Due to increasing demand for environment friendly vehicles with better fuel economy and strict legislations on greenhouse gas emissions, lightweight design has become one of the most important issues concerning the automobile industry. Within the scope of this work lightweight design potentials that a conventional single cylinder engine crankshaft offers are researched through utilization of structural optimization techniques. The objective of the study is to reduce mass and moment of inertia of the crankshaft with the least possible effect on the stiffness and strength. For precise definition of boundary conditions and loading scenarios multi body simulations are integrated into the optimization process. The loading conditions are updated at the beginning of each optimization loop, in which a multi body simulation of the output structure from the previous optimization loop is carried out.
Torque and performance requirements of Diesel engines are continually increasing while lower emissions and fuel consumption are demanded, thus increasing thermal and mechanical loads of the main components. The level of peak firing pressure is approaching 200 bar (even higher in Heavy Duty Diesel engines), consequently, a structural optimization of crankcase, crank train components and in particular of the cylinder head is required to cope with the increasing demands. This report discusses design features of cylinder head concepts which have the capability for increasing thermal and mechanical loads in modern Diesel engines
This paper introduces a new approach based on a statistical investigation and finite element analysis (FEA) methodology to predict the crankshaft torsional stiffness and stress concentration factors (SCF) due to torsion and bending which can be used as inputs for simplified crankshaft multibody models and durability calculations. In this way the reduction of the development time and effort of passenger car crankshafts in the pre-layout phase is intended with a least possible accuracy sacrifice. With the designated methodology a better approximation to reality is reached for crank torsional stiffness and SCF due to torsion and bending compared with the empirical approaches, since the prediction does not depend on the component tests with limited numbers of specimen, as in empirical equations, but on various FE calculations.