Designing and 3D printing continuous fibre-reinforced composites with a high fracture toughness

The translaminar fracture toughness determines in many cases the damage tolerance of composite components, and this property is strongly influenced by the microstructure. A finite element model was developed that can aid in the optimisation of the microstructure for maximising the translaminar fracture toughness of composites hybridised at the tow level. The model proved that the toughness is increased when the crack has to grow through an interface between carbon and glass in a hybrid composite. This implies that the microstructure can be optimized to maximize the translaminar fracture toughness. Hybridisation at the tow level is now possible by using micro-tow placement machines. Therefore, samples were 3D-printed with continuous fibres. Therefore, samples were 3D printed with continuous fibres. Compact tension tests indicated that the toughness can indeed be increased by fibre-hybridization. This provides new avenues for improving the damage tolerance of composite materials.status: publishe