Tensile specimen design proposal for truss-based lattice structures

Abstract

Additive manufacturing technology offers a high degree of design freedom that promises a high structural lightweight potential where, among others, cellular mesostructures such as honeycomb or lattice structures find a growing resonance. In order to exploit the inherent lightweight potential to its greatest extent, a reliable and reproducible assessment of the mechanical properties of lattice structures for different loading scenarios is essential. The test specimens used for material characterization have to be designed so that the required mechanical properties are not falsified by the test specimen geometry or the experiment itself. The current state of the art and the corresponding norms, which are based on conventional solid material specimens, provide only vague design concepts toward appropriate lattice test specimens and are therefore not applicable. This contribution highlights the challenges met by the actual standards of the characterization of mechanical properties of lattice structures by proposing a normalized sample design for tensile specimens and a corresponding design methodology for cubic truss lattices structures. Specimen design measures based on numerically verified analytical formulations are proposed in order to systematically assess mechanical properties of lattice structures in a reliable and reproducible way and are thus recommended for future use in engineering practice.