Influence of microscale effect on the radial rotation error of aerostatic spindle

This paper presents the influence of the microscale effect on the radial rotation error of aerostatic spindle, which is determined by the corresponding stiffness, damping, and unbalance mass. A microscale gas film flow model is used to simulate the static performance of the aerostatic bearing by introducing the microscale effect factor Q in this paper. Firstly, the radial stiffness and damping coefficients of aerostatic bearing were calculated considering microscale effect factor Q, therefore, the position of the rotating shaft in radial plane was deduced, and the corresponding rotation error was obtained. Finally, the simulation results of the stiffness and radial rotation error were verified by the experiment on the shaft test table, and the motion orbit was measured by a displace sensor with a high precision standard ball. The experimental results indicated that the simulated result considering the microscale effect factor Q was more consistent with the actual experimental value, which provided a reference for the design and optimization of the aerostatic spindle.

Analysis of aerostatic spindle radial vibration error based on microscale nonlinear dynamic characteristics

This paper presents a method of predicting the radial rotary error of an aerostatic spindle based on the microscale-effect to investigate the influence of gas film fluctuation on the rotation accuracy of the aerostatic spindle. First, the gas bearing of the spindle is simplified as a spring-damping system with two degrees of freedom perpendicular to each other. Additionally, the aerostatic spindle bearing-rotor system is established by considering the forced vibration and deflection vibration of the rotor. Subsequently, the microscale-effect is introduced into the dynamic model of the gas film flow, and the dynamic Reynolds equation of the gas film is established in the microscale. Moreover, the nonlinear dynamic stiffness and dynamic damping coefficient are obtained by the perturbation method. The nonlinear dynamic parameters in the microscale are introduced into the dynamic model of the bearing-rotor system and all the vibration errors are obtained. By comparison with the conventional case, it is found that the spindle gyration error increased and that the response delay occurred when the microscale-effect is considered. Moreover, the influence of the supply pressure and speed on the vibration of the spindle is also analyzed. An experiment measuring the spindle rotation error is carried out. The experimental results reveal that the prediction method of the nonlinear spindle rotation error in the microscale is more accurate, and that the errors are 5.8% and 9.6%.

The Study of Microscale Effect Assessment in Micro Forming

Metal micro forming is microscale effect in the process of classification and evaluation, for the correct understanding of micro forming and conventional forming difference, it is guiding significance in the course of micro forming technology similar to conventional forming which is applied to the data and experience. The microscale effect is beneficial to accurate grasp of all kinds of microscale effect in the forming reasonable classification and evaluation.Change law of microscale affects the nature of knowledge for the right team which provides effective quantitative data, when determine the major hours of rights, it also can provide the guiding idea for material selection and process optimization.The reasonable classification and evaluation of microscale effect is the experience that conventional forming calculation provides a reality way. In all kinds of process load calculation, as long as the material intrinsic microscale is joined, microscale can be introduced in corresponding few and the process conditions.

Microscale Effect of Elastic Beam of the Micro-Machined Gyroscope

A detailed analysis of the concept of strain energy density and strain gradient on the material microscale effect in a micro-machined gyroscope is carried out. By analysis, the material microscale effect mainly influences its elastic modulus. The analytical expression of the valid elastic modulus on the micro elastic beam structure of the micro-machined gyroscope is deduced. When considering the valid elastic modulus and not, respectively compare the natural frequency of the elastic beam with the actual measurement results. The error of former is far less than the latter. By the theoretical derivation and experiment test, the influence of the material microscale effect on the micro-machined gyroscope is analyzed.

Experimental Study of the Real Gas Flow in Microtubes

The flow characteristics of nitrogen in microtubes with diameters of 14.9, 10.1, 5.03 and 2.05μm are investigated experimentally under high pressure conditions. The results show that the high pressure flow characteristics of nitrogen in microtube with the diameter of 14.9μm are in accordance with the classical fluid mechanics theory. However, with the decrease of the inner diameter of microtube, gas flow shows an apparent microscale effect and the results depart from the theoretical predictions of the conventional theory, moreover the smaller the diameter, the stronger the microscale effect. Besides, the high pressure microscale effect can not be characterized by the Knudsen number, which is proposed for studying rarefaction effect at low-pressure. Because of the existence of high-pressure microscale effect, it is inappropriate to study the real gas seepage characteristic in reservoir through the flow experiment at low pressure.