ASTM D2256 PDF

A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. Scope 1. NOTE 1—Special methods for testing yarns made from speci?

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A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. Scope 1. NOTE 1—Special methods for testing yarns made from speci? Terminology 3. Summary of Test Method 4. Elongation at a speci? Breaking force, breaking tenacity, elongation, initial and chord modulus, and breaking toughness of the test specimen, in terms of linear density, may be calculated from machine scales, dials, recording charts, or by an interfaced computer.

It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Referenced Documents 2. Current edition approved Sept. Published November Originally published as D — 64 T. Last previous edition D — However, this statement is not applicable to knot and loop breaking force tests, tests on wet specimens, tests on oven-dried specimens, or tests on specimens exposed to low or high temperatures and should be used with caution for acceptance testing because factual information on between-laboratory precision and bias is not available.

As a minimum, use the samples for such a comparative tests 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 a 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. Initial modulus is a measure of the resistance of the yarn to extension at forces below the yield point. The chord modulus is used to estimate the resistance to imposed strain. The breaking toughness is a measure of the work necessary to break the yarn.

The skein-breaking force is always lower than the sum of the breaking forces of the same number of ends broken individually. Some modi? To prevent slippage in the clamps or damage as a result of being gripped in the clamps, special clamping adaptations may be necessary with high modulus yarns made from?

Specimen clamping may be modi? In any event, the procedure described in this test method for obtaining tensile properties must be maintained. It provides an indication of the likely stretch behavior of garment areas such as knees, elbows, or other points of stress. It also provides design criteria for stretch behavior of yarns or cords used as reinforcement for items such as plastic products, hose, and tires.

NOTE 3—Force-elongation curves can be converted to stress-strain curves if the force is converted to unit stress, such as to centinewtons per tex, or pounds per square inch, or pascals, or grams-force per tex, or grams-force per denier, and the elongation is based on change per unit length.

Elongation in knot or loop tests is not known to have any signi? When tensile tests are performed at a? The 5 Tweedie, A. D — 02 agreement is not necessarily good, however, between CRE or CRT tension testing machines on the one hand and CRL tension testing machines on the other even when they are all operated at the same time-to-break.

The CRE-type tester is the preferred tension testing machine. It also provides for alternate speeds, such as 6 10 mm 12 6 0. See 9. The difference in breaking force between tests at 17 and 23 s will usually not exceed 1.

These alternative rates may be used only by agreement between the parties concerned or when required in an applicable material speci? Wet tests are made on? Note that results obtained when testing oven-dried specimens at standard temperature will not necessarily agree with the results obtained when testing oven-dried yarns at high temperatures. Low-temperature tests are made on coated yarns used in the manufacture of materials used in outdoor applications, such as screening fabrics.

Apparatus and Reagents 6. A variable-speed drive, a change of gears, or interchangeable weights are required to obtain the s timeto-break. If the rate of operation is adjusted in steps, the steps should be no greater than 1.

The tension testing machine may be equipped with: 1 clamps having? The tension testing machine may be interfaced with a computer system for operation and data gathering. The CRE-type tension testing machine is recommended unless otherwise agreed upon between the purchaser and the supplier.

NOTE 4—Test machines capable of both tension and compression are acceptable for use with Test Method D when operated in the tension mode. NOTE 5—Flat-faced clamps are usually used with?

The snubbing-type clamps are used with coarse yarns or yarns that show a high breaking force. They are also used when specimens slip in the clamps or the number of breaks at or close to the jaws exceeds statistical expectations.

To check slippage, make a mark on the specimen as close as possible to the back of each clamp, operate the machine to break the specimen, and observe whether the marks have moved from the jaw faces of either clamp.

See Note 6. NOTE 6—Units described in 6. Sampling 7. Consider shipping cases or other shipping D — 02 units to be the primary sampling units. NOTE 7—An adequate speci? Preferably, the same number of packages should be taken from each shipping unit in the lot sample. If differing numbers of packages are to be taken from shipping units in the lot sample, determine at random which shipping units are to have each number of packages drawn.

When packages other than beams contain more than one parallel wound end, select one end from which to prepare the three specimens. For beams, take three specimens from each end in the laboratory sample. Conditioning of Specimens 8. Rate of Operation and Gage Length 9. Break one or more trial specimens, observe the time-to-break, and adjust the rate of crosshead displacement if necessary. For CRL tension testing machines, the rate of force application per minute should be approximately three times the breaking force, and for CRE tension testing machines the rate of extension per minute should be approximately three times the elongation at break.

On CRT tension testing machines with interchangeable or adjustable pendulum weights, the lower capacity ranges result in longer times to break, and higher capacities result in shorter times. These approximate rates are not acceptable for referee testing where a time to break of 20 6 3 s is speci?

When elongation is measured, the change in the gage length must be considered in the calculation. When shrinkage interferes with determination of elongation measurements; cooling of the test chamber may be required between subsequent loading of individual specimens. Secure one end of the specimen in one of the clamps of the tension testing machine.

Place the other end in the other clamp, applying 5 6 0. Close the second clamp. Avoid touching the portion of the specimen between the clamps with bare hands. NOTE 8—Because of the difficulty of securing the same tension in all the? But, for unfamiliar materials it may be necessary to test with several different twist levels and determine the maximum breaking force.

Twist a test specimen length that is about mm 9 in. Place one end of the specimen in one clamp of the machine, tie a single overhand knot near the middle of the specimen, place the other end in the second clamp, and tighten the clamp. Take care that the knot is always tied in the direction speci?

Each specimen consists of two pieces of yarn taken from one package or end. Secure both ends of one piece in one clamp of the tension testing machine without a change in twist having the length of the loop about one half the gage length.

Pass one end of the second piece through the loop formed by the? Testing Conditions After preconditioning, bring the sample skeins to moisture equilibrium for testing in the standard atmosphere for testing textiles.

Equilibrium is considered to have been reached when two successive weighings not less than 15 min apart do not differ by more than 0. NOTE 9—Conditioning in skein form is much more rapid than conditioning of tightly wound packages and is needed whenever other tests are to be made on the same sample, that is, tests requiring a large amount of conditioned material.

However, the outer layers of a tight package reach approximate equilibrium in a reasonable length of time; and where only a few yards are to be used and extreme accuracy is not required as, for example, in production control work it may be more convenient to condition the yarn in package form. NOTE 10—It is recognized that in practice yarns are frequently not weighed to determine when moisture equilibrium has been reached.

While such a procedure cannot be accepted in cases of dispute, it may be sufficient in routine testing to expose the material to the standard atmosphere for testing for a reasonable period of time before the specimens are tested. A time of at least 24 h has been found acceptable in most cases. However, certain? When this is known, a preconditioning cycle, as described in Practice D may be agreed upon between contractual parties. Remove a specimen from the container and immediately mount the oven-dried specimen in the tension testing machine in the normal setup.

Testing must begin within 20 6 2 s after removal of the specimen from the container or discard the specimen and take a new one. Preheat the oven until equilibrium is reached at the speci? Mount the specimen in the tension testing machine in the normal setup. Set the oven for the speci? The specimens are exposed for the speci? Set the cold chamber for the speci? Measurement of Tensile Properties

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ASTM D2256 Thread and Yarn Tensile Testing

More D However, this statement is not applicable to knot and loop breaking force tests, tests on wet specimens, tests on oven-dried specimens, or tests on specimens exposed to low or high temperatures and should be used with caution for acceptance testing because factual information on between-laboratory precision and bias is not available. As a minimum, use the samples for such a comparative tests 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 a 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.

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A number in parentheses indicates the year of last reapproval. A superscript epsilon indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. Scope 1. NOTE 1—Special methods for testing yarns made from specic bers; namely, glass, ax, hemp, ramie, and kraft paper and for specic products; namely, tire cords and rope, have been published: Test Methods D , and Specication D Terminology 3.

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More D The objective is to minimize these contaminants to avoid filter plugging and other operational problems. Although tolerable levels of particulate contaminants have not yet been established for all points in fuel distribution systems, the total contaminant measurement is normally of most interest. The Appendix X1 color rating method is useful for fuel system monitoring purposes. No quantitative relationship exists between gravimetric and color rating test results. Scope 1.

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