Engineering Deformation and Failure in Diamond Triply Periodic Minimal Surface Lattices via 3D Wall‐Thickness Grading

Among the different lattice structures, the one based on triply periodic minimal surface (TPMS) is characterized by the absence of sharp angles, which guarantees superior mechanical properties if compared to beam-based structures. The mechanical response of these structures depends on the geometry of the guiding surface and the wall thickness, which is typically considered constant throughout the structure. On the contrary, this work investigates the modulation of the mechanical response of the diamond TPMS structure through the graduation of the wall thickness, with four different patterns: vertical, diagonal, cross, and core. For each of these structures, samples are produced with the powder bed fusion with electron beam additive manufacturing technique. Morphological characteristics of the structures are measured using X-ray computed tomography. These data are then correlated to the mechanical properties obtained from compression tests and the deformation behavior obtained from digital image correlation analyses. The results show that 3D wall thickness gradation can be successfully adopted to modulate the mechanical and deformation behavior of the structures. Moreover, structures with a graded wall thickness provide improved energy absorption capabilities and show the possibility to tune energy absorption as a function of the adopted gradation pattern and thickness.