基于工作应变模态损伤识别方法的试验研究

Experimental study on damage identification based on operational strain modal shape

介绍了笔者近几年提出的工作应变模态频域识别方法、基于损伤应变模态差分原理的损伤位置直接指标法、基于局域应变模态面积的损伤程度直接指标法。为了验证所提方法,开展了悬臂梁多损伤物理模型试验及数值仿真计算分析,结果表明,利用该方法识别出的工作应变模态与锤击激励下的应变模态形状相似。初步验证并完善了损伤位置、损伤程度直接指标法。位于损伤处的损伤位置直接指标值远大于非损伤处指标值,识别出的损伤位置与实际损伤位置一致;同一损伤量下的损伤程度指标值变化不大,与损伤位置、模态阶数、是否归一化无关;对于多损伤结构,只要损伤间距大于影响区范围,损伤位置、损伤程度即可按单损伤方法确定。

Operational strain modal shape（OSMS） as well as direct index methods for damage location detection（named as ISMSD） and damage degree detection（named as ILSMSA）,which were advanced in recent years by authors,were introduced.The results of model test and numerical simulation were applied to verify the methods.The results show that the operational strain modal shape identified in the method is similar to the strain modal shape under impact excitation.According to the results,direct index methods of damage location detection and damage degree detection were also improved.The direct index value of ISMSD at damage location is greater than the index value in other area,and so the damage location can be detected in accord with actual situation.Furthermore,when damage degree is equal,the variation of ILSMSA is slight.The value of ILSMSA is independent of damage location,order number of strain modal shape and normalization.If the space between damages is greater than the damage affected region,the methods can be applied to the multi-damage detection of structure.