This paper presents the mathematical formulation and procedure of an ongoing developmental work on the optimum design of engine and body mounts at a total system level. The LOHITSA/SYS OPT computer software, a total system level non-linear unconstrained optimizer with built-in component mode synthesis solution technique, is used. The aim is to develop the optimum engine and body mount characteristics. The main goal of the paper is to minimize the forces transmitted into the body structure in order to reduce the tactile and acoustic response with constraints on geometry and material properties, and manufacturability. A forced frequency response optimization with component mode synthesis technique is used. The aim is to develop various sets of mount stiffnesses that satisfy all constraints and results in minimum transmissibility corresponding to each excitation frequency. A selection scheme is used to identify a set of optimized values of the constraints which will produce minimum transmissibility over a wide frequency range of interest. Engine excitations and the road load induced excitations are simulated using unit harmonic excitations over a wide frequency range. However, the software is capable of handling actual forcing functions with real and imaginary or magnitude and phase components.
Abstract