Static and fatigue behaviour of continuous fibre reinforced thermoplastic composites manufactured by fused deposition modelling technique

In additive manufacturing (AM), the thermoplastic parts made by FDM present lack of strength and low stiffness, as required for fully functional and load-bearing parts. Due to this restriction, a new technology to reinforce with fibres the thermoplastic filaments was developed over the last years. Continuous fibre reinforced thermoplastic composites (CFRTPC) printers are elevating this technology to a whole new level in terms of efficient production and mechanical properties. Static mechanical properties, as well as fatigue behaviour, were studied since in these types of loads a wide range of engineering dynamic applications can be envisaged. Tensile tests were performed to characterise the static mechanical properties. Fatigue tests were done to analyse the durability behaviour of the FDM composite materials, and the fracture surface was analysed by SEM microscopy. The results showed that carbon fibre isotropic layers had the higher ultimate tensile stress, with 165 MPa. From fatigue tests, stress vs. number of cycles curves (S vs N-f) in the temporary life zone were obtained. It was observed from the results that specimens with nylon matrix, triangular filling pattern and matrix density of 20%, reinforced with carbon fibre at 0-degrees, showed better fatigue performance, increasing significantly the number of cycles before specimen rupture. The parameters for the Basquin's equation were found (S = A.N-f(b)), with A = 206 MPa, and b = - 0,039. Accordingly, mechanical characterization of continuous fibre reinforced thermoplastic composites was investigated, which showed the potential use as a composite material for engineering applications.