Abstract: Vibration character analysis for the powertrain system of a diesel engine has been accomplished by means of the FEM based on multi-body dynamics model. The loading conditions applied to the diesel engine and the gear box are very similar to the practical situation, for example the connections between the engine and the gearbox are simulated by preload bolts and the headstock loads are simulated by the compressive elements without extension. The results show that the vibration level in the surface of the bottom shell of the engine is the highest. So, it is suggested that the ribbings be used in the side wall of the bottom shell. Since the vibration level of the engine surface increases gradually from the bottom to the top of the engine, it is suggested that composite material and high damping material be used to reduce the vibration level of the engine.

Key words: vibration and wave, powertrain system, diesel engine, gear box, multi-body dynamics, FEM

摘要： 以某动力传动系统(柴油机和齿轮箱)为工程背景，基于多体动力学和有限元方法，在加载方式与实际情况尽量一致的原则下(柴油机和齿轮箱的连接方式采用具有预紧力的螺栓模拟，主轴承的加载采用只具有压缩而不具有拉伸的单元模拟)，对系统进行振动特性预估，结果表明：对该系统来说，油底壳是表面振动最为恶劣的部件，建议通过诸如添加加强筋等方式加强油底壳侧壁和底板的刚度；由于上曲轴箱两侧壁自上而下有刚度逐渐弱化的趋势，因此越接近上箱裙部，柴油机结构表面的振动情况越为恶劣；同时，对结构施加合适的阻尼对结构振动将有很大影响，复合材料或高阻尼材料的使用是降低系统振动等级的有效方法。

关键词: 振动与波, 动力传动系统, 柴油机, 齿轮箱, 多体动力学, 有限元