Effects of residual stresses on probabilistic lifing of engine disk materials

Residual stresses are known to be beneficial with respect to fatigue life of metal components. Shot peening or other techniques are frequently used to improve fatigue performance. This study uses a probabilistic methodology to examine the significance of the residual stress, obtained from shot peening, on the crack growth fatigue life. Specifically, the residual stress at a bolthole in a compressor disk composed of a superalloy is modeled as a random variable in addition to the initial crack size, crack propagation scatter and stress scatter random variables. The probabilistic sensitivities of the predicted probability-of-fracture with respect to the parameters of the random variables are computed and comprise a metric for assessing the significance of the residual stress on reducing the probabilityof-fracture.