Design and evaluation of composite external fixator ring

Abstract

Current work reports the design and evaluation of circular rings for Ilizarov external fixator system. A radiolucent composite material of knitted aramid fibre (and short chopped carbon) and epoxy resin is used to replace stainless steel, currently the most commonly used material. The use of a radiolucent composite material permits easier and more accurate radiographic evaluation of the healing process, and results in a much lighter system. Finite Element Method (FEM) is employed to determine the worst possible in service loading condition and modify the ring dimension accordingly. Prototype of the half ring is produced using two different fabrics. Knitted Aramid fibre (Kevlar-29) and short chopped carbon fibre is used as reinforcement for epoxy resin matrix. In-plane compressive strength and axial stiffness of the complete frame were tested according to the ASTM specification. The performance was evaluated and compared to an existing system in simulated in-service conditions.