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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.

Conventional CFD analysis for underhood thermal management is quite involved and time consuming because of the complex geometry and flow distributions. As an alternative to full scale CFD modeling, a hybrid method of vehicle underhood air flow and thermal analysis is presented in this paper, using the principle of flow network modeling (FNM) and CFD. In the present method, the entire flow domain in underhood is broken into various air flow passages, which are represented in a FNM model by nodes and links. For each individual air flow passage selected, CFD analysis is carried out to obtain the pressure drop (ΔP) vs. flow rate (Q) relation by considering various air flow rates, leading to a characteristic curve for each passage. The distribution of flow rates and pressure is then determined by FNM through solving 1D mass and momentum conservation equations over the entire flow network.

Refinement of vehicle interior and exterior noise is becoming more important for occupant comfort and perception of product quality. Recent trends show that modern cars have refined powertrains and as a result other parameters like road and wind noise start dominating. The objective of current work is to establish a structured methodology for analysis of road noise using fairly established techniques like sound quality analysis, operational deflection shape analysis, modal analysis and transfer path analysis. The approach includes road noise characterization, identification of frequencies responsible for road noise, estimation and ranking of contribution of individual frequency noise and vibration through different structural transmission paths from wheel - suspension to the vehicle body. This work also critically examines body modal response, body attach point sensitivities and suspension characteristics.

The advent of April 2005 saw the introduction of Bharat Stage-III (akin to Euro-III) norms in 11 major Indian Cities for all class of vehicles and 74 dB(A) vehicle pass by requirement as per EEC homologation norms for M1 class of vehicles across the country. This paper summarizes development methodology investigated and adopted for 3.0 lit direct injection, naturally aspirated diesel engine with cam driven mechanical fuel injection equipment on multi utility vehicle. This lean technical package compared to the trends of using turbocharger, intercooler and electronic common rail system was conceived to meet the requirement of low cost product offering. The base engine was a derivative of commercial vehicle engine with design features posing significant challenge to achieve the impending regulatory requirements.