Structural Optimization in Multibody Dynamics System With FEM Model on Engine Components

This paper describes the structural optimization technique with FEM optimization technology. The design shape of engine components have been optimized with consideration of dynamic effects. In the conventional approach of structural optimization in a Multibody Dynamics (MBD) system, the loads on FEM models of components as boundary conditions for subsequent shape optimization were used to be an output from MBD analysis. When an MBD system was optimized in MBD analysis, the body properties were used to be optimized instead of component shape. In this study a special modeling approach is followed to capture the loads easily and accurately with respect to contact behavior of metal bearings existing in engine components in order to improve the conventional approach with rigid elements. This approach is applied to the piston-crankshaft system of a one-cylinder engine. Topology optimization is performed to detect the effective design parameters of connecting rod (con-rod) shape to reduce weight prior to the shape optimization. Shape optimization of the con-rod results in a 6% weight reduction under the condition of critical compression loading just after the TCD (top dead center) of the combustion process. Furthermore, the structure modification for a piston based on an FE model also inside MBD analysis is performed. The base vectors of FEM morphing technology are used as design variables instead of body properties. These techniques are advanced approaches of structure modification based on FE model for MBD system.