Resesrch On Thermal Load Performance Of Brake Disc Of Straddle-type Monorail Vehicle

With the continuous development of science and technology,in order to meet the daily travel needs of urban population,urban rail transit has rapidly developed into an effective solution.Among them,the straddle-type monorail has many advantages,such as strong climbing ability,small turning radius,less land occupation,low noise and low cost,and will have a huge application market in China in the future.The straddle-type monorail often brakes in the course of operation because of their small turning radius and complex terrain in the city.Therefore,the brake disc bears more intense heat load than other urban rail transit vehicles,which leads to a significant decrease in fatigue life and thus affects the safe operation of vehicles.Due to the limitation of test conditions,the research on the thermal load of the Straddle-type monorail brake disc is still in the exploratory stage at home and abroad.In order to simulate the heat load of the straddle-type monorail brake disc more in line with the actual situation,the research method of simulating the contact friction thermogenesis model is adopted in this thesis.In the ABAQUS software,the physical model for 1:1 brake disc was established,and the calculation of the parameters related to the typical brake operation conditions of both the usual brake and emergency brakes was completed.Combined with the braking conditions,the solid model was set with the boundary condition models of velocity displacement and convection heat transfer,and the finite element simulation models of the straddle-type monorail vehicle brake disc and friction plate were established.The transient temperature field of the brake disc is simulated and analyzed.Then the simulation results are compared with the simulation results using the equivalent heat source method.In addition,combined with the simulated contact friction heat generation model,the thermal stress field of the brake disc is simulated by the thermo-mechanical complete coupling method,and the simulation results of the stress field under the two braking conditions are obtained,and the distribution and variation rules of the stress field in different directions are compared and analyzed.Finally,the static evaluation of the brake disc is carried out Refer to the UIC ORE B12/RP17 test report,and combined with MATLAB,the fatigue performance of the brake disc is evaluated with six incremental steps of analysis under emergency braking condition in Goodman diagram revised by Smith graphic form.Through the simulation analysis of the temperature field and thermal stress of the Straddletype monorail brake disc under two braking conditions,the results show that: As for the temperature field,the temperature field obtained by simulating the contact friction thermogenesis model is asymmetrical.The maximum temperature is located in the middle of the contact friction area of the brake disc near the outside diameter.The temperature change curve of the node is "sawtooth",and the temperature difference between the nodes along the radial direction is large,and there is a phase difference in the temperature change curve along the circumferential direction.The temperature field obtained by using the equivalent heat source method presents a symmetrical distribution,and the node temperature changes smoothly with time.The temperature difference between the radial and circumferential nodes is very small.The results show that the method of simulating friction heat generation model is more practical because the effect of contact friction is considerd.As for the stress field,the simulation results show that the stress field is asymmetrically distributed,and the stress of the joint changes with time in a "sawtooth" shape.And the maximum stress is distributed near the outside diameter in the friction area,which is the same as the maximum temperature.The stress difference between radial and circumferential joints is obvious,and the phase difference exists along the curve of circumferential joints,and the stress difference is small.The simulation results show that the stress field and temperature field are coupled with each other.As for fatigue,the results show that the static strength and fatigue strength of the brake disc meet the safety requirements.