Welcome!

 

Senior Project II Presentation:

11:20 am Friday April 27, 2007

Armstrong Hall Room 124

The College of New Jersey

2000 Pennington Rd

Ewing, NJ 08628

 

Abstract

Ankle-foot orthoses (AFOs) are prescribed for patients with gait abnormalities to control painful movements of dorsiflexion and plantar flexion. The ability of the AFO to constrain motion is dependent on material composition and structural design. There is a need to design a comfortable, light weight, aesthetically acceptable AFO that limits plantar flexion and dorsiflexion in arthritic patients whilst maintaining low production turnaround and cost.  The AFO CAD model validated in Senior Project I was the basis for parametric studies investigating fiber orientation of Kevlar 49 (Cycom 919) for an L-shape insert.  The L-shape was chosen based on superior stress and deflection reactions to a point load when compared to other geometries.  The goal of the parametric studies was to optimize orientation of Kevlar fibers to minimize overall deflection and stress along the orthosis’ lateral side.  Studies suggested that an insert at 75°/165° reduced deflection by 17% and maximum stress by 36%.  Two models were manufactured: a control (made from 3 mm subortholen) and a fiber composite model.  In the composite model, Kevlar was impregnated between 1 mm and 2 mm subortholen layers.  These models were then tested using a Materials Testing Machine for bending to validate the ANSYS results.

 

Keywords: Ankle-Foot Orthosis, dorsiflexion, plantar flexion, ANSYS, Finite Element Analysis, parametric studies, subortholen, Materials Testing Machine

 

 

Our goal is to design an ankle-foot orthosis that will limit the range of motion in dorsiflexion for arthritic patients; thus we will alleviate pain and restore stability.

•  We need to make the AFO lightweight but at the same time ensure stiffness

•  We want to keep the ankle at 90° at all points

•  The design for arthritic patients should last for as long as physically possible

•  Current manufacturing costs average $150-250, therefore we want to remain in this range

 

Design Considerations include:

•  We will want to put more support on the lateral side of the device to limit inversion and eversion

•  We might want to consider a wider neck because it has a greater stiffness

•  Graphite struts will help to absorb energy and exert a high resistance to dorsiflexion

•  Carbon fibre inserts help increase stiffness, but a strap can do the same thing at a lower price

•  Vertebral design may be effective, but it may be too difficult to engineer