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    A new energy-based isothermal and thermo-mechanical fatigue lifetime prediction model for aluminium-silicon-magnesium alloy

    , Article Fatigue and Fracture of Engineering Materials and Structures ; Volume 36, Issue 12 , 2013 , Pages 1323-1335 ; 8756758X (ISSN) Farrahi, G. H ; Azadi, M ; Winter, G ; Eichlseder, W ; Sharif University of Technology
    2013
    Abstract
    In this paper, a new fatigue lifetime prediction model is presented for the aluminium-silicon-magnesium alloy, A356.0. This model is based on the plastic strain energy density per cycle including two correction factors in order to consider the effect of the mean stress and the maximum temperature. The thermal term considers creep and oxidation damages in A356.0 alloy. To calibrate the model, isothermal fatigue and out-of-phase thermo-mechanical fatigue (TMF) tests were conducted on the A356.0 alloy. Results showed an improvement in predicting fatigue lifetimes by the present model in comparison with classical theories and also the plastic strain energy density (without any correction... 

    Optimization of air plasma sprayed thermal barrier coating parameters in diesel engine applications

    , Article Journal of Materials Engineering and Performance ; Volume 22, Issue 11 , 2013 , Pages 3530-3538 ; 10599495 (ISSN) Azadi, M ; Farrahi, G. H ; Moridi, A ; Sharif University of Technology
    2013
    Abstract
    In the present paper, an optimization of thermal barrier coating parameters is performed for diesel engine applications. The substrate is A356.0-T7, a cast aluminum alloy which has a vast application in diesel engines, and the alloy is coated by plasma sprayed ZrO2-8 wt.% Y2O3. Parameters including the feed rate of coating powders, the nozzle distance to specimen surfaces, and the coating thickness are optimized by thermal shock fatigue tests and bending tests. Optimum values of the feed rate and the nozzle distance are 30 g/min and 80 mm, respectively, when the objective is considered as maximizing the bending strength. Thermal shock tests demonstrate that lower thickness of coating layers... 

    Heat treatment effect on thermo-mechanical fatigue and low cycle fatigue behaviors of A356.0 aluminum alloy

    , Article Materials and Design ; Volume 45 , 2013 , Pages 279-285 ; 02613069 (ISSN) Azadi, M ; Shirazabad, M. M ; Sharif University of Technology
    2013
    Abstract
    In the present paper, the heat treatment effect on A356.0, a cast aluminum alloy which has been widely used in diesel engine cylinder heads, is investigated under out-of-phase thermo-mechanical fatigue and low cycle fatigue (at different temperatures) loadings. A typical heat treatment is applied to the material including 8. h solution at 535 °C, water quench and 3. h ageing at 180 °C. The experimental fatigue results show that the heat treatment process has considerable influence on mechanical and low cycle fatigue behaviors, especially at room temperature, but its effect on thermo-mechanical fatigue lifetime is not significant. The improvement in the strength can be explained by the...