Ultrasonic weld-bonding of thermoplastic composites

A method for ultrasonic welding of polymeric workpieces, the method comprising:

• disposing a first region of a first thermoplastic polymer workpiece and a second region of a second thermoplastic polymer workpiece between an ultrasonic horn and an anvil of an ultrasonic welding device, wherein the first thermoplastic polymer workpiece is adjacent to the ultrasonic horn and the second thermoplastic polymer workpiece is adjacent to the anvil, wherein the first thermoplastic polymer workpiece has a preformed deformation in the first region, the entire preformed deformation being in the first region, the preformed deformation defining a depression on a first side of the first thermoplastic polymer workpiece and a protrusion on a second side of the first thermoplastic polymer workpiece, and at least one of the first thermoplastic polymer workpiece and the second thermoplastic polymer workpiece has an adhesive precursor layer applied thereto such that the adhesive precursor layer is disposed directly between and in direct contact with a third region of the first thermoplastic polymer workpiece and a fourth region of the second thermoplastic polymer workpiece, the third region being non-overlapping with the first region and the fourth region being non-overlapping with the second region, wherein the deformation has a cross-sectional shape that corresponds to a cross-sectional shape of the ultrasonic horn and the ultrasonic horn is seated within the depression of the preformed deformation to provide a predetermined bondline between the first thermoplastic polymer workpiece and the second thermoplastic polymer workpiece;
• and
• applying ultrasonic energy from the ultrasonic horn to create a weld nugget between the first region and the second region, wherein an assembly of the first thermoplastic polymer workpiece and the second thermoplastic polymer workpiece having the weld nugget has a green strength so that the assembly can be further processed immediately.