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Viewing 31 to 60 of 10699
2016-09-18
Technical Paper
2016-01-1928
ByeongUk Jeong, Sang Do Kwak, Cheol Ki Kim
Owing to the enhanced requirement of brake free noise these days, more damping kits should be installed in the braking system. Success of doing this properly causes softness in the brake system which results in the loosened stroke feeling of brake pedal, the increased compressibility by durability. A study for detailed factors to aggravate brake feeling was done as a solution to prevent these from happening. In this paper, we present our work based on experiments to measure compressibility of shims by the influence of variations in different parameters, for example, of adhesive shims (bonding spec., steel and rubber thickness), piston’s shapes (different contact areas to the shims), and the numbers of durability. We installed the brake feeling measurement system extended from brake pedal to caliper. Experimental parameters were compared with brake feelings in vehicle using it. The optimization for brake feeling was determined by design for six sigma (DFSS).
2016-09-18
Technical Paper
2016-01-1922
Yongchang Du, Yujian Wang
Modelling of disc is crucial in analyzing brake squeal since the disc rotates past the non-rotating pads and the pads are coupled with different areas of the disc at different times. However, in most of the complex eigenvalue analysis of brake squeal, the effect of disc rotation was ignored. This paper proposes a closed-loop coupling model for brake squeal analysis. A modal parameter–based rotating disc model, whose dynamic behavior is represented by rotation speed-dependent equivalent modal parameters, is built through space and time-frequency transformation between reference and moving systems. The orthogonality of the equivalent modal parameters in state-space is derived. By performing modal synthesis in state-space, the rotating disc is incorporated into brake squeal closed-loop coupling model with other stationary components. Dynamic instability of the system is solved through complex eigenvalue analysis in state-space.
2016-09-18
Technical Paper
2016-01-1909
Diego Adolfo Santamaria Razo, Fernao Persoon
Environmental and financial factors are leading developments in the automotive industry, friction materials are not an exception. Different associations around the globe are increasing their attention in regards to fine dust emissions. End users are increasing their focus on comfort and cost due to global economic conditions. Two of these factors are directly related to each other: comfort and fine dust. They are the result of tribologic mechanisms deriving in pad and disc wear. Such mechanisms linked to friction performance are the consequence of the interaction between friction material surface and disc surface. The definition of what is being formed between the two surfaces is a continuously evolving layer called third body layer (transfer layer, tribologic film, among others) and it has been deeply studied in different papers. In order to be formed and to work properly, the third body layer needs to possess a strong chemical and mechanical stability.
2016-09-18
Technical Paper
2016-01-1926
Matthew Robere
Brake pad to rotor adhesion during exposure to corrosive environments, commonly referred to as “stiction”, continues to present braking engineers with challenges with prediction issues in early phases of development and in resolution once the condition has been identified. The goal of this study took on two parts – first to explore trends in field stiction data and how different testing conditions can help to better duplicate the vehicle issue at the component level, and second to explore the impacts of various brake pad physical properties variation on stiction propensity via a controlled design of experiments. Part one will involve comparison of various productionized hardware configurations on component level stiction tests with different levels of prior braking experience to evaluate conditioning effects on stiction breakaway force.
2016-09-18
Technical Paper
2016-01-1936
Ashesh Anil Shah, Kshitiz Raj
Brake system for any vehicle plays an important role, as safety comes at highest level , also domestic and international safety norms for commercial vehicles are stringent. In current scenario of highly competitive commercial market, Payload advantage comes at peak level in customer demand list, also maintainability plays an important role to make sure least vehicle downtime linked to customer profitability. Finally, if product has less complexity (reducing no. of parts), then it will provide add on benefit to any organization. Considering these customer oriented perspectives mainly payload & maintenance along with regulation compliance , we have proposed new Disc brake system for heavy duty commercial vehicle providing maximum payload benefit along with enhancement in maintainability. It has also enhanced performance and meeting all legislative criteria at aggregate and vehicle level.
2016-09-18
Technical Paper
2016-01-1937
Taylor Erva, Adam Loukus, Luke Luskin
Aluminum metal matrix composite brake rotors with a selective ceramic function reinforcement gradient (FRG) have been developed for automotive applications. This paper will highlight the design, manufacturing, and testing of the rotors. Weight saving of an aluminum composite rotor in comparison to an industry standard cast iron rotor is 50-60%. With this material change comes design considerations to manage rotor temperature, rotor surface integrity, and friction. Manufacturing methods to meet these design constraints were needed to develop a viable high performance aluminum composite rotor. High pressure squeeze casting with soluble coring techniques were developed to incorporate the selective FRG MMC rotors. Dynamometer testing was performed, concentrating on brake friction and temperature to evaluate the macro and micro interfaces in the rotors.
2016-09-18
Technical Paper
2016-01-1935
Binyu Mei, Xuexun Guo, Gangfeng Tan, Ming Chen, Bo Huang, Longjie Xiao
With the continuous increasing requirements of commercial vehicle weight and speed on highway transportation, conventional friction brake is difficult to meet the braking performance. To ensure the driving safety of the vehicle in the hilly region, eddy current retarder has been widely used due to its fast response, lower prices and convenient installation. Electric eddy current retarder breaks the vehicle through the electromagnetic force generated by the current, and converted vehicle mechanical energy into heat through magnetic field. Air cooling structure is often used in the traditional eddy current retarder and cooling performance is limited, which causes low breaking torque, thermal recession, low reliability and so on. A water jacket has been equipped outside the eddy current region in this study, and the electric eddy current retarder is cooled through the water circulating in the circuit, which prolongs its working time.
2016-09-18
Technical Paper
2016-01-1932
Niclas Strömberg
During several years a toolbox for performing virtual rig tests of a brake disc has been developed by the author. A thermo-flexible multi-body model of a test rig is derived and implemented. A thermo-mechanical model of the pad-disc system is formulated including thermo-elasticity, frictional contact and wear. The energy balance at the contact interface is governed by contact conductance that depends linearly on the contact pressure and the frictional heat depends on a temperature dependent coefficient of friction. Instead of adopting a standard Lagrangian approach, the disc is formulated in an Eulerian frame like a fluid. This is then coupled to the pad most accurately by using Signorini’s contact conditions, Coulomb’s law of friction and Archard’s law of wear. The numerical treatment of these laws are performed by applying an augmented Lagrangian formulation, which in turn is solved with a non-smooth Newton method.
2016-09-18
Technical Paper
2016-01-1933
Mingzhuo Li, Dejian Meng, Lijun Zhang
Brake judder severely affects the riding comfort and safety of vehicle. For the brake corner system, a rigid-flexible coupling model are established based on ADAMS. In the model, brake pads, caliper, anchor and knuckle are flexible body, and the contacts between pads and disc and the contact between pads and caliper are defined in detail. Meanwhile, the vibration acceleration of the brake corner components and the contact forces between disc and pads are used as evaluation index and the evaluation system of brake judder are improved. The analysis results show that the novel model and evaluation system can be used to predict brake judder effectively.
2016-09-18
Technical Paper
2016-01-1947
Albert Boretti, Sarim Al-Zubaidy
The operation of a conventional passenger car is characterised by increasing or maintaining kinetic energy when accelerating or cruising the vehicle by using an internal combustion engine, and reducing kinetic energy by using the friction brakes. The energy used by the friction brakes to slow the vehicle with traditional powertrains is gone, dissipated in heat, and never to be recovered. This is a source of endless energy management frustration, and one major obstacle to drastically reduce the fuel consumption in the internal combustion engine. There is however no good reason why it shouldn't be otherwise and it can be done with the introduction of Kinetic Energy Recovery Systems (KERS). Full hybrid and electric vehicles recover the kinetic energy during braking but have very well-known environmental, economic and societal pros and cons.
2016-09-18
Technical Paper
2016-01-1940
Scott Lambert
Industry requirements to improve fuel economy now drive the automotive industry to continually find ways to reduce vehicle mass, particularly to components contributing to ‘un-sprung’ weight. One such component is the steel disc brake backing plate, with commercial vehicle applications weighing as much as 2 kg each; however until now there have been no lightweight alternatives offered. To address this growing requirement, NUCAP Global developed a composite disc plate design which consists of 2 thin-gauge steel facing plates integrally bonded to a phenolic core via mechanical attachment. While the composite design results in the immediate advantage of significant weight reduction, up to 40% on larger vehicle applications, it must also meet or exceed the same function and performance criteria required for solid steel plates by industry standard test methods. Additionally, manufacturability and cost must be factors.
2016-09-18
Technical Paper
2016-01-1941
Tie Wang, Gangfeng Tan, Xuexun Guo, Shengguang Xiong, Zhiwei Zhang, Xin Gao
Vehicle hydraulic retarder is applied in heavy-duty trucks and buses as an auxiliary braking device. In traditional cooling system of hydraulic retarder, working fluid is introduced into heat exchanger to transfer heat to cooling liquid in circulation, whose heat is then dissipated by engine cooling system, not enabling waste heat of working fluid used effectively. In hydraulic retarder cooling system based on Rankine cycle, organic working fluid transfers heat with hydraulic retarder working fluid in Rankine cycle, and then outputs power through expansion machine. It can both reduce heat load of engine cooling system, and enhance thermal stability of hydraulic retarder while recovering and utilizing braking energy. First of all, according to the target vehicle model, hydraulic retarder cooling system model based on Rankine cycle is established.
2016-09-18
Technical Paper
2016-01-1938
Xin Gao, Gangfeng Tan, Binyu Mei, Mengzuo Han, Tie Wang
Hydraulic retarder is an auxiliary brake used by commercial vehicle in long slope brake. Working liquid generates a lot of heat during hydraulic retarder working. If the heat is not properly managed, it will seriously affect hydraulic retarder braking performance. Refrigerant outlet temperature of condenser in Rankine cycle is lower, condensing more fully. But the two-phase area of evaporator reduces or even disappears. Anyhow, Rankine cycle evaporate-condensate system parameter setting not reasonable will affect efficiency of whole system and the temperature stability of hydraulic retarder. The article uses Rankine cycle which refrigerant is R141b to replace hydraulic retarder original cooling system. It can make hydraulic retarder heat exchange in time and working fluid temperature stability in a smaller range.
2016-09-18
Technical Paper
2016-01-1955
Liangyao Yu, Xiaohui Liu, Xiaoxue Liu
The traditional vacuum booster is gradually replaced by Brake-by-Wire system (BBW) in modern passenger car, especially Electric Vehicle. Different from solenoid valve based BBW system, typical BBW system employed in latest vehicle design is using a DC motor to build the brake pressure through a reduction mechanism and a brake master cylinder. Although vehicle's braking performance is greatly improved by using BBW, the system will inevitably consume some energy of the vehicle power supply, thus introducing unexpected drawback in comparison with the traditional vacuum assist braking system, since it doesn't need any electric power. Therefore the analysis of energy consumption on typical DC motor based BBW system under typical driving cycles will contribute to advanced design of current advanced braking system.
2016-09-18
Technical Paper
2016-01-1954
Zhe Xiong, Xiaofei Pei, Xuexun Guo, Chengcai Zhang
In this paper a new pressure control method of a modified accumulator-type Electro-hydraulic Braking System (EHB) is proposed. The system is composed of a hydraulic motor pump, an accumulator, an integrated master cylinder, a pedal feel simulator, valves and pipelines. Two pressurizing modes are switched between by-motor and by-accumulator to adapt different pressure boost demands. A differentiator filtering raw sensor signal and calculating pedal speed is designed. By using the pedal feel simulator, the relationship between wheel pressures and brake force is decoupled. The relationships among pedal displacement, pedal force and wheel pressure are calibrated by experiments. A model-based PI controller with predictor is designed to lower the influences caused by delay. Moreover, a self-tuning regulator is introduced to deal with the parameter’s time-varying caused by temperature, brake pads wearing and delay variation.
2016-09-18
Technical Paper
2016-01-1953
Michael Herbert Putz, Harald Seifert, Maximilian Zach, Jure Peternel
Vienna Engineering (VE) is working since more than eight years on an electro-mechanical brake (EMB) with a special eccentric and highly non-linear actuation mechanism. The principle allows e.g. high brake torque in approx. 50 milliseconds with only approx. 3 A rms actuator current at 12 V. This EMB reached an elaborated state and versions for passenger cars, elevators, railway and commercial vehicles (CVs) were derived. Now, as the EMB is going to road tests, it is necessary to closely fulfill safety requirements. What these safety requirements are and how they can be fulfilled is discussed in this paper: That are properties of the overall system and of the mechanics and electronics of the single brake. The overall brake system for EMBs needs a truly redundant power supply, a safe control bus and a safe brake pedal. The mechanics of a single brake can be required to release when power is off and it must not get mechanically stuck.
2016-09-18
Technical Paper
2016-01-1951
Björn Dingwerth
Brake components happen to operate under some of the harshest conditions a surface on a car may experience. Choosing the right surface finishing is crucial for the component’s overall quality. Selection of the right finish from a choice of alternatives to a large extend is driven by performance, available finishing quality and finally cost of the coating. The zinc-nickel alloy has shown to be an excellent coating for corrosion protection of cast iron hydraulic brake components while being cost competitive with other alternatives. But that corrosion protection is far from being the sole advantage over the other alternatives. There is many other beneficial properties in this zinc-nickel alloy that account for an even faster pace the share of components finished with zinc-nickel grows at in these days.
2016-09-18
Technical Paper
2016-01-1950
Guirong Zhuo, Subin Zhang, Kun Xiong
As is known to all, structure of the chassis has been greatly simplified as the application of in-wheel motor in electric vehicle (EV) and distributed control is allowed. The micro EV can alleviate traffic jams, reduce the demand for motor and battery capacity due to its small size and light weight and accordingly solve the problem that in-wheel motor is limited by inner space of wheel hub. As a result, this type of micro EV is easy to be recognized by the market. In the micro EV above, two seats are side by side and the battery is placed in the middle of the chassis. Besides, in-wheel motors are mounted on rear axle and only front axle retains traditional hydraulic braking system. Based on this driving/braking system, distribution of braking torque, system reliability and braking intensity is analyzed in this paper.
2016-09-18
Technical Paper
2016-01-1948
Axel Freiwald, Gunn Hwang
Axel Freiwald, Infineon Technologies AG Germany Gunn Francis Hwang, Infineon Technologies Korea Co. Ltd Connecting mobile communication channels to vehicles’ networks is currently attracting engineers in a wide range. Herein the desire of vehicle manufacturers to remotely execute software updates over the air (SOTA) within electronic control units (ECU) is probably the field of highest attention at the moment. Today software updates are typically done at vehicle service stations and connecting the vehicles’ electronic network via the onboard diagnosis (OBD) interface to a service computer under the control of trained technicians. SOTA means putting the update process into the hands of the driver.
2016-09-18
Technical Paper
2016-01-1960
Yukihisa Takayama
Vehicle production volumes have been increasing, particularly in newly developing countries that often lack adequate infrastructure. Rolling bearings for automotive wheels, Hub Unit Bearings, used in the developing markets, are required to prevent premature failures due to water ingress. These regions utilize many unimproved roads and frequently experience heavy rainfall, necessitating product features to enhance robustness against exposure to large amounts of contamination and water that may otherwise lead to damage of the Hub Unit Bearing rolling surfaces. Automotive bearings are also required to incorporate low friction technology to reduce overall fuel consumption. Growth in emerging markets tends to increase the amount of global carbon dioxide emissions and the use of low friction technologies in automotive bearings can help mitigate those increases.
2016-09-18
Technical Paper
2016-01-1957
Seonho Lee, Heejae Kang, Ohchul Kwon, Chirl Soo Shin
A trend in automotive parts development is the pursuit of long life, high quality and reliability. The increase in service life of automotive wheel bearings, by improving the rolling contact fatigue (RCF) life of bearing steels, was investigated. Conventional studies of bearing steels and heat treatments have dealt with quenching and tempering (Q/T) in 52100 steel. This study is a new trial to increase the strength of bearing steels by special austempering in phases after general Q/T heat treatments.
2016-09-18
Technical Paper
2016-01-1934
Arun Kumar Prasad, Baskar Anthonysamy, Gopalakrishn V. A., Gurdeep Singh Pahwa
Fierce completion in India’s automotive industry has led to constant production innovation among manufactures. This has resulted in the reduction of the life cycle of the design philosophies and design tools. One of the performance factors that have continues to challenge automotive designer is design and fine tune the braking performance with low cost and short life cycle. Braking performance of automotive vehicle is facilitated by the adhesion between the tyre and the ground. Braking force generated at the wheels of a vehicle have to appropriately match to the adhesion. Antilock braking system (ABS) is used for this purpose. ABS is a modern braking system which could significantly improve directional stability and reduce stopping distance of a vehicle. However this system still too complicated and expensive to use in low end compact car and pickup truck.
2016-09-18
Technical Paper
2016-01-1942
Sarah Chen, Steve Hoxie
Developing a brake system with high overall customer satisfaction rating is a constant challenge for OEMs as well as their brake suppliers. Brake system performance is directly linked to the engagement between the rotor and pads. The materials for the rotors and pads play a key role in the nature of the engagement. Therefore, it is critical to have a good understanding of brake rotor materials to meet performance targets. Due to its superior thermal handling capacity, damping characteristics, wear and cost advantages, gray iron is the most widely used brake rotor material in the industry. G30 per ASTM A48 is generally specified for most brake rotors with minimum tensile strength of 200 Mpa and Brinell hardness of 187~241. G20 is also widely used for brake rotors, especially when people are looking for brake smoothness and optimal pad life. This study has found that variation in gray iron material can considerably affect brake output, wear, DTV, BTV, and noise propensity.
2016-09-18
Technical Paper
2016-01-1915
Meechai Sriwiboon, Seong Rhee, Kritsana Kaewlob, Nipon Tiempan, Rungrod Samankitesakul
Two formulations have been selected and tested for this investigation; Low-Copper NAO and Copper – Free NAO. Each formulation was processed to achieve 3 levels of porosity; 12, 17 and 22%. Each sample was tested for hardness (HRR, HRS, and HRL), natural frequencies and compressibility plus performance testing for friction, wear and brake squeal. This paper describes correlations or lack of them between all the measurements.
2016-09-18
Journal Article
2016-01-1911
Philippe Dufrenoy, Vincent Magnier, Yassine WADDAD, Jean-Francois Brunel, Gery DE SAXCE
A multiscale model of a disc brake including material and surface heterogeneities Y. Waddad; V. Magnier; P. Dufrénoy* ; G de Saxcé University of Lille Cité scientifique Avenue Paul Langevin F-59655 Villeneuve d’Ascq Cedex * Corresponding author : philippe.dufrenoy@univ-lille1.fr During friction it is well known that the real contact area is much lower to the theoretical one and that it evolves constantly during braking. It influences drastically the system’s performance. Conversely the system behavior modifies the loading conditions and consequently the contact surface area. This interaction between scales is well-known for the problematic of vibrations induced by friction but also for the thermomechanical behavior. Indeed, it is necessary to develop models combining a fine description of the contact interface and a model of the whole brake system. This is the aim of the present work. The macroscopic model is obtained with Finite Element analysis.
2016-09-18
Technical Paper
2016-01-1910
Philippe Dufrenoy, Vincent Magnier, Ruddy MANN, Anne-Lise CRISTOL, ITZIAR SERRANO
A methodology to identify the bulk properties of friction material from their formulation V. Magnier; I. Serrano; AL. Cristol ; P. Dufrénoy* University of Lille Cité scientifique Avenue Paul Langevin F-59655 Villeneuve d’Ascq Cedex * Corresponding author : philippe.dufrenoy@univ-lille1.fr Friction materials for braking applications are made of a high number of components leading to bulk properties which guarantee the performances. Development are mainly made by a trial-error methodology due to the misunderstanding of the relationship between formulation and process and properties. In this work we propose to identify this relationship by an experimental methodology combined with microstructural analysis. The first step is the description of the microstructure obtained by tomographic analysis leading to quantitative information about the morphology of the components, their distribution in the volume, orientations, etc.
2016-09-18
Technical Paper
2016-01-1920
Deaglan O'Meachair, Stamatis Angelinas, Matthew Crumpton, Antonio Rubio Flores, Juan Garcia, Pablo Barles
Bentley Motors Ltd. has developed a Carbon Silicon Carbide (CSiC) brake system for it’s Mulsanne product, introduced at 17MY. The CSiC brake system is conceived as a performance brake system, and as such offers notable improvements in brake performance In developing the brake system, particular focus was placed on meeting the refinement levels required for a premium product, and indeed as the flagship model for Bentley Motors, NVH refinement of the brake system was of particular concern. This paper intends to discuss the technical performance of the brake system and review the NVH performance of the brakes. This paper will also demonstrate the effect of vehicle isolation on the cabin NVH, and ultimately the passenger experience, by comparing the noise and vibration content in the wheel arch with that apparent to the driver.
2016-09-18
Technical Paper
2016-01-1912
Bo Hu, Sydney Luk, Peter Filip
Copper and copper alloys are widely used in friction materials such as brake pad formulations as one of key ingredients by providing good thermal conductivity and high temperature friction stability to achieve desired friction performance, fade and wear resistance. However, the use of copper or copper containing material is being restricted in brake pads due to environment and health concerns. Extensive works have been made to explore the copper substitutes but most of these efforts became ineffective and failed with issues either thermal fade or excessive pad/rotor wear. In this paper, friction and wear responses were examined when a metallic composite material was used as the copper substitute in NAO and Low-met brake formulations where the copper and copper alloys were added 8% and 22% respectively.
2016-09-18
Journal Article
2016-01-1943
Tadayoshi Matsumori, Yoshitsugu Goto, Noboru Sugiura, Kenji Abe, Yoshihiro Osawa, Yosuke Akita, Satoshi Wakamatsu, Katsuya Okayama, Kyoko Kosaka
Abstract This paper deals with friction under wet condition in the disk brake system of automobiles. In our previous study, the variation of friction coefficient μ was observed under wet condition. And it was experimentally found that μ becomes high when wear debris contains little moisture. Based on the result, in this paper, we propose a hypothesis that agglomerates composed of the wet wear debris induce the μ variation as the agglomerates are jammed in the gaps between the friction surfaces of a brake pad and a disk rotor. For supporting the hypothesis, firstly, we measure the friction property of the wet wear debris, and confirm that the capillary force under the pendular state is a factor contributing to the μ variation. After that, we simulate the wear debris behavior with or without the capillary force using the particle-based simulation. We prepare the simulation model for the friction surfaces which contribute to the friction force through the wear debris.
2016-09-18
Journal Article
2016-01-1944
Seongjoo Lee, JeSung Jeon, ShinWook Kim, ShinWan Kim, Seong Rhee, Wan Gyu Lee, Young Sun Cho, Jeongkyu Kim
When two identical brakes are simultaneously tested on a vehicle chassis dynamometer, very often the left hand brake is found to squeal more or less than the right hand brake, all at different frequencies. This study was performed to develop some understanding of this puzzling phenomenon. It is found that as the wear rate difference between the inner pad and the outer pad increases, low frequency (caliper and knuckle) squeals occur more and more, and as the differential wear becomes larger and larger, high frequency (disc) squeals occur less and less, finally disappearing all together. Discs and calipers are found to affect the differential pad wear, in turn affecting brake squeal generation.
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