基于不完备测试阵型的结构损伤识别与误差分析

Structure Damage Detection and Error Analysis Based on Incomplete Mode Shapes

目前大多数结构损伤识别方法假定有限元模型自由度与实测自由度相同,而实测的数据往往非常有限,为了使测试的不完备模态参数能够用于损伤识别,一般需要对不完备模态进行扩阶处理,该文研究了一种将未测自由度的模态阵型用原始结构的阵型与阵型的改变量之和表示的扩阶方法,通过确定阵型的改变量获得受损结构的完备模态阵型,同时对扩阶过程中的误差进行定量分析,提出了模态贡献因子指标,依据模态贡献因子对不完备信息进行扩充并进行损伤识别。数值结果表明,利用模态贡献因子进行的扩阶识别方法能在保证识别损伤精度的基础上一定程度的提高计算效率。

At present,most methods of damage detection assume the FEM modal degrees of freedom as same as the actual measured degrees of freedom,but the actual data measured are very limited.In order to use the measured incomplete mode shapes in damage detecting,the modal expansion technology usually be used.In this paper unmeasured modal shapes is represented by the sum of undamaged structural modal shapes and shapes changes.The complete modal shapes can be obtained by determining the shapes changes,meanwhile the residual of the modal expansion is analysed,modal contribution factor is put forward,which can be used in incomplete mode shapes expansion and damage detection.Numerical results shows the approach which using modal contribution factor expansion the incomplete mode shapes and for damage detection can increase calculation efficiency.