An efficient three-dimensional foil structure model for bump-type gas foil bearings considering friction
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ISSN 2223-7690 CN 10-1237/TH
RESEARCH ARTICLE
An efficient three-dimensional foil structure model for bump-type gas foil bearings considering friction Yongpeng GU, Xudong LAN*, Gexue REN, Ming ZHOU School of Aerospace Engineering, Tsinghua University, Beijing 100084, China Received: 25 December 2019 / Revised: 01 June 2020 / Accepted: 07 July 2020
© The author(s) 2020. Abstract: This paper presents an efficient three‐dimensional (3D) structural model for bump‐type gas foil bearings (GFBs) developed by considering friction. The foil structures are modeled with a 3D shell finite element model. Using the bump foil mechanical characteristics, the Guyan reduction and component mode synthesis methods are adopted to improve computational efficiency while guaranteeing accurate static responses. A contact model that includes friction and separation behaviors is presented to model the interactions of the bump foil with the top foil and bearing sleeve. The proposed structural model was validated with published analytical and experimental results. The coupled elastohydrodynamics model of GFBs was established by integration of the proposed structural model with data on hydrodynamic films, and it was validated by comparisons with existing experimental results. The performance of a bearing with an angular misalignment was studied numerically, revealing that the reaction torques of the misaligned bearing predicted by GFB models with 2D and 3D foil structure models are quite different. The 3D foil structure model should be used to study GFB misalignment. Keywords: gas foil bearing; bump foil model; frictional contact; elastohydrodynamics; bearing misalignment
1 Introduction Gas foil bearings (GFBs) have been applied to high speed and high performance rotating machinery in many industrial fields because of their low frictional losses and oil‐free operation [1, 2]. Designing hydrodynamic bearings requires the analysis of important characteristics such as the hydrodynamic pressure distribution [3] and the minimum film thickness [4]. The behavior of GFBs depends on both the gas film and compliant foil structure. The foil structure usually consists of a smooth top foil that acts as a bearing surface and a support structure that provides flexibility and frictional energy dissipation. Among the various types of GFBs, the bump‐type foil bearing is most
widely used, and it is illustrated in Fig. 1. The bump foil structure is one of the most critical aspects of GFB designs, as it can greatly improve the bearing performance [5]. However, the complex geometry and nonlinear friction behavior lead to challenges in analyzing its mechanical characteristics. Walowit and Anno [6] first investigated the mechanics of an individual bump without considering the friction between the top foil and the bump foi
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