柴油机动力总成异常振动的模态分析

Modal Analysis of Abnormal Vibration for the Diesel Engine Power Train

针对柴油机动力总成在常用工作转速条件下产生异常振动的实际问题,采用试验模态与有限元计算模态分析相结合的方法,研究了各种条件下动力总成的动态特性。首先开展了整车和台架条件下动力总成的振动模态试验,找到了导致动力总成异常振动的原因-动力总成弯曲刚度偏低,然后建立了一种符合实际情况的动力总成有限元仿真模型,并计算了约束模态,验证了所建仿真模型的合理性。综合模态试验与计算模态分析表明,飞轮壳刚度偏低易导致动力总成系统一阶固有频率落入柴油机工作转速的激励频率区间而产生系统共振。

In the light of the abnormal vibration at the normal operating speed for the power assembly, dynam- ic characteristics under the various conditions were studied, taking the testing modal and finite element modal analysis together. The vibration modal test of vehicle and chassis dynamometer is firstly developed to find out the vibration reason of which power train bending rigidity is lower. Then power train FEA simulation model is established according with the actual conditions, and the constraint mode is calculated. The modeling is proved reasonable. Synthesizing the modal test and calculation modal analysis, it shows that the low rigidity of flywheel will lead to the first-order natural frequency of power train locating into the range of working speed ex- citation frequency of diesel engine, which causes the system resonance.