Design of variable-stiffness morphing skins using curvilinear continuous fibre 3D printing

Abstract A morphing skin must withstand local aerodynamic loads while remaining flexible enough to accommodate the shape changes of the morphing aircraft. The conflicting requirements can be satisfied by tuning the mechanical properties of the variable stiffness composites. In the present study, the variable stiffness composite is investigated by varying the lamina angles through 3D printing of curvilinear continuous fibre. At first, the design requirements and application scenario are introduced. The fabrication method is introduced and tensile tests are also performed to obtain the mechanical properties of the printed composite lamina. Then, the numerical model is established to explore the mechanical properties of the variable stiffness composite. Optimisation is carried out to balance the different mechanical properties. Finally, a composite sample is manufactured, which is tested to validate the proposed concept. The results demonstrate that the variable stiffness composite exhibits significant improvements in mechanical properties compared with the straight fibre composite.