Dynamic response influenced by joint contact uncertainties in complex machinery

Abstract

The contact characteristics of joints in complex machinery often exhibit uncertainty, directly affecting dynamic performance and stability. The principal scientific challenge is to establish a dynamic model for complex systems that accounts for the uncertain contact characteristics of joints. This study focuses on the uncertain contact mechanisms of joints distributed across complex systems, providing a new and efficient method for system dynamic analysis under joint uncertainty. The transfer matrix method for multibody systems and fractal theory are utilized to construct a dynamic model that integrates the three-dimensional contact micromechanics of joints with the macroscopic structural features of rigid-flexible coupled multibody systems. An improved interval arithmetic is developed to characterize uncertain contact behaviors. It incorporates the overall transfer principle and Taylor inclusion function to decouple interval operations from complicated computations, thereby effectively controlling interval expansion and enhancing computational accuracy. The proposed method is applied to an ultra-precision three-axis single-point diamond machine tool and validated experimentally. Through orthogonal analysis, the impacts of different joints on the dynamic response of the ultra-precision machine tool are revealed, identifying key joints and critical contact factors. This approach significantly contributes to the forward design and dynamic optimization of complex machinery.