1. Scope of application
A method for determining the tensile shear strength of a metal-to-metal lap joint at room temperature is specified. This standard applies to standard samples prepared and tested under specified conditions.
GB 7124-1986 Equivalent ISO 4587-1979 "Adhesives - Determination of tensile shear strength of high-strength adhesives".
The sample is a single overlap structure. A longitudinal tensile shear force is applied to the overlapping surface of the sample, and the maximum load that the sample can withstand is measured. The average shear stress on the lap joint is the tensile shear strength of the adhesive metal lap.
3.1 Testing machine
The test machine shall be used so that the destruction load of the specimen is between 15% and 85% of the full-scale load. The error value of the testing machine should not exceed 1%.
The testing machine shall be equipped with a self-aligning sample holder so that the force line is consistent with the sample centerline.
The testing machine shall ensure that the movement speed of the specimen holder is stable within (5 Â± 1) mm/min.
3.2 Measuring Tools
05mmã€‚ Measuring the length of the sample overlap surface and the width of the measuring tool accuracy is not less than 0. 05mm.
The fixture of the bonded specimen shall be such that the bonded specimen meets the requirements of Clause 4.
(Note: In the case of ensuring that the metal sheet is not damaged, the sample and sample holder can also be connected by pins and holes. However, it cannot be used for arbitration tests.)
4.1 Unless otherwise specified, the specimen shall conform to the shape and dimensions of Figure 1. The lap length of the standard sample was (12.5 Â± 0.5) mm, and the thickness of the metal piece was (2.0 Â± 0.1) mm [ISO thickness (1.6 Â± 0.1) mm]. The lap length of the sample or the thickness of the metal plate will have an effect on the test results.
4. 2 It is recommended to use LY12-CZ aluminum alloy, 1Cr18Ni9Ti stainless steel, 45 carbon steel, T2 copper and other metal materials.
4.3 routine test, the number of samples should not be less than five. The number of arbitration test samples should not be less than ten.
Note: 1. For high-strength colloidal dry agents, if there is a situation where the metal material yields or breaks during the lateral test, it may be appropriate to increase the thickness of the metal sheet or reduce the overlap length. The former is better.
2. The stress on the sheet metal during the test should not exceed the yield strength Ïƒs. The thickness t of the sheet metal can be calculated as follows: t= lgÏ„/Ïƒs
In the formula: t A metal sheet thickness, mm;
l A sample lap length, mm;
Ï„ an adhesive tensile shear strength, Mpa;
Ïƒsâ€”Metal material yield strength, MPa.
5. Sample preparation
5.1 Specimens can be prepared on plates without troughs (Figure 2) or with troughs (Figure 3), but they can also be prepared monolithically.
5.2 The surface of the metal sheet used for bonding should be flat and should not be bent, warped, skewed, etc. The metal sheet should be free of burrs and the edges should be at right angles.
5.3 Adhesive, surface treatment of the metal sheet, the ratio of the adhesive, the amount of glue applied, the number of times of coating, the open time, etc., and the curing temperature, pressure, and time of the adhesive are all in accordance with the requirements of the adhesive.
5.4 The specimen shall be prepared using a jig to ensure that the specimen is correctly overlapped and accurately positioned.
5.5 When cutting the bonded flat plate, to prevent the sample from overheating, damage to the plastic joints should be avoided as much as possible.
6. Test conditions
Unless otherwise specified, the test time and test environment should meet the following requirements.
6.1 The shortest time from sample preparation to test is 16 hours, and the maximum time is one month.
6.2 The test shall be conducted in an environment with a temperature of (2312) Â°C. Arbitration tests or adhesives sensitive to temperature and humidity shall be performed in an environment with a temperature of (23 Â± 2) Â°C and a relative humidity of 45% - 55%.
6.3 For temperature-only tests, the test time at the test temperature before the test shall not be less than half an hour; for tests with temperature and humidity requirements, the test time for the test sample in the test environment shall not be less At 16h.
7. Test procedure
7.1 é‡å…· With the length and width of the test sample overlap surface, accurate to 0. 05mm.
7.2 The sample is symmetrically clamped in the upper and lower holders, and the distance from the clamping point to the lap joint (50 Â± 1) mm.
7.3 Start the tester and load at a steady speed within (5 Â± 1) mm/min. Record the maximum load of specimen shear failure. Record the type of bonding failure (cohesive failure, adhesion failure, metal failure).
8. Test results
8.1 Tensile Shear Strength of Adhesives to Metal Bonds Calculated as follows:
Where: Ï„ a tensile shear strength of the adhesive, MPa;
p - the maximum load of specimen shear failure, N;
Bâ€”the width of the sample overlap surface, mm;
Lâ€”Length of sample overlap surface, in mm.
8.2 Test results are expressed as the arithmetic mean, maximum, and minimum values â€‹â€‹of shear strength. Take three valid figures.
9. Test report
The test report should include the following:
a. Model and lot number of the adhesive;
b. Metal material model, thickness and surface treatment method;
c. necessary instructions for sample preparation method (without groove plate, grooved plate, single piece) and bonding process;
d. Sample lap length;
e. The number of samples;
f. test results (arithmetic mean, maximum, minimum);
g. The type and amount of damage to the sample;
h. The average thickness of the glue layer;
i. Differences from this standard.
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