Thermomechanical effects in the torsional actuation of twisted nylon 6 fiber

Aziz, Shazed; Naficy, Sina; Foroughi, Javad; Brown, Hugh R.; Spinks, Geoffrey M.

doi:10.1002/app.45529

Cited by 16 publications

(5 citation statements)

References 27 publications

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“…Mechanical torsion guided twisted structures are subject to stress relaxation, both time‐based free relaxation and external stimuli or stress‐assisted relaxation. [ 19 ] Pre‐conditioning (training) these helical structures will allow to release the residual temporary stresses that are not recoverable or reversible. We trained our Alg‐PU/yarn muscle for three consecutive wetting/drying cycles when slight permanent stretching of muscle was noticed.…”

Section: Resultsmentioning

confidence: 99%

Plant‐Like Tropisms in Artificial Muscles

et al. 2023

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Helical plants have the ability of tropisms to respond to natural stimuli, and biomimicry of such helical shapes into artificial muscles has been vastly popular. However, the shape‐mimicked actuators only respond to artificially provided stimulus, they are not adaptive to variable natural conditions, thus being unsuitable for real‐life applications where on‐demand, autonomous operations are required. Novel artificial muscles made of hierarchically patterned helically wound yarns that are self‐adaptive to environmental humidity and temperature changes are demonstrated here. Unlike shape‐mimicked artificial muscles, a unique microstructural biomimicking approach is adopted, where the muscle yarns can effectively replicate the hydrotropism and thermotropism of helical plants to their microfibril level using plant‐like microstructural memories. Large strokes, with rapid movement, are obtained when the individual microfilament of yarn is inlaid with hydrogel and further twisted into a coil‐shaped hierarchical structure. The developed artificial muscle provides an average actuation speed of ≈5.2% s−1 at expansion and ≈3.1% s−1 at contraction cycles, being the fastest amongst previously demonstrated actuators of similar type. It is demonstrated that these muscle yarns can autonomously close a window in wet climates. The building block yarns are washable without any material degradation, making them suitable for smart, reusable textile and soft robotic devices.

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Section: Resultsmentioning

confidence: 99%

Plant‐Like Tropisms in Artificial Muscles

et al. 2023

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“…Heat setting at a temperature over T g benefits the newly formed coiled shape to be permanently set. Different elevated heat setting temperature was chosen as time-based creep and stress relaxation effects are less for high-temperature annealed twisted/coiled polymer fibres [ 28 ]. Heat setting at high temperature could also have a significant effect on the polymer crystallinity, hence vibration damping, which is one of the major aims of this study.…”

Section: Methodsmentioning

confidence: 99%

Self-Reinforced Nylon 6 Composite for Smart Vibration Damping

et al. 2021

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Passive vibration control using polymer composites has been extensively investigated by the engineering community. In this paper, a new kind of vibration dampening polymer composite was developed where oriented nylon 6 fibres were used as the reinforcement, and 3D printed unoriented nylon 6 was used as the matrix material. The shape of the reinforcing fibres was modified to a coiled structure which transformed the fibres into a smart thermoresponsive actuator. This novel self-reinforced composite was of high mechanical robustness and its efficacy was demonstrated as an active dampening system for oscillatory vibration of a heated vibrating system. The blocking force generated within the reinforcing coiled actuator was responsible for dissipating vibration energy and increase the magnitude of the damping factor compared to samples made of non-reinforced nylon 6. Further study shows that the appropriate annealing of coiled actuators provides an enhanced dampening capability to the composite structure. The extent of crystallinity of the reinforcing actuators is found to directly influence the vibration dampening capacity.

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“…The theoretically calculated results were then compared to the measured muscle contraction. Previous studies have shown that over-twisted and coiled polymer fibre actuators exhibit low structural stability during the first few heating / cooling actuation cycles [20,24,28].…”

Section: Tensile Actuationmentioning

confidence: 99%

Twist–coil coupling fibres for high stroke tensile artificial muscles

Aziz

Naficy

Foroughi

et al. 2018

Sensors and Actuators A: Physical

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A new concept for tensile artificial muscles is introduced in which the torsional actuation of a twisted polymer fibre drives a twist to writhe conversion in a serially attached elastomeric fibre. Thermally induced torsional rotation of the twisted fibre caused formation of coils in the elastomeric fibre which resulted in overall muscle length contraction. Theoretical predictions of the muscle strain were developed by means of a modified singlehelix theory. Experimental tests were conducted to measure the isotonic contraction strains for elastomeric fibres of different diameters and lengths. A good agreement between the measured and calculated results was found. Practical applicability of this muscle is evaluated by using different mechanical loading conditions. Actuation contraction strains as high as 10% were observed with excellent reversibility. Unlike original coiled fibre tensile actuators, these twist-coil artificial muscles did not require any pre-conditioning cycles.

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Thermomechanical effects in the torsional actuation of twisted nylon 6 fiber

Cited by 16 publications

References 27 publications

Plant‐Like Tropisms in Artificial Muscles

Plant‐Like Tropisms in Artificial Muscles

Self-Reinforced Nylon 6 Composite for Smart Vibration Damping

Twist–coil coupling fibres for high stroke tensile artificial muscles

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