Mechanical properties of a node-interlocking pyramidal welded tube lattice sandwich structure

A novel node interlocking assembly method is proposed for manufacturing a new type of pyramidal welded tube lattice sandwich structures with enhanced mechanical properties, consisting of millimeter-scale tubular truss cores and single layer solid face sheets. Sandwich panel specimens with relative densities ranging from 1.99-5.47% are fabricated from a stainless steel alloy. Mechanical responses and energy absorption are tested under through-thickness compressive and transverse shear loading. A three-stage nominal compressive stress strain model for as-brazed stainless steel welded tubes with different wall thicknesses is proposed to accurately predict the inelastic buckling strength of the lattice cores as well as the nonlinear material behaviors up to a nominal strain level on the order of 0.23. In general, the tested compressive and shear stiffnesses and strengths are in good agreement with analytical predictions. By comparison with numerous competing periodic cellular topologies, the node-interlocking pyramidal welded tube lattices exhibit significantly better overall mechanical properties, especially for specific strengths and specific energy absorptions.