试验模态分析最佳测试点选取方法的优化

作为有限元模型修正的重要依据，试验模态分析的结果受多方面因素的影响，其中很重要的一方面就是测试点的选取.基于目前试验模态分析中最常用的两种测试点选择方法——有效独立法（EI，Effective Independent）和模态动能法（MKE，Modal Kinetic Energy），提出了一种新的测试点优化选择方法——有效独立-模态动能变异系数法（EI-CVMKE，Effective Independent-Coefficient Variance of Modal Kinetic Energy）.并提出了一种新的评估测试点选择方法优劣的准则——模态动能变异系数准则（CVMKE）.运用模态置信准则（MAC，Modal Assurance Criterion）、CVMKE和奇异值分解比（SVD ration，Singular Value Decomposition ratio）评价并比较了EI，MKE和EI-CVMKE的测试点优化结果.以印刷电路板作为算例，并通过实物模态试验验证，结果表明EI-CVMKE选取的测试点在考虑了截断模态线性独立的同时又具有较高的模态动能，有较强的抗噪声性能，在3种方法中最佳.

Method optimization of optimum measurement point selection in experiential modal analysis

As an important basis of the validation of the finite element model, the result of experimental modal analysis is influenced by various aspects, one significant aspect is the measurement point selection. A new optimal measurement point selection method, namely effective independent-coefficient variance of modal kinetic energy (EI-CVMKE) method was proposed based on the effective independent (EI) method and the modal kinetic energy (MKE) method. Besides, a new criterion called the coefficient variance of modal kinetic energy (CVMKE) was presented. The obtained optimal measurement points using the new method were compared with those gained by EI method and MKE method. The advantage and disadvantage of those three methods were demonstrated by three evaluation criteria which are CVMKE, modal assurance criterion (MAC) and singular value decomposition ratio (SVD ratio). A computational simulation and a modal test on an aluminum alloy plate were carried out to demonstrate the feasibility of the optimal measurement point selection method. The result shows that EI-CVMKE method can not only make the truncated mode shapes as linearly as possible but also enable the measured MKE to maintain the maximum value. The new method is most feasible in the three methods.