ACTS-3D: Advanced continuous tow shearing for manufacturing of defect-free 3D complex composite parts

Continuous Tow Shearing (CTS) is a novel fibre steering process developed to overcome the inherent limitations of Automatic Fibre Placement (AFP), which relies on in-plane bending deformation of the tow in fibre steering process. Unlike AFP, CTS utilises in-plane shear deformation of the tow, and it has proven effective in eliminating fibre steering-induced defects on doubly-curved surfaces. However, challenges remain with more complex layups that cannot be perfectly tessellated using finite-width tows. This work introduces an advanced CTS process for three-dimensional complex geometries (ACTS-3D), incorporating a novel path planning and head control algorithm, along with an on-the-fly tow-width control (TWiC) mechanism. The path planning algorithm tessellates the surface using an improved pin-jointed strip (PJS) model that discretises the geometry of the individual variable-width tow. The local orientations of the CTS head, its nip points, and the local tow widths along the layup path are computed based on the spatial arrangements and lengths of the tow width elements within the PJS. To validate the feasibility of ACTS-3D process, a CTS prototype head with an integrated TWiC device was mounted on an industrial robot, producing a multi-layered fibre-steered preform on a doubly curved tool surface. Visual inspection and laser surface scans of the preform confirmed the potential of ACTS-3D for defect-free manufacturing of fibre-steered composite parts with complex geometries, by synchronously utilising the new head control and tow-width control.