车用动力总成模态优化研究

The Study on Modal Optimization in a Powertrain

针对某车用动力总成试验过程中发动机和变速器结合面渗油的情况,运用有限元模态分析和试验模态分析相结合的方法,研究动力总成的固有模态。结果表明,动力总成一阶模态只有176.1Hz,低于发动机最高转速下的点火激励频率,存在发动机运转过程中在某个转速点产生共振的风险。经过有限元模态分析一阶模态阵型,显示薄弱位置在缸体、油底壳与变速器的结合面处;通过对缸体和油底壳增加加强筋进行优化,使动力总成的一阶模态提高到240.2Hz,比优化前提升了36.4%,二阶模态也提升了22.5%。优化后的动力总成试验模态分析结果表明:该方案提高了动力总成固有模态。

Aim the oil-leakage problem during the powertrain test,Combining finite element modal analysis with modal experiment,to study the vibration modes of powertrain.The result show,The first-order mode of the powertrain is only 176.1Hz,Lower than the ignition excitation frequency of the engine,have a risk of resonance.Through finite element modal analysis,find the first-order mode on the junction surface cylinder of the block、oil pan and transmission is lower;add the reinforcing bar on the cylinder block and oil pan,Improve the first-order mode of powertrain to 240.2Hz,increased by 36.4%,and second-order mode also increased by 22.5%.The optimized test modal shows that:the natural frequency of the powertrain increased.