基于单元应变能变化率的结构损伤识别方法

Structural damage identification method based on elemental strain energy change ratio

针对梁类结构,根据单元损伤前后的模态应变能变化率,推导了新的损伤位置识别指标,并利用结构在损伤前后模态应变能变化与频率变化的关系提出了损伤程度评估指标.悬臂梁的数值模拟分析结果显示:损伤位置识别指标在损伤单元对应的结点处呈现显著的正号峰值,能够清楚地指示损伤位置;损伤程度识别指标对于单一损伤工况的损伤程度估算结果较接近于实际损伤程度,但对于多点损伤工况的损伤程度估计值偏小.所提出的损伤指标仅根据结构损伤前后的低阶模态频率和模态曲率即能达到较好的损伤识别效果,可应用于实际结构中.

For beam-type structures, a new index for identifying the damage location is developed and proposed based on the elemental strain energy change ratio before and after the damage of element, and the index for evaluating the damage extent is presented according to the relation between the modal strain energy change and the frequency change before and after the structural damage. The numerical simulation analysis results of a cantilever beam show that the damage location index displays a significant positive peak on the nodes corresponding to the damaged element, indicating the damage position clearly. The damage extent index offers estimation results close to the true damage extent for single damage cases but for multiple damage cases the value of estimation is somewhat smaller. The proposed damage indexes are able to produce satisfying damage identification effects only according to the lower-order modal frequencies and curvatures of the structure before and after damage, which can be applied to practical structures.