Interfacial micromechanics modeling for bolted joints in ultra-precision machine tools

Bolted joints are widely adopted in various mechanical structures. However, the uncertainty and complexity of the contact surfaces affect accurate modeling. Herein, an interfacial micromechanics model is proposed to characterize the contact behaviors of bolted joints in an ultra-precision machine tool (UMT). The bolted joint is modeled as a virtual material layer with transversely isotropic behaviors, whose constitutive relation is identified by fractal theory. The proposed model accurately formulates the multi-scale contact characteristics and allows convenient integration with the structural dynamic modeling of UMT. Dynamic analysis of the simulation results and the experimental measurements in the time and frequency domains was conducted to identify the most sensitive factor affecting the tool tip vibration. On this basis, the structural optimization for the UMT was further implemented, which effectively reduced vibration by 15.5 %. The dynamic predictions were validated by modal and vibration response tests.