Assessment of numerical models for multiaxial fatigue

The objective of this research work is to assess existing models for different loading conditions. The approach is based on the experimental research findings of the Society of Automotive Engineers (SAE), which is used as a benchmark. The models are classified into three categories: (i) Empirical formulas based on modification of the Coffin-Manson equation; (ii) Critical plane models which are based on physical observation that fatigue crack initiate and grow on certain planes; (iii) Damage mechanics models based on energetic thermodynamic approach. The first two categories of models are implemented in commercial software "FE-Fatigue". The software uses the results of linear finite element analysis to determine the critical locations. The fatigue life prediction is therefore evaluated based on the stress-strain distribution obtained from the finite element analysis. The continuum damage mechanics approach uses a fundamental formulation based on energetic thermodynamics. This technique integrates an elasto-plastic-damage locally coupled constitutive law in the critical location where plastic deformation is accumulated. Based on its nature the continuum damage mechanics approach is restricted to low cycle fatigue. (Abstract shortened by UMI.)...