基于随机振动响应相干函数的梁结构损伤检测

摘要

A beam's damage detection method based on coherence function of its random vibration was presented here.It was based on the principle that the nonlinearity of a structure's dynamic responses increases after its local structure suffering a loss of stiffness due to damage.Furthermore,a modified local damage factor (MLDF)method was proposed. This method was capable of determining the presence,severity,and location of structural damage at the same time.By including the dynamic characteristics of the intact local structure in this method,the influences of structural nonlinearity, imperfections,and system noise were considered,so the accuracy of damage detection was improved.As a demonstration, the tests of a cantilever beam with different magnitudes of local damages were conducted to validate the proposed method. The experimental results indicated that the method can be used to detect single-crack and multi-crack of the cantilever beam accurately and reliably.%损伤通常会减小结构的刚度，增加结构动力响应的非线性程度，基于该原理，提出了基于随机振动响应相干函数的梁结构损伤检测的方法，并推导出判别损伤的改进型局部损伤因子（MLDF）。该法考虑了结构本身非线性和系统噪声的影响，提高了检测精度，根据 MLDF 出现的位置以及大小可以对损伤进行定性和定量的分析。通过不同工况下悬臂梁的随机振动试验研究，验证了该方法对识别梁结构单裂缝损伤与多裂缝损伤的准确性和可靠性，表明此法可有效地检测梁结构中损伤的程度和位置。