A comprehensive experimental investigation on mechanical properties and fracture morphology of particulate composites via material extrusion-based 3D printing

Abstract

Mechanical properties and fracture morphologies of Poly-Lactic acid (PLA) neat and composites (PLA reinforced with Aluminium, Copper, Carbon fibres and Brass) developed by Material Extrusion based Additive Manufacturing technique were studied to consolidate the comprehensive data for various applications. In the current study, printing parameters viz., layer height, print angle and print speed were varied to form the arrays of experimental trials to estimate the Tensile (Ultimate Tensile strength, young's moduli) and Flexural (Maximum bending strength) properties. Further, the study emphasized on fracture morphologies and categorized the types of fractures within the PLA neat and composite samples via Field Emission Scanning Electron Microscope (FESEM). An analytical model was adopted for a qualitative validation of results of micrographs for estimating the tensile and bending strengths.Results showed that the percentage improvement in the young's modulus was relatively higher for carbon fibre and brass reinforced composites in comparison to the other counterparts. It was conclusive from fracture morphology that the Intra-laminar type of fracture was prominent. However, PLA + Carbon Fibre (CF) samples exhibited Trans-laminar type of fracture, owing to their higher aspect ratio. Also, the composite samples exhibited better strengths during flexural test, in comparison to the tensile test. Optimization plots showed that the print angle was the most dominant factor influencing the strength values.