Design, additive manufacturing, and characterisation of a three-dimensional cross-based fractal structure for shock absorption

Fractal geometries have the potential to enhance the mechanical performances of materials. However, these geometries are often unfeasible using traditional processes. Focusing on selective laser sintering (SLS), an additive manufacturing process, this study investigates the mechanical properties of a 3D Greek Cross fractal. The mechanical behaviour of the structure is numerically investigated under quasi-static and dynamic compressive loads in the case of shock-absorbing head protection equipment applications. The material model is tailored and validated by experimental results. The energy absorption results higher up to 77% than traditional foam. However, for features smaller than 1 mm, the induced process defects drastically reduce the mechanical performance of the structure.