Modelling of Engine Suspension Components for Crash Simulations

Abstract

Explicit finite element analysis (FEA) simulations are widely used in the product development of cars to evaluate their crash safety. Thus helping save substantial amount of resources required if only physical testing was to be used. At present there are several areas where simple modelling techniques are still used, primarily because of limited knowledge about the detailed behaviour of the system in a crash. One such area is engine suspension components, e.g. engine and gearbox mounts. The objective of this thesis work is to develop new and improved finite element (FE) models for engine suspension mounts to be used in full vehicle crash simulations. These components play an important role in both high-speed crashes wherein failure occurs in the engine mount and in low speed crash where the dynamic properties of the engine mount are of interest in capturing the motion of the components in the engine bay. The new model should replace the usage of multi dimensional spring elements currently used in the existing models at Volvo Car Corporation (VCC). The methodology used to achieve the objective was to perform component and sub assembly level tests in Fall Rig and correlate the test results by conducting simulations in the explicit solver LS-DYNA. Material models derived from the fracture curves are used to visualize the crack propagation in the aluminium casting. A detailed FE model for engine mount has been developed from the observations made during correlation of Fall Rig tests. The new model was incorporated in the full vehicle crash simulations. The new model showed good agreement with the existing model for the engine mount and observations from actual crash tests.