Pyramidal lattice truss structures with hollow trusses

A method for fabricating pyramidal lattice structures with hollow metallic trusses has been explored. A periodic diamond hole pattern sheet consisting of 304L stainless steel hollow tubes was made by an alternating collinear Jay-up process followed by vacuum brazing. The array was then folded at the nodes to create a periodic pyramidal cellular metal lattice and was then bonded to face sheets by a second vacuum brazing process. The out-of-plane compression properties of this hollow truss lattice structure have been investigated and compared to a similar lattice made with the solid trusses. In both cases, the peak strength is found to be governed by inelastic truss buckling. The compressive strength of a hollow lattice with a relative density of 2.8% was approximately twice that of a solid pyramidal lattice of similar relative density. The increased strength resulted from an increase in the buckling resistance of hollow trusses because of their higher radius of gyration. (c) 2005 Elsevier B.V. All rights reserved.