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New process development of forging component require lot of process knowledge and experience. Even lots of trial-and-error methods need to be used to arrive at optimum process and initial billet dimensions. But with help of reliable computer simulation tools, now it is possible to optimize the complete process and billet dimensions without a single forging trial. This saves lot of time, energy and money. Additionally, simulation gives much more insight about the process and possible forging defects. In this paper, a complete forging process was needed to be designed for a complex component. With the help of computer simulation, the complete conventional forging process and modified forging process were simulated and optimized. Forging defects were removed during optimization of the process. Also billet weight optimization was carried out. Deciding the pre-forming shape of the billet was the main challenge.

High noise at Operator Ear Level (OEL) of tractor is the major cause of fatigue to the operator. With growing competition, and upcoming legislative requirement there is ominous need for the agricultural tractor manufacturers to control noise levels. Objective of the present study is noise reduction on agriculture tractor by identifying and controlling key noise sources unaffecting performance parameters like power, torque and fuel efficiency to meet upcoming noise legislations. Noise Source Identification (NSI) is carried out to identify and rank airborne and structure borne noise sources. The airborne sources such as cooling fan, exhaust silencer and intake are evaluated using elimination method at tractor level. The NSI on engine is carried out separately in hemi anechoic chamber to identify the major noise radiating components by using noise and vibration measurement, sound intensity mapping tools.

Automotive seats play a vital role for improving the overall sound absorption inside the vehicle. To understand the acoustic performance of automotive seats in the passenger compartment of a vehicle, various types of seat assemblies were tested by the reverberation chamber method as per ASTM C423. The methodology has been developed to test the seats based on seats position in the chamber and minimum requirement of seats to evaluate the accurate sound absorption and Reverberation Time (RT). The effect of various seat cover materials like leather and cloth fabrics on the seat sound absorption and RT has been determined experimentally. Study of various cover materials (leather/vinyl and cloth fabrics) with PU foam for sound absorption characteristics has been carried out using simulation technique. The intrinsic parameters used as inputs in above steps are evaluated using specialized test rigs.

Diesel engine generator (DG) sets used in industrial plants and residential/official buildings cause serious noise problems if not (canopised) properly. Generally, DG set engines used are with rotational speed of 1500 rpm. In present study automotive diesel engine with 3000 rpm speed was converted for Genset application. Due to higher speed, engine noise levels and its cooling requirements were quite high. Objective of the study was to optimize the design of an enclosure for the said DG set to meet requirements of low noise and proper ventilation to comply MoEF legislative limits. A detailed Noise Source Identification (NSI) was carried out to identify and rank different noise sources. A Hybrid approach which consists of experimental DOE and simulation based on Boundary Element Method (BEM) was used for enclosure design. Design variables like enclosure dimensions, sound absorbing materials and louvers were used in optimization study.

Transfer Path Analysis (TPA) is an important tool used worldwide to identify noise and vibration sources in vehicle(s). A complete TPA can be performed on proto-type vehicle or a fully built vehicle but it is time consuming and resource sensitive. New advancements in TPA include combining both acoustic and structural loads from stationary response functions and actual noise/vibration during operating conditions. So it is becoming important to define a known set of frequency response functions in order to understand vehicle's operational behavior. In this paper, an attempt has been made to simulate vehicle cab from structural and acoustic viewpoint with the help of vibro-acoustic transfer functions. Vibro-acoustic modal parameters, vibration transfer functions (VTF) and Noise Transfer Functions (NTF) were predicted using FEA techniques. A set of experiments on a simple model was carried out to validate the predicted FE results.

Exhaust noise is the major noise source for the automotive vehicle contributing to its interior as well as exterior noise. The Transmission Loss (TL), noise reduction, Insertion Loss (IL) and radiated noise are the major characteristics used to describe the performance of a muffler in an automotive exhaust system. Out of these characteristics, Insertion loss and exhaust radiated sound pressure levels plays a significant role in muffler design as it is a measure of true performance of muffler along with engine/vehicle and very much useful for the designers to compare different silencer configurations. In present work, the sound source is modelled by acoustic impedance and volume velocity of the engine. Since it is difficult to estimate the sound source impedance of the exhaust by measurements either with direct or indirect methods as both are prone to errors and difficult to implement, the empirical equations are used to define exhaust source, to have reasonable accuracy.

Seat system resonant frequencies play an important role in seat design and ride dynamics. So NVH performance of the seats should be assessed from the viewpoint of tactile, acoustic and visual sense. Tactile response is the response of sub-systems, which is induced when the human body contacts steering wheel, footrest or seats. Acoustic response is the behavior of the seat system at the cavity resonance frequencies and visual sense is what we perceive under actual operating conditions. The objective of the present work is to conduct and correlate experimental modal test with FE modal test to identify tactile vibrations. Then the identified main seat modes will be used to set the mode map (seat target) at the stage of full vehicle level. This work will present a practical approach in understanding varied methods and techniques for determining resonant characteristics and for subsequent refinement of FE model.

The acoustical performance of a vehicle dash panel system is rated by the noise reduction, which is calculated from the sound transmission and absorption characteristics. A typical dash insulator consists of a steel panel (vehicle body panel), a porous decoupler and heavy layer in the form of sandwich construction. The use of dash panel is to block engine noise from entering into the interior cabin. In the present study the transmission loss of dash panel has been evaluated in reverberation chambers and the sound absorption of dash panel has been determined in impedance tube. This paper deals with improving over all sound transmission loss and shifting of the double wall resonance well below the engine firing frequencies by changing the decoupler materials such as felt and foams of different density and thickness and heavy layer mass per unit area.

The transportation noise is one of the major sources of noise exposure in residential areas and causes substantial annoyance particularly during night. Considering this, many countries have enacted legislation limiting the noise levels in residential areas and also the noise levels emitted by vehicles. In India also, the Ministry of Environment and Forests enacted Environment (Protection) Rules through Air Pollution Act in 1986. Various international as well as Indian standards for vehicles consider two types of noise measurement viz., Pass-By Noise (PBN) and Stationary Noise (SN). There is a debate going on whether in-use vehicle noise should be considered as a parameter for the Inspection and Maintenance (I&M) regime, which is to be introduced shortly in India. A detailed study was conducted to understand the relation between PBN and SN for both new and in-use vehicles.

The braking systems for vehicles are undergoing a continuous development and improvement. The recent trend in motorcycle industry is to go for front disc brake system to have the advantage of less stopping distance and efficient braking over conventional drum brakes. In India the present practice of replacing the drum brake assembly with disc brake assembly, without redesigning of complete assembly of shock absorber may adversely affect its durability. This paper presents a detailed study made through service load data acquisition and analysis on the strength of front shock absorber tube. It was observed that with disc brake there is considerable increase in bending stress on the inner steel tube of shock absorber during braking. This paper highlights the comparison of strain distribution of the shock absorber tubes in disc brake and drum brake and concludes with a need for better design/material for shock absorber tube.

This paper addresses in detail the methodology developed for the design and evaluation of engine mounting system. The design phase involves selection and laying out mount locations and specifying the insulators, in order to decouple the critical modes. The 3 main criteria to be used viz. nodal point location, centre of percussion and decoupling are discussed. The evaluation phase involves measurement of vibration and noise level at different locations in the vehicle. The evaluation tools available are the transmissibility, the Campbell diagram and peak sound pressure level. This paper presents the results of a study carried out for evaluation of existing arbitrary 3 point and 4 point mount options and a systematically developed 3 point one. It also presents a methodology for the evaluation of design and development of engine mounts.