Tp. Savas et Jc. Earthman, Fatigue and stress analysis of a novel test coupon geometry developed for hydraulic pressure impulse testing, J TEST EVAL, 28(5), 2000, pp. 359-366
Pressure impulse fatigue testing of a novel test coupon geometry was conduc
ted to simulate hydraulic flight control manifolds under multiaxial stress
conditions. The configuration of the coupon was particularly useful for eva
luating complex multiaxial stress states and for comparing the impulse fati
gue performance of different types of alloys under conditions of high stres
s concentration. In this article, three-dimensional linear elastic finite e
lement analyses are presented to quantify the von Mises equivalent and maxi
mum principal stress distributions at the stress-critical regions. Fatigue
life results using the present coupon geometry are provided for two high-st
rength aluminum alloy variants, including Types 7075 and 6013. Post-test ma
croscopic and scanning electron microscopy examinations are presented to ch
aracterize the fatigue fractures and to show that fatigue crack initiation
takes place at the maximum stress locations as predicted by finite element
analysis.