# Design of Flexible Bearing with Larger Inner Diameter
## 1 Introduction
[18] analyzed the distribution law of deformation and stress of FB under different structural parameters by FEA method for static analysis. [PERSON] et al. [19] utilized ANSYS/LS-DYNA and LS-PrePost to carry out dynamic analysis of the FB and obtained the stress distribution laws of each part. [PERSON] et al. [20] investigated the vibration frequency of elliptically deformed FB using experimental measurement data and the finite element method. [PERSON] et al. [21] determined the location of the maximum equivalent force of the FB based on the triple bending moment equations and FEA. [PERSON] et al. [22] proposed a method to solve the elastic deformation problem of thin-walled shell structures with complex geometric shape in ally nonlinear shell theory and compared it with ANSYS calculation results, drew the conclusion that the contact model in ANSYS is more in line with reality. [PERSON] et al. [23] used FEA simulation to analyze the deformation characteristics of FB after assembly. Based on the analysis of FB by ABAQUS, [PERSON] et al. [24] found that the fatigue damage of the inner ring is mainly caused by contact stress, the contact fatigue damage and bending fatigue damage of the outer ring occur at the same time, and the fatigue failure of the outer ring occurs before that of the inner ring. To simulate the actual working condition of FB and reduce the test cost, [PERSON] et al. [25] developed a bearing testing machine that can simulate the motion state of FB under different attitudes of robotic arm. [PERSON] et al. [26] developed a fatigue life test method to simulate the actual operating condition of FB. [PERSON] et al. [27] analyzed the effect of parameters of aspect ratio and wall thickness etc. on the contact mechanical features of FS under the action of a forced WG. The FEA method is used to analyze the stress distribution and deformation patterns of convention flexible bearing (CFB) under different loads [28; 29]. [PERSON] et al. [30] analyzes the materials microstructure and mechanical properties of FS and FB in domestic and Japanese HD. [PERSON] et al. [31] designed a device for accelerated life test of HD set. The method and program of selection, maintenance and fault diagnosis are provided for rolling bearing [32; 33]. [PERSON] et al. [34] proposed a fault diagnosis method for HD set using multi-scale convolutional neural networks (MSCNN). The industry has been committed to developing the HD reducers with larger hollow inner diameter [35]. [PERSON] et al. [36] presented the novel forced wave generator (NFWG) for the HD with a large hollow bore. In precision HD transmission applications such as miniature robot joints, the HD and the FB are required to have a smaller mass, lower moment of inertia, and larger inner diameter. The inner diameter of the FB is one of the important factors limiting further expansion of the hollow inner diameter of the HD, and there is no relevant design materials for increasing the inner diameter of the FB in the references retrieved so far. Therefore, it is necessary to carry out the modification design for the structural parameters of the CFB in order to increase the inner diameter while the outer diameter remains unchanged. Based on the life theory of CRB [37], by using the first method of L-P theory, this paper deduces the new formula suitable for calculating the FB lifespan and proposes a new method for the design of structural parameters of FB, after studying the laws of structural parameters affecting on the fatigue life of the FB by taking the working characteristics of the FB for HD into consideration. On this basis, the novel design method for improved flexible bearing (IFB) with a larger inner diameter compared to CFB is proposed, and an improved design instance are made for a type of CFB. Finally, this paper conducts a comparative analysis of IFB and CFB through FEM.