Doctoral defence in Mechanical Engineering - Heimir Tryggvason | University of Iceland Skip to main content

Doctoral defence in Mechanical Engineering - Heimir Tryggvason

Doctoral defence in Mechanical Engineering - Heimir Tryggvason - Available at University of Iceland
When 
Tue, 15/06/2021 - 14:00 to 16:00
Where 

Askja

Room 132

Further information 
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Ph.D. student: Heimir Tryggvason

Dissertation title: Smart Material Prosthetic Ankle - Employing material properties for variable stiffness

Opponents: 
Dr. Peter G. Adamczyk, Assistant Professor at the University of Wisconsin, USA
Dr. Elliott J. Rouse, Assistant Professor at the University of Michigan, USA

Advisor: Fjóla Jónsdóttir, Professor at the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland

Doctoral committee: 
Dr. Sigurður Brynjólfsson, Professor at the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland
Dr. Sigrún Nanna Karlsdóttir, Professor at the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland
Magnús Oddsson, Senior Research Engineer at Össur hf

Chair of Ceremony: Dr. Rúnar Unnþórsson, Professor and the Head of the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland

Abstract:
The inspiration for this research is the natural graduation in stiffness of the biological ankle, over a wide range of ambulation tasks. The goal is to achieve variable stiffness in the force response of a prosthetic foot, utilizing the properties of smart materials. This thesis presents the design and prototyping of a coupling that utilizes the discontinuous change in viscosity observed in shear thickening fluids. A speed dependent stiffness is achieved with the coupling installed in a system of springs. The coupling design presented is used in the modification of a commercially available prosthetic foot. The stiffness of the prototype foot depends on the rate of movement, ranging from a dissipating support at very slow walking speed, to efficient energy storage and return at normal walking speed.
Maximizing energy return during walking is an important design objective for passive prosthetic feet. The objective of this work is to design a prosthetic foot that provides a damped compliant support for slow ambulation without sacrificing the spring like energy return that is beneficial in normal walking. The function of the original prosthetic foot was analyzed in a finite element model to acquire the parameters for the improved design. The coupling was developed and characterized by uniaxial testing. A prototype prosthetic foot was designed and built, and the speed dependent stiffness measured mechanically. Furthermore, the prototype was tested by a user and body mechanics measured in gait analysis for varying walking speed, comparing the prototype to the original foot model. The results confirm speed dependent stiffness introduced by the novel device.

About the doctoral candidate:

Heimir Tryggvason was born in 1977. He finished a B.Sc. degree in Mechanical and Industrial Engineering at the University of Iceland in 2003 and a M.Sc. degree in Mechanical Engineering at the Danish Technical University in Copenhagen, in 2004. Heimir started his doctoral studies, under the tutelage of Prof. Fjóla Jónsdóttir, in 2016.

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Doctoral defence in Mechanical Engineering - Heimir Tryggvason