Very recently, thermoplastic pultrusions, inc., has developed the capability to pultrude ultra high-modulus graphite fiber/powdered thermoplastic resin prepregs into high quality composites without damaging the fibers. Since the pultruded composites are already consolidated, reforming does not require the high pressures and long durations typical of autoclave fabrication. Hence, it should be possible to layup a component from pultruded stock materials onto a mandrel which would fit inside another metal shell. The key will be to make the inner and outer mandrels out of materials having different coefficients of thermal expansion. By having an inner mandrel that can expand more than the external shell, virtually any pressure could be exerted on the composite sandwiched in between in an inexpensive oven. The goal of the proposed project will be to utilize the unique reforming properties of thermoplastic composites to allow simple fabrication of high-modulus high-strength tubular composite components via this novel differential thermal expansion (DTE) process.
