Mechanical Performance and Crack Propagation Resistance in 3D-Printed Nylon-Carbon Composites

This study investigates the fracture toughness of 3D-printed Polyamide 12 (PA-12) reinforced with carbon fiber. Tensile tests demonstrated an average ultimate tensile strength of 74.24 MPa. Compact tension tests on specimens (W=14 mm, B=4 mm, a=8 mm) revealed a critical load of 1.8 kN. The fracture toughness (KIC) was calculated as 36.8 MPa√m following ASTM E399 standards. Using an experimental elastic modulus of 5 GPa typical for carbon fiber reinforced PA-12 composites, the corresponding critical strain energy release rate (GIC) was determined to be 245 kJ/m². This substantial fracture resistance, combined with the observed mixed-mode failure mechanisms including fiber bridging and matrix deformation, indicates that 3D-printed PA-12 carbon fiber composites offer promising damage tolerance for structural applications.