Freeform Fiber Alignment In a Polymer Matrix Using Conformal Electrode Field Networks

Abstract

Composite materials have been around for some time now. It is desired to manufacture light weight high strength composite parts. Fibers in an epoxy resin can be influenced to align along a desired direction such that the strength and stiffness of the part can be increased. One approach to achieving fiber alignment within a polymer matrix involves the use of electric fields. Dielectrophoresis can be used to induce fibers to rotate within a liquid such that they become aligned with the electric field lines. In this manner, fibers can be concentrated and aligned in a composite to improve the mechanical properties of the part. In order to take maximum advantage of this phenomenon, the use of freeform fabrication techniques to produce molds with conformal electrode networks is proposed. This enables designers to specify mass producible molded parts having fibers aligned in any three-dimensional spatial arrangement needed.

In order to demonstrate the idea, specimens were created in the form of 90 degree bent rods, and additional coupons were fabricated to quantify the change in mechanical properties when fibers are aligned via the conformal electrode networks. The 90 degree bent rod was cut and mounted to observe the fibers under a microscope. The images were compared with images of samples not exposed to an electric field, and a pronounced fiber alignment was readily apparent. The tensile coupons were tested, and the mechanical properties were measured.