A Digital and Additive Manufacturing Approach for the Fabrication of Custom Orthoses

The traditional manufacture of orthotics from thermoplastics, which involves plaster casting and vacuum forming, is time-consuming and largely manual, thus prone to error.
$\mathbf{3D}$
printing provides healthcare professionals involved in the prescription of orthotic and prosthetic devices the opportunity to develop novel and custom designs. With the advancement of additive manufacturing, carbon fibre-reinforced polymer composites have been used in the manufacture of orthosis mainly due to their high strength-to-weight ratio. Orthoses made from carbon fibre-reinforced polymer (CFRP) composites have good energy storage and return capacity and are therefore able to facilitate high-intensity activities. In this study, a finite element coupled analysis was used to model and predict the dynamic properties of an ankle foot orthosis printed from carbon fibre-reinforced Polyamide 12 (PA12CF) composite. The process-induced residual stress, porosity and fibre orientation are mapped onto a structural model and the flexural strength is estimated. Using the optimum printing parameters, which maximise the flexural strength, a prototype ankle-foot orthosis (AFO) was printed. This is part of an ongoing project, and the development of a test rig for the AFO is under construction.