Experimental characterization of the mechanical properties of metamaterials

The mechanical behavior of metamaterials is ruled by a complex interplay of unit cell geometry, relative density, manufacturing-induced defects, and loading conditions, necessitating rigorous experimental validation. This chapter comprehensively reviews experimental methodologies for assessing the monotonic, fatigue, and energy absorption properties of lattice structures. It first examines compression and tensile testing, emphasizing specimen geometry, boundary conditions, and unit cell design. Given the challenges associated with full-scale lattice testing, the use of miniaturized specimens is discussed as a potential means to isolate strut-based sub-unital elements to inspect key factors such as microstructural effects, surface roughness, and defect distribution, and their impact on quasi-static and fatigue properties. The chapter then discusses fatigue behavior, highlighting the influence of manufacturing parameters, print orientation, and postprocessing. Finally, it addresses energy absorption and how unit cell topology affects crashworthiness and impact resistance. Key challenges in standardization and scalability are also considered, underscoring the need for further research to refine testing protocols and numerical–experimental correlations.