To improve the mobility of lower limb amputees, many modern prosthetic ankle-foot devices utilize a so called energy storing and return (ESAR) design. This allows for elastically stored energy to be returned to the gait cycle as forward propulsion. While ESAR type feet have been well accepted by the prosthetic community, the design and selection of a prosthetic device for a specific individual is often based on clinical feedback rather than engineering design. This is due to an incomplete understanding of the role of prosthetic design characteristics (e.g. stiffness, roll-over shape, etc.) have on the gait pattern of an individual. Therefore, the focus of this work has been to establish a better understanding of the design characteristics of existing prosthetic devices through mechanical testing and the development of a prototype prosthetic foot that has been numerically optimized for a specific gait pattern. The component stiffness, viscous properties, and energy return of commonly prescribed carbon fiber ESAR type feet were evaluated through compression testing with digital image correlation at select loading angles following the idealized gait from the ISO 22675 standard for fatigue testing. A representative model was developed to predict the stress within each of the tested components during loading and to optimize the design for a target loading response through parametric finite element analysis. This design optimization approach, along with rapid prototyping technologies, will allow clinicians to better identify the role the design characteristics of the foot have on an amputee's biomechanics during future gait analysis.
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Master of Science in Mechanical Engineering (M.S.M.E.)
College of Engineering and Computer Science
Mechanical and Aerospace Engineering
Mechanical Engineering; Mechanical Systems
Length of Campus-only Access
Masters Thesis (Open Access)
Smith, Kevin, "The Mechanical Response and Parametric Optimization of Ankle-Foot Devices" (2016). Electronic Theses and Dissertations, 2004-2019. 5144.