基于S变换和互信息的梁类结构裂纹定位方法

Crack Location Method for Beam-Like Structures Based on S Transformation and Mutual Information Entropy

实际使用中的梁类结构容易萌生裂纹,影响其使用寿命及安全可靠运行,准确判定其裂纹损伤位置对于实现梁类结构的快速准确维护处理具有重要意义,为此提出基于振动信号S变换和互信息值实现梁类结构裂纹的识别与定位。首先,基于测试获得梁类结构上分布点的振动信号;其次,利用S变换将振动信号变换到时频域,计算梁结构在裂纹损伤前后各对应位置点时频域振动信号的互信息值;最后,通过检索互信息值向量中分量的最小值位置实现裂纹区域的准确定位。为了避免引入附加质量的影响,利用机器视觉测振系统采集悬臂梁和小型复合材料叶片上的分布点振动信号,设置不同裂纹位置对梁类结构裂纹定位方法进行了验证,证明了方法的有效性。

Cracks often occur in beam-like structures,which are prone to shorten the structures′service life and decrease their reliability.Accurately locating the crack damage is of great importance for the rapid and accurate maintenance of beam structures.In light of this problem,a crack location method is proposed for beam-like structures based on S transformation and mutual information entropy.First,the vibration signals are measured and transformed into time-frequency domain by S transformation.Then,the mutual information entropy of the time-frequency signals is computed before and after the beam-like structures are damaged.The damaged area is located by retrieving the minimum component in the mutual information entropy vector.In order to avoid the influences of the additional mass of measurement system,the machine vision system is employed to measure the distributed vibration responses of cantilever beams and composite blades.The damage locations are successfully identified by the proposed method and the effectiveness of this method is verified.This method can enrich vibration-based methods for structural damage detection in engineering applications and academic research.