Browse Topic: Friction materials

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Clutch Thermal Adequacy Assessment in Repeat Restart Launch Condition on Gradient2026-26-0434To be published on 01/16/2026
The clutch is a mechanical device that engages and disengages power transmission from the engine to the wheels. It consists of the clutch disc assembly and cover assembly. The clutch disc, with friction material linings, is mounted on the transmission shaft and gets clamped between the flywheel and cover assembly to transmit power as required. However, wear and tear occur due to the differential speeds and slippage between the engine and transmission during operation. Clutch performance is assessed for its thermal behavior under repeat restart conditions on steep gradients, which is essential for the reliability and durability of commercial vehicle clutches. Repeat restart test is a key test to assess clutch performance on a 12% gradient. This test replicates real world scenarios, such as truck launches on hilly terrains under full load, where the clutch experiences significant slippage due to speed differences. This generates heat, and repeated engagements can cause the temperature to
Munisamy, Sathishkumar, Chollangi, Damodar, Mane, Sudhir
Niobium Alloyed Brake Disc for reduced NVH and emission control2026-26-0285To be published on 01/16/2026
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 technology to meet brake emissions requirements. The proposed process is to alloy the Gray Cast Iron with Niobium. The Niobium addition will reduce wear debris and improve NVH (Noise Vibration Harshness). The test methodology included: Manufacture of disc samples alloyed with Niobium, and 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
Barile, Bernardo, Holly, Mike
Investigation of Particulate Matter Emissions from Brake Pads of Light-Duty Vehicles: A Comparative Analysis of Friction Material Compositions2025-36-020012/18/2025
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Catão, Vítor Gustavo Gomes, Machado, Amanda Ribeiro, Fiorentin, Felipe Klein, Silva, João Pedro Anuto, Bernardino, Lucas Gabriel, Fiorentin, Thiago Antonio, Carboni, Andrea Piga
Study on the Clarification of the Mechanism of Scooter Centrifugal Clutch Squeal2025-32-002211/03/2025
A centrifugal clutch is used in many machines such as scooters, lawn mowers, outboard motor of boats, brush cutters, and so on. It may produce a shrill sound, similar to a brake squeal, when the clutch engages for starting. In this study, we have proved that this shrill sound, in another word, clutch squeal, is caused by the self-excited vibrations of the centrifugal clutch. And we have also clarified that the clutch squeal can be restrained by employing an asymmetrical shape for the clutch housing. The clutch squeal tends to occur when the centrifugal clutch becomes hot due to repetitive starting and stopping, which causes the friction coefficient of the friction material on the clutch shoe to increase. It is presumable that vibration on the clutch housing generated by the self-excited vibrations is the cause of the clutch squeal. In an attempt to clarify the cause of clutch squeal, we first measured the sound pressure of the clutch squeal and the vibration shapes of the clutch
Yamamoto, Kohei, Iwamoto, Tatsuya, Otsuka, Takashi
Thermal Performance Evaluation Methodology for Wet Clutch: Simulation and Testing Correlation2025-28-037210/30/2025
This paper describes a simulation methodology developed to predict the temperature distribution in separator plate and friction disc of the wet clutch corresponding to given slip power, oil flow rate and clutch geometry for off-highway applications. This study adopts a model-based design approach to understand thermal behavior of the wet clutch. This simulation methodology has been developed in a 1D environment with the right fidelity modeling approach to predict thermal performance of the clutch. This model includes heat flow through conduction and convection corresponding to heat generated due to friction between separator plate and friction material. Lab test includes multiple thermocouples installed on separator plate to capture temperature distribution in radial direction. This methodology has been correlated >90% with test data acquired in the lab. This dynamic simulation model aids to identify the potential root cause of clutch failures and risk mitigation. DOE has been
Kumar, Suneel, Memane, Nilesh, Veerkar, Vikrant
Development of an SSP-180 Synchronizer Durability Test2025-01-040810/07/2025
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
Glasgow, Michael B., Zreik, Khaled, Ezanno, Philippe Nicolas, Shelton, Robert W.
Influence of Titanate Composition and Particle Size on Friction Stability and Wear in Brake Pads2025-01-033709/15/2025
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
A Novel Framework for Elastic Constants and Damping Ratio Optimization of Friction Material in Brake Squeal Simulations2025-01-035009/15/2025
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
Philip, Rony, Muralidharan, Sudharsan, Mohanam, Gopalakrishnan
Achieving Euro 7 Compliance: Cost-Effective Brake Wear Particle Emissions and Performance with FNC-Smart ONC® GCI Rotors2025-01-033209/15/2025
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
Winter, Karl-Michael, Holly, Mike
Further Investigation of Disc Pad Compression Deformation during ISO Compressibility and Dynamic Modulus Measurements under Relatively Low Pressures2025-01-033409/15/2025
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 Materials2025-01-033609/15/2025
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
Effects of Moisture Behavior on Corrosion Stiction in Friction Materials2025-01-033309/15/2025
This study investigates the correlation between moisture behavior and corrosion stiction mechanisms in NAO friction materials. While previous studies on corrosion stiction have primarily focused on electrochemical approaches, this study aims to elucidate the mechanism by examining moisture behavior within the friction material. Although recent research has investigated changes in pad properties in humid environments, most studies have primarily focused on variations in pad stiffness and the friction coefficient. To date, no studies have investigated the behavior of moisture within pads using Fick’s Second Law and its impact on corrosion stiction. In this study, Fick’s Second Law was applied to model moisture behavior in friction materials. The diffusion coefficient and maximum moisture content were quantified, revealing that moisture behavior in the friction material can be divided into two distinct stages: one following Fick’s Second Law and the other not. For NAO friction materials
Choi, Nakcheon, Ju, Joungsu, Youn, Deokki
Development of a Laboratory Brake for a Flywheel Mass Test Rig for Variable Pad Sizes and Shapes with a Force Distribution Unit for Ideal Contact Pressure and a Topography Measurement System for In-Situ Recording of Surface Changes and Wear2025-01-033109/15/2025
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
Heuser, Robert Michael, Rosenthal, Tobias Richard, Wiest, Daniel Christian, Meyer, Henning Jürgen
SAE No. 2 Friction Test Machine 3600 rpm Stepped Power TestJ2487_202507 (Current)07/16/2025
This SAE Recommended Practice is intended as the definition of a standard test, but it may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. The specific purpose of this document is to define a 3600 rpm stepped power test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 3600 rpm and is intended as a standard procedure for common use by both suppliers and end users. The only variables selected by the supplier or user of the friction system are: a Friction material b Fluid c Reaction plates These three variables must be clearly identified when reporting the results of using
Automatic Transmission and Transaxle Committee
Thermal Swell, Growth, and Hot Compressibility of Brake Friction Materials and Noise InsulatorsJ160_202505 (Current)05/27/2025
This document specifies a universal method of measuring the thickness change of friction materials to determine the effects of temperature. The test applies to both disc and drum-type linings commonly used in hydraulic and air brake systems for automotive or commercial vehicle applications. This document describes several methods for thermal swell and growth. Method A is where the friction material is in contact with a heated surface to simulate the heat input to the pad that occurs during actual usage. Method B uses an oven to heat the freestanding material and is an approximate procedure requiring less instrumentation. Method A is recommended for disc brake pad assemblies, noise insulators, or flat coupons, while Method B is recommended for curved drum brake linings. This document also describes how to test the warmed-up disc brake pads and noise insulators for hot compressibility using Method A.
Brake Linings Standards Committee
A Nonlinear Characteristics Identification and Compensation Control Method for Electromechanical Brake System2025-01-881004/01/2025
Clamping force control in Electromechanical Brake (EMB) systems must overcome various nonlinear characteristics, such as motor distorted voltage, Back Electromotive Force (EMF), and actuator friction disturbances. Therefore, modeling and parameter identification of these nonlinearities are necessary. This paper first proposes a motor parameter identification method based on the mathematical model of a Permanent Magnet Synchronous Motor (PMSM). A combination of the Least Square Method and Particle Swarm Optimization (PSO) is used to stepwise identify both the electrical and mechanical parameters of the motor. The accuracy of the identified parameters is validated by comparing simulation results with test bench responses. The identified parameters are applied to design the motor Back EMF compensation module, the distorted voltage compensation module, and to tune the current loop parameters. Next, a lumped parameter friction model suitable for closed-loop clamping force control in EMB
Qiao, Le, Xiong, Lu, Zhuo, Guirong, Shu, Qiang
Material-Combined Vehicle Brake Disc Design for Enhanced Cooling Performance2025-01-818904/01/2025
The improvement of heat dissipation performance of ventilated brake discs is vital to braking safety. Usually, the technical approaches shall be material optimization or structural improvement. In this paper, a simulation model of the heat transfer of brake discs is established using STAR-CCM+ software. Cast iron, aluminum metal matrix composite (Al-MMC), and carbon-ceramic composite materials (C-SiC) are compared. The results show that: Al-MMC has better thermal conductivity so that a more uniform temperature gradient distribution shall be formed; C-SiC has poorer heat capacity yet, according to previous studies, it has better thermal stability, which is the ability to ensure its friction factor under high-temperature condition; cast iron performs better with convective heat transfer rate, which enhances the heat transfer between the surface and surrounding flow field. Based on the results, this paper proposes four types of material combined brake discs using different friction
Wang, Jiarui, Jia, Qing, Zhao, Wentao, Xia, Chao, Yang, Zhigang
A Comparative Study on the Working Efficiency of Journal Bearing Employing Different Micro-Textures04-18-02-001102/19/2025
This study proposed the different micro-textures of the SC (square cylinder), SWS (square wedge shape), HS (hemispherical shape), and CR (cylindrical round) to improve the working efficiency of the journal bearing. A hydrodynamic lubrication model of the journal bearing under the impact of the changing dynamic loads is established to analyze the performance of micro-textures. The maximum oil film pressure and minimum frictional force in the journal bearing are selected as two evaluation indices. Some outstanding research results show that all the SC, SWS, HS, and CR added on the bearing surface improved the working efficiency of the journal bearing better than without the micro-textures. Moreover, the HS also improved the working efficiency of the journal bearing better than other structures of SC, SWS, and CR. To optimize the working efficiency of the journal bearing using HS, the dimension ltex and depth htex of HS should be selected and designed in a range of 3.6 < ltex ≤ 3.9 mm and
Song, Fengxiang, Nguyen, Vanliem, Liu, Yaxi
Road Vehicles - Friction Materials - Finished Brake Pad Normalized Elastic Constant of Friction MaterialJ3175_202412 (Current)12/06/2024
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
Time for a Model Change - Inorganic Friction Materials2024-01-304209/08/2024
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
A Study on the Countermeasure to EURO7 Brake Dust Regulation Phase 12024-01-304909/08/2024
This is a case study to cope with the brake dust regulation of EURO7, countermeasures were listed, and evaluation and verification studies using C segment sports utility vehicle were conducted on them. Through this phase1 study, it was most reasonable to apply hard metal cladding disks and metallic friction material to front brake and apply friction materials as NAO with less dust generation to rear brake. This was because it is possible to satisfy new regulations without deteriorating the required performance in Europe. However, it is necessary to develop detailed specifications of discs and friction materials to satisfy our braking development goals for European models in the Phase 2.
Kim, Yoon Cheol, Kim, Jwa Kyum
Objectively Quantify Creep Groan and Dynamic Grunt Performance of Different Brake Friction Materials2024-01-303509/08/2024
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
Enhancing Brake Performance: FNC-Smart-ONC® Technology to Address Corrosion Challenges and Extend the Durability of GCI Rotors2024-01-304409/08/2024
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
Niobium Alloyed Ferritic Nitrocarburized Brake Rotors2024-01-303109/08/2024
Niobium (Nb) alloyed Grey cast iron in combination with Ferritic Nitrocarburize (FNC) case hardening heat treatment is proposed to improve wear resistance and reduce brake dust generation of brake rotors. Standard Eutectic and Hypereutectic Grey irons alloyed with Niobium were evaluated in comparison to baseline unalloyed compositions. Brake speed snub sensitivity tribological testing was performed on a matrix including Niobium alloyed, Unalloyed, FNC, Non FNC, Non-Asbestos Organic (NAO) friction and Low metallic (Low Met) friction materials. Full size brake rotors were evaluated by Block Wear and Corrosion Cleanability. Improved wear, corrosion resistance and reduced brake dust debris were demonstrated by the Niobium alloyed FNC brake rotor combinations. Corrosion is an important consideration when evaluating brake performance. Combining cyclic corrosion and brake rotor testing provides the best comparison with field exposure.
Holly, Mike
Development of Brake Shoe with Carbon Footprint Reduction2024-36-031108/09/2024
Considered one of the greenest forms of transport, the rail industry is at an exciting point pursuing several key initiatives to decarbonise its operations, assets, and supply chains. Therefore, having a brake shoe with a lower carbon footprint is essential for achieving the goals related to decarbonizing the operation, as it is a wear item. For this purpose, a carbon footprint measurement methodology was applied to the development of a friction material for railway brake shoes in order to reduce the carbon footprint generated in the production of the material, combining a sustainable material with greater durability in operation, thus reducing the total cost of ownership. In order to assess the advantages of the new product, a comparative analysis was carried out of the carbon footprint of the conventional shoe and the new railway shoe proposal, both used in the same application, considering the performance and environmental impact of each raw material and stage of the production
Casagrande, R.B., De Souza, A.R.A., Finimundi, A.V., Pereira, C.H.S, Masotti, D., Rombaldi, R.J., Gotardo, T.
Thermal coupled structural analysis of a brake disc2024-36-030508/09/2024
Designing a brake disc is a very challenging job. Besides to being a key item in vehicle safety, we are referring to a product that goes through several manufacturing processes and during its application it is exposed to extreme conditions of mechanical stress, temperature and vibration. The raw material for a large portion of commercial brake discs is normally gray cast iron with the possibility of adding alloy elements. This material is characterized by having high resistance to wear due to friction and having practically zero plasticity. As it is a material without a plastic working regime, it is very important to properly size the product for use, once the material’s resistance limit is reached, a catastrophic failure in operation may be inevitable. Quality control systems in casting and machining have great importance in the development of the disc, but physical tests are always essential in this type of product. Dynamometer tests are great options for validating brake discs, due
Deckmann, Jardel Luis, do Nascimento, Vagner
Microstructural Analysis and Tribological Performance of Composite Iron Sulfides in Automotive Brake Pads2024-36-032208/09/2024
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 Conditions2024-01-504904/24/2024
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
The Influence of Torsional Vibrations on the Longevity of Manual Transmission Synchronizers and the Durability of Clutch Dampers2024-01-501001/25/2024
This study delves into the impact of engine torsional vibration on transmission component failures, specifically synchronizers and clutch damper springs. Synchronizers are crucial in ensuring smooth gear shifts by synchronizing the rotational speeds of the transmission input and output shafts. While design factors such as geometry, friction material, and lubrication are often attributed to synchronizer failures, engine-generated torsional vibrations significantly affect their lifespan. Clutch damper mechanisms integrated into the clutch disc are designed to mitigate these vibrations. This research employs 1D powertrain simulation modeling to predict powertrain torsional vibration behavior. Additionally, rig tests are conducted to simulate vehicle-level angular accelerations and examine the impact of torsional vibrations on synchronizer life. The results provide valuable insights into optimizing clutch damper design to effectively dampen vibrations and prolong transmission component
Jagtap, Amol, Rudramath, Sagar, Chollangi, Damodar, Bhandari, Kiran
Power Cylinder Effects on Friction and Fuel EconomyJ2904_202401 (Current)01/22/2024
This document covers the mechanisms from the power cylinder, which contribute to the mechanical friction of an internal combustion engine. It will not discuss in detail the influence of other engine components or engine driven accessories on friction.
Piston and Ring Standards Committee
Brake Pad Life Monitoring System Using Machine Learning2024-26-003201/16/2024
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
Reliability Prediction and Demonstration for Wear Failure Mechanism2024-26-032301/16/2024
Wear phenomenon has extensively been published in the literature and this paper presents a methodology of how the wear models were used to assess the risk of failures in a field application, through endurance testing at a system level. Correlation of the wear prediction by the model with actual measurement was performed and used to predict the field operation reliability. Results are shown for sliding wear as well as impact wear phenomenon in this paper. In the case of sliding wear, wear modeling and prediction was done for a friction material using a system level metric, and the mean wear predicted was not different from the model predicted values at 95% confidence under a field application duty cycle.
SR, Ranjith Kumar, Soma, Nagaraju
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
Low-Speed Continuous Slip SAE No. 2 μPVT ProcedureJ2964_202311 (Current)11/15/2023
This SAE Recommended Practice is intended as the definition of a standard test, which may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 friction test is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluid combinations. The specific purpose of this document is to define a µPVT test for the evaluation of the variation of wet friction system low speed slip characteristics as a function of speed, temperature, and pressure. This procedure is intended as a suggested method for both suppliers and end users. The only variables selected by the supplier or user of the friction system are: Friction material Fluid Reaction plates Oil flow (optional) These four variables must be clearly identified when reporting the results of this test. If any of the test parameters or system hardware as described in this document are changed
Automatic Transmission and Transaxle 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 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 Noise2023-01-186211/05/2023
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
Reproducibility of Physico-Chemical Properties in Brakes Emissions Generated at Different Dynamometric Benches2023-01-187711/05/2023
In recent years, brakes emission tests have become increasingly standardized to meet progressively stricter intra and inter laboratory reproducibility requirements. In particular, following the recent EURO 7 regulation proposal, WLTP-Brake cycle has surged as EU standard braking sequence to determine emission factors of investigated brake systems. Furthermore, the UN GTR (United Nations Global Technical Regulation) on Laboratory Measurement of Brake Emissions for Light-Duty Vehicles collects all the information needed to perform emission tests in laboratory. This includes design specifications for the testing platforms as well as the typology and configuration of measuring instruments. Notably, laboratory emission tests are also increasingly used to collect particulates for chemical characterization, since the compositional information is crucial to: i) provide correct assessment of their toxicological and environmental behavior; and ii) better understand tribological and emission
Mancini, Alessandro, Tsyupa, Bozhena, Della Bella, Pietro, Russo, Simone, Martinelli, Elia, Leonardi, Mara, Belotti, Stefano, Hense, Maximilian, Niemann, Hartmut, Bertasi, Federico, Bonfanti, Andrea
Engineering Properties of Drum Brake Friction Materials2023-01-189011/05/2023
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
Experimental Investigation of Tribochemical Processes in Frictional Contacts Using a Pin-on-Disk Tribometer2023-01-188911/05/2023
Friction in tribological systems can lead to significant energy consumption and wear. While there are several dissipation mechanisms in the frictional boundary layer, the role of chemical processes is not fully understood. The aim of this study is to investigate the influence of chemical reactions on the tribological behavior of sliding friction pairs. In order to carry out initial analyses, minimal mixtures with a few simple components and epoxy resin as a binder are developed, produced and used. A series of experiments are performed on a pin-on-disc tribometer with different minimal mixtures. Temperature and friction coefficient are measured throughout the friction process, and the rubbed surface of the samples is measured in situ. Three types of chemically inert minimal mixtures are developed in the first phase of the experiment. In the second phase of the experiment, copper powder is added to all minimal mixtures to study the influence of copper oxidation as the main chemical
Fang, Chengyuan, Ostermeyer, Georg-Peter, Schiefer, Frank, Schilde, Carsten, Lehmann, Christina, Bräuer, Günter
Dynamometric Investigation on Airborne Particulate Matter from Brake of Automobile: Impact of Disc Materials on Brake Emission Factor2023-01-186111/05/2023
Non-exhaust airborne particulate matter (PM) from automobiles might lead to potential adverse effects on the respiratory system. In this work, we evaluated the impact of surface properties of disc rotors on brake wear PM emission for passenger vehicles. Dynamometric measurements using the novel cycle were made for gray cast iron (GCI), nitrocarburized (NC), and superhard ceramic coated (SCC) disc rotors using non-steel (N/S) friction materials. The brake emission factors (BEF) for the GCI and NC disc rotors ranged from 1.76 to 1.74 mg/km/vehicle, whereas that of the SCC rotor exhibited a much-reduced value of 0.50 mg/km/vehicle. As the hardness of the SCC rotor increases (> 1150 HV), lower BEF was obtained, whereas the coefficient of friction (COF) of the SCC disc was more than 20 % higher than the NC rotor. Temperature-dependent data indicated that disc temperature (Tdisc) for the SCC disc (~115 °C) was lower than that for the GCI and NC (Tdisc >130 °C).
Jeong lng, Mu Hyeok, Lee, Jungju, Choi, SungWoo, Sung, Sanghun, Kim, Jong-Young, Oh, Yoonsuk, Pee, Jae-Hwan
Brake Pad Moisture Adsorption and Its Effect on Brake Pad Compression Strain/Modulus and Friction Coefficient: Effect of Pad Cure Temperatures2023-01-186311/05/2023
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
Sound Source Identification of In-Plane Squeal of Disc Brakes Using Array Microphones and Its Verification by Acoustic Simulation2023-01-186911/05/2023
As the vehicle electrification progresses and the demand for acoustic comfort increases, the NVH performance of brakes becomes more important theme. In-plane squeal of disc brake is one of phenomena that is difficult to countermeasure. In this study, we used array microphones to search for sound sources of in-plane squeal in order to elucidate the mechanism. The Microphones were set in the out-of-plane direction and the lateral direction of a disc in brake components on a full-sized dynamometer. In the vibration mode in which in-plane stretch vibration was dominant, the sparse and dense parts showed high sound pressure. 3D laser vibrometer was used to check displacements of the disc, and the result indicated a possibility that the sparse and dense parts could vibrate in the out-of-plane direction and generate the sound. Then, complex eigenvalue analysis (CEA) and acoustic simulation were conducted to validate the experimental results. Firstly, frequency of instability mode occurred in
Tanamachi, Shuhei, Millsap, Tom, Yamaguchi, Yoshiyuki
Desorption of Brake Friction MaterialsJ3281_202305 (Current)05/10/2023
This SAE Recommended Practice specifies a method to reduce and stabilize the moisture of products containing brake friction material (disc brake pads, drum brake shoes, friction blocks) so the parts are conditioned and maintained in a stable low moisture state.
Brake Linings Standards Committee
Root Cause Analysis of Limited Slip Differential Noise Vibration Harshness2023-01-113805/08/2023
The primary objective of this research was to identify the root cause of limited slip differential (LSD) NVH. The study examined the significance of different oils and additives that make up the lubrication mix in the axle. The impacts of gear marking compound type, friction modifier type, gear marking compound level, friction modifier level, reaction plate surface finish roughness, and friction material type were studied using Taguchi's Design of Experiment. Eaton's Vertical Friction Tester (VFT), a sub-system level test stand, was used to measure the performance characteristics of the clutch pack and oil mix. Sequential approximation and cumulative analysis methodologies were used to analyze test data where NVH was beyond the measurement capacity of the test stand. The DOE analysis showed that the type of gear marking compound used to set the ring gear mesh during axle build had the most significant influence on NVH levels.
Sarkar, Subrata, Samuelson, Eric, Allen, Jordan, Spiekermann, Ryan
Road Vehicles - Friction Materials - Elastic Properties MeasurementsJ2725_202304 (Current)04/21/2023
This SAE Standard specifies a method for testing and measuring elastic constants in friction materials by precise ultrasonic velocity measurements. Measurement methods are also described for measurement of the out-of-plane modulus as a function of pre-load as well as the measurement of engineering constants as a function of temperature. Finally, methods are formulated to produce all engineering constants as a function of pre-load and temperature.
Brake Linings Standards Committee
Correlated Simulation of Pseudo Transient Torque Converter Clutch Engagement Using Coupled Fluid Structure Interaction2023-01-045704/11/2023
This investigation utilizes a correlated fluid-structure interaction (FSI) model of the torque converter and clutch assembly to perform a pseudo transient clutch engagement at steady state operating conditions. The pseudo transient condition consists of a series of nine steady state simulations that transition the torque converter clutch from fully released to near full lockup at a constant input torque and output speed representative of a highway cruising speed. The flow and pressured field of the torque converter torus and clutch are solved using a CFD model and then passed along to a transient structural model to determine the torque capacity of the lockup clutch. Bulk property assumptions regarding the friction material, deformation of the clutch plate, and deflection of supporting structures were made to simplify the model setup, run time, and solution convergence. Telemetry pressure measurements acquired in an operating torque converter under similar operating conditions on a
Beldar, Aniket, Robinette, Darrell, Blough, Jason
Tribological Performance of Brake Friction Composites with Sb 2 O 3 Pre-blended with Metal Sulfide2022-28-057512/23/2022
The brake friction composite in brake pad plays a crucial role in converting the energy by absorbing the frictional shear load against the rotor. During the braking action, the brake friction composite maintains a stable coefficient of friction in all adverse conditions. The metal sulfide plays a significant role in stabilizing the coefficient of friction as they oxidized at elevated temperature at the interface. The research work evaluates the tribological performance of the brake pads developed with the mixture of pre-blended metal sulfide and Sb2O3 in varying wt.% such as 3, 5 and 7% in a standard friction material formulation. The brake friction composites are fabricated with the compression moulding technique. The tribological properties of the fabricated samples are evaluated by SAE J661a standards. The worn surfaces are characterized by SEM to understand the wear mechanism. The sample with 5 wt.% of the Sb2O3 exhibited the overall best performance compared to the other samples
K, Sathickbasha, B, Surya Rajan, P, Hariharasakthisudhan, Chandramohan, Sivakumar, K J, Nagarajan, COTILLI, FRANCESCO, P, Balaji
Low-Speed Continuous Slip Durability TestJ3210_202211 (Current)11/22/2022
This SAE Recommended Practice is intended as the definition of a standard test, which may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. This SAE No. 2 friction test monitors the µ-v curve for a negative slope which can be used to evaluate a wet clutch system (WCS) anti-shudder performance and can be used for any wet driveline mechanism. WCS shudder is considered a clutch failure condition. The cause of shudder is consistent with glazing as the primary failure mode. It has been shown that a substantial loss of the wet friction material surface porosity leads to a glaze forming on the friction material surface. This process typically leading to a negative dµ/dv slope over time as addressed in SAE 2020-01-0560. This procedure includes evaluation friction characteristics of wet clutch stystem (WCS) at various specific pressures, speeds, and temperatures, and an extended durability duty cycle test to
Automatic Transmission and Transaxle Committee
Drum and Disc Brake Static Performance Test EquivalencyJ3192_202210 (Current)10/13/2022
This SAE Recommended Practice is intended for measuring the static brake torque performance of a pnuematically actuated brake assembly, friction material, and drum/disc combination on an inertia brake dynamometer.
Truck and Bus Brake Systems Committee
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