基于振动响应时频分析的桅杆损伤识别方法

桅杆的模态参数和刚度对纤绳平衡张力、激励和环境条件比较敏感,导致目前比较有效的结构损伤识别方法和指标难以直接应用。为此,探索了基于测点振动响应时频分析而不依赖模态信息的桅杆结构损伤识别方法,提出利用结构测点振动响应的Wigner-Ville分布交叉项统计量WCS(WVD Cross-term Statistic),通过比较损伤前后统计量的相对变化量来进行损伤识别。算例分析结果表明,利用测点振动响应的损伤识别指标WCS相对变化量,除能识别杆身单个不同程度的损伤位置以及多个损伤外,还能分辩出纤绳的损伤特征。通过增大激励的幅值和增加测点的数量,可以提高识别的精度和指标的灵敏度;基于测点位移响应与基于测点加速度响应的损伤识别指标相比,具有更好的损伤识别效果。

Damage identification method for a guyed mast based on WVD cross-term distribution

The modal parameters and stiffness of a guyed mast are sensitive to the initial pre-tension, excitation and environment, this leads to that many effective methods and indexes are difficult to use.A damage identification method that took advantages of the time-frequency analysis of structure response and did not rely on modal information was explored, the relative alteration of Wigner-Ville distribution cross-term statistic (WCS)based on vibratory response was developed for damage identification of a guyed mast.Analysis results of a numerical example demonstrated that, not only can the relative alteration of WCS at sensors distinguish single damage at different levels and several damages of the mast, but also it can identify guy's damage; the susceptivity of the index to damage can be enhanced by increasing excitation and the number of sensors; the damage identification with the index computed based on displacement response is better than that with the index computed based on acceleration response.