Prediction Technique for Stress and Vibration of Nonlinear Supported, Rotating Crankshafts

Abstract

Design analyses of crankshafts, including bearings, are necessary for both the layout of new engines and the modification of existing engines (increased power output, etc.). To improve the existing calculation systems for crankshafts and bearings, AVL has developed a new method. This method enables the coupled vibrations in the torsional, bending, and axial directions, including gyroscopic effects, to be analyzed. For simulation of multibearing effects, the bearing models consider both the hydrodynamic oil film and the stiffness of the bearing structure. The calculation of forced vibrations is carried out using the gas and mass forces acting upon the rotating crankshaft. Comparisons of calculated to measured results demonstrate the accuracy of this calculation technique. The method can be used for passenger car, truck, and medium speed engines. In this paper examples of truck and passenger car engine applications confirm the additional possibilities for the estimation of crankshaft dynamics. Also the improvement of the results obtained from the new technique compared with those from classical calculation methods is described.