Browsing by Author "Preston, Daniel J"

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    Programmable failure of heat-sealable textiles for soft robotics
    (2024-04-19) Broshkevitch, Adam Teofil; Preston, Daniel J; Wehmeyer, Geoffrey
    While mechanisms are often designed for compliance or controllability, heat-sealable textiles (HSTs) can be bonded to form fluidic networks which operate within both constraints. I examined failure in HST systems, clarifying the effects of processing parameters on seal strength and relating pouch geometry to burst pressure. My findings can be leveraged to ensure a HST soft robot or device is sufficiently robust for a given use case. I also present a soft fluidic component, analogous to an electrical crowbar circuit, into which failure is deliberately programmed. When integrated into a fluidic network, the component can be used to limit damage in cases of overpressure or to achieve multiple modes of actuation with a single pressure input. Operation is triggered by signals on the order of 1 to 3 bars. In summary, my findings enable the design of more intelligent and resilient HST systems, broadening their application space.
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    Tailored Wicking Performance in Porous Media Attained with Additive Manufacturing
    (2024-04-18) Noce, Evan; Preston, Daniel J
    Additive manufacturing (AM) has improved the ability and accessibility of manufacturing wicking materials. With lower manufacturing costs than traditional methods, AM is of particular value to fields such as thermal management and microfluidics to decrease the unit price of devices. Due to the limited control of the flow rate of wicking in porous media, designing these materials is a significant challenge. As a result, there is a need for easy-to-produce materials with tailorable wicking performance. In this work, we present a method of predicting wicking in porous media, achieved through the use of AM to create porous structures with simple geometries. Layers of parallel lines, each successive layer rotated 90° from the last, formed a gridded structure for which analytical models for the capillary pressure and solid fraction and a semi-analytical model for permeability were found. These models were then verified with capillary rise experiments against gravity using an area-independent form of Darcy’s law. The experiments validated the models over a range of solid fractions from 0.4 to 0.9. Finally, by representing porous media as a series of Ohmic fluidic resistors, we designed wicking material with spatially varying parameters. These materials achieved non-intuitive wicking performances, such as progressions that were linear or piecewise functions of time rather than the traditional exponential Washburn relationship.
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    TREB: A Pneumatically Actuated Tunable Resistive Exercise Bellows Device for Resistance Training
    (2024-04-19) Zobayed, Irfan; Preston, Daniel J
    Resistance training is imperative for overall health and well-being in humans. This modality of exercise is not only popular for maintaining a healthy lifestyle but is also sought after by athletes for increased performance and patients with mobility impairments for locomotion therapy. However, resistance training equipment can be inaccessible for both humans on earth and space, where gravity independent and vibration isolated equipment can combat muscle loss in astronauts. TREB (tunable resistive exercise bellows) resistance training device leverages pneumatic resistance for gravity independent resistance-based training in a compact, lightweight device compared to traditional resistance exercise equipment, like free-weights and weighted machines. This work demonstrates the modeling and performance characterization of the expected resistive behavior for quick, interchangeable pneumatic resistors to tune TREBs resistive output. Furthermore, a suite of TREB exercises are proposed that contribute to both resistive exercises for enhanced muscular conditioning and other rehabilitative and assistive applications.