Sharif Digital Repository

Cast aluminium-silicon alloy, A356.0, is widely used in automotive and aerospace industries because of its outstanding mechanical, physical, and casting properties. Thermal barrier coatings can be applied to combustion chamber to reduce fuel consumption and pollutions and also improve fatigue life of components. The purpose of the present work is to simulate stress distribution of A356.0 under thermo-mechanical cyclic loadings, using a two-layer elastic-visco-plastic model of ABAQUS. The results of stress-strain hysteresis loop are validated by an out of phase thermo-mechanical fatigue test. Different thicknesses from 300 to 800. μm of top coat and also roughness of the interfaces are... 

In this research, a finite element model was developed in order to simulate the two-step residual stress distribution of a thermal barrier coating system, considered to be used in diesel engine cylinder head, with a real roughness and real porosity. Two steps including the bond coat and the top coat deposition processes were taken into account. The real geometry of coating layers, including the roughness and the porosity, was also considered based on a scanning electron microscopy image. Then, effects of the convective heat transfer coefficient and initial substrate and substrate/bond coat preheating temperatures on the residual stress were studied. Obtained results illustrate that the... 

This paper presents the fatigue lifetime of an aluminum-silicon-magnesium alloy, widely used in diesel engine cylinder heads, both with and without a thermal barrier coating (TBC) system. The coating system in this study consists of two layers including a 150 μm thick metallic bond coat and a zirconium oxide top coat 350 μm thick. These coating layers were applied on the substrate of A356.0 alloy by air plasma thermal spraying. The isothermal fatigue tests were conducted in low cycle fatigue (LCF) regime at various temperatures. Out-of-phase thermo-mechanical fatigue (OP-TMF) tests were also performed at different maximum temperatures and constraint factors. Experimental results demonstrate... 

In this article, a novel energy-based lifetime prediction model has been presented for uncoated and coated aluminum alloys, subjected to thermal and mechanical fatigue loadings. For this objective, isothermal and thermo-mechanical fatigue tests were performed on the A356.0 alloy, with and without thermal barrier coating systems. This model, which was based on the plastic strain energy, had three correction factors including temperature, strain and mean stress effects. The predicted lifetime showed a proper agreement with experimental data. By the present model, higher accuracy was obtained in comparison to other existed approaches. Besides, the present model had lower number of material... 

In the present paper, numerical simulation of thermal barrier coating system under thermo-mechanical loadings is performed, using the finite element method in ABAQUS software. The base material is Aluminum-silicon alloy, A356.0 which is widely used in automotive components such as diesel engine cylinder heads. Thermal barrier coatings (TBCs) are applied to combustion chamber in order to reduce fuel consumption and pollutions and also improve fatigue life of components. The roughness effect of coating layers on stress distribution of test specimens is investigated. Semi-ellipsoid roughness of the interfaces between substrate/bond coat and bond coat/top coat are simulated to get the stress...