轨道列车用铝合金弯曲变形在线监测信号分析

Online monitor signal analysis on aluminum bending deformation for railway vehicle

为了研究轨道列车用7N01铝合金弯曲变形过程中不同变形阶段产生的声发射信号特征,采用小波包分析方法,利用db5小波函数对信号进行3层分解,并计算8个子频带的能量,构造了基于能量元素的特征向量。通过对比分析不同变形状态(塑性变形、裂纹萌生、裂纹扩展)的声发射信号特征向量以及能量分布比例,发现铝合金变形各阶段声发射信号的主能量频带都处于低频,但裂纹扩展信号的高频带能量比例明显高于塑性变形及裂纹萌生。

In order to study the acoustic emission signal characteristics during the bending deformation period of 7N01 aluminum alloy adopted for the railway vehicles,the characteristics vector based on the energy element is built by using wavelet packet analyzing method and db5 wavelet function to disintegrate signals in three- layers and to calculate the energy of eight sub frequency ranges.By comparing the acoustic emission signal characteristics vector and energy- distribution proportion during different deformation periods,including plastic deformation,crack initiation and crack propagation,it is found that the main energy frequency range during the bending deformation period of the aluminum alloy is under low frequency while the energy proportion of high frequency range of the crack propagation is higher obviously than that of plastic deformation and crack initiation.