Browse Topic: Disc brakes
The SAE J2923 procedure is a recommended practice that applies to on-road vehicles with a GVWR below 4540 kg equipped with disc brakes
The influence of moisture adsorption, prior braking, and deceleration rate on the low-speed braking noise has been investigated, using copper-free disc pads on a passenger car. With increasing moisture adsorption time, decreasing severity of prior braking or increasing deceleration rate, the noise sound level increases for the air-borne exterior noise as well as for the structure-borne interior noise. The near-end stop noise and the zero-speed start-to-move noise show a good correlation. Also, a good correlation is found between the noise measured on a noise dynamometer and on a vehicle for the air-borne noise. All the variables need to be precisely controlled to achieve repeatable and reliable results for dynamometer and vehicle braking groan noise tests. It appears that the zero-speed start-to-move vehicle interior noise is caused by the pre-slip vibration of the brake: further research is needed
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
This Recommended Practice applies to commercial vehicles equipped with air disc brakes and above 4536 kg of Gross Vehicle Weight Rating. Other assessments on the friction material or rotor related to wear, durability, correlation to product life, noise, judder, compliance to specific regulations, etc., are not part of this RP (Recommended Practice
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
Despite efforts to reduce disc brake noise occurrence, it remains a significant concern in the automotive industry, particularly in the current era of electric vehicles, where it can be an intermittent issue. There is no standard solution available for every noise frequency, as it depends on various conditions and parameters that need to be experimentally identified and addressed. This paper specifically focuses on addressing low-frequency noise. During dynamic conditions, the contact pressure becomes uneven, leading to uneven pad wear and making the disc brake system susceptible to noise. In noise rigs, the paper selects the most suitable shim and pad geometry based on trials that analyze the interaction between the shim and pad. In conventional practice, shim modification was performed using computer-aided engineering, but obtaining accurate pressure patterns in dynamic conditions with CAE is challenging due to certain assumptions. Through dynamometer trials, the paper identifies
This SAE Recommended Practice establishes dimensions and tolerances for the interface between inboard mounted disc brake rotors and disc wheel hubs. This document is intended for inboard mounted disc brake rotors and disc wheel hubs for Class 5, 6, 7, and 8 commercial vehicles. Special and less-common applications are not covered
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
This procedure provides methods to determine the appropriate inertia values for all passenger cars and light trucks up to 4540 kg of GVWR. For the same vehicle application and axle (front or rear), different tests sections or brake applications may use different inertia values to reflect the duty-cycle and loading conditions indicated on the specific test
This SAE Recommended Practice provides test performance requirements for air disc brake actuators for service and combination service parking brake actuators with respect to function, durability, and environmental performance when tested according to SAE J2902
The braking system in a vehicle is one of the most crucial parts for proper and safe operation. It is required to slow down or stop the vehicle and work by converting the kinetic energy of the wheel to heat. It is essential to dissipate the generated heat for optimal working and the long life of the disc brakes. Heat generated is due to friction between the brake pad and disc. Due to overheating of brakes due to prolonged braking and heavy braking, brake fade occurs. This leads to boiling of the brake fluid, gassing, and glazing of brake pads, hence reducing braking performance. Therefore, in this study, we used computer simulations to determine the best design that allows for the most heat dissipation by analyzing four different conventional disc brake designs. It was found that the slotted disc brake design had the maximum value of heat transfer coefficient (87.2% more than that of the vented disc brake) and also correspondingly the most decrease in the maximum temperature (39.56
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
The SAE J2521 procedure applies to high-frequency squeal noise occurrences for on-road passenger cars and light trucks below 4540 kg of GVWR. The procedure incorporates high-temperature and low-temperature test matrixes but does not fully account for the effects of the environment on brake squeal. For this test procedure, squeal occurs when the peak noise level is at least 70 dB(A) between 1.25 kHz and 16 kHz for tests using full suspension corners or full axle assemblies or between 2 kHz and 16 kHz for brakes not using a full suspension corner. Before using this recommended practice for chassis dynamometer testing, review in detail the specifics related to at least (a) instrumentation, including in-cabin microphones, (b) threshold levels for noise detection, (c) temperature control priority between the front and rear axles, (d) vehicle loading and load distribution, (e) cooling air and environmental conditioning, and (f) detailed nomenclature and labeling of channels and sensors
The brake of a vehicle is of particular importance for vehicle safety. Brake inspection is an essential part of the periodic technical inspection and contributes to road safety. The current vehicle brake inspection methods are mostly tied to brake tester and check the vehicle brake in a workspace that does not have much practical relevance. Therefore, an attempt is made to develop dynamic inspection methods for automotive brakes, which are based on driving tests. To develop these dynamic inspection methods, a vehicle model is used, which includes an empirical brake model that takes into account the various dependencies of the coefficient of friction of the friction pairing of automotive disc brakes. The model is later validated with full-vehicle brake maneuvers from different velocities and under different conditions and shows good results
This document describes standard test methods, analysis methods, and reporting methods for measuring the resonant modes of automotive disc brake rotors and drums for design/development and production verification of these components
This SAE Recommended Practice provides instructions and test procedures for air braked vehicles including but not limited to trucks, truck-tractors, trailers, dollies, and buses used on highways but does not include off-highway vehicles
This SAE Recommended Practice establishes uniform engineering nomenclature for wheels, hubs, rims, and their components used in truck, bus, and trailer applications. This nomenclature and accompanying drawings are intended to define functional truck wheel, hub, and rim designs. For nomenclature specific to “passenger-type” disc wheels, refer to SAE J1982. The International Standard (ISO) nomenclature is shown in parentheses when different than SAE J393
This SAE Recommend Practice specifies a method for measuring the deflection of friction materials and disc brake pad assemblies in a manner more consistent with classical material compressive strain testing. This SAE test method differs from SAE J2468 in the preload and maximum load applied to the test sample when deflection is measured. It adopts the material applied stress levels found in ISO 6310 (0.5 to 8.0 MPa) using a 25 mm diameter flat plunger
This paper addresses the brake pad particle emission during the braking process of a vehicle in motion. The frictional-constant contact between the disc brake and pads results in an increased temperature and wear of the pads. The emission of brake pad particles into the atmosphere leads to an increase in air pollution and hence becomes hazardous to the human body. In this paper, a wheel brake disc is installed in a ventilation system where the specific air flow is introduced in order to investigate the thermal performance and the emission of particles from the brake pads. A mathematical model using the fundamental parameters of the brake disc and ventilation system is established. The behavior of the heat transfer is studied using computational fluid dynamics (CFD). The particle emission rate from the pads is calculated under the assumption of uniform constant pressure distribution at the contact surface of the brake disc and pad. The results of the analysis show that circumferential
This article presents a novel aero-thermal coupled simulation approach for estimating the cooling performance of automotive vented disc brakes under the scenario of emergency braking. This approach couples the quasi-steady computational fluid dynamics (CFD) analysis in the fluid domain and the transient thermal calculation in the solid domain, and no finite element method (FEM)-based calculation is involved in the simulation. An advanced coupling strategy is proposed and used in the approach to solve the problem of boundary mismatch when data exchanging between the solid and fluid domains, and a specific point-in-polygon (P-in-P) algorithm is incorporated into the approach for a precise calculation of the braking heat flux through the brake disc. This approach has been implemented to analyze the temperature change of the vented disc brake for a real vehicle, and the results show that it is able to replicate the real pattern of heat generation via friction on the surface of the brake
The braking capacity of reducing the speed or even keeping the vehicle stoped is extremely important in the design of any brake system, as more than meeting legislation requirements; it directly affects the safe operation of the vehicle and its users. A fundamental component, which requires notable attention, is the friction material, which is designed to establish a compromise between mechanical properties, friction coefficient, noise propensity, deformation, wear, among others. However, braking capacity is a combined response for several of these friction material properties, along with the performance of other brake system components, such as the brake chamber, disc and caliper. This work aims to analyze firstly the influence of the friction material deformation and secondly the brake system deformation on the total stroke of the brake chamber. To the first one, three different formulations of friction material, applied to commercial vehicles, were selected. For these materials
The work investigates the use of cathodic protection -based strategies (e.g. sacrificial anodes) with the aim of extending the corrosion resistance of Aluminum components to be used in disc brake systems. Lab-scale electrochemical measurements, including voltammetry and zero resistance ammetry (ZRA), are used to: a) define the requirements of a cathodic protection system for a 42200 Aluminum alloy; b) evaluate the protection capability of a Zn-based sacrificial anode; and c) demonstrate an extended corrosion resistance of the protected part even in the presence of a galvanic coupling, with respect to the unprotected condition
Copper-free disc pads of 9 different compositions were made using a traditional hot molding process and tested to study frictional behavior. It is found that the friction coefficient consists primarily of two parts; one part controlled by the plastic deformation of the friction surface region of the disc and pad, and the second part controlled by the total wear of the disc and pads. As the plastic deformation and the wear are non-linear with respect to the load and sliding speed, the friction coefficient becomes a non-linear function of the load and speed. Under moderate braking conditions, the plastic deformation part is more significant in determining the friction coefficient while under more severe braking conditions, the wear contribution becomes more significant. The frictional behavior of a fade cycle is explained, and the correlation between brake squeal and disc wear is confirmed
It is important for assessing the service life of the braking mechanisms of passenger cars that are in operation is the establishment of the speed and the value of the permissible wear of the friction surfaces, which ensures the durability of the brake. The purpose of the study is to assess effect of area friction surfaces on resource of vehicle braking mechanisms. This will extend the service life of the disc brakes on cars. In the work, the regularities of wear of mating parts of disc brakes were established depending on the change in the geometric parameters of the friction surfaces and operating modes during their operation. It was found that the service life of disc brakes can be increased by 1.16 times with an increase in the area of frictional contact by 15 %, for passenger cars DAEWOO LANOS and LADA PRIORA. A comparative assessment of the wear of the new DAEWOO LANOS and LADA PRIORA brake pads, which perform cyclic emergency braking, is provided. Recommendations have been
The current investigation was undertaken to find out if lighter-weight passenger car disc pads would exhibit wear behaviors similar to pickup truck pads and commercial heavy truck drum linings in terms of the permanent volume expansion of the friction material contact surface region. 2 high-copper NonAsbestos Organic formulations and 3 copper-free LowMet formulations were tested according to the SAE J2522 test procedure. In all cases, the measured pad thickness loss was found to be less than the thickness loss calculated from the weight loss, indicating pad volume expansion in the pad surface region, in full agreement with the results from the pickup truck and heavy trucks. The heataffected swollen/expanded layer ranges from 0.27 to 0.61 mm in thickness depending on the formula and test conditions. Due to the expansion, pad durability projections made from test results based on high temperature city traffic tests can result in underestimating the actual durability. Also, one needs to
In today's world with fast-growing mobility, everything is becoming compact day by day with ever-increasing technological advances. This paper deals with the design of a disc brake rotor considering the requirement of a student formula team. In this paper, the different iterative design has been done to achieve the maximum heat flux distribution and at the same time maintain the structural rigidity of the rotor so that it can withstand the torque requirement of an SAE vehicle [3] Solid works was used for design modelling while Ansys and Hypermesh were used to perform the CAE Analysis for the brake rotor. Here, we will explain various design iterations and how design can be optimized with extensive use of CAE tools by performing structural and thermal analysis. The analytical results from the CAE simulation will help us to determine the slots or holes pattern on the rotor face as well as the selection of material for the rotor. The numerical calculation is calculated to find required
Disc brake is the customarily used braking system in automobiles. In the disc brake assembly, rotor is subjected to rotation and the brake pads are operated by the driver through mechanical action. So, the disc plays a decisive role in dropping the speed or stopping the vehicle. These discs were commonly made of cast iron conventionally. But the limitations with respect to cast iron are that they have less corrosion resistance and heavy in weight. In order to overcome the above-said complications, alternate materials for disc have to be found. The main objective of this paper is to analyze the characteristics of three different materials and their characteristics and recommend a fitting material that highly replaces the conventional material and has better performance at on-road braking conditions. In order to find an alternative material for Cast Iron (CI), EN31, Ti-6Al-4V(Ti alloy) acts as a potential candidate in offering great damping property and thermal conductivity with less
Groan is a low frequency noise generated when moderate brake pressure is applied between the surfaces of the brake disc and the brake pad at a low-speed condition. Brake groan is often very intense and can cause large numbers of customer complaints. During a groan noise event, vehicle structure and suspension components are excited by the brake system and result in a violent event that can be heard and felt during brake application. The cause of noise is friction variation of stick-slip phenomenon between friction material and disc. Creep groan is the structure-borne noise that is related to dynamic characteristic of the vehicle. However, it has been mainly improved through friction material modifications in the past. In this paper, transfer path of creep groan noise was analyzed by means TPA and structural countermeasure to creep groan noise was suggested. This paper discusses the approach for prediction and mitigation of brake groan noise for passenger vehicles having disc brakes
In recent days, the usage of disc brake is increased acutely in commercial vehicle applications apart from the passenger vehicles. The main advantage of using disc brake is reducing the stopping distance, temperature and wear between the disc and pad. During the braking, kinetic energy of the vehicle is converted into thermal energy due to the friction between disc and pad. To maintain the temperature between the disc and pad is critical for the overall performance of the disc brake and safety of the vehicle. The process of vehicle braking is a dynamically thermal structure coupling problem which is complex in nature. In this study, temperature between the disc and pad is determined using Finite Element Analysis for two different pad configurations. As per recent vehicle norms by the government the axle load is increased by 20 % which requires increased braking force and will leads to high temperature in the disc pad interface. Considering the vehicle tonnage, braking force is
In order to reveal the temperature and stress change of wet brake under emergency working conditions, a wet multi-disc brake used in mining machinery was taken as the research object. The thermomechanical coupling simulation model of a wet brake was established, and the temperature and stress change of the friction disc under emergency working conditions were analyzed through a bench experiment. The temperature and stress change of the friction disc of the simulation model are compared to the experimental one to verify the correctness of the model. The results show that (1) There is a coupling relationship between the temperature field and stress field during emergency braking. In the process of braking, the variation trend and spatial distribution law of the temperature field and stress field are very similar. (2) When the brake is applied at 40 km/h, the temperature rise of the friction disc reaches 46.8°C during the process of emergency braking conditions. Thus braking at the speed
This SAE Recommended Practice (RP) specifies a dynamometer test procedure to characterize wear rates of automotive service brake linings (brake shoes) and disc brake pads
This SAE Recommended Practice contains dimensions and their tolerances concerning disc wheel to hub or drum interface areas for truck and bus applications. Disc wheels designed only for single wheel applications (not dual wheels) for light trucks and special or less common applications are not covered in this document
Brakes are the critical component, plays a significant role regards to performance of vehicle. Vehicle safety is also strongly influenced by proper braking operation, which depends on pad to disc contact interface. Pad and disc surfaces are worn out due to continuous braking events, which in turn affects the life of the brake assembly and its performance. This paper presents the brake pad wear prediction of a disc brake assembly. A new and unworn pair of brake pads are considered for the study and tested under different braking scenarios. Wear simulation procedure is formulated based on Rhee’s wear formula and wear calculation model is established based on friction and wear mechanism. The correlation between the wear behavior of a friction material tested under controlled laboratory conditions and finite element method is investigated. Based on the calculated wear, lifespan of the brake pad is also calculated. The predicted life of the pad using inertia brake dynamometer (IBD) is then
When driving a vehicle, reliable braking system ensures maximum human safety. Increasing vehicle speed under driving conditions generate heat due to the friction between rotating disc and pads. Elevated temperatures accelerate brake disc contact surface thermal deformation and shortens the service life. The particles formed as a result of high temperature and friction coefficient on the contact surface of the brake disc must not be emitted into the atmosphere. The ventilation system ensures that particles do not escape into the atmosphere by installing a car air filter system in the outdoor air flow duct. Minimizing the amount of heat and temperature on the contact surface of the brake disc in the ventilation system leads to an increase in the service life of the brake disc. The present research is essentially dealing with the modeling and analysis of solid and ventilated disc brake using ventilation system test rig. Methods for design and analysis of optimal airflow rate ventilation
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