Energy absorption and mechanical performance of 3D printed Menger fractal structures

Porous structures fabricated through selective laser melting (SLM) are prospective candidates for high-energy-absorbing applications due to their tuneable mechanical properties. The Menger Fractal Cube (MFC) is a unique fractal cube formed through iterative removal of smaller cubes from a larger one. It is distinguished by its intricate self-similar pattern of voids and cubes repeating at diminishing scales, resulting in a lightweight and highly complex structure. Using AlSi7Mg, compression experiments and simulations investigated MFCs with three different orders. Digital image correlation was used to identify the stress concentration areas within the elastic deformation range of MFCs, and the relationship proposed in the Gibson-Ashby model was successfully implemented. The nature of the collapse, fracture mechanism, and energy absorption behaviour were investigated with the plateau and densification region deformation profiles. The highest level of specific energy absorption was recorded in third-order MFC, whereas the maximum densification displacement and energy absorption efficiency were observed in the fourth-order MFC. The test results also showed that the peak force decreased with increasing fractal order, suggesting that high-order MFCs can be employed as protective sacrificial structures that reduce force transmission to the protected structures. In brief, MFCs demonstrate outstanding energy absorption properties and hold promising potential for a wide range of structural applications that require energy-damping characteristics.