NBSIR 73-123

Resistance of Human Skin

Puncture and Laceration

Bernard J. McGuire

John R. Sorrells John D. Moore

Performance Criteria Section

Product Systems Section

Product Evaluation Technology Division

February 10, 1973

Report to Bureau of Product Safety

Food and Drug Administration

Department of Health, Education, and Welfare

NBSIR 73-123

RESISTANCE OF HUMAN SKIN TO

PUNCTURE AND LACERATION

Bernard J. McGuire

John R. So r re 1 1 s John D. Moore

Performance Criteria Section

Product Systems Section

Product Evaluation Technology Division

February 10, 1973

This is a progress report. The work is incomplete and is continuing. Conclusions

are not necessarily those that will be

included in a final report

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

INTRODUCTION

In support of the Bureau of Product Safety's program to

improve toy safety, the NBS Product Evaluation Technology

Division has been studying the problem of determining the

degree of hazard associated with the use of toys having points

and edges of various degrees of sharpness. The final goal of

this project is to develop a definition of and a simple test

method or device that will differentiate between "hazardous"

and "non-hazardous" toy configurations. In order to do this,

however, the investigation must cover many areas of interest.

The first report on this project, NBS Report No. 10,67 3

by Moore (1972) , provided results of preliminary subjective

evaluations of point sharpness and described the construction

of a mechanical device for easily measuring point sharpness

and strength. The second report, NBS No. 10,8 39 by McGuire

and Moore (1972) , provided further definition of the skin

puncture problem, including a review of published data, and

gave results of subjective evaluations of point sharpness by

physicians, results of laboratory tests on the puncture resistance of pigskin, preliminary results of tests on the puncture

resistance of human skin, and an evaluation of the injury

potential of various points. The present report, third in the

series, provides further discussion of the general problem

area, additional data on the physical properties of human

skin and gives results of tests to measure hand-toy impact

velocities and the cutting effects of sheared steel edges on
2

pigskin at appropriate impact velocities. Some preliminary

information on the puncture resistance of pigskin under

dynamic conditions is also given.
3

CONCLUSIONS

1. Human skin tensile strength and modulus of elasticity

increase rapidly during the first year of life and reach

near adult values by age one year. (See Section I A and

Figures 1 and 2 .

)

2. The resistance of adult human skin to puncture by Moore

penetrometer tips can be described by equations of the

form y = u + ax^ + bx2 + cx£ + dx| . (See Section I B and

Figure 8)

.

3. The estimated average puncture force curve previously

provided by McGuire and Moore (1972) can still be considered a reasonable dividing line between hazardous and

non-hazardous points under essentially static conditions.

(See Section I B.) Work now in progress may define other

criteria for points hazardous under dynamic conditions.

(See Conclusion No. 8.)

4. Hand velocities achieved by children of age 5 to 8 years are

approximately 2.1 to 2.5 meters/sec. for "quick-grab" motions,

and approximately 6.4 to 7.3 meters/sec. for "karate chop"

motions, based on a small sample. (See Section II A.)

5. The "effective weights" of children's hands and forearms

for ages 5 to 8 years are approximately 0.3 to 0.6 kg,

based on a small sample. (See Section II A.)

6. The pendulum skin test device used in this study provided

a useful first approximation of some possible hand-toy
4

impact conditions, but the device is not considered

suitable for use in further testing. (See Sections II B,

III A, III C, and Figures 9, 10, and 11.)

7. For a wide range of quality of sheared steel edges, all

such edges cut pigskin under impact conditions that are

easily achieved by the hands of children age 8 years.

Probably the sheared edges would cut human skin under the

same conditions. (See Section III D and Figure 12.)

8. Based on preliminary information obtained with a new

dynamic skin test device, even the least hazardous of

the present set of Moore penetrometer tips punctures

pigskin under impact conditions that are easily achieved

by the hands of children age 8 years. Probably the tips

would also puncture human skin under the same conditions.

(See Section IV B.)
5

DISCUSSION

This technical progress report describes new information

obtained since the publication of NBS Report No. 10,8 39 dated

April 27, 1972. It covers material from several areas of

interest but is not intended to be an all-inclusive or final

report

.

Discussion is divided into the following topics:

I. Mechanical Properties of Human Skin

A. Tensile Properties

B. Static Puncture Resistance

II. Pendulum Skin Test Device Development

A. Hand Velocity and Weight Measurements

B. Pendulum Design

III. Cutting Tests of Pigskin with Sheared Steel Edges

A. Test Edges

B. Test Tissue

C. Test Method

D. Test Results

IV. Continuing Activities

A. Improved Test Methods

B. Dynamic Skin Puncture Test Results (Preliminary)

C. Easy-Open Food Containers

D. Basic Skin Properties

V. References
6

I. MECHANICAL PROPERTIES OF HUMAN SKIN

A . Tensile Properties

Among the technical papers discussed by McGuire

and Moore (1972) was one by Holzmann, Korting, Robert,

and Vogel (1971) that described the thickness, breaking

force for 5mm width, percent elongation, and modulus

of elasticity of skin from the thigh and over the

sternum of 52 unembalmed cadavers of various ages.

These data, as published, were grouped into age

categories. In response to an NBS request, co-author

H. G. Vogel furnished detailed information on each

skin specimen tested during the study described in

that paper.

Of the data furnished by Vogel (19 72) , those from

the 14 youngest cadavers are represented in Figures 1

and 2 . They indicate that the force required to break

a 5mm wide skin specimen roughly doubles during the

first year of life. After the first year, change is

more gradual

.

McGuire and Moore (1972) had postulated that skin

puncture force bore a certain relationship (Figure 32

of that report) to skin breaking strength. Also, it

was shown that average skin breaking force for

children in the 0-10 year age group was approximately

equal to skin breaking force for persons in the 60-70
7

year age group for many parts of the body. It was,

therefore, concluded that the skin puncture data

obtained from older cadavers were approximately equal

to those that would have been obtained from younger

cadavers. On the basis of the data provided by

Vogel (1972) , it still appears that this might hold

true, but only down to about one year of age.

B. Static Puncture Resistance

McGuire and Moore (1972) presented preliminary

results from a study of human skin resistance to

puncture under low velocity, or essentially static,

conditions. In the study, the puncture resistance of

skin from five locations on 21 unembalmed cadavers

was measured using the nine different penetrometer tips.

This work, which was performed by W. H. Graham of the

Office of the Chief Medical Examiner of the State of

Virginia, is now complete.

The five skin test locations used in this study

were selected primarily on the basis of their vulnerability to injury and the fact that average skin

strength was expected to be measurably different in

each location. In one location, the neck, measurements were also made of the puncture resistance of the

skin backed up by the platysma, which is a thin sheet

of muscle which forms a part of the subcutaneous
8

tissue in that area. The cadavers used, described in

Figure 4, were simply those that became available for

research use during the study, and were not specially

selected. The penetrometer tips used, shown in

Figure 3, were selected because previous work had

indicated that they would best help define the puncture

force regions of greatest interest in the study.

To measure the skin puncture force, an incision

was made in the cadaver skin at the desired location

and a lead-surfaced spatula blade was inserted under

the skin. The appropriate penetrometer tip was

mounted in a hand-held force measuring device. The

penetrometer tip was pressed perpendicularly through

the skin until it made contact with the lead surface,

completing an electrical circuit and causing a small

light bulb to go on. At this signal the operator read

the force-indicating dial on the force-measuring device.

The lead-surfaced spatula blade was intended to

simulate the effect of human bone just beneath the skin.

This test condition was chosen because previous tests

reported by McGuire and Moore (1972) had indicated that

skin was more vulnerable to puncture when backed by a rigid surface than when backed by resilient muscle or

other soft tissue. Therefore, the test condition represented a "worse case" condition from the standpoint of

skin puncture. A lead surface was used rather than bone
9

so that the electrical signal could be used to indicate

complete puncture. The test equipment and method are

more fully explained by McGuire and Moore (19 72) . The puncture force data obtained are shown in

Figures 5 and 6. Except for the measurements made on

the neck skin with platysma, the data were analyzed

statistically by the NBS Applied Mathematics Division

using the NBS-developed OMNITAB II computing system

described by Hogben, et al (1971) . (OMNI TAB II is

available outside NBS; see Hogben, et al 19 70.) The

following two paragraphs may be of particular interest

to those versed in statistical theory.

An analysis of variance was made, treating the

experiment as a two-way nested design without

replications. That is, "penetrometer tips" and "bodies"

were treated as independent variables with "body

locations" nested within "bodies." Since there were

no replications, there was no direct measure of

experimental error as such. In the absence of a direct

measure of experimental error, the tips x locations

within bodies mean square, 1.83, could be used as an

estimate of error variance with 6 72 degrees of freedom.

This would only be valid if, in fact, there were no

interaction. This is not a realistic assumption.

Results of the analysis are shown in conventional

form in Figure 7. Measured differences between tips,
10

between bodies, and between locations within bodies were

all found to be significant at the .01 significance level

This indicated that the measured differences were primarily due to purposeful changes in test conditions

rather than random variations in materials or methods

.

For each of the five body locations, data obtained

from the 21 cadavers using the 8 Moore penetrometer

tips were examined and found to describe series of

constant-force curves approximating sections of

ellipses. Therefore, computations were made to

determine the values for constants that would provide

least-squares fits between the puncture force data

and the following general equation for an ellipse:

2 2

y = u + ax-j_ + bx2 + cx^ + dx2

where y

= puncture force, kg

x-^ = tip angle, degrees (see Figure 3)

X2 = tip radius, mm and

u, a, b, c, d = constants

Results of these computations were as follows:

Body Least Squares Estimates of Constants

Location

Forehead

Cheek

Scalp

Forearm

Neck

u

1.5731

1.8688

1.9421

1.8669

1.2223

a

.04417

.00952

.02448

.00749

-.00712

b

-1.9811

-0 .4453

-0.7072

-0 .9636

+1.6636

c .000447

.000826

.000851

.000872

.001326

d

18 .7539

13.9832

18 .2296

21.2810

22 . 3977
11

These values were then used in the general

equation to compute sets of values for x-^ and x

2

for

the condition where puncture force y = 7.5 kg . The

resulting curves are shown in Figure 8 . A curve

previously estimated by McGuire and Moore (1972) is

also shown in this figure. The 7.5 kg force level

selected was based on children's grip strength, and

will be discussed later in this section.

Since each of the five curves shown in Figure 8

represents all the measurements made at one body location on 21 cadavers by 8 Moore penetrometer tips, each

curve might be considered to be an "average" 7.5 kg

puncture force curve for a given body location. However, the range of puncture force values obtained with

any one penetrometer tip at a given body location

varied widely, as shown in Figures 5 and 6. This

variation was due to the combined effect of natural

differences between cadavers and experimental error

in measuring puncture forces. Of these two factors,

natural differences between cadavers probably produced

the greatest variation. The fact that no measurements

were repeated, however, prevents calculation of the

proportion of the total variation attributable to

each cause.
12

Computations were made to determine the 9 5%

confidence interval for measurements made at any one

body location by any one Moore penetrometer tip,

considering variation due to the combined effects of

body differences and measurement errors. As an

example, as shown in Figure 5 the mean value for all

puncture force measurements made with the 60 degree,

.41mm Moore tip on the foreheads of the 21 cadavers

was 8.1 kg. A 95% confidence interval for a single

measurement is 8.1 +3.9 kg based on 16 degrees of

freedom. In general, the confidence limits were

nearly identical for all tips at each body location,

but quite different between body locations. The

calculated values for 95% confidence limits, rounded

to the nearest 0.1 kg, were as follows (mean values

indicated refer to those shown in Figures 5 and 6 for

each tip)

Forehead mean value for individual tip + 3.9 kg

(range of means 3.5 to 8.1 kgY

Cheek mean value for individual tip + 3.1 kg

(range of means 3.3 to 7.5 kg)

Scalp mean value for individual tip + 5.7 kg

(range of means 4.0 to 9.4 kg)

Forearm mean value for individual tip + 3.9 kg

(range of means 3.9 to 9.4 kg)

Neck mean value for individual tip + 4.0 kg

(range of means 4.0 to 10.7 kg)
13

The calculated confidence intervals are very

large, but this is not unusual for data representing

measurements of biological attributes. The fact

remains that the curves in Figure 8 are still

reasonable estimates of the puncture resistance of

human skin.

The 7.5 kg force level used in the curves in

Figure 8 was based on the grip strength of children

5 years of age as described by Krogman and McCown (19 71)

.

If grip strength is a valid criteria, it is not unreasonable to think that children of less than 1 year of age

would be able to exert much less force on an object and

the fact that their skin is weaker would be at least

partly balanced by their lesser strength. However, we do

not now have enough data to adequately define this trade-o

It should be noted that although the puncture

force work to date has dealt with essentially static

conditions, future work may indicate that dynamic

conditions are of greater importance. With the

present data serving as a foundation, work is now being

done to determine the effects of dynamic interactions

between body parts and sharp points and edges. As

discussed in greater detail in Section IV B, early

indications are that points that will not puncture

human skin at the 7.5 kg static force level will puncture skin under dynamic conditions that can easily be
14

achieved by children's hands. It is not yet known

whether this is simply due to the greater forces

involved or whether other dynamic effects are also

significant

.
15

PENDULUM SKIN TEST DEVICE DEVELOPMENT

A . Hand Velocity and Weight Measurements

This phase of the toy safety program is primarily

concerned with hazards encountered during ordinary play

conditions as opposed to either essentially static

conditions or very high energy situations. Therefore,

the dynamic problems associated with hand-toy impact

comprise one appropriate area for analysis.

Many of the factors affecting the degree of hand

injury caused by a hand-toy impact can be discussed

from an engineering viewpoint,, For example, toy

characteristics such as configuration, mass, and

rigidity must be considered significant, with toys

having sharp points or edges, high mass and high

rigidity tending to produce the greatest injury in a given impact situation. Likewise, the mass, velocity,

and resilience of the hand must be considered significant factors. However, the dynamic characteristics of

the hand are particularly difficult to measure. One

problem is that the supporting tissue under the skin

varies greatly. On. the knuckles, where there is

little soft subcutaneous tissue, a given impact velocity

will tend to produce high decelerations and high

impact forces. Areas having a substantial amount of

soft tissue under the skin will tend to produce lower

decelerations and lower impact forces.
16

In order to make a first attempt at simulating

some hand-toy impact conditions, a search was made for

information on typical hand travel velocities and masses.

Hand and forearm velocities (up to 4.4 meters/second

during controlled movement) and weights are described

by Damon, Stoudt, and McFarland (1966), but their data

are all for adults. No published data on children were

found, so measurements were made by the Product Evaluation Technology Division to determine typical values

for children's hand velocities. Two miniature photo

diodes mounted one inch apart were used to measure the

hand velocities achieved by five subjects of various

ages under two conditions. Maximum velocity measured

was obtained by a downward "karate chop" motion past the

photo diodes. Maximum grabbing velocity was measured

during a quick horizontal grabbing motion from a standing

start toward an object about 45cm from the starting

position. The effective weights of the subjects' hands

were then measured. This was done by placing their

arms in the position where the elbow joint supported the

upper (proximal) end of the forearm, and the hand was

supported by a scale. Thus, the weight measured was

equal to the hand weight, plus approximately one-half

of the forearm weight.
17

Hand velocities and effective weights measured

were

Subject

Age

Years

Karate Chop

Velocity

Meters/sec

.

Quick Grab

Velocity

meters/sec

.

Effective

Weight

iss

2 4.2 .2 (est.)

5 6.4 2.1 .3

8 7.3 2.5 .6

Adult (2) 12.7 4.2 2.0

B. Pendulum Design

A test device was built that was intended for

use in simulating a variety of child-toy impact

conditions. This device, shown in Figure 9, featured

a light-weight pendulum arm long enough to produce

impact velocities of up to the value of the maximum

"quick-grab" velocities measured and a pivoted carrier

to which various sharp edges or points could be

attached. The pendulum head could be weighted to

simulate the weight of a hand or other body part.

The device was built with the tissue test specimen

held stationary and the test edge movable so that it

could be used for tests on human skin without the

necessity of removing tissue specimens from the

cadavers. However, this was never done.

The tissue test specimen shown in Figure 9 is

chamois skin. Wet chamois skin was used in development
18

of the test device, and some tests were later made

using fresh pigskin.

The pendulum test device provided a useful first

approximation of some possible hand-toy impact

conditions and was used for the series of tests

described in Section III of this report. However,

the interactions between the pendulum components and

the test tissue were extremely complex. For example,

higher pendulum release heights produced both higher

cutting velocities and higher impact forces. It

seemed unlikely that the relative effect of velocity

and force, for example, could be determined without

complex instrumentation. Also, successful use of the

device depended on careful setting of edge impact

angles and points of impact. Therefore, the device

has been abandoned, and a "free-fall" drop test device

is now being developed. The new device is further

discussed in Section IV.

A satisfactory method for describing edge

characteristics has not yet been found, though several

ideas are being considered. Probably the most promising

is a technique that would utilize a profilometer of

the type ordinarily used to measure surface roughness.

In place of the usual pointed stylus, a chisel-shaped

stylus that could be passed over any edge would be
19

used. Edge roughness might be expressed in terms of

root mean square deviation from a given line, or by

other appropriate terminology.
20

III. CUTTING TESTS OF PIGSKIN WITH SHEARED STEEL EDGES

A . Test Edges

One of the specific problems facing the Bureau

of Product Safety is determination of the hazard

potential of toys made in whole or in part from thin

steel components having unprotected sheared edges.

BPS furnished a number of toys, including cars, mechanical animals, a xylophone, and a toy umbrella with

sheared and formed steel ribs and handle, as examples

of this problem. Sheared sheet steel edges were chosen

as the most appropriate starting point for the edge

evaluation work.

A set of sixteen sheared sheet steel edges was

made in the general form shown in Figure 10. Characteristics of the edges were as described in Figure 12.

Note the following variations:

1. The edges were made of 0.4 , 0.6 , and 1 . 5mm

thickness steel.

2. Half of the edges were "0 degree" and half were

"37 degree" as defined in Figure 10.

3. Six of the edges were sheared on a "rough," very

poor shear. Eight of the edges were sheared on

a "good," well-maintained shear. Two of the edges

were sheared on an "excellent" shear, which was

actually just a relatively unused portion of the
"good" shear. The better conditions of the shear

produced the smaller wire edges on the sheared

material

.

4. After shearing, ten edges were left as sheared.

Two edges were given 10 strokes on a fine stone,

which removed the sharpest or "toothiest" part

of their wire edges. Four edges were given 20

strokes on a fine stone, which removed their wire

edges entirely and left smooth edges.

Neglecting for the moment the variables of edge

angle and steel thickness, the various combinations

of operations described above produced the four

subjectively distinct types of edges illustrated in

Figure 13. These are:

Type A. Smooth square edge. Feels sharp but smooth

to touch. The best possible shear might

approach, but would probably not attain, an

edge of this smoothness. Test edges 8, 12,

14, 16.

Type B. Rough fine wire edge. Feels rough to touch.

Typical manufacturing quality, similar to

edges on most toys. Test edges 1, 2, 7, 11.

Of slightly better finish are test edges 3, 4

Type C. Smooth irregular wire edge. Feels irregular

to touch but does not catch on skin. Similar
22

to a rough shear job finished by tumbling.

Test edges 6, 10.

Type D. Rough irregular wire edge. Feels jagged to

touch a Much rougher than typical manufacturing quality. Test edges 5, 9, 13, 15.

B . Test Tissue

Because of the similarities between pigskin and

human skin as described by McGuire and Moore (19 72)

,

pigskin was selected as the test tissue for the first

test series. Fresh pigskin having an average thickness

of 3.2mm was obtained from a local meat supply house

and used within 48 hours. It had previously been found

that pigskin is most vulnerable to puncture when it has

a rigid backing simulating bone. It was thought that

this would also be true with regard to vulnerability to

laceration, particularly under dynamic conditions

where use of the rigid backing would result in higher

decelerations and higher impact forces. Therefore,

the pigskin specimens were mounted directly over the

plywood specimen holder, much like the chamois is

mounted in Figure 8, except that a thin plastic sheet

was used to prevent absorption of grease by the

plywood

.

C. Test Method

The pendulum head was weighted so that total

pendulum weight was .56 kg. Since the pendulum center
23

of gravity was 42.5cm from the pendulum pivot and the

edge carrier pivot was 52.5cm from the pendulum pivot,

a vertical force of .45 kg at the carrier pivot could

hold the pendulum arm in a horizontal position. This

.45 kg force was called the "effective weight" of the

pendulum. The "effective weights" of children's

hands had previously been found to be .3 kg and .6 kg

for 5 and 8 year olds, respectively. Therefore, it

was thought that for a given test velocity, the amount

of energy available at impact with the pendulum would

be less than, and probably only about 75 percent of,

that available in the hand of an 8 year old at the

same velocity. However, precise measurements of

moments of inertia and centers of percussion were not

attempted on either the pendulum or the children's

hands

.

The edge carrier was set to bring the edge into

contact with the test tissue at an angle of 15° to the

direction of travel, and to ride over the tissue in the

manner shown in Figure 11. One series of tests was run

with the carrier spring installed, and one series was run

with it removed. (This spring, which produced a force

of about 1.5 kg at full compression, can be seen in the

photographs in Figure 11.) Since the carrier complete

with edge weighed only .13 kg, the test conditions,
24

particularly for tests without the carrier spring, were

thought to be far less severe than actual conditions

involved in hand-edge impacts at 15° impact angles.

Before the tests, the pendulum arm was released

from various initial angles, and the velocities achieved

at the impact point were measured by means of photo

diodes. The resulting plot of velocity vs. release

angle was used to determine test impact velocities.

The higher impact velocities, of course, tended to be

accompanied by higher impact forces and decelerations.

However, since force and deceleration were not measured,

test results are presented in terms of impact velocity.

To determine the minimum impact velocity at which

each test edge would cut pigskin, about 300 trials were

made. For each edge and each test condition (with

spring or without spring) , the pendulum was released

from at least three different initial angles, with three

trials at each angle, using a different skin specimen

area for each trial.

Test Results

Minimum impact velocities at which the 16 test

edges would cut rigidly-supported pigskin are shown in

the last two columns of Figure 12. The following

comparisons can easily be made:

1. "With spring" versus "without spring" conditions

.

Compare the "with" and "without" columns of results.
The addition of the carrier spring force reduced

required velocity to cut for most edges. This effect

was reversed for edges 6 and 16, the two dullest

edges. Overall, the effect of the spring force was

small

.

"0 degree" edge versus "37 degree" edge. Compare edges

2 with 1; 4 with 3; and 9, 10, 11, 12 with 5, 6, 7, 8.

In every case the 37 degree edge required a lower

velocity to cut than the 0 degree edge. It was thought

that for very thin material there would be little

difference between 0 degree and 37 degree edges, but

apparently this would require a metal thickness of

less than 0.4mm.

0.4mm versus 0.6mm versus 1.5mm metal thickness.

Compare 0 degree edges 8 with 14 with 16. Compare

37 degree edges 9 with 13 with 15. For the 0 degree

edges, thicker material required greater velocity to

cut, presumably because of the increased bearing area

between edge and tissue. For the 37 degree edges

there did not appear to be any significant variation

in velocity required to cut with metal thickness.

Type A versus Type B versus Type C versus Type D

edges. Compare the 0 degree edges 8 with 7 with 6

with 5. Compare the 37 degree edges 12 with 11 with

10 with 9. For both edge angles, the Type C, smooth,
26

irregular edges required the highest velocity to

cut. The Type D rough, irregular wire edges and

Type A smooth, square edges required about half of

the velocity of the Type C edges. The Type B rough,

fine wire edges required the lowest velocity to

cut. The Type B+ edges 3 and 4 required about the

same velocity to cut as similar Type B edges.

As discussed in Section II A, measured hand

velocities for a five-year old child were 6.4 meters/sec

for a "karate chop" and 2.1 meters/sec. for "quick grab.

Maximum hand velocities increase with age. The

velocity required to cut pigskin with an edge sheared

on a poor, good, or excellent shear and not given further finishing operations was less than .75 meters/sec.

for corner contact (37 degree edges) , even with low

dynamic forces as discussed in Section III C. Human

skin is less resistant to puncture than pigskin and

is believed to be less resistant to laceration. Therefore, it appears at this time that any toy having

exposed, unfinished, sheared sheet steel edges could

cut a child's skin under easily obtainable impact

conditions

.
27

IV. CONTINUING ACTIVITIES

A. Improved Test Methods

The pendulum skin test device described in

Section II B did not prove to be satisfactory,

primarily because interactions between pendulum

components and the test tissue were complex and

difficult to analyze. Because of this, a different

experimental approach is now being used. It's chief

features are:

1. A less complex impact test device has been built

and is now being used to simulate impact conditions

resulting from child-toy interactions.

2. An essentially constant speed test device,

utilizing a machine lathe to bring test edges and

test tissue into contact under closely controlled

conditions, is being developed to investigate the

relative effects of pressure and velocity in skin

cutting. This device will first be used to cut

human skin and various synthetic materials in an

attempt to find a material that simulates the

reaction of skin to cutting.

3. Arrangements have been made to obtain specimens of

human skin for testing in NBS laboratories.

The new test equipment and methods, just now

coming into use, will be fully described in future

progress reports.
28

Impact Skin Puncture Test Results (Preliminary)

The impact test device now in use is a drop test

device capable of approximating the hand weight and

velocity conditions discussed in Section II A. In

the course of developing this device, some measurements

were made of the puncture resistance of pigskin under

impact conditions. The results, though preliminary,

are of sufficient importance to present at this time.

The test device was used to produce impacts

between Moore penetrometer tips and rigidly supported

pigskin at angles of 87, 45, and 30 degrees. Three

relatively non-hazardous Moore penetrometer tips were

used, each point being installed in a circular drop

head with about 3.0mm of the point protruding from

the head. Thickness of the pigskin used was about

2.0mm. The drop head was released from various

heights, producing impact velocities of up to 2.4 meters/

sec. (as reported in Section II A, the "quick-grab" hand

velocity of an 8 year old child is about 2.5 meters/

sec). The higher impact velocities, of course,

produce higher impact forces, but no force estimates

have yet been made. Results of the test drops were

as follow:
29

Impact

Angle

,

deg.

Tip

Angle

,

deg.

Tip

Radius

,

mm

Impact Velocity

Req ' d for Puncture,

meters/sec

.

87 15 .80 2.4

90 . 05 2 . 0

120 .05 2.4

45 15 .80 1.4

90 .05 >2.4

120 .05 >2.4

30 15 .80 2.0

90 .05 >2.4

120 .05 >2.4

No attempt at detailed analysis of the preliminary

test results will be made in this report. However, one

significant aspect of the results is that even the

least hazardous Moore tips punctured the pigskin under

impact conditions that, it is thought, could easily

be achieved by the hand of an 8 year old child. Since

it was reported by Moore and McGuire (1972) that pigskin is more resistive to puncture than human skin

under low velocity conditions, it is probable that

pigskin is also more resistive to puncture under higher

velocity conditions. In that case, the test conditions

used in these tests would also have resulted in the

puncture of human skin. Therefore, even the least

hazardous Moore penetrometer tips could be expected to

puncture children's skin under rather ordinary impact

conditions. This problem is being given further

consideration

.
30

C . Easy-Open Food Containers

A specific problem important to BPS is the

presence of sharp edges on the top and within the upper

rim of various types of easy-open food cans. It is

desirable to evaluate some can designs in the near

future, before the general investigation of skin

mechanical properties can be completed. Attempts are

now being made to develop a simple device that will

provide an interim method for evaluating several

specific can designs.

D . Basic Skin Properties

PETD is sponsoring a histological investigation

of basic skin properties by the University of Virginia

School of Medicine. Up to the present, this investigation has not produced any findings affecting the values

of skin puncture and laceration resistance described

in this series of reports. Results of the investigation will be given in a future NBS report.
31

J. REFERENCES

1. Damon, A., Stoudt, W. W. , and McFarland, R. A. "The

Human Body in Equipment Design." Harvard University

Press, Cambridge. Second Printing (1971).

2. Graham, W. H. Data on puncture properties of skin

from 21 cadavers. Private correspondence (1972).

3. Hogben, D., Peavy, S. T . , and Varner, R. N. "OMNITAB II

Magnetic Tape and Documentation Parcel." NBS Tape 1,

National Technical Information Service, Springfield,

Virginia (1970) .

4. Hogben, D., Peavy, S. T., and Varner, R. N. "OMNITAB II

User's Reference Manual." National Bureau of Standards

Technical Note 552, U.S. Government Printing Office,

Washington, D.C. (1971)

.

5. Holzmann, H. , Korting, G. W. , Kobert, D . , and

Vogel, H. G. "Mechanical Properties of Skin in Relation

to Age and Sex." Orchiv. Fur Klinische and Experimen telle

Dermotologie, 239 , 355 (1971)

.

6. Krogman, W. M. , and McCown, T . "The Manual and Oral

Strengths of American White and Negro Children, Age 3-5

Years." Philadelphia Center for Research in Child Growth

(1971)

.

7. McGuire, B. J., and Moore, J. D. "The Skin Puncture

Potential of Points Associated with Certain Toys."

National Bureau of Standards Report No. 10,839 (1972).

8. Moore, J. D. "A Method for Evaluating and Testing the

Sharpness of Points." National Bureau of Standards

Report No. 10,673 (1972).

9. Vogel, H. G. Detailed data on tensile properties of

skin from 52 cadavers. Private correspondence (1972).

I

RANGE OF VALUES FOR SPECIMENS FROM ONE CADAVER

55

100

z

0" 80

o z

ISN AK 60

ui ijj \—X CD 40

Ld

UJ

_J OR 20

u_ TO

UJCO 0

0 15

AGE, YEARS

IL. O

CO

_l

Z)QO

CME

E

O

h-

<

_J

LjJ 10 15

AGE, YEARS

Figure 1. Human Skin Thickness, Breaking Force, Total Extension

and Modulus of Elasticity vs. Age, for Skin Over Sternum.

From Vogel (1972).

CO

£

£

COCO

hJ

z

o

I

J

RANGE OF VALUES FOR SPECIMENS FROM ONE CADAVER

3

-

2 -

oL

100

X 1

10 15

AGE, YEARS

10 15

AGE, YEARS

20 25

Figure 2.

10 15

AGE , YEARS

Human Skin Thickness, Breaking Force, Total Extension

and Modulus of Elasticity vs. Age, for Skin from Thigh,

From Vogel (1972)

DIMENSIONS OF MOORE PENETROMETER TIPS

TIP RADIUS TIP ANGLES DEC

in. mm 15 30 45 60 75 90 120

.002 .05 X X ® X X X X

.004 • 10 X X ® X

.008 .20 X f

X X

.012 .30 d> X X X

.016 41 X ® ® X

.024 .61 X X X

.032 .81

® PENETROMETER TIPS SELECTED FOR USE IN CADAVER TESTS

DIMENSIONS OF MODIFIED GADD PENETROMETER TIP

Figure 3. Geometry of Penetrometer Tips Used in this Study.

u -K

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15

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45

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15

15

45

45

45

60

60

75

Description of Tip Puncture Force, kg

Angle Radius Cadaver No. Degrees mm 219 227 228 229 230 232 234 235 236 238 239 245 246 249 250 251 252 253 254 265 266 Mean

1 ^ 0. 30 1 .

2. 7 2.3 3.2 3.2 3.2 4.5 2.3 4.5 2.7 4.5 3.2 4.5 3.2 4.1 4.1 3.6 4.1 3.6 5.0 2.3 3.5

0. 61 5.

5.9 10.

9.5 7. 3 9.

10.9 7.3 4.5 4.5 9.1 10.9 9.1 9.5 10.9 7.7 7.7 6.8 10.9 5.5 6.8 8.1

0. 05 1.8 1.4 4 .

2.3 3.2 5.9 5.5 3.6 3.6 3.6 4.5 5.5 5.5 3.2 10.0 3.2 5.9 4.5 4.1 5.5 6.4 4.5 45 0.20 2.3 2.7 6.4 3.6 4.5 5.5 5.0 3.2 3.2 4.1 6.8 5.0 4.1 3.6 8.2 3.6 6,8 4.1 4.1 4.5 4.6

45 0.41 2.7 3.6 7.7 7.7 8.2 8.6 10.9 5.9 5.0 3.6 5.5 8.6 6.4 9.1 12.3 6.8 6.4 6.8 5.0 7.3 7.3 6.9

60 0.20 3.6 3.6 6.4 9.5 7.7 9.5 7.7 6.8 4.5 3.6 10.0 5.0 5.9 5.0 10.0 6.8 5.9 5.5 4.5 5.5 5.5 6.3

60 0.41 4.5 5.5 7.7 10.5 8.6 10.5 9.1 9.5 4.1 7.3 12.3 10.5 10.0 6.4 11.4 7.3 6.8 7.3 5.9 8.2 6.8 8.1

75 0.10 5.5 5.9 7.7 6.8 7.3 11.8 7.3 4.1 5.0 5.5 10.0 9.1 6.4 6.4 13.6 8.2 10.9 4.5 5.5 6.8 6.4 7.4 Modified Gadd 2.7 3.6 5.5 5.5 5.9 9.1 6.4 6.8 3.2 3.6 10.0 8.2 7.3 5.9 10.9 5.9 6.4 7.3 6.8 5.5 4.5 6.2

15 0. 30 4 . 1 1.8 4.1 3.6 3.6 3.6 3.6 2.3 2.3 3 .

3.2 2.3 2.3 2.7 4.1 3.2 3.6 3.2 2.7 5.9 4.

3.3 15 0.61 6.8 6.8 10.0 6.8 7.3 4.5 8.2 5.0 4 .

5.0 10.0 7.7 8.6 5.0 11.8 4.5 7.7 7.7 4.5 10.0 8.2 7 .

45 0. 05 3.6 2. 3 4.1 4.1 5.5 6.8 3.2 3.6 2. 7 2.3 6.4 2.7 4.1 5.5 4.5 3.6 4.1 4.1 2.7 4.5 3.6 4.0

45 0.20 5.0 2.7 4.5 5.9 5.9 5.5 5.0 3.6 3.2 5.0 5.0 2.7 4.5 4.1 5.0 4 .

4.1 4.1 3.6 3.2 3.2 4.3 5

45 0.41 5.9 5.9 7.3 5.9 7.3 5.9 5.5 6.8 4.1 4.5 7.7 5.0 6.8 5.5 7.7 5.5 5.9 6.8 4.1 6.8 7.3 6.1 60 0.20 7.7 3.6 6.8 5.0 8.6 6.8 7.3 7.3 4.5 5.9 8.2 5.0 5.9 5.5 6.4 5.5 6.4 3.6 4.5 7.7 7.3 6.2 60 0.41 8.2 6.4 8.2 7.3 9.1 7.7 8.6 6.4 7.7 7.3 7.3 5.9 10.5 7.3 7.3 5.9 7.7 7.7 4.5 8.2 9.1 7.5 75 0.10 10.0 4.1 9.1 3.6 9.1 8.6 6.8 6.8 5.0 7.7 9.5 3.6 9.1 9.5 13.6 7.3 6.4 5.9 3.6 6.8 5.9 7.2 Modified Gadd 4.1 5.5 5.9 6.8" 6.8 4.5 5.9 5.5 4.5 6.4 6.8 4.5 9.1 5.5 6.8 4.

5.5 6.8 4.1 5.5 4.5 5.7

15 0. 30 2. 7 2.7 2.3 3.2 4.5 2.3 5. 5 2.3 1.4 2.3 6.4 5.0 3.6 3.6 6.4 5.0 5.0 5.0 4.1 5.5 5 .

15 0. 61 5.9 6.4 9.1 9.5 8.2 7.3 12.3 6.8 4.5 4.5 12.3 9.1 10.0 5.5 13.2 8.6 7.7 12.7 8.6 10. 9 11.8 Q a 45 0. 05 1.8 2.3 3.6 4.5 4.1 5.5 4.1 6.8 2.7 3.6 9.1 5.0 4.5 3.6 10.5 4.1 6.8 4 .

5.5 4.5 5 .

49

45 0.20 3.2 3.6 5.5 6.4 4.1 6.4 7.7 6.4 4.1 3.6 7.7 5.5 4.5 3.6 11.4 4.1 5.5 4.1 4.5 3.2 3.6 5.2 45 0.41 5.5 5.0 7.7 6.8 7.3 8.6 10.5 5.5 6.4 3.6 12.7 7.7 8.6 5.0 12.7 5.9 7.3 9.1 6.4 8.2 7.7 7.5 60 0.20 4.1 3.6 5.5 7.7 5.5 10.5 11.4 5.5 5.5 4.5 11.8 6.8 6.6 5.5 11.4 4.5 7.7 8.2 5.9 7.7 7.7 7.0

60 0.41 8.2 6.8 8.2 10.0 10.0 9.1 12.3 io.o 7.3 5.5 12.7 10.9 11.4 5.5 13.6 10.0 11.4 10.9 6.8 7.3 9.1 9.4 75 0.10 6.8 5.5 6.8 11.8 6.4 12.3 11.8 6.8 9.1 5.0 13.2 6.8 10.0 5.5 13.6 7.7 12.3 8.6 5.5 6.8 9.1 8.6 Modified Gadd 4.5 5.0 7.3 6.8 5.5 7.7 7.3 9.1 4.5 4.5 11.4 9.1 6.4 5.5 13.6+ 7.3 5.9 9.1 6.8 6.8 4.5 7.1

+ Force required was slightly above maximum force gage reading.

Figure 5. Force required to puncture adult human skin with Moore and modified Gadd Penetrometer tips. For forehead, cheek and scalp. From Graham (1972)

Descriptii

Angle

Degrees

15

15

45

rearr 45

45

o 60

60

75

Modif

i

nJ 15

)

Platysn 1545

45

45

60

>. 60

Necl 75

Modif i<

zysma 15

15

a) 45

45

,a 45 4-1 H 60

Neck

v 60

75

Modif ii

*Data w

"Figure

Description of Tip Puncture Force , kg

Angle Radius Cadaver No. Degrees mm 219 227 228 229 230 232 234 235 236 238 239 245 246 249 250 251 252 253 254 265 266 Mean

15 0.30 3.6 2.3 3.6 4.5 4.1 2.7 3.2 3.6 2.7 2.7 5.0 4.5 5.5 4.1 4.5 3.2 4.1 5.0 3.6 4.5 4.1 3.9 15 0.61 6.4 5.5 9.1 8.6 9.1 11.8 7.7 10.0 8.6 9.1 11.4 10.5 12.7 9.1 10.5 10.0 10.0 10.0 9.1 9.5 9.5 9.4

- 45 0.05 4. 5 2.3 5.5 2.7 5.0 5.9 3.6 4.5 2.7 5.0 6.8 3.2 3.6 2.7 5.0 3.2 4.1 3.6 4.5 4.5 2.7 4.1

45 0.20 3.2 3.2 3.6 3.6 3.2 4.1 3.6 6.4 2.7 5.5 7.7 3.2 3.6 4.1 8.6 2.7 6.8 4.5 3.6 3.2 3.2 4.3

g 45 0.41 7.3 3.6 8.2 7.3 6.8 6.8 6.4 6.4 4.5 9.1 9.1 6.8 6.8 8.2 10.0 5.9 8.6 9.1 5.9 10.0 9.1 7.4 60 0.20 5.5 2.7 10.0 5.5 6.4 5.5 3.6 9.1 4.1 5.9 11.4 5.5 5.9 5.5 11.4 4.5 4.5 5.0 5.0 7.3 '4.5 6.1

60 0.41 7.3 4.5 7.3 7.7 9.5 11.4 7.3 10.9 5.0 10.0 12.7 5.0 10.5 10.5 13.2 11.4 8.6 8.2 10.0 4.5 4.1 8.6

75 0.10 8.6 4.5 7.7 4.5 5.9 6.8 5.9 8.6 6.4 5.5 13.2 4.1 7.3 10.5 13.6+ 8.2 9.5 7.7 5.5 6.4 6.4 7.5 Mod If 1 ed Gadd 4.5 3.6 5.5 6.8 6.8 6.8 5.5 5.0 1.8 5.5 10.0 6.4 10.9 8.2 11.8 6.8 4.5 9.1 5.5 4.5 4.1 6.4

B

15 0.30 4.5 4.1 4.5 4.5 4.1 3.6 4.5 4.1 3.2 5.5 3.6 3.2 2.7 3.6 3.6 4.1 3.2 3.6 3.6 5.9 4.5 4.0

15 0.61 10.9 10. S 12.7 10.5 12.7 11.8 9.1 13.2 11.8 10.9 9.1 13.2 10.9 7.7 13.2 9.5 9.5 10.0 7.7 10.5 10.0 10.7

-t 45 0.05 i.e 0.9 5.5 1.8 4.1 5.5 3.2 5.5 1.8 5.0 8.2 3.6 2.7 3.2 3.6 1.8 4.5 4.1 3.2 5.9 5.5 3.9 H 45 0.20 4.1 3.2 6.4 3.2 3.2 4.1 6.8 5.0 2.3 4.5 4.5 4.1 3.6 4.1 5.0 4.5 5.0 3.2 3.2 3.2 4.1 4.2

45 0.41 7.3 5.9 11.6 5.5 8.2 8.6 11.4 9.1 6.8 8.6 8.6 10.0 6.4 7.7 11.8 6.8 6.4 6.4 5.9 10.0 10.0 8.3 > 60 0.20 8.2 3.2 10.5 6.4 6.8 8.6 8.2 6.8 4.5 7.7 12.7 7.3 4.5 6.4 12.3 6.8 5.9 4.1 5.0 9.5 9.1 7.4

60 0.41 8.6 7.3 10.9 8.6 10.0 13.2 9.5 11.8 10.5 11.8 4 .

5

10.9 12.7 9.1 13.6+ 13.2 7.7 7.3 8.2 8.2 9.5 9.9

75 0.10 9.5 4.5 9.1 5.9 7.7 9.1 12.3 9.1 6.2 7.7 6.8 3.6 4.5 13.6 13.6 9.5 12.3 6.4 4.5 10.0 8.2 8.4 z Modifi id Gadd 3.6 3.6 9.5 4.5 5.5 12.3 5.5 7.7 4.5 6.4 10.0 7.3 5.0 13.6 3.6 6.4 7.7 4.1 9.1 9.1 7.1

E 15 0.30 6.8 4.5 5.5 4.1 4.1 5.5 8.2 5.0 4.5 2.7 4.1 5.0 3.6 3.6 4.1 3.6 7.3 5.9 4.9

15 0.61 12.3 10.0 11.4 13.2 13.6+ 12.7 12.7 12.3 13.2 11.4 10.9 13.2 13.2 9.5 10.0 7.7 12.7 11.4 11.7 45 0.05 6.4 2.3 4.5 3.6 5.9 5.5 6.8 7.7 3.2 2.7 4.5 6.4 2.3 6.4 4.5 3.6 7.7 6.8 5.0 45 0.20 7.3 10.0 6.4 9.5 6.8 6.4 5.9 7.3 5.0 3.2 5.0 5.5 5.5 5.9 4.5 4.1 4.1 4.5 5.9 45 0.41 11.8 10. 5 8.2 10.0 9.1 10.5 10.5 10.5 8.6 6.4 9.1 11.8 8.2 8.2 8.2 6.8 11.8 12.7 9.6 60 0.20 9.5 6.4 8.6 11.8 11.8 8.2 9.1 9.1 4.5 4.5 7.7 13.6 5.9 7.7 4.5 5.5 10.5 10.5 8.3

3 60 0.41 10.9 8.6 10.5 13.6+ 11.8 13.2 12.7 13.2 11.8 9.5 10.0 13.6 8.2 9.1 7.7 10.5 11.4 11.0

75 0.10 10.0 7.3 8.2 9.1 13.2 11.8 11.4 11.8 4.5 5.5 12.7 8.6 13.2 8.2 4.5 11.4 10.0 9.5 Modified Gadd 10.5 7.7 8.6 13.6+ 5.9 L0.

9

7.3 5.0 7.7 6.8 13.2 6.4 5.5 10.0 7.7 11.4 11.4 8.8

not available + Force required slightly above maximum force gage reading.

Figure 6. Force required to puncture adult human skin with Moore and Modified Gadd Penetrometer tips. For forearm, neck without platysma, and neck

with platysma. From Graham (1972)

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• I «2 *3 .4 .5 06

TIP RADIUS, mm

.7 .8 .9

COMBINATIONS OF TIP ANGLE AND TIP RADIUS

USED IN TESTS ON 21 CADAVERS

* PREVIOUSLY ESTIMATED AVERAGE CURVE FOR

5 LOCATIONS (McGUIRE AND MOORE 1972)

© COMBINATIONS OF TIP ANGLE AND TIP RADIUS

COMPRISING THE COMPLETE SET OF MOORE

PENETROMETER TIPS

Figure 8. Combinations of Tip Angle and Tip Radius for Moore

Penetrometer Tips That Require a Force of 7.5 kg.

to Puncture Adult Human Skin. Data from Forehead,

Cheek, Scalp, Forearm, and Neck of 21 Cadavers.



0 DEGREE EDGE

JWIRE

-"EDGE

37 DEGREE EDGE —i > i >-

- 76.2 mm

SIDE

W!RE

EDGE

END

DRAWINGS ARE APPROXIMATELY- FULL SIZE

Figure 10. Typical Test Edges Used in Tests of Rigidly

Supported Pig Skin with Pendulum Test Device

Fisure 11. Typical action of edge and carrier of pendulum skin test

device during pigskin laceration tests.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Edge No. Thickness

Edge Annie Condition Shear of Edge as UsedEdge Type

(Fig. 12) Pig Skin Cut Velocity, m/sec. mm deg. Without Spring With Spring

1 0.6 37 Cood None Rough fine wire edge B .38 .38

2 0.6 0 Good None Rough fine wire edge B 1.15 .94

3 0.6 37 Excellent None Rough very fine wire edge B+ .38 .38

4 0.6 0 Excellent None Rough very fine wire edge B+ .94 .62

5 0.4 0 Poor None Rough irregular wire edge D 1.15 1.02

6 0.4 0 Poor 10 strokes Smooth irregular wire edge C 2.07 2.90

7 0.4 0 Cood None Rough fine wire edge B .51 .51

8 0.4 0 Good 20 strokes Smooth square edge A 1.15 1.09

9 0.4 37 Poor None Rough irregular wire edge D .74 .39

10 0.4 37 Poor 10 strokes Smooth irregular wire edge C 1.45 .74

LI 0.4 37 Good None Rough fine wire edge B .45 .39

12 0.4 37 Good 20 strokes Smooth square edge A .74 .67

13 0.6 37 Poor None Rough irregular wire edge D .58 .55

14 0.6 0 Good 20 strokes Smooth square edge A 1.21 1.15

15 1.5 37 Poor None Rough irregular wire edge D .58 .58

16 1.5 0 Good 20 strokes Smooth square edge A 2.54 2.91

|

Figure 12. Characteristics of Sheared Steel Edges Used in Laceration Tests of Rigidly Supported Pig Skin.

Type A. Smooth square edge.

Cut on good shear, fine stone

used to remove wire edge.

! Type B. Fine wire edge. Cut on good shear, no further

finishing.

Type C. Smoothed irregular

wire edge. Cut on rough shear,

fine stone used to remove small

irregularities

.

Type D. Irregular wire edge.

Cut on rough shear, no further

finishing.

Figure 13. Types of Sheared Steel Edges Used in Tests of

Rigidly Supported Pig Skin. Magnification 50X.

jrm NBS-114A (i-7t) U.S. dept. of comm. 1. PUBLICATION OR REPORT NO. 2. Gov't Accession

BIBLIOGRAPHIC DATA No. SHEET NHST-R 7^-12L*W

.TITLE AND SUBTITLE

Resistance of Human Skin to Puncture and

Laceration

5. Publication Date

6. Performing Organization Code

.AUTHOR(S)

B. J. McGuire, J. R. Sorrells, J. D. Moore

8. Performing Organization

NBSIR 73-123

.PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4110410

11. Contract/Grant No.

2. Sponsoring Organization Name and Address

Bureau of Product Safety, Food & Drug Administratior

Department of Health, Education, and Welfare

5401 Westbard Avenue

Bethesda, Maryland 20016

13. Type of Report & Period

C overe d -r —. x~ ^ \ Interim 1 4/27/72 - 10/30/72

14. Sponsoring Agency Code

). SUPPLEMENTARY NOTES

This report is a sequel to NBS Reports No. 10,673 and 10,839

>. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

Information is provided on the following topics:

1. Human skin tensile properties measured on 14 cadavers age

1 day to 25 years. Skin strength increases rapidly during

first year of life.

2. Human skin resistance to puncture by conical tips measured

on 21 cadavers age 45 to 89 years. Results described by

equations of form y

= u + axx + bx2

+ cx^ + dx^

.

3. Hand velocities and weights measured on 5 subjects age 5

to 50 years. Maximum measured velocity during "grabbing"

motion was 4 . 2 meters/sec s

4. Relative laceration ability of selected sheared steel edges

measured on pigskin.

5. Preliminary data on resistance of pigskin to puncture by

conical tips under impact conditions

.

. KEY WORDS (Alphabetical order, separated by semicolons) Adults; Bureau of Product Safety; Children;

xperimental Studies; Injury Potential; Lacerations; Mechanical Force; Mechanical

roperties; NBS; Punctures; Sampling; Sharp Edges; Simulation: Skin. (TIPS Thesaurus)

AVAILABILITY STATEMENT

I I UNLIMITED.

2 FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Price

USCOMM-DC 66244-P71
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