A local damage identification approach based on improved cross-model cross-mode method
Since the core matrix in the traditional Cross-Model Cross-Mode(CMCM) method is rank-deficient, constraints must be applied artificially for getting a unique solution in a complete model-updating situation. In previous damage identification researches based on the CMCM method, structural masses are often supposed to be unchanged for getting the updated coefficients of stiffness, and the reduction of stiffness is regarded as an indicator of damage. However, element mass changes under operational conditions are obviously a kind of damage. For detecting damage more effectively, we improved the traditional CMCM method, and proposed an improved method as follows. First, evaluate the core matrix from the finite element model under the baseline condition and the measured modal data after damage, take the right singular vector corresponding to the least singular value of the core matrix as a Damage Indication Vector(DIV); secondly, identify the abnormal elements in the DIV by cluster analysis algorithm based on the assumption that damage appears locally, locate damage based on these abnormal elements; finally, derive the extent of damage for each elemental mass and stiffness from the DIV. The advantage of the improved method is its ability to solve the mass and stiffness changes before and after damage for all elements without artificial constraints, thus the error of damage identification caused by imprecise or wrong constraints vanishes. We studied the improved method’s practicability, robustness, and sensitivity to damage by a numerical simulation, and further verified its effectiveness by a 4 degrees of freedom test-bed structure experiment done at the Los Alamos National Laboratory.
State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian,116024,China
Abstract:Since the core matrix in the traditional Cross-Model Cross-Mode(CMCM) method is rank-deficient, constraints must be applied artificially for getting a unique solution in a complete model-updating situation. In previous damage identification researches based on the CMCM method, structural masses are often supposed to be unchanged for getting the updated coefficients of stiffness, and the reduction of stiffness is regarded as an indicator of damage. However, element mass changes under operational conditions are obviously a kind of damage. For detecting damage more effectively, we improved the traditional CMCM method, and proposed an improved method as follows. First, evaluate the core matrix from the finite element model under the baseline condition and the measured modal data after damage, take the right singular vector corresponding to the least singular value of the core matrix as a Damage Indication Vector(DIV); secondly, identify the abnormal elements in the DIV by cluster analysis algorithm based on the assumption that damage appears locally, locate damage based on these abnormal elements; finally, derive the extent of damage for each elemental mass and stiffness from the DIV. The advantage of the improved method is its ability to solve the mass and stiffness changes before and after damage for all elements without artificial constraints, thus the error of damage identification caused by imprecise or wrong constraints vanishes. We studied the improved method’s practicability, robustness, and sensitivity to damage by a numerical simulation, and further verified its effectiveness by a 4 degrees of freedom test-bed structure experiment done at the Los Alamos National Laboratory.
占超, 李东升, 任亮, 李宏男. 基于改进交叉模型交叉模态法的局部损伤识别方法[J]. 振动与冲击, 2015, 34(7): 127-133.
ZHAN Chao, LI Dong-sheng, REN Liang, LI Hong-nan. A local damage identification approach based on improved cross-model cross-mode method. JOURNAL OF VIBRATION AND SHOCK, 2015, 34(7): 127-133.
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