  Recent advances in additive manufacturing methods make it possible, for the
first time, to manufacture complex micro-architectured solids that achieve
desired stress versus strain responses. Here, we report experimental
measurements and associated finite element (FE) calculations on the effect of
strut shape upon the tensile response of two-dimensional (2D) lattices made
from low-carbon steel sheets. Two lattice topologies are considered: (i) a
stretching-dominated triangular lattice and (ii) a bending-dominated hexagonal
lattice. It is found that strut waviness can enhance the ductility of each
lattice, particularly for bending-dominated hexagonal lattices. Manufacturing
imperfections such as undercuts have a small effect on the ductility of the
lattices but can significantly reduce the ultimate tensile strength. FE
simulations provide additional insight into these observations and are used to
construct design maps to aid the design of lattices with specified strength and
ductility.
