This standard specifies the shear tensile fatigue test method for spot welded joints. This standard is applicable to the shear tensile fatigue test of standard fatigue specimens of two overlapping single-point spot welded joints of metal plates with a thickness of 0.5 to 6 mm in an atmospheric environment at room temperature. The load ratio of the test is 0 to 0.2. GB/T 15111-1994 Shear tensile fatigue test method for spot welded joints GB/T15111-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for shear tensile fatigue of spot welded joints Subject content and scope of application
This standard specifies the test method for shear tensile fatigue of spot welded joints. GB/T 15111-94
This standard is applicable to the shear tensile fatigue test of standard fatigue specimens of two overlapping single-point spot welded joints of metal plates with a thickness of 0.5 to 6 mm in an atmospheric environment at room temperature. The load ratio of the test is 0~~0.2. 2 Reference standards
GB/T13816 Pulsating tensile fatigue test method for welded joints 3 Terminologybzxz.net
3.1 Shear tensile fatigue test
A fatigue test in which the shear fatigue specimen is installed between the chucks of the fatigue testing machine and a cyclic tensile load is applied. 3.2 Cyclic load F
A load that changes monotonically and periodically between a certain maximum value and a minimum value 3.3 Maximum load Fmax
The maximum value of the algebraic value of the cyclic load.
3.4 ​​Minimum load Fmin
The minimum value of the algebraic value of the cyclic load.
3.5 Load amplitude AF
The algebraic difference between the maximum load and the minimum load of the cyclic load. △F=Fm-Fmin3.6 Average load Fm
One-half of the algebraic sum of the maximum load and the minimum load of the cyclic load. 3.7 Load ratio R
The ratio of the minimum load to the maximum load. R-Fmn/Fmx. 3.8 Load capacity
The maximum load of the fatigue testing machine.
3.9 Test plate
Short strip of metal plate before spot welding.
3.10 Test piece
Assembly of test plates after spot welding.
4 Test plate and test piece
4.1 Shape and size
Approved by the State Administration of Technical Supervision on July 19, 1994 204
Implementation on May 1, 1995
GB/T15111--94
The test piece is made by spot welding two test plates of equal length with width W and thickness t. The length of the overlapping strip is Y, the length of the brace is U, and the length of the test section is V. See Figure 1 and Table 1.
Lighting position
Test plate and test piece shape
Test plate and test piece size
Plate width W
0. 5~~1. 6
>1. 6~3. 2
Overlap area Y
4.1.1 If the thickness of the two test plates is different, the shape and size of the thinner test plate shall prevail. 4.1.2 The error of the plate width W shall be ±2% of the W value in Table 1. 4.1.3 If the test piece with the shape and size other than those in this standard is used, it must be clearly indicated in the report. 4.2 Test plate production
Test section V
Above 160
Above 200
Above 240
4.2.1 The test plate shall be cut by a shearing machine. There shall be no obvious burrs on the sheared part. If there are obvious burrs, they shall be removed by mechanical processing or other methods.
4.2.2 The test plate shall not be distorted. If distorted, it shall be corrected, but no indentation shall be produced. 4.3 Test piece preparation
4.3.1 Appropriate fixtures shall be used for spot welding of the test plate. The center lines of the width of the two test plates shall be consistent, and spot welding must be performed on the center line of the overlapping part.
2 In order to avoid the deviation of the load axis and the center line of the specimen when the specimen is loaded, an additional plate can be welded to the clamping end of the specimen (as shown in Figure 4.3.2
2 or other connection methods can be used. The length of the additional plate should conform to the value of U in Figure 1. Specimen center line
Added plate
Figure 2 Schematic diagram of welding added plate
Added plate
Cutting axis
Specimen center line
And load auxiliary line
4.3.3 The specimen shall not have defects and rust after welding. 5 Testing machine
5.1 The testing machine shall be capable of applying fatigue load. GB/T1511194
5.2 The connection between the chuck of the testing machine and the specimen must be kept tight during the test. No slippage should occur during the test, and the upper and lower chucks of the testing machine should remain aligned. 5.3 The testing machine should use appropriate accessories to facilitate the observation of cracks and crack propagation behavior on both surfaces of the specimen during the test. 5.4 The testing machine should have a device to record the number of cycles and loads. 5.5 When the testing machine stops due to power outage or other reasons, it is not allowed to restart automatically. 5.6 The indicator error of the load should be the minimum of 3% of the indicated value and 0.5% of the testing machine capacity. 6 Test method
6.1 Test conditions
6.1.1 Requirements for drawing Fn curve
A Fn curve requires at least 12 specimens. If the number of specimens needs to be increased, it can be determined according to specific circumstances. b.
The load ratio should be less than or equal to 0.1. | |tt||c. The ratio of two adjacent load ranges: the inclined part of the Fn curve is 1.1~1.5, and the ratio near the fatigue limit is 1.05~1.2. 6.1.2 Requirements for determining the conditional fatigue limit
See 6.1.1b.
Several load ranges can be selected, and the number of cycles to failure of the specimen must be close to the specified number of cycles. b.
The ratio of two adjacent load ranges should be between 1.05 and 1.2.
More than two valid specimens are required for each load range. 6.2 Clamping of specimens
6.2.1 The load axis of the testing machine should be consistent with the center line of the specimen. 6.2.2 The specimen should be clamped tightly and should not slip or loosen during the test. 6.2.3 Excessive force should not be applied to the spot weld during installation. Stress. Such as hammering and other actions. 6.3 Operation of the testing machine
6.3.1 At the beginning of the test, the load should be quickly adjusted to the specified range, but the specified maximum load should not be exceeded during the debugging process. 6.3.2 The load parameters in the test should be adjusted synchronously. 6.3.3 The test frequency is in the range of 3 to 60 Hz. 6.3.4 For the same test piece, the test cannot be stopped from the beginning to the end. If the test must be stopped in the middle due to a test machine failure or other reasons, the number of cycles and the downtime should be recorded, and the data of the test piece is for reference. 6.4 Termination of the test
6.4.1 A crack equivalent to the diameter of the nugget is generated at or near any spot welding position on the two surfaces of the test piece, or the test piece is broken without cracks on the surface. The above situation is the failure of the test piece.
6.4.2 When the number of cycles of the test piece reaches 10° or reaches the specified number of condition cycles, the test can be terminated regardless of whether the test piece is destroyed. 6.4.3 Test pieces that have been tested are not allowed to be used again. 7 Test result processing
7.1 Units and significant figures
7.1.1 The load range unit is expressed in Newton. The significant figures are 3. 7.1.2 The number of cycles is expressed in scientific notation, for example: 3.34×10%. 7.1.3 The number of cycles is counted from the time the specified load range is reached. 7.2 Drawing of Fn curve and determination of fatigue limit (as shown in Figure 3) 206
GB/T 15111--94
Number of cycles n (rounds)
Figure 3 F-n curve
7.2.1 The vertical axis is the load range and the horizontal axis is the number of cycles. Use double logarithmic or single logarithmic coordinate paper to draw. N
7.2.2 When the F-n curve is a horizontal line, the load range corresponding to the horizontal line is the fatigue limit. However, the number of specimens corresponding to the load range of the horizontal line shall be not less than 2 as specified in 6.1.2c. 7.2.3 Determine the fatigue limit according to one of the following methods: Method 1: In the load range of each stage, more than half of the specimens are not damaged. The load range slightly lower than this load range is the fatigue limit.
Method 2: The fatigue limit can be determined by the GB/T13816 method. Method 3: For important components, the number of specimens in each load stage can be determined according to the specific situation, and the fatigue limit can be obtained by statistical methods. 7.3 Determination of conditional fatigue limit
7.3.1 Number of cycles
Can be determined from the following values ​​according to the working conditions of the specimen: 10*, 2×10*, 5×10*, 105, 2×105, 5×105, 10, 2×10%, 5×10%, 10. 7.3.2 Calculate the conditional fatigue limit according to the Fn curve. On the Fn curve, draw a curve according to the median value of the test point in each load range stage. The load range corresponding to the specified conditional cycle number is the conditional fatigue limit under this condition. The conditional fatigue limit determined by this method is marked with the symbol A, for example, △F(A105)=2750N, etc.
7.3.3 The conditional fatigue limit is not determined by the Fn curve. In the load ranges near the conditional cycle number, there are test results of more than 2 specimens in each load range. The conditional fatigue limit can be determined according to one of the following methods.
Method 1 The load range in which more than half of the specimens are not damaged, and the load range slightly lower than this load range does not exceed half of the specimens that are not damaged. This slightly lower load range is defined as the conditional fatigue limit. Method 2 The load range in which the specimens are not damaged is the average value of the load range of the same lower level. However, the specimens in the load range slightly lower than the average value are not damaged, and the average value is defined as the conditional fatigue limit. Method 3 For necessary important components, the number of specimens in each load stage can be determined according to the specific situation, and the fatigue limit can be obtained by statistical methods. Its symbol is B, for example: AF(B105)=2750N, etc. 8 Test report
The test report includes all the contents of Articles 8.1 to 8.11, and the test results can be filled in the table in Appendix A (reference). 8.1 Test time and place.
8.2 Type, name and nominal thickness of test material. 8.3 Chemical composition of test material.
8.4 Heat treatment and surface treatment of test material. 8.5 Mechanical properties of test material.
8.6 Shape and size of test piece.
8.7 Type, model and rated capacity of spot welding machine. 8.8 Spot welding conditions and diameter of spot welding nugget. GB/T 15111—94
8.9 Type (fixed load type, fixed displacement type), model and capacity of testing machine. 8.10 Load range, maximum load, minimum load, load ratio, average load and cheek rate of testing machine. 8.11
Fn curve diagram, fatigue limit or conditional fatigue limit determination method. 208
Material brand
Specimen number
Specimen number
Maximum capacity, N
Test frequency, Hz
Rated capacity, kVA
Cycle, Hz
Maximum pressure, N
Maximum current, A
Diameter, mm
Tip shape and size, mm
GB/T 15111-94
Appendix A
Test result table
(reference)
Types and mechanical properties of test materials
Table A2 Chemical composition of plate
Nominal composition, %
Table A3 Fatigue testing machine
Table A4 Spot welding machine, welding conditions and welding results Welding conditions
Current, A
Electrode pressure, N
Main power-on time, s
Current, A
Time, s
Current, A
Time, s
Re-test composition before test, %
Fatigue strength
Welding results
Nugget diameter
Specimen number
Load range
Additional instructions:
Average load
GB/T 15111—94
Table A5 Fatigue test conditions and results
Maximum and minimum loads
Load ratio
This standard is proposed and managed by the National Technical Committee for Welding Standardization. This standard is drafted by Harbin Welding Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Zhang Baochang and Jiao Wei. 210
Number of cycles
(weeks)
Fracturing conditions
Fracturing form）
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