Brake Disc Temperature Research Articles

Conversion of images of 3D friction maps to study the coupling between coefficient of friction, velocity and contact temperature of the disc brake

The coefficient of friction during braking is not constant. Determining its variability requires measurements in real conditions. This paper presents a methodology of conversion of the measured time profiles of the sliding velocity Veq, contact temperature T, and coefficient of friction f, into analytical formulation of two variables z = f(x,y). This was executed in the following steps: 1) creating a three-column table Veq, T, f from experimental measurements; 2) interpolation using Kriging; 3) creating a contour map of the coefficient of friction dependent on the sliding velocity and temperature, 4) import of a grey scale image of the friction map into the finite element (FE) software, and 5) definition of a function z = f(x,y). The studies were carried out for five composite organic friction materials and cast-iron brake disc of a railway vehicle. The developed five friction maps for each friction pair were based the data from the full-scale bench tests during braking from the initial vehicle velocity of 80 kmh−1, 120 kmh−1, 140 kmh−1, 160 kmh−1, 200 kmh−1 to a stop. In the second part of the study the initial-value problem for the equation of motion combined with the heat conduction problem were formulated and solved numerically using special functionalities of the FE software, e.g. Deformed Geometry, Mathematics. Changes in the vehicle velocity and time profiles of the coefficient of friction were determined from the solution of the coupled thermal problem. The computational FE model was verified by comparing the measured and calculated changes in the vehicle velocity, coefficient of friction and evolutions of the brake disc temperature during single braking. The maximum calculated temperature 1 mm under the contact surface of the brake disc, during braking from initial vehicle velocity of 80 kmh−1, was obtained for the base friction material and was equal to T1,3,5Num.= 72 °C. The corresponding experimental value was T1-6Exp.= 66.1 °C. When braking from 140 kmh−1, for the same material it was T1,3,5Num.= 129.7 °C and T1-6Exp.= 130.7 °C. The obtained differences in braking times calculated and measured did not exceed 1.7 %. The corresponding temperature differences of the disc at the stopping time were lower than 5.5 %.

ANALYSIS OF THE BRAKE CALIPER POSITIONING IN VEHICLES

This paper aims to analyze the positioning of the brake caliper on vehicles, considering the most common situations, namely in front of or behind the brake disc. The positioning of the brake caliper on cars depends on the design and configuration of the brake system specific to each vehicle model. This positioning is determined by the engineers and designers responsible for the vehicle's safety, considering factors such as chassis geometry, weight distribution, desired braking performance, and other relevant technical factors. Generally, the brake caliper is located near the brake disc so that it can apply the necessary pressure to efficiently stop the wheels. Typically, in the case of disc brake systems, the brake caliper is positioned in front of the wheel, near the brake disc. There are cases where the positioning is behind the disc. Starting from this controversy, we considered it opportune to analyze the two cases on a stand that replicates the brake system. Thus, the two situations were analyzed using pressures of 2, 4, and 6 bars in the brake pipe. The variations in brake disc temperatures and braking distances were determined for each case to conclude the positioning of the caliper. The decision regarding the placement of the brake caliper in front of or behind the wheel is made by the vehicle manufacturer based on technical specifications and the desired performance of the brake system.

Tyre and brake thermal management in NASCAR

The need to manage race car tyres is routine faire and several academic papers have already appeared on this topic. We contribute to this literature with refined tyre grip and wear-rate models. Less well known is a methodology for managing the thermal transients in the car's braking system. This knowledge gap is addressed with a physically-based disc-and-calliper brake-heating model. The parameters in each of the models are optimised against measurement data captured on an instrumented Generation 7 (Gen 7) NASCAR driven on the Darlington speedway. These models are replicated on each corner of the vehicle. The remainder of the paper is directed to studying the minimum lap time performance of a Gen 7 NASCAR that is subject to tyre wear and temperature variations; brake heating influences are emphasised. Due to their novelty, the results focus on the performance impact of temperature variations and constraints on the front brake disc temperatures. Constraints on the brake temperatures are introduced to protect the brakes from fade and thermally-induced damage.

Measurement and Analysis of Brake and Tyre Particle Emissions from Automotive Series Components for High-Load Driving Tests on a Wheel and Suspension Test Bed

A current challenge in realising clean road transport is non-exhaust emissions. Important advances regarding measurement systems, including well-defined characterisation techniques, as well as regulation, will be made in the next few years. In this work, we present the detailed results of particle emission analyses, consisting of aerosol (size distribution, particle number (PN), and mass (PM)) and electron microscopy (EM) measurements, under different load conditions on a test bed for a wheel suspension and brakes. Standard tyres and brakes from serial production were tested with a high-load driving cycle, while particle measurements were conducted by gravimetric measurements and with a TSI SMPS, a TSI APS, and a GRIMM OPS. Furthermore, samples were analysed by electron microscopy. A bimodal particle size distribution (PSD) was obtained with an SMPS, with peaks at 20 nm and around 400 nm. The results of an EM analysis of >1400 single particles from the electrostatic sampler match the PSD results. The EM analysis also showed ultrafine particles, mainly containing O, Fe, Si, Ba, Mg, and S, and also fractal particles with high-C fractions. Our results suggest, in agreement with the previously published literature, that particulate emissions are related to the brake disc temperature and occur in significant amounts above a threshold temperature.

An Improved Semi-Transient Brake Cooling Simulation Method

<div>In this article, an improved brake cooling simulation method is introduced. By this method, the vehicle parameters, such as weight, height of the center of gravity, wheelbase, and the like can be included to calculate the braking thermal load under different operating conditions. The effect of the brake kinetic energy regeneration (BKER) on the braking thermal load can also be calculated by this method. The calculated braking thermal load is then input to a coupled 3D simulation model to conduct flow and thermal simulation to calculate brake disc temperature. It is demonstrated that by this simulation method, the difference between the brake disc temperatures obtained from simulation and vehicle test can be controlled below 5%.</div>

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.

A Co-Simulation Platform with Tire and Brake Thermal Model for the Analysis and Reproduction of Blanking

In the world of motorsports engineering, improving brake performance is a crucial goal. One significant factor that affects this performance is the increase in brake disc temperature due to reduced cooling airflow, a phenomenon called “blanking”. This temperature increase also impacts the rim and the air inside the tire, causing changes in tire temperature and pressure, which affects the vehicle’s performance. Properly adjusting the brake blanking can be essential to keep the tire running at the right temperature, resulting in maximization of the performance on track. To address this complex problem, this study describes the problem of cooling brake discs, and this problem is then used as an opportunity to introduce a new variable in order to optimize the performance of the vehicle. By changing the thermal evolution of the brake disc, through the blanking, it can change a large percentage of heat that heats the tire. When combining an existing brake model in the literature with a tire thermal model in a co-platform simulation, it was seen that it is possible to work these two models together with the aim of being able to obtain the prediction of the optimal blanking value to be adopted before proceeding on track, thus saving time and costs.

Development of Sensor for the Real-time Monitoring of Brake Pad Wear and Brake Disc Temperature in High Temperature

Development of Sensor for the Real-time Monitoring of Brake Pad Wear and Brake Disc Temperature in High Temperature

Simulated and experimental study on the relationship between coefficient of friction and temperature of aluminum-based brake disc

PurposeThis study aims to clarify the relationship between the coefficient of friction (COF) and temperature of aluminum-based brake discs.Design/methodology/approachThree friction blocks with different COFs are examined by a TM-I-type reduced-scale inertial braking dynamometer. On this basis, the thermo-mechanically coupled model of friction pairs is established to study the evolution of brake disc temperature under different COFs using ADINA software.FindingsResults indicate that the calculated disc temperature field matches the experimental well. The effect of COF on the peak temperature is magnified by the braking speed. With the COF increasing, the rise rate of instantaneous peak temperature is accelerated, and the dynamic equilibrium period and cooling-down period are observed in advance. The increase in COF promotes the area ratio of the high-temperature zone and the maximum radial temperature difference. When the COF is increased from 0.245 to 0.359 and 0.434 at 140 km/h, the area ratio of high-temperature zone increases from 12% to 44% and 49% and the maximum radial temperature difference increases from 56°C to 75°C and 83°C. The sensitiveness of the axial temperature difference to the COF is related to the braking time. The maximum axial temperature difference increases with COF in the early stages of braking, while it is hardly sensitive to the COF in the later stages of braking.Originality/valueThe effect of COF on the aluminum-based brake disc temperature is revealed, providing a theoretical reference for the popularization of aluminum-based brake discs and the selection of matching brake pads.

The Influence of Adding Copper and Iron Third Body on Brake Disc Temperature

The Influence of Adding Copper and Iron Third Body on Brake Disc Temperature

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%.

Thermal Simulation of Ventilated Brake Disc Based on Complex Multifield Coupled Method

In this article, considering the coupled interaction of heat, stress, material wear, and wheel–rail force transmission in the disc-braking process, a complex multifield coupled method was proposed to study thermal mechanical properties and contact state of brake discs. First, a coupled dynamic model of train, track, and brake gear was established to analyze the force transmission between brake friction pairs and wheel–rail system. Based on the coupled dynamics simulation results, a thermomechanical wear coupled model of the friction pair was established. It is found that the track irregularity results in vertical relative displacements with a range of (–2.6 mm, 2.8 mm) and makes the maximum brake force increase to 24.1 kN. As a comparison, brake bench tests without wheel–rail interaction were carried out. This showed that there was no vertical relative displacement between the friction pair, and the braking force had a stable value of 22.5 kN. The simulation results of the brake disc temperature distribution, and the friction pair contact state are consistent with the bench test results. In addition, different thermal simulation methods of the brake disc were used to verify the validity of the complex multifield coupled simulation results.

Study of friction, wear and plastic deformation of automotive brake disc subjected to thermo-mechanical fatigue

The function of the automotive braking system is to reduce the vehicle’s speed or stop within a stipulated time. An efficient braking system dissipates all heat generated during braking into the environment before subsequent braking is applied. The heating and cooling cycles, in combination with mechanical loads during braking operation, cause thermal stresses on the surface of the brake disc. The resulting thermomechanical fatigue (TMF) on the brake disc is a life-limiting factor and causes failure. Understanding their impact, given experimental investigation using a full-scale inertia brake dynamometer is the paramount aspect. The reference disc, that is used for the experiment is a wheel-mounted brake disc. During the investigation, it is observed that (i) friction coefficient is sensitive to vehicle speed and braking pressure (ii) fade test records a maximum brake disc temperature of 403°C (iii) repeated thermal and mechanical cycles induced plastic deformation and cracks on the brake disc. The study provides insight into the parameters contributing to the damage at the friction surface of the brake disc that is subjected to Thermo Mechanical Fatigue (TMF).

Analytical Modeling of Heat Transfer Coefficient Analysis in Dimensionless Number of an Electric Parking Brake Using CFD

The present study intends the development of an electric parking brake (EPB) for commercial vehicles (CVs). CVs with EPB applications are currently available in an entirely different set of issues than EPB applications on passenger cars, which are presently widely used. Safe parking requires much more focus with an order of magnitude, more thermal capacity, brake mass, and clamp pressures. In the first instance, heat loss from the brake disc was estimated. The investigations also allowed for precise prediction of radiative heat loss by defining surface emissivity. The parameters of air movement, convective heat transfer coefficients, and velocities were investigated, and validation was done with the CFD model. When the temperature dropped to 252 °C, the maximum estimated value of the Nusselt number was 72.25. Nusselt number pattern that looks identical over the arc surface yields 13.38 percent better results. Nu values at maximum temperature were calculated to be 80.5 and 82.6 at 251.8 °C. The “hconv” value was 4.1 percent lower than in the arc region, with the highest value at 400°C being 11.5 W/m2K. The present study adopted unique approach and obtained brake disc temperature and the coefficient of convective heat transfer on disc friction surfaces and hat regions. CFD modeling was done during the cooling phase to evaluate flow patterns and “hconv” fluctuation across the entire disc brake surface area. The mathematical modeling and adopted methodology for computing heat transfer coefficients for different disc regions have helped to better understand of a CV brake disc heat dissipation.

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.

Simulation Analysis and Verification 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.

Thermal-mechanical coupling analysis and optimization of mine hoist brake disc

Based on heat conduction theory and energy conversion, the theoretical model of brake disc temperature field was established. The temperature field and equivalent Von Mises stress field distribution of brake disc during braking were investigated by using the finite element (FE) analysis. According to the thermal-mechanical coupling analysis, orthogonal optimization and analysis of variance (ANOVA) were used to optimize brake for reducing Von Mises stress on the brake disc. Results show that the temperature of a friction surface is high in the middle and low on both sides, with a large temperature gradient. In addition, the temperature and Von Mises stress form two extreme points in a direction of the friction surface circumference. Temperature and stress values decrease slowly along the direction of a brake disc rotation from an extreme value point, and decrease faster in the opposite direction. The maximum temperature of the optimized brake during braking is 473 K and the maximum equivalent Von Mises stress is 264 MPa. The main objective of this work is to reveal the influence of brake shoes structure and material on thermal-mechanical coupling of the brake disc to ensure famous strength that guarantees a longer life.

Integrated simulation platform for a locomotive braking system

We used a locomotive and a rail car to examine the working principle of a locomotive braking system. We established models of the locomotive braking system, the locomotive dynamics, and the brake disc thermodynamics and, based on the correlation parameters for each subsystem, built an integrated simulation platform for the locomotive braking system based on Simulink and AMESim. Using this platform, we simulated the characteristics of the pneumatic braking unit, the locomotive braking, and temperature increase in the brake disc under emergency braking conditions. We compared our simulation results with experimental data and the results showed that the integrated simulation platform for the locomotive braking system could successfully be used to study locomotive braking control on the vehicle level. We provide a design optimization method for the development of a braking system, the setting of the anti-skid criterion, and early warning of an increase in the brake disc temperature.

Studies on Enhanced Brake Disc Cooling using Wheel Rim with Axial Ventilators

The purpose of this study is to improve the cooling of brake disc by modifying the wheel rim by fitting it with an axial ventilator. The orientation angle of these blades in axial ventilator is varied between 0 and 10. The numerical investigation is carried out using commercial CFD code ANSYS Fluent. The pressure difference induced in 5 model is maximum leading to a better air flow through the wheel rim resulting with enhanced cooling of the brake disc. The 5 model reduced the brake disc temperature from 450C to 207.84C which is nearly 54%. The surface heat transfer coefficient and Nusselt number of 5 model is found to be maximum. The resulting improvement in heat dissipation enhances the performance and hence the lifetime of the brake disc. Therefore, the wheel rim with axial ventilator 5 model is found to the suitable configuration so as to achieve enhanced convective cooling of brake disc.

Investigation of tribological characteristics of brake pairs elements of mobile machine

The subject of the experiments was the tribological properties of typical brake pads and disc characteristics. For the experiment was used Grey Cast Iron brake disc and semi metallic, low steel quantity and ceramic brake pads. The breaking process was imitated. The experiment was conducted at 0.75, 1.25 and 1.76 m/s sliding speed using 0.85 MPa contact pressure. The experiments lasted 10 minutes. The results of the experiments showed that best tribological characteristics have ceramic brake pads, despite the fact that brake disc temperature rapidly increase the with ceramic brake pads, but the friction coefficient (and braking torque) was the best. Semi metallic and low steel braking pads had very similar friction coefficient values, but wear and disc temperature values were more dissimila