A three-dimensional fully auxetic cellular structure with negative Poisson’s ratio is presented. Samples are fabricated from Ti6Al4V powder via selective electron beam melting. The influence of the strut thickness and the amplitude of the strut on the mechanical properties and the deformation behaviour of cellular structures is studied.
Our
contribution demonstrates that the combination of additive
manufacturing and electrophoretic deposition offers great potential
for the future manufacturing of tailor-made catalytic structures for
continuous flow applications. A new protocol for the controlled and
homogeneous coating of both electrodes of interpenetrating porous
open cell structures (interPOCS) with layers of boehmite is presented.
Moreover, it has been found that by applying different coating voltages
in an electrophoretic deposition (EPD) process, the properties of
the obtained coating can be fine-tuned with respect to layer thickness,
density, and porosity. This offers very interesting options for optimizing
the catalysis-relevant properties from two sides by the use of the
special interPOCS support design and by adjusting the coating through
the parameters of the EPD coating process.
To investigate the influence of auxetic behavior on thermally induced stresses, finite element analysis simulations of the displacement and stress fields in locally heated three dimensional auxetic and cubic structures are compared. The simulations were carried out in Comsol for a cubic as well as a chiral array of 30 mm length in each spatial dimension (3 × 3 × 3 unit cells). The center cells of these arrays were heated for 20 s. For two boundary conditions (free and clamped), deformation mechanisms are analyzed. It is found, that the auxetic behavior can effectively reduce thermal stresses by internal node rotation and strut bending, especially for constrained (clamped) boundary conditions. A stress reduction of a factor of 3.3 in comparisons to a simple cubic cell array could be evaluated.
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