The active controlled hydrostatic bearing is becoming more and more popular because of its accuracy, safety, as well as low vibration and noise. In this paper, we present a design approach for a hydrostatic thrust bearing system, where the analytical nonlinear state space equation of the system is established first, and then three kinds of control inputs are investigated and compared to each other. It is found that, by selecting the supply pressure as the control input, we could obtain an affine nonlinear system, which could be linearized by the feedback linearization method, and its robustness could be enhanced by the sliding mode control method. The tracking control law could be easily obtained with the linearized system. The simulation verifies the effectiveness of the nonlinear control law. The proposed nonlinear control model might have a positive effect on the improvement of the machining accuracy, safety, and vibration absorption.
Both flat and island type membranes are used in single-action membrane restrictors. But the difference between the single-action flat membrane restrictor (SFMR) and the single-action island type membrane restrictor (SITMR) has rarely been reported in the literature. In this study, we first compared the static and dynamic characteristics of SFMR and SITMR, and found that there is a little difference between them when the difference between supply pressure ps and outlet pressure pr is not large. Then, we investigated the dynamic characteristics of hydrostatic thrust bearings using both SFMR and SITMR compensation, and found SITMR having a better dynamic bearing performance. The reason for this phenomenon is that the mass of the membrane in SITMR is smaller than that of the membrane in SFMR. When the difference between supply pressure ps and outlet pressure pr becomes large, SFMR reduces the static flow rate of the lubricant of bearing systems more significantly than SITMR.
This paper presents a novel method to determine the flow rate and fluid resistance of membrane-type restrictors. The coupled fluid pressure and membrane deformation is solved utilizing a fluid and structure interaction algorithm. The arbitrary boundary condition of a membrane is properly handled by adding the displacement springs and torsion springs to the boundary nodes of the membrane, and the finite element method is used to calculate the membrane deformation. Three different methods are studied using several case studies: the arbitrary boundary method, the large deformation method, and the traditional method. The results are compared with the experimental data available in the literature. It has been found that among all three methods, the arbitrary boundary method offers the best results. The membrane deformations show a nonlinear relationship with different supply pressures. The results reveal the boundary condition of the membrane is not a fixed boundary or a simply supported boundary; it is an arbitrary boundary condition, which varies with respect to the supply pressure. By taking the statistical model into consideration in the design process, the proposed arbitrary boundary condition method offers the potential to accurately calculate the flow rate and improve the reliability of the designs for membrane-type restrictors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.