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Viewing 1 to 30 of 7609
2015-04-14
Technical Paper
2015-01-1373
Yulong Lei, Hui Tang, Xingjun Hu, Ge Lin, Bin Song
With the continuous improvement of the road condition, commercial vehicles get to be faster and more overloaded than before, which puts higher pressure on the vehicle braking system. Conventional friction braking has been difficult to meet the needs of high-power commercial vehicle. The auxiliary brake equipment will become the future trend for commercial vehicle. Hydraulic retarder is superior secondary braking equipment. Previously hydraulic retarder research mainly focus on flow field analysis, the braking torque calculation, cascade system optimization and control methods for hydraulic retarder. The gas-liquid two-phase flow in working chamber is less researched. Based on this, this article discusses on the hydraulic retarder from two aspects, including CFD numerical modeling method, transient characteristics of oil-filling , which provides support for hydraulic retarder design and matching in the vehicle. The main contents and conclusions are as follows: 1.
2015-04-14
Technical Paper
2015-01-0608
Gang Tang, Hengjia Zhu, Yunqing Zhang, Ying Sun
The vehicle ride comfort behavior is closely associated with the vibration isolation system such as the primary suspension system, the engine mounting system, the cab suspension system and the seat suspension system. Air spring is widely used in the cab suspension system for its low vibration transmissibility, variable spring rate and inexpensive automatic leveling. The mathematical model of the pneumatic system including the air spring, the leveling valve and the pipe is presented. The frequency dependency of the air spring’s stiffness characteristic is highlighted. The air spring dynamic model is validated by comparing the results of the experiments and the simulation. The co-simulation method using ADAMS and AMESim is applied to integrate the pneumatic system into the cab multi-body dynamic model. The simulation and ride comfort test results under random excitation are compared.
2015-04-14
Technical Paper
2015-01-0216
Ping-Min Hsu, Ming Hung Li, Kuo-Ching Chang
This paper studies noise filtering in an autonomous emergency braking (AEB) system with a sensor fusion between a millimeter wave (MMW) radar and a camera. The AEB system may automatically brake cars by mistake due to the sudden appearance of noise signal if it does not involve any noise filtering mechanism for the object sensor. This may cause some accidents. To avoid such accidents, we propose the filters for three kinds of noise—named as twice harmonic noise, ground noise, and specular refection noise—which are commonly suffered while applying MMW radars. The former is caused by the reflection of a radar wave between a target object and the MMW radar. Based on the concern that the MMW radar evaluates the sensing distance based on the time interval between the transmitting and receiving of the radar wave, one of the sensing distances would be twice as longer as one of others due to the wave reflection. The object featuring this characteristic is further filtered.
2015-04-14
Technical Paper
2015-01-1600
Tong Zou, Lu Xiong, Pengfei Yang, Chi Jin
Distributed drive electric vehicles are driven by four independent hub motors mounted directly in wheels while retaining the traditional hydraulic brake system. So it can quickly produce drive/brake motor torque and large stable hydraulic brake force. In this paper a control allocation strategy for distributed drive electric vehicles (EV) is proposed to improve vehicles’ lateral stability performance. It exploits the quick response of motor torque and controllable hydraulic pressure of the hydraulic brake system. The allocation strategy is consisted of two sections. The first section uses an optimal allocation controller to calculate the total longitudinal force at each wheel. In the controller, a dynamic efficiency matrix is introduced via local linearization to improve lateral stability control performance, as it considers the influence of tire coupling characteristics over yaw moment control in extreme situations.
2015-04-14
Technical Paper
2015-01-1118
Fengyu Liu, Li Chen, Jian Yao, Jianlong Zhang, Chengliang Yin, Dongxu Li, Chunhao Lee, Ying Huang
A New Clutch Actuation System for a Dry DCT Fengyu Liu, Li Chen, Jian Yao, Jianlong Zhang, Cheng-Liang Yin Shanghai Jiao Tong University Dongxu Li, Chunhao Lee, Ying Huang General Motors LLC Abstract Dry DCT has played an important role in the high performance applications as well as low-cost market sectors in Asia, with a potential as the future mainstream transmission technology due to its high mechanical efficiency and driving comfort. Control system simplification and cost reduction has been critical in making dry DCT more competitive against other transmission technologies. Specifically, DCT clutch actuation system is a key component with a great potential for cost-saving as well as performance improvement. This paper is to propose a new actuation system that has a unique force-aid spring and consume less power. The main components of this mechanism include a lever and a pre-loaded spring. The spring can store and release energy when needed.
2015-04-14
Technical Paper
2015-01-0627
Xiaoguang Yang, Oluremi Olatunbosun, Daniel Garcia-Pozuelo, Emmanuel Bolarinwa
The development of intelligent tyre technology from concept to application covers multi-disciplinary fields. During its development course, computational method has a significant effect on understanding tyre behaviour, assisting design of intelligent tyre prototype system and developing tyre parameters estimation algorithm, etc. In this paper, finite element tyre model was adopted for developing strain-based intelligent tyre system. The finite element tyre model was created considering tyre composite structure and nonlinear material properties, which was also validated by fundamental test. It is used to study tyre strain characteristics by steady state simulation for straight line rolling, traction and braking, and cornering rolling. Tyre loading conditions were estimated by feature extraction and data fitting. This process forms the fundamentals for identifying tyre loadings from strain information on potential sensor locations.
2015-04-14
Technical Paper
2015-01-0626
Adam C. Reid, Moustafa El-Gindy, Fredrik Oijer, David Philipps
The purpose of this research paper is to outline the methodology and procedure used for the development of a wide base rigid ring tire model. A rigid ring model is a mechanical representation of a tire model in which its in-plane and out-of-plane characteristics and behaviour can be captured. The FEA construction of the tire model is first completed to match all known information regarding the physical dimensions and material properties of the tire. For information that is unknown, an optimization-based parameter tuning algorithm is then run in order to solve for said parameters while matching any experimental data that is supplied. A series of virtual experiments are then conducted which replicate laboratory tests as well as some high speed maneuvers in order to isolate for specific tire dynamic parameters.
2015-04-14
Technical Paper
2015-01-1117
Yang Liu, Zechang Sun
Regenerative braking control for a four-wheel drive (4WD) electric vehicle equipped with a decoupled electro-hydraulic brake system was studied. The 4WD electric vehicle powertrain with four in-wheel motors was introduced, and the four motors could be controlled independently during the driving or braking operation modes, which have advantages on powertrain configurations and fuel economy improvement over the vehicles driven by a single motor. An electro-hydraulic brake system using a master cylinder integrated with brake pedal feel simulator, hydraulic brake booster and failure backup was adopted to guarantee the coordinate control between the regenerative force and the hydraulic force, whose brake pedal force and wheel cylinder pressure was decoupled. The energy flow of the 4WD electric vehicle was analyzed during braking, and the brake force distribution strategy between the front-rear axles, in-wheel motor regenerative braking and hydraulic braking was studied.
2015-04-14
Technical Paper
2015-01-1127
Wenbin Liu, Gangfeng Tan, Xiaoqing Tian, Zhiqiang Hu, Yuanqi Gao, Zhi Li, Junyi Yuan, Wei Liu
As a kind of an important auxiliary brake of heavy vehicle, hydraulic retarder has good performance for stability and braking sustainability. However, the hydraulic retarder is filled with air when the vehicle is traveling in non-braking state, and the Air-friction may reduce the vehicle transmission efficiency obviously.   The air density in retarder cavity can be decreased by pumping the gas, which can reduce the transmission power loss. The gas pumping in retarder cavity has an important influence on the retarder working stability. Firstly, the dynamic characteristics relationships between the vacuum degree and the change of flow resistance in retarder cavity are analyzed by the 3D fluid simulation in different driving conditions, and the stability boundary conditions of the Air-friction change is determined.
2015-04-14
Technical Paper
2015-01-1120
Siddhartha Singh, Sudha Ramaswamy
Driving comfort is very important selling factor in today’s automobile market. Manual Transmission Clutch systems has to balance between driving control given to the driver and driver comfort.If ergonomics of ABC pedals are not taken care, driving stress will increase. The increase in engine torque because of change in technologies like turbocharging and pressure injection has also increased the release load for actuating clutch which in turn increases pedal load. There are many assistance mechanisms integrated with pedal to reduce the load like over-center spring, double torsion spring, each with its own limitations.
2015-04-14
Technical Paper
2015-01-0527
Pierre-Olivier Santacreu, Guillaume Badinier, Jean-Benoit Moreau, Jean-Marc Herbelin
A new Ni-free martensitic stainless steel was developed for hot stamped automotive parts, especially in order to design lightweight chassis. After hot stamping simulation, the material exhibits 1.2 GPa ultimate tensile strength with 8% total elongation, in the as-quenched condition (without any tempering treatment). Moreover the material’s chemical composition was optimised to improve the ductility at low temperature and during high strain rate mechanical testing. As a result, no brittle fracture in impact testing at -40°C was observed, and a good behaviour in crash was recorded. To further assess the material’s performance, high cycle and low-cycle fatigue properties of the grade were characterized and the effects of machining and surface were studied. Results show that the fatigue limits at 2 million cycles for a stress ratio of -1 for rough bare surface and shot peened surface are quite high at 0.45 and 0.55 times the ultimate tensile strength (in the range of 540 MPa to 640 MPa).
2015-04-14
Technical Paper
2015-01-1601
Long Chen, Mingyuan Bian, Yugong Luo, Keqiang Li
Nowadays, vehicle active safety systems have attracted more attention than ever before due to the dramatically increasing demand for driving safety.Since the forces between the tires and road interface primarily determine the states of vehicle motion, accurate information about road-tire friction coefficient is crucial to get a better performance in such system. As a new type of vehicle structure, the distributed electric vehicle, which has some advantages in estimating states of vehicle and tire, may bring new breakthroughs in estimating road-tire friction coefficient. This paper proposes a method of estimating road-tire friction coefficient for the distributed electric vehicle during the pure longitudinal wheel slip, lateral sideslip and combined slip situations.
2015-04-14
Technical Paper
2015-01-1598
Milad Jalaliyazdi, Amir Khajepour, Shih-Ken Chen, Bakhtiar Litkouhi
In this paper, the problem of stability control of an electric vehicle is addressed. To this aim, it is required that the vehicle follows a desired yaw rate at all driving/road conditions. The desired yaw rate is calculated based on steering angle, vehicle speed, vehicle geometric properties as well as road condition. The vehicle response is modified by torque vectoring on front and/or rear axles. This control problem is subject to several constraints. The electric motors can only deliver a certain amount of torque at a given rotational speed. In addition, the tire capacity also plays an important role in the stability control. It limits the amount of torque they can transfer without causing wheel over spinning. These constraints make Model Predictive Control (MPC) approach a suitable choice, because it can explicitly consider the constraints of the control problem, in particular the tire capacity, and help to prevent tire saturation, which is often the onset of vehicle instability.
2015-04-14
Technical Paper
2015-01-0628
Bin Li, Xiaobo Yang, Yunqing Zhang, James Yang
As one of the most important components of a vehicle, a tire is essential for vehicle handling, ride comfort as well as durability. Although several decade efforts have been dedicated to tire modeling, there is still room to improve its performance. Currently tire models cannot accurately predict the longitudinal spindle force under severe road conditions. In order to improve the prediction results, a detailed in-plane flexible ring tire model is proposed based on multi body dynamic (MBD) approach in this paper. In this model, we discretize the belt into different belt segments, and each belt segment is considered as a rigid body and attached to a number of parallel tread blocks. This model is able to describe the tire behavior for the transformation among static condition, quasi-static rolling, as well as dynamic rolling conditions.
2015-04-14
Technical Paper
2015-01-0607
Xincheng Liang, Jingshan Zhao
This paper proposes a theoretical model to interpret the heat generation mechanism and thermal failure of shock absorber. For a common structure of double-tube shock absorber, all frictions between two contacting components of shock absorber are calculated particularly. The heat generation mechanism and heat distribution can be explained with the theoretical model. Thermal failure is a recurrent malfunction for traditional shock absorber, which leads to shorten the service lives of vehicle components. Heat generation experiments are accomplished to validate the thermal degeneration of shock absorber. So this study is meaningful to develop a new system of vibration attenuation that is essential to improve the riding comfort and handling stability of vehicles.
2015-04-14
Technical Paper
2015-01-1436
Divyanshu Joshi, Anindya Deb, Manoj Mahala, Clifford Chou
In the past few decades, increasing concern for vehicle occupant safety and comfort has motivated the development of advanced tools for vehicle dynamics analysis. To date, most of the published work on vehicle stability predominantly employs basic handling models such as 2-DOF (degrees of freedom) bicycle model, as well as 3, 4 and 5-DOF models that capture lateral and yaw dynamics alone or coupled with longitudinal, roll and pitch dynamics. 2-DOF quarter car, 4-DOF half car and 7-DOF full car models are found to be the most popular configurations for ride comfort analysis. It is noted that ride comfort and stability have mostly been dealt with independently by researchers, however, a coupling may exist in reality when a vehicle encounters road irregularities, bumps, potholes, etc. while undergoing a maneuver.
2015-04-14
Journal Article
2015-01-0622
H. Metered, A. Elsawaf, T. Vampola, Z. Sika
Proportional integral derivative (PID) control technique is the most common control algorithm applied in various engineering applications. Also, particle swarm optimization (PSO) is extensively applied in various optimization problems. This paper introduces an investigation into the use of a PSO algorithm to tune the PID controller for a semi-active vehicle suspension system incorporating magnetorheological (MR) damper to improve the ride comfort and vehicle stability. The proposed suspension system consists of a system controller that determine the desired damping force using a PID controller tuned using PSO, and a continuous state damper controller that estimate the command voltage that is required to track the desired damping force. The PSO technique is applied to solve the nonlinear optimization problem to find the PID controller gains by identifying the optimal problem solution through cooperation and competition among the individuals of a swarm.
2015-04-14
Journal Article
2015-01-0621
Mina M.S. Kaldas, Kemal Çalışkan, Roman Henze, Ferit Küçükay
Nowadays with the advances in the vehicle control systems, the customers want new and exciting features in their vehicles, which make the vehicle driving characteristics adjustable as they prefers. One of the vehicle controlled systems which can be used to change the vehicle driving characteristics from time to time is the semi-active suspension system. Therefore, the paper presents a rule-optimized fuzzy controller for semi-active suspension system which is continuously adjusts itself according to the road conditions and the drivers’ requirements. The proposed rule-optimized fuzzy controller has three different control modes (Sport, Normal and Comfort), which can be switched using the button and thus adjusted to customer requirements. The Normal Mode is adjusted to provide an overall balance between the vehicle ride comfort and road holding. On the other hand, the Comfort Mode is adapted to leads to a comfort-oriented, softer basic configuration of the damping.
2015-04-14
Technical Paper
2015-01-0492
Gaurav Paliwal, Naveen Sukumar, Umashanker Gupta, Ashutosh Dubey, Nitin Chopra
The need to develop products faster and to have designs which are first time right have put enormous pressure on the product development timelines, thus making Computer Aided Optimization one of the most important tool in achieving this targets. In this paper, a Design of Experiments (DOE) study is used, to gain an insight as to, how changes to different parameters of Front Suspension & Steering of a Passenger Bus affect its kinematic properties & thus to obtain an optimized design in terms of Handling parameters such as bump steer, roll steer, percent Ackermann, Lock to Lock rotation angle. The Conventional Hit & Trial method is time consuming and monotonous & still is an approximate method, whereas in Design of Experiments (DOE), a model is repeatedly run through simulations in a single setup, for various combinations of parameter settings. Effects and interactions of the design variables of the model are then studied, which provides an insight to help design an optimized model.
2015-04-14
Technical Paper
2015-01-1417
Jeffrey Muttart
An analysis was performed utilizing the results from seven emergency steering studies and four routine lane change studies. Closed course and naturalistic research were included. These studies showed that in a routine lane change, Drivers reached peak lateral acceleration approximately one-second after steering after which lateral acceleration decreases linearly. These results were consistent with those from forward and backing acceleration research published elsewhere. Though, when drivers steered in response to an emergency situation, again, peak lateral acceleration occurred near one-second after steering onset, but average lateral acceleration decreased non-linearly. This non-linear decrease between onset of steering and completion of the maneuver was indicative of counter-steering, or reduced subsequent steering (straightening). The results show that the average lateral acceleration could be modeled with a power function.
2015-04-14
Technical Paper
2015-01-1328
Da-Wei Gao, Xing-Xing Huang, Jun Xu, Song-Lin Zheng
Taking a domestic brand car as example, this paper is about how to find out a three-point nonlinear stiffness characteristic curve which can meet the requirements of variable stiffness and three-load condition. The new coil spring gives the passive suspension a lot of improvement in riding and safety, changing the nonlinear stiffness characteristic performance from weak to strong. This paper summarizes the optimization design method for the rear suspension coil spring, including the fitting of ideal stiffness characteristic curve,quantitative method for figuring out how the change of vehicle load influences the load on rear suspension axle,the design method of variable stiffness coil spring which corresponds to the change of vehicle load. A new kind of modified ideal point solution for building the objective function was also put forward.
2015-04-14
Technical Paper
2015-01-1356
Atishay Jain
Swingarm, originally known as the swing fork or pivoted fork is a dynamic structural part of the rear suspension of most modern motorcycles. It is used to hold the rear axle firmly, while pivoting vertically on the frame, to allow the suspension to absorb bumps in the road. Driving and braking loads are also transmitted through the swing arm, and thus, it plays a major role in vehicle dynamics. Weight minimization is important in a swingarm as it is largely an unsprung mass. The conventional swingarm design includes steel tubing and sheet metal structures. Due to higher forces near the pivot, conventional swingarm are inherently over-designed as they use tubular structures of same cross section through the entire length of the swingarm. An aluminum alloy swingarm design even when subjected to casting manufacturing constraints, has the potential for better material layout and weight minimization.
2015-04-14
Technical Paper
2015-01-1345
Srinivas Kurna, Arpit Mathur, Sandeep Sharma
In commercial vehicle, Leaf Spring design is an important milestone during product design and development. Leaf springs are the most popular designs having multiple leaves in contact with each other and show hysteresis behavior when loaded and unloaded. Commonly used methods for evaluation of leaf spring strength like endurance trials on field and Rig testing are time consuming and costly. On the other hand, virtual testing methods for strength and stiffness evaluation give useful information early in the design cycle and save considerable time and cost. They give flexibility to evaluate multiple design options and accommodate any design change early in development cycle. A study has been done in VECV to correlate rig result with FEA simulation result of Multi-stage Suspension Leaf Spring, entirely through Finite Element Analysis route. Virtual leaf spring with U-Clamps and Suspension brackets with revolute joints are modeled in FEA which is similar to rig test bed setup.
2015-04-14
Technical Paper
2015-01-1464
Qiang Chen, Miao Lin, Bing Dai, Jiguang Chen
The objective of this work was to describe typical accident scenarios for pedestrian accidents in China. The accident analysis aims to develop test procedures for assessing Autonomous Emergency Braking (AEB) systems. Beyond that, this study was also with the goal of estimating the effectiveness of potential reduction of fatally and severely injured pedestrians by AEB systems.Based on statistics, more than 25% of traffic fatalities were pedestrians in China. Autonomous Emergency Braking (AEB) systems are already penetrating the vehicle market and are designed to offer protection against the occurrence and severity of collisions. However there is a need to evaluate the systems and their effectiveness. Test methods for such active safety systems are being developed and will be implemented in NCAP tests in the near future, e.g. 2016 in Euro-NCAP, and most probably in 2018 C-NCAP tests (still in consulting phase).
2015-04-14
Technical Paper
2015-01-1574
Tao Sun, Yuping He
The phase-plane approach is a powerful tool for analyzing yaw stability of single-unit vehicles. Articulated vehicles, such as car-trailer combinations, consist of multiple vehicle units. Multi-unit vehicles exhibit unique dynamic features compared against single-unit vehicles. For example, a car-trailer may experience one of the three unstable motion modes, i.e., jack-knifing, trailer sway and rollover. Considering the distinguished configurations and dynamic features of articulated vehicles, it is questionable whether the phase-plane approach is applicable to the analysis of the lateral stability of the multi-unit vehicles. In order to address the problem, case studies are conducted to test the effectiveness of the application of the phase-plane to the analysis of the lateral stability of a car-trailer combination with and without an active trailer differential braking (ATDB) system.
2015-04-14
Technical Paper
2015-01-0689
R. Rajendran, G. Ramanjaneyulu, T R Tamilarasan, Vladimir I. Semenov
Cryogenic treatment has a good potential to significantly increase the service life of automotive components, where friction and wear are the major factors in their operation leading to failure. Cryogenic treatment changes the surface as well as the core properties of the component in comparison with other treatments. It has significant improvement in dimensional stability, wear resistance and toughness. Numerous studies have been conducted on cryogenic treatment of steels and tool steels showing significant improvements in wear resistance, only minimal work has been done in cast irons. In this study the effects of cryogenic treatment on the wear resistance, hardness, tensile strength, toughness and microstructure of spheroidal graphite iron was assessed. The deep cryogenic treatment was carried out at 87 K for 12h and annealed in the chamber itself. The samples were then tempered at 473 k for 1 h.
2015-04-14
Technical Paper
2015-01-1572
L. Daniel Metz, J. Sneddon
Deteriorated roadway surfaces (potholes) encountered under everyday driving conditions produce external vehicle disturbance inputs that are potentially destabilizing and highly transient. We examine vehicle behavior in response to such inputs through simulation. Idealized pothole geometrical configurations are used to represent common deteriorated roadway surfaces, and as environments in the HVE simulation suite of programs. Differences in vehicle behavior are catalogued and the potential for destabilized vehicle behavior is examined, particularly under conditions in which only one side of the vehicle contacts the pothole. Vehicle types employed in the simulations consist of a sedan, sports car and SUV. Results show that many combinations of speed, vehicle type and pothole configuration have significant destabilizing effects on vehicles.
2015-04-14
Technical Paper
2015-01-1573
Guirong Zhuo, Hui Shen, Shenchen Wu, Yilin Ren
In order to regulate the hydraulic braking force accurately and independently by controlling high speed on-off valves (HSV), parameterized finite element models of HSV are established based on the measured ABS hydraulic actuator unit (HCU) parameters and its transient electromagnetic characteristics are analyzed by the ANSYS software. During the process, an ABS HCU developed by TRW Inc is dismantled and interrelated parameters are acquired to build an HSV CAD model, which mainly consists of drive circuit, electromagnet and mechanical-hydraulic module. Next, 12V voltage is selected as step loading and the 2D transient electromagnetic fields are analyzed. The inductance L is acquired, together with the ampere turns Ni of the solenoid and the electromagnetic force F of the valve core, which is dealt into F-x-Ni and L-x-Ni 3D data sheets. In the end, an accurate physical model of HSV is accomplished by the AMESim software.
2015-04-14
Technical Paper
2015-01-1586
Guirong Zhuo, Jin Wang, Fengbo Zhang
The automobile driving system, of which tire is an important part, ensures the drivability handing stability and riding comfort of the vehicle. The magic formula tire model is put forward by H.B.Pacejka, which is a semi-empirical tire model. The magic formula tire model is a steady state tire model that can accurately reflect the tire characteristics. This model may fully express longitudinal force, lateral force, self-aligning torque, turning torque, rolling resistance torque and longitudinal and lateral force for combined slips mode. It has highly commonality and is the most widely used tire model in study of vehicle dynamics nowadays. Also the magic formula tire model has disadvantage. The model contains too much parameters, so that the method of parameter identification of magic formula tire model is too complex, which course an inconvenience in the engineering application.
2015-04-14
Technical Paper
2015-01-1578
Kaoru Kusaka, Nobuyuki Nagayama
Tire is one of the most important parts of vehicle chassis which characterizes chassis performance greatly and affects wide range of vehicle performances and qualities such as handling response and directional stability, braking distance, ride comfort, noise and vibration, fuel consumption and so on because all the movement of vehicle is raised by forces and moments from tires. And tire is also one of the largest chassis components which influences overall vehicle layout like wheel base or track width. Therefore the basic specification of the tire should be properly determined so that that size of the tire can satisfy the needs for vehicle performance better with smaller resources. In the field of the vehicle development, computer simulations plays more important role on vehicle performance improvement so that the vehicle design can satisfy the rapidly changing demand of the customers by shorter period of product development.
Viewing 1 to 30 of 7609