Browse Topic: Brake pads

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Characterisation of Brake Wear PM2.5 and PN10 Emissions Across Pad/Disc Technologies, Vehicle Types and Braking Behaviours, Under Real World Conditions2026-24-0022To be published on 09/21/2026
This paper summarises targeted brake emissions investigations undertaken as part of the Department for Transport’s Non Exhaust Emissions programme. The work was carried out to improve understanding of particulate mass and particle number emissions from friction braking and to assess the influence of component selection, vehicle technology, operating conditions, and control measures on those emissions. Starting from a pre-developed brake enclosure and sampling system methodology, these were further refined to improve airflow management, reduce leakage, and minimise sampling artefacts. The updated system was integrated with a suite of particulate measurement instruments, including MPEC (hot and cold), APC10, DMS500, and eFilter, enabling simultaneous measurement of volatile and non volatile PN10 plus PM2.5. A matrix of nine brake pad formulations and two disc types was tested on a common C segment vehicle platform across chassis dyno and on road cycles, together with controlled braking
Andersson, Jon
Aerodynamic Disc Brake Drag: An Elusive Source of Variability2026-01-0802To be published on 09/14/2026
The ever-present drive to increase vehicle range and efficiency has resulted in disc brake caliper requirements at or near zero residual drag. It is increasingly critical to understand and design around potential edge cases that can drastically increase off-brake drag. One frequently observed, but often misunderstood, phenomenon is drag induced by aerodynamic forces surrounding the brake pad. Complex airflow characteristics surrounding the pad in the brake corner environment can lead to Venturi Effect induced air pressure differentials on each side of the pad, leading to transient, yet pronounced, increases in brake drag. This paper will follow a case study during which brake pad pressure differentials were discovered and experimentally measured, review the Venturi Effect as it relates to brake corners, and explore modelling approaches for identifying and correcting designs that are prone to this phenomenon.
Robere, Matthew, Tresmondi, Thales
Advanced Brake Force Distribution on trailers with Bendix Electronic Brake Controller2026-01-0797To be published on 09/14/2026
Commercial vehicle fleets frequently operate with tractors that connect to different trailers and dollies, resulting in combinations with varying brake pad wear across wheel‑ends. Traditional brake force distribution strategies whether proportioned, electronic, or load‑adaptive do not account for these pad life differences. This can lead to uneven brake utilization, irregular maintenance intervals, and increased total cost of ownership (TCO), especially in mixed‑fleet and multi‑trailer operations. This work introduces an advanced brake force distribution function, a mechatronic brake control concept that incorporates brake pad health information into supervisory brake force allocation. In the proposed architecture, the tractor is equipped with a Brake Control ECU, which collects brake pad life status from each trailer or dolly through Pad Wear Sensing ECUs over the Tractor‑Trailer CAN (TT‑CAN) network. The Pad Wear Sensing ECUs report pad wear information only and do not host braking
Ganesha, Vinodkumar
Finite Element–Based Wear Analysis of Brake Pads2026-01-0817To be published on 09/14/2026
Brake pads are essential components that play a critical role in ensuring vehicle safety and braking performance. Variations in the pad–disc contact interface directly affect the behavior of both the disc and the piston, which can lead to reduced braking efficiency, unstable pedal response, or overall brake system degradation. As wear on the pad surface gradually alters the contact conditions, accurately predicting the evolution of brake pad wear is vital not only for maintaining brake stability but also for assessing long-term component durability. In particular wear behavior observed during the burnish evaluation mode is significant, as this phase governs the stabilization of the pad surface and influences the establishment of a steady friction coefficient. In this study, a finite element–based wear analysis procedure was developed using the Archard wear theory to evaluate the wear behavior of automotive brake pads. A wear direction algorithm and an element distortion control
SONG, SEONG IL, JOO, SANG DON, KIM, MIN SOCK, KERSZBERG, NICOLAS, Lee, Heewook
Further Investigation of Brake Squeal: Effect of (Inboard/Outboard) Pads Property Differential2026-01-0799To be published on 09/14/2026
It was reported earlier that the wear differential between the inboard pad and the outboard pad leads to brake squeal generation. The (I/O) pads wear differential can occur due to hardware issues such as brake pad drag and/or two different wear rates of the (I/O) pads, which is caused by two different properties of the pads although the pad formula may be the same. The current investigation focuses on the pad property issues. It is found that pad compressibility differential and pad hardness differential are closely related to brake squeal generation. The property differentials are caused by pad porosity variations. The implications of hardness differential on friction/vibration will be discussed.
Liu, Richard, Wu, Shane, Wu, Godot, Li, Aihong, Zou, Tianlang
Optimization of Hydraulic Disc Brake Caliper Parameters to Achieve Near Zero Residual Drag in Two-Wheeler Brake Systems2026-01-0820To be published on 09/14/2026
Residual drag in hydraulic disc brake systems is an inherent phenomenon caused by elastic deformation of piston seals, geometric tolerances, and frictional interaction between piston, seal, and brake pads. Even minimal unintended pad-to-disc contact after brake release can generate residual torque, leading to increased rolling resistance, temperature rise, accelerated pad wear, and reduced vehicle efficiency. With growing emphasis on performance optimization and energy efficiency in two-wheeler applications, minimizing brake drag without affecting braking response has become an important design objective. This paper presents the design, analysis, and experimental validation of a zero-drag floating brake caliper concept developed to reduce residual brake torque through optimization of piston seal characteristics and groove geometry. The study focuses on understanding piston rollback behavior as the primary mechanism governing pad clearance after pressure release. Analytical evaluation
Badade, Ashish Laxman
Machine Learning Prediction of Wear of NAO Brake Pad Using Scaled-Down FMVSS 135 Testing2026-01-0808To be published on 09/14/2026
Brake pad lifespan significantly influences environmental pollution and public health due to non-exhaust particulate emissions. Global vehicle production reached approximately 7 billion units in 2025, with brake systems generating an estimated 50,000 to 100,000 metric tons of wear debris annually, underscoring the need for improved durability and material optimization. This study investigates the capability of a Fully Connected Neural Network (FCNN) to predict brake pad wear and support formulation optimization. Controlled experiments were performed using a simplified FMVSS 135 protocol on a Universal Mechanical Tester (UMT) to simulate realistic braking conditions. Wear loss was measured under varying normal loads, sliding velocities, and interface temperatures. An FCNN was selected for its ability to capture nonlinear interactions between operating conditions and tribological responses. Despite a limited but high-quality dataset, the application of data standardization
Katakam, Abhishek, Eslamiat, Hossein, Kancharla, Sai Krishna, Filip, Peter
Comparison of the Surfaces and Coefficients of Friction of Truck Brake Pads Tested on a Flywheel Test Bench and a Scaled Tester – A Case Study2026-01-0826To be published on 09/14/2026
Mechanical brakes have been used and studied in many areas of mechanical engineering and automotive technology for decades. However, the processes in the contact zone have not yet been described with sufficient accuracy. One reason for this is the inability to observe the contact zone during contact. Studies in which one contact partner is replaced by an optically transparent material influence the processes in the contact area. Researchers are therefore forced to examine the surfaces of the contact partners after the actual contact has taken place. Various measuring systems, such as microscopes or laser sensors for surface structure measurement, are used to measure the surfaces of the brake pads. Due to shorter measuring times, mainly only smaller samples from measurements using pin-on-disc tribometers are examined for this purpose. However, various studies show that the friction and wear values of pin-on-disc tribometers cannot be transferred to real brake systems. For this reason
Rosenthal, Tobias Richard, Wiest, Daniel Christian, Meyer, Henning Jürgen
Real-time Estimation of Brake Temperature using Physics-Informed Machine Learning Model2026-01-0810To be published on 09/14/2026
The current work presents a novel approach to estimate brake surface temperature in real time to aid in brake wear prognostics. Brake prognostics involve estimating the brake pad wear in real-time that helps in its predictive maintenance. Brakes are a safety critical system for vehicles, therefore, demands accurate and robust pad wear estimation, ensuring vehicle safety. However, it involves several challenges. The estimation of pad wear is fundamentally a two-stage process: the first stage involves the accurate prediction of brake pad surface temperature, while the second stage utilizes this thermal history to calculate cumulative material wear. A significant challenge in estimating brake pad wear without expensive sensor is that it is sensitive to the surface temperature prediction; any error in the thermal model propagates and compounds in the wear prediction stage. To identify surface temperature, traditional physical sensors are often cost-prohibitive or prone to failure in the
Gannavarapu, Shivadath, Pal, Anuj, Fan, Mengdi
Influence of Modified Fly Ash Content on the Properties of Resin-Based Friction Materials2026-99-1657To be published on 07/24/2026
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
Li, Xiaobiao, He, Kang, Zhao, Zhuanzhe, Wu, Bo, Sun, Fei
Test Procedures for Shear Strength of Automotive Brake Pads and Brake Lining AssembliesJ840_202603 (Current)3/31/2026
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
Brake Pads, Lining, Disc, and Drum Wear MeasurementsJ2986_202602 (Current)2/19/2026
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
Vibrational Analysis of Hybrid Composite Laminated Plates of E – Glass and Areca Fibers with Brake Pad Waste Powder2026-28-00732/12/2026
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
D R, Rajkumar, O, Vivin Lenin, R, Saktheevel, R G, Ajay Krishna, Ng, Bhavan
Agricultural Tractor Brake Linkage Efficiency Prediction and Correlation Using Flexible Multibody Dynamics Model2026-26-01031/16/2026
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
Subbaiyan, Prasanna Balaji, Nizampatnam, Balaramakrishna, Redkar, Dinesh, Arun, G, K, Vinoth, R, Sengottu, Paulraj, Lemuel
Investigation of Particulate Matter Emissions from Brake Pads of Light-Duty Vehicles: A Comparative Analysis of Friction Material Compositions2025-36-020012/18/2025
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
Catão, Vítor Gustavo Gomes, Machado, Amanda Ribeiro, Fiorentin, Felipe Klein, Silva, João Pedro Anuto, Bernardino, Lucas Gabriel, Fiorentin, Thiago Antonio, Carboni, Andrea Piga
Multi-Physics Numerical Modelling of a Magnetorheological Braking System2025-36-005012/18/2025
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
de Carvalho Pinheiro, Henrique, Billiant, Lucas, Imberti1, Giovanni, Carello, Massimiliana
Wear Test Procedure on Inertia Dynamometer for Brake Friction MaterialsJ2707_202509 (Current)9/23/2025
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
Influence of Titanate Composition and Particle Size on Friction Stability and Wear in Brake Pads2025-01-03379/15/2025
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
Jara, Diego Chavez, Lorenzana, Carlos, Sliepcevich, 1Lt Andrea, Conforti, Michael
Further Investigation of Variables Affecting Brake Squeal: Porosity Effect on Lowmet Pad Properties2025-01-03359/15/2025
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 Kwan, Rathee, Aman, Singh, Shiv Raj, Sharma, Devendra
Further Investigation of Disc Pad Compression Deformation during ISO Compressibility and Dynamic Modulus Measurements under Relatively Low Pressures2025-01-03349/15/2025
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
Sriwiboon, Meechai, Rhee, Seong Kwan, Sukultanasorn, Jittrathep
Water Interaction and Its Effect on the Tribological Behavior of NAO Friction Materials2025-01-03369/15/2025
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
Iodice, Valentina, Durando, Pietro, Balestra, Simone, Pellerej, Diego
Anti-Noise Brake Pads Shims: T-Pull Test and Bond CoverageJ2694_202503 (Current)3/5/2025
This recommended practice covers the attachment of bonded anti-noise brake pad shims only. Mechanically attached shims (those without bonding) are not covered by this procedure.
Brake Linings Standards Committee
Study of Mechanical, Barrier and Tribological Behaviour of Jute & Glass Fiber Epoxy Hybrid Polymer2025-28-00312/7/2025
The incorporation of natural available material into synthetic materials to form a fiber within a single polymer matrix has been ignited since environment concerns become crucial nowadays. Composite materials embedded with two or more types of fibers makes a composite as hybrid. The study of hybridization of natural and synthetic fibers brings out superior mechanical and tribological properties. In our present studies, fabrication of jute & glass fiber reinforced epoxy-based polymer hybrid composites were carried out using resin infusion technique. For comparing the various properties, the composite made of pure jute fiber i.e 100% jute, pure glass fiber i.e 100% glass, the hybrid composite containing 75% jute and 25% glass fiber, 50% jute and 50% glass fiber, and 25% jute and 75% glass fiber were made and its functional behaviors were studied. The results revealed the hybrid composite containing 25% jute and 75% glass fiber possessed maximum tensile strength of 292±5.8 MPa, flexural
J, Chandradass, T, Thirugnanasambandham, M, Amutha Surabi, P, Baskara Sethupathi, Rajendran, R, Murugadoss, Palanivendhan
Composite Brake Pads Reinforcement with Natural Fiber: A Comparative Analysis of Mechanical and Thermal Properties2024-01-511212/30/2024
This work pioneers the development of eco-friendly brake pads using coconut fiber and sawdust as reinforcement materials, combined with abrasives and friction modifiers. The innovation lies in the utilization of these natural fibers, which are not only cost-effective and abundantly available but also contribute to the sustainability of brake pad manufacturing. The study aims to explore the feasibility and performance of these organic fibers in brake pad applications. Coconut fiber and sawdust were chosen for their unique properties, such as high strength-to-weight ratio and thermal stability, making them ideal candidates for enhancing brake pad performance. The inclusion of abrasives and friction modifiers further optimizes the braking efficiency and durability of the pads. Comprehensive testing was conducted, including hardness, compression, wear (using a pin-on-disc apparatus), and thermogravimetric analysis (TGA), to thoroughly evaluate the mechanical properties and thermal
Ajay Devan, V., Gunasekar, N., Ravikumar, K., Balaguru, B. A., Deepak, S.
Road Vehicles - Friction Materials - Finished Brake Pad Normalized Elastic Constant of Friction MaterialJ3175_202412 (Current)12/6/2024
This SAE standard specifies a method for testing and measuring a normalized elastic constant of brake pad assemblies using ultrasound. This document applies to disc brake pad assemblies and its coupons or segments used in road vehicles.
Brake Linings Standards Committee
TOC99-06-05-0TOC10/10/2024
TOC
Tobolski, Sue
Time for a Model Change - Inorganic Friction Materials2024-01-30429/8/2024
This paper’s aim is to explain alternative friction lining formulations based on inorganic polymer binders for the production of new, future-proof brake friction materials. The aspects of high-temperature stability in the fading tests of the AKM- and AMS tests, as well as the reduction in PM10 emissions compared to classic organic friction materials, make these materials particularly fascinating for future use. Additionally, the energy savings potential of this type of friction lining could be of particular importance when sustainability considerations further influence our development activities in friction brake related applications.
Milczarek, Roman Paul, Wittig, Niels
Investigation on Brake-Drag-Optimization on Vehicle-Level2024-01-30379/8/2024
Brake drag in disc brakes occurs during the off-brake-phase, when the brake is not applied but friction contacts between brake disc and pads persist. First and foremost, the resulting drag torque increases energy consumption, where a few Newton meters can have a significant impact on the crucial factor – range – of battery-electric-vehicles. Moreover, brake wear is accelerated in conjunction with enlarged taper-wear of the pads. Additional wear can also imply increased brake particle emissions which are going to be limited by upcoming regulations due to their potential health risk. In this light different countermeasures aim to create and maintain a sufficient air gap between brake disc and pads when the brake is released to avoid residual friction contacts. Among others these include optimization of piston retraction by adjusting the seal-grooves and integrating pad springs into the caliper to push the pads back. State of the art to analyze the effectiveness of countermeasures are
Huchtkoetter, Philipp, Neubeck, Jens, Wagner, Andreas
Initial Corrosion and Wear Behavior of Brake Rotors Treated with Plasma Electrolytic Aluminating or Ferritic Nitrocarburizing Process2024-01-30439/8/2024
To combat corrosion and wear issues of automotive brake discs, many manufacturers have introduced various surface treatment technologies, such as thermal spraying, laser cladding, and ferritic nitrocarburizing (FNC). Besides those surface treatment technologies, a plasma electrolytic aluminating (PEA) process has also shown to be effective in producing alumina-based ceramic coatings on cast iron substrates, providing an enhanced corrosion resistance. In this study, the PEA-coated brake rotor and FNC-treated brake rotor were comparatively tested in various corrosion conditions, including an electrochemical corrosion test and simulative corrosion experiment, before and after a road driving test. A scanning electron microscope (SEM) and an energy-dispersive X-ray (EDX) were used to observe and analyze morphology and chemical compositions of the surfaces and cross-sections of the tested rotors. The results showed that the new PEA-coated brake rotor demonstrated the best corrosion
Liu, Yinting, Nie, Xueyuan
Enhancing Brake Performance: FNC-Smart-ONC® Technology to Address Corrosion Challenges and Extend the Durability of GCI Rotors2024-01-30449/8/2024
The most used rotor material is gray cast iron (GCI), known for its susceptibility to corrosion. The impact of corrosion on the braking system is paramount, affecting both braking performance and the emission of particulate matter. The issue becomes more severe, especially when the brakes are left stationary or unused for extended durations in humid conditions, as seen with electric vehicles (EVs). Brake disc corrosion amplifies the risk of corrosion adhesion between contacting surfaces, leading to substantial damage, increased quantity and mass of non-exhaust particulate emissions, and decreased braking effectiveness. In addition, brake pads' friction material plays a crucial role in generating the necessary stopping force, creating friction that transforms kinetic energy into heat. However, heightened pressure during braking elevates rotor temperatures, contributing to the degradation of the friction material. This degradation manifests in decreased mechanical strength, heightened
Nousir, Saadia, Winter, Karl-Michael
Low-Speed Stop and Near Zero-Speed Start-to-Move Brake Noise: Effect of Moisture Adsorption, Prior Braking and Deceleration Rate2024-01-30579/8/2024
The influence of moisture adsorption, prior braking, and deceleration rate on the low-speed braking noise has been investigated, using copper-free disc pads on a passenger car. With increasing moisture adsorption time, decreasing severity of prior braking or increasing deceleration rate, the noise sound level increases for the air-borne exterior noise as well as for the structure-borne interior noise. The near-end stop noise and the zero-speed start-to-move noise show a good correlation. Also, a good correlation is found between the noise measured on a noise dynamometer and on a vehicle for the air-borne noise. All the variables need to be precisely controlled to achieve repeatable and reliable results for dynamometer and vehicle braking groan noise tests. It appears that the zero-speed start-to-move vehicle interior noise is caused by the pre-slip vibration of the brake: further research is needed.
Sriwiboon, Meechai, Rhee, Seong Kwan, Sukultanasorn, Jittrathep, Kunthong, Jitpanu
Moisture Adsorption and Compression Deformation Behavior of Semimet vs. NAO Brake Pads: Effect of Pad Cure Temperatures and Moisture Adsorption on Low-Speed Friction2024-01-30569/8/2024
Moisture adsorption and compression deformation behaviors of Semimet and Non-Asbestos Organic brake pads were studied and compared for the pads cured at 120, 180 and 240 0C. The 2 types of pads were very similar in moisture adsorption behavior despite significant differences in composition. After being subjected to humidity and repeated compression to 160 bars, they all deform via the poroviscoelastoplastic mechanism, become harder to compress, and do not fully recover the original thickness after the pressure is released for 24 hours. In the case of the Semimet pads, the highest deformation occurs with the 240 °C-cure pads. In the case of the NAO pads, the highest deformation occurs with the 120 0C-cure pads. In addition, the effect of pad cure temperatures and moisture adsorption on low-speed friction was investigated. As pad properties change all the time in storage and in service because of continuously changing humidity, brake temperature and pressure, one must question any
Rhee, Seong Kwan, Rathee, Aman, Singh, Shivraj, Sharma, Devendra
Brake Particle Emission Influenced by Grooved Disc Friction Surfaces with or without a Hard Coating2024-01-30309/8/2024
Many performance sport passenger vehicles use drilled or grooved cast iron brake rotors for a better braking performance or a cosmetic reason. Such brake rotors would unfortunately cause more brake dust emission, appearing with dirty wheel rims. To better understand the effects of such brake rotors on particle emission, a pin-on-disc tribometer with two particle emission measurement devices was used to monitor and collect the emitted airborne particles. The first device was an aerodynamic particle sizer, which is capable of measuring particles ranging from 0.5 to 20 μm. The second device was a condensation particle counter, which measures and collects particles from 4 nm to 3 μm. The testing samples were scaled-down brake discs (100 mm in diameter) against low-metallic brake pads. Two machined surface conditions (plain and grooved) with uncoated or ceramic-coated friction surfaces were selected for the investigation. The results showed that the grooved friction surface led to a higher
Cai, Ran, Nie, Xueyuan, Lyu, Yezhe, Wahlström, Jens
Analysis of Disc-Brake Squeal Considering Lining Wear2024-01-30369/8/2024
Brake squeal is a phenomenon caused by various factors such as stiffness of brake components, mode coupling, friction coefficient, friction force variation, pressure, temperature and humidity. FEA simulation is effective at predicting and investigating the cause of brake squeal, and is widely used. However, in many FEA simulations, models of brake lining are mostly a brand-new shaper, so that the change of pressure distribution or pad shape, which can occur due to the lining wear, are not taken account. In this research, brake squeal analysis was conducted with consideration of lining wear, applying Fortran codes for Abaqus user subroutine. The brake assembly model for the analysis is created by using a 3D scanner and has a close shape to the real one. The wear patterns calculated by the analysis are similar to those of brake pads after a noise test. The complex eigenvalue analysis shows two unstable modes at the frequency of squeal occurred in the noise test. One is out-of-plane
Ikegami, Tokunosuke, Millsap, Tom, Yamaguchi, Yoshiyuki
Objectively Quantify Creep Groan and Dynamic Grunt Performance of Different Brake Friction Materials2024-01-30359/8/2024
The assessment of brake friction materials extends beyond squeal noise and thermal roughness testing as it play crucial role in other brake noise phenomena such as creep groan and dynamic grunt. These low frequency noise types are significant as they directly affect passengers comfort levels. Creep groan noise defined as audible stick-slip noise at low vehicle speed during partial brake application, typically encountered in dense traffic conditions. Dynamic grunt is another form of stick-slip noise observed during high-speed braking and it is noticeable just prior to vehicle’s complete stop. This noise is indicative of frictional interaction between the brake pad and disc under deceleration scenario. Comparative analysis of two distinct brake friction materials was conducted utilizing both NVH dynamometer and real-world vehicle testing. The NVH dynamometer procedure was designed to evaluate the creep groan and dynamic grunt phenomena under controlled environmental conditions. For the
Barot, Ankit, Wang, Weicherng
Microstructural Analysis and Tribological Performance of Composite Iron Sulfides in Automotive Brake Pads2024-36-03228/9/2024
This research explores the tribological characteristics of brake friction materials, focusing on synthetic iron-based sulfides with unique microstructures. Tribological testing, conducted per the SAE J2522 and SAE J2707 standards across diverse temperatures, reveals the superior performance of brake pads incorporating composite iron sulfide, especially at high temperatures. These pads exhibit stable friction levels and reduced wear compared to those utilizing pure iron sulfide, signifying a noteworthy advancement in overall tribological properties. A comprehensive cross-sectional analysis of friction materials using Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDS) reveals chemical alterations. Pure iron sulfide undergoes extensive oxidation compared to composite iron sulfide, which exhibits oxidation near the friction surface due to differences in the oxidation mechanism because of the differential microstructure. Furthermore, Thermogravimetric Analysis
Jara, Diego Chavez, Lorenzana, Carlos, Cotilli, Edoardo, Sliepcevich, Andrea, Conforti, Michael
Proposed Test Method for Brake Pad Lining Robustness in Cold Conditions2024-01-50494/24/2024
With globalization, vehicles are sold across the world throughout different markets and their automotive brake systems must function across a range of environmental conditions. Currently, there is no current standardized test that analyzes brake pads’ robustness against severe cold and humid environmental conditions. The purpose of this proposed test method is to validate brake system performance under severe cold conditions, comparing the results with ambient conditions to evaluate varying lining materials’ functional robustness. The goal of this paper is to aid in setting a standardized process and procedure for the testing of automotive brakes’ environmental robustness. Seven candidate friction materials were selected for analysis. The friction materials are kept confidential. Design of experiment (DOE) techniques were used to create a full-factorial test plan that covered all combinations of parameters. The test script involves brake applications at 5, 10, 15, and 20 bar, at both
Passador, Stephen Daniel Austin, Boudreau, Douglas Barret, Capacchione, Christopher James
Effect of Surface Roughness on Tribological and NVH Behaviour of Brake System2024-01-27324/9/2024
Brake assemblies are an essential part of any vehicle, and their effective functioning is critical for the safety and comfort of passengers. The surface roughness of brake components plays a vital role in figuring out their tribological and NVH (Noise, Vibration, and Harshness) behavior. It is essential to understand the impact of surface roughness on brake performance to ensure efficient braking and it has been a topic of interest in the automotive industry. In this study, the influence of surface roughness on the wear, and noise characteristics of a brake assembly has been investigated. The study also provides insights into the relationship between surface roughness, frictional behavior, and NVH performance, which can be used to improve the design and manufacturing of brake assemblies. The brake assembly includes of a disc, caliper, and brake pads, which work together to convert the kinetic energy of the vehicle into heat energy, has been considered in this study. First, the
S, Gurumoorthy, Bhimchand, Naresh, Bourgeau, Alyssa, Bhumireddy, Yugandhar
Gap Adjustment Strategy for Electromechanical Brake System Based on Critical Point Identification2024-01-23204/9/2024
Abrasion of the Electromechanical brake (EMB) brake pad during the braking process leads to an increase in brake gap, which adversely affects braking performance. Therefore, it is imperative to promptly detect brake pad abrasion and adjust the brake gap accordingly. However, the addition of extra gap adjustment or sensor detection devices will bring extra size and cost to the brake system. In this study, we propose an innovative EMB gap active adjustment strategy by employing modeling and analysis of the braking process. This strategy involves identifying the contact and separation points of the braking process based on the differential current signal. Theoretical analysis and simulation results demonstrate that this gap adjustment strategy can effectively regulate the brake gap, mitigate the adverse effects of brake disk abrasion, and notably reduce the response time of the braking force output. Monitoring is critical to accurately control EMB clamping force. Pressure transducers are
Zhang, Yilong, Chen, Zixuan, Wu, Jinglai, Zhang, Yunqing
Brake Pad Life Monitoring System Using Machine Learning2024-26-00321/16/2024
In the context of vehicular safety and performance, brake pads represent a critical component, ensuring controlled driving and accident prevention. These pads consist of friction materials that naturally degrade with usage, potentially leading to safety issues like delayed braking response and NVH disturbances. Unfortunately, assessing brake pad wear remains challenging for vehicle owners, as these components are typically inaccessible from the outside. Moreover, Indian OEMs have not yet integrated brake pad life estimation features. This research introduces a hybrid machine learning approach for predicting brake pad remaining useful life, comprising three modules: a weight module, utilizing mathematical formulations based on longitudinal vehicle dynamics to estimate vehicle weight necessary for calculating braking kinetic energy dissipation; and temperature and wear modules, employing deep neural networks for predictive modeling. Notably, the model’s training leverages rig-level data
Iqbal, Shoaib, Bhambri, Mihir, lahase, Rahul
Inertia Dynamometer Disc and Drum Brake Effectiveness Test ProcedureJ2522_202312 (Current)12/13/2023
This SAE Recommended Practice establishes a standard method to perform screening test sequences that identify a brake friction material’s effectiveness under various test conditions. The result is an evaluation of brake friction material effectiveness under a set of defined braking conditions considered most relevant to automobile braking system development.
Brake Dynamometer Standards Committee
Effect of Soft Reinforcement Particles on Microstructural, Mechanical, and Tribological Properties of Sintered Copper-Based Brake Composite Friction Material2023-28-013211/10/2023
The main objective of the work is to investigate the friction and wear behavior of sintered copper-based brake composite friction material with a change in the volume percentage of soft reinforcement particles namely MoS2 by pin-on-disc tribometer for medium-duty automotive applications. The composite brake friction material contains copper (Cu) as a matrix, tin (Sn) as an additive, silicon carbide (SiC) and molybdenum disulfide (MoS2) as hard and soft reinforcement particles and barium sulfate (BaSO4) as filler. These hybrids copper-based brake composite friction (pin) samples are successfully prepared by a change in compositions of MoS2 from 0 to 5 vol. % in the step of 1 vol. % and the characterizations of friction samples are studied to understand the physical and mechanical properties such as density, hardness, and compressive strength. Finally, the dry sliding friction and wear test is conducted against grey cast iron material (disc) at constant load and sliding speed of 50 N and
P, Raja, Ramkumar, Penchaliah
Development of Organic Reinforcement Composite Materials for Brake Pads2023-28-006911/10/2023
Commercial brake pads are being wind down because of asbestos fibre which causes carcinogenic effect. By observing it is obligatory to analyse about the alternate materials for brake pads additionally there are heaps of alternatives for asbestos furthermore to develop an organic composite material for brake pads using organic fibers including grind orange peel and banana peel as the reinforcement material. Disparate alternatives for filler materials and different binders such as epoxy resin, phenolic resin and distinctive organic materials used to alter the material for asbestos fiber and studied miscellaneous possible formulations and their effect on the performance of the brake pads by varying the reinforcement composition from 20% - 30%, binding material from 30% - 40%, filler materials as 17.5%, friction modifiers as 22.5%, and fabricated the material for brake pads using grinded orange peel and banana peel as reinforcement further performed hardness test and wear test to compare
Jamuna Rani, G, Konda, Chaitanya Sai Teja, Gollamudi, Srivalli, Lakshmipuram, Naveen Babu
Development of Asbestos Free Aramid Fibre based Friction lining Material for Automotive Application2023-28-012211/10/2023
The usage of asbestos-free material has grown in the automotive, aviation, and marine sectors due to its carcinogenic nature. The present investigation is to evaluate the non-asbestos organic friction material for automotive applications using aramid fibers. The aramid fibers or pulp is one of the essential ingredients of friction material as it possesses good qualities of friction material like high wear resistance and reliability. The present work is to optimize the pulp required for the best performance of friction lining material for brake pads in the automotive industry. The pulp percentage is varied by 0, 5, 7.5, and 10 weight percentages in hybrid composite friction materials. The various mechanical, wear and microstructural analysis are studied. The experimental result revealed that friction material having 10 wt% of aramid fiber (AF) proved the best performance with superior mechanical and wear characteristics.
J, Chandradass, T, Thirugnanasambandham, M, Amutha Surabi, P, Baskara Sethupathi, Rajendran, R
Effect of Moisture Adsorption on Low-Speed and Moderate-Speed Braking: Effect on In-Stop Friction Coefficient and Low Frequency Noise2023-01-186211/5/2023
Copper-free NAO disc pads of passenger cars were investigated for a combination of prior braking conditions and moisture adsorption influencing in-stop friction and noise during low-speed stops, and in-stop-friction during moderate-speed stops. Prior braking conditions and moisture adsorption strongly influence subsequent in-stop friction behavior and noise at room temperature. The low-speed in-stop friction behavior looks totally different from that of moderate-speed stops. The low-speed in-stop friction increasingly oscillates with increasing moisture adsorption and goes down towards the end of a stop, which is accompanied by increasing low-frequency noise. The moisture content needs to be quantified/specified to obtain repeatable/reproducible brake test results as the moisture is an unintended and uncontrolled ingredient of a friction material. As the disc surface roughness increases due to prior braking conditions, the friction coefficient of low-speed stops is found to decrease
Sriwiboon, Meechai, Koetniyom, Saiprasit, Rhee, Seong Kwan, Sukultanasorn, Jittrathep, Kaewlob, Kritsana, Kunthong, Jitpanu
Some Considerations for Brake-Based Park Systems, Including Residual Drag Impact2023-01-187811/5/2023
Brake-based park systems, where an electric parking brake system becomes fully responsible for vehicle immobilization and enables elimination of the traditional driveline-based parking pawl, has increased in popularity, especially in full Electric Vehicles. At face value, the promise of saving mass, cost, and critical packaging space in an electric drive unit is compelling. However, this must be weighed carefully against less obvious impacts, which include engineering in added redundancy, significant changes in “real world” duty cycle of EPB components, risk of brake pad and rotor crevice corrosion, and perhaps most acutely because it affects every drive cycle, the impact to residual drag and therefore vehicle energy use. The present work endeavors to present a balanced view of the considerations, both advantages and tradeoffs, for brake-based park systems, with a special focus on the residual drag behavior because it is perhaps the most difficult to characterize, most variable in its
Antanaitis, David, Harris, Maria Richelle, Connor, Kevin, Riefe, Mark
Simulated LACT Procedure for Predicting Lining Life for Vehicles with Regenerative Braking2023-01-189211/5/2023
The Simulated Los Angeles City Traffic (SLACT) test is a well-established dynamometer test procedure used to evaluate brake noise and lining wear performance under a typical US city driving conditions. This procedure is based on a vehicle test conducted on the roads of Los Angeles, California. Unlike ICE vehicles, in electric vehicles regenerative brakes do a significant amount of the work to stop the vehicle, resulting in less work required from the foundation brakes. This means that the life of a brake pad could significantly increase in electric vehicles. It is possible then to reduce the thickness of the brake pad to improve packaging and cost. However, in situations where regenerative braking is disabled due to a failure or low battery charge level, all the work must be done by the foundation brake with no support from the regenerative braking. Hence, it is crucial to select the optimal brake pad thickness for such scenarios. The SLACT test was designed primarily for ICE vehicles
Jayyousi, Wael, Divakaruni, Saikiran
Engineering Properties of Drum Brake Friction Materials2023-01-189011/5/2023
The rising popularity of EVs has led to a resurgence of interest in drum brakes. Drum brakes benefit from less complex mechanical design, have no residual brake drag, and the enclosed design is less susceptible to corrosion and debris emission. For the commercial EVs, the elimination of engine noise makes brake noise a major contributor to vehicle noise. With the renewed interest in drum brakes, there is an increased need for property data for NVH simulations to optimize noise performance. Similar to disc brakes, the modeling of drum brake performance requires a complete set of friction material engineering properties determined over the pre-loads and temperatures encountered in brake applications. Results are presented for eight different drum brake formulations and platforms. The measurement approach and data analysis parallels that used for the elastic property measurements of disc pad friction materials, SAE J2725. A complete set of elastic properties and engineer properties are
Yuhas, Donald, Vorres, Carol, Oleksak, Loretta, Divakaruni, Saikiran, Subramanian, Vijay
Optimization of Insulating Material Selection for Effective Squeal Noise Damping2023-01-187011/5/2023
Squeal noise phenomenon in disc brakes is a complicated dynamic challenge which brake manufacturers have confronted for decades. The most prevalent technique apprehended by the brake manufactures is to simulate the braking conditions using a noise dynamometer. This is a well-established, expensive technique which is time-consuming. The objective of this paper is to understand the phenomenon of brake squeal, modal coupling and publish an analytical approach to predict a suitable damping material and thereby to optimize the dynamometer tests and time. As the temperature increases the stiffness of the component decreases thereby the resonance frequency tends to decrease. Compressing the pad increases its stiffness and thereby its resonance frequency. Compressibility being inversely proportional to stiffness has direct influence over the frequency response function of the brake components. Shim suppliers use generic structure to obtain the damping ratio at its resonance at every other
Anand, Ramamoorthy, Kitchana, Venkatesh, Vasanth, Kannan
Brake Pad Moisture Adsorption and Its Effect on Brake Pad Compression Strain/Modulus and Friction Coefficient: Effect of Pad Cure Temperatures2023-01-186311/5/2023
The moisture adsorption kinetics of copper-free brake pads was studied to confirm an earlier finding that the adsorption weight gain follows a logarithmic relationship with respect to the square root of humidity exposure time and the relationship is linear in the beginning. When the pad cure temperature was raised from 120 to 180 and 240 °C, the adsorption rate increased. The 180 °C cure produced the highest pad modulus. With increasing moisture adsorption, the pad compression modulus increased just like the pad dynamic modulus, meaning decreasing compression/compressibility while the ISO ‘compressibility’ determined after 3 compressions under 160 bars increased in contradiction. It is concluded that the ISO ‘compressibility’ is a destructive hardness measurement like the Gogan or Rockwell hardness: the key difference is the indenter covers the entire surface of the pad. The true compressibility must be determined as an inverse function of bulk modulus. It is recommended that the pad
Rhee, Seong Kwan, Rathee, Aman, Singh, Shiv Raj, Kumar Sharma, Devendra
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