Biomechanical optimization of printing paths in Fused Filament Fabrication

Additive Manufacturing has progressed from rapid prototyping to producing functional components. Extrusion based processes like Fused Filament Fabrication (FFF) enable fast, cost-effective fabrication of complex geometries, particularly in small quantities. However, the layer-by-layer structure leads to orthotropic mechanical properties, with strength and stiffness highest along print direction and decreasing in deviating directions. Designing robust components thus requires accounting for anisotropy and optimizing the printing paths themselves. Computer Aided Internal Optimization (CAIO), inspired by tree growth, aligns orthotropic axes with local principal stress, to match material strength and load paths. For a tensile-loaded perforated plate, the resulting orientation of orthotropic axes was translated into printing paths. Optimized specimens printed out of Polylactic Acid showed up to 28% higher tensile strength, compared to industry-standard printing patterns using the same material amount. The Soft Kill Option (SKO), based on bone growth principles, was applied for topology optimization, targeting minimal mass and maximum stiffness. SKO optimized specimens achieved 25% weight reduction and a 5% increase in tensile strength over industry-standard prints. Compared to standard specimens of equal mass, breaking loads increased by nearly 70%. These results demonstrate that CAIO and SKO significantly enhance mechanical performance and suggest strong potential for manufacturing highly robust components.