Design method for individualised 3D printed lattice shoe midsoles

Additive manufacturing has enabled the production of individualised 3D printed shoe soles with improved properties. A promising approach is to use lattice structures that have high energy absorption properties and low weight. A design method of a cellular shoe midsole with optimised strut diameters of lattice structures is proposed. The shoe sole model is obtained by re-modelling a 3D scan of a foot to ensure a customised fit. The optimisation of strut thicknesses is based on a simplified stress distribution acting on the shoe sole during walking or running, using finite element simulations. Therefore, the optimal strut thickness for each region of the sole can be determined and adjusted. Two types of lattice structures with different topology and thus significant variations in stiffness are chosen, resulting in a wide range of required strut thicknesses. The developed design process allowed for the creation of a 3D printed shoe sole with improved strut thicknesses and a customised fit. The resulting cellular shoe soles are additively manufactured and experimental compressive tests are conducted to investigate the mechanical behaviour and differences between the shoe soles with the corresponding lattice types. The results show that both shoe soles have a similar behaviour under compression. The design tool developed has the potential to improve foot health and comfort, especially for people with foot problems, as all parameters affecting the performance of a shoe sole can be adjusted. However, more research is needed to fully understand the durability and performance of these shoe soles in real-world conditions.