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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
2015-01-0608
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
2015-01-0627
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
2015-01-0654
Bing Zhu, Jiapeng Gong, Jian Zhao, Jian Wu, Weiwen Deng
The permanent-magnet DC motor, which directly connected to the hydraulic pump, is a significant component of hydraulic control unit (HCU) in an anti-lock braking system (ABS). It drives the pump to dump the brake fluid from the low-pressure accumulator back to master cylinder and make sure the pressure decrease of wheel cylinder in ABS control. Obviously, the motor should run fast enough to provide sufficient power and prevent the low-pressure accumulator from fully charging. However, the pump don’t need always run at full speed for the consideration of energy conservation and noise reduction. Therefore, it is necessary to accurately regulate the speed of the DC motor in order to improve quality of ABS control. In this paper, a DC motor model was established using Matlab/Simulink software at first. Then the ABS hydraulic brake system model was present in AMESim.
2015-04-14
Journal Article
2015-01-0656
Amir Soltani, Francis Assadian
A new control strategy for wheel slip control, considering the complete dynamics of the electro-hydraulic brake (EHB) system, is developed and experimentally validated in Cranfield University’s HiL system. The control system is based on closed loop shaping Youla-parameterisation method. The plant model is linearized about the nominal operating point, a Youla parameter is defined for all stabilizing feedback controller and control performance is achieved by employing closed loop shaping technique. The stability and performance of the controller are investigated in frequency and time domain, and verified by experiments using real EHB smart actuator fitted into the HiL system with driver in the loop.
2015-04-14
Journal Article
2015-01-0655
Francesco Calabrese, Manfred Baecker, Carlos Galbally, Axel Gallrein
Current state-of-the-art tire models may show a certain lack of accuracy in some advanced handling applications. This lack of accuracy is partly due to thermal effects. In reality, the tire rubber temperature can dramatically increase under certain conditions. The tire friction coefficient strongly depends on the temperature level. As a direct consequence of the temperature variations, the tire’s handling performance changes, e.g. when the temperature significantly differs from its optimal value, the tire’s grip level declines. As a result, the vehicle’s longitudinal and lateral behavior is influenced. This paper shows that in order to increase the reliability of the tire models also in the described extreme conditions, it is necessary to couple a thermo-dynamical model with a mechanical one. The thermal model is important to estimate the temperature propagation inside the tire structure and the temperature evolution over time.
2015-04-14
Technical Paper
2015-01-1237
Xiaoming Chen, Jeff L. Conklin, Robert M. Carpenter, Jeff Wallace, Cynthia Flanigan, David A. Wagner, Vijitha Kiridena, Stephane Betrancourt, Jason Logsdon
As part of the Ford and Vehma collaborative efforts on the DOE sponsored project on Multi Materials Lightweight Vehicle, several automotive chassis components were identified for development and evaluation on a lightweight passenger vehicle. The lightweight prototype chassis parts included composite and hollow steel coil springs, carbon fiber wheels, tires with a tall and narrow design, hollow steel stabilizer bars, and an aluminum front cradle. The lightweight chassis parts development included mixed and multi materials to investigate potential weight savings. The glass fiber reinforced composite front spring and hollow steel rear springs achieved 59% and 37% weight savings respectively. Both springs passed required component tests and survived proving ground durability test with no issues detected. For the lightweight tall narrow tires, evaluations were conducted on three distinct sets of tires with varying material constructions and final weight in the range of 17 pounds per tire.
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
Journal Article
2015-01-1225
Chen Lv, Junzhi Zhang, Yutong Li, Ye Yuan
Abstract 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 is worthwhile researching for an advanced powertrain control of electrified vehicles during regenerative deceleration. In this study, a nonlinear powertrain of an electric passenger car equipped with a central motor is modeled using 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, an active control algorithm with a hierarchical architecture is studied for powertrain backlash compensation.
2015-04-14
Technical Paper
2015-01-0316
Kazuto Yokoyama, Masahiro Iezawa, Yohei Akashi, Toshihide Satake, Yukiyasu Akemi, Satoru Inoue, Ryotaro Suzuki
Abstract Parking assist systems which relieve burden of drivers have been put into practice in the world. Mitsubishi Electric has also been developing several technologies to realize the system, where our products such as sonar (ultrasonic sensor), electric power steering (EPS), a motor, and an inverter are used. In the parking assist system, peripheral environment of the vehicle in a parking lot is detected with our sonar sensors and determine whether or not there is a parking space available. Estimation of the position and the attitude of the vehicle is also carried out. On the basis of the detection and the estimation, a smooth and efficient path to drive and park the vehicle is generated with an optimization technique. In particular, this paper focuses on a drive control for electrified vehicles to track the reference trajectory at a desired speed given from the assist system.
2015-04-14
Journal Article
2015-01-0432
Xingxing Feng, Jinglai Wu, Yunqing Zhang, Ming Jiang
Abstract The optimization of vehicle suspension kinematic/compliance characteristics is of significant importance in the chassis development. Practical suspension system contains many uncertainties which may result from poorly known or variable parameters or from uncertain inputs. However, in most suspension optimization processes these uncertainties are not accounted for. This study explores the use of Chebyshev polynomials to model complex nonlinear suspension systems with interval uncertainties. In the suspension model, several kinematic and compliance characteristics are considered as objectives to be optimized. Suspension bushing characteristics are considered as design variables as well as uncertain parameters. A high-order response surface model using the zeros of Chebyshev polynomials as sampling points is established to approximate the suspension kinematic/compliance model.
2015-04-14
Journal Article
2015-01-0489
Jason Rogers
Abstract A 3D-and-Excel-based predictive tool was developed to determine trunk spring movement for preventing recurrence of a noise problem. While effective, the tool could not completely explain measured results on the completed body unit (CBU). Since design data is used as the input, it was hypothesized that the difference between predicted and actual results was related to tolerance variation on the actual vehicle. Using Siemens® Variation Analysis software, the CBU was built and simulated virtually with tolerances using a Monte Carlo model. The study found that the hypothesis was correct; tolerance variation was fully responsible for the differences. In addition, the study also allowed accurate prediction of failure rates.
2015-04-14
Journal Article
2015-01-0518
Hirokuni Fuchigami
Abstract In this research, a new wire material made using surface-reforming heat treatment was developed in order to enhance the corrosion fatigue resistance of suspension springs. The aim of surface reforming is to improve hydrogen embrittlement characteristics through grain refinement and to improve crack propagation resistance by partial softening of hardness. The grain refinement method used an α'→γ reversed transformation by rapid short-term heating in repeated induction heating and quenching (R-IHQ) to refine the crystal grain size of SAE 9254 steel spring wire to 4 μm or less. In order to simultaneously improve the fatigue crack propagation characteristics, the possibility of reducing the hardness immediately below the spring surface layer was also examined. By applying contour hardening in the second IHQ cycle, a heat affected zone (HAZ) is obtained immediately below the surface.
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
Technical Paper
2015-01-1371
Samuel T. Bartlett
Abstract With the many model variations produced on the same production line because of increasing power train options, fuel efficiency targets, performance and customer demands we saw limitations with our existing suspension mount equipment. Layout options were limited due to guided shifts and transfers. Large supporting frame work took up valuable floor space. Model wheelbase sizes and suspension pallets were limited to the model requirements of the original equipment. We needed an adaptable system to install the engine/front suspension assemblies and the rear suspension assemblies. We found a solution by utilizing the capabilities of 6-axis industrial robots to make the core components of the equipment simpler; many of the functions of a traditional machine can now be accomplished by the robot. We were able to vary install position to optimize handling characteristics and accommodate the model-to-model varieties on the same production line.
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
Journal Article
2015-01-0691
Salah H. R. Ali, Sarwat Z. A. Zahwi, Hassan H. Dadoura
Abstract The main aim of this work is to develop an identification method to demonstrate the crucial surfaces of automotive braking system. Two brand new brake discs manufactured by two different manufacturers are tested. A typical disc to the one of them was put under working condition in actual braking system. Dimensional and geometrical deviations are investigated using advanced engineering metrological technique. Mechanical properties, tribological characteristics and chemical analyses are investigated. A coordinate measuring machine, universal hardness tester, mass comparator and XRF spectrometer are used in these diagnoses. Measurements of dimensional and geometrical deviations such as disc thickness variations, thickness deviations, straightness, parallelism, runout of disc surfaces are conducted. A comparison between form deviations in disc surfaces have been carried out and analyzed.
2015-04-14
Technical Paper
2015-01-1373
Yulong Lei, Hui Tang, Xingjun Hu, Ge Lin, Bin Song
Abstract 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 braking equipment will become the future trend for commercial vehicle. Hydraulic retarder is superior to 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. Firstly, this paper presents a block modeling method for hydraulic retarder system.
2015-04-14
Journal Article
2015-01-1481
Myles Wilson, David Aylor, David Zuby, Joseph Nolan
Abstract The Insurance Institute for Highway Safety (IIHS) evaluates autonomous emergency braking (AEB) systems as part of its front crash prevention (FCP) ratings. To prepare the test vehicles' brakes, each vehicle must have 200 miles on the odometer and be subjected to the abbreviated brake burnish procedure of Federal Motor Vehicle Safety Standard (FMVSS) 126. Other organizations conducting AEB testing follow the more extensive burnishing procedure described in FMVSS 135; Light Vehicle Brake Systems. This study compares the effects on AEB performance of the two burnishing procedures using seven 2014 model year vehicles. Six of the vehicles achieved maximum AEB speed reductions after 60 or fewer FMVSS 135 stops. After braking performance stabilized, the Mercedes ML350, BMW 328i, and Volvo S80 showed increased speed reductions compared with stops using brand new brake components.
2015-04-14
Technical Paper
2015-01-1494
Quan Zhou, Xuexun Guo, Lin Xu, Guoling Wang, Jibing Zhang
Abstract Nowadays, off-highway vehicles enjoyed a significant status in the national defense and civil construction. There is no doubt that the working conditions of off-highways are quite different from the conventional passenger cars, hence, their suspensions are particularly designed. Since the hydro-pneumatic suspension technology is maturely applied in engineering machinery, this paper presents a concept for a novel energy-harvesting device, which is applied in off-highway vehicles based on hydro-pneumatic suspension, namely, electro-hydraulic energy-harvesting suspension (EHEHS). The EHEHS took the fundamental of mechanism-electronic-hydraulic system, which consisted the following elements: a cylinder, 2 check valves, a hydro-pneumatic spring, a hydraulic motor, a DC motor, a processing circuit and a battery. In the EHEHS system, the cylinder is used to transmit the vibration energy into hydraulic energy, which is stored in hydro-pneumatic spring.
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
2015-01-1522
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
Journal Article
2015-01-1564
Joshua L. Every, Dennis A. Guenther, Gary J. Heydinger
Typically, when one thinks of advanced driver assistance systems (ADAS), systems such as Forward Collision Warning (FCW) and Collision Imminent Braking (CIB) come to mind. In these systems driver assistance is provided based on knowledge about the subject vehicle and surrounding objects. A new class of these systems is being implemented. These systems not only use information on the surrounding objects but also use information on the driver's response to an event, to determine if intervention is necessary. As a result of this trend, an advanced level of understanding of driver braking behavior is necessary. This paper presents an alternate method of analyzing driver braking behavior. This method uses a frequency content based approach to study driver braking and allows for the extraction of significantly more data from driver profiles than traditionally would have been done.
2015-04-14
Journal Article
2015-01-1566
Youngil Koh, Kyongsu Yi, Kilsoo Kim
This paper presents a tire slip-angle based speed control race driver model. In developing a chassis control system for enhancement of high-speed driving performance, analysis of the vehicle-driver interaction at limit handling is one of the main research issues. Thus, a driver model which represents driving characteristics in a racing situation is required to develop a chassis control system. Since a race driver drives a vehicle as fast as possible on a given racing line without losing control, the proposed driver model is developed to ensure a lateral stability. In racing situation, one of the reasons which cause the lateral instabilities is an excessive corner-entry speed. The lateral instability in that moment is hard to handle with only a steering control. To guarantee the lateral stability of the vehicle while maximizing a cornering speed, a desired speed is determined to retain a tire slip-angle that maximizes lateral tire forces without front tire saturation.
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
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
Journal Article
2015-01-1579
Jun Nakahara, Koji Yamazaki, Yusuke Otaki
There exist some cars which ride performance become less comfortable on smooth road. If vibration transmissibility of suspension system on such a vehicle is evaluated by means of equivalent dynamic stiffness, it is found that the increase of storage stiffness deteriorates the vibration transmissibility of suspension due to the steep rising of hysteresis on wheel-stroke to wheel-load curve when excitation amplitude become small. To improve the ride-comfort performance on smooth road, therefore, the rising shape of wheel stroke curve due to hysteresis components, such as shock-absorber, ball-joints and rubber bushes, should be adjusted to prevent the increase of storage stiffness at small amplitude of suspension stroke. For investigating the hysteresis characteristics of these components, appropriate simulation models, which can reproduce their characteristics accurately, must be installed in the vehicle model and their parameters have to be determined with sufficient accuracy.
2015-04-14
Journal Article
2015-01-1567
Scott Bradley Zagorski, Tomoya Ushimura, James Post
Many vehicle dynamics handling simulations have utilized a constant speed two degree-of-freedom bicycle model. To add greater fidelity, a third (roll) degree-of-freedom has been included. The input to this model is typically road wheel angle. However, in an actual vehicle, the driver’s input is handwheel angle. Usually, to relate the two a simple kinematic relationship, on-center steering ratio, is used; however, the system dynamics of the steering system have considerable influence on overall vehicle response. By considering the chassis and steering system at an early stage of development then the interaction of the two can be characterized. Power steering system models are typically hydraulic-based power steering (HPS); however, contemporary power steering systems are predominantly electric-based (EPS). This research develops an EPS model which includes a three degree-of-freedom (DOF) steering model coupled with a three degree-of-freedom vehicle model and EPS maps.
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