ASTM D76-99
(Specification)Standard Specification for Tensile Testing Machines for Textiles
Standard Specification for Tensile Testing Machines for Textiles
SCOPE
1.1 This specification covers the operating characteristics of three types of tensile testing machines used for the determination of the force-elongation properties of textile materials. These types of tensile testing machines are:
1.1.1 Constant-rate-of-extension, CRE.
1.1.2 Constant-rate-of-traverse, CRT.
1.1.3 Constant-rate-of-loading (force), CRL.
1.2 Specifications for tensile testing machines to measure other tensile-related properties of textile materials not covered by this standard are given in the ASTM standards using those machines.
1.3 The values stated in SI units are to be regarded as standard; the values in inch-pound units are provided as information only and are not exact equivalents.
1.4 The following safety hazards caveat pertains only to the test methods described in this specification: This standard does not purport to address all of the safety problems, if any, associated with its use. 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.
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Designation: D 76 – 99
Standard Specification for
Tensile Testing Machines for Textiles
ThisstandardisissuedunderthefixeddesignationD76;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D5034 Test Method for Breaking Strength and Elongation
of Textile Fabrics (Grab Test)
1.1 Thisspecificationcoverstheoperatingcharacteristicsof
D5035 Test Method for Breaking Strength and Elongation
three types of tensile testing machines used for the determina-
of Textile Fabrics (Strip Method)
tion of the force-elongation properties of textile materials.
E4 Practices for Force Verification of Testing Machines
These types of tensile testing machines are:
E74 Practice of Calibration of Force-Measuring Instru-
1.1.1 Constant-rate-of-extension, CRE.
ments for Verifying the Force Indication of Testing Ma-
1.1.2 Constant-rate-of-traverse, CRT.
chines
1.1.3 Constant-rate-of-loading (force), CRL.
1.2 Specifications for tensile testing machines to measure
3. Terminology
other tensile-related properties of textile materials not covered
3.1 Definitions:
by this standard are given in the ASTM standards using those
3.1.1 bench marks, n—marks placed on a specimen to
machines.
definegagelength,thatis,theportionofthespecimenthatwill
1.3 The values stated in SI units are to be regarded as
be evaluated in a specific test.
standard; the values in inch-pound units are provided as
3.1.2 calibrate, v—to determine and record the relationship
information only and are not exact equivalents.
betweenasetofstandardunitsofmeasureandtheoutputofan
1.4 The following safety hazards caveat pertains only to the
instrument or test procedure.
testmethodsdescribedinthisspecification: This standard does
3.1.2.1 Discussion—This term is also commonly used to
not purport to address all of the safety concerns, if any,
describe the checking of previously marked instruments, an
associated with its use. It is the responsibility of the user of this
operation more properly described as a description of verifi-
standard to establish appropriate safety and health practices
cation.
and determine the applicability of regulatory limitations prior
3.1.3 capacity, n—for tensile testing machines, the maxi-
to use.
mum force for which the machine is designed.
2. Referenced Documents 3.1.3.1 Discussion—Capacity is the maximum force the
tester-frameandthedrivesystemcanexerciseonthespecimen
2.1 ASTM Standards:
2 without inadmissible deformations of the tester-frame, etc.
D123 Terminology Relating to Textiles
Within its capacity, there are available load-cells with different
D580 Specification for Greige Woven Glass Tapes and
2 full-scale-ranges which may be chosen to select an appropriate
Webbings
full-scale-range for a special test.
D885 Methods of Testing Tire Cords, Tire Cord Fabrics,
3.1.4 clamp, n—that part of a testing machine used to grip
and Industrial Filament Yarns Made from Man-Made
the specimen by means of suitable jaws.
Organic-Base Fibers [Metric]
2 3.1.5 constant-rate-of-extension (CRE) type tensile testing
D1578 Test Method for Breaking Strength of Skeins
machine(CRE),n—intensiletesting,anapparatusinwhichthe
D2256 Test Method for Tensile Properties of Yarns by the
pulling clamp moves at a uniform rate, and the force-
Single-Strand Method
measuring mechanism moves a negligible distance with in-
D3822 TestMethodforTensilePropertiesofSingleTextile
creasing force, less than 0.13 mm (0.005 in.).
Fibers
3.1.6 constant-rate-of-load tensile testing machine (CRL),
n—in tensile testing, an apparatus in which the rate of increase
This specification is under the jurisdiction of ASTM Committee D-13 on
of the force is uniform with time after the first 3 s and the
Textiles and is the direct responsibility of Subcommittee D13.58 on Yarn Test
Methods, General.
Current edition approved May 10, 1999. Published July 1999. Originally
published as D76–20T. Last previous edition D76–93.
Annual Book of ASTM Standards, Vol 07.01.
3 4
Annual Book of ASTM Standards, Vol 07.02. Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D76
specimen is free to elongate, this elongation being dependent 3.1.15.1 Discussion—The calculated percentage of elonga-
on the extension characteristics of the specimen at any applied tion based on the nominal gage length may be in error due to
force. extension of that part of the specimen which lies between the
3.1.7 constant-rate-of-traverse tensile testing machine jaws of the clamps.
(CRT), n—in tensile testing, an apparatus in which the pulling
3.1.16 response time, n— in tensile testing machines, the
clamp moves at a uniform rate and the force is applied through
timerequiredbytheindicatingorrecordingdevicetoreflectan
the other clamp, which moves appreciably to actuate a force-
instantaneous change in force, usually 0 to 90% of full scale.
measuring mechanism, producing a rate of increase of force or
3.1.17 sensitivity, n— in electronic systems, the minimum
extension that is usually not constant and is dependent on the
change in the input signal that produces a change in the output
extension characteristics of the specimen.
signal that can be reliably measured.
3.1.8 effective carriage mass, n— in CRL-type tensile test-
3.1.17.1 Discussion—Sometimes the term sensitivity is
ing machine, the force actually applied to a specimen by the
used for the ratio of the response or change induced in the
mass of the carriage, plus any added weight.
output to a stimulus or change in the input. For this ratio
3.1.9 effective gage length, n— in tensile testing, the esti-
“amplification” is a better term.
matedlengthofthespecimensubjectedtoastrainequaltothat
3.1.18 sensitivity, n— in mechanical systems, the smallest
observed for the true gage length.
change that can be induced on a material by the system and be
3.1.9.1 Discussion—The effective gage length can be cal-
reliably measured. (See also least count.)
culated using the following equation:
3.1.19 stress, n—the resistance to deformation developed
E
N
within a material subjected to an external force.
G 5 G 3 (1)
E N
E
T
3.1.20 tensile testing machine, n—an apparatus designed to
where: impart, or transmit, force/extension, or stress/strain, to a
G 5 effective gage length, material and to measure the effect of the action. (See also
E
G 5 nominal gage length,
constant-rate-of-extension tensile testing machine, constant-
N
E 5 percent elongation based on nominal gage length,
rate-of-load type tensile testing machine, constant-rate-of-
N
and
traverse tensile testing machine.)
E 5 percent elongation based on true gage length.
T
3.1.21 test skein, n—a small skein which has a prescribed
3.1.10 grip, v—in tensile testing, to hold, grasp, or secure,
length of yarn and is used for the determination of linear
for example, to grip the specimen by the jaws of the clamps.
density or breaking, or both.
3.1.11 jaw face, n—in tensile testing machines, the surface
3.1.22 time-to-break, n—the time interval during which a
of a jaw which in the absence of a liner contacts the specimen.
specimen is under prescribed conditions of tension and is
3.1.12 jaw liner, n—in tensile testing machines, any mate-
absorbing the energy required to reach maximum load.
rial placed between the jaw face and the specimen to improve
3.1.22.1 Discussion—Time-to-break does not include the
the holding power of the jaws.
time required to remove slack from the specimen.
3.1.13 jaws, n—in tensile testing machines, the elements of
3.1.23 true gage length, n—in tensile testing, a precise
a clamp which grip the specimen.
length between welldefined bench marks located on the speci-
3.1.14 least count, n—in tensile testing machines,thesmall-
men while under known tension in the unsupported portion
est change in the indicated property that can customarily be
between the holding clamps and free from contact with any
determined (see also sensitivity).
snubbing surfaces or other sources which could result in
3.1.14.1 Discussion—In tensile testing machines with close
nonuniform strain.
graduations for force or elongation indications, the least count
3.1.24 verify, v—(1) to determine whether a previously
may be the value of a graduation interval; with open gradua-
calibrated instrument, standard solution, or other standard is
tions, or with magnifiers for reading, the least count may be an
still properly calibrated, (2) to establish that an operation has
estimated fraction (rarely as fine as 0.1) of a graduation
been completed correctly.
interval; and with verniers, the least count is ordinarily the
difference between the scale and vernier graduations measured 3.1.25 For definitions of other textile terms used in this
specification, refer to Terminology D123.
in terms of scale units. If the indicating mechanism includes a
steppeddetent,thedetentactionmaydeterminetheleastcount.
3.2 Abbreviations:
(See also sensitivity, in mechanical systems.)
3.2.1 CRE—constant-rate-of-extension.
3.1.15 nominal gage length, n— in tensile testing,(1) the
3.2.2 CRL—constant-rate-of-load.
lengthofaspecimenunderspecifiedpretensionmeasuredfrom
3.2.3 CRT—constant-rate-of-traverse.
nip-to-nip of the jaws of the holding clamps in their starting
position at the beginning of the test, and including any portion
4. Performance Requirements
of the specimen in contact with bollard or snubbing surfaces.
(2) the length of a specimen under specific pretension 4.1 Individual ASTM methods for tensile testing of textile
betweenfrets,ininstrumentswherethespecimenisnotheldby
materials that prescribe apparatus which conforms to this
clamps, for example, in a vibroscope. specification shall also include such other detailed specifica-
(3) thelengthofaspecimenmeasuredbetweenthepointsof tions as may be necessary to describe the testing machine and
attachment to the tabs while under specified pretension. its operation completely.
D76
4.1.1 This specification shall not be construed as being 5.1.4 Multiple-Purpose Type—Machines capable of being
intended to preclude the evolution of improved methods of operated as both a CRE-type and a CRL-type may be used.
testing or testing apparatus, which is recognized as being vital
5.2 Measuring Devices—Machinesshallbeequippedwitha
in an advancing technology. suitable device for measuring the force and, when needed, a
4.2 Comparison of results from tensile testing machines
device to measure elongation. Preferably a force-elongation
operating on different principles is not recommended. When curveshallberecordedgraphically,ortheforceandelongation
these machines are used for comparison testing however,
data may be indicated on appropriate scales or displays.
constant time-to-break at 20 6 3 s is the established way of
5.2.1 Most testing machines record only force-elongation
producing data, but even then the data may differ significantly.
data. When the capacity of a testing machine is adjusted to fit
4.2.1 Comparison of test data from machines of the same
the predetermined linear density or cross-sectional area of the
type, especially two or more CRT-type or two or more
specimen, the force recorded will be stress.When the machine
CRL-type machines, requires consideration of the effect of
is adjusted to record extension in terms of unit specimen
individual machine characteristics; for example, inertia effects,
length, the chart can be read directly in percent elongation or
capacity, sensitivity, type of loadcell, etc., which may cause strain.Whentheseconditionsdonotexist,theforce-elongation
significant differences in results even though uniform proce-
curve must be converted to obtain stress-strain characteristics.
dures are employed. Data from different CRE-type testing
5.2.2 Theforce-indicatingandforce-recordingdevicesshall
machines, however, should not be significantly different.
be in conformance with the requirements of this specification
4.2.2 In any case, all types of tensile testing machines must
as to accuracy, sensitivity, and response time, and shall permit
satisfy the accuracy requirements as given in Section 7.
calibration or verification by appropriate methods described or
4.3 While changes in humidity affect the tensile properties
referenced herein.
ofmanytextilematerials,changesinhumiditynormallydonot
5.3 Clamping or Holding Devices—Specimen clamping or
affect the testing machines themselves.
holding devices shall be prescribed in the individual test
4.4 When machines are moved to different locations, their
methods in sufficient detail for all users to employ the same or
calibrationshallbeverifiedtomakesurethattheystillmeetthe
comparable devices.
specified tolerances.
5.3.1 The prescribed specimen clamping or holding devices
4.5 When each of the sub-systems (force, extension, clamp-
shall be designed to ensure that the pulling axis of the testing
ing) has been individually calibrated, verified, or checked, it is
machine and the central axis of a properly mounted specimen
recommendedthatthetotalsystembeverifiedusingastandard
coincide.
materialappropriateforthetypetestingtobecarriedout. This
5.3.2 The clamping or holding device may be designed for
testing of the total system is the established way of ensuring
manual or automatic mounting of specimens.
that the clamping system is operating properly.
5.3.3 The required clamping force can be obtained with the
clamping or holding devices by any suitable mechanism; for
5. Apparatus
example, screw, cam action, pneumatic, or toggle.
5.1 Tensile Testing Machines—Tensile testing machines for
5.3.4 Clamping surfaces in contact with a test specimen
textile materials are classified according to their operating
shall be of any suitable material and configuration which
principle as follows:
provides the required restraint, preclude slippage, and mini-
Type Principle of Operation
mize specimen failure in the clamped areas. Clamp liners may
CRE Constant rate-of-extension
be used, provided the above conditions are met.
CRT Constant rate-of-traverse (pendulum type)
CRL Constant rate-of-load (inclined plane type)
5.3.5 When the flat-faced type clamp proves unsatisfactory
because of slippage or excessive breakage in the clamp,
5.1.1 CRE-Type—A testing machine in which the pulling
snubbingtypedevices(capstan,drum,split-drum,etc.)maybe
clamp moves at a uniform rate, and the force-measuring
used.
mechanism (load cell) moves a negligible distance with in-
5.4 Calibrating Devices—Calibrating weights or other cali-
creasing force less than 0.13 mm (0.005 in.).
brating dev
...
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