Comprehensive modeling strategy for thermomechanical tribological behavior analysis of railway vehicle disc brake system

A comprehensive modeling strategy for studying the thermomechanical tribological behaviors is proposed in this work.The wear degradation considering the influence of temperature(T)is predicted by Archard wear model with the help of the UMESHMOTION subroutine and arbitrary Lagrangian–Eulerian(ALE)remeshing technique.Adopting the proposed method,the thermomechanical tribological behaviors of railway vehicle disc brake system composed of forged steel brake disc and Cu-based powder metallurgy(PM)friction block are studied systematically.The effectiveness of the proposed methodology is validated by experimental test on a self-designed scaled brake test bench from the perspectives of interface temperature,wear degradation,friction noise and vibration,and contact status evolution.This work can provide an effective way for the investigation of thermomechanical tribological behaviors in the engineering field.

Thermal fatigue and wear of compacted graphite iron brake discs with various thermomechanical properties

The increase in payload capacity of trucks has heightened the demand for cost-effective yet high performance brake discs.In this work,the thermal fatigue and wear of compacted graphite iron brake discs were investigated,aiming to provide an experimental foundation for achieving a balance between their thermal and mechanical properties.Compacted graphite iron brake discs with different tensile strengths,macrohardnesses,specific heat capacities and thermal diffusion coefficients were produced by changing the proportion and strength of ferrite.The peak temperature,pressure load and friction coefficient of compacted graphite iron brake discs were analyzed through inertia friction tests.The morphology of thermal cracks and 3D profiles of the worn surfaces were also discussed.It is found that the thermal fatigue of compacted graphite iron discs is determined by their thermal properties.A compacted graphite iron with the highest specific heat capacity and thermal diffusion coefficient exhibits optimal thermal fatigue resistance.Oxidization of the matrix at low temperatures significantly weakens the function of alloy strengthening in hindering the propagation of thermal cracks.Despite the reduced hardness,increasing the ferrite proportion can mitigate wear loss resulting from low disc temperatures and the absence of abrasive wear.

Numerical and Experimental Analysis of the Aerodynamic Torque for Axle-Mounted Train Brake Discs

As the velocity of a train increases,the corresponding air pumping power consumption of the brake discs increases proportionally.In the present experimental study,a standard axle-mounted brake disc with circumferential pillars was analyzed using a 1:1 scale model and a test rig in a wind tunnel.In particular,three upstream velocities were selected on the basis of earlier investigations of trains operating at 160,250,and 400 km/h,respectively.Moreover,3D steady computational fluid dynamics(CFD)simulations of the flow field were conducted to compare with the wind tunnel test outcomes.The results for a 3-car train at 180 km/h demonstrated:(1)good agreement between the air resistance torques obtained from the wind tunnel tests and the related numerical results,with differences ranging from 0.95%to 5.88%;(2)discrepancies ranging from 3.2 to 3.8 N·m;(3)cooling ribs contributing more than 60%of the air resistance torque;(4)the fast rotation of brake discs causing a significantly different flow field near the bogie area,resulting in 25 times more air pumping power loss than that obtained in the stationary brake-disc case.

Simulation Analysis and Verifcation of Temperature and Stress of Wheel-Mounted Brake Disc of a High-Speed Train

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.

Preparation and characteristics of C/C composite brake disc by multi-cylindrical chemical vapor deposition processes

The C/C composite brake discs were prepared by tri-cylindrical chemical vapor deposition （CVD） process. The optimum processing parameters were as follows： deposition temperature was 830 - 930 ℃, the gas- flow rates of N2 and propylene were 4.8 - 5.2 m^3/h and 5.8 - 6.2 m^3/h, respectively, the furnace pressure was 4.5 - 5.5 kPa and the deposition time was 200 h. The effects of processing parameters on the densified rates, thermal-physical property and mechanical performance of C/C composite brake discs were studied. The results show that density, heat conductivity, bend strength and abrasion ratio of the multi-cylindrica brake discs are 1. 02 - 1. 78 g/cm^3 , 31 W/（m·K）, 114 MPa and 7μm/s, respectively, which are approximately similar to those of the singlecylindrical ones. The gas tlow rate has no relation to the number of the cylinder and furnace loading. The utilization ratio of carbon can be improved by multi-cylinder CVD process without changing the characteristics of brake disc.

A Review of a Study on Disc Brake Noise

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.

Investigation into precision engineering design and development of the next-generation brake discs using Al/SiC metal matrix composites

Substantially lightweight brake discs with high wear resistance are highly desirable in the automotive industry.This paper presents an investigation of the precision-engineering design and development of automotive brake discs using nonhomogeneous Al/SiC metal-matrixcomposite materials.The design and development are based on modeling and analysis following stringent precision-engineering principles,i.e.,brake-disc systems that operate repeatably and stably over time as enabled by precision-engineering design.The design and development are further supported by tribological experimental testing and finite-element simulations.The results show the industrial feasibility of the innovative design approach and the application merits of using advanced metal-matrix-composite materials for next-generation automotive and electric vehicles.

Gear walk instability caused by brake-disc friction characteristics

A multi-body dynamic rigid-flexible coupling model of landing gear is established to study the gear walk instability caused by the friction characteristics of the brake disc.After validating the model with the experimental results,the influence of the landing gear structure and braking system parameters on gear walk is further investigated.Among the above factors,the slope of the graph for the friction coefficient of the brake disc and the relative velocity of brake stators and rotors is the most influential factor on gear walk instability.Phase trajectory analysis verifies that gear walk occurs when the coupling of multiple factors causes the system to exhibit an equivalent negative damping trend.To consider a more realistic braking case,a back propagation neural network method is employed to describe the nonlinear behavior of the friction coefficient of the brake disc.With the realistic nonlinear model of the friction coefficient,the maximum error in predicting the braking torque is less than 10%and the effect of the brake disc temperature on gear walk is performed.The results reveal that a more negative friction slope may contribute to a more severe unstable gear walk,and reducing the braking pressure is an effective approach to avoid gear walk,which provides help for future braking system design.

四自由度盘式制动系统的非线性动力学特性分析

为了研究非线性因素对盘式制动系统动力学的影响,建立了四自由度的非线性动力学模型.采用Stibeck模型及相关参数,并采用龙格-库塔法求解动力学方程,利用分叉图、频域图、相平面图、时域图、庞加莱截面图分析了不同工况下盘式制动器的振动特性.结果表明,制动压力的增大会导致系统的振动稳定性减弱;较低的车速更容易引发系统的振动;较大的制动片支承刚度会增大系统的振动特性.

下运带式输送机盘式制动器液压系统设计及研究

基于下运带式输送机的制动要求,结合使用工况,设计基于电液比例溢流阀的盘式制动器液压系统,对液压系统最大工作压力、最大工作流量等关键参数进行计算,对电液比例溢流阀、蓄能器等关键元件进行选型,设计合理可靠的盘式制动系统液压站;结合液压系统的工作原理,对不同工况下制动系统的动作指令进行详细的设计和阐述;利用AMESim搭建基于电液比例溢流阀的盘式制动器液压系统,探究系统的动态响应特性。结果表明:设计的盘式制动器液压系统具有较好的启动特性,能够很好地满足下运带式输送机的使用要求。

Pin-on-disc tribological characterization of single ingredients used in a brake pad friction material

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.

汽车盘式制动器尖叫声仿真研究

针对某乘用车前制动器低频尖叫问题,建立了制动系统稳定性分析有限元模型及多工况矩阵,利用复模态分析方法对该制动系统稳定性进行了分析,结果表明,系统在1830 Hz频率下出现不稳定模态,与实车制动尖叫试验结果吻合良好。采用组件贡献和模态贡献分析方法对不稳定模态进行了分析,结果显示,制动钳的一阶扭转模态和摩擦片的一阶弯曲模态贡献显著,并对制动钳和摩擦片进行了优化,仿真结果表明,制动钳结构加强后系统1830 Hz不稳定模态趋于稳定,摩擦片材料及结构调整后,系统稳定性得到改善,但仍处于不稳定区间,噪声难以消除,与试验验证结果一致,主观评价结果为可接受。

石油钻机液压盘式刹车安全性分析

为了提高液压盘式刹车在石油钻机上的工作安全性,对液压盘式刹车工作原理、安全风险进行了分析,说明了设计上采取的安全风险削减措施。同时分析了维修保养不善导致的安全隐患,针对安全隐患提出了设置刹车监测系统,以及对液压盘刹刹车功能、性能及阀件工作状态进行实时检测及预警的安全性提升策略。该刹车监测系统的实施将大幅提升钻井作业的安全性。

矿井提升机制动盘状态监测及制动系统的优化

针对提升机系统采用非闭环控制模式所存在的制动速度慢、制动冲击大、稳定性不足的问题,提出了一种新的提升机制动盘状态监测及制动系统。其利用制动盘状态监测模块实现了对制动盘状态的实时监测,为制动系统提供基础数据信息并实现了闭环调控,解决了传统控制模式只能根据预设程序制动效果差的不足。对整个系统结构、制动盘监测方案及实际应用情况进行了研究。结果表明,新的制动系统能够将提升机制动反应速度降低33.3%,将制动冲击力降低72.4%,极大提升了提升机的运行稳定性和可靠性。

A DYNAMIC MODEL FOR A DISC EXCITED BY VERTICALLY MISALIGNED,ROTATING,FRICTIONAL SLIDERS

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.

制动过程中闸片材料与制动盘温度关系试验研究

为探讨碳/陶制动盘与不同闸片材料的匹配性,对碳/陶制动盘分别与碳/陶复合闸片、铜基粉末冶金闸片和铁基粉末冶金闸片组成的摩擦副进行制动试验,研究了在制动过程中盘面各点瞬时温度、最高温度、闸片温度与制动工况的关系。结果表明:碳/陶制动盘与碳/陶复合闸片摩擦副温度及温度梯度均高于其他2种摩擦副,其温度梯度在低速制动时随压力的增加而明显增加,当制动速度较高时,温度梯度并没有随压力的增加而增加;对于碳/陶制动盘与铜基和铁基粉末冶金闸片摩擦副,随制动速度和压力的提高,盘面温度梯度变化不明显。原因在于材料导热性和起始摩擦因数决定了盘面的散热能力和制动功率,碳/陶制动盘与碳/陶复合闸片摩擦副因较高的起始摩擦因数以及较低的导热性,其制动功率高和散热能力低,导致盘面温度持续升高。

石油钻井绞车驻车盘刹系统的设计

针对现有盘刹控制系统结构复杂,体积大、成本高,与能耗制动刹车冲突等问题,设计了石油钻井绞车驻车盘刹系统。驻车盘刹控制系统设在司钻房盘刹控制台上,通过I/0模块将现场数据接入到盘刹控制系统的PLC可编程控制器,参与逻辑控制。驻车盘刹控制系统按电控气或气控气方式实现。现场数据控制气液增压泵,气液增压泵通过供油管路为安全钳液缸供液,实现石油钻井绞车刹车与释放。驻车盘刹控制系统同时与钻机各防碰系统联动,完成防碰刹车功能,也可实现钻机使用中断气、断电状态下的紧急刹车保护。

某轻卡盘式制动系统的性能仿真与试验研究

采用计算机辅助工程(CAE)仿真方法和试验测试手段,开展某轻卡盘式制动系统的CAE强度分析、温度场分析及噪声测试分析,结果显示,80 km/h初速度制动工况下,该盘式制动系统关键零件制动盘的屈服强度、热应力和温升曲线均满足设计目标要求,同时实车测试表明,未出现盘式制动系统强度及热应力相关可靠性问题。通过仿真分析与实车测试相结合的开发流程,提升了盘式制动系统的可靠性,缩短了零部件开发周期,降本增效,有效提升了该轻卡车型的产品竞争力。

矿用下运带式输送机制动装置的研究与应用分析

对下运带式输送机进行精确制动是设备运行安全的重要保障。以上社煤矿DSJ120/100/2×315型带式输送机为研究对象,在分析其制动装置基本原理及安装位置要求的基础上,结合上社煤矿实际经验,分析了传统盘式制动装置在实践中存在的问题。针对上述问题,对传统盘式制动装置结构进行改进,配合压力传感器,可通过液压系统的压力控制实现制动力的精确控制。实践表明,改进后的制动装置运行期间没有出现“飞车”情况,验证了改进的盘式制动装置的运行可靠性。

考虑轮轨蠕滑的高速列车制动非线性振动行为研究

为了揭示在制动工况下轮轨蠕滑对高速列车非线性振动的影响,考虑Polach轮轨蠕滑和盘片Stribeck摩擦,建立了高速列车盘式制动系统的3自由度非线性动力学模型,采用数值积分法求解制动系统的振动响应,并与线路试验数据进行对比,验证了模型的有效性。通过该模型进一步研究了低速下盘式制动系统非线性动力学行为,对比分析了Polach轮轨蠕滑模型与双线性轮轨蠕滑模型的差异;探究了平均蠕滑率和轨面条件对制动系统振动的影响;揭示了轮轨黏着与盘式制动系统非线性行为的相互作用机理。结果表明:相比于双线性轮轨蠕滑模型,Polach轮轨蠕滑模型受车速影响更为明显,更加符合实际服役情况;平均蠕滑率增大、轨面条件变差将导致混沌运动出现时的制动压力更小,混沌-周期振动交替出现的次数增加,制动系统振动行为更为复杂。