Anisotropic mechanical properties of Selective Laser Sintered starch-based food

The characteristic layer-by-layer structure of a Selective Laser Sintered food product inherently results in anisotropic mechanical properties which depend on the laser sintering parameters. Tailoring these mechanical properties by the printing process enables food customization. The mechanical behavior and microstructure of printed starch-based food were characterized by means of uniaxial compression testing and Computed Tomography. Two directions were considered: the build direction and the principal in-plane direction. By increasing the area energy density from 14 J/cm² to 82 J/cm², the stiffness in build direction was more than tripled, whereas the stiffness in the in-plane direction remained unaffected and the fracture stress was more than doubled. Moreover the ductility in the build direction decreased. These effects are a combination of the change in microstructure, with average relative density ranging from 42% to 50%, and a change in local mechanical properties. In-situ compression tests revealed heterogeneous crack propagation in the material.