Torque in Worsted Wool Yarns

Mitchell, Philip H.; Naylor, Geoffrey Rs; Phillips, D. G.

doi:10.1177/0040517506060909

Cited by 13 publications

(19 citation statements)

References 16 publications

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“…The torsional rigidity (S) [13], torsional modulus (k=JG) [1] and shear modulus (G) [14] of both the twisted (actuated) fibre and return spring fibre were determined by measuring the shaft rotation resulting from mechanical increase of torque applied by the lever arm. Torsional rotation ( ) versus torque (τ) curves from multiple samples of different lengths was used to determine torsional rigidity of fibre, as in equation (2).…”

Section: Fibre Characterizationmentioning

confidence: 99%

Characterisation of torsional actuation in highly twisted yarns and fibres

et al. 2015

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Highly twisted oriented polymer fibres and carbon nanotube yarns show large scale torsional actuation from volume expansion that can be induced, for example, thermally or by electrochemical charging. When formed into spring-like coils, the torsional actuation within the fibre or yarn generates powerful tensile actuation per muscle weight. For further development of these coil actuators and for the practical application of torsional actuators, it is important to standardise methods for characterising both the torsional stroke (rotation) and torque generated. By analogy with tensile actuators, we here introduce a method to measure both the free stroke and blocked torque in a one-end-tethered fibre. In addition, the torsional actuation can be measured when operating against an externally applied torque (isotonic) and actuation against a return spring fibre (variable torque). A theoretical treatment of torsional actuation was formulated using torsion mechanics and evaluated using a commercially available highly-oriented polyamide fibre. Good agreement between experimental measurements and calculated values was obtained. The analysis allows the prediction of torsional stroke under any external loading condition based on the fundamental characteristics of the actuator: free stroke and stiffness. AbstractHighly twisted oriented polymer fibres and carbon nanotube yarns show large scale torsional actuation from volume expansion that can be induced, for example, thermally or by electrochemical charging. When formed into spring-like coils, the torsional actuation within the fibre or yarn generates powerful tensile actuation per muscle weight. For further development of these coil actuators and for the practical application of torsional actuators, it is important to standardise methods for characterising both the torsional stroke (rotation) and torque generated. By analogy with tensile actuators, we here introduce a method to measure both the free stroke and blocked torque in a one-end-tethered fibre. In addition, the torsional actuation can be measured when operating against an externally applied torque (isotonic) and actuation against a return spring fibre (variable torque). A theoretical treatment of torsional actuation was formulated using torsion mechanics and evaluated using a commercially available highly-oriented polyamide fibre. Good agreement between experimental measurements and calculated values was obtained. The analysis allows the prediction of torsional stroke under any external loading condition based on the fundamental characteristics of the actuator: free stroke and stiffness.

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Section: Fibre Characterizationmentioning

confidence: 99%

Characterisation of torsional actuation in highly twisted yarns and fibres

et al. 2015

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“…The torque in spun single wool yarns depends significantly on the yarn structural parameters and the environmental conditions (Tran and Phillips, 2006b;Mitchell et al, 2006). In particular for wool yarns that are investigated in normal conditions (65% r.h., 20°C) the viscoelastic nature of wool causes several time-dependent effects.…”

Section: Experimental Methods Used To Measure the Ply In Zero-torque Mmentioning

confidence: 99%

Application of topological conservation to model key features of zero-torque multi-ply yarns

Tran

Heijden²,

Phillips

2008

Journal of the Textile Institute

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During yarn formation by ring spinning, fibres are bent into approximately helical shapes and torque or twist-liveliness is created. The yarn torque causes yarn instability, manifested as snarling or entanglements, and this instability must be controlled during manufacturing processes. Generally, the torque depends on yarn geometric factors such as the yarn twist, linear density and the fibre properties. A practical solution to the problem of twist-liveliness is the formation of a two-fold yarn. This twisting or plying process produces a yarn structure where the energy of the system is determined by purely geometrical constraints of the plied structure and consequently when an energy minimum is reached the plied yarn obtained from the process is torsionally balanced and torque-free. In the present paper, the stability of plied textile yarns will be evaluated using the Topological Conservation law (Fuller, F. B., 1971, Proc.Nat. Acad. Sci. USA, 68, 815-819.) developed to study the post-buckling behaviour of twisted rods by Van der Heijden et al. (Int. J. Mech. Sci., 45, 161-196, 2003).The present work considers the equilibrium configuration of a series of multi-ply twisted yarns (2, 4, and 6 strands) of finite length.Several structural and mechanical properties are highlighted: (i) the influence of structural properties (the number of strands, the strand linear density and strand twist) and the ratio of the torsional and bending stiffnesses of the strands on the balance point in multi-ply yarns. The topological invariant of the twisted yarn (link) is used to calculate the ply and strand properties (writhe) and compared with experimental results obtained at CSIRO. The inter-strand pressure between strands of a multi-ply yarn, a feature of also known as D.

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“…As described previously by Mitchell et al (2006) a torquemeter was constructed to directly measure the torque in the hanks of yarn. Weights were applied to the hank manually and the torque of the hank was measured.…”

Section: Numerical Analysismentioning

confidence: 99%

“…Weights were applied to the hank manually and the torque of the hank was measured. The work by Mitchell et al (2006) showed that the torque per strand was independent of the number of strands in the hank and the hank length. For the present study a hank of loop length 400 mm comprising 5 loops was prepared and attached to the torsion wire, that is, 10 strands each of 200 mm in length were measured.…”

Section: Numerical Analysismentioning

confidence: 99%

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Torsional properties of staple fibre plied yarns

Phillips¹,

Tran²,

Fraser³

et al. 2010

Journal of the Textile Institute

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A mathematical analysis of the mechanical governing equations applying to the torsional behaviour of multi-ply yarns under tension has been carried out. This analysis clearly shows that there are two components, a geometric component that determines the slope or gradient of the torque due to tension and a component that determines the yarn torque at zero applied tension (intrinsic torque) that depends on the fibre number, fibre moduli and diameter as well as the strand structural geometry. The effect of the ratio of the ply twist to the spinning twist of the single strands on the torque properties has been numerically analysed for two, three and four-ply yarns prepared from single 31 tex yarns. The model has been compared with experimental torque data for a range of two-ply yarns plied at different percentages of the singles spinning twist and also with different yarn histories and test environments. The experimental data reflect the trends identified by the model.

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Torque in Worsted Wool Yarns

Cited by 13 publications

References 16 publications

Characterisation of torsional actuation in highly twisted yarns and fibres

Characterisation of torsional actuation in highly twisted yarns and fibres

Application of topological conservation to model key features of zero-torque multi-ply yarns

Torsional properties of staple fibre plied yarns

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