| The disc brake process is the braking resistance generated by friction to prevent the continuous rotation of the axle,and finally realize the process of decelerating and stopping the train.During the entire braking process,the brake discs and brake pads will generate a lot of heat,and studying how to transfer the generated heat to the air is the key to the service life and safety of the brake discs.There are several ways to improve the heat dissipation performance of brake discs:（1）Change the materials of brake pads and brake discs,so that the friction and wear of brake pads and brake discs can reach a better state;（2）Change the heat dissipation structure inside the brake disc,so that the heat dissipation of the brake disc is better improved.In this paper,a resin-based synthetic brake pad material for low-speed train braking is designed and prepared,and the friction and wear mechanism of the synthetic brake pad material is studied.Then the temperature field and stress field of the brake discs of different structures in the same braking process are analyzed,and a certain basic research is done to optimize the stability and safety of the brake system in work.The work done in this article and the conclusions are as follows:（1）Synthesize TiO2modified reduced graphene oxide（Ti O2@RGO）with a silane coupling agent,use Ti O2@RGO as polyimide（PI）filler particles to prepare polyimide synthetic brake pads,and systematically study the changes friction and wear performance of the brake pad material of synthetic polyimide,and compared with the polyimide material filled with RGO particles,the friction,wear and compression performance of the polyimide material with Ti O2@RGO is significantly better.The main reason is that the addition of Ti O2@RGO reduces the fatigue wear and abrasive wear of the polyimide material.It can be seen that under a higher load,the wear rate of the modified polyimide material is only 1/10 of that of the pure polyimide material.Next,the reasons for this good performance are explored and analyzed.The very good performance of the modified polyimide is attributed to the unique three-dimensional structure of the internal filler Ti O2@RGO and the chemical bond between reduced graphene oxide and titanium dioxide.This unique structure can block the cracks,so that the wear of the polyimide composite material becomes very small.（2）Using modified polyimide synthetic material brake pads and ductile iron brake discs,the entire braking process is simulated in Abaqus engineering simulation software.The linear ribbed brake disc is studied（braking time is 50s,braking start speed:152.6km/h）,and the temperature field and stress field are obtained after simulation.Comparing the temperature field and the stress field,it is found that the temperature in the center area of??the brake disc increases rapidly and reaches the highest temperature of 328°C when braking for about35 seconds.It can be seen from the radial temperature of the brake disc that the brake disc is mainly divided into the central area,the sub-central area,the transition area and the edge area.The temperature of the edge area has been rising during braking,while the temperature of the other three areas is present.First rise and then fall,there is a maximum temperature value.It can be seen from the circumferential temperature that the unit temperature is only related to the area.（3）The internal structure of the brake disc was optimized,and the curved ribbed brake disc and the cylindrical linear brake disc were compared and studied.From the temperature field and stress field generated by the results,we can find that the temperature of the curved ribbed brake disc and the cylindrical linear brake disc is lower than that of the linear ribbed brake disc,and the maximum temperature of the curved ribbed brake disc is the same.Compared with the maximum temperature of the linear ribbed brake disc,the temperature is lowered by 14.6℃. |
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