With the development of the automotive industry, disc brake noise has become an issue of growing concern to the automotive industry and customers. In this paper, the types of disc brake noise have been discussed. Afte...With the development of the automotive industry, disc brake noise has become an issue of growing concern to the automotive industry and customers. In this paper, the types of disc brake noise have been discussed. After that, the theories and models that have been proposed as an explanation of brake squeal are reviewed. On the basis of these theories and models, some example simulations of disc brake squeal which use the Finite Element method and mathematical model have been introduced.展开更多
This paper presents a dynamic model for a disc subjected to two sliders rotating in the circumferential direction over the top and bottom surfaces of the disc.The two sliders are vertically misaligned and each is a ma...This paper presents a dynamic model for a disc subjected to two sliders rotating in the circumferential direction over the top and bottom surfaces of the disc.The two sliders are vertically misaligned and each is a mass-spring-damper system with friction between the slider and the disc. The moving loads produced by misaligned sliders can destabilise the whole system.Stability analysis is carried out in a simulated example.This model is meant to explain the friction mechanism for generating unstable vibration in many applications involving rotating discs.展开更多
During the braking process,a large amount of heat energy is generated at the friction surfaces between the brake disc and pads and rapidly dissipates into the disc volume.In this paper,a three-dimensional thermo-mecha...During the braking process,a large amount of heat energy is generated at the friction surfaces between the brake disc and pads and rapidly dissipates into the disc volume.In this paper,a three-dimensional thermo-mechanical coupling model of high-speed wheel-mounted brake discs containing bolted joints and contact relationships is established.The direct coupling method is used to analyze the temperature and stress of the brake discs during an emergency braking event with an initial speed of 300 km/h.A full-scale bench test is also conducted to monitor the temperatures of the friction ring and bolted joints.The simulation result shows that the surface temperature of the friction ring reaches its peak value of 414°C after 102 s of braking,which agrees well with the bench test result.The maximum alternating thermal stress occurs in the bolt hole where the maximum circumferential compressive stress is−658 MPa and the maximum circumferential tensile stress is 134 MPa.During the braking process,the out-of-plane deformation of the middle part of the friction ring is larger than that of the edge,which increases the axial tensile load of the connecting bolt.This work provides support for the design of brake discs and connecting bolts.展开更多
In this paper,a long stroke moving secondary permanent magnet linear eddy current brake is proposed.Without exciting coils,the permanent magnet eddy current brake possesses the advantage of saving copper and better re...In this paper,a long stroke moving secondary permanent magnet linear eddy current brake is proposed.Without exciting coils,the permanent magnet eddy current brake possesses the advantage of saving copper and better reliability.The topology and operating principle are presented.The mathematical model was derived with the layer theory.The braking force characteristic was analyzed using the finite element method.The structural parameters of the long stroke moving secondary permanent magnet linear eddy current brake were studied by referring the design progress of the other types of eddy current brakes.Finally,a prototype of long stroke moving secondary permanent magnet linear eddy current brake was built and tested,and the experimental result verifies the correctness of the above analysis.展开更多
Researchers have long been studying the effects of the modification of friction material compositions on their tribological properties.Predictive models have also been developed,but they are of limited use in the desi...Researchers have long been studying the effects of the modification of friction material compositions on their tribological properties.Predictive models have also been developed,but they are of limited use in the design of new compositions.Therefore,this research aims to investigate the tribological behaviour of single ingredients in friction materials to develop a tribological dataset.This dataset could then be used as a foundation for a cellular automaton(CA)predictive model,intended to be a tool for designing friction materials.Tribological samples were almost entirely composed of four distinct friction material ingredients,and one sample composed of their mixture was successfully produced.Pin-on-disc(PoD)tribometer testing and scanning electron microscopy/energy-dispersive X-ray spectroscopy(SEM/EDXS)analysis were used for the tribological characterization.Each material showed distinct tribological properties and evolution of the contact surface features,and the synergistic effect of their mutual interaction was also demonstrated by their mixture.展开更多
Developing disc-brake pair materials with better performances is a key technique for thedisc brake of drilling rig. Screening experiments were carried out with five different brake-disc ma-terials in pair with two dif...Developing disc-brake pair materials with better performances is a key technique for thedisc brake of drilling rig. Screening experiments were carried out with five different brake-disc ma-terials in pair with two different brake-block materials. The frictional coefficient along with the cor-responding steady coefficient and fluctuating coefficient as well as the wear rate have been dis-cussed. Some conclusions have been achieved: (1) Between the two different cladding materialsbuilt-up on the steel 20~# and 35~# as brake-disc materials, the overall tribological behaviour of theone is better than that of the other. (2) Between the two brake-block composites, the one is betterthan the other. (3) Among these brake pair materials, the tribological behaviours of the second kindof brake-block composite in pair with the second build-up welding material are much better thanthat of the others, therefore, these materials can be selected preliminarily to use in disc brake fordrilling rig.展开更多
In the automotive and transport industry,braking noise and vibrations are persisting issues and difficult to control.Automo-tive engineers and researchers are putting considerable effort into overcoming these problems...In the automotive and transport industry,braking noise and vibrations are persisting issues and difficult to control.Automo-tive engineers and researchers are putting considerable effort into overcoming these problems,and significant breakthroughs have been made in this area.In this study,M-shaped grooves were bionically designed and manufactured on the frictional surfaces of four automotive brake discs using a laser machine.Various tests were conducted to characterize the physical and mechanical performance of the modified discs along with their noise and vibration responses.The experimental results demonstrate that discs with laser-machined grooved surfaces have better surface hardness and residual stress reduction than discs with un-grooved surfaces.Significant improvement in the braking performance was observed in terms of disc thickness variation,friction and wear,noise,and vibration reduction.It is concluded that the reduction in braking noise and vibrations is mainly caused by the reduction in the coefficient of friction and wear,increase in damping ratio,and improvement of disc thickness variation of the brake disc by laser surface grooving.展开更多
基金This paper is sponsored by Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘With the development of the automotive industry, disc brake noise has become an issue of growing concern to the automotive industry and customers. In this paper, the types of disc brake noise have been discussed. After that, the theories and models that have been proposed as an explanation of brake squeal are reviewed. On the basis of these theories and models, some example simulations of disc brake squeal which use the Finite Element method and mathematical model have been introduced.
文摘This paper presents a dynamic model for a disc subjected to two sliders rotating in the circumferential direction over the top and bottom surfaces of the disc.The two sliders are vertically misaligned and each is a mass-spring-damper system with friction between the slider and the disc. The moving loads produced by misaligned sliders can destabilise the whole system.Stability analysis is carried out in a simulated example.This model is meant to explain the friction mechanism for generating unstable vibration in many applications involving rotating discs.
基金Supported by Natural Science Foundation of China(Grant No.52075032)Technology Research and Development Program Project of CHINA RAILWAY(Grant No.P2020J024).
文摘During the braking process,a large amount of heat energy is generated at the friction surfaces between the brake disc and pads and rapidly dissipates into the disc volume.In this paper,a three-dimensional thermo-mechanical coupling model of high-speed wheel-mounted brake discs containing bolted joints and contact relationships is established.The direct coupling method is used to analyze the temperature and stress of the brake discs during an emergency braking event with an initial speed of 300 km/h.A full-scale bench test is also conducted to monitor the temperatures of the friction ring and bolted joints.The simulation result shows that the surface temperature of the friction ring reaches its peak value of 414°C after 102 s of braking,which agrees well with the bench test result.The maximum alternating thermal stress occurs in the bolt hole where the maximum circumferential compressive stress is−658 MPa and the maximum circumferential tensile stress is 134 MPa.During the braking process,the out-of-plane deformation of the middle part of the friction ring is larger than that of the edge,which increases the axial tensile load of the connecting bolt.This work provides support for the design of brake discs and connecting bolts.
基金This work was supported in part by the National Natural Science Foundation of China under Grant 51877051,the Research and Development Project of Scientific and Technological Achievements in Provincial Universities of Heilongjiang Education Department under Grant TSTAU-C2018014.
文摘In this paper,a long stroke moving secondary permanent magnet linear eddy current brake is proposed.Without exciting coils,the permanent magnet eddy current brake possesses the advantage of saving copper and better reliability.The topology and operating principle are presented.The mathematical model was derived with the layer theory.The braking force characteristic was analyzed using the finite element method.The structural parameters of the long stroke moving secondary permanent magnet linear eddy current brake were studied by referring the design progress of the other types of eddy current brakes.Finally,a prototype of long stroke moving secondary permanent magnet linear eddy current brake was built and tested,and the experimental result verifies the correctness of the above analysis.
文摘Researchers have long been studying the effects of the modification of friction material compositions on their tribological properties.Predictive models have also been developed,but they are of limited use in the design of new compositions.Therefore,this research aims to investigate the tribological behaviour of single ingredients in friction materials to develop a tribological dataset.This dataset could then be used as a foundation for a cellular automaton(CA)predictive model,intended to be a tool for designing friction materials.Tribological samples were almost entirely composed of four distinct friction material ingredients,and one sample composed of their mixture was successfully produced.Pin-on-disc(PoD)tribometer testing and scanning electron microscopy/energy-dispersive X-ray spectroscopy(SEM/EDXS)analysis were used for the tribological characterization.Each material showed distinct tribological properties and evolution of the contact surface features,and the synergistic effect of their mutual interaction was also demonstrated by their mixture.
文摘Developing disc-brake pair materials with better performances is a key technique for thedisc brake of drilling rig. Screening experiments were carried out with five different brake-disc ma-terials in pair with two different brake-block materials. The frictional coefficient along with the cor-responding steady coefficient and fluctuating coefficient as well as the wear rate have been dis-cussed. Some conclusions have been achieved: (1) Between the two different cladding materialsbuilt-up on the steel 20~# and 35~# as brake-disc materials, the overall tribological behaviour of theone is better than that of the other. (2) Between the two brake-block composites, the one is betterthan the other. (3) Among these brake pair materials, the tribological behaviours of the second kindof brake-block composite in pair with the second build-up welding material are much better thanthat of the others, therefore, these materials can be selected preliminarily to use in disc brake fordrilling rig.
基金This study was supported by the Science and Technology Committee of Shanghai Municipal Key Project(1806052400)the NSFC Project(51275126).
文摘In the automotive and transport industry,braking noise and vibrations are persisting issues and difficult to control.Automo-tive engineers and researchers are putting considerable effort into overcoming these problems,and significant breakthroughs have been made in this area.In this study,M-shaped grooves were bionically designed and manufactured on the frictional surfaces of four automotive brake discs using a laser machine.Various tests were conducted to characterize the physical and mechanical performance of the modified discs along with their noise and vibration responses.The experimental results demonstrate that discs with laser-machined grooved surfaces have better surface hardness and residual stress reduction than discs with un-grooved surfaces.Significant improvement in the braking performance was observed in terms of disc thickness variation,friction and wear,noise,and vibration reduction.It is concluded that the reduction in braking noise and vibrations is mainly caused by the reduction in the coefficient of friction and wear,increase in damping ratio,and improvement of disc thickness variation of the brake disc by laser surface grooving.