Experimental and theoretical studies on thermo-mechanical fatigue test for aluminium cast alloy

Evaluation of the thermo-mechanical behaviour and prediction of the service life of cast aluminium alloys are important for the design of automobile engine cylinder heads. In this study, cast Al alloy specimens are extracted from cylinder heads and subjected to in-phase thermo-mechanical cyclic loading. The hysteresis curves related to stress and strain were recorded under the individual thermo-mechanical loading conditions. The number cycles to failure corresponding to multiple mechanical strain and temperature ranges were obtained. It is found that the cyclic stress amplitude decreases and the cyclic softening rate increases with increasing maximum temperature rise. A modified fatigue-creep model based on energy conservation has been developed for prediction of the fatigue life of cylinder heads. The proposed method shows good agreement with the well-established Ostergren model and low standard deviations. In summary, the proposed method described in this study provides an option for prediction of the thermo-mechanical behaviour of metals.