Corrosion fatigue test clamp and testing machine

Abstract

The invention relates to the technical field of material fatigue performance testing, in particular to a corrosion fatigue test clamp and a testing machine, and the corrosion fatigue test clamp comprises a base clamp, a medium containing groove, a sample clamping assembly and an upper end fastener which are coaxially assembled; the outer side of the bottom of the base clamp is provided with a first connecting part for connecting a lower end chuck of a testing machine, the inner side of the bottom is provided with a bearing boss extending upwards, the outer peripheral surface of the bearing boss is provided with a second connecting part, and the inner wall is provided with a third connecting part; the medium containing groove is formed in the base clamp, and a fourth connecting part detachably connected with the second connecting part is arranged at the bottom of the medium containing groove, so that a cavity surrounding the sample is formed; the sample clamping assembly is connected with the third connecting part, and the bottom end of the sample clamping assembly abuts against and fixes the medium containing groove. The upper end fastener is connected with the lower part of the sample; the corrosion fatigue test clamp provided by the invention can keep the sample clamping stability and the medium sealing reliability in a high-frequency corrosion fatigue test.

Description

Technical Field

[0001] The present invention relates to the technical field of material fatigue performance testing, and in particular to a corrosion fatigue test fixture and a testing machine. Background Art

[0002] High-cycle corrosion fatigue testing is a key method for evaluating the performance degradation of metal materials under the combined effects of cyclic stress and corrosive media. Traditional test equipment typically uses flange bolt connections or integrally welded structures. These structures can meet basic sealing requirements under static or low-frequency (<30Hz) conditions, but face unique challenges in high-frequency fatigue testing:

[0003] High frequency testing machine realizes fast loading through electromagnetic resonance of 60Hz~200Hz, and the test time can be shortened by more than 90% (10 5 Taking weekly tests as an example, traditional equipment requires about 28 hours (10Hz), while high-frequency equipment can shorten it to 8.3 minutes (200Hz). However, high-frequency vibration can cause the following problems with traditional devices: First, the connection between the specimen clamping end and the testing machine chuck is prone to loosening due to high-frequency micro-motion, causing additional bending stress and distorting the test data; second, the sealing interface between the corrosive medium container and the fixture is prone to medium leakage under the action of high-frequency vibration, which not only contaminates the test equipment but also destabilizes the corrosive environment. Although existing technologies have attempted to use integral corrosion-resistant materials for manufacturing, it is difficult to take into account both the structural stiffness under high-frequency vibration and the chemical stability of the complex medium environment, resulting in a significant reduction in test efficiency and reliability. Summary of the Invention

[0004] In view of some of the above shortcomings of the prior art, the object of the present invention is to provide a corrosion fatigue test fixture and testing machine that can maintain specimen clamping stability and medium sealing reliability during high-frequency corrosion fatigue testing.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a corrosion fatigue test fixture, comprising a coaxially assembled base fixture, a medium holding tank, a specimen clamping assembly, and an upper end fastener;

[0006] The base fixture is a cylindrical structure, with a first connection portion for connecting to the lower end chuck of the testing machine provided on the outer side of the bottom, a bearing boss extending upwardly provided on the inner side of the bottom, a second connection portion provided on the outer peripheral surface of the bearing boss, and a third connection portion provided on the inner wall;

[0007] The medium holding tank is provided in the base fixture. The medium holding tank is a cylindrical structure with an opening at the bottom. A fourth connecting portion detachably connected to the second connecting portion is provided at the bottom of the tank to form a cavity surrounding the sample.

[0008] The sample clamping assembly is detachably connected to the third connecting portion and is used to fix the sample in the medium holding tank, and the bottom end of the sample clamping assembly abuts against and fixes the medium holding tank;

[0009] The upper end fastener is detachably connected to the lower portion of the sample and is used to fix the sample and the sample clamping assembly to the base fixture.

[0010] In one embodiment of the present invention, the first connection portion, the second connection portion, the third connection portion, and the fourth connection portion are all threaded connection structures.

[0011] In one embodiment of the present invention, the sample clamping assembly includes a pressing member and an inner sleeve sleeved on the outside of the sample;

[0012] The pressing member is connected to the second connecting portion to fix the medium holding tank in the base fixture; the inner sleeve is detachably connected to the third connecting portion and is used to fix the sample in the medium holding tank.

[0013] In one embodiment of the present invention, a fifth connection portion for detachably connecting to the third connection portion is provided on the outer side of the inner sleeve, and a sixth connection portion for connecting to a sample is provided on the inner side of the inner sleeve.

[0014] In one embodiment of the present invention, the threaded connection between the inner sleeve and the third connecting portion is a fine thread with a pitch ranging from 0.5 mm to 1.5 mm.

[0015] In one embodiment of the present invention, the upper end fastener is a cylindrical structure with an opening at the bottom, and a seventh connection portion connected to the lower part of the sample is provided on the top. An eighth connection portion connected to the second connection portion is provided on the inner side of the upper end fastener of the cylindrical structure. The inner kit is accommodated in the upper end fastener, and the bottom of the upper end fastener is arranged to abut against the clamping member.

[0016] In one embodiment of the present invention, a sealing adhesive layer is provided at the connection between the bottom of the medium containing tank and the second connecting portion.

[0017] In one embodiment of the present invention, the medium containing tank is made of non-metallic material.

[0018] In one embodiment of the present invention, a boss is provided at one end of the inner sleeve, and the boss is arranged to be in sealing contact with the end of the upper fastener.

[0019] The present invention provides a testing machine comprising the corrosion fatigue testing fixture.

[0020] In summary, the present invention uses a coaxial assembly structure to make the center lines of each component coincide, effectively reducing the eccentric load under high-frequency vibration and avoiding additional bending stress at the sample clamping end; the bearing boss of the base fixture is connected to the medium holding tank through the outer peripheral surface to form a closed sealed cavity, blocking the medium leakage path; the inner wall of the base fixture is connected to the sample clamping assembly to form a double fastening structure, in which the bottom end of the sample clamping assembly is fixed to the medium holding tank by the interference, which can maintain the stability and sealing of the sealing interface under high-frequency vibration; the detachable connection between the upper end fastener and the lower part of the sample further ensures the rigid connection between the sample and the testing machine chuck, eliminating the hidden danger of micro-loosening, thereby overcoming the test data distortion caused by the loosening of the sample clamping end in high-frequency fatigue tests of traditional devices, and the environmental instability and equipment pollution problems caused by the failure of the corrosion medium container seal; the corrosion fatigue test fixture of this case is adapted to the fast loading characteristics of the high-frequency testing machine, while shortening the test time, ensuring the stability and repeatability of the test process, and effectively improving the test efficiency and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is an overall assembly diagram of a corrosion fatigue test fixture in one embodiment of the present invention;

[0023] Figure 2 Schematic diagram of the three-dimensional structure of a corrosion fatigue test fixture in one embodiment of the present invention;

[0024] Figure 3 is a structural cross-sectional view of a base clamp in one embodiment of the present invention;

[0025] Figure 4 A bottom view of a base fixture in one embodiment of the present invention;

[0026] Figure 5 This is an axial structural cross-sectional view of a medium containing tank in one embodiment of the present invention;

[0027] Figure 6 A top view of a medium holding tank according to an embodiment of the present invention;

[0028] Figure 7 A top view of a pressing member in one embodiment of the present invention;

[0029] Figure 8 This is a cross-sectional view of the axial structure of a pressing member in one embodiment of the present invention;

[0030] Figure 9 This is an axial structural cross-sectional view of an inner sleeve in one embodiment of the present invention;

[0031] Figure 10 A top view of an inner sleeve according to an embodiment of the present invention;

[0032] Figure 11 This is an axial structural cross-sectional view of an upper end fastener in one embodiment of the present invention;

[0033] Figure 12 A top view of an upper end fastener in one embodiment of the present invention;

[0034] Figure 13 This is a schematic structural diagram of a sample in one embodiment of the present invention;

[0035] Component number explanation: base clamp 1, first connecting part 11, supporting boss 12, second connecting part 121, third connecting part 122, medium holding tank 2, fourth connecting part 21, sample clamping assembly 3, pressing part 31, connecting structure 311, inner kit 32, fifth connecting part 321, sixth connecting part 322, boss 323, upper end fastener 4, seventh connecting part 41, eighth connecting part 42, sample 5, end connecting part 51, neck portion 52. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0037] See also Figures 1 to 13. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0038] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0039] High cycle fatigue refers to the condition in which a material is subjected to a cyclic stress higher than its yield strength and undergoes a large number of cycles (generally more than 10 5 High-cycle corrosion fatigue testing simulates corrosive media (such as salt water and acidic solutions) in actual operation, inducing fatigue cracks in materials and accelerating their growth rate. This allows for evaluation of their performance under the combined effects of corrosion and fatigue. A corrosion fatigue test fixture is a fixture specifically designed for high-cycle fatigue testing of test materials in corrosive environments. The design of this fixture must take into account the corrosive environment and the special requirements of high-cycle fatigue testing to ensure the effectiveness and reliability of the test.

[0040] See also Figure 1-13 The present invention provides a corrosion fatigue test fixture, comprising a coaxially assembled base fixture 1, a medium containing tank 2, a sample clamping assembly 3 and an upper end fastener 4;

[0041] The base fixture 1 is a cylindrical structure, and a first connecting part 11 for connecting to the lower end chuck of the testing machine is provided on the outer side of its bottom, and a bearing boss 12 extending upward is provided on the inner side of the bottom. The outer peripheral surface of the bearing boss 12 is provided with a second connecting part 121, and the inner wall is provided with a third connecting part 122; the medium holding tank 2 is arranged in the base fixture 1, and the medium holding tank 2 is a cylindrical structure with an opening at the bottom, and a fourth connecting part 21 detachably connected to the second connecting part 121 is provided at the bottom, forming a cavity surrounding the sample 5; the sample clamping assembly 3 is detachably connected to the third connecting part 122, and is used to fix the sample 5 in the medium holding tank 2, and the bottom end of the sample clamping assembly 3 axially contacts and fixes the medium holding tank 2; the upper end fastener 4 is detachably connected to the lower part of the sample 5, and is used to fix the sample 5 and the sample clamping assembly 3 to the base fixture 1.

[0042] It should be noted that the corrosion fatigue test fixture comprises a coaxially assembled base fixture 1, a medium holding tank 2, a specimen clamping assembly 3, and an upper fastener 4, forming an integrated structure. The base fixture 1 is cylindrical in structure, with a first connecting portion 11 on the outer side of the bottom being removably connected to the lower chuck of the testing machine via threads or flanges. A bearing boss 12 on the inner side of the bottom extends upward, with a second connecting portion 121 on its outer circumference removably connected to a fourth connecting portion 21 on the bottom of the medium holding tank 2, for example, by threaded engagement, a snap-in slot, or a plug-in structure, to form a sealed cavity surrounding the specimen 5. A third connecting portion 122 on the inner wall of the bearing boss 12 is removably connected to the specimen clamping assembly 3, using a threaded connection, a pin lock, or a keyway engagement. The specimen clamping assembly 3 is axially positioned by contact with the bottom of the medium holding tank 2, ensuring that the medium holding tank 2 does not move during high-frequency vibration. The medium holding tank 2 is made of a corrosion-resistant material and serves to contain the corrosive test medium, providing the specimen 5 with the required corrosive environment.

[0043] In this case, the center lines of each component are aligned through a coaxial assembly structure, which effectively reduces the eccentric load under high-frequency vibration and avoids additional bending stress at the clamping end of the sample 5; the bearing boss 12 of the base clamp 1 is connected to the medium holding tank 2 through the outer peripheral surface, and the inner wall is connected to the sample clamping assembly 3, forming a double fastening structure, in which the bottom end of the sample clamping assembly 3 is fixed to the medium holding tank 2 by abutment, and cooperates with the sealant or sealing ring (such as O-ring, lip sealing ring) at the threaded connection to maintain the stability and sealing of the sealing interface under high-frequency vibration; the detachable connection between the upper end fastener 4 and the lower part of the sample 5 (such as bolt tightening, nut tightening) further ensures the rigid connection between the sample 5 and the testing machine chuck, eliminates the hidden danger of micro-loosening, and thus overcomes the test data distortion caused by the loosening of the clamping end of the sample 5 in the high-frequency fatigue test of the traditional device, and the environmental instability and equipment pollution caused by the failure of the seal of the corrosive medium container. Therefore, this case improves the reliability of specimen 5 clamping through multiple fastening and coaxial positioning, ensuring the accuracy of test data under high-frequency vibration. Secondly, the combination of detachable connections and sealing structures prevents the leakage of corrosive media, maintains a stable corrosive environment, and avoids equipment contamination. Finally, the fast loading characteristics of the high-frequency testing machine shorten the test time while ensuring the stability and repeatability of the test process, effectively improving test efficiency and reliability.

[0044] See also Figure 1-6 As an optional embodiment of the present invention, the first connection portion 11, the second connection portion 121, the third connection portion 122 and the fourth connection portion 21 are all threaded connection structures.

[0045] It should be noted that the first connection part 11, the second connection part 121, the third connection part 122 and the fourth connection part 21 adopt a threaded connection structure, wherein the first connection part 11 serves as a connection structure between the outer side of the bottom of the base fixture 1 and the lower end chuck of the testing machine, and can be fixed by screwing an external thread with the internal thread of the testing machine chuck, or adopting different tooth profile structures such as trapezoidal thread and serrated thread to adapt to the anti-fatigue requirements under high-frequency vibration; the second connection part 121 is a threaded match between the outer peripheral surface of the bearing boss 12 and the fourth connection part 21 at the bottom of the medium holding tank 2, for example, using fine thread to enhance the sealing performance, or adding auxiliary sealing structures such as sealant and O-rings between the thread pairs, and the auxiliary sealing structure can be made of anti-corrosion material to ensure the sealing of the corrosive medium cavity; the third connection part 122 serves as a connection structure between the inner wall of the bearing boss 12 and the sample clamping assembly 3, and can optionally use a cylindrical thread or a conical thread. The axial pressure generated when the thread is tightened will press the bottom end of the sample clamping assembly 3 against the fixed medium holding tank 2, forming a multiple tightening effect. This case utilizes the advantages of the self-locking characteristics and adjustable preload of threaded connections. Under high-frequency vibration conditions, the axial clamping force generated by tightening the threaded pair is used to form a rigid whole among the base fixture 1, the medium holding tank 2, the specimen clamping assembly 3 and the upper end fastener 4, effectively suppressing micro-slippage of each connection part. At the same time, the selection of thread tooth profile and the combination of sealing structure (such as thread gap filling sealant) can prevent the leakage of corrosive media along the thread gap while maintaining the connection rigidity, thereby avoiding additional bending stress caused by loose connection and environmental instability caused by medium leakage.

[0046] See also Figure 1 and Figure 7-10 As an optional embodiment of this case, the sample clamping assembly 3 includes a pressing member 31 and an inner sleeve 32 that is sleeved on the outside of the sample 5; the pressing member 31 is connected to the second connecting portion 121 to fix the medium holding tank 2 in the base fixture 1; the inner sleeve 32 is detachably connected to the third connecting portion 122 and is used to fix the sample 5 in the medium holding tank 2.

[0047] It should be noted that the sample clamping assembly 3 adopts a combined structure of a clamping piece 31 and an inner sleeve 32. The connection between the clamping piece 31 and the second connecting part 121 can be achieved by threaded engagement (such as fine-pitch thread to enhance pre-tightening force) to fix the top end of the medium holding tank 2 against the lower end surface of the bearing boss 12 of the base fixture 1 to form an axial limit; the detachable connection between the inner sleeve 32 and the third connecting part 122 can be achieved by cylindrical thread engagement (with a lock nut) or conical thread engagement (using the self-locking characteristics of the taper). When the inner sleeve 32 is mounted on the outside of the sample 5, the sample 5 can be fixed to the center position of the medium holding tank 2 by a radial clamping structure (such as a top screw distributed along the circumferential direction) or an axial clamping structure (such as tightening the upper end nut) to ensure that the axis of the sample 5 coincides with the center line of the base fixture 1.

[0048] In this case, the medium holding tank 2 is axially fixed in the base clamp 1 by connecting the clamping piece 31 with the second connecting part 121, thereby suppressing the up and down movement of the medium holding tank 2 under high-frequency vibration; the connection between the inner sleeve 32 and the third connecting part 122 rigidly fixes the sample 5, and cooperates with the sealant or elastic sealing ring (such as fluororubber O-ring, polytetrafluoroethylene gasket) at the threaded connection to maintain close contact of the sealing interface during vibration; when high-frequency vibration occurs, the composite fastening structure formed by the clamping piece 31 and the inner sleeve 32 can effectively disperse the vibration load, avoiding micro-loosening of the clamping end of the sample 5 due to single-point force, and at the same time, the medium holding tank 2 is fixed to prevent sealing failure due to displacement.

[0049] See also Figure 1 、 9 -10, as an optional embodiment of the present case, the outer side of the inner sleeve 32 is provided with a fifth connection part 321 for detachably connecting to the third connection part 122, and the inner side of the inner sleeve 32 is provided with a sixth connection part 322 for connecting to the sample 5.

[0050] It should be noted that the outer side of the inner sleeve 32 is provided with a fifth connection portion 321 to achieve a detachable connection with the third connection portion 122, and the inner side is provided with a sixth connection portion 322 to achieve connection with the specimen 5. The fifth connection portion 321 can be a threaded connection structure, which, through screwing, forms a rigid connection between the inner sleeve 32 and the inner wall of the bearing boss 12 of the base fixture 1. The sixth connection portion 322 can be a threaded connection (e.g., the external thread on the outer wall of the specimen 5 matches the internal thread on the inner wall of the inner sleeve 32) or an interference fit structure (e.g., an interference fit in which the inner diameter of the inner sleeve 32 is slightly smaller than the outer diameter of the specimen 5) to coaxially fix the specimen 5 to the center of the inner sleeve 32. The removable connection of the fifth connecting portion 321 creates an axial preload between the inner sleeve 32 and the base fixture 1. This preload suppresses micro-slip between the inner sleeve 32 and the base fixture 1 when high-frequency vibration occurs. The rigid fixation of the specimen 5 by the sixth connecting portion 322 ensures that the axis of the specimen 5 coincides with the centerline of the device, preventing additional bending stress caused by eccentric loading. Furthermore, the thread profile design of the fifth connecting portion 321 (e.g., fine-pitch threads for enhanced sealing) or the sealing lip of the clamping structure (e.g., a rubber gasket embedded in the clamping gap) complement the sealing measures of the medium-holding groove 2 to prevent leakage of corrosive media along the connection interface. The dual connection structure of the fifth connecting portion 321 and the sixth connecting portion 322 enhances the clamping reliability of the specimen 5 during high-frequency vibration and ensures the accuracy of test data. The sealing design of the connection interface, combined with the preload structure, effectively prevents leakage of corrosive media, maintains a stable corrosive environment, avoids equipment contamination and test environment instability, and meets the rapid loading requirements of high-frequency fatigue testing, improving test efficiency and repeatability.

[0051] See also Figure 1 、9 -10, as an optional embodiment of the present case, the threaded connection between the inner sleeve 32 and the third connecting portion 122 is a fine thread with a pitch range of 0.5 mm to 1.5 mm.

[0052] It should be noted that the inner sleeve 32 and the third connecting part 122 are connected by fine thread, and the pitch range is limited to 0.5mm to 1.5mm. The fine thread structure can achieve equivalent technical effects through different tooth angles (such as 55°, 60° or with a sealing lip structure), pitch parameters (such as 0.75mm, 1.0mm, 1.25mm) or auxiliary sealing measures (such as thread glue). For example, when using a fine thread with a 60° tooth angle, a smaller pitch can increase the number of meshing turns of the thread teeth, and the use of polytetrafluoroethylene raw tape can further fill the thread gap and enhance the sealing performance. On the one hand, the connection reliability between the inner sleeve 32 and the base fixture 1 is improved, and additional bending stress is avoided at the clamping end of the sample 5 under high-frequency vibration, thereby ensuring the accuracy of the test data; secondly, the self-locking characteristics and vibration resistance of the fine thread are utilized to adapt to the fast loading requirements of the high-frequency testing machine, shortening the test cycle while ensuring the stability and repeatability of the long-term operation of the device.

[0053] See also Figure 1 、 11 -12, as an optional embodiment of the present case, the upper end fastener 4 is a cylindrical structure with an opening at the bottom, and a seventh connecting portion 41 connected to the lower part of the specimen 5 is provided on the top thereof, and an eighth connecting portion 42 connected to the second connecting portion 121 is provided on the inner side of the upper end fastener 4 of the cylindrical structure, and the inner sleeve 32 is accommodated in the upper end fastener 4, and the bottom of the upper end fastener 4 is arranged to abut against the clamping member 31.

[0054] It should be noted that the upper fastener 4 is a cylindrical structure with an opening at the top. Its design follows the principle of coaxial assembly to ensure that it coincides with the center lines of the base fixture 1, the medium holding tank 2, and the sample 5. The seventh connecting portion 41 at the bottom is used to connect to the lower part of the sample 5. This connection portion can adopt a threaded connection (such as fine thread, triangular thread, trapezoidal thread), a clamping structure (such as elastic clamping claws, radial top screws), or an interference fit (such as a conical interference fit). For example, a fine thread screw is used to achieve a rigid connection between the sample 5 and the upper fastener 4. The eighth connecting portion 42 on the inside of the cylindrical structure is connected to the second connecting portion 121 (the outer peripheral surface of the bearing boss 12) and can be threaded (such as a cylindrical thread or a conical thread). The inner sleeve 32 is housed within the upper fastener 4. Its outer side is connected to the eighth connecting portion 42, and its inner side fixes the sample 5 via the sixth connecting portion 322. At the same time, the bottom of the upper fastener 4 contacts and seals with the pressing member 31, forming an axial bidirectional limit structure and multiple seals.

[0055] The cylindrical upper end fastener 4 in this case is connected to the lower part of the sample 5 through the seventh connecting part 41, and the eighth connecting part 42 is connected to the bearing boss 12 of the base fixture 1, forming a rigid force transmission path of "sample 5-upper end fastener 4-base fixture 1". When high-frequency vibration is generated, the axial preload force is transmitted to the medium holding tank 2 through the bottom of the abutting pressing part 31, thereby suppressing the relative displacement of each component; the thread tooth profile design of the seventh connecting part 41 (such as fine thread to increase the number of engagement circles) avoids micro-loosening of the sample 5 and the upper end fastener 4; the thread pair of the eighth connecting part 42 and the second connecting part 121 is matched with sealant (or O-ring) to prevent the corrosive medium from leaking to the inner side of the upper end fastener 4 along the connection interface. At the same time, the inner sleeve 32 is fixed in both directions by the upper end fastener 4 and the bearing boss 12, further ensuring that the medium holding tank 2 maintains the stability of the sealed cavity during vibration. This solution overcomes the problems of loosening of the specimen 5 and the generation of additional bending stress caused by single-point fixation under high-frequency vibration in the traditional upper connection structure, as well as the leakage of the medium caused by displacement failure of the sealing interface. Through the above-mentioned structural design, the double connection structure of the upper end fastener 4 (the connection between the specimen 5 and the base fixture 1) improves the overall rigidity, avoids micro-slippage of the clamping end of the specimen 5 under high-frequency vibration, and ensures the accuracy of the test data; secondly, the sleeve-shaped upper end fastener 4 and the clamping member 31 form a seal to prevent the leakage of corrosive media and maintain a stable corrosive environment; finally, the detachable connection method facilitates the replacement of the specimen 5, and the coaxial assembly structure adapts to the rapid loading requirements of the high-frequency testing machine, shortening the test time while ensuring the reliability and repeatability of the device in long-term high-frequency vibration.

[0056] As an optional embodiment of the present invention, a sealing layer is provided at the connection between the bottom of the medium containing tank 2 and the second connecting portion 121 .

[0057] It should be noted that the sealant layer can be made of materials such as silicone sealant, fluororubber sealant, or polytetrafluoroethylene sealant, and can be attached to the connection interface through coating, pressing, or embedding. For example, silicone sealant has excellent weather resistance and elasticity, making it suitable for dynamic sealing under high-frequency vibration; fluororubber sealant has excellent corrosion resistance and is suitable for highly corrosive environments such as acid or salt spray; and polytetrafluoroethylene sealant forms a plastic sealing layer by filling the thread gap, enhancing interfacial adhesion. Furthermore, the sealant layer can be used in conjunction with sealing structures such as O-rings and spiral wound gaskets to form a composite sealing system.

[0058] As an optional embodiment of the present invention, the medium containing tank 2 is made of a non-metallic material or a non-metallic transparent material.

[0059] It should be noted that the material can be selected from polymer materials such as polytetrafluoroethylene, polypropylene, and polyethylene, or inorganic non-metallic materials such as quartz glass and ceramics. For example, polytetrafluoroethylene has excellent chemical stability and can withstand corrosion from strong acids, strong bases, and salt solutions; polypropylene has low density and moderate mechanical strength, making it suitable for neutral or weakly corrosive media environments; and quartz glass has high light transmittance and temperature resistance, facilitating observation of media conditions and adapting to high-temperature corrosive environments. The selection of the above materials can be adapted according to the characteristics of the test medium (such as acidity, alkalinity, temperature) and vibration conditions, forming a variety of implementation methods.

[0060] See also Figure 1 、 9 -10, as an optional embodiment of the present case, a boss 323 is provided at one end of the inner sleeve 32, and the boss 323 is configured to seal and abut against the end of the upper fastener 4.

[0061] It should be noted that a boss 323 is provided at one end of the inner sleeve 32. This boss 323 can take the form of an annular boss, a stepped boss, or a tapered boss, etc., to achieve sealing contact with the inner end of the upper fastener 4. For example, an annular boss extending circumferentially along the inner sleeve 32 forms an annular protrusion that cooperates with the annular groove at the end of the upper fastener 4 to form an axial seal; a stepped boss increases the contact area through a multi-step structure, improving sealing reliability; and a tapered boss utilizes the self-tightening properties of the tapered surface to achieve dynamic sealing under axial pressure.

[0062] See also Figure 1 、 9 -10, as an optional embodiment of the present invention, the pressing member 31 and / or the outer side surface of the upper end fastener 4 and / or the inner sleeve 32 have symmetrically arranged clamping surfaces.

[0063] It should be noted that the outer side surfaces of the pressing member 31 and / or the upper end fastener 4 are provided with symmetrical clamping surfaces, which can be flat, grooved, or ridged. These clamping surfaces can be adapted to the type of assembly tool (e.g., open-end wrench, ring wrench, special clamp), forming a variety of implementation methods, thereby improving the assembly and disassembly efficiency of the device and shortening test preparation and maintenance time.

[0064] See also Figure 1 、 3 As an optional embodiment of this case, the second connecting portion 121 is an external thread provided on the outer peripheral surface of the bearing boss 12, and the fourth connecting portion 21 is an internal thread provided at the bottom opening of the medium containing tank 2.

[0065] As an optional embodiment of the present case, the contact surface between the pressing member 31 and the upper end fastener 4 is a conical mating surface, and the taper angle ranges from 15° to 45°.

[0066] As an optional embodiment of the present case, the end of the sample 5 is provided with an end connection portion 51, and the end connection portion 51 is a threaded structure. The middle part of the sample 5 is a constricted portion 52, and the diameter of the constricted portion 52 is smaller than the diameter of other position sections of the sample 5, and at least part of the structure of the constricted portion 52 is located in the medium holding tank 2.

[0067] The corrosion fatigue test fixture provided by the present invention comprises a coaxially assembled base fixture 1, a medium holding tank 2, a specimen clamping assembly 3, and an upper end fastener 4, forming an integrated structure. The base fixture 1 is cylindrical, with a first connecting portion 11 on the outer side of the bottom portion connected to the lower end chuck of the testing machine. The inner bearing boss 12 is detachably connected to the fourth connecting portion 21 of the medium holding tank 2 via a second connecting portion 121. A third connecting portion 122 on the inner wall of the bearing boss 12 is connected to the inner sleeve 32 in the specimen clamping assembly 3. The inner sleeve 32 secures the specimen 5 via a sixth connecting portion 322. The upper end fastener 4 is connected to the lower portion of the specimen 5 via a seventh connecting portion 41 and to the outer circumference of the bearing boss 12 via an eighth connecting portion 42, forming a dual fastening path. The medium holding tank 2 is made of non-metallic material, and a sealing layer is provided at the connection between its bottom and the base fixture 1. The boss 323 at one end of the inner sleeve 32 is in sealing contact with the end of the upper fastener 4. The symmetrical clamping surfaces on the outer side of the pressing member 31 and / or the upper fastener 4 facilitate the application of force by the assembly tool. This case utilizes the self-locking characteristics and pre-tightening force of the threaded connection to form a rigid whole of each component. The fine thread design increases the engagement depth to suppress micro-slip under high-frequency vibration; the medium holding tank 2 made of non-metallic material cooperates with the sealing layer and the boss 323 sealing structure to block the leakage path of the corrosive medium; the symmetrical clamping surface ensures uniform transmission of the assembly torque to avoid deformation of the components. Through the above structure, the problems of loosening of the clamping end of the sample 5, leakage of the medium and inconvenience of assembly in high-frequency vibration of the traditional device are solved, and the following technical effects are achieved: first, double fastening and coaxial positioning improve the clamping reliability of the sample 5 and ensure the accuracy of the test data; second, the non-metallic material and composite sealing structure prevent medium leakage and maintain the stability of the corrosive environment.

[0068] The specific features of the corrosion fatigue test fixture are as follows: First, corrosion-resistant materials: The corrosion fatigue test fixture in this case is usually made of corrosion-resistant materials, such as stainless steel and non-metallic materials, to maintain its performance and stability in corrosive environments. Second, compact structure: The device has a compact structural design. For example, through the cooperation between the upper end fastener 4 and the clamping member 31, the structure inside the upper end fastener 4 is contained and sealed to reduce the exposure area to the corrosive medium, thereby reducing the impact of corrosion on the corrosion fatigue test fixture itself. Third, high clamping precision: The corrosion fatigue test fixture can clamp the specimen 5 with high precision to ensure that the specimen 5 will not fall off or generate additional stress due to unstable clamping during the fatigue test. Fourth, multiple fastening and coaxial positioning improve the clamping reliability of the specimen 5 and ensure the accuracy of the test data. Fifth, the cylindrical base fixture 1 has a secondary leak-proof effect. If the corrosive medium enters the cavity of the base fixture 1, no secondary leakage will occur because there are no holes at the bottom of the base fixture 1, thereby ensuring safety in use.

[0069] The present invention also provides a testing machine, including a corrosion fatigue test fixture, such as a high-frequency testing machine that is a universal electromagnetic excitation resonance testing machine, which is used to perform high-cycle corrosion fatigue tests. The high-frequency testing machine completes the metal material 10 by a force cycle frequency of 60Hz to 200Hz. 5 cycles or more high cycle corrosion fatigue test, thereby shortening the test time.

[0070] In summary, the present invention effectively overcomes some practical problems in the prior art and thus has high utilization value and use significance.

[0071] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A corrosion fatigue test fixture, characterized in that: It includes a coaxially assembled base fixture, a medium holding tank, a sample clamping assembly and an upper end fastener; The base fixture is a cylindrical structure, with a first connection portion for connecting to the lower end chuck of the testing machine provided on the outer side of the bottom, a bearing boss extending upwardly provided on the inner side of the bottom, a second connection portion provided on the outer peripheral surface of the bearing boss, and a third connection portion provided on the inner wall; The medium holding tank is provided in the base fixture. The medium holding tank is a cylindrical structure with an opening at the bottom. A fourth connecting portion detachably connected to the second connecting portion is provided at the bottom of the tank to form a cavity surrounding the sample. The sample clamping assembly is detachably connected to the third connecting portion and is used to fix the sample in the medium holding tank, and the bottom end of the sample clamping assembly abuts against and fixes the medium holding tank; The upper end fastener is detachably connected to the lower portion of the sample and is used to fix the sample and the sample clamping assembly to the base fixture.

2. The corrosion fatigue test fixture according to claim 1, characterized in that: The first connection portion, the second connection portion, the third connection portion and the fourth connection portion are all threaded connection structures.

3. The corrosion fatigue test fixture according to claim 1, characterized in that: The sample clamping assembly includes a pressing member and an inner sleeve sleeved on the outside of the sample; The pressing member is connected to the second connecting portion to fix the medium holding tank in the base fixture; the inner sleeve is detachably connected to the third connecting portion and is used to fix the sample in the medium holding tank.

4. The corrosion fatigue test fixture according to claim 3, characterized in that: A fifth connection portion for detachably connecting to the third connection portion is provided on the outer side of the inner sleeve, and a sixth connection portion for connecting to a sample is provided on the inner side of the inner sleeve.

5. The corrosion fatigue test fixture according to claim 4, characterized in that: The threaded connection between the inner sleeve and the third connecting part is a fine thread with a pitch ranging from 0.5 mm to 1.5 mm.

6. The corrosion fatigue test fixture according to claim 3, characterized in that: The upper end fastener is a cylindrical structure with an opening at the bottom, and a seventh connection part connected to the lower part of the sample is provided on the top. An eighth connection part connected to the second connection part is provided on the inner side of the upper end fastener of the cylindrical structure. The inner kit is accommodated in the upper end fastener, and the bottom of the upper end fastener is arranged to abut against the clamping part.

7. The corrosion fatigue test fixture according to claim 1, characterized in that: A sealing adhesive layer is provided at the connection between the bottom of the medium containing tank and the second connecting portion.

8. The corrosion fatigue test fixture according to claim 1, characterized in that: The medium containing tank is made of non-metallic material.

9. The corrosion fatigue test fixture according to claim 3, characterized in that: One end of the inner sleeve is provided with a boss, and the boss is arranged to abut against the end of the upper end fastener.

10. A testing machine, characterized in that: The corrosion fatigue test fixture comprises the corrosion fatigue test fixture according to any one of claims 1 to 9.

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