Browse Topic: Brake components

Items (2,128)
S-cam brake is a drum-type foundation brake used in heavy commercial vehicles. It is a safety-critical device; hence, thorough validation of its performance by lab test rigs and field tests is essential. During prototype testing, an unusual impact was observed during dynamic braking at high pressure application, specifically when the brake drum is rotating, after a period of operation of about 10,000 cycles. This phenomenon was then observed even at static braking when the brake drum was at rest. From initial inspection, it is due to the cam roller, which rides on the web-slot provided at the shoe assembly, while the S-cam is rotating and falls back instantly. This phenomenon occurs repeatedly and creates an audible noise, which needs to be eliminated. The study aims to correlate the phenomenon using finite element analysis (FEA) as in a prototype test and to identify the root cause and optimize the design variables. Since the friction coefficient at the cam roller–web interface is unknown after a period of operation, different values of friction coefficient, ranging from 0.1 to 0.8, are iterated and simulated by rotating the S-cam until the braking effort is reached. The dynamic implicit analysis procedure in Abaqus standard is used to simulate this condition. Based on the results, design variables were improved to mitigate the issue. A quick solution, achieved by modifying a minor feature, successfully prevented the fallback behavior and was validated through physical testing. Furthermore, a permanent solution was developed to eliminate both the “ride-on” and “fallback” phenomena by optimizing component dimensions. This FEA methodology helps to validate the design in an initial concept phase itself for future variants. Using this method, even the structural and fatigue performance of braking parts can be validated at a system-level simulation with better accuracy.
Dinesh Kumar, J.Riyaz Mohamed, D.Vasanth Bharath, S.Rajkumar, S.Murugan, S.
In conventional braking systems, the kinetic energy of a vehicle is predominantly converted into heat through friction, a thermodynamically inefficient process. This not only causes progressive wear of components but also leads to the release of various materials, including heavy metals and organic compounds. With increasing concern over non-exhaust emissions, the search for innovative solutions becomes imperative. In electrified vehicles (xEVs), regenerative braking emerges as a strategic technology, converting kinetic energy into electrical energy to recharge the battery and extend range. This process not only enhances the vehicle's energy efficiency but also results in reduced frequency and intensity of mechanical brake usage. Consequently, there is a direct reduction in the wear of friction braking components, which translates into a significant mitigation of particulate matter emissions associated with this wear. The optimization of these systems occurs through Cooperative Regenerative Braking (CRB), which intelligently integrates with hydraulic braking. The primary challenge lies in managing the transition between modes to recover maximum energy without compromising safety and driver comfort. This technical paper explores how CRB employs 'torque blending' via advanced ECUs and software to adjust in real-time the proportion of each braking type, aiming for maximum energy recovery in diverse driving scenarios. To verify the effectiveness of this system, practical tests were conducted on a vehicle. The results obtained from these tests were conclusive, demonstrating significant gains in energy efficiency, with an increased battery recharging capacity during decelerations, optimized by the braking system. This improvement in efficiency directly impacts the reduction in the use of the conventional friction brake system and, consequently, a sharp decrease in particulate matter emissions. In this context, the intelligent and cooperative management of regenerative braking is a strategic and fundamental component for building a more sustainable future in vehicular mobility.
Batagini, EmersonRomão, Bruno
This study investigates the influence of wheel structural stiffness and wheel configuration (single- and dual-tire) on brake drum deformation in commercial vehicles equipped with pneumatically actuated drum brakes. A comprehensive multi-method approach was adopted, combining on-vehicle measurements, controlled bench testing using two- and three-dimensional optical metrology, and Finite Element Analysis (FEA) of the rear axle assembly. Three- wheel configurations were evaluated: a dual-tire arrangement (Configuration A) and two single-tire designs with distinct stiffness characteristics (Configurations B and C). Radial distortion was quantified using the displacement difference between the bottom and top regions of the brake drum (ΔZ). The results demonstrate that wheel stiffness and the offset between the wheel-disc attachment point and the ground reaction force are dominant factors governing brake drum deformation. The brake drum equipped with dual-tire configurations exhibited minimal ΔZ, whereas the brake drums equipped with single-tire configurations, particularly the least stiff Configuration C, showed pronounced outward radial displacement and increased deformation asymmetry. Design evaluations conducted under the worst-case configuration confirmed these findings, showing an effective reduction in brake drum deformation achieved by increasing the brake drum collar thickness (–36.1%; +6 kg) and by increasing the wheel rim thickness (–27.8%; +4.5 kg).
de Souza, Cassio Belo ClementeSantana, Flávio ArcanjoHenze, SteffenPulju, HendrikFilho, William Manjud Maluf
During the development of mechanical components, engineers use numerical tools as a first step to design, develop, and analyze potential solutions for specific requirements, thereby reducing time- to-market of new components. Furthermore, numerical tools are also highly useful for analyzing components that exhibit failures. For brake discs, numerical analysis must consider not only mechanical behavior but also thermal and fluid dynamic behavior. In this context, as a further step, experimental tests can be performed in test facilities such as dynamometers, where the brake discs are evaluated under different operating conditions to determine their susceptibility to failures such as thermal distortion, judder (hot or cold), squeal, coning, etc. If such failures occur, corrective actions can be implemented using different approaches: a) redesign of the disc and braking system aided by numerical tools; b) tuning of the matching between disc and pad materials; and c) modification of the disc and/or the pad material. Regarding the first approach, the finite element method (FEM) is one of the most important numerical tools, and to obtain reliable results, accurate boundary conditions must be applied. The aim of the study is to demonstrate the feasibility of the CFD-thermal-structural boundary conditions derived from an experimental test performed on a ventilated brake disc assembled in an instrumented vehicle. Firstly, a comparison between an analytical method and the CFD solution was made regarding convective heat transfer coefficient (HTC). The test consisted of 16 main braking cycles from 140 to 0 km/h, conducted under eight different pedal pressure levels. After each main braking, a thermal shock was applied to the disc using water, followed by a secondary braking from 80 to 0 km/h, always with the same pedal pressure. The numerical analysis results showed good agreement with experimental tests in terms of temperature distribution. In addition, axial displacement distribution along the circumference is presented, with emphasis on coning deformation, one of the main triggers for judder.
Bagatini, Pablo SchettertViotti, Matias RobertoPereira, LeonardoTuzzin, MatheusTitton, Angelo PradellaBoaretto, JoelDe Leon, Daniel Milbrath
The development of copper-free brake pads poses a significant challenge because copper plays a critical role in tribofilm formation and friction stability. This study proposes a novel approach using a recycled flake iron oxide material, characterized by high thermal stability and a unique plate-like morphology, as a sustainable alternative. The material acts as a friction modifier, promoting the formation of stable tribofilms and serving either as a copper substitute or a functional additive. Its iron-oxide composition ensures strong compatibility with the counterface tribofilm, enhancing adhesive friction, while its role as a primary plateau contributes to friction stability and reduced wear. Three application scenarios were investigated: (i) copper substitution in Low-Steel (LS) and Non-Asbestos Organic (NAO) formulations, (ii) partial replacement of steel fibers in copper-free LS formulations, and (iii) synergistic use with iron sulfide in copper-free NAO formulations. Tribological performance was evaluated using a tribometer, and worn surfaces were analyzed by SEM and EDS to characterize tribofilm formation. Results demonstrate that the proposed material provides friction stability and wear resistance comparable to copper in both LS and NAO formulations. Partial substitution of steel fibers improved wear resistance by up to 75%, while synergistic addition with iron sulfide further enhanced friction and wear performance in copper-free NAO pads. These findings highlight the potential of this recycled material as a sustainable and effective alternative for copper-free brake pads, offering both environmental benefits and high tribological performance while reducing reliance on critical raw materials.
Jara, Diego ChávezLorenzana, Carlos
Embedded electronics are becoming increasingly common in solutions developed for commercial vehicles. Technological advancements enabled the development of electronic solutions that provide braking systems with functions to improve safety, comfort, performance, durability, and cost-effectiveness of wear components. In this context, the electronic braking system, EBS, has become increasingly present in the electronic architecture of commercial vehicles. Considering the functions that can be developed within the electronic braking system, the following stand out: the pedal characterization, which potentially improves comfort and increases the sensation of safety during braking; and the brake force distribution, which can be adjusted to ensure that the vehicle achieves an optimal balance between performance and friction material’s durability. This work consists of the presentation of tests and results of technical activities required to develop an EBS for medium-heavy and heavy-duty vehicles designed for a variety of applications. EBS was developed to prioritize comfort and safety, with optimized braking sensation and performance without compromising the durability of the wear components of the vehicles. Activities started with the experimental determination of the brake factor—a value that transmits to EBS the braking capacity of the truck. In sequence, brake pedal setup was performed based on data extracted from a vehicle equipped with a mechanical braking system and validated by subjective assessment. In addition, the braking force distribution definition started by establishing its target: friction material’s wear equalization or braking performance; went through balancing the mechanical braking power per axle; and finished being validated by data obtained from vehicles in use. Results showed that the implementation of electronic braking systems in commercial vehicles brought several benefits to the product, in particular, improvement of braking feeling when pressing the brake pedal, and in both braking performance and friction material’s durability, which resulted in a better balance between maintenance costs and technical advantages.
Travaglia, Carlos A. P.Rodrigues, AndréRudek, ClaudemirDias, Eduardo MirandaSilveira, Juliana
In this study, five resin-based brake pad samples with modified fly ash contents of 0%, 4%, 8%, 12%, and 16% were prepared to investigate the influence of fly ash content on the comprehensive performance of the friction materials. The tribological properties of all samples were evaluated under temperature conditions ranging from 100 °C to 350 °C, and their overall performance was assessed using five evaluation indices. Based on the AHP-MOORA algorithm, sample F12 exhibited the highest comprehensive weighted score of 0.11, followed by samples F0 and F8 with scores of 0.10 and 0.09, respectively, indicating a slight decline. In contrast, the comprehensive weighted scores of F4 and F16 were relatively low, at 0.05 and −0.01, respectively. Among the five composites, F12 demonstrated the best overall performance, with F0 and F8 ranking next, while F4 and F16 performed poorly. These results suggest that, within a certain range, increasing the fly ash content can enhance the comprehensive properties of the material. However, excessive addition of fly ash may lead to the detachment of harder particles during wear, thereby increasing wear thickness and wear rate.
Li, XiaobiaoHe, KangZhao, ZhuanzheWu, BoSun, Fei
In this study, an efficient method for concurrent thermomechanical performance and weight optimization under modal constraints is proposed to address the coupled design challenges of thermomechanical characteristics (thermal capacity, thermal deformation, and modal) and structural weight in straight-ribbed brake discs. Based on high-fidelity computer-aided engineering (CAE) simulations of brake disc thermomechanical behavior, a neural network (NN)-based surrogate model and a ResNet-guided geometric feature recognition (RGFG) model for automatic modality recognition were developed, and integrated with a particle swarm optimization (PSO) framework for optimal solution exploration. When applied to a passenger vehicle brake disc case study, the surrogate model of NN demonstrates remarkable accuracy: it shows more than 95% agreement with the CAE results in thermal capacity prediction, the prediction accuracy of thermal deformation exceeds 90% compared to CAE results and 83.4% compared to test result, thereby validating the method’s effectiveness. Compared with conventional CAE approaches, the surrogate model of NN achieves a subsecond prediction speed, significantly reducing computational costs. The surrogate model of RGFG achieves a test accuracy exceeding 95%. Furthermore, the proposed optimization framework offers valuable insights for the inverse design of brake discs.
Han, SimiaoJiang, DaxinHan, ChaoWang, JindaSui, Qinghai
The increasing pressure to decarbonize manufacturing systems is pushing industry beyond conventional lightweighting strategies toward material and process paradigms, capable of delivering functional performance with radically lower environmental impact. In this context, polymer-based composite Additive Manufacturing (AM) offers an underexplored yet highly promising pathway for sustainable production of load-bearing components. This study presents a preliminary comparative cradle-to-gate Life Cycle Assessment (LCA) of a Formula SAE brake pedal, assessing the environmental transition from conventional sheet metal fabrication and finishing operations of Aluminum 7075-T6 to additive manufacturing solutions, with specific focus on Carbon-Fiber-Reinforced Polymer (CFRP) composites. Two topology-optimized designs, respectively for Powder Bed Fusion (PBF) in AlSi10Mg and Material Extrusion (MEX) in Polyethylene Terephthalate Glycol with Carbon Fiber (PETG-CF) are compared to conventional fabrication aluminum benchmark. The analysis is integrated in the product and process design following ISO 14040/14044 standards and is implemented using the Environmental Footprint 3.0 methodology within the 3DEXPERIENCE platform. Results outline that Material Extrusion (MEX) composite manufacturing achieves the lowest environmental impact across all evaluated categories. Compared to conventional manufacturing, the PETG-CF solution enables an approximate 50% reduction in Global Warming Potential and an almost complete elimination of mineral depletion. Unlike metal additive manufacturing, which remains constrained by high process energy demand, MEX benefits from low processing temperatures, minimal auxiliary systems, and highly efficient material deposition. Crucially, these sustainability gains are achieved while maintaining functional performance through design-driven topology optimization. AM composite solutions, by merging advanced material science with additive flexibility, may lead to design approaches which cease to be ‘potential’ enablers of sustainable manufacturing for the Industry 5.0 transition.
Dalpadulo, EnricoRusso, MarioApté MD, RaphaëlleLeali, Francesco
This SAE Recommended Practice establishes uniform test procedures for friction based parking brake components used in conjunction with hydraulic service braked vehicles with a gross vehicle weight rating greater than 4500 kg (10 000 lb). The components covered in this document are the primary actuation and the foundation park brake. Various peripheral devices such as application dashboard switches or indicators are not included. These test procedures include the following: a Brake Related Tests 1 Brake Functional Performance 2 Brake Dynamic Torque Performance 3 Brake Corrosion Resistance 4 Brake Endurance with Torque 5 Brake Endurance without Torque 6 Vibration Resistance 7 Brake Ultimate Static Load 8 Brake Lining Wear Adjuster Function b Actuation Related Tests 1 Mechanical Actuator Functional Performance 2 Mechanical Actuator Endurance 3 Mechanical Actuator Quick Release 4 Mechanical Actuator Ultimate Load 5 Spring Apply Actuator Functional Performance 6 Spring Apply Actuator Operating Temperature Range 7 Spring Apply Actuator Endurance 8 Spring Apply Actuator Corrosion Resistance 9 Spring Apply Actuator On-Off Switch 10 Spring Apply Actuator Vibration
Truck and Bus Hydraulic Brake Committee
This study aims to explore and evaluate the effect of various foot positions on the kinematic and kinetic response of the lower extremity during frontal crashes using a realistic vehicle interior. Frontal impact sled tests were performed with the Test Device for Human Occupant Restraint, 50th-percentile Male (THOR-50M) and Test Device for Human Occupant Restraint, 5th-percentile Female (THOR-05F) anthropometric test device (ATD) in the driver’s seat of a midsize SUV testing buck (with realistic interior components including an instrument panel with steering wheel and steering wheel airbag, seat, three-point seat belt with pretensioner and force-limiter, accelerator pedal, brake pedal, knee airbag, and seat belt retractor pretensioner). Six sled tests were performed in two principal directions of force (PDOF) [three each in frontal (0°) and oblique (−20°) configurations]. The right foot was positioned on the accelerator pedal, fully on the brake, and half on the brake. A single test was conducted with the THOR-05F in an oblique configuration with the foot on the accelerator. Ankle response was analyzed from internal ATD instrumentation. Restraint engagement was found to be consistent across all testing cases. Ankle moment and angle varied based on PDOF and the tested foot condition. Right ankle moment ranged from 70 to −70 Nm in inversion/eversion. Right ankle angles ranged from 37° inversion to 28° eversion. Left ankle moment ranged from 10 to −41 Nm in inversion/eversion. Left ankle angles ranged from 10° eversion to 23° inversion. Differences in lower extremity motion and loading were observed for each testing condition. Placing the foot on the accelerator pedal produced greater ankle moment than either brake pedal condition. Placing the foot on the brake pedal resulted in the highest dorsiflexion angle response. Obliquity increased ankle moment and rotation for both ankles. The United States New Car Assessment Program (US-NCAP) foot position with an oblique PDOF created the highest ankle moment while the in-line brake position in oblique created the highest dorsiflexion rotation. By combining these findings with other efforts focused on naturalistic driving and foot positioning, these results might aid in development of additional testing practices that might enhance our understanding of the lower extremity in nonstandard initial positions.
Noss, JuniorDonlon, John-PaulMorris, AnnaSamier, GermainPark, JosephForman, Jason
High thermal loads on brake systems during extended descents followed by vehicle soak pose significant safety and durability risks. Excessive rotor or fluid temperatures can cause loss of braking efficacy, fluid degradation or evaporation, thermal fade, and accelerated component wear. This study uses time-history data of brake-disc and fluid temperatures which were collected during controlled hill-descent events with subsequent soak periods, where the vehicle is parked in a wind protected area. Besides the rotor and brake fluid temperatures, environmental conditions were recorded (ambient temperature, humidity, wind speed and direction) and the vehicle and brake specifications are known (rotor/caliper geometry, pad material, vehicle aerodynamic configuration and mass). 126 test runs from a dedicated vehicle program are used, each providing time-history records that form the basis of our analysis. From these records we extract phase-specific samples (descent and soak phase) and engineer compact descriptors — start and peak temperatures, environmental factors, rolling statistics and contextual metadata to represent each event. We develop and evaluate machine-learning regression and neural-network models to predict the disc and brake-fluid temperatures occurring during the descent and across the soak phase. Cross-validation is done to ensure generalization to unseen descent events. Models are evaluated with mean absolute error (MAE) and bias diagnostics. The predictive models enable early warning of critical temperature spikes and support design and operational decisions (cooling design, allowable profiles and optimization). By delivering fast temperature estimates, they reduce reliance on computationally expensive CFD during early design, while CFD and experiments remain for final validation. We present workflow, model performance and uncertainty characterization.
Poojari, Uday KumarWestphalen, JanVenugopal, Narayana
As the adoption of electric vehicles continues to accelerate, the demand for their development and testing using chassis dynamometers has also increased significantly. Compared with internal combustion engine vehicles, chassis dynamometer testing for electric vehicles typically requires test durations several to several dozen times longer, resulting in substantially increased labor requirements. In addition, low-temperature testing is often required, further intensifying the workload associated with vehicle testing. To address these challenges, this study developed and evaluated a pedal robot designed to enable unmanned and automated testing. The pedal robot developed in this study weighs only 12 kg and can be installed within a few minutes. It is, to the authors’ knowledge, the world’s first pedal robot that mimics human driving behavior by using a single foot to operate both the accelerator and brake pedals. Unlike conventional driving robots, the actuators of the proposed system do not require direct mechanical attachment to the vehicle pedals, allowing for rapid installation. Furthermore, the robot is mounted on the driver-side floor, eliminating the need for attachment to the seat structure. The pedal robot features three degrees of freedom driven by three motors and employs artificial intelligence to recognize the shape and position of pedals across different vehicle models, thereby enabling automated test initiation without manual adjustment. The performance of the pedal robot was evaluated under UDDS, HWFET, and WLTC driving modes, and the results were analyzed in accordance with the SAE J2951 standard. Comparative evaluations demonstrated that the pedal robot achieved superior speed-tracking performance relative to that of an experienced human test driver. The developed pedal robot is currently being utilized for vehicle certification testing of electric and other vehicles at the Mobile Environment Research Center of the National Institute of Environmental Research in Korea. This paper presents a detailed analysis of the corresponding experimental results.
Lee, DaeyupKang, Ji MyeongJo, YechanChoi, SeongUnShin, JaesikKim, JongminKang, Keonwoo
Brake pulsation noise caused by fluid-borne vibration, which is generated by pressure pulsations from the pump in the Electronic Stability Control (ESC) modulator, occurs when the control brake function is activated under various driving conditions, such as Adaptive Cruise Control (ACC) and regenerative-friction brake coordination. This noise is particularly noticeable in Battery Electric Vehicles (BEVs), where the background noise from the power source is lower than that of internal combustion engine vehicles. The simulation of pressure pulsations in the brake system requires the excitation force of the pump built into the ESC modulator, the characteristics of valves, and the characteristics of the flexible hose; however, it is extremely difficult to determine these parameters with high accuracy from the design specifications. For this reason, in this study, the pump and valves were experimentally identified, while the flexible hose was represented by a three-element Voigt model to describe its viscoelastic properties. The pressure pulsation prediction model of the brake line was constructed by formulating the characteristics of all hydraulic components using four-pole matrix equations consisting of pressure, flow rate, and impedance, along with the continuity equation. This paper describes the method for creating a prediction model of pressure pulsation, the measurement results of the transfer matrix of the flexible hose, the modeling and parameter identification method of the flexible hose, and the accuracy verification results from a bench test of a brake system equivalent to an actual vehicle. Since a high-accuracy prediction model has been constructed, by predicting the pressure pulsation at any position in the brake line for any pump rotation speed, it can be utilized for designing the pump rotation speed that achieves both braking performance and brake pulsation noise reduction, and for examining bending and clamp positions of the brake line that avoid the amplification of excitation force.
Koike, YoheiKomada, MasashiYano, MasahiroYoshioka, Nobuhiko
This paper presents research into the inertial displacement of brake pedals and the subsequent activation of brake light switches during crash events. In certain scenarios, such as multiple-impact crashes or crashes with pre-impact interactions such as curb strikes or sideswipes, inertial forces alone may generate sufficient brake pedal movement to trigger the brake switch, activating the brake lights. Such signals may be recorded by an Event Data Recorder (EDR) or observed by witnesses and incorrectly interpreted as an indication of intentional driver braking. To investigate this phenomenon, HYGE sled tests were performed using brake pedal assemblies and associated components from a Toyota Tacoma pickup truck and a Cadillac DeVille passenger sedan. The assemblies were subjected to acceleration pulses simulating a frontal impact, with high-speed video used to capture brake pedal displacement and brake light activation. The tests demonstrated that inertial loading from a pulse with a delta-V (change in velocity) as low as 12 mph could result in momentary brake light activation due to pedal displacement from inertial forces. Increasing the magnitude of the acceleration pulse produced greater displacement of the brake pedal and extended the duration of the brake light activation. An example is presented that demonstrates inertial pedal movement in a full-scale vehicle test conducted by striking a curb, which resulted in brake light activation with a delta-V considerably less than 12 mph. Additionally, a field survey of 50 passenger vehicles found that the brake switch activation threshold ranged from 0.25 to 0.56 inches of pedal travel for 80% of the vehicles measured. These findings indicate that relatively small crash accelerations and durations can produce sufficient inertial pedal movement to activate brake lights and that only minimal pedal displacement is required in most vehicles.
Walker, JamesDuran, AmandaBarnes, DanielOsterhout, AaronClayton, Aidan
The purpose of this SAE Recommended Practice is to establish a uniform laboratory procedure for securing and reporting the friction and wear characteristics of brake linings. The performance data obtained can be used for in-plant quality control by brake lining manufacturers and for the quality assessment of incoming shipments by the purchasers of brake linings.
Brake Linings Standards Committee
This SAE Recommended Practice covers equipment capabilities and the test procedure to quantify and qualify the shear strength between the friction material and backing plate or brake shoe for automotive applications. This SAE Recommended Practice is applicable to: bonded drum brake linings; integrally molded disc brake pads; disc brake pads and backing plate assemblies using mechanical retention systems (MRS); coupons from drum brake shoes or disc brake pad assemblies. The test and its results are also useful for short, semi-quantitative verification of the bonding and molding process. This Recommended Practice is applicable during product and process development, product verification and quality control. This Recommended Practice does not replicate or predict actual vehicle performance or part durability.
Brake Linings Standards Committee
This study primarily focuses on quasi-static mechanical modeling and dynamic flow modeling of the brake vacuum booster used in a typical four-wheeled passenger vehicles, under brake apply condition. Vacuum Booster is a key component of brake actuation system whose primary function is to multiply the force received from brake pedal. A hybrid methodology consisting of FEA and 1D simulation of the vacuum booster has been constructed in this study by accommodating its compliance. The brake vacuum booster consists of two chambers, namely vacuum and apply chamber; the force multiplication in vacuum booster occurs because of pressure difference between these two chambers. The hybrid methodology not only captures its flow dynamics but also accommodates the structural interaction that happens between the ratio disc (rigid body) and the reaction disc (hyperelastic body) with the help of finite element analysis, which is the novel part of this project. The result from finite element analysis is then fed into the quasi-static equation of motion of different components of brake vacuum booster modeled using 1D system software, to obtain a typical input load vs output load plot of the same. This study shows 96% correlation between hybrid model and the experimental results for the entire regime of the booster operation. The hybrid model is now used by the designer to obtain the booster performance curve while varying different geometrical parameters, which includes dimension of ratio disc or lap gap and the like.
Iyengar, Sharan YoganandMani Saravanan, C.Gopalan, Seshadri
This SAE Recommended Practice provides a common method to measure wear of friction materials (brake pad assemblies and brake shoes) and their mating parts (brake disc or brake drum). These wear measurements apply to brakes fitted on passenger cars and light trucks up to 4536 kg of Gross Vehicle Weight Rating under the Federal Motor Vehicle Safety Standard (FMVSS), or vehicles category M1 (passenger cars up to nine occupants, including the driver) under the European Community’s ECE Regulations.
Brake Dynamometer Standards Committee
Wheel-corner brake failures can significantly deteriorate vehicle stability and safety, since unbalanced braking forces may introduce an undesired yaw moment. This work investigates a fault-tolerant control strategy for Active Wheel-Corner Systems, exploiting Four-Wheel Independent Steering (4WIS) to mitigate such effects and preserve vehicle stability when brake actuator malfunctions occur. Unlike many existing approaches, the proposed framework does not require explicit fault detection or quantification as a prerequisite for corrective action, eliminating potential delays and uncertainties associated with fault-diagnosis schemes. A reference model for yaw rate and sideslip angle, incorporating combined longitudinal and lateral dynamics, is proposed, and a Weighted Pseudo-Inverse Control Allocation (WPCA) scheme is employed to distribute corrective actions among the four steering angles according to each tire’s capability, compensating for yaw moment imbalances caused by degraded braking performance. The overall control framework is evaluated using a high-fidelity vehicle model implemented through VI-CarRealTime, with control algorithms and fault scenarios integrated via MATLAB/Simulink, providing a flexible and realistic platform for systematic analysis. The strategy is tested in cornering maneuvers with fault injection representing the worst-case scenario of a complete failure of the outer-front wheel brake. Results demonstrate that 4WIS can effectively recover the desired vehicle response, reducing deviations in yaw rate and sideslip compared to a baseline vehicle without reconfiguration. The study highlights the potential of steering redundancy as a complementary solution to braking and torque-vectoring systems for improving fault tolerance in future Active Wheel-Corner systems.
Sonnino, SamuelMelzi, StefanoCaresia, PietroManzoni, AlessandroVaini, Gianluca
The Automobile Life Extender (ALE) comprises an on-board function, a machine learning model operating via cloud computing and a smartphone app. The on-board function receives signals such as engine RPM, throttle position, brake pedal position, and hydraulic pressure from the vehicle's ECUs. Based on this data, the on-board ALE module calculates the engine load, brake circuit load, etc., and sends it to the predictive maintenance model via the on-board IoT system. The predictive maintenance model contains recorded data about the type of engine, brake system, and their performance curves acquired from tests conducted by its OEM. Machine learning models holds a crucial role in dynamically analyzing vehicle data, identifying drive patterns, and predicting the need for maintenance of a part or system. A hybrid approach of training models based on supervised and unsupervised learning is incorporated, creating an active learning strategy to maximize the use of available data. Amazon SageMaker handles training the ML models, which can be fed into the Amazon Bedrock cloud agent as a customized model. The Amazon Bedrock code interpretation feature assists in visualizing the machine learning model. The model predicts whether repair, replacement, or maintenance is needed. The results from the ML model are displayed to the driver via a smartphone app. Based on the owner's approval, the service center can access the results from the cloud to perform diagnostics even before the vehicle reaches the service station and allocate servicing slots based on their current workload, spare parts availability, and the vehicle owner's schedule. The modular design approach is applied to accommodate other vehicle types, with provisions for model retraining based on new data.
Sundaram, RameshselvakumarKumar, LokeshSaint Peter Thomas, EdwinSureshkumar, SrihariMuthukumaran, ChockalingamMenon, Abhijith
This study focuses on the vibration analysis of hybrid composite laminated plates fabricated from E-glass Fiber and areca Fiber reinforced with epoxy resin. The hybrid laminates were prepared using the Vacuum Assisted Resin Transfer Moulding (VARTM) process with different stacking sequences and Fiber ratios, where brake lining powder was also incorporated as a filler in selected configurations to enhance mechanical and damping properties. The fabricated plates (280 × 280 mm) were subjected to experimental modal analysis using an impact hammer and accelerometer setup, with data acquisition carried out through DEWESoft software. Natural frequencies and damping ratios were determined under three boundary conditions (C- C-C-C, C-F-C-F, and C-F-F-F). The results revealed that Plate 1, with E-glass outer layers, areca reinforcement, and filler addition, exhibited the best vibration performance, achieving a maximum natural frequency of 332.8 Hz under C-C-C-C condition, while Plate 2 showed a balanced response and Plate 3 demonstrated higher stiffness but lower damping capability. These findings suggest that incorporating areca Fiber in combination with E-glass not only reduces weight but also improves damping without significantly compromising structural integrity. The developed hybrid composites hold strong potential for lightweight, vibration-sensitive applications such as automotive interiors, marine structures, construction panels, and sports equipment, where both sustainability and performance are critical.
D R, RajkumarO, Vivin LeninR, SaktheevelR G, Ajay KrishnaNg, Bhavan
The recently increasing global concern about sustainability and greenhouse gas emission reduction has boosted the diffusion of electric vehicles. Research on this topic mainly focuses on either re-designing or adapting most conventional vehicle subsystems, especially the propulsion motor and the braking components. In this context, the present work aims to model, analyze, and compare three-braking system layouts design alternatives focusing on their contribution to vehicle performance and efficiency: a commercial vacuum-boosted hydraulic braking system, a commercial integrated electrohydraulic braking system, and a concept distributed electrohydraulic brake system. Braking systems performance are evaluated by simulating key maneuvers adopting a full model of a battery electric vehicle (BEV), which includes all relevant components like tires, and powertrain dynamics, which is validated against real-world data. Implementation and integration of the first two systems are discussed, followed by the design and detailed modeling of the third, which includes a control strategy for pressure modulation, including antilock braking system (ABS) and electronic stability control (ESC) functionalities. Once the simulation environment is set, simulations are performed and KPIs are defined to compare the three braking systems from both the performance and the energy consumption point of view. The results show that the distributed electrohydraulic system reduces the time to lock by 30.8%, the stopping distance by 5.89%, and the energy consumption by more than 50% in specific test cases compared to the analyzed vacuum-boosted system due to its distributed hardware and control architecture and power-on-demand operation.
Savi, LorenzoGarosio, DamianoFloros, DimosthenisVignati, MicheleTravagliati, AlessandroBraghin, Francesco
In agricultural tractors, braking actuation is usually done through control linkages consisting of a series of connected four-bar linkages with multiple pivots from the pedal to the brake pads. The quality of force transmission is critical as it directly affects the braking performance of the tractor. Forces measured at the end of the control linkage or brake pull rod often show deviation from theoretical values based on mechanical advantage calculations. This is due to various factors such as linkage transmission angle, elasticity, and friction losses in joints. A standardized simulation method needs to be developed and validated to predict the losses in the control linkage system. In this paper, the author proposes a simulation approach using multi-body dynamics, which includes contribution factors such as transmission angle, linkage elasticity, and friction in joints. MBS models for brake linkage systems for three different tractors were developed with flex bodies using ADAMS/View software. Coulomb friction and LuGre friction models were used to describe friction in joints. Force on the brake pull rod of the simulation model correlated with measured test data, showing above 85% correlation. The developed method can be adopted to design efficient brake linkage systems for agricultural tractors.
Subbaiyan, Prasanna BalajiNizampatnam, BalaramakrishnaRedkar, DineshArun, GK, VinothR, SengottuPaulraj, Lemuel
Recent regulations limiting brake dust emissions have presented many challenges to the brake engineering community. The objective of this paper is to provide a low cost, mass production solution utilizing well known existing technologies to meet brake emissions requirements. The proposed process is to alloy the Gray Cast Iron with Niobium and subsequently Ferritic Nitrocarburize (FNC) the disc. The Niobium addition will improve the wear resistance of the FNC case, reducing wear debris. The test methodology included: 1. Manufacture of disc samples alloyed with Niobium, 2. Finish machining and ferritic nitrocarburizing and 3. Evaluation of airborne wear debris utilizing a pin-on-disc tribometer equipped with emission collection capability. The airborne emission and wear surfaces were further analyzed by Scanning Electron Microscopy, Energy Dispersive techniques (SEM-EDS), X-Ray Diffraction and Optical Microscopy. The cast iron test matrix included four groups; Unalloyed eutectic 4.3% Carbon Equivalent (CE), Unalloyed hypereutectic >4.3% CE, Niobium alloyed Eutectic and Niobium alloyed hypereutectic gray cast iron. The results demonstrate the advantages of Niobium alloyed FNC treated discs in reduced wear and meeting Euro7 airborne emission requirements. The Niobium alloyed eutectic Gray Cast Iron plus FNC treatment exhibited the best wear debris performance for both the Non-Asbestos organic (NAO) and Low Metallic (Low Met) friction materials. The Niobium alloyed hypereutectic Gray Iron plus FNC treatment also performed well with both NAO and Low Metallic friction materials.
Barile, BernardoHolly, Mike
The objective of this paper is to evaluate the thermal performance of the brake discs in the design stage of its life cycle by developing a methodology to replicate dynamometer testing using multi-disciplinary Finite Element Analysis (FEA) methods. A simulation workflow was formulated in which Computational Fluid Dynamics (CFD) was used to create temperature and velocity dependent Heat Transfer Coefficients (HTC) which were in turn used in Computer Aided Engineering (CAE) to do a thermo-mechanical analysis. With this workflow various designs of the brake discs were analyzed. A sensitivity study was done to determine critical design features that affected its thermal performance. A final design was fixed that met both the weight and thermal performance targets. This design was evaluated in dynamometer testing, and 93% correlation was achieved. Thus, the developed simulation workflow ensured that a first-time right brake disc can be finalized in the design stage, which will meet the performance in dynamometer testing.
Balaji, PraveenK, KarthikeyanS, KesavprasadS Kangde, SuhasReddy, Jagadeeswara
Indian passenger car accident data indicates that approximately 44% of crashes are frontal impacts (Refer fig 1). Among the injuries sustained in these crashes, lower leg injuries are notably critical, contributing to nearly 25% of driver occupant injuries (Refer fig 2). To evaluate such injuries, the Bharat New Car Assessment Program (BNCAP) includes lower leg injury metrics as part of the Frontal Offset Deformable Barrier (ODB64) test. While the overall injury performance is assessed at the vehicle level, BNCAP also monitors vehicle interior intrusions—particularly pedal intrusions—as key contributors to lower limb injury severity. A major challenge in frontal crashes is the intrusion of the vehicle's front-end structure into the occupant compartment. Rigid components, particularly the brake pedal assembly, can be displaced rearward during a crash, significantly increasing the risk of lower leg injuries. Therefore, minimizing pedal intrusions into the driver foot-well is critical for enhancing lower leg protection. As part of an innovative safety initiative, Tata Motors has developed a collapsible brake pedal mechanism designed to mitigate lower leg injuries during frontal crashes. This patented system incorporates a series of levers and linkages that disengage upon impact, allowing the brake pedal to collapse and thereby reducing the risk of intrusion-related injuries to the driver lower legs. The mechanism is engineered to be robust, ensuring that normal braking performance and pedal operation remain unaffected during everyday vehicle use, while providing effective injury mitigation in crash scenarios.
Shetti, Rahul R.Kudale, ShaileshNaik, NagarajBisen, BadalKotak, VijayDudhewar, SwapnilBhagat, AmitDurgaprasad, HNV
This paper proposes a DYC/ABS coordinated control strategy for cornering and braking based on driver intention. A hierarchical control structure is established, where the upper-level controller uses a vehicle dynamics model to calculate the additional yaw moment required by the DYC controller to track the desired yaw rate and sideslip angle, as well as the driver’s intended braking intensity. Taking multiple constraints into account, a quadratic programming algorithm is employed to optimize the distribution of braking forces among the four wheels. The lower-level ABS controller is designed with multiple thresholds and corresponding control phases to precisely regulate the hydraulic pressure of individual wheel cylinders. In emergency braking scenarios where ABS intervention may conflict with the upper-layer braking force allocation, a rule-based, stepwise diagonal pressure reduction compensation strategy is proposed. This strategy fully considers the influence of longitudinal and lateral forces of each wheel on the vehicle's yaw moment. By selectively reducing brake pressure, it generates an additional yaw moment to compensate for the negative impact of ABS on vehicle steerability, while ensuring a smooth pressure transition. The proposed strategy is validated on a Driver-in-the-Loop (DIL) simulation platform built using NI PXI, DSPACE, and external driver inputs such as the steering wheel and brake pedal. Under various driver braking intentions and cornering scenarios with high and low road adhesion, the strategy shows significant improvements in fulfilling driver braking demands and enhancing vehicle yaw stability compared to the non-optimized strategy.
Zou, YanMa, YaoKong, YanPei, Xiaofei
The global effort to reconsider transport in compliance with ecological challenges leads to a significant increase in the market share of Electric Vehicles (EVs), enlightening secondary sources of pollution. One of the most important is the particles emitted by the abrasion of braking pads. The innovative system addressed in this paper is among the most promising non-polluting solutions to ensure safety and comfort. It uses the capability of the Magneto-Rheological Fluid (MRF) to change its properties when subjected to a magnetic field, generating a braking torque between a stator and a rotor. This study focuses on characterizing the system's performance and endurance during an emergency braking situation by developing a numerical model that involves fluid and structural considerations. This model takes the form of a Finite-Element Model (FEM) that interpolates local forces determined from Computational Fluid Dynamics (CFD) and takes them as input. It enables analysis of the stresses induced by the variation of fluid behavior described by a Bingham theoretical model developed following experimental rheological results.
de Carvalho Pinheiro, HenriqueBilliant, LucasImberti1, GiovanniCarello, Massimiliana
Studies correlate air pollution with an increase in the incidence of respiratory diseases, affecting lung function and raising hospitalization rates. Among the pollutants associated with these diseases, inhalable coarse particulate matter (PM10) and fine particulate matter (PM2.5) stand out. The emission of particulate matter resulting from the wear of brake pads in light vehicles is the second largest source, accounting for approximately 33% of a vehicle’s total emissions. The particulate matter generated during the braking process can be analyzed through its collection in tests conducted on dynamometers, using enclosure and sampling systems. The development of the dynamometer used was based on the braking cycles described in the SAE J2522:2003 standard, whose main objective is to provide comparative data on different friction materials. Given the variations in particulate matter emissions depending on the composition of the brake pads, as reported in the literature, this study presents an analysis of the emissions from two distinct formulations, as well as a comparison of wear parameters and the surface roughness of the pads. The characterization of the particulate matter was carried out using a sampling system in accordance with ISO 9096:2017, with a sampling duct aligned with the flow duct downstream of the enclosure chamber, and particle retention achieved through fiberglass filters. The airflow velocity was controlled to ensure isokinetic transport conditions in the sampling system, adjusting the connected pump to match the probe velocity. The results show that wear was not uniform between the pairs of brake pads, also revealing differences in the chemical composition of the particulate matter according to the different formulations, consistent with what is reported in the literature, but with similar particle concentrations by size.
Catão, Vítor Gustavo GomesMachado, Amanda RibeiroFiorentin, Felipe KleinSilva, João Pedro AnutoBernardino, Lucas GabrielFiorentin, Thiago AntonioCarboni, Andrea Piga
The development of a high reliability brake disc is fundamental to automobility projects, considering its relevance as a safety component. In competitions such as Formula SAE, there is an increased emphasis on the need to reduce weight, which demands a detailed engineering analysis to minimize mass without compromising safety requirements. This paper proposes a finite element based computational methodology, combining thermal and structural simulations, built upon data collected from bench tests and in-competition courses such as the Autocross (AC) and endurance. The results describe the thermostructural behavior of the brake disc in practical conditions, enabling the determination of the acting tensions during a competitive scenario, and consequently, calculate safety factors and fatigue life of the component. The proposed methodology validates the brake disc resilience and durability, which allows for the study of more optimal geometries or more specific materials, reducing weight. Such concept can be applied not only in Formula SAE, but also in the industrial sector of development and validation of brake discs.
Machado, João Pedro FariasRibeiro, Rodrigo Eustaquio
The demand for electrified vehicles has been increasing over the last few years, near to 180 thousand units were sold only in 2024, which represented around 7% of total sales of this type of vehicle in Brazil. By the year 2030, it is expected that at least 40% of sales volume will be electrified vehicles, considering mild hybrids. These results show that vehicle manufacturers are moving towards electrification and reducing carbon emission rates. Different levels of electrification are applied in their portfolio: from mild hybrid or rechargeable vehicles to fully electric vehicles. When analyzing the number of components in each automotive system, it is possible to notice a huge reduction. Electric vehicles have 90% fewer moving parts in the engine than combustion vehicles. In brake systems, the reduction can be up to 20% in hybrid and electric vehicles, which can use the same solutions. This paper aims to present the changes in the sets of braking components from combustion vehicles to electric and hybrid vehicles and the technical advantages in terms of efficiency. These, in addition to reducing parts and providing less weight, also increase cooperative energy regeneration with the electric motor.
Romão, BrunoBatagini, EmersonHorschutz, Everton
Aircraft operations during landing or takeoff depend strongly on runway surface conditions. Safe runway operations depend on the tire-to-runway frictional force and the drag offered by the aircraft. In the present research article, a methodology is developed to estimate the braking friction coefficient for varied runway conditions accurately in real-time. To this end, the extended Kalman filtering technique (EKF) is applied to sensor-measured data using the on-ground mathematical model of aircraft and wheel dynamics. The aircraft velocity and wheel angular velocity are formulated as system states, and the friction coefficient is estimated as an augmented state. The relation between the friction coefficient and wheel slip ratio is established using both simulated and actual ground roll data. Also, the technique is evaluated with the simulated data as well as real aircraft taxi data. The accuracy of friction estimation, with and without the measurement of normal reaction force on the landing gear, is analyzed using the simulated data. The friction coefficient vs slip ratio curve, derived from the empirical “Magic formula”, compares well with the estimated maximum tire-to-ground braking friction, and a shift in optimal slip is observed in actuality compared to the predictions. The brake disc friction coefficient is also estimated during the process since the brake torque measurements are not available in the actual data. The estimated friction coefficient, which represents the real characteristics of the runway, can be used to tune the control algorithms of the aircraft’s anti-skid brake management system for various runway conditions. While improvements in anti-skid efficiency alone may not directly prevent all runway excursions, accurate real-time friction estimation enhances the predictability and reliability of braking action, supporting safer operations under degraded or uncertain runway conditions. Moreover, the real-time estimation of tire-to-ground friction coefficient vs slip ratio curves can be used to develop adaptive control algorithms for the brake management system.
T.K., Khadeeja NusrathSingh, Jatinder
The knowledge of the brake linings coefficient of friction (BLCF) is crucial for the control of the braking moment in modern vehicles equipped with electric powertrains. In the case of race vehicles equipped with carbon–carbon brakes, the coefficient of friction exhibits great variations as a function of the main influencing factors, namely the pressure, the temperature, and the sliding speed at the pad–disc interface. In this work, a Le Mans Hypercar instrumented with more than 150 sensors was adopted to perform the characterization of the BLCF from racetrack acquisitions. The front and rear left suspensions of the vehicle were instrumented with strain gauge channels and position transducers to acquire the reaction loads at the upright and the orientation of the arms. Then, the geometric matrix method was implemented for calculating the moments at the upright from which the braking torque was derived without the need to know any of the wheel inertia, nor the driveshaft torque. Data from multiple acquisitions across different racetracks, operating temperatures, and ambient conditions were used to characterize the BLCF of the front and rear carbon brakes equipped on the vehicle. After implementing pre-processing steps aimed at improving data homogeneity, two friction maps were characterized for the front and rear systems, respectively. The friction maps were validated against new experimental data showing an average 3% error reduction over assuming a constant BLCF. Accordingly, the characterized friction maps can be integrated in the brake-by-wire system of the vehicle for accurate caliper pressure control through real-time estimation of the BLCF from commonly available sensor signals, such as caliper pressure, wheel speed, and disc temperature. In this context, the effectiveness of the friction maps was demonstrated by comparing the predicted brake moments with the torques measured by the instrumented suspensions, highlighting the advantages over assuming a constant BLCF.
Cortivo, DavideVendramin, MattiaDindo, Luigi
This paper focuses on defining the optimal length of rear axle brake lines (flexible polyamide tubes) for commercial vehicles by simulating the lines digitally by considering tube behavior and various axle articulation conditions. Currently, the length of rear axle brake lines are predominantly defined with the help of a physical mockup by articulating axle conditions in a vehicle. This approach requires actual components such as frame, axle, suspension, etc., which consumes considerable time and cost. Through technological advancements, prototyping can be reduced and convergence on digital to build can be achieved through digital simulation. This paper explores tube properties, axle configurations and definitions, and various methods of digitally simulating line articulation. Boundary conditions, space reservations and design criteria for pneumatic routing are defined for the type of line designed. Digital simulation of rear axle brake lines articulation was performed and compared with prototype. The experimented method of digitally simulating line articulation significantly reduced the design iterations. And as a case study, the findings are discussed in detail.
Duraiswamy, RupeshSankaran, BhargavRaj, Santhosh
Magnetorheological brakes based on MR technology are being investigated for their potential use for automotive purposes. Among the design decisions, the selection of an appropriate MR fluid for the brake application remains an unexplored key issue. This article proposes an MCDM-based framework comprising analytic hierarchy process (AHP) and technique for order of preference by similarity to ideal solution (TOPSIS) to select an appropriate MR fluid for the automotive brake application. Three commercially available MR fluids from Lord Corporation (MRF-122EG, MRF-132DG, and MRF-140CG) are assessed against six criteria, viz. density, temperature range, yield stress, viscosity, magnetic saturation limit, and solid content. Considering all the criteria, the AHP ranked MRF-140CG highest, while TOPSIS chose MRF-122EG. Excluding the temperature range, both methods converged on MRF-122EG as the optimal choice. The proposed framework can be used for the MR fluid selection problem of other MR devices as well.
Powar, KanhaiyaPatil, Satyajit
This SAE Standard covers motor vehicle brake fluids of the nonpetroleum type, based upon glycols, glycol ethers, and appropriate inhibitors, for use in the braking system of any motor vehicle, such as a passenger car, truck, bus, or trailer. These fluids are not intended for use under arctic conditions. These fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR) or a terpolymer of ethylene, propylene, and a diene (EPDM).
Brake Fluids Standards Committee
Synchronizers are designed to provide smooth, efficient and safe transfer of torque between mechanical gears. Friction level, durability, and consistency of the fluid / friction lining system are crucial to ensuring crisp gear engagements without clashing and noise, vibration and/or harshness (NVH) for the life of the transmission. Excellent wear control of gears, synchronizer ring and cone surfaces is also critical to protecting the life of moving mechanical parts. The SSP-180 synchronizer rig measures friction durability and wear up to 100,000 engagements, using a variety of fluids and friction materials. Methodology for the development of a synchronizer durability procedure using the SSP-180 rig is presented for qualifying fluids for dry dual clutch (DCT) and manual transmission (MT) applications for General Motors. It will be shown that the new DEXRON® SSP-180 Synchronizer Durability Test in Appendix C of the GMW 16612 fluid specification [1] satisfies four key conditions for new mechanical test methods: discrimination, repeatability, effective failure mode analysis, and reasonable test duration.
Glasgow, Michael B.Zreik, KhaledEzanno, Philippe NicolasShelton, Robert W.
This RP specifies a dynamometer test procedure to characterize wear rates of automotive service brake linings (brake shoes) and disc brake pads.
Brake Dynamometer Standards Committee
The ever-increasing prevalence of electric vehicles in the global market continues to push automakers towards more stringent brake drag requirements. As OEMs seek to differentiate themselves with greater vehicle range to offset consumer anxiety as a barrier for entry to EVs, brake caliper suppliers see requirements for zero or near-zero drag at the component level becoming commonplace. Despite this pressure, many practical concerns exist with torque measurement capabilities in the sub 1.0 N-m range. Additionally, the authors have observed an industry tendency to employ suboptimal engineering methodology for assessing drag concerns, with trial and error attempts continuing to perplex engineers more than it provides solutions. This paper will seek to reintroduce to the reader the basic physics of brake drag from a fundamental free body diagram level, review statistical approaches for characterizing the individual forces acting within the caliper, and propose a simple – yet effective – virtual tool for characterizing potential solutions. The virtual tool will be correlated with physical assessments, and the practical challenges of full brake corner drag evaluations will be discussed. Finally, recommendations will be presented for evolving sliding caliper design to enable zero drag.
Robere, MatthewRetting, Joshua
As the ICE vehicle changes into the EV, we can use regenerative brake. It can improve not only the energy consumption but also reduce the hydraulic brake usage. The less hydraulic brake usage mitigates the heat loading on the brake disc. From this reason, the lightweight brake can be used in the EV. However, when the lightweight brake is applied, the brake NVH can be increased. The optimization design of the lightweight brake should be done to prevent the brake NVH. In this paper, the optimal brake disc thickness and brake interfaces are determined by using of disc heat capacity analysis. The lightweight brake should be optimized by using of the brake squeal analysis. We can verify the results from both analysis and test. Finally, we can have the lightweight brake, which is competitive in terms of cost, weight and robust to the brake NVH.
Kim, SunghoKim, JeongkyuHwang, JaekeunKang, Donghoon
This work investigates the influence of casting microstructure on the mechanical performance of ad hoc samples of recycled EN AC-43200 Al-Si alloy. Three batches are produced by modifying the casting process parameters (i.e., molten alloy temperature and in-mold cooling conditions) to obtain different casting microstructures. Room temperature tensile and high-cycle fatigue tests, coupled with metallography, X-ray tomography, and fatigue fracture surface analysis, are performed to elucidate the relationship between microstructural characteristics and mechanical properties of the investigated alloy. The findings indicate that casting pores and intermetallic precipitates play a pivotal role in influencing the mechanical behavior and performance of cast, recycled EN AC-43200 Al-Si alloy. Additionally, an inverse correlation between secondary dendrite arm spacing (SDAS) and both tensile properties and fatigue life is established.
Pavesi, AriannaBarella, SilviaD'Errico, FabrizioBonfanti, AndreaBertasi, Federico
Pin-on-disk tribometers are used to determine the frictional behaviour and boundary layer dynamics of material pairings. Material pairings are examined under defined conditions in order to reason about the friction behaviour and wear. Pairings for real brake systems with larger pad sizes can be tested on flywheel mass test rigs in order to provide proof of suitability. This is mainly due to a lack of knowledge about the scaling behaviour of friction linings. The Department of Machinery System Design at TU Berlin has combined the classic approach of a pin-on-disk tribometer with a flywheel mass test rig (up to 12.78 kgm2) and thus set up a laboratory brake on which material pairings with different pad shapes and sizes (up to 48 cm2) can be examined. The flywheel mass test rig consists of an adjustable DC-motor that drives a shaft on which variable flywheel masses and brake disks can be installed. The variability allows for different kinetic energies at different friction speeds. The test stand also has a linear table on which the pad sample holder sits. The specified braking force is generated by a hydraulic cylinder. The normal force is applied to the friction lining sample by means of a force expansion and distribution unit. This expansion ensures a uniform contact force over the entire pad surface, which has been designed with FEM simulations and proven with pressure measurement film. Different force expansions are possible for different pad geometries. During the tests, the torque, the forces in the normal and tangential directions, the temperature of the brake disk and lining sample as well as the speed are recorded using NI measuring cards and corresponding sensors. Furthermore, the lining sample can be moved with the linear table to a topography measuring unit including a camera system. By using the linear table and a laser distance sensor mounted on a linear motor, the topography of the lining sample is recorded and images can also be taken. This flexible setup allows to record the topography between individual braking operations without the need for long changeover times. The laboratory brake can be used to investigate the influence of brake force distribution on the friction process. Topographical changes can be observed in situ in between braking operations. The test rig has already been used in an initial series of tests and the first results of a running-in process of a material pairing consisting of a gray cast iron disk and an organic friction lining for truck brakes are shown.
Heuser, Robert MichaelRosenthal, Tobias RichardWiest, Daniel ChristianMeyer, Henning Jürgen
Moisture is known to be a relevant factor during a friction material life, affecting tribological behaviors such as friction coefficient and torque variations. In this study we investigated the interaction between friction materials and water; employing various techniques such as contact angle measurements, water adsorption, and exposure to controlled environmental condition changes. Focusing on NAO friction material, mix modifications were studied to highlight differences and understand mechanisms, in particular, organic content and hydrophobic agents, were examined. Characterization results showed that brake pads hydrophobicity can be influenced by water interaction conditions; even low-wettability surfaces, such as those treated with hydrophobic modifiers, can still absorb water depending on internal factors (e.g., porosity) and external conditions (e.g., contact time, humidity). Additionally, we investigated the capacity of a friction material to adsorb water and desorb it back to its initial state. Climatic chamber tests revealed that under high-humidity conditions, the differences between materials were minimized. Following this characterization, the materials were tested with Bruker UMT tribometer to assess how different conditioning treatments influence the tribological response, with particular emphasis on vibrations.
Iodice, ValentinaDurando, PietroBalestra, SimonePellerej, Diego
The effects of particle size and composition of platelet titanates, including potassium titanate and potassium-magnesium titanate, were investigated to determine their friction stability, wear resistance, and transfer film formation. The composition and properties of titanates were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), and particle size analysis. Tribological properties were evaluated using a tribometer (MFT-5000), while the worn surfaces were analyzed with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Results indicate that the transfer film characteristics are significantly influenced by the particle size and composition of platelet titanates. Brake pads containing potassium-magnesium titanates formed a more uniform transfer film, leading to improved friction stability and reduced wear rates. In contrast, potassium titanates increased friction levels but also resulted in higher wear on the brake friction materials. These findings demonstrate the importance of carefully controlling titanate composition and particle size to enhance brake pad performance. This research provides valuable insights for designing more durable and stable brake materials.
Jara, Diego ChavezLorenzana, CarlosSliepcevich, 1Lt AndreaConforti, Michael
In an earlier publication, it was reported that the pad compressibility measured under 160 bars on NAO formulas keeps decreasing with increasing number of repeated measurements due to unrecoverable residual deformation of the friction material combined with increasing moisture adsorption, which increases the hardness of the friction material. This current investigation was undertaken to find out if this same phenomenon occurs for NAOs under a low pressure of 100 bars during compressibility measurements and under 700N during dynamic modulus measurements. In all cases, it is found that the same phenomenon occurs, meaning that friction materials become permanently compressed without full recovery, making them harder to compress and raising up the modulus. The dynamic modulus of friction material attached to a backplate is found to be lower as compared with the friction material without the backplate, which is caused by more rapid moisture adsorption of friction material pads without a backplate. As pad properties are continuously changing under pressure at temperature during usage, compressibilities and dynamic moduli measured for the initial quality must not be used for predicting brake performance/NVH – an important issue for AI databases.
Sriwiboon, MeechaiRhee, Seong KwanSukultanasorn, Jittrathep
As Lowmet pad porosity increases, pad hardness decreases; pad ISO compressibility increases; the nominal friction coefficient increases (SAE J2522); and the disc wear/pad wear decreases. Brake squeal occurrence is affected by the total wear of disc and pads; the wear differential between the inboard pad and outboard pad; pad tangential taper; and pad hardness/material damping. Also, pad chamfer shape has a strong influence on brake squeal occurrence.
Rhee, Seong KwanRathee, AmanSingh, Shiv RajSharma, Devendra
Friction material properties critically impact brake squeal simulation outcomes due to their nonlinear and transversely isotropic behaviors, which vary with load type and direction. To improve the reliability of brake squeal predictions, this study introduces the Transversely-isotropic Elastic Constants Optimization (TECO) method, a novel multi-dimensional constrained optimization framework for refining the elastic constants and damping ratio of friction materials. By integrating experimental testing, finite element analysis (FEA), and an advanced optimization technique - Gradient Response Surface Algorithm (GRA), the TECO method minimizes discrepancies between simulated and experimental data, ensuring accurate characterization of elastic properties. The TECO method offers significant advantages, including flexibility and robustness, making it an effective alternative to ultrasonic measurements and traditional optimization techniques, especially for anisotropic friction lining materials. Unlike existing approaches, TECO imposes no restrictions on the number of defined modes, allowing accurate characterization with fewer input data points. Its iterative process ensures strong correlation between experimental and simulated results while preserving essential modal attributes, such as natural frequencies and mode shapes. Focused on drum brake squeal prediction, the TECO method enhances complex eigenvalue analysis (CEA) by incorporating friction material properties measured under actual squeal loading conditions. This approach yields highly correlated NVH simulation models at the component level, providing a reliable framework for brake squeal analysis and design. By advancing the predictive accuracy of brake squeal simulations, the TECO method offers a versatile and effective solution for characterizing friction material properties, contributing significantly to noise, vibration, and harshness (NVH) optimization strategies in braking systems.
Philip, RonyMuralidharan, SudharsanMohanam, Gopalakrishnan
Brake caliper rattle noise is difficult to simulate due to its non-stationary, random, and broadband frequency characteristics. Many CAE engineers have adopted rattle vibration as an alternative metric to quantitative noise levels. Previous rattle noise simulations primarily presented relative displacement results derived from normal mode analysis or vibration dB levels rather than actual noise dB levels. However, rattle noise consists of continuous impact noise, which must account for reflections, diffractions, and refractions caused by transient nonlinear contacts and localized vibrations—especially during extremely short contact events. To accurately simulate impact noise, vibration and acoustic characteristics should be analyzed using a simplified structure, given the numerous mechanisms influencing impact noise generation. The rattle noise can be effectively modeled using LS-Dyna, which incorporates both explicit and BEM solvers. The correlation between test results and CAE simulations was established using a simple beam rattle model and a caliper system-level model, ensuring compliance with automotive manufacturer test specifications. A reasonably simplified FE model for rattle noise was developed to optimize computational efficiency and validated against previous complex eigenvalue analysis, explicit transient dynamic analysis for squeal noise (representing high frequencies), and explicit transient dynamic analysis for creep-groan vibration (representing low frequencies). This validation confirmed strong system-level correlation with vehicle and dynamometer test results. Finally, caliper system-level rattle noise simulations, utilizing the same validated squeal and creep-groan models, were conducted under Belgian road power spectral density conditions. Employing a single CAE tool and a unified FE model provides an efficient NVH engineering approach for identifying countermeasures during vehicle development. This study presents a practical example of an efficient CAE methodology for addressing brake NVH challenges.
Park, Joosang
Advanced ferritic nitrocarburizing process combined with a specialized post-oxidation treatment described as FNC + Smart ONC® [1] is developed for brake rotor applications. The process can be applied to standard grey cast iron brake rotors, significantly reducing PM 10 emissions to levels below the Euro 7 limits for most vehicles equipped with at least some recuperative braking capabilities, all without compromising performance. Finished grey iron brake rotors, ferritic nitrocarburized and post oxidized were evaluated according to several industry standards. The standards include SAE J2707B (Block Wear Test including Highway) [2], GRPE-90-24 Rev.1 Emission Test (Full WLTP Brake Cycle 6 Times) [3], and SAE J2522 (AK-Master Performance) [4]. Nitrocarburized post oxidized brake rotors were compared to untreated grey iron rotors exposed to several friction materials. Ferritic nitrocarburizing and post oxidation addresses the issue of corrosion, which is particularly relevant for brake rotors that experience less use in vehicles with recuperative braking systems. Improved corrosion performance of ferritic nitrocarburizing and post oxidation could potentially eliminate the need for the conventional practice of painting rotors. Corrosion performance was validated by conducting cyclic corrosion according to SAE J2334 (Cyclic Corrosion, 36 cycles) [5]. A reduction in brake emissions by 50 percent was achieved for existing vehicles without recuperative braking systems.
Winter, Karl-MichaelHolly, Mike
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