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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.

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.

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.