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Technical Paper

Optimizing Steering Column Layout and UJ Phase Angle to Enhance Vehicle Dynamics Performance

2019-02-05
2019-01-5010
Vehicle dynamics is one of the most important vehicle attributes. It is classified into three domains, the longitudinal, vertical, and lateral dynamics. This paper focuses on optimizing the lateral vehicle dynamics which is driven by the straight ahead controllability and cornering controllability of the vehicle. One of the important parameters that dictates these sub-attributes is the steering ratio. Therefore, designing the right steering ratio is critical to meet the vehicle “specific” targets. Significant amount of work has been done by many researchers on variable steering ratio by implementing variable gear ratio (VGR) rack, active steering, and steer-by-wire systems. This paper discusses the methodology and considerations to optimize the steering ratio for a constant gear ratio rack by optimizing the steering column layout, viz., orientation and the phase angle in universal joints.
Technical Paper

Design, Simulation & Optimization of an Air Intake System to Reduce Induction Noise

2019-01-09
2019-26-0191
Air intake system (AIS) plays a major role in reducing the noise level in passenger car compartment, which has become an important requirement due to increasing customer expectation for better in cab noise. The ideal air intake system design should have minimum possible noise at snorkel entry point which ultimately contributes in cabin noise. There are different techniques that are implemented for an air intake system noise reduction e.g. choosing proper location of air entry suction point in engine bay compartment, suitable design for air filter box (volume), duct designs etc. Further design improvement are possible with an addition of tuned resonators in the system. An addition of resonator have major effect seen in reducing air induction noise and to meet target Sound Pressure Levels (SPL). But at the same time, selecting the correct type of resonator, its position & volume, frequency/s band at which resonator is tuned are important parameters.
Technical Paper

Virtual Road Torque Data Collection

2019-01-09
2019-26-0289
The traditional method of collecting the Road Torque Data of a vehicle is by instrumenting and running the vehicle on different road terrains. Every time, physical testing becomes tedious & most challenging task due to unavailability of unit under tests, kind of resource required and so on. However, in view of response to the fast emerging technology & limit less competition, it has become mandatory to develop & launch products in market within no time. In recent times, there is increased demand for physical road torque data measurements for a vehicle program based on its application and different powertrain configurations, which clearly shows that unless we front load the data to design it is practically impossible to meet the deadlines. Each of these measurements cost and consumes valuable resources of the company in collecting and analyzing the data.
Technical Paper

Adhesive Failure Prediction in Crash Simulations

2019-01-09
2019-26-0297
Structural adhesive is a good alternative to provide required strength at joinery of similar and dissimilar materials. Adhesive joinery plays a critical role to maintain structural integrity during vehicle crash scenario. Robust adhesive failure definitions are critical for accurate predictions of structural performance in crash Computer Aided Engineering (CAE) simulations. In this paper, structural adhesive material characterization challenges like comprehensive In-house testing and CAE correlation aspects are discussed. Considering the crash loading complexity, test plan is devised for identification of strength and failure characteristics at 0°, 45°, 75°, 90°, and Peel loading conditions. Coupon level test samples were prepared with high temperature curing of structural adhesive along with metal panels. Test fixtures were prepared to carryout testing using Instron VHS machine under quasi-static and dynamic loading.
Technical Paper

Development of Hydrogen Fuel Cell Bus Technology for Urban Transport in India

2019-01-09
2019-26-0092
Polymer Electrolyte Membrane Fuel Cell (PEMFC) technology is considered for automotive applications due to rapid start up, energy efficiency, high power density and less maintenance. In line with National Hydrogen Energy Roadmap of Govt. of India that aims to develop and demonstrate hydrogen powered IC engine and fuel cell based vehicle. TATA Motors Ltd. has designed, developed and successfully demonstrated “Low Floor Hydrogen Fuel Cell Bus” which comprises of integrated fuel cell power system, hydrogen storage and dispensing system. The fuel cell power system, converts the stored chemical energy in the hydrogen to DC electrical energy. The power generated is regulated and used for powering the traction motor. The development of fuel cell bus consists of five stages: Powertrain sizing as per vehicle performance targets, fuel cell stack selection and balance of plant design and development, bus integration, hydrogen refueling infrastructure creation and testing of fuel cell bus.
Technical Paper

Optimization of Air Intake System and Exhaust System for Better Performance of Turbocharged Gasoline Engine

2018-04-03
2018-01-1424
Gasoline engines with Multi point fuel injection (MPFI) technology are being developed with naturally aspirated and/or turbocharged engines. Wherein a MPFI and turbo charged combination engines have certain challenges during development stages. One of the important challenge is design of air intake and exhaust system. With MPFI turbocharged engine combination, the under bonnet heat management is crucial task for drivability. The heat management of air intake plays a vital role in drivability part therefore a design layout of air intake path is an important aspect. Drivability can be categorized as low end, mid-range and top end drivability. Turbocharged MPFI engines have a typical phenomenon of ‘Lag in response’ in the low-end region. This ‘Lag in response’ phenomenon at low-end drivability region can be overcome through optimization of air intake system and optimization of exhaust back pressure.
Technical Paper

A Feedback and Feedforward Control Algorithm for a Manual Transmission Vehicle Simulation Model

2018-04-03
2018-01-1356
Authors were challenged with a task of developing a full vehicle simulation model, with a target to simulate the electrical system performance and perform digital tests like Battery Charge Balance, in addition to the fuel efficiency estimation. A vehicle is a complicated problem or domain to model, due to the complexities of subsystems. Even more difficult task is to have a control algorithm which controls the vehicle model with the required control signals to follow the test specification. Particularly, simulating the control of a vehicle with a manual transmission is complicated due to many associated control signals (Throttle, Brake and Clutch) and interruptions like gear changes. In this paper, the development of a full vehicle model aimed at the assessment of electrical system performance of the vehicle is discussed in brief.
Technical Paper

Derivation of Test Schedule for Clutch Using Road Load Data Analysis and Energy Dissipation as Basis

2018-04-03
2018-01-0404
During every clutch engagement energy is dissipated in clutch assembly because of relative slippage of clutch disc w.r.t. flywheel and pressure plate. Energy dissipated in clutch is governed by many design parameters like driveline configuration of the vehicle vis-a-vis vehicle mass, and operational parameters like road conditions, traffic conditions. Clutch burning failure, which is the major failure mode of clutch assembly, is governed by energy dissipation phenomenon during clutch engagement. Clutch undergoes different duty cycles during usage in city traffic, highways or hilly regions during its lifetime. A test schedule was derived using energy dissipated during every clutch engagement event as a base and using road load data collected on the vehicle. Road load data was collected in different road mix conditions comprised of city traffic, highway, hilly region, rough road for few hundred kilometers.
Technical Paper

An Engine Stop Start System with Driver Behavior Learning and Adaption for Improving the User Experience

2018-04-03
2018-01-0609
Engine Stop/Start System (ESS) promises to reduce greenhouse emissions and improve fuel economy of vehicles. Previous work of the Authors was concentrated on bridging the gap of improvement in fuel economy promised by ESS under standard laboratory conditions and actual driving conditions. Findings from the practical studies lead to a conclusion that ESS is not so popular among the customers, due to the complexities of the system operation and poor integration of the system design with the driver behavior. In addition, due to various functional safety requirements, and traffic conditions, actual benefits of ESS are reduced. A modified control algorithm was proposed and proven for the local driving conditions in India. The ways in which a given driver behaves on the controls of the vehicles like Clutch and Brake Pedals, Gear Shift Lever were not uniform across the demography of study and varied significantly.
Journal Article

Study of Frequency Characteristics of Vehicle Motions for the Derivation of Inherent Jerk

2016-04-05
2016-01-1681
Jerk in a vehicle is a feel of user which appears due to sudden acceleration changes. The amplitude and frequency components of the jerk defines quality of an engine or an AMT calibration tuning. Traditional jerk evaluation methods use amplitude (peak) of the jerk as a performance index and its frequencies are either used as weighing factor with amplitude or not taken into account. A method is proposed in this paper to quantify and differentiate the non-acceptable level of jerk which is perceivable to human body. Jerk is obtained by differentiating the acceleration data which contains the frequencies in the lower to higher range. Differentiation of such signal causes an amplification of undesired noise in both analog and digital circuits. This results in significant loss or disturbances in the useful data.
Technical Paper

A DFSS Approach to Design Cooling System of Small Passenger Car Having Rear Engine and Front Mounted Radiator

2016-04-05
2016-01-0657
DFSS is a disciplined problem prevention approach which helps in achieving the most optimum design solution and provides improved and cost effective quality products. This paper presents the implementation of DFSS method to design a distinctive cooling system where engine is mounted in the rear and radiator is mounted in the front of the car. In automobile design, a rear-engine design layout places the engine at the rear of the vehicle. This layout is mainly found in small, entry level cars and light commercial vehicles chosen for three reasons - packaging, traction, and ease of manufacturing. In conventional Passenger cars, a radiator is located close to the engine for simple packaging and efficient thermal management. This paper is about designing a distinctive cooling system of a car having rear mounted engine and front mounted radiator.
Technical Paper

Methodology Development to Accurately Predict Aerodynamic Drag and Lift for Passenger Vehicles Using CFD.

2016-04-05
2016-01-1600
Important vehicle performance parameters such as, fuel economy and high speed stability are directly influenced by its aerodynamic drag and lift. Wind tunnel testing to asses these parameters requires heavy investment especially when test wind tunnel is not available in the country where vehicle development center is present. Hence to save cost and to compress development time, it is essential to asses and optimize parameters of a vehicle in very early stages of development. Using numerical flow simulations optimization runs can be carried out digitally. Industry demands prediction of aerodynamic drag and lift coefficients (CD,CL) within an accuracy of a few counts, consuming minimal HPC resources and in a short turnaround time. Different OEMs deploy different testing methods and different softwares for numerical simulations.
Technical Paper

An Effort to Build Mathematical Model using Time Series Analysis to Aid Steering Auto-Correction in Heavy Commercial Vehicle during High Speed Braking

2015-09-29
2015-01-2763
Steering pull during high speed braking of heavy commercial vehicles possesses a potential danger to the occupants. Even with negligible wheel-to-wheel brake torque variation, steering pull during the high speed braking has been observed. If the steering pull (i.e. steering rotation) is forcibly held at zero degree during high speed braking, the phenomena called axle twist, wheel turn and shock absorber deflection arise. In this work the data have been collected on the mentioned measures with an intention to develop a mathematical model which uses real time data, coming from feedback mechanism to predict the values of the measures in coming moments in order to aid steering system to ‘auto-correct’. Driven by the intention, ‘Time Series Analysis’, a well-known statistical methodology, has been explored to see how suitable it is in building the kind of model.
Technical Paper

Spot Weld Failure Prediction in Safety Simulations Using MAT-240 Material Model in LS-DYNA

2015-01-14
2015-26-0165
Spot welding is the primary joining method used in automobiles. Spot-weld plays a major role to maintain vehicle structural integrity during impact tests. Robust spot weld failure definitions is critical for accurate predictions of structural performance in safety simulations. Spot welds have a complex metallurgical structure, mainly consisting of fusion and heat affected zones. For accurate material property definitions in simulation models, huge number of inputs from test data is required. Multiple tests, using different spot weld joinery configurations, have to be conducted. In order to accurately represent the spot-weld behavior in CAE, detailed modeling is required using fine mesh. The current challenge in spot-weld failure assessment is developing a methodology having a better trade-off between prediction accuracy, testing efforts and computation time. In view of the above, cohesive zone models have been found to be very effective and accurate.
Technical Paper

Approach to Control the in Cab Noise without Affecting Passenger Comfort in AC Midi Buses

2015-01-14
2015-26-0125
This paper discusses various fruitful iterations / experiments performed to reduce air flow induced noise without compromising on total air flow requirement for thermal comfort and ways to avoid heat ingress inside the bus. Also the paper discusses the devised process for noise reduction through front loading of computer aided engineering and computational fluid dynamics analysis. Air conditioning buses in light commercial vehicle (LCV) segment is growing market in India, especially for applications like staff pick-up and drop, school applications and private fleet owners. The air-conditioning system is typically mounted on bus roof top and located laterally and longitudinally at center. It is an easiest and most feasible way to package air conditioning system to cater the large passenger space (32 to 40 seats) with the conditioned air. This makes air conditioning duct design simple and commercially viable.
Technical Paper

High Fidelity Modeling and HIL Porting of a Hybrid Electric Car Development

2015-01-14
2015-26-0011
A hybrid electric powertrain being a complex system requires analysis of all its subsystems to optimally utilize, size components for performance evaluation and control strategy development. An integrated high fidelity model of these can lower development costs, time and achieve the targeted performance while allowing for early redefinition of the system. A high fidelity model of a sedan car featuring chassis with longitudinal and lateral dynamics, suspension with joints, tires calculating longitudinal & lateral forces during vehicle motion, Engine model with combustion & dynamics of reciprocating and rotating components, Electric motors, Battery system, and gearbox with synchronizers and friction components was developed. Powertrain components were interconnected using 3D rotational flanges. Weight distribution was accomplished by appropriately locating various powertrain components using 3D supporting mounts, which help to study the mount forces as well.
Technical Paper

Mathematical Model to Evaluate and Optimize the Dynamic Performance of Pneumatic Brake System

2015-01-14
2015-26-0082
Pneumatic brake system is widely used in heavy truck, medium and heavy buses for its great superiority and braking performance over other brake systems. Pneumatic brake system consists of various valves such as Dual Brake Valve (DBV), Quick release Valve (QRV), Relay Valve (RV), Brake chambers. Dynamics of each valve is playing a crucial role in overall dynamic performance of the braking system. However, it is very difficult to find the contribution of each valve and pipe diameters in overall braking performance. Hence, it is very difficult to arrive a best combination for targeted braking performance as it is not possible to evaluate all combination on the actual vehicle. Hence, it is very important to have a mathematical model to optimize and evaluate the overall braking performance in early design phase. The present study is focusing on the mathematical model of a pneumatic brake circuit.
Technical Paper

Parametric Study of Hub Cum Brake Drum for Optimum Design Performance

2015-01-14
2015-26-0079
Brake drum is an important component in automotive, which is a link between axle and wheel. It performance is of utmost importance as it is related to the safety of the car as well to the passengers. Many design parameters are taken into consideration while designing the brake drum. The sensitivity of these parameters is studied for optimum design of brake drum. The critical parameters in terms of reliability, safety & durability could be the cross section, thickness of hub, interference & surface roughness between bearing and hub, wheel loading, heat generation on drum, manufacturing and assembly process. The brake drum design is derived by considering these parameters. Hence the sensitivity of these parameters is studied both virtually & physically, in detail. The optimum value of each parameter could be chosen complying each other's values.
Technical Paper

Shock Tube Simulation in LS-DYNA for Material Failure Characterization

2014-04-01
2014-01-0937
Shock tube is used to simulate blast loading conditions on materials for studying the failure behavior of different materials under blast pressures on smaller scale. This paper describes CAE method developed for simulating shock tube experiment in LS-DYNA3D environment. The objective of shock tube simulation is to characterize material failure parameters so as to predict risk of material failure in full vehicle blast simulations while developing vehicle for blast protection applications. The paper describes modeling of shock wave and its interaction with test specimen in shock tube environment. Arbitrary Lagrangian-Eulerian (ALE) techniques are applied to simulate shock tube experiment in LS-DYNA3D and simulation predictions are compared with experimental test data. CAE correlation studies were carried out with respect to incident and reflected pressures in shock tube, deformation and plastic strains on test specimen, shock wave velocity etc.
Technical Paper

A Novel Approach for Diagnostics, End of Line and System Performance Checks for Micro Hybrid Battery Management Systems

2014-04-01
2014-01-0291
Micro Hybrid Systems are a premier approach for improving fuel efficiency and reducing emissions, by improving the efficiency of electrical energy generation, storage, distribution and consumption, yet with lower costs associated with development and implementation. However, significant efforts are required while implementing micro hybrid systems, arising out of components like Intelligent Battery Sensor (IBS). IBS provides battery measurements and battery status, and in addition mission critical diagnostic data on a communication line to micro hybrid controller. However, this set of data from IBS is not available instantly after its initialization, as it enters into a lengthy learning phase, where it learns the battery parameters, before it gives the required data on the communication line. This learning period spans from 3 to 8 hours, until the IBS is fully functional and is capable of supporting the system functionalities.
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