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The Stress Distribution Property on the Customized Ankle Foot Orthoses During the Gait Period  

Choi, Young-Chul (대구대학교 재활과학대학)
Rhee, Kun-Min (대구대학교 재활공학과)
Choi, Hwa-Soon (포항공과대학교 산학협력연구소)
Publication Information
Journal of the Korean Society for Precision Engineering / v.25, no.3, 2008 , pp. 165-175 More about this Journal
Abstract
An ankle-foot orthosis(AFO) is a brace for persons with gait disabilities to support or replace the function of ankle joint. Ankle-foot orthoses(AFO's) are usually prescribed to alleviate the drop-foot by constraining the excessive plantar flexion. The shape and the strength of the AFO are often based on 'trial and error' due to a lack of knowledge of the stress distribution in the AFO. In this study, an improved stress-freezing method was proposed to measure the stress distribution characteristics in the AFO. As a result, a photoelastic material with low freezing temperature was developed to measure the stresses under a person's direct contact loading condition. The three-dimensional stress-1rozen photoelastic models of AFO's for five stages of stance phase such as heel contact, foot flat, mid stance, heel off, and toe off were produced. The results of photoelastic analysis revealed that the stresses developed in the AFO were varied considerably from tensile to compressive or vice versa, during walking. At the posterior part of ankle joint in the AFO, the maximum compressive stress of 1.81MPa was observed in the mid stance, and the maximum tensile stress of 0.74MPa was observed during heel contact. The overall stress levels in the AFO's were low in the toe off phase. The results suggested that the posterior part of ankle joint might be the most fragile part in the AFO.
Keywords
Ankle foot Orthosis; Photo-elasticity; Stress freezing method;
Citations & Related Records
Times Cited By KSCI : 3  (Citation Analysis)
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