| In predicting the fatigue lives of structural or mechanical components, there are several multiaxial fatigue theories that can be used to evaluate the fatigue crack initiation. However, there exists a lack of agreements on which theory models the fatigue crack initiation most appropriately.; The purpose of this thesis is to evaluate the validity of most commonly used multiaxial fatigue criteria; specifically the maximum principal strain and the maximum shear strain criteria. Moreover, a new criterion based on strain energy density is proposed and evaluated for elastic and elastic-plastic damage scenarios. The best criterion, identified through comparative analyses, is used to evaluate the fatigue lives of two connecting rods supplied by an automotive company.; Three-dimensional finite element analysis is performed on the SAE notch shaft, which is used as a test component to evaluate the validity of the existing and proposed multiaxial fatigue damage criteria. Elastic and elastic-plastic stress-strain responses are then used to obtain the required damage parameters that are eventually used to predict the fatigue lives. (Abstract shortened by UMI.)... |
