【摘要】 传统的交叉模型交叉模态(CMCM)法由于其核心矩阵的缺秩使其在全局修正时的解不唯一,为得到唯一解必须人为假定约束。以往利用CMCM法进行损伤识别的研究中,通常将损伤前后质量保持不变作为约束求得各单元刚度的修正量,然后将刚度的下降作为判断损伤的依据。然而,结构在极端运营条件下质量的变化也是损伤的一种。为此,对传统的CMCM法进行了改进,提出了以下的改进方法:首先,由基准状态下的有限元模型和损伤后实测的结构低阶模态信息求得核心矩阵,将核心矩阵最小奇异值对应的右奇异向量作为损伤指示向量(DIV);然后,基于损伤的局部性利用聚类分析算法自动识别DIV中的异常元素,将异常元素作为损伤定位的依据;最后,由DIV估计各单元质量和刚度的损伤程度。改进后方法的优势在于:无需人为主观地添加约束即可一次性求出结构各单元质量和刚度损伤前后的变化,避免了错误或不准确的假设给损伤识别结果带来的误差。通过数值实验对该改进方法的可行性、鲁棒性以及损伤敏感性进行了研究,并通过美国洛斯阿拉莫斯国家实验室(LANL)的一个4自由度板柱结构振动台实验对改进方法的有效性做了进一步的验证。更多还原

【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,elemental mass changes under operational conditions are obviously a kind of damages. For detecting damage more effectively,the traditional CMCM method was improved,and an improved method was proposed as follows: evaluate the core matrix from the finite element model under the baseline condition and the measured modal data after damage and take the right singular vector corresponding to the least singular value of the core matrix as a damage indication vector( DIV);identify the abnormal elements in the DIV by using cluster analysis algorithm based on the assumption that damage appears locally and locate damage based on these abnormal elements; 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. The improved method’s practicability,robustness,and sensitivity to damage were analysed via a numerical simulation,and its effectiveness is further verified by virtue of the experiments on a 4 degrees of freedom test-bed structure done at the Los Alamos National Laboratory.更多还原