ASTM D76-99(2005)
(Specification)Standard Specification for Tensile Testing Machines for Textiles
Standard Specification for Tensile Testing Machines for Textiles
ABSTRACT
This specification covers operating characteristics of tensile testing machines for the determination of the force-elongation properties of textile materials. Types of tensile machine covered in this specification are constant-rate-of-extension, constant-rate-of-traverse, and constant-rate-of-loading. Testing machines calibration shall be verified using the methods indicated in this specification, especially when moved to different locations to make sure that they still meet the specified tolerances. Motor-driven machine is preferred over manually driven machine. Constant-rate-of-traverse type machines shall not be used for measuring forces below fifty times their resolution. Machines shall be equipped with a device for measuring force. Clamping or holding devices shall be prescribed in test methods. Maximum allowable error, indicated force, recorded elongation, nominal gage length, and moving clamp speed shall be within the tolerances prescribed in the individual standards. Verification methods for recorded clamp displacement, recorded elongation, and nominal gage length, shall conform to the procedures indicated in this specification.
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 concerns, 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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Standards Content (Sample)
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Designation: D76 – 99 (Reapproved 2005)
Standard Specification for
Tensile Testing Machines for Textiles
ThisstandardisissuedunderthefixeddesignationD76;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 bench marks, n—marks placed on a specimen to
definegagelength,thatis,theportionofthespecimenthatwill
1.1 Thisspecificationcoverstheoperatingcharacteristicsof
be evaluated in a specific test.
three types of tensile testing machines used for the determina-
3.1.2 calibrate, v—to determine and record the relationship
tion of the force-elongation properties of textile materials.
betweenasetofstandardunitsofmeasureandtheoutputofan
These types of tensile testing machines are:
instrument or test procedure.
1.1.1 Constant-rate-of-extension, CRE.
3.1.2.1 Discussion—This term is also commonly used to
1.1.2 Constant-rate-of-traverse, CRT.
describe the checking of previously marked instruments, an
1.1.3 Constant-rate-of-loading (force), CRL.
operation more properly described as a description of verifi-
1.2 Specifications for tensile testing machines to measure
cation.
other tensile-related properties of textile materials not covered
3.1.3 capacity, n—for tensile testing machines, the maxi-
by this standard are given in the ASTM standards using those
mum force for which the machine is designed.
machines.
3.1.3.1 Discussion—Capacity is the maximum force the
1.3 The values stated in SI units are to be regarded as
tester-frameandthedrivesystemcanexerciseonthespecimen
standard; the values in inch-pound units are provided as
without inadmissible deformations of the tester-frame, etc.
information only and are not exact equivalents.
Within its capacity, there are available load-cells with different
1.4 The following safety hazards caveat pertains only to the
full-scale-ranges which may be chosen to select an appropriate
testmethodsdescribedinthisspecification: This standard does
full-scale-range for a special test.
not purport to address all of the safety concerns, if any,
3.1.4 clamp, n—that part of a testing machine used to grip
associated with its use. It is the responsibility of the user of this
the specimen by means of suitable jaws.
standard to establish appropriate safety and health practices
3.1.5 constant-rate-of-extension (CRE) type tensile testing
and determine the applicability of regulatory limitations prior
machine(CRE),n—intensiletesting,anapparatusinwhichthe
to use.
pulling clamp moves at a uniform rate, and the force-
2. Referenced Documents measuring mechanism moves a negligible distance with in-
creasing force, less than 0.13 mm (0.005 in.).
2.1 ASTM Standards:
3.1.6 constant-rate-of-load tensile testing machine (CRL),
D123 Terminology Relating to Textiles
n—in tensile testing,anapparatusinwhichtherateofincrease
D2256 Test Method for Tensile Properties of Yarns by the
of the force is uniform with time after the first 3 s and the
Single-Strand Method
specimen is free to elongate, this elongation being dependent
E4 Practices for Force Verification of Testing Machines
on the extension characteristics of the specimen at any applied
E74 Practice of Calibration of Force-Measuring Instru-
force.
ments for Verifying the Force Indication of Testing Ma-
3.1.7 constant-rate-of-traverse tensile testing machine
chines
(CRT), n—in tensile testing, an apparatus in which the pulling
3. Terminology
clampmovesatauniformrateandtheforceisappliedthrough
the other clamp, which moves appreciably to actuate a force-
3.1 Definitions:
measuring mechanism, producing a rate of increase of force or
extension that is usually not constant and is dependent on the
This specification is under the jurisdiction of ASTM Committee D13 on
extension characteristics of the specimen.
Textiles and is the direct responsibility of Subcommittee D13.58 on Yarn Test
3.1.8 effective carriage mass, n— in CRL-type tensile test-
Methods, General.
Current edition approved April 1, 2005. Published June 2005. Originally ing machine, the force actually applied to a specimen by the
approved in 1920. Last previous edition approved in 1999 as D76–99. DOI:
mass of the carriage, plus any added weight.
10.1520/D0076-99R05.
3.1.9 effective gage length, n— in tensile testing, the esti-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
matedlengthofthespecimensubjectedtoastrainequaltothat
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standardsvolume information, refer to the standard’s Document Summary page on
observed for the true gage length.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D76 – 99 (2005)
3.1.9.1 Discussion—The effective gage length can be cal- 3.1.18 sensitivity, n— in mechanical systems, the smallest
culated using the following equation: change that can be induced on a material by the system and be
reliably measured. (See also least count.)
E
N
G 5 G 3 (1)
E N 3.1.19 stress, n—the resistance to deformation developed
E
T
within a material subjected to an external force.
where:
3.1.20 tensile testing machine, n—an apparatus designed to
G = effective gage length,
E impart, or transmit, force/extension, or stress/strain, to a
G = nominal gage length,
N
material and to measure the effect of the action. (See also
E = percent elongation based on nominal gage length,
N
constant-rate-of-extension tensile testing machine, constant-
and
rate-of-load type tensile testing machine, constant-rate-of-
E = percent elongation based on true gage length.
T
traverse tensile testing machine.)
3.1.10 grip, v—in tensile testing, to hold, grasp, or secure,
3.1.21 test skein, n—a small skein which has a prescribed
for example, to grip the specimen by the jaws of the clamps.
length of yarn and is used for the determination of linear
3.1.11 jaw face, n—in tensile testing machines, the surface
density or breaking, or both.
of a jaw which in the absence of a liner contacts the specimen.
3.1.22 time-to-break, n—the time interval during which a
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
3.1.25 For definitions of other textile terms used in this
difference between the scale and vernier graduations measured
specification, refer to Terminology D123.
in terms of scale units. If the indicating mechanism includes a
3.2 Abbreviations:Abbreviations:
steppeddetent,thedetentactionmaydeterminetheleastcount.
3.2.1 CRE—constant-rate-of-extension.
(See also sensitivity, in mechanical systems.)
3.2.2 CRL—constant-rate-of-load.
3.1.15 nominal gage length, n— in tensile testing,(1) the
3.2.3 CRT—constant-rate-of-traverse.
lengthofaspecimenunderspecifiedpretensionmeasuredfrom
4. Performance Requirements
nip-to-nip of the jaws of the holding clamps in their starting
position at the beginning of the test, and including any portion 4.1 Individual ASTM methods for tensile testing of textile
of the specimen in contact with bollard or snubbing surfaces.
materials that prescribe apparatus which conforms to this
specification shall also include such other detailed specifica-
(2) the length of a specimen under specific pretension
tions as may be necessary to describe the testing machine and
betweenfrets,ininstrumentswherethespecimenisnotheldby
its operation completely.
clamps, for example, in a vibroscope.
4.1.1 This specification shall not be construed as being
(3) thelengthofaspecimenmeasuredbetweenthepointsof
intended to preclude the evolution of improved methods of
attachment to the tabs while under specified pretension.
testing or testing apparatus, which is recognized as being vital
3.1.15.1 Discussion—The calculated percentage of elonga-
in an advancing technology.
tion based on the nominal gage length may be in error due to
4.2 Comparison of results from tensile testing machines
extension of that part of the specimen which lies between the
operating on different principles is not recommended. When
jaws of the clamps.
these machines are used for comparison testing however,
3.1.16 response time, n— in tensile testing machines, the
constant time-to-break at 20 6 3 s is the established way of
timerequiredbytheindicatingorrecordingdevicetoreflectan
producing data, but even then the data may differ significantly.
instantaneous change in force, usually 0 to 90% of full scale.
4.2.1 Comparison of test data from machines of the same
3.1.17 sensitivity, n— in electronic systems, the minimum
type, especially two or more CRT-type or two or more
change in the input signal that produces a change in the output
CRL-type machines, requires consideration of the effect of
signal that can be reliably measured.
individualmachinecharacteristics;forexample,inertiaeffects,
3.1.17.1 Discussion—Sometimes the term sensitivity is capacity, sensitivity, type of loadcell, etc., which may cause
used for the ratio of the response or change induced in the significant differences in results even though uniform proce-
output to a stimulus or change in the input. For this ratio dures are employed. Data from different CRE-type testing
“amplification” is a better term. machines, however, should not be significantly different.
D76 – 99 (2005)
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-
mize specimen failure in the clamped areas. Clamp liners may
Type Principle of Operation
CRE Constant rate-of-extension
be used, provided the above conditions are met.
CRT Constant rate-of-traverse (pendulum type)
5.3.5 When the flat-faced type clamp proves unsatisfactory
CRL Constant rate-of-load (inclined plane type)
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 devices conforming to Practice E74 are required for
5.1.2 CRT-Type—A testing machine in which the pulling
verificationofcalibration.Calipers,asteelrulethatcanberead
clampmovesatauniformrateandtheforceisappliedthrough
to 0.25 mm (0.01 in.), or a suitable cathetometer, and a stop
the other clamp, which moves appreciably to actuate a force-
watch are required for verification of recorded elongation, and
measuring mechanism, producing a rate of increase of force or
crosshead and chart speed.
extensionwhichisusuallynotconstantandisdependentonthe
6. Machine Operational Design
extension characteristics of the specimen.
5.1.3 CRL-Type—A testing machine in which the rate of
6.1 The use of motor-driven machines is preferred over
increase of the force is uniform with time after the first3sand
manually driven machines because of improved control of
the specimen is free to elongate, this elongation being depen-
testing.
dent upon the extension characteristics of the specimen at any
6.2 Testing machines of the CRT-type shall not be used for
applied force.
measuring forces below fifty times their resolution. For ex-
5.1.4 Multiple-Purpose Type—Machines capable of being
ample,iftheminimumforcethatcanbereadis0.5cN(0.5gf),
operated as both a CRE-type and a CRL-type may be used.
thetestingmachinemaynotbeusedformate
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