基于环境激励下的工作应变模态频域识别方法

MODAL PARAMETERS IDENTIFICATION OF OPERATIONAL STRAIN MODES UNDER AMBIENT EXCITATION WITH FREQUENCY DOMAIN METHOD

针对应变型指标比位移型指标对损伤具有更好的识别能力,以及环境激励的优越性,提出工作应变模态。本文从应变频响函数理论出发,对工作应变模态频域识别方法进行推导。利用应变幅频响应曲线峰值判断系统固有频率。当激励为白噪声或宽带随机谱时,根据各测点应变响应幅值谱与参考点应变幅值谱的比值,得到系统的工作应变模态幅值。并可利用互谱实部符号判断工作应变模态的相位。

Based on the theory of strain mode and frequency response function, the modal parameters identification of operational strain modes is deduced with the frequency domain method. According to the peaks on frequency-amplitude characteristic curves, the natural frequencies are identified. Then, according to the ratio of strain response magnitude at the measurement point to that at the reference point, the amplitudes of operational strain mode shapes (OSMS) under the excitation of white noise or wide-band random spectrum are obtained. The phases of OSMS are defined by the sign of cross-spectral real part.