Improving fuel economy and reducing emissions is becoming critical for future vehicles which will be lighter and faster. This demands, future engines to cater two contradictory requirements, one is high power density engine and other is lightweight compact engine design. This would require rigorous and accurate structural evaluation to achieve optimum design.
Downsizing the engine is best way to achieve these goals. Three cylinder diesel engine is best suited for achieving high power and performance. It brings in challenges of design complexity due to need of balancer shaft for three cylinder engine.
Bedplate evaluation becomes difficult due to design complexity induced by integration of Cast Iron inserts in Aluminum bedplate and packaging of balancer shaft. Also manufacturing process involved, operating temperatures, high combustion pressures increase the difficulties.
The paper deals with methodology adopted to evaluate structural strength of Aluminum bedplate with Cast iron insert for operating loads. The approach considers material nonlinearity, temperature dependent property variation, uneven expansion and contraction, sliding interactions at the interfaces of dissimilar bedplate materials, and stresses generated due to thermo-mechanical loads. Quenching and machining generates residual stresses in bedplate of significant levels. Consideration of these effects in fatigue analysis is discussed. Operating temperature from CFD simulations and bearing dynamic loads from multi-body dynamic simulations are used to evaluate fatigue factor of safety. All this leads to accurate predictions of structural strength.
The multi-disciplinary approach adopted provides opportunity to work out optimum, lightweight design for high density diesel engines.