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Viewing 91 to 120 of 10186
2015-04-14
Journal Article
2015-01-1506
Bastian Scheurich, Tilo Koch, Michael Frey, Frank Gauterin
Today, body vibration energy of passenger cars gets dissipated by linear working shock absorbers. A new approach substitutes the damper of a passenger car by a cardanic gimbaled flywheel mass. The constructive design leads to a rotary damper in which the vertical movement of the wheel carrier leads to revolution of the rotational axis of the flywheel. In this arrangement, the occurring precession moments are used to control damping moments and to store vibration energy. A gyroscope is set to high speed revolutions by an electric motor and a gimbal is used for bearing. The gimbal consists of an outer ring which is connected to the vertical movement of the wheel carrier. Right-angled to the outer ring, there is an inner ring pivoting the gyroscope right-angled. In order to avoid undesirable body movements, the directional vector of the angular velocity of the gyroscope is parallel to the car’s yaw axis.
2015-04-14
Journal Article
2015-01-1507
Kentaro Komori, Takahito Nagataki
Research on passenger vehicles responds to mechanical loss-reduction demands for improving fuel economy. Handling, steering feel, and ride-comfort can be attributed to the steering and suspension. We researched friction behavior in terms of low- or high- friction coefficients, and in terms of static-kinetic transient motion. We improved the vehicle handling and ride comfort by giving the appropriate friction to the tie-rod end ball joint. Controlling friction behavior, we used diamond-like carbon (DLC) coating submitted to boundary lubrication. Different DLC coatings varied widely in hydrogen content, mechanical properties and micro-surface roughness were applied to the ball joint studs. The larger the micro-surface roughness in asperity of DLC coatings, the higher the kinetic friction torque. The friction behaviors corresponded to the DLC properties.
2015-04-14
Technical Paper
2015-01-1508
Lijiao Yu, Hongyu Zheng
As the electric technique develops fast, steering systems change from conventional mechanic steering systems to electrically controlled steering (ECS) systems, including electric power (EPS) system, active front steering (AFS) system and steer-by-wire (SBW) system. ECS could improve vehicles’ steering portability at a low speed and handing stability at a high speed. The study of ECS involves mechanic design, detection of electric components, software design and so on, which need a lot of trials and errors. By now, the development of ECS mostly depends on experiments on hard-ware-in-the-loop (HIL) and real vehicles. Because tests on real vehicles have many short cuts, such as a higher cost, a longer period, etc. HIL is gradually taking the place of real vehicles to carry out kinds of experiments in order to reduce test times, cycles and cost, which has been a main means to research and develop ECS.
2015-04-14
Journal Article
2015-01-1556
Mark E. Gleason, Bradley Duncan, Joel Walter, Arturo Guzman, Young-Chang Cho
Comparison of Analytical Prediction of Automotive Spinning Wheel Flowfield with Full Width Moving Belt Wind Tunnel Results Abstract One of the remaining challenges in the simulation of the aerodynamics of ground vehicles is the modeling of the airflows around the spinning tires and wheels of the vehicle. As in most advances in the development of simulation capabilities, it is the lack of appropriately detailed and accurate experimental data that holds back the advance of the technology. The flow around the wheels and tires and their interfaces with the vehicle body and the ground is a critical area for the development of automobiles and trucks, not just for aerodynamic forces and moments, and their result on fuel economy and vehicle handling and performance, but also for the airflows and pressures that affect brake cooling, engine cooling airflows, water spray management etc.
2015-04-14
Journal Article
2015-01-1554
Bastian Schnepf, Thomas Schütz, Thomas Indinger
Efforts in aerodynamic optimization of road vehicles have been steadily increasing in recent years, mainly focusing on the reduction of aerodynamic drag. This has been motivated by the need of reducing CO2 emissions as well as extending the range of electric vehicle concepts. Both targets can only be achieved when all driving resistances are minimized. At velocities higher than 70 kph aerodynamic drag, which increases with the square of velocity, even becomes the dominant force. Breaking a passenger car’s aerodynamic drag down into the contributions of certain areas, wheels and wheel houses account for approx. 25 percent [1], a large share compared to their geometric dimensions. Consequently, industry and academia have been investigating the flow around automotive wheels intensively at an increasing level of detail lately.
2015-04-14
Technical Paper
2015-01-0613
Donghong Ning, James Coyte, Hai Huang, Haiping Du, Weihua Li
Heavy duty vehicles suffer from detrimental vibrations which have significant influence to the operator’s comfort, health and safety. Especially, long term exposures to vibration with a frequency range between 0.5 and 10Hz will severely damage the driver’s backbone. Tires, chassis suspension and seat suspension are three traditional methods to isolate vehicles vibration, but it is generally difficult to modify the parameters of tires and chassis suspension, even many approaches are proposed for the performance of chassis suspension. On the other hand, the seat suspension system is easy to modify and optimize. Therefore, seat suspension has been employed as a simple and effective method to isolate vehicle vibration transmitted to the driver’s body. Studying the vibration characteristics of seat suspension is one important step for seat suspension design.
2015-04-14
Technical Paper
2015-01-1096
Robert Lloyd
Abstract The frequent occurrence of stops and starts on the typical postal delivery route makes it an attractive application for regenerative braking. The transmission described in SAE paper 2014-01-1717 contains all the functions necessary to implement hydraulic regenerative braking including the accumulator and reservoir. This paper describes the substitution of the hydro-mechanical transmission for the present transmission and estimates the performance benefits. The result in a low impact path for the US Postal Service to conform to the congressional mandate to improve the mpg of the vehicles and extend their useful life.
2015-04-14
Technical Paper
2015-01-1203
Subhashree Rajagopal, Sebastien Desharnais, Balamurugan Rathinam, Upendra Naithani
Eddy-current brakes are contactless magnetic brakes that allow decelerating a vehicle without friction and wear. Electromagnetic brakes are found in variety of applications. However they suffer from a decreasing torque at low and high speed. In this study a novel concept of permanent magnet eddy-current brake is proposed that maintains a flat braking torque profile over a broad speed range. The principle is analytically investigated and numerically validated through finite element simulations using MAXWELL. It is demonstrated that a useably flat braking torque profile can be achieved by altering the path of eddy-currents by magnetic field orientation, thereby, affecting the apparent rotor resistance. Keywords: Eddy-currents, eddy-current brakes, electromagnetic brakes, permanent magnet brakes, MAXWELL
2015-04-14
Technical Paper
2015-01-1210
Bharat Singh, Naveen Kumar, Amaya Kak, Satya Kaul
In the present, vast numbers of problems are triggered due to growing global energy crisis and rising energy costs. Since, on-road vehicles constitute the majority share of transportation; any energy losses in them will have a direct effect on the overall global energy scenario. Most of the energy lost is dissipated from the exhaust, cooling, and lubrication systems, and, most importantly, in the braking system. About 6% of the total energy produced is lost with the airstream in form of heat energy when brakes are applied. Thus, various technological systems need to be developed to conserve energy by minimize energy losses while application of brakes. Regenerative Braking is one such system or an energy recovery mechanism causing the vehicle to decelerate by converting its kinetic energy into another form (usually electricity), which further can be used either immediately or stored until needed.
2015-04-14
Technical Paper
2015-01-1211
Zhuoping Yu, Caitao Jian, Songyun Xu, Lu Xiong
This paper is to research the dynamic response of active power source (APS) of electro hydraulic brake (EHB) system, which is a new design system. The dynamic response of APS could impact the effectiveness of brake system, the reason is that the slow-response of APS will cause the slow speed of building pressure and increasing the braking distance. So researching the dynamic response of active power source is very important for brake system. First of all, the part is about the components and working principle of EHB system and some parameters of active power source. EHB systemconsists of active power source (APS), pedal feel emulator (PFE), electro control unit (ECU) and hydraulic control unit (HCU). APS includes motor, master cylinder and retarding mechanism consisting of warm, gear and gear rack. Secondly, this paper proposes a restricted distribution control strategy——the control strategy of restricted distribution (CSRD).
2015-04-14
Journal Article
2015-01-1309
Hyunggyung Kim
This paper describes about the development of new concept’s rear wheel guards for the reduction of Road Noise in the passenger vehicle using test. The new wheel guards are proposed by various frequency chamber concept and different textile layers concept. Two wheel guards were verified by small cabin resonance test and vehicle test. Through new developing process without vehicle test, Result of road noise will be expected when new concepts and materials of wheel guard is applied into automotive vehicle. As this concept consider tire radiation noise frequency and multilayers sound control multilayers, 2 concepts reduced road noise from 0.5 to 1.0 dB The suggested Estimation method of part reverberant absorption method is similar to result of vehicle tests by part absorption index. Furthermore, optimization of frequency band to wheel guards will reduce more 0.5 dB noises in vehicle.
2015-04-14
Journal Article
2015-01-1517
David Stalnaker, Ke-Jun Xie, Terence Wei
Tire manufacturers need to perform various types of testing to determine tire performance under representative vehicle load conditions. However, test results are influenced by a number of external variables other than tire construction. Vehicle load distribution and suspension properties are some of those external variables which can have a significant effect on tire wear rate and durability. Therefore, in order to measure tire performance in a controlled and repeatable manner, a representative vehicle and associated tire load conditions are needed. Laboratory or indoor tire testing offers many advantages over vehicle fleet testing. It provides a well-defined test environment and repeatable results without influence from external factors. Indoor testing has been largely developed around the process of simulating tire wear performance on a specific reference vehicle, including its specific weight distribution, suspension characteristics, and alignment.
2015-04-14
Technical Paper
2015-01-1516
Mohammed K Billal, Rizwan Basha, Anilkumar Nesarikar, Abdul Haiyum, Thomas Oery
Damages (fracture) in metals are caused by material degradation due to crack initiation and growth due to fatigue or dynamic loadings. The accurate and realistic modeling of an inelastic behavior of metals is essential for the solution of various problems occurring in engineering fields. Currently, various theories and failure models are available to predict the damage initiation and the growth in metals. In this paper, the failure of aluminum alloy is studied using progressive damage and failure material model using Abaqus explicit solver. This material model has the capability to predict the damage initiation due to the ductile and shear failure. After damage initiation, the material stiffness is degraded progressively according to the specified damage evolution response. The progressive damage models allow a smooth degradation of the material stiffness, in both quasi-static and dynamic situations.
2015-04-14
Technical Paper
2015-01-1515
Kwangwon Kim, Hyeonu Heo, Md Salah Uddin, Jaehyung Ju, Doo-Man Kim
Due to the relatively high freedom of selection of materials associated with a simple manufacturing method, a nonpneumatic tire (NPT) can be manufactured with a low viscoelastic energy loss material. A highly increasing demand to reduce greenhouse gases drives engineers to explore NPTs. NPTs consisting of flexible spokes and the shear band are still at an early stage of research and development. An optimization study of geometry of NPTs needs to be conducted, which is the objective of this paper. Parametric studies, design of experiments (DOE), and sensitivity analyses are conducted with a hyper-viscoelastic finite element (FE) model to determine the effects of three design variables on rolling resistance; the thickness of cellular spokes, the cell angle, and the shear band thickness.
2015-04-14
Technical Paper
2015-01-1513
Anudeep K. Bhoopalam, Kevin Kefauver
Indoor laboratory tire testing on flat belt machines and tire testing on the actual road yield different results. Testing on the machine offers the advantage of repeatability of test conditions, control of the environmental condition, and performance evaluation at extreme conditions. However, certain aspects of the road cannot be reproduced in the laboratory. It is thus essential to understand the connection between the machine and the road, as tires spend all their life on the road. This research, investigates the reasons for differences in tire performance on the test machine and the road. The first part of the paper presents a review on the differences between tire testing in the lab and on the road, and existing methods to account for differences in test surfaces.
2015-04-14
Technical Paper
2015-01-1514
Deepak Tiwari, Japveer Arora, Rakesh Khanger
A typical wheel development process involves designing a wheel based on a defined set of criteria and parameters followed by verification on CAE. The virtual testing is followed by bench level and vehicle level testing post which the design is finalized for the wheel. This paper aims to establish the learnings which were accomplished for one such development processes. The entire wheel development process had to be analyzed from scratch to arrive at a countermeasure for the problem. This paper will not only establish the detailed analysis employed to determine the countermeasure but also highlight its significance for the future development proposals. The paper first establishes the failure which is followed by the detailed analysis to determine the type of failure, impact levels and the basic underlying conditions. This leads to a systematic approach of verification which encompasses the manufacturing process as well as the test methodology.
2015-04-14
Technical Paper
2015-01-1512
Sairom Yoo, Md Salah Uddin, Hyeonu Heo, Jaehyung Ju, Doo Man Kim, Seok-Ju Choi
In an effort to develop tires with low rolling resistance, nonpneumatic tires (NPTs) with low viscoelastic energy loss materials are receiving more attention. For better design of NPTs for better fuel efficiency, one may need to analyze rolling energy loss of NPTs at a component level. The objective of this study is to develop a tool to quantify rolling energy loss and thermal dissipation of NPTs at a component level. For varying vehicle loads and rolling speeds, we suggest a thermo-mechanical model of an NPT with hexagonal cellular spokes to investigate temperature distribution of the NPT caused by hysteresis and convection loss into air. Using a hyper-viscoelastic model developed from a uniaxial (tensile and compression) testing and dynamic mechanical analysis (DMA), a thermo-mechanical model is developed by combining longitudinal shear deformation induced hysteresis and cooling to air.
2015-04-14
Journal Article
2015-01-1511
Srikanth Sivaramakrishnan, Kanwar Bharat Singh, Peter Lee
Anti-lock Braking System (ABS) is a critical safety component and its performance is crucial for every vehicle manufacturer. The tire plays an important role during an ABS braking maneuver as it is the component that connects the vehicle to the ground and is responsible for generating braking force. The steady-state and transient properties of the tire affect the operation of the vehicle’s ABS system. The main objective of this study is to investigate how tire design changes influence its interaction with the ABS and its eventual effect on stopping distance. This was conducted through an experimental study where tires were built with three levels of variation in carcass stiffness, tread stiffness and tread compound. Following this, ABS braking maneuvers were performed on instrumented vehicles with regular ABS and high-performance ABS using these tires on all four wheels.
2015-04-14
Technical Paper
2015-01-1510
Edoardo Sabbioni, Davide Ivone, Francesco Braghin, Federico Cheli
Estimation of friction coefficient and sideslip angle represents a key-point for improving control systems for vehicle safety, e.g. ESP (Electronic Stability Control), VDC (Vehicle Dynamics Control), etc. A model-based approach (state observer or Kalman filter) is generally used on purpose. Benefits induced by in-tyre sensors on sideslip angle and friction coefficient estimation are investigated in this paper. Thus tyre cornering force measurements are added to the ones usually present on-board vehicle (steer angle, lateral acceleration and yaw rate) and used to implement an Extended Kalman Filter (EKF) based on a single-track vehicle model. Tyre-road contact forces are assumed to be provided once per wheel turn by a smart tyre constituted of two tri-axial accelerometers glued on the tyre inner liner. Performance of the proposed observer is evaluated on a series of handling maneuvers and its robustness to road bank angle and tyre/vehicle parameters variation is discussed.
2015-04-14
Technical Paper
2015-01-1518
Emmanuel O. Bolarinwa, Oluremi Olatunbosun
Three-dimensional (3D) Finite element (FE) tyre models have been widely used for tyre design, vehicle design and dynamic investigations. Such tyre models have the inherent advantage of covering a wide range of tyre modelling issues such as the detailed tyre geometry and material composition, in addition to an extensive coverage of tyre operational conditions such as the static preload, inflation pressure and driving speed. Although tyre vibration behaviour, in different frequency ranges are of general interest, both for the vehicle interior and exterior noise, the present study is limited to a frequency of 100 Hz which is prevalent in most road induced NVH ride and handling problems. This study investigates tyre vibration behaviour using a propriety FE code. Such investigation plays an important role in the study of vehicle dynamics.
2015-04-14
Journal Article
2015-01-1521
Kanwar Bharat Singh, Srikanth Sivaramakrishnan
Tread depth, inflation pressure, tire temperature, and road surface condition are among the most notable factors that have a noticeable effect on the tire force and moment characteristics. They can vary significantly during the operation of a tire and can effectively modify tire (and thus vehicle) performance. This study presents details of an adaptive magic formula (MF) tire model capable of coping with changes to the tire operating condition. More specifically, extensions have been made to the magic formula expressions for tire cornering stiffness and peak grip level, to account for variations in the tire inflation pressure, load, tread-depth and temperature. As a next step, the benefits of using an adaptive tire model for vehicle control system applications is demonstrated through simulation studies for enhanced vehicle control systems using an adaptive tire model in comparison to traditional control systems based on a non-adaptive tire model with fixed model parameters.
2015-04-14
Journal Article
2015-01-1520
Massimiliano Gobbi, Giampiero Mastinu, Federico Ballo, Giorgio Previati
A wheel able to measure the generalized forces at the hub of a race motorcycle has been developed and used. The wheel has a very limited weight (about 2 kg). It is made from magnesium with a special structure to sense the forces and provide the required level of stiffness. The wheel has been tested both indoor for preliminary approval according to internal standards and on the track. The three forces and the three moments at the hub can be measured with a resolution of respectively 1N and 0.3Nm. Twelve strain gauges are positioned at relevant locations to sense the generalized forces. Utilizing an encoder (angle resolution 0.06°), a simultaneous ADC sampling is performed on the six strain gauges bridges outputs while coupling the force/torque output with the absolute wheel angular position. The sincronous sampling allows seamless real-time measurements at vehicle speed up to 400 km/h.
2015-04-14
Journal Article
2015-01-1523
Takahiro Uesaka, Tatsuya Suma
Simulating road noise while a vehicle is operating shortens the development period and reduces the number of prototypes, which lowers development costs. Realizing road noise simulation identifies the force transmitted to the suspension through the tires and wheels from vibration between the road surface and the tires. There are significant variations between static state characteristics and vibration characteristics of tires in motion, which are challenging to measure. The effects of reduction of the elastic modulus of the rubber in the tires due to repeated loads accompanying contact with the ground, and of Coriolis and centrifugal forces resulting from the rolling motion are known. Detailed analysis of the eigenvalue fluctuations produced by Coriolis force based on measurements taken using sensors installed inside the tires has recently been reported. Knowledge is still lacking in areas such as the specifics of how the input from the tires changes due to these fluctuations.
2015-04-14
Technical Paper
2015-01-1522
Takahiro Yokoyama, Koji Hiratsuka, Shinya Notomi
Users drive at relatively high speeds during the winter season, and maneuvering on snow-covered roads is a key performance for drivers. Demands are increasing for tires with lower rolling resistance. Tire patterns were developed similar to summer tires with reduced grooving and tire patterns with shallower grooves. This required techniques that predict maneuverability on snow-covered roads. This study treated maneuverability on snow-covered roads as maneuverability in the grip region, and verified the correlation between subjective evaluation using vehicles and tire stand-alone characteristics. Indexes were clarified for the tire contact patch and the physical properties of the tread rubber, which are prerequisites for securing grip in the normal-use. Typical index values for indexes were investigated using the surface pressure distribution obtained by a tire contact and surface pressure measuring system.
2015-04-14
Technical Paper
2015-01-1524
Ping Chen, Nan Xu, Konghui Guo, Rongsheng Liu
Tire lateral force is essential to vehicle handling and stability under cornering. However, it is difficult for engineers to get tire lateral force under high loading condition due to the loading ability limitation of most tire test machine in the world. Widely used semi-empirical tire lateral force models are obtained by curve-fitting experiments data and don’t possess load prediction ability. The objective of this paper is to predict the tire lateral force model under high-load condition based on low-load tire data. The nonlinear characteristic of tire cornering stiffness vary with load is greatly affected by tire carcass compliance. In this paper, a theoretical tire lateral model was built by considering carcass complex deformation. Combined with the relationship between half-length of tire contact patch and load, the non-linear characteristic of tire cornering stiffness vary with load was obtained.
2015-04-14
Technical Paper
2015-01-0614
Ye Zhao, Liangmo Wang, Xiangli Yang, Liukai Yuan, Zunzhi Zhang
Abstract: In most cases, researches on the ride performance of air suspension system are based on simplified mathematical models which could be too theoretical or not be able to consider the coupling relationship between the various components so that they behave far away from the actual vehicle system. This paper represents the study on the ride performance of an air suspension vehicle based on the complex whole vehicle model which was established though ADAMS and Matlab. The applying of flexible components helped to improve the model accuracy and the tensile and compression tests of the air spring were used to establish the interconnected four-gasbag air suspension system. The vehicle ride performance was studied through the co-simulation between ADAMS and Matlab. The accuracy of the results were verified by the vehicle test results, which demonstrated the reliability of the whole model.
2015-04-14
Technical Paper
2015-01-0642
Per Hyldahl, Sebastian Andersen, Sebastian Mikkelsen, Ole Balling
The modeling of a vehicle’s suspension system is one of the most crucial tasks when designing and optimizing modern vehicles. One of the preferred tools to assist the designers to perform this task is multibody dynamics. When using multibody dynamics, it is possible to model arbitrary systems with high mechanical complexity, include non-linear characteristics of e.g. springs and dampers, and simulate the systems behavior in the time domain to assess its performance in various scenarios. A non-trivial job when building a vehicle model, is estimating the characteristics of the many suspension components that exhibits non-linear behavior during operation of the vehicle. Examples of such components are rubber bushings and stabilizer bars. Especially the latter can be difficult to characterize using an idealized spring with a non-linear force-deflection curve, since its stiffness depends highly on its geometry and deformation stage.
2015-04-14
Technical Paper
2015-01-0617
Jie Zhang, Xiao Chen, Bangji Zhang, Lifu Wang, Shengzhao Chen, Nong Zhang
Well-deigned suspension system plays an important role in improving ride comfort. Underground mining vehicles which work in harsh conditions commonly employ leaf spring suspension to provide large stiffness and damping while be compact in size. Another characteristic of the mining vehicle is that its sprung mass varies significantly when loaded/unloaded. The leaf spring suspension has to be designed very stiff to meet the full-loaded requirement, therefore when the vehicle is unloaded, the stiff leaf spring damage the ride quality and expose the passengers to noise, vibration and harshness. Since the hydraulic suspension systems can provide better ride comfort, the paper proposes a design of adding an interconnected hydraulic system to resist bounce motions to share the vertical load with the leaf spring, which therefore can be designed softer. Furthermore, The hydraulic system also increases the suspension stiffness in the pitch mode to prevent vehicle from large pitch motions.
2015-04-14
Technical Paper
2015-01-1612
Wei Liu, Gangfeng Tan, Jiafan Li, Xin Li, Fuzhao Mou, Yongqiang Ge
The hydraulic retarder is a significant auxiliary braking device for the heavy duty vehicle. Traditionally, cooling circulation of the hydraulic retarder was coupled with the engine cooling system, and the thermal energy of the transmission oil would be cooled by the engine radiator ultimately. For this scheme, radiator’s spare heat removal capacity could be fully utilized whereas the cooling system is very complicated and is hard to maintain. Furthermore, the corresponding of thermal management system lags behind the power change of the retarder. In this research, integrated cooling evaporation system is developed for the hydraulic retarder, which makes the cooling water contact with the transmission oil through the wall of the fixed wheel so that it can rapidly response to the thermal variation of the retarder, keep the stability of the oil temperature and meanwhile reduce the risk of cooling medium leakage.
2015-04-14
Journal Article
2015-01-1225
Chen Lv, Junzhi Zhang, Yutong Li, Ye Yuan
Regenerative braking provided by an electric powertrain is far different from conventional friction braking with respect to the system dynamics. During regenerative decelerations, the nonlinear powertrain backlash would excite driveline oscillations, deteriorating vehicle drivability and blended brake performance. Therefore, backlash compensation in advanced powertrain control is worthwhile researching for electrified vehicles during regenerative deceleration. In this study, a nonlinear powertrain of an electric passenger car equipped with a central motor is modeled using a hybrid system approach. The effect of powertrain backlash gap on vehicle drivability during regenerative deceleration is analyzed. To further improve an electric vehicle’s drivability and blended braking performance, active control algorithm with a hierarchical architecture is studied for powertrain backlash compensation.
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