On the Service Life Prediction of Diesel Engine Cylinder Head under Thermo-mechanical Fatigue Loading with Several Damage Models: A Comparative Study

The objective of the present paper is to assess the capability of several classical damage models in prediction of service lifetime of engine components subjected to Thermo-mechanical Fatigue (TMF) loading. The focus of the present study is based on efficient and robust predictive tools which are suitable in industrial development process, thus the classical fatigue damage models are selected to perform such a tsk. In the classical framework, three strain-based models including Manson-Coffin, Smith-Watson-Topper and Ostergren models and one plastic strain energy-based model are examined. Besides, some correction factors are added to the Manson-Coffin, Ostergren and plastic strain energy models regarding the mean stress and temperature effects. The statistical analysis of the models is carried out utilizing the Low-cycle fatigue and Thermo-mechanical Fatigue tests on standard specimens of A۳۵۶ aluminum alloy. The analysis indicated that modified Ostergren model is the most reliable model in fatigue lifetime description of the A۳۵۶ alloy among the others. The studied engine component is a passenger-car diesel engine cylinder head made of A۳۵۶ aluminum alloy. The temperature, stress and strain distribution fields of the component are considered as the given boundary conditions from our previous work as they are not in the scope of the present investigation. The selected damage models based on the best accuracy identified during statistical analysis are introduced into the ABAQUS software. The modified Ostergren model presented the most accurate and realistic results based on empirical observations of fatigue crack area in diesel engine cylinder heads studied in the literature.

Keywords:

Thermo-mechanical Fatigue , Diesel engine cylinder head , Damage criterion , Cast aluminum alloy , ABAQUS software