899 (427)

16-ply,

12-in.opening

Impact

Static0.05 in./min

Static1 in./min

Medium:Support/ThicknessRatioof50

8-ply,

2-in. opening

Impact

Static0.05 in./min

Static1 in./min

616--04f

720--04f

720-05f

728-1 lm

722-04m

722-05m

7,108 (1,598)

6,993 (1,572)

7,357 (1,654)

1,036 (233)

1,045 (235)

939 (211)

16-ply, Impact 616-28m 3,728 (838)

4-in. opening Static 0.05 in./min 708-02m 3,705 (833)

Static1 inJmin 720-06m 3,857 (867)

48-ply, Impact 616-04m 26,823 (6,030)

12-in.opening Static0.05 in./min 817-01m 26,293 (5,911)

Static1 in./min 818-02m 28,290 (6,360)

Stiff:Support/ThicknessRatioof 25

16-ply, Impact 616-32s 3,100 (697)

2-in. opening Static0.05 in./min 722-02s 2,918 (656)

Static1 in./min 722-08s 2,931 (659)

32-ply, Impact 616-20s 7,313 (1,644)

4-in. opening Static0.05 in./min 706-01s 7,455 (1,676)

Static1 in./min 708-07s 7,455 !1,676)

48-ply, Impact 727-05s 23,100 (5,193)

6-in. opening Static0.05 in./min 720-01s 23,429 (5,267)

Static1 in./min 817-03s 23,389 (5,258)

the amount of load needed to cause a given amount of deflection increases greatly. Little damage is noted

in these specimens until the maximum load is reached. This suggests a damage mode associated with large

bending stresses.

The "medium" specimens all show a "kink" in the initial loading portion of the load/deflection

curves associated with initial damage. Higher shear stresses are developed in the stiffer specimens, which

results in delamination-type failures within the laminate. The curves are seen to be slightly nonlinear until

the initial damage is formed, at which point the curves demonstrate more nonlinearity.

The "stiff" specimens also have the initial load drop along the loading curve, which appears to be of

a larger magnitude than in the "medium" specimens. This follows since the stiff specimens will develop

larger shear stresses which will release more energy when @lamination does occur. Also of note is the

change of stiffness at the very beginning of the load/deflection curve. This is associated with the contact

stresses between the impactor and the plate. As the impactor first touches the plate, it begins to "dent into"

the specimen, causing an indentation in the specimen. As the impactor goes deeper into the specimen, the

contact stresses are spread out and the impactor stops indenting into the specimen.

19
Table8.Identificationnumbersandmaximumloadsfor simplysupportedspecimens.

MaximumLoad

Typeof Event SpecimenID No. N (Ibf)

Flex:Support/ThicknessRatioof 150

8-ply, Impact 727-10f 1,873 (421)

6-in. opening Static 0.05 in./min 817-11f 1,859 (418)

Static1 in./min 817-04f 1,859 (418)

16-ply, Impact 728-06f 5,400 (1,214)

12-in.opening Static0.05 in./min 818-06f 5,458 (1,227)

Static1 in./min 818-04f 5,667 (1,270)

Medium:Support/'rhicknessRatioof 50

8-ply, Impact 728-03m 974 (219)

2-in. opening Static0.05 in./min 819-02m 907 (204)

Static1 in./min 819-08m 1,059 (238)

16-ply, Impact 727-12m 3,701 (832)

4-in. opening Static0.05 in./min 819--016m 3,677 (827)

Static1 inJmin 819-10m 3,777 (849)

48-ply, Impact 61599--02m 23,562 (5,297)

12-in.opening Static0.05 in./mln 818-07m 23,878 (5,368)

Static1 in.lrnin 818-02m 28,304 (6,363)

Stiff:Support/ThicknessRatioof 25

16-ply,

2-in. opening

32-ply,

4-in. opening

48-ply,

6-in. opening

Impact

Static0.05 in./min

Static1 in./min

Impact

Static0.05 in./min

Static1 in./min

Impact

Static0.05 in./min

Static1 in./min

727-20s

819--04s

819--06s

727-18s

819-14s

819-12s

727-02s

817-08s

817-06s

2,922 (657)

2,918 (656)

2,931 (656)

9,853 (2,215)

9,866 (2,218)

10,898 (2,450)

22,121 (4,973)

22,726 (5,109)

21,476 (4,828)

4.4 Nondestructive Analysis

As mentioned earlier, three different types of nondestructive analysis techniques were used. All

nondestructive evaluation (NDE) analysis results are tabulated in appendix D. Since visible damage that

occurs from an impact event is most easily measured, all analysis will be presented with the dent depth as

the independent variable.

When an impact event occurs to a laminated component, visual damage is not always apparent,

although there can be severe underlying damage. It has been proposed that if a correlation between the

measurable dent depth, usually the only visible damage, and underlying delamination or measurable crack

length on the nonimpacted surface, then a damage resistance concern could be easily addressed. For this

reason the dent depths were measured and documented for all specimens and used as the independent

variable for all subsequent comparisons.

2O
4.5 Crack Length

The specimens listed in tables 7 and 8 were used to generate the dent depth versus crack length

plots shown in figures 13 and 14. Figure 13 is for the clamped boundary condition and figure 14 is for the

simply supported boundary condition. For these two figures, a least-squares linear approximation was

performed to find if any linear correlation between the two variables was present.

In figure 14 the data represented by the open squares were not included for the least-squares linear

approximation. This was done because it fell outside of what was considered valid scatterbands. Equation

(4) is the calculated linear approximation:

C = -0.347 + 224d ,

(4)

where

C is the crack length (in.)

d is the dent depth (in.).

From eq. (4) when the crack length (C) was set equal to zero and the equation solved for the dent

depth (d), a value of 0.0015 in. was calculated. This would suggest that a carbon/epoxy structure/component could sustain a low-velocity impact event that produces a dent depth of 0.0015 in. and not have any

measurable crack length on the nonimpacted surface.

Equation (5) is the linear approximation, calculated using the least-squares approach, as performed

for figure 14:

C = -0.309 + 202d , (5)

where

C is the crack length (in.)

d is the dent depth (in.).

If the same analysis is performed on eq. (5) as performed on eq. (4), the value for the maximum

dent depth without cracking was calculated to be O.OO153 in.

Although the two equations are in general agreement, they do not take into account the stiffness

ratio of the composite plates. As previously mentioned, the stiffness ratio has a direct effect on the failure

mode of the composite plates. Therefore, a correlation needs to be found that is not as generalized as this

approach.

21
gl

O

o

.w

160

140

120

100

8O

60

4O

2O

2

,O, , ,OOL,,, i,,,

4 6 13

Impact Duralion (mac)

I n u r

10 12

Figure 11. Impact duration versus stiffness ratio for clamped boundary conditions.

g_

o

gtl

160

140

120

100

80

6o)

40

20 , ,e ,

4

• • •

i O , , , I , , , I , , , !

6 8 10 12

ImpactDuration(msec)

t t !

14

Figure 12. Impact duration versus stiffness ratio for simply supported boundary conditions.

22
3

.,,d

.ff

2

¢,J

DentDepth(mm)

0.5 1 1.5

......... , .......... , ........ 120

\

\

\

%

\

%

DXD

0 .... I .... I .... [ , , _ t I .... I ....

0 0.01 0.02 0.03 0.04 0.05 0.06

Dent Depth(in.)

100

8O

6O

4O

2O

EF

3

Figure 13. Crack length versus dent depth clamped boundary conditions.

.; 4

v

= 3

2

0 0.5 1 1.5

....... -- 'l ......... i ......... _ 150

w

O •

0 -, "w i ,i .... i .... i .... 60

0 0.01 0.02 0.03 0.04 0.05 0.06

loo _'

R.-

m

._=

3

80

DentDepth(in.)

Figure 14. Crack length versus dent depth simply supported boundary conditions.

23
4.6 Delamination Area

For the delamination area comparisons, the same analysis will be performed as in the case of the

crack lengths. Figures 15 and 16 are plots of delamination area versus dent depth for the clamped and

simply supported boundary conditions, respectfully. The least-squares linear approximations are presented

in eqs. (6) and (7); however, the physical interpretations of these equations take on a different approach.

10

8

i

.| 4

2

0

1.5

6,400

Dent Depth (mm)

0.5 1

i i I t i i i i i [ i i i i i i i i i [ i i i i t i i i i

-_Q• ' ' ' I

I _ _1 .... I L,,i, , , I .... I , I I ' ' ' I I

0.01

5,600

4,800 =m

4,000

3,200 _

2,400 _.

1,600

800

0

0 0.02 0.03 0.04 0.05 0.06

Dent Depth (in.)

Figure 15. Delamination area versus dent depth clamped boundary conditions.

A

N

,i

v

t_

Q)

Ig

O

,m

C

E

t_

O

Dent Depth (mm)

0 0.5 1

6

4

3

1

0 _ tit II I[ I IZ i I, ,, ,I, ,_ ,lI ,, ,

0

.5

1-

4,000

3,000

2,000

1,000

0

0.01 0.02 0.03 0.04 0.05 0.06

m

=!

m.

ml

_=-.

==

w

A

=1

Dent Depth (in.)

Figure 16. Delamination area versus dent depth simply supported boundary conditions.

24
Equation(6)is thelinearapproximationto thedatapresentedin figure 15:

A = 0.005 + 178d ,

(6)

where

A is the delamination area (in. 2)

d is the dent depth (in.).

Unlike the dent depth discussion, in order to understand the physical meaning, if there is any, of

eq. (6), the dent depth (d) was allowed to become zero. Doing this leads to a value of delamination area (A)

equal to 0.005 in 2.

Equation (7) for figure 16 is presented as:

A = 0.52 + 124d ,

(7)

where

A is the delamination area (in. 2)

d is the dent depth (in.).

Using the same analysis as performed on eq. (6), a delamination area of 0.52 in. 2 is found. This

value is extremely large compared to the value for eq. (6). One could argue that because of the simply

supported boundary conditions, this is possible. The simply supported boundary conditions allow for a

larger amount of flexure to the composite plate, which in turn would produce more internal stress, alluding

to large internal delaminations for the same applied load.

These data imply that after an impact event has occurred to a carbon/epoxy component/structure,

underlying damage can occur with no visual evidence. Again, this analysis is overly simplified and a more

indepth analysis needs to be found to better predict internal damage to laminated structures.

4.7 Comparison of Quasi-Static Indentation Testing and Drop-Weight Impact Testing

This section presents the main topic of this TP--"Does a statically applied transverse load yield the

same damage as a low-velocity impact load of the same magnitude?" Using damage area as detected by

x-ray analysis was deemed the most suitable method to do this since internal damage can be detected with

this method. Figures 17-24 present delamination area as a function of applied transverse load for both lowvelocity impacts and quasi-static loads of two rates. Each figure contains data for both clamped and simply

supported specimens to test Jackson's assertion 4 that the delamination area should be independent of this

parameter.

Figures 17 and 18 present data for the case of "flexible" laminates (support/thickness ratio of 150).

The open symbols represent the simply supported boundary condition.

25
1.2

": 0.8

v

M

g 0.6

E

_ 0.4

0.2

1,400

_r ImpactClamped

• 0.05 in./minClamped

• 1 in./min Clamped

_ ImpactS-S

0 0.05 in./min S-S

[] 1 in./min S-S

Load(N)

1,600 1,800 2,000 2,200 2,400

•r-T--F-r_---r , , , i: , _

..... • --..i ...............................

0 0

300 350 400 450 500 550

Load(Ibf)

6

m

5

_=_

4 --,

3

Figure 17. Delamination area versus maximum load for 8-ply specimens over 6-in. opening.

1,3

1.2

_" 1.1

4,500 5,000 5,500

l = , 'l ;i I t i J; I I ' '

• i i

ii • Impact clamped

• 0.05 in./min Clamped

• 1 in./min Clamped

_' Impact S-S

Load(N)

6,000 6,500 7,000

;'' = ' ';'' I ';'. ' '_;' ' '11

.................... "vv.....

........................... i]"'•-

7,500

8

7 -=

'0.1 _ 0.05 1 in./min in./minS-SS-S ......................... -0--; i .......... 3

6

i 0.9_........i.......... ,t7........i.......... _......... ,........ ......... ._

-- g. * ..................... L.O. ......i............................................ 5

m

,I i-i ........... ,........... i .......... , .......... 0.7 ........... -.......... i......

0.6 ........ i i .... i .... _ .... i .... i ....

1,000 1,100 1,200 1,300 1,400 1,500 1,600 1,700

Load(Ibf)

Figure 18. Delamination area versus maximum load for 16-ply specimens over 12-in. opening.

26
Figures 19-21 present data for the case of "medium" laminates (support/thickness ratio of 50). The

open symbols represent the simply supported boundary condition.

Load (N)

800 900 1,000 1,100 1,200

0.30 .... _ .... iI 'V' = ' ..... ' .... ''

,

• Impact Clamped

0.25 • 0.05 in./min Clamped .........................................

• 1 in./min Clamped

_ Impact S-S

0 0.05 in./min S-S 'i ...... ._r..., ............. ; ..........

[] 1 in./min S-S

........... _........ _............ i......... ._.......................

• :

,, v

0.10 ........................ i......................... i ............... • ......

0.05Q,, i,,, _,,,,, ,, i,,, i,,,

160 180 200 220 240 260

_a

'g 0.20

,Ic

¢¢

•-= 0.15

E

0

L

1.8

1.6

1.,

1.2 iS

1.0

m

0.8 a

0.6

1.4

28O

Load (Ibf)

Figure 19. Delamination area versus maximum load for 8-ply specimens over 2-in. opening.

.z

,wv

m

0.8

0.7

0.6

= 0.5

o

m

.E

E

0.4

0.3

0.2

65O

Load (N)

3,000 3,200 3,400 3,600 3,800 4,000 4,200

' I ' '; _ I ' ' 'z' I ' ' " I ' ' ':1 ' ' ' ' ' '

5

• Impact Clamped V

• 0.05 in./min Clamped ............................................... 4.5

• 1 in./min Clamped

ImpactS-S : Q_) : • •

(_ 0.05 in./min S-S ...... i ......... _.......................... 4 _"

............ r............. i...................... g..........

-v......._............ i.......... i._. ......i............ _..........

I "

...................... t............. t............. {............. :............ 2

/,,,,i,,,,, .... , .... , .... i, ,,, 1.5

700 750 800 850 900 950

m.

3.5

¢I

3 _

2.5

Load (Ibf)

Figure 20. Delamination area versus maximum load for 16-ply specimens over 4-in. opening.

27
A

._.R 5.5

v

,C

eo 5

E

-_ 4.5

6.5

6

........ 1--

4 ..... --(_-[-

3.5 ,,,I,

5,200 5,400

Load(N)

24,000 25,000 26,000 27,000 28,000 29,000 30,000

_ r v _ _ _ , , , _ r t_ r,_T | I _ ,t _ I _ _ _ I , ' ' I '

W

40

......i ............................ _. ....................................

:Y

........ J ......... J ......... J ......... • ......... J ...... i ......... • ........

"_ • ImpactClamped

• 0.05 in./min Clamped

• 1 in./min Clamped

_ ImpactS-S

(_ 0.05 in./min S-S

[] 1 in./min S-S

36

=-

==

32_

m

28 _'

24

i z I , , i I n i , I ...... l,,,l._

5,600 5,800 6,000 6,200 6,400 6,600 6,800

Load(lbf)

Figure 2 l. Delamination area versus maximum load for 48-ply specimens over 12-in. opening.

Figures 22-24 present data for the case of "stiff' laminates (support/thickness ratio of 25). The

open symbols represent the simply supported boundary condition•

1.6

1.4

1.2

|

__. 0.8

0.6

0.4

600

Load(N)

2,700 2,800 2,900 3,000 3,100 3,200 3,300

' I ' * _ t ' '_' ' I ' ,_ ' ' I n;n ' ' I',' ' ' ' I', .... ;I ' ' '

_r Impact Clamped _:

• 0.05 in./min Clamped ..........................................

10

9

• 1 in./min Clamped

_" Impact S-S .... 8 _

0.05 in./min S-S 'i ......... i......... i......... _........ _=_.

0

[] l inJminS-S i i i i 7 ._

........ :. ........ _......... +........ :......... _......... "......... -........

i i 1,; i

............ -.. ....... '..... "............ '-

............................ ==......... -_...................... _Jr:-.-; ........ 4

i , , i , _ _ I i , , o , z i J , i i I i , , I _ _'_

620 640 660 680 700 720 740 760

Load(Ibf)

Figure 22. Delamination area versus maximum load for 16-ply specimens over 2-in. opening.

28
Load(N)

7,500 8,000 8,500 9,000 9,500 10,000 10,500 11,000 11,500

2.6 _ , :

............ J............... JO........

_" 2.2

.mv

; 2

0

(O.E 18

E

o

1.6

• 1 in/min Clamped

_ ImpactS-S

C) 005 in/•in s-s

[] 1 in/min s-s ........... ............. _ ...............

14

3

0

12 _

3

................................ • V ......... _ ...........................

............................................................... ,o

1.4 _"II ........................ +................................................

12 __ , , , 8

1,600 1,800 2,000 2,200 2,400 2,600

Load(Ibl)

Figure 23. Delamination area versus maximum load for 32-ply specimens over 4-in. opening.

21,000

10 i _ I _'

9 • 0.05 in./minClamped

• 1 in./minClamped

V ImpactS-S

(_ 0.05 in./minS-S

[] 1 in./minS-S

v 8

.=

¢=

t=s

.5

E

e=

o

Load(N)

21,500 22,000 22,500 23,000 23,500

• v

6O

55

w

50 3

!

7 .......................... +............. +............. _.............. !............. 45

[] :: o oV v

6 .......................... _............. ,=.........................................

[] : 35

5 ........................... i........-V--i.............-.............................

• 30

4 , i i i J i i i i i i i I i i i , , + t i z i [ = z J I

4,700 4,800 4,900 5,000 5,100 5,200 5,300

eLI

40 '_"

Load(Ibf)

Figure 24. Delamination area versus maximum load for 48-ply specimens over 6-in. opening.

29
For the "flexible" laminates, there is no difference between the impacted specimens and those

tested quasi-statically at either rate. The effects of the boundary conditions show no difference for the 8-ply

specimens supported over the 6-in. opening, whereas a distinct difference is seen for the 16-ply specimens

supported over the 12-in. opening. This difference is due to the clamped specimens being loaded to a

higher level, resulting in a larger delamination area.

The "medium" specimens have no distinct trends between boundary conditions or rate of loading.

The impact test results fall in well with the static indentation tests in figures 19-21. Boundary conditions

also appear to have no effect on the maximum load versus delamination area.

Figures 22-24 represent the opposite extreme from the "flexible" specimens in that the contact

damage is the dominant failure mode. Again, there is no discernable difference between impact and static

indentation results. In figure 22, the simply supported specimens show slightly less damage for the same

magnitude of maximum load than the clamped specimens; however, this difference is slight.

Overall, the low-velocity impact tests can be represented by static indentation testing at rates of

0.05 and 1 in. per minute, regardless of specimen rigidity and boundary conditions. There is enough inherent scatter in both types of tests that all data fall within this scatter. It must be kept in mind that these results

are only valid for laminates of the rd4 type and laminates with different layups or clumped plies may yield

different results.

Another check of the validity of using static indentation tests to represent impact tests, a comparison of the load/deflection data, can be made.

Figures 25-31 show static indentation load/deflection data superimposed over impact load/

deflection data. The static data are represented by filled symbols, while the impact data are represented by

open symbols. Static load/deflection data were not available for all of the static tests since a faulty LVDT

was used; thus, only the valid data are presented.

On the loading portion of the curves, the data agree well. However, for the unloading portion of the

curves, the impact data consistently indicate that more energy was lost during the event since there is a

much larger hysteresis in the impact curves. However, from the delamination area data, it was anticipated

that the energy lost should be about the same. It has always been suspected that most of the energy lost in

this type of impact testing is lost due to vibrations within the impact apparatus, not in damage to the

specimen. When the falling crosshead and tup impact the composite plate, the head will tend to rebound at

an angle that is not parallel to the guideposts. Thus, a sideways force is exerted on the guideposts which

causes them to vibrate and interfere with the "natural" rebound of the impactor.

Figures 25, 27, and 30 represent this erroneous "loss of energy" data quite well. Figure 25 is a

flexible specimen and the loading portions of the curves agree well for both the static and impact cases.

However, for unloading, the impact data show a much larger deflection than the static data for a given load

on the rebound. Furthermore, the maximum displacement does not coincide with the maximum load, rather

it is seen to occur during the unloading portion of the curve and is quite a bit larger than the displacement

at the maximum load for two of the four impact specimens. Figures 27 and 30 also demonstrate this behavoir

and are data for medium and stiff plates, respectfully, so this phenomena is not a function of how rigid the

target is.

30
500

400

300

200

100

0

Deflection(cm)

0 0.2 0.4 0.6 0.8 1

_ 2,000

. Ilel__ v

: _m ...e_xj,l- _ V_- I

_ ," q, v6'

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Deflection(in.)

Figure 25. Static indentation data superimposed over impact data

for 8-ply clamped specimens over a 6-in. opening.

1,400

1,200

1,000

--_ 800

o

600

400

200

Deflection(cm)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Static1018-02 I

l

B Impact728-05 I _ z'_

Impact 728-06 I m

i i

0 0.1 0.2 0,3 0.4 0.5 0.6 0.7

i5,600

4,800

4,000

3,2O0

D.

2,400

1,600

800

Deflection(in.)

Figure 26. Static indentation data superimposed over impact data for 16-ply

simply supported specimens over a 12-in. opening.

31
Deflection(cm)

0.1 0.2 0.3 0.4 0.5

t,O00 .... i , 1--, , = , , , , i .... i .... 11

I A Static 708-02 4,OOO

,, • Static 708-03 ..iv ._

800 _-I41,Static 708-04 _lv, _ t

J-I • Static708-05 _1__'_ ]

I-I v Static708-06 e_ _ -4 3,000

j-] o Impact616-25 =dl_r_ Z _ {

_ 600L-I[] ,mpact616-26 1

I-I J_[<>z_ Impact Impact616-28 616-27 <p._t_ ooe._]_ __ _J_ 2,000 _.

0 0.05 0.1 0.15 0.2

Deflection(in.)

Figure 27. Static indentation data superimposed over impact data

for 16-ply clamped specimens over a 4-in. opening.

Deflection(cm)

0 0.2 0.4 0.6

7,000 30,000

6,000

25,000

5,000

20,000

4,000 Z.

15,ooo

3,000

IO,000

2,000

1,000 5,000

0 0

0 0.1 0.2 0.3 0.4 0.5 0.6

Deflection(in.)

Figure 28. Static indentation data superimposed over impact data

for 48-ply clamped specimens over a 12-in. opening.

32
Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

• Static 1015-02 25,000

[] Impact727-04

5,000 o Impact 727-05

-4°°° I t'°°°°

15,000

3,000

2,000 i n_e_/_300 z;_u °° eeo°" / -_10,000

1,000 ..../ • o°°°- j,ooo

1(3o° _o •

0 0

0 0.05 0.1 0.15 0.2 0.25 0.3

Deflection(in.)

Figure 29. Static indentation data superimposed over impact data

for 48-ply clamped specimens over a 6-in. opening.

0

1,750

1,500

1,250

__ 1,000

c_

o

•_ 750

5OO

25O

Oq

0

Figure 30.

Deflection(cm)

0.05 0.1 0.15 0.2 0.25 0.3 0.35

o°°

#

_,uog ,L nle J • Static706-01

I "_1 _ VAa' liP" _ Static 708-07

p_&_l,_l • _ Static708-08 o Impact616-20

[] Impact 616-21

x7 Impact616-22

_> Impact616-24

, , , ] ,-,-;-i , ,_-1 , , , i , , , i , " " ; 7 " " ; " "

0.02 0.04 0.06 0.08 0.1 0.12 0.14

0.4

, 8,000

7,000

6,000

5,000

4,000 _"

-- 3,ooo

2,000

1,000

0

]

0.16

Deflection(in.)

Static indentation data superimposed over impact data

for 32-ply clamped specimens over a 4-in. opening.

33
A

m

O

..I

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5 0.6

2,500

10,000

2,000

8,000

1,500

6,000 _--

1,ooo 4,000

500 2,000

0 0

0 0.05 0.1 0.15 0.2 0.25

Deflection(in.)

Figure 31. Static indentation data superimposed over impact data

for 32-ply simply supported specimens over a 4-in.opening.

An argument may be made that this is due to the inertial effects of the plate, that after the "collision" of the impactor and plate, the plate continues to move downward due to its own inertia. This argument would indicate that heavier plates would show more difference in load/deflection data for static

indentation and impact since heavier plates will have more inertia. However, figure 29 is a 48-ply plate

over a 6-in. opening whereas figure 25 is an 8-ply plate over the same size opening, yet the lighter plate

shows more of a difference.

Figure 26 does not have unloading data for the static case, but the loading portions of the curves

agree quite well.

Figure 28 is unique in that during the static indentation test, the maximum load, as determined from

the impact tests, could not be reached since the impactor began penetrating through the plate before this

load was obtained.

34
5. CONCLUSIONS

Major conclusions of this study are as follows:

° Static indentation tests can be used to represent low-velocity impact events when the damage is

compared by maximum transverse force. This is true of plates that experience flexural-type

damage, contact-type damage, and a combination of the two. Layups other than those of the rd4

type may not yield these same results.

2. Duration of an impact event is dependent upon the transverse stiffness of the plate. The stiffer the

plate, the shorter the duration of impact. Boundary conditions have little effect on this behavior.

° Much nonlinear behavior is observed in the load/deflection curves for flexible laminates. As the

laminate becomes stiffer, more linearity is seen and a distinct drop in load due to delamination

becomes more pronounced.

4. Load/deflection plots of static indentation and low-velocity impact are similar.

5. Dent depth results produce a great deal of scatter, which makes any conclusions concerning this

parameter difficult.

35

APPENDEX AmIMPACT SPECIMEN IDENTIFICATION NUMBERS

Tables 9-14 show clamped and simply supported data for impact specimens.

Table 9. Clamped flex.

S Plyon6-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (Ibf) J (ft-lbf) m/sec(ft/sec) cm (in.)

616-15f

616-16f

616-17f

616-18f

Specimen

ID No.

616-01f

616-02f

616-03f

616-04f

30(12)

25(10)

15 (6)

15 (6)

1,930(434)

2,148 (483)

1,673(376)

1,668(375)

7.5 (5.6)

6.4 (4.7)

3.7 (2.8)

3.8 (2.8)

2.42(7.95)

2.22(7.29)

1.71 (5.60)

1.71 (5.60)

No data

0.90 (0.35)

0.76(0.30)

0.78(0.31)

Drop

Height

cm(in.)

122 (48)

122 (48)

122 (48)

122 (48)

16Plyon 12-in. Platen

Maximum

Load

N (Ibf)

6,841 (1,536)

6,921 (1,556)

7,037 (1,582)

7,108 (1,598)

Impact

Energy

J (ft-lbf)

30.1 (22.2)

29.7 (30.1)

30.3 (22.3)

30.3 (22.3)

Impact

Velocity

m/sec(fl/sec)

4.86 (15.94)

4.82 (15.81)

4.86 (15.96)

4.87 (15.97)

Maximum

Deflection

cm(in.)

1.49 (0.59)

1.49 (0.59)

1.47 (0.58)

1.44 (0.57)

37
Table 10. Clamped medium.

8 Plyon2-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (ibf) J (ft-lbf) m/sec(fl]sec) cm (in.)

616-37m

616-38m

728-09m

728-11m

12.7 (5)

12.7 (5)

12.7 (5)

12.7 (5)

1,045 (235)

939 (211)

936 (210)

1,036 (233)

3.3 (2.4)

2.3 (1.7)

3.0 (2.2)

2.9 (2.1)

2.10 (6.89)

1.76 (5.78)

1.61 (5.28)

1.57 (5.14)

0.31 (0.12)

No data

No data

0.46 (0.18)

16 Plyon4-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (Ibf) J (ft-lbf) m/sec(ft/sec) cm (in.)

616-25m

616-26m

616-27m

616-28m

35.6 (14)

35.6 (14)

35.6 (14)

35.6 (14)

3,634 (817)

3,629(816)

3,665(824)

3,728(838)

8.6 (6.4)

8.7 (6.4)

8.7 (6.4)

8.g (6.5)

2.61 (8.55)

2.6t (8.57)

2.61 (8.55)

2.60 (8.53)

0.48 (0.19)

0.48 (0.19)

0.48 (0.19)

0.48 (0.19)

48 Plyon 12-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

IDNo. cm (in.) N (Ibf) J (ft-lbf) m/sec (ft/sec) cm (in.)

61599-04m

61599-05m

119(47)

119(47)

26,823 (6,030)

23,420 (5,265)

155(115)

157(115)

4.71 (15.46)

4.73 (15.52)

1.26 (0.50)

1.17 (0.46)

38
Table 11. Clamped stiff.

16 Plyon 2-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (Ibf) J (ft-lbf) m/sec(ft/sec) cm (in.)

616-29s

616-30s

616-31s

616-32s

34.3 (13.5)

26.7 (10.5)

33.0 (13.0)

-33.0(13.0)

3,239 (728)

2,922 (657)

3,105(698)

3,100 (697)

8.4(6.2)

6.4(4.7)

8.1(6.0)

8.0(5.9)

2.57 (8.43)

2.23 (7.33)

2.52 (8.27)

2.51 (8.24)

0.43 (0.17)

0.34 (0.13)

0.42 (0.17)

0.41 (0.16)

32 Plyon4-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

IDNo. cm (in.) N (Ibf) J (ft-lbf) m/sec(ft]sec) cm(in.)

616-20s

616-21s

616-22s

616-24s

71.1 (28)

71.1 (28)

71.1 (28)

71.1 (28)

7,313 (1,644)

7,268 (1,634)

7,544 (1,696)

7,322 (1,646)

17.2 (12.7)

17.4 (12.8)

17.1 (12.6)

17.5 (12.9)

3.67(12.05)

3.69(12.12)

3.66 (12.00)

3.70(12.14)

0.38 (0.15)

0.39 (0.15)

0.38 (0.15)

No Data

48 Plyon 6-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (Ibf) J (ft-lhf) m/sec(ft]sec) cm (in.)

727-04s 63.5 (25) 22,788 (5,123) 80.7 (59.5) 3.40 (11.15) 0.65 (0.26)

727-05s 63.5 (25) 23,100 (5,193) 80.7 (59.5) 3.40 (11.15) 0.64 (0.25)

Table 12. Simply supported flex.

8 Plyon 6-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (Ibf) J (fl-lbf) m/sec (lt/aec) cm (in.)

,,J ....

727-06f

727-07f

727-08f

727-09f

727-10f

44.4 (17.5)

44.4 (17.5)

44.4 (17.5)

44.4 (17.5)

44.4 (17.5)

1,850(416)

1,766(397)

1,850(416)

1,873(421)

1,873(421)

10.2(7.5)

9.6(7.1)

10.2(7.5)

10.1(7.5)

9.7(7.1)

2.9(9.6)

2.9(9.3)

2.9(9.6)

2.9(9.6)

2.9(9.4)

No data

1.18 (0.47)

1.23 (0.48)

1.34 (0.53)

1.24 (0.49)

16 Plyon12-1n.Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

IDNo. cm(in.) N (Ibf) J (fl-lbf) m/aec(ft/sec) cm (in.)

728-05f 132 (52.0) 4,862 (1,093) 29.7 (21.9) 4.8 (15.8) 1.61 (0.63)

728-06f 149 (58.5) 5,400 (1,214)" 32.2 (23.8) 5.0 (16.5) 1.64 (0.64)

728-07f 149 (58.5) 5,373(1,208) 31.6 (23.3) 5.0 (16.3) Nodata

39
Specimen

ID No.

728--02m

728-03m

728-(Hm

Specimen

ID No.

727-11m

727-12m

727-13m

727-14m

727-15m

Specimen

ID No.

61599-02m

61599-03m

Table 13. Simply supported medium.

8 Plyon 2-in. Platen

Drop

Height

cm (in.)

7.6 (3.0)

5.7 (2.3)

4.5 (1.8)

Maximum

Load

H (Ibf)

1,023(230)

974 (219)

907 (204)

Impact

Energy

J (fl-lbq

1.8(1.3)

1.3(0.9)

1.1(0.8)

Impact

Velocity

m/sec (It/see)

1.23 (4.04)

1.03 (3.38)

0.96 (3.16)

16 Plyon 4-in. Platen

Drop

Heighl

cm (in.)

49.5 (19.5)

46.4 (18.3)

39.4 (15.5)

24.1 (9.5)

24.1 (9.5)

Maximum

Load

N (Ibf)

3,723(837)

3,701(832)

3,670(825)

2,998(674)

2,963(666)

Impact

Energy

J (n-lbt)

11.9 (8.8)

10.6 (7.8)

8.3 (6.1)

5.6 (4.1)

5.3 (3.9)

Impact

Velocity

m/sec (ft/sec)

3.18 (10.43)

2.30 (9.83)

2.65 (8.71)

2.18 (7.15)

2.13 (6.99)

48 Plyon 12-in. Platen

Drop

Height

cm (in.)

119 (47)

119 (47)

Maximum

Load

N (Ibf)

23,562 (5,297)

29,492 (6,630)

Impact

Energy

J (fl-lbf)

158 (116)

159 (116)

Impact

Velocity

m/sec(ft]sec)

4.75 (15.57)

4.75 (15.58)

Maximum

Deflection

cm (in.)

0.29 (0.11)

0.23 (0.09)

No data

Maximum

Deflection

cm (in.)

0.63 (0.25)

0.58 (0.23)

o.52(o.2o)

0.44 (0.17)

0.34 (0.17)

Maximum

Deflection

cm (in.)

1.42 (0.56)

1.42 (0.56)

40
Table 14. Simply supported stiff.

16 Plyon2-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (Ibf) J (fl-lbf) m/sec (ft]sec) cm(in.)

727-20s

727-21s

727-22s

728-01s

52.7(20.8)

20.3 (8.0)

16.5 (6.5)

16.5 (6.5)

2,922 (657)

2,771 (623)

3,350 (753)

3,051 (686)

4.5 (3.3)

4.5 (3.3)

3.9 (2.8)

3.9 (2.9)

1.95(6.40)

1.96(6.42)

1.81(5.95)

1.82(5.97)

0.28 (0.11)

0.28 (0.11)

0.27 (0.11)

0.27 (0.10)

32 Plyon 4-in. Plalen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm (in.) N (Ibt) J (ft-lbt) m/sec(ft/sec) cm (in.)

727-16s

727-17s

727-18s

727-19s

104 (41.0)

112(44.3)

125(49.0)

125(49.0)

8,696 (1,955)

9,101 (2,047)

9,853 (2,215)

9,346(2,101)

22.2 (12.7)

24.0 (12.8)

27.1 (12.6)

24.1 (12.9)

4.35 (14.27)

4.52 (14.82)

4.80 (15.74)

4.53 (14.86)

0.46 (0.18)

0.48 (0.19)

0.51 (0.20)

0.48 (0.19)

48 P.!.y..on.6-in. Platen

Drop Maximum Impact Impact Maximum

Specimen Height Load Energy Velocity Deflection

ID No. cm(in.) N (Ihf) J (fl-lbf) m/sec (ft]sec) cm(in.)

727-02s 63.2 (24.9) 22,121 (4,973) 79.2 (58.4) 3.36 (11.04) 0.70 (0.27)

727-03s 63.2 (24.9) 22,810 (5,128) 82.6 (60.9) 3.39 (11.12) Nodata

41
APPENDIX BmLOAD VERSUS DEFLECTION PLOTS FOR IMPACT SPECIMENS

Impact specimen load versus deflection plots are displayed in figures 32-82.

Deflection(cm)

R

500

400

300

200

100

0 0.2 0.4 0.6 0.8 1 1.2

8-Ply, 6-in. Opening 2

Simply SupportedImpact Idl

'_, I, i i _ I i,,, I, I i I I I , , , 0

0 0.1 0.2 0.3 0.4 0.5

1.5

0.5

Deflection(in,)

o,

c_.

Z

v

Figure 32. Load versus deflection specimen 727-06f.

i

v

O

4OO

35O

3OO

25O

2OO

150

IO0

5O

0

0

Deflection(cm)

0.2 0.4 0.6 0.8 1 1.2

''' '"' '''' "'' "'' " '^'t.l,..,

- 8-Ply,6-in. Opening _ lVlJ'] 1.6

i Simply SupportedImpact ,p), T_,. _ 1.4

1.2

1

0.8

0.6

0.4

0.2

0

0.1 0.2 0.3 0.4 0.5

Deflection(in.)

Figure 33. Load versus deflection specimen 727-07f.

o

c3.

Z

42
Deflection(cm)

400

300

200

100

0

0 0.2 0.4 0.6 0.8 1 1.2

_,l i1 , i, it, ii i ii II I, It IJ Ig I ,

- 8-Ply,6-in. Opening LIII

i SimplySupportedImpact =.=Jl'_

I'%l,llri _ i I I I I I !/i i i I I I I I I I I I i I i

0 0.1 0.2 0.3 0.4 0.5

Deflection(in.)

Figure 34. Load versus deflection specimen 727-08f.

1.5

E

_ I

0.5

0

400

300

$

v

"11

-. 2OO

.--I

100

Deflection(cm)

0 0.2 0.4 0.6 0.8 1 1.2

-, i I I i I I I I i i I I I I I I I I I I I I I

- 8-Ply,6-in. Opening . X

Simply SupportedImpact _ _l_t

i_ll_ i I I I i I 1 .,Jill t I I I I I I I I i I i 1

0 0.1 02 02 0.4 0.5

Deflection(in.)

' 2

1.5

0.5

Figure 35. Load versus deflection specimen 727-09f.

f,-.

g

¢1.

A

.!

43
m

400

3OO

20O

100

Deflection(cm)

0 0.2 0.4 0.6 0.8 1 1.2

-t I I I ,I s I I I I I I I _ I I I I I I I i I I

8-Ply,6-in. Opening

SimplySupportedImpact ,/,,v%,/lllltq

r,,Iz,,ar,=,-_._li i i _-.,i'_'F-i i i I i i , , I i i , L

0.1 0.2 0.3 0.4

Deflection(in.)

0

0.5

1.5

o

w

Z

0.5

Figure 36. Load versus deflection specimen 727-10f.

0

1,200

1,000

800

m

v

•= 600

400

200

Deflection(cm)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

16-Ply,12-in. Opening .t_ -

Simply SupportedImpact _ _.

4

3

2

1

__ l , i I I I#l I I I I , , I I I I I J 0

0.1 0.2 0.3 0.4 0.5 0.6 0.7

Deflection(in.)

Figure 37. Load versus deflection specimen 728-05f.

cI,

Z

44
0

1,400

1,200

1,000

8oo

o 600

400

2OO

0

0

Deflection(cm)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

_li,lll il li,l,i, I , Ill II'I '''I' i'l'I

- 16-Ply,12-in.Opening

SimplySupportedImpact

I

0.1 0.2 0.3 0.4 0.5 0.6

Deflection(in.)

-'6

5

2

-1

, 0

0.7

Figure 38. Load versus deflection specimen 728-06f.

4

i-=

O

W

3

250

200

b

"= 150

D

,--I

100

5O

Deflection(cm)

0 0.05 0.1 0.15 0.2 0.25 0.3

-, ISll i''' IIii_l 'U'il Im''II_'=-f 1.2

8-Ply,2-in.Opening

Simply SupportedImpact _ _ 1

0.4

" 0.2

" i I i I i i i I i _ I_lr'l I I i i _ I i i i 0

0 0.02 0.04 0.06 0.08 0.1 0.12

Deflection(in.)

Figure 39. Load versus deflection specimen 728-02m.

0.8

r'-

g

0.6 _a"

45
0

25O

200

,-.. 150

o 100

50

Deflection(cm)

0.05 0.1 0.15 0.2

I J I I II I I I I _ I I I I_ I J I II I i I

8-Ply,2-in. Opening

Simply Suppoded Impact _

i J I I i i I _l i I i i i I t i i

0.02 0.04 0.06 0.08

0

0 0.1

Deflection(in.)

Figure 40. Load versus deflection specimen 728-03m.

0.8

r0.6

Z

0.4

0.2

2OO

150

v

100

,,--I

5O

Deflection(cm)

0 0.05 0.I 0.15 0.2 0.25

,.-_ n _ I I t t J I 1 I I I I I I I I I I _ i J l

8-Ply,2-in. Opening ..,,_

SimplySuppoSedImpact _ ]

MaxLoa 

, I l I J t- I I I i 0

0 0.02 0.04 0.06 0.08 0.1

Deflection(in.)

Figure 41. Load versus deflection specimen 728-04m.

0.8

0.6

0.4 _

0.2

46
Deflection(cm)

800

600

o 400

200

0.08 0.16 0.24 0.32 0.4 0.48 0.56 0.64

'' 'I' ' ' I' ' ' I'''I '''I'''I'' ' I'' ' I-

- 4

16-Ply,4-in. Opening

Simply SupportedImpact _ ...

MaxLoad = 837 Ibf

_..i="P'_ , l l [ J,_ * l , i i J l

0.05 0.1 0,15 0.2 0.25

3.5

2.5

2

z

v

1.5

0.5

Deflection(in.)

Figure 42. Load versus deflection specimen 727-11 m.

Deflection(cm)

8OO

600

ml= 400

2O0

0.1 0.2 0,3 0.4 0.5

,,ll I,ti,l, ,I ,I J, ,,lilllltill t

16-Ply,4-in. Opening

SMmjIJoSdPP°rted Impact _""_ i

0.05 0.1 0.15 0.2

0.6

i_ 4

3.5

2.5

a.

2

1.5

0.5

t 0

0.25

Deflection(in.)

Figure 43. Load versus deflection specimen 727-12m.

4?
v

-J

1,000

80O

600

Deflection(cm)

400

200

0 0.1 0.2 0.3 0.4 0.5

16-Ply,4-in. Opening

SimplySupportedimpact

MaxLoad

L

i_l, l I j L..a_P_[ ] j ] t I i , , , _] , , ,

0 0.05 0.1 0.15 0.2

0.6

i_-

4

3.5

3

2.5 .=,

m=

2 Z

1.5

1

0.5

' 0

0.25

Deflection(in.)

Figure 44. Load versus deflection specimen 727-13m.

700

600

500

.= 400

Ill

o, 300

200

100

Deflection(cm)

0.1 0.2 0.3 0.4

i J l i I i i J i I _ I J i l J t i I I _ L I

16-Ply,4-in. Opening ,,,_

Simply SupportedImpact / v]w

Max

-_J , l._==-t , l t ,,, , , , I , , ,

0 0.05 0.1 0.15

Deflection(in.)

0.5

_ 1- 3

- 2.5

1

0.5

0

0.2

2

¢D

1.5

Z

Figure 45. Load versus deflection specimen 727-14m.

48
700

600

500

_- 400

o

300

2O0

100

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5

-* I I t I n * I I I I I I I I u I I I I I I I I"

16-Ply,4-in. Opening _, 2.8

SimplySupported Impact _l_j I

- 2.4

0.8

0.4

_, jr, , I _ i , , I , i , , I , , l , 0

0 0.05 0.1 0.15 0.2

Deflection(in.)

Figure 46. Load versus deflection specimen 727-15m.

3.2

2

i=-

o

W

1.6 a.

A

v

1.2

6,000

5,000

4,000

m

"= 3,000

,.J

2,000

1.5

I-

- 25

Deflection(cm)

0.5 1

I I I I I I I I ! I I ! I I I I I t I I I I I I I I I I I

48-Ply,12-in. Opening

Simply SupportedImpact _ A

MaxLoad = 5,266 ,bf / t/ _

t 1 L I 1 1 I I [ I I_1 ,

0.1 0.2 0.3 0.4 0.5

1,000

0 0

0 0.6

Deflection(in.)

2O

,=,

=i,

15 A

10

Figure 47. Load versus deflection specimen 61599-02m.

49
Deflection(cm)

7,000

6,000

5,000

_. 4,000

o

"J 3,000

2,000

1,000

0 0.5 1 1.5

4

0 , 0

0 0.6

48-Ply,12-in. Opening

SimplySupportedImpact

_ Max Load= 6,630 Ibf

0.1 0.2 0.3 0.4

Deflection(in.)

28

24

20 r--

O

e_

cs.

16

12

Figure 48. Load versus deflection specimen 61599-03m.

7OO

600

500

=. 400

m

0

_ 300

200

100

Deflection(cm)

0 0.02 0.04 0.06 0.08 0.1

0.8

0.4

0

0.12

Deflection(in.)

Figure 49. Load versus deflection specimen 727-20s.

50
.=,

v

0

,,,=l

70O

60O

5O0

4OO

300

2OO

IO0

0

Deflection(cm)

0 0.05 0.1 0.15 0.2 0.25

.ill Jl Jllilillllllill llttllfll

,',

MaxLoad = 62_ _

0.02 0.04 0.06 0.08 0.1

0.3

"£3

2.5

2

0

m

-1.5 _="

Pzt

1

0.5

' 0

0.12

Deflection(in.)

Figure 50. Load versus deflection specimen 727-21 s.

Deflection(cm)

700

600

500

400

3OO

2OO

IO0

0

0 0.05 0.1 0.15 0.2 0.25 0.3

800-I, I I I I I, I I I I I I I a u I I'l I I I I I I I I I I" 3.5

16-Ply,2-in. Opening |

SimplySupportedImpact it]l

-- Max Load =753 Ibf /P'_' _1_ 3

/ v# ,.2

1.5

1

0.5

,,1,., I 0

0 0.02 0.04 0.06 0.08 0.1 0.12

Deflection(in.)

Figure 51. Load versus deflection specimen 727-22s.

51
700

60O

500

=. 400

O

300

200

100

Deflection(cm)

0 0.05 0.1 0.15 0.2 0.25

Illlll I,IlIJllllllllJIJIlllll

- 16-Ply,2-in. Opening ,_, __

_ J I l I _.#dr t j i [ i I i i i i i

0 0.02 0.04 0.06 0.08 0.1

Deflection(in.)

0.3

r 3.2

2.8

2.4

-- 2 to

==.

1.6_

1.2

0.8

0.4

I 0

0.I2

Figure 52. Load versus deflection specimen 728-01s.

Deflection(cm)

2,000

1,500

"U

1,000

5OO

0

0

0 0.1 0.2 0.3 0.4

r J i l t I i i l i I t i j I I _ i l i I i ,

32-Ply,4-in. Opening

Simply SupportedImpact

MaxLoad

-- ,.Z"N.j

0.1 0.2 0.3

Deflection(in.)

0.5

• 10

8

6 r-

.=,

=l.

Z

4 v

2

,io

0.4

Figure 53. Load versus deflection specimen 727-16s.

52
2,500

2,000

1,500

.=

"J 1,000

5OO

Deflection(cm)

0.1 0.2 0.3 0.4

32-Ply,4-in. Opening

Simply SupportedImpact

Max Load= 2,047 Ibf

0.05 0.1 0.15

0.5

0

0 0.2

Deflection(in.)

Figure 54. Load versus deflection specimen 727-17s.

10

r--

6 g

el.

A

4

2,500

2,000

A 1,500

0

1,000

5OO

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5

32-Ply,4-in. Opening

SimplySupportedImpact _

Max Load= 2,215Ibf _}

', , , ] I .J..=_-, [ I , i i ] I i , , , I

0 0.05 0.1 0.15 0.2

0.6

I2

I[ll 0

0.25

Deflection(in.)

Figure 55. Load versus deflection specimen 727-18s.

10

r'-

o

6 =

gl.

Z

v

4

53
Deflection(cm)

0

2,500

2,000

1,500

.¢D

Q

1,000

5OO

0

0 0.05 0.1 0.15

0.1 0.2 0.3 0.4

,,,, I, i i _ I, I J, I,,,, I I , I

32-Ply,4-in. Opening

_m_Y°aSdP=P2_ IlbfPact

Deflection(in.)

0.5

t

10

8

-6

4

2

0

0.2

Figure 56. Load versus deflection specimen 727-19s.

cI.

Z

v

v

O

,=,d

5,000

4,000

3,000

2,000

1,000

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

-i,,Jl,,,lll,1,1,1111,,I,lJJJ_l,JI, I ,

48-Ply,6-in.Opening

,_ 24

SimplySupported Impact __,,_ "] 2O

8

'l I i i I i I i ' l i ' i'=i""T i I I I I I I i [ I i i i 4

A 0

0.05 0.1 0.15 0.2 0.25 0.3

16

r.=

==

12 ="

;X

Z

v

Deflection(in.)

Figure 57. Load versus deflection specimen 727-02s.

54
5OO

4OO

A 300

,,m

"u

t_

o

200

1go

Deflection(cm)

0 0.2 0.4 0.6 0.8

i i i I i t i I t i i I i i i I i i i

8-Ply,6-in. Opening #l

ClampedImpact J _ AA

L

Fj__TI I i][J]=j[llt.,,_rl =ll J i j

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Deflection(in.)

1.5

0

w

=l.

0.5

I" 0

0.4

Figure 58. Load versus deflection specimen 616-15f.

0

5O0

400

300

m

o

"_ 200

100

Deflection(cm)

0.2 0.4 0.6 0.8

i i i t i _ i I i i i I i i ,.=lI i i i

8-Ply,6-in. Opening /,J11

ClampedImpact t [

MaxLoad =

_'_,_J.,'_-I ,.#"P_'_iI I I t | I [ I,,, I, I-_"I, ],, I ,,l

0.05 0.1 0.15 0.2 0.25 0.3 0.35

Deflection (in.)

1.5

I"

o

lid

a.

Z

v

- 0.5

, 0

0.4

Figure 59. Load versus deflection specimen 61 6-16f.

55
Deflection(cm)

400

350

300

25O

200

150

100

50

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

8-Ply,6-in. Opening _ 1.6

- ClampedImpact f j'

-- Max Load 1.4

1.2

1

0.8

0.6

0.4

0.2

_,/_'%.._,_,,-,.,.,,"T_ _ i f I i H ,__'#'_,, I i i J, I J- 0

0.05 0.1 0.15 0.2 0.25 0.3

Deflection(in.)

Figure 60. Load versus deflection specimen 616-17f.

ro

m

z

v

400

350

3OO

25O

•_ 200

o

..J

150

100

Deflection(cm)

50

0

0.1 0.2 0.3 0.4 03 0.6 0.7 0.8

_llalll_lltJlittll=il*lltlltllllll_llllllll_

i 8-Ply,6-in. Opening r_

- ClampedImpact ## ii

- MaxLo

aP_,,..i,,_t_ j I I I I J I I..,i_l I I I I I I I I = ] I

0 0.05 0.1 0.15 0.2 0.25 0.3

1.6

1.4

1.2

1 =

Gin,

o.s

0.6

0.4

0.2

0

0.35

Deflection(in.)

Figure 61. Load versus deflection specimen 616-18f.

56
Deflection(cm)

1,600

1,400

1,200

1,000

800

600

4O0

200

0

0

0 0.4 0.8 1.2 1.6

, , I I I , , I ' I t I s , , I ' I -

|

16-Pty,12-in.Opening ]_

ClampedImpact r_

[11

0.1 0.2 0.3 0.4 0.5 0.6 0.7

Deflection(in.)

Figure 62. Load versus deflection specimen 616-0 If.

4

ira_

A

3

1,600

1,400

1,200

1,000

.=

-o 800

600

Deflection(cm)

400

200

0

0.4 0.8 1.2 1.6

' ' ' I ' ' i I ' ' ' l J J ' I , r- 7

16-Ply,12-in.Opening

ClampedImpact I 4- 6

Jl

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Deflection(in.)

Figure 63. Load versus deflection specimen 6 ! 6-02f.

r- 4 o

cI.

3

5?
Deflection(cm)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

1,600 .- '1 ' I ' 7

1,400 _Lli 16Ply, Clamped12in. Impact Opening _t _ 6

1,2OO 5

1,000

800 4_=

__ a N

600

400 2

200 1

0 0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Deflection(in.)

Figure 64. Load versus deflection specimen 616-03f.

1,600

1,400

1,200

.-. 1,000

,,D

-= 800

m

o

600

400

200

0

Deflection(cm)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

,_ I I I I I I I I I I I I I I I _ I a I I I I I I I = I I I s*'i*_-'E_

"- 16-Ply,12-in. Opening '_ -

-- Clampedlmpact / t_-

f--

I

0

4

3

2

1

0

0.1 0.2 0.3 0.4 0.5 0.6 0.7

Deflection(in.)

Figure 65. Load versus deflection specimen 616--04f.

r'-

58
A

b

,mv

"u

m

0

25O

200

150

100

5O

Deflection(cm)

0.1 0.2 0.3 0.4

- I I i I I I I i i I I I I I I i I I I l i I i I

- 8-Ply, 2-in. Opening

ClampedImpact _ _

I i l I I l I I I I i I I I l , i

0.05 0.1 0.15

0.5

- 12

0.8

0

Ih)

0.6 _"

0.4

0.2

0

0.2

Deflection(in.)

Figure 66. Load versus deflection specimen 616-37m.

.m

M

O

,.,J

250

2OO

150

100

5O

Deflection(cm)

0.25

1

0 0.05 0.1 0.15 0.2

i , J , I i , J , I , l I , I I i t i I I , , t

8-Ply,2-in. Opening

ClampedImpact

il I I I I I l I , , ] J , z , I I ! I

0.02 0.04 0.06 0.08

0 0

0 0.1

0.8

0

0.6 _.

g

0.4

0.2

Deflection(in.)

Figure 67. Load versus deflection specimen 616-38m.

59
250

200

150

i

o

100

5O

Deflection(cm)

0.6

I1

0.1 0.2 0.3 0.4 0.5

8-Ply,2-in. Opening

ClampedImpact _

_,,_1 t t i i i t [ i _ J I t i R i I _ i i

0.05 0.1 0.15 0.2

0 0

0 0.25

Deflection(in.)

0.8

0.6 -

==.

v

0.4

0.2

Figure 68. Load versus deflection specimen 728-09m.

250

2OO

A-- 150

o

-J

100

5O

Deflection(cm)

0 0.1 0.2 0.3 0.4

8-Ply,2-in.Opening

ClampedImpact

"T'I I 1 I J ' ' ,='k,._ , ._=', I I I I ]

0 0.05 0.1 0.15

Deflection(in.)

0.5

0.8

0.6 _.

Z

0.4

0.2

0

0.2

Figure 69. Load versus deflection specimen 728-1 lm.

60
Deflection(cm)

800

600

,,m

m

"u

m

o 400

200

0 0.1 0.2 0.3 0.4 0.5

J i J i i , i , i i , , , , i , , , , 1 i , , i 4

16-Ply,4-in. Opening .,.,_1 3.5

ClampedImpact ../"" I

3

2.5

2

1.5

1

0.5

-b-.._=.l-.._. I , l I l I.,_" J 1 I I I J , I 0

0 0.05 0.1 0.15 0.2

Deflection(in.)

Figure 70. Load versus deflection specimen 616-25m.

:X

1,000

800

ff soo

400

200

0

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5

I , a , i i i i i i i i I t 1 u J i i i i i i i

16-Ply,6-in. Opening 4

ClampedImpact _ .,L..

3.5

3

2.5

2 j

1.5

1

- 0.5

___n,.,_a, I J I i ] i I1 = I I ] I I I I 0

0.05 0.1 0.15 0.2

Deflection(in.)

Figure 71. Load versus deflection specimen 616-26m.

61
1,000

8OO

600

4OO

2OO

0

Deflection(cm)

0.1

I I I I I I I i i I i J I I I I I i I l _ J i i

1B-Ply,4-in. Opening

ClampedImpact

r I ]"_l=li'ri J. I 1 I .I I I _ I I I _ _ I I

0.05

0.2 0.3 0.4 0.5

- 4

3.5

3

2.5 E

2 N

1.5

1

0.5

0

0.1 0.15 0.2

Deflection(in.)

Figure 72. Load versus deflection specimen 616-27m.

1,000

800

.-.. 60O

400

200

0

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5

I ! ! I l J | I l i I I I I l I I I I i I I I I

16-Ply,4-in. Opening --t 4

ClampedImpact _ A_ _1 3.5

=

3

2.5 E

2 N

1.5

1

0.5

0

0 0.05 0.1 0.15 0.2

Deflection(in.)

Figure 73. Load versus deflection specimen 616-28m.

62
Deflection(cm)

7,000

6,000

5,000

4,000

"m

N

'_, 3,000

2,000

1,000

0

0

0 0.2 0.4 0.6 0.8 1 1.2

I I I t 0 _ t I _ I I I I I J i i t i 11 i i I _r 30

48-Ply,12-in. Opening

ClampedImpact _. fll

I I _ I I I [ I = I--_" I I L.l I J I I I I I I

0.1 0.2 0.3 0.4 0.5

Deflection(in.)

- 25

- 2O

0

¢=.

- 15

Z

v

10

Figure 74. Load versus deflection specimen 61599-04m.

Deflection(cm)

0 0.2 0.4 0.6 0.8 1

6,000 _l i i i i i i I i I I t Jill, i i i i J i

48-Ply,12-in. Opening

5,000 ClampedImpact ,,w,

Max Load= 5,265 Ibf

f'v

1'001 t I I I I I 1 I I l I I' 'S I

0.1 0.2 0.3 0.4

4,000

i

.= 3,000

o

..J

2,000

Deflection(in.)

1.2

I L

- 25

- 20

1_15 E

m

el.

10

- 5

, 0

0.5

Figure 75. Load versus deflection specimen 61599-05m.

63
800

700

600

5OO

v

= 400

o

..,.I

300

200

Deflection(cm)

100

0

0 1 2 3 4

I J i l t I i _ I i I i _ I i i i _ l _ i

16-Ply,2-in. Opening t_,

ClampedImpact / _,

- MaxLoad =

/ i i , , , , , i i , i f i , ,..i.l.r.T_ i i t ,

lll]]lllllllllllll l,[jll I I I I I I

0.05 0.1 0.15

Defleclion(in.)

J-O

Figure 76. Load versus deflection specimen 616-29s.

2.5

2 =

1.5 z

0.5

700

600

5OO

400

3 300

2OO

IO0

0

Deflection(cm)

0 0.5 1 +1.5 2 2.5 3 3.5

V " -t

0.02 0.04 0.06 0.08 0.1 0.12

2.5

Deflection(in.)

0.5

0

0.14

2

Q

1.5

Z

v

Figure 77. Load versus deflection specimen 616-30s.

64
v

3

=.=1

700

600

500

400

300

200

100

O

Deflection(cm)

1 2 3 4

16-Ply,2-in. Opening _r _ /_

ClampedImpact J _ _ _ _ A

Max Load=

_ l I I I i I [ 1 1 I I I I[l I L_d_li'_l I I i i i 1 i -

0.05 0.1 0.15

Deflection(in.)

Figure 78. Load versus deflection specimen 616-31 s.

3

2.5

2

1.5 ._

1

0.5

0

Deflection(cm)

0 1 2 3 4

700 }_ ' ' ' ' I ' ' o , Ii#I. , , , I ' l , , I ' '--I

E 16-Ply,2-in. Opening /f'_ _ _ 3

600 l- ClampedImpact ] _ t _t _ _ _1

500 MaxLoad= 697 Ibf 2.5

!

2

,oo .; 1.5 _

300

1

2OO

100 0.5

0 O

0 0.05 0.1 0.15

Deflection(in.)

Figure 79. Load versus deflection specimen 616-32s.

65
2,000

1,500

•= 1,000

o

.J

5OO

Deflection(cm)

0

0

0.5 1 1.5 2 2.5 3 3.5 4

iii,llialtli_tl_tllilt_l_iJllltiJiJ_I_

32-Ply,4-in. Opening - 8

ClampedImpact

MaxL0a 7

6

5

4

-3

1

i I I i i I I i i..l_illl_ I I i i I I i I I I i 11- 0

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

Deflection(in.)

Figure 80. Load versus deflection specimen 616-20s.

O

w

Z

2,000

1,500

A

w

v

"_ 1,000

o

.,.I

500

0

0

Deflection(cm)

0.5 1 1.5 2 2.5 3 3.5 4

I I iillitll I I i I I II i I I III I I I i I I I I i iil I I I I

32-Ply,4-in. Opening 8

ClampedImpact

6

5

4

' - 3

2

|

_1 i t i i l,l i i J I i i i Lo_'l i I i i i I i _ J I i i i 0

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

Deflection(In.)

Figure 81. Load versus deflection specimen 616-21 s.

w

Z

v

66
Deflection(cm)

0

2,000

1,500

•,= 1,000

m

o

ml

500

0.5 1 1.5 2 2.5 3 3.5 4

ialllliJllllllllllllllllllJlllllllllllJ

32-Ply,4-in. Opening 8

ClampedImpact

MaxLoad = 7

6

5

4

3

J

2

Illll[I lllJl]lJ 0

0.02 0.04 0.06 0.08 0.1 0,12 0.14 0,16

Oelleclion(in.)

Figure 82. Load versus deflection specimen 616-22s.

r"-

o

w

gl.

z

6?
APPENDIX CmLOAD VERSUS DEFLECTION PLOTS FOR QUASI-STATIC

INDENTATION TESTS

Figures 83-97 show load versus deflection plots for quasi-static indentation tests.

400

35O

300

25O

200

150

IO0

50

0

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

.... , .... , .... , .... , .... , .... ,"i'"':l

1L ]

8-Ply, 6-in. OpeningClampedStatic .._ -1 1,600

MaxLoad = 390 Ibf ,ll I' _1

Jlg !

LostEnergy= 0.57 ft-lb _ -1 1,400

= . " • "

1,200

1,000

800

6OO

4OO

2OO

0

0.05 0•1 0.15 0.2 0.25 0.3

Deflection(in.)

Figure 83. Load versus deflection specimen 708-10f.

68
A

b

m

(U

O

ml

600

5OO

400

3O0

200

100

0 0.1 0.2

Deflection(cm)

0.3 0.4

8-Ply,6-in. OpeningClampedStatic

Max Load= 513 Ibf

LostEnergy= 1.92 ft-lb

Rate= 0.05 in./min

0.5 0.6 0.7

0 0.05 0.1

Figure 84.

0.15

Deflection(in.)

0.2 0.25

0

0.3

Load versus deflection specimen 708-1 If.

2,500

2,000

1,500

1,000

500

m

==.

v

1,400

1,200

1,000

800

600

400

2OO

0

Deflection(cm)

0 0.5 1

16-Ply,12-in.OpeningSimplySupportedStatic

MaxLoad = 1,218ibf

Rate= 1 in./min

0 0.1 0.2 0.3 0.4 0.5

Deflection(in.)

1.5

6,000

5,000

4,000

3,000

2,000

1,000

0

0.6

Figure 85. Load versus deflection specimen 1018-02f.

69
Deflection(cm)

1,000

800

600

O

400

200

OI

0

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

16-Ply,4-in. OpeningClampedStatic

Max Load = 827 Ibf

Lost Energy= 0.99 ft-lb

Rate= 0.05 in./min

0.05

Deflection(in.)

0.1

4,000

3,500

3,000

2,500 E

2,000 =

1,500

1,000

5OO

0

0.15

Figure 86. Load versus deflection specimen 708-03m.

t_

o

-.I

1,000

8OO

600

400

200

Deflection(cm)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

16-Ply,4-in. OpeningClampedStatic

Max Load = 833 Ibf

Lost Energy= 0.89 ft-lb

Rate= 0.05 in./min

0 0.05 0.1

Deflection(in.)

Figure 87. Load versus deflection specimen 708-02m.

4,000

3,500

3,000

2,500

2,000 z

1,500

1,000

500

0

0.15

7O
v

1,000

8OO

600

400

200

Dellection(cm)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

16-Ply,4-in. OpeningClampedStatic

Max Load= 821 Ibf

Lost Energy= 0.86 ft-lb

Rate= 0.05 in./min

Figure 88.

4,000

3,500

3,000

2,500

2,000 ._=

1,500

1,000

50O

0

0.05 0.1 0.15

Deflection(in.)

Load versus deflection specimen 708-04m.

O

,..I

1,000

800

60O

400

200

Deflection(cm)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

16-Ply,4-in. OpeningClampedStatic 4,000

MaxLoad = 916 Ibf

Lost Energy= 1.58 ft-tb 3,500

Rate= 1 in./min

3,000

2,500 _"

2,000

1,500

1,000

5O0

0

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

Deflection(in.)

Figure 89. Load versus deflection specimen 708-05m.

71
1,000

8OO

600

400

200

0

Deflection(cm)

0.05 0.1 0.15 0.2 025 0.3 0.35 0.4

.... I .... t ' ' ' ' I ' ' ' ' I ' ' ' ' I .... t .... I .... I

16-Ply,4-in. OpeningClampedStatic

MaxLoad = 867 lbf ,1_=-_"

Lost Energy= 1.07 ft-lb hr_

0.02

4,000

3,500

3,000

2,500 [

2,000

1,500

1,000

5O0

0

0.04 0.06 0.08 0.1 0.12 0.14 0.16

Deflection(in.)

Figure 90. Load versus deflection specimen 708-06m.

Deflection(cm)

6,000

5,000

4,000

3,000

2,000

i ,000

0,'

0

0.5 1 1.5

i i , t i , , i i i i = J o i p , i _ I ' ' ' ' ' ' ' ' '

48-Ply, 12-in.OpeningClampedStatic 25,000

Max Load = 5,384 Ibf

Rate= 1 in./min / J'. _l _I_ 20,000

15,000

10,000

5,000

;,,, I .... _,,,, i .... J,, ',,, , , ,

, i l i , 0

0.1 0.2 0.3 0.4 0.5 0.6

Deflection(in.)

Figure 9 l. Load versus deflection specimen 1015-01 m.

72
Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

6,000

25

5,000

2O

4,000

3,000

10

2,000

1,000 5

0 0

0 0.05 0.1 0.15 0.2 0.25 0.3

Deflection(in.)

Figure 92. Load versus deflection specimen 1015-02s.

A

i

v

t_

O

--J

2,000

1,500

1,000

500

Deflection(cm)

0.05 0.1 0.15 0.2 0.25 0.3

.... t .... 1 .... I .... I .... I ....

32-Ply,4-in. OpeningClampedStatic 8,000

MaxLoad = 1,676Ibf

7,000 Lost Energy= 3.1 ft-lb

Rate= 1 in./min _ .___e m_of 6,000 5,000

.t f / 4,000

_1_" 3,000

o_O 2,000

1,000

0 F ! , , , [ • , • 0

0 0.02 0.04 0.06 0.08 0.1 0.12

Deflection(in.)

Figure 93. Load versus deflection specimen 708--07s.

73
1,400

1,200

1,000

"" 8OO

m

o

600

400

200

Deflection(cm)

0 0

0 0.07

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

, ' ' ' I ' ' ' I ' ' ' t ' ' ' I ' ' ' I ' ' ' I ' ' ' I ' ' ' I ' '

32-Ply, 4-in. Opening Clamped Static

MaxLoad = 1,236Ibf •

Lost Energy= 1.85 ft-lb °• eo__

Rate= 1 in./min ° •

• CO ° O o

O0 •° O o • •

• o o

• o gO O

O •• •O °

• O o•

• O O o

• O go

.....,_;;.o,.,,,., .... . .... , .... , ....

0.01 0.02 0.03 0.04 0.05 0.06

=

6,000

5,000

4,000

D

W

3,000

2,000

1,000

Deflection(in.)

Figure 94. Load versus deflection specimen 708-08s.

Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5 0.6

2,500

10,000

2,000

8,000

,/I 16,000

.o0o I /-./, l.oo0

,o oooo

0 0.05 0.1 0.15 0.2 0.25

Deflection(in.)

Figure 95. Load versus deflection specimen 1015-03s.

?4
Deflection(cm)

0 0.1 0.2 0.3 0.4 0.5

2,500

f__'J"'_"---""'hl 10,000

A l',ooo

6,000

=. _

1,ooo I /-/ 1`°°°

0 0.05 0.1 0.15 0.2

Deflection(in.)

Figure 96. Load versus deflection specimen 1018-03s.

Deflection(cm)

0 0.05 0.1 0.15 0.2 0.25 0.3

2,000 _rl_mn_.d .qtntin

t _::_!:!ii!_!iZ ..............., 1,0oo

1,5ooI- _:°_'"_"' 11 ] '

f J'/ 1`000

=_ F ,, _" / t _'°°°=_

1,000I- ./ _ / j R

= t 71"/ t'°°°_"

r / / t_°°°

ot/__- t?°

0 0.02 0.04 0.06 0.08 0.1 0.12

Deflection(in.)

Figure 97. Load versus deflection specimen 706-01s.

75
APPENDIX DmNONDESTRUCTIVE EVALUATION ANALYSIS DATA

Tables 15-20 display simply supported and clamped flex data for nondestructive evaluation

analysis.

Table 15. Simply supported flex.

8 Plyon 6-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

IDNo. N (Ibf) mm(in.) mm (in.) mm2 (in.2)

727-06F

727-07F

727-08F

727-09F

727-10F

1,850 (416)

1,766 (397)

1,850 (416)

1,873 (421)

1,873 (421)

0.102(0.004)

0.075(0.003)

0.075 (0.003)

0.075(0.003)

Not measurable

I6.OO(0.63)

47.75 (1.88)

22.35 (0.88)

25.4 (1.00)

31.75 (1.25)

170 (0.28)

216 (0.33)

157 (0.24)

223 (0.34)

190 (0.29)

Quasi-Static

817-10F

817-11F

817-04F

817-05F

1,819 (409)

1,859 (418)

1,859 (418)

1,850 (416)

0.102 (0.004)

0.102 (0.004)

0.075 (0.003)

0.075 (0.003)

0.075 (0.003)

Not measurable

19.05 (0.75)

22.35 (0.88)

177 (0.27)

111 (0.17)

190 (0.29)

190 (0.29)

16 Plyon12-in. Platen

Impact

Specimen

ID No.

728-05F

728-06F

728-07F

Max

Load

N (Ibf)

4,862 (1,093)

5,400 (1,214)

5,373 (1,208)

Dent

Depth

mm(in.)

0.102(0.004)

0.102(0.004)

0.051(0.002)

Crack

Length

mm(in.)

Not measurable

31.75 (1.25)

35.o5(1.38)

Delamination

Area

mm2 (in.2)

426(0.65)

499(0.76)

590(0.90)

Quasi-Static

818-05F

818-06F

818-03F

818-04F

1018-02F

5,360 (1,205)

5,458 (1,227)

5,809 (1,306)

5,667 (1,270)

5,420 (1,218)

0.152(0.006)

0.127(0.005)

0.127(0.005)

0.127(0.005)

Nodata

6.35 (0.25)

6.35 (0.25)

4.83 (0.19)

9.65(0.38)

No data

505 (0.77)

538 (0.82)

433 (0.66)

472 (0.72)

416 (0.64)

76
Impact

Specimen

IDNo.

728-02M

728-03M

728-04M

Table 16. Simply supported medium.

8 Plyon 6-in. Platen

Max

Load

N (Ibf)

1,023 (230)

974 (219)

907 (204)

Dent

Depth

mm (in.)

0.076 (0.003)

0.076 (0.003)

0.051 (0.002)

Crack

Length

mm (in.)

16.00(0.63)

16.00(0.63)

9.65(0.38)

Delamination

Area

mm2 (in.2)

85 (0.13)

79 (0.12)

52 (0.08)

Quasi-Static

819-01M 734 (165) 0.025 (0.001) 6.35 (0.25) 39 (0.06)

819-02M 907 (204) 0.076 (0.003) 4.83 (0.19) 46 (0.07)

819-07M 1,059 (238) 0.152 (0.006) 16.00(0.63) 79 (0.12)

819-08M 1,059 (238) 0.127 (0.005) 19.05(0.75) 105 (0.16)

16 Ply on 4-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

ID No. N (Ibf) mm (in.) mm(in.) mm2 (in.2)

727-11M

727-12M

727-13M

727-14M

727-15M

Quasi-Static

3,723 (837)

3,701 (832)

3,670 (825)

2,998 (674)

2,963 (666)

819-16M 3,677 (827)

819-17M 3,670 (825)

819-09M 4,003 (900)

819-10M 3,777 (849)

Penetrated

0.279 (0.011)

0.102 (0.004)

0.051 (0.002)

0.076 (0.003)

Nodata

28.70 (1.13)

25.40 (1.00)

6.35 (0.25)

19.05(OZ5)

No data

492 (0.75)

321 (0.49)

171 (0.26)

262 (0.40)

Nodata

0.102 (0.004)

0.152 (0.006)

0.203 (0.008)

No data

9.65 (0.38)

31.75(1.25)

31.75(1.25)

400 (0.61)

308 (0.47)

315 (0;48)

328 (0.50)

48 Plyon12-in. Platen

Impact

Max Dent crack Delamination

Specimen Load Depth Length Area

ID No. N (Ibf) mm(in.) mm (in.) mm2 (in.2)

61599-02M 23,557 (5,296) 0.614 (0.024) 112.13(4.38) 3,214 (4.90)

61599-03M 29,496 (6,631) 0.205 (0.008) 118.53(4.63) 3,011 (4.59)

Quasi-Static

818-07M 23,878 (5,368) 0.635 (0.25) Numerouscracks 25.80 (4.00)

818-01M 28,304 (6,363) No data Nodata 26.38 (4.09)

77
Table 17. Simply supported stiff.

16Ply on2-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

I0 No. N (Ibf) mm(in.) mm (in.) mm2 (in.2)

727-20S

727-21S

727-22S

728-01S

Quasi-Static

819-03S

819-04S

819-05S

819--06S

2,922(657)

2,771(623)

3,350(753)

3,051(686)

2,904(653)

2,918(656)

2,758(620)

2,931(659)

0.127(0.005)

o.178(0.0o7)

0.102(0.004)

0.152(0.006)

31.75 (1.25)

35.05 (1.38)

16.00(0.63)

26.92 (1.06)

Not measurable 1.27 (0.50)

0.178 (0.007) 16.00(0.63)

0.356 (0.014) 38.10 (1.50)

0.279 (0.011) 30.22 (1.19)

288 (0.44)

334 (0.51)

269 (0.41)

295 (0.45)

269 (0.41)

328 (0.50)

348 (0.53)

308 (0.47)

32 Plyon4-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

IDNo. N (Ibf) mm (in.) mm (in.) mm2 (in.2)

727-16S

727-17S

727-18S

727-19S

8,696 (1,955)

9,106 (2,047)

9,853 (2,215)

9,346 (2,101)

0.152 (0.006)

0.152 (0.006)

0.178 (0.007)

0.152 (0.006)

38.10 (1.50)

Not measurable

Notmeasurable

47.75 (1.88)

984 (1.53)

1,I54 (1.76)

1,141 (1.74)

1,207 (1.84)

Quasi-Static

819-14S

819-15S

819-12S

819-13S

1015-03S

1018-03

9,866 (2,218)

9,844 (2,213)

10,898 (2,450)

10,925 (2,456)

9,718 (2,184)

9,790 (2,200)

0.330 (0.013)

0.330 (0.013)

0.254 (0.010)

0.279 (0.011)

Nodata

Nodata

47.75 (1.88)

47.75 (1.88)

41.40 (1.63)

28.70(1.13)

No data

No data

1,220(1.86)

1,233(1.88)

1,586(2.42)

1,614(2.46)

1,232(1.91)

1,297(2.01)

48 Plyon 6-in. Platen

Impact

Specimen

ID No.

727-022

727-032

Quasi-Static

Max

Load

N (Ibf)

122,121(4,973)

22,810(5,128)

Dent

Depth

mm (in.)

0.279 (0.011)

0.686 (0.027)

Crack

Length

mm(in.)

1.27(0.50)

63.50 (2.50)

817-08S

817-092

817-062

817-072

22,726 (5,109)

22,383 (5,032)

21,476 (4,828)

20,987(4,718)

0.457 (0.018)

1.067(0.042)

1.497(0.059)

1.016(0.040)

Numerouscracks

55.63 (2.19)

Numerouscracks

31.75 (1.25)

Delamination

Area

mm2(in.2)

3,339 (5.09)

4,284 (6.53)

4,146 (6.32)

4,146 (6.32)

4,211 (6.42)

3,765 (5.74)

?8
Table 18. Clamped flex.

8 Plyon6-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

IDNo. N (lbl) mm (in.) mm (in.) mm2(in.2)

616-15F 1,930 (434) 0.203 (0.008) 85.85 (3.38) 676 (1.03)

616-16F 2,148 (483) 0.381 (0.015) 74.68 (2.94) 479 (0.73)

616-17F 1,673(376) 0.051 (0.002) 19.05 (0.75) 112 (0.17)

616-18F 1,668(375) 0.076 (0.003) 22.35 (0.88) 112 (0.17)

Quasi-Static

708-10F

708-11F

720-07F

720-08F

1,735(390)

2,277 (512)

1,415(318)

1,899(427)

No data

0.635 (0.025)

0.152 (0.006)

0.127 (0.005)

Nodata

44.45 (1.75)

12.70 (0.50)

9.53 (0.38)

Nodata

348 (0.53)

92 (0.14)

85 (0.13)

16 Plyon 12-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

ID No. N (Ibf) mm (in.) mm (in.) mm2 (in.2)

616-01F

616--02F

616-03F

616-04F

6,841 (1,538)

6,921 (1,556)

7,037 (1,582)

7,108 (1,598)

0.152 (0.006)

0.127 (0.005)

0.127 (0.005)

0.127 (0.005)

41.28(1.63)

57.15 (2.25)

38.10(1.50)

42.07(1.66)

774 (1.18)

741 (1.13)

833 (1.27)

78t (1.19)

Quasi-Static

720-03F

720--04F

720--05F

720-06F

6,935(1,559)

6,993(1,572)

7,357(1,654)

7,517(1,690)

0.178 (0.007)

0.203 (0.008)

0.152 (0.006)

0.178 (0.007)

44.45 (1.75)

44.45 (1.75)

25.4 (1.00)

35.05 (1.38)

643 (0.98)

708 (1.08)

715 (1.09)

84O(1.28)

79
Table 19. Clamped medium.

8 Plyon 2-in. Platen

Impact

Specimen

IDNo.

616-37M

616-38M

728-09M

728-11M

Max

Load

N (Ibf)

1,045 (235)

939 (211)

936 (210)

1,036 (233)

Dent Crack

Depth Length

mm(in.) mm (in.)

Extensivedamage

0.229(0.009) I Numerouscracks

0.102(0.004) I 22.35 (0.88)

Extensivedamage

Delamination

Area

mm2(in.z)

No data

190 (0.29)

92 (0.14)

131 (0.20)

Quasi-Static

722-03M

722-04M

722--05M

722-06M

1,183 (266) 0.076(0.003)

1,045 (235) 0.102(0.004)

939 (211) 0.127(0.005)

894 (201) Not measurable

16.00 (0.63)

9.65 (0.38)

6.35 (0.25)

Not visible

66 (0.10)

59 (0.09)

52 (0.08)

46 (0.07)

16Ply on4-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

IDNo. N (Ibf) mm(in.) mm (tn.) mm2 (in.2)

616-25M

616-26M

616-27M

616-28M

Quasi-Static

3,634 (817)

3,629 (816)

3,665 (824)

3,728 (838)

708-02M 3,705 (833)

708--03M 3,679 (827)

708-04M 3,652 (821)

708-05M 4,075 (916)

708-06M 3,857 (867)

0.076(0.003)

0.076(0.003)

0.076(0.003)

0.127(0.005)

0.152(0.006)

0.152(0.006)

0.152(0.006)

0.152 (0.006)

0.127(0.005)

22.23(0.88)

34.93 (1.38)

38.10 (1.50)

44.45 (1.75)

Notmeasurable

25.4 (1.00)

22.35 (0.88)

16.00 (O.63)

Not measurable

276 (0.42)

348 (0.53)

230 (0.35)

335 (0.51)

348 (0.53)

374 (0.57)

308 (0.47)

420 (0.64)

420 (0.64)

48 Plyon 12-in. Plalen

Impact

Specimen

ID No.

Max

Load

N (Ibf)

Dent

Depth

mm(in.)

61599-04M 26,823 (6,030) 0.794 (0.031)

61599-05M 23,420 (5,265) 1.434 (0.059)

Quasi-Static

817-01M 26,293 (5,911) 0.333(0.013)

817--02M 28,290 (6,360) 0.435(0.017)

Crack

Length

mm(in.)

Delamination

Area

mm2 (in.21

80.00 (3.16) 3,640(5.55)

70.40 (2.75) 3,378(5.15)

99.20 (3,88) 4,159 (6.34)

107.20 (4.19) 3,241 (4.94)

8O
Table 20. Clamped stiff.

16 Plyon2-in. Platen

Impact

Max Dent Crack Delamination

Specimen Load Depth Length Area

ID No. N (Ibf) mm(in.) mm(in.) mm2 (in.2)

616-29S 3,239 (728) 0.457 (0.018) 50.80 (2.00) 382 (0.592)

616-30S 2,922 (657) 0.203 (0.008) 55.56 (2.19) 512 (0.794)

616-31S 3,105 (698) 66.68 (2.63) 624 (0.967)

616--32S 3,100 (697) 0.356 (0.014) 68.26 (2.69) 676 (1.048)

Quasi-Static

722-01S

722-02S

722-07S

722-08S

3,272(736) 0.203 (0.008)

3,109(699) 0.178(0.007)

2,989(672) 0.178(0.007)

3,003 (675) 0.305(0.012)

9.65 (0.38) 432 (0.670)

19.05 (0.75) 560 (0.868)

9.65 (0.38) 528 (0.818)

22.35 (0.88) 536 (0.831)

32 Plyon 4-in. Platen

Impact

Max Dent Crack Delaminaiion

Specimen Load Depth Length Area

ID No. N (Ibf) mm(in.) mm (in.) mm2 (in.2)

616-20S

616-21S

616-22S

616-24S

Quasi-Stalic

706-01S

708-07S

708-08S

7,313 (1,644)

7,268 (1,634)

7,544 (1,696)

7,322 (1,646)

0.127(0.005)

0.152(0.006)

0.178(0.007)

0.152 (0.006)

22.53 (0.88)

19.20 (0.75)

19.20 (0.75)

28.93 (1.14)

1,006 (1.56)

1,012 (1.57)

1,012 (1.57)

987 (1.53)

7,455 (1,676)

7,455 (1,676)

5,498(1,236)

0.203 (0.008)

0.203 (0.008)

0.203(0.008)

Not measurable 1,256 (1.947)

19.05(0.75) 904 (1.401)

Not measurable

48 Plyon6-in. Platen

Impact

Max Dent Crack Delaminatlon

Specimen Load Depth Length Area

IDNo. N (Ibf) mm (in.) mm(in.) mmz(in.2)

727-04S 22,788 (5,123) 0.381 (0.015) 73.03(2.86) 5,412(8.39)

727-05S 23,100 (5,193) 0.483 (0.019) 77.78(3.06) 4,128 (6.40)

Quasi-Static

720-01S

720-02S

817--02S

817-03S

23,429 (5,267)

22,196 (4,990)

23,389 (5,258)

23,389 (5,258)

1.321 (0.052) 28.70 (1.18)

1,19 (0.047) 22.35 (0.88)

0.838 (0.033) 16.00 (0.63)

1.19 (0.047) 31.75 (1.25)

5,648 (8.754)

5,244 (8.128)

3,186 (4.94)

4,880 (7.564)

81
REFERENCES

1. ASTM Standard D6264-8, 1999 ASTM Book of Standards, Vol. 15.03.

2. Cantwell, W.J.; and Morton, J.: "Comparison of the Low- and High-Velocity Impact Response of CP-RP,"

Composites, Vol. 20, No. 6, pp. 545-551, November 1989.

3. Wu, E.; and Chang, L.: "Loading Rate Effect on Woven Glass Laminated Plates by Penetration Force,"

Journal of Composite Materials, Vol. 32, No. 8, pp. 702-721, 1998.

4. Jackson, W.C.; and Poe, C.C.: "The Use of Impact Force as a Scale Parameter for the Impact Response

of Composite Laminates," NASA Technical Memorandum 104189, January 1992.

5. Bucinell, R.B.; Nuismer, R.J.; and Koury, J.L.: "Response of Composite Plates to Quasi-Static Impact

Events," Composite Materials: Fatigue and Fracture (Third Volume), ASTM STP 1110, pp. 528-549,

1998.

6. Swanson, S.R.: "Limits of Quasi-Static Solutions in Impact of Composite Structures," Composites

Engineering, Vol. 2, No. 4, pp. 261-267, 1992.

7. Kwon, Y.S.; and Sankar, B.V.: "Indentation-Flexure and Low-Velocity Impact Damage in Graphite

Epoxy Laminates" Journal of Composites Technology and Research, Vol. 15, No. 2, pp. 101-111,

Summer 1993.

8. Lagace, EA.; Williamson, J.E.; Wilson Tsang, EH.; Wolf, E.; and Thomas, S.: "A Preliminary Proposition for a Test Method to Measure (Impact) Damage Resistance," Journal of Reinforced Plastics and

Composites, Vol. 12, pp. 584-601, May 1993.

9. Kaczmarek, H.; and Maison, S.: "Comparative Ultrasonic Analysis of Damage in CFRP Under Static

Indentation and Low-Velocity Impact," Composites Science and Technology, Vol. 51, pp. 11-26, 1994.

10. Wardle, B.L.; and Lagace, P.A.: "On the Use of Dent Depth as an Impact Damage Metric for Thin

Composite Structures," Journal of Reinforced Plastics and Composites, Vol. 16, No. 12, pp. 1093-

lll0, 1997.

11. Nettles, A.T.; Douglas, M.J.; and Estes, E.E.: "Scaling Effects in Carbon/Epoxy Laminates Under

Transverse Quasi-Static Loading," NASA Technical Memorandum 209103, March 1999.

12. Cheresh, M.C.; and McMichael, S.: "Instrumented Impact Test Data Interpretation" Instrumented Impact

Testing of Plastics and Composite Materials, ASTM STP 936, pp. 9-23, 1987.

82
13.Found,M.S.;Howard,I.C.;andParan,A.E:"InterpretationofSignalsfromDrop-WeightImpactTests,"

Composite Structures, Vol. 42, pp. 353-363, 1998.

14. Lee, S.M.; and Zahuta, E: "Instrumented Impact and Static Indentation of Composites," Journal of

Composite Materials, Vol. 25, pp. 204-222, February 1991.

15. Sjoblom, P.O.; Hartness, T.J.; and Cordell, T.M.: "On Low-Velocity Impact Testing of Composite

Materials," Journal of Composite Materials, Vol. 22, pp. 30-52, January 1988.

16. lber, W.: "Failure Mechanics in Low-Velocity Impacts on Thin Composite Plates," NASA Technical

Paper 2152, 1983.

17. Highsmith, A.L.: "A Study of the Use of Contact Loading to Simulate Low-Velocity Impact," NASA

Contractor Report 97-206121, January 1997.

83


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August 2000 Technical Publication

4. TITLE AND SUB1TrLE

A Comparison of Quasi-Static Indentation to Low-Velocity Impact

AUTHORS

A.T. Nettles and M.J. Douglas*

PERFORMINGORGANIZATION NAMES(S) ANDADDRESS(ES)

George C. Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

5. FUNDING NUMBERS

8" PERFORMING ORGANIZATION

REPORT NUMBER

M-991

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA/TP--2000-210481

11.SUPPLEMENTARY NOTES

Prepared by the Materials, Manufacturing, and Processes Department, Engineering Directorate

*Old Dominion University, Norfolk, VA

12a. DISTRIBUTION/AVAILA BILITY STATEMENT

Unclassified-Unlimited

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12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

A static test method for modeling low-velocity foreign object impact events to composites would prove to be

very beneficial to researchers since much more data can be obtained from a static test than from an impact test. In

order to examine if this is feasible, a series of static indentation and low-velocity impact tests were carried out

and compared. Square specimens of many sizes and thicknesses were utilized to cover the array of types of lowvelocity impact events. Laminates with a n/4 stacking sequence were employed since this is by far the most

common type of engineering laminate. Three distinct flexural rigidities -under two different boundary conditions

were tested in order to obtain damage ranging from that due to large deflection to contact stresses and levels

in-between to examine if the static indentation-impact comparisons are valid under the spectrum of damage

modes that can be experienced. Comparisons between static indentation and low-velocity impact tests were based

on the maximum applied transverse load. The dependent parameters examined included dent depth, back surface

crack length, delamination area, and to a limited extent, load-deflection behavior. Results showed that no distinct

differences could be seen between the static indentation tests and the low-velocity impact tests, indicating that

static indentation can be used to represent a low-velocity impact event.

14. SUBJECT TERMS

composite materials, impact, static indentation

15. NUMBER OF PAGES

94

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A05

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