子结构界面连接参数识别的波传播法

IDENTIFICATION OF JOINT PARAMETERS BASED ON WAVE PROPAGATION

提出一种基于波传播法识别子结构连接界面刚度和阻尼的新方法。以子结构在平面内的弯曲振动为例,将单元的状态变量与波模式联系起来。通过单元波幅系数的识别,得到连接界面的位移和力向量,再由结点上位移连续及力平衡条件,求得连接界面各个自由度上的动刚度。在识别过程中,将动刚度分离为实部和虚部,以便于连接刚度和阻尼的独立识别。为了提高识别精度,选择一定的频率范围,在每一频率下求得连接界面的刚度和阻尼,最后求出统计平均值作为界面的连接参数。数值仿真算例表明本方法具有良好的识别精度和数值稳定性,是一种极有潜力的参数辨识方法。

A new approach to identify the stiffness and damping parameters is presented for a joint of beam- or rod-combination structures. The basic concept consists of solving an inverse problem where the measured response of the system tested is combined with an incomplete analytical model in order to identify the joint parameters in the frequency domain. The original technique based on wave propagation provides a small-size analytical model. In order to explain the identification method, a two-beam-member structure is illustrated. For flexural vibration of beam structures in two dimensions, when the wave mode amplitudes are identified, the general displacement and force of the joint are known. So the dynamic stiffness can be derived. During the identification procedure, the dynamic stiffness is separated into real and imaginary parts in order to identify the stiffness and damping parameters independently. The frequency response functions for each discrete frequency are employed so that the joint properties could be estimated for each frequency and averaged using statistical methods. The validity and feasibility of the approach are shown using a numerical example.