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Technical Paper

A Simplified Model of Air Suspension for Multi Body Simulation of the Commercial Passenger Vehicle

2013-01-09
2013-26-0157
Multi Body Dynamics (MBD) simulation software is used in product development cycle to reduce the lead time to market. These software have standard parametric templates for modeling metallic suspension systems, which can be quickly modified and used in full vehicle models for ride, handling analysis and the durability load predictions. Generally every Original Equipment Manufacturer (OEM) has unique air suspension arrangement and hence standard template is not available for air suspension modeling in commercial MBD software. Air suspension with self-leveling control mechanism is preferred over metallic suspension in the commercial passenger vehicle like bus for smooth ride comfort. Hence custom made templates for these systems need to be developed for use with MBD software. In this paper, a simplified model of air suspension is presented.
Technical Paper

Accelerated Combined Stress Testing of Automotive Head Lamp Relays

2017-03-28
2017-01-0275
As technology gets upgraded every day, automotive manufacturers are paying more attention towards delivering a highly reliable product which performs its intended function throughout its useful life (without any failure). To develop a reliable product, accelerated combined stress testing should be conducted in addition to the conventional design validation protocol for the product. It brings out most of the potential failure modes of the product, so that necessary actions can be taken for the reliability improvement. This paper discusses about the field failure simulation and reliability estimation of automotive headlamp relays using accelerated combined stress testing. To analyze various field failure modes, performance and tear down analysis were carried out on the field failure samples. Field data (i.e. electrical, thermal and vibration signals) were acquired to evaluate normal use conditions.
Journal Article

Accelerated Lab Test Methodology for Steering Gearbox Bracket Using Fatigue Damage and Reliability Correlation

2017-04-11
2017-01-9177
In the modern automotive sector, durability and reliability are the most common terms. Customers are expecting a highly reliable product but at low cost. Any product that fails within its useful life leads to customer dissatisfaction and affects the reputation of the OEM. To eradicate this, all automotive components undergo stringent validation protocol, either in proving ground or in lab. This paper details on developing an accelerated lab test methodology for steering gearbox bracket using fatigue damage and reliability correlation by simulating field failure. Initially, potential failure causes for steering gearbox bracket were analyzed. Road load data was then acquired at proving ground and customer site to evaluate the cumulative fatigue damage on the steering gearbox bracket. To simulate the field failure, lab test facility was developed, reproducing similar boundary conditions as in vehicle.
Technical Paper

An Integrated Test Facility for Suspension Dampers of Commercial Vehicle

2018-04-03
2018-01-1383
In the present scenario, delivering the right product at the right time is very crucial in automotive sector to grab the competitive advantage. In the development stage, validation process devours most of the product development time. This paper focuses on reducing the validation time for damper (shock absorber) variants which is a vital component in commercial vehicle suspension system. New test facility is designed for both performance test and endurance testing of six samples simultaneously. In addition, it provides force trend monitoring during the validation which increases the efficiency of test with an enhanced control system. This new facility is also designed to provide side loading capability for individual dampers in addition to the conventional axial loading. The key parameter during validation is control of damper seal temperature within the range of 70-90°C. A cooling circuit is designed to provide an efficient temperature control by re-circulating cold water.
Technical Paper

Cab Suspension Optimization Using Matlab

2013-01-09
2013-26-0147
Driver's ride comfort is an important characteristic in heavy commercial vehicle cab design. Optimizing the ride behavior for different cab variants and vehicle applications is a challenge for cab design and development engineers. Suspension parameter tuning with physical test is time consuming and costly. Therefore, a lumped parameter quarter car model of suspended cab is developed in MATLAB® tool SimScape which includes cab mass, springs and dampers for predicting ride behavior as per ISO 2631. The study is done for a 25 t rigid truck. The input to the system is displacement at axles and the output is acceleration measured at cab and chassis level. This output is correlated with test data obtained from physical measurements using Power Spectral Density (PSD) curves, bode plots and level cross count. This proved that simple lumped parameter models which use very few input parameters can be effectively employed in analysis of cab ride in initial design phases.
Technical Paper

Cost effective and Sustainable Alternate Material for Air Brake Tubings (ABT) in Commercial Vehicles

2014-09-30
2014-01-2409
The automotive industry is constantly looking for new alternate material and cost is one of the major driving factors for selecting the right material. ABT is a safety critical part and care has to be taken while selecting the appropriate material. Polyamide (PA12) [1] is the commonly available material which is currently used for ABT applications. Availability and material cost is always a major concern for commercial vehicle industries. This paper presents the development of ABT with an alternative material which has superior heat resistance. Thermoplastic Elastomer Ether Ester Block Copolymer (TEEE) [3] materials were tried in place Polyamide 12 for many good reasons. The newly employed material has better elastic memory and improved resistance to battery acid, paints and solvents. It doesn't require plasticizer for extrusion process because of which it has got excellent long term flexibility and superior kink resistance over a period of time.
Journal Article

Design and Analysis of Lifting Pusher Drop Axle for Heavy Commercial Vehicle

2017-04-11
2017-01-9176
Lifting axles are auxiliary axles that provide increased load carrying capacity in heavy commercial vehicles. Lift axle gives better fuel efficiency as well as it reduces the operational costs by means of increasing the loading carrying capacity. These axles are raised when the vehicle is in unloaded condition, thus increasing the traction on remaining wheels and reducing the tire wear which in turn lower down the maintenance cost of the vehicle. Lifting height and force requires to lift the whole mechanism and are two main considerable factors to design the lifting axle mechanism. Although in India currently, the use of lift mechanism of single tire with continuous axle is more common. But in the case of pusher axle, continuous axle is unable to lift more after certain height because of the draft angle of the propeller shaft, and single tire axle which has less load carrying capacity up to 6T (Tons).
Technical Paper

Design and Application of ECU Controlled Constant Pressure Exhaust Brake on 5.7 l Engine for ICV Application

2013-01-09
2013-26-0125
To share the excessive load on the service brakes and for safety of the engine valve trains in downhill gradients heavy duty diesel engines are installed with exhaust brake. The duty cycle of an engine is high in mid-range speeds, thus an exhaust brake system with higher braking power at mid- range speeds is required. Automatic actuation of exhaust brake will ensure effective utilization of the available engine braking power and safety. A higher braking efficiency will also lead to improved vehicle downhill performance. This calls for design and application of constant pressure exhaust brake controlled through Electronic Control Unit (ECU) of the vehicle. In the present work, an attempt to applicate constant pressure exhaust brake controlled through ECU of the vehicle on 5.7 l heavy duty diesel engine was made. The limitations of the system were reviewed. A 1-D thermodynamic simulation was used to predict the performance of exhaust brake.
Technical Paper

Design and Development of Bimetal Brake Drum to Improve Heat Dissipation and Weight Reduction

2014-09-30
2014-01-2284
Automotive component light weighing is one of the major goals for original equipment manufacturers (OEM's) globally. Significant advances are being made in developing light-weight high performance components. In order to achieve weight savings in vehicles, the OEM's and component suppliers are increasingly using ultra-high-strength steel, aluminum, magnesium, plastics and composites. One way is to develop a light weight high performance component through multi material concept. In this present study, a bimetal brake drum of inner ring cast iron and outer shell of aluminum has been made in two different design configurations. In two different designs, 40 and 26% weight saving has been achieved as compared to conventional gray cast iron brake drum. The component level performance has been evaluated by dynamometer test. The heat dissipation and wear behavior has been analyzed. In both designs, the wear performance of the bimetal brake drum was similar to the gray cast iron material.
Technical Paper

Design and Weight Optimization of an Automobile Link - A Case Study

2013-01-09
2013-26-0078
A case study was conducted on the design, optimization and material replacement for an automobile suspension link. The link is part of a four bar mechanism. The mechanism was developed in Adams/Car® and multibody simulation was carried out on it. The joint forces arrived from the simulation were exported for finite element analysis of the components in OptiStruct®. Finally, topology and shape optimization was conducted to reduce the weight of the original component. A feasibility study was also carried out to replace the fabricated steel link with a heat treated cast iron link. Heat treated cast iron being lighter than steel, ensures reduction in weight without compromising on strength. The experiment resulted in a feasible optimized shape which was 32% lighter than the current shape of the link being used in the vehicle, while keeping the stresses and displacements within limits.
Technical Paper

Development of a Specific Durability Test Cycle for a Commercial Vehicle Based on Real Customer Usage

2013-01-09
2013-26-0137
Every class of commercial vehicle has an entirely different usage pattern based on customer application and needs. To perform accurate durability testing, these prototypes should run on real customer usage locations and loading conditions for the target life. However, this is time consuming and not practical, hence resulting in Proving Ground (PG) testing. It is also known that a standard PG durability cycle cannot be valid for every class of vehicle and every application. So a statistical approach was followed to develop an accelerated durability test cycle based on in-house PG test surfaces in order to match the real customer usage to the durability target life. This paper summarizes the methodology to develop Durability Validation test cycles for commercial vehicle based on the work carried out on a heavy duty tipper and an intermediate commercial vehicle.
Technical Paper

Durability Analysis of a Bus by Virtual Test Model (VTM)

2013-09-24
2013-01-2378
In this work, durability of the bus structure is evaluated with a Virtual Test Model (VTM).Full vehicle Multi Body Dynamics (MBD) model of the bus is built, with inclusion of flexibility of the bus structure to capture structural modes. Component mode synthesis method is used for creation of flexible model for use in MBD. Load extraction is done by performing MBD analysis with measured wheel inputs. Modal Superposition Method (MSM) is employed in FE along with these extracted loads for calculation of modal transient dynamic stress response of the structure. e-N based fatigue life is estimated. The estimated fatigue life from the modal superposition method show good correlation with the physical test results done in 6-poster test rig.
Technical Paper

Durability Enhancement of Spring Seat in Bogie Suspension

2013-11-27
2013-01-2848
Spring seat plays major role in bogie suspension; which is guiding and controlling the leaf spring for better suspension and also to withstand the compressive load from leafs. Currently used spring seats are failing frequently in medium and heavy duty vehicles, which lead to customer concerns by higher idle time and part replacement cost. Thickness of the spring seat can't be increased by large extent due to packaging constraints in the vehicle. Stress levels identified by FEA method are found higher than the current material capacity. With these constraints, the spring seat has been re-designed with improved strength and ductility of material by modern technology - Austempered Ductile Iron (ADI). The parts have been developed and assembled in various tipper applications and performance was studied. The developed spring seat shows five times superior durability compare to existing design.
Technical Paper

Evaluation of Truck Driver Safety in Various Crash Scenarios

2013-01-09
2013-26-0029
Driver safety is one of the key considerations in truck design and development. Virtual simulation offers opportunities to reduce development time and the number of physical prototypes consumed for design verification and validation for safety parameters. Thus, the application of virtual simulations of crash has become an integral part of the vehicle development process. The continuously emerging scenarios involving challenging test requirements can only be tested by means of virtual simulation techniques. This paper presents simulations that are performed to verify various safety aspects to ensure crashworthiness of the truck cabin. The cabin structure was evaluated for various national/international safety regulations. The FE model and simulation methodology was validated through physical testing and correlated for frontal impact test and roof strength test as per AIS 029/ECE R29. Analysis performed to ensure compliance to upcoming regulation ECE R29 Revision 03 is also discussed.
Technical Paper

Failure Analysis and Multi Frequency Swept Sine Testing of Automotive Engine Oil Sump

2019-01-09
2019-26-0354
Automotive business is more focused towards delivering a highly durable and reliable product at an optimum cost. Anything falls short of customer expectation will ruin the manufacturer’s reputation. To exterminate this, all automotive components shall undergo stringent testing protocol during the design validation process. Nevertheless, there are certain factors in the field which cannot be captured during design validation. This paper aims at developing a validation methodology for engine oil sump by simulating field failure. In few of our vehicles, field failure was observed in engine oil sump near the drain plug location. Preliminary analysis was carried out to find the potential causes for failure. Based on the engine test bed results, multi frequency swept sine testing was carried out in laboratory. Field failure was simulated in the lab test and the root causes for failure were found out.
Technical Paper

Methodology Development for Torsional Vibration Measurement and Processing in Powertrains

2015-06-15
2015-01-2278
Torsional vibration is a characteristic phenomenon of automotive powertrains. It can have an adverse impact on powertrain related noise as well as the durability of transmission and drivetrain components. Hence minimizing torsional vibration levels associated with powertrains has become important. In this context, accurate measurement and representation of angular acceleration is of paramount importance. A methodology was developed for in-house vehicle level torsional vibration measurement, analysis and representation of results. The evaluation of torsional vibration has two major aspects. First, the acquisition of raw rotational data and secondly, the processing of acquired data to arrive at usable information from which inferences and interpretations can be made about the behavior of the rotating element. This paper describes the development process followed for establishing a torsional vibration evaluation methodology.
Technical Paper

Noise Reduction at Source for a Vehicle Using Free Layer Damper

2011-01-19
2011-26-0067
Traditional methods of noise control in most application are by using absorption and barrier techniques. These involve brackets & clamps for assembly, carrier material to hold absorbing materials. Usage of absorbing materials which could be high, as this is based on noise control technique by allowing source to produce noise and hence the cost is also higher. Based on the survey, several demerits have been studied in using absorption and barrier noise control techniques in the field of an automobile application. This paper deals with the noise control by using the application of free layer damping technique thereby overcoming the demerits happening in using former techniques, helping better control of noise in the environment and solutions which are more durable. The methodology followed here before going for the FLD application is identification of noise radiating components which needs to be damped in a system or subsystem.
Technical Paper

Optimization of Proving Ground Durability Test Sequence Based on Relative Damage Spectrum

2018-04-03
2018-01-0101
In competitive vehicle market, the product must be designed and validated in shorter time span without compromising the quality. The durability of the vehicle is tested either by on road trials undertaken at the actual customer supplication sites for large time period or in the accelerated rough surfaces called “Proving ground” to validate in shorter time span. Accelerated proving ground durability testing plays a vital role in enabling shorter product development cycles by simulating the road load influences alone from the actual field conditions. It is imperative to simulate the test vehicle at proving ground (PG) testing such that it replicates the same damage that occurs in the field due to road loads. PG validation requires a specific durability test sequence for every segment of commercial vehicles due to different customer usage applications and terrain conditions. This diversity in applications and terrains induce structural damage at different range of frequencies.
Technical Paper

Seat Suspension Based on Variable Absorber System Stiffness for Enhanced Ride Comfort

2006-10-31
2006-01-3480
One of the important methods by which vibrations of a body are reduced is by the use of vibration absorbers or tuned absorbers. This technique involves attaching a spring mass system, called absorber system, to the vibrating body (also called primary body). This paper is a case study dealing with a primary system, here a driver seat, to attenuate its response to disturbance. It has high damped natural frequency compared to the base excitation frequency, which was collected from test data. The paper discusses the variations in absorber and primary system damping ratio, mass ratio variation and usage of variable stiffness. Detailed analysis showed instability in the tuned system due to the large gap between the primary body's damped natural frequency, and the target base excitation frequency. In order to address varying target excitation frequency, an adaptive tuned absorber is suggested.
Technical Paper

Steering Column Slip Endurance Test & Rig Development

2018-04-03
2018-01-0125
In the emerging commercial vehicle sector, it is very essential to give a product to customer, which is very reliable and less prone to the failures to make the product successful in the market. In order to make it possible, the product is to be validated to replicate the exact field conditions, where it is going to be operated. Lab testing plays a vital role in reproducing the field conditions in order to reduce the lead time in overall product life cycle development process. This paper deals with the design and fabrication of the steering column slip endurance test rig. This rig is capable of generating wear on the steering column splines coating which predominantly leads to failure of steering column. The data acquired from Proving Ground (PG) was analyzed and block cycles were generated with help of data analyzing tools.
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