大功率发动机机体与曲轴组合结构自由模态分析

应用有限元法分析软件，建立了某大功率发动机机体与曲轴组合结构的有限元模型，并进行了动态特性研究，得到了组合结构的自由模态参数；与实验结果基本吻合，证明了所建模型的正确性。在建立有限元模型时，利用模拟试验，定性分析了曲轴与机体结合部的连接特性，提出了用弹簧单元来模拟油膜接触刚度的方案。分析得到，对于机体与曲轴这类组合结构，其刚度主要取决于机体，曲轴相对于机体是柔性的。因此，在以避免共振为设计目的时，应主要考虑优化机体的刚度。

Composite Structure Free Modal Analysis of High Power Engine Block and Crankshaft

Applying FEM technology, the finite element model of one high power engine is established, in the meanwhile the dynamic property of its composite structure is studied in this paper. The modal parameters achieved by finite element analysis coincide with those achieved in experiment, which shows the correctness of the models. With the experimental facility, the feature of interface between axes and bearing is studied,the method of spring element simulating oil film is provided,the dynamic property of the combination structure is analyzed. The conclusion is that the toughness of combination structure lies on the engine block,and compared to the engine block,the crankshaft is flexible.In conclusion, when the design target is to avoid system resonance vibration,the engine block toughness should be taken into account mainly.