THERMO-MECHANICAL FATIGUE LIFE PREDICTION OF A HEAVY DUTY DIESEL ENGINE LINER

摘要

Engine designers are increasingly using more advanced simulation techniques to reduce design time and costs and at the same time to improve the accuracy of the work to limit the number of validation tests required. In recent years, the demand for higher specific power has enforced higher operating temperatures in engine parts, so thermo-mechanical fatigue (TMF) analysis is becoming more important. Liners are one of the challenging parts in heavy duty diesel engines which are exposed to high temperature differential between cooling jacket and combustion chamber and also they are in frictional contact with piston rings, therefore liners are subjected to complicated multiaxial thermal and mechanical stresses. In this study, a detailed analysis is conducted on a centrifugal gray cast iron liner using different CAE tools to have a more accurate estimate of thermo-mechanical loads. The coolant flows inside the liner jacket and combustion process within the cylinder are simulated using 3D CFD methods. Besides the linear FE analysis which is known as an oversimplified method, a multilinear kinematic model is used to simulate the material response more accurately. Using experimental results obtained from cylinder liner material, the different TMF approaches have been investigated and the differences between linear and nonlinear FE simulation in lifetime prediction have been revealed. It is shown that modified Manson-Coffin criterion is the promising relation for lifetime prediction of liner material that correlate better with experimental results.