Fatigue crack growth in the re-entrant auxetic structure

Abstract

The investigation of fatigue behaviour of the re-entrant and rotated re-entrant auxetic specimens made of Al-alloy 7075-T651 is presented in this study. In the proposed work, the influence of the orientation of the unit cell on the crack path and fatigue life were studied by using both experimental and computational approaches. In the experimental and computational approach, two geometric layouts of the base unit cell were analysed (re-entrant and rotated re-entrant structure). The Low Cycle Fatigue (LCF) tests were performed at load control with the load ratio 0.1 in tensile. In the LCF tests, five loading levels were selected and at least two tests were performed at each loading level. The same loading conditions were then applied in the computational model in the framework of the ANSYS software package. For the fatigue life calculation, the strain life approach was used, based on the Coffin-Manson model with a Morrow mean stress correction. The comparison between computational and experimental results regarding Fa − N fatigue-life curves and observed fatigue failure path showed a reasonable agreement.