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. Although the initial material cost is higher in case of stainless steel, it still scores better in other areas, namely lower weight, less replacement, lesser down time and recyclability. On the whole the lower life cycle cost (LCC) offsets the initial material cost and yields rich dividends to the end customer.
Besides a lower LCC, stainless steel contributes to safety, because in the event of a collision a mild steel structure may cave in at critical inconspicuous areas if it is exposed to corrosion. Stainless steel by virtue of its higher strength to weight ratio, brings down the unladen weight of the bus and hence improves the fuel efficiency of the vehicle.
This paper establishes an empirical relationship between LCC, raw material cost, weight reduction and fuel cost.