Multiaxial fatigue life prediction model with relative stress gradient and size effect

Abstract

To investigate the effects of notched root stress gradient and geometric size parameters on the fatigue performance of engineering components, a new multiaxial fatigue life prediction model is established. First, based on the energy-critical plane method, the location of the dangerous plane is determined with the help of finite element (FE) analysis. Second, the sixth-order multinomial stress function is used to study the stress/strain distribution state on the critical plane, and the relative stress gradient (RSG) function is used to find the stationary point to determine the RSG value and the magnitude of the fatigue damage zone boundary value. Specifically, for specimens with different notch types, the indexes to determine the high-stress influence zone and the size influence factor are proposed. Finally, a multiaxial fatigue life prediction model considering RSG and size effect is established, and the compared resultsshow that the new model has a high fatigue life prediction capability.

Recent developments and future trends in fatigue life assessment of additively manufactured metals with particular emphasis on machine learning modeling

“…It is generally known that there exist different types of criteria and that each considers a different damage parameter that acts on the critical plane. For some stress‐based multiaxial fatigue criteria, the maximum stress amplitude and direction on the critical plane are usually used to estimate the fatigue life and crack initiation angle 179,180 . Cruces et al 181,182 investigated the multiaxial fatigue of AMed 18Ni300 using several methods:…”

“…For some stressbased multiaxial fatigue criteria, the maximum stress amplitude and direction on the critical plane are usually used to estimate the fatigue life and crack initiation angle. 179,180 Cruces et al 181,182 investigated the multiaxial fatigue of AMed 18Ni300 using several methods: Strain energy-based models Liu and Wang 183 defined the maximum normal strain energy and maximum shear strain energy at the critical plane to describe the fatigue damage dominated by mode I failure mechanism and mode II failure mechanism, respectively. Cruces et al 181 modified their forms to consider the effect of mean stress, as follows:…”