Brake Disc Surface Research Articles

Preventing insufficient braking force in wading conditions by strategic use of surface texture on brake discs

Surface texture technology has been widely used in many industrial fields due to its outstanding antifriction and wear-resistance properties. In this study, groove textures with different quantities and inclined angles are prepared on the surface of a brake disc for high-speed railways. The effects of these textures on the braking capacity and wear resistance of the brake disc under dry and wading conditions are investigated. Results reveal that groove textures significantly reduce the damage caused by abrasive wear on the brake disc surface. The reason is that the grooves can capture and collect debris, which effectively mitigates wear. Under dry conditions, the effect of groove texture on the average friction coefficient is found to be negligible. However, under a small number of dripping conditions, the friction coefficient of the nontextured group drops to 0.04. By contrast, the groove textured groups maintain the lowest friction coefficient between 0.15 and 0.35. This excellent drainage performance of the groove textures prevents the formation of a continuous and whole water film, which ensures effective braking. Under a large number of flushing conditions, the groove textured group requires a shorter number of cycles to recover the initial friction coefficient than the nontextured group. Therefore, groove textures effectively overcome the problem of insufficient braking force during wading. In addition, no linear relationship exists between the quantity and inclined angle of grooves and their ability to suppress braking force deficiency. The groove texture is more conducive to improving braking capacity when the number of grooves is 6 and the direction is aligned with the friction direction.

Car Brake Disc Surface Defect Detection Based on Improved YOLOv5

Car Brake Disc Surface Defect Detection Based on Improved YOLOv5

Study on the influence of running parameters on the temperature field of disc brake on long downhill road

The braking system of the vehicle is liable to fail due to the high temperature of frequent braking in the downhill road. This paper analyzes the influence of the main operating parameters of the vehicle on the maximum temperature of the brake disc surface. Firstly, the mechanical characteristics of the vehicle on the long downhill road are analysed, and the Finite Element Model of the brake disc/friction plate is established; Secondly, the effects of gradient, vehicle weight, brake speed threshold and brake pressure on the braking cycle and disc brake temperature field on long downhill roads are studied. The results show that when the gradient increases from 3° to 9°, the maximum temperature of the brake disc increases by 41.6%, while when the vehicle weight increases from 4 to 7 tons, the brake disc temperature only increases by 16.7%. For the braking speed threshold and braking force that the driver can control, selecting a smaller braking force and a lower braking speed threshold can better inhibit the temperature rise of the brake disc. Finally, the effectiveness of the simulation method is verified by the real vehicle test. It is found that the average measured temperature is 9.2%–11.8% lower than the simulated average temperature. It is considered that the modified temperature value can be obtained by reducing the maximum temperature of the simulation model by 5%–6%.

Material Wear Calculation of Braking Surface under High-Power Braking Conditions

The wear phenomenon of the braking surface of a high-power disc brake under emergency braking conditions is analyzed in this paper. Considering the classical Archard wear model, including the influence of the braking load, speed, and friction coefficient on the braking surface, the wear model of the brake disc surface is established to obtain the wear depth and distribution. It is essential to investigate the wear mechanism of the brake disc surface, and the evolution of wear laws is revealed under different braking parameters. The results have shown that the brake disc surface wear is constantly accumulating. The large load, the high speed, and the large friction coefficient would aggravate the surface wear area. It is expected that the wear study of the brake disc surface can guide the design of the disc brake.

Thermal fatigue crack growth behavior of Ni60 coating and bonding area on 20CrNiMo alloy strengthened by laser shock processing

After the laser cladding repair of the brake disc surface in high-speed trains, thermal fatigue cracks in the cladding layer and bonding area are easily observed during the service process. With the aim of solving this problem and decreasing hidden risks, effects of laser shock processing (LSP) on the thermal fatigue life and crack growth behavior of the coating and bonding area of the brake disc were investigated. The results indicate that LSP can refine the columnar grain structures of the cladding layer and bonding area while simultaneously converting residual tensile stress into compressive stress; as a result, the thermal fatigue performance of the brake disc repaired by laser cladding is enhanced. After strengthening by LSP, on the one hand, grain refinement made the structure more uniform and generated more grain boundaries; on the other hand, a pre-set compressive stress field in the cladding layer and bonding area existed. Both aspects were beneficial to dissipate the alternating stress generated by the thermal fatigue process, dissipating the driving force of crack extension and promoting the transformation of thermal fatigue cracks from lateral growth along the interface between the cladding layer and bonding area to the growth into the substrate.

Braking-experimental study on the relationship between friction material type and brake disc temperature

PurposeThis study aims to clarify the relationship of friction material type and brake disc temperature through braking experiment.Design/methodology/approachThe braking performances of resin materials (RM), semimetallic materials (SM) and copper-based powder metallurgy materials (PM) friction blocks mating with forged steel brake disc were examined based on TM-I-type reduced-scale inertial braking dynamometer. The brake disc surface temperature was recorded by infrared thermal camera during braking.FindingsExperimental results indicate that the thermal wear resistance of three friction materials differs with mental content, resulting in the deviation of pad-disc system contact state during braking, thus forming different temperature distribution on the brake disc surface. The peak temperature on the disc face of RM (190°C) is 36.6% and 45.4% lower than that of PM (300°C) and SM (348°C) at 160 km/h. The maximum radial temperature deviation of PM (35°C) is approximately three times than that of RM (12°C) and 40% higher than that of SM (25°C) at 50 km/h, whereas the maximum temperature deviation of SM (97°C) is six times than that of RM (16°C) and 31% higher than that of PM (74°C) at 160 km/h.Originality/valueThe effect of friction material type on the disc surface temperature distribution is revealed, which provides a meaningful reference for the design of brake friction pairs and choice of brake pad materials.

On the Impact of Surface Morphology and Transfer Film on Brake System Performance of High-Capacity Metro Train

The brake system of Melbourne’s High-Capacity Metro Train (HCMT) suffers from consistently extended braking distances after repeating a set of high-speed tests and the commission process. The degradation of brake system performance affects the safety of rolling stock and its conformance to the design standard. In this paper, the root cause leading to the degraded brake performance was analyzed. The brake discs and brake pads of the affected train and another train with normal working conditions were removed and a series of examinations was to determine the reason for the change of friction coefficient between friction surfaces. The results revealed that brake disc samples from the affected TS02 trainset suffered from changed transfer film and surface morphology after multiple consecutive high-speed braking applications. The factors that may affect the brake system performance were analyzed in the laboratory. It was found the brake disc surface had a lower hardness level, coefficient of friction, and smaller contacting area with the brake pad when compared to the brake disc and pad samples from another trainset. These factors harmed the performance of the braking system, and the decrease in the braking effort led to a longer braking distance than expected and failed braking tests.

New insights into reducing airborne particle emissions from brake materials: Grooved textures on brake disc surface

Airborne particles from brake systems have been widely recognised as a great contributor of particulate matter (PM) in railway environments, such as micro- and nano-size airborne particles. Increasing attention is being paid to airborne particles due to their potential for adverse health effects. In the brake system, particulate matter and wear debris mostly come from the wear of brake pair materials. Reducing-friction and anti-wear effect can be achieved by means of a reasonable grooved texture. In this paper, evaluation of friction, wear and particle emission behaviour of commercial brake pads for high-speed trains were studied using a pin-on-disc tribometer. Effect of grooved textures on the characteristics of airborne particles and deposited debris particles, as well as the wear behaviour of brake materials, was investigated on the basis of the brake discs with different numbers and angles of grooved textures. Results show that the grooved texture on the brake disc can effectively restrain airborne brake particulate emissions, particularly particles in the size range of 1.0 µm ≤ d ≤ 5.0 µm. Compared with the brake discs with the grooved texture, the size of the abrasive particles generated in the non-textured test group become smaller, irregular agglomerates of wear debris are more easily formed, and the debris particles are mostly lamellar with smooth surfaces and sharp edges. The wear rate of the pins against the brake disc with the grooved texture slightly increases, but the surface wear of the brake discs is effectively mitigated. In comparison with the number of grooves, the angle of the grooved texture has a more significant effect on the particle emission and wear behaviour of the brake disc. Additionally, the brake disc with 6 grooves, as well as the angle of the grooves face the friction direction, exhibits the best comprehensive performance.

The Influence of Boron Carbide on the Mechanical Properties and Bonding Strength of B4C/Nickel 63 Coatings of Brake Disc

Metal-based ceramic composite laser cladding offers substantial compensations in enhancing brake disc surface characteristics. Laser cladding was utilized to combine B4C powder (10–40%) with Ni 63 powder to make Boron Carbide (B4C)/Nickel 63 composite coatings. For the subsequent experiments, the specimens were ground and polished. Bonding strength, fracture toughness, and residual stress were examined with the B4C content. The fracture morphologies were checked using a scanning electron microscope (SEM). It was observed that the bonding strength of various coatings might approach 175 MPa. Best bonding was observed when the B4C level was between 15% and 30%. The porousness of the coating continuously raised as B4C content increased. The coating’s maximum permeability was 5.6% after the B4C level reached 30%. As the B4C level in the coating grew, the coating’s compression resistance decreased. The bonding strength was within desirable limits, and compression resistance was consistently strong. The material bending strength increased when the B4C materials were reduced below 35%; at this level, the bending strength was highest. The bending strength was covered by the optimal range of bonding strength. Good bonding strength and mechanical characteristics were achieved when B4C content was 20% to 30%. The 20% B4C coating had the smoothest fracture morphologies and the strongest bonding strength, making it the most stable. For the estimation of total matrix deformation and corresponding coating stress on coated brake discs, Ansys software was utilized to create a static structural model.

An Analysis of the Coupling Between Temperature and Thermal Stress of Disc Brakes Based on Finite Element

Disc brakes have been more widely used in recent years due to its many merits such as fast heat absorption and dissipation, and resistance to water fade. Since it’s difficult to describe the failure of brakes under complex working conditions in only a few times of thermal-structural coupling simulations, this paper analyzed the coupling between temperature and thermal stress of disc brakes under multiple continuous braking conditions. At first, a 3D model of bus disc brake was built in ABAQUS, and its braking motion and dynamic parameters, heat flux density, convective heat dissipation coefficient, heat flux distribution coefficient, and other thermodynamic parameters were calculated. Then, the numerical simulation of the temperature field of disc brake and the coupling analysis of thermal stress under different braking conditions were completed. At last, experimental results gave the analysis results of the temperature distribution characteristics of brake disc surface, and the comparison and demonstration of the finite element analysis were conducted.

Study on the Ice-Coated Brake Disc for EMUs Based on Force Coupling

Based on the abnormal wear of the brake disc of Electrical Multiple Units (EMUs), considering the ice-coated friction pair, the finite element (FE) models of the brake disc, the friction blocks and ice impurity were established in ANSYS to explore the stress characteristics of the brake disc. For the ice-coated model, it is found that the maximum equivalent stress is 956.75MPa under the condition of pad stress of 25kN and initial braking speed of 250 km/h. The value of the maximum stress on brake disc surface decreased by 400MPa while removing the ice impurity. The maximum Z-displacement on the ice-coated disc is nearly 4.7mm, and with the contact point farther away, the smaller the deformation will be. The overall trend of the equivalent stress and Z-displacement of the brake disc increases with the braking pressure increasing. Droplet-like frictional blocks can improve the maximum stress and Z-displacement of the disc. Therefore, it is suggested that droplet -like frictional blocks are used for the braking equipment. For improving abnormal wear of the brake disc in extremely cold and snow environment, the analysis provides important reference and theoretical basis for engineering.

Effect of Vibration on Emergency Braking Tribological Behaviors of Brake Shoe of Deep Coal Mine Hoist

The effects of vibration on the emergency braking tribological behaviors of the brake shoe of a deep coal mine hoist were investigated in this study. The thermal, frictional and mechanical parameters of the brake shoe were obtained. The vibration characteristics of the brake shoe during emergency braking were investigated, employing multibody dynamics analysis. The effect of vibration on the emergency braking tribological behaviors (temperature and stress distributions) of brake interfaces was explored using the finite element method. The self-made tribo-brake test rig of a brake shoe was employed to reveal the friction deterioration behaviors of the brake shoe during emergency braking. The results show obvious vibrations of all brake shoes along the direction of positive braking pressure during emergency braking. The vibration causes increases in the equivalent Von Mises stress and temperature at the contact interfaces between the brake disc and the brake shoe as compared to the case of ignoring the vibration. Along the rotation direction of the brake disc, the equivalent stress and temperature of the brake disc surface present three overall rapid increases, as well as two slight decreases during emergency braking. As compared to cyclic emergency braking, continuous emergency braking exhibits more obvious tribological degradation of the brake shoe, attributed to enhanced vibration. The wear loss of the brake shoe increases with increasing emergency braking cycles and continuous emergency braking time.

Optimal location of brake pad for reduction of temperature deviation on brake disc during high-energy braking

During the braking process, frictional heat generated between a disc and a pad can lead to high temperatures. The location of friction blocks on the brake pad can lead directly to differences in friction contact time and friction speed at each point on the brake disc surface, this can lead to non-uniform temperature distribution on the brake disc surface. In this paper, the optimum design for friction blocks on a brake pad is investigated using the design of experiments (DOE) of Taguchi approach and response surface method (RSM) with an aim to minimize the deviation in the rate of friction heating in each area along the radial direction of brake disc. 18 design variables on 2 levels are adjusted. A table of orthogonal arrays, L32 (218), is used. Finite element analysis (FEA) is performed to analyze the mean squared error (MSE) values in the temperature deviations from frictional heat, the disc’s thermo-mechanical characteristics are taken into account. Analysis of variance (ANOVA) is carried out using the data gathered from the DOE stage, we find 7 significant factors among the design variables. A meta-model using RSM is proposed for reduction of temperature deviations over the brake disc. An optimized brake pad is analyzed in terms of the temperature and thermal stress imparted on the brake disc, this optimized pad is then compared with the original pad. The maximum temperatures of the optimized pad and original pad were 399.8 °C and 480.6 °C, respectively. The thermal stress of the optimized pad and original pad were 640.4 MPa and 721.4 MPa, respectively. In the optimized model, the size of the hot band on the disc is larger than that from the original model, so the thermal stress distribution on the disc is smaller. Finally, the optimized pad was found to give significant performance benefits with a 16.8 % decrease in maximum temperature and 11.2 % decrease in thermal stress.

ВЛИЯНИЕ НАПРЯЖЕННОГО СОСТОЯНИЯ ТОРМОЗНОГО ДИСКА НА ПАРАМЕТРЫ МИКРОГЕОМЕТРИИ ЕГО ПОВЕРХНОСТИ, НАХОДЯЩЕЙСЯ ВНЕ ОБЛАСТИ КОНТАКТА

The paper shows results of the study dedicated to influence of contact area stress state on a trend of changes for roughness and waviness parameters of brake disc surface located on the periphery of contact with a brake pad in the coverage area of preferred compression and tensile stresses. It also displays that the main trend of surface deformation under the influence of growing mechanical compression stresses consists in increase of altitude and decrease of step parameters of roughness and waviness. The authors have established that in the coverage area of tensile stresses the roughness and the waviness of the brake disk surface returns to initial values determined in condition of absence of external power influence. On the basis of the results, the authors have explained the process of waviness appearance on the brake disc surface. Results of the study are recommended for the application at solving tasks on friction and wear.

Research on the Temperature Law of Brake Disc Based on Friction

The temperature characteristics of the brake disc will affect the material properties and stress characteristics and affect the safe operation of the train. In order to study the temperature distribution of the brake disc during the operation, a three-dimensional finite element contact model of the brake disc and the brake pad was established by software ABAQUS, applying the initial braking speed of 80 km/h. By analyzing the simulation results, it is found that in the process of the braking, the friction between the brake pad and the brake disc surface causes the temperature rising and forms a high-temperature zone in the middle of the brake disc surface. The temperature of the node belonging to the high temperature zone on the brake disc surface increases first and then decreases. The temperature of the brake disc along the axial direction decreases, and the temperature of the back of the disc increases continuously during the braking process.

Investigation of tribological behavior of 20NiCrBSi-WC12Co coated brake disc by HVOF method

In braking systems, which consist of dry sliding lining against a pearlitic cast-iron disc, disc wear has a significant impact on the overall wear rate. In this work, dynamometer tests were conducted to find out the friction and wear behaviour of 20NiCrBSi-WC12Co cermet coating accumulated on the cast-iron disc by High velocity oxy-fuel spraying (HVOF) and the findings were compared with those of the uncoated disc. Braking tests of the coated and uncoated discs were performed on a full-scale brake dynamometer, which was designed in line with the SAE-J2430 Brake Effectiveness Procedure. Microhardness values, surface properties, scanning electron microscopy (SEM) analysis, energy dispersive x-ray (EDX) and x-ray diffraction (XRD) analysis of the discs were evaluated. As a result of these analyses, it was found out that cermet coating had a much higher microhardness and abrasion resistance with the combination of hard WC phase and mild Ni matrix compared to the conventional disc. The coated disc exhibited stable braking effectiveness with lower surface contact temperature. At the same time, this coating results in longer service life by reducing abrasive wear on the brake disc surface and a lower lining wear rate, reducing particle matter emissions to the environment.

Study on Laser Cladding Preparation of Bionic Surface of Cast Iron Brake Disc

The shellfish in nature was taken as the biological model, and the coupling design was carried out on the surface of grey cast iron. With the help of advanced laser cladding technology, the unit body was prepared on the surface of grey cast iron, so as to obtain the bionic samples of grey cast iron with high wear resistance and fatigue resistance. The composition, hardness distribution, morphology and phase of the unit were analyzed by micro-hardness tester, scanning electron microscopy (SEM) and XRD. Thermal fatigue test and friction and wear test were carried out on bionic and untreated grey cast iron samples. The effects on fatigue resistance and wear resistance of bionic laser cladding and grey cast iron were studied by comparing the experimental results. It was found that the laser cladding has a compact structure and a metallurgical bond with the substrate. The hardness of the unit is 2 times of that of the grey cast iron substrate. The thermal fatigue resistance of the material is improved by bionic laser cladding. The bionic laser cladding preparation can greatly improve the wear resistance of materials.

High temperature wear performance of laser cladding Co06 coating on high-speed train brake disc

Abnormal wear sometimes occurs on the high speed train brake disc surface in winter time. In this paper, Co-based alloy powders were deposited by laser cladding technology to improve the wear resistance of train brake discs. Sliding wear at room temperature, 200 °C, 400 °C and 600 °C were conducted to investigate the wear behavior. Microstructure, hardness, and phase composition of Co06 cladding layers were also studied. The results showed that Co06 cladding layer exhibited better wear resistance than the substrate, with different wear mechanisms at high temperatures. Co06 cladding layers also exhibited better high temperature oxidation resistance than the substrate. Cr23C6 played a significant role in anti-friction.

Design, Development and FE Thermal Analysis of a Radially Grooved Brake Disc Developed through Direct Metal Laser Sintering.

The present research work analyzed the effect of design modification with radial grooves on disc brake performance and its thermal behavior by using additive manufacturing based 3D printed material maraging steel. Temperature distribution across the disc surface was estimated with different boundary conditions such as rotor speed, braking pressure, and braking time. Design modification and number of radial grooves were decided based on existing dimensions. Radial grooves were incorporated on disc surface through Direct Metal Laser Sintering (DMLS) process to increase surface area for maximum heat dissipation and reduce the stresses induced during braking process. The radial grooves act as a cooling channels which provides an effective means of cooling the disc surface which is under severe condition of sudden fall and rise of temperatures during running conditions. ANSYS software is used for transient structural and thermal analysis to investigate the variations in temperatures profile across the disc with induced heat flux. FE based thermo-structural analysis was done to determine thermal strains induced in disc due to sudden temperature fluctuations. The maximum temperature and Von Mises stress in disc brake without grooves on disc surface were observed which can severely affect thermal fatigue and rupture brake disc surface. It was been observed by incorporating the radial grooves that the disc brake surface is thermally stable. Experimental results are in good agreement with FE thermal analysis. DMLS provides easy fabrication of disc brake with radial grooves and enhancement of disc brake performance at higher speeds and temperatures. Therefore, DMLS provides an effective means of implementing product development technology.

EVALUATION OF THE HOMOGENEITY OF THE WORKING SURFACE OF CAST IRON BRAKE DISCS

This article deals with the one of the most important elements of modern braking systems, which is a brake disc. A brake disc is the one of more stressed parts of the braking system, and its quality and design largely determine the braking performance of the vehicle. The article describes the technology of manufacturing disc brake pads that is important from the point of view of the wear processes occurring between two friction surfaces: the brake disc and the brake pad lining. The research of the cast iron ventilated brake disc surface measured the values of the selected roughness parameters at this site. In the context of measurements, it was also determined to be able to maintain a certain value of selected geometric parameters at a given location for the group of brake discs tested of a specific type and manufactured by a particular manufacturer. The work was carried out in the aspect of the research to create a surface layer to protect the brake discs from the effects of corrosive wear.