A cohesive zone model approach to multiaxial fatigue
Multiaxial fatigue crack initiation in standing contact fatigue is investigated utilizing an irreversible cohesive zone model. Fatigue crack initiation by irreversible cohesive zones in finite element models are compared to the prediction of crack initiation of the Findley multiaxial fatigue criteria due to standing contact fatigue. In contrast to the use of multiaxial fatigue criteria, the present method provides an incremental approach to damage accumulation as well as a method to predict the number of cycles to crack initiation. Such an approach allows the investigation of damage accumulation due to variable amplitude loading. Current multiaxial fatigue criteria utilize the Palmgren-Miner rule in conjunction with cycle counting methods but are known to provide incomplete insight. The model definition, its numerical implementation and its application to both constant and variable amplitude loading for standing contact fatigue crack initiation is reported. By comparison to experimental data from literature, results showed that the current method to predict crack initiation due to standing contact fatigue was able to capture the crack initiation location for constant amplitude loading. The developed model was able to capture changes in loading and geometry in variable amplitude loading which leads to non-linear damage accumulation. The finite element model was created and analyzed utilizing the ABAQUS software package.^
Thomas H. Siegmund, Purdue University.