Ni bonded TiC cermet pyramidal lattice structures

Ultralight pyramidal lattice structures with a relative density (ρ̄) ranging from 1.5 to 21% have been fabricated from a Ni bonded TiC cermet and configured as sandwich panels using a mechanical snap-fit and vacuum brazing technique. The lattice structures moduli and strengths have been measured using unit cell samples during out of plane compression as a function of the lattice relative density. Two strut failure modes were observed: Euler buckling of the struts dominated the response at low density, ρ̄⩽ 1.5%, while compressive yielding failure governed the response for ρ̄> 1.5%. The measurements are shown to be well predicted by micromechanics models of these strut failure modes, and excellent agreement was achieved between experimental results and finite element predictions. When compared with other cellular lattices and topologies, snap-fit Ni bonded TiC composite pyramidal lattice structures are found to exhibit superior mechanical properties, and appear to be promising candidates for high temperature applications.