基于结构水下冲击响应识别结构模态参数

在冲击载荷作用下，基于水下结构的动力学方程，结合Hilbert-Huang变换(HHT)推导出冲击作用下结构响应与模态参数的关系，并识别了水下结构的频率和模态阻尼比.HHT方法适合处理冲击等非平稳响应，设计的带通滤波器能自动选取截止频率，可以准确地得到各阶模态响应.且只需要结构适当一点的冲击响应，就可得到结构的固有频率和模态阻尼比.最后，以一水下矩形钢板为例，经数值计算在典型的爆炸冲击载荷作用下结构的振动响应，通过本方法得到了结构的固有频率和模态阻尼比，再以水下圆柱壳结构为例，同样得到了结构的固有频率和模态阻尼比，验证了本方法在冲击作用下识别水下结构模态参数的可行性.
Based on the dynamic equations of underwater structures, the modal parameters under shock were identified with Hilbert-Huang Transform (HHT).The method combines the advantages of HHT for nonlinear and non-stationary signal, and the band-pass filters designed can select the cut-off frequency automatically, which can accurately obtain each modal response.Then, it can identify the structural natural frequencies and dampings with only one measured data in proper place.Finally, the accuracy and the validity of the method were verified on the basis of numerical simulation experiments, which identify the structural natural frequencies and dampings with one node response.It offers a practical method for the structural identification of modal parameters of underwater shock environment.