A strength-based wearout model is presented for predicting the residual strength and life of composite structures subjected to constant amplitude or two-stress level fatigue loadings. It is assumed that the structure undergoes proportional loading, that its residual strength is a monotonically decreasing function of the number of loading cycles, and that both the life distribution due to continuous constant amplitude cycling and the residual strength distribution after an arbitrary load history may be represented by two parameter Weibull functions. The model also incorporates a "cycle mix factor" to account for the degradation of strength and life that may be associated with frequent changes in the stress amplitude of the loading. Experimental results from two-stress level, uniaxially loaded laminates are used to evaluate the model's predictive capability for sequencing effects, as in a low-high or high-low test, and for cycle mix effects, as in a low-high-low-high repeating test. Good correlation between theory and experiment is obtained for all loadings and laminates studied.
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References
1.
1. McLaughlin, P., S. V. Kulkarni, S. N. Huang and R. B. Walter. 1975. "Fatigue of Notched Fibre Composite Laminates—Part I: Analytical Model," NASA-CR-132747.
2.
2. Kulkarni, S. V., P. McLaughlin, R. B. Pipes and B. W. Rosen. 1977. "Fatigue of Notched Fiber Composite Laminates: Analytical and Experimental Evaluation,"Composite Materials: Testing and Design (Fourth Conference), ASTM STP 617, Philadelphia: American Society for Testing Materials, pp. 70-92.
3.
3. Talreja, R. 1985. "Fatigue of Composite Materials" Technical University of Denmark, Ph.D. Thesis.
4.
4. Timmer, J. S. and H. T. Hahn. 1993. "The Effect of Preloading on Fatigue Damage in Composites,"18th Annual Mechanics of Composites Review, pp. 144-153.
5.
5. Schaff, J. R. and B. D. Davidson. 1997. "Life Prediction Methodology for Composite Structures. Part H1: Spectrum Fatigue,"Journal of Composite Materials, 31:158-181.
6.
6. Hwang, W. and K. S. Han. 1986. "Fatigue of Composites-Fatigue Modulus Concept and Life Prediction,"Journal of Composite Materials, 20:154-165.
7.
7. Sendeckyj, G. P.1990. "Life Prediction for Resin-Matrix Composite Materials,"Composite Materials Series: Fatigue of Composites, K. L. Reifsnider, ed., New York: Elsevier Science Publishers, 4:431-483.
8.
8. Hahn, H. T. and R. Y. Kim. 1976. "Fatigue Behavior of Composite Laminates,"Journal of Composite Materials, 10:156-180.
9.
9. O'Brien, T. K. and K. L. Reifsnider. 1981. "Fatigue Damage Evaluation through Stiffness Measurements in Boron-Epoxy Laminates,"Journal of Composite Materials, 15:55-70.
10.
10. Whitworth, H. A.1987. "Modeling Stiffness Reduction of Graphite/Epoxy Composite Laminates,"Journal of Composite Materials, 21:362-372.
11.
11. Whitworth, H. A.1990. "Cumulative Damage in Composites,"Journal of Engineering Materials and Technology, 112:358-361.
12.
12. Farrow, I. R. 1989. "Damage Accumulation and Degradation of Composite Laminates Under Aircraft Service Loading: Assessment and Prediction, Volumes I and 1," Cranfield Institute of Technology, Ph.D. Thesis.
13.
13. Hwang, W. and K. S. Han. 1986. "Cumulative Damage Models and Multi-Stress Fatigue Life Prediction,"Journal of Composite Materials, 20:125-153.
14.
14. Hwang, W. B. and K. S. Han. 1989. "Fatigue of Composite Materials-Damage Model and Life Prediction,"Composite Materials: Fatigue and Fracture, 2nd Vol., ASTM STP 1012, P. A. Lagace, ed., Philadelphia: American Society for Testing and Materials, pp. 87-102.
15.
15. Poursartip, A., M. F. Ashby and P. W. R. Beaumont. 1986. "The Fatigue Damage Mechanics of a Carbon Fibre Composite Laminate: I—Development of the Model,"Composites Science and Technology, 25:193-218.
16.
16. Poursartip, A. and P. W. R. Beaumont. 1985. "The Fatigue Damage Mechanics of a Carbon Fibre Composite Laminate: 11-Life Prediction,"Composites Science and Technology, 25:283-299.
17.
17. Yang, J. N., S. H. Yang and D. L. Jones. 1989. "A Stiffness-Based Statistical Model for Predicting the Fatigue Life of Composite Laminates,"Journal of Composite Technology and Research, 11(4):129-134.
18.
18. Lee, L. J., J. N. Yang and D. Y. Sheu. 1993. "Prediction of Fatigue Life for Matrix-Dominated Composite Laminates,"Composite Science and Technology, 46:21-28.
19.
19. Hahn, H. T. and R. Y. Kim. 1975. "Proof Testing of Composite Materials,"Journal of Composite Materials, 9:297-311.
20.
20. Halpin, J. C., T. A. Johnson and M. E. Waddoups. 1972. "Kinetic Fracture Models and Structural Reliability,"International Journal of Fracture Mechanics, 8:465-468.
21.
21. Weibull, W. and G. W. Weibull. 1977. "New Aspects and Methods of Statistical Analysis of Test Data with Special Reference to the Normal, the Lognormal, and the Weibull Distributions," FOA Report D 20045-DB, Stockholm: Defense Research Institute.
22.
22. Yang, J. N. and M. D. Liu. 1977. "Residual Strength Degradation Model and Theory of Periodic Proof Tests for Graphite/Epoxy,"Journal of Composite Materials, 11:176-203.
23.
23. Yang, J. N.1978. "Fatigue and Residual Strength Degradation for Graphite/Epoxy Composites Under Tension-Compression Cyclic Loadings,"Journal of Composite Materials, 12:19-41.
24.
24. Yang, J. N. and D. L. Jones. 1980. "Effect of Load Sequence on the Statistical Fatigue of Composites,"AIAA Journal, 12:1525-1531.
25.
25. Yang, J. N. and D. L. Jones. 1981. "Load Sequence on the Fatigue of Unnotched Composites Materials,"Fatigue of Fibrous Composite Materials, ASTM STP 723, Philadelphia: American Society for Testing and Materials, pp. 213-232.
26.
26. Yang, J. N. and D. L. Jones. 1983. "Load Sequence Effects on Graphite/Epoxy [±35],. Laminates,"Long-Term Behavior of Composites, ASTM STP 813, T. K. O'Brien, ed., Philadelphia: American Society for Testing and Materials, 246-262.
27.
27. Yang, J. N. and S. Du. 1983. "An Exploratory Study Into the Fatigue of Composites Under Spectrum Loading,"Journal of Composite Materials, 17:511-526.
28.
28. Chou, P. C. and R. Croman. 1978. "Residual Strength in Fatigue Based on the Strength-Life Equal Rank Assumption,"Journal of Composite Materials, 12:177-195.
29.
29. Chou, P. C. and R. Croman. 1979. "Degradation and Sudden-Death Models of Fatigue of Graphite/Epoxy Composites,"Composite Materials, Testing and Design (Fifth Conference), S. W. Tsai, ed., ASTM STP 674, Philadelphia: American Society for Testing and Materials, pp. 431-454.
30.
30. Talreja, R.1981. "Estimation of Weibull Parameters for Composite Materials Strength and Fatigue Life Data,"Fatigue of Fibrous Composite Materials, ASTM STP 723, Philadelphia: American Society for Testing Materials, pp. 291-311.
31.
31. Broutman, L. J. and S. Sahu. 1972. "A New Theory to Predict Cumulative Fatigue Damage in Fiberglass Reinforced Plastics,"Composite Materials: Testing and Design (Second Conference), ASTM STP 497, Philadelphia: American Society for Testing and Materials, pp. 170-188.
32.
32. Schaff, J. R. and B. D. Davidson. 1994. "Life Prediction for Composite Laminates Subjected to Spectrum Fatigue Loading,"Durability of Composite Materials, MD-Vol. 51, R. C. Wetherhold, ed., New York: The American Society of Mechanical Engineers, pp. 89-109.
33.
33. Miner, M. A.1945. "Cumulative Damage in Fatigue,"Journal of Applied Mechanics, 12:159-164.
34.
34. Palmgren, A.1924. "Die Lebensdauer von Kugellagern,"Zeitschrift des Vereins Deutscher Ingenieure, 68:339-341.
35.
35. Schaff, J. R. and B. D. Davidson. 1994. "Life Prediction Methodology for Composite Laminates—Part I: Constant Amplitude and Two-Stress Level Fatigue," WL-TR-4046-94, Dayton: Wright Laboratory.
