弯管结构模态柔度曲率差法损伤识别

Modal flexibility-curvature and difference in damage identification of bend-type structures

对弯管结构进行损伤识别,采用模态柔度比结构的频率或位移模态更灵敏,且模态柔度仅需结构的低阶频率和振型就可准确地计算。采用有限元方法,以一弯管为仿真算例,以结构模型的单元刚度的下降来模拟损伤。结果表明:弯管结构的模态柔度具有方向性,弯管所在平面x、y方向柔度求解的模态柔度曲率差不能对弯管进行频率损伤识别,垂直弯管所在平面z方向柔度不仅可以对弯管进行单处、多处的损伤定位,而且可以对同一位置的损伤程度进行定量分析。

As for the damage identification of bend-type structures, modal flexibility is more sensitive than the modal frequencies and displacement. Only according to the first few orders can the modes be easily calculated. With a bend-type as an simulation example, it is damaged due to a decrease in ben- ding stiffness of several elements on predefined location. The results show that the modal flexibility of bend-type has the characteristic of the direction. In addition, using the plane x, y direction to solve the modal flexibility curvaturers difference cannot be suitable for the damage identification of the bend. But by using the vertical pipe where the bending flexibility exists in the plane z direction, it is possible to localize a single or multiple damage and also do a quantitative analysis of the degree of damage in the same position.