Effects of different boundary conditions on free mode test

Finite element simulation analysis is widely used in the study of dynamics in the field of precision machinery, with the completeness of the finite element method and the update of simulation software. To improve the accuracy of finite element simulation analysis, the modal test results are typically used to modify or optimize the model of finite element simulation. Therefore, the accuracy of the experimental results is crucial. Different support conditions are one of the important factors that influence the modal test results. This paper focuses on the metal sheet as the research object and adopts the multi-point excitation and multi-point response hammering impact method. Modal test results are obtained for two different boundary conditions (support conditions), namely, the sponge block and spring suspension. Based on the finite element simulation analysis results as the accurate solution, the differences in modal test results between two support methods were analyzed. It was found that the cotton block support method can obtain the resonant frequency of the structure more accurately. Thus, it provides a basis for selecting the support method for free modal test.