Method and device for testing high-cycle fatigue life of thin-wall sinking locking structure

Abstract

The invention discloses a high-cycle fatigue life test method and device for a thin-wall sinking locking structure, relates to the technical field of thin-wall sinking locking structures, and aims to solve the problems that a mechanical property test method for a locking structure after severe plastic deformation is lacked at present, and a test piece adopted by an existing thin-wall test is extremely easy to break. The method comprises the following steps: acquiring a first target loading load and a second target loading load of a test piece; the test piece is of a cantilever beam type structure; based on the first target loading load, the test device is adopted to carry out initial plastic strain force loading treatment on the test piece, and a target test piece is obtained; and performing a high-cycle fatigue test on the test piece by using the test device based on the second target loading load. The test piece adopted by the high-cycle fatigue life test method for the thin-wall sinking locking structure is not easy to break, and the fatigue life test of the locking structure after severe plastic deformation can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin-wall impact locking structure, and particularly relates to a high-cycle fatigue life test method and device for thin-wall impact locking structure. BACKGROUND

[0002] A large number of anti-loose locking parts are used in engine turbine assemblies to assemble and lock fasteners, seals and other structures. In the assembly process, local locking structures will produce large plastic deformation. In the working state of the engine, the structure is not only subjected to mechanical vibration load, but also subjected to fluid excitation force generated by medium pulsation. Under the action of these vibration loads, the structure has the risk of fatigue failure, which seriously affects the service safety of the turbine pump and the engine. Therefore, it is necessary to carry out detailed evaluation on the fatigue life of such structures.

[0003] At present, there is no performance test method for locking structures after large plastic deformation, and the test is difficult to control the plastic strain size in the test, and the test piece is prone to fracture when the conventional thin plate fatigue test method is used for testing due to the large plastic strain.

[0004] Therefore, there is an urgent need for a high-cycle fatigue life test method and device for thin-wall impact locking structure. SUMMARY

[0005] The present application aims to provide a high-cycle fatigue life test method and device for thin-wall impact locking structure, to solve the problems of lack of mechanical performance test method for locking structures after large plastic deformation, and easy fracture of test pieces used in existing thin-wall tests.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] In a first aspect, the present application provides a high-cycle fatigue life test method for thin-wall impact locking structure, comprising:

[0008] Obtaining a first target loading load and a second target loading load of a test piece; the test piece is a cantilever beam structure, the cantilever beam structure comprises a fixed block and a cantilever structure installed on the side surface of the fixed block and flush with the upper surface of the fixed block, the thickness of the cantilever structure is the same as the thickness of the thin-wall structure of the target locking structure;

[0009] Based on the first target loading load, the test device is used to perform initial plastic strain force loading treatment on the test piece to obtain a target test piece; the first target loading load makes the cantilever structure close to the fixed block;

[0010] Based on the second target loading load, the test device is used to perform high cycle fatigue test on the test piece; the second target loading load makes the cantilever structure away from the fixed block.

[0011] Optionally, the test piece further comprises an evaluation component; the evaluation component is a structure arranged at the connection between the fixed block and the cantilever structure, the evaluation component is a rounded corner structure, the fixed block is integrally formed with the cantilever structure, the fixed block is a cubic structure, and a first through hole penetrating through the fixed block is arranged along the height direction of the fixed block; the upper and lower surfaces of the cantilever structure are both provided with a limiting boss, and the limiting boss is arranged at one end away from the fixed block.

[0012] Optionally, the test device comprises a fixed clamp and a loading end head, the fixed clamp comprises a first clamping rod with external threads and a support structure, the first clamping rod is a cylindrical structure, the longitudinal section of the support structure is L-shaped, the support structure comprises a cylindrical base and a semicylindrical protrusion arranged at one axial end of the cylindrical base, the semicylindrical protrusion is provided with a fixed clamping groove penetrating through the semicylindrical protrusion along the axial direction perpendicular to the semicylindrical protrusion, the size of the end face of the fixed clamping groove is the same as that of one surface of the fixed block connected with the cantilever structure, a second through hole penetrating through the semicylindrical protrusion and communicating with the fixed clamping groove is arranged along the axial direction of the semicylindrical protrusion, and the diameter of the second through hole is the same as that of the first through hole; the loading end head comprises a second clamping rod with external threads and a pressure head, and the second clamping rod and the pressure head are connected in T shape.

[0013] Optionally, based on the first target loading load, the test device is used to perform initial plastic strain force loading treatment on the test piece to obtain a target test piece, and the method further comprises the following steps:

[0014] The test piece is placed in the fixed clamping groove, and the test piece and the fixed clamp are fixed by bolts, so that the upper surface of the cantilever structure of the test piece is flush with the upper surface of the fixed clamping groove;

[0015] The fixed clamp is fixed into the fixed end chuck of the testing machine through the first clamping rod;

[0016] The loading end head is fixed into the loading end chuck of the testing machine through the second clamping rod, so that the pressure head contacts the upper surface of the cantilever structure, and the pressure head is parallel to the cantilever structure, and the installation of the test device is completed.

[0017] Optionally, the first target loading load is displacement, and based on the first target loading load, the test device is used to perform initial plastic strain force loading treatment on the test piece to obtain a target test piece, and the method further comprises the following steps:

[0018] The loading end head is controlled to move downward at a constant speed by the testing machine until the displacement reaches the first target loading load, the loading end head is controlled to move upward at a constant speed until the pressure head is separated from the cantilever structure and stopped, and the target test piece is obtained.

[0019] Optionally, the second target loading load is displacement, and the high-cycle fatigue test of the test piece by the testing device based on the second target loading load comprises:

[0020] The target test piece is inverted by 180° in the testing device, the upper surface of the cantilever structure is flush with the lower surface of the fixed clamping groove, and the target test piece is fixed with the fixed clamp;

[0021] The loading end head is fixed to the loading end chuck of the testing machine through the clamping rod, and the pressure head is kept in contact with and parallel to the lower surface of the cantilever structure of the target test piece;

[0022] The loading end head is controlled to move downward at a constant speed by the testing machine until the displacement reaches the second target loading load, the loading end head is controlled to move upward at a constant speed until the pressure head is separated from the cantilever structure, and one fatigue test is completed;

[0023] The fatigue test is performed in cycles according to a preset loading frequency until the test piece is fractured, and the high-cycle fatigue test is completed.

[0024] Optionally, the first target loading load and the second target loading load of the test piece are obtained by:

[0025] The test piece of the testing device is simulated in two opposite compression bending processes by numerical simulation, and simulation data is obtained;

[0026] The first target loading load and the second target loading load applied to the test piece are determined based on the simulation data and the target plastic stress.

[0027] Optionally, the test piece of the testing device is simulated in two opposite compression bending processes by numerical simulation, and simulation data is obtained by:

[0028] A numerical model of the testing device is constructed;

[0029] Based on the numerical model, the cantilever structure is loaded according to a first preset displacement, a compression bending process of the cantilever structure is simulated, and a first relationship curve between the plastic strain of the test piece and the compression displacement of the cantilever structure is obtained.

[0030] Based on the numerical model, the cantilever structure is reversely loaded according to a second preset displacement, a reverse compression upward bending process of the cantilever structure is simulated, and a second relationship curve between plastic strain of the test component and reverse compression displacement of the cantilever structure is obtained.

[0031] Optionally, the target locking structure comprises a ring-shaped cylinder and a thin-walled structure integrally formed with the ring-shaped cylinder, the thin-walled structure is an annular structure, the thin-walled structure is arranged at one end of the ring-shaped cylinder in the axial direction, the inner ring diameter of the thin-walled structure is the same as the outer ring diameter of the ring-shaped cylinder, a connecting component is arranged at the connection between the thin-walled structure and the outer side surface of the ring-shaped cylinder, the connecting component is a fillet structure, the connecting component is arranged along the circumferential direction of the ring-shaped cylinder, and the fillet radius of the test component is the same as the fillet radius of the connecting component.

[0032] Compared with the prior art, the high-cycle fatigue life test method of the thin-walled impact locking structure provided by the application comprises the following steps: obtaining a first target loading load and a second target loading load; based on the first target loading load, an initial plastic strain force loading process is performed on the test piece by using a test device to obtain a target test piece; the first target loading load makes the cantilever structure close to the fixed block; based on the second target loading load, a high-cycle fatigue test is performed on the test piece by using the test device; and the second target loading load makes the cantilever structure away from the fixed block. The application can realize fatigue life testing of a structure after large plastic deformation, and provides support for the safety and reliability of the structure in service. The test piece using the cantilever beam structure utilizes local stress concentration to enable the test piece to satisfy large plastic stress without breaking, the cantilever structure can simulate the thin-walled structure of the target locking structure, and can accurately restore the state of one end fixed and one end stressed of the target locking structure in actual use; the test piece is first subjected to the initial plastic strain force loading process, which can simulate the plastic deformation of the target locking structure during assembly, and can ensure the effectiveness of the test data; and the high-cycle fatigue life test is performed on this basis, and the test is more accurate.

[0033] In a second aspect, the application further provides a high-cycle fatigue life test device for a thin-walled impact locking structure, which is applied to the high-cycle fatigue life test method of the thin-walled impact locking structure, and comprises at least a test piece, wherein the test piece is a cantilever beam structure, the cantilever beam structure comprises a fixed block and a cantilever structure mounted on the side surface of the fixed block and flush with the upper surface of the fixed block, and the thickness of the cantilever structure is the same as the thickness of the thin-walled structure of the target locking structure.

[0034] The test device is used for performing the initial plastic strain force loading process on the test piece and performing the high-cycle fatigue test on the test piece.

[0035] Compared with the prior art, the high-cycle fatigue life test device for the thin-wall impact locking structure has the same beneficial effects as the high-cycle fatigue life test method for the thin-wall impact locking structure, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0037] Figure 1 A structure schematic view of the target locking structure provided by the application;

[0038] Figure 2 A structure schematic view of a test piece of the high-cycle fatigue life test device for the thin-wall impact locking structure provided by the application;

[0039] Figure 3 A structure schematic view of the fixing clamp provided by the application;

[0040] Figure 4 A structure schematic view of the loading end provided by the application;

[0041] Figure 5 A flow chart of the high-cycle fatigue life test method for the thin-wall impact locking structure provided by the application;

[0042] Figure 6 A loading schematic view of the test device in the initial plastic strain force loading process of the test piece provided by the application;

[0043] Figure 7 A loading schematic view of the test device for the high-cycle fatigue test provided by the application.

[0044] LIST OF REFERENCES:

[0045] 11-thin-wall structure, 12-connecting part, 13-annular cylinder, 21-fixing block, 211-first through hole, 22-cantilever structure, 221-limiting protrusion, 23-evaluation part, 31-first clamping rod, 32-supporting structure, 321-cylinder base, 322-semi-cylinder protrusion, 323-fixing clamping groove, 324-second through hole, 41-second clamping rod, 42-press head. DETAILED DESCRIPTION

[0046] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the terms "first", "second", etc. are used to distinguish the same or similar items with basically the same function and role. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and the order is not limited. Those skilled in the art can understand that the terms "first", "second", etc. do not limit the quantity and execution order, and the terms "first", "second", etc. also do not necessarily mean different.

[0047] It should be noted that in the present application, the words "exemplary" or "for example" are used to mean serving as an example, instance, or illustration. Any embodiment or design described as "exemplary" or "for example" in the present application should not be construed as being more preferred or advantageous than other embodiments or designs. Rather, the use of the words "exemplary" or "for example" is intended to present concepts in a particular manner.

[0048] In the present application, "at least one" means one or more, and "multiple" means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can represent: a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0049] After large plastic deformation, the tensile, fatigue and other mechanical properties of the thin-walled locking structure will change, resulting in a lack of relevant performance data when evaluating the fatigue life of the structure, and the results evaluated by using general performance data have large errors. Currently, there is no corresponding standard specification for testing the performance of materials after large plastic deformation, and most of the design testing relies on engineering experience. For some simple tests, traditional test pieces can meet the requirements, but for some tests under complex conditions, the conventional test method is no longer applicable, and new test structures and test methods need to be considered for testing.

[0050] The locking structure widely used in the turbine pump assembly will produce large plastic deformation in the assembly process, and the deformation has significant tension-compression asymmetry, so that the structure has a large strain gradient, and the local plastic strain is close to or even exceeds the elongation at break of the material. When analyzing and evaluating the fatigue life of the structure in this state, the effectiveness of the test data can be ensured by introducing the same initial plastic strain when testing the material fatigue performance, but when using the conventional thin plate fatigue test method for testing, there are problems such as uncontrollable plastic strain size and easy fracture of the test piece due to excessive plastic strain, which brings great trouble to the test.

[0051] To solve the above problems, the present application provides a high-cycle fatigue life test method and device for thin-wall impact locking structure, which designs a test piece capable of conducting fatigue test after large plastic deformation, and conducts high-cycle fatigue life test of the structure after large plastic deformation through the corresponding test method, thereby providing support for the safety and reliability of the structure in service. Next, the description will be made in combination with the drawings.

[0052] Referring to Figure 1 , the target locking structure is a thin-wall impact locking structure, the target locking structure comprises an annular cylinder 13 and a thin-wall structure 11 integrally formed with the annular cylinder 13, the thin-wall structure 11 is an annular structure, the thin-wall structure 11 is arranged at one end of the annular cylinder 13 in the axial direction, the inner ring diameter of the thin-wall structure 11 is the same as the outer ring diameter of the annular cylinder 13, a connecting component 12 is arranged at the connection between the thin-wall structure 11 and the outer side surface of the annular cylinder 13, the connecting component 12 is a rounded corner structure, and the connecting component 12 is arranged along the circumferential direction of the annular cylinder 13.

[0053] Referring to Figures 2-4 , the high-cycle fatigue life test device for the thin-wall impact locking structure provided by the present application comprises a test piece, a fixed clamp and a loading end, as shown in Figure 2 (a), the test piece is a cantilever beam structure, the cantilever beam structure comprises a fixed block 21 and a cantilever structure 22 installed on the side surface of the fixed block 21 and flush with the upper surface of the fixed block 21, the fixed block 21 and the cantilever structure 22 are integrally formed, the fixed block 21 is a cubic structure, a first through hole 211 penetrating through the fixed block 21 is arranged along the height direction of the fixed block 21, the first through hole 211 is a threaded hole, a limiting protrusion 221 is arranged at the end of the cantilever structure 22 away from the fixed block 21, and the limiting protrusion 221 comprises a protrusion arranged on the upper surface of the cantilever structure and a protrusion arranged on the lower surface of the cantilever structure. The thickness of the cantilever structure 22 is the same as the thickness of the thin-wall structure 11 of the target locking structure; as Figure 2(b) as shown, the test piece further comprises an evaluation component 23, which is a structure arranged at the joint of the fixed block 21 and the cantilever structure 22, the evaluation component 23 is a rounded structure, and the length of the evaluation component is the same as that of the cantilever structure. The rounded radius of the evaluation component is the same as that of the connecting component of the target locking structure. The cantilever structure is used to bear the initial plastic strain load and the fatigue load and to transfer the load to the evaluation component, and the limiting boss is used for load limiting and preventing the test piece from slipping during the test. It should be noted that the upper surface of the fixed block, the upper surface and the lower surface of the cantilever structure are the corresponding upper surface and lower surface of the test piece according to Figure 2 (a) as shown.

[0054] In actual application, the test piece is integrally manufactured, the cantilever structure is machined at the right side of the fixed end, the upper and lower surfaces of the cantilever structure are machined, the limiting boss is left at the right end of the fixed end, the lower surface of the joint of the cantilever structure and the fixed end is rounded, the evaluation component is machined, and the first through hole penetrating through the upper and lower surfaces of the fixed end is machined at the center of the fixed end, which is used for fixing with the fixed clamp.

[0055] As shown in Figure 3 , the fixed clamp comprises a support structure 32 and a first clamping rod 31 with external threads, the first clamping rod 31 is a cylindrical structure, the longitudinal section of the support structure 32 is L-shaped, the support structure 32 comprises a cylindrical base 321 and a semicircular cylindrical protrusion 322 arranged at one end of the axial direction of the cylindrical base 321, the first clamping rod 31 is arranged at the other end of the axial direction of the cylindrical base 321, and the surface of the cylindrical base 321 away from the first clamping rod 31 is a test area except the area of the semicircular cylindrical protrusion 322, which is used to provide a test space for the initial plastic strain force loading process and high-cycle fatigue test. The semicircular cylindrical protrusion 322 is provided with a fixed clamping groove 323 penetrating through the semicircular cylindrical protrusion 322 in the first direction, the fixed clamping groove is used to install the test piece, the first direction is the direction perpendicular to the axial direction of the semicircular cylindrical protrusion, the size of the end face of the fixed clamping groove 323 is the same as that of the surface of the fixed block connected with the cantilever structure 22, and the semicircular cylindrical protrusion 322 is further provided with a second through hole 324 penetrating through the semicircular cylindrical protrusion in the second direction and communicating with the fixed clamping groove 323, the second direction is the axial direction of the semicircular cylindrical protrusion, the diameter of the second through hole 324 is the same as that of the first through hole 211, and the two form a corresponding relationship, and the test piece and the fixed clamp are fixed by bolts.

[0056] As shown in Figure 4 , the loading end head comprises a second clamping rod 41 with external threads and a pressure head 42, the second clamping rod 41 and the pressure head 42 are connected in T shape, and the loading end head can be two cylindrical bodies welded together.

[0057] In the structure, the first clamping rod and the support are connected by welding, and the support part is integrally processed and manufactured. The fixing clamp is used for clamping and fixing the test piece during the test, the loading end is used for loading during the test, a certain space size is reserved in the fixing clamp for clamping and testing the test piece, and the fixing clamp can adapt to the loading mode of the commonly used fatigue test device. The pressure head is used for applying initial plastic strain load and fatigue load

[0058] The test device is used for initial plastic strain force loading treatment of the test piece and high-cycle fatigue test of the test piece.

[0059] Referring to Figure 5 The application also provides a high-cycle fatigue life test method of the thin-wall collapse locking structure, which is realized by the high-cycle fatigue life test of the thin-wall collapse locking structure. The test method comprises the following steps:

[0060] Step 100: obtaining a first target loading load and a second target loading load of the test piece;

[0061] The test piece is a cantilever beam structure, which comprises a fixed block and a cantilever structure installed on the side surface of the fixed block and flush with the upper surface of the fixed block. The thickness of the cantilever structure is the same as that of the thin-wall structure of the target locking structure.

[0062] As an optional mode, step 100 can be realized based on the following steps:

[0063] Step 110: simulating the compression bending process of the test piece of the test device in two opposite directions by using numerical simulation to obtain simulation data;

[0064] Specifically, a numerical model of the test device is constructed by using a finite element software. The numerical model is a finite element model. The simulation process of the compression bending of the cantilever structure is as follows: based on the numerical model, the cantilever structure is loaded according to a first preset displacement to simulate the compression bending process of the cantilever structure, and a first relationship curve between the plastic strain of the test piece and the compression displacement of the cantilever structure is obtained. The compression displacement of the cantilever structure is the first preset displacement of the loading, and the loading process is as follows: slowly press the cantilever structure downward until the first preset displacement is reached, and the plastic strain force of the test piece at this time is measured. The first preset displacement comprises a plurality of preset displacements, and the cantilever structure is loaded in turn to obtain the plastic strain force data corresponding to each first preset displacement. The first relationship curve is obtained by curve fitting based on the first preset displacement and the plastic strain force data.

[0065] The simulation process of cantilever structure bending upward under compression is as follows: Based on the numerical model, the cantilever structure is subjected to reverse loading according to a second preset displacement to simulate the upward bending process of the cantilever structure under reverse compression, and the second relationship curve between the plastic strain of the test component and the reverse compression displacement of the cantilever structure is obtained. The fitting formula can be any formula with suitable fit.

[0066] The reverse compressive displacement of the cantilever structure is the second preset displacement applied to it. The loading process is as follows: the cantilever structure is slowly pressed upwards until the second preset displacement is reached, and the plastic strain force of the component under test is measured at this point. The second preset displacement includes multiple preset displacements. The cantilever structure is loaded sequentially, and the plastic strain force data corresponding to each second preset displacement is obtained. Based on the second preset displacements and the plastic strain force data, curve fitting is performed to obtain the second relationship curve. The fitting formula can be a quadratic polynomial equation or other formulas with suitable fit.

[0067] In practical applications, since numerical simulation is performed using finite element software, it is only necessary to change the direction of the load applied to the cantilever structure, without changing the direction of the cantilever structure in the test piece.

[0068] Step 120: Determine the first target loading load and the second target loading load to be applied to the test specimen based on the simulation data and the target plastic stress.

[0069] Specifically, the target plastic stress is substituted into the equation corresponding to the first relationship curve to obtain the first target loading load, and the target plastic stress is substituted into the equation corresponding to the second relationship curve to obtain the second target loading load. Both the first and second target loading loads can be either displacement loading or force loading.

[0070] In practical applications, the testing device needs to be assembled before the initial plastic strain loading treatment of the test specimen. Specifically: the test specimen is placed in the fixed slot, and the test specimen and the fixed fixture are fixed by bolts passing through the second through hole and the first through hole, so that the upper surface of the cantilever structure of the test specimen is flush with the upper surface of the fixed slot; the fixed fixture is fixed to the fixed end chuck of the testing machine by the first clamping rod; the loading end head is fixed to the loading end chuck of the testing machine by the second clamping rod, so that the pressure head contacts the upper surface of the cantilever structure and the pressure head is parallel to the cantilever structure, thus completing the installation of the testing device.

[0071] Step 200: Based on the first target loading load, the test piece is subjected to initial plastic strain loading using a test device to obtain the target test piece; the first target loading load brings the cantilever structure close to the fixed block;

[0072] like Figure 6As shown, step 200 specifically includes: controlling the loading end head to move downwards at a uniform speed using the testing machine, causing the cantilever structure to bend downwards under pressure, and the cantilever structure to transfer force to the test component until the displacement reaches the first target loading load; then controlling the loading end head to move upwards at a uniform speed until the pressure head separates from the cantilever structure and stops, thus obtaining the target test piece. The target test piece is then separated from the fixing fixture by removing the bolts, completing the introduction of initial plastic strain.

[0073] Step 300: Based on the second target loading load, the test device is used to conduct a high-cycle fatigue test on the test piece; the second target loading load moves the cantilever structure away from the fixed block.

[0074] Step 300 specifically includes: rotating the target test piece 180° in the testing device so that the upper surface of the cantilever structure is flush with the lower surface of the fixing slot, and fixing the target test piece to the fixing clamp. The testing device after installation is as follows: Figure 7 As shown; the loading end is fixed to the loading end clamp of the testing machine by the clamping rod, and the indenter is kept in contact with and parallel to the lower surface of the cantilever structure of the target test piece; the loading end is controlled by the testing machine to move downward at a uniform speed until the applied displacement reaches the second target loading load, and the loading end is controlled to move upward at a uniform speed until the indenter separates from the cantilever structure, completing one fatigue test; the fatigue test is repeated according to the preset loading frequency, that is, the steps of controlling the loading end to move downward at a uniform speed until the applied displacement reaches the second target loading load, controlling the loading end to move upward at a uniform speed until the indenter separates from the cantilever structure are repeated until the cantilever structure of the test piece fractures, completing the high-cycle fatigue test.

[0075] As can be seen from the above structure and method, this application ensures the validity of test data by introducing a uniformly distributed initial plastic strain. The magnitude of the applied load is obtained more accurately and conveniently through numerical simulation. The initial plastic strain introduction and fatigue load loading can be realized by using a fixed fixture and a loading end, thereby realizing the fatigue life test of the structure after large plastic deformation, providing support for the safety and reliability of the structure in service. Among them, the test piece of this application adopts a cantilever beam structure, which utilizes local stress concentration to enable the test piece to meet large plastic stress without fracture. The cantilever structure can simulate the thin-walled structure of the target locking structure, and accurately reproduce the state of the target locking structure in actual use where one end is fixed and the other end is stressed. Furthermore, the test piece is first subjected to initial plastic strain loading treatment, which can simulate the plastic deformation experienced by the target locking structure during assembly, ensuring the validity of the test data. On this basis, high-cycle fatigue life test is carried out, and the test is more accurate.

[0076] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0077] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A high-cycle fatigue life test method for a thin-walled stamping locking structure, characterized in that, include: Obtain the first and second target loading loads on the test specimen; The test piece is a cantilever beam structure, which includes a fixed block and a cantilever structure installed on the side of the fixed block and flush with the upper surface of the fixed block. The thickness of the cantilever structure is the same as the thickness of the thin-walled structure of the target locking structure. Based on the first target loading load, the test piece is subjected to initial plastic strain loading using a test device to obtain the target test piece; the first target loading load brings the cantilever structure closer to the fixed block; Based on the second target loading load, the test device is used to conduct a high-cycle fatigue test on the test piece; the second target loading load moves the cantilever structure away from the fixed block.

2. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 1, characterized in that, The test piece also includes an assessment component; the assessment component is a structure disposed at the connection between the fixed block and the cantilever structure, the assessment component is a rounded corner structure, the fixed block and the cantilever structure are integrally formed, the fixed block is a cubic structure, and a first through hole is provided along the height direction of the fixed block; a limit protrusion is provided at the end of the cantilever structure away from the fixed block.

3. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 2, characterized in that, The testing apparatus includes a fixing fixture and a loading end. The fixing fixture includes a first clamping rod with external threads and a support structure. The first clamping rod is a cylindrical structure. The longitudinal section of the support structure is L-shaped. The support structure includes a cylindrical base and a semi-cylindrical protrusion disposed at one axial end of the cylindrical base. The semi-cylindrical protrusion is provided with a fixing groove that penetrates the semi-cylindrical protrusion in a direction perpendicular to the axial direction of the semi-cylindrical protrusion. The size of the end face of the fixing groove is the same as the size of the side of the fixing block connected to the cantilever structure. A second through hole is provided in the axial direction of the semi-cylindrical protrusion that penetrates the semi-cylindrical protrusion and communicates with the fixing groove. The diameter of the second through hole is the same as that of the first through hole. The loading end includes a second clamping rod with external threads and a pressure head. The second clamping rod and the pressure head are connected in a T-shape.

4. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 3, characterized in that, The process of applying initial plastic strain force to the test specimen using a testing device based on the first target loading load to obtain the target test specimen further includes: The test piece is placed in the fixing slot, and the test piece and the fixing fixture are fixed with bolts so that the upper surface of the cantilever structure of the test piece is flush with the upper surface of the fixing slot. The fixing fixture is fixed to the fixed end chuck of the testing machine by means of the first clamping rod; The loading end is fixed to the loading end clamp of the testing machine by the second clamping rod, so that the pressure head contacts the upper surface of the cantilever structure and the pressure head is parallel to the cantilever structure, thus completing the installation of the testing device.

5. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 4, characterized in that, The first target loading load is displacement. The initial plastic strain loading treatment of the test specimen using a testing device based on the first target loading load to obtain the target test specimen includes: The loading end is controlled by the testing machine to move downward at a constant speed until the displacement reaches the first target loading load. Then, the loading end is controlled to move upward at a constant speed until the pressure head separates from the cantilever structure and stops, thus obtaining the target test piece.

6. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 4, characterized in that, The second target load is displacement. Based on the second target load, the high-cycle fatigue test of the test piece using the test apparatus includes: In the test apparatus, the target test piece is rotated 180° so that the upper surface of the cantilever structure is flush with the lower surface of the fixing slot, and the target test piece is fixed to the fixing fixture. The loading end head is fixed to the loading end chuck of the testing machine by the clamping rod, and the pressure head is kept in contact with and parallel to the lower surface of the cantilever structure of the target test piece; The loading end is controlled to move downward at a constant speed by the testing machine until the displacement reaches the second target loading load. Then, the loading end is controlled to move upward at a constant speed until the pressure head separates from the cantilever structure, thus completing one fatigue test. The fatigue test is performed cyclically according to a preset loading frequency until the test piece fractures, thus completing the high-cycle fatigue test.

7. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 1, characterized in that, The acquisition of the first and second target loading loads of the test specimen includes: Numerical simulation was used to simulate two opposing compressive bending processes on the test piece of the test device to obtain simulation data; Based on the simulation data and the target plastic stress, the first target loading load and the second target loading load are determined on the test specimen.

8. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 7, characterized in that, The numerical simulation method was used to simulate two opposing compressive bending processes on the test piece of the test device, and the simulation data obtained included: Construct a numerical model of the experimental setup; Based on the numerical model, the cantilever structure is loaded according to the first preset displacement to simulate the downward bending process of the cantilever structure under pressure, and the first relationship curve between the plastic strain of the test component and the compressive displacement of the cantilever structure is obtained. Based on the numerical model, the cantilever structure is subjected to reverse loading according to the second preset displacement to simulate the upward bending process of the cantilever structure under reverse pressure, and a second relationship curve between the plastic strain of the test component and the reverse pressure displacement of the cantilever structure is obtained.

9. The high-cycle fatigue life test method for the thin-walled stamping locking structure according to claim 2, characterized in that, The target locking structure includes an annular cylinder and a thin-walled structure integrally formed with the annular cylinder. The thin-walled structure is annular and is located at one end of the annular cylinder along its axial direction. The inner diameter of the thin-walled structure is the same as the outer diameter of the annular cylinder. A connecting component is provided at the connection between the thin-walled structure and the outer surface of the annular cylinder. The connecting component has a rounded corner structure and is arranged along the circumference of the annular cylinder. The rounded radius of the testing component is the same as the rounded radius of the connecting component.

10. A high-cycle fatigue life testing apparatus for a thin-walled stamped locking structure, applied to the high-cycle fatigue life testing method for the thin-walled stamped locking structure according to any one of claims 1-9, characterized in that, The test apparatus includes at least: a test piece, which is a cantilever beam structure, the cantilever beam structure including a fixed block and a cantilever structure mounted on the side of the fixed block and flush with the upper surface of the fixed block, the thickness of the cantilever structure being the same as the thickness of the thin-walled structure of the target locking structure; The testing apparatus is used to perform initial plastic strain loading on the test specimen and to conduct high-cycle fatigue tests on the test specimen.

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