Browsing by Author "Granberry, Rachael"
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Item Design and Control of Reduced Power Actuation for Active-Contracting Orthostatic Intolerance Garments(49th International Conference on Environmental Systems, 2019-07-07) Granberry, Rachael; Padula, Santo; Eschen, Kevin; Abel, Julianna; Holschuh, BradActive-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.Item Effects of Anthropometric Variability and Dimensional Change Due to Posture on Orthostatic Intolerance Garments(47th International Conference on Environmental Systems, 2017-07-16) Granberry, Rachael; Dunne, Lucy; Holschuh, BradleyOrthostatic intolerance garments (OIG) (e.g., the anti-gravity suit (AGS) worn by astronauts during earth reentry) produce therapeutic pressures on the body through inflation or through pattern reduction (i.e., undersized knit garments that stretch when donned). While pneumatic garments (AGS) are currently employed by NASA, skin-tight OIGs allow for increased mobility and could improve astronaut safety in the event of an off-nominal event. Undersized OIGs have been explored as alternatives to inflatable systems; however, they are static and designed from a series of limb circumferences taken from the standing position. Lower body radii are not fixed dimensions - but rather dynamic dimensions dependent on body posture, composition, and topography; therefore, functional pressures exerted on the body in a seated posture (i.e. during earth reentry) are unpredictable and could produce unanticipated blood pooling if radii increase. This paper serves as an investigation of the variability and dynamics of the human body in relation to OIGs. To quantify body variability due to posture change, anthropometrics from 1264 North American women were gathered from the Civilian American & European Surface Anthropometry Resource (CAESAR) database. Four circumferential measurements were collected from a sample of the CAESAR population (n=80) at the ankle, calf, knee, and thigh. A paired t-test was conducted to determine the difference between standing and sitting mean circumferences for each region of the leg. Descriptive statistics were calculated to determine the range of percentage change within the sample statistics. The study concludes that leg radii are complex and fluctuate non-uniformly from the thigh to the ankle between body postures (i.e. standing to sitting). Future OIG design will require an incorporation of anthropometric analysis to account for dimensional variability to maintain effective and predictable medically therapeutic pressure on the body.Item Preliminary Investigation of the Design of a Mechanically Antagonistic, Actuating Countermeasure Garment(2020 International Conference on Environmental Systems, 2020-07-31) Granberry, Rachael; Abel, Julianna; Holschuh, BradCountermeasure garments are worn by all NASA crew during Earth reentry, landing, and egress in accordance with NASA-STD-3001. These lower-body compression garments are designed to mitigate lower body blood pooling, which can impair a crew member’s ability to complete critical landing tasks. The likelihood of cardiovascular deconditioning increases with mission duration; therefore, countermeasure garments are a critical safeguard to astronaut health as we push the bounds of space exploration into 3+ year missions (e.g. Journey to Mars). Current on-body compression technologies are either a mobility hazard, such as tethered inflatable compression systems, or uncomfortable and cumbersome due to their static design, such as undersized, elastane garments. Shapeshifting fabrics enable an alternative solution – compression garments that can be donned in a loose, relaxed configuration and contract and stiffen in response to small changes in temperature. Prior work has found that knitted actuator fabrics have actuation pull forces capable of providing suitable cardiovascular protection during astronaut landing activities. Additionally, prior work has presented and validated the use of custom SMA chemistries that can actuate below 40℃, the NASA-STD-3001 maximum allowable touch temperature. This work presents a preliminary investigation of the design of an actuating orthostatic intolerance garment using these high-force, low-temperature actuator fabrics in parallel with passive elastane fabrics to form a mechanically antagonistic wearable system. This mechanically antagonistic wearable system will be conceptually defined and built in the form of a prototype calf sleeve with two goals in mind. First, we present the first implementation of a new design methodology and use operation to observe the functional challenges of this mechanically antagonistic actuating countermeasure system. Secondly, we present system performance data, covering 2D mechanical performance testing and on-body user compression testing. The resulting trial run documentation and feedback paves the way for future, full garment actuating countermeasure garment prototypes.