Effect of temperature on fatigue life behaviour of aluminium alloy AA6061 using analytical approach

Abstract

This paper presents the effect of temperature on the fatigue life behaviour of aluminium alloy AA6061, under constant loading conditions, by using an analytical approach. Most of the moving components in automotive engines are under the combined effects of fatigue and temperature. Fatigue life predictions by using conventional experimental methods take a significantly long time. The finite element analysis (FEA) was used for the prediction of fatigue life and point for fatigue failure in the aluminium alloy AA6061 specimen. The stress-life curves at different levels of elevated temperature (50, 100, 150, 200, 250, and 300℃) were predicted by using a mathematical approach of linear interpolation. The maximum temperature of 300℃ was chosen based on the extreme temperature on a piston face that can be reached during the operation of the engine. The results for fatigue life at ambient temperature and at elevated temperature were compared by the Basquin relation and a decrease of 99% in fatigue life cycles was found at 300℃. A general mathematical expression was obtained to calculate the fatigue life for aluminium alloy, AA6061, at elevated temperatures. Therefore, it was concluded that the mathematical expression used in this study can be used as a good alternative approach for time consuming experimental methods. Hence, the mathematical expression proposed in this paper can be used for the early prediction of fatigue life at elevated temperatures without using much experimental analysis.

Keywords

• aluminium alloy 6061
• elevated temperatures
• finite element analysis
• fatigue life
• linear interpolation