A numerical model is developed for prediction of the process-induced thermal residual stresses in thermoplastic composite laminates. The model addresses the development of the three-dimensional residual stress state in fracture-critical free-edge regions as well as through-thickness stress variations. The current approach and analysis provide a unique capability for the investigation of the influence of thermal processing and structural parameters on the resulting buildup of residual stresses during manufacturing. Therefore, it can assist in the design and analysis of thermoplastic composites in terms of tailoring of mechanical and strength characteristics.
The applied surface cooling rate from the melt has a strong effect on the free-edge stress levels obtained at room temperature, and in particular the interlaminar stresses. Results are shown for the case of typical cross-ply and quasi-isotropic APC-2 (graphite/polyether-ether-ketone) laminates.
1. Pipes, R. B. and N. J. Pagano. 1970. "Interlaminar Stresses in Composite Laminates Under Uniform Axial Extension,"J. of Composite Materials, 4:538-548.
2.
2. Wang, A. S. D. and F. W. Crossman. 1977. "Edge Effects on Thermally Induced Stresses in Composite Laminates,"J. of Composite Materials, 11:300-312.
3.
3. Rybicki, E. F. and D. W. Schmueser. 1978. "Effect of Stacking Sequence and Lay-Up Angle on Free Edge Stresses Around a Hole in a Laminated Plate Under Tension,"J. of Composite Materials, 12:300-313.
4.
4. Muzzy, J. D. and A. O. Kays. 1984. "Thermoplastic vs. Thermosetting Structural Composites,"Polymer Composites, 5(3):169-172.
5.
5. Jeronimidis, G. and A. T. Parkyn. 1988. "Residual Stresses in Carbon Fibre-Thermoplastic Matrix Laminates,"J. of Composite Materials, 12(5):401-4415.
6.
6. Nairn, J. A. and P. Zoller. 1987. "The Development of Residual Thermal Stresses in Amorphous and Semicrystalline Thermoplastic Matrix Composites,"Toughened Composites, ASTM STP 937, Philadelphia, PA, pp. 328-341.
7.
7. Kim, K. S., H. T. Hahn and R. B. Croman. 1989. "The Effect of Cooling Rate on Residual Stress in a Thermoplastic Composite,"J. of Composite Technology and Research, 11 (2):47-52.
8.
8. Unger, W. J. and J. S. Hansen. 1993. "The Effect of Cooling Rate and Annealing on Residual Stress Development in Graphite Fibre Reinforced PEEK Laminates,"J. of Composite Materials, 27(2):108-137.
9.
9. Schulte, K. J. and H. T. Hahn. 1989. "Prediction and Control of Processing-Induced Residual Stresses in Composites. Part II: AS4/PEEK Composites," Final Report, Air Force Office of Scientific Research, AFOSR Grant-87-0242, pp. 1-76.
10.
10. Chapman, T. J., J. W. Gillespie Jr., R. B. Pipes, J.-A. E. Manson and J. C. Seferis. 1990. "Prediction of Process-Induced Residual Stresses in Thermoplastic Composites,"J. of Composite Materials, 24(6):616-643.
11.
11. Lawrence, W. E., J.-A. E. Manson, J. C. Seferis, J. W. Gillespie Jr. and R. B. Pipes. 1990. "Prediction of Residual Stress in Continuous Fiber Semicrystalline Thermoplastic Composites: A Kinetic-Viscoelastic Approach,"5th ASC Technical Conf, East Lansing, MI, pp. 401-414.
12.
12. Domb, M. M. and J. S. Hansen. 1994. "Development of Free-Edge Effect During Processing of Semicrystalline Thermoplastic Composites,"AIAA Journal, 32(5):1029-1033.
13.
13. Domb, M. M. and J. S. Hansen. 1993. "Free-Edge Effect Development in the Processing and Annealing of Fibre-Reinforced Semicrystalline Thermoplastic Composites."9th Int. Conf. on Composite Materials, Madrid. Spain, 2:219-226.
14.
14. Blundell, D. J., J. M. Chalmers, M. W. Mackenzie and W. F. Gaskin. 1985. "Crystalline Morphology of the Matrix of PEEK-Carbon Fiber Aromatic Polymer Composites. 1—Assessment of Crystallinity,"SAMPE Quarterly, 16(4):22-30.
15.
15. Blundell, D. J. and B. N. Osborn. 1983. "The Morphology of Poly-(aryl-ether-ether-ketone),"Polymer, 24:953-958.
16.
16. Blundell, D. J. and B. N. Osborn. 1985. "Crystalline Morphology of the Matrix of PEEK-Carbon Fiber Aromatic Polymer Composites. 2-Crystallization Behavior."SAMPE Quarterly, 17(l):1-6.
17.
17. Velisaris, C. N. and J. C. Seferis. 1986. "Crystallization Kinetics of Polyether-ether-ketone (PEEK) Matrices,"Polymer Engineering and Science, 26(22):1574-1581.
18.
18. Downs, R. J. and L. A. Berglund. 1987. "Apparatus for Preparing Thermoplastic Composites,"]J. of Reinforced Plastics and Composites, 6:89-99.
19.
19. Curtis, P. T., P. Davies, I. K. Partridge and J. P. Sainty. 1987. "Cooling Rate Effects in PEEK and Carbon Fibre-PEEK Composites,"Proc. of 6th ICCM and 2nd ECCM, 4:4.401-4.412.
20.
20. Grossman, S. P. and M. F. Amateau. 1988. "The Effect of Processing on a Graphite Fiber/Polyetheretherketone Thermoplastic Composite,"33rd Int. SAMPE Symp., Anaheim, CA, pp. 681-692.
21.
21. Davies, P., W. Cantwell, H. Richard, C. Mowlin and H. H. Kansch. 1989. "Interlaminar Testing of Carbon Fiber/PEEK Composites,"Proc. of the 3rd European Conference on Composite Materials, Bordeaux, France.
22.
22. Velisaris, C. N. and J. C. Seferis. 1988. "Heat Transfer Effects on the Processing-Structure Relationships of Polyetheretherketone (PEEK) Based Composites."Polymer Engineering and Science, 28(9):583-591.
23.
23. Domb, M. M. 1995. "Analysis of Thermal Residual Stresses During Processing of Fibre-Reinforced Thermoplastic Composites," Ph.D. Thesis, Department of Aerospace Science and Engineering, University of Toronto.
24.
24. Huebner, K. H. and E. A. Thornton. 1982. The Finite Element Method for Engineers, 2nd Edition, Wiley Interscience Publications, John Wiley and Sons, New York.
25.
25. McCullough, R. L.1977. "Anisotropic Elastic Behavior of Crystalline Polymers,"Properties of Solid Polymeric Materials, 10B, (ed., J. M. Schultz), AP, NY, pp. 453-540.
26.
26. McCullough, R. L., G. J. Jarzebski and S. H. McGee. 1983. "Constitutive Relationships for Sheet Molding Materials,"Proc. USA-Italy Joint Symp. on Composite Materials, Plenum Publ., NY, pp. 261-287.
27.
27. Unger, W. J. and J. S. Hansen. 1993. "The Effect of Thermal Processing on Residual Strain Development in Unidirectional Graphite Fibre Reinforced PEEK,"Journal of Composite Materials, 27(1):59-82.
28.
28. Nowinski, J. L.1978. Theory of Thermoelasticity with Applications, Sijthoff& Noordhoff International Publishers, The Netherlands.
29.
29. Lekhnitskii, S. G.1963. Theory of Elasticity of an Anisotropic Elastic Body, Holden-Day Inc., San Francisco.
