Influence of Ply Waviness on Stiffness and Strength ... Influence of Ply Waviness on Stiffness and Strength

  • View
    0

  • Download
    0

Embed Size (px)

Text of Influence of Ply Waviness on Stiffness and Strength ... Influence of Ply Waviness on Stiffness and...

  • AD-A263 224

    ARMY RESEARCH WAORATORY •

    Influence of Ply Waviness on Stiffness and Strength Reduction of

    Composite Laminates

    Travis A. Bogetti DTI U.S. ARMY RESEARCH LABORATORY

    Jack W. Gilespie, Jr. 2 19UNIVERSITY OF DELAWARE

    Mark A. Lamontia E. 1. DUPONT DE NEMOURS AND COMPANY- INC.

    ARL-TR-110 April 1993

    93-08684

    3 4• :I" 012 "AMovE MR PMUC WRE. mDITmDIoN ts utm-Wo.

  • NOTICES

    Destroy this report when it is no longer needed. DO NOT return it to the originator.

    Additional copies of this report may be obtained from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161.

    The findings of this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.

    The use of trade names or manufacturers' names in this report does not constitute indorsement of any commercial product.

  • b/

    REPORT DOCUMENTATION PAGE Fo .Approwd _____OM8 No. 0704-0188

    A Pubic rp~~fl•' n; j urdf i I 01-"-- tfth C Uat-&n o i Unflmartto 9 Ii e rtimat to vf g I O uNLln Oe re~mteonn , Incld €ong tIWal t~m o e tawn lstructl n. esearte og aittn O d at, O thurel ai~lgr y. te 1204. Arinton.VA 2-4302. and to the Office of Mnagmenmt nd udget. Paperwok Redcto P"ot m r(anyo=)W *angon. OC 20"03.

    1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE I3. REPORT TYPE AND DATES COVERED Apri~ 1993 IF'nal, June 1991-August 1992

    4. TITLE AND SUBTITLE S. FUNDING NUMBERS

    Influece of Ply Waviness on Stiffness and Strength Reduction of Composihe Lamws

    6. AUTHOR(S) PR: IL162618AH80

    Travis A. Boge••i, Jack W. Gillespie, Jr1 ., and Mark A. Lamontia2

    7. PERFORMING ORGANIZATION- NAME(S) AND AOORESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER

    9. SPONSORING/ MONITORING AGENCY NAME(S) AND ADORESSRES) 10. SPONSORING /MONITORING AGENCY REPORT NUMBER

    US. Army Research Laboratory AnW: AMSRL-OP-CI-B (Tech U1b) ARL-TR-11O Aberdeen Proving Ground, MD 21005.5066

    11. SUPPLEMENTARY NOTES ICenW for Cosite M Uiv.of Delawar, Newark, DE. 2E. I. DuPont De Nemours and Co., Ja., Engineming Technology Laboratory. Wilmington, D& This work was sponsored by the Defense Advanced Research Projects Agency (DARPA), Naval Technology Program, under contract No. MDA972-89-C-0043. The work was performed at the University of Delaware's Center for Composite Materials located in Newark, DE

    12a. DISTRIBUTION/AVAILABIUTY STATEMENT 12b. DISTRIBUTION CODE

    Approved for public release; nistribust is unlmied.

    13. ABSTRACT (Maximum200words)

    An analytic model is developed to investigat the influence of ply waviness on the stiffness and strength of composite laminates. The model predicts

    ielasp•r and ewhrmal expansion coerrociet of sublamimaies containing wavy layers ply sres for preibed mechanical and thermal load cases q sength reduction associated with ply waviness

    Parametric studies am conducted for sublaminbies of AS4 GraphiteREKK and S2 Glass/PEKK which exhibit layer waviness. Results show that stiffness and smrngth reduction are significant in the direction of ply undulation only. Mechanisnsof stiffne reduction are attributed to out-of-piane rotation of wavy layers. This waviness may also create signi frica lntrauinr sbea s. e that reduces strngth. The magnitude of the property reduction increases as the amplitude of the undulation icaesand the half-waveleagth of the undulation decreases. Ply waviness represents one mochanism tat may patally explain why the Sin and faiu analyses of composite sauctures based on flat. autoclave cured coupon propety dam (minimal waviness), do not correlate with test results.

    14. SUBJECT TERMS 1S. NUMBER OF PAGES

    46Ply waviness; strength (mechanics); thermoelastic preoperies filament winding;- PC themoplastic composites; models; composite mat=euria

    17. SECURITY CLASSIFICATION 18. S!CURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT

    UNCLASSIFIED UNC.ASSIFIED UNCLASSIFIED UL

    NSN 7540-01-280-5500 Standard Form 298 (Rev 2-89) PFecfletd by ANSI tl St•3 9.t1 296-102

  • INTEmnToNALLY LEFr BLANK.

  • TABLE OF CONTENTS

    L OeU

    LIST OF FIGURES .............................................. ix

    LU ST OF TABLES ............................................... ix

    ACKNOWLEDGMENTS .......................................... xi

    1. INTRODUCTION ............................................... . I

    1.1 Manufacturing Issues and Ply Waviness ............................. 1 1.2 Literature Survey ............................................. 3 1.3 Problem Statement ............................................ 5

    2. ANALYSIS .................................................... 5

    2.1 Background: Laminated Plate Theory .............................. 5 2.2 Description of the Geomety ..................................... 7 2.3 Effective Elastic Properties ...................................... 7 2.4 Effective Thermal Expansion Coefficients ............................ 11 2.5 Ply S Esses. ................................................. 11 2.6 Applied Failure Criterion: Maximum Stress .......................... 13

    3. RESULTS ..................................................... 14

    3.1 Geometric Constraint on Ply Waviness .............................. 14 3.2 Parametric Studies ............................................ 16 3.2.1 Effective Elastic Properties ................................... 16 3.2.2 Effective Thermal Expansion Coefficients ......................... 22 3.3 Ply Stresses ................................................. 22 3.4 Strength Reduction Due to Ply Waviness ............................ 26 3.4.1 Uniaxial Loading .......................................... 26 3.4.2 Biaxial Loading ........................................... 31

    4. CONCLUSIONS ................................................ 31

    5. REFERENCES .................................................. 35

    DISTRIBUTION LIST ............................................ 37

    iii

  • INTEmfioNALLY LEFT BLANK.

    iv

  • LIST OF FIGURES

    EMLure F

    I. Ply Waviness in a Filament Wound Composite ........................... I

    2. [9//9 01 Ply Waviness: Unit Cell .................................... 8

    3. Laminate Analogy for [90W]901 Ply Waviness ............................ 8

    4. Lamina Coordinat . System ......................................... 13

    5. Definition of Thickness Ratio: TR .................................... 15

    6. Geometric Constraint on Amplitude ................................... .15

    7. Global and Ply Coordinate Systems Used in Analysis ....................... 17

    8. Influence of Undulation Amplitude on E, in AS4 GraphitePEKK (L/hf = 5) ....... 18

    9. Influence of Undulation Amplitude on E. in AS4 Graphite/PEKK (Uhf = 20) ...... 19

    10. Influence of Undulation Amplitude on E, in S2 Glass/PEKK (Uhf = 5) .......... 20

    11. Influence of Undulation Amplitude on ac in AS4 Graphite/PEKK (Uhf = 20) ...... 23

    12. Influence of Undulation Amplitude on a, in S2 Glass/PEKK (L/hf = 5) .......... 24

    13. Longitudinal Stress Within a Wavy [01 Ply in AS4 Graphite/PEKK: Uniaxial Loading (TR = 2, Lhf = 5, Ný (A = 0) = -901 lb/in at Failure) .............. 25

    14. Interlaminar Normal Stress Within a Wavy [0] Ply in AS4 Graphite/PEKK: Uniaxial Loading (TR = 2, LJhf = 5, N. (A = 0) = -901 lb/in at Failure) .............. 27

    15. Interlaminar Shear Stress Within a Wavy [01 Ply in AS4 Graphite/PEKK: Uniaxial Loading (TR = 2, /h = 5, N, (A = 0) = -901 lb/in at Failure) ............... 28

    16. Strength Reduction in AS4 Graphite/PEKK: Uniaxial Loading (TR = 2, L/hf = 5, N (A = 0) = -901 b/in at Failure) .................................. 29

    17. Strength Reduction in AS4 Graphite/PEKK: Uniaxial Loading (TR = 2, LUhf = 20, Nx (A = 0) = -901 lb/in at Failure) .................................. 30

    18. Nondimensional Biaxial Compression Failure Envelopes in AS4 Graphite/PEKK (TR = 2, Uhf = 20, AT = 0 0 F, Nx (A = 0) = -901 lbWin, NY (A = 0) = -1,612 Wbin) ...... 32

    19. Nondimensional Biaxial Compression Failure Envelopes in AS4 Graphite/PEKK (TR = 2, LUhf= 20, AT = -150* F) N. (A = 0) = -901 lb/in, NY (A = 0) = -1,612 lb/in) ... 33

    v

  • INramToNALLY L.EFr BLANK.

  • LIST OF TABLES

    Table kares

    1. Parameter Study: Geometry ........................................ 21

    2. M aterial Properties ............................................... 21

    3. Strength Allowables ............................................... 22

    DTIC QtJArjM -73F 7-1r4

    H £@@SSIOU 1or 01 ' ZITIS GRA&I • -

    DTIC TAB El Unannox•ioed

    Justtifcation

    By

    Distribution/

    AvailabilitY Co0es "A vail and/or

    vDist SpooItl

  • INTENTIONALLY L.EFT BLANK.

    viii

  • ACKNOWLEDGMENTS

    This work was sponsored by the Defense Advanced Research Projects Agency (DARPA), Naval

    Technology Program, under contract No. MDA972-89-C-0043. The work was performed at the University

    of Delaware's Center for Composite Materials 7-cated in Newark, Delaware.

    ix

  • INTENTIONALLY LEFF BLANK.

  • 1. INTRODUCTION

    1.1 Manufacturing Issues and Ply Waviness. The quality and