Direct measurement of torsional properties of single fibers

Liu, Dabiao; Peng, Kai; He, Yuming

doi:10.1088/0957-0233/27/11/115017

Cited by 10 publications

(5 citation statements)

References 34 publications

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“…Unfortunately, the energy analysis of the torsional actuation of dragline silks driven by humidity is not available since the torque in a single wet silk is tiny (<0.1 nN·m) and we do not attempt to measure it. An enhanced torsion tester for microfibers ( 25 , 26 ) is needed in the future study for determining the humidity-sinduced torque, which is as important as the supercontraction stress in wet spider dragline ( 8 ).…”

Section: Resultsmentioning

confidence: 99%

Spider dragline silk as torsional actuator driven by humidity

et al. 2019

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Self-powered actuation driven by ambient humidity is of practical interest for applications such as hygroscopic artificial muscles. We demonstrate that spider dragline silk exhibits a humidity-induced torsional deformation of more than 300°/mm. When the relative humidity reaches a threshold of about 70%, the dragline silk starts to generate a large twist deformation independent of spider species. The torsional actuation can be precisely controlled by regulating the relative humidity. The behavior of humidity-induced twist is related to the supercontraction behavior of spider dragline silk. Specifically, molecular simulations of MaSp1 and MaSp2 proteins in dragline silk reveal that the unique torsional property originates from the presence of proline in MaSp2. The large proline rings also contribute to steric exclusion and disruption of hydrogen bonding in the molecule. This property of dragline silk and its structural origin can inspire novel design of torsional actuators or artificial muscles and enable the development of designer biomaterials.

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Section: Resultsmentioning

confidence: 99%

Spider dragline silk as torsional actuator driven by humidity

et al. 2019

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“…Torque sensing is also a big challenge in micro/nano twisting test 11 , 25 – 27 . However, this paper mainly focuses on solving the operation problems in in-situ SEM twisting test, i.e., precise assembly and positioning, especially the misalignment problem in existing twisting test approach 11 , 13 . Up to now, we have been able to investigate the sample’s behavior during twisting and study the fracture plane after twisting.…”

Section: Discussionmentioning

confidence: 99%

“…To twist the small sample, a commonly used approach is to upgrade the traditional torsion test instrument in accuracy 9 , 10 . However, limited to the inherent drawbacks of the traditional instruments in structure and working mechanism, it is hardly possible to align the sample perfectly into the rotation axis of the rotation table, so that the effective gauge need to be lengthened to reduce the influence of the vertical misalignment 11 – 13 . It not only affect the measurement accuracy, but also make it nearly impossible to integrate within SEM for in-situ twisting test.…”

Section: Introductionmentioning

confidence: 99%

Nanorobotic System iTRo for Controllable 1D Micro/nano Material Twisting Test

Shang

Wei

et al. 2017

Sci Rep

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In-situ micro/nano characterization is an indispensable methodology for material research. However, the precise in-situ SEM twisting of 1D material with large range is still challenge for current techniques, mainly due to the testing device’s large size and the misalignment between specimen and the rotation axis. Herein, we propose an in-situ twist test robot (iTRo) to address the above challenges and realize the precise in-situ SEM twisting test for the first time. Firstly, we developed the iTRo and designed a series of control strategies, including assembly error initialization, triple-image alignment (TIA) method for rotation axis alignment, deformation-based contact detection (DCD) method for sample assembly, and switch control for robots cooperation. After that, we chose three typical 1D material, i.e., magnetic microwire Fe74B13Si11C2, glass fiber, and human hair, for twisting test and characterized their properties. The results showed that our approach is able to align the sample to the twisting axis accurately, and it can provide large twisting range, heavy load and high controllability. This work fills the blank of current in-situ mechanical characterization methodologies, which is expected to give significant impact in the fundamental nanomaterial research and practical micro/nano characterization.

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“…Due to the limitations of the working mechanism of traditional twisting systems, researchers have proposed methods to lengthen the effective gage to reduce the influence of the misalignment problem. 31,32 However, to realize an in situ SEM twisting test, the proposed traditional solutions did not work, owing to the limited space inside the SEM chamber. Therefore, this study proposes an alignment method (Figure 1(b)) based on a nanorobotic manipulation system to shorten the effective gauge, which can be integrated within SEM for an in situ twisting test.…”

Section: Experiments and Methodsmentioning

confidence: 99%

Scale effect investigation of copper microwire's mechanical properties after in situ scanning electron microscope twisting

Xue

Shen

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this study, the mechanical property of copper microwire, a widely used material in our daily life, is investigated by subjecting it to in situ scanning electron microscope twisting based on a self-developed nanorobotic manipulation system. First, copper microwire is assembled on the nanorobotic system inside the scanning electron microscope, and then twisted clockwise and anticlockwise continuously from 0° to 360° until fracture. After that, the mechanical properties of elastic modulus, microhardness, yield stress, and the strain hardening exponent of the twisted sample are investigated by nanoindentation. The change in elastic modulus and indention hardness showed strong indentation size effects, because a large number of geometrically necessary dislocations were generated around the indenter. In addition, the fracture analysis indicated that the smaller the scale of the material, the more sensitive it was to surface cracks or defects. Ductile fracture features of the twisted sample appear due to the nucleation, growth, and coalescence of the microvoids.

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Direct measurement of torsional properties of single fibers

Cited by 10 publications

References 34 publications

Spider dragline silk as torsional actuator driven by humidity

Spider dragline silk as torsional actuator driven by humidity

Nanorobotic System iTRo for Controllable 1D Micro/nano Material Twisting Test

Scale effect investigation of copper microwire's mechanical properties after in situ scanning electron microscope twisting

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