基于剩余模态力和模态应变能理论的网架结构损伤识别

DAMAGE DETECTION OF SPACE TRUSS USING RESIDUAL MODAL FORCE AND MODAL STRAIN ENERGY

针对网架结构特点,引入敏感模态的概念,提出了一种识别敏感模态的算法;基于剩余模态力理论,利用敏感模态进行损伤位置识别,并建立了基于模态应变能理论的损伤程度评估算法,采用非负最小二乘法求解超静定方程组,实现定量评估损伤程度。以某实际结构为仿真对象,分析了上述算法在网架结构损伤识别中联合应用的可行性,同时将评估结果与基于最小秩摄动理论的损伤程度评估结果进行了比较研究,并考虑测试噪声影响。结果表明,二者联合工作效果较好,不仅可以识别结构单处损伤,还可以识别结构多处损伤,且损伤程度评估结果同基于最小秩摄动理论损伤程度评估结果比,更可信,将其应用于网架结构的健康诊断是可行的。

Based on the characteristics of space truss structures, the concept of sensitive mode shape is introduced and an algorithm for its determination is presented. The damage location is determined based upon the residual modal force theory and with the assistance of sensitive mode shape. An evaluation algorithm based on the modal strain energy theory is given adopting an indeterministic equation group solved by the non-negative least-square method to quantitatively identify the damage extent. A practical space truss structure is used in the simulation to demonstrate the feasibility of the proposed algorithms on damage detection of space truss structures. Meanwhile the evaluation results on the damage extent are compared with those obtained by using the minimum rank perturbation theory with the consideration of measurement noise in the mode shape. The results show that the two methods are complementary to each other. They are both applicable to not only single damage but also double damages. The damage evaluation result is better and more reasonable than those obtained by only the minimum rank perturbation theory. It is feasible to be applied in fault diagnosis of space truss structures.