Lattice truss structures from expanded metal sheet

Metallic lattice truss structures are usually made by perforating a metal sheet with a periodic diamond pattern followed by folding at node rows to create a plate of 3D interconnected trusses. For low relative density lattices, the initial sheet material is inefficiently utilized, and the node area is small raising concerns about node bond robustness under shear or tensile loading. Here, we explore a simple approach for making open cell, pyramidal lattice truss structures with robust nodes and close to 100% utilization of the sheet material. Aluminium alloy lattices with a relative density of 5.7% were fabricated and bonded to aluminium alloy facesheets using a brazing technique. They have been tested in through thickness compression, and in both transverse and longitudinal shear. The lattice truss structures made by this approach have a normalized compressive peak strength close to the predicted maximum. The non-dimensional transverse and longitudinal shear strengths were also close to theoretical predictions. No node failures were observed during plastic shear straining up to 20%.