Unilateral bending angle joint weld toe fatigue test device and method

Abstract

The invention discloses a unilateral bending angle joint weld toe fatigue test device and method. The unilateral bending angle joint weld toe fatigue test device comprises a clamp, a T-shaped sample and a fatigue testing machine. The whole clamp is in an L shape and comprises a bottom plate and a vertical plate, and the vertical plate is vertically fixed to the bottom plate and located on one side of the bottom plate. The T-shaped sample comprises an installation plate and a web plate, the T-shaped sample is fixedly installed on the to-be-clamped face of the vertical plate through the installation plate, and the whole clamp after clamping is fixedly installed on an installation base through the bottom plate. By designing the L-shaped clamp, after the T-shaped sample is mounted on the L-shaped clamp, a web of the T-shaped sample can form a cantilever beam form, so that a fatigue testing machine can apply a vertical load to the web of the T-shaped sample, a welding seam between the web and a mounting plate can bear a single bending load, and the welding seam can be ensured to bear uniform concentrated stress; therefore, the bending fatigue life and the fatigue damage behavior of the weld joint of the sample under the real working condition can be comprehensively reflected, so that the bending fatigue performance of the weld joint can be accurately evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of fatigue testing, and in particular to a device and method for fatigue testing a weld toe of a single-sided bending angle joint. Background Art

[0002] In the field of mining machinery manufacturing, welded structures are widely used due to their advantages such as high material utilization, low manufacturing cost, and strong design flexibility. For important parts such as mine car frames and excavator booms, they are often subjected to complex and variable loads, including but not limited to strong dynamic impacts, cyclic overload alternations and other extreme conditions. As the weak link of the structure, the fatigue performance of welded joints is directly related to the stability and durability of the overall structure. Among them, fillet joints (especially single-sided fillet welds and double-sided fillet welds) are more common in mining machinery, which often bear complex stress states such as bending or shearing. Therefore, the fatigue performance evaluation of fillet joints needs to comprehensively consider the influence of load properties.

[0003] At present, there are many test methods for fatigue performance evaluation of welded joints, such as butt pulsating stretching, cross joint pulsating stretching, rotational bending fatigue, T-joint three-point / four-point bending, etc. However, these methods cannot accurately simulate the alternating bending load of welded joints and their materials in actual use, so as to evaluate their bending fatigue performance. Taking the three-point bending fatigue test of corner joints as an example, it mainly applies a concentrated load on the top of the specimen to cause bending deformation between two supporting points, and then evaluates the mechanical properties of the material such as bending resistance and fatigue life. However, the stress distribution of this concentrated loading test is uneven, especially in the weld area, which leads to inaccurate evaluation of the bending fatigue performance of the weld, and cannot fully reflect the bending fatigue life and fatigue damage behavior under real working conditions.

[0004] On the other hand, excluding structural design factors, from a process perspective, strengthening the fatigue strength of the weld toe of fillet joints is a common and effective strategy to improve the overall fatigue performance of the joint. However, in the actual test evaluation process, the notch effect at the weld root of a single-sided fillet joint is much greater than the fatigue stress concentration at the weld toe. Therefore, fatigue cracks usually tend to initiate first in the weld root area. This phenomenon hinders the in-depth analysis and accurate evaluation of how bending stress and its post-processing process specifically affect the fatigue performance of the weld toe, limiting the accuracy and effectiveness of the test evaluation.

[0005] In order to solve the limitations of uneven bending fatigue stress distribution of existing corner joint specimens and the inability to fully evaluate the influence of stress concentration in the weld toe of corner joints on fatigue damage behavior, based on the standardization and accuracy of the test method, it is urgently necessary to accurately evaluate the fatigue damage behavior of corner joints under a single bending load through reasonable joint design, optimized welding process, specific specimen clamping, and accurate test data analysis, so as to effectively support the fatigue life prediction and performance optimization of heavy-loaded welded structures. Summary of the invention

[0006] In view of this, the present invention provides a single-sided bending angle joint weld toe fatigue testing device, which can apply a single bending load to a specimen to ensure that the stress distribution at the specimen weld is more uniform.

[0007] To achieve the above object, the present invention provides the following technical solutions: A single-side bending angle joint weld toe fatigue test device comprises: a fixture, a T-type specimen and a fatigue testing machine.

[0008] Among them, the fatigue testing machine is provided with a mounting base; the fixture is L-shaped as a whole, and the fixture includes a bottom plate and a vertical plate, the vertical plate is vertically fixed on the bottom plate, and is located on one side of the bottom plate; the T-type specimen includes a mounting plate and a web plate, the web plate is vertically welded to the middle of the mounting plate, and the T-type specimen is fixedly mounted on the clamping surface of the vertical plate through the mounting plate to complete the clamping of the specimen, and the clamped fixture as a whole is fixedly mounted on the mounting base through the bottom plate.

[0009] Preferably, the clamp further comprises a rib plate, wherein two rib plates are provided, the two rib plates are symmetrically arranged on the bottom plate, and one side of the two rib plates is connected to the vertical plate.

[0010] Preferably, the bottoms of the vertical plates and the rib plates are provided with K-shaped grooves, and both are fixedly mounted on the base plate by double-sided welding.

[0011] Preferably, the bottom end of the rib plate away from the vertical plate is fillet welded, and the weld is polished into an arc shape.

[0012] Preferably, after the fixture is assembled as a whole, the bottom surface of the base plate and the clamping surface of the vertical plate are both polished.

[0013] Preferably, a mounting through hole is opened on the bottom plate, a mounting base is provided on the fatigue testing machine, a T-shaped groove is provided on the mounting base, a T-shaped bolt is provided in the T-shaped groove, the T-shaped bolt passes through the mounting through hole and cooperates with a nut to tighten and fix the bottom plate.

[0014] Preferably, a K-shaped groove is formed at the bottom of the web, and the web is fixedly mounted on the mounting plate by double-sided symmetrical full penetration welding.

[0015] Preferably, bolt holes are arranged at the four corners of the mounting plate, and oblong holes corresponding to the bolt holes and connected with the bolts are opened on the vertical plate.

[0016] The present invention also discloses a fatigue test method for a weld toe of a single-sided bent fillet joint, which includes: fatigue test and data analysis and calculation; The fatigue test process includes: S1. Bolting the T-type specimen to the clamping surface of the vertical plate of the L-type clamp; S2. Bolting the L-type clamp to the mounting base of the fatigue testing machine; S3. Calibrating the fatigue testing machine; S4. Using the fatigue testing machine to cyclically apply load to the web of the T-type specimen until the weld between the web and the mounting plate breaks; S5. Replacing the T-type specimen and performing repeated cycle tests.

[0017] Data analysis and calculation include: S1, obtaining the overall size data and weld size data of the T-type specimen, and calculating the stress concentration factor of the weld toe notch; S2, obtaining the number of cycles and load amplitude when the T-type specimen is fatigue fractured; S3, according to the cantilever beam bending stress concentration calculation formula: , the applied vertical load is transformed into stress load to obtain the bending nominal stress amplitude; in the formula: b is the width of the T-type specimen, h is the thickness of the T-type specimen, l is the cantilever beam force arm, F m is the load amplitude, s is the bending nominal stress amplitude; S4, the SN curve of the T-type specimen is obtained by importing the number of cycles and the bending nominal stress amplitude into the data analysis software for data analysis; S5, the "notch-life" mapping relationship under bending load conditions is established based on the weld toe notch stress concentration factor and the SN curve.

[0018] Preferably, the calibrating the fatigue testing machine includes: ensuring that the indenter of the fatigue testing machine and the bolts on the mounting base are both on the loading center axis; ensuring that the indenter of the fatigue testing machine is more than 10 mm away from the weld toe on the T-type specimen.

[0019] Preferably, the obtaining of the overall dimension data and weld dimension data of the T-type specimen and the calculation of the weld toe notch stress concentration coefficient comprises: performing laser scanning on the overall body and weld of the T-type specimen, and performing measurement and statistical analysis on the scanned model of the T-type specimen using three-dimensional software to obtain the overall dimension data and weld dimension data of the T-type specimen; performing statistical analysis on the weld size and weld toe arc radius in the three-dimensional model of the T-type specimen exported by the three-dimensional software using metrology software, and calculating the statistical analysis results using the finite element method to obtain the maximum stress of the weld toe notch; calculating the weld toe notch stress intensity factor according to the maximum stress of the weld toe notch, and calculating the weld toe notch stress concentration coefficient based on the weld toe notch stress intensity factor.

[0020] Compared with the prior art, the present application discloses a single-sided bending angle joint weld toe fatigue testing device, which designs an L-shaped fixture so that after the T-shaped specimen is installed on the L-shaped fixture, its web can form a cantilever beam. In this way, the fatigue testing machine can apply a vertical load to the web of the T-shaped specimen, so that the weld between the web and the mounting plate can be subjected to a single bending load, and can ensure that the weld is subjected to uniform concentrated stress, thereby being able to fully reflect the bending fatigue life and fatigue damage behavior at the specimen weld under actual working conditions, so as to accurately evaluate the bending fatigue performance of the weld.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a single-sided bending fillet joint weld toe fatigue test device disclosed in an embodiment of the present application; Figure 2 is a side view of a single-sided bending fillet joint weld toe fatigue test device disclosed in an embodiment of the present application; Figure 3 It is a schematic structural diagram of a fixture of a single-sided bending fillet joint weld toe fatigue test device disclosed in an embodiment of the present application; Figure 4 It is a front view of a T-shaped specimen of a single-sided bending fillet joint weld toe fatigue test device disclosed in an embodiment of the present application; Figure 5 is a top view of a T-shaped specimen of a single-sided bending fillet joint weld toe fatigue test device disclosed in an embodiment of the present application; Figure 6 It is the SN curve diagram of the present invention.

[0023] Reference numerals: 1. Clamp; 11. Bottom plate; 12. Vertical plate; 13. Rib plate; 111. Mounting through hole; 121. Long round hole; 2. T-type specimen; 21. Mounting plate; 22. Web plate; 211. Bolt hole; 31. Mounting base; 32. Press head; 311. T-shaped groove; 4. Load the center axis. DETAILED DESCRIPTION

[0024] The invention discloses a single-sided bending angle joint weld toe fatigue test device, which can apply a single bending load to a sample to ensure that the stress distribution at the sample weld is more uniform.

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] Reference below Figures 1 to 6 A single-sided bending fillet joint weld toe fatigue test device in an embodiment of the present invention is described.

[0028] The embodiment of the present application discloses a single-sided bending angle joint weld toe fatigue testing device, comprising: a fixture 1, a T-type specimen 2 and a fatigue testing machine.

[0029] Among them, a mounting base 31 is provided on the fatigue testing machine; the fixture 1 is L-shaped as a whole, and the fixture 1 includes a bottom plate 11 and a vertical plate 12, the vertical plate 12 is vertically fixed on the bottom plate 11, and is located on one side of the bottom plate 11; the T-type specimen 2 includes a mounting plate 21 and a web 22, the web 22 is vertically welded to the middle of the mounting plate 21, and the T-type specimen 2 is fixedly mounted on the surface to be clamped of the vertical plate 12 through the mounting plate 21 to complete the clamping of the specimen. After clamping, the fixture 1 is fixedly mounted on the mounting base 31 through the bottom plate 11 as a whole.

[0030] By designing the L-shaped fixture 1, the web 22 of the T-shaped specimen 2 can form a cantilever beam after being installed on the L-shaped fixture 1. In this way, the fatigue testing machine can apply a vertical load to the web 22 of the T-shaped specimen 2, so that the weld between the web 22 and the mounting plate 21 can be subjected to a single bending load, and can ensure that the weld is subjected to uniform concentrated stress, thereby being able to fully reflect the bending fatigue life and fatigue damage behavior of the specimen weld under actual working conditions, so as to accurately evaluate the bending fatigue performance of the weld.

[0031] In order to ensure the accuracy of the test, it is necessary to ensure the integrity of the structure of the T-shaped test specimen 2. Therefore, in order to avoid defects in the T-shaped test specimen 2 during the preparation process of the T-shaped test specimen 2, the material and welding of the T-shaped test specimen 2 are optimized accordingly in this embodiment.

[0032] First, Z-direction steel (anti-laminar tearing steel) is selected as the manufacturing material of T-type specimen 2 to avoid tearing between plate layers when T-type specimen 2 is subjected to large alternating loads, ensuring that the base material of T-type specimen 2 itself has excellent fatigue resistance.

[0033] Secondly, during the welding process of the T-type specimen 2, the arc-starting plate and the arc-ending plate are riveted and welded at both ends of the test plate to avoid welding defects that may occur at the arc-starting and arc-extinguishing positions. At the same time, multiple process tie bars are spot-welded at intervals on the back of the mounting plate 21 of the T-type specimen 2 to avoid the angular deformation of the mounting plate 21 caused by the welding stress caused by the uneven heating and cooling during the welding process, thereby ensuring the flatness of the mounting plate 21. In addition, a K-shaped groove is provided at the bottom of the web 22 of the T-type specimen 2, and is fixedly mounted on the mounting plate 21 by double-sided symmetrical full penetration welding, wherein the double-sided symmetrical full penetration welding is preferably a gas shielded arc welding; this can avoid the weld root fatigue cracking caused by the large weld root notch effect of the traditional single-sided fillet weld and the double-sided non-full penetration fillet weld under the unilateral bending load, and thus cannot accurately evaluate the problem of the influence of the weld toe stress concentration on the fatigue damage behavior of the joint. In addition, after the welding of the T-type specimen 2 is completed, the weld of the T-type specimen 2 is subjected to carbon arc gas planing and root cleaning treatment to ensure full penetration welding at the root.

[0034] Finally, when the T-type specimen 2 is cut and sampled, the process route of wire cutting, milling, and low-stress grinding is used to cut and process the T-type specimen 2 to ensure the shape and position tolerance requirements of the specimen. At the same time, the sampled T-type specimen 2 is visually inspected to ensure that the axial processing marks of the T-type specimen 2 have been removed by polishing, and there are no other influencing factors such as scratches, pits and cracks.

[0035] In some embodiments, the fixture 1 further includes a rib plate 13, for example Figure 3 As shown, two rib plates 13 are provided, and the two rib plates 13 are symmetrically arranged on the bottom plate 11, and one side of the two rib plates 13 is connected to the vertical plate 12. The provision of the rib plates 13 can enhance the structural stability of the clamp 1 when it is subjected to bending loads.

[0036] Furthermore, the overall height of the rib plate 13 is the same as the width of the T-shaped test specimen 2, so that the eccentric vibration of the fatigue testing machine caused by the eccentric bending load can be greatly reduced, thereby avoiding the fracture of the indenter 32 of the fatigue testing machine or the failure of the fatigue testing machine.

[0037] In some embodiments, for example Figure 3 As shown, the bottom of the vertical plate 12 and the rib plate 13 is provided with a K-shaped groove, and both are fixedly mounted on the bottom plate 11 by double-sided welding. The K-shaped groove can effectively increase the welding penetration, and the double-sided welding can increase the ability of the rib plate 13 to resist fatigue loads.

[0038] In some embodiments, the bottom end of the rib plate 13 away from the vertical plate 12 is fillet welded, and the weld is polished into an arc shape, which can effectively reduce the occurrence of cracking of the clamp 1 itself due to fatigue stress concentration.

[0039] In some embodiments, after the overall assembly of the fixture 1 is completed, the bottom surface of the base plate 11 and the clamping surface of the vertical plate 12 are polished. In this way, the installation flatness and verticality of the fixture 1 during clamping can be ensured, the clamping accuracy of the T-shaped specimen 2 can be effectively improved, and the service life of the fixture 1 can be extended.

[0040] In some embodiments, a mounting hole 111 is opened on the bottom plate 11, and a mounting base 31 is provided on the fatigue testing machine. A T-shaped groove 311 is provided on the mounting base 31, and a T-shaped bolt is provided in the T-shaped groove 311. The T-shaped bolt passes through the mounting hole 111 and cooperates with a nut to tighten and fix the bottom plate 11. In this way, the overall installation stability of the fixture 1 can be guaranteed to ensure the stable progress of the fatigue test.

[0041] In some embodiments, for example Figure 5 As shown, bolt holes 211 are provided at the four corners of the mounting plate 21, and oblong holes 121 corresponding to the bolt holes 211 are provided on the vertical plate 12. The oblong holes 121 can reserve a certain amount of installation adjustment to reduce the difficulty of installation.

[0042] In this embodiment, the installation position of the bolt is ensured to be more than 10 mm away from the weld toe to ensure that the tightening force of the bolt will not interfere with the fatigue performance evaluation of the weld, thereby fully evaluating the fatigue damage behavior of the weld toe of the T-joint under unilateral bending load conditions and different post-weld treatment processes.

[0043] The present invention also discloses a single-sided curved angle joint weld toe fatigue test method, which is applied to the single-sided curved angle joint weld toe fatigue test device in the above embodiment, including: fatigue test and data analysis and calculation; The fatigue test process includes: S1, bolting the T-type specimen 2 to the clamping surface of the vertical plate 12 of the L-type clamp 1; S2, bolting the L-type clamp 1 to the mounting base 31 of the fatigue testing machine; S3, calibrating the fatigue testing machine; S4, using the fatigue testing machine to cyclically apply load to the web 22 of the T-type specimen 2 until the weld between the web 22 and the mounting plate 21 is broken; S5, replacing the T-type specimen 2 and performing repeated cycle tests.

[0044] Data analysis and calculation include: S1, obtaining the overall size data and weld size data of T-type specimen 2, and calculating the stress concentration factor of weld toe notch; S2, obtaining the number of cycles and load amplitude when T-type specimen 2 is fatigue fractured; S3, according to the cantilever beam bending stress concentration calculation formula: , the applied vertical load is transformed into stress load to obtain the bending nominal stress amplitude; in the formula: b is the width of the T-type specimen, h is the thickness of the T-type specimen, l is the cantilever beam force arm, F m is the load amplitude, s is the bending nominal stress amplitude; S4, by importing the number of cycles and the bending nominal stress amplitude into the data analysis software for data analysis, the SN curve (fatigue design curve) of T-type specimen 2 is obtained; S5, according to the weld toe notch stress concentration factor and the SN curve, the "notch-life" mapping relationship under the bending load condition is established.

[0045] Fatigue tests are carried out on T-type specimen 2 according to the above fatigue test process, and the data obtained in the fatigue test are processed according to the above data analysis and calculation methods. This allows the fatigue test plan to focus on the stress concentration factor at the weld toe, and comprehensively and accurately measure the actual effects of different post-weld treatment technologies on improving the fatigue strength of the weld toe under a bending load environment, thereby ensuring the accuracy and effectiveness of the evaluation. At the same time, it can accurately evaluate the fatigue damage behavior of the fillet joint under a single bending load, and effectively support the fatigue life prediction and performance optimization of the welded structure.

[0046] In some embodiments, the fatigue testing machine is calibrated, including: ensuring that the pressure head 32 of the fatigue testing machine and the bolts on the mounting base 31 are both on the loading center axis 4 to reduce the impact of eccentric vibration; ensuring that the pressure head 32 of the fatigue testing machine is more than 10 mm away from the weld toe on the T-type specimen 2 to avoid the pressure head 32 causing direct stress concentration or interference to the weld toe area of ​​the weld.

[0047] In some embodiments, the overall dimension data and weld dimension data of the T-type specimen 2 are obtained, and the weld toe notch stress concentration coefficient is calculated, including: laser scanning the entire T-type specimen 2 and the weld, and using three-dimensional software to perform measurement and statistical analysis on the scanned model of the T-type specimen 2 to obtain the overall dimension data and weld dimension data of the T-type specimen 2; using metrology software to perform statistical analysis on the weld size and weld toe arc radius in the three-dimensional model of the T-type specimen 2 exported by the three-dimensional software, and calculating the statistical analysis results by finite element method to obtain the maximum stress of the weld toe notch; calculating the weld toe notch stress intensity factor according to the maximum stress of the weld toe notch, and calculating the weld toe notch stress concentration coefficient based on the weld toe notch stress intensity factor.

[0048] Other structures and operations of the single-sided bending angle joint weld toe fatigue testing device and the single-sided bending angle joint weld toe fatigue testing method according to the embodiments of the present invention are well known to ordinary technicians in the field and will not be described in detail here.

[0049] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0050] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A single-sided bending fillet joint weld toe fatigue test device, characterized in that: include: Fixtures, T-specimens and fatigue testing machines; The fatigue testing machine is provided with a mounting base; The clamp is L-shaped as a whole, and comprises a bottom plate and a vertical plate, wherein the vertical plate is vertically fixed on the bottom plate and is located on one side of the bottom plate; The T-shaped specimen includes a mounting plate and a web, the web is vertically welded to the middle of the mounting plate, and the T-shaped specimen is fixedly mounted on the surface to be clamped of the vertical plate through the mounting plate to complete the clamping of the specimen. After clamping, the entire fixture is fixedly mounted on the mounting base through the bottom plate.

2. The single-sided bending fillet joint weld toe fatigue test device according to claim 1 is characterized in that: The clamp further comprises a rib plate, wherein two rib plates are provided, the two rib plates are symmetrically arranged on the bottom plate, and one side of the two rib plates is connected to the vertical plate.

3. The single-sided bending fillet joint weld toe fatigue test device according to claim 2 is characterized in that: The bottoms of the vertical plate and the rib plate are provided with K-shaped grooves, and both are fixedly mounted on the bottom plate by double-sided welding.

4. The single-sided bending fillet joint weld toe fatigue test device according to claim 3 is characterized in that: The end of the rib plate away from the bottom of the vertical plate is fillet welded, and the weld is polished into an arc shape.

5. The single-sided bending fillet joint weld toe fatigue test device according to claim 1 is characterized in that: After the fixture is assembled as a whole, the bottom surface of the bottom plate and the clamping surface of the vertical plate are both polished.

6. The single-sided bending fillet joint weld toe fatigue test device according to claim 1, characterized in that: The bottom plate is provided with a mounting hole, the fatigue testing machine is provided with a mounting base, the mounting base is provided with a T-shaped groove, a T-shaped bolt is provided in the T-shaped groove, the T-shaped bolt passes through the mounting hole and cooperates with a nut to tighten and fix the bottom plate.

7. The single-sided bending fillet joint weld toe fatigue test device according to claim 1 is characterized in that: The bottom of the web is provided with a K-shaped groove and is fixedly mounted on the mounting plate by double-sided symmetrical full penetration welding.

8. The single-sided bending fillet joint weld toe fatigue test device according to claim 1 is characterized in that: The four corners of the mounting plate are provided with bolt holes, and the vertical plate is provided with oblong holes corresponding to the bolt holes and connected with bolts.

9. A single-sided bending fillet joint weld toe fatigue test method, characterized in that: The single-sided bent fillet joint weld toe fatigue test device according to any one of claims 1 to 8, comprising: fatigue testing and data analysis and calculation; The fatigue testing process includes: S1. Connect the T-type specimen bolts to the clamping surface of the vertical plate of the L-type fixture; S2. Bolt the L-shaped clamp onto the mounting base of the fatigue testing machine; S3. Calibrate the fatigue testing machine; S4, using a fatigue testing machine to cyclically apply load to the web of the T-type specimen until the weld between the web and the mounting plate breaks; S5. Replace the T-type specimen and repeat the cycle test; Data analysis and calculations include: S1. Obtain the overall dimension data and weld dimension data of the T-type specimen, and calculate the stress concentration factor of the weld toe notch; S2, obtaining the number of cycles and load amplitude when the T-type specimen is fatigue fractured; S3. According to the cantilever beam bending stress concentration calculation formula: , perform stress load transformation on the applied vertical load to obtain the bending nominal stress amplitude; In the formula: b is the width of the T-type specimen, h is the thickness of the T-type specimen, l is the cantilever beam force arm, F m is the load amplitude, s is the bending nominal stress amplitude; S4, by importing the number of cycles and the bending nominal stress amplitude into the data analysis software for data analysis, the SN curve of the T-type specimen is obtained; S5. According to the weld toe notch stress concentration factor and SN curve, the "notch-life" mapping relationship under bending load conditions is established.

10. The single-sided bending fillet joint weld toe fatigue test method according to claim 9, characterized in that: The calibrating of the fatigue testing machine comprises: Ensure that the indenter of the fatigue testing machine and the bolts on the mounting base are on the loading center axis; Ensure that the indenter of the fatigue testing machine is at least 10 mm away from the weld toe on the T-type specimen.

11. The single-sided bending fillet joint weld toe fatigue test method according to claim 9, characterized in that: The method of obtaining the overall dimension data and weld dimension data of the T-type specimen and calculating the weld toe notch stress concentration factor includes: Laser scan the whole body and weld of the T-type specimen, and use 3D software to measure and statistically analyze the scanned model of the T-type specimen to obtain the overall size data and weld size data of the T-type specimen; The metrology software is used to statistically analyze the weld size and weld toe arc radius in the three-dimensional model of the T-type specimen exported by the three-dimensional software, and the statistical analysis results are calculated by the finite element method to obtain the maximum stress of the weld toe notch; The weld toe notch stress intensity factor is calculated according to the maximum stress of the weld toe notch, and the weld toe notch stress concentration factor is calculated based on the weld toe notch stress intensity factor.

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