Specimen, tooling and method for z-direction fatigue testing of explosive bonded joints

Abstract

The present application relates to the field of metal composite plate explosion welding, and provides a sample, a tool and a method for Z-direction fatigue test of an explosion composite joint, the sample comprising at least a top layer and a bottom layer, and the sample comprising at least one interface, the sample comprising: a circumferential boss part composed of an upper part of the top layer; a central column part arranged below the circumferential boss part, the central column part comprising at least a lower part of the top layer and the bottom layer; a tapered transition part arranged between the circumferential boss part and the central column part; an upper central through hole opened downward from the top of the sample and extending to below the interface to be tested by more than 1mm; and a lower central through hole in communication with the upper central through hole. The sample for Z-direction fatigue test of the explosion composite joint, one, controls the fatigue failure surface at the interface, and realizes accurate determination of the Z-direction fatigue performance of the explosion composite joint; two, does not easily cause interface fracture during installation; and three, can satisfy tensile-tensile fatigue, tensile-compressive fatigue and compressive-compressive fatigue tests.

Description

Technical Field

[0001] This invention relates to the field of explosive welding of metal composite plates, and more specifically, to a specimen, tooling and method for Z-axis fatigue testing of explosive composite joints. Background Technology

[0002] Ships navigate the undulating ocean year-round, subjected to repeated alternating stresses. Therefore, designers and builders require high fatigue resistance in explosive composite joints to prevent fatigue damage. Neither current Chinese standards nor Japanese LWSB8102 specify fatigue performance requirements for transition joints. Explosive composite joints are currently typically tested for Z-axis fatigue using the welded fin type as specified in MIL-J-24445A "Military Standard for Aluminum-Steel Transition Joints." Fatigue specimens for aluminum-steel welded components are shown in [reference needed]. Figure 1 and Figure 2 An aluminum connecting plate 811 is welded to one side of the aluminum-steel transition joint 81, and a steel connecting plate 812 is welded to the other side. Current testing methods typically locate fatigue failure at the connection point between the joint and the aluminum connecting plate, failing to determine the fatigue performance of the joint itself and ultimately affecting material performance assessment.

[0003] Some domestic scholars have machined small-sized specimens by paralleling the thickness of the explosive composite joint. Since the thickness of the explosive composite joint is typically 19-32 mm, this results in small fatigue specimens and even smaller clamping ends. To facilitate testing, small-scale fatigue specimens, such as... Figure 3 and Figure 4 As shown, the specimen length L is 25~32mm, the specimen width b is 19~29mm, the specimen thickness is 0.5~2mm, and the width of the test area is 3~10mm. These specimens are small and have low interfacial bearing capacity, typically presenting two problems: first, during installation, if the clamping ends are not coaxial, interfacial fracture can easily occur, making it impossible to effectively evaluate fatigue performance; second, during testing, only tensile-tensile fatigue testing can be performed, not tensile-compressive fatigue testing, which cannot meet the requirements of actual working conditions in marine engineering.

[0004] In summary, the existing technology has the following disadvantages: First, the fatigue failure location is incorrect, usually at the connection between the joint and the aluminum connecting plate, and the fatigue performance of the joint body cannot be determined; Second, sample clamping and alignment are extremely difficult, and interface fracture is easily caused during installation, which cannot effectively evaluate fatigue performance; Third, it can only perform tensile fatigue testing and cannot carry out tensile-compression fatigue testing, which cannot meet the needs of actual working conditions in marine engineering.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a specimen and method for Z-axis fatigue testing of explosive composite joints, in order to overcome the shortcomings of the prior art: 1. The fatigue failure location is incorrect, usually at the connection between the joint and the aluminum connecting plate, and the fatigue performance of the joint body cannot be determined; 2. Specimen clamping and alignment are extremely difficult, and interface fracture is easily caused during installation; 3. Only tensile fatigue testing can be performed, and tensile-compression fatigue testing cannot be carried out, which cannot meet the needs of actual working conditions in marine engineering.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A specimen for Z-axis fatigue testing of an explosive composite joint, the specimen comprising, from top to bottom, at least a top layer and a bottom layer of metallurgical bonding, the specimen containing at least one interface, the specimen having a cup-shaped structure, and the specimen comprising:

[0009] The circumferential boss portion is formed by the upper part of the top layer;

[0010] A central column portion is disposed below the circumferential boss portion, and the central column portion includes at least the lower part of the top layer and the last layer;

[0011] A tapered transition portion is provided between the circumferential boss portion and the central column portion;

[0012] A central through hole is formed from the top of the sample downwards and extends more than 1 mm below the interface to be tested.

[0013] A lower central through hole is formed at the bottom of the sample and communicates with the upper central through hole. The diameter of the upper central through hole is larger than the diameter of the lower central through hole.

[0014] Furthermore, the taper of the tapered transition section is 1:2 to 1:10.

[0015] Furthermore, the taper of the tapered transition section is 1:5.

[0016] Furthermore, a plurality of radial connecting holes are provided through the circumferential boss portion, and the plurality of radial connecting holes are evenly arranged around the outer circumference of the upper central through hole.

[0017] Furthermore, one or more intermediate layers are provided between the top layer and the bottom layer.

[0018] In a second aspect, the present invention provides a fixture for Z-axis fatigue testing of an explosive composite joint, wherein the Z-axis fatigue testing fixture is used in conjunction with a fatigue testing machine to perform Z-axis fatigue testing on a specimen of an explosive composite joint as described in any one of the present invention, the Z-axis fatigue testing fixture comprising:

[0019] An upper mold is positioned above the sample;

[0020] The lower mold is positioned below the sample;

[0021] The upper central mold is installed in the upper central through hole;

[0022] A lower center mold is installed in a lower center through hole, and the lower center mold is connected to the upper center mold.

[0023] The first connecting member is used to pass through the upper mold, the circumferential boss and the lower mold in sequence to fix the sample in the Z-axis fatigue testing fixture;

[0024] A connecting component is installed below the lower mold;

[0025] During testing, the upper clamping assembly of the fatigue testing machine clamps the upper central mold, and the lower clamping assembly of the fatigue testing machine clamps the connecting assembly.

[0026] Furthermore, a receiving cavity is provided in the lower mold, and the central cylindrical part of the sample and the lower central mold are disposed in the receiving cavity. The lower central mold and the bottom of the receiving cavity are spaced apart, and the space is not less than 5 mm.

[0027] Furthermore, a clearance hole is provided at the center of the upper mold, the clearance hole being used to avoid the upper central mold.

[0028] Furthermore, an installation cavity is provided at the bottom center of the lower mold, and the connecting component cooperates with the installation cavity.

[0029] A third aspect of the present invention provides a method for Z-axis fatigue testing of an explosive composite joint, wherein the Z-axis fatigue testing method is performed using the tooling for Z-axis fatigue testing of an explosive composite joint as described in any one of the claims, in conjunction with a fatigue testing machine, and the Z-axis fatigue testing method includes the following steps:

[0030] S1. Obtain a sample from the explosive composite joint;

[0031] S2. Install the upper center mold of the Z-axis fatigue testing fixture in the upper center through hole, and install the lower center mold in the lower center through hole. The lower center mold is connected to the upper center mold.

[0032] S3. The upper mold is positioned above the sample, and the lower mold is positioned below the sample. The upper mold, the sample, and the lower mold are then connected together by the first connecting member.

[0033] S4. Install the connecting assembly below the lower mold to form the test assembly;

[0034] S5. Install the test component into the fatigue testing machine, wherein the upper clamping component of the fatigue testing machine clamps the upper central mold, and the lower clamping component clamps the connecting component;

[0035] S6. Control the Z-axis stress loading by controlling the fatigue testing machine until the specimen fails at the interface to be tested.

[0036] This invention proposes a specimen and method for Z-axis fatigue testing of explosive composite joints. Compared with the prior art, the specimen and method for Z-axis fatigue testing of explosive composite joints described in this invention have the following advantages:

[0037] 1. It can accurately guide the failure location, determine the fatigue performance of the joint body, control the fatigue failure surface at the interface, and ensure that the test results are accurate and effective.

[0038] Second, it can meet various fatigue testing requirements: it can not only perform tensile fatigue testing, but also conduct type tests such as tensile-compression fatigue and compressive-compression fatigue. The actual working conditions in marine engineering are complex and diverse, and explosive composite joints may be subjected to loads in different directions. This specimen can simulate various actual stress conditions, more comprehensively evaluate the fatigue performance of the joint, and provide a more reliable basis for engineering applications.

[0039] Third, it solves the problems of difficulty in centering small-sized specimens and the tendency for interface fracture to occur during clamping. During installation, the design of the upper and lower center through holes not only enables precise centering and ensures accurate load transmission along the Z-axis of the specimen, reducing the risk of interface fracture and effectively evaluating fatigue performance, but also achieves stable connection and secure installation, avoiding abnormal failures caused by eccentric loads.

[0040] Fourth, it can test explosive composite joints of different thicknesses.

[0041] Fifth, the method is convenient to clamp, easy to implement and promote, with a clear sample structure and mature processing technology. After the sample is combined with the matching Z-axis fatigue testing fixture, the clamping operation is simple, the positioning is fast and accurate, which effectively reduces the technical threshold for testing personnel, improves the overall testing efficiency, and is conducive to the standardization, promotion and application of this method. Attached Figure Description

[0042] Figure 1 This is a front view structural schematic diagram of a fatigue specimen of an aluminum-steel welded component as described in the prior art;

[0043] Figure 2 This is a side view of the fatigue specimen of the aluminum-steel welded part as described in the prior art.

[0044] Figure 3 This is a front view structural diagram of a small-scale fatigue specimen as described in the prior art;

[0045] Figure 4 This is a side view of the structure of a small-scale fatigue specimen as described in the prior art.

[0046] Figure 5 This is a top view of the specimen used for Z-axis fatigue testing of an explosive composite joint according to an embodiment of the present invention.

[0047] Figure 6 For along Figure 5 Schematic diagram of the cross-sectional structure of the mid-section AA;

[0048] Figure 7 This is a cross-sectional view of the specimen for Z-axis fatigue testing of an explosive composite joint according to an embodiment of the present invention, installed in a fatigue specimen fixture.

[0049] Explanation of reference numerals in the attached figures:

[0050] 1. Specimen; 11. Top layer; 12. Intermediate layer; 13. Last layer; 14. Upper central through hole; 15. Lower central through hole; 16. Circumferential boss; 161. Radial connecting hole; 17. Central column; 18. Conical transition section; 2. Lower mold; 21. Receiving cavity; 22. Protruding edge; 23. Mounting cavity; 3. Lower central mold; 4. Upper central mold; 5. Upper mold; 51. Clearance hole; 6. First connector; 7. Connecting assembly; 71. Second connector; 72. Third connector; 81. Aluminum-steel transition joint; 811. Aluminum connecting plate; 812. Steel connecting plate; 82. Small-scale fatigue specimen; 821. Test area. Detailed Implementation

[0051] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0052] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0053] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0056] Example 1

[0057] Fatigue test specimens of aluminum-steel welded parts are shown below. Figure 1 and Figure 2 ,like Figure 1 and Figure 2 As shown, an aluminum connecting plate 811 is welded to one side of the aluminum-steel transition joint 81, and a steel connecting plate 812 is welded to the other side of the aluminum-steel transition joint 81. Current testing methods typically locate fatigue failure at the connection point between the joint and the aluminum connecting plate 811, failing to determine the fatigue performance of the joint itself and ultimately affecting the material performance assessment.

[0058] 82 small-scale fatigue specimens are shown. Figure 3 and Figure 4 ,like Figure 3 and Figure 4 As shown, the length L of the small-scale fatigue specimen 82 is 25~32mm, the width b is 19~29mm, the thickness is 0.5~2mm, and the width of the test area 821 is 3~10mm. These specimens are small and have low interfacial bearing capacity, typically presenting two problems: first, during installation, if the clamping ends are not coaxial, interfacial fracture can easily occur, making it impossible to effectively evaluate fatigue performance; second, during testing, only tensile-tensile fatigue testing can be performed, not tensile-compressive fatigue testing, which cannot meet the requirements of actual working conditions in marine engineering.

[0059] The existing technology has the following disadvantages: First, the fatigue failure location is incorrect. The fatigue failure location is usually at the connection between the joint and the aluminum connecting plate 811, and the fatigue performance of the joint body cannot be determined. Second, the sample clamping and alignment are extremely difficult, which can easily lead to interface fracture and cannot effectively evaluate fatigue performance. Third, it can only perform tensile fatigue testing and cannot carry out tensile-compression fatigue testing, which cannot meet the needs of actual working conditions in marine engineering.

[0060] To address the aforementioned technical problems, in this embodiment, the applicant proposes a specimen for Z-axis fatigue testing of an explosive composite joint. The specimen 1, from top to bottom, comprises at least a metallurgically bonded top layer 11 and a bottom layer 13. The specimen 1 includes at least one interface. The specimen 1 has a cup-shaped structure, and its projection onto a vertical plane forms a T-shape. The specimen 1 includes:

[0061] The circumferential boss 16 is formed by the upper part of the top layer 11;

[0062] A central column portion 17 is disposed below the circumferential boss portion 16, and the central column portion 17 includes at least the lower part of the top layer 11 and the bottom layer 13.

[0063] A tapered transition portion 18 is disposed between the circumferential boss portion 16 and the central column portion 17;

[0064] The upper central through hole 14 is opened from the top of the sample 1 downward and extends more than 1 mm below the interface to be tested;

[0065] The lower central through hole 15 is opened upward at the bottom of the sample 1 and communicates with the upper central through hole 14. The diameter of the upper central through hole 14 is larger than the diameter of the lower central through hole 15.

[0066] The specimen for Z-axis fatigue testing of an explosive composite joint described in this embodiment has a cup-shaped structure. The projection of the specimen 1 onto the vertical plane forms a T-shape. This unique structure may have better mechanical property distribution and stress transmission characteristics in fatigue testing, which helps to more accurately reflect the fatigue performance of the explosive composite joint under actual working conditions.

[0067] The circumferential boss 16, formed by the upper part of the top layer 11, provides a stable and suitable clamping position for the specimen 1 during testing, facilitating installation and fixation. This allows the specimen 1 to be stably clamped by the testing machine fixtures, enabling it to withstand both tensile and compressive loads. Thus, fatigue testing under multiple load modes, including tension-tension, tension-compression, and compression-compression, is achieved for the first time. This comprehensively covers the complex stress state of ships under actual wave loads, enabling laboratory testing to realistically simulate and evaluate the fatigue behavior of the joint in service, providing significant guidance.

[0068] The tapered transition section 18 significantly reduces stress concentration at the clamping root, preventing premature fracture of the sample 1 at the clamping root and ensuring that the fatigue failure surface is at the interface of the explosive composite joint. This allows the test results to more accurately reflect the fatigue damage of the joint in actual use, improving the accuracy and reliability of the test.

[0069] The design of the upper central through hole 14 and the lower central through hole 15 makes the installation and operation of the sample 1 more convenient and faster, improving the testing efficiency. On the other hand, it forms a precisely aligned central loading axis, ensuring that the load is accurately transmitted along the Z-axis of the sample, fundamentally avoiding unexpected failures caused by clamping eccentricity or stress concentration, and greatly improving the accuracy, repeatability and reliability of the test data.

[0070] The upper central through hole 14 extends more than 1 mm below the interface to be tested, so that the fatigue failure surface is at the interface of the explosive composite joint, making the test results more accurately reflect the fatigue damage of the joint in actual use, and improving the accuracy and reliability of the test.

[0071] The specimen and method for Z-axis fatigue testing of an explosive composite joint described in this embodiment have the following beneficial effects:

[0072] 1. It can accurately guide the failure location, determine the fatigue performance of the joint body, control the fatigue failure surface at the interface, and ensure that the test results are accurate and effective.

[0073] Second, it can meet various fatigue testing requirements: it can not only perform tensile fatigue testing, but also conduct type tests such as tensile-compression fatigue and compressive-compression fatigue. The actual working conditions of marine engineering are complex and diverse, and explosive composite joints may be subjected to loads in different directions. This specimen 1 can simulate a variety of actual stress conditions, more comprehensively evaluate the fatigue performance of the joint, and provide a more reliable basis for engineering applications.

[0074] Third, it solves the problems of difficulty in centering small-sized specimens and easy interface fracture during clamping. During installation, the design of the upper center through hole 14 and the lower center through hole 15 can not only achieve precise centering and ensure that the load is accurately transmitted along the Z-axis of the specimen 1, making it less likely to cause interface fracture and effectively evaluate fatigue performance; it can also achieve stable connection and secure installation, avoiding abnormal failure caused by eccentric load.

[0075] Fourth, it can test explosive composite joints of different thicknesses.

[0076] V. The clamping is convenient and easy to implement and promote. The structure of Specimen 1 is clear and the processing technology is mature. After Specimen 1 is combined with the matching Z-axis fatigue testing fixture, the clamping operation is simple, the positioning is fast and accurate, which effectively reduces the technical threshold for testers, improves the overall testing efficiency, and is conducive to the standardization, promotion and application of this method.

[0077] In this embodiment, the sample 1 includes a metallurgically bonded top layer 11 and a bottom layer 13 from top to bottom. The sample 1 includes an interface, which is the interface between the top layer 11 and the bottom layer 13. The interface to be tested is the interface between the top layer 11 and the bottom layer 13.

[0078] Specifically, the upper central through hole 14 extends 1.5 mm below the interface between the top layer 11 and the bottom layer 13, that is, the depth of the upper central through hole 14 extending on the bottom layer 13 is 1.5 mm.

[0079] When all interfaces are to be tested, the upper central through hole 14 is opened from the top of the sample 1 downwards and extends to a depth greater than 1 mm on the last layer 13.

[0080] This setting ensures that the projected area of ​​all interfaces on the horizontal plane remains consistent. Therefore, under the same fatigue load, the interface with the weakest point is more prone to cracking. This allows for the simultaneous characterization of the fatigue performance of all interfaces and the determination of which interface has the weakest fatigue resistance.

[0081] In this embodiment, the diameter of the circumferential boss 16 is 60 mm, the width of the sample 1 is 60 mm, and the length of the sample 1 is 60 mm.

[0082] The thickness of the top layer 11 is 20 mm, the thickness of the bottom layer 13 is 10 mm, and the thickness of the sample 1 is 30 mm.

[0083] Specifically, the taper of the tapered transition portion 18 is 1:2 to 1:10.

[0084] This configuration most effectively achieves a smooth and continuous transition of stress flow lines from the circumferential boss portion 16 to the central column portion 17. It maximizes the elimination of stress concentration factors at the clamping root, reducing stress peaks to levels far below the interface fatigue strength. This ensures that fatigue cracks are precisely guided to the interface to be tested, thereby fundamentally solving the deficiency of existing technologies in evaluating the interface fatigue performance of the joint body, and achieving the core objective of this invention.

[0085] Preferably, the taper of the tapered transition portion 18 is 1:5.

[0086] The 1:5 taper strikes a perfect balance between completely eliminating stress concentration at the clamping root and maintaining the compactness and robustness of the main body structure of specimen 1. It can reliably prevent unexpected fractures at the clamping root or transition zone, while ensuring that the central column 17 has sufficient rigidity and load-bearing capacity to withstand fatigue loads of various modes, providing structural assurance for obtaining stable and highly repeatable effective test data.

[0087] The taper ratio of 1:5 means that for every 1 mm increase in the axial length of the tapered transition section 18, the diameter increases by 5 mm.

[0088] Specifically, a plurality of radial connecting holes 161 are provided through the circumferential boss portion 16, and the plurality of radial connecting holes 161 are evenly arranged around the outer circumference of the upper central through hole 14.

[0089] This design enhances the connection stability and balance between the specimen 1 and the tooling for Z-axis fatigue testing, ensuring that the specimen 1 will not loosen or shift during the test, thus guaranteeing the smooth progress of the test.

[0090] Furthermore, the number of radial connecting holes 161 is not specifically limited.

[0091] More specifically, such as Figure 5 As shown, in this embodiment, the number of radial connecting holes 161 is set to four, and the four radial connecting holes 161 are evenly arranged around the outer circumference of the upper central through hole 14.

[0092] In a second aspect of this embodiment, a tooling for Z-axis fatigue testing of explosive composite joints is provided, such as... Figure 7 As shown, the fixture, when used in conjunction with a fatigue testing machine, can perform Z-axis fatigue testing on specimen 1 of any of the explosive composite joints described in the present invention. The fixture includes:

[0093] The upper mold 5 is positioned above the sample 1;

[0094] The lower mold 2 is positioned below the sample 1;

[0095] The upper central mold 4 is installed in the upper central through hole 14;

[0096] The lower center mold 3 is installed in the lower center through hole 15, and the lower center mold 3 is connected to the upper center mold 4.

[0097] The first connecting piece 6 is used to pass through the upper mold 5, the circumferential boss 16 and the lower mold 2 in sequence to fix the sample 1 in the Z-direction fatigue testing fixture.

[0098] The connecting component 7 is installed below the lower mold 2;

[0099] During testing, the upper clamping assembly of the fatigue testing machine clamps the upper central mold 4, and the lower clamping assembly of the fatigue testing machine clamps the connecting assembly 7.

[0100] The tooling for Z-axis fatigue testing of an explosive composite joint described in this embodiment has the following advantages:

[0101] 1. Achieving absolutely precise axial alignment and load transfer: The upper center mold 4 and the lower center mold 3 are inserted into the upper center through hole 14 and the lower center through hole 15 of the specimen, respectively. The lower center mold 3 is connected to the upper center mold 4, naturally forming a rigid and absolutely aligned central loading axis. This ensures that the pure axial tensile or compressive force is directly and without eccentricity transferred to the central column part 17 of the specimen 1. This fundamentally avoids the additional bending moment caused by clamping eccentricity and prevents the specimen 1 from breaking prematurely at the non-test interface.

[0102] 2. It provides rigid and stable circumferential clamping to support tensile and compressive loads. The upper mold 5 and the lower mold 2 firmly clamp the circumferential boss 16 of the specimen 1 through the first connecting piece 6. This provides strong radial constraint and anti-torsional capacity. It provides stable lateral support for the specimen and prevents buckling of the central column part 17, making it possible to carry out compression fatigue testing and meeting the simulation requirements of actual working conditions such as wave impact on ship structures.

[0103] Third, it is highly modular and versatile, easy and reliable to operate, efficient, and easy to promote.

[0104] More specifically, such as Figure 7 As shown, a connecting groove is provided at the bottom center of the upper central mold 4, and a connecting column is provided at the top of the lower central mold 3. The connecting column is connected to the connecting groove.

[0105] On the one hand, achieving "automatic centering" and "precise positioning" ensures that the loading axis system composed of the upper center mold 4 and the lower center mold 3 has extremely high coaxiality, eliminating axis misalignment caused by manual installation deviations from a mechanical structure perspective. On the other hand, establishing a stable rigid connection ensures efficient load transfer. In addition, it can prevent mold separation and improve testing safety.

[0106] Specifically, such as Figure 7 As shown, a receiving cavity 21 is provided in the lower mold 2, and the central column part 17 of the sample 1 and the lower central mold 3 are disposed in the receiving cavity 21. The lower central mold 3 and the bottom of the receiving cavity 21 are spaced apart, and the space is not less than 5 mm.

[0107] Without this gap, the bottom of the lower center mold 3 would directly and violently impact the bottom of the receiving cavity 21 of the lower mold 2, generating a huge impact force. This impact would not only damage the precision lower center mold 3 or the bottom of the receiving cavity 21 of the lower mold 2; it would also accidentally transfer the impact load to the lower mold 2 and connecting assembly 7, potentially damaging the lower clamping assembly of the fatigue testing machine; this impact would also generate significant noise and vibration, posing a safety hazard. This gap of at least 5mm is a crucial safety buffer. This setting not only ensures that the load is transmitted only through the specimen 1 during compression testing, guaranteeing the accuracy and validity of the test results; it also prevents damage to the lower center mold 3, lower mold 2, connecting assembly 7, and the lower clamping assembly of the fatigue testing machine, extending their service life.

[0108] More specifically, in this embodiment, the interval is 10 mm.

[0109] Specifically, such as Figure 7 As shown, a clearance hole 51 is provided at the center of the upper mold 5, and the clearance hole 51 is used to avoid the upper central mold 4.

[0110] The clearance hole 51 allows the upper central mold 4 to transfer the tensile or compressive load applied by the upper clamping assembly of the fatigue testing machine directly to the connection inside the specimen 1 completely independently and vertically, without any interference from the upper mold 5.

[0111] Specifically, such as Figure 7 As shown, an installation cavity 23 is provided at the bottom center of the lower mold 2, and the connecting component 7 cooperates with the installation cavity 23.

[0112] More specifically, the connecting component 7 includes a second connecting member 71 and a third connecting member 72, wherein the second connecting member 71 is a bolt and the third connecting member 72 is a nut.

[0113] Specifically, such as Figure 7 As shown, a protruding edge 22 is provided below the lower mold 2.

[0114] In a third aspect of this embodiment, a method for Z-axis fatigue testing of an explosive composite joint is provided. The Z-axis fatigue testing method is performed using the tooling and fatigue testing machine described in any one of the embodiments of the present invention. The Z-axis fatigue testing method includes the following steps:

[0115] S1. Obtain sample 1 from the explosive composite joint;

[0116] S2. Install the upper center mold 4 of the Z-axis fatigue testing fixture in the upper center through hole 14, and install the lower center mold 3 in the lower center through hole 15. The lower center mold 3 is connected to the upper center mold 4.

[0117] S3. The upper mold 5 is positioned above the sample 1, and the lower mold 2 is positioned below the sample 1. The upper mold 5, sample 1, and lower mold 2 are then connected together by the first connecting member 6.

[0118] S4. Install the connecting component 7 below the lower mold 2 to form a test component;

[0119] S5. Install the test components into the fatigue testing machine, wherein the upper clamping component of the fatigue testing machine clamps the upper central mold 4, and the lower clamping component clamps the connecting component 7;

[0120] S6. Control the Z-axis stress loading by controlling the fatigue testing machine until the specimen 1 fails at the interface to be tested.

[0121] The Z-axis fatigue testing method for an explosive composite joint described in this embodiment has steps S1 to S6 that are interconnected and inseparable, and has the following advantages:

[0122] I. Simple to operate and highly efficient in testing.

[0123] Second, it ensures that each test measures the fatigue performance of the interface of the explosive composite joint body, thereby ensuring the validity of the data.

[0124] Third, it can meet a variety of fatigue test requirements: it can not only perform tensile fatigue tests, but also conduct tensile-compression fatigue, compressive-compression fatigue and other type tests.

[0125] Fourth, the method is highly versatile and can be used to test explosive composite joints of different thicknesses.

[0126] Fifth, it has a high success rate, is cost-effective, and is easy to standardize and promote.

[0127] Example 2

[0128] In this embodiment, unlike in Embodiment 1, specifically, as follows: Figure 6 As shown, an intermediate layer 12 is provided between the top layer 11 and the bottom layer 13.

[0129] like Figure 5 and Figure 6 As shown, the sample 1 consists of a metallurgically bonded top layer 11, a middle layer 12, and a bottom layer 13 from top to bottom.

[0130] The sample 1 includes two interfaces: the interface between the top layer 11 and the middle layer 12 is the first interface, and the interface between the middle layer 12 and the bottom layer 13 is the second interface.

[0131] When the interface to be tested is the first interface, the upper central through hole 14 is opened from the top of the sample 1 downwards, penetrates the top layer 11, and extends to 1.5mm below the first interface, that is, the depth of the upper central through hole 14 extending on the intermediate layer 12 is 1.5mm.

[0132] When the interface to be tested is the second interface, the upper central through-hole 14 is opened from the top of the sample 1 downwards, penetrates the top layer 11, and extends 1.5 mm below the second interface, that is, the depth of the upper central through-hole 14 extending on the last layer 13 is 1.5 mm. This setting can also characterize the first and second interfaces simultaneously. The 1.5 mm depth of the upper central through-hole 14 extending on the last layer 13 ensures that the projected areas of the first and second interfaces on the horizontal plane are consistent. Therefore, under the same fatigue load, the interface that is weakest is more prone to cracking. This allows for the simultaneous characterization of the fatigue performance of all interfaces and the determination of which interface is the weakest during fatigue.

[0133] Specifically, the top layer 11 is made of steel plate for ship hull structure, the middle layer 12 is made of industrial pure titanium, and the bottom layer 13 is made of aluminum-manganese alloy.

[0134] More specifically, in this embodiment, the top layer 11 is made of hull structure steel plate CCSB, and the thickness of the top layer 11 is 20mm; the middle layer 12 is made of industrial pure titanium TA1, and the thickness of the middle layer 12 is 2mm; the bottom layer 13 is made of aluminum manganese alloy 3003, and the thickness of the bottom layer 13 is 12mm; and the thickness of the sample 1 is 34mm.

[0135] This combination of material and thickness more realistically simulates the structure of actual multi-layer explosive composite joints, enabling a more accurate assessment of the fatigue life of such multi-layer explosive composite joints under simulated actual working conditions. This provides an important reference for the design, material selection, and use of joints in marine engineering.

[0136] Example 3

[0137] In this embodiment, unlike in embodiment 2, a two-layer intermediate layer 12 is provided between the top layer 11 and the bottom layer 13.

[0138] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A specimen for Z-axis fatigue testing of an explosive composite joint, wherein the specimen (1) comprises, from top to bottom, at least a metallurgically bonded top layer (11) and a bottom layer (13), and the specimen (1) contains at least one interface, characterized in that, The sample (1) has a cup-shaped structure and includes: The circumferential boss (16) is formed by the upper part of the top layer (11); The central column portion (17) is disposed below the circumferential boss portion (16), and the central column portion (17) includes at least the lower part of the top layer (11) and the bottom layer (13). A tapered transition portion (18) is provided between the circumferential boss portion (16) and the central column portion (17); The upper central through hole (14) is opened downward from the top of the sample (1) and extends more than 1 mm below the interface to be tested; The lower central through hole (15) is opened upward at the bottom of the sample (1) and communicates with the upper central through hole (14). The diameter of the upper central through hole (14) is larger than the diameter of the lower central through hole (15).

2. The specimen for Z-axis fatigue testing of an explosive composite joint according to claim 1, characterized in that, The taper of the tapered transition section (18) is 1:2 to 1:

10.

3. The specimen for Z-axis fatigue testing of an explosive composite joint according to claim 2, characterized in that, The taper of the tapered transition section (18) is 1:

5.

4. The specimen for Z-axis fatigue testing of an explosive composite joint according to claim 3, characterized in that, A plurality of radial connecting holes (161) are provided through the circumferential boss (16), and the plurality of radial connecting holes (161) are evenly arranged around the outer circumference of the upper central through hole (14).

5. The specimen for Z-axis fatigue testing of an explosive composite joint according to claim 1, characterized in that, One or more intermediate layers (12) are provided between the top layer (11) and the bottom layer (13).

6. A tooling for Z-axis fatigue testing of an explosive composite joint, characterized in that, The fixture, in conjunction with the fatigue testing machine, is capable of performing Z-axis fatigue testing on the specimen (1) of the explosive composite joint as described in any one of claims 1 to 5. The fixture includes: The upper mold (5) is positioned above the sample (1); The lower mold (2) is positioned below the sample (1); The upper central mold (4) is installed in the upper central through hole (14); The lower center mold (3) is installed in the lower center through hole (15), and the lower center mold (3) is connected to the upper center mold (4); The first connecting piece (6) is used to pass through the upper mold (5), the circumferential boss (16) and the lower mold (2) in sequence to fix the sample (1) in the Z-direction fatigue testing fixture. The connecting component (7) is installed below the lower mold (2); During testing, the upper clamping assembly of the fatigue testing machine clamps the upper central mold (4), and the lower clamping assembly of the fatigue testing machine clamps the connecting assembly (7).

7. The tooling for Z-axis fatigue testing of an explosive composite joint according to claim 6, characterized in that, A receiving cavity (21) is provided in the lower mold (2). The central column part (17) of the sample (1) and the lower central mold (3) are provided in the receiving cavity (21). The lower central mold (3) and the bottom of the receiving cavity (21) are spaced apart, and the space is not less than 5 mm.

8. The tooling for Z-axis fatigue testing of an explosive composite joint according to claim 6, characterized in that, An obstacle hole (51) is provided at the center of the upper mold (5), and the obstacle hole (51) is used to avoid the upper central mold (4).

9. The tooling for Z-axis fatigue testing of an explosive composite joint according to claim 6, characterized in that, An installation cavity (23) is provided at the bottom center of the lower mold (2), and the connecting component (7) cooperates with the installation cavity (23).

10. A method for Z-axis fatigue testing of an explosive composite joint, characterized in that, The Z-axis fatigue testing method is performed using the tooling and fatigue testing machine for the Z-axis fatigue testing of the explosive composite joint as described in any one of claims 6 to 9. The method includes the following steps: S1. Obtain a sample (1) from the explosive composite joint. S2. Install the upper center mold (4) of the tooling into the upper center through hole (14), and install the lower center mold (3) into the lower center through hole (15). The lower center mold (3) is connected to the upper center mold (4). S3. The upper mold (5) is set above the sample (1), and the lower mold (2) is set below the sample (1). Then, the upper mold (5), the sample (1) and the lower mold (2) are connected together by the first connector (6). S4. Install the connecting component (7) below the lower mold (2) to form a test component; S5. Install the test components into the fatigue testing machine, wherein the upper clamping component of the fatigue testing machine clamps the upper central mold (4), and the lower clamping component clamps the connecting component (7). S6. Control the Z-direction stress loading by controlling the fatigue testing machine until the specimen (1) fails at the interface to be tested.

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