CRANKSHAFT STRESS-ANALYSIS - COMBINATION OF FINITE-ELEMENT AND CLASSICAL-ANALYSIS TECHNIQUES

The conflicting legislative and customer pressures on engine design, for example, combining low friction and a high leicl of refinement, require Sophisticated tools competitive designs ate to be realized. This is particularly true of crankshafts, probably the mast analyzed of all engine components This paper describes the hierarchy of methods used for crankshaft stress analysis with case studies. A computer-based analysis system is described that combines FE and classical methods to allow optimized designs to be produced efficiently. At the lowest level simplified classical techniques arc integrated into the CAD-based design process. These methods give the rapid feedback necessary to perform concept design iterations. Various levels of FE analysis are available to carry out more detailed analyses of the crankshaft. The FT. studies may feed information to or lake information from the classical methods. At the highest level a method far including the load sharing effects of the flexible crankshaft within a flexible block interconnected by nonlinear oil films is described. This method includes the FE modeling of the complete crankshaft and the consideration of its stress field throughout an engine cycle Fatigue assessment is performed to calculate the distribution of fatigue safety factor on the surface of the crankshaft. This level of analysis can be used for failure Ininstigation, or detailed design optimization and verification. The method is compatible with those used for vibration and oil film analysis. © 1990 by ASME.