基于频率变化识别结构损伤的摄动有限元方法

在结构有限元计算模型中定义了单元的损伤识别参数,将摄动理论与振动理论相结合导出结构振动特征值的一、二阶摄动方程,并由此建立了结构的一、二次损伤识别方程,给出了两种方程在欠定情况下求解损伤识别参数的优化算法。该方法仅使用在役结构固有频率测量值就能识别出结构的损伤位置和损伤程度,以及结构的老化程度,避免了使用模态振型识别结构损伤,因测量精度不高或自由度不足带来的误差。通过一座连续梁桥损伤识别的数值仿真结果,证明了该方法的有效性和实用性。该方法可用于大型结构的损伤识别或健康监测。

THE PERTURBATION FEM TO IDENTIFY DAMAGES BASED ON FREQUENCY CHANGES

The definition of element damage identification parameters in finite element method (FEM) is firstly presented. The 1st and 2nd perturbation equations for structural vibration eigenvalue problems are derived by combination of perturbation and vibration theories. The related optimization algorithms of these equations (in un-determined situation) for solving damage identification parameters are also proposed. Structural damage location and severity as well as structural aging can be detected using the proposed method with measured frequencies. The proposed method avoids the errors caused by low measurement accuracy or insufficient degrees of freedom when using traditional mode identifying method. Numerical simulation showed the validity of the presented approach. It can be utilized in health monitoring and damage detecting procedures.