Master's lecture in Mechanical Engineering - Gunnar Sigurðsson

Master's student: Gunnar Sigurðsson

Title: Design of a Shear Thickening Fluid Damper

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Faculty: Faculty of Industrial Engineering, Mechanical Engineering and Computer Science

 Advisors:  Fjóla Jónsdóttir, Professor at the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science and Heimir Tryggvason, Ph.D student in Mechanical Engineering.

Examiner: Felix Starker, Specialist at Össur

Abstract

Shear thickening fluids (STFs) are known for their ability to dissipate energy under sudden impact, making them suitable for equipment like protective clothing and devices with adaptive stiffness and damping. Much research has been conducted regarding textiles impregnated with colloidal suspensions, but mechanical devices that utilize the properties of STFs have been studied markedly less. Recent research for STFs as medium for damper devices have shown propitious results for commercial application. In this thesis, the feasibility of using an STF-based damper as a part of a prosthetic ankle joint is investigated. Dampers are normally used to mitigate vibrations by dissipating energy. By introducing an STF as medium of the damper, the damper device has the capability to change the damping characteristics substantially during load, towards severe overdamping that can be considered as a mechanical coupling. A prototype of an annular flow damper is devised, and its dynamic behavior measured by varying the rheological properties of the STF and the physical dimensions of the piston (radius, length). The damper’s characteristics are analyzed qualitatively where the piston reciprocates sinusoidally within the cylinder, at various excitation frequencies. Experimental results for the damper indicates the viability of using the damper as a component in a prosthetic ankle joint.