Effect of fused filament fabrication parameters on crashworthiness studies of hydroxyapatite particle reinforced PLA composite thin-walled tubes.

Hydroxyapatite-reinforced Poly Lactic Acid (PLA) thermoplastic composite is mainly used for scaffolding and bone implant applications. They are developed using the naturally derived hydroxyapatite particles from marine industry waste, which proves to be economical and has ecological benefits towards the composite development. The mechanical and dimensional stability of the 3D printed composite can be varied based on the mineralogical and structural characteristics of the added particle reinforcement into the matrix. The present work concentrates on developing thin-walled PLA/hydroxyapatite composite tubes using fused filament fabrication technology by the novel extruded PLA/hydroxyapatite composite filament. For the current study, the hydroxyapatite particles are derived from crab shell waste, and the tube was fabricated with a wall thickness of 4 mm. In this work, the prepared composite tube's crashworthiness behavior and dimensional stability are studied concerning various experimental parameters such as build orientation, line width, printing speed, nozzle temperature, and layer height. The experimental parameters were optimized using the Taguchi optimization technique. The results showed that the optimized parameters for the maximum compressive strength would be a build orientation of 90°, a lower layer height of 0.1 mm, a nominal printing speed of 20 mm/s, a moderate nozzle temperature of 220 °C, and a line width of 0.2 mm. The rank of influential experimental parameters for the output response, such as compressive strength, was nozzle temperature > build orientation > layer height > line width > printing speed. Macroscopic observation of the failure samples shows that 90° oriented composites are subjected to compressive loading, and the progressive mode of fracture takes place, leading to the crushing of composites. This progressive fracture mode develops the highest compressive strength compared to other fracture modes and build orientations.