镁合金AZ91D的阻尼减振性能

为了解镁合金减振效果与频率、振幅等因素的关系，对AZ91D镁合金的实际减振行为有明确的把握，对镁合金AZ91D、变形镁合金AZ31、铝合金以及钢4种材料进行室温下的阻尼－频率测量，发现在相同振幅和频率下，镁合金AZ91D具有比铝合金、钢和变形镁合金高出3～5倍的阻尼性能，并在6 Hz左右出现阻尼峰。通过对镁合金与铝合金发动机箱盖在冲击脉冲载荷作用下的振动进行三阶模态分析，发现镁合金试件的阻尼比，除第三阶比铝合金试件稍微偏小外，其余各阶均高于铝合金试件。镁合金试样的第一阶模态阻尼比比铝合金试件高出17.6%，而第二阶模态阻尼比高出41.3%，另外镁合金试样的第一阶模态质量比铝合金试样高出45.0%，而第二阶模态质量高出15.3%，表明镁合金发动机箱盖在使用中镁合金的稳定性、抗冲击性能以及对冲击载荷的减幅等方面都具有良好的动力学表现。

VIBRATION DAMPING CAPACITY OF AZ91D MAGNESIUM ALLOYS

To understand damping capacity of magnesium at different frequency and amplitude of vibration, damping-frequency curves of AZ91D, AZ31, aluminum alloy and steel are measured at room temperature. It reveals that AZ91D has the best damping capacity among the mentioned four materials and a damping peak is found at frequency 6 Hz. To know its damping action in real use, the dynamic mechanical characteristics of magnesium engine box cover and aluminum engine box cover are studied by means of the experimental modal analysis technique. It is found that the first and the second stages of modal damping ratio of magnesium engine box cover are 17.6% and 41.3%, higher than the aluminum engine box cover individually. The first and the second stages of the modal mass of magnesium engine box cover are 45.0% and 15.3%, higher than the aluminum engine box cover individually. These reveal that magnesium alloys have better shock absorption and better stability in appliance.