基于混合建模的发动机曲轴模态分析

开展了发动机曲轴在自由状态和安装状态下的模态参数识别,发现曲轴的边界条件对模态参数影响较大;研究了曲轴试验模态与仿真模型的混合建模方法,计算得到曲轴在约束状态下的模态结果。研究结果表明,利用混合建模的方式可以将曲轴自由模态结果转换为实际安装状态下的约束模态,以用于评估曲轴实际工作过程的动态特性,同时得到了气缸压力对曲轴约束模态影响较小的结论。混合建模的方式结合了试验和仿真的优点,提高了曲轴约束模态的分析精度,降低了试验限制条件,为评估曲轴动态性能和发动机动力学分析创造了更准确的条件。

Modal Analysis of Engine Crankshaft Based on Hybrid Modeling

The identification of modal parameter for engine crankshaft in the free and fixed state was carried out.It was found that the boundary condition of crankshaft had great influence on the modal parameters.The hybrid modeling method of crankshaft test mode and simulation model was studied and the modal results in the constrained mode were acquired.The results show that the hybrid modeling method can convert the free mode results of crankshaft into the constrained mode that corresponds to the real fixed state in order to evaluate the dynamic characteristics of actual crankshaft operating process.In addition,it is confirmed that the in-cylinder pressure has less influence on the crankshaft restraint mode.The hybrid modeling method has the advantages of both experiment and simulation,improves the analysis accuracy of crankshaft constrained mode and reduces the test constraints,which provides more accurate conditions for evaluating the crankshaft dynamic performance and analyzing engine dynamic characteristics.