Active aerodynamics can be defined as the concept of reducing drag by making real-time changes to certain devices such that it modifies the airflow around a vehicle. Using such devices also have the added advantages of improving ergonomics and performance along with aesthetics. A significant reduction in fuel consumption can also be seen when using such devices. The objective of this work is to reduce drag acting on a passenger car using the concept of active aerodynamics with grill shutters and air dams. First, analysis has been carried out on a baseline passenger car and further simulated using active grill shutters and air dams for vehicle speed ranging from 60 kmph to 120 kmph, with each active device open from 0° to 90°. The improved model obtained is then subjected to variations in yaw angle ranging from -18° to +18°. The optimized model is then validated for a scaled down prototype in a wind tunnel.
A high impetus from Government on road infrastructure development, is giving a fillip to passenger CV space. This has resulted in making the passenger CV segment lucrative enough, thereby pulling in many operators in the business. The quality of road has immensely improved over a decade, as a result of which the average speed and hence the quantum of distance covered by passenger buses has increased significantly. People are preferring to travel in buses over trains, owing to at par ticket cost, high availability, reduced travel time and also improved level of comfort. Aligned to the market need and the trend, OEM's are offering buses with capable powertrains to cater the need of speed, reduced trip time as well as a lot of attention is also being paid to tune in the comfort level for long hauls. A big chunk of passenger travel is catered by the bus operators especially during major festivals in India.
The study aims to evaluate the lateral stability of tractor-front end loader system in consideration with difficult work conditions based on various loader bucket lifting heights from ground while driving a system on transversal slopes. In the proposed method the centre of gravity of tractor-front end loader system was calculated and analysed to evaluate the transversal overturning of the system. This overturning of the system was analysed by applying mathematical equations presented in past studies and compared with the newly developed prediction model for 3 test tractors of 25 HP. The excel spreadsheet comprised of mathematical equations used to calculate the Tractor Stability Index (TSI) on transverse slope with respect to loader bucket height and payload in dynamic condition. A criterion has been defined to categorize the Tractor Stability Index (TSI) poor to excellent on a scale of 0 to 4 where <0 being the very poor, 0-2 Poor, 2-4 Good and >4 being the excellent.
Objective This paper explores the usage of Altair simulation driven optimisation process, Front Suspension hard points of a sedan Car model are optimised for specific target toe curves using MotionView, MotionSolve and HyperStudy This process gives the optimal hard point values to match the target curves without much iterations. Methodology Parametric Multibody model of the front end of sedan is built in MotionView. To Carry out optimisation HyperStudy is used where few of the suspension hard points which affect the toe curves are chosen as design variable. For the chosen Design variables upper and lower bound limits are specified. Ride, Roll and lateral force tests are performed. Optimisation is performed using HyperStudy where it iterates the suspension hard points to match the target toe curves. Each iteration response can be visualized in HyperStudy and can be compared with the target toe curve.
Title Development of a Graphical User Interface (GUI) Based Tool for Vehicle Dynamics Evaluation Authors Mr. Shubham Kedia, Dr. Divyanshu Joshi, Dr. Muthiah Saravanan Mahindra Research Valley, Mahindra & Mahindra, Chennai Objective Objective metrics for evaluation of major vehicle dynamics performance attributes i.e. ride, handling and steering are required to compare, validate and optimize dynamic behavior of vehicles. Some of these objective metrics are recommended and defined by ISO and SAE, which involve data processing, statistical analysis and complex mathematical operations on acquired data, through simulations or experimental testing. Due to the complexity of operations and volume of data, evaluation is often time consuming and tedious. Process automation using existing tools such as MS Excel, nCode, Siemens LMS, etc. includes several limitations and challenges, which make it cumbersome to implement.
OBJECTIVE Race vehicles are designed to achieve higher lateral acceleration arising at cornering conditions. A focused study on the steady state handling of the car is essential for the analysis of such conditions. The transient response analysis of the car is also equally important to achieve best driver-car relationship and to quantify handling in the range suitable for a racing car. This research aims to investigate the design parameters responsible for the transient characteristics and optimize those design parameters. This research work examines the time-based analysis of the problem to truly capture the non-linear dynamics. Apart from tires, chassis can be tuned to optimize vehicle handling and hence the response times. METHODOLOGY To start with, the system is modelled with governing parameters and simulation is carried out to set baseline configurations. Steady state and transient handling simulations run independent of each other with independent logic, coded on MATLAB.
The application in vehicle ride and handling has been mostly subjective or intuitive. There are several methods to improve vehicle stability and handling. One of the methods is suspension tuning. The objective of this work is to perform dynamical analysis of suspension by spring and damper tuning to reduce transmissibility for an all-terrain vehicle. A baseline spring rate data is used for tuning to provide better ride. The Fox air shock absorbers with progressive damping are used for testing. First the dynamics simulation is carried out by using ADAMS CAR tool. A detailed characteristic of the air shocks is obtained at various loading conditions by experimentation using test rig. Based on it, the simulation has been carried out for desired tuning parameters of spring and damper to improve stability.
Fuel lid is one of the parts which are mostly operated mechanically by the end user while filling the fuel. Therefore part design should be done in such a manner that it can be operated smoothly without any hassles. The conventional steel fuel filler doors are of two types: Three-piece type fuel filler doors also known as the dog-leg type and two-piece type fuel filler doors also known as the butterfly type. Both types of fuel filler doors have a pin that acts as a rotational hinge axis about which the fuel filler door opens and closes. Depending on the styling and shape of the side body outer, fuel lid type is decided. In the current study, dog-leg type fuel lid is considered. The factors that primarily affect the opening-closing performance are the weight of fuel lid, hinge axis, and the friction at the hinge area. The orientation of the hinge axis is derived from the profile of the side body outer panel. The fuel lid weight and hinge axis are decided in the initial design stage.
Research Objective The importance of evaluating ride comfort with high degrees of accuracy objectively and its correlation with subjective perception is increasing day by day because of the long duration of the driving experience. The complex motion of the vehicle which is the combination of heave, roll and pitch motion is responsible for causing extreme uneasiness to the driver as well as the passenger. In this paper, ride comfort evaluation is done on the highway with similar traffic conditions with the help of Vibration Dose Value Analysis, Suspension Working Space and Ride Diagram methods for two hatchbacks and its correlation with the complex motion like choppiness of the vehicle is established that will help us to enhance the driver ride experience. Methodology The ride testing is performed for two hatchbacks on a highway road with different kinds of terrain ranging from highly uneven road roughness to moderately smooth surface for a speed range of 60-100 kmph.
Objective To achieve better fuel economy and reduced carbon footprint, OEMs are reducing the sprung and unsprung mass. This translates into a reduction in stiffness which profoundly deteriorates the handling/road holding characteristics of the vehicle. To model these changes in stiffness, modifications are made to suspension roll stiffness at the front and rear. This study compares different configurations of roll stiffness and evaluates vehicle behavior using frequency response characteristics and phase change of Yaw Gain recorded. The present work associates acquired data with subjective feedback to outline the shift in vehicle balance emerging from a variation of sprung and unsprung mass ratio. Methodology To study the frequency response characteristics of the vehicle, the pulse input is chosen for this. An ideal pulse input’s Fourier transform represents constant amplitude over all the frequency ranges. By giving a single input, the system is subjected to a range of frequencies.
The present work involves Machine Learning (ML) based Multi-objective Multidisciplinary Design Optimization (MMDO) for lightweighting the automotive structures. The challenge in deployment of MMDO algorithms in solving real-world automotive structural design problems is the enormous time involved in solving full vehicle finite element models that involve large number of design variables and multiple performance constraints pertaining to vehicle dynamics, durability, crash and NVH domains. With the availability of powerful workstations and using the advanced Computer Aided Engineering (CAE) tools, it has become possible to generate huge sets of simulation data pertaining to multiple domains.
Tyre Traction Trailer is a device designed to find the Peak Brake co-efficient of C2 and C3 tyre as per ECE R117. The trailer is towed by the truck and is braked suddenly to evaluate braking co-efficient of specimen tyre. It is a single wheel trailer equipped with load cell to capture tire loads (Normal and longitudinal)while braking. Traction Trailer is modelled in MSC Adams and rigid body simulation is carried out for static stability of the system. Dynamic simulations were performed to understand locking of wheels during braking. Body frame was further modelled as flex body to perform structural analysis of the frame. The paper contains stress and deformation plots of trailer Structure under various loading conditions, change in Centre of gravity, weight transfer and forces on springs during braking and cornering, plots of tractive and normal load on tyre during braking.
The application in ride and handling development has been mostly subjective or intuitive. Suspension settings are based on the opinions of experts. The product of this research will enable to quantify the performance of a suspension in terms of its ability to minimize the transmission of road irregularities to the chassis and achieve good mechanical grip with the road surface. This work presents a dynamical analysis of the transmissibility of an off-road vehicle suspension, developed in VIT Vellore for Baja SAE India competition. A baseline spring rates curve for ride is developed to provide a solid foundation to tune from. The shock absorbers used for testing are Fox Float Evol R air shock absorbers with progressive damping. A thorough data acquisition of the force curves for shocks from a test rig is done. A detailed characteristic of the air shocks is obtained at various loading conditions. The basic damping curve is modified towards the desired ideal nature with the data obtained.
In the current commercial vehicles market, ride-comfort and handling are crucial parameters for the customer and end user. There are various aspects which determine the vehicle behaviour. One of aspects is the structural rigidity of the vehicle, which has its own effect on vehicle dynamics. To meet the required stiffness of the main structural component of the vehicle i.e. chassis frame, FEA analysis has to be done in current methodology. The number of iterations have to be done to build an appropriate model with low weight, which can meet the design requirements. At first, conceptual design mock-up unit is to be developed then FEA (CAE) analysis to be done on it. If any design criteria are not met, then this cycle repeats again until it fulfils the required stiffness. Today, the direct stiffness procedure is the basic principle of almost every FEA software package.
Objective: The Objective of the research is to detect drop in level of pressure in the wheel with respect to nominal pressure using data obtained from speed sensors. The research discusses the standard procedure of experimentation to obtain data which eventually used to produce results. This procedure is taken from principles Design of Experiments. Statistical tools are used to analyze and give determining factors for pressure variation. Methodology: To study idea, we made use of two-wheeler platform and collected data of wheel speed sensors on both wheels. The idea is when there is any change in tire pressure the radius of the wheel also changes and usually this relation is direct. Hence, change in tire pressure changes the angular velocity of the wheel. In this approach wheel speed sensors are used to measure the angular speed for standard and reduced pressure conditions.
Abstract The electrification of conventional internal combustion engine vehicle is a need of today’s advanced world to reduce the dependency of the transportation sector on the oil and gases. It can be achieved by replacing the engine by an electric motor which is powerful enough to provide required torque. The important requirement for a vehicle to drive in the hilly region with steep corners is proper torque distribution on each wheel which is taken care by the differential system. When the friction between road and wheels are different from left to right, then the wheel with low friction contact will lose its traction on the road. These situations are unfavorable for driving a vehicle on off-road and extrema conditions like driving in muddy roads or on the ice. These problems can be overcome by providing individual power supply system to separate wheels.
India has emerged as the world’s biggest market for Two-wheelers and Four-wheeler. Besides rising incomes and growing infrastructure in all areas, one big reason for the spurt in sales has been ease of zipping in and out of chaotic city traffic along with road irregularities and potholes. Furthermore, the efficiency increase in the Shock absorber within the vehicle have high demands to use of regenerative solutions, in which e-system can be employed as to recover part of the energy otherwise dissipated in form of heat. The Smart e-Shock can charge battery and illuminate accessories of vehicle. Also, the e-shock can provide the various damping characteristics by changing the Electric load on to it to make system as Semi-Active Suspension. This Smart e-Shock system is based on unique and patented concept of constraining the reciprocating motion of the shock absorber in to a single sense of rotation of e-system and the energy is recuperated and given to the battery from the e-system.
In current automobile market, due to the need of meeting future CO2 limits and emission standards, demand for hybrid systems is on the rise. In general, the requirements of modern automobile architecture demands modular chassis structure to develop vehicle variants using minimum platforms. The multi-link modular suspension system provides ideal solution to achieve these targets. To match ideal stiffness characteristics of system with minimum weight, aluminum links are proving a good alternative to conventional steel forged or stamped linkages. Design of current 2-point link (Upper Control Arm) is based on elasto-kinematic model developed using standard load cases from multi body dynamics. CAD system used is CATIA V5 to design upper control arm for rear suspension. This arm connects steering knuckle & rear sub frame. For Finite Element Analysis we used Hyperworks CAE tool to analyze design under all load cased & further optimization is done to resolve highly stressed zones.
This seminar will present an introduction to Vehicle Dynamics from a vehicle system perspective. The theory and applications are associated with the interaction and performance balance between the powertrain, brakes, steering, suspensions and wheel and tire vehicle subsystems. The role that vehicle dynamics can and should play in effective automotive chassis development and the information and technology flow from vehicle system to subsystem to piece-part is integrated into the presentation. Governing equations of motion are developed and solved for both steady and transient conditions.