Regulation Of Tribological Behavior Of High-Speed Train Braking Interface Via Damping Element

Friction braking of high-speed trains is mainly realized by the kinetic energy consumed by friction between the brake disc friction block and brake disc,which must ensure that the train can stop within a specified distance to ensure the safety of train operation.According to the braking control strategy of high-speed trains in China,when the train speed is lower than60 km/h,mechanical friction braking starts to step in and work together with electric braking.When the train speed is lower than 20 km/h,mechanical friction(friction between brake disc friction blocks and brake disc)braking is used to control the train speed until the train stops.Under the action of low train speed and strong disc-plate friction,it is extremely easy to induce the braking system to produce high frequency and high-intensity friction-induced vibration and noise(FIVN),which not only endangers brake system safety but also brings great noise pollution along the railway.Therefore,it is of great significance to explore effective measures to suppress the FIVN of the high-speed train braking system,and then try to improve the tribological behavior of the braking interface and realize the collection of friction-induced vibration(FIV)energy,to ensure the safe operation of high-speed trains.In recent years,introducing damping elements into friction systems to suppress FIVN intensity and improve friction and wear characteristics of interfaces is considered to be an excellent method.Therefore,this study aims at the problems of the high frequency and intensity of FIVN in the case of low running speed and strong disc-plate friction of high-speed trains.Based on tribology and dynamics,the mechanism of regulating the braking FIVN by Mn-Cu damping alloy gaskets was proved with means of surface morphology microscopic analysis equipment,signal processing method,and finite element simulation.On this basis,designed an Mn-Cu damping alloy and rubber damping staggered composite structure,and studied the regulation mechanism of the structure on the tribological behavior of braking.A new method combining energy collection and interface tribological behavior regulation with sandwich damping piezoelectric structure is proposed.The main research contents and conclusions of this thesis are as follows:(1)Mn-Cu damping alloy gaskets were installed on the leading edge and the trailing edge of the pentagonal friction block.Then the differences in the FIVN and friction wear morphology of the braking system under different installation modes was evaluated by tribology tests and finite element analysis.The results showed that the contact behavior of the braking interface was improved by Mn-Cu damping alloy gaskets.The vibration signal intensity in the normal and tangential,the intensity of friction noise were reduced by Mn-Cu damping alloy gaskets.The leading edge and the trailing edge of friction blocks installed MnCu damping alloy had the much better interface contact behavior.Their surface wear was relatively mild,while the contact platform was relatively fragmented and smaller in size.And its surface didn’t have the obvious furrow with the serious peeling phenomenon.nick shallow and narrow width.While the friction surface temperature distribution of the brake disc was more even.(2)The influence of four kinds of composite structure dampers,such as Mn-Cu damping alloy and silicon rubber damping staggered composite structure,on the tribological behavior of the braking interface was evaluated through the brake tribological test.The results showed that Mn-Cu damping alloy and rubber damping staggered composite structure could better adjust the contact state of the braking interface and changed the distribution of wear debris on the braking interface.Then affected the FIVN characteristics of the whole system.The two damping elements were better meshed together through staggered recombination to avoid the relative sliding between them.Part of the vibration energy generated is dissipated by Mn-Cu damping alloy so that the rubber damping could better adjust the braking interface.Therefore,the staggering composite structure improved the contact behavior.(3)A kind of sandwich damping piezoelectric structure was designed and holes were opened to its side.The influence of the structure on the braking tribology behavior was evaluated from the aspects of FIVN,output voltage,and surface wear by braking tribology tests and finite element analysis.Then verified the feasibility of the structure on the friction interface regulation and vibration energy harvesting.The results showed that the structure with open-hole damping could suppress the FIVN intensity and continuity,and reduced the eccentric wear angle of the friction block.The friction and wear characteristics of the friction block surface were improved by the structure.At the same time,the maximum output voltage can be used to light the LED lamp group.The optimization of the hole structure was beneficial to increase the damping deformation and the output voltage.The contact stress distribution on the surface of the friction block had also been improved with the FIVN intensity of the braking system was suppressed significantly.