Objective The diesel engine unit of a certain type of high-speed diesel multiple unit (DMU) generates exciting forces with large amplitude and complex frequency during operation, leading to severe vibration in the driver's cab and potential safety hazards. Therefore, it is necessary to study the vibration characteristics and vibration reduction of the diesel engine unit.

Method A rigid body dynamics model of single-layer vibration isolation system for the power pack is established, and the initial stiffness parameters of the single-layer vibration isolation system are designed based on vibration isolation theory and static load support conditions. A refined finite element model of the diesel multiple unit car body including the power pack is established to study the vibration characteristics of the car body under the power pack excitation. Taking the three-way stiffness of the vibration absorber as the design variable and the maximum force transmissibility at the car body reference point as the optimization objective, the global response surface method is used for multi-objective optimization, and the finite element model is used to verify the accuracy of the optimization prediction. Considering the coupling effect of other excitations such as wheel-rail excitation, the rationality of the optimized stiffness parameters of the vibration isolation system is verified through tests and simulation calculations.

Result & Conclusion  After the optimization of vibration isolation design, the force transmissibility at the central floor of the driver's cab is reduced from 44.05% to 32.45%. Under different operating speeds, the comfort indicators in the middle part of the driver's cab all meet the requirements, indicating that the vibration isolation design method can effectively improve the vibration isolation effect of the diesel engine unit vibration isolation system.