Design of step-stress accelerated life tests for estimating the fatigue
reliability of structural components based on a finite-element approach
Abstract
This article describes how a step-stress accelerated life test (SSALT)
can be designed for testing the fatigue life and reliability of
structural components with a single failure mode. With simple numerical
simulations of the crack’s propagation in the notched area of the
structural part for different loading levels, the slope of the S-N curve
for a structural component is initially estimated. Then, a very few
fatigue-life experiments are carried out in the high-cycle domain to
determine the intercept of the structure’s S-N curve. By considering the
scatter from the material’s P-S-N curve, different SSALT designs for the
structural component can be composed and checked for their expected
acceleration factor. The procedure is experimentally validated for the
case of a notched specimen and two different SSALT designs. From the
results it can be concluded that the predicted durations of the SSALT
experiments correlate well with the real experiments.