Fatigue Damage-Strength Relationships in Composite Laminates. Volume 1
Final rept. 1 Jun 1981-31 May 1983
VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIENCE AND MECHANICS
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This report is Vol. I of a 2-part final report on the activities which were conducted under Contract No. F33615-81-3225. The general objective of this program was to investigate the precise nature of the damage events caused by cyclic fatigue loading of composite laminates that are directly related to fracture of those laminates, to develop a conceptual understanding of how those damage events reduce the residual strength of the laminates, and to determine how the collective damage condition following long-term cyclic loading precipitates the final fracture event. The program was conducted in four phases 1 the development of fatigue damage during long-term cyclic loading was investigated in such a way that the damage events which occur quite late in the fatigue life of the material, just prior to fracture, were identified and characterized 2 the special contribution and nature of fiber fracture was investigated 3 the nature of the collective damage condition which precipitates the fracture event under long-term fatigue loading was investigated 4 a philosophy of fracture in composite laminates following severe damage development due to cyclic loading was developed. A wide variety of destructive and nondestructive experimental evaluation schemes were used in the program, and several analytical efforts were conducted to support the experimental activities.
- Laminates and Composite Materials