Mechanical Characteristics of Architected Polycrystal Lattice Affected by the Orientation of Metagrain Boundary

Abstract

The orientation of internal metagrain boundary shows an important influence on shearing behaviors and mechanical performance of architected polycrystal lattice. This study designs four types of architected polycrystal lattices equipped with single boundary, multiple parallel boundaries, or multiple intersecting boundaries, with boundary orientations of 0°, 26.55°, 45°, 63.45°, or 90°. The compressive responses of these architected polycrystal lattices are investigated to reveal the effects of the boundary orientations. Especially the relations between the shearing deformation and the boundary orientation are clarified, and the underlying shearing mechanisms are discussed to provide a basis for predicting and explaining the energy absorbing capacity in the architected polycrystal lattice. For the architected polycrystal lattice consisting of +30° and −30° orientated metagrains with intrinsic shear bands of 60° and 75°, the 75° rather than 60° shear band is more likely to occur when the angle of the architected polycrystal boundary increases from 0° to 90°. Most importantly, the higher energy absorption prefers the shear band more horizontal and shorter, which can be realized by increasing the angle and the number of grain boundaries. This contributes to resisting catastrophic failure for lattice structures. These findings provide guidance for developing novel lattice structures with well‐controlled mechanical characteristics.