Predication of the in-plane mechanical properties of continuous carbon fibre reinforced 3D printed polymer composites using classical laminated-plate theory

TLDR

The study develops a model to predict the elastic properties of continuous carbon‑fiber reinforced thermoplastic composites printed with a Markforged Two 3D printer, enabling designers to tailor in‑plane mechanical performance. Mechanical testing (tensile, shear, Poisson’s ratio) of longitudinal and transverse specimens, microstructural analysis, and orientation‑dependent modeling with classical laminated‑plate theory in LAP software were used to characterize and predict the composite’s behavior. The composite achieved a modulus of 603.43 MPa and tensile strength of 85 GPa, markedly surpassing unreinforced nylon.

Abstract

In this study in-plane mechanical properties of continuous carbon fibre reinforced thermoplastic polyamide composite manufactured using a Markforged Two 3D printing system was evaluated and compared against predicted values from classical laminated-plate theory. Strength, stiffness and Poisson’s ratio of the composite specimens were measured using tensile testing both in longitudinal and transverse direction and the shear properties were also measured. The influence of fibre orientation on mechanical properties was investigated and were compared with that of non-reinforced nylon samples and known material property values from literature. It was determined that the modulus of elasticity and tensile strength values were significantly improved to 603.43 MPa and 85 GPa respectively as compare to unreinforced nylon specimens. Furthermore, cross-sectional micrographs of specimens are analysed to observe the microstructure and fracture mechanism of the 3D printed composite. Experimentally determined values were used to predict the behaviour of the materials in different orientation using classical laminated-plate theory on the commercially available LAP (Laminated Analysis programme) software. The model developed will allow the designers to predict the elastic (mechanical) properties of 3D printed parts reinforced with fibre for components which require specific mechanical properties.