Towards standardization of tensile testing for strut-based lattices using compensated beam modeling and strain-energy-based optimization

Lattice structures are increasingly employed in lightweight, high-performance applications, where additive manufacturing allows precise tailoring of their mechanical response. However, tensile testing remains difficult due to complex geometry, anisotropy, and gripping challenges that often induce stress concentrations and premature failure. This work introduces an optimization-driven framework for the design and standardization of tensile lattice specimens, relying on a reduced-order finite element model based on compensated beam theory. The framework integrates a novel merit index based on average strain energy density to reduce mesh dependency, enabling robust and efficient two-step optimization, acting on the material distribution in the transition region and base geometry design. The optimized design ensures smooth stress transfer and minimizes localized effects. To validate the approach, a case study is conducted on a BCC lattice specimen fabricated via Multi-Jet Fusion (MJF). Experimental results in the elastic regime show less than 5 % deviation from numerical predictions, confirming the method's reliability. The proposed framework provides an efficient and accurate tool for tensile characterization of lattice structures, supporting both research and industrial applications.