3D printed continuous fibre composites: exploiting design flexibility to achieve application specific properties

In the current study, the response of continuous fibre composite structures with variable fibre topology was investigated. These structural configurations are designed to be manufactured via continuous fibre three-dimensional (3D) printing. In order to take advantage of the design flexibility afforded by 3D printing a periodic sinusoidal fibre printing pattern was introduced. It would be difficult to manufacture this type of sample using conventional manufacturing methods, however, these structures can be easily produced using commercially available continuous fibre 3D printers. In order to understand the influence of variable fibre topology the response of these structures under both axial and shear loading was investigated. For axially loaded samples a moderate fibre deviation or 'waviness' resulted in an increased failure displacement with a slight reduction in ultimate strength. For similar samples subjected to pure shear loading it was found that the fibre misalignment introduced both transverse and axial stresses. There is experimental evidence that moderate transverse compressive stresses require a larger shear stress to initiate failure, compared to the pure shear failure stress. However, the transverse tensile stresses that were introduced would effectively weaken the structure negating any benefit that would be obtained from the moderate transverse compressive stresses. Future work will focus on eliminating the transverse tensile stresses whilst introducing moderate transverse compressive stresses. If this can be achieved, the effective laminate shear strength, can be increased with no change to the mechanical performance of the constituent materials.