Investigation of impact and compression behaviour of polymer composites for foot prosthesis through fused filament fabrication

Abstract

The loss of a lower limb greatly impacts an individual's mobility, underscoring the critical need for prosthetic feet as a functional solution. However, the production of prosthetic feet poses challenges due to the complexity of process variables and materials used. This study investigates the effects of key process parameters – nozzle diameter (ND) and print speed (PS) on the compression and impact performance of four materials: polylactic acid (PLA), carbon fibre-reinforced PLA (PLA-CF), Acrylonitrile Butadiene Styrene (ABS), and CF-reinforced ABS (ABS-CF). These materials were fabricated through fused filament fabrication (FFF) and subjected to compression and impact testing, with detailed analysis of failure morphology. Statistical methods, including Taguchi's methodology, were used to assess how these process parameters influence the compression and impact performance. Experimental results reveal that ABS material achieved the highest impact strength (IS) of 50.32 kJ/m² with 0.6 mm ND and PS of 30 mm/s, while PLA-CF exhibited that of 52.47 MPa under the same conditions. Taguchi's statistical analysis identified ND as the most influential factor, followed by PS and filament material. Based on this analysis, a prosthetic foot was fabricated using PLA-CF with a 0.6 mm ND and a PS of 30 mm/s, demonstrating significant improvements in compressive and IS. This research provides a robust framework for optimising FFF parameters to enhance the structural performance of prosthetic feet, paving the way for advanced, cost-effective solutions in lower-limb prosthetics.