Abstract: A method of fabricating a composite structure having at least one skin molecularly bonded to a core. A skin is provided of reinforcing fibrous material and a thermoplastic matrix. The skin is thermoformed to the general exterior shape of the composite structure. A core having a thermoplastic matrix complementary to the matrix of the skin is molded into the general shape of the composite structure. The skin and the core are placed in juxtaposition in a final forming mold. A thermoplastic material is injected into the final forming mold under isostatic conditions. The thermoplastic material is complementary to the thermoplastic matrices of the skin and the core.

Abstract: A composition for a pressure molded core of a composite structure, including a thermal plastic resin. The composition also includes a component to reduce the coefficient of thermal expansion, a lightweight high compressive strength filler, and a blowing agent. The thermoplastic resin may be polyetheretherketone, the component may be carbon fibers, and the filler may be hollow glass microspheres.