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With the stringent legislative requirements for noise in automobiles, gensets etc., the concern for properly designed silencers for specific applications is increasing. Optimized design of silencer requires an integrated study of acoustical and engine performance viz. Insertion loss and backpressure. However, the insertion loss itself depends upon engine characteristics geometry indicated by the transmission loss, flow induced noise, type of silencer - reactive, absorptive, hybrid, etc. Most of the work till date covers the acoustical and engine performance in isolation rather than in an integrated fashion due to the multidisciplinary nature of the problem. The objective of this study is to develop an integrated methodology to predict the performance of the silencer at the design stage resulting in an optimized time and cost effective design. In the present study, the acoustical and engine performance of silencer was predicted using FEM/BEM and CFD techniques.

Modern vehicles are designed for quiet interior with lower engine and exhaust noise levels. Under such circumstances, gear whine and rattle become one of the significant contributors towards in-cab noise, besides wind and road noise. Present paper deals with dynamic analysis, simulation and validation of the transmission system model for observed gear whine inside the cabin of a passenger car during its running condition. The exercise included development of an accurate numerical model to enable prediction of noise transmission from automatic gearbox to cabin structure. Experimental Modal Testing (EMT) of automatic transmission and suspension components, Multibody simulation of automatic transmission and Finite Element Analysis (FEA) of components and subassemblies followed by component and system level response correlations were carried out. Detailed methodology adopted for the exercise is discussed in the paper.

The latest requirements for automotive cabin comfort require lower sound levels inside the cabin. There are many sources contributing to this noise of which fan is an important one. The blade passage noise of the cooling fan is often unpleasant and it is generally expensive to build and test different prototypes for optimum noise performance. Also, traditional unsteady computational approaches for predicting the fan noise are time and resource consuming and do not fit within the design cycle time. This paper proposes use of a steady state computational technique to predict the fan noise performance which provides for effective design study with optimum resources. The steady state data is used with the wave analogy to predict the overall sound pressure level. First, the computational results were validated with the experimental data for a base case and then parametric study was carried out to have optimum design.

Accelerated life evaluation of vehicle has become the order of the day with the continuously decreasing development time for product development. With the rapid progress in the computer aided design area, today it is possible to feed-in virtual test tracks so that even before a prototype is made, a life estimate could be arrived at. Further, the advent of rapid prototyping has also resulted in reducing the time required for development of prototypes considerably. This has put the proving engineers under tremendous pressure in reducing the time required for design validation. This has resulted in a number of techniques being developed for reducing number of tests required as well as test duration in validation of the prototypes. One such technique is non-square matrix simulation. This technique can also be used for the investigation of failures and validation of the modifications.

With increasing competition and number of global players entering the Indian market, the Indian tractor scenario is as hot and fluid as that of the passenger car. Tractor manufacturers are under tremendous market pressure to become internationally competitive and bring out new tractor models in the shortest time possible as well as keeping the validation costs to a minimum. This is making them to look for advanced techniques for reducing the development time such as service load data acquisition and analysis, life prediction and accelerated simulation tests for design validation. This paper presents such an effort by an Indian tractor manufacturer along with ARAL Design validation of the chassis was carried out as a complete structure instead of carrying out on individual components.

For high degree of engine performance, it is imperative that all critical parts are designed and optimised through durability assessment. The conventional engine development programme based on actual engine test on test bed is time consuming and expensive, and is being replaced by use of simulation tools and accelerated component testing. The present work is a systematic fatigue strength evaluation programme for connecting rod of an up-rated Naturally Aspirated, Direct Injection, Inline Diesel Engine The established staircase method of fatigue test is slightly modified to minimise the effect of scatter in the results and to arrive at a consistent and dependable factor of safety. Also analytical tools like Finite Element Analysis (FEA) and Statistical Techniques were used; which helped to keep design and tooling iterations to a minimum and facilitated connecting rod development in the given time frame.