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Viewing 121 to 150 of 10938
2017-03-28
Journal Article
2017-01-1563
Abhijeet Behera, Murugan Sivalingam
Abstract Two and three wheeler vehicles are largely used in many developing and under developing countries because of their lower cost, better fuel economy and easy handling. Although, the construction of them is simpler than the four wheeler vehicle, they pose some problems related to instability. Wobbling is the main cause of instabilities in two wheeler and three wheeler vehicles. In this study, a mathematical model was proposed and developed to determine wobble instability of a two wheeler. Nonlinear equations were formulated by using kinematics and the D’Alembert’s principle with the help of multi body formalism. The non-linear equations found in the study were linearized with respect to rectilinear and upright motion, considering no rolling. It led to formation of matrix. The real part of the Eigen value of the matrix was found to be negative, implication of whose was an asymptotic stable motion.
2017-03-28
Journal Article
2017-01-1558
Jose Velazquez Alcantar, Francis Assadian, Ming Kuang
Abstract Hybrid Electric Vehicles (HEV) offer improved fuel efficiency compared to their conventional counterparts at the expense of adding complexity and at times, reduced total power. As a result, HEV generally lack the dynamic performance that customers enjoy. To address this issue, the paper presents a HEV with eAWD capabilities via the use of a torque vectoring electric rear axle drive (TVeRAD) unit to power the rear axle. The addition of TVeRAD to a front wheel drive HEV improves the total power output. To further improve the handling characteristics of the vehicle, the TVeRAD unit allows for wheel torque vectoring at the rear axle. A bond graph model of the proposed drivetrain model is developed and used in co-simulation with CarSim. The paper proposes a control system which utilizes tire force optimization to allocate control to each tire. The optimization algorithm is used to obtain optimal tire force targets to at each tire such that the targets avoid tire saturation.
2017-03-28
Journal Article
2017-01-1569
Amro Elhefnawy, Alhossein sharaf, Hossam Ragheb, Shawky Hegazy
Abstract This paper presents an advanced control system, which integrates three fuzzy logic controllers namely; Direct Yaw-moment Control (DYC), Active Roll-moment Control (ARC) and Active Front Steering (AFS) to enhance vehicle cornering and overturning stability. Based on a well-developed and validated fourteen degree of freedom (DOF) full vehicle model with non-linear tire characteristics, a reference 3-DOF yaw-roll plane vehicle model is introduced to control yaw rate, sideslip angle, and roll angle of the vehicle body. The control actions of both direct yaw and active roll moments are performed by generating differential braking moments across the front wheels, while the control action of the active steering is performed by modifying the steering wheel angle. Different standard cornering tests are conducted in MATLAB / Simulink environment such as J-turn, fishhook and lane change maneuvers.
2017-03-28
Journal Article
2017-01-1573
Andreas Carlitz, Sebastien Allibert, Thomas Schmitz, Axel Engels
Abstract A twistbeam is a very cost effective rear suspension architecture which has drawbacks compared to an independent rear suspension. One drawback is the lateral compliance during cornering compromising the handling of the vehicle. Common solutions to correct this issue are complex reinforcements or an additional Watts linkage. However, these solutions drive high cost and additional weight. The challenge was to find a solution which reduces the gap to the functional performance of a multilink rear suspension. Due to the bush attachment, the set-up of a twistbeam is always a compromise between ride comfort and vehicle dynamics. The more comfort is desired the softer the bushings will be, resulting in less agility and slower vehicle response. The target was to determine a way to separate ride comfort and dynamic agility. A solution was found using a special set of springs working as a dynamic anti-compliance mechanism.
2017-03-28
Journal Article
2017-01-1584
Peng Hang, Xinbo Chen, Fengmei Luo, Shude Fang
Abstract Compared with the traditional front-wheel- steering (FWS) vehicles, four-wheel-independent-steering (4WIS) vehicles have better handing stability and path-tracking performance. In view of this, a novel 4WIS electric vehicle (EV) with steer-by-wire (SBW) system is proposed in this paper. As to the 4WIS EV, a linear quadratic regulator (LQR) optimal controller is designed to make the vehicle track the target path based on the linear dynamic model. Taking the effect of uncertainties in vehicle parameters into consideration, a robust controller utilizing μ synthesis approach is designed and the controller order reduction is implemented based on Hankel-Norm approximation. In order to evaluate the performance of the designed controllers, numerical simulations of two maneuvers are carried out using the nonlinear vehicle model with 9 degrees of freedom (DOF) in MATLAB/Simulink.
2017-03-28
Journal Article
2017-01-1578
Tianyang Liu, Zhuoping Yu, Lu Xiong, Wei HAN
Abstract Two control strategies, safety preferred control and master cylinder oscillation control, were designed for anti-lock braking on a novel integrated-electro-hydraulic braking system (I-EHB) which has only four solenoid valves in its innovative hydraulic control unit (HCU) instead of eight in a traditional one. The main idea of safety preferred control is to reduce the hydraulic pressure provided by the motor in the master cylinder whenever a wheel tends to be locking even if some of the other wheels may need more braking torque. In contrast, regarding master cylinder oscillation control, a sinusoidal signal is given to the motor making the hydraulic pressure in the master cylinder oscillate in certain frequency and amplitude. Hardware-in-the-loop simulations were conducted to verify the effectiveness of the two control strategies mentioned above and to evaluate them.
2017-03-28
Technical Paper
2017-01-1560
Wei Liu, Lu Xiong, Bo Leng, Haolan Meng, Renxie Zhang
Abstract In this paper, a novel method is proposed to establish the vehicle yaw stability criterion based on the sideslip angle-yaw rate (β-r) phase plane method. First, nonlinear two degrees of freedom vehicle analysis model is established by adopting the Magic Formula of nonlinear tire model. Then, according to the model in the Matlab/Simulink environment, the β-r phase plane is gained. Emphatically, the effects of different driving conditions (front wheels steering angle, road adhesion coefficient and speed) on the stability boundaries of the phase plane are analyzed. Through a large number of simulation analysis, results show that there are two types of phase plane: curve stability region and diamond stability region, and the judgment method of the vehicle stability domain type under different driving conditions is solved.
2017-03-28
Technical Paper
2017-01-1537
Ananya Bhardwaj
Abstract Improving brake cooling has commanded substantial research in the automotive sector, as safety remains paramount in vehicles of which brakes are a crucial component. To prevent problems like brake fade and brake judder, heat dissipation should be maximized from the brakes to limit increasing temperatures. This research is a CFD investigation into the impact of existing wheel center designs on brake cooling through increased cross flow through the wheel. The new study brings together the complete wheel and disc geometries in a single CFD study and directly measures the effect on brake cooling, by implementing more accurately modeled boundary conditions like moving ground to replicate real conditions correctly. It also quantifies the improvement in the cooling rate of the brake disc with a change in wheel design, unlike previous studies.
2017-03-28
Technical Paper
2017-01-1408
Satoshi Kozai, Yoshihiko Takahashi, Akihiro Kida, Takayuki Hiromitsu, Shinji Kitaura, Sadamasa Sawada, Gladys Acervo, Marius Ichim
Abstract A Rear Cross Traffic Auto Brake (RCTAB) system has been developed that uses radar sensors to detect vehicles approaching from the right or left at the rear of the driver’s vehicle, and then performs braking control if the system judges that a collision may occur. This system predicts the intersecting course of approaching vehicles and uses the calculated time-to-collision (TTC) to control the timing of automatic braking with the aim of helping prevent unnecessary operation while ensuring system performance.
2017-03-28
Technical Paper
2017-01-1284
Khushal Ahmad, Monis Alam
Abstract With the ever increasing number of vehicles on road and the rise of the electric and automated vehicles, it is important to minimize the consumption of energy by each vehicle, regenerative braking is in wide use today, however, the research in the field of regenerative suspension is limited. The regenerative suspension has huge capabilities in power generation especially on third world roads having rather bumpy rides. A huge amounts of energy is wasted in shock absorbers due to friction. This study emphasizes on the implementation of the energy present in the suspension system by replacing the Shock Absorber with a Energy transfer system Involving Hydraulic cylinder, Hydraulic Motor and Dynamo. The energy which is usually lost as heat due to friction in conventional Suspension is used to drive a dynamo through Hydraulic System designed in this paper and electricity is generated.
2017-03-28
Technical Paper
2017-01-1176
Hafiz S. Khafagy
Abstract Auto stop-start (Engine stop-start, ESS) has become a widely used feature to reduce fuel consumption and CO2 emissions particularly in congested cities. Typically, vehicles equipped with such systems include two DC power sources that are coupled in parallel: a primary and a secondary power source. The primary power source supplies energy to the starter to crank the engine, while the secondary power source supplies energy to the rest of the vehicle electric loads. During an auto-stop event, a controllable switch decouples the two power sources. Moreover, operating current, voltage and the State of Charge (SOC) are monitored to ensure enough energy for the next auto-start event. When any of these operating parameters are below the threshold values, the controllable switch opens to isolate the two batteries and then the engine is automatically started.
2017-03-28
Journal Article
2017-01-0411
Yuming Yin, Subhash Rakheja, Jue Yang, P-E. Boileau
Abstract This study is aimed at characterizing the nonlinear stiffness and damping properties of a simple and low cost design of a hydro-pneumatic suspension (HPS) that permits entrapment of gas into the hydraulic fluid. The mixing of gas into the oil yields highly complex variations in the bulk modulus, density and viscosity of the hydraulic fluid, and the effective gas pressure, which are generally neglected. The pseudo-static and dynamic properties of the HPS strut were investigated experimentally and analytically. Laboratory tests were conducted to measure responses in terms of total force and fluid pressures within each chamber under harmonic excitations and nearly steady temperature. The measured data revealed gradual entrapment of gas in the hydraulic fluid until the mean pressure saturated at about 84% of the initial pressure, suggesting considerably reduced effective bulk modulus and density of the hydraulic fluid.
2017-03-28
Journal Article
2017-01-0418
Gregory McCann, Prashant Khapane
Abstract An increase in data measurement and recording within vehicles has allowed Anti-lock Braking Systems (ABS) to monitor a vehicle’s dynamic behavior in far more detail. This increased monitoring helps to improve vehicle response in scenarios such as braking whilst cornering and braking on uneven surfaces. The Durability and Robustness (D&R) CAE department within Jaguar Land Rover discovered that the lack of a complex ABS system in virtual vehicle models was contributing to poor lateral and longitudinal loads correlation throughout the suspension and mounting systems. D&R CAE started a project to incorporate Continental’s ABS system, provided by ‘©Continental AG’ for physical JLR vehicles, into SIMPACK virtual vehicles by means of a co-simulation (2017 n.d.). The work involved collaboration between 3 departments in Jaguar Land Rover and ultimately led to implementation of the ABS into the JLR standard automotive virtual database.
2017-03-28
Journal Article
2017-01-0404
Anatoliy Dubrovskiy, Sergei Aliukov, Sergei Dubrovskiy, Alexander Alyukov
Abstract Currently, a group of scientists consisting of six doctors of technical sciences, professors of South Ural State University (Chelyabinsk, Russia) has completed a cycle of scientific research for creation of adaptive suspensions of vehicles. We have developed design solutions of the suspensions. These solutions allow us to adjust the performance of the suspensions directly during movement of a vehicle, depending on road conditions - either in automatic mode or in manual mode. We have developed, researched, designed, manufactured, and tested experimentally the following main components of the adaptive suspensions of vehicles: 1) blocked adaptive dampers and 2) elastic elements with nonlinear characteristic and with improved performance.
2017-03-28
Journal Article
2017-01-0412
Mina M.S. Kaldas, Kemal Çalışkan, Roman Henze, Ferit Küçükay
Abstract Semi-active suspension offers variety of damping force range which demands greater need to optimize the top mount to ensure multiple objectives of ride comfort, harshness and safety can be achieved. For this purpose, this paper proposes a numerical optimization procedure for improving the harshness performance of the vehicle through the adjustment of the damper top mount characteristics of the semi-active suspension system. The proposed optimization process employs a frequency dependent combined objective function based on ride comfort and harshness evaluation. A detailed and accurate damper top mount mathematical model is implemented inside a validated full vehicle model to provide a realistic simulation environment for the optimization study. The semi-active suspension system employs a Rule-Optimized Fuzzy-Logic controller. The ride comfort and harshness of the full vehicle are evaluated by analyzing the body acceleration in different frequency ranges.
2017-03-28
Journal Article
2017-01-0421
Xiang Liu, Wei Chen, Ying Chen, Jing Zhao
Abstract The leaf spring has significant hysteresis characteristics due to the interleaf friction. The traditional three-link model could not simulate the hysteresis characteristics at all. According to the dynamic load test results one can find that the dynamic stiffness of leaf spring has a nonlinear relationship with the travel distance and the load frequency has a tiny influence on it. Based on the traditional three-link model, this paper proposed a simulation modeling method by introducing torsional friction on the revolute joints. The key parameters including torsional spring stiffness, friction torque preload, stiction transition velocity and max stiction deformation are optimized by combining the ADAMS and OPTIMUS. The comparison analysis between the simulation and test results of front and rear leaf springs have revealed that the maximum average errors are 4.84% and 6.41%, respectively.
2017-03-28
Journal Article
2017-01-0419
Yuliang Yang, Yu Yang, Ying Sun, Jian Zeng, Yunquan Zhang
Abstract In addition to ride comfort, handling stability and other conventional vehicle performances, we should also focus on other aspects of performance to a center axle trailer combination, such as the maximum stable side-inclination, the anti-rolling stability, the lateral stability and so on. Based on the finite element method, a rigid-flexible coupling model for the truck combination was built and analyzed in the multi-body environment (ADAMS), in which the key components of the chassis and cab suspension were treated as flexible bodies. A series of simulations were carried out to evaluate the lateral stability of the center axle trailer in accordance with the relevant regulations of the vehicle. The influence of design variables on the lateral stability was studied by an experiment. Furthermore, in order to improve the lateral stability of the trailer combination, the optimal design was obtained by the co-simulation of the ADAMS/Car, iSIGHT and Matlab.
2017-03-28
Journal Article
2017-01-0437
Bin Li, Subhash Rakheja
Abstract In this paper, a gain-scheduling optimal control approach is proposed to enhance yaw stability of articulated commercial vehicles through active braking of the proper wheel(s). For this purpose, an optimal feedback control is used to design a family of yaw moment controllers considering a broad range of vehicle velocities. The yaw moment controller is designed such that the instantaneous tractor yaw rate and articulation angle responses are forced to track the target values at each specific vehicle velocity. A gain scheduling mechanism is subsequently constructed via interpolations among the controllers. Furthermore, yaw moments derived from the proposed controller are realized by braking torque distribution among the appropriate wheels. The effectiveness of the proposed yaw stability control scheme is evaluated through software-in-the-loop (SIL) co-simulations involving Matlab/Simulink and TruckSim under lane change maneuvers.
2017-03-28
Journal Article
2017-01-1554
Ajith Jogi, Sujatha Chandramohan
Abstract Over the years, commercial vehicles, especially tractor-semitrailer combinations have become larger and longer. With the increasing demand for their accessibility in remote locations, these vehicles face the problem of off-tracking, which is the ensuing difference in path radii between the front and rear axles of a vehicle as it maneuvers a turn. Apart from steering the rear axle of the semitrailer, one of the feasible ways of mitigating off-tracking is to shift the fifth wheel coupling rearwards. However, this is limited by the distribution of the semitrailer’s load between the two axles of the tractor; any rearward shift of the fifth wheel coupling results in the reduction of the total static load on the tractor’s front axle and hence available traction. This may in turn lead to directional instability of the vehicle. In the present work, a new model of the fifth wheel coupling is proposed which the authors call Split fifth wheel coupling (SFWC).
2017-03-28
Journal Article
2017-01-1507
Prashanta Gautam, Yousof Azizi, Abhilash Chandy
Abstract Tire noise is caused due to the complex interactions between the rotating tire and the road surface at the tire/road interface. It is usually caused due to a combination of individual noise generation mechanisms, which can either be structural or air-borne. The influence of each of these noise generation mechanism may vary, depending on various conditions such as tire design, road surface and operating conditions. Due to the many variables that affect the noise generation mechanisms in tires, it is usually a very complex task to isolate and categorize those that are present in the overall tire/road noise spectrum. Various approaches are used to categorize noise generation mechanisms in tires. In this paper, a statistical model based on the assumption that the tire noise acoustic pressure at a specific frequency band is related to the vehicle speed, is used, in order to study tire noise at different speeds.
2017-03-28
Journal Article
2017-01-1111
Marcello Canova, Cristian Rostiti, Luca D'Avico, Stephanie Stockar, Gang Chen, Michael Prucka, Hussein Dourra
Abstract To improve torque management algorithms for drivability, the powertrain controller must be able to compensate for the nonlinear dynamics of the driveline. In particular, the presence of backlash in the transmission and drive shafts excites sharp torque fluctuations during tip-in or tip-out transients, leading to a deterioration of the vehicle drivability and NVH. This paper proposes a model-based estimator that predicts the wheel torque in an automotive drivetrain, accounting for the effects of backlash and drive shaft flexibility. The starting point of this work is a control-oriented model of the transmission and vehicle drivetrain dynamics that predicts the wheel torque during tip-in and tip-out transients at fixed gear. The estimator is based upon a switching structure that combines a Kalman Filter and an open-loop prediction based on the developed model.
2017-03-28
Technical Paper
2017-01-1058
L.V. Pavan Kumar Maddula, Ibrahim Awara
Abstract Increased focus on fuel efficiency and vehicle emissions has led the automotive industry to look into low weight alternative designs for powertrain system components. These new design changes pose challenges to vehicle attributes like NVH, durability, etc. Further, the requirement of high power applications produces even more complexities. The present work explains how a potential design change of half shafts driven by a desire to reduce weight and cost can lead to NVH problems caused by half shaft resonances and explains how using multiple dynamic vibration absorbers can solve the issue to meet customer expectation while improving efficiency. With the aid of Finite Element Analysis (FEA) & optimization software, interactions between multiple DVA’s on a system was understood and optimal damper parameters for effective damping was identified. The final DVA design was tested and verified on the vehicle for optimal attribute performance.
2017-03-28
Journal Article
2017-01-1489
Duanxiang Zhang, Bo Lin, Ahmet Kirli, Chinedum Okwudire
Abstract Electric Power Assisted Steering (EPAS) is widely adopted in modern vehicles to reduce steering effort. It is probable that some EPAS systems will experience a shutdown due to reliability issues stemming from electrical and/or electronic components. In the event of EPAS failure, power assist becomes unavailable and the steering system reverts to a fully manual state, leading to excessive steering torque demands from the driver to maneuver the vehicle at lower speeds, i.e., under 30 mph. This situation has resulted in dozens of reported crashes and several OEM safety recalls in the past few years. Inspired by recent work which utilizes independent driving torque of in-wheel-motor vehicles to reduce steering torque, this paper proposes the use of Differential Braking Assisted Steering (DBAS) to alleviate steep increases in steering torque upon EPAS failure. DBAS requires software upgrades with minimal hardware modification to EPAS, which is preferable for a backup system.
2017-03-28
Journal Article
2017-01-1519
Arturo Guzman, Young-Chang Cho, John Tripp, Kumar Srinivasan
Abstract Pickup trucks are designed with a taller ride height and a larger tire envelope compared to other vehicle types given the duty cycle and environment they operate in. These differences play an important role in the flow field around spinning wheels and tires and their interactions with the vehicle body. From an aerodynamics perspective, understanding and managing this flow field are critical for drag reduction, wheel design, and brake cooling. Furthermore, the validation of numerical simulation methodology is essential for a systematic approach to aerodynamically efficient wheel design as a standard practice of vehicle design. This paper presents a correlation the near-wheel flow field for both front and rear spinning wheels with two different wheel designs for a Ram Quad Cab pick-up truck with moving ground. Twelve-hole probe experimental data obtained in a wind tunnel with a full width belt system are compared to the predictions of numerical simulations.
2017-03-28
Technical Paper
2017-01-0401
Ye Yuan, Junzhi Zhang, Yutong Li, Chen Lv
Abstract As the essential of future driver assistance system, brake-by-wire system is capable of performing autonomous intervention to enhance vehicle safety significantly. Regenerative braking is the most effective technology of improving energy consumption of electrified vehicle. A novel brake-by-wire system scheme with integrated functions of active braking and regenerative braking, is proposed in this paper. Four pressure-difference-limit valves are added to conventional four-channel brake structure to fulfill more precise pressure modulation. Four independent isolating valves are adopted to cut off connections between brake pedal and wheel cylinders. Two stroke simulators are equipped to imitate conventional brake pedal feel. The operation principles of newly developed system are analyzed minutely according to different working modes. High fidelity models of subsystems are built in commercial software MATLAB and AMESim respectively.
2017-03-22
Article
Replacing the decade-old Jeep Compass is the new-for-2017 Jeep Compass, FCA’s (and Jeep’s) first truly global vehicle program. Styled to resemble a slightly scaled-down Grand Cherokee, the new C-segment SUV is being produced in four plants (Mexico, China, India and Brazil) and offered in 17 powertrain combinations including diesels and 6-speed manual gearboxes.
CURRENT
2017-03-21
Standard
AS5714
This SAE Aerospace Standard (AS) prescribes the Minimum Performance Standards (MPS) for wheel, brake, and wheel and brake assemblies to be used on aircraft certificated under 14 CFR Parts 23, 27, and 29. Compliance with this specification is not considered approval for installation on any aircraft.
2017-03-13
Article
Startup-company Twin Spring Coupling features its new power transfer coupling that is warrantied to 300 lb·ft (407 N·m) of torque.
CURRENT
2017-03-13
Standard
J2995_201703
This recommended practice will specify a standard duty cycle and set of conditions for component-level durability testing. The "duty cycle" refers to a set of loading conditions (e.g. torque or pressure and cycling count), and the 'test conditions" refers to environmental conditions such as temperature, humidity, and part conditioning from prior exposure (e.g. heat aging).
CURRENT
2017-02-13
Standard
J2611_201702
This SAE information report covers the basic guidelines concerning off-road tire conditions that warrant replacement, removal, or repair. This material can assist the tire user in establishing specific written procedures for each job site.
Viewing 121 to 150 of 10938

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