Design and Control of Reduced Power Actuation for Active-Contracting Orthostatic Intolerance Garments



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49th International Conference on Environmental Systems


Active-contracting fabrics are a developing innovation that could revolutionize compression garment technology, notably aerospace orthostatic intolerance garments (OIG), by contracting on demand. Traditional fabric structures exhibit surface-wide distributed and/or functionally graded contractile actuation through the integration of materials with shape memory (SM) properties. Prior research has found that active-contracting fabrics, specifically weft knit garter fabric architectures constructed with shape memory alloy (SMA) filaments, can apply 8-30 mmHg on the body (single-layer construction) or 15-65 mmHg (double layer construction), depending on body radius (i.e. average ankle girth, SizeUSA women; average torso girth, SizeUSA men). Prior garment prototyping and performance validation efforts have been conducted with commercially available Flexinol wire with an actuation finish temperature of 90°C, a temperature that is not appropriate proximal to the human body. While other chemistries of SMA having lower actuation temperatures commonly used for medical devices inside the human body (T ≈ 37°C) are available, SMA material is currently not designed specifically for actuation control against the human skin (T ≈ 31°C). This research characterizes and validates a novel SMA material designed in collaboration with Fort Wayne Metals specifically for actuation adjacent to the surface of the body. Through traditional SMA material testing paired with experimental temperature-force-displacement testing, we present data validating material functionality in the design of a future OIG. The manuscript presents evidence for a future OIG that is donned in an oversized and compliant state, heated momentarily above ambient skin temperature to initiate actuation, and remains actuated post-applied heat indefinitely. The result is an OIG that requires almost no operating power that could be doffed through zipper releases and placed in a sub-zero chamber to return to the “off” state before reuse. Preliminary findings will be presented to characterize the performance of the material in future aerospace compression systems.


Rachael Granberry, University of Minnesota, USA
Santo Padula, National Aeronautics and Space Administration (NASA), USA
Kevin Eschen, University of Minnesota, USA
Julianna Abel, University of Minnesota, USA
Brad Holschuh, University of Minnesota, USA
ICES400: Extravehicular Activity: Space Suits
The 49th International Conference on Environmental Systems as held in Boston, Massachusetts, USA on 07 July 2019 through 11 July 2019.


compression garments, orthostatic intolerance garments, contracting fabrics, robotic fabrics, shape memory alloys, shape memory effect, functional clothing