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。
Abstract
A structural damage detection method based on the coherence function of random vibration is presented in this study, and is based on the principle that the nonlinear severity effect between the local and entire structure will increase if the local structure suffers a loss of stiffness due to damage. Furthermore, a modified local damage factor (MLDF) method is proposed. This method is 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 influence of structural nonlinearity, imperfections, and system noise is considered, so that the accuracy of damage detection is improved. As a demonstration, the experiment of a cantilever beam with different magnitudes of local damage is conducted to validate the concept. The experimental results indicate that the method can be used to detect the single-crack and multiple-cracks of cantilever beam accurately and reliably.
关键词
悬臂梁 /
损伤检测 /
相干函数 /
随机振动 /
非线性
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Key words
cantilever beam；damage detection ; /
coherence function；random vibration； nonlinearity
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