Die-Less Forming of Thermoplastic- Matrix, Continuous-Fiber Composites

Abstract

A die-less forming process is described which is intended to be an eco nomical method for manufacturing large, complex-shaped components from thermoplastic matrix, continuous-fiber composite materials. The concept is specialized to tapered shapes which are singly curved, long in their straight direction, and of arbitrary variable cross section along their length. An array of universal, computer-controlled rollers generates such shapes from initially flat laminates or stacks of prepreg sheet. Heating and bending of the material are strictly local operations occurring only within a small active zone at any one instant, thereby eliminating the need for fixed tooling and for large autoclaves or presses. The rollers are controlled using a "kinematically admissible bending" algorithm which requires interply sliding only in the local hot zone. Despite the fact that all of the regions not being formed are cold and rigid, the fibers of the composite are not forced to change length. Experimental verification to date includes: (1) rapid, local, through-thickness induction heating of carbon fiber, polymer matrix composite workpieces, and (2) kinematically- admissible bending of preconsolidated thermoplastic matrix laminates to simple singly- curved shapes, using a "near-term demonstration" forming machine. Tension superim posed during such bending operations has been shown to be useful for maintaining good fiber alignment.

Induction Spot Welding of Metal/CFRPC Hybrid Joints

“…Welding of thermoplastic fiber reinforced polymer composites means joining by melting the thermoplastic polymer, diffusion or adhesion of molecule chains at the bonding line and reconsolidation under pressure . Specially for fiber reinforced polymer composites (FRPC) welding seems to be an ideal joining technology and compared to other heating mechanisms, induction heating is characterized by contact free, fast, and locally concentrated energy input directly into the laminate …”

Experimental and Numerical Characterization of Spot Welded Hybrid Al/CFRP‐Joints on Coupon Level

“…[8,9] The joining partners are treated (corundum-blasting and an additional polymer sheet of 100 mm) before joining to improve the surface area. The metallic joining partner is treated by corundum-blasting and an additional polymer sheet of 100 mm is used in the welding zone to improve the bonding quality.…”

Science of composite materials

“…Die-less forming uses an adjustable array of universal, computer-controlled rollers to form an initially flat composite material into a long, singly curved part having one arbitrary cross-sectional shape at one end and another arbitrary shape at the other end. Induction heating is used to provide the local heating in die-less forming, because it enables rapid, non-contact, localized and uniform through-thickness heating [79]. The initially flat workpiece is translated back and forth along its length in a number of passes.…”