Display:

Results

Viewing 91 to 120 of 10739
2016-09-18
Journal Article
2016-01-1948
Axel Freiwald, Gunn Hwang
Abstract Vehicle manufacturers are suffering from increasing expenses for fixing software issues. This fact is mainly driving their desire to use mobile communication channels for doing Software Updates Over The Air (SOTA). Software updates today are typically done at vehicle service stations by connecting the vehicles’ electronic network via the On Board Diagnostic (OBD) interface to a service computer. These operations are done under the control of trained technicians. SOTA means that the update process must get handled by the driver. Two critical aspects need to get considered when doing SOTA at Electronic Brake Control (EBC) systems. Both will determine the acceptance of SOTA by legal authorities and by the passengers: The safety and security of the vehicle The availability of the vehicle for the passengers The security aspect includes the necessity to protect the vehicle and the manufacturers IP from unwanted attacks.
2016-09-18
Journal Article
2016-01-1929
Nimrod Kapas, Ajith Jayasundera
Abstract There is an increasing interest in transient thermal simulations of automotive brake systems. This paper presents a high-fidelity CFD tool for modeling complete braking cycles including both the deceleration and acceleration phases. During braking, this model applies the frictional heat at the interface on the contacting rotor and pad surfaces. Based on the conductive heat fluxes within the surrounding parts, the solver divides the frictional heat into energy fluxes entering the solid volumes of the rotor and the pad. The convective heat transfer between the surfaces of solid parts and the cooling airflow is simulated through conjugate heat transfer, and the discrete ordinates model captures the radiative heat exchange between solid surfaces. It is found that modeling the rotor rotation using the sliding mesh approach provides more realistic results than those obtained with the Multiple Reference Frames method.
2016-09-18
Journal Article
2016-01-1930
Heewook Lee
Abstract Contamination protection of brake rotors has been a challenge for the auto industry for a long time. As contamination of a rotor causes corrosion, and that in turn causes many issues like pulsation and excessive wear of rotors and linings, a rotor splash protection shield became a common part for most vehicles. While the rotor splash shield provides contamination protection for the brake rotor, it makes brake cooling performance worse because it blocks air reaching the brake rotor. Therefore, balancing between contamination protection and enabling brake cooling has become a key critical factor when the splash shield is designed. Although the analysis capability of brake cooling performance has become quite reliable, due to lack of technology to predict contamination patterns, the design of the splash protection shield has relied on engineering judgment and/or vehicle tests. Optimization opportunities were restricted by cost and time associated with vehicle tests.
2016-09-18
Journal Article
2016-01-1931
Aaron Völpel, Georg Peter Ostermeyer
Abstract In today’s research and development of brake systems the model-based prediction of complex vibrations and NVH phenomena plays an important role. Despite the efforts, the high dimensional computational simulation models only provide a limited part of the results gained through experimental measurements. Several reasons are discussed by the industry and academic research. One potential source of these inadequacies is the very simple formulation of the friction forces in the simulation models. Due to a significant shorter computation time (by orders of magnitude), the complex eigenvalue analysis has been established, in comparison to the transient analysis, as the standard method in the case of industrial research, where systems with more than one million degrees of freedom are simulated.
2016-09-18
Journal Article
2016-01-1939
Toshikazu Okamura
Abstract Brake judder is one of the most serious problems in automotive-brake systems. It is basically a forced vibration caused by the friction-surface geometry of a brake disc, and therefore, disc rotors play a significant role in judder. There are two types of judder: cold and hot. Hot judder is caused by the thermo-mechanical deformation of a brake disc due to high-speed braking. There are several shapes of deformation, e.g., coning and circumferential waviness. Circumferential waviness is caused by thermo-mechanical buckling and typically found as a butterfly shape in a 2nd rotational-order and hot-spotting. In a previous paper, two groups of disc castings with different material homogeneity were machined intentionally to have two kinds of dimensional variations.
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.
2016-09-18
Journal Article
2016-01-1949
John David Fieldhouse, Joe Gelb
Abstract The design of a braking system involves a delicate balance between the friction pair, the disc and pad, where the pad is a complex blend of constituents to provide predictable characteristics, typically, a known and consistent friction level. In its base form the brake has to absorb the vehicle kinetic energy by converting it into heat. This heat absorption by the friction pair can result in chemical and physical interactions with the release of debris about which we know little. Other than environmental concerns, brake dust causes unnecessary problems with wear, thermal gradients (hot banding) and NVH. This paper is concerned with the removal and collection of brake debris from the friction interface - the debris being regarded as solids and airborne particles, the latter less than 10μm in size. The test procedure consisted of a Burnish program followed by 8 different drive cycles. The overall effects of debris removal is then reported for each test.
2016-09-18
Journal Article
2016-01-1959
Laura Sguotti, Davide Olivieri, Domenico Bosco
Abstract Bearing friction is a direct contribution to vehicle CO2 emissions. The friction is defined as the total resistance to rotation, resulting from the combination of rolling and sliding friction in the contact areas. First, friction reduction was approached from a theoretical standpoint by employing modeling and simulation techniques. Improvements identified in simulation were then used to: create a new set of design rules for the internal geometry of the bearing, introduce a new grease, develop new seals, also with the integration of labyrinth functions and an optimization of the preload range variation. In order to provide a reliable confirmation of the expected achievements, a new friction measurement methodology was also introduced.
2016-09-18
Journal Article
2016-01-1958
Seungpyo Lee, Nahyon Lee, Jongkeun Lim, Jungyang Park
Abstract Through transmitting power and carrying vehicle weight, automotive wheel bearings play an important role. Counterbalancing the bearing responsibilities, they also are designed to last the life of a vehicle without servicing. When mounted to the vehicle steering knuckle by bolts, distortion occurs to the outer ring. Performance is affected when distortion takes place at the seal mounting location and raceways. Finite element analysis using commercial software was performed to analyze the outer ring distortion. Elasto-plastic and contact analyses were carried out to compute the clamping behavior of the outer ring, bolts and the knuckle under various conditions. To verify the reliability of this study, the distortion of the outer ring was measured. The experimental results proved to be comparative with the analysis results.
2016-09-18
Journal Article
2016-01-1923
Lorne R. Dyar, Yuichiro Akita, Scott Paul, Joseph Lepito, Yoshio Ishikawa, Tomohiro Watanabe
An advanced braking system had to be developed for a next-generation hybrid sports car with Sport Hybrid Super Handling All-Wheel Drive to achieve an intuitive brake feeling in a variety of driving conditions, ultimate track performance and reduction of CO2 emissions per vehicle. This paper outlines the integration of brake-by-wire with traditional high-performance braking hardware and describes the technology needed to achieve these goals. Key focus areas to generate these results were: brake feeling control, corner hardware specification considerations and brake cooling.
2016-09-18
Journal Article
2016-01-1925
David B. Antanaitis
Abstract The strong focus on reducing brake drag, driven by a historic ramp-up in global fuel economy and carbon emissions standards, has led to renewed research on brake caliper drag behaviors and how to measure them. However, with the increased knowledge of the range of drag behaviors that a caliper can exhibit comes a particularly vexing problem - how should this complex range of behaviors be represented in the overall road load of the vehicle? What conditions are encountered during coastdown and fuel economy testing, and how should brake drag be measured and represented in these conditions? With the Environmental Protection Agency (amongst other regulating agencies around the world) conducting audit testing, and the requirement that published road load values be repeatable within a specified range during these audits, the importance of answering these questions accurately is elevated. This paper studies these questions, and even offers methodology for addressing them.
2016-09-18
Journal Article
2016-01-1911
Philippe Dufrenoy, Vincent Magnier, Yassine WADDAD, Jean-Francois Brunel, Gery DE SAXCE
Abstract 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. A multiscale strategy is propose to integrate the microscopic behavior of the interface in a macroscopic numerical model. Semi-analytical resolution is done on patches at the contact scale while FEM solution with contact parameters embedded the solution at the microscale is used. Asperities and plateaus are considered at the contact interface.
2016-09-18
Journal Article
2016-01-1919
Joo Sang Park, Min Gyu Han, Seon Yeol Oh
Abstract This paper introduces the experimental test results of an investigation to understand the relationship between the leading offset and squeal propensity. In addition Transient Analysis (TA) and Complex Eigenvalue Analysis (CEA) are used simultaneously as a means to compare the experimental approach to two different numerical tools, so evaluating the validity of each theoretical approach. To confirm the CAE results. An ODS was recorded of the brake using a 3D laser scanning vibrometer. Even though the CEA approach is very popular in the study of brake squeal noise, there are some limitations and difficulties in replicating the real phenomenon especially containing unstable behavior. The differences are due to weak pad contact stiffness and friction characteristics which are dependent on the relative interface velocity between pad and rotor. It is necessary to consider stick-slip vibration and time domain analysis in addition.
2016-09-18
Journal Article
2016-01-1927
Christian Riese, Frank Gauterin
Abstract New technologies like alternative power trains and driver assistance systems have a big impact on brake system development. Most of the development work aims at the improvement of the actuation and modulation components of the brake system. The basic hydraulic network remained nearly the same over decades and still has to meet these new requirements. Previous papers have focused mainly on studying the behavior of single components, like for example the brake hose fluid consumption in detail. Other papers studied the complete system but simplified it extremely, so that some relevant effects are neglected. In this work, one focus is to study the influence of single relevant components, like the hydraulic unit and the hoses on the overall system performance. For this measurements with a complete hydraulic brake system, including a state of the art electromechanical brake booster and single component measurements for identification, are conducted.
2016-09-18
Journal Article
2016-01-1914
Pavlina Peikertova, Miroslava Kuricova, Alena Kazimirova, Jana Tulinska, Magdalena Barancokova, Aurelia Liskova, Marta Staruchova, Mira Horvathova, Silvia Ilavska, Eva Jahnova, Michaela Szabova, Miroslav Vaculik, Jana Kukutschova, Karla Kucova, Maria Dusinska, Peter Filip
Abstract Particulate air pollution from road traffic currently represents significant environmental and health issue. Attention is also paid to the “non-exhaust pollution sources,” which includes brake wear debris. During each brake application, the airborne and nonairborne particles are emitted into the environment due to wear. High temperatures and pressures on the friction surfaces initiate chemical and morphological changes of the initial components of brake pads and rotating counterparts. Understanding of impact of matter released from brakes on health is vital. Numerous studies clearly demonstrated that particulate matter caused potential adverse effects related to cytotoxicity, oxidative stress, stimulation of proinflammatory factors, and mutagenicity on the cellular level. This paper compiles our main results in the field of genotoxicity, immunotoxicity, and aquatic toxicity of airborne brake wear particles.
2016-09-18
Journal Article
2016-01-1915
Meechai Sriwiboon, Seong Rhee, Kritsana Kaewlob, Nipon Tiempan, Rungrod Samankitesakul
Abstract As some brake engineers believe that brake squeal can be related to pad hardness, friction coefficient or compressibility while others disagree, a study has been undertaken to develop further insights. Two commercial formulas, one low-copper NAO and the other copper-free NAO, were made into disc pads of varying porosity without an underlayer and they were checked for specific gravity, porosity, hardness (HRS and HRR), natural frequencies, compressibility, friction, wear and squeal. With increasing porosity, the hardness and natural frequencies continue to decrease. The compressibility definitely does not increase, but rather slightly decrease or stays the same. The coefficient of friction decreases for the low-copper along with pad and disc wear reduction, and increases for the copper-free along with pad wear increase with no change in disc wear. No obvious correlation emerges between brake squeal and pad hardness, friction coefficient or compressibility.
2016-09-16
WIP Standard
J2806
Subject document is specifically intended for service brakes and service brakes when used for parking and/or emergency brakes (only) that are commonly used for automotive-type, ground wheeled vehicles exceeding 4536 kg (10 000 US lb) Gross Vehicle Weight Rating (GVWR). Subject specification provides the off-vehicle procedures, methods, and processes used to objectively determine suitability of tactical and combat ground wheeled vehicle brake systems and selected secondary-item brake components (a.k.a. aftermarket or spare parts), including brake “block” for commercial applications only, specifically identified within subject document. Subject specification is primarily based on known industry and military test standards utilizing brake inertia dynamometers. Targeted vehicles and components include, but may not be limited to the following: a.
CURRENT
2016-09-16
Standard
J1981_201609
The test is designed to evaluate the frontal impact resistance of wheel and tire assemblies used with passenger cars, light trucks and multi-purpose vehicles. The test is specifically related to vehicle pothole tests that are undertaken by most vehicle manufacturers. The scope has been expanded to allow the use of a striker that can be angled to preferentially impact the inboard and outboard wheel flange. For side impact of the outboard rim flange only, please refer to SAE J175. This SAE Recommended Practice provides a procedure to test a wheel or a tire and the test failure critiera. The specific test for a vehicle requires input from a pothole test on that vehicle to establish the drop height of the striker used in this test.
2016-09-16
Journal Article
2016-01-9018
Judhajit Roy, E. Harry Law
Abstract It is well known that the ride quality of trucks is much harsher than that of automobiles. Additionally, truck drivers typically drive trucks for much longer duration than automobile drivers. These two factors contribute to the fatigue that a truck driver typically experiences during long haul deliveries. Fatigue reduces driver alertness and increases reaction times, increasing the possibility of an accident. One may conclude that better ride quality contributes to safer operation. The secondary suspensions of a tractor have been an area of particular interest because of the considerable ride comfort improvements they provide. A gap exists in the current engineering domain of an easily configurable high fidelity low computational cost simulation tool to analyze the ride of a tractor semi-trailer. For a preliminary design study, a 15 d.o.f. model of the tractor semi-trailer was developed to simulate in the Matlab/Simulink environment.
2016-09-14
WIP Standard
J257
The minimum performance values in this SAE Recommended Practice are applicable to vehicles with brake systems having typical service pressure ranges 0 to 16.6 MPa (0 to 2400 psi) hydraulic or 0 to 945 kPa (0 to 135 psi) air only. SAE J880 not only provides for determining maximum brake rating power capability, but also permits verification of any desired or arbitrary level such as the requirement established herein. The determining criteria for deciding brake rating power capability are: a. Cold brake stopping ability. b. Fade as a result of brake power absorption. c. Hot brake stopping ability following brake power absorption. d. Brake system stability following brake power absorption. e. Functional and structural integrity of brake system following test.
2016-09-14
Technical Paper
2016-01-1871
Renxie Zhang
Abstract Path following controller of a six-wheel skid-steering vehicle is designed. The vehicle speed is controlled through engine speed control and the lateral vehicle steering is controlled through hydraulic braking on each side. Contrary to the common approaches considering non-holonomic constraints, vehicle dynamic characteristics and nonlinear characteristics of tire are considered. A hierarchical control structure is applied in this vehicle control system. The kinematic controller works out the reference yaw rate and reference vehicle speed. And a robust dynamic controller tracks the reference signal. In addition, the dynamic controller takes actuator ability into account.
2016-09-14
Technical Paper
2016-01-1886
Zhuoping Yu, Yi Zhang, Lu Xiong, Songyun Xu
Abstract With development of vehicle advanced driver assistant system and intelligent techniques, safer and more intelligent Integrated-Electro-Hydraulic Braking System is required to realize brake-by-wire. Thus, more and more companies and universities developed Integrated-Electro-Hydraulic Braking System to fulfill these requirements. In this paper, an Integrated-Electro-Hydraulic Braking System is introduced, which consists of active source power, pedal feel emulator and electro control unit. As a composite system of mechanic, electron and hydraulic pressure, the Integrated-Electro-Hydraulic Braking System has complex system characteristics. Integrated-Electro-Hydraulic Braking System and active power source have very different dynamic characteristics. So algorithms of hydraulic pressure control and motor control should be apart, but algorithm of them should be united in hardware to meet integration demand.
2016-09-14
Technical Paper
2016-01-1905
Gaoming Fang, Hui Chen
Abstract Electric Power Steering (EPS) is the actuator of several lateral-dynamic-related Advanced Driver Assistance Systems (ADAS). A driving simulator with EPS will be much helpful for the ADAS development. However, if a real EPS is used in the driving simulator, it is quite difficult to realize the road reaction force accurately and responsively. To overcome this weakness, a virtual EPS platform is established. The virtual EPS platform contains two parts: one is the vehicle and EPS model, the other is the force feedback actuator (FFA) of the Steer-by-Wire (SBW) system. The FFA is an interface between the driver and the EPS/vehicle model. The reactive torque of the FFA is obtained based on the models. Meanwhile, the input of the EPS model is the steering angle of the FFA. Comparing to a real EPS, the virtual EPS platform has a problem of instability because of the actuator lag of the FFA. Therefore, a damping control method is applied to make the system stable.
2016-09-14
WIP Standard
J75
Motor vehicle brake fluid must conform to the requirements of SAE J1703 or J1704, not only when manufactured, but also after extended storage in any commercial packaging container. The purpose of this SAE Information Report is to generate an awareness of the major problems involved in the storage of brake fluids and, to some extent, provide means of circumventing them. It is also the purpose of this document to relate to experience and to test data accumulated and to list certain conclusions which should aid in the proper selection of containers for brake fluid.
2016-09-14
Technical Paper
2016-01-1902
Xiaoyu Wang, Yun Zhao, Yufeng Lian, Yantao Tian
Abstract A new lateral stability control method, which is based on vehicle sideslip angle and tire cornering stiffness estimation, is proposed to improve the lateral stability of the four-in-wheel-motor-driven electric vehicle (FIWMD-EV) in this paper. Through the lateral tire force information, vehicle sideslip angle can be estimated by the extended kalman filter (EKF). Using the estimated vehicle sideslip angle, tire cornering stiffness can be also estimated by forgetting factor recursive least squares (FFRLS). Furthermore, combining with the vehicle dynamics model, an adaptive control target model is proposed with the information on vehicle sideslip angle and tire cornering stiffness. The new lateral stability control system uses the direct yaw moment control (DYC) based on dynamic sliding mode is proposed. The performance and effectiveness of the proposed vehicle state estimation and lateral stability control system are verified by CarSim and Simulink cosimulation.
2016-09-14
Journal Article
2016-01-1899
Tao Wang, Weiwen Deng, Ying Wang, Yuhao Chen, Keke zhang
Abstract Aimed to provide an effective solution for control-oriented applications, this paper proposes a novel method using a high-precision digital map to achieve high-accuracy positioning with fast updating rate. First, the map is developed using a high-definition LiDAR (Velodyne HDL 64E) and a RTK-GNSS system, which contains lane-level waypoints, road width, curb and typical obstacles along the road. Next, a robust version of ICP (Iterative Closest Point) is proposed to clean the corresponding points of large errors on map matching (MM). Finally, based on the large set of data from the environmental map, an unscented Kalman filter (UKF) is applied to fuse GNSS signal and dead reckoning (DR) to estimate the position. Thus the searching scope on the map can be considerably reduced so that the matching speed can be greatly improved. The high-precision digital map can be used not only for global path planning, but also for local driving detection and path planning.
CURRENT
2016-09-14
Standard
AS1145C
This specification covers minimum requirements for brake temperature monitoring equipment whenever used on any type and model of civil aircraft. It shall be the responsibility of the purchaser to determine the compatibility of these requirements with the application aircraft and to specify requirements in excess of these minimums as necessary.
2016-09-14
Technical Paper
2016-01-1872
Bin Wu, Xichan Zhu, Lin li
Abstract Based on the emergency lane change cases extracted from the China naturalistic driving data, the driving steering behavior divides into three phases: collision avoidance, lateral movement and steering stabilization. Using the steering primitive fitting by Gaussian function, the distribution of the duration time, the relationship between steering wheel rate and deflection were analyzed in three phases. It is shown that the steering behavior essentially is composed of steering primitives during the emergency lane-change. However, the combination of the steering primitives is different according to the specific steering constraints in three phases. In the collision avoidance phase, a single steering primitive with high peak is used for the fast steering; in the lateral movement and stabilization phase, a combination of two or even more steering primitives is built to a more accurate steering.
CURRENT
2016-09-13
Standard
J1707_201609
This SAE Recommended Practice provides basic recommendations for dispensing and handling of SAE J1703 and SAE J1704 Brake Fluids by Service Maintenance Personnel to assure their safe and effective performance when installed in or added to motor vehicle hydraulic brake actuating systems. This document is concerned only with brake fluid and those system parts in contact with it. It describes general maintenance procedures that constitute good practice and that should be employed to help assure a properly functioning brake system. Recommendations that promote safety are emphasized. Specific step-by-step service instructions for brake maintenance on individual makes or models are neither intended nor implied. For these, one should consult the vehicle manufacturer’s service brake maintenance procedures for the particular vehicle. Vehicle manufacturer’s recommendations should always be followed.
Viewing 91 to 120 of 10739

Filter