基于预实验分析的箱梁模型模态测试

Modal Test of the Box-girder Model Based on Pre-test Analysis

以箱梁模型为实验对象,使用一种基于预实验分析的方法对箱梁模型进行模态识别。首先,在有限元模型模态分析结果的基础上,利用预实验分析确定合理的布点方案及最优激励点;再由预实验分析结果,采用激振器法对自由支撑的箱梁模型进行模态识别;最后,将实验模态与有限元模态进行相关性分析,以验证实验模态数据的可信性。实验结果表明,识别的四阶模态频率值与有限元分析结果在10%以内,前三阶在5%以内;与有限元模态相关性分析表明,实验测得的模态数据与有限元结果相似度高,尤其是对应前两阶模态振型相关性高达90%以上。

With the box-girder model as the experimental object,a method based on pre-test analysis is used to identify its modals.Firstly,based on the results of modal analysis of the finite element model,the reasonable distribution of the measurement points and the optimal excitation point are determined by pre-test analysis.Then,the modals of a freely supported box-girder model are identified using the vibration exciter based on the pre-test results.Finally,the correlation between the modal results from the experiments and the finite element simulation is analyzed to verify the credibility of the experimental modal data.The experimental results show that the error of the identified 4-th order modal frequency is within10 % in comparison with the finite element simulation results,and the errors of the first three order modal frequencies are all within 5 %.And the results of the correlation analysis show that the similarity between the measured modal data and the finite element results is high,especially the correlativity of the first two modals is up to 90 %.