| China is the country with the largest capacity of wind turbine,but there is still a certain technical gap compared to foreign developed countries in the field of research and manufacture of torque limiter of wind turbine.When wind turbine is overloaded,torque limiter is the key part of overload protection in the wind power coupling,which can make the active end and load end separate,effectively protect the normal operation of the wind turbine.At present,there is no complete design model and evaluation system for torque limiter.At the same time,the research on the temperature rise of friction pair in the sliding process of torque limiter is only based on the work done by friction torque,and the distribution of temperature field and stress field is not studied in more detail.In response to the above problems,the thermal mechanical coupling analysis of torque limiter is carried out and the fatigue life is evaluated.At the same time,the structure of torque limiter is optimized by combining the simulation results.Finally,the performance measurement and control system of the torque limiter is established,the grinding-in experiment,sliding torque calibration experiment and reliability experiment of the designed torque limiter are carried out,and its performance is evaluated.The main contents and conclusions of this thesis are as follows:(1)The design mathematical model of torque limiter is established according to the slip torque.Firstly,the basic structure and working principle of the torque limiter are analyzed.Secondly,based on the slip torque,the friction pair material,friction plate,disc spring and spring pressure regulating element of the torque limiter are designed,and the design mathematical model is established.Finally,the relationship between internal and external radius of friction plate,spring load and screw tightening turns and slip torque is studied.(2)The theory of thermal coupling analysis and fatigue life analysis of torque limiter are studied systematically.Firstly,the contact theory,friction heat generation theory and heat transfer theory are introduced.Secondly,the three-dimensional transient temperature field heat conduction equation of friction pair of torque limiter is deduced,and its initial and boundary conditions are determined.Finally,the fatigue failure process and fatigue life analysis method of metal parts are introduced.(3)The thermal coupling analysis of friction pair model of torque limiter is carried out by using the temperature displacement coupling solver of ABAQUS software.Firstly,the friction pair model of torque limiter is introduced into ABAQUS software.Based on the theory of thermal coupling and reasonable assumption,the boundary conditions of simulation analysis are calculated,and the thermal coupling analysis model under the slip condition of torque limiter is obtained.The simulation results reveal the distribution gradient and change trend of temperature field and stress of friction pair of torque limiter under the condition of thermal coupling.At the same time,with the prolongation of sliding time,it is found that the maximum temperature and maximum stress of friction pair appear in the middle of friction area.Secondly,the influence of different factors(slip speed and spring load)on the maximum stress and maximum temperature of dual disk is studied.Finally,based on the results of thermal coupling analysis,the fatigue failure form and main danger area of friction pair are determined.The fatigue life prediction of torque limiter is carried out by using strain range fatigue life method.The fatigue failure of torque limiter is determined after 215 stress cycles under sliding condition.(4)Based on the results of thermal coupling simulation,the structure of torque limiter is optimized.Through the thermal coupling analysis and fatigue life prediction of torque limiter,it is found that the torque limiter has the problems of high thermal stress,high temperature and low fatigue life under the existing design structure.Therefore,the optimization design of friction pair of torque limiter is proposed.In the process of optimization design,the approximate model of maximum stress and maximum temperature of friction pair is established by using Isight software,and then the optimal solution of the approximate model is found by pointer algorithm.Finally,the design variables in the optimal solution are substituted into the finite element model to calculate.The error between the actual value and the predicted value of the approximate model is less than 1.7%,which proves that the approximate model has high reliability.The final optimization results show that the maximum stress of friction disc of torque limiter decreases from 328 MPa to 238.6 MPa,the maximum temperature decreases from 762.2℃to 604.6℃ and fatigue life increases from 215 to 1521 times.(5)According to the test requirements of slip torque of torque limiter,a set of torque limiter performance test system is developed and designed,and the performance evaluation experiment of torque limiter is carried out.Firstly,the performance measurement and control system is designed,which is based on PLC and configuration software as the interface.Secondly,the performance evaluation of the slip torque and reliability of torque limiter is carried out by using the measurement and control system.It is found that the error between the measured slip torque and the set slip torque is 6.7%,which meets the design requirements of 10%.Based on the initial structure design of torque limiter,the structure optimization and performance evaluation are carried out by numerical simulation,optimization design and experimental research.The results of the study are of great significance to the quality evaluation and performance improvement of torque limiter. |
