Comprehensive and Comparative Characterizations of Tensile Properties and Fracture Mechanisms of <scp>3D</scp> Printed Multifunctional Carbon‐Fiber and Metal‐Filled <scp>PLA</scp> Composite Parts

ABSTRACT This work presents a comprehensive and comparative study of tensile properties and fracture mechanisms of multifunctional carbon‐fiber and metal‐filled PLA composite components fabricated by fused deposition modeling (FDM). Seven PLA composites, including carbon‐fiber, brass, bronze, copper, iron, stainless steel, and aluminum PLAs, are evaluated and compared against pure PLA. Tensile tests are conducted to evaluate key mechanical properties: tensile strength, yield strength, modulus of elasticity, elongation rate, and energy at break. The results show that while the addition of fillers introduces desired functionalities such as thermal and electrical conductivities or magnetism, it sacrifices mechanical performance. Specifically, carbon‐fiber PLA exhibits increased stiffness but significantly reduced tensile strength, ductility, and toughness, whereas bronze and copper PLA composites show moderate gains in ductility or toughness at the expense of strength and stiffness. Scanning electron microscopy (SEM) analysis revealed that filler inclusion significantly alters fracture surface morphology, with varying degrees of porosity, filler detachment, and interfacial damage. These fracture characteristics are closely tied to filler type, dispersion, and matrix adhesion, which critically affect the mechanical responses under tensile load. This study provides valuable insights into the mechanical properties and their failure mechanisms in the 3D printed multifunctional PLA composite components.