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Training / Education
2014-07-22
One of the most important safety critical components on cars, trucks, and aircraft is the pneumatic tire. Vehicle tires primarily control stopping distances on wet and dry roads or runways and strongly influence over-steer/under-steer behavior in handling maneuvers of cars and trucks. The inflated tire-wheel assembly also acts as a pressure vessel that releases a large amount of energy when catastrophically deflated. The tire can also serve as a fulcrum, both directly and indirectly, in contributing to vehicle rollover. This seminar covers these facets of tire safety phenomena. Engineering fundamentals are discussed and illustrated with numerous practical examples and case studies of current public interest. The Pneumatic Tire, a 700-page E-book on CD, edited by Joseph Walter and Alan Gent is included in the course material. This course has been approved by the Accreditation Commission for Traffic Accident Reconstruction (ACTAR) for 7 Continuing Education Units (CEUs). Upon completion of this seminar, accredited reconstructionists should contact ACTAR, 800-809-3818, to request CEUs.
Training / Education
2014-07-21
The principal functions of the pneumatic tire are to generate driving, braking, and cornering forces while safely carrying the vehicle load and providing adequate levels of ride comfort. This seminar explains how tire forces and moments are generated under different operating and service conditions and, in turn, demonstrates how these forces and moments influence various vehicle responses such as braking, handling, ride, and high-speed performance. The content focuses on the fundamentals of tire behavior in automobiles, trucks, and farm tractors, but also includes experimental and empirical results, when necessary. The Pneumatic Tire, a 700-page E-book on CD, edited by Joseph Walter and Alan Gent is included in the course material. This course has been approved by the Accreditation Commission for Traffic Accident Reconstruction (ACTAR) for 7 Continuing Education Units (CEUs). Upon completion of this seminar, accredited reconstructionists should contact ACTAR, 800-809-3818, to request CEUs.
Technical Paper
2014-05-10
Hyeonu Heo, Jaehyung Ju, Doo Man Kim, Harkbong Kim
An understanding of the flow around a tire in contact with the ground is important when designing fuel-efficient tires as the aerodynamic drag accounts for about one third of an entire vehicle's rolling loss. Recently, non-pneumatic tires (NPTs) have drawn attention mainly due to their low rolling resistance associated with the use of low viscoelastic materials in their construction. However, an NPT's fuel efficiency should be re-evaluated in terms of aerodynamic drag: discrete flexible spokes in an NPT may cause more aerodynamic drag, resulting in greater rolling resistance. In this study, the aerodynamic flow around a non-pneumatic tire in contact with the ground is investigated for i) stationary and ii) rotating cases using the steady state Reynolds-Averaged Navier-Stokes (RANS) method. A sensitivity analysis was carried out with a varying mesh density. The flow into cavity by the discrete spoke geometry of the NPT does not significantly affect the overall aerodynamic drag.
Event
2014-04-10
Event
2014-04-10
WIP Standard
2014-04-10
This SAE Recommended Practice provides performance and sampling requirements, test procedures, and marking requirements for aftermarket wheels intended for normal highway use on passenger cars, light trucks, and multipurpose passenger vehicles. For aftermarket wheels on trailers drawn by passenger cars, light trucks or multipurpose vehicles, see SAE J1204. These performance requirements apply only to wheels made of materials included in Table 1 and Table 2. New nomenclature and terms are added to clarify wheel constructions typically not used in OEM applications. The testing procedures and requirements are based on SAE standards listed in the references.
WIP Standard
2014-04-10
This SAE Recommended Practice provides a method for testing the speed performance of light truck tires under controlled conditions in the laboratory on a test wheel.
WIP Standard
2014-04-10
This Recommended Practice describes the determination of tire pull force properties for an uninclined tire (SAE J670e) on a laboratory flat surface tire force and moment machine. It is suitable for accurately determining pull forces and residual aligning moments for passenger and light-truck tires. These properties are important determinants of vehicle trim. They describe steady-state, free-rolling pull effects ascribable to tires. The test method described in this document is suitable for comparative evaluation of tires for research and development purposes. The method is also suitable for modeling when followed carefully.
WIP Standard
2014-04-10
This SAE Recommended Practice provides a method for testing the speed performance of passenger car tires under controlled conditions in the laboratory on a test wheel. This procedure applies to "standard load," "extra load," and "T-type high-pressure temporary-use spare" passenger tires.
WIP Standard
2014-04-10
This SAE Recommended Practice describes the determination of passenger car and light truck tire force and moment properties on a belt-type flat surface test machine. It is suitable for accurately determining five tire forces and moments in steady-state under free-rolling conditions as a function of slip angle and normal force which are incrementally changed in a given sequence. Heavy-duty tires are not considered in this document, because the measuring system would have force and moment ranges too large to meet sensitivity requirements for passenger and light truck tire force and moment measurements. A standard for heavy-duty truck tires would have many of the same features as this document, but the measuring system, would have to be extensively altered. Inclination angle combined with slip angle, pull forces, and any combination with spindle torque are not considered in this document. Standards needed for these topics will be considered separately. The test method described in this document is suitable for comparative evaluations of tires for research and development purposes.
Event
2014-04-09
Advanced concepts and modeling of tires will be presented by industry and university researchers.
Event
2014-04-01
WIP Standard
2014-04-01
This SAE Standard applies to the usage of tires of the same nominal size and tread type, but with different outside diameter for articulated front-end loaders. Articulated four-wheel-drive front-end loader performance and component life can be affected by excessive differences in the tire outside circumference and/or diameter. The purpose is to provide specific guidelines for the usage of tires with different outside circumference and/or diameter on articulated front-end loaders.
Technical Paper
2014-04-01
Haizhen Liu, Weiwen Deng, Changfu Zong, Jian Wu
Abstract This paper first presents an algorithm to detect tire blowout based on wheel speed sensor signals, which either reduces the cost for a TPMS or provides a backup in case it fails, and a tire blowout model considering different tire pressure is also built based on the UniTire model. The vehicle dynamic model uses commercial software CarSim. After detecting tire blowout, the active braking control, based on a 2DOF reference model, determines an optimal correcting yaw moment and the braking forces that slow down and stop the vehicle, based on a linear quadratic regulator. Then the braking force commands are further translated into target pressure command for each wheel cylinder to ensure the target braking forces are generated. Some simulations are conducted to verify the active control strategy. From the simulation results, it is shown that this active brake control strategy can not only ensure the flat tire vehicle stability, but also slow down the vehicle with a safe speed and for a shorter distance.
Technical Paper
2014-04-01
Shahyar Taheri, Corina Sandu, Saied Taheri
Studying the kinetic and kinematics of the rim-tire combination is very important in full vehicle simulations, as well as for the tire design process. Tire maneuvers are either quasi-static, such as steady-state rolling, or dynamic, such as traction and braking. The rolling of the tire over obstacles and potholes and, more generally, over uneven roads are other examples of tire dynamic maneuvers. In the latter case, tire dynamic models are used for durability assessment of the vehicle chassis, and should be studied using high fidelity simulation models. In this study, a three-dimensional finite element model (FEM) has been developed using the commercial software package ABAQUS. The purpose of this study is to investigate the tire dynamic behavior in multiple case studies in which the transient characteristics are highly involved. The process of running dynamic FE tire simulations starts by statically inflating and loading the tire using an implicit method with refined mesh in the contact patch.
Technical Paper
2014-04-01
Edoardo Sabbioni, Federico Cheli, Matteo Riva, Andrea Zorzutti
Abstract For passenger cars, individual tyre model parameters, used in vehicle models able to simulate vehicle handling behavior, are traditionally derived from expensive component indoor laboratory tests as a result of an identification procedure minimizing the error with respect to force and slip measurements. Indoor experiments on agricultural tyres are instead more challenging and thus generally not performed due to tyre size and applied forces. However, the knowledge of their handling characteristics is becoming more and more important since in the next few years, all agricultural vehicles are expected to run on ordinary asphalt roads at a speed of 80km/h. The present paper presents a methodology to identify agricultural tyres' handling characteristics based only on the measurements carried out on board vehicle (vehicle sideslip angle, yaw rate, lateral acceleration, speed and steer angle) during standard handling maneuvers (step-steers, J-turns, etc.), instead than during indoor tests.
Technical Paper
2014-04-01
Yuhang Chen, Yunfeng Ji, Konghui Guo
Abstract In this paper, a sliding mode observer for estimating vehicle slip angle and tire forces is developed. Firstly, the sliding mode observer design approach is presented. A system damping is included in the sliding mode observer to speed the observer convergence and to decrease the observer chattering. Secondly, the sliding mode observer for vehicle states is developed based on a 7 DOF embedded vehicle model with a nonlinear tire model ‘UniTire’. In addition, since the tire lateral stiffness is sensitive to the vertical load, the load transfers are considered in the embedded model with a set of algebraic equations. Finally, a simulation evaluation of the proposed sliding mode observer is conducted on a validated 14 DOF vehicle model. The simulation results show the model outputs closely match the estimations by the proposed sliding mode observer.
Technical Paper
2014-04-01
Walid Oraby, Mahmoud Atef Aly, Samir El-demerdash, M. El-Nashar
Abstract Integral Control strategy for vehicle chassis systems had been of great interest for vehicle designers in the last decade. This paper represents the interaction of longitudinal control and lateral control. In other words the traction control system and handling control system. Definitely, tire properties are playing a vital role in such interaction as it is responsible for the generated forces in both directions. A seven degrees of freedom half vehicle model is derived and used to investigate this interaction. The vehicle body is represented as a rigid body with three degrees of freedom, lateral and longitudinal, and yaw motions. The other four degrees are the two rotation motion of the front wheel and the rear wheel. This two motions for each wheel are spin motion and the steering motion. The traction controller is designed to modulate engine torque through adjusting the throttle angle of the engine upon utilized adhesion condition at the driving road wheels. The active four steering (4WS) control system is designed to enhance vehicle lateral dynamics through controlling rear steer angle.
Technical Paper
2014-04-01
Axel Gallrein, Manfred Baecker, Michael Burger, Andrey Gizatullin
Abstract In the last two years, Fraunhofer has developed an advanced tire model which is real-time capable. This tire model is designed for ride comfort and durability applications for passenger cars and trucks, as well as for agricultural and construction machines. The model has a flexible belt structure with typically about 150 degrees of freedom and a brush contact formulation. To obtain sufficient computational efficiency and performance for real time, a dedicated numerical implicit time-integration scheme has been developed. Additionally, specific coordinate frames were chosen to efficiently calculate and use the needed Jacobian matrices. Independently from this, Fraunhofer ITWM has developed and installed the new driving simulator RODOS (RObot based Driving and Operation Simulator), which is based on the industrial robot KUKA KR1000. The main application area of this driving simulator are interactive human-in-the-loop simulations with agricultural and construction machines, but also with trucks and passenger cars.
Technical Paper
2014-04-01
Adam C. Reid, David Philipps, Fredrik Oijer, Inge Johansson, Moustafa EL-Gindy
Abstract The rigid-ring tire model is a simplified tire model that describes a tire's behaviour under known conditions through various in-plane and out-of-plane parameters. The complex structure of the tire model is simplified into a spring-mass-damper system and can have its behaviour parameterized using principles of mechanical vibrations. By designing non-linear simulations of the tire model in specific situations, these parameters can be determined. They include, but are not limited to, the cornering stiffness, vertical damping constants, self-aligning torque stiffness and relaxation length. In addition, off-road parameters can be determined using similar methods to parameterize the tire model's behaviour in soft soils. By using Finite Element Analysis (FEA) modeling methods, validated soil models are introduced to the simulations to find additional soft soil parameters. By determining the full FEA tire model's characteristics, a simplified rigid-ring model can replace the complex model in full vehicle model simulations to reduce computation time and effort.
Technical Paper
2014-04-01
Andrew Nevin, Eric Daoud
Abstract Traditional tread depth measurements require manual utilization of a mechanical device to acquire measurements at each location of interest on a tire. Drive-over machine-vision sensors are becoming available as a means for measuring tread depth. These sensors typically consist of a laser and a camera contained in an environmentally-sealed sensor housing. Tires approach the sensor over the supporting surface, while a laser projects an illuminating line across the tread surface for capture in a digital image. This scan is evaluated to provide a single 2D contour of tread depth at the illuminated line. Advanced machine-vision sensors acquire a sequence of images, which results in a multitude of data points over a 3D region of the tread surface. Post-processing of the acquired images illustrates the observed tread pattern and establishes multiple tread depth measurements. Measurements determined by the advanced sensors from hundreds of tires were compared to manual measurements acquired with analog and digital mechanical gauges.
Technical Paper
2014-04-01
Ben Wen, Gregory Rogerson, Alan Hartke
Abstract Tire rolling resistance is one of tire performance indicator that represents a force needed to maintain the constant rolling of a tire. There are quite few methods and standards to measure tire rolling resistance, such as ISO-28585, ISO-18164, SAE-J1269, SAE-J2452, …. These tests have been used by tire companies, vehicle manufactures, and government agencies to evaluate tire rolling resistance performance. SAE-J1269 and SAE-J2452 are two popularly used multi-condition rolling resistance tests for passenger and light truck tires. Examining the test conditions and procedures of these two test standards showed that some key procedures and conditions from both standards are similar although there are many difference as well. The study presented here is to analyze test results from both tests and their correlation under certain conditions. If the correlation exists, one test may provide test results for both test conditions, therefore, test efficiency can be improved.
Technical Paper
2014-04-01
Yugong Luo, Kun Cao, Yifan Dai, Wenbo Chu, Keqiang Li
The current global chassis control (GCC) frequently makes use of decoupled control methods which depend on driving condition partition and simple rule-based vertical force distribution, and are insufficient to obtain optimal vehicle dynamics performance. Therefore, a novel hierarchical global chassis control system for a distributed electric vehicle (DEV), which is equipped with four wheel driving/steering and active suspension systems, is developed in this paper. The control system consists of three layers: in the upper layer, the desired forces/moments based on vehicular driving demands are determined; in the middle layer, a coordinated control method of longitudinal/lateral/vertical tire forces are proposed; in the lower layer, the driving/steering/suspension control is conducted to realize each distributed tire force. As the most outstanding contribution of this paper, a non-convex optimization problem with multiple constraints for coordinated control of longitudinal/lateral/vertical tire forces is solved, in which (1) tire force distribution problem is theoretically concluded as a constrained non-convex optimization problem, (2) a unique objective function that combines the tire workload and the dynamic ratio of the vertical forces is designed to evaluate tire force distribution, (3) 14 constraints including vehicular driving demands, tire friction limitations and actuator natures are involved to bound each tire force reasonably, and (4) an algorithm that combines constrained optimization and feasible region planning is proposed to solve the constrained non-convex optimization problem.
Technical Paper
2014-04-01
Scott Varnhagen, Donald Margolis
The use of electric motors to independently control the torque of two or four wheels of a vehicle has the potential to significantly improve safety and handling. One virtue of electric motors is that their output torque can be accurately estimated. Using this known output torque, longitudinal tire force and coefficient of friction can be estimated via a controller output observer. This observer works by constructing a model of wheel dynamics, with longitudinal tire force as an unknown input quantity. A known wheel torque is input to the physical and modeled system and the resulting measured and predicted wheel speeds are compared. The error between the measured and predicted wheel speed is driven towards zero by a robust feedback controller. This controller modulates an estimate of longitudinal tire force used as an input by the wheel dynamics model. The resulting estimate of longitudinal tire force quickly converges towards the actual value with minimal computational expense. Using this estimate, a methodology for controlling tire slip ratio is presented.
Technical Paper
2014-04-01
Mingyuan Bian, Long Chen, Yugong Luo, Keqiang Li
Abstract A new dynamic tire model for estimating the longitudinal/lateral road-tire friction force was derived in this paper. The model was based on the previous Dugoff tire model, in consideration of its drawback that it does not reflect the actual change trend that the tire friction force decreases with the increment of wheel slip ratio when it enters into the nonlinear region. The Dugoff model was modified by fitting a series of tire force data and compared with the commonly used Magic Formula model. This new dynamic friction model is able to capture accurately the transient behavior of the friction force observed during pure longitudinal wheel slip, lateral sideslip and combined slip situation. Simulation has been done under different situations, while the results validate the accuracy of the new tire friction model in predicting tire/road friction force during transient vehicle motion.
Technical Paper
2014-04-01
Austin Gurley
Abstract Selection of springs and dampers is one of the most important considerations when finalizing a race car suspension design. It is also one of most complex due to the dynamic interaction of the vehicle with the ground. Current tuning methods for spring and dampers' effect on vehicle ride can be based on simplified dynamic models of the vehicle, such as the quarter-car model. While efficient computationally, the traditional quarter-car model does not account for the non-linear variation in grip seen by a fluctuating contact-patch. Both amplitude and frequency of suspension oscillation contribute to loss of tire grip. The method can be improved by incorporation of a dynamic tire model, though resulting in non-linear effects. An improved ‘rolling quarter-car’ model is created, which includes the effect of dynamic tire forces in the analysis of improved grip. Using typical Formula SAE race car, characteristics as a test case, a linearized dynamic model is made. The effect of suspension parameters on the dynamic tire forces produced are surveyed.
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