上海拉力機(jī)；上海拉力機(jī)維修；上海拉力機(jī)報價

唐   

B 36/B36M Specification for Brass Plate, Sheet, Strip, and
Rolled Bar3
B 152 Specification for Copper Sheet, Strip, Plate, and
Rolled Bar3
B 209 Specification for Aluminum and Aluminum-Alloy
Sheet and Plate4
B 265 Specification for Titanium and Titanium Alloy Strip,
Sheet, and Plate5
D 907 Terminology of Adhesives6
D 4896 Guide for Use of Adhesive-Bonded Single Lap-
Joint Specimen Test Results6
E 4 Practices for Force Verification of Testing Machines7
3. Terminology
3.1 Definitions—Many terms in this test method are defined
in Terminology D 907.
4. Significance and Use
4.1 This test method is primarily comparative. However, it
does have application as a discriminator in determining variations
in adherend surface preparation parameters and adhesive
environmental durability. The test method has found applications
in controlling surface preparations, primer, and adhesive
systems for determining strength properties of tested systems.
4.2 The misuse of strength values obtained from this test
method as design-allowable stress values for structural joints
could lead to product failure, property damage, and human
injury. The apparent shear strength of an adhesive obtained
from a given small single-lap specimen may differ from that
obtained from a joint made with different adherends or by a
different bonding process. The normal variation of temperature
and moisture in the service environment causes the adherends
and the adhesive to swell or shrink. The adherends and
adhesive are likely to have different thermal and moisture
coefficients of expansion.
4.3 Even in small specimens, short-term environmental
changes may induce internal stresses or chemical changes in
the adhesive that permanently affect the apparent strength and
other mechanical properties of the adhesive. The problem of
predicting joint behavior in a changing environment is even
more difficult if a different type of adherend is used in a larger
structural joint than was used in the small specimen.
4.4 The apparent shear strength measured with a single-lap
specimen is not suitable for determining design-allowable
stresses for designing structural joints that differ in any manner
from the joints tested without thorough analysis and understanding
of the joint and adhesive behaviors.
4.5 Single-lap tests may be used for comparing and selecting
adhesives or bonding processes for susceptibility to fatigue
and environmental changes, but such comparisons must be
made with great caution since different adhesives may respond
differently in different joints. See Guide D 4896 for further
discussion of the concepts relative to interpretation of
adhesive-bonded single-lap-joints.
5. Apparatus
5.1 The testing machine shall conform to the requirements
of Practices E 4. The testing machine shall be so selected that
the breaking load of the specimens falls between 15 and 85
percent of the full-scale capacity. The machine shall be capable
of maintaining a rate of loading of 80 to 100 kg/cm2 （1200 to
1400 psi）/min, or, if the rate is dependent on crosshead motion,
the machine should be set to approach this rate of loading,
approximay 0.05 in./min. It shall be provided with a suitable
pair of self-aligning grips to hold the specimen. It is recommended
that the jaws of these grips shall engage the outer 25
mm （1 in.） of each end of the test specimen firmly.
5.2 The grips and attachments shall be so constructed that
they will move into alignment with the test specimen as soon
as the 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 assembly.
5.3 The length of overlap of the specimen may be varied
where necessary. The length of the specimen in the jaws,
however, must not be varied. The distance from the end of the
lap to the end of the jaws should be 63 mm （21⁄2 in.） in all tests.
6. Test Specimens
6.1 Test specimens shall conform to the form and dimensions
shown in Fig. 1. These shall be cut from test panels
prepared as prescribed in Section 7. The recommended thickness
of the sheets is 1.62 6 0.125 mm （0.064 6 0.005 in.）. The
recommended length of overlap for most metals of 1.62 mm
（0.064 in.） in thickness is 12.7 6 0.25 mm （0.5 6 0.01 in.）.
6.2 Since it is undesirable to exceed the yield point of the
metal in tension during test, the permissible length of overlap
in the specimen will vary with the thickness and type of metal,
and on the general level of strength of the adhesive being
investigated. The maximum permissible length may be computed
from the following relationship:
L 5 Fty t/t （1）
where:
L = length of overlap, in.,
t = thickness of metal, in.,
Fty = yield point of metal （or the stress at proportional
limit）, psi, and
t = 150 percent of the estimated average shear strength
in adhesive bond, psi.
6.3 A variation in thickness of the metal, and the length of
overlap, will likely influence the test values and make direct
comparison of data questionable. For this reason, in comparative
or specification tests, the thickness should preferably be
1.62 6 0.125 mm （0.064 6 0.005 in.） and the length of overlap
3 Annual Book of ASTM Standards, Vol 02.01.
4 Annual Book of ASTM Standards, Vol 02.02.
5 Annual Book of ASTM Standards, Vol 02.04.
6 Annual Book of ASTM Standards, Vol 15.06.
7 Annual Book of ASTM Standards, Vol 03.01. FIG. 1 Form and Dimensions of Test Specimen
D 1002

上海拉力機(jī)；上海拉力機(jī)維修；上海拉力機(jī)報價
2
should preferably be 12.7 6 0.25 mm （0.5 6 0.01 in.）, or not
in excess of the value computed in 6.2. For development tests
values could be different, but should then be constant.
6.4 The following grades of metal are recommended for the
test specimens:
Metal ASTM Designation
Brass B 36, C26800 （Alloy 8）
Copper B 152, C11000
Aluminum B 209, Alloy 2024, T3 temper
Steel A 109, Grade 2
Corrosion-resisting steel A 167, Type 302
Titanium B 265
6.5 At least 30 specimens shall be tested, representing at
least four different joints. However, if statistical analysis of
data and variance is employed, it should be possible to reduce
this number.
7. Preparation of Test Joints
7.1 It is recommended that test specimens be made up in
multiples of at least five specimens, and then cut into individual
test specimens （Note 1）, Fig. 2 and Fig. 3. Cut sheets of
the metals prescribed in 6.1 and 6.4 to suitable size. All edges
of the metal panels and specimens which will be within （or
which will bound） the lap joints shall be machined true
（without burrs or bevels and at right angles to faces） and
smooth （rms 160 max） before the panels are surface-treated
and bonded. Clean and dry the sheets carefully, according to
the procedure prescribed by the manufacturer of the adhesive,
and assemble in pairs. Prepare and apply the adhesive according
to the recommendations of the manufacturer of the adhesive.
Apply the adhesive to a sufficient length in the area across
FIG. 2 Standard Test Panel
D 1002
3

上海拉力機(jī)；上海拉力機(jī)維修；上海拉力機(jī)報價