Equivalent Modeling Method for Screw Joints Based on Stiffness Calculation

Accurate assessment of the mechanical properties of an assembly with screw joints has to rely on the equivalent modeling of the screw joint and accurate kinetic properties analysis. In this paper, an equivalent modeling method for screw joints based on stiffness calculation is proposed. With the solid model of the screw-coupled member, the equivalent virtual material parameters that can characterize the mechanical properties of the joint surface of the coupled member are obtained by calculating the joint surface stiffness, and then the accurate parametric modeling of the screw joints is realized. In addition, the vibration modal test platform for screw joints is built. By comparing the frequency response function obtained from the experiment with that obtained from the equivalent model simulation, it is found that the errors of the 1st-order and 2nd-order bending natural frequencies of the cantilever beam are 3.96% and 5.5%, respectively, and the simulation analysis results are of high accuracy. Furthermore, by comparing the first 6th-order of natural frequencies of the cantilever beam, the maximum frequency deviation between the simulation analysis results and the test results is ≤ 7%, and the average frequency deviation is 4.67%, which can better reflect the mechanical properties of the screw joint.