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Technical Paper

Systematic CAE Approach to Minimize Squeak Issues in a Vehicle Using Stick-Slip Test Parameters

2021-09-22
2021-26-0269
Due to recent advancements in interior noise level and the excessive use of different grade leathers and plastics in automotive interiors, squeak noise is one of the top customer complaints. Squeak is caused by friction induced vibration due to material incompatibility. To improve costumer perception, interior designs are following zero gap philosophy with little control on tolerances leading to squeak issues. Often manufacturers are left with costly passive treatments like coatings and felts. The best option is to select a compatible material with color and finish; however, this will reduce the design freedom. Material compatibility or stick-slip behavior can be analyzed with a tribology test stand. However, this test is performed on a specimen rather than actual geometry. There were instances, when a material pair was found incompatible when tested on a specimen, but never showed any issue in actual part and vice versa.
Technical Paper

Methodology Development for Open Station Tractor OEL Noise Assessment in the Virtual Environment

2021-09-22
2021-26-0310
There is a higher demand for quieter tractors in the agri-industry, as the continued exposure to noise levels have disastrous effects on operator’s health. To meet the world-wide regulatory norms and to be the global market leader, its mandatory to develop the comfortable tractor which meets homologation requirements and customer expectations. Typically, Operator Ear Level (OEL) noise has been evaluated in the test, after First Proto has been made. This approach increases cost associated with product development due to late changes of modifications and testing trails causing delay in time-to-market aspect. Hence, there is a need to develop the methodology for Predicting tractor OEL noise in virtual environment and propose changes at early stage of product development. At first, full vehicle comprising of skid, sheet metals and Intake-exhaust systems modelled has been built using Finite Element (FE) Preprocessor.
Technical Paper

Utilizing Weathering Effect to Understand Squeak Risk on Material Ageing

2021-09-22
2021-26-0280
Squeak and rattle concerns accounts for approximately 10% of overall vehicle Things Gone Wrong (TGW) and are major quality concern for automotive OEM’s. Objectionable door noises such as squeak and rattle are among the top 10 IQS concerns under any OEM nameplate. Customers perceive Squeak and rattle noises inside a cabin as a major negative indicator of vehicle build quality and durability. Door squeak and rattle issues not only affects customer satisfaction index, but also increase warranty cost to OEM significantly. Especially, issues related to door, irritate customers due to material incompatibilities. Squeaks are friction-induced noises generated by stick-slip phenomenon between interfacing surfaces. Several factors, such as material property, friction coefficient, relative velocity, temperature, and humidity, are involved in squeak noise causes.
Technical Paper

A Comprehensive Study on the Challenges of Dual Mass Flywheel in Real-World Operating Conditions of the Indian Market

2020-04-14
2020-01-1014
The present work is focussed on the real-world challenges of a dual mass flywheel (DMF) equipped vehicle in the Indian market. DMFs are widely used to isolate the drivetrain from the high torsional vibrations induced by the engine. While DMFs can significantly improve noise, vibration and harshness (NVH) characteristics of a vehicle, there are multiple challenges experienced in real-world operating conditions when compared with the single mass flywheel (SMF). The present work explains the challenges of using a DMF in a high power-density diesel powertrain for a multi-purpose vehicle (MPV) application in the Indian market. Measurements on the flat-road operating conditions revealed that the DMF vehicle is very sensitive for launch behaviour and requires a higher clutch modulation. Vibration measurements at the driver’s seat confirm that the SMF vehicle could be launched more comfortably at the engine idle speed of 850 RPM.
Technical Paper

A Case Study of Compressor Surge Related Noise on Turbocharged 2.0-L Gasoline Engine

2021-09-22
2021-26-0282
Till recently supercharging was the most accepted technique for boost solution in gasoline engines. Recent advents in turbochargers introduced turbocharging technology into gasoline engines. Turbocharging of gasoline engines has helped in powertrains with higher power density and less overall weight. Along with the advantages in performance, new challenges arise, both in terms of thermal management as well as overall acoustic performance of powertrains. The study focuses mainly on NVH aspects of turbocharging of gasoline engines. Compressor surge is a most common phenomenon in turbochargers. As the operating point on the compressor map moves closer to the surge line, the compressor starts to generate noise. The amplitude and frequency of the noise depends on the proximity of the operating point to the surge line. The severity of noise can be reduced by selecting a turbocharger with enough compressor surge margin.
Technical Paper

Agricultural Tractor Engine Noise Prediction and Optimization through Test and Simulation Techniques

2021-09-22
2021-26-0277
Engine radiated noise has complex behavior as engine assembly consist different components, varying dynamic forces with wide range of speed. For open station tractor, engine noise is major contributor and hence needs to be optimized for regulatory norms as well customer comfort. The awareness about NVH comfort in domestic market as well as export market is increasing as customer have become more demanding. This forces OEM’s to put serious efforts to ensure the OEL noise / Engine noise is at acceptable levels. Identifying the optimized countermeasures to reduce the engine noise during the early design phase has a greater impact in reducing product development time and cost. This paper describes about a process that has been established for evaluating engine radiated noise and to improve the overall NVH performance.
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

Thermal Signature Investigation of an Electric Tractor for Military Applications

2013-11-27
2013-01-2757
Technology is one of the key determinants of the outcome in today's wars. Many targeting systems today use infra-red imaging as a means of acquiring targets when ambient light is insufficient for optical systems. Reducing thermal signatures offers an obvious tactical advantage in such a scenario. One way to reduce thermal emission of combat vehicles is to adopt highly efficient electrical power trains instead of internal combustion engines that tend to reject a sizeable amount of the input energy as heat. The tractor is one of the most versatile vehicles that are used in the theatre of combat for various operations such as haulage, clearing terrain, deploying bridges, digging trenches etc due to its excellent abilities in handling difficult terrain. A tractor powered by an all-electric power train was developed for civilian applications. The traction characteristics are identical to that of a conventional diesel powered tractor of comparable size.
Technical Paper

Diagnosis and Elimination of Disc Brake Groan in a Utility Vehicle

2014-04-01
2014-01-0043
Brake groan noise is resolved without any major change in the design of brake system and vehicle sub-system components in the development phase of a utility vehicle. The groan noise is observed during the end of the stopping of the vehicle under moderate braking. The concerned NVH issue is perceived as unacceptable noise in the passenger compartment. Groan induced vibration is subjectively felt on steering and seat frame. A typical process is established to successfully reproduce the groan which helped in precisely evaluating the effect of modifications proposed. The temperature range of the disc which has the highest probability to produce the groan noise is found out experimentally. The transfer path analysis is carried out to find the path contributions from suspension. Acoustic transfer functions from considered paths are measured with the suspension removed from vehicle.
Technical Paper

Overcoming Manufacturing Challenges in Mass Production of Vanadium Micro-Alloyed Steel Connecting Rods

2022-03-29
2022-01-0234
With recent advancements to create light weight engines and therefore, to design stronger and lighter connecting rods, automobile manufacturers have looked upon vanadium micro-alloyed steels as the material of choice. These materials have been developed keeping in mind the strength and manufacturing requirements of a connecting rod. Since, 36MnVS4 has been the most popular of this category, the same has been discussed in this paper. The transition of manufacturers from the traditional C70S6 grade to the new 36MnVS4 must be dealt with in-depth study and modification of processes to adapt to new properties of the latter. C70S6 is a high carbon grade with superior fracture split whereas 36MnVS4 is a medium carbon grade with superior strength and ductility owing to the presence of vanadium.
Technical Paper

Model-Based Simulation Approach to Reduce Jerk Issue in Power Shuttle Transmission (PST) Tractor

2022-08-30
2022-01-1119
Nowadays, tractors are frequently used with front-end loaders, dozers and backhoes to cater to various non-agricultural and construction application needs. These applications require frequent shifting of gears due to the constant need for a tractor's forward/reverse direction of motion. Hence, the tractors are fitted with a power shuttle transmission (PST) to cater this need. Power-shuttle transmission (PST) development is a design process that incorporates multiple disciplines such as mechanical, hydraulics, controls and electronics. This paper presents a simulation-based approach to model the power shuttle transmission of the tractor. Firstly, individual components of PST are modelled in detail and then integrated with the complete tractor model. For this, GT-Suite has been used as a simulation platform.
Technical Paper

A Unique Methodology to Evaluate the Metallic Noise Concern of a Dual-Mass Flywheel in Real-World Usage Conditions

2021-10-01
2021-28-0249
Dual mass flywheel (DMF) is an excellent solution to improve the noise, vibration, and harshness (NVH) characteristic of any vehicle by isolating the driveline from the engine torsional vibrations. For the same reason, DMF’s are widely used in high power-density diesel and gasoline engines. However, the real-world usage conditions pose a lot of challenges to the robustness of the DMF. In the present work, by capturing the Real-World Usage Profile (RWUP) conditions, a new methodology is developed to evaluate the robustness of a DMF fitted in a Sports utility vehicle (SUV). Ventilation holes are provided on clutch housing to improve convective heat transfer. Improvement in convective heat transfer will increase the life and will reduce clutch burning concerns. Cities like Mumbai, Chennai, Bangalore, roads will have clogged waters during rainy season. When the vehicle was driven in such roads, water enters inside the clutch housing through ventilation holes.
Technical Paper

Optimization of Clutch Pedal Vibration without Compromising the Overall Efficiency of the Clutch System

2021-10-01
2021-28-0247
The clutch pedal in manual transmission plays a significant role in defining the comfort of driver as the component is one of the end user’s direct interface in the vehicle. Whenever driver operates the clutch pedal, comfort and NVH refinement should be felt over the complete pedal travel. The expectations of customer on NVH refinements, such as pedal vibration felt on foot during actuation, becomes the part of perceived quality and hence addressing the concern is very crucial. Due to advancements of technology and down-sizing of engines, NVH becomes the challenging area where the clutch pedal vibrations need to be eliminated to improve the comfort. In this paper we are explaining the problem statement and NVH solution to eliminate the clutch pedal vibration observed during clutch pedal actuation. Pedal vibrations were very severe at 10% clutch pedal pressed condition, and the same tends to diminish till 50% clutch pedal pressed condition.
Technical Paper

A Disciplined Approach to Minimize Rattle Issues in Automotive Glove Box Assembly

2018-06-13
2018-01-1481
Nowadays, perception of automotive quality plays a crucial role in customer decision of vehicle purchase. Hence, automotive OEM’s are now working on the philosophy of “Quality Sound”. Out of all the Noise, Vibration & Harshness (NVH) issues identified in a vehicle, the ranking of Buzz, Squeak & Rattle (BSR) stands high and glove box rattle is one of the issues that is continuously observed in all customer verbatim. Specific issues like lid rattle and latch rattle are predominant and gets worse over mileage accumulation. Also minimizing BSR issues in glove box is difficult due to complex latch mechanism. While deciding the bump stop specifications more weightage is given to efforts. The bump stop is selected in a way as not to increase the glove box opening and closing efforts, but the selected bump stops will not provide enough preload to glove box lid leading to rattle issues.
Technical Paper

Design For Affordability -Composite Running Board

2015-01-14
2015-26-0070
Light weighting is the Current trends in automotive to achieve better fuel economy which helps for meeting fuel economy standards & to offset the higher fuel prices. Thus there is a need to develop composite running board which is light weight & structurally sound enough to meet the performance. The present paper provides a composite running board assembly for an automobile. The running board assembly includes a board, an insert body and a plurality of brackets. Upon stepping of a passenger on the board, the board transfers load on the insert body which subsequently transfers the load to the plurality of brackets thus facilitating even distribution of the load on the automobile body. This paper also put lights on the use of improved TRIZ application - an approach to inventive problem solving for designing highly affordable & light weight running board. The cost & weight reduction achieved with innovative design is about 40 % & 35 % comparing to existing cost & weight.
Technical Paper

Analysis of Drive Line Vibration and Boom Noise in an All Wheel Drive Utility Vehicle

2014-04-01
2014-01-1975
The customer demand for all wheel drive (AWD) vehicles is increasing over the period of time which also requires NVH performance on par with front wheel drive vehicles. AWD vehicles are equipped with power transfer unit, propeller shaft and independent rear differential assembly to achieve their functional requirement. The additional drive train components in AWD vehicles may amplify torsional fluctuations in the drive line. Hence achieving the NVH performance of AWD vehicles on par with FWD vehicles without any major change in the existing design is a major challenge. In this work, an AWD vehicle with severe body vibration and booming noise is studied. The operational measurements are taken throughout the drive train on all sub-systems from engine to the rear part of the body in the problematic operating condition. An operational deflection shape analysis is conducted to visualize the vibration behavior of the drive train.
Technical Paper

Ergonomic Study of Occupant Seating Using Near-Vertical Posture for Shared Mobility Applications

2020-09-25
2020-28-0519
Transportation system is at the brink of revolution and many new ways of mobility are arising in the market to ease the pressure on the established transportation infrastructure. Many companies and governments around the world are exploring innovative options in the space of shared mobility to reduce the overall carbon footprint. To expedite the adoption of shared mobility in India, it is necessary to make such options comfortable and cost-effective. One of the most effective way to make shared mobility options cost effective is to comfortably increase occupancy per vehicle footprint. This paper aims to evaluate a novel method of occupant seating to identify the maximum number of passengers a vehicle can accommodate without significant impact on occupant comfort. It is assumed that shared mobility options are used for a short duration of commute, and hence the comfort of the seat can be marginally compromised to increase the total number of occupants.
Technical Paper

A Unique Methodology to Evaluate the Structural Robustness of a Dual-Mass Flywheel under Real-World Usage Conditions

2020-09-25
2020-28-0475
Dual mass flywheel (DMF) is an excellent solution to improve the noise, vibration and harshness (NVH) characteristic of any vehicle by isolating the driveline from the engine torsional vibrations. For the same reason, DMFs are widely used in high power-density diesel and gasoline engines. However, the real-world usage conditions pose a lot of challenges to the structural robustness of the DMF. In the present work, a new methodology is developed to evaluate the robustness of a DMF fitted in a compact sports utility vehicle (SUV) with rear-wheel drive architecture. The abuse conditions (mis-gear, sudden braking, etc) in the real-world usage could lead to a sudden engine stall leading to an abnormally high angular deceleration of the driveline components. The higher rate of deceleration coupled with the higher rotational moment of inertia of the systems might end up in introducing a significantly high impact torque on the DMF.
Technical Paper

A Test Methodology for Vehicle Wind Noise Reduction and Acoustic Quality Improvement

2019-01-09
2019-26-0216
Aeroacoustics of vehicles is becoming an important design criterion as it directly affects passenger’s comfort. The wind noise at highway speeds (>80 KMPH) is a critical quality concern under normal and crosswind conditions and dominant factor in assessing acoustic comfort of the vehicle. Wind noise is caused by the vortex air flow around a vehicle body and air leakage through the sealing gaps of attached parts. This majorly contributes to high frequency noise (>250 Hz). Accurate identification and control of noise sources and leakage paths result in improved acoustic comfort of the vehicle. In this paper, aero-acoustic quality characteristics of validation prototype vehicle are studied. The major wind noise sources and leakage paths in the vehicle are identified through in-house blower set up in the semi anechoic room. The overall wind noise level and articulation index of vehicle at various speeds are determined through on- road measurements.
Technical Paper

Importance of Metallurgical Properties to Prevent Shaft Failures in Off-road Vehicle Validation

2023-05-25
2023-28-1319
Globally, automotive sector is moving towards improving off-road performance, durability and safety. Need of off-road performance leads to unpredictable overload to powertrain system due to unpaved roads and abuse driving conditions. Generally, shafts and gears in the transmission system are designed to meet infinite life. But, under abuse condition, it undergo overloads in both torsional and bending modes and finally, weak part in the entire system tend to fail first. This paper represents the failure analysis of one such an incident happened in output shaft under abuse test condition. Failure mode was confirmed as torsional overload using Stereo microscope and SEM. Application stress and shear strength of the shaft was calculated and found overstressing was the cause of failure. To avoid recurrence of breakage, improvement options were identified and subjected to static torsional test to quantify the improvement level.
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