  A recent report on successful employment of the grain boundary strengthening
to design extraordinarily damage-tolerant architected materials (i.e.
meta-crystals) necessitates fundamental studies to understand the underlying
mechanisms responsible for the toughening and high performance of
meta-crystals. Such understanding will enable greater confidence and control in
developing high performing and smart architected materials. In this study,
buckling of lattice struts in single crystal-like meta-crystals was firstly
analysed to reveal its role in shear band activities. Shear band systems of
singly oriented meta-crystals were also identified to provide a solid basis for
predicting and controlling the shearing behaviour in polygrain-like
meta-crystals. The boundary-induced strengthening effects in meta-crystals was
found to relate to the boundary type and coherency as they govern the
transmission of shear bands across meta-grain boundaries. The obtained insights
in this study provide crucial knowledge in developing high strength architected
materials with great capacity in controlling the mechanical strength and damage
path.
