The impact of defects on tensile properties of 3D printed parts manufactured by fused filament fabrication

Fused Filament Fabrication (FFF) is a popular 3D printing process that has gained interest from industry in a wide range of applications. This research work studies directional properties of FFF 3D printed PLA specimens per ASTM D638-14. Tensile strength, modulus, and failure strain of specimens along and transverse to the printing direction are evaluated. It is observed that FFF 3D printing introduces anisotropic behavior to the manufactured part, e.g. tensile strength of 57.7 and 30.8 MPa for loading along and perpendicular to the printing direction, respectively. FFF 3D printers, like other automated manufacturing techniques, introduce defects into fabricated parts considering their tolerances, e.g. in the form of missing materials leading to gaps. This study investigates the impact of gaps on tensile strength, modulus, and failure strain of 3D printed parts. Compared with the baseline, 20.5% reduction in tensile strength, 9.6% in modulus, and 11.5% in failure strain are observed due to missing extrudates (gaps) transverse to the loading direction. Experimental results from this study can be used as input data for Finite Element (FE) simulation and its verification.