A trailer car dynamics model considering brake rigging of a high-speed train and its application

Brake systems are essential for the speed regulation or braking of a high-speed train.The vehicle dynamic performance under braking condition is complex and directly affects the reliability and running safety.To reveal the vehicle dynamic behaviour in braking process,a comprehensive trailer car dynamics model(TCDM)considering brake systems is established in this paper.The dynamic interactions between the brake system and the other connected components are achieved using the brake disc-pad frictions,brake suspension systems,and wheel-rail interactions.The force and motion transmission from the brake system to the wheel-rail interface is performed by the proposed TCDM excited by track irregularity.In addition,the validity of TCDM is verified by experimental test results.On this basis,the dynamic behaviour of the coupled system is simulated and discussed.The findings indicate that the braking force significantly affects vehicle dynamic behaviour including the wheel-rail forces,suspension forces,wheelset torsional vibration,etc.The dynamic interactions within the brake system are also significantly affected by the vehicle vibration due to track irregularity.Besides,the developed TCDM can be further employed to the dynamic assessment of such a coupled mechanical system under different braking conditions.

Position Control Optimization of Aerodynamic Brake Device for High-speed Trains

The aerodynamic braking is a clean and non-adhesion braking, and can be used to provide extra braking force during high-speed emergency braking. The research of aerodynamic braking has attracted more and more attentions in recent years. However, most researchers in this field focus on aerodynamic effects and seldom on issues of position control of the aerodynamic braking board. The purpose of this paper is to explore position control optimization of the braking board in an aerodynamic braking prototype. The mathematical models of the hydraulic drive unit in the aerodynamic braking system are analyzed in detail, and the simulation models are established. Three control functions--constant, linear, and quadratic--are explored. Two kinds of criteria, including the position steady-state error and the acceleration of the piston rod, are used to evaluate system performance. Simulation results show that the position steady state-error is reduced from around 12-2 mm by applying a linear instead of a constant function, while the acceleration is reduced from 25,71-3.70 m/s2 with a quadratic control function. Use of the quadratic control function is shown to improve system performance. Experimental results obtained by measuring the position response of the piston rod on a test-bench also suggest a reduced position error and smooth movement of the piston rod. This implies that the acceleration is smaller when using the quadratic function, thus verifying the effectiveness of control schemes to improve to system performance. This paper proposes an effective and easily implemented control scheme that improves the position response of hydraulic cylinders during position control.

The effect of friction block hole configurations on the brake tribological performance of high-speed trains

Three triangular friction block configurations are commonly employed in high-speed train brake systems,namely,unperforated,perforated configuration with one circular hole,and perforated with three circular holes.In this study,we adopted these friction block types to investigate the effect of perforated friction block configurations on the brake performance of high-speed trains based on a self-developed brake test rig.The results indicate the significant impact of the number of the holes on the wear behavior,temperature distribution,and vibration characteristics of the brake interface.The friction surface of the unperforated block is covered by wear debris,while the perforated blocks produce less wear debris.Furthermore,the one-hole block exhibits a more uniform temperature distribution and better vibration behavior than that with three holes.The friction brake is a dynamic process,during which separation and attachment between the pad and disc alternatively occur,and the perforated structure on the friction block can both trap and expel the wear debris.

A Modified Generative Adversarial Network for Fault Diagnosis in High-Speed Train Components with Imbalanced and Heterogeneous Monitoring Data

Data-driven methods are widely considered for fault diagnosis in complex systems.However,in practice,the between-class imbalance due to limited faulty samples may deteriorate their classification performance.To address this issue,synthetic minority methods for enhancing data have been proved to be effective in many applications.Generative adversarial networks(GANs),capable of automatic features extraction,can also be adopted for augmenting the faulty samples.However,the monitoring data of a complex system may include not only continuous signals but also discrete/categorical signals.Since the current GAN methods still have some challenges in handling such heterogeneous monitoring data,a Mixed Dual Discriminator GAN(noted as M-D2GAN)is proposed in this work.In order to render the expanded fault samples more aligned with the real situation and improve the accuracy and robustness of the fault diagnosis model,different types of variables are generated in different ways,including floating-point,integer,categorical,and hierarchical.For effectively considering the class imbalance problem,proper modifications are made to the GAN model,where a normal class discriminator is added.A practical case study concerning the braking system of a high-speed train is carried out to verify the effectiveness of the proposed framework.Compared to the classic GAN,the proposed framework achieves better results with respect to F-measure and G-mean metrics.

列车刹车闸片冶金材料成分配比优化研究

为了促进我国列车刹车闸片粉末冶金材料的发展,研究分析了不同增强组元对粉末冶金材料制备的摩擦材料性能影响。研究分析的2种增强组元分别是羰基铁粉和磷铁粉,粉末冶金材料的基体为超细铜粉,润滑组元为镀铜石墨,摩擦组元为铬铁粉。结果显示,时速低于275 km/h时,磷铁粉材料的摩擦系数更高,时速高于275 km/h时,羰基铁粉的摩擦系数更高,时速为350 km/h时,羰基铁粉材料磨损量为0.625 mg/kJ,磷铁粉材料磨损量为1.634 mg/kJ,研究还探讨了磷铁粉及羰基铁粉对列车刹车材料摩擦性能的影响,对我国粉末冶金材料、制备列车刹车闸片的发展具有指导意义。

Regularity and sensitivity analysis of main parameters of plate effects on the aerodynamic braking drag of a high-speed train

With increase of train speed,braking plate technology has a good application prospect in the high-speed stage of the train.Based on the 1/8 scaled symmetrical train model composed of two half cars,the Reynolds Av era ge Navier-Stokes(RANS)equations and Shear Stress Transfer(SST)k-ωturbulence model are adopted to simulate the aerodynamic performance of the train with plate.The aer odynamic dra g de pendence of single par ameter of the plate(shape,area,angle,position and n umber)is anal ysed,and identification resear c h of the main aerodynamic parameters of the plate is carried out.The numerical settings used in this paper are verified by wind tunnel test data.Results show that the braking plate with an aspect ratio of one has better performance on aerodynamic drag.The area,opening angle and number of plates are basically positively correlated with the total aerodynamic drag of the target car and plate.Arr anging plates at the downstream of the vehicle is a good method of raising total aerodynamic drag.Within the range of plate parameter design in this paper,by using orthogonal design of experiment and the method of range analysis and analysis of variance,the influence degrees of plate parameters on aer odynamic dra g ar e determined,and the order is n umber,ar ea and opening angle of plate.The research results provide theoretical support for the design and safe operation of high-speed trains with aerodynamic braking plates.

Opening Angle Rules of the Aerodynamic Brake Panel

In order to get the relationship between aerodynamic brake effect and the opening angle,based on a high-speed train model in CFD software FLUENT,the aerodynamic force properties from brake panels with different opening angles were analyzed as well as the flow field's variation laws. Six cases were researched,taking opening angles 45°,60°,75°,80°,85° and 90° respectively.Three-dimensional Reynolds-average Navier-Stokes equation combined with k-ε turbulence model was utilized. The control equation was discretized and solved by finite volume method.SIMPLE method was also considered to couple the pressure and velocity fields and search the numeric solutions. Conclusions can be achieved from the results which are shown as follows. When the opening angle increases from 45° to 75°,the aerodynamic forces and the central area with larger pressure increase fast,and the flow field distribution changes greatly; when the opening angle increases from75° to 90°,the aerodynamic forces and the central area with larger pressure increase slowly, and the flow field distribution changes slightly; considering train boundary and opening performance of the wind resistance brake mechanism,the opening angle should be 75°.

Rail temperature rise characteristics caused by linear eddy current brake of high-speed train

The rail temperature rises when the linear eddy current brake of high-speed train is working, which may lead to a change of rail physical characteristics or an effect on train operations. Therefore, a study concerning the characteristics of rail temperature rise caused by eddy current has its practical necessity. In the research, the working principle of a linear eddy current brake is introduced and its FEA model is established. According to the generation mechanism of eddy current, the theoretical formula of the internal energy which is produced by the eddy current is deduced and the thermal load on the rail is obtained. ANSYS is used to simulate the rail temperature changes under different conditions of thermal loads. The research result shows the main factors which contribute to the rising of rail temperature are the train speed, brake gap and exciting current. The rail temperature rises non-linearly with the in- crease of train speed. The rail temperature rise curve is more sensitive to the exciting current than the air gap. Moreover, the difference stimulated by temperature rising between rails of 60 kg/m and 75 kg/m is presented as well.

Design and analysis of the hybrid excitation rail eddy brake system of high-speed trains

Compared to the current eddy braking patterns using a single magnetic source,hybrid excitation rail eddy brakes have many advantages,such as controllability,energy saving,and various operating models.Considering the large braking power consumption of the high-speed train,a hybrid excitation rail eddy brake system,which is based on the principle of electromagnetic field,is proposed to fulfill the needs of safety and reliability.Then the working processes of the mechanical lifting system and electromagnetic system are demonstrated.With the electromagnetic system analyzed using the finite element method,the factors such as speed,air gap,and exciting current have influences on the braking force and attractive force.At last,the structure optimization of the brake system is discussed.

高速列车粉末冶金制动闸片的应用与研究

高速列车通过制动闸片与制动盘相互摩擦作用将动能转化成热能耗散到空气中,从而实现其减速或停车。制动闸片是高速列车机械摩擦制动装置不可或缺的关键部件,其合理的结构和稳定可靠的摩擦材料性能关系着列车运营的安全性与舒适性。粉末冶金闸片因其具有稳定的摩擦因数、优异的耐磨性和耐热性、良好的环境适应性等优点,被广泛应用在高速列车上。文章对国内高速列车的机械摩擦制动与粉末冶金制动闸片的应用进行了简述,同时从闸片结构和摩擦材料两个方面对高速列车粉末冶金制动闸片开展的分析与研究工作进行了综述,介绍了固定连接、弹性连接和浮动连接3种闸片结构原理的差异及研究现状,阐述了高速列车制动闸片摩擦材料摩擦磨损性能及机理的研究。最后,对高速列车制动闸片的未来研究方向提出了展望。

Influence of aerodynamic braking on the pressure wave of a crossing high-speed train

When aerodynamic braking works,the braking wings can change the flow field around the train,which may impact on the comfort and safety.Based on a sliding mesh,the pressure wave and flow field around high-speed trains with aerodynamic braking are analyzed.By comparing three typical intersection situations,the pressure wave of a high-speed train during braking (with or without aerodynamic braking) is studied.The analyses indicate that the pressure wave around the high-speed train body will change while using the aerodynamic braking,causing several pressure pulses on the surface of crossing high-speed trains.The distances between the pressure pulses are equal to the longitudinal distances of the brake wings,but the magnitudes of the fluctuations are less than those induced by the head of crossing trains.During the crossing,a train without aerodynamic braking will not impact the crossing train.

Role of titanium carbide and alumina on the friction increment for Cu-based metallic brake pads under different initial braking speeds

To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds,pad materials with two typical abrasives,titanium carbide(TiC)and alumina(Al_(2)O_(3)),were produced and tested using a scale dynamometer under various initial braking speeds(IBS).The results showed that at IBS lower than 250 km/h,both TiC and Al_(2)O_(3) particles acted as hard points and exhibited similar friction-increasing behavior,where the increase in friction was not only enhanced as IBS increased,but also enhanced by increasing the volume fraction of the abrasives.However,at higher IBS,the friction increase was limited by the bonding behavior between the matrix and abrasives.Under these conditions,the composite containing TiC showed a better friction-increasing effect and wear resistance than the composite containing Al_(2)O_(3) because of its superior particle-matrix bonding and coefficient of thermal expansion(CTE)compatibility.Because of the poor interface bonding between the matrix and Al_(2)O_(3),a transition phenomenon exists in the Al_(2)O_(3)-reinforced composite,in which the friction-increasing effect diminished when IBS exceeded a certain value.

制动闸片磨耗及卡控措施研究

伴随着修程修制改革进程的推进,动车组检修模式的优化、运行里程的延长、运行交路的调整、运行速度的提高,从动车组运行安全有序考虑,现从制动闸片检修要求、判断标准、磨耗情况、使用周期、后续更换预警预测的卡控措施出发,通过大数据分析的方式方法,对制动闸片磨耗情况进行分析研究。结果表明:在交路相对固定的前提下,制动闸片的起始厚度及分布轴位,不影响制动闸片整体磨耗规律成线性变化。针对这一特性制定“一车一表”,结合动车组运行里程及检修可以有效卡控闸片厚度超限情况,同时提高制动闸片的利用效率,降低维修成本,保障动车组线上运行安全有序。

长大坡道高速列车制动闸片磨耗规律分析

高原铁路具有桥隧比高、长大坡道多、高寒高海拔、自然地理环境极其复杂等特点,高速列车长时间在上述复杂环境中运行时,其制动闸片损耗较在平原地区更为严重,但是目前国内尚无先例研究长大坡道环境下在役期间高速列车制动闸片的磨耗情况,导致长大坡道高速列车制动闸片状态监测技术缺乏相应理论支撑.首先通过自适应参数灰度映射方法及结构分解算法融合红外图像和可见光图像的优点,建立了制动闸片图像识别模型.然后以长大坡道和传统坡道为例,对高温环境和低温环境下高速列车制动闸片进行图像采集及磨耗量计算分析.结果显示:在同一环境温度下,高速列车制动闸片在长大坡道与传统坡道下的磨耗量差值随着走行里程的增加而增加;在同一坡道线路下,高速列车制动闸片在高温环境与低温环境下的磨耗量差值随着走行里程的增加基本无变化;高速列车制动闸片磨耗速度受坡道线路的影响比受环境温度的影响更大.研究成果可为研究高原铁路高速列车制动闸片状态监测提供理论支撑.

高速制动工况下Cu基粉末冶金闸片材料摩擦磨损性能

采用粉末冶金工艺,制得铜基摩擦材料;利用MM-1000Ⅱ型摩擦磨损试验机模拟列车实际工况条件,测试其摩擦磨损性能;用扫描电镜观察铜基摩擦材料表面磨痕,并分析其磨损机制。结果表明：一定制动压力下,铜基摩擦材料摩擦因数和磨损率均随着制动速度的增加先升高后降低,150 km/h时制动性能最好,250-300 km/h时制动性能最为稳定;制动速度一定时,随着制动压力的增加,摩擦因数先升高后降低,磨损率增大并趋于稳定,0.4 MPa时摩擦因数最大,0.8-1.0 MPa时制动性能比较稳定;铜基摩擦材料在高速制动工况下的磨损机制主要为磨粒磨损和疲劳磨损。

粉末冶金摩擦材料在高速列车制动中的应用

本文介绍了高速列车摩擦制动和粉末冶金闸瓦及闸片材料的成份、性能和国内外研究概况,并对我国高速列车制动材料的发展提出了建议。

时速300km高速列车铜基粒子强化闸片的研究

通过粉末冶金工艺,制备了铜基粒子强化材料,材料由金属基体铜、铁、铝、锡和多种高硬度陶瓷粒子以及石墨、二硫化钼构成。利用定速摩擦试验机在摩擦压力为0.45~0.9 MPa、模拟列车速度为50~300km.h-1的实验条件下,对制备的材料进行了摩擦性能测试。结果表明:该材料在定速摩擦条件下的摩擦系数大都处于或高于国际铁路联盟(UIC)标准的上限。在1∶1制动动力试验台上,对用该材料制造的高速列车制动闸片进行最高时速达300 km的工况测试。结果表明:该制动闸片的摩擦系数完全处于UIC标准的控制范围内,磨损率为0.37 cm3.MJ-1,并且产生的噪音低,振动小,导热性好,适合在时速300 km的高速列车上使用。

混杂纤维增强酚醛闸片在提速列车上的应用研究

采用混杂纤维作增强材料并以改性酚醛树脂为基体制成提速列车用的制动闸片。在1:1列车动力试验台上对闸片的应用特性进行了测试。试验结果表明,研制的制动闸片在紧急制动、常规制动、洒水制动、坡道调速制动和静摩擦情况下的摩擦性能均十分理想,而且摩擦系数的离散性很小。实验发现,摩擦工作面的成膜控制是解决制动闸片的速度敏感性和温度敏感性问题的关键。

高速动车组粉末冶金闸片研制及试验研究

时速350km/h高速列车在紧急制动过程中将产生巨大的热负荷,制动过程中闸片的瞬时温度将达到900℃以上,在此极端工况下普通的闸片材料将难以胜任。根据UIC标准相关要求,结合中国高速列车的运用特点,研制出一种性能优良的高速列车铜基粉末冶金闸片,经大量试验研究分析最终证明所研制高速动车组粉末冶金闸片摩擦性能优良、导热性、耐磨性好,对制动盘无损伤,满足350km/h高速列车制动系统相关需求。

高速列车刹车片材料的研究进展与展望

高速列车刹车片材料是指固定在高速列车制动盘上的摩擦材料,不同材料的刹车片决定了高速列车不同的制动性能。高速列车的制动速度从200 km/h提升到350 km/h,刹车片材料从粉末冶金(P/M)材料发展到陶瓷基新型材料,其中200 km/h及以下的高速列车刹车片材料逐渐被新型材料替代。重点对高速列车刹车片材料的研究展开讨论,使刹车片材料与不同制动速度的高速列车匹配。高速列车的车速提高1倍,制动功率就需要提高8倍,这对高速列车的制动性能提出了更严格的要求,同时也对刹车片材料的要求更加严格。通过材料种类、性能以及应用3个方面详细介绍了刹车片材料的研究情况。其中材料种类是影响高速列车刹车片性能的主要因素,分别报告了铁基粉末冶金刹车片、铜基粉末冶金刹车片、C/C基刹车片和陶瓷基刹车片的研究现状,对比了上述几种刹车片材料的优缺点。高速列车刹车片的性能好坏决定了它的应用范围,目前应用最广泛的仍然是铜基粉末冶金刹车片,但是伴随着陶瓷基材料的不断优化,其脆性降低、韧性提高,耐磨性优于铜基粉末冶金材料,有望取代铜基粉末冶金刹车片,成为400 km/h及以上高速列车的新型刹车片材料。最后总结出现阶段高速列车刹车片材料存在的问题,并对未来新型刹车片材料的发展前景进行了展望。