In order to effectively improve the dynamic characteristics of the fixed metal joint interface, it is important to establish a correct equivalent model of the metal joint interface. In this paper, three equivalent methods for simulating the metal joint interface are analyzed, including the virtual material method, spring damping method, finite element method, and verification by modal experiment. First, according to the contact mechanics model of the constructed metal joint interface, the physical properties of the three-dimensional models of the fixed joint interface are assigned in the ANSYS software. Then, three methods are used for the modal analysis and compared with a modal experiment. The results show that the modal shapes of the three theoretical methods are consistent with those of the experimental modes. The first five natural frequencies obtained by the virtual material method are closest to the experimental natural frequencies, and the errors are within 10%. The errors of the other two methods are between 9% and 39%. Therefore, the virtual material method is a better equivalent method of the metal joint interface.

The mechanical joint surface plays an important role in transmitting motion, load and energy during the normal operation of the mechanical system. Effective mechanical joint equivalent models are established to solve the practical problem of the dynamic model engineering. Equivalent models of joint surface in this study include spring damping method, virtual material method and Bond connection method. Firstly, the model is established by CATIA. Secondly, the physical properties of the model are assigned by ANSYS or Abaqus finite element simulation software. Then the modal analysis of the model carries out. By comparing the mode shapes and natural frequencies of the three methods, it is concluded that the mode shapes of the three methods are basically the same. Therefore, all three methods are reliable joint surface equivalent models. However, the natural frequency obtained by the virtual material method is significantly lower than the natural frequencies obtained by the other two methods. It is concluded by analysis that the natural frequency error obtained by the virtual material method is small, and the spring damping method and the finite element method have large errors.