Hysteresis dynamic modeling of 4-SPS parallel all-metallic isolator with spherical joints considering nonlinear micro-collision and interfacial friction

This work aims to identify ways to model a high-accuracy hysteresis dynamic model for an innovative 4-SPS parallel all-metallic isolator. Firstly, a three-dimensional contact model of spherical joints under different conditions (stretching and compression) is proposed, referred to as the integrated model of nonlinear micro-collision and interfacial friction (INCF model). Simultaneously, in conjunction with the nonlinear elastic recovery force, nonlinear damping force, and nonlinear hysteresis damping force, the high-accuracy hysteresis dynamic model of the isolator is constructed. To validate the accuracy, dynamic experiments are conducted on the isolator at distinct frequencies (6–9 Hz) and amplitudes (0.6–0.9 mm). The results indicate that the hysteresis dynamic model constructed based on the INCF model exhibits a remarkably high level of precision compared to the classic model (R²=0.998). This increased accuracy is attributed to the consideration of influencing factors of the INCF model, such as micro-collisions between spherical joints and interfacial friction during the operation of the isolator. These variables are determined by the material properties and geometric dimensions of the spherical joint and can be adjusted in real time based on the isolator deformations to enhance the model's accuracy. The method of parameter identification applied to overall structure resolves challenge of measuring the internal deformation of spherical joints. Importantly, the INCF model is not limited to the isolators proposed in this work but can also be applied to similar isolators with Stewart structure-type connections that employ spherical joints. These research findings provide a robust theoretical support for the design and performance optimization of the isolator, with the potential to positively impact related engineering applications.