SAE 2017-01-0329 : 2017

Driveline and suspension notched components of off-road ground vehicles often experience multiaxial fatigue failures along notch locations. Large nominal load histories may induce local elasto-plastic stress and strain responses at the critical notch locations. Fatigue life prediction of such notched components requires detailed knowledge of local stresses and strains at notch regions. The notched components that are often subject to multiaxial loadings in services, experience complex stress and strain responses. Fatigue life assessment of the components utilizing non-linear Finite Element Analysis (FEA) require unfeasibly inefficient computation times and large data. The lack of more efficient and effective methods of elasto-plastic stress-strain calculation may lead to the overdesign or earlier failures of the components or costly experiments and inefficient non-linear FEA. An analytical computational model is developed to calculate actual elasto-plastic stresses and strains of notched components based linear-elastic FEA solution. The model is based on the integration of the material constitutive theory and the multiaxial notch correction method along with computational modeling techniques. The computation model is validated using non-linear FEA data of 1045 steel notched bar/shaft subjected to non-proportional multiaxial loadings. The comparison showed that calculated notch elasto-plastic stresses and strains from the model are in good agreement with the non-linear FEA data. The model is further assessed against experimental fatigue data of SAE 1045 steel notched shaft under multiaxial loadings. The notch stresses and strains estimated by the model have been subsequently used to perform fatigue life predictions and predicted lives showed good correlations with experimental fatigue data of the SAE 1045 steel notched shaft.

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