镁合金AZ31阻尼性能的实验研究

Experimental study on damping performance of magnesium alloy AZ31

采用脉冲响应衰减法研究镁合金AZ31的减振降噪效果.由脉冲激励激发镁合金薄板自由振动,测得镁合金薄板表面的辐射声压,将声压信号进行带通滤波,分离出薄板各个简正振动对应的辐射声压,或分析带宽内几个简正振动产生的复合声压,将该声压信号曲线进行多项式拟合,由拟合曲线的斜率得出镁合金的阻尼损耗因子,并与钢的阻尼性能进行比较.结果表明,镁合金的阻尼损耗因子随频率的增大逐渐减小,在660、1090、1230和1760Hz处存在阻尼峰值,是减振性能最佳的频率.在中低频段,镁合金的阻尼性能约为钢的2、3倍.镁合金构件在使用中必将体现出良好的抗冲击和减振降噪性能.

Vibration damping and noise reduction effects of magnesium alloy AZ31 was researched with the impulse response decay method （IRDM）.The free vibration of magnesium alloy sheet was excited by a pulse excitation,and the sound pressure near the magnesium alloy sheet was measured.The radiated sound pressure due to one normal vibration mode or the complex sound pressure due to few normal vibration modes in one frequency band was isolated by a band-pass filter from the measured sound pressure signals.The damping loss factor （DLF） of the magnesium alloy was obtained by the slope of the polynomial fitting curve for the sound pressure signal,and compared with that of steel.The results showed that the DLF of magnesium alloy decreases with the increase of frequency.Many damping peaks appear at 660,1 090,1 230 and 1 760 Hz,which are most suitable for the vibration reduction.In the low-mid frequency range,the damping capacity of magnesium alloy is 2 to 3 times higher than steel＇s.Therefore,magnesium alloy components will show excellent shock absorption,vibration damping and noise reduction performance.