Fatigue Behavior of Composite Laminates
Final technical rept. 1 Sep 1979-Aug 1980
WASHINGTON UNIV ST LOUIS MO MATERIALS RESEARCH LAB
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The main objective of this program during the final reporting period was to investigate the fatigue behavior of a 0290 or - 45s AS3501-5A Gr Ep laminate through proof testing. The primary emphasis was on the delineation of the effect of proof test on the residual strength and life, the establishment of strength-life relations, and the identification of sources of scatter in strength and life. The test program consisted of static tests, tension-tension fatigue tests preceded by proof tests, and examinations of failure characteristics. Major findings can be summarized as follows 1 Proof tests have little effect on the residual strength and life 2 A relation exists between strength and life such that a statically stronger specimen has a longer life 3 A minimum life can be assured by a proof test 4 A higher modulus is an indication of a higher strength and longer life 5 What distinguishes a typical static failure mode from a typical fatigue failure mode is the lack of delamination in the former 6 At a moderate fatigue stress, the failure mode changes from a static failure mode to a typical fatigue failure mode around 20, 000 cycles and 7 A delamination surface consists of shiny and dull areas. The shiny area has bare fibers whereas the dull area only has fiber traces in the epoxy.
- Laminates and Composite Materials
- Test Facilities, Equipment and Methods