基于线性多点逼近方法的结构局部非线性损伤识别

Structural local nonlinear damage identification using a multi-point approximations method

结构损伤通常伴随一定的非线性响应特征,当非线性特征较为明显时,单纯的有限元更新方法无法克服本身所固有的非线性特征的限制,在动力特性测试中也存在许多困难.本文研究时域内损伤识别方法,将局部非线性结构损伤等效为一个的附加子结构,基于线性多点逼近方法,将一个非线性损伤识别问题转化为作用于线性模型的载荷识别问题.通过结构非线性响应识别出等效附加力的时间历程,利用附加子结构的输入输出特性识别实际结构的单元损伤特性.在所提出的识别方法理论算法基础上,对单元刚度线性损伤和非线性损伤形式进行了数值模拟,算例显示这种方法的有效性.

Structural damages are often accompanied by a certain nonlinear response characteristics and sometimes the nonlinear characteristics should not be ignored.So the finite element updating method may be unable to overcome the limitations of the non-linear characteristics inherent and there are also many difficulties in the local testing.A new identification method is proposed to deal with the local nonlinear damage identification problem.The nonlinear structural damage is modeled as unknown equivalent substructure and the nonlinear identification inverse problem is translated into a linear-model based equivalent force identification problem.Using the moving least squares method,a matrix is derived to extract the force time history from the measured dynamic response.The nonlinear property is identified using the input-output data of the equivalent substructure.The proposed approach has been demonstrated by some numerical examples and the results show satisfied accuracy and noise robustness.