Application of FEM and Evaluation Method for Connecting Rod Design

A structural analysis for the connecting rod was performed in consideration of bearing crush, oil clearance and initial deformation of the big end bore caused by tightening force of the rod bolts. This analysis enabled to calculate not only the bearing pressure distribution but also the three-dimensional stress state with accuracy.

A new fatigue criterion for multi-axial out-of-phase stress was proposed by using mean stress tensor and alternating stress tensor of complex number in this study. This criterion was developed to improve the classical multi-axial “yield criteria”. This criterion is simple, comprehensive and suitable for the evaluation of three-dimensional FEM results.

The connecting rods exhibiting high reliability under severe conditions were investigated through the stress analysis and the new evaluation criterion.