Boeing Commercial ._

Airplane Company _

Contract NASI-15025 _

This Report is Submitted in Compliance

With DRL Line Item Number 018 i'

$

FIRTH QUARTERLY TECHNICAL PROGRESS REPORT :a

19 July 1978 through 18 October 1978 _i

O. E. DespOt, Jr. _/

Program Administration and Data Manager

Approved by :

EHngSiY_ing Design Manager

Approved by:

Operat:ions Technology Manager

Approved b;,: _'__ _-_"_. _-_/_.

Director of Advanced Composites Programs
_ Boeing Commercial

Airplane Company

Contract NASI-15025 ;

r

FOREWORD

/

This report was prepared by the Boeing Commercial Airplane Company,

Ren_on, Washington, under Contract NASI-15025. It is the fifth quarterly

technical progress report covering work performed between 19 July 1978

and 18 October 1978. The program is sponsored by the National Aeronavtics and Space Administration, Langley Research Center (NASA-LRC).

Dr. H. A. Leybold is the Project Manager for NASA-LRC.

The following Boeing personnel are principal contributors to the program

during the reporting period: G. Ohgi, Design; R. Johnson, Structural

Analysis; M. Garvey, Manufacturing Specialist; D. Grant, Production

Manager; L.D. Pritchett, Technical Operations Coordinator; and D.V. Chovil,

Business Support Manager.

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Boeing AirplaneCommercial Company

Contract NASI-15025

SUMMARY

Activities related to development of an advanced composites stabilizer

f

for the Boeing 737 commercial transport are reported.

Activities include discussion of the design and weight status, stiffness

requirements, the finite element model, test programs, quality assurance,

and manufacturing produclblllty studies.

Design details of the graphite/epoxy components are virtually complete.

The major effort is now being expended on the metal and fiberglass

tralllng-edge components. The bending and torsional stiffness properties

were satisfactory for both stabillty/control and for flutter requirements.

The finite element model input geometry was revised to reflect the

latest changes to production drawings. The program is progressing as

scheduled.

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Boeing Commercial

._ AirpianL Company _"

Contract NASI-15025 ;"

TABLE OF CONTENTS

_ SECTION PAGE _,,.

FOREWORD iii ,_,

5 SUMMARY v

I LIST OF FIGURES AND TABLES viii

_ 1.0 INTRODJCTION 1-1

2.0 DESIGN AND ANALYSIS 2-i

2.1 DESIGN STATUS 2-1

2.1.1 Skin Panel Stiffener Material 2-1

_. 2.1.2 Production Drawing Preparation 2-2

: 2.2 ANALYSIS 2-2

_ 2.3 WEIGHT STATUS 2-3

3.0 DEVELOPMENT TEST PLAN AND STATUS 3-i

3.1 ANCILLARY TEST PROGRAM 3-1

4.0 OPERATIONS DEVELOPMENT 4-1

4.1 PRODUCIBILITY STUDIES 4-1

4.2 ANCILLARY TEST COMPONENT FABRICATION 4-3

4.3 QUALITY ASSURANCE DEVELOPMENT 4-6

4.4 MANUFACTURING VERIFICATION HARDWARE 4-6

5.0 REFERENCES 5-1

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Boeing Commercial ,_

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Contract NASI-15025

i

LIST OF FIGURES AND TABLES

FIGURE PAGE

4-5 Test No. 21, Stub Box-Showing Drilling of Titanium _

Strap on Front Spar 4-8

4-6 Test No. 21, Stub Box-Showing Bushing Hole Being .:

Bored in Graphite/Titanium Stackup of Rear Spar 4-8

4-7 Test No. 21, Stub Box--Showing Aluminum Trailing-Edge J

Ribs 4-9

4-8 Test No. 21, Stub Box--Showlng Rear Spar, Inboard

Closure Rib, and Aluminum Trailing-Edge Ribs 4-9

4-9 Test No. 21, Stub Box-Showing Front Spar, Aluminum

Nose Ribs, and Lower Skin in Place 4-10

4-10 Test No. 21, Stub Box--Showing Trailing-Edge

Fiberglass Closure Panel and Lower Skin in Place 4-10

4-11 Test No. 21, Stub Box--Showing Trailing-Edge Beam,

Rear Spar, and Graphite/Epoxy Ribs in Place 4-11

4-12 Test No. 21, Stub Box-Showing Front and Rear Spar,

Lower Skin Panel, and Ribs with Instrumentation 4-11

4-13 Test No. 21, Stub Box--Showing Upper Skin Panel

with Instrumentation 4-12

4-14 Test No. 21, Stub Box--Showing Rear View of Completed

Assembly 4-12

4-15 Test No. 21, Stub Box--Showing Front View of Completed

Assembly 4-13

4-16 Test No. 21, Stub Box--Showing Side View of Completed

Assembly 4-i3

TABLES PAGE

2-1 737 Advanced Composites Stabilizer Structure

Weight Comparison 2-4

3-1 100% Load Transfer Joint Test Results 3-2

3-2 50% Load Transfer Joint Test Results 3-4

3-3 Impact Test Results-Dry 3-9

3-4 Impact Test Results-Wet 3-10

3-5 Spar Chord Crippling Test Data 3-17

A . _
Boeing Commercial

Airplane Company

Contract NASI-15025 _

SECTION 1.0 _"

_4

INTRODUCTION '_

The escalation of Jet-fuel prices is causing a reassessment of technology _,

concepts and trades used in designing and building commercial airplanes.

The task is to incorporate fuel-saving concepts into commercial aircraft

design.

The potential weight savings and fuel reduction resulting from the use

of advanced composites in aircraft structure, especially primary structure,

_ are significant. However, the lack of technical confidence and cost

data has de,aye# their use in commercial aircraft.

Hardware programs conducted in a production environment are required to

establish and demonstrate the safety, operating-life characteristics,

and manufacturing cost of advanced composites primary structure.

,_ Boeing's approach to the problem is to obtain reliable production,

technical, and cost data bases by the integration of advanced composites

technology development under NASA contracts, which, when combined with

company effort, will accelerate the application of composites. This

approach =ddresses these data bases, and develops realistic production

costs in a co_nercial transport manufacturing environment. Program

emphases are directed toward developing the information needed to obtain

an early production commitment decision by management, and will be

conducted in a production environment.

Preliminary developments, as covered in the first quarterly report, were

devoted to conceiving, developing, and analyzing alternative design _"

|.

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Boeing Commercial

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Contract NASI-15025 _

SECTION 2.0

, DESIGN ANt ANALYSIS

2.1 DESIGN STATUS

; The design effort is continuing, with the detail design of graphite/epoxy

i components virtually completed. The major effort is now being expended

L on the metal and fiberglass traillng-edge components.

2 i.i Skin Panel Stiffener Material

W

The graphite/epoxy tapes previously used in the skin panel stiffener caps

have been replaced by graphlte/epoxy fabric of equivalent stiffness. The

current design and the previous design are shown in Figure 2-I. This change

.' resulted from warpage experienced In the skin panels for the stub box

(Test No. 21). A Boelng-funded study and verification program showed

that removal of graphite/epoxy tape from the stringer caps will minimize

warpage. The stub box skin warpage is described in Section 4.0.

?.

f 6 Pliu 0° rope Ply i'45 ° fabric f9 Plies 0° fabric 

(Onouulde)

\

3 Plies fabric _ 3 Plia falxic 3 Prim _br 3 PIIn fabriI _"'-

Ptwk_s Deign New Design ':

Figure 2. I. Skin PanelStiffener Section

2-1

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Boeing Commercial I

Airplane Company

Contract NASI-15025

; presented in Reference i have been evaluated by the Stability/Control

and Flutter Technology groups. Analysis results have shown that the

stiffness properties are satisfactory.

The ATLAS finite element model input geometry is being reviewed in

detail. In the region of the rear spar and closure rib, the model is

being revised to reflect the latest changes in production drawings.

2.3 WEIGHT STATUS

Table 2-1 presents the current weight status of the stabilizer. The

only weight change, from the previous quarterly report, is the inclusion

of omitted doubler material to the outboard section of the upper and

lower skin panels. The upper panel increases by 0.4 kg (0.9 Ib), the

lower panel by 0.9 kg (1.9 ib), and the overall weight reduction decreases

from 27% to 26%.

Weight evaluation of the stub box (Test No. 21) is completed and stabilizer production verification initiated.

VR ¢F..OINQP4GEBNK NOTFILD
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Boeing Commercial

Airplane Company

Contract NASI-15025

SECTION 3.0 _

DEVELOPMENT TEST PLAN AND STATUS _

3.1 ANCILLARY TEST PROGRAM _

During this reporting period, the Test No. i bolted-Joint moistureconditioned specimens were tested. This _ecent wet test data and the

previousl;y published dry data (see Reference 2) are presented in Tables

3-1 and 3-2. These data are graphically displayed in Figures 3-1 and

J

r 3-2. Three typical failed specimens are shown in Figure 3-3. Results

indicate the hot-wet or cold-dry conditions can affect Joint strengths

: approximately _ 12%, compared to room temperature dry conditions.

Tension tests of impact-damaged coupons hzve been conducted. Impact

levels used in the test program were selected based on the following:

• Visually undetectable damage

2.82 N-m (25 in-lb) impact on 16-ply laminate

5.65 N-m (50 in-lb) impact on 24-ply laminate

• Visually barely detectable damage

5.65 N-m (50 in-lb) impact on 16-piy laminate

8.36 N-m (74 in-lb) impact on 24-ply laminate

The specimen descriptions and test results are presented in Tables 3-3

and 3-4, and results are plotted in Figures 3-4 through 3-7. For comparison purposes, the undamaged room-t_perature dry lamlnate ultlmate _

tenelon stress is 413.7 MPa (60 ksl). A typical specimen is shown in

Figure 3-8, and a typical teat setup is shown in Figure 3-9. These test _

results indlcaced Chat:

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0.23_:m (O.09-in) rider specimenreaches1.1% moisture content.

Figure3.2. Effect of Environment on 50% Load TransferJoint

3-7

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t- 3.05 mm (0.12 in)

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Figure3.4. Effect of 2.82 N-m Impacton Laminate[(0/90)(*46)] (I6 PliaJ

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(O.09-in) rider specimen reaches1.1% moisture content. ,p:,-

Figure3-6. Effect of 5.65 N-m Impact on Laminate [(0/90)(+45)] (24 Plies)

3-13

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Figure 3-8. Typical Tension Impact Specimen

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3-15

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Contract NASI-15025

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on Spar Chord CtYpplingSpecimens

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3-21

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3-23

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Loeing Commercial

Airplane _.......

Contract NASI-15025 !,

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SECTION 4.0 _

OPERATIONS DEVELOP}_NT

This section discusses results of the manufacturing producibitity studies,

ancillary test component fabrication and assembly auality assurance

development, and manufacturing verification hardware,

4.1 PRODUCIBILITY STUDIES

Two produ:ibility studies were conducted during this reporting period.

One addressed minimizing porosity in the spar radii, the other addressed

minimizing warpage in the "l"-st£ffened configurated design.

Spar Radius Study-Both the front and rear spar details for the stub box

had porosity in the tool side radii (Figure 4-1). In order to minimize

and possibly eliminate the porosity, a study was conducted to determine

the effect of reducing the corner radius of the layup tool. A test spar/

lug aluminum tool was modified with three different radii: 0.48 cm (0.19 in),

0.25 cm (0. I0 in), and 0.08 cm (0.03 in). Two parts from each radius were

/ fabricated. The preliminary results indicate that the 0.25-cm (0.10-in)

radius gave the best results; however, the improvement was not sufficient

i

to warrant the cost and schedule impact for rework of the spar tools.

"l"-Stiffened Panel Warpage Study-The completed "l"-stiffened stub box skin

panels had up to 1.59-cm (0.627-in) warpage. This warpage did not affect

the assembly of the stub box. However, a Boelng-funded program was conducted

in an effort to minimize the warpage. Under this program, an "l"-stiffened _

conflgurated design, using (he Identical skin layup as the stub box upper

surface panel, was fabricated by replacing the unidirectional (0°) tape on

the top of the stringer-free flange with graphlte/epoxy fabric. The _"

overall warpage of this panel was less than half the warpage of the stub box

panels. The warpage was reduced to 0.672 cm (0.302 in).

4-1

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Boeing Commercial

Airplane Company 4

Contract NASI-15025

Engineering has reviewed the results and is proceeding with this configuration for the production stabilizer skin panels, i

4.2 ANCILLARY TEST COMPONENT FABRICATION

The ancillary test plan includes allowables and environmental, and concept

verification. The f311owing describes the fabrication status of each effort

as of September 28, 1978. i

q

Allowables and Environmental--This part of the ancillary test program

includes material allowables (Test No. I), mechanical joints (Test

No. 5), and environmental specimens (Test No. 4). All ancillary test

specimens have been fabricated and assembled.

Concept Verification--Th_ part of the ancillary test program includes

spar chord crippling (Test No. 7), skin-to-rib Joints (Test No. 9), skin

panel (Test No. I0), spar shear web (Test No. ii), spar/lug (Test No.

12), sonic test box (Test No. 20), stub box (Test No. 21), discontinuous

laminate critical strain (Test No. 22), skin panel-to-rib Joint (Test

No. 24), production verification specimens (Test No. 25), and manufacturing feasibility spar tes_ coupons (Test No. 26). The following describes

the fabrication and assembly status:

• Spar chord crippling (Test No. 7)--Detail fabrication and assembly

complete

• Skin-to-rib Joints (Test No. 9)--Detail fabrication and assembly

complete

• Skin panel (Test No. lO)--Detail fabrication 40% complete

(Figure 4-2)

• Spar shear web (Test No. ll)--Detail fabrication and assembly complete

• Spar/lug (Test No. 12)--Detail fabrication and assembly complete

(Figures 4-3 and 4-4)

4-3
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Boeing Commercial

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Contract NASI-15025

• As reported, tile two major items derived from the fabrication of the

_z

• stub box were the corner build-up on ribs, and the warpage of the

i "l"-stiffened skin panel. The production ribs have been redesigned to °i

1

eliminate the corner build-ups. During the assembly of the "l"-stiffened

skin panels, the warpage could be removed with hand pressure. However,

on the production skin panels, the graphite/epoxy tapes used in the caps

of the stiffeners will be replaced by graphite/epoxy fabric of equivalent

stiffness in order to reduce the warpage.

Figures 4-5 through 4-16 show the assembly and completed stub box.

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: Boeing Commercial

_- Airplane Company

Contract NASI-15025

.'T'-'"

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' Figure4-11. TestNo. 21, Stub Box--ShowingTrailing-EdgeBeam,RearSpar,and

Grephi_e/Epoxy Ribs in Pla_.

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Figure4-12. Te_tN_ 21, Stub 8ox-Showin_ Front and Rut Sp_r, LowerSkin Pane/ eL
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Boeing Commercial OF POORQUALITY Airplane Company

Contract NASI-15025 -_

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Figure 4-15. Test No. 21, Stub Box--Showing Front View of Completed Assembly

• m'___ "= " p/. - , " .

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Figure4.16. TestNo. 21, Stub Box-Showing Side Viewof CompletedAs_rnbly

4-13

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SECTION 5.0 'i

REFERENCES _

i i. "Advanced Composite Stabilizer for Boeing 737 Aircraft," Fourth

_ Quarterly __e_hn_ca_ ^ _ _ Progress Report, _o_ ..... Contract NASi-15025,

i July 1978

I 2. Quarterly "Advanced Composite Technical Stabilizer Progress Report, for Boeing NASA Contract 737 Aicraft, NASI-15025, ''Third

i April 1978

i " Second

3. "Advanced Composite Stabilizer for Boeing 737 Aircraft,

Quarterly Technical Progress Report, NASA Contract NASI-15025,

January 1978

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