Design and simulation of a cylinder head structure for a compressed natural gas direct injection engine

In this work, the design and simulation of a cylinder head with compressed natural gas direct injection (CNGDI) is studied based on finite element analysis. The analysis was carried out to simulate the stress and displacement for the cylinder head at various engine speeds in the range of between 1000 and 5400 rpm. The design is developed using CATIA V5, and simulated using MSC Nastran, then pre- and post-processed by MSC Patran. Based on the simulation results, an improved design for the CNGDI cylinder head was achieved. The stress and displacement analysis highlighted several areas of interest, and the maximum stress for the modified model of 56.16 MPa was found not to exceed the allowable compressive yield strength of the material used (aluminum alloy A356-T6), of 172 MPa. The maximum displacement for the modified model, which was 0.00972 mm, was below the lowest displacement limit of 0.032 mm. For the modified model, the strength was improved by about 1.72%, and the displacement decreased by about 3.55% compared to the original model. Thus, the result can be used to assess the quality of the design, where no yielding and structural failure occurred in the firing load case, as having satisfied the requirement.