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There have always been different approaches when it comes to ‘Bus body architecture’. The design approach has gone through different phases namely, chassis based, semi integral, integral and monocoque. Equally varied is the choice of material for bus super structure. The predominantly used ones are - mild steel with galvanization, stainless steel (SS) and aluminum. This paper discusses the rationale behind choosing stainless steel for the complete bus structure. With rapid development in infrastructure and public mass transit system, it has become imperative to have a robust structure for buses that is durable and crash worthy. Among the family of stainless steels, ferritic stainless steel exhibits excellent mechanical properties with corrosion resistance and better strength to weight ratio compared to the galvanized mild steel.

Buses have been main means of mass transport in organized as well as unorganized sectors in India. Though the art and science of Chassis Designing had been practiced and matured by all Indian OEMs, Body design had long not been accorded high priority by them. Till 1989, there was no comprehensive set of rules enforced. Bus designs were developed with scant regard for safety and emission. OEMs sold their products in the form of drive away chassis and the Body Design & Body Building was largely left to Body Builders, many of whom employed poor design, build and quality control practices. Spurious materials, parts, non-uniform construction resulted in number of accidents and many of them were fatal. Central Motor Vehicle Rules (CMVR) kicked-in 1st July 1989. With roll out of CMVR, various safety related features like entry/exit door, emergency exits, window frames, their locations, dimensions and designs were defined.

Oil strainer is used in engine oil sump, which prevents dirt, scale and other particle from clogging downstream orifice. In this paper, dynamic analysis was carried out using FEA tool. As a part of dynamic analysis, constrained modal analysis and frequency response (steady state dynamics) analysis was done. Frequency response analysis was done for different engine exciting frequency at different service load (vibration amplitude). Modal superposition method is used for doing frequency response analysis and load is applied as base excitation. The natural frequency from modal analysis and stress response from frequency response analysis is well correlated with test results. Based on achieved good correlation with test, several design modification could be carried out in CAE before finalizing the final design.

Vehicle light-weighting of late has gained a lot of importance across the automotive industry. With the developed nations like the U.S. setting stringent fuel economy targets of 54.5 mpg by 2025, the car industry's R&D is taking light weighting to a whole new level, besides improving engine efficiency. The commercial vehicles on the other hand are also gradually catching up when it comes to using alternate material for weight reduction. This paper will discuss light-weighting in the context of buses though. For a typical bus, the contribution of shell structure weight in the bus body weight is more than 40%. This qualifies as the area with a huge potential for weight saving. On the other hand the shell structure forms the base skeleton of the bus body providing it with adequate strength and stiffness for meeting both functional (bending & torsional stiffness) and passive safety requirements (rollover compliance).