Tensile Properties Regression Analysis of FDM 3D Printed Composites with ONYX Matrix and Different Fibres

The influence of infill density, number of layers, and fibre type on the tensile mechanical properties of composite parts produced by FDM 3D printing with continuous fibre reinforcement (CFR) was investigated. Specimens made of ONYX composite material reinforced with carbon, glass, and aramid fibres were tested using a static tensile test according to ISO 527. A linear regression model was developed to correlate mechanical properties with 3D printing parameters. However, the influence of infill density could not be reliably determined due to the automatic generation of solid infill around fibre layers and at boundary layers in the utilized 3D printing software. These reinforcements provided varying degrees of enhancement, with carbon and glass fibres showing the highest increase in strength, glass fibres offering the best enhancement in fracture strain, and carbon fibres in stiffness. The obtained models for tensile strength, strain at maximum stress, and modulus of elasticity can be useful in the design of 3D printed parts, offering a simple solution for the prediction of mechanical properties.