ASTM D3983-98(2011)
(Test Method)Standard Test Method for Measuring Strength and Shear Modulus of Nonrigid Adhesives by the Thick-Adherend Tensile-Lap Specimen
Standard Test Method for Measuring Strength and Shear Modulus of Nonrigid Adhesives by the Thick-Adherend Tensile-Lap Specimen
SIGNIFICANCE AND USE
This test method is capable of providing shear modulus and shear strength values for adhesives with accuracy suitable for use by design engineers in predicting the characteristics of building assemblies bonded with nonrigid adhesives. Adhesive formulators will also find the method useful during the development of new adhesive systems. In general, the thick adherend lap-shear test is a useful tool in research during studies of both short- and long-term load-deformation properties of adhesives. This thick adherend lap-shear test yields a uniformity of stress distribution approaching that obtained in thin tubular butt joints subjected to torsion, which is considered to be a condition of pure shear.
The user is cautioned that pure shear strength cannot be obtained by this test method, because some tensile and compression stresses and stress concentrations are present in the joint. The estimate of shear strength by this test method will be conservative. If pure shear strength is demanded, then Test Method E229 should be used.
SCOPE
1.1 This test method describes a method of measuring the shear modulus and rupture stress in shear of adhesives in bonded joints. The method employs lap-shear specimens with wood, metal, or composite adherends, with adhesives having shear moduli ranging up to 700 MPa (100 000 psi). This test method is suitable generally for joints in which the ratio of adherend tensile modulus to adhesive shear modulus is greater than 300 to 1. It is not suitable for adhesives that have a high shear modulus in the cured state and that also require elimination of volatile constituents during cure.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.3 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: D3983 − 98 (Reapproved 2011)
Standard Test Method for
Measuring Strength and Shear Modulus of Nonrigid
Adhesives by the Thick-Adherend Tensile-Lap Specimen
This standard is issued under the fixed designation D3983; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E104Practice for Maintaining Constant Relative Humidity
by Means of Aqueous Solutions
1.1 This test method describes a method of measuring the
E229Test Method for Shear Strength and Shear Modulus of
shear modulus and rupture stress in shear of adhesives in
Structural Adhesives (Withdrawn 2003)
bonded joints. The method employs lap-shear specimens with
wood, metal, or composite adherends, with adhesives having
3. Terminology
shear moduli ranging up to 700 MPa (100000 psi). This test
3.1 Definitions:
method is suitable generally for joints in which the ratio of
3.1.1 For definitions of terms used in this test method, refer
adherend tensile modulus to adhesive shear modulus is greater
to Terminologies E6 and D907.
than 300 to 1. It is not suitable for adhesives that have a high
3.1.2 initial tangent modulus, n—the slope of the stress-
shear modulus in the cured state and that also require elimina-
strain curve at the origin.
tion of volatile constituents during cure.
3.1.3 nominal stress, n—the stress at a point calculated on
1.2 The values stated in SI units are to be regarded as
the net cross section by simple elastic theory without taking
standard. The values given in parentheses are for information
intoaccounttheeffectonthestressproducedbydiscontinuities
only.
such as holes, grooves, fillets, etc.
1.3 This standard does not purport to address all of the
3.1.4 normal stress, n—the stress component perpendicular
safety concerns, if any, associated with its use. It is the
to a plane on which the forces act, that is, the plane of the
responsibility of the user of this standard to establish appro-
bondline.
priate safety and health practices and determine the applica-
3.1.5 proportional limit, n—the maximum stress that a
bility of regulatory limitations prior to use.
material is capable of sustaining without significant deviation
2. Referenced Documents
from proportionality of stress to strain.
2.1 ASTM Standards:
3.1.6 secant modulus, n—theslopeofthesecantdrawnfrom
D143Test Methods for Small Clear Specimens of Timber
the origin to any specified point on the stress-strain curve.
D905Test Method for Strength Properties of Adhesive
3.1.6.1 Discussion—Modulus is expressed in force per unit
Bonds in Shear by Compression Loading
area (MPa, lb/in. , etc.).
D907Terminology of Adhesives
3.1.7 shear modulus, n—the ratio of shear stress to corre-
D1151Practice for Effect of Moisture and Temperature on
sponding shear strain below the proportional limit. (Compare
Adhesive Bonds
secant modulus.)
D2651GuideforPreparationofMetalSurfacesforAdhesive
3.1.7.1 Discussion—The term shear modulus is generally
Bonding
reserved for materials that exhibit linear elastic behavior over
E6Terminology Relating to Methods of Mechanical Testing
most of their stress-strain diagram. Many adhesives exhibit
E83Practice for Verification and Classification of Exten-
curvilinear or nonelastic behavior, or both, in which case some
someter Systems
other term, such as secant modulus, may be substituted.
1 3.1.8 shear strain, n—thetangentoftheangularchange,due
This test method is under the jurisdiction of ASTM Committee D14 on
Adhesives and is the direct responsibility of Subcommittee D14.70 on Construction to force, between two lines originally perpendicular to each
Adhesives.
other through a point in the body.
Current edition approved Jan. 1, 2011. Published January 2011. Originally
3.1.8.1 Discussion—Shear strain equals adherend slip/
approved in 1981. Last previous edition approved in 2004 as D3983–98(2004).
adhesive layer thickness.
DOI: 10.1520/D3983-98R11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3983 − 98 (2011)
3.1.9 shear strength, n—in an adhesive joint, the maximum
average stress when a force is applied parallel to the joint.
3.1.9.1 Discussion—In most adhesive test methods, the
shearstrengthisactuallythemaximumaveragestressatfailure
ofthespecimen,notnecessarilythetruemaximumstressinthe
material.
3.1.10 shear stress, n—the stress component tangential to
the plane of which the forces act, that is, the plane of the
bondline.
3.1.10.1 Discussion—Nominal shear stress equals load/
bond area.
3.1.11 strain, n—the unit change due to force, in the size or
shape of a body referred to its original size or shape.
3.1.12 stress, n—the intensity at a point in a body of the
internalforcesorcomponentsofforcethatactonagivenplane
through the point.
3.1.13 stress-strain diagram, n—a diagram in which corre-
sponding values of stress and strain are plotted against each
other. Values of stress are usually plotted as ordinates (verti-
NOTE 1—Case load and unload diagrams and modulus line are
cally) and values of strain as abscissas (horizontally).
congruent.
3.2 Definitions of Terms Specific to This Standard:
FIG. 1 Load-Slip Diagram of Linear Elastic Adhesive Under Cyclic
Low-Level Loading
3.2.1 load, n—the force applied to the specimen at any
given time.
3.2.2 load-slip diagram, n—adiagraminwhichcorrespond-
ing values of load and slip are plotted against each other.
Values of load are usually plotted as ordinates (vertically) and
values of slip as abscissas (horizontally).
3.2.2.1 Discussion—Stress-strain behavior is commonly re-
corded in the form of a load-slip diagram. The difference
between the two is simply one of scale. Load is divided by
bond area to obtain stress and slip is divided by adhesive layer
thickness to obtain strain. Examples of various types of
load-slip diagrams and modulus are shown in Figs. 1-3.
3.2.3 rate of strain, n—rate of slip per unit adhesive
thickness.
3.2.4 slip, n—the relative collinear displacement of the
adherends on either side of the adhesive layer in the direction
of the applied load.
3.3 Symbols:
3.3.1 c =half the overlap length= L/2, mm or in.
3.3.2 Ĝ =estimate of shear modulus of adhesive, MPa or
NOTE 1—The modulus is represented by the secant modulus line at
psi.
some load P less than the load to cause failure.
3.3.3 G =shear modulus of adhesive, MPa or psi.
FIG. 2 Load-Slip Diagram of Nonlinear Adhesive Under Cyclic
3.3.4 E =tensile modulus of adherend, MPa or psi.
Low-Level Loading Showing Both Elastic and Viscoelastic
Recovering Diagrams
3.3.5 t =thickness of adherend, mm or in.
3.3.6 η =thickness of adhesive, mm or in.
3.3.7 P =failure load for the bond, N or lbf.
max
4. Summary of Test Method
3.3.8 L =overlap length, mm or in.
4.1 Lap-shear specimens are prepared with the adhesive in
2 2
3.3.9 A =bond area, mm or in. .
questionusingselectedadherends.Theload-deformationprop-
3.3.10 δ =adherend slip at load equivalent to 0.1 P ,mm
max erties of the specimens are measured under specific recom-
or in.
mended conditions to yield a “first estimate” of adhesive shear
3.3.11 τ¯ =maximum nominal shear stress sustained by modulus.Thisestimateisusedtodeterminetheoptimizedjoint
max
the bond, MPa or psi. geometry for best attainable uniformity of stress distribution in
D3983 − 98 (2011)
thintubularbuttjointssubjectedtotorsion,whichisconsidered
to be a condition of pure shear.
5.2 The user is cautioned that pure shear strength cannot be
obtained by this test method, because some tensile and com-
pression stresses and stress concentrations are present in the
joint.Theestimateofshearstrengthbythistestmethodwillbe
conservative. If pure shear strength is demanded, then Test
Method E229 should be used.
6. Equipment
6.1 Test Machine—A tension test machine with electronic
load cell capacities of 0 to 100 and 0 to 1000 kg (0 to 200 and
0 to 2000 lb) is satisfactory for this test method. The machine
should have a loading rate capability of 0 to 200 kg/min (0 to
400lb/min)oracrossheadmovementrateof0to1mm/min(0
to0.040in./min).Closed-loopcontrolofloadlevelandloading
rate, or crosshead position and movement rate, is desirable to
facilitate testing under controlled cyclic loading conditions. A
working space approximately 450 by 450 mm (18 by 18 in.) is
NOTE 1—The modulus may be represented by the initial tangent, the
desirable to accommodate the specimen grips and the installa-
secant drawn to the ultimate load, or the secant drawn to some interme-
tion of a chamber for environmental control. In-line tension
diate load.
grips, shown in Fig. 4, are used for transmitting the load to the
FIG. 3 Load-Slip Diagram of Adhesive Loaded to Failure
specimen.
6.2 Slip Gage and Signal Conditioner:
the joint. A second set of specimens is prepared having the
6.2.1 The shear strain in adhesive layers is usually small.
optimized joint geometry. The final values for load-
Thin layers of relatively rigid adhesives (greater than 50 MPa
deformation properties are then measured under a variety of
(7000 psi)) require anASTM ClassAextensometer. Class B-1
controlled environmental and experimental conditions.
or B-2 extensometers suffice for thicker layers and more
flexible adhesives. Extensometer classes are described in
4.2 The test method is based upon the theoretical analysis
Practice E83.
by Goland and Reissner relating stress concentrations (that is,
6.2.2 Amechanical-electrical transducer, the linear variable
nonuniformity) in single-lap joints to the geometry of the joint
differential transformer (LVDT), is well suited for these tests.
and the mechanical properties of the materials involved. The
The LVDT with suitable signal conditioning will satisfy the
controlling factor in the Goland and Reissner equations is a
requirementsofClassBandAextensometers.Theyarerugged
composite of essentially three ratios which can be manipulated
enough to remain fastened to the specimen through failure if
to improve the stress uniformity in the joint, and thereby
the gage is properly designed.
control the accuracy of measurement. Stress uniformity is
6.2.2.1 The LVDT should have a linear output over a
improved by (1) increasing the adherend tensile modulus in
displacement range of 62.5 mm (60.10 in.) to accommodate
relation to the shear modulus of the adhesive, and by (2)
adhesive layers varying in shear modulus and thickness.
increasing adherend and adhesive thickness while minimizing
6.2.2.2 The LVDT transducers with signal conditioner
overlaplength.Becauseoftheserelationships,thepracticewas
should provide several ranges of displacement resolution—
developed to use high-modulus adherends in thick cross
between 0.0005 and 0.5 mm/cm (5×10 and 0.05 in./m) of
sections.
chart paper.
6.2.3 TheslipgageshallemploytwoLVDTsasdescribedin
5. Significance and Use
6.2.2, positioned in such a manner as to measure and compen-
5.1 This test method is capable of providing shear modulus
sate for rotation of the adherends as well as slip.
and shear strength values for adhesives with accuracy suitable
6.2.4 A gage design that has been found to compensate
for use by design engineers in predicting the characteristics of
satisfactorily for adherend rotation is shown in Fig. 5, Fig.
building assemblies bonded with nonrigid adhesives.Adhesive
A1.1, and Fig. A1.2. The gage consists of three components:
formulators will also find the method useful during the
thegageitselfonwhichtwoLVDTsaremounted,thefollower,
development of new adhesive systems. In general, the thick
and a gage block. The gage and follower attach to opposing
adherend lap-shear test is a useful tool in research during
adherends by clamping knife edges. One knife edge on each
studies of both short- and long-term load-deformation proper-
component may be advanced or retracted by a captive screw.
ties of adhesives. This thick adherend lap-shear test yields a
The gage block is placed between the gage and follower to
uniformity of stress distribution approaching that obtained in
align the knife edges. The gage is clamped to the stationary or
downward moving adherend and the follower to the upward
moving adherend, so the LVDT core moves out of the LVDT
Goland, M., and Reissner, E., “The Stresses in Cemented Joints,” Journal of
Applied Mechanics, November 1944, pp. A17–A27. during loading. This prevents damage to the LVDT upon
D3983 − 98 (2011)
FIG. 4 Incline Tension Grips with Specimen Bolted in Place Ready for Testing
FIG. 5 Dual Transducer Slip Gage Mounted on a Thick Adherend Lap Specimen
failure of the specimen. The follower is equipped with a 6.4.2 The combined test chamber and conditioning unit
knurled adjustment screw for each LVDT. These screws are shouldbecapableofmaintainingaconstanttemperaturewithin
used to null mechanically and electrically each LVDT prior to thelimitsfrom23to71 61°C(80to160 62°F),andconstant
testing. relativehumiditywithinthelimitsof44to98 62%atagiven
6.2.5 The slip gage shall be equipped with a switching and
temperature.
signal-conditioning device to permit recording the signal from
6.4.3 A suitable test chamber is described in Annex A2.
each LVDT individually or the sum of the signals.
6.2.6 The LVDTs and slip gage components should be
7. Materials
fabricated of corrosion-resistant materials.
7.1 Adherend:
6.3 X-Y Recorder—A general-purpose X-Y recorder with
7.1.1 Wood—Hard maple (Acer saccharum or Acer nigrum)
inputs compatible with the outputs of the load cell and slip
with a minimum specific gravity of 0.60 is the standard wood
gage is required. The load is connected to the recorder of the
adherend for this test method. Other dense species with
Y-axis and the LVDTs to the X-axis. The recorder should have
comparable modulus of elasticity such as yellow birch, Doug-
several precalibrated input ranges and a preamplifier to scale
las fir, western hemlock, or southern pine may be used. The
the transducer signals conveniently. The required ranges will
lumber shall be of straight grain and free of defects, including
dependuponthevoltageoutputoftheloadcellsandtheLVDT
knots, birdseye, short grain, decay, and any unusual discolor-
transducers and their signal c
...
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