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Viewing 91 to 120 of 9978
2014-09-28
Technical Paper
2014-01-2486
Axel Stenkamp, Michael Schorn
Abstract Starting in the late '90s, a new and innovative brake disk technology entered the high performance passenger car market. Approx. 2 years later, small volume production of carbon-ceramic brake disks started. In the past ten years the number of cars equipped with the new generation of ceramic matrix composite (CMC) brake disks has continuously increased, with main usage in low volume, high horse power applications. The goal of this paper is to give an overview of the system specific boundary conditions as well as today's and tomorrow's targets and aspects of friction material development used in CMC-disk based brake systems. Starting with a description of the system component properties, a comparison of typical CMC vs. standard gray cast iron disk (GCI) applications will be made. The impact of the component properties, especially the disk as friction counterpart to the pad, will be shown by comparing industry standard test scenarios. One described system boundary will be the thermal load to the brake pad.
2014-09-28
Technical Paper
2014-01-2484
Kazuho Mizuta, Yukio Nishizawa, Koji Sugimoto, Katsuya Okayama, Alan Hase
Abstract Brake pads are composite materials made from dozens of ingredients intended to simultaneously satisfy various performances such as brake effectiveness, wear, noise and vibrations. For this reason, the friction phenomena that occur during braking are complicated. It is important to clarify the friction phenomena, but that is not easy because the associated complexities as mentioned above. We looked to acoustic emission (AE) as an online evaluation method of friction phenomena. AE is a non-destructive testing method that measures elastic stress waves caused by the deformation and fracturing of materials. In fact, it has been reported that the difference between abrasive wear and adhesive wear of a metal can be identified from the change in the frequency spectrum of AE signals. In this study, we verify whether differences in the friction phenomena of brake pads are detectable by the AE method. Three kinds of brake pads were used in the experiments. One of the specimens included an abrasive ingredient, one included an adhesive ingredient, and another included neither.
2014-09-28
Technical Paper
2014-01-2496
Adarsh Venkata Padmanabhan, Hariram Ravichandran, Lokendra Pavan Kumar Pappala, Shreyas Shenoy
This paper comprises obtaining friction coefficient (μ) measure by extracting surface and texture information using sensors during brake interventions. A primary estimate of friction coefficient has been obtained using wheel and vehicle signals. The estimates have been compared and combined to obtain a more accurate measure of friction coefficient. Finally, a suitable interpolation technique is used to obtain a μ-grid around the vehicle. The grid is graphically realized with the aid of visualization techniques using vehicle traces. This type of surface characterization usually enables brake distance optimization and effective countermeasures pertaining to a standard ESP system.
2014-09-28
Technical Paper
2014-01-2524
Chendi Sun, Xiaofei Pei
Abstract This paper presents how hardware-in-the-loop (HIL) simulations have been used for testing during the development of ABS (Anti-lock Braking System). The Labcar system of ETAS is a popular tool for HIL tests. The vehicle model which is built in Matlab/Simulink is downloaded to run in RTPC (Real-time PC). The Labcar software, Integration Platform (IP), can configure boards which is a link between the model and ABS ECU. In this paper, a classical logic threshold control algorithm is adopted in ABS ECU. Through Labcar Experiment Environment (EE) various parameters can be monitored and modified conveniently. The HIL test of ABS ECU is implemented on high or low - adhesion road respectively. The results show that, although response lag exists in the hydraulic braking system, the curves of velocity and pressure in wheel cylinders can be close to those on real road with proper adjustment of control parameters. So HIL simulations are invaluable, when considering the short development time required in the automotive industry.
2014-09-28
Technical Paper
2014-01-2523
Nils Perzborn, Carlos Agudelo, Georg Peter Ostermeyer
Abstract Inertia dynamometers are commonly used to determine the friction coefficient of brake assemblies. Dynamometers are a well-established platform, allow testing under controlled conditions, exhibit a good correlation to many situations encountered in real driving, and are comparatively economical and less time-consuming than full vehicle test. On the other side of the spectrum is the use of scaled tribometer. These test systems make possible a test without the entire brake corner. This separation allows the investigation of the frictional-contact only (frictional boundary layer) speedily and independently of a given brake system or vehicle configuration. As the two test systems (inertia dynamometers and tribometers) may have different users with possibly different tasks, the question remains regarding how comparable the two systems are. These issues provide incentives to better define the fields of investigations, correlation, and applicability for the two systems. In order to provide further insights and learning on this topic, this paper focuses on the measurement of the friction coefficient and the wear behavior using inertia dynamometer and scaled pin-on-disc tribometer testing.
2014-09-28
Technical Paper
2014-01-2481
Lars Wilkening, Hans-Guenther Paul, Georg Peter Ostermeyer
Abstract Friction materials for automotive brakes are known to exhibit a time-dependent tribological behavior. When examining these dynamic effects special demands are made on the measurement device: The influences of the brake system should be minimized and parameters like velocity, contact pressure and temperature should be controlled closely and independently. Furthermore, special test procedures need to be designed. This can ideally be achieved using a scaled tribometer like the High-Load-Tribometer at the Institute of Dynamics and Vibrations in Braunschweig. Former investigations [1] have shown that a kind of memory effect can occur for a low-met brake pad rubbing on a cast iron disk. A variation of the initial disk temperatures has revealed that a temporary increase of the coefficient of friction can occur at slightly elevated temperatures. This effect is memorized by the material as a certain procedure needs to be performed in order to achieve a regeneration. The scope of the current work is to extend this examination with respect to different materials and also include different load cases.
2014-09-28
Technical Paper
2014-01-2490
Werner Oesterle, Andrey I. Dmitriev
Abstract Third bodies, also termed friction layers, tribofilms or secondary contact patches, are layers of more or less compacted wear debris between pads and rotor of a disc brake. Our approach of assessing the sliding behavior and friction properties induced by third bodies has been: i) structural characterization after AK-master test procedure, ii) sliding simulation of model structures similar to the observed ones but with simpler and well defined compositions, and iii) verification of simulation results by pin-on-disc tests with artificial third bodies showing the same microstructures and compositions as the model structures. The idea was to simulate structure formation during real braking conditions by high energy ball milling of appropriate powder blends. The final outcome of numerous parameter studies was that a third body containing 15 vol% soft ingredients and 0-20 vol % hard ingredients, both distributed homogeneously in a nanocrystalline iron oxide matrix, should be most desirable for braking.
2014-09-28
Technical Paper
2014-01-2487
Mohamed Samy Barakat
The Braking System is the most crucial part of the racing vehicle. There is no doubt, that if only one minority failure in the braking system took place, this would be more than enough reason to cause the racing team disqualification from the competition. Time is the main and the most important criteria for any racing competition; on the other hand the formula student “FS UK SAE” competition care the most about developing the automotive engineering sense in the students by putting them under strict rules normally taken from the original version “formula 1” to encourage their creativity to reach the optimum performance under these strict rules. One of the most important rules is “No Braking by wire”, and the obvious consequences are more stopping distance and time. Braking distance is a critical facture in achieving racing success in a competitive domain. This report will cover using the bias bar, dynamic weight distribution “before and after braking” and carefully choosing the braking and suspension system components dimensions, in order to fulfill the main functions of “ABS and EBD” which are preventing the wheels from lock-up and preventing side skid of the vehicle during cornering in the different dynamic tests with full consideration of the maximum approachable deceleration of the vehicle without locking up without using any kind of electronic “actuators or control”.
2014-09-28
Technical Paper
2014-01-2497
Bongkeun Choi
Abstract In this paper an effective technology of virtual thermal test of disc brake with several advanced analytic techniques was presented. With the virtual thermal test process, thermal performance of brake system could be easily evaluated without any possibility of great errors that used to happen in the past. In addition to the classical result of CFD, this virtual thermal test produced several valuable applications such as thermal deformation of rotor, optimization of thermal performance and estimation of braking distance.
2014-09-28
Technical Paper
2014-01-2495
David B. Antanaitis, Heewook Lee
Abstract An area of brake system design that has remained continually resistant to objective, computer model based predictive design and has instead continued to rely on empirical methods and prior history, is that of sizing the brake pads to insure satisfactory service life of the friction material. Despite advances in CAE tools and methods, the ever-intensifying pressures of shortened vehicle development cycles, and the loss of prototype vehicle properties, there is still considerable effort devoted to vehicle-level testing on public roads using “customer-based” driving cycles to validate brake pad service life. Furthermore, there does not appear to be a firm, objective means of designing the required pad volume into the calipers early on - there is still much reliance on prior experience. This paper builds upon previous work by GM [1], where short duration, objective vehicle and dyno tests were combined with a computer model to allow for accurate pad service life prediction without vehicle tests, and expands it into a methodology combining CAE (CFD), computer modeling, objective friction material characterization data, to enable confident sizing of the brake pads very early in the vehicle development process.
2014-09-28
Technical Paper
2014-01-2499
Lijun Zhang, Cheng Ruan, Dejian Meng
Abstract Brake pedal feel characteristic is determined by the structural and kinetic parameters of the components of the brake system. As the servo power component of the brake system, vacuum booster has a significant influence on the brake pedal feel. In this paper, a brake system model for brake pedal feel which has a detail vacuum booster mathematical description is established in the software MATLAB/Simulink. The structure gaps, spring preload, friction force and reaction disc characteristics of vacuum booster are considered in this model. A brake pedal feel bench test under different input velocity and vacuum pressure is completed in order to validate the prediction of the model. Finally, based on the assessment index in pedal travel, pedal force and master cylinder pressure three-quadrant diagram, the influence of vacuum booster design parameters such as structure gaps, spring preloads, press plate and press ring areas, diaphragm effective area and reaction disc stiffness on the brake pedal feel characteristics is analyzed and discussed.
2014-09-28
Technical Paper
2014-01-2502
Toshikazu Okamura
Abstract There are various processes for finishing the friction surfaces of a brake disc, which affect the braking effectiveness of a vehicle in the early stages of use in some cases. To examine the interaction between the disc surface texture, rotational direction, and friction material, a series of experiments on a tribotester using small-scale specimens was conducted. In a previous paper (2013-01-2056), the results from the first series of experiments, which involved of thirty disc surface textures and a less aggressive non-asbestos organic (NAO) friction material in on-brake-drag conditions combining constant speed and normal-load, was reported. Disc surfaces were finished by the following finishing processes in two rotational directions: turning under four cutting conditions, roller burnishing after turning, turning with a wiper insert, and grinding with two stones. Contact-pressure dependency of friction and wear was confirmed. Roller-burnished and wiper-turned discs exhibited different friction and wear at a certain contact pressure between rotational directions in the turning process.
2014-09-28
Technical Paper
2014-01-2506
David B. Antanaitis
Abstract It is obvious at this point even to the most casual observer of the automotive industry that efforts to reduce mass throughout the vehicle are at a fervor. The industry is facing its most significant increase in fuel economy standards in its history, and light-weighting the vehicle is a major enabler. Despite the performance and quality of the brake system being intensely related to its mass, it too has not been spared scrutiny. However, like many modern automotive subsystems, it is very complex and mass reduction opportunities that do not sacrifice performance or quality are not always obvious. There are some interesting and sometimes even profound relationships between mass and other vehicle attributes built into brake system design, and making these more visible can enable a better balancing of brake system with the rest of the vehicle design objectives. Examples include - what is the cost, in terms of brake system mass, of added engine power? Of tire and wheel size? What is the mass cost of brake pad volume and service life?
2014-09-28
Technical Paper
2014-01-2521
Jaroslaw Grochowicz, Carlos Agudelo, Shanglei Li, Harald Abendroth, Karl-Heinz Wollenweber, Achim Reich
Abstract The efforts of the ISO “Test Variability Task Force” have been aimed at improving the understanding and at reducing brake dynamometer test variability during performance testing. In addition, dynamometer test results have been compared and correlated to vehicle testing. Even though there is already a vast amount of anecdotal evidence confirming the fact that different procedures generate different friction coefficients on the same brake corner, the availability of supporting data to the industry has been elusive up to this point. To overcome this issue, this paper focuses on assessing friction levels, friction coefficient sensitivity, and repeatability under ECE, GB, ISO, JASO, and SAE laboratory friction evaluation tests. With multiple companies (or programs) developing and assessing the friction coefficient and friction behavior under different methods, it is inevitable to avoid conflicts of performance requirements or lack of reproducibility or correlation of test results under different test methods.
2014-09-28
Technical Paper
2014-01-2525
Tomasz Grabiec
Abstract Wear and friction behavior of disc brakes are important properties of disc brake systems and are mainly addressed by appropriate selection and tuning of friction material. Disc material composition is often considered as “given”. The most common material used for brake discs is grey cast iron which can have carbon content between 2.5 to 4.2 percent. It is difficult to find in literature investigations related to the influence of cast iron material in combination with modern low-met friction material on wear and friction performance of disc brakes. In this work, the author will try to analyze impact of brake disc material properties on wear and friction performance.
2014-09-28
Technical Paper
2014-01-2538
Jongsung Kim, Chjhoon Jo, Yongsik Kwon, Jae Seung Cheon, Soung Jun Park, Gab Bae Jeon, Jaehun Shim
Abstract Electro-Mechanical Brake (EMB) is the brake system that is actuated by electrical energy and has a similar design with the Electric Parking Brake (EPB). It uses motor power and gears to provide the necessary torque and a screw & nut mechanism is used to convert the rotational movement into a translational one. The main difference of EMB compared with EPB is that the functional requirements of components are much higher to provide the necessary performance for service braking such as response time. Such highly responsive and independent brake actuators at each wheel lead to enhanced controllability which should result in not only better basic braking performance, but also improvements in various active braking functions such as integrated chassis control, driver assistance systems, or cooperative regenerative braking. Although the EMB system has the potential for numerous advantages and innovations in braking, it has yet to be successfully introduced in series production mainly due to safety and cost concerns.
2014-09-28
Technical Paper
2014-01-2503
Johannes Schneider
The brake discs and brake drums used on motor vehicles are, in 90% of applications, made from grey cast iron. Although other designs such as composite systems comprising of a grey iron braking band and a light weight mounting bell made from aluminum, Al-MMC or entire ceramic brake discs have been developed, cast iron will continue to play a major role as a work piece material for brakes. Cast iron offers advantages in material characteristics such as good thermal conductivity, high compressive strength and damping capacity. In addition it shows a superior casting behavior and also an unbeatable competitive price per part, when compared to other brake materials or designs. Ongoing research in material and casting science are leading to new types of alloyed CI materials, fulfilling the increasing demands in terms of performance but also increasing the demands for a reliable and economical production. As a product of high volume production the economics and productive manufacturing of the brake discs is a fundamental issue to ensure the competitiveness of the manufacturers.
2014-09-22
WIP Standard
J1801
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. The edge markings are intended to provide relevant and meaningful data on the normal and hot effectiveness of brake blocks, using the reference full size brake assembly, to aid in the characterization of these brake block frictional properties. This edge marking methodology is intended to permit accurate identification of the effectiveness values over the full wear life of the brake block. This is accomplished by means of permanent markings on one edge of the brake block.
2014-09-22
WIP Standard
J1802
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.
2014-09-22
WIP Standard
J44
This SAE Recommended Practice establishes performance requirements for hand-operated brake systems on recreational, noncompetition snowmobiles.
2014-09-22
WIP Standard
J45
This SAE Recommended Practice establishes a uniform procedure for the level surface testing of hand-operated brake systems on recreational noncompetitive snowmobiles. Purpose This procedure offers a method of testing snowmobiles on turf. Turf is preferred over snow because test repeatability is more easily obtained. In addition, tests shall be conducted under winter conditions to ensure that the braking systems remain operative and that the vehicle has no undue tendency to lose stability, overturn, or swerve out of a test lane 1.2 m (4 ft) wider than the vehicle when the brakes are applied. The purpose of the document is to establish brake system capabilities with regard to deceleration or stopping distance versus applied brake lever force, as affected by vehicle speed, brake temperature, and usage.
2014-09-18
Standard
J1403_201409
The vacuum brake hose is intended for use in the power braking systems of vehicles or as connections on transmission lines in combinations of vehicles or systems thereof. For the purposes of clearly identifying hose classification and for specification simplification, vacuum brake hose is divided into two types: heavy-wall Type H, and light-wall Type L.
2014-09-16
Article
A racecar fitted with a prototype rear suspension will compete in the Sports Car Club of America's 2015 season as a proof-of-concept demonstrator for using thermoplastic composite suspension components in future light-duty vehicle production applications.
2014-09-16
Magazine
All the right connections With 2013 sales of $6.8 billion, Dana is a leading tier one supplier. Ian Adcock catches up with its chief technical and quality officer George Constand. Jaguar's lightweight challenger Ian Adcock uncovers the secrets that make the XE saloon, Jaguar's most important car yet. Boxing clever How composite crashboxes save weight and cost
2014-09-15
Article
Germany's ZF has entered into a definitive agreement to acquire U.S.-based TRW Automotive Holdings Corp. for $13.5 billion, according to a Sept. 15 TRW press release. ZF has stated that TRW will be operated as a separate business division within ZF.
2014-09-15
WIP Standard
J3079
The procedure describes how to measure the deflection of a brake pad, noise insulator, and brake pad assembly.
2014-09-15
WIP Standard
J393
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. The International Standard (ISO) nomenclature is shown in parentheses when different than SAE J393.
2014-09-09
Standard
J191_201409
This SAE Standard covers hose fabricated from fabric braid and synthetic rubber, assembled with end fittings for use in automotive power steering applications at pressures as indicated in Table 1B, as flexible connections within the temperature range of -40 ×C (-40 ×F) to 121×C (250 ×F) average, 135 ×C (275 ×F) maximum peaks. These hoses are intended for use in applications where reduction in amplitude of pump pressure pulsations is not required.
2014-09-09
Standard
J2522_201409
This SAE Recommended Practice defines an Inertia Dynamometer Test procedure that assesses the effectiveness behavior of a friction material with regard to pressure, temperature and speed for motor vehicles fitted with hydraulic brake actuation. The main purpose of SAE J2522 is to compare friction materials under the most equal conditions possible. To account for the cooling behavior of different test stands, the fade sections are temperature-controlled.
2014-09-04
Article
Mazda Motor Corp. on Wednesday evening unveiled the fourth-generation MX-5 Miata, which adopts both SkyActiv technology and Mazda’s “Kodo” (or "Soul of Motion") design language. The MX-5, first introduced 25 years ago, maintains Mazda’s original aim of offering the pure driving fun that only a lightweight sports car can provide.
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