Press forming a 0/90 cross-ply advanced thermoplastic composite using the double-dome benchmark geometry

A pre-consolidated thermoplastic advanced composite cross-ply sheet comprised of two uniaxial plies orientated at 0/90° has been thermoformed using tooling based on the double-dome bench-mark geometry. Mitigation of wrinkling was achieved using springs to apply tension to the forming sheet rather than using a friction-based blank-holder. The shear angle across the surface of the formed geometry has been measured and compared with data collected previously from experiments on woven engineering fabrics. The shear behaviour of the material has been characterised as a function of rate and temperature using the picture frame shear test technique. Multi-scale modelling predictions of the material’s shear behaviour have been incorporated in finite element forming predictions; the latter are compared against the experimental results

Induction melt thermoforming of advanced multi-axial thermoplastic composite laminates

The viability of using induction heating to facilitate the wrinkle-free forming of multi-axial pre-consolidated advanced thermoplastic composites over complex geometries is explored. The research focuses on the use of tin as a medium to both heat and lubricate the forming laminate. Initial tests demonstrate the viability of the fundamental ideas of the process; induction heating is used to melt the tin sheet, which is then shown to melt the matrix phase of carbon-nylon composite laminates when stacked in a hybrid composite/tin layup. A novel low-cost reconfigurable multi-step forming tool is used to demonstrate how most of the tin can be squeezed out of the layup prior to consolidation. The multi-step tool can be augmented with segmented tooling to rapidly manufacture composite parts of high geometric complexity. In this investigation, a 'ripple' geometry containing three 'cavities' is used to demonstrate the technique. Tests demonstrated that at least three sheets of inter-laminar tin can be simultaneously melted using the induction heating system. Initial results indicate complex geometries can be formed with minimal wrinkling while removing interlaminar tin