Sage Journals: Discover world-class research

Abstract

A Trans-Laminar-Reinforced (TLR) composite is defined as composite laminate with up to five percent volume of fibrous reinforcement oriented in a trans-laminar fashion in the through-thickness direction. The objective of this work was to examine the effect of important parameters on elastic response. Detailed finite element models of unit cells were used to study the effects of adding TLR on the elastic constants. Parameters investigated included TLR material, TLR volume fraction, TLR diameter, TLR through-thickness angle, ply stacking sequence, and the microstructural features of pure resin regions and curved in-plane fibers. The work was limited to materials with at least one ply interface. Adding a few percent TLR had a small negative effect on the in-plane extensional and shear moduli, E_x, E_y and G_xy but a large positive effect (up to 60 percent) on the thickness direction extensional modulus, E,. The volume fraction and the axial modulus of the TLR were the controlling parameters affecting E,. The out-of-plane shear moduli, G, and Gy, were significantly affected only with the use of a TLR with a shear modulus an order of magnitude greater than that of the composite lamina. A simple stiffness averaging method for calculating the elastic constants was found to compare closely with the finite element results, with the greatest difference being found in the inter-laminar shear moduli, G., and Gy.

Get full access to this article

View all access options for this article.

References

1. Farley, G. L.

"A Mechanism Responsible for Reducing Compression Strength of Through-the-Thickness Reinforced Composite Material,"

Journal of Composite Materials, 1991, Vol. 26, No. 12.

2. Farley, G. L. and Dickinson, L. C. "Mechanical Response of Composite Materials with Through-the-Thickness Reinforcement," in Fiber-Tex 1991, 1992, NASA CP 3179.

3. Farley, G. L. and Dickinson, L. C.

"Removal of Surface Loop from Stitched Composites Can Improve Compression and Compression after Impact Strengths,"

Journal of Reinforced Plastics and Composites, 1992, Vol. 11, No. 6 (June).

4. Jain, L. K. and Mai, Y. W.

"On the Effect of Stitching on Mode I Delamination Toughness of Laminated Composites,"

Composites Science and Technology, 1994, 51.

5. Huang, S. L. , Richey, R. J. and Deska, E. W. "Cross Reinforcement in a GR/ER Laminate," in ASME Winter Annual Meeting, 1978.

6. Krasnov, V. I., Kusnetsov, V. A. and Maksakov, A. Y. "Automated Method of Transverse Reinforcement of Composites by Short Fibers," Translated from Mekhanika Kompozitnykh Materialov, 1987, No. 3 (May-June).

7. Evans, D. A. and Boyce, J. S. "Transverse Reinforcement Methods for Improved Delamination Resistance," in 34th International SAMPE Symposium, 1989.

8. Freitas, G. , Magee, C. , Boyce, J. and Bott, R. "Serive Tough Composite Structures Using the Z-Direction Reinforcement Process," in Ninth DoD/NASA/FAA Conference on Fibrous Composites in Structural Design, 1991.

9. Freitas, G. "Z-Fiber™ Insertion Process for Improved Damage Tolerance in Aircraft Laminates," in 25th International SAMPE Technical Conference, 1993.

10.

10. Freitas, G. , Magee, C. , Dardzinski, P. and Fusco, T.

"Fiber Insertion Process for Improved Damage Tolerance in Aircraft Laminates,"

Journal of Advanced Materials, 1994, Vol. 25, No. 24 (July).

11.

11. Freitas, G. , Fusco, T. , Campbell, T. , Harris, J. and Rosenberg, S. "Z-Fiber™ Technology and Products for Enhancing Composite Design," in AGARD, 1996.

12.

12. Sharma, S. K. and Sankar, B. V. "Effects of Through-the-Thickness Stitching on Impact and Interlaminar Fracture Properties of Textile Graphite/Epoxy Laminates," NASA CR 195402, 1995.

13.

See also: Dickinson, L. C. , Farley, G. L. and Hinders, M. K. "Trans-Laminar Reinforced (TLR) Composites: A Review," submitted for publication in Composites Science and Technology, 1997.

14.

14. Tomashevskii, V. T. , Sitnikov, S. Y. , Shalygin, V. N. and Yakovlev, V. S. "A Method of Calculating Technological Regimes of Transversal Reinforcement of Composites with Short-Fiber Microparticles," Translated from Mekhanika Kompozitnykh Materialov, 1989, No. 3 (May-June).

15.

15. Tomashevskii, V. T. , Shalygin, V. N. , Romanov, D. A. and Sitnikov, S. Y. "Transversal Reinforcement of Composite Materials Using Ultrasonic Vibrations," Translated from Mekhanika Kompozitnykh Materialov, 1987, No. 6 (Nov.-Dec.).

16.

16. Marrey, R. V. and Sankar, B. V. "Micromechanical Models for Textile Structural Composites, NASA CR 198229, 1995.

17.

17. Cox, B. N. and Flanagan, G. Handbook of Analytical Methods for Textile Composites, Version 1.0, 1996.

18.

18. Bennett, G. R. "A Parametric Study of the Global Stiffness and Stress Concentrations of Through-The-Thickness Reinforced Composite Laminae Using A Representative Volume Element Approach," M.S., Virginia Polytechnic Institute and State University, 1997.

19.

19. Walker, J. , Roundy, L. and Goering, J. "Effects of Thermal and Moisture Cycling on the Internal Structure of Stitched RTM Laminates," in Third NASA Advanced Composites Technology Conference, 1992, NASA CP 3178, Vol. 1, Part 1, 1992.

20.

20. Hipp, R. C. , Renze, S. P. , Saff, C. R. and Walker, J. V. "Effects of Environment on Textile Composites," in Fourth NASA/DoD Advanced Composite Technology Conference, 1993, NASA CP 3229, Vol. 1, Part 1, 1993.

21.

21. Naik, R. A. "Micromechanical Combined Stress Analysis-Micstran, A User Manual," NASA CR 189694, 1992.

22.

22. Naik, R. A. and Crews, J. H. J. "Closed-Form Analysis of Fiber-Matrix Interface Stresses under Thermo-Mechanical Loadings," NASA TM 107575, 1992.

23.

23. Naik, R. A. "TEXCAD Textile Composite Analysis for Design, Version 1.0 User's Manual," NASA CR 4639, 1994.

24.

24. Naik, R. A. "Analysis of Woven and Braided Fabric Reinforced Composites," NASA CR 194930, 1994.

25.

25. Naik, R. A. "Failure Analysis of Woven and Braided Fabric Reinforced Composites," NASA CR 194981, 1994.

26.

26. Portanova, M. A. , Poe, C. C. J. and Whitcomb, J. D.

"Open Hole and Post Impact Compression Fatigue of Stitched and Unstitched Carbon/Epoxy Composites,"

Composite Materials; Testing and Design, ASTM STP 1120, 1990.

27.

27. Dickinson, L. C. "Effects of Stitching Parameters on Mechanical Properties and Damage Tolerance of Stitched/RTM Composites," in The Fourth NASA Advanced Composites Technology Conference, 1993, NASA CP 3229, Vol. 1, Part 1, 1993.

Prediction of Effective Three-Dimensional Elastic Constants of Translaminar Reinforced Composites

Abstract

Get full access to this article

References