Active Knit Actuation Architectures.

Smart Materials and Structures;Design;Actuator Architecture;Mechanical Engineering;Engineering;Mechanical Engineering

Abel, Julianna M.Daly, Samantha Hayes ;

University of Michigan

关键词: Smart Materials and Structures;    Design;    Actuator Architecture;    Mechanical Engineering;    Engineering;    Mechanical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/108748/jmariee_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Actuators move our world. While conventional and smart material actuators have enabled myriad applications, many advanced applications (e.g., morphing aircraft, deployable space structures, and medical devices) require complex, distributed, three-dimensional motions that are limited by current actuation capabilities. This dissertation explores a new cellular architectural actuator, active knits, and provides the fundamental scientific understanding of the active knit actuation architecture to enable the design, analysis, and synthesis of simultaneous large force and strain actuators that produce complex three-dimensionally distributed motions. The active knit architecture leverages a smart material fiber through a continuous network of hierarchically organized loops that generate complex motions (contraction, scrolling, coiling, accordion, arching, etc.), while simultaneously delivering high strain (10-600%) and force (1-100 N). This dissertation defines a four level active knit hierarchy (knitted loops, knit patterns, grid patterns, restructured grids), establishing a language to design, synthesize, and analyze new actuators and a framework to explore the breadth of actuator motions. To provide high fidelity predictive capabilities of planar active knit actuators, a two-dimensional analytical model is derived using Euler-Bernoulli beam bending and Elastica theory assuming dual-stiffness material behavior. To provide predictive capabilities of three-dimensional knit patterns early in the design process, a segment superposition modeling approach is developed that segments the unit cell and creates simple mechanical models that are superimposed to yield coarse prediction of the textile’s global performance. All models were experimentally validated against shape memory alloy (SMA) active knit prototypes with strong correlation of the force-deflection and actuation performance, confirming predictive capabilities for this simultaneous large strain and force actuation architecture. To further demonstrate the actuation potential, an active flow control case study was conducted using rib pattern actuators. The study verified that active knits can generate the simultaneous large displacements (23 mm/75%) and forces (4.4 kPa/44.4 N) that are necessary for extreme applications. While further research will be necessary to bring active knits into practice, this research established the necessary language, models, and experimental techniques to provide the scientific understanding essential for design, analysis, and synthesis of this novel cellular actuator architecture – opening the door to applications not yet imagined.