Abstract

Constant-stress-amplitude axial-load fatigue tests were conducted to generate mean stress data for notched and unnotched specimens of a thermoplastic composite material with 40% (by weight) randomly oriented continuous-strand glass in a polypropylene matrix. Maximum likelihood point and interval estimates for the median fatigue strengths at 107 cycles were computed for four stress ratios R (−1.0, −0.2, +0.2, and +0.6) based on tests conducted following a modified small sample up-and-down methodology appropriate when extensive preliminary data are available to aid in test planning.

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