吊挂式模态试验系统动力学建模和分析

根据吊挂式模态试验系统的工作原理，通过合理简化等效，建立了吊挂式模态试验系统的力学基本模型。依据瑞利理论，求解出其在水平和竖直2个方向测试基频的解析计算公式，揭示了测试基频和真实基频的等量关系式，分析了2个方向上基频测试误差的产生机理、影响因素和变化趋势。通过开展标准杆模态试验以及有限元仿真分析，验证了吊挂式模态试验系统力学等效模型合理、正确和有效。结果表明，吊挂式模态试验系统竖直方向的基频测试值偏低，水平方向的基频测试值偏高，需对测试结果进行误差修正，方能得到被测对象较准确的基频值。

Dynamic modeling and analysis of hanging modal test system

According to the working principles of the hanging modal test system, a basic mechanical model for the system is established via reasonable simplification and equivalence. Based on the Rayleigh theory, calculation formulas for correction of the test frequency in both horizontal and vertical directions are given, and the relationship between the test base frequency and true base frequency is revealed. The mechanism, influencing factors and trends of the test base frequency errors in both directions are analyzed. Through the modal test of the standard bar and finite element simulation analysis, the mechanical equivalent model for the hanging modal test system is verified to be reasonable, correct and effective. The results show that the test base frequency of the hanging modal test system in the vertical direction is low and the test base frequency in the horizontal direction is high, and thus the test result errors must be corrected to obtain the accurate base frequency of the measured object.