Determination and studying of stress distribution in various ankle-foot orthoses : experimental stress analysis
Biomedical Engineering Committee
Master of Science
Kristol, David S.
Ankle-Foot Orthosis (AFO) is prescribed to constrain and inhibit abnormal motion such as "drop foot" due to stroke. Most orthoses were hand-made by orthotists according to their own experience. However, some types of AFO were easy to fatigue (out of their functional capabilities) than others due to regular usage. In order to improve the design and usage, quantitative stress analysis of different types of orthoses is needed. The objective of this project is to obtain experimental data which will confirm the results obtained from previous Finite Element Analysis (FEA). In addition, the experimental analysis is extended to obtain more data related to design parameters in various types of orthoses in order to improve the AFO design. An experimental test system and method are developed which allow accurate measurements of the strain/stress in AFOs.
Results obtained from the experimental analysis provided a clear picture of Average Peak Stress (APS) concentration and its distribution. Results further confirmed the hypothesis and results from earlier FEA that peak stress in the orthosis occurs in the neck region. Thus, failure in this place is common and a better design is needed. From the present investigations, the following suggestions are made. Every AFO should be made asymmetrically and the lateral side should be wider or thicker than the medial side.
njit-etd1997-023 (93 pages ~ 4,276 KB pdf)
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Created June 13, 2005