Tensile and fatigue failure of 3D printed parts with continuous fibre reinforcement

Abstract

This paper introduces a design methodology used to integrate continuous fibre reinforcement into AM polymer parts with the aim of improving their mechanical properties. Tensile and low-cycle fatigue (LCF) testing of reinforced parts is carried out for a range of load conditions and strain rates. Physical testing showed that it was possible to improve the strength of parts by 400% and cycles to failure by 42,800% with the addition of 5% carbon by weight. Logarithmic load/cycle relationships were found also samples showed significant variability in the number of cycles to failure. No correlation between the density of the polylactic acid (PLA) infill and the tensile strength or LCF life. Access holes used to thread the fibre into the reinforcement channels were identified as stress concentrators initiating cracks in the PLA and separation of the reinforcement from the PLA part.