eng Science and Education Publishing American Journal of Mechanical Engineering 2328-4110 2026-01-08 14 1 1 6 10.12691/ajme-14-1-1 AJME20261411 article Saeed Al-Noman 1 Somia Alfatih M. S. 1 Mohammed Ghazi Gronfula 2 Galal Al-Mekhlafi 3 Mohammed Y. Abdellah Mohammed.ahmad@alasala.edu.sa 3 Abdulmajid AlAliw 3 Mohammed K. Hassan 4 Mechanical Engineering Department, College of Engineering, Alasala Colleges, Dammam 31483, Saudi Arabia Department of Electrical Engineering, College of Engineering, Alasala Colleges, Dammam 32324, Saudi Arabia Department of Civil Engineering, College of Engineering, Alasala Colleges, Dammam 32324, Saudi Arabia Industrial Engineering Department, College of Enineering and Computer Science, Mustaqbal University, Buraydh, Qassim, 51411, Saudi Arabia 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¡Ìm 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. https://pubs.sciepub.com/ajme/14/1/1/ajme-14-1-1.pdf 3D printing / Additive manufacturing Carbon fiber reinforced polymer (CFRP) Fracture toughness Polyamide 12 (PA-12/Nylon 12) Damage tolerance / Failure analysis