The stringent legislative requirements towards a further reduction of vehicle CO2 emissions lead to a continuous increase in specific power output for both gasoline and diesel engines. Simultaneously there is the need for reduced engine structural component masses to ensure fast engine warm-up. Both technology trends result in increased local mechanical stresses in the individual engine components, e.g. cylinder head, engine block, imposing severe requirements onto the components design and the subsequent production process. In particular, the production process needs to be optimized in a way to ensure the resulting engine components to exhibit minimized or well characterized residual stresses and distortions after the casting and/or heat treatment processes in order to fulfill the requirements regarding thermo-mechanical fatigue. The aim of the project is to develop a numerical tool for the industry to optimize the quenching (water quenching and spray quenching) processes of aluminum engine cylinder heads, hence to replace the conventional exhausting experimental trials. An existing 3D-CFD code will be extended to include thermal mechanical model, i.e. to realize the fluid mechanical and thermal mechanical coupling. The multiphase flow in the quenching medium, the heat exchange at the casting/quenching medium interface, the cooling process and the evolution of the residual stress and distortion of the quenched component will be coupled. This development (capability) will enable further integration into the through-process modeling chain which covers numerical predictions of casting, heat treatment, and service performance. Modeling of microstructural evolution will enable the optimization of the solution treatment and the ageing process and to determine the mechanical properties based on kinetic simulation results. Verification and validation are accompanied with the above model development via comparison of calculation results with experimental data from selected reference cases. Finally, the extended CFD code is applied to the analysis of different process design variants of the water and spray quenching processes to provide guidelines for their optimization with respect to achieving minimized and/or well defined residual stresses in the aluminum cylinder heads.
|Tatsächlicher Beginn/ -es Ende||1/12/10 → 30/11/13|