【国外标准】 Standard Test Method for Breaking Force and Elongation of Textile Fabrics (Strip Method)

5.1 The raveled strip test in this test method is considered satisfactory for acceptance testing of commercial shipments of woven textile fabrics because the method has been used extensively in the trade for acceptance testing. The same is true for the cut strip test for felted or nonwoven textile fabrics.5.1.1 If there are differences of practical significance between reported test results for two laboratories (or more), comparative test should be performed to determine if there is a statistical bias between them, using competent statistical assistance. At a minimum, use the samples for such a comparative test that are as homogeneous as possible, drawn from the same lot of material as the samples that resulted in disparate results during initial testing and randomly assigned in equal numbers to each laboratory. The test results from the laboratories involved should be compared using a statistical test for unpaired data, a probability level chosen prior to the testing series. If bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.5.2 The method is not recommended for knitted fabrics because of their high stretch.5.3 Some modification of the techniques may be necessary for any fabric having a strength in excess of 200 N/cm (1140 lbf/in.) width. Special precautionary measures are provided for use when necessary with strong fabrics, or fabrics made from glass fibers (see Specification D579), to prevent them from slipping in the clamps or being damaged as a result of being gripped in the clamps.5.4 All of the procedures are applicable for testing fabrics either conditioned or wet.5.5 Comparison of results from tensile testing machines operating on different principles is not recommended. When different types of machines are used for comparison testing, constant time-to-break at 20 ± 3 s is the established way of producing data. Even then the data may differ significantly.5.6 Although a constant-rate-of-extension tensile testing machine is preferred in these methods, in cases of dispute, unless there is agreement to the contrary between the purchaser and supplier, a constant-time-to-break (20 ± 3 s) is to be used.5.7 The raveled strip procedure is applicable to the determination of the force required to break a specific width of fabric. The breaking force information on woven fabrics is particularly useful for comparison of the effective strength of the yarns in the fabric with the combined strength of an equal number of the same yarns which are not woven. The procedure is not recommended for fabrics having fewer than 20 yarns across the width of the specimen. If a 20-yarns-per-specimen width cannot be obtained with a 25-mm (1-in.) strip, a 50-mm (2-in.) strip should be used. In general, the observed force for a 50-mm (2-in.) specimen is not double the observed force for a 25-mm (1-in.) specimen and the results should be reported as observed on a 50-mm (2-in.) strip without mathematical adjustment to 25 mm (1 in.). If a fabric cannot be raveled readily, use either a cut strip or grab procedure.5.8 The cut strip procedure is applicable to heavily fulled fabrics, woven fabrics that cannot be readily raveled, felted fabrics and nonwoven fabrics. This procedure is not recommended for fabrics which can be raveled because the yarns at the edges tend to unravel during testing. The recommendation regarding the minimum number of yarns in a woven specimen discussed in 5.7 for raveled strips applies equally to cut strips.1.1 This test method covers raveled strip and cut strip test procedures for determining the breaking force and elongation of most textile fabrics. Provision is made for wet testing.1.1.1 The raveled strip test is applicable to woven fabrics while the cut strip test is applicable to nonwoven fabrics, felted fabrics, and dipped or coated fabrics.1.2 This test method is not recommended for knitted fabrics or for other textile fabrics which have high stretch (more than 11 %).NOTE 1: For the determination of the breaking force and elongation of textile fabrics using the grab test and modified grab test procedures, refer to Test Method D5034.NOTE 2: For determination of the breaking force and elongation of some specific types of fabrics which use the strip test, refer to Specifications D579 and D580.1.3 This test method shows the values in both inch-pound units and SI units. Inch-pound units is the technically correct name for the customary units used in the United States. SI units is the technically correct name for the system of metric units known as the International System of Units. The values stated in either acceptable metric units or in other units shall be regarded separately as standard. The values expressed in each system may not be exact equivalents; therefore, each system must be used independently of the other, without combining in any way.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.