The Radius Size Variation Effects on Fatigue Strength of AA6061-T6 and AA6061-O Alloys

Abstract

This research ensured the effects of radius variation on fatigue – life of AA6061-T6 and annealed alloy, AA6061-O. Five different sizes of radius (1, 2, 4, 8, and 16) mm were studied using Neuber notch factor (Kf) instead of the theoretical stress concentration factor (Kt). The numerical modeling was adopted using ANSYS Workbench 15 to evaluate the radius size effectiveness on strain and stress distribution, while the experimental procedure carried out to determine the strain-life constants for analytical calculations. The results show that the reduction in the radius leads to increase stress, while the strain remains close to each other with the variations of radius for both alloys. The decrement in stress and strain values for annealed specimens were observed in comparison with base alloy. The transition life (NT) was decreased whenever the radius decreased in both alloys. The fatigue life of annealed specimens increased for all values of radius compared to the specimens without annealed. The comparison of the fatigue life between the experimental and numerical results shows that the experimental results have more than those obtained by numerical estimation and this indicated the validity of the numerical approach.

Hardness measurements as a technique for measuring accumulated fatigue damage

“…Generally, it does not seem that the fatigue capacity is reduced, nor is this discussed by the authors (Ye et al, 1996(Ye et al, , 1998Ye and Wang, 2001;Drumond et al, 2021;Miroslav et al, 2017). This might be due to the indentation being so small that the LRS and the notch effect are not large enough to have an effect on the total fatigue life, as is known for small notches in relation to the theory of critical distances (Susmel, 2008;Saleh et al, 2019;De Oliveira Miranda et al, 2019;Navarro et al, 2021). In fact, the theory states that the highest stress at a notch is not necessarily what defines the fatigue capacity, but it is the stress at a certain depth (point method) or, effectively, at an area behind the notch (line method) which governs.…”

“…, 2017). This might be due to the indentation being so small that the LRS and the notch effect are not large enough to have an effect on the total fatigue life, as is known for small notches in relation to the theory of critical distances (Susmel, 2008; Saleh et al. , 2019; De Oliveira Miranda et al.…”