Use of Non Linear Analysis in Powertrain Design for Prediction of Cylinder Bore Distortion, Design Changes for Reduction along with Experimental Validation

The work presented in this paper deals with the use of non-linear FEA simulation in powertrain development. Prediction of cylinder bore distortion early in the design stage significantly affects overall performance of engine as bore distortion directly affects oil consumption, blowby and emission. The paper presents a methodology for predicting bore distortion with an objective of achieving improved performance of powertrain. For this purpose detailed Finite Element Model of Engine Assembly was prepared, nonlinear interaction between powertrain mating parts was captured by defining contacts, physical behaviour of gasket was captured through experimental testing by extracting loading and unloading pressure closure curve and the same data was used as an input for defining gasket nonlinear properties. Physical assembly sequence was captured by carrying out sequential analysis. In the first step cylinder head bolt pretention was applied as per bolt tightening sequence followed by application of combustion pressure and temperature as per firing order in the subsequent steps. Bore distortion was predicted along the complete length of the liner along with harmonic distortion orders. In order to reduce bore distortion, design changes were carried out in the cylinder head, block and bolt pattern etc. Physical cylinder bore distortion measurements were carried out on prototype using Enchometer. Predicted results through FEA and experimentally measured values were found to be in close agreement. The methodology so developed helped in addressing oil consumption, blowby and emission aspects well in advance early in the design stage, this in turn eliminated design changes after proto built.