噪声与振动控制2017，Vol.37Issue(6)：17-22,6.DOI:10.3969/j.issn.1006-1355.2017.06.004
结构应变模态参数辨识的最小二乘复频域方法
Least Square Complex Frequency-domain Method for Structural Strain Modal Parameter Identification
摘要
Abstract
Due to its sensitivity to structural state, the strain mode has more advantages than the displacement mode in online structural health monitoring and damage identification. Since the strain mode and displacement mode are merely the different expressions of the same physical state and they are similar in mathematical expression, the relationship between strain and displacement can be applied to the least square complex frequency-domain method (LSCF) to analyze structural stress and strain. In this study, the frequency domain identification method of structural dynamics parameters is established based on strain measurement data. First of all, a parameterized common denominator model with strain as its variable is established. On this basis, the nonlinear least square problem is linearized and the error of the weighted least square linear equation is obtained. Then, the equation is solved by using the algorithm based on the reduction of regular equations. In this way the amount of computation is reduced and parameter redundancy is avoided by imposing the restriction on the modal parameters. Afterwards, an experimental system of a free beam structure is designed and the structural dynamic strain is measured using Fiber Bragg Grating strain sensors. Finally, the frequency and damping ratio are identified by means of LSCF based on the measured strain data. The acceleration results of the identification agree well with those of the traditional identification method based on the measurement data of acceleration. Besides, the strain mode shapes obtained by this identification method are also consistent with the simulation results. Therefore, numerical simulation and the experiment show that the proposed method based on LSCF can accurately identify the strain modes of structures.关键词
振动与波/应变模态/模态参数辨识/最小二乘复频域法/模态实验Key words
vibration and wave/strain mode/modal parameters identification/LSCF/modal experiment分类
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周思达,曹博远,周小陈..结构应变模态参数辨识的最小二乘复频域方法[J].噪声与振动控制,2017,37(6):17-22,6.基金项目
国家自然科学基金资助项目(11402022) （11402022）
