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2014-09-28
Technical Paper
2014-01-2494
Mithun Selvaraj, Suresh Gaikwad, Anand Kumar Suresh
Abstract The highest goal for a good brake system design must be that the vehicle when braking obtains a shorter stopping distance does not leave the track and remains steerable. From the perspective of road traffic, safety and for avoidance of accidents the time and location of a vehicle coming to halt after braking are crucial. In heavy commercial vehicle having longer wheel base, pneumatic brake system is being used.The pneumatic brake system configuration has to be designed in such a way that the response time should meet the safety regulation standards and thereby achieve shorter stopping distance and vehicle stability. Validating the effectiveness of pneumatic brake system layout experimentally on stopping distance and vehicle stability is expensive.
2014-09-28
Technical Paper
2014-01-2491
SeongJoo Lee, JooSeong Jeong, ShinWook Kim, ShinWan Kim, Seong Rhee
A previous investigation showed that minor variations in alloying elements in gray cast iron disc contributed to measurable differences in friction and disc wear. This investigation was undertaken to find out if and how the increased friction and disc wear might affect brake squeal. The SAE J2522 and J2521 dynamometer procedures as well as an OEM noise dynamometer procedure and a chassis dynamometer noise procedure were used to find out if a correlation between disc wear and brake squeal could be discovered. In all cases, as the wear rate of a disc increases under a given set of test conditions, disc material transfer to the pad surface increases, which results in increased friction and brake squeal. Also a good method to detect disc variability (disc to disc, within a disc) is discussed.
2014-09-28
Technical Paper
2014-01-2493
Juan Carlos Martinez Laurent, Adrian Jordan, Francisco Canales
Abstract The brake system and components are essential active safety systems for users of motor vehicles, one common NVH phenomenon known as Brake Disc Thermal Coning creates a perception of poor braking system performance. Although Brake Disc Thermal Coning does not deteriorate the braking distance or the vehicle performance, is a concern for the customer who identifies any undesired vibration as a potential performance loss resulting in complaints and warranty claims. In order to increase the quality, and reliability of the products, Automotive OEMs have created processes and tests, today incorporating the ones based in computational solutions, to identify, prevent and correct potential issues before its present in the final product.
2014-09-28
Technical Paper
2014-01-2522
Tobias Schramm, Georg Peter Ostermeyer
Abstract There are few principal excitation mechanisms that brake system NVH simulations are based on, especially the high frequency squeal simulations. These mechanisms can be described by some simple mechanical models that exhibit excitation or self-excitation effects induced by friction [1, 2]. These models use very simple friction laws of Coulomb type, described by a friction coefficient that is either a constant or simple functions of some state variables, taking into account a Stribeck characteristic. Measurements from the AK-Master or SAE J2521, however, show that the friction coefficient is not a simple function of some state variables, describing a steady state behavior of friction. In the past several years, material dependent descriptions of the frictional brake interface have started attracting attention [3]. These aspects are greatly influenced by the tribological effects at the frictional interface, which can be characterized by typical wear patterns.
2014-09-28
Journal Article
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.
2014-09-28
Technical Paper
2014-01-2520
Qiang Wang, Gang Qi, Guangrong Zhang, Xinyu Pu
Abstract A brake durability experimental method is proposed to simulate a brake durability vehicle road test. Brake judder and noise often occur in brake durability road testing. Brake judder is difficult to address because of its many potential causes, such as assembly run out, component stiffness, lining characteristics, thermal coning/hot spot/thermal instability and corrosion. There are currently several test procedures to predict brake thermal roughness and pad cleaning corrosion performance for preventing brake judder. Brake durability vehicle road testing is performed to check brake NVH and wear; examples include the Mojacar test in Spain and the Huangshan test in China. Brake energy intensity and road vibration are the significant factors that cause brake rotor thickness variation, which generates brake judder in public road testing.
2014-09-28
Technical Paper
2014-01-2519
ByeongUk Jeong, Hoon Kim, Woochul Kim, Sang Do Kwak
Abstract Owing to the enhanced performance of engines these days, more heat should be dissipated in the braking system. Failure of doing this properly causes temperature rise in the brake disc which result in the brake fade, disc distortion, brake judder, etc. A cooling-air-duct was proposed as a solution to prevent these from happening. In this paper, we present our work based on experiments optimized parameters such as direction, location, shapes and the size of the duct for the cooling-air-duct installation in real cars. We installed the duct extended from a front bumper to a rear wheel guard. Experimental parameters were compared with theoretical analysis using the impinging jet analysis. The heat transfer coefficients were determined by using the finite elements method (FEM). We found that our experimental data is supportive of theoretical analysis. We believe that our results should serve an useful guideline for designing the cooling-air-duct for braking system.
2014-09-28
Technical Paper
2014-01-2518
Diego Masotti, Ney Ferreira, Patric Neis, Ademir Menetrier, Luciano Matozo, Paulo Varante
Abstract Creep groan is a low-frequency (20-300Hz) self-excited brake vibration caused by stick-slip phenomena at the friction interface observed at very low vehicle speed. The creep groan propensity of friction materials is closely related with the difference (Δμ) between the static (μs) and the kinetic (μk) coefficients of friction. In this study, a NAO brake pad material was used as a base formulation and the abrasives tested were commercial grade of black iron oxide, chromite, zirconium oxide, magnesium oxide and aluminum oxide. Experimental results were obtained by testing seven different friction material formulations, in which the type of abrasives or its hardness or its particle size was changed in order to explore the impact of these variables on the stick-slip occurrence. A laboratory-scale tribometer was used to investigate the influence of different types of abrasives and their physical properties in the stick-slip.
2014-09-28
Technical Paper
2014-01-2517
Kun Diao, Lijun Zhang, Dejian Meng
Abstract Disc brake squeal has always been a great challenge to the automotive industry. Based on the pin-on-disc system, a series of frictional squeal bench tests are carried out, which show significant time-varying characteristics on occurrence, sound pressure and frequency of frictional squeal. To investigate the generation mechanism of time-varying characteristics of frictional squeal, a four-degree-of-freedom (4DOF) lumped parameter model considering the time-varying tangential contact stiffness, the normal contact stiffness and the friction coefficient is established in this paper. Through both the system stability analysis and the transient response analysis, the time-varying frictional squeal is predicted successfully, and the generation mechanism and the key impact factors are also investigated in depth.
2014-09-28
Technical Paper
2014-01-2516
Katsuhiro Uchiyama, Yuji Shishido
Abstract Last year, we presented the “spring - mass model” FEA simulation from stick-slip phenomenon standpoint for improvement of “creep groan”. “Creep groan” is one of representative groan of brake system for automobile and it is clarified by µ vs velocity (µ−V) property of friction material. This time, we will present our study for reduction of creep groan by pad shape parameter (chamfer and slot) with “advanced” spring - mass model” FEA simulation which used actual pad shape as mass model. In addition, this paper was revised based on oral presentation which we presented at SAE 2013.
2014-09-28
Technical Paper
2014-01-2515
Jin kuk Park, Hyun Bum Jung, Min Gyu Han, Nam ill Jeon
Abstract Prediction of noise and vibration of a gear train is important to achieve a competitive design. Objective of this paper is to develop a dynamic simulation model for vibration analysis and a synthesis process to predict vehicle interior noise using TPA (Transfer Path Analysis). The hybrid gear model is developed to simulate the stiffness of teeth and meshing characteristics in a gear pair. It is modeled by using the teeth stiffness map which is following real contact characteristics of a gear pair. The teeth stiffness is obtained by structural analysis. The multi-body model is composed of flexible bodies, shafts and nonlinear bearings. Input forces at the mounting point (input point) of the gear train are calculated by accelerations from dynamic analysis under real operating conditions. Calculated forces are used to synthesize a vehicle interior noise. Predicted noise is compared with experiment data.
2014-09-28
Technical Paper
2014-01-2514
Prashant Mahale, Aziz Bohari, Raajha M P
Abstract Brake noise is an emerging concern in Indian Auto-industry; with brake squeal being the most evident form of brake NVH. Squeal noise generation attributes to many parameters including kinematics of braking parts during pressure application, structural dynamic behavior which in turn depends on coupling at resonant frequencies of different parts of a brake assembly, material of brake parts, operating clearances in the mating parts etc. The genesis of brake squeal lies in the generation of unstable frictional forces during braking event. These frictional forces induce uncontrolled amplification of brake parts vibration, which in turn tend to produce perceivable sound or noise. The magnitude this vibration induced squeal depends on co-efficient of friction, braking pressure, speed and temperature of friction material.
2014-09-28
Technical Paper
2014-01-2513
Taeho Jung, Jeongkyu Kim
Abstract Rust accumulated on disc surfaces causes brake judder and grind noise. This paper deals with grind noise(wire brush brake noise) in vehicles which is a low frequency vibration and broadband noise problem at 100∼1kHz that appears in low vehicle speed. Recently, the customer complaints have increased for grind and creep groan noise more than squeal noise. Low frequency brake noise is a combined effect of brake and suspension systems working with each other. The noise transfer path is also important. Experimental results are confirmed through ODS, Modal, TPA and 3D acoustic camera for noise transmission path. Finally, reduction methods of grind noise are presented.
2014-09-28
Technical Paper
2014-01-2512
Hidetoshi Shimizu, Yasunori Oura, Tatsuya Suzuki, Yoshinori Sano
Abstract SAE J2521 noise tests are conducted to examine the impact of shim and grease on brake squeal generation. The impact of adhesive (bonded) shim, clip-on shim and grease for noise generation are examined. Low frequency squeal is eliminated by the application of grease on both adhesive (bonded) shims and clip-on shims. The role of shim and grease for reducing brake squeal is discussed. Adhesive (bonded) shims were found to be effective for high frequency squeal (pad bending mode) by increasing damping. Grease is effective for low frequency squeal (pad rigid mode). The mechanism to eliminate low frequency squeal by the application of grease is investigated. Friction between the shim and caliper piston/finger is reduced. Pads contact directly to the anchor bracket. As a result the contact stiffness is increased. The mechanism is confirmed by experiments.
2014-09-28
Technical Paper
2014-01-2511
Nils Gräbner, Merten Tiedemann, Utz Von Wagner, Norbert Hoffmann
Abstract Industry and academia agree that brake squeal is a nonlinear phenomenon. Consequently, using solely linear finite-element (FE) models and assessing the tendency of a brake system to squeal exclusively on the stability of the trivial solution is not appropriate. However, the latter approach - in the brake community known as complex eigenvalue analysis (CEA) - is extensively used in industry. Until now, nonlinear simulation approaches considering existence and stability of periodic solutions are mostly limited to minimal models. Among the variety of reasons for this the complexity of large-scale nonlinear models as well as the identification of nonlinear material and system parameters are crucial. This contribution discusses the relevance of nonlinearities in friction brake noise, vibration, harshness (NVH) and presents a novel simulation approach for brake squeal.
2014-09-28
Technical Paper
2014-01-2510
Jung Hoon Woo, Jeongkyu Kim, Kwang Yun Kim, Daekyung Ko
Abstract Creep groan noise occurs in a just moving vehicle by the simultaneous application of torque to the wheel and the gradual release of brake pressure in-vehicle. It is the low frequency noise giving the driver a very uncomfortable feeling. It is caused by the stick-sleep phenomenon at the lining and disc interface. Recently, the field claim of low frequency creep groan has increased. There are a lot of efforts to improve creep groan noise by means of modification of lining material. In this paper, Transfer path of creep groan noise was analyzed through ODS and TPA. Additionally the correlation between Source (Brake torque variation, Brake vibration) and Creep Groan Sound level was discussed. Finally countermeasure to Creep Groan noise was suggested.
2014-09-28
Technical Paper
2014-01-2509
N. Prabhakar, J. Suresh Gayakwad, K. Muthumanickam, E. Nagaraj
Abstract The present investigation deals with the failure load prediction during the wrong procedure of unlocking the hand brake valve. The design of the hand brake valve top cover should have adequate strength such that the driver cannot move the lever without lifting the sleeve during brake off condition. The objective of this work is to design the top cover with higher strength such that it requires more load during wrong procedure of unlocking the valve. In this study, the nonlinear analysis is conducted (which includes three types of nonlinearities namely material, geometry and contact) in order to study the strength of the top cover during abuse condition. The design adequacy of the top cover is estimated by elasto plastic analysis. The maximum load carrying capacity of the top cover is determined from Force Vs Deformation plot which is good in agreement with the experimental results. Various design iterations are carried out to propose the appropriate design.
2014-09-28
Technical Paper
2014-01-2508
Stanislav I. Pliassounov
Abstract The article discusses the common shortcomings of contemporary standardized automotive brake tubing connectors (tube joints) against the modern requirements. These shortcomings are originated in the inborn disadvantages of currently utilized cone-to-cone sealing surfaces' mating. During last decade modern production excellence mindset and lean manufacturing practice have developed additional requirements to the tube joints, with the focus on their assembly process. Correspondingly, at least 99.9% probability to assemble and seal each connector from the very first attempt at the designated assembly station is necessary to resolve the challenge. The article deliberates that 99.9% probability as the design target in pursuing connectors' excellence. The article also discusses the pathway to the connectors' design perfection via replacement of the existing cone-to-cone mating type between the sealing surfaces with a sphere-to-cone one.
2014-09-28
Technical Paper
2014-01-2507
Guoling Wang, Xuexun Guo, Quan Zhou
Abstract Air disc brake (ADB) is the execution unit of automobile brake, which plays a vital role in traffic safety. Lever is a very important driving as well as stress part of ADB. However, seldom periodical or thesis has given specifications about the lever. In this paper, working principle of the lever is illustrated in detail. Finite element analysis (FEA) of the lever is conducted and some structural problems of the lever are found out. Finally, for the condition that the lever doesn't meet the strength requirement, topography optimization is introduced to improve the shape of lever. Simulation results show that the strength of the lever improved obviously with the optimization, and analysis method as well as optimization method in this paper is feasible.
2014-09-28
Technical Paper
2014-01-2536
Alberto Boretti, Stefania Zanforlin
Abstract Real driving cycles are characterized by a sequence of accelerations, cruises, decelerations and engine idling. Recovering the braking energy is the most effective way to reduce the propulsive energy supply by the thermal engine. The fuel energy saving may be much larger than the propulsive energy saving because the ICE energy supply may be cut where the engine operates less efficiently and because the ICE can be made smaller. The present paper discusses the state of the art of hydro-pneumatic drivelines now becoming popular also for passenger cars and light duty vehicle applications permitting series and parallel hybrid operation. The papers presents the thermal engine operation when a passenger car fitted with the hydro-pneumatic hybrid driveline covers the hot new European driving cycle. From a reference fuel consumption of 4.71 liters/100 km with a traditional driveline, the fuel consumption reduces to 2.91 liters/100 km.
2014-09-28
Technical Paper
2014-01-2537
Zhizhong Wang, Liangyao Yu, Yufeng Wang, Kaihui Wu, Ning Pan, Jian Song, Liangxu Ma
Abstract The four-wheel-independent Electro-hydraulic Braking system (4WI EHB) is a wet type Brake-by-Wire system for passenger vehicle and is suitable for electric vehicle (EV) and hybrid electric vehicle (HEV) to cooperate with regenerative braking. This paper gives a review on the design concepts of the 4WI EHB from the following three aspects. 1. Hydraulic architectures. 2. Design concepts of the brake actuator. 3. Installation of the components on the vehicle. Simulations and experiments are carried out to further explore the performance of hydraulic backup and implicit hardware redundancy (IHR). A method to integrate the IHR with hydraulic backup without increasing the total amount of valves is proposed, making the IHR cost and weight competitive. By reviewing various design concepts and analyzing their advantages and drawbacks, a cost and weight competitive design concept of the 4WI EHB with good fail-safe and fault-tolerant performance is proposed.
2014-09-28
Technical Paper
2014-01-2539
Dongmei Wu, Haitao Ding, Konghui Guo, Yong Sun, Yang Li
Abstract Four-wheel-drive electric vehicles (4WD Evs) utilize in-wheel electric motors and Electro-Hydraulic Braking system (EHB). Then, all wheels torque can be controlled independently, and the braking pressure can be controlled more accurately and more fast than conventional braking system. Because of these advantages, 4WD Evs have potential applications in control engineering. In this paper, the in-wheel electric motors and EHB are applied as actuators in the vehicle stability control system. Based on the Direct Yaw-moment Control (DYC), the optimized wheel force distribution is given, and the coordination control of the hydraulic braking and the motor braking torque is considered. Then the EHB hardware-in-the-loop test bench is established in order to verify the effectiveness of the vehicle stability control algorithm through experiments.
2014-09-28
Technical Paper
2014-01-2531
Mandeep Singh Walia, Magnus Karlsson, Lars Hakansson, Gaurav Chopra
Abstract An analysis method to study the potentials of recovering the brake energy from Volvo articulated haulers has been developed. The study has been carried out with purpose to find out how and where possible hybrid solutions can be used. The method is based on the mapping of the peak brake power, brake energy and engine energy. This method was developed using adequate signals collected on haulers at three different customer sites. A conceptual study was also carried out concerning the brake energy to understand the actual amount of brake energy that may be stored in an Energy storage system (ESS). The results indicate that the analysis method developed can map the brake energy generated and also provide an overview of the actual amount of brake energy that can be accumulated in an ESS. Hence, the method may also providing guidelines regarding the selection of an ESS for a particular work site.
2014-09-28
Technical Paper
2014-01-2529
Klaus Augsburg, Dzmitry Savitski, Lukas Heidrich, Valentin Ivanov
Abstract The presented research discusses the experimental procedure developed for testing of friction brake systems installed on the modern electric vehicles. Approach of combined experimental technique utilizing hardware-in-the-loop platform and brake dynamometer is introduced. As the case study, an influence of brake lining coefficient of friction fluctuations on the anti-lock brake system (ABS) performance is investigated. The ABS algorithm is represented by the direct slip control aimed to the precise tracking of reference slip ratio by means of electric and friction brake system. Vehicle prototype is represented by RWD electric vehicle with in-wheel motors. Results, representing the investigated phenomenon, are derived using the developed combined test bench. The achieved results give a basis for further extension of standard brake testing procedures.
2014-09-28
Technical Paper
2014-01-2527
Gunn Hwang, Axel Freiwald, Hyun-Sik Ahn
Abstract Currently major investments by Tier1 and vehicle manufacturers are made to implement and optimize safety critical automotive systems according to the ISO standard 26262 “Road vehicles functional safety”. The ISO 26262 standard describes methods to detect the safety critical faults of a system designed according to the rules of functional safety, but it does not describe how an actual implementation shall look like. Development of ISO 26262 standard compliant systems concentrates on optimizing and improving cost and performance in a competitive environment. More competitive and practical implementations use fewer additional hardware and software resources for safety control and error detection and have higher performance with less overhead. Microcontrollers already have implemented many safety related hardware functions, so called safety mechanisms to mitigate safety critical risks.
2014-09-28
Journal Article
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.
2014-09-28
Journal Article
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.
2014-09-28
Journal Article
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.
2014-09-28
Journal Article
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.
2014-09-28
Journal Article
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.
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