Standard test Method for
Tensile Properties of Plastics1
This standard is issued under the fixed designation D 638; the number immediately following跑步机坡度
the designation indicates the year of original adoption or, in the ca of revision, the year of
last revision. A number in parenthes indicates the year of last reapproval. A superscript
epsilon (∈) indicates an editorial change since the last revision or reapproval.
This test method has been approved for u by agencies of the Department of Defen.
Consult the DoD Index of Specifications and Standards for the specific year of issue which has
been adopted by the Department of Defen.
1. Scope
1.1 This test method covers the determination of the tensile properties of unreinforced and
山东的大学有哪些reinforced plastics in the form of standard dumbbell-shaped test specimens when tested under defined conditions of pretreatment, temperature, humidity, and testing machine speed.
Note 1—This test method and ISO 527-1 are technically equivalent.
Note 2—A complete metric companion to Test Method D 638 has been developed—D638M.
Note 3—This test method is not intended to cover preci physical procedures. It is recognized that the constant-rate-of-cross-head-movement type of test leaves much to be desired form a theoretical standpoint, that wide differences may exist between rate of crosshead movement and rate of strain between gage marks on the specimen, and that the testing speeds specifies disgui important effects characteristic of materials in the plastic state. Further, it si realized that variations in the thickness of test specimens, which are permitted by the procedures, produce variations in the surface-volume ratios of such specimens, and that the variations may influence the test results. Hence, where directly comparable results are desired, all samples should be of equal thickness. Special additional tests should be ud where more preci physical data are needed.
Note 4—This test method may be ud for testing phenolic molded resin or laminated materials. However, where the materials are ud as electrical insulation, such materials should be tested in
accordance with Test Methods D 229 and Test Method D 651.
Note 5—For tensile properties of resin-matrix composites reinforced with oriented continuous or discontinuous high modulus >20 GPa (>3.0×106 psi) fibers, tests shall be made in accordance with Test Method D 3039.
1.2 This test method can be ud for testing materials of any thickness up to 14 mm (0.55 in.).
However, for testing specimens in the form of thin sheeting, including film less than 1.0 mm
(0.04 in.) in thickness, Test Methods D882 is the preferred test method. Material with a thickness
greater than 14 mm (0.55 in.) must be reduced by machining.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parenthes
are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its
u. It is the responsibility of the ur of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to u.
2. Referenced Documents
2.1 ASTM Standards:
D229 Test Methods for Rigid Sheet and Plate Materials Ud for Electrical Insulation2.
D374 Test Methods for Thickness of Solid Electrical Insulation2.
D412 Test Methods for Vulcanized Rubber and Thermoplastic Rubbers and
Elastomers—Tension3.
D618 Practice for Conditioning Plastics and Electrical Insulating Materials for Testing4.
D638M Test Method for Tensile Properties of Plastics (Metric)4.
D651 Test Method for Tensile Strength of Molded Electrical Insulating Materials2.
D882 Test Methods for Tensile Properties of Thin Plastic Sheeting4.
D883 Terminology Relating to Plastics4.
D1822 Test Method for Tensile Properties of Fiber-Resin Composites5.
D3039 Classification System for Specifying Plastic Materials6.
D4066 Specification for Nylon Injection and Extrusion Materials (PA)6.
E 4 Practices for Force Verification of Testing Machines7.
E 83 Practice for Verification and Classification of Extensometers7.
E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test
Method8.
2.2 ISO Standard:
ISO 527 – 1 Determination of Tensile Properties.
3. Terminology
3.1 Definitions—Definitions of terms applying to this test method appear in Terminology D 883 and
Annex A2.
4. Significance and U
4.1 This test method is designed to produce tensile property data for the control and specification of
plastic materials. The data are also uful for qualitative characterization and for rearch and development. For many materials, there may be a specification that requires the u of this test method, but with some procedural modifications that take precedence when adhering to the
specification. Therefore, it is advisable to refer to that material specification before using this
test method. Table 1 in Classification D 4000 lists the ASTM materials standards that currently exist.
4.2 Tensile properties may vary with specimen preparation and with speed and environment of
testing. Conquently, where preci comparative results are desired, the factors must be
滑板的英语carefully controlled.
4.2.1 It is realized that a material cannot be tested without also testing the method of
preparation of that material. Hence, when comparative tests of materials per are desired,
the greatest care must be exercid to ensure that all samples are prepared in exactly the
same way, unless the test is to include the effects of sample preparation. Similarly, for
referee purpos or comparisons within any given ries of specimens, care must be taken
to cure the maximum degree of uniformity in details of preparation, treatment, and
handling.
4.3 Tensile properties may provide uful data for plastics engineering design purpos. However,
becau of the high degree of nsitivity exhibited by may plastics to rate of straining and
environmental conditions, data obtained by this test method cannot be considered valid for
applications involving load-time scales or environments widely different from tho of this test method. In cas of such dissimilarity, no reliable estimation of the limit of ufulness can be
made for most plastics. This nsitivity to rate of straining and environment necessitates testing over a broad load-time scale (including impact and creep) and range of environmental conditions if tensile properties are to suffice for engineering design purpos.
Note 6—Since the existence of a true elastic limit in plastics (as in many other organic materials and in many metals) is debatable, the propriety of applying the term “elastic modulus” in its quoted, generally accepted definition to describe the “stiffness” r “rigidity” of a plastic has been riously questioned. The exact tress-strain characteristics of plastic materials are highly dependent on such factors as rate of application of stress, temperature, previous history of specimen, etc. However, stress-strain curves for plastics, determined as described in this test method, almost always show a linear region at low stress, and a straight line drawn tangent to this portion of the curve permits calculation of an elastic modulus of the usually defined type. Such a constant is uful if its arbitrary nature and dependence on time, temperature, and similar factors are realized.
葫芦怎么做5. Apparatus
5.1 Testing Machine—A testing machine of the constant-rate-of –crosshead-movement type and
comprising esntially the following:
5.1.1 Fixed Member—A fixed or esntially stationary member carrying one grip.
5.1.2 Movable Member—A movable member carrying a cond grip.
心神不定的意思
5.1.3 Grips—Grips of holding the test specimen between the fixed member and the movable
member of the testing machine can be either the fixed or lf-aligning type.
5.1.3.1 Fixed grips are rigidly attached to the fixed and movable member of the testing
machine. When this type of grip is ud extreme care should be taken to ensure
that the test specimen is inrted and clamped so that the long axis of the test
specimen coincides with the direction of pull through the center line of the grip
asmbly.
5.1.3.2 Slef-aligning grips are attached to the fixed and movable members of the testing
machine in such a manner that they will move freely into alignment as soon as
any load is applied so that the long axis of the test specimen will coincide with
the direction of the applied pull through the center line of the grip asmbly. The
specimens should be aligned a perfectly as possible with the direction of pull so
that no rotary motion that may induce slippage will occur in the grips; there is a
limit to the amount of misalignment lf-aligning grips will accommodate.
5.1.3.3 The test specimen shall be held in such a way that slippage relative to the grips is
prevented insofar as possible. Grip surfaces that are deeply scored or rrated
with a pattern similar to tho of a coar single-cut file, rrations about 2.4mm
(0.09 in.) apart and about 1.6 mm (0.06 in.) deep, have been found satisfactory
for most thermoplastics. Finer rrations have been found to be more satisfactory
for harder plastics, such as the thermotting materials. The rrations should be
kept clean and sharp. Breaking in the grips may occur at times, even when deep
rrations or abraded specimen surfaces are ud; other techniques must be ud
in the cas. Other techniques that have been found uful, particularly with
smooth-faced grips, are abrading that portion of the surface of the specimen that
will be in the grips, and interposing thin pieces of abrasive cloth, abrasive paper,
or plastic or rubber-coated fabric, commonly called hospital sheeting, between
the specimen and the grip surface. No. 80 double-sided abrasive paper has been
found effective in many cas. An open-mesh fabric, in which the threads are
coated with abrasive paper has been effective. Reducing the cross-ctional area
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of the specimen may also be effective. The u of special types of grips is
sometimes necessary to eliminate slippage and breakage in the grips.
5.1.4 Drive Mechanism—A drive mechanism for imparting to the movable member a uniform,
controlled velocity with respect to the stationary member, with this velocity to be
regulated as specified in Section 9.
5.1.5 Load Indicator—A suitable load-indicating mechanism capable of showing the total
tensile load carried by the test specimen when held by the grips. This mechanism shall be
esntially free of inertia lag at the specified rate of testing and shall indicate the load
with an accuracy of ±1% of the indicated value, or better. The accuracy of the testing
machine shall be verified in accordance with Practices E 4.
Note 7—Experience has shown that many testing machines now in u are incapable of
maintaining accuracy for as long as the periods between inspection recommended in Practices E
4. Hence, it is recommended that each machine be studied individually and verified as often as
may be found necessary. It frequently will be necessary to perform this function daily.
5.1.6 The fixed member, movable member, drive mechanism, and grips shall be constructed of such materials and in such proportions that the total elastic longitudinal strain of the system constituted by the parts does not exceed 1% of the total longitudinal strain between the two gage marks on the test specimen at any time during the test and at any load up to the rated capacity of the machine.
5.2 Extension Indicator (extensometer)—A suitable instrument shall be ud for determining the
distance between two designated points within the gage length of the test specimen as the
specimen is stretched. For referee purpos, the extensometer must be t at the full gage length of the specimen, as shown in Fig. 1. It is desirable, but not esntial, that this instrument
automatically record this distance, or any change in it, as a function of the load on the test
specimen, or of the elapd time from the start of the test, or both. If only the latter is obtained, load-time data must also be taken. This instrument shall be esntially free of inertia at the
specified speed of testing. Extensometers shall be classified and their calibration periodically verified in accordance with Practice E83.
5.2.1 Modulus-of Elasticity Measurements—For modulus-of-elasticity measurements, an
extensometer with a maximum strain error of 0.0002 mm/mm (in./in.) that automatically
and continuously records shall be ud. A class B-2 extensometer (Practice E 83) meets
this requirement.
5.2.2 Low-Extension Measurements—For elongation-at-yield and low-extension measurements
(nominally 20% or less), the same above extensometer, attenuated to 20% extension, may
be ud. In any ca, the extensometer system must meet at least Class C (Practice E 83)
requirements, which include a fixed strain error of 0.001 strain or ±1.0% of the indicated
strain, whichever is greater.
5.2.3 High-Extension Measurements—For measurement at elongations greater than 20%,
measuring techniques with error no greater than ±10% of the measured value are
acceptable.国际象棋棋谱
5.3 Micrometers—Suitable micrometers for measuring the width and thickness of the test specimen
to an incremental discrimination of at least 0.025 mm (0.001 in.) should be ud. All width and thickness measurements of rigid and mirigid plastics may be measured with a hand
micrometer with ratchet. A suitable instrument for measuring the thickness of nonrigid test
specimens shall have: (1) a contact measuring pressure of 25 ±2.5kPa (3.6 ±0.36 psi), (2) a
movable circular contact foot 6.35 ±0.025 mm (0.250 ±0.001 in.) in diameter, and (3) a lower fixed anvil large enough to extend beyond the contact foot in all directions and being parallel to the contact foot within 0.005 mm (0.0002 in.) over the entire foot area. Flatness of foot and anvil shall conform to the portion of the Calibration Section of Test Methods D374, which address “flatness of surfaces of micrometers.”
5.3.1 An optional instrument equipment with a circular contact foot 15.88 ±0.08 (0.625 ±0.003
in.) in diameter is recommended for thickness measuring of process samples or larger
specimens at least 15.88 mm (0.625 in.) in minimum width.
6. Test Specimens
6.1 Sheet, Plate, and Molded Plastics:
6.1.1 Rigid and Semirigid Plastics—The test specimen shall conform to the dimensions shown
in Fig. 1. The Type I specimen is the preferred specimen and shall be ud where
sufficient material having a thickness of 7 mm (0.28 in.) or less is available. The Type II
specimen may be ud when a material does not break in the narrow ction with the
preferred Type I specimen. The Type V specimen shall be ud where only limited
material having a thickness of 4 mm (0.16 in.) or less is available for evaluation, or where
a large number of specimens are to be expod in a limited space (thermal and
environmental stability tests, etc.). the Type IV specimen should be ud when direct
comparisons are required between materials in different rigidity cas (that is, nonrigid
and mirigid). The Type III specimen must be ud for all materials with a thickness of
greater than 7 mm (0.28 in.) but not more than 14 mm (0.55 in.).
6.1.2 Nonrigid Plastics—The test specimen shall conform to the dimensions shown in Fig. 1.
The Type IV specimen shall be ud for testing nonrigid plastics with a thickness of 4 mm
(0.16 in.) or less. The Type III specimen must be ud for all materials with a thickness
greater than 7 mm (0.28 in.) but not more than 14 mm (0.55 in.).
6.1.3 Reinforced Composites—The test specimen for reinforced composites, including highly
orthotropic laminates, shall conform to the dimensions of the Type I specimen shown in
Fig. 1.
6.1.4 Preparation—Test specimens shall be prepared by machining operations, or die cutting,
from materials in sheet, plate, slab, or similar form. Materials thicker than 14 mm (0.55
in.) must be machined to 14 mm (0.55 in.) for ud as Type III specimens. Specimens can
also be prepared by molding the material to be tested.
Note 8—Test results have shown that for some materials such as glass cloth, SMC, and BMC lamina
我的前半生贺涵tes, other specimen types should be considered to ensure breakage within the gage length of the specimen, as mandated by 8.3.
Note 9—When preparing specimens from certain composite laminates such as woven roving, or glass cloth, care must be exercid in cutting the specimens parallel to the reinforcement. The reinforcement will be significantly weakened by cutting on a bias, resulting in lower laminate properties, unless testing of specimens in a direction other than parallel with the reinforcement constitutes a variable being studied.
Note 10—Specimens prepared by injection molding may have different tensile properties than specimens prepared by machining or die-cutting becau of the orientation induced. This effect may be more pronounced in specimens with narrow ctions.
6.2 Rigid Tubes:
6.2.1 The test specimen for rigid tubes shall be as shown in Fig. 2. The length, L, shall be as
shown in the table in Fig. 2. A groove shall be machined around the outside of the
specimen at the center of its length so that the wall ction after machining shall be 60%
of the original nominal wall thickness. This groove shall consist of a straight ction 57.2
mm (2.25 in.) in length with a radius of 76 mm (3 in.) at each end joining it to the outside
diameter. Steel or brass plugs having diameters such that they will fit snugly inside the
tube and having a length equal to the full jaw length plus 25 mm (1 in.) shall be placed in
the ends of the specimens to prevent crushing. They can be located conveniently in the
tube by parating and supporting them on a threaded metal rod. Details of plugs and test
asmbly are shown in Fig. 2.
6.3 Rigid Rods:
6.3.1 The test specimen for rigid rods shall be as shown in Fig. 3. The length, L, shall be as
shown in the table in Fig. 3. A groove shall be machined around the specimen at the
center of its length so that the diameter of the machined portion shall be 60% of the
original nominal diameter. This groove shall consist of a straight ction 57.2 mm (2.25
in.) in length with a radius of 76 mm (3 in.) at each end joining it to the outside diameter.
