The most common tensile test used in the textile industry is called the grab test. The grab test method is a modification of a standard tensile test for use with woven and non woven textile fabrics that measures ultimate strength and elongation. A typical tensile test clamps the end of the specimen, which is effective when testing metals, plastics, and other traditional solid materials. However, this type of gripping introduces edge effects if used for textile materials, giving inaccurate tensile data and does not provide a correct measure of the bulk fabric material properties. The grab test eliminates edge effects by clamping the center of the sample width, away from the sample ends, and using jaws smaller than the sample width. As with all textile tests, alignment of the grip surfaces with the plane of the fabric sample is crucial for achieving accurate results. However, the orientation of the fabric in the sample is only significant if the material exhibits anisotropic material properties, which would give different strength values for off axis loading.
Textile Grab Strength Test Standards In accordance with ASTM and ISO standards, data from grab test experiments is used to determine effective fabric strength, which is the fabric strength in a specific width together with the strength contributed by adjacent material. Popular grab test standards are ASTM D751 for coated fabrics, ASTM D1683 for woven apparel fabric seams, ASTM D2208 for soft, boarded, sueded, or embossed leather, ASTM D5034 for textile fabrics, and ISO 13934-2 for fabrics, and ISO 13935-2 for fabrics and made-up textiles, such as clothing apparel. Textiles tend to be difficult to test without slippage or jaw face breaks due to over- tightening. Pneumatic grips offer ease of use, productivity, and enhanced repeatability. Pneumatic action grips also allow the user to set clamp pressure. Common grab tests require special 25.4 mm x 50.8 mm (1 in x 2 in) front jaw faces, with the opposing jaw face at least as big. Grip pressure and specimen alignment are critical. Too much pressure produces premature breaks, and low pressure causes specimen slippage or breaks at or near the grip jaw faces. Slack correction is needed or the specimen is held too loosely in the grips at the start of the test. Tabletop tensile test machines are a good fit for textile tensile tests in general because they feature CRE (constant rate of extension or constant test speed) capabilities. They meet and exceed ASTM D76 textile test machine standards.
Applicable Testing Standards
- ISO 9073 Textiles Test Equipment
- ISO 13934 Test Machines for Grab and Strip Tests of Fabric
- ISO 13935 Seam Tensile Properties of Textiles
- ASTM D751 Coated Fabrics Rainwear Test Equipment
- ASTM D1683 Sewn Seams of Woven Fabric
- ASTM D2208 Grab Break Strength Leather Testing Equipment
- ASTM D5034 Grab Testing for Textile Fabrics
Recommended Test Machine
Forces up to 10 kN (2,250 lbf)
Low force tabletop systems
Modular series of five frame options with adjustable test space
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Forces up to 5 kN (1,125 lbf)
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Tests at speeds up to 2,500 mm/min (100 in/min)
Best for high travel or high elongation test requirements
Force range of 5 kN to 600 kN (1,125 lbf to 135,000 lbf)
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These dual column testers are available in both tabletop and floor standing models
Recommended Testing Accessories
Grip and jaws satisfy the requirements of ASTM D1683
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Quick and easy specimen setup
Consistent clamp force between tests
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Clamping force up to 7.0 kN (1,600 lbf)
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Quick and easy specimen setup for a wide variety of applications
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Clamping force up to 16 kN (3,600 lbf)
Maximum specimen thicknesses from 10 mm to 30 mm (0.39 in. to 1.2 in.)
Pneumatic actuation allows for quick and simple specimen setup
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Simple design can be used for a multitude of tensile applications
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