Investigating the Effects of Geometrical Parameters of Re-Entrant Cells of Aluminum 7075-T651 Auxetic Structures on Fatigue Life

In this study, the effects of two geometrical parameters of the re-entrant auxetic cells, namely, internal cell angle (θ) and H/L ratio in which H is the cell height, and L is the cell length, have been studied on the variations of Poisson’s ratio and fatigue life of Aluminum 7075-T6 auxetic structures. Five different values of both the H/L ratio and angle θ were selected. Numerical simulations and fatigue life predictions have been conducted through the use of ABAQUS (version 2022) and MSC Fatigue (version 11.0) software. Results revealed that increases in both the H/L ratio and angle θ improved the average value of Poisson’s ratio. Increasing the H/L ratio from 1 to 1.4 and θ from 50° to 70° increased the values of Poisson’s ratio, respectively, 7.7% and 80%. In all angles, increasing the H/L values decreased the fatigue life of the structures significantly. Furthermore, in all H/L values, an increment in θ caused a reduction in fatigue life. The effects of H/L and θ parameters on fatigue life were dominant in the low cycle fatigue regime. Results also showed that the H/L ratio parameter had greater influence as compared to the θ angle, and the structures with higher auxeticity experienced higher fatigue resistance. It was found that the auxetic property of the structure has a direct relationship with the fatigue resistance of the structure. In all samples, structures with greater auxetic property had higher fatigue resistance.