镁合金曲轴箱盖的试验模态分析

Experimental Modal Analysis on Crankcase Cover of Magnesium Alloy

研究了镁合金材料(AZ91D)替代铝合金材料(A380)后曲轴箱盖的动力学性能表现,运用锤击法分别对结构相同的镁合金和铝合金发动机曲轴箱盖进行了试验模态分析。研究表明:镁合金和铝合金材料属性参数之间内在关系决定了两种材料曲轴箱盖的固有频率和振型较为接近;虽然镁合金材料具有良好阻尼减振性能,但镁合金曲轴箱盖刚性较低,在结构相同条件下其频响函数曲线整体上反而要略高于铝合金曲轴箱盖,存在结构优化的必要性;在几何结构相似条件下两种材料固有频率和固有振型等模态参数的接近,有利于实际工程中两种材料的替换。

To understand the dynamic behavior of crankcase cover made of magnesium alloy in compari- son to aluminum alloy crankcase cover, experimental modality analysis of the crankcase covers made of magnesium alloy and aluminum alloy was condmcted by means of the hammering method. Research result shows that similarity on modal parameters of the crankcase covers with different materials is depended on inherent relationship between the attribute parameters of these two kind materials. However, compared with the aluminum alloy crankcase cover, the magnesium alloy crankcase cover has a lower stiffness, and has a higher curve of the frequency response function. Therefore, it is necessary for the magnesium alloy crankcase cover to optimize its structure and exert its good performance in shock absorption. In general, in the case of the same structure, these two kind material have the similar modal parameters, so it is favorable for replacement between these two kind materials in practical engineering application.