Look-ahead stress-oriented trajectory planning to improve the strength of fused filament fabricated parts

Fused filament fabrication (FFF) is a promising additive manufacturing method; nevertheless, the mechanical properties of its final products, particularly for end-use applications, still require enhancements. Combining FFF's low cost and well-established technology with enhanced mechanical properties would increase its competitiveness among other additive manufacturing methods. Similar to the well-established subtractive manufacturing methods, the majority of the trajectory planning algorithms developed for FFF, prioritize print time and dimensional accuracy. However, the effect of trajectory planning on the strength of parts produced through FFF has not received adequate attention. This paper proposes a look-ahead trajectory planning algorithm for FFF, which generates an optimized nozzle path to align the print direction with the principal stress direction. This alignment has been proven effective in increasing the tensile properties of the FFF parts. To minimize print defects, especially when printing high-viscosity materials like metals, path intersection elimination, single point elimination, and linear approximation algorithms are applied to the method. The validity of the proposed algorithm was initially tested on more convenient Polylactic Acid (PLA) specimens and was further verified by experimentations on 17–4PH stainless steel specimens.