STUDY ON STRICTLY DECOUPLING AND OPTIMIZATION DESIGN OF AUTOMOTIVE POWERTRAIN MOUNTING SYSTEM

At present,the main task of designing a mounting system of automotive engine powertrain is to select appropriate stiffness,position and angle of mounting components so that free-vibration modal frequency of the mounting system can avert from the exciting-force frequency at the idle speed of the engine and the natural frequency of vibration of the vehicle body and that the decoupling degree of each mode shape is increased as far as possible,so as to improve the vibration-isolation effect of the mounting system. The design of a mounting system based on strict decoupling at predetermined frequencies is to make the modal frequencies of the designed mounting system completely equal to the frequencies predetermined in accordance with the frequency planning of automotive design,and to enable strict decoupling of each mode shape of each mode,i.e.,the decoupling degree of vibration energy in every direction equals to 1. Based on a free-vibration equation for a mounting system,this paper presents an equation system for designing a mounting system with strict decoupling at predetermined frequencies,discusses about the properties of the solution of this equation system by using the theory of generalized inverse matrix,and gives a solving method for this equation system by algorithm of generalized inverse matrix,so as to provide an optimal design method more efficient and simpler than the current modal optimization method of mounting system. Relevant example has validated the correctness of equations and solving method of the strict-decoupling design at predetermined frequencies.