ASTM D 638-08

Standard testing method for

Tensile properties of plastics
This standard is issued under the fixed designation D 638: the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of the last revision. A number in parentheses indicates the year of the last
renewal of recognition. The epsilon exponent (E) indicates an editorial change since the last review or
renewal of recognition

This standard has been approved for use by the bodies of the Ministry of Defense.

1-Scope

1.1 This testing method covers the determination of stress properties of

unreinforced and reinforced plastics in the standard form of samples in shape
of the dumbbell, when tested under defined pre-treatment conditions,
temperature, humidity, and speed test machine.

1.2 This testing method can be used to test materials of any

thickness up to 14 mm (0.55 inches). However, for the tests
specimens in the form of thin sheets, including films less than 1.0 mm (0.04
inches) thick, test method D 882 is the preferred method.
Materials thicker than 14 millimeters (0.55 inches) must be
reduced in machining.

1.3 This test method includes the possibility of determining coefficient of

Poisson at room temperature.

NOTE 1 - This test method and ISO 527-1 are technically equivalent.

NOTE 2 - This method is not intended to precisely cover procedures

physicists. It is recognized that the constant rate of movement is a type of test
leaves much to be desired from a theoretical point of view, what large differences can
to exist between the circulation rate and the tension cross rate between the brands
bitola about the model, and that the specified speed tests disguise
important effects characteristics of materials in state. Further plastic, that
it was noticed that variations in the thicknesses of test specimens. which are
allowed by these procedures, produce variations in surface-volume
specimen ratios such that these variations can influence the results of
test. Then, when the desired directly comparable results.
samples must be of equal thickness. Especially complementary examinations he
should be used when physical data is most needed.

NOTE 3 - This method can be used to test phenolics, molded, resin

or laminated material. However, when these materials are used as
electrical insulation, these materials must be tested according to the
testing methods D229 and D651.

1
NOTE 4 - For tensile properties of resin matrix composites
reinforced with continuous or discontinuous guidance elevated module > 20 GPa
1> 3.0 x 10^6 psi), fibers, the tests must be conducted according to the test
method D3039 D3039M.

The test data obtained by this method is relevant and appropriate.

for use in the engineering project.

1.5

1.6 This standard does not intend to address all safety concerns, if
to have, associated with its use, is the responsibility of the user of this
standard to establish adequate safety and health practices and
determine the applicability of regulatory limits before use.

2-Reference Documents
2.1 ASTM Standards

D 229 Test methods for rigid sheet and plate materials used for
electrical insulation.

D 412 Test methods for vulcanized and thermoplastic rubber

Elastomers - Tension.

D 618 Practice of conditioning plastics under tension.

D 651 Test method for tensile strength of insulating electrical material.

D 882 Testing method for tensile properties of thin plastic 'sheet'.

D 883 Terminology related to plastic.

D 1 882 Test method for impact energy of tensile rupture,

plastics and insulating electrical materials.

D 3039 / D 3039M Test method for tensile properties of matrix

polymeric, composite materials.

D 400 Classification system for plastic specification.

D 4066 Classification system for the injection and extrusion of nylon, materials
(PA).

D 5947 Testing method for physical or solid dimensions of samples of

plastics.

Practice for the verification of the strength of the testing machine.

E 83Practice for verification and classification of system extension.

2
E 132 is the testing method to keep the temperature rate within range.
environment.

E 691 is the practice for conducting an interlaboratory study for

determine the accuracy of a testing method.

2.2 ISO Standard

ISO 527-1 Determination of Tensile Properties.

3. Terminology

3.1 Definitions of terms applicable to this test method appear in

Terminology D 883 and A2 of the annex.

4. Meaning and Use

4.1 This test method is designed to produce tensile goods, given

for the control and specification of plastic materials. This data also
are useful for qualitative characterization and research and development. For
for many materials, there may be a specification that requires the use of this
testing method, but with some procedural modifications that
they prevail when adhering to the specification. Therefore, it is advisable
consult the material specification before using this testing method.

4.2 Tensile properties may vary according to the preparation of

samples and with the speed and the testing environment. As a result, where
accurate comparative results are desired, these factors must be
carefully controlled.

4.2.1It is noted that a material cannot be tested without also testing the
method of preparing this material. Therefore, when the comparative tests
Materials, in themselves, are desired, the greatest care must be taken to
ensure that all samples are prepared exactly the same
way, unless the test is to include the effects of preparation of
sample. Similarly, for the purposes of arbitration or comparisons within a
given set of samples, care must be taken to ensure the
maximum degree of uniformity in the details of preparation, treatment and
handling.

4.3 Tensile properties can provide useful data for fine plastics
engineering. However, due to the high degree of sensitivity displayed by
many plastics the effort rate and environmental conditions, the data
obtained by this test method cannot be considered valid for
applications that involve load time scales or in very environments
different from the present testing method. In case of divergence,
no reliable estimate of the utility limit can be made for most.

3
two plastics. This sensitivity to effort and environmental impact demands
tested more than one broad loading time scale (including impact and
fluency) and range of environmental conditions are tensile properties
sufficient for engineering project purposes.

NOTE 5 - Since the existence of a true elastic limit in plastic

(like many other organic materials and, in many metals), it is debatable the
regularity of the use of the term "plastic module" in its cited,
A general accepted definition to describe the 'stiffness' or 'rigidity' of a plastic is
has been seriously questioned. The exact tension-characteristic in plastic
materials are highly dependent on factors such as the application rate of
stress, temperature, previous history of specimen, etc, however, tension-
curves for the plastics, determined as described in this method of
The test almost always shows a linear region at low voltages, and a line
tangent; this part of the curve allows for the calculation of a modulus of elasticity
of generally defined type. This constant is useful if your factors of nature
arbitrary and the dependence on time, temperature, and similar factors are carried out.

5. Device
5.1 Test Machine - A constant rate cross-movement testing machine
type and understanding, essentially, the following:

5.1.1 Fixed or essentially stationary member, member carrying a

open.

5.1.2Mobile member – a mobile member carrying a second wrist.

5.1.3 Handles for carrying out the sample between the fixed and movable member
The test member machine can be fixed or of the self-aligning type.

5.1.3.1 fixed apertures are firmly connected to the fixed and movable members of the
testing machine. When this type of Grip is used, extreme care must be taken.
to be taken to ensure that o test to be specified. A
sample is inserted and fixed so that the longitudinal axis of the test model
coincides with the direction of the traction through the central line of the assembly
adhesion.

5.1.3.2 Auto-alignment of fasteners is attached to the fixed and movable members.

from the testing machine in such a way that they will move freely in
alignment, as soon as any load is applied so that the axis
the longitudinal sample will match the direction of the applied tension through the
center line to the assembly adhesion. The specimens must be
perfectly aligned, possible with the traction direction so that the
rotational movement that can cause skidding will occur in the tight turns, there is
a limit for the amount of misalignment auto-alignment will be
to arrange.

4
5.1.3.3A the sample must be taken in such a way that the skidding in
grips are prevented as much as possible. Grip on surfaces that
are deeply marked or notched with a pattern similar to the
from a rough file single cut, serrations about 2.4 mm (0.09
inches) away and about 1.6 mm (0.06 inches) deep, have
considered satisfactory for most thermoplastics. Finer serrations
were found to be more satisfactory for more plastics, such as the
thermoset materials. The serrations must be kept clean and sharp.
Breaking in the grips can occur sometimes, even when the specimen
deep grooves, or worn surfaces are used, others
techniques should be used in these cases. Other techniques that have been helpful
In particular with beardless squeezes, they are abrasive that part of the surface of the
model that will be in the claws, and interposing fine pieces of abrasive cloth,
sandpaper or plastic, or fabric, commonly referred to as hospital cover, among
the sample and the surface adhesion. Abrasive no. 80 on both sides on paper
it was effectively found in many cases.
An open mesh fabric, in which the threads are coated with abrasives,
they were also effective. Reducing the cross-sectional area of the sample
can also be effective. The use of special types of grips is sometimes,
necessary to eliminate skidding and breakage in the grips.

5.1.4 Drive Mechanism - a disk diffusion mechanism to the moving member

uniform, the speed controlled in relation to the stationary member, with
this speed to be regulated, as specified in Section 8.

5.1.5 Load Indicator - An appropriate loading mechanism, indicating capacity

to show the total traction load carried out by the model test when conducted
by the pressures. This mechanism must essentially be free of inertia in the rate
specified in the test and must indicate the load with a precision of ±1% of the value
indicated, or rather. The precision of the testing machine must be verified in
compliance with E4 practices.

NOTE 6- Experience has shown that many testing machines already in use
are unable to maintain accuracy, while the periods between Practices of
recommended controls in E4. Thus, it is recommended that each machine be
studied individually and checked as many times as deemed necessary.
It will often be necessary to perform this function daily.

5.1.6 The fixed member, movable member, the mechanism of the unit, and pliers must
to be built with appropriate materials and in proportions such that deformation
the total longitudinal elasticity of the system formed by these parts does not exceed 1%
from the total longitudinal tension between the two marks measured in the sample test, in
at any moment during the rehearsal and, at any load up to capacity
machine nominal.

5
5.1.7 Cross Indicator Extension - extension of an adequate indicating
mechanism capable of showing the amount of change in the separation of the grips,
that is, crosshead movement. This mechanism must be essentially free from
inertia delay at the expected testing rate and should indicate the movement of the crosshead with
an accuracy of ±10% of the indicated value.

5.2 Indicator Extension (extensometer) A suitable instrument must be

used to determine the distance between two designated points along the length
sample size as the model is extended. For referee purposes, the
the extensometer should be defined at the full measured length of the model,
as shown in the figure. J. It is desirable, but not essential, that this instrument
automatically record this distance, or any change to it, as a
function of the load on the sample or the time elapsed since the beginning of the test,
or both. If only the last one is obtained, the loading time data also
must be taken. This instrument must be essentially free of inertia with
the specified test speed. Strain gauges will be classified and their
Calibration verified periodically in accordance with practice E83.

5.2.1 Elasticity module - Measurements - For the module of - measurements of

elasticity, a strain gauge with a maximum stress error of 0.0002 mm / mm
(pol / pol.) that records must be used automatically and continuously.
A extensometer classified by practice E S3 that meets the requirements of
a B-2 classification within the range of use of modulus measures satisfies
this requirement.

5.2.2 Low Extension Measurements, for elongation - in performance and

measures of extension reduction [nominally 20 'Ji, or less). the extensometer
same above. attenuated to 20 'lc extension, they can be used. In any
In this case, the extensometer system must meet at least class C (Practice E 83)
requirements, which include a fixed tension error of 0.001 strain or 10% of the tension
indicated, which is larger.

5.2.3 The High Extension Measurements - To make measurements in stretching

greater than 20%, measurement techniques with an error no greater than ±10% of the value
measured are acceptable.

5.3 Micrometers - Device for measuring the width and thickness of the test sample
must comply with the requirements of test method D 5947.

Sample test

6.1 Sheets, Plates and Molded Plastics.

6.1.1 Rigid and Semi-rigid Plastics - The sample test must be in

compliance with the dimensions indicated in the figure. I. The type I model is the model
preferred and should be used when sufficient material with a thickness of 7
mm (0.28 inches) or less is available. The type II model can be used.
when a material does not break in the narrow section with its preferred model
Type I model. The Type V specimen should be used when only material
limited com a thickness of 4 mm (0,16 inches) or

6
less available for evaluation, or when a large number of samples
they must be exposed in a limited space (thermal and stability testing of
environment, etc.). Type IV model should be used when necessary
comparisons direct between
materials in cases of different stiffness (that is, non-rigid and semi-rigid). The model
type III should be used for all materials with a thickness greater than
7 mm (0.28 inches), but not exceeding 14 mm (0.55 inches).

6.1.2 Non-rigid plastics - The sample must comply with the

dimensions shown in Fig 1. The Type IV model will be used to test plastics
not rigid with a thickness of 4 mm (0.16 inches) or less. The model of
Type III must be used for all materials with a thickness greater than 7
mm (0.28 inches), but no more than 14 mm (0.55 inches).

6.1.3 Reinforced Composites - The sample for reinforced composites, including

highly orthotropic laminates.

6.1.4 Preparation - The test specimens must be prepared through operations of

machining, cutting, from sheet materials, plates, slabs, or similar forms.
Materials thicker than 14 mol (0.55 in) must be machined to 14 mm (0.55
inches) for use as Model Type III. The samples can also be
prepared by molding the material to be tested.

NOTE 7 - The test results showed that for some materials such as the
glass cloth SMC, BMC laminated from other types of samples must be
considered to ensure the break within the measured length of the sample,
as mandated by 7.3.

NOTE 8 When preparing samples of certain laminated composites such as fabric or a

glass cloth, care must be taken when cutting the samples in parallel with the
reinforcement. The reinforcement will be significantly weakened by the cut in bias,
resulting in lower laminated properties, unless sample tests in
a different parallel direction with reinforcement constitutes a variable that is being
studied.

NOTE 9 injection molded samples can have different

tensile properties of samples prepared by machining or cutting by
due to the induced orientation. This effect may be more pronounced in the samples.
with narrow section.

6.2 Rigid Tubes - The sample for rigid tubes must be as shown in
Figure 2. The length L will be as shown in the table in Fig. 2. A
the groove should be worked around the outside of the sample in the center of its
length so that the wall section after machining must be 60%
the thickness of the original nominal wall. This groove consists of a section
length of 57.2 millimeters (2.25 inches), with a radius of 76 mm
(3 inches) at each end connecting to the outer diameter. Caps
of steel or brass have diameters that allow them to fit inside the tube and
has a length equal to the total length of the mandible, plus 25 mm (1
he must place at the ends of the samples to avoid

7
crushing. They can be conveniently located in the tube of
separation and supporting-011 a metal rod with thread.

6.3 Rigid rods - The sample for the rigid rods must be as shown in the
Figure 3. The length, L, must be as shown in the table in fig. 3. A groove
it must be worked around the model of the center of its length so that
that the diameter of the parcel machine will be 60% of the original nominal diameter. This
the groove consists of a straight section of 57.2 millimeters (2.25 inches), in
length, with a radius of 76 mm (3 inches) at each end that the
one or external diameter.

6.4 All surfaces of the sample must be free of visible defects, scratches.
or imperfections. Marks left by rough machining, operations must be
carefully removed with a fine file or abrasive, and the surfaces
deposited, then to be smoothed with sandpaper (No. 00 or finer). The strokes of
The finishing sandpaper should be done in a direction parallel to the long axis of the test.
specimen. All flashes must be removed from a molded specimen,
taking great care not to disturb the molded surfaces. In machining
of a specimen, which reduces exceeding the dimensional tolerances must be
scrupulously avoided. Care must be taken to avoid others
common machining errors.

If it is necessary to place gauge marks on the sample, this must be done with
wax or ink, which does not affect the material is being tested.
Gage marks should not be scratched, pierced, or printed on the model.

6.6 When the test materials that are suspected of anisotropy, duplicate
test sample sets must be prepared, which have their
long axes, respectively parallel and normal, in the suspected direction of
anisotropy.

7. Number of test specimens

Test at least five specimens for each sample in the case of

isotropic materials.

Test ten samples, five normal and five parallel with the axis
principal anisotropy, for each sample in the case of anisotropic materials.
7.3 specimens to discard that break due to some defect, or that break externally.
from the narrow cross-sectional test section and conduct new tests, unless such
Failures constitute a variable to be studied.

NOTE IO-tests First, all transparent specimens must be

inspected in a polarimeter. Those that show atypical or
tension patterns must be rejected unless the effects
these residual strains constitute a variable to be studied.

8. Test speed

8
8.1 Testing speed should be the relative speed of movement of
tightness or templates TESL during the test. The movement rate the tightness
conducted or accessory when the testing machine is being operated
idle can be used, if it can be demonstrated that the resulting speed
of the test is within the permitted variation limits.

8.2 Choose the speed of the table tests. 1. Determine this speed.
chosen tests by the specification of the material being tested, or by
agreement between the interested parties. When the speed is not specified,
use the lowest speed for the geometry of the model to be used, which
Give the rupture in half an hour to test for 5 minutes. Module of 8.3
determinations can be made at the speed selected for the others
tensile properties when the recorder response and resolution are
adequate.

9. Conditioning

9.1 conditioned Condition as samples at 23 +/- 2 °C (73.4 +/- 3.6 °F) and 50
+ / - 5% relative humidity for no less than 40 hours before the test,
compliance with procedure A or Practice D 618 unless otherwise indicated
contrary to the contract or the specification of the relevant ASTM material.
Pre-test conditional reference, to resolve discrepancies, the following apply
tolerances or + / - 1 ° C (1.8 ° F) and + / - 2% relative humidity. Conditions of
test at 23 +/- 2 °C (73.4 +/- 3.6 °F) and 50 +/- 5%
relative humidity, unless otherwise specified by contract or
relevant material specification ASTM. reference test conditions, for
to resolve the disagreements, tolerances of + / - 1 ° C (1.8 ° F) and + / - apply
2% relative humidity.

10. Procedure

10.1 measure the width and thickness of each sample to the nearest 0.025
millimeters (0.001 inches) using the criterion to apply methods D 5947.

10.1.1 measure the width and thickness of the specimens at the center of each
specimen and within 5 mm of each end of the gage length.

10.1.2 Injected sample dimensions can be determined through the

real measurement of only one specimen of each sample, when it has been
demonstrated that the variation of sample-model of width and thickness is
younger than me c.

10.1.3 Take the width of specimens produced by a type 1 V as the

distance between the cutting edges of the die at the narrow part.

10.1.4 Measure the diameter of the rod samples, and the diameters, inside and outside of
tube specimens, with an approximation of 0.025 millimeters (0.001
inches) with a minimum of two points 90 º part take the measurements to

9
long of the groove of specimens so built. Use plugs in the tests to
tube samples.

1 0.2 Place the sample in the testing machine's grips, taking care to
align the longitudinal axis of the sample and the clamps with an imaginary line
that connects the grip mounting points for the machine. The distance between the
extremities of the gripping surfaces, when using flat specimens, is
as indicated in the figure. I. In tube and rod specimens, the location of
confrontation. Tighten the clamps evenly and firmly as needed
to prevent the samples from sliding during the test, but not to the point
where the model would be crushed.

10.3 Fix the extension indicator. When the module is being determined,
A class B-2 or higher extensometer is required (see 5 0.2!).

NOTE 11 - The modulus of materials is determined by the slope of the linear portion.
of the stress-strain curve. For most plastics, the linear part is
very small. O runs very quickly, e it must be recorded
automatically.
The change in maxillary separation should never be used for calculation.
module or stretching.

10.4 Define the speed of the tests at the appropriate rate as provided in
Section 8, and start the machine.

10.5 Define the load curve extension of the model.

10.6 Define the load and extension at the yield point (if it exists) and of
load and extension at the moment of rupture.

NOTE 12 - If you wish to measure the properties of modulus and failure (Yield or
break, or both), it may be necessary, in the case of high extensible material, to
execution of two independent tests. The high magnification extensometer
normally used to determine the properties up to the point of
yield may not be suitable for tests involving extensibility. If high
to be able to remain connected to the model. the extensometer can be permanent
damaged. A wide range incremental extensometer or hand rule
Technique may be necessary when these materials are brought to rupture.

11. Calculation

II. The compensation will be made in accordance with Annex I. Unless it can be
demonstrate that the curved finger region is not due to the adoption of slack.
sample seat, or another artifact, but it is an authentic material the answer.

11.2 Tensile Strength - Calculate the tensile strength by dividing the

maximum load, in newtons (pounds-force), by the average original cross-sectional area
in the length of the sample gauge segment, in square meters (cm²).
To manifest the result in pascal (pounds-force per square inch) and
report for three significant values such as resistance to production or

10
rupture resistance, as the term is applicable. When a yield
nominal or load break below maximum is present and applicable, it can
it is also desirable to calculate, in a similar way, the tension
corresponding to the break in production or tensile stress at break and report
to three significant figures (See note 2.8).

11.3 Stretching valid values arch and arch reported in cases where the
Uniformity of deformation in the gauge model length is present.
Stretching values arc quantitatively relevant and suitable for the
engineering project. When non-uniform deformation (like caresses)
In the gauge model, nominal length values of tension are
reported. nominal tension The values are of only qualitative usefulness.

11.3.1 percent percent of the elongation The elongation is the change in

length gage in relation to the original model gage length, expressed
in percentage. percentage elongation is calculated using the device
described in point 5.2.

11.3.1.1 Elongation percentage in Yield - Calculate the elongation percentage to

production through reading the extension (gauge length change) in
yield point. Divide this extension of the original gauge length and
multiply by 100.

11.3.1.2 percentage of elongation at rupture Calculate the percentage

stretching in the rupture with reading the extension (change in length)
gage) at the breaking point of the sample. It divides the length extent
Take the original and multiply by 100.

11.3.2 nominal tension Simin-nominal is the change in grip separation in

the original adhesion relationship expresses one percent. nominal tension
is calculated using the device described in 517.

11.3.2.1 nominal rupture voltage - Calculate the nominal rupture voltage value
with the reading the extension (variation of adherence separation) at the point of
break. Divide this extension by the original grip separation and multiply by
100.

11.4 Elasticity Module - Calculate the elasticity module through the

lengthening of the initial linear portion of the load-extension curve and dividing it
difference in stress corresponding to any segment of the section on this line
network corresponding to the voltage difference. All the values of the module of
elasticity will be calculated using the original mean cross-sectional area in
length gauge segment of the model in calculations. The result must be
expressed in pascal (pounds-force per square inch) and reported for three
significant figures

11.5 Secant modulus - In a designated strain, this must be calculated

dividing the corresponding (nominal) stress by the designated tension.
Elastic modulus values are preferable and should be calculated whenever
possible. However, for materials where proportionality is not evident, the

11
the secant value must be calculated. Draw the tangent, as indicated in the
A 1.3 and fig. A 1.2, and mark the tension designated from the point where the
yield at the tangent line crosses zero stress. The stress to be used in
Next, the calculation is determined by the division of the load-extension average curve.
yes area original of section transversal from sample.

11.6 for each test series. calculate the arithmetic mean of all values
obtained and report it as the "average" value for the private property in
question.

11.7 Calculate the standard deviation (estimated) of the following way and report it to
two
significant figures:

s= estimated standard deviation.

X = value of the individual observation.
n = number of observations and
X = arithmetic mean of the set of observations.

11.8 See Annex A1 for information on finger compensation

foot.

12.Report

12.1 report the following information:

12.1.1 The complete identification of the tested materials, including type, source, the
manufacturer code numbers, a main form dimensions,
backgrounds, etc.

12.1.2 Method for preparing test specimens.

13. Precision and (partial or bias, I don't know which is the correct translation)

13.1 Precision - is based on a round-robin test conducted in 1984,

involving five materials tested by eight laboratories that use the model of
type I, all with a nominal value of 0.125 inch thickness. The test result
It was based on five individual determinations. Each laboratory obtained two.
test results for each material.

13.1.1 are based on a round-robin test conducted by the subcommittee of

polyolefins, in 1988, involving eight polyethylene materials tested in ten
laboratories. For each
material, all samples were molded into a single source, but the samples
were prepared in the laboratories that tested them. The test result was the average
individual of five determinations. Each laboratory obtained three test results
for each material. The data from some laboratories could not be used
for various reasons.

12
13.1.2 based on a repeatability study involving a single laboratory.
The two materials used were various types of polypropylene. Measurements were
carried out by a single technician in a single day. The result of the test is a
individual determination. The test was performed with two Type B-1 extensometers
for transverse and axial measurement in a speed test of 5 mm/min.

13.1.3 for the indicated materials, and for results derived from tests of
five samples:

13.1.3.1 The standard deviation in the laboratory of the average; Ir = 2.83 Sr. (See
13.1.3.3 for the application of the Ir).

13.1.3.2 SR is the standard deviation between the laboratory of the average; IR = 2.83 SR (see
13.1.3.4 for the application of IR).

13.1.3.3 Repeatability - In the comparison between two test results for the
same material, obtained by the same operator, using the same equipment
on the same day, the test results must be judged not equivalent if they
They differ because of the value Ir for this material and condition.

3.1.3.4 Reproducibility Comparing results of two tests of the same

material, obtained by different operators and using different equipment
on different days, the test results should be judged as not equivalent
if they differ by more than the value of the IR for this material and condition. (This if
applies between different laboratories or between different equipment in the same one
laboratory).

13.1.3.5 Any decision of agreement com 13.1.3.3 e

13.1.3.4 will have approximately 95% (0.95) probability of being correct.

Other formulations may yield slightly different results.

For more information about the methodology used in this section, see
Practices E 691.

13.1.3.8 The accuracy of this testing method is highly dependent on the

sample preparation uniformity, the standard practices for which are
addressed in other documents.

13.2 Partiality - There are unrecognized norms on which to base a

estimate of partiality for this end of not method.

14.Keywords

14.1 modulus of elasticity: elongation percent; plastics; properties of

tension: tensile resistance.

13
A1.1com Material Region hooken

A1.1 In a typical stress - Tension curve, there is a region of the toe,

AC, which does not represent a property of the material. It is an artifact caused
for an examination above the break and the alignment or positions of the sample. For
obtain the correct values of the parameters, such as module, voltage and
elastic displacement, this artifact must be compensated to provide the
zero point corrected on the tension or extension axis.

In the case of the material exhibiting a Hookean region (linear)

behavior (Fig. A1.1), a continuation of the linear (CD) of the region is
built through the zero - stress axis. This intersection (B) is the correct zero -
tension point that all extensions or strains must be measured,
including the production of offset (BE), if applicable. The modulus of elasticity
can be determined by dividing the stress at any point along the
line CD (or its extension) by the strain at the same point (measurement of point B,
defined as zero voltage.

In the case of a material that does not exhibit any linear region (Fig.
A1.2), the same type of correction finger from zero - tension point can be made
for the construction of a tangent to the maximum slope at the inflection point (H
This is extended to cross the tension axis at point B, the point of
zero tension corrected -. Using as point B 'zero tension, the stress in
Any point (G') on the curve can be divided by the stress at that point.
to obtain a dry elasticity modulus (slope B'G of the line). For the
materials with no linear region, any attempt to use tangent by
inflection point, as a basis for determining a compensation point
The yield of my result is unacceptable error.

A2. The definitions of the terms and symbols related to the tests
of plastic tension

A2. An elastic limit - the greatest stress that a material can withstand,
without any residual permanent tension after complete release of the
stress. It is expressed in force per unit area, usually in megapascals.
(pounds per square inch).

Note A2.1 - Measures of proportionality limit values and limit of

Elasticity varies greatly with the final sensitivity of the equipment.
test, the eccentricity of the loading, the scale at which the stress - diagram
tension is generated, and other factors. Consequently, these values are
usually replaced by efficiency.

A2.2 Stretching - the increase in length produced in length of

sample caliber under a tensile load. It is expressed in units of
length, usually millimeters (inches). (Also known as
extension).

14
Note A2.2 Stretching and deformation values are valid only in the
cases in which exemplary behavior uniformity, within the
gauge length is present. In the case of materials that exhibit touches
phenomena, such values are only qualitative in utility after the realization
from the point of yield. This is due to the inability to ensure that caresses
will cover the entire stretch between the brands before gauge model failure.

A2.3 length gauge - the original length of the part of the model on
what the strain or change in length is determined.

FIG. A2.1 Flow resistance

A2.4 elasticity module the relationship of stress (nominal) to tension
corresponding below the proportional limit of a material.
It is expressed in force per unit area, usually megapascals (Pounds-
force per square inch). (Also known as modulus of
elasticity or Young's modulus.

Note - A2.3 The voltage-relations of many plastics are not compliant 10 Law of
Hooke in the entire elastic range, but they deviate from them evell in the highlight well
below the elastic limit. For these materials, the slope of the tangent to the curve
stress-strain at low tension is generally taken as the modulus of
elasticity. Once the existence of a 'true proportional limit
in plastics is debatable, the property of applying the expression 'modulus of
elasticity "to describe the stiffness or rigidity of a plastic was seriously
questioned. The exact stress-strain characteristics of plastic materials are very
dependent on factors such as the highlighting temperature rate, the history
previous example. etc, however, this value is useful if its nature is arbitrary
The dependence on time, temperature, and other factors is carried out.

A2.5 touches, the localized reduction in the cross-section that can occur in
a material under tensile stress.

A2.6to compensate for the force yield in which the stress of the tension exceeds one
specified value (or offset) an extension of the proportional share
initial of the stress-strain curve. It is expressed in force per unit area,
generally mega pascals (pounds-force per square inch).

Note A 2.4 measurement This is useful for materials whose stress curve is in the range
the yield is of gradual curvature. The production of plywood force can
being the derivative of a stress curve, as follows (Fig.A2.1):
In the tension axis, it was all OM equal to the specified displacement. Draw.
AO tangent to the initial line segment of the tension-curve. Through M
draw a line MN parallel to the oil and locate the intersection of MN
com a curve of tension.
The tension at the intersection point of r is the 'displacement of the force of
production." The specified value outside the displacement must be indicated as
a percentage of the original gauge length, in conjunction with the value
of force. Example: 0.1% compensating the yield = force ... MPa (psi), or
elasticity of 0.1% compensates ... MPa (psi).

15
A2.7 hundred stretching, the stretching of a test sample expressed
as a percentage of the gauge length.

A2.8 percentage of elongation at break and yield:

A2.8.1 percentage of elongation at break, the percentage of elongation

at the moment of breaking the sample.

A2.8.2 percentage stretching in production with the percentage stretch

at the moment the yield point (A2.22) is reached in the test
specimen.

A2.9 percentage of area reduction (nominal): the difference between the area
original transversal measured at the breaking point after the break and after everything
retraction ceased, expressed as a percentage of the original area.

A 2.10 percent reduction in area (true), the difference between the area
original cross section of the sample and the minimum cross-sectional area at the limit gauges
in force at the time of the break, expressed as a percentage of the original area.

A2.11 Poisson's ratio, the absolute value of the transverse stress ratio to
corresponding axial tension resulting in uniformly distributed stress
axial below the material's proportional limit.

A2.12 limit stress proportional to what a material is capable of

sustain, without any deviation of proportionality of stress the tension (law of
Hooke). It is expressed in force per unit area, usually megapascals.
(pounds-force per square inch).

A2.13 rate of variation of the traction load carried out by the

sample per unit of time. It is expressed in force per unit time,
usually newtons (pounds-force) per minute. The initial charging rate
can be calculated from the initial slope of the load versus diagram
time.

A2.14 stress rate, the change in tensile stress per unit of time.
It is expressed as tension or per unit of time, usually meters per
meters (inches per inch) per minute, or percentage stretch per
time unit, usually percent of elongation per minute. The rate
initial deformation can be calculated from the initial inclination of the stress
traction versus time diagram.

NOTA-A2.5The initial effort rate is synonymous with the movement rate

crossbar divided by the initial distance between the crossbars only in one
machine with constant speed of movement and when the crosshead model
there is a uniform original cross-section. not at the neck 'downwards', and
don't slip on the jaws.

16
A2.I5 underline rate (nominal), the change in stress tension (nominal) by
unit of time. It is expressed in force per unit area per unit of
time. generally megapascals (pounds-force per square inch) per
minute. The initial highlighting rate can be calculated from the slope
initial tensile stress (nominal) versus time diagram.

NOTE-A2.6 The initial rate to highlight as determined in this way only has
limited physical significance. It is, however, about describing the average rate in
that the initial (nominal) voltage performed by the model test is applied. It is
affected by the elasticity and flow characteristics of the materials that are
being tested. At the yield point, the underline rate (true) can
continue to have a positive value if the cross-sectional area is decreasing.

A2.16 secant modulus, the relationship between stress (nominal) and strain
correspondent at any specific point about tension stress and
curve. É expressed in force per unit area, generally
megapascals (pounds-force per square inch), and reported with the stress or the
specified tension.

NOTE A2.7, this measure is usually used instead of the module of

elasticity, in the case of materials, whose stress-strain diagram does not
demonstrate the stress proportionality to the tension.

A2.17 strain reason for the elongation of the sample's gauge length, or
be, the change in length per unit of original length. It is
expressed as a dimensionless ratio.

A2.17.1 nominal breaking voltage, the voltage at the moment of breakage in

relation to original adherence separation.

A2.18 tensile strength (nominal) of maximum tensile stress (nominal)

supported by the model during a test tension. When the maximum tension
it occurs at the yield point.

A2.22, should be designated as resistance to productivity. When the tension

maximum occurs in the interval. it must be designated.

Resistance

A2.19 traction (nominal value) a traction load per unit

minimum area of original cross section, at boundary gage, carried out by
test sample at any time. It is expressed in strength per unit of
area, usually megapascals (pounds-force per square inch).

Note-A2.8 The expression of tensile properties in terms of minimum of

the original cross-section is almost universally used in practice. In case
of materials EXHIBITOR high extensibility; or stretching, or

17
both (A2.16) calculated nominal voltage may not be significant beyond
of the yield point (A2.22) due to the reduction in the extensive area of the section
transversal that follows. In some circumstances, it may be convenient
for minimum current tensile properties per unit of cross section.
These expression properties are called true properties.
of traction (that is, the true traction effort, etc.)

A2.20 traction tension-curve a diagram in which values of tensile stresses

are represented as coordinates against the corresponding values of
tensile stress as abscissas
A2.21 true strain (see fig.A2.2) is defined by the following equation
for the Et.

A2.22 yield point of the first point on the stress-strain curve - at which a
tension increase occurs without increase in stress (Fig. A2.2).

NOTE A2.9 - Only materials whose stress-strain curves have a point of

zero decline can be considered as having a yield point.

NOTE A2.IO- Some materials exhibit a break of 'distinct' or

discontinuity in the stress-strain curve in the elastic region. This pause
it is not an illustrative yield, by definition. However, this point can be
useful for material characterization in some cases.

A2.23 elasticity-stress in which a material shows a deviation

specified limitation of proportionality stress. Unless otherwise provided
on the contrary, this effort will be the tension at the yield point and when
expressed in relation to the tensile strength must be designated or resistance to
yield or tensile stress in production as required in A2.18 (Fig.
A2.3). (See offset elasticity.)

A3.1 Scope

A3.1.1 This test method covers the determination of Poisson's ratio obtained from
stress uniaxial only.

A3.1.2 Data obtained by this method are relevant and suitable for use in
engineering project.

The values expressed in SI units are considered as standard.

Values in parentheses are for information only.

A3.2 Referenced Documents

A3.2. I ASTM Standards:

D 618 Practice for Plastics conditioned for the test.

D 883 terminology referring to Plastics.

18
D 5947 testing methods for dimensions of solid plastic samples.

The practice for verification and classification of systems Extensometer

E132 Eo testing method for Poisson Ratio in the Temperature Room.

E 691 Practice for conducting an interlaboratory study to determine precision

of a testing method.

E 1012 practice for verifying the test frame and samples in axial alignment
of tension and compression.

Application of force
ISO Standard A3.2.2:

ISO 527-1 Determination of Tensile Properties

A3.3. Terminology

A3.3.1-Definitions The definitions of the terms apply to this testing method

appear in Terminology D 8x3 and / Annex of this standard.

A3.4 meaning and use

A3.4.1 When uniaxial tensile force is applied to a solid, it is extended.

solid in the direction of the applied force (axial), but also contracts in both
the dimensions perpendicular to the applied force. If the solid is homogeneous and
isotropic, and the material remains elastic under the action of applied force, the
transverse tension has a constant relationship with axial tension. This
constant, called the Poisson ratio, is defined as the negative ratio
transversal relationship (negative) for axial stress under uniaxial stress.

A3.4.2 Poisson is used for the design of structures where all

dimensional changes resulting from the application of force must be considered in
count and in the generalized application of the theory of elasticity for analysis
structural.

NOTE A3.2 - The accuracy of the determination of the Poisson coefficient is

usually limited by the accuracy of the transverse voltage measurements because
the percentage errors in these measurements are generally greater than in the measurement
from axial deformation. Since a relationship is more than absolute quantity
measure, it is only necessary to know precisely in relation to the value of the
calibration factors of the extensometers. In addition, in general, the value of the loads
applied does not need to be known with precision.

A3.5 Devices

19
Refer to 5.1 and 5.3 of this standard for the machine requirements.
testing and micrometers.

A3, 10 1.1.1 The errors that are introduced by a straight line drawing through
the points are reduced through the application of the least squares method
squares.

A3, 10.1.2For materials where there is no stress proportionality of

evident tension determines the relationship of DE / DE 'when of' = 0.002 (with
Based on the range of 0.0005 to the axial tension of 0.0025 millimeter / mm) and after the
compensation of the toe was made.

A3.11 Report

A3.11.1 Report the following information:

A3.11.1.1 identification complete do material tested

including the type, source, manufacturer code numbers, shape,
main dimensions, background, etc

A3.11.1.2 method of preparing test specimens,

A3.11.1.3 Sample type and dimensions

A3.11.1 Conditioning procedure used,

A3.11.1.5 atmospheric conditions in the examination room,

A3.II.l.6 Number of samples tested,

A3.1l.1.7 test speed,

A3.II.l.8 Classification of extensometers used. A description

from the measurement techniques and calculations used,

A3.1l.1.9 Poisson ratio, the mean value, standard deviation, and statement of
existence of proportionality in the voltage range,

Data A3.1l.l.l test code

A3.11.1.11data Review of Test Method D 638. Precision A3.12 and Bias

A3.12.1 Repeatability Precision The standard deviation

It was determined to be the following (see table; A3.l.) An attempt to

develop total precision and the bias statement for the testing method
will be done at a later date. For this reason, the data on accuracy and bias do not
it can be given. As this testing method does not contain a round-robin and
numerical precision based on a declaration of bias should not be used

20
as a referee test method in case of dispute. Anyone who
it should aim to participate in the development of data accuracy and bias
contact Chainnan, Subcommittee D20.10 Mechanical Properties. ASTM
International, 100 Harbor Barr, West Conshohocken. PA 19428.
13.Keywords

axial tension Committee D20

identified the location of selected changes to this standard since the
latest edition (D 638-03) that may affect the use of this standard. (April I, 2008)

21