3D-Durability Analysis of Crankshafts via Coupled Dynamic Simulation including Modal Reduction

The combination of multi purpose software with powertrain specific application codes allows highly flexible simulation models, which are independent on the specific engine concept. Related to the requests those models may be refined or simplified during the simulation process. Finally a fully coupled 3D dynamic simulation including flexible components is performed to assess the engine crankshaft's durability. To take into account the stiffness of the cranktrain components and the cylinder block at first a linear Finite Element Analysis (FEA) simulation is performed. Via modal reduction the complete deformation order information of the FEA simulation are reduced to the necessary information for the dynamic Multi Body System (MBS) simulation [1, 2]. All main boundary conditions of the system, e. g. gas forces, oil temperature or driveline application are taken into account. To cover the engine's complete rpm range, a set of steady state analyses is performed to evaluate possible resonances, the minimum safety factor, the rpm at which it occurs and its physical location. For selected rpm values the 3D distribution of the safety factors with local high resolution, the maximum mean and amplitude stresses and the deformations are investigated. The dynamic result evaluation supports the understanding of loading mechanism and the occurrence of safety factors.