基于频响函数虚部的板结构损伤检测方法研究

仅利用损伤后的板结构频率响应函数虚部，建立二维板结构的损伤定位指标, 避免了由于建立未损伤有限元计算模型所引起的损伤检测误差。提出了一种基于测量点平均互相干性的加权格式，以减小测量系统误差对检测效果的影响。数值算例详细对比了模态振型指标、均匀载荷面指标和频率响应函数虚部指标对板结构损伤定位效果。最后，通过一多损伤薄板结构的损伤检测实验，验证了该指标具有良好的损伤敏感性和抗噪声能力。对于实际工程中的薄板结构损伤定位研究具有一定的意义。

Damage detection for a plate based on imaginary part of frequency response function

A scheme for damage detection of a plate based on vibration data only from its damaged status was presented here.The error caused with its undamaged finite element analytical model could be avoided using the gapped smoothing method.The imaginary part of its frequency response function was extended to a two-dimensional plate structure as a damage index.To eliminate the influence of measurement system errors,a weighted method for repeated measurements on a practical structure based on point-averaged coherence was proposed.The effectiveness of three indices including(modal shapes,uniform load surface and imaginary part of frequency response function) were analyzed in condition of different noise levels,and were compared in detail.Finally,test for a multi-damaged plate was performed to assess the sensitivity of the proposed index to damage and antinoise ability.It was shown that the proposed index is meaningful for detecting multi-damage in a plate.