Cornering Conditions Research Articles

A Theoretical and Experimental Investigation of the Effects of Inverted Wings Modifications on the Stability and Aerodynamic Performance of a Sedan Car at Cornering

ABSTRACTThis research examines the impact of cornering on the aerodynamic forces and stability of a Nissan Versa (Almera) passenger sedan car by introducing novel modifications. These modifications included single inverted wings with end plates as a front spoiler, double‐element inverted wings with end plates as a rear spoiler, and incorporating the ground as a diffuser under the car trunk. The goal is to enhance the performance and stability of conventional passenger cars. To ensure the accuracy of the numerical data, the study utilized multiple methodologies to model the turbulence model, ultimately selecting the most suitable option. This involved comparing numerical data with wind tunnel experimental data using force balance and pressure distribution. Once validated, the computational fluid dynamics (CFD) was employed to analyze the vehicle's aerodynamic performance relative to the straight‐line condition under cornering conditions. The car simulation in a cornering condition was conducted at a representative Reynolds number based on the vehicle length of about 1.3 × 107. The study discovered that asymmetry was a recurring theme regarding surface pressure distribution, with greater prominence under cornering conditions. All modified models exhibited a more favorable lift‐to‐drag ratio than the baseline, indicating improved aerodynamic efficiency. The underbody double‐element diffuser proved most effective for enhancing fuel efficiency and stability. Mesh refinement with a polyhedral algorithm consisting of 11.27 million elements and a computational domain with a frontal area of 91.8 m2 and a curved length of 31 m (˜7 times car length) was crucial for achieving accurate and repeatable results. The study employed multiple turbulence models within the CFD framework. The realizable k‐ε model was chosen due to its balance between accuracy and computational cost for all Nissan Versa models. These findings are limited to the selected parameters and wind tunnel conditions, and further investigations might be needed for extreme driving scenarios.

Effects of cornering conditions on the aerodynamic characteristics of a high-performance vehicle and its rear wing

This study investigates the aerodynamic behavior of a high-performance vehicle and the interaction with its rear wing in straight-line and steady-state cornering conditions. Analyses are performed with Reynolds-averaged Navier–Stokes based computational fluid dynamics simulations using a moving reference frame and overset mesh technique, validated against moving ground wind tunnel experiments. The results indicate a significant 20% decrease in downforce and 35% increase in drag compared to straight-line conditions at the smallest considered corner radius of 2.9 car-lengths. Downforce losses primarily stem from performance deficits on the underbody and rear wing, alongside elevated upper body lift. Drag penalties mainly result from additional pressure drag induced by a recirculation wake vortex generated behind the vehicle's inboard side. The vehicle's lateral pressure distribution is also affected, introducing a centripetal force that increases with smaller corner radii. Additionally, analyses of the rear wing reveal alternations of its aerodynamic characteristics in cornering, particularly impacting vortical flow and suction on the lower surface. Throughout the operating conditions, the rear wing's individual downforce contribution falls off beyond its stall angle. At higher angles of attack, the rear wing primarily generates downforce by pressurizing the vehicle's upper surfaces, but its interaction with the near-wake leads to a substantially increased pressure drag. Overall, these findings provide crucial insights into the intricate aerodynamic interactions of high-performance vehicles in diverse operating conditions as well as form an essential foundation for future research on static and active aerodynamic designs in the pursuit to optimize vehicle performance in dynamic driving conditions.

Finite Element Analysis and Optimization of Hydrogen Fuel Cell City Bus Body Frame Structure

Hydrogen fuel cell city bus is a type of new energy public transportation. In this paper, in order to evaluate the safety performance of a newly developed hydrogen fuel cell city bus body frame designed by the collaborating enterprise, finite element analysis is conducted to investigate its structural mechanics and dynamic characteristics under four typical operating conditions, including horizontal bending, ultimate torsion, emergency cornering, and emergency braking. Based on the simulation results, although the body frame of the bus meets the stiffness design requirements and avoids body resonance, it exhibits maximum stresses of 328.9 MPa and 348.6 MPa under emergency cornering and ultimate torsion conditions, respectively, exceeding the material yield strength and failing to satisfy the strength design requirements. Therefore, the size optimization method is employed to optimize the thickness of the body frame components. After optimization, the maximum stresses are reduced to 262.7 MPa and 300.6 MPa, respectively, representing a reduction of up to 20.13%. The optimization significantly improves performance and meets the strength design requirements. Furthermore, the body frame is lightened by 106 kg, achieving the goal of weight reduction.

An Analysis of Fuel Oil Sloshing in Partially Filled Cargo Tanker Trucks under Cornering Conditions Using Various Baffle Systems

Ethiopia imports all fuel and crude oils from abroad at high cost, and transportation of these fluids has been carried out by using various capacity of road transportation heavy-duty truck vehicle. Most tanker truck accidents happen during turning because of the fluid splashing in partially loaded tanks and of the uniqueness of the carrying liquids. This is a result of the fact that current baffle configurations are effective at reducing sloshing when braking or accelerating but ineffective at doing so when turning. Consequently, the primary goal of this thesis work is to investigate how different baffle systems affect lateral sloshing reduction. In this work, the optimal baffle configuration and its arrangements for modified oval tanks at 50% and 80% fill levels were tried, and the dynamic analysis of tanker trucks was researched. The tanker truck and baffle system are designed in CATIA V5 for the numerical analysis, and the CFD study is completed in ANSYS Fluent 2021. R2 and the dynamic analysis are carried out in ANSYS LS-DYNA to study the stability of truck. The computational simulation is carried out as a tank with eight types of baffle systems such as existing baffles (TB), TB with BMLB, UMLB, CLB, 2HLB, 2VHLB, 4HLB, and 4VHLB with similar meshing resolution, similar turbulence modeling, similar boundary conditions, and also similar solution strategies. Transverse baffles with bottom-mounted four holes longitudinal baffle with hole-varying position (4VHLB) are discovered to be the best baffle type after evaluating all baffle designs. This suggests that the quantity of sloshing is reduced as the number of holes with small diameters increases. Maximum lateral force and roll moment are reduced by the most, by 47.76% and 58.66%, respectively, at 50% fill level and by 58.08% and 22.52%, at 80% fill level. Consequently, the case tanker truck’s use of this revised design baffle will be crucial for enhancing rollover stability while cornering.

Predictive Anti-Jerk and Traction Control for V2X Connected Electric Vehicles With Central Motor and Open Differential

V2X connectivity and powertrain electrification are emerging trends in the automotive sector, which enable the implementation of new control solutions. Most of the production electric vehicles have centralized powertrain architectures consisting of a single central on-board motor, a single-speed transmission, an open differential, half-shafts, and constant velocity joints. The torsional drivetrain dynamics and wheel dynamics are influenced by the open differential, especially in split- scenarios, i.e., with different tire-road friction coefficients on the two wheels of the same axle, and are attenuated by the so-called anti-jerk controllers. Although a rather extensive literature discusses traction control formulations for individual wheel slip control, there is a knowledge gap on: a) model based traction controllers for centralized powertrains; and b) traction controllers using the preview of the expected tire-road friction condition ahead, e.g., obtained through V2X, for enhancing the wheel slip tracking performance. This study presents nonlinear model predictive control formulations for traction control and anti-jerk control in electric powertrains with central motor and open differential, and benefitting from the preview of the tire-road friction level. The simulation results in straight line and cornering conditions, obtained with an experimentally validated vehicle model, as well as the proof-of-concept experiments on an electric quadricycle prototype, highlight the benefits of the novel controllers.

Estimation of Tire-road Friction Limit with Low Lateral Excitation Requirement Using Intelligent Tire

<div class="section abstract"><div class="htmlview paragraph">Tire-road friction condition is crucial to the safety of vehicle driving. The emergence of autonomous driving makes it more important to estimate the friction limit accurately and at the lowest possible excitation. In this paper, an early detection method of tire-road friction coefficient based on pneumatic trail under cornering conditions is proposed using an intelligent tire system. The previously developed intelligent tire system is based on a triaxial accelerometer mounted on the inner liner of the tire tread. The friction estimation scheme utilizes the highly sensitive nature of the pneumatic trail to the friction coefficient even in the linear region and its approximately linear relationship with the excitation level. An indicator referred as slip degree indicating the utilization of the road friction is proposed using the information of pneumatic trail, and it is used to decide whether the excitation is sufficient to adopt the friction coefficient estimate. The friction coefficient is estimated by the ratio of the normalized lateral force and the nonlinear adaptation of the slip degree. The tire forces and pneumatic trail are estimated by neural networks. The experimental validation demonstrates that the pneumatic trail has a good potential to precisely predict the friction coefficient at a low excitation under cornering conditions.</div></div>

Study and analysis of structural steel sway bar using linear and nonlinear regression techniques

The primary goal of this project is to determine the effect of varying sway bar stiffness and the stress generated when the clamping distance of the anti-roll bar is changed. A sway bar effect on the rear suspension can only be detrimental to vehicle handling. To ensure a vehicle's desired handling characteristics, these installations should be tested under severe cornering conditions. The analysis has been done by using Beta CAE ANSA, MSC NASTRAN, and Beta CAE METAPOST software applications for generative structure analysis. This analysis is done on the basis of constant displacement but in the opposite direction since the main motive of the sway bar is achieved by twisting it. After gathering the engineering data, the prediction of bushing distance for the respective stiffness of the bar is calculated using a linear regression technique. In this study, observe the stiffness behaviour with respect to bushing position and predict the bushing distance for a target stiffness using a linear regression table.

Experimental identification of wheel-surface model parameters: various terrain conditions.

Since the wheel interaction with a certain terrain cases (asphalt, concrete) are known and well described in case of straightforward motion and non-slip and slip cornering conditions, the skid-steered wheeled vehicles case needs to be analyzed. Side-slip for various attack angle has to be investigated. The main area of interest of research that is shown in the project is energy demand calculation of skid-steered wheeled vehicles in various terrain conditions. Certain cases of all-electric vehicles with individual electric motors per wheel demand a precise assessment of longitudinal and lateral forces in order to perform the fully controlled turn. Experimental stand designed and developed by authors allows to test the wheel-surface interaction for various terrain conditions and different driving directions. Test data were acquired for dry and wet sand and granite pavement. Traction and side forces were acquired and used to identify the wheel-soil interaction model parameters for unpropelled wheel. Results in a form of time series including longitudinal and lateral forces show the relation between attack angle, load and surface conditions in terms of stick and slip phenomenon that is essential for skid-steering dynamics calculations. Measurement results are then used for calculation of longitudinal and lateral forces coefficients as a function of attack angle and vertical load. Test were performed in natural environment, thus they are affected by changeable conditions. Multiple runs are used for elimination of that influence. Described experiments are a part of the project that includes results generalization using test validated FEM model. Described work is not intended to develop new ground-tire interaction models, it is focused on numerically efficient traction effort calculation method for various conditions including passive mode—unpropelled wheel.

Analysis of Tire‐Pavement Contact Morphology Characteristics during the Virtual Track Train Maneuvering

The tire‐pavement contact morphology during the virtual track train maneuvering has an essential function in assessing vehicle performance and pavement damage. The longitudinal tread tire and viscoelastic asphalt pavement were developed based on the finite element method. Then, the tire‐pavement contact model was developed according to the Euler–Lagrange algorithm and validated. Contact area and stress distribution under uniform, braking, and cornering conditions are explored with the dynamic tire force of the virtual track train as the external load. Also, the effect factors were analyzed. The results indicate that vertical stress distribution is symmetrical along the length and width directions, and contact area is rectangular under uniform condition. Vertical and longitudinal stresses have similar distributions under braking condition, with a wide front and a narrow back along the length direction. Under cornering condition, the closer to the inside of the cornering, the larger the contact area. Vertical stress is similar to the lateral stress distribution, and the larger stress value is concentrated on the inner side of each tread. Load, tire pressure, slip rate, and slip angle have significant effects on contact morphology, while velocity has little effect. Contact area increases with the increase of load and slip rate and decreases with the increase of tire pressure and slip angle. Vertical stress increases gradually with the increase of load. Higher tire pressure makes stress distribution more concentrated. The increase in slip rate increases vertical and longitudinal stresses and gradually moves in the running direction. Vertical and lateral stresses increase with the slip angle and are mainly distributed on the inside of the turn. This research can be used to evaluate and analyze the response and damage of the virtual track train to asphalt pavement under uniform, braking, and cornering conditions. It can be used as a reference for the design and paving of asphalt pavement.

Research on Optimal Torque Control of Turning Energy Consumption for EVs with Motorized Wheels

This paper aims to explore torque optimization control issue in the turning of EV (Electric Vehicles) with motorized wheels for reducing energy consumption in this process. A three-degree-of-freedom (3-DOF) vehicle dynamics model is used to analyze the total longitudinal force of the vehicle and explain the influence of torque vectoring distribution (TVD) on turning resistance. The Genetic Algorithm-Particle Swarm Optimization Hybrid Algorithm (GA-PSO) is used to optimize the torque distribution coefficient offline. Then, a torque optimization control strategy for obtaining minimum turning energy consumption online and a torque distribution coefficient (TDC) table in different cornering conditions are proposed, with the consideration of vehicle stability and possible maximum energy-saving contribution. Furthermore, given the operation points of the in-wheel motors, a more accurate TDC table is developed, which includes motor efficiency in the optimization process. Various simulation results showed that the proposed torque optimization control strategy can reduce the energy consumption in cornering by about 4% for constant motor efficiency ideally and 19% when considering the motor efficiency changes in reality.

Analytical modeling and DEM analysis of soil–wheel interaction under cornering and skidding conditions in off-road vehicles

Soil–wheel interaction under cornering and slip conditions (SWICS) has a significant impact on the steering performance of off-road vehicles. In order to analyze the six-dimensional wheel forces in SWICS, a SWICS model based on the analytical method and the discrete element method (DEM) is developed in this paper. First, the modeling process of SWICS using the analytical method was detailed to predict the six-dimensional wheel forces in SWICS. The SWICS was then modeled using the DEM, which involved the following steps: (a) establishment of tire geometry, (b) selection of particle parameters, (c) parameter calibration, and (d) particle generation. Finally, DEM simulations were carried out for different slip angles and slip ratios under three loads, and the results were compared with those of the analytical model. The results show that the SWICS DEM model in this paper maintains a good fit with the analytical model, validating the efficiency of the DEM model and the parameter calibration method. The slip angle has a great influence on the lateral force, overturning moment, and aligning moment and a smaller impact on the normal force, drawbar pull, and rolling resistance moment. The slip ratio promotes an increase in the drawbar pull and rolling resistance moment but reduces the value of the lateral force and aligning moment. The research in this paper provides a DEM modeling approach and an analysis method for solving mechanical problems with different dimensions in SWICS, which will help improve the performance of off-road vehicles.

Investigation on linear and nonlinear dynamic equation for vehicle model in numerical simulation

With the increase in vehicles in the world today, more accidents have occurred. Therefore, more safety systems are needed for conventional vehicles. However, physical testing is dangerous and costly compared with numerical simulation. So, a good numerical simulation is especially important. In general, the vehicle dynamics equations were used in the numerical simulation. There are two types of vehicle dynamics equations that are linear and nonlinear. This paper researched which one is more practical between linear and nonlinear equations in the simulations versus real-time experiments. In this paper, the equation of motion was used to simulate the state of vehicle motion during cornering conditions in the MatLab Simulink software. The results show that the value of the linear and non-linear yaw is close to the yaw from experimental at lower speed conditions. With the speed increase, the linear yaw value will decrease and farther and farther away from experimental yaw results. Although the linear equation is relatively simple to calculate, the results of the nonlinear equations are closer to the results of real experiments. In summary, the nonlinear equation is more applicable, while the linear equation is not applicable to simulate the motion of the vehicle.

Synergy between topology optimization and additive manufacturing in the automotive field

This article purposes on developing and on re-interpreting the numerical results of a topology optimization for a structural component built via additive manufacturing. A critical appraisal of the optimization results is presented by modeling the feasible component with a holistic approach that merges structural and manufacturing requirements. The procedure is expected to provide a design guideline for similar applications of practical relevance, toward an increase of the right-first-time parts that is required to bring additive manufacturing to its full competitiveness. Topology optimization of a steering upright for a Formula SAE racing car was performed by targeting weight minimization while complying with severe structural constraints, like global and local stiffness performance. Cornering, bumping and braking vehicle conditions were considered. The optimization constraints were evaluated via finite element analysis on a reference component, where the loading conditions were retrieved from telemetry data. The reference part was manufactured by computer numerical control machining from a solid aluminum block. Spurred by the interpretation of the topology optimization predictions, a new upright geometry was designed and validated by calculating its stress field and the possible occurrence of Euler buckling. The new upright was 9% lighter than the reference component. The new geometry was analyzed according to Design for Additive Manufacturing principles to choose the orientation on the build platform and the supports’ location and geometry. The part was successfully manufactured and proved consistent with the application.

Research on intelligent vehicle trajectory tracking based on model predictive control

Intelligent vehicle trajectory tracking lateral control is the key technology to realize intelligent driving. Aiming at the problems that the existing control methods have a small effective control area and poor control effect under cornering conditions or small road adhesion coefficients, a model predictive control (MPC) algorithm is proposed for trajectory tracking control. Based on the two-degree-of-freedom vehicle model, a state space equation is established and discretized to obtain a predictive model that meets the conditions. Then, the corresponding objective function is designed based on the ideal yaw angular velocity under the optimal preview control theory, and the input-output constraints and side-slip angle constraints are designed according to the control and state quantities. The controller model is established in MATLAB / Simulink, and the road model is built in CarSim for joint simulation. Compared with CarSim’s own algorithm, the changes in side acceleration and steering wheel angle are smoother and less oscillating. The maximum lateral deviation and lateral acceleration are also smaller, and the lateral stability of the car is improved. It has better adaptability on pavement with lower adhesion coefficient, and can also maintain control stability. The real vehicle test results are consistent with the simulation results, with a maximum lateral error of 0.44m and a maximum heading angle deviation of 1.43 °. Therefore, the trajectory tracking control algorithm based on model predictive control designed in this paper has significantly improved control accuracy and stability, and can maintain control stability even when the road surface adhesion coefficient is low.

Analysis of Steering Returnability and Compensation Logic Developmet in Limit Cornering Condition

This paper describes steering returnability by analyzing forces applied to kingpin axis in limit cornering conditions. The steering returnability is related to forces applied to kingpin axis. These forces are classified by its source: Tire force and steering force. Tire force is generated from tire such as longitudinal, lateral, vertical force, and residual self-aligning torque. Steering force consists of friction force and assist force. These forces are vectorized by suspension geometry and calculated with respect to kingpin axis. The simulation results are compared with measurement data and verifies that steering returnability can be formulated by tire forces and steering forces. Using these relations, this paper proposes new steering control logics at limit driving conditions. This logic is verified by simulation model to check performance and confirmed in various test conditions for robustness.

Safety assessment of control design parameters through vehicle dynamics model

An existing vehicle dynamics model was utilized to define design parameters up to which steady state cornering conditions apply and consequently lift the restrictions of the point mass model. Aiming to assess critical safety concerns in terms of vehicle skidding, the motion of a passenger car was examined over a range of design speed values paired with control design elements from AASHTO 2011 Design Guidelines as well as certain values of poor pavement friction coefficients.Two distinct cases were investigated; the determination of the maximum attainable constant speed (termed as safe speed) at impending skid conditions as well as the case of comfortable curve negotiation where lower constant speed values were utilized. The overall objective was to define the safety margins for each examined case.From the interaction between road geometry, pavement friction and vehicle characteristics, many interesting findings are reported, where some of them are beyond the confined field of road geometry parameters; such as demanded longitudinal and lateral friction values and horse-power utilization rates. From the road geometry point of view, it was found that control alignments on steep upgrades consisting of low design speed values and combined with poor friction pavements are critical in terms of safety. Such cases should be treated very cautiously through certain actions. These actions include the adoption of acceptable arrangements for the above values regarding new alignments, posted speed management for existing but also scheduling friction improvement programmes more accurately for both cases.

Rollover threshold investigation of a heavy-duty vehicle during cornering based on multi-body dynamics

The objective of this article is to investigate the rollover threshold of a heavy-duty vehicle during cornering. Based on the multi-body dynamics theory, a high-fidelity model is established, which takes account of the chassis flexibility, the suspension nonlinear characteristics, the tire handling model, and Ackermann steering strategy. Furthermore, by the inverse fast Fourier transform method, a three-dimensional stochastic road in space domain is employed in the model to improve the accuracy. A full-size heavy-duty vehicle test was carried out to validate the model. Based on the validated model, the rollover stability and rollover threshold of the heavy-duty vehicle during cornering are investigated. Lateral acceleration, yaw rate, roll angle, and vehicle torsional deflection in different cornering conditions are analyzed. The rollover threshold is summarized by the response surface methodology for the safe cornering purpose. The result shows the practical meaning of improving transportation safety of heavy-duty vehicles and also provides useful insights for developing the rollover warning system.

Design and Optimization of Formula SAE Suspension system

In automobile industry it is essential to produce the Compact and reliable Suspension system in order to increase the vehicle performance. Also, lot of forces during cornering, acceleration and bump conditions are also applied directly during dynamic condition. This article deals with design of Formula SAE Suspension by considering various loads and their simulation on each component of the system

Finite Element Modeling of an Aircraft Tire Rolling on a Steel Drum: Experimental Investigations and Numerical Simulations

The aim of this study is to investigate the thermal evolution of an aircraft tire rolling at high velocities up to take off values. As this kind of experiment is difficult to realize on a real runway, experimental tests were realized on aircraft tires rolling on a steel drum. The rotating drum facility allows to apply variable velocities beyond the take off limits, at fixed skidding angles and loadings. The rolling conditions, vertical loading, velocity and cornering conditions were adopted to correspond to the real conditions of an aircraft tire running or skidding on a flat runway. In the experimental part, the influence of skidding angle, velocity and loading on the thermal evolution of the tire tread were investigated. The thermo-mechanical finite element analysis of a pneumatic radial tire structure was performed taking into account the hyper-viscoelastic rubber behavior, with heating mechanisms developed by the inelastic deformation and by friction. Three-dimensional finite element simulations of an aircraft tire rolling on a steel drum were carried out using Abaqus/Standard finite element solver. The comparison of the temperature distribution on the tire tread between numerical results and the experimental data shows the same overall tendencies. The good correlation between numerical and experimental data shows that numerical simulation could predict the thermal evolution of the tire in critical situations. The authors would like to mention that for confidentiality reason, certain numerical data could not be revealed.

Modeling of Contact Patch in Dual-Chamber Pneumatic Tires

ABSTRACT This study presents an investigation of the inner tire surface strain measurement by using piezoelectric polymer transducers adhered on the inner liner of the tire, acting as strain sensors in both conventional and dual-chamber tires. The piezoelectric elements generate electrical charges when strain is applied. The inner liner tire strain can be found from the generated charge. A wireless data logger was employed to measure and transmit the measured signals from the piezoelectric elements to a PC to store and display the readout signals in real time. The strain data can be used as a monitoring system to recognize tire-loading conditions (e.g., traction, braking, and cornering) in smart tire technology. Finite element simulations, using ABAQUS, were employed to estimate tire deformation patterns in both conventional and dual-chamber tires for pure rolling and steady-state cornering conditions for different inflation pressures to simulate on-road and off-road riding tire performances and to compare with the experimental results obtained from both the piezoelectric transducers and tire test rig.