Additive manufacturing with fused filament fabrication (FFF) allows a cost-effective production of complex geometries, even in small batches. To expand its use from the manufacturing of prototypes to the production of ready-to-use components, strength and resilience of the additive manufactured components must be improved. The technology-related anisotropy of the material properties, such as Young's modulus and tensile strength, depends on the design of the filling pattern. Weak points include the interpath adhesion of the individual print paths. Depending on the printing orientation and the infill density of FFF-produced PLA samples, there are considerable differences in tensile strength. Similar to fiber composites, the resilience of printed paths under tension or compression in printing direction is substantially greater than transverse to it or under shear stress.
The complex geometry of components promotes inhomogeneous stress distributions in terms of size and direction in the component. As an examplary case, the stress distribution in a tensile loaded plate with a hole was investigated in more detail. Based on the load path orientation of naturally occurring fibers, the orientation of the main stress trajectories was determined using CAIO and the printing paths for additive manufacturing were oriented accordingly.
In addition to the flexibility of FFF in terms of printable geometries, the lightweight potential is also a key advantage of the manufacturing process. In order to exploit this potential, the perforated tensile specimen was adapted using another optimization process inspired by nature. The Soft Kill Option (SKO) is a topology optimization which virtually removes material in weakly loaded areas. As a result, structures were generated in which areas with load-bearing print paths were maintained and lower loaded areas were only filled with a low infill density. This enables high load-bearing capacity despite considerable material savings.