# Design of Flexible Bearing with Larger Inner Diameter
## 5 Discussion  
The load distribution of FB is not the same as that of CRB. The FB is subjected to two-sided forces at the major axis of cam assembly, and the number of stress cycles is twice as much as that of CRB. The formula for the RREL of FB is derived from the actual stress situation of FB in this paper. The load acting on the FB is related to the deformation force and engagement force of the FS. The radial force on the FB is transmitted by the radial component of the torque of the FS, and the formula of EREL is derived according to the force characteristics of the FB so as to deduce the new design formula of FB. The fatigue life of CFB under rated test conditions is about 10,000 h. Using the new design formula to calculate the existing CFB, the results are in good agreement with the actual test results. That verifies the accuracy and effectiveness of the new design formula and provides a theoretical basis for the improvement of the design of FB. In order to meet the requirements of FB with larger inner diameter, it is necessary to improve the structural parameters of existing CFB. The diameter of the rolling elements of FB decreases while keeping the outer diameter constant and the inner diameter increasing. According to the empirical formula of CFB, when the CCRR is constant, the CRR of the IFB becomes smaller. When the number of rolling elements remains unchanged, the distance between the centers of the two rolling elements increases (i.e., the thickness of the separate block of the cage also increases). Calculations of IFB are carried out by means of new design formulas derived for the improved design of CFB, and the changes in geometrical parameters have a great influence on the load distribution and life of FB, which includes the following: the decrease of rolling element diameter leads to the decrease of the RREL of the FB collar, which results in a sharp decrease in the overall fatigue life of the FB. The effect of CCRR on the lifespan and axial bearing capacity of IFB and CFB is consistent. The decrease in the CRR leads to the decrease in the ultimate axial load. The new design formula shows that the decreasing the CCRR increases the RREL of the collar, and increasing the number of rolling elements result in the increase of the RREL of the collar and decrease of the EREL of the collar at the same time. In order to ensure the load carrying capacity of FB and improve the RREL of the collar, so as to improve the fatigue life of FB, methods to increase the number of rolling elements and reduce the radius of curvature coefficient are necessary. The calculation and optimization have been performed to the parameters determination of IFB on the basis of new design formula of FB. The calculation results show that to increase the number of rolling elements and reduce the CCRR within a certain range will improve the capacity and fatigue life and reduce the moment of inertia of FB when the diameter of the rolling element is reduced. Taking into account the stress characteristics and fatigue life of FB and the CCRR of inner and outer rings, the diameter and number of rolling elements of IFB is determined. The FEA results have shown that in the case of the same displacement of deformation, the maximum equivalent force of the IFB collar is smaller than that of the CFB, which is due to the fact that the number of rolling elements of the IFB is more than CFB, improving the load carrying capacity of the IFB. While decreasing the CCRR of IFB collar, the deformation generated at the contact between the rolling elements and raceway has a certain effect on the ellipse contact, and reducing the width of the inner ring increases the maximum equivalent force of the FB. The material selected for the FB collar is GCr15, and the yield limit is about 518.42 MPa. According to the FEA results, it can be found that the maximum equivalent force of the CFB and the IFB are all less than the yield limit, and the material can meet the performance requirements.