Linear Friction Welding of Carbon Fibre Reinforced PEEK composite

The increasing use of thermoplastic CFRP, with matrix materials such as Polyetheretherketone (PEEK), observed in twin aisle aircrafts leads to an increased demand for this material. Limited composite processing routes reveal a need for reduced costs and higher deposition rates.

Linear Friction Welding, a rapidly developing solid-phase joining process, was used in this programme for the joining of a continuous fibre thermoplastic CFRP known as Carbon/PEEK, to demonstrate process capability.Initial welding trials were carried out on pure PEEK to establish the feasibility of linear friction welding using this matrix material, looking first for a stable plasticisation state. These trials were followed by the manufacture of the Carbon/PEEK laminate and matching tooling design. Last, Carbon/PEEK work-pieces were linear friction welded using parameters drawn from the pure PEEK welding programme.

Adhesive bonding, which requires lengthy and careful special surface preparation, offers carbon/PEEK single lap shear joints that have been tested to approximately 60% of the parent material.

Careful design of the welded Carbon/PEEK coupons allowed joining two workpieces without surface preparation, to achieve a lap shear strength exceeding the target set by adhesives, at of 64% of the parent material.