ASTM D3433-99(2020)
(Test Method)Standard Test Method for Fracture Strength in Cleavage of Adhesives in Bonded Metal Joints
Standard Test Method for Fracture Strength in Cleavage of Adhesives in Bonded Metal Joints
SIGNIFICANCE AND USE
Note 2: Crack growth in adhesive bond specimens can proceed in two ways: (1) by a slow-stable extension where the crack velocity is dictated by the crosshead rate or (2) by a run-arrest extension where the stationary crack abruptly jumps ahead outrunning the crosshead-predicted rate. The first type of crack extension is denoted flat; the second type peaked because of the appearance of the autographic record. The flat behavior is characteristic of adhesives or test temperatures, or both, for these adhesives where there is no difference between initiation, G1c, and arrest, G1a. For example, the rubber modified film adhesives tested above −17.8°C (0°F) all exhibit flat autographic records. Peaked curves are exhibited for all modified materials tested below −73°C (−100°F) and in general for unmodified epoxies.
It should be noted that both peaked and flat behaviors are determined from a crack-length-independent specimen. For other specimens or structures where G increases with a at constant load the onset of crack growth would result in rapid complete fracturing whatever the adhesive characteristics.
5.1 The property G1c (and G1a if relevant) determined by this test method characterizes the resistance of a material to slow-stable or run-arrest fracturing in a neutral environment in the presence of a sharp crack under severe tensile constraint, such that the state of stress near the crack front approaches tritensile plane strain, and the crack-tip plastic region is small compared with the crack size and specimen dimensions in the constraint direction. It has not been proven that tough adhesive systems fully meet this criteria. Therefore, data developed using equations based on this assumption may not represent plane-strain fracture values. Comparison of fracture toughness between adhesive systems widely different in brittleness or toughness should take this into consideration. In general, systems of similar type toughness (6, 7, 8, 9, 10) can be compared as can t...
SCOPE
1.1 This test method (1, 2, 3, 4, 5)2 covers the determination of fracture strength in cleavage of adhesives when tested on standard specimens and under specified conditions of preparation and testing (Note 1).
1.2 This test method is useful in that it can be used to develop design parameters for bonded assemblies.
Note 1: While this test method is intended for use in metal-to-metal applications it may be used for measuring fracture properties of adhesives using plastic adherends, provided consideration is given to the thickness and rigidity of the plastic adherends.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3433 − 99 (Reapproved 2020)
Standard Test Method for
Fracture Strength in Cleavage of Adhesives in Bonded Metal
Joints
This standard is issued under the fixed designation D3433; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope A167 Specification for Stainless and Heat-Resisting
2 Chromium-Nickel Steel Plate, Sheet, and Strip (With-
1.1 Thistestmethod (1, 2, 3, 4, 5) coversthedetermination
drawn 2014)
of fracture strength in cleavage of adhesives when tested on
A366/A366M Specification for Commercial Steel (CS)
standard specimens and under specified conditions of prepara-
Sheet, Carbon, (0.15 Maximum Percent) Cold-Rolled
tion and testing (Note 1).
(Withdrawn 2000)
1.2 This test method is useful in that it can be used to
B36/B36MSpecification for Brass Plate, Sheet, Strip, And
develop design parameters for bonded assemblies.
Rolled Bar
B152/B152MSpecification for Copper Sheet, Strip, Plate,
NOTE 1—While this test method is intended for use in metal-to-metal
applications it may be used for measuring fracture properties of adhesives and Rolled Bar
using plastic adherends, provided consideration is given to the thickness
B209 Specification for Aluminum and Aluminum-Alloy
and rigidity of the plastic adherends.
Sheet and Plate
1.3 The values stated in SI units are to be regarded as the
B265Specification for Titanium and Titanium Alloy Strip,
standard. The values given in parentheses are for information
Sheet, and Plate
only.
D907Terminology of Adhesives
E4Practices for Force Verification of Testing Machines
1.4 This standard does not purport to address all of the
E399Test Method for Linear-Elastic Plane-Strain Fracture
safety concerns, if any, associated with its use. It is the
Toughness K of Metallic Materials
responsibility of the user of this standard to establish appro- Ic
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use.
3.1 Definitions: Many of the terms used in this test method
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard- are defined in Terminology D907.
3.2 Definitions of Terms Specific to This Standard:
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.2.1 crack-extension force, G—the system isolated (fixed
load-displacement) loss of stress field energy for an infinitesi-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. mal increase, d A, of separational area. In equation form,
GdA52dU (1)
T
2. Referenced Documents
where U =total elastic energy in the system (component or
T
2.1 ASTM Standards:
test specimen). In the test specimens of this method, the crack
front is nearly straight through the specimen thickness, B,so
This test method is under the jurisdiction of ASTM Committee D14 on
that dA=B da, where da is an infinitesimal forward motion of
Adhesives and is the direct responsibility of Subcommittee D14.80 on Metal
the leading edge of the crack. Completely linear-elastic behav-
Bonding Adhesives.
Current edition approved Jan. 1, 2020. Published January 2020. Originally ior is assumed in the calculations (see AnnexA1)of G used in
approved in 1975. Last previous edition approved in 2012 as D3433–99 (2012).
this method, an allowable assumption when the zone of
DOI: 10.1520/D3433-99R20.
nonlinear deformation in the adhesive is small relative to
The boldface numbers in parentheses refer to the references at the end of this
specimen dimensions and crack size.
test method.
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
D3433 − 99 (2020)
3.2.1.1 When the shear stress on the plane of crack and plane-strain fracture values. Comparison of fracture toughness
forward to its leading edge is zero, the stress state is termed between adhesive systems widely different in brittleness or
“opening mode.” The symbol for an opening mode G is G for toughness should take this into consideration. In general,
I
plane-strain and G when the connotation of plane-strain is not systems of similar type toughness (6, 7, 8, 9, 10) can be
wanted. compared as can the effect of environment on toughness of a
3.2.2 opening mode fracture toughness, G —thevalueof G single system. A G value is believed to represent a lower
1c 1c
justpriortoonsetofrapidfracturingwhen Gisincreasingwith limiting value of fracture toughness for a given temperature,
time. strainrate,andadhesiveconditionasdefinedbymanufacturing
variables. This value may be used to estimate the relation
3.2.3 opening mode crack arrest toughness, G —the value
1a
between failure stress and defect size for a material in service
of Gjustafterarrestofarun-arrestsegmentofcrackextension.
wherein the conditions of high constraint described above
3.2.3.1 It is assumed that the dimensions of the part con-
would be expected. Background information concerning the
taining the crack are large compared to the run-arrest segment
basis for development of this test method in terms of linear
whichprecedescrackarrestandthatthequasi-staticstressfield
elastic fracture mechanics may be found in Refs (4) and (8).
enclosingthecracktipjustaftercrackarrestcanbeassumedin
5.1.1 Cyclic loads can cause crack extension at G values
calculating G .
1a
less than G value. Furthermore, progressive stable crack
1c
extension under cyclic or sustained load may be promoted by
4. Summary of Test Method
the presence of certain environments.Therefore, application of
4.1 This test method involves cleavage testing bonded
G in the design of service components should be made with
1c
specimenssuchthatacrackismadetoextendbyatensileforce
awareness of the G increase for a prior crack which may occur
acting in a direction normal to the crack surface.
in service due to slow-stable crack-extension.
4.2 Load versus load-displacement across the bondline is
5.2 This test method can serve the following purposes:
recordedautographically.The G and G valuesarecalculated
1 1a
5.2.1 In research and development to establish, in quantita-
from this load by equations that have been established on the
tive terms, significant to service performance, the effects of
basis of elastic stress analysis of specimens of the type
adhesive composition, primers, adherend surface treatments,
described below. The validity of the determination of G and
1c
supporting adhesive carriers (scrim), processing variables, and
G values by this test method depends upon the establishment
1a
environmental effects.
of a sharp-crack condition in the bondline in a specimen of
5.2.2 In service evaluation to establish the suitability of an
adequate size. This test method will measure the fracture
adhesive system for a specific application for which the stress
strength of a bonded joint which is influenced by adherend
conditions are prescribed and for which maximum flaw sizes
surface condition, adhesive, adhesive-adherend interactions,
can be established with confidence.
primers, adhesive-supporting scrims, etc., and in which of the
5.2.3 For specifications of acceptance and manufacturing
above possible areas the crack grows.
quality control, but only when there is a sound basis for
specification of minimum G values. The specification of G
5. Significance and Use
1c 1c
values in relation to a particular application should signify that
NOTE2—Crackgrowthinadhesivebondspecimenscanproceedintwo
ways: (1) by a slow-stable extension where the crack velocity is dictated
a fracture control study has been conducted on the component
by the crosshead rate or (2) by a run-arrest extension where the stationary
in relation to the expected history of loading and environment,
crack abruptly jumps ahead outrunning the crosshead-predicted rate. The
and in relation to the sensitivity and reliability of the crack
first type of crack extension is denoted flat; the second type peaked
detection procedures that are to be applied prior to service and
because of the appearance of the autographic record. The flat behavior is
characteristic of adhesives or test temperatures, or both, for these subsequently during the anticipated life.
adhesives where there is no difference between initiation, G , and arrest,
1c
G . For example, the rubber modified film adhesives tested
1a
6. Apparatus
above−17.8°C (0°F) all exhibit flat autographic records. Peaked curves
are exhibited for all modified materials tested below −73°C (−100°F) and
6.1 Testing Machine, conforming to the requirements of
in general for unmodified epoxies.
Practices E4. Select the testing machine such that the cracking
It should be noted that both peaked and flat behaviors are determined
load of the specimens falls between 15 and 85% of the
from a crack-length-independent specimen. For other specimens or
full-scale capacity and that is provided with a suitable pair of
structures where G increases with a at constant load the onset of crack
growth would result in rapid complete fracturing whatever the adhesive self-aligning pinned fixtures to hold the specimen.
characteristics.
6.2 Ensure that the pinned fixtures and attachments are
5.1 The property G (and G if relevant) determined by
1c 1a
constructed such that they will move into alignment with the
this test method characterizes the resistance of a material to
test specimen as soon as the load is applied.
slow-stable or run-arrest fracturing in a neutral environment in
6.3 For a discussion of the calculation of separation rates
the presence of a sharp crack under severe tensile constraint,
see Annex A1.
such that the state of stress near the crack front approaches
tritensile plane strain, and the crack-tip plastic region is small
7. Test Specimens
compared with the crack size and specimen dimensions in the
constraint direction. It has not been proven that tough adhesive 7.1 Flat Adherend, conforming to the form and dimensions
systems fully meet this criteria. Therefore, data developed shown in Fig. 1, cut from test joints as in Fig. 2, prepared as
using equations based on this assumption may not represent prescribed in Section 8.
D3433 − 99 (2020)
FIG. 1 Flat Adherend Specimen
FIG. 2 Test Joint
where:
7.2 Contoured Double-Cantilever Beam (CDCB), conform-
h = thickness of metal normal to plane of bonding, mm (or in.),
ing to the form and dimensions shown in Fig. 3.
F = tensile yield point of metal (or the stress at proportional limit)
ty
7.3 Thefollowinggradesofmetalsaresuggestedforthetest
MPa (or psi),
specimens (Note 3):
T = 150% of the maximum load to start the crack in the adhesive
bond, N (or lbf),
Metal ASTM Designation
a = crack length at maximum load, mm (or in.), and
Brass B36/B36M, Alloy 260 (4), quarter hard tem-
per B = bond width, mm (or in.).
Copper B152/B152M, cold rolled, Type 110, hard
temper
8. Preparation of Test Joints
Aluminum B209, Alclad 2024, T3 temper, mill finish
Steel A366/A366M, regular matte finish
8.1 Cut sheets of the metals or contoured adherends pre-
Corrosion-resisting steel A167, Type 304, No. 2B finish
Titanium B265, Grade 3
scribed in 7.1 – 7.3 and to recommended size (Figs. 2 and 3).
7.4 Test at least twelve specimens, representing at least four
All edges of the metal panels and specimens must be flat, free
different joints.
of burrs, and smooth (4.1-µm (160-µin.) maximum) before the
panelsaresurface-treatedandbonded.Clean,treat,anddrythe
NOTE 3—Since it is unacceptable to exceed the yield point of the metal
sheetsorcontouredadherendscarefully,inaccordancewiththe
in flexure during test, the permissible thickness of the specimen will vary
with type of metal, and the general level of strength of the adhesive being
procedure prescribed by the manufacturer of the adhesive.
investigated. The minimum permissible thickness in a uniform symmetri-
Prepare and apply the adhesive in accordance with the recom-
cal adherend may be computed from the following relationship:
mendations of the manufacturer of the adhesive. Apply the
6 Ta adhesivetothefayingsurfaceofoneorbothmetalsheets.Then
h 5 (2)
Œ
BF assemble the sheets, faying surface to faying surface in pairs,
ty
D3433 − 99 (2020)
FIG. 3 Contoured Double-Cantilever Beam Specimen
and allow the adhesive to cure under conditions prescribed by 10.2 Determine the following test specimen dimensions.
the manufacturer of the adhesive.
10.2.1 Distance from center of 6.4-mm (0.25-in.) inside-
diameter pin holes to close end of specimen.
8.2 Itisrecommendedthateach“flatadherend”testjointbe
10.2.2 Width of test specimen, b.
madewithsufficientareatoprovideatleastfivetestspecimens.
10.2.3 Thickness of test specimen 127 mm (5 in.) from pin
9. Preparation of Test Specimens
end and 227 mm (9 in.) from pin end.
10.2.4 Bondlinethickness125mm(5in.)frompinendand
9.1 For flat adherend test specimens, trim joint area in
227 mm (9 in.) from pin end.
accordance with Fig. 2. Then cut test specimens, as shown in
Fig. 1, from the joints, Fig. 2 (Note 4). Then cut holes for load
10.3 Load the specimen in the test machine and pin in
pins as shown in Fig. 1.
position using the 6.4-mm (0.25-in.) inside-diameter pin holes.
9.2 Contoured double-cantilever specimens are ready for Balance the recorder or chart, or both. Set the test machine at
test as bonded. a crosshead separation raten˙ chosen to keep time-to-fracture
in the order of 1 min, see 6.1 and Annex A1. For example, 2
NOTE 4—Do not use lubricants or oils during the cutting process. For
mm/min (0.08 in./min) gives fracture in 1 min for a CDCB
aluminum it is suggested that the specimens be rough cut 3.2 mm ( ⁄8 in.)
−1
⁄2-in. wide m=90-in. aluminum adherend specimen having
over-size using a four-pitch band saw traveling at approximately 4.2 m/s
(800 ft/min) followed by finish dimensioning to a 1-in. wide 3.2-µm
a 3-in. long starter crack.
(125-µin.) surface using a five-blade 15-deg carbide fly cutter at 1115 rp
...
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