基于环境激励的港口起重机工作模态分析

Operational modal analysis of harbor crane under ambient excitation

针对港口起重机难以施加激振力的问题,采用自然环境激励技术(NExT)对港口起重机进行了工作模态分析。在自然风的随机激励下,对某港口40 t位起重机进行了模态试验。采用响应点与参考点之间的互功率谱的幅值图代替集总传递函数的幅值图进行了模态分析。由所有测点和参考点间的互功率谱,通过拟合各响应点同参考点之间的互功率谱来识别起重机前4阶低阶模态参数(振型、频率和阻尼)。研究结果表明,利用环境激励法对港口起重机的模态参数识别是行之有效的,该方法可推广应用于其他大型特种设备的模态试验和分析。

Aiming at solving the excitation problems of a 40 t harbor crane,operational modal analysis using natural excitation technique（NExT） were investigated.Ambient excitation,such as that caused by wind,was employed to excite the crane.With the unknown input（excitation） signal,only the response signals were recorded.Taking one of the response signals as the reference,the cross power spectra of response signals were calculated and used for modal identification of the crane.The first four lower modal parameters（frequencies,damping ratios and mode shapes） were obtained.The results indicate that operational modal analysis of harbor cranes using NExT is applicable.Therefore,NExT could be recommended in modal testing and analysis of other special equipments.