时域内梁式结构的两阶段裂缝诊断方法

提出诊断梁式结构中裂缝的位置和尺寸的一种时域两阶段方法．基于时域内的位移响应，结合正则化技术和假设检验，用平均曲率相对变化率表示的损伤指标来诊断梁式结构中边缘张开型裂缝的位置．应用线弹性断裂力学中的应变能释放率和应力强度因子与裂缝尺寸的解析关系式，推导出了时域内的裂缝尺寸模型来识别裂缝的尺寸．通过将裂缝模拟为扭转弹簧的有限元仿真分析，研究了文中方法的可行性，结果表明，应用该方法能够在较高的置信区间内准确地识别梁式结构中多处裂缝的位置，在一定精度内诊断出裂缝的尺寸．用受噪声污染的损伤指标与尺寸模型进行裂缝诊断结果表明，该方法对测量噪声具有良好的鲁棒性．

A Two-Stage Crack Detection Method for Beam-Type Structures in Time Domain

A two-stage method in time domain to detect the location and size of cracks in beam-type structure is proposed. Based on the displacement responses in time domain and combined with the regularization technique and hypothesis testing, a damage index expressed with relative variation rate of the mean curvature is used to detect the location of the opening mode edge cracks in beam-type structure. By employing the analytical relationship between the strain energy release rate and the stress intensity factor in linear elastic fracture mechanics and the size of crack, a model of crack size in time domain is derived to detect the size of crack. Through the finite element simulation in which the crack is simulated as a torsional spring, the feasibility of the proposed method is investigated. The results show that by employing the proposed method, the locations of multiple cracks may be detected precisely in high confidence range, and the sizes of the cracks may be detected in a certain accuracy range. The damage index and size model polluted by noise are used to detect cracks and the results show that the proposed method has good robustness against measuring noise.