Volume 28, Issue 5 (September 2000)
Fatigue and Stress Analysis of a Novel Test Coupon Geometry Developed for Hydraulic Pressure Impulse Testing
Pressure impulse fatigue testing of a novel test coupon geometry was conducted to simulate hydraulic flight con trol manifolds under multiaxial stress conditions. The configuration of the coupon was particularly useful for evaluating complex multiaxial stress states and for comparing the impulse fatigue performance of different types of alloys under conditions of high stress concentration. In this article, three-dimensional linear elastic finite element analyses are presented to quantify the von Mises equivalent and maximum principal stress distributions at the stress-critical regions. Fatigue life results using the present coupon geometry are provided for two high-strength aluminum alloy variants, including Types 7075 and 6013. Post-test macroscopic and scanning electron microscopy examinations are presented to characterize the fatigue fractures and to show that fatigue crack initiation takes place at the maximum stress locations as predicted by finite element analysis.