| As the core part of the CVT,the metal belt bears the important task of transmitting power.The metal belt is composed of friction blocks and steel rings,but excessive wear of the friction blocks will affect the transmission efficiency of CVT,and even lead to the failure of the metal belt.Meanwhile,the fatigue will cause deformation and fracture of friction plate,which also can lead to failure of the metal belt.The failure of the friction blocks determines the service life of the entire metal belt.In order to improve the service life of the metal belt,the wear and fatigue of the friction block were studied in this paper,and the main work bad been done as follows:1.The geometric relation of the metal belt CVT and the calculation of its main parameters.The basic structure and working principle of CVT were discussed,and the geometric relation of the transmission was deduced;The force of the steel ring and the friction block was analyzed.On the basis of the above,the basic parameters such as the size of the axial force and the size of the steel ring are calculated according to the basic parameters of the object.2.In this paper,the contact stress between the friction block and the pulley was theoretically calculated;At the same time,CAE software was used to simulate the contact.The results show that the contact stress increase from left to right,and the maximum stress value is almost the same as that of the theoretical calculation.The wear patterns of the friction blocks were studied,and the surface morphology of the friction block was observed and analyzed.The results show that the degree of side wear is deepened from left to right.Based on the Archard model,the calculation model of the wear depth of the friction block was deduced.On this basis,the estimation model of wear life was deduced,which lay the foundation for comparative analysis of life.3.The entity model of CVT was established.Some common methods of flexible treatment of steel ring were summarized.At the same time,the steel ring was processed to flexible body.The dynamic model of CVT was established by the solid model,and the simulation analysis was carried out.The analysis of the friction block,located in the active pulley inlet area,was carried out.The results show thatthe variation trend of the contact force of the friction plate is consistent with the theoretical analysis,and the reliability of the simulation model is verified.The stress curve is obtained,namely friction block load time history,which provides the basis for the study of the fatigue life.4.The basic theory and method of fatigue and fatigue life prediction were described.The fatigue life analysis process of the friction block was determined.And the static analysis of friction block was carried out.At the same time,the material S-N curve of the friction block was drew,based on the yield strength of the friction block.The fatigue life prediction of the friction plate was studied,based on the static analysis results,the S-N curve and the load time history.The results show that the fatigue life is92.15 ?10 cycles,under the condition that the speed ratio is 2.35 and the torque is 160N·m,and the minimum life appears at the arc of the saddle surface.The number of cycles was converted to the life time,and the wear life was estimated.The results show that under the above conditions,the wear life is lower than the fatigue life. |
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