Nonlinear thermal-vibration characteristics analysis of aerostatic spindle considering coupling effect

Neglecting the thermal-vibration coupling effect of the aerostatic spindle at high speeds reduces the analytical accuracy of the thermal and dynamic characteristic models. Based on the thermal-vibration interaction mechanism, this paper proposes an iterative calculation method that considers the coupling relationship between transient temperature rise and dynamic vibration response, which is used to enhance the simulation accuracy. The multi-degree-of-freedom dynamic model of an aerostatic spindle under dynamic air film force and mass eccentricity excitation considering the influence of thermal effects is established to predict the nonlinear dynamics behavior. The thermal network model of the spindle global system under the influence of vibration response is developed to simulate the temperature rise variation by determining the type of thermal resistance. The dynamic air film thickness is derived to obtain the air film heat generation and dynamic thermal resistance considering gas leakage, and the heat generation loss of the built-in motor is calculated based on the equivalent circuit diagram. The combined effect of temperature on air density and viscosity is analyzed to more accurately simulate the heat-generating state. Experiments under different condition parameters are set to verify the accuracy and applicability of the coupling iterative model. The interaction between the temperature field and the dynamic model is analyzed using the thermal-vibration coupling closed-loop idea. This work investigates the transient temperature rise variations under the influence of nonlinear vibration and hence the altered dynamical behavior. The thermal-vibration coupling can excite rich amplitude-frequency characteristics and response trajectory changes. The coupling mechanism is analyzed through the parametric analysis to have a non-negligible important influence on the theoretical prediction of thermal and dynamic properties.