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Technical Paper

Simulations Based Approach for Vehicle Idle NVH Optimization at Early Stage of Product Development

2011-05-17
2011-01-1591
The noise and vibration performance of diesel fueled automotives is critical for overall customer comfort. The stationary vehicle with engine running idle (Vehicle Idle) is a very common operating condition in city driving cycle. Hence it is most common comfort assessment criteria for diesel vehicles. Simulations and optimization of it in an early stage of product development cycle is priority for all OEMs. In vehicle idle condition, powertrain is the only major source of Noise and Vibrations. The key to First Time Right Idle NVH simulations and optimization remains being able to optimize all Transfer paths, from powertrain mounts to Driver Ear. This Paper talks about the approach established for simulations and optimization of powertrain forces entering in to frame by optimizing powertrain mount hard points and stiffness. Powertrain forces optimized through set process are further used to predict the vehicle passenger compartment noise and steering vibrations.
Technical Paper

Investing Factors Affecting Door Slam Noise of SUV and Improved Performance by DFSS Approach

2011-05-17
2011-01-1595
Recent development in automobile industries has seen increased customer attention for good door slamming noise. One of the constituent which plays major role in building brand image of vehicle in terms of NVH performance is door slam noise quality. Hence it is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to achieve specific sound target in order to ensure the door closing noise quality, NVH engineers needed to look at contributions from different door subsystems. The use of statistical tools like Six Sigma can further help them to ensure the consistency in results. This paper explains the systematic approach used to characterize different element of door which contributes to the overall door slam noise quality through QFD (Quality Function Deployment) and contribution analysis. The different mechanisms contributing to door slam noise were studied.
Technical Paper

Evaluation of Intercooler Efficiency as a Technique for Reducing Diesel Engine Emissions

2011-04-12
2011-01-1133
As the emission targets are getting tighter, efforts are made to improve the emission by all possible means. This work emphasis the potential of intercooler to reduce exhaust gas emissions (CO, HC, NOx and PM). A detailed analysis of experimental results on emissions is presented. The effect of intercooler efficiency on emissions is explained. A multi-utility vehicle equipped with common rail diesel engine was tested in NEDC cycle in chassis dynamometer. Ideally the vehicle emission lab should replicate a flat straight road condition & natural airflow. To obtain the airflow a variable velocity fan is used. The velocity of air emerging from the fan and relative position of the fan with vehicle has a significant role in intercooler efficiency and hence on emissions. This work explains the exercise carried out to correlate the intercooler efficiency and exhaust emissions with fan position and velocity.
Technical Paper

Design of a Single Rail Internal Gear Shift System for a 5 Speed Manual Transmission

2013-04-08
2013-01-1771
This paper presents the detailed design of a Single Rail Internal Gear Shift System for a 5-speed manual transmission of a load carrier vehicle. Gear shifting in manual transmissions is achieved by actuating a synchronizer sleeve and engaging it with the required gear. Actuation of synchronizer sleeves is effected by gear shift forks which are supported in the transmission by a rail/shaft. Conventional 5-speed transmissions use Multi Rail Gear shift systems, wherein each of the forks viz. Fork 1-2, Fork3-4 & Fork 5th, for actuating the synchronizer sleeves, are supported by and fixed to individual rails. This paper presents the design of a Single Rail Gear shift system, wherein all the gear shift forks will be supported on a common rail/shaft, thus making the entire system compact and reducing the system weight. The Single Rail, in the proposed design, apart from supporting the three forks, also serves to actuate the Reverse Gear, which is of sliding mesh type in this case.
Technical Paper

Functional Safety - Progressing Towards Safer Mobility

2013-11-27
2013-01-2841
Increasing complexity in E/E architecture poses several challenges in developing comfortable, clean and safe cars. This mandates robust processes to mitigate potential hazards due to malfunction of electronic systems throughout the product life cycle. With the advent of ISO 26262 [1] which provides guidelines for developing safe cars, the process is getting standardized towards safer mobility. In this paper, the functional safety process is briefly covered and a case study of Hazard Analysis and Risk Assessment for specific E/E system is presented. An in-house tool developed for functional safety process and management is covered.
Technical Paper

Experimental Analysis of Lead Acid Batteries for Estimating State of Charge and State of Health

2013-11-27
2013-01-2742
Batteries have become increasingly important in automotives with increase in vehicle electrical loads. Therefore the reliability of battery is a critical issue in automotive applications. It has been noticed that most batteries have limited cycle durability, that is, the total capacity drops when a battery is charged and discharged for a number of cycles. If a battery is too weak to offer sufficient energy, it should be replaced at the right time. But current problem is that there is no reliable method to quantify the capacity loss and to estimate the remaining capacity of battery. Complete discharge, which is the only way of capacity estimation, which will effect the battery plates therefore it cannot be used too frequently. This paper summarizes the experimental work in the development of the battery status estimation algorithm.
Technical Paper

Study of Optimal Magnification for Retained Austenite Evaluation in Low carbon Case Hardening steel Using Metallurgical Microscopy

2014-04-01
2014-01-1017
This study on optimum magnification at which Retained austenite to be evaluated by comparing the difference in determining the retained austenite in low carbon carburizing alloy steel using the optical metallurgical micrographic method and X-ray diffraction method. The retained austenite phase will be in surface and color is white in nature also its presented in between the martensite needles. It can be distinguished as separate micro-constituents by using image analyzing software. In another method the RA measurements were carried out on the surface by PROTO iXRD Retained austenite measuring system using Cr K radiation. The (211) and (200) reflections of Martensite and (220) and (200) reflections of Austenite were made for this estimation. However, the calculated values of retained austenite by metallurgical microscope in different magnifications are not identical.
Technical Paper

Servomotor Controlled Standard Automated Manual Transmission for Rapid Smooth Shifts

2013-10-14
2013-01-2605
Present day AMT unit uses two high pressure hydraulically operated pistons for select & shift operations which make the unit weigh around 8kg. Besides this it also makes the unit more complex & unreliable with a lot of torque interruption. The use of electrical servo motors steps in here as a better alternative as it provides a more precise and smoother shift. To test this we used a 5-MT Transmission. For the selection, a precise 14.5 degree of twisting was required which was easily achieved by the servo motor. Further, shift of 10.5mm could be made possible by using the motor to shift the rack using a pinion on the shaft. This system then essentially eliminates the whole hydraulic circuit, the housing of actuator pack & power pack making it a simpler unit all together. Thus, it offers an uninterrupted torque path from the engine to vehicle which allows for a seamless gearshift. This seminal paper provides an introduction to the technology together.
Technical Paper

Suspension Strain Correlation Using Flex Bodies in MBD

2014-04-01
2014-01-0763
Automotive Suspension is one of the critical system in load transfer from road to Chassis or BIW. Using flex bodies in Multi body simulations helps to extract dynamic strain variation. This paper highlights how the MBD and FE integration helped for accurate strain prediction on suspension components. Overall method was validated through testing. Good strain correlation was observed in dynamic strains of constant amplitude in different loading conditions. Combination of different direction loading was also tested and correlated. Method developed can be used in the initial phase of the vehicle development program for suspension strength evaluation. Suspension is one of the important system in vehicle which is subjected to very high loading in all the directions. To predict the dynamic stresses coming on the suspension system due to transient loads, faster and accurate method is required. To accelerate the suspension design process it become necessary to get good accuracy in the results.
Technical Paper

A Systematic Approach for Weight Reduction of BIW Panels through Optimization

2010-04-12
2010-01-0389
This paper describes application of Design of Experiments (DOE) technique and optimization for mass reduction of a Sports utility vehicle (SUV) body in white (BIW). Thickness of the body panels is taken as design variable for the study. The BIW global torsion, bending and front end modes are key indicators of the stiffness and mass of the structure. By considering the global modes the structural strength of the vehicle also gets accounted, since the vehicle is subjected to bending and twisting moments during proving ground test. The DOE is setup in a virtual environment and the results for different configurations are obtained through simulations. The results obtained from the DOE exercise are used to check the sensitivity of the panels. The panels are selected for mass reduction based on the analysis of the results. This final configuration is further evaluated for determining the stiffness and strength of the BIW.
Technical Paper

Design Strategies for Meeting ECE R14 Safety Test for Light Commercial Vehicle

2010-10-05
2010-01-2017
The ECE R-14, AIS015 safety standard specifies the requirements of the safety belt anchorages namely, minimum numbers, their locations, static strength to reduce the possibility of their failure during accidental crashes for effective occupant restraint and the test procedures. This standard applies to the anchorages of safety belts for adult occupants of forward facing or rearward facing seats in vehicles of categories M and N. ECE R14 ensures the passenger safety during sudden acceleration/retardation and accidents. Early simulations revealed some structural short falls that demanded cabin improvements in order to fulfill regulation requirements for the seal belt anchorage test. This paper describes the innovative design modifications done to meet the seat belt anchorage test. Good correlation with the test is achieved in terms of deformations. These simulation methods helped in reducing the number of intermediate physical tests during the design process.
Technical Paper

Study of Intake and Exhaust System Acoustic Performance Refinement with the Help of Vibro-Acoustic Analysis Tool

2010-06-09
2010-01-1427
Increase in customer's awareness for better vehicle NVH has prompted automobile industry to address NVH issues more seriously. Among other critical vehicle systems for NVH, Air Intake and Exhaust Systems play an important role in terms of passenger compartment noise, sound quality and vehicle pass-by noise. Hence proper design & development of these systems is imperative to reduce their contribution in overall vehicle NVH. This needs to be achieved within constraints of meeting other functional requirements such as emissions and engine performance. The design parameters one needs to look at while developing the intake and exhaust system are mainly the acoustic transmission loss, structural noise radiations from the surfaces and structural isolation between body and these systems. This paper demonstrates the use of FEM approach for Vibro-Acoustic Analysis as a practical means for design of intake and exhaust system in terms of high transmission loss.
Technical Paper

Powertrain Noise & Sound Quality Refinement for New Generation Common Rail Engines

2010-06-09
2010-01-1414
Noise & sound quality has gained equal importance as that of emissions and crash safety of the vehicles. With increased engine power to weight ratio, the challenges for NVH engineers has increased multifold. Passenger compartment comfort levels are getting affected largely due to lighter and powerful engines. Same time, there is pressure to reduce overall vehicle weight and cost. This impose constraints to NVH engineer in designing the body structure and sound package to reduce the effect of powertrain forces and airborne noise on passenger compartment. In addition to weight constraints, there is trend emerging to use two & three cylinder engines which need to perform on par with four cylinder engines. This has shown adverse effect on vehicle NVH performance due to wider low frequency unbalance forces.
Technical Paper

Derivation of Extreme Static Durability Load Cases for FEA Based Vehicle Strength Evaluation

2011-09-13
2011-01-2174
Validation of vehicle structure by use of finite element analysis is at the core of reduction of product development time. In the early phase of validation it is required to evaluate the strength of the vehicle structure to account for the loading during physical validation and service loading. In service the vehicle is subjected to variable loads. These act upon the components that originate from road roughness, maneuvers and power train loads. All systems in the vehicle represent more or less complicated elastic structures subjected to time varying loads. A time domain dynamic assessment of the vehicle structure is time consuming and expensive. Also in the early phase of design wherein several design iterations need to be carried out for design validation, it is practically impossible to conduct a dynamic analysis and fatigue life assessment. Extreme static load cases are traditionally being used for this process.
Technical Paper

Gear Shift Fork Stiffness Optimisation

2011-09-13
2011-01-2235
This paper presents a simulation of the stiffness of the shift fork of a manual transmission using contact pattern analysis and optistrut. All the subsystem (i.e. synchronizer and the shift system component) are constrained to optimize the shift fork stiffness. A-5-speed manual transmission is used as an example to illustrate the simulation, co-relation and validation of the optimization of the gear shift fork stiffness. The shift system was modeled in the software to collate the synchronization force, shift system gap etc with the constraint on the shift fork. It is constrained by the synchronizer sleeve and the fork mounting on the gear shift rail. The synchronizer force is then applied on the gear shift fork pads which are translated to the synchronizer sleeve. It has a number of pads which come into contact at different occasion of the synchronization because of the varying stiffness of the fork.
Technical Paper

Turbocharging a Small Two Cylinder DI Diesel Engine - Experiences in Improving the Power, Low End Torque and Specific Fuel Consumption

2011-09-11
2011-24-0133
Turbocharged common rail direct injection engines offer multiple benefits compared to their naturally aspirated counterparts by allowing for a significant increase in the power and torque output, while simultaneously improving the specific fuel consumption and smoke. They also make it possible for the engine to operate at a leaner air/fuel mixture ratio, thereby reducing particulate matter emission and permitting higher EGR flow rates. In the present work, a two cylinder, naturally aspirated common rail injected engine for use on a load carrier platform has been fitted with a turbocharger for improving the power and torque output, so that the engine can be used in a vehicle with a higher kerb weight. The basic architecture and hardware remain unchanged between the naturally aspirated and turbocharged versions. A fixed geometry, waste gated turbocharger with intercooling is used.
Technical Paper

Hybrid Oil Sump for CI Engine

2011-09-11
2011-24-0135
Recently fuel economy and stringent emission norms are the ever growing concern in automotive global scenario. So, automotive engineers are constantly seeking new cost effective methodologies and techniques to achieve considerable weight reduction and improved performance. Nowadays Automotive OEMs are using Aluminum Oil sump (which is a structured part of an engine and supports considerable amount of transmission housing weight) for better emission, reducing the engine height, engine weight and NVH levels. Our present work reveals the concept of ‘Hybrid oil sump’ which made by sheet metal and aluminum in such a way that weight and cost reduced by 20% and 30 % respectively, without compromising NVH and strength properties. Exactly it deals the iteration part of design to arrive the optimum model, various structural modifications since it carries considerable amount of weight of transmission.
Technical Paper

Dynamic Correlation and Optimization of an SUV Rear Bumper Structure

2010-04-12
2010-01-0501
Structural durability of different components and systems for a Utility Vehicle is critical to design, due to severe customer usage in rural zones and off road driving conditions. Physical validation of new component designs is time consuming, costly and iterative. Also, this process does not ensure an optimized structure. Through virtual validation it is possible in the initial phase of design to validate the structure and optimize the design. The core of a virtual validation process is to obtain accurate correlation which can replace developmental laboratory testing. Hence, only a confirmatory test can be carried out. This enables design optimization based on simulations. This paper presents the systematic approach used for optimization of SUV rear bumper and bumper mounting structure. Dynamic correlation is obtained for bumper structure subjected to the vibration levels as mapped from the proving ground test. The objective of new bumper development is for value engineering.
Technical Paper

Correlation of Test with CAE of Dynamic Strains on Transmission Housing for 4WD Automotive Powertrain

2010-04-12
2010-01-0497
Reducing the vibrations in the powertrain is one of the prime necessities in today's automobiles from NVH and strength perspectives. The necessity of 4×4 powertrain is increasing for better control on normal road and off-road vehicles. This leads to bulky powertrains. The vehicle speeds are increasing, that requires engines to run at higher speeds. Also to save on material costs and improve on fuel economy there is a need for optimizing the mass of the engine/vehicle. The reduced stiffness and higher speeds lead to increased noise and vibrations. One more challenge a powertrain design engineer has to face during design of its transmission housings is the bending / torsional mode vibrations of powertrain assembly. This aggravates other concerns such as shift lever vibrations, shift lever rattle, rise in in-cab noise, generation of boom noise at certain speeds, etc. Hence, reducing vibrations becomes an important and difficult aspect in design of an automobile.
Technical Paper

A Systematic Approach for Design of Engine Crankcase Through Stress Optimization

2010-04-12
2010-01-0500
The cylinder block for the power train has always been a classic example of concurrent engineering in which disciplines like NVH, Durability, thermal management and lubrication system layout contribute interactively for concept design. Since the concept design is based on engineering judgment and is an estimated design, the design iterations for optimization are inevitable. This paper aims at outlining a systematic approach for design of crankcase for fatigue which would eliminate design iterations for durability. This allows a larger scope for design improvement at the concept stage as the design specifications are not matured at this stage. A process of stress optimization is adopted which gives accurate dimensional input to design. The approach is illustrated with a case study where an existing crankcase was optimized for fatigue and significant weight reduction was achieved.
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