26—structural and Non-Structural Effects in the Observed Stress-Strain Curve for Wet Wool Fibres

Collins, J. D.; Chaikin, M.

doi:10.1080/09636416808629949

Cited by 3 publications

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“…In this approach, keeping nutrition consistent maintains FFLwt and avoids increasing MFD over time. This consistent diameter along the fibre will maximise staple strength (Collins and Chaikin, 1968).…”

Section: Discussionmentioning

confidence: 99%

Coarser wool is not a necessary consequence of sheep aging: allometric relationship between fibre diameter and fleece-free liveweight of Saxon Merino sheep

McGregor

Butler²

2016

animal

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The mean fibre diameter (MFD) of wool is the primary determinant of price, processing performance and textile quality. This study determines the primary influences on MFD as Saxon Merino sheep age, by allometrically relating MFD to fleece-free liveweight (FFLwt). In total, 79 sheep were grazed in combinations of three stocking rates and two grazing systems (GS: sheep only; mixed with Angora goats) and studied over 3 years. Measurements were made over 14 consecutive periods (Segments), including segments of FFLwt gain or FFLwt loss. Using shearing and liveweight records and dye-bands on wool, the FFLwt and average daily gain (ADG) of each sheep were determined for each segment. The mean and range in key measurements were as follows: FFLwt, 40.1 (23.1 to 64.1) kg; MFD, 18.8 (12.7 is a random animal effect, γ(Segment.Plot) a random effect associated with Segment.plot combinations, and κ a constant that depends on GS, random animal effects, random Segment.plot combination effects, Segment and ADG. Thus, MFD was allometrically related to the cube root of FFLwt over seasons and years for sheep, but to the square root of FFLwt for sheep grazed with goats. The result for sheep grazed alone accords with a primary response being that the allocation of nutrients towards the cross-sectional growth of wool follicles is proportional to the changes in the skin surface area arising from changes in the size of the sheep. The proportionality constant varied systematically with ADG, and in sheep only grazing, was about 5 when sheep lost 100 g/day and about 6 when sheep gained 100 g/day. The proportionality constant did not systematically change with chronological age. The variation in the allometric coefficient between individual sheep indicates that some sheep were more sensitive to changes in FFLwt than other sheep. Key practical implications include the following: (a) the reporting of systematic increases in MFD with age is likely to be a consequence of allowing sheep to increase in size during shearing intervals as they age; (b) comparisons of MFD between sheep are more likely to have a biological basis when standardised to a common FFLwt and not just to a common age; (c) wool quality (MFD, staple strength) are most likely to be optimised in management systems that maintain constant FFLwt of adult sheep within and between years.Keywords: allometric coefficient, sheep, scaling, wool, skin follicles ImplicationsResponses in mean fibre diameter (MFD) of Merino wool to changes in fleece-free liveweight (FFLwt) were in accord with the primary response of MFD being proportional to the changes in the skin surface area arising from changes in animal size. However, this response can change with individual sheep and nutritional environment. Comparisons of MFD between sheep are more likely to have a biological basis when standardised to a common FFLwt than when standardised to a common age. Wool quality (MFD and staple strength) will be optimised in management systems that maintain constant FFLwt of adult sheep within and between years...

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Section: Discussionmentioning

confidence: 99%

Coarser wool is not a necessary consequence of sheep aging: allometric relationship between fibre diameter and fleece-free liveweight of Saxon Merino sheep

McGregor

Butler²

2016

animal

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“…23 Stress-strain curves of wool fibres: A, with good uniformity; B, more irregular fibre. From Collins and Chaikin[54].…”

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confidence: 99%

Tensile properties

Morton¹

2008

Physical Properties of Textile Fibres

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“…The average breaking extension of a fiber decreases as the specimen gauge length increases [7]. Collins and Chaikin [3][4][5] have examined the effects of fiber non-uniformity on the tensile properties of non-uniform fibers. They have shown that variations in cross-sectional area along the fiber length markedly affect the stress-strain curves.…”

Section: Introductionmentioning

confidence: 99%

Modeling the tensile strains of non-uniform fibers

Deng

Wang

2007

Fibers Polym

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Abstract:The maximum strain experienced by the thinnest segment of a non-uniform fiber governs fiber breakage, yet this maximum strain can not be obtained from a normal single fiber test. Only the average strain of the whole fiber specimen can be obtained from a normal single fiber tensile test. This study has examined the relationship between the average strain, the maximum strain and the degree of fiber non-uniformity, expressed in coefficient of variation (CV) of fiber diameters along fiber length. The tensile strain of irregular fibers has been simulated using the finite element method (FEM). Using this method, average and maximum tensile strains of non-uniform fibers were calculated. The results indicate that for irregular fibers such as wool, there is an exponential relationship (i.e. ) and the alongfiber diameter variation (CV). The strain ratio decreases with the increase of the along-fiber diameter variation.

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26—structural and Non-Structural Effects in the Observed Stress-Strain Curve for Wet Wool Fibres

Cited by 3 publications

References 0 publications

Coarser wool is not a necessary consequence of sheep aging: allometric relationship between fibre diameter and fleece-free liveweight of Saxon Merino sheep

Coarser wool is not a necessary consequence of sheep aging: allometric relationship between fibre diameter and fleece-free liveweight of Saxon Merino sheep

Tensile properties

Modeling the tensile strains of non-uniform fibers

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