Comprehensive Modelling of the Hysteresis Loops and Strain–Energy Density for Low-Cycle Fatigue-Life Predictions of the AZ31 Magnesium Alloy

Abstract

Magnesium is one of the lightest metals for structural components. It has been used for producing various lightweight cast components, but the application of magnesium sheet plates is less widespread. There are two reasons for this: (i) its poor formability at ambient temperatures; and (ii) insufficient data on its durability, especially for dynamic loading. In this article, an innovative approach to predicting the fatigue life of the AZ31 magnesium alloy is presented. It is based on an energy approach that links the strain–energy density with the fatigue life. The core of the presented methodology is a comprehensive new model for tensile and compressive loading paths, which makes it possible to calculate the strain–energy density of closed hysteresis loops. The model is universal for arbitrary strain amplitudes. The material parameters are determined from several low-cycle fatigue tests. The presented approach was validated with examples of variable strain histories.

Determination of Stress–Strain Behaviour of Magnesium Alloy AZ31 under Variable Thermomechanical Loading

“…AZ31 alloy showed cyclic softening at 150 C in the tensile region of the hysteresis loop whereas cyclic hardening was observed in the tensile region at room temperature tests in previous studies. [21][22][23] On the contrary, cyclic hardening was obtained in the compressive region of the hysteresis loop at 150 C which corresponded to the observations at room temperature [21][22][23] (Figure 8A).…”

Cyclic deformation behavior and fatigue life prediction of an automotive cast aluminum alloy: A new method of determining intrinsic fatigue toughness

“…Fatigue life prediction using strain‐energy density approaches has been studied by several researchers, 17,18,23,37,43,44 and is essential in the case of strain‐controlled fatigue tests, as the plastic strain amplitude plays a dominant role in determining fatigue behavior, including the nature of fatigue damage. Wang et al 17,23 proposed a strain‐energy density expression for Al–Si hypereutectic piston alloy fatigued at room and elevated temperatures, considering the concept of accumulated damage, and found that the expression was linked to fatigue life ( N f ) nicely.…”

High-Cycle Fatigue Behaviour of the Aluminium Alloy 5083-H111

“…In applications that use aluminium alloys frequently, it is necessary to understand the fatigue performance of the components and the effects of operating parameters on the fatigue behaviour of the analysed constructional components. A fatigue assessment can be carried out using the stress–life (S–N) or the strain–life approach, depending on whether stresses in the critical cross-sections of the analysed component are in the elastic or plastic areas [ 15 , 16 ]. In the case that only elastic stresses occur, the S–N approach is usually used to obtain the fatigue life up to the final failure of the component.…”