AU621859B2 - Apparatus for measuring fabric extensibility - Google Patents

Description

161 "ii 0- OPI DATE 25/08/89 AOJP DATE 28/09/89 APPLN. ID 30449 89 PCT NUMBER PCT/AU89/00030

PCT

INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 Inter i ubl i on be O 89/07251 G01N 3/14, 3/00, 19/00 Al (43) inter S blictio A t 1989 (0.08.89) I n&bi1to'Ae: AV 99(00.9 (21) International Application Number: PCT/AU89/00030 (22) latersational Filing Date: 31 January 1989 (31.01.89) (31) Priority Application Number: PI 6611 (32) Priority Date: (33) Priority Country: S February 1988 (05.02.88) (74) Agent: SPRUSON FERGUSON; G.P.O. Box 3898, Sydney, NSW 2001 (AU).

(81) Designated States: AT (European patent), AU, BE (European patent), CH (European patent), DE (Europepa; patent), FR (European patent), GB (European patent), IT (European patent), JP, KR, LU (European patent), NL (European patent), SE (European patent), US.

Published With international search report.

(71) Applicant (for all designated States except US): COM- MONWEALTH SCIENTIFIC INDUSTRIAL RE- SEARCH ORGANISATION [AU/AU]: Limestone Avenue, Campbc:ll, ACT 2600 (AU), (72) Inventors; and Inventors/Applicants (for US only) LY, Nhan, Gia [VN/ AU]; 26 Keene Street, Baulkham Hills, NSW 2153 BUCKENHAM, Peter [AU/AU]: 10 Bundanoon Place, Hornsby Heights, NSW 2077 (AU), (54) Title: APPARATUS FOR MEASURING FABRIC EXTENSIBILITY (57) Abstract An apparatus (10) to measure fabric in extensibility, the apparatus (10) includes a base (11) upon which there is pivotally mounted, for rotation about a horizontal axis, an arm one end of the arm is provided with a elamp (18) which is vertically aligned with a further clamp (12) between which a piece of fabric (31) extends to be placed under ten.

sion by the apparatus The apparatus (10) further includes a sensor (34) which detects deflection of the arm (13) to pro.

vide an idication of the extension of the piece of fabric (3 l), I I ir c I I i WO 89/07251 PCr/AU89/00030 -1- APPARATUS FOR MEASURING FABRIC EXTENSIBILITY Background of the Invention The present invention relates to an apparatus for measuring fabric extensibility.

During garment making up, in particular fabric shaping and sewing, the fabric needs to be stretched to a certain degree to conform to the intended shape. This ability of a fabric to stretch at low load, or fabric extensibility is of major concern to the tailors.

Prior Art The recent introduction to the garment manufacturing industry of sophisticated instruments for measuring fabric mechanical and physical properties has raised the awareness of the textile industry to the usefulness of objective measurement for quality control and product development, However, apart from being expensive, the currently available instruments require a skillful and devoted operator, These are the main reasons for the reluctance of most tailors to adopt fabric objective measurement for quality control.

Objects of the Invention It is the object of the present invention to overcome or substantially ameliorate the above disadvantages.

Summary of the Invention There is disclosed herein an apparatus to measure fabric extensibility, said apparatus comprising: a base; a first clamp fixed to the base to securely engage an end portion of a piece of fabric; an arm pivotally mounted intermediate its ends on said base so as to be pivotable about a horizontal axis; a second clamp mounted on said arm remote from said axis and -;sitioned to securely engage a further end portion of said piece of fabric so that said piece of fabric extends between the two clamps; means to vary the force applied to said piece of fabric and thereby cause angular deflection of said arm about said axis; and means to measure the displacement of said arm.

Description of the Preferred Embodiment A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wnerein: Figure 1 is a schematic perspective view of an apparatus to measure the extensibility of fabric; Figure 2 is a schematic perspective view of the clamps employed in SUBSTITUTE SHEET WO 89/07251 PCT/AU89/00030 2 the apparatus of Figure 1; and Figure 3 Is a schematic side elevation of the apparatus of Figure 1.

In the accompanying drawings there Is schematically depicted an apparatgus 10 to measure the extensibility of fabric. The apparatus includes a base 11 to which there Is fixed a first clamp assembly 12. Also mounted on the base 11 Is a pivoted arm 13 which Is supported by means of a shaft 14 extending between a pair of bearings 15 mounted In bearing blocks 16 secured to the base 11. The arm 13 Is pivoted intermediate Its ends so as to be rotatably about the horizontal axis 17.

One end of tha arm 13 Is provided with a clamp assembly 18 while the other end of the arm 13 is provided with a pin 19 to retain in position ole or more weights Each clamp assembly 12 and 18 includes a frame portion 21 including side members 22 between which there extends a rod 23. Slldably located within each frame portion 21 is a clamp plate 24, with each plate 24 including flanges 25 which rest on side members 22. Each clamp plate 24 includes a body 26 which can be moved In a clamping action towards the associated rod 23. Each body 26 is also provided with a tapered aperture 27 which receives the tapered end 28 of a threaded member 29. The threaded member 29 threadably engages an aperture 30 formed in the frame portion 21.

Rotation of the threaded members 29 moves the clamping plates 24 towards the rods 23 to engage t he piece of fabric 31.

Extending between the bearing block 16 is a plate 32 upon which there is mounted a sensing head 33 of a transducer 34. The transducer 34 provides an electric signal indication of the displacement of the arm 13.

The force to which the piece of fabric 31 Is subjected, is determined

B

by the weight or weights 20. Initially the fabric 31 would be placed under tension due to the weight of the clamp assembly 18. This tension force would then be varied by adding one or more weights Displacement of the arm 13 Is a measure of the extension of the piece of fabric 31. Accordingly the transducer 34 provides a signal Indicative of the degree of extension of the piece of fabric 31.

If so required, a pivoted plate may be mounted on the arm 13, adjacently below the sensing head 33, which plate would be retained horizontal despite angular movement of the arm 13 in order to aid In the accurate reading of the displacement of the arm 13.

The transducer 34 would be a non-contact electronic sensor which gives a direct reading of extension as percentage of toe initial gauge length.

WO 89/07251 PCT/AU89/00030 -3 The apparatus 10 is capable of measuring the fabric extensibility at 20, 50 and 100 gf/cm. The loads from 20 gf/cm and above are used for the warp and weft directions while the 5 gf/cm load Is used for the bias direction of the fabric, ie at 45 degrees to either the warp or weft direction.

In one example, the fabric sample was 150 mm x 50 mm and the fabric area tested was 100 mm x 50 mm when clamped between the clamp assemblies 12 and 18. The following parameters were obtained directly: Extensibility at 20 gf/cm: E20 Extensibility at 50 gf/cm: E50 (M) Extensibility at 100 jf/cm: E100 Bias extensibility at 5 gf/cm: EB5 The ability of a two dimensional piece of fabric to form a three dimensional garment also depends on how easily the fabric can be sheared In Its plane. This mode of deformation is characterized by the fabric shear rigidity which can be estimated from the bias extensibility in the following way: Assuming the fabric behaves as an anisotropic elastic lamina, the Young's Modulus In a direction e to the warp (Yo) is related to the Young's Modull in the warp and weft direction (Y1 and Y2), and the shear modulus by the following equation 4 2 2 4 1_ _s4 1 212 sin 0 cos 0 sinq 4 Yo Y1 G Y1 Y2 where 012 Is the Polsson's ratio, relating the contraction in the weft direction on the extension in the warp direction. For most apparel fabrics, the Young's moduli in the warp and weft direction are much greater than the shear modulus and when e 45*, It was shown [71 that the Young's modulus at 45" (Y45) can be approximated by four times the shear modulus, ie Y45 4 x G Since the relationship between stress and strain in the bias direction is approximately linear for low-stress deformation, s45/E4b. For s45 5 gf/cm and E45 EB5/100, the shear modulus or shear rigidity can be expressed as G 125/EB5 (gf/cm) A comparison has been made between the apparatus 10 and 'che KES-F Tensile and Shear Tester [23 for 29 fabrics covering a wide range of fabric thicknesses and weights. The results are shown in Figures 4 for the extensibility at 50 gf/cm and in Figure 5 for the shear rigidity.

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i i WO 89/07251 PCT/AU89/00030 1 -4- Excellent correlations are found between the two instruments with a correlation coefficient of 0.98 for the extensibility at 50 gf/cm and of 0.94 for the shear rigidity.

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Claims (4)

1. 2. The apparatus of Claim 1 wherein the centre of gravity of said arm and said second clamp is displaced from said horizontal axis towards said second clamp so that in use said arm and second clamp place said piece of fabric under tension due to their weight.
2. 3. The apparatus of Claim 2 wherein said apr has a mounting to receive one or more weights, which mounting isAlF-ae-from said axis in the opposite direction to said second clamp.
3. 4. The apparatus of Claim 3 wherein said first clamp and said second clamp each consi.st of a fixed clamp member and a movable clamp member, which movable clamp member is moved horizontally towards the fixed clamp member in order to engage the piece of fabric. The apparatus of Claim 4 wherein the first clamp and the second clamp are vertically aligned.
4. 6. The apparatus of Claim 5 further including a pivot assembly supporting said arm for rotation about said axis. mean tomeaure he ispaceent f sid rm.I