A Multi-disciplinary Approach for Evaluating Strength of Engine Cylinder Head and Crankcase Assembly under Thermo-Structural Loads

摘要

The design and development of cylinder head and crankcase is the most critical activity in a new Engine program. These two components are subjected to complex and cyclic loading as a result of the interaction between fluid flow, heat transfer and mechanical loads. Apart from structural durability, bore distortions, the need of effective sealing at the head and crankcase joint has to be ensured. The physical validation of the structure requires the components to be developed and this is a long phase including the validation itself. Any modification due to failure or optimization at this stage can be a setback in meeting the deliverables within the given time lines. Physical testing does not provide any means of visualization of the flow and the structural deformation modes. Without proper understanding of the fluid structure interaction and its influence on the thermal loads, it is not possible to reach a fast and optimal solution for any concerns on critical structural parameters, stagnation zones and thermal hot spots. Cylinder head and crankcase evaluation through CAE and CFD in the early stage of design provides significant leap in optimizing and validating these components. The analysis gives multifold benefits, - Identifying thermo-structural hot spots because of flow behavior inside the water jackets. - Prediction of gasket sealing pressures for assessment of the engine head-crankcase joint integrity. - Durability of the structure which is evaluated by considering the coupling of the thermomechanical loads. The paper describes how to integrate the various simulation technologies leading to a multidisciplinary approach for validating the Cylinder head and Crankcase. The paper shows the application of the methodology to a two-cylinder four-stroke diesel engine.