  Auxetic materials are a novel class of mechanical metamaterials which exhibit
an interesting property of negative Poisson ratio by virtue of their
architecture rather than composition. It has been well established that a wide
range of negative Poisson ratio can be obtained by varying the geometry and
architecture of the cellular materials. However, the limited range of stiffness
values obtained from a given geometry restricts their applications. Research
trials have revealed that multi-material cellular designs have the capability
to generate range of stiffness values as per the requirement of application.
With the advancements in 3D printing, multi-material cellular designs can be
realized in practice. In this work, multi-material cellular designs are
investigated using finite element method. It was observed that introduction of
material gradient/distribution in the cell provides a means to tune cellular
stiffness as per the specific requirement. These results will aid in the design
of wearable auxetic impact protection devices which rely on stiffness gradients
and variable auxeticity.
