Browse Topic: Brake pads

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Snowmobile Service Brake SystemJ44_202103 (Current)3/16/2021
This SAE Standard establishes a uniform testing procedure and performance requirements for the level surface testing of hand-operated service brake systems on snowmobiles.
Snowmobile Technical Committee
Validation of Compressibility Test Systems for Friction MaterialsJ3079/1_202101 (Current)1/13/2021
This SAE Recommended Practice (RP) applies to the validation process for test systems used to measure deflection (compressibility, creep, or swell and growth) of friction materials and friction material assemblies. The materials or assemblies can fit passenger cars, light trucks, and commercial vehicles equipped with hydraulic or air brake systems, using disc or drum brakes.
Brake Linings Standards Committee
Air Brake Performance and Wear Test Code Commercial Vehicle Inertia DynamometerJ2115_202008 (Current)8/20/2020
This SAE Standard provides test procedures for air and air-over-hydraulic disc or drum brakes used for on-highway commercial vehicles over 4536 kg (10000 pounds) GVWR. This recommended practice includes the pass/fail criteria of Federal Motor Vehicle Safety Standard No. TP-121D-01.
Truck and Bus Foundation Brake Committee
Measurement of Copper and Other Elements in Brake Friction MaterialsJ2975_202007 (Current)7/23/2020
This procedure describes a method for generating, preparing and analyzing samples of new and unused brake friction materials for their chemical constituents.
Brake Linings Standards Committee
Low-Duty Inertia Dynamometer Hydraulic Brake Wear Test Procedures for Vehicles Above 4536 kg (10000 pounds) of GVWRJ3006_202005 (Current)5/26/2020
This Recommended Practice is derived from OEM and tier-1 laboratory tests and applies to two-axle multipurpose passenger vehicles, or trucks with a GVWR above 4536 kg (10 000 pounds) equipped with hydraulic disc or drum service brakes. Before conducting testing for a specific brake sizes or under specific test conditions, review, agree upon, and document with the test requestor any deviations from the test procedure. Also, the applicable criteria for the final test results and wear rates deemed as significantly different require definition, assessment, and proper documentation; especially as this will determine whether or not Method B testing is needed. This Recommended Practice does not evaluate or quantify other brake system characteristics such as performance, noise, judder, ABS performance, or braking under extreme temperatures or speeds. Minimum performance requirements are not part of this recommended practice. Consistency and margin of pass/fail of the minimum requirements related to wear rates and wear behavior can be assessed as part of the project in coordination with the test requestor. NOTE: This Recommended Practice uses the unit conversion and rounding techniques from the NIST Special Publication 811. This to ensure the use of standard conversion factors and to determine the appropriate number of significant digits to ensure the Rounding Error (RE) of the converted unit is smaller than or similar to the RE of the original English or Imperial unit.
Truck and Bus Hydraulic Brake Committee
Model-Based Brake Disc Temperature Prediction on High Speed Testing Mode and Circuit2020-01-02144/14/2020
A brake is a mechanical device that inhibits the motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by friction energy. Commonly, most brakes use friction between two surfaces pressed together to convert the kinetic energy of the moving object into heat, though other methods of energy conversion may be employed. If braking is repeated or sustained in high load or high-speed conditions, the motion will be unstable and can lead to a loss of stopping power because the disc capability for braking is not enough. These phenomena are generally defined as brake fading. Brake fade is caused by an overheating brake system. This paper describes the thermal modeling and process to predict the disk temperature under a condition which causes the fade characteristics. Also, the model of disc temperature prediction developed with consideration of acceleration and deceleration from the vehicle specification by combining the full vehicle modeling with thermal disc model. The disc temperature model is a highly reliable model because it is correlated with measurement data and based on this correlated thermal model, it can be predicted the brake disc geometrical parameters according to the specification change of the vehicles in the concept stage before the prototype development.
Jeong, PilYoung, Lee, Jaekil, Oswald, Mario, Kellner, Stefan
Flow Field Experimental Study in Brake Discs with Aerodynamic Ventilation Columns06-13-01-00042/27/2020
This work presents a new design of ventilation pillars in ventilated brake discs. The use of National Advisory Committee for Aeronautics (NACA) aerodynamic profiles is proposed. Of the references consulted, there is no standard or procedure that indicates how the pillars should be installed in the ventilated discs. Therefore, it is proposed using the Kaplan’s error triangles theory of turbo hydraulic machinery to have a geometrically orderly way of placing the NACA 66-209 profiles from the suction diameter to the discharge diameter. To validate this new design, a 1:1 scale acrylic disc model was constructed, and tests were conducted in water using the particle tracking velocimetry technique to characterize the water model. The water experiment was performed at test speeds of 35, 41, 48, and 54 rpm. From the experiment in water, it is possible to visualize the flow field from the suction diameter to the model discharge diameter and scale the results to the prototype in air. Being 54 rpm in water equivalent to N = 1020 rpm in air, the radial velocity is 15.4% higher than a straight vanes disc. In addition, comparing the mass flow at the point of maximum speed, it is observed that the results obtained in this work are 40.21%, 65.49%, and 98.11% higher than those obtained by other works. Finally, the error of the accumulated experimental bias is extremely low, where the maximum error did not reach 1.17%. For this reason, it can be ensured that both the measurements made as well as the results obtained are highly reliable.
Rivera López, Jesús Eduardo, Gutiérrez Paredes, Guadalupe Juliana, Quintero Orozco, Abner, Tamayo Meza, Pedro Alejandro, Orozco Durán, Gabriela Esmeralda, Arciniega Martínez, José Luis
Regressions of brake pads compressibility from experimental data2019-36-00141/13/2020
One of the critical characteristics in a brake pad is its deformation when subjected to compressive loads. This deformation is called compressibility, which can be obtained quantitatively through compression cycles performed by a specific test bench. However, such testing is costly and long enough not to meet the demand of manufacturers of friction materials. To overcome this difficulty, this work presents regressions for the estimation of compressibility through the natural frequencies of the pads, since they can be obtained quickly and at low cost through a simple modal analysis. The theoretical basis for the correlation between compressibility and natural frequencies includes the theory of elasticity - which defines an inverse relationship between strain and stiffness - and the theory of vibrations, which defines the natural frequencies of a mechanical system as a function of its mass matrices and stiffness. Since the dependent variable (compressibility) and explanatory variable (natural frequency) are linked to stiffness, it is theoretically plausible to direct estimative. As additional explanatory variables, in addition to the experimental data of natural frequencies, the work uses the mass values and the temperature during the natural frequency measurement to improve the regression models.
Suetti, André Garcia Lima
Influence of Pads and Brake Disc wear on Brake Squeal Noise2019-36-00051/13/2020
The present work aims to investigate the influence of wear of the pads and brake disc on the brake squeal behavior with the help of the Finite Element tool. Brake discs basically work by the pressure of the brake pads against a rotating disc. The friction between the pads and the disc causes the latter to decelerate, but it can also cause dynamic instabilities of the system giving rise to noises. Among the main noise in vehicle brake systems, there is the squeal noise, which is usually associated with the coupling of two neighboring natural modes. One possible way to identify unstable modes is by extracting complex eigenvalues from the system. An unstable mode can be identified when, in the result of the extraction of the complex eigenvalues, the real part of the eigenvalue is positive. In the present work, a brake system (disc and positioned pads and their respective materials and friction coefficients) was duly modeled and validated. The validation was done by means of a correlation between the frequency of the noises found experimentally and the frequency of the unstable modes found in the virtual model. A parametric analysis was performed simulating the wear of the disks and pads to understand the effect of the mass variations and stiffness on the instability of the system. According to the results found in the analyzes that simulate the wear, with the decrease, mainly the thickness of the brake pads, there was an increase of numbers of unstable modes, that is, the brake system is more prone to squeal generation.
dos Anjos, Marco Túlio Batista, Gutiérrez, Juan Carlos Horta, Ferreto, Cláudio Junior, Silva, Felipe Dornellas, Donadon, Lázaro Valentin
Brake noise analysis on tractive axle of 6x2 tractor vehicle2019-36-00081/13/2020
This study aims at analyzing the causes of noise in a heavy vehicle brake system (6x2 tractor) and proposing solutions to improve comfort during braking as it is known that, during the activation of the automotive brakes, noise can be generated in different frequency bands that can cause discomfort to the user and the study of how to reduce it is considerably important to bring more comfort in its use. As a working methodology, firstly, comparative analysis of dimension and material were performed between the axle assembly that presented noise and another axle assembly of a vehicle with no noise adopted as reference. This information was used as the basis for the frequency and acceleration virtual analysis that were validated with vehicle instrumentation and data acquisition. In parallel, vehicle tests with different brake friction materials were conducted. The answers of the dimension and material analysis from the axles assemblies highlighted the specificities of each of them but did not show great influence in the observed noise incidence. The vehicle instrumentation and data acquisition besides validate the virtual data, also showed the system amplitude of vibration which, through comparative tests with the same vehicle with the reference axle and similar vehicles, showed high variation in the acceleration and amplitude of vibration. The vehicle tests with different brake friction material varied the stiffness of the brake system, however, showing no evolution in its integrality but causing the noise at different braking pressure of the presented in those conditions. It is concluded that the difference between the axles assemblies is the assembly of the brake system “S” cam axle which, when actuated, has the rotation contrary to the wheel rotation, which can originate the variations in the acceleration and amplitude of vibration verified in the data acquisition and, therefore, may influence in the noise appearance.
Fortuna Pizzi, Rafael, Soares Júnior, Getúlio, Tonetti Anselmo, Pablo, Do Nascimento, Vagner, dos Santos, Roger Lusa, Severo Antunes, Diego, Masotti, Diego, Horta Gutierrez, Juan Carlos
Road Vehicles - Friction Materials - Finished Brake Pad Normalized Elastic Constant of Friction MaterialJ3175_201911 (Current)11/20/2019
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
Analysis of Metal Pick-Up Formation Process within Automotive Brake Pad05-13-01-000311/19/2019
Metal Pick-Up (MPU) is a problematic phenomenon in automotive disc brakes. MPU generally forms as some metal lumps on the surface of the brake pad. If brake pads have MPU, during braking they would cause grooving of the disc rotor, generating brake noise and deteriorating the performance of the brake. The previous literature has so far reported that the source of the MPU is an Fe component from a disc rotor or brake pads. However, only a few of the generation mechanisms of MPU have been proven. We investigate MPU to completely elucidate the mechanism of MPU generation by using different analyses than the previous literature. First, to find out the source of MPU generation, we focus on the chemical reaction of a certain component with wear debris during braking, and some of the verification experiments are conducted under the conditions of simulated friction interface. Second, to clarify the change in the form of the MPU growth process, the crystal structure of MPU is analyzed in detail by using the world’s largest synchrotron radiation facility (SPring-8). The results in this study reveal new facts about the source of MPU generation and the MPU growth process that have so far only been supposed.
Noda, Hirokazu, Takei, Takahiro
Fatigue Life Prediction of Heavy Duty Automobile’s Brake Drum through Coupled Thermo-Mechanical Analysis2019-28-003110/11/2019
The aim of this paper is to demonstrate the methodology to simulate the induced stresses/strains due to thermo-mechanical loading of automobile brake drum.. The brake drum undergoes mechanical load due to applied brake pressure and thermal load due to friction generated between brake pad and brake drum while brake is applied. This coupled thermo-mechanical loading affects the life of the brake drum as the stiffness of the brake drum is reduced. The conventional method of simulating this problem is done using Lagrangian discretization in which the load is applied and inertia effect due to angular velocity is applied to a drum at static condition. In contrast, in this paper Eulerian discretization is adopted for finite element analysis, in which drum brake model is discretized as spatially dependent that facilitates actual rotation of brake drum with simultaneous application of brake load resulting more precise simulation. A sequentially coupled transient thermo-mechanical analysis is carried out using ABAQUS 6.12 simulation tool to predict the induced stresses/strains and fatigue life of the brake drum.
Annamalai, Krishnamoorthy, Naiju, Chooriyaparambil Damodaran
The Improvement Brake’s Qualities of Vehicle by Developing the Method of the Choosing Frictional Pairs of the Brakes Mechanisms2019-01-21459/15/2019
One of the reasons for the large number of road accidents on highways in Ukraine [1] is the instability of the braking properties due to the unstable characteristics of the brake mechanisms’ friction pairs. The manufacturer produces new automobiles with installed brake pairs (brake pads and their counter bodies), which have passed long-term tests for the stability of the friction coefficient and braking forces distribution of between the axles. This ensures the compatibility of the friction pairs characteristics for front and rear brake mechanisms according to the criteria of heat resistance. During operation, instead of worn-out brake pads, brake discs and drums, drivers can purchase new ones, manufactured as spare parts. However, in the well-known literature there are no methods that allow to check the compatibility of the friction pairs characteristics for front and rear brake mechanisms according to the criteria of heat resistance. In the article a method for choosing a set of friction pairs of brake mechanisms for passenger car during operation is proposed. Assessment of the compatibility of the friction pairs characteristics for front and rear brake mechanisms was carried out according to the criteria of heat resistance.
Podrigalo, Mikhail, Klets, Dmytro, Kholodov, Mykhailo, Bogomolov, Viktor, Turenko, Anatoliy, Molodan, Andrii, Rudzinskyi, Volodymyr, Tarasov, Yurii, Mykolai, Aloksa, Hatsko, Vasyl
Objective Method for Crack Detection in Brake Friction Material2019-01-21139/15/2019
Friction material manufacturing is a complex process where numerous raw materials are mixed, pressed, and cured to make brake pads. It is important to have a consistent manufacturing process that can produce a brake pad that satisfies the vehicle braking requirements. A basic and critical requirement for any brake pad is structural integrity with no internal cracks. In this work a series of processing changes were made to intentionally produce internal cracks in the friction material. Various pad crack detection methods were studied, and their advantages and disadvantages are discussed in detail. One of the crack detection methods used an ultrasonic measuring instrument which gives objective data in the form of calculated modulus of elasticity and signal loss. The details of the machine and how the measurements are obtained are discussed. The modulus calculation is also described. Additionally, random pads with and without cracks were selected and checked using subjective and objective crack detection methods. The comparison analysis is discussed, and authors were able to show the difference between cracked and non-cracked pads using several methods. Conclusions and recommendations are made based on the data from these studies.
Divakaruni, Saikiran, Yuhas, Donald, Vorres, Carol, Kaatz, Richard
Squeal Noise Improvement by High Damping & High Stiffness under Layer Material2019-01-21119/15/2019
The purpose of this research is to clarify how damping characteristics of Under Layer (hereafter “UL”) material in the brake pads (hereafter “PAD”) influences brake squeal noise performance. In this study, UL material structure and dynamic viscoelasticity, for two different types of UL formulations are investigated. In addition, PAD damping ratio and squeal noise performance for multiple UL formulations are verified. As a result, the raw material orientation is determined based on manufacturing method, and it causes the UL material’s anisotropic properties. Dynamic viscoelasticity are dependent on the direction in which they are measured. In particular, the loss modulus, which is the damping element of dynamic viscoelasticity, is higher in the direction of the raw material orientation for the high damping and high stiffness UL formulation. In addition, it was confirmed that this loss modulus in the direction of the raw material orientation is effective for bending vibration. In the verification, the study focuses on the PAD damping ratio and squeal noise performance in the 1st bending vibration of the PAD. It is clarified that the PAD damping ratio increased as the loss modulus increases, which leads to improve squeal noise. In conclusion, this research proves that the high damping and high stiffness UL material is effective for squeal noise improvement.
Nishioka, Masato, Johnson, Leanne, Rosalez, Sean, Suzuki, Shusuke
Frequency Inspection of Brake System Components2019-01-21179/15/2019
Frequency inspection has long been a tool utilized by manufacturers of brake system components as a means of quality control. This is important to combat perceived defectiveness of a system that experiences issues, such as brake squeal, as well as to identify actual defects in the parts going out to customers. Every component has its own resonance frequencies based on the dynamics of that component. Knowledge of the resonance frequencies of each component provides insight that can prevent manufacturers from sending out defective units, whether they be perceived defects or actual defects. NVH engineers who understand these phenomena perform theoretical analysis and acquire experimental data in the lab to gain insight into their parts that will eventually be produced on the assembly line. Unfortunately, the frequency requirements, and the consequences thereof, defined by the NVH engineers can still remain somewhat of a mystery to the manufacturing engineers who are tasked with applying them. Oversights in specifications can lead to avoidable scares that lead to delays and downtime. For example, differences in accelerometer placement on a brake rotor from the lab to the assembly line can lead to issues such as variable frequency reporting. This leads to inaccurate data reporting, which leads to poor Gage R&R. A basic understanding of vibration and how to analyze data would allow the manufacturing engineer to troubleshoot such an issue and prevent unnecessary delays. This paper will attempt to take these concepts beyond the specification sheet and into the science and mathematics behind the dynamics of the different components of the total brake system. The knowledge gleaned from this analysis allows for intelligent decision making for go/no-go on the production line, as well as root cause analysis in the lab.
Cagle, Robert
Brake Rotor Corrosion and Friction Cleaning Effect on Vehicle Judder Performance2019-01-21159/15/2019
Brake disc corrosion has emerged as an important field of study within the automotive industry due to the wide range of lining materials that are currently used worldwide, and their inherent rust-cleaning properties. The presence of oxide layers irregularly deposited on the cast iron disc surfaces usually leads to a forced, braking-induced vibration that can reach the driver’s position as a pronounced annoyance. Hence, the friction material composition directly impacts on the judder performance during the early corrosion-removal stage. This study incorporates both dynamometer and vehicle tests into the definition of a predictive methodology that allows corrosion-induced vibrations to be investigated at both system and vehicle levels. The oxide film is artificially generated by means of a salt spray chamber under steady-state climate conditions in order to guarantee a repetitive and robust procedure. The vibration response of the system is objectively evaluated in the form of caliper accelerations and pressure (BPV) / torque (BTV) oscillations throughout a reduced rust-removal test sequence composed of 30 snubs; basic spectral and order analyses are conducted with the gathered data. Furthermore, vehicle-based results are correlated with the subjective ratings that an expert driver gives to the different vibrations perceived at chassis level. The in-service roughness of the oxide layer, on the other hand, is indirectly monitored by using a couple of non-contacting capacitive sensors that measure the variation in disc thickness (DTV). Ultimately, this paper is intended to characterize the inherent corrosion-cleaning capability of different friction materials -paying special attention to the presence of copper-, as well as revealing their impact on the vehicle judder subsequently induced during the actual removal of the oxide layers.
Molina Montasell, Narcís, Ferrer, Bernat
Divergence of Thickness Loss vs. Weight Loss, Friction and Wear Behavior of Heavy Truck Brake Blocks: Development of a New Test Procedure for the Chase Tester2019-01-21079/15/2019
Heavy truck brake blocks are found to swell (or expand) permanently during testing or usage, especially so at high temperatures, thus leading to longer durability as measured by thickness loss, similar to light vehicle disc pads. This swelling phenomenon occurs continuously in the layer adjacent to the friction surface during testing or usage; not a one time event. The thickness loss estimated from the weight loss is always greater than measured thickness loss. Brake block wear does not increase linearly with increasing normal load, and the load-sensitivity of block wear is very much dependent on the products. A new test procedure has been developed for generating friction-vs.-temperature and wear-vs.-temperature data at a constant temperature employing intermittent braking on the Chase Brake Lining Quality Tester (SAE J661) and friction material wear can be compared on equivalent-work basis.
Rathee, Aman, Sharma, Devendra Kumar, Singh, Shivraj, Rhee, Seong Kwan
A Study on the Optimum Reduction of Required Brake Fluid Level for Improvement of the High Speed Continuous Brake Distance2019-01-21219/15/2019
The high speed continuous braking distance assessment is the worst condition for thermal fades. This study was conducted to investigate the relationship between fade characteristic and friction materials & brake fluid amount for improving braking distance. So, we used the dynamometer to measure the friction coefficient, braking distance and required brake fluid amount. Through the measurements, the research was carried out as follows. First of all, we studied the influence of friction coefficient about different shapes (chamfer shape, area of the friction material, number of slots) on the same friction material. Secondly, we knew the effects of braking distance by the shape of the friction material. Through these two studies, the shape of the friction material favorable to the fade characteristics was derived. Finally, we measured the amount of required brake fluid in caliper after 10 consecutive braking cycles through Dynamometer. And then, we measured the amount of compression deformation and uneven wear of the friction material. It was found that the above two factors cause the increase the amount of required brake fluid. Through this study, in order to have strength for the fade characteristic, it is required that continuous management of the friction material and shape of brake pad. This is because the friction coefficient and the high temperature compression deformation of the friction material are determined by its material. Also, it is necessary to robust design the caliper for reducing for uneven wear about the brake pad.
Kim, Junggyu, Kim, Kwang Yun, So, Eue-sub
Development of Regenerative Brake Control Strategy to Remove Brake Rust2019-01-21259/15/2019
This study is the development concept of regenerative braking cooperative control to reduce creep groan noise considering fuel efficiency. Creep groan noise is a traditional brake system noise that has been improved with advances in technology such as brake materials, surface treatment and transfer path. However, recently creep groan noise is again an issue in electronic vehicle which applied a drive motor. Generally, creep groan noise frequently occurs when rust occurs on the friction surface of the brake disc and the brake pad is humidified, but it is easily removed by friction braking several times. However, in the case of electric vehicles which applied regenerative braking system, it is hard to remove. In case of electric vehicle, instead of friction braking, most of brake toques are made by motor regenerative braking. Therefore, even if the same conventional brake system and chassis system are applied, the noise level of the electric vehicle is higher than gasoline or diesel vehicle, and the field claim is also higher. To improve the noise, regenerative braking cooperative control logic was developed that detects long-term vehicle parking condition and control the regenerative brake ratio of total driver demand brake toque considering fuel efficiency. Also several tests are proceeded to review the effect of creep groan noise and fuel efficiency.
Jang, Sora, Kim, Gwichul
The Analysis of Brake Squeal Noise Related to the Friction Properties of Brake Friction Materials2019-01-21329/15/2019
The friction properties related to squeal noise was analyzed with the development histories and simplified computational method. Firstly, the development histories were investigated especially focusing on the case which the friction materials were modified to improve squeal noise occurrence. Based on the histories, the friction properties of selected friction materials were newly measured using dynamometer. The average friction coefficient levels, torque oscillations, the increment of friction coefficient during full-stop, and etc. were compared with the squeal noise occurrence, and the results showed that increase of friction properties cause production of squeal noise. The result suggested that the size of friction energy was important factors related to triggering the squeal noise. Also, the contact conditions between rotor disc and friction materials were significant factors deciding the noise occurrence. We performed simplified computational analysis using MATLAB program to prove the effect of friction energy on the noise occurrence. The friction surfaces were roughly designed and the distribution of contact plateaus was controlled to simulate different contact conditions. The different contact conditions were designed and performed sliding at low velocity condition to observe stick-slip phenomena. The friction energy was calculated with the amplitude of stick-slip for each case. The results showed that when the similar sized contact plateaus were increased, friction energy or the amplitude of stick-slip was also increased. And the total size of contact plateaus, which denote contact area, also affected the amplitude of stick-slip profile. Therefore the computational analysis supported the test results. In this study, we suggest that the design of friction surface considering contact condition is important to reduce triggering of the squeal noise.
Lee, Sang-mok, Woo, Jung Hoon, Cho, Younggu, Kim, Dong Won
The Influence of Differential Pad Wear on Low-Frequency and High-Frequency Brake Squeal2019-01-21309/15/2019
The NVH behavior of disc brakes in particular, is in the focus of research since a long time. Measurements at a chassis dynamometer show that brake pad wear has a significant influence on the occurrence of low- and high-frequency squealing [1]. It is suspected that high-frequency squealing is more likely to occur when the wear difference between the inner and outer brake pad is small. In the other case, if the differential wear rate between the inner and outer pads becomes higher, the prevalence of low-frequency squealing increases. In order to examine this hypothesis, this work focuses on a simplified model of a commercial brake system [2]. In a first step, the inner pad’s wear is iteratively increased, while the wear on the outer pad remains unaffected. In a second step, the coefficient of friction at the worn pad is iteratively increased to investigate the influence on the low and high-frequency squealing. With the aid of the Complex Eigenvalue Analysis (CEA), the real part of the eigenvalue is used as a quantification measure in order to investigate the dependence between wear and high and low frequency squealing.
Otto, Johannes, Ostermeyer, Georg-Peter, Rhee, Seong K.
A Study of the Disc Scoring Generation Principle and Reduction(III)2019-01-21129/15/2019
In the latest works [12], we presented the guideline for reducing Metal pick up(MPU, the main component of disc scoring) by controlling the location of the roughness of disc, the brake pad friction coefficients and the disc slot's size. In this study, the previously studied iron transfer theory to 'Cu free' brake pad and the disc surface roughness controlling methods which are based on the mass production manufacturing process are applied. It is possible to suggest the ways to improve the scoring-free disc without reducing friction coefficient between the disc and pad, and any demerit such as increased wear and airplane noise like conventional slot discs [11].
Jeong, ByeongUk, Ryu, Hyoung Tae, Jung, Kwang Ki, Kim, Chang Jin, Lee, Hyunkyoung
Brake Squeal Prevention through Suspension Design and Adaptive Suspension10-03-03-00119/3/2019
The brake squeal phenomenon has bothered automobile manufacturers for a long time. Although having no ill effects on the braking performance, the squeaky noise is often a nuisance and one of the major complaints of many customers. In order to design quality and noise-free automobiles, the brake squeal issue has to be permanently tackled. Many researchers have suggested shape optimization and additional damping of the disk as brake squeal control measures. Other methods proposed in the literature include the use of a different brake pad material or an anti-squeal paste. However, the effect of the type of brake pad suspension on brake squeal has not been studied. In this article, we demonstrate that the use of a 4-element viscoelastic support can prevent brake squeal for a vehicle speed of 5-200 kmph, which is the practical vehicle speed range. For a 2-element support, we have identified a suitable control parameter and proposed an efficient active control for squeal prevention based on that. A nondimensional analysis has been carried out so as to ensure that the results are applicable for any system.
Saxena, Shashank, Dutt, Jayanta Kumar
Brake Block Effectiveness RatingJ1802_201906 (Current)6/6/2019
This SAE Recommended Practice provides the test procedure and methods to calculate the effectiveness of brake blocks, using an inertia dynamometer. To minimize testing variability, and to optimize standardization and correlation, a single, high volume size of brake block is specified (FMSI No. 4515E) and evaluated in a reference S-cam brake assembly of 419 mm x 178 mm (16.5 in x 7.0 in) size, using a specified brake drum.
Truck and Bus Foundation Brake Committee
Brake Effectiveness Marking for Brake Blocks - Truck and BusJ1801_201906 (Current)6/6/2019
This SAE Recommended Practice provides the method to assign numerical values of brake effectiveness, using data from single station inertia dynamometer effectiveness tests, and to identify a uniform procedure to mark these values on the edge of brake blocks in excess of 12.7 mm (0.51 in) in thickness.
Truck and Bus Foundation Brake Committee
Self-Lubrication Improves Standard Braking SystemsTBMG-341164/1/2019
By mixing carbon fibers into polymer-based brakes, researchers designed brakes that are self-lubricating. These new and improved brakes can prevent wear-and-tear and have better frictional properties than brakes currently on the market.
Effect of Slot and Chamfer Shape of Brake Pad on Mode Coupling2019-01-14193/25/2019
In the present, one of the essential quality concerns in the automotive industry is brake squeal. Brake pad shape is one of the factors affecting to brake vibration and squeal noise. This research aims to study the effect of slot and chamfer shape on mode coupling through the Finite Element Analysis (FEA), impact hammer testing and performance test from dynamometer. The results can be used to develop geometry of the brake pad surface that leads to brake squeal reduction in the design stage. The natural frequencies and mode shape of brake components calculated by FEA are compared with the impact hammer testing to ensure the accuracy of the results. The FE results are also verified through the standard test with a dynamometer.
Yeamdee, Sirapath, Bovornratanaraks, Thiti, Sriwiboon, Meechai, Chantalakhana, Chak, Ratanasumawong, Chanat
Friction Coefficient Identification and Environmental Marking System for Brake LiningsJ866_201903 (Current)3/11/2019
This SAE Recommended Practice is intended to provide a uniform means of identification which may be used to classify the friction coefficient of brake linings, based on data obtained from tests conducted in accordance with SAE J661 Brake Lining Quality Test Procedure and SAE J2975 Measurement of Copper and other elements in Brake Friction Materials. NOTE: It is emphasized that this document does not establish friction requirements for brake linings, nor does it designate significant characteristics of brake linings which must be considered in overall brake performance. Due to other factors that include brake system design and operating environment, the friction codes obtained from this document cannot reliably be used to predict brake system performance.
Brake Linings Standards Committee
High-Preload Deflection and Compressibility Test Procedures for Friction MaterialsJ2468_201811 (Current)11/12/2018
This standard specifies a method for testing and measuring the deflection of friction materials assemblies and compressibility of friction materials. This standard applies to disc brake pad assemblies and its coupons or segments, brake shoe lining and its coupons or segments, and brake blocks segments used in road vehicles. This SAE test method is consistent in intent with the ISO 6310 and the JIS 4413.
Brake Linings Standards Committee
Properties and Limitation of an Oxide Coated Aluminum Brake Rotor2018-01-187710/5/2018
The electrification of the powertrain and the thereto related recuperation of the electric engine saves the energy in the battery and thus reduces the thermally dissipated brake energy, which leads to lower brake rotor temperatures compared to combustion engine vehicles (ICEVs). These new conditions enable to reconsider brake disc concepts. Including lightweight design in heavy battery electric vehicles (BEVs) and the increasingly reliant corrosion resistance of brake rotors, Aluminum is a promising approach for new brake disc concepts. In the past, Aluminum brake disc concepts have already been deployed. For instance Aluminum Metal-Matrix Composite (Al-MMC) concepts in the Lotus Elise S1 and on the rear axle of the Volvo V40 [1]. The presented concept is a different approach and separates the friction system from the bulk Aluminum brake disc, achieved by coating of the friction rings. By locally reinforcing the friction rings, the good machinability and ductility of the base body is maintained and simultaneously the friction surface is sufficiently protected to resist the frictional loading during a brake application. In this work, fundamental studies on a brake dynamometer were conducted and supplemented by microstructural investigation to identify damage mechanisms and to judge the technical application of the concept.
Gulden, Florian, Gramstat, Sebastian, Stich, Anton, Hoppel, Heinz Werner, Tetzlaff, Ulrich
Non-Asbestos Organic (NAO) Disc Pad Wear Behavior: Divergence of Thickness Loss and Weight Loss2018-01-186610/5/2018
There is anecdotal evidence that disc pad wear numbers measured in thickness loss and disc pad wear numbers measured in weight loss do not show the same wear trends after wear or performance testing. However, research papers on this topic are difficult to find. Therefore, this investigation was undertaken to study and document this behavior in detail on high-copper, low-copper and no-copper (or copper-free) NAO pads. In all cases, thickness loss measurements are found to be substantially lower than expected from the weight loss data according to the SAE J2522 test schedule. This divergence is caused by pad swelling in the pad layer adjacent to the friction contact surface during brake testing at high temperatures. In addition to formulation changes, disc pad processing conditions such as mixing time and hot molding pressure are found to affect pad swelling. As pad physical properties, especially in the layer adjacent to the friction contact surface, are expected to dynamically change during braking due to the pad swelling, one has to seriously question any attempt to correlate physical properties of unused pads to brake performance and squeal generation. Detailed characterization of the dynamic changes taking place in the pad during testing/usage is recommended to gain better understanding and better prediction of brake performance and squeal.
Sriwiboon, Meechai, Tiempan, Nipon, Kaewlob, Kritsana, Rhee, Seong
Cementitious-Based Brake Pads Technology: Performance, Low Energy Consumption, Emission Drop2018-01-186710/5/2018
Brake pads employing innovative hydraulic inorganic binders in place of common state-of-the-art thermosetting phenolic resins have been produced by means of a unique prototypal equipment and a distinctive manufacturing process. The unicity of the process enables us to exclude completely any thermal cycle in the manufacturing steps, with a considerable positive energy balance compared to the standard counterpart. Realized brake pads have indeed been successfully tuned to meet the braking performances of phenolic counterparts. In the present work our latest efforts in this field are illustrated, focusing our attention to three main areas of interest: performance, energy consumption, volatile organic emissions. One selected exponent of our cementitious-based material is reported, demonstrating its capability of matching both standard OE and AM braking performances (investigated through a full scale brake dynamometer by SAE J2522 procedure), and its feasibility to be released as an actual AM material according to ECE R90 regulation (road test on vehicle). The energetic evaluation of the employed technology in term of prototypal manufacturing process and employed raw materials has been established, demonstrating the advantages of this new system compared to the standard one. Our investigation finally reports selected thermo-chemical analysis (TG-EGA and pyrolysis PY-GC/MS) devoted at identifying the key organic compounds potentially/eventually emitted during braking at various temperatures. Our material shows a dramatic drop of the volatile hazardous/organic compounds (VHCs/VOCs) released by a standard phenolic homologous, thus increasing the favorable characteristics of such inorganic hydraulic-binder brake pads and related technology.
Sanguineti, Alessandro, Samela, Alessandro, Rampinelli, Flavio, Bottalico, Luca, Ranza, Luigi, Romeo, Marco, Bonfanti, Andrea
Estimation of Transport Efficiency for Brake Emissions Using Inertia Dynamometer Testing2018-01-188610/5/2018
There is vast literature and peer-reviewed methods to estimate losses1 during aerosol sampling. However, there are no current published models for transport losses during laboratory measurement for brake emissions. This paper presents an open source (Microsoft® Excel) Macro using three different models (Particle Loss Calculator - PLC - from the Max Planck Institute [1]; AeroCalc [2] from the United States Center for Disease Control and Prevention; and SAE AIR6504™:2017-10 [3] for calculation of non-volatile particulate matter penetration). The fourth model (LINK) provides the average value from the three initial models. The LINK PALS2 Microsoft® Excel Macro (or ‘Macro’ for short version) also includes calculations for isokinetics not included on any of the three initial models. The results include additional factors (aerosol and air properties) to better estimate losses during: a) conceptual design and assessment of the feasibility of the initial system layout, with emphasis on the influence of duct design, dimensions and isokinetics; b) validation (prior to actual testing) of a given system; and c) actual testing, with proper corrections for cooling air conditions. The methods proposed are agnostic to the brake dynamometer design, brake type or size, or the specific particle measurement system. In order to cover meaningful ranges for duct size, airflow in the duct, and airflow in the sampling lines, the assessments follows a Renard series according to ISO 3:1973 Preferred numbers - Series of preferred numbers [4]. This work contributes to the industry efforts (UNECE/GRPE/PMP and led by the JRC [5]) to develop a robust and harmonized test method to characterize and report automotive brake emissions using inertia dynamometer testing.
Agudelo, Carlos, Vedula, Ravi Teja, Odom, Tyler
Numerical Study on Fluid Flow and Heat Transfer Characteristics of a Ventilated Brake Disc Connected to a Wheel2018-01-187810/5/2018
The role of a brake disc is to convert the kinetic energy of automobiles into thermal energy caused by friction between the brake pads and disc surfaces. The braking performance of an overheated disc is decreased due to hot judder and fade. Hence, the cooling technology of a brake disc is one of the most important issues related to automobile safety. In the present study, the fluid flow and heat transfer analysis of a ventilated brake disc are conducted numerically. Some geometries of automotive parts such as bearings, hubs and wheels are considered in this study. The commercial code ANSYS CFX is used to simulate the fluid flow and the conjugate heat transfer which includes conduction and convection. To evaluate the cooling performance in each case, the results, including the flow patterns of cooling air inside the wheel and the heat transfer coefficient distribution at the disc surfaces, were investigated and compared for various disc-hub combinations.
Lee, Byung Ju, Chung, Jin Taek, Jung, Yunho, Kim, Honglae, Lee, Seungpyo, Kim, Hee Yeol
The Factors Governing Corrosion Stiction of Brake Friction Materials to a Gray Cast Iron Disc2018-01-189910/5/2018
Corrosion stiction at the contact interface between a brake friction material and a gray iron disc under the parking brake condition was investigated by evaluating the possible parameters that affect the shear force to detach the corroded interface. Using production brake friction materials, comprising non-steel and low-steel types, corrosion tests were carried out by pressing the brake pad onto the gray iron disc using a clamp at various conditions. Results showed that the shear force to detach the corroded interface tended to increase with applied pressure and corrosion time. On the other hand, porosity, acidity, and hydrophobicity of the friction material did not show a reliable correlation to the stiction force. The poor correlation of the stiction force with the friction material properties indicated that the stiction force was not determined by a single factor but governed by multiple parameters including surface contact areas and inhomogeneity of the ingredients. Microscopic observation of the detached disc surface showed adhered fragments that were removed from the friction material surface, thus shedding light on the possible estimation of the stiction force from the disc area covered by the friction materials. The scattered small areas without corrosion on the gray iron surface, which were well matched with hollow areas on the friction material surface, supported the importance of the contact area information in understanding the poor correlation between the stiction force and of the friction material properties.
Gweon, Jaehyun, Shin, Sanghee, Jang, Ho, Lee, Wangyu, Kim, Dooyeon, Lee, Keeyang
On the Wear Dependence of Low-Frequency and High-Frequency Brake Squeal2018-01-190210/5/2018
The dynamics of disc brakes, and in particular their NVH behavior, have long been the focus of research. Measurements by Rhee et al. show that brake pad wear has a significant influence on the occurrence of low and high frequency squealing [1]. It is suspected that low frequency squealing is more likely to occur when the wear difference between the inner and outer brake pads is high. If the two pads incur comparable wear, however, the prevalence of high frequency squealing increases. In order to investigate this hypothesis, this paper focuses on a simplified model of a commercial brake system. First, the friction force between the inner pad and the disc is iteratively adjusted, while the force between the outer pad and the disc is held constant. In a second step, the inner pad’s wear is iteratively increased, while the wear on the outer pad remains unaffected. With the aid of the Complex Eigenvalue Analysis (CEA), the real part of the eigenvalue is used as a quantification measure in order to investigate the dependence between wear and high and low frequency squealing.
Otto, Johannes, Ostermeyer, Georg, Rhee, Seong
A Study of the Disc Scoring Generation Principle and Reduction (II)2018-01-189110/5/2018
In the latest paper [10], we presented our work based on experiments studying MPU (Metal Pick Up) of the pad and scoring(scratching) of the disc. The main component of MPU was iron “Fe”. If the roughness of the disc was small, the content of iron “Fe” was increased and the segregation of that was decreased especially in initial condition. In this study, we extended our study based on the results by adding some additional factors such as the location of the roughness of the disc, the coefficients brake pad friction, and disc slots. We made various discs of different roughness boundaries and slots, and pads of pad friction coefficients; and conducted two types of tests for whether a slot is present or not with the other same conditions to confirm the impact of the scoring. We find and believe that our experimental data should serve a useful guideline for reducing MPU of the pad and scoring of the disc.
Jeong, ByeongUk, Ryu, Hyoung Tae, Kim, Chang Jin, Jung, Kwang Ki, Lee, Hyunkyoung
Performance Evaluation of Two Wheeler Brake System Using Coupled Thermo-Mechanical Simulation2018-01-189610/5/2018
Safety aspect has been a key requirement in designing braking system. However, non-safety aspect like NVH and thermal performance are gaining equal importance. High engine capacity (cc) motorcycles are prone to thermal and NVH issues as braking energies are more. Therefore, virtual validation of brake disc system by considering both dynamic and thermal load with predefined assumptions is a toughest challenge when confronted with reality boundary conditions. Thus, the paper comes in a unique way of coupling dynamic and thermal load executed between multi body dynamics (MBD) and heat transfer equation which will convey results closer to real time scenario. MBD solves motion and the dynamic influence on heat transfer is calculated using “sliding boundary condition”. A series of repeated braking condition are performed on front brake disc of motorcycle. The results obtained from the analysis shows critical temperature rise. As a consequence, disc thickness variation (DTV) due to thermal expansion are aggregated when coupled with dynamic friction. DTV will prove to be critical in concerning NVH and durability issues of brake disc. Braking conditions are numerically simulated on finite element method (FEM) using nonlinear approach and results are summarized with test data.
Sukumaran, Suraj, Kalani, Dinesh, Suryavanshi, Yogesh, Kokane, Girish, Deshpande, Moresh, Kharul, Ravindra
Explanation for Variability in Lower Frequency Structure-Borne Noise and Vibration: Roles of Rear Subframe Dynamics and Right-Left Spindle Phasing10-02-01-00025/17/2018
This investigation focuses on a class of rear suspension systems that contain both direct and intersecting structural paths from the tire contact patches to the vehicle body. The structural paths intersect through a dynamically active rear subframe structure. New experiments and computational models are developed and analyzed in this article to investigate the variability of structure-borne noise and vibration due to tire/road interactions in the lower- to mid-frequency regimes. Controlled operational experiments are conducted with a mass-production minivan on a chassis dynamometer equipped with rough road shells. Unlike prior literature, the controlled experiments are analyzed for run-run variations in the structure-borne noise up to 300 Hz in a single vehicle to evaluate the nature of excitations at the spindle as the key source of variation in the absence of significant manufacturing, assembly and instrumentation errors. Further, a deterministic modal expansion approach is used to examine these variations. Accordingly, an illustrative eleven-degree-of-freedom lumped parameter half vehicle model is developed and analytically utilized to demonstrate that left-right spindle excitation phasing dictates the participation of the subsystem vibrational modes in the system forced response. The findings are confirmed through the analysis of a reduced finite element model of the vehicle system with a high-fidelity, modally dense suspension model, where the left-right rolling excitation phasing at the spindle alone is found to affect the component dynamic vibration amplitudes up to ±30 dB depending upon the component location and frequency range. These results are in qualitative agreement with the type of variations observed in the experiments.
Noll, Scott, Singh, Rajendra
3D Design and Surface Mapping of Disc Brake Pad for High Speed Train Using FEA2018-01-08414/3/2018
Recurrently, the increase in production of high-speed trains worldwide has become a confirmed fact. Seeking to use the high-speed trains locally to link the capital of Egypt “Cairo” with the new industrial cities has become a national requirement. Modeling 3D surface maps using finite element analysis (FEA) is one of the most important mechanical design tools for frictional parts to facilitate the manufacture of brake systems for heavy duty vehicles, especially high-speed trains due to difficult working conditions. In this paper, we presented simulate 3D surface maps for proposed frictional material pad using FEA at certain design parameters and experimental result conductions. The typical surface characteristics of disc brake pad are compared with commonly used materials in railway and vehicle brakes in Egypt. The surface mapping of the pad materials are characterized by the analysis and distribution for profile deformation, stress as well as the thermal distribution at different thicknesses of the proposed brake pad. We also studied the safety factor of the proposed design. This work aims to explain the dynamic behavior phenomena to ensure the robustness of the proposed design to be studied to meet the standard requirements.
Ali, Salah H. R., Azzam, Badr S N, Osman, Tarek, Moustafa, Ahmed
Truck Brake Failure: Differences between Failure Modes for Drum and Disc Brakes2018-01-05284/3/2018
On-highway heavy trucks are fitted with air disc brakes with increasing frequency. Disc brakes and traditional air drum brakes have different adjustment and heat dissipation characteristics. These differences lead to different failure modes when overheated. This paper describes how adjustment and other in-use factors affect the general braking capability of on-highway trucks fitted with disc and drum brakes. Simulations of a loaded tractor-trailer on a long, down-hill grade are used to predict brake temperature increase over time, and how that temperature increase can result in a runaway condition. The tractor and trailer are modeled with both traditional drum brakes and new disc brakes to illustrate operational differences between the two brake types.
Day, Terry D.
Lattice Brake Disc Instability Analysis Using Transient Complex Eigenvalue Method in Terms of Excitation Applied to the Pad2018-01-00914/3/2018
This paper describes an integrated approach to the analysis of brake squeal with newly lattice brake disc design. The procedure adopted to define the lattice properties by considering the periodicity cell of lattice plates, present equations of motion and modes response of a periodic lattice disc in principal coordinates on the rotating disc which excited by distributed axial load. The non-linear contact problem is carried out based on a typical passenger car brake for vanned and lattice brake disc types as it undergoes a partial simulation of the SAE J2521 drag braking noise test. The experimental modal analysis (EMA) with impact hammer test is used to obtain the brake rotor modal properties and validated finite element Free- Free State and stability analysis. The fugitive nature of brake squeal is analyzed through the complex eigenvalue extraction technique to define dynamic instability. The likelihood of squeal noise occurrence is quantified by the definition of a single indicator derived from the system eigenvalues. The lattice type brake disc indicated lower propensity to squeal with leading to the standard deviation (SD) of the instability measurement and indicated that it is more reliable at low squeal frequencies.
KARAMOOZIAN, AMINREZA, Tan, Chin, Wang, liangmo
Development, Performance Analysis and Optimization of Parallel Hydraulic Hybrid System for City Bus Application2018-01-04194/3/2018
One of the key requisites for a sustained mobility development is to have an efficient public transport system. Fuel efficiency and emission control are extremely important in this respect. By the very nature of city driving, it is obvious that city traffic results in frequent vehicle start and stops; which involves huge waste of vehicle kinetic energy. Every time vehicle moving from idle, needs a bigger input of power and every time the brakes are applied, all energy built up disappears again, wasted in the brake pads as heat. An effort has been taken to recuperate vehicle kinetic energy, hydraulically during braking events and utilize it to assist the vehicle during acceleration. Hydraulic based hybrid vehicle working on the principle of regenerative braking is one of the most fuel-efficient technologies for city application. Parallel hydraulic hybrid vehicle has been developed and optimized for fuel efficiency gain at vehicle level. Objective of this paper is to study behavior, performance and optimization of hydraulic hybrid vehicle in city application. This paper deals with evaluation of simulation, integration, calibration and performance tests carried out at real world usage conditions. As a final proof of concept and performance, the hydraulic hybrid bus was tested back to back with conventional city bus of same configuration and results were analyzed and compared. This paper also deals on the scope of engine downsizing and major challenges faced in developing hydraulic hybrid system for extremely hot weather conditions such as South Asian countries.
Yaser, K U Syed Taj, Bakatwar, Rupesh, Bhargava, Aashish, Tiwari, Sanjay
Test Procedures for Shear Strength of Automotive Brake Pads and Brake Lining AssembliesJ840_201711 (Current)11/15/2017
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
Effect of Normal Load and Temperature on the Evolution of Topology of Friction Materials2017-36-014111/7/2017
The friction materials of the drum and disk brakes correspond to one of the most complex materials applied to automotive industry, however, little is known about how this type of material reacts under wear conditions. The aim of this work is to understand the effects of loads and temperatures on the topology of brake's friction materials under wear regime. For this, brake friction material specimens were subjected to wear tests on which procedure was based on the SAE J661 standard. The tests consisted on a sequence of braking and cooling intervals, where friction material specimens were pushed against a rotating drum with controlled velocity. Different test temperatures and normal loads were set. From these tests, the mass loss of each specimen was measured. In order to understand the topological aspects of the materials tested, an optical microscope and confocal microscope were used. The variation of the surface characteristics during the wear process on each specimen was analyzed using quantitative metallography technique and the influences of normal load and temperature on the topology evolution were studied.
Terra, Caroline da Silva, Suetti, André Lima, Travaglia, Carlos Abílio Passos, Silva, Ladário da, Lopes, Luiz Carlos Rolim
Objective Method to Quantify Ecological Toxicity between Friction Materials2017-01-24959/17/2017
California and Washington recently passed legislation to limit certain constituents in brake pad friction materials. As part of the California (CA) legislation enacted in 2010, brake pad manufacturers need to perform an alternative assessment to identify potentially safer environmental and toxicological choices for future friction material production. Copper, chromium VI-salts, lead, cadmium, mercury, and other compounds have been identified as potentially unsafe to the environment. This paper contains the methodology behind an objective and comprehensive alternative assessment to quantify the ecological impact of friction materials. Utilizing raw material specific Chemical Abstracts Service (CAS) numbers and their associated toxicological reference values (TRVs), this newly defined method estimates the total toxicological impact of finished friction materials on both the environment and on a human carcinogenic level to allow the manufacturer to screen greener alternatives. Utilizing chemical specific TRVs such as the lethal concentration 50% (LC50), median effective concentration 50% (EC50), and the median effective reproductive concentration 50% (ErC50), this method quantifies ecological impact characteristics of brake pad friction material. In the same regard, the carcinogenic properties of each chemical are evaluated, placed into groupings based on their carcinogenic potential as evaluated by the International Agency for Research on Cancer (IARC) and are utilized to generate comparative carcinogenic ratings. The methodology is best utilized as a relative comparison between multiple uncompressed friction formulations in order to create greener friction material for the future.
Visser, Andrew M., Severnak, Scott
Finite Element Analysis of a Brake Disc under Constant Mechanical Loading2017-01-24909/17/2017
A brake disc is one of the most critical components in modern vehicle’s brake systems; hence, thorough validation of its performances in the development process by simulations, rig and vehicle tests is essential. In this paper, a disc brake system under a constant braking torque is analyzed using finite element method, and the stress and strain in a rotating ventilated brake disc employed are studied comprehensively. From detailed examination of the stress distribution and the cyclic stress history, it is found that the maximum stress in the rotating brake disc under the constant mechanical loading only occurs at some specified locations; and the stress history is multiaxial and non-proportional. These findings will help, as guidelines, to develop suitable evaluation tools for the strength and the fatigue of the brake discs; to setup proper laboratory test procedures and equipment; and to design strong and durable brake discs. Furthermore, the stress and strain under various amplitudes of loading are analyzed, and a linear relationship between the maximum stress/strain and the amplitude of loading is established. Finally, two simplified finite element modeling methods to shorten the analysis time are evaluated.
Yang, Qianjin, Zhang, Baozhi, Ding, Kangrong, Song, Liqiang
Influences of Initial DTV on Thermomechnical Coupling in Disc Brake System2017-01-24929/17/2017
In this paper, the initial disc thickness variation (DTV) of a ventilated disc in automotive brake system is modeled as sinusoidal function of the second order. The transient thermomechanical coupling properties of the brake system is simulated using finite element (FE) modeling. The system models and results were verified by a thermomechanical coupling test of a disc brake conducted on a brake dynamometer. By using varied evaluation indexes such as the temperature distribution, the normal stress and the elastic deformation of disc surfaces, the influences of the initial DTV and its direction as well as its amplitude on the thermomechanical coupling characteristics were analyzed. The simulation results show that the distribution of temperature and the normal stress in circumferential direction exhibit the same sinusoidal function of the second order as the modeled initial DTV property, which is different from the thermomechanical coupling characteristics caused by disc surface initial run-out (LRO). Whereas the thermomechnical coupling property of the disc in circumferential direction exhibit the same sinusoidal function of the second order as that of the initial DTV, the distribution of the temperature, the normal stress and the elastic deformation in radial direction are found to be uniform. The changes in the magnitude of initial DTV are found to have insignificant effects on the changes in the overall thermomechnical coupling property. However, the circumferential gradients of the temperature, the normal stress, and the maximum disc distortion increase linearly with the increase of the magnitude of the initial DTV. The radial gradients of these quantities are not linear proportional to the magnitude of the initial DTV.
Meng, Dejian, Wang, Ziyi, Zhang, Lijun, Yu, Zhuoping
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