bstract : The μ multi-objective genetic algorithm is used to optimize the damping values of the controllable vibration damper. The damping parameters of the front and rear suspension are selected as the optimization variables, and the MSR values of the body vibration acceleration, the suspension travel movement and the tyres dynamic displacement are selected as the optimization objective. The three-levels damping values of the controllable vibration damper are optimized design by considering the characteristics of the different load, speed and road surface level for the suspension system at the same time. According to the optimization results, the three-levels damping values of the controllable vibration damper are confirmed, i.e. "soft-middle-hard". The suspensions simulation test proved that this algorithm is a kind of high efficiency of the multi-objective global optimization method.

Based on acoustic FEM, the transmission losses of three mufflers with different combinations of perforated tubes were computed. The influences of the perforation porosities of the tubes on the transmission losses of the mufflers were discussed. Then, the acoustic performance of a complicated muffler with multiple perforated tubes was stimulated. The result shows that the transmission loss of the muffler is low when the noise frequency is below 1 000 Hz. This work provides a reference for further improvement of the muffler.