Metal material low-temperature fracture toughness testing device for fatigue testing machine

Abstract

The invention discloses a metal material low-temperature fracture toughness testing device for a fatigue testing machine, relates to the technical field of material mechanical property testing, and solves the problem that room-temperature and low-temperature material testing cannot be performed on the same testing device. The device comprises a test barrel, an inner container, an extensometer, an upper joint and a lower joint, wherein the inner container is arranged in the test barrel; the extensometer is in contact with the sample and returns a real-time mechanical signal; the upper end of the upper connector is connected with a hydraulic chuck above the fatigue testing machine, and the lower end of the lower connector penetrates through the inner container and the testing barrel to be connected with a hydraulic chuck below the fatigue testing machine; the upper joint and the lower joint are opposite to each other and are used for clamping a sample; a sealing structure is arranged between the lower connector and the inner container. According to the invention, a testing machine does not need to be transformed, testing conditions for samples with different sizes are obtained by replacing different accessories, and meanwhile, a testing clamp can be replaced to test the mechanical properties of materials under different environmental conditions.

Description

Technical Field

[0001] The invention relates to the technical field of material mechanical property testing, in particular to a metal material low-temperature fracture toughness testing device for a fatigue testing machine. Background Art

[0002] The development of materials science is often inseparable from engineering applications. In the field of polar and deep space exploration, metal materials often need to maintain stable mechanical properties in low-temperature environments to ensure the reliability and safety of the structure. However, metal materials often show a sharp drop in fracture toughness at low temperatures, causing sudden brittle fractures of metal materials under external loads, resulting in structural failure and serious safety hazards. Therefore, evaluating the fracture toughness of metal materials in low-temperature environments is crucial to predicting the actual service performance of materials.

[0003] Fatigue testing machines are key equipment for measuring the fracture toughness of metals, but they cannot directly provide suitable low-temperature conditions for measuring fracture toughness at low temperatures, so additional testing equipment is needed to assist in completing the test. At present, it is still very difficult to conduct low-temperature and room-temperature fracture toughness tests on the same set of testing equipment and sensors, making it difficult to compare room-temperature and low-temperature data horizontally; at the same time, existing experimental devices have problems such as complex equipment structure, cumbersome testing process, poor safety, high cost, and poor equipment versatility, which is not conducive to the research and development of materials in the field of low temperatures. Summary of the invention

[0004] In order to solve the problem mentioned above that room temperature and low temperature material tests cannot be performed on the same set of test equipment, the present invention proposes a low temperature fracture toughness test device for metal materials for a fatigue test machine. The present invention does not require any modification of the test machine. By replacing different accessories, test conditions for samples of different sizes can be obtained. At the same time, the test fixture can also be replaced to test the mechanical properties of materials under different environmental conditions.

[0005] The present invention proposes a low-temperature fracture toughness testing device for a metal material for a fatigue testing machine, which specifically comprises a testing barrel, an inner liner, an extensometer, an upper joint and a lower joint, wherein the inner liner is arranged inside the testing barrel; the extensometer contacts the sample and returns a real-time mechanical signal; the upper end of the upper joint is connected to a hydraulic chuck above the fatigue testing machine, and the lower end of the lower joint passes through the inner liner and the testing barrel and is connected to the hydraulic chuck below the fatigue testing machine; the upper joint and the lower joint are opposite to each other to clamp the sample; and a sealing structure is arranged between the lower joint and the inner liner.

[0006] Furthermore, the upper joint includes an upper clamping screw and an upper fixture, the hydraulic chuck above the fatigue testing machine clamps the upper clamping screw, and the lower end of the upper clamping screw is connected to the upper fixture.

[0007] Furthermore, the lower joint includes a lower clamp, a lower clamping screw, a clamp base, a top flange and a transition structure; the clamp base and the top flange are arranged between the test barrel and the inner liner; the lower end of the lower clamp is connected to the lower clamping screw, the lower end of the lower clamping screw passes through the inner liner and is connected to the clamp base, and the clamp base is connected to the top flange; the upper end of the transition structure passes through the bottom of the test barrel and is connected to the top flange, and the lower end is connected to the hydraulic chuck below the fatigue testing machine; the sealing structure is arranged between the lower clamp and the bottom of the inner liner, and is sleeved on the lower clamping screw.

[0008] Furthermore, the adapter structure includes a connecting screw, a bottom connecting rod and an adapter; the upper end of the connecting screw passes through the bottom of the test barrel and is connected to the top flange, and the lower end is connected to the bottom connecting rod; the lower end of the bottom connecting rod is connected to the adapter.

[0009] Furthermore, the lower end of the bottom connecting rod and the adapter are connected by a pin.

[0010] Furthermore, a locking nut is provided on the bottom connecting rod, and the locking nut locks the pin.

[0011] Furthermore, a sealing ring is provided between the top flange and the test barrel, and a sealing ring is provided between the connecting screw and the test barrel.

[0012] Furthermore, the sealing structure includes a plurality of gaskets, and the plurality of gaskets are stacked between the lower clamp and the inner container.

[0013] Furthermore, a plurality of O-rings are arranged between the gaskets, and a plurality of O-rings are arranged between the gaskets and the inner liner.

[0014] Furthermore, a plurality of side grooves are arranged on the outer wall of the inner container.

[0015] The beneficial effects of the metal material low temperature fracture toughness testing device for a fatigue testing machine described in the present invention are:

[0016] (1) The low-temperature fracture toughness testing device for metal materials used in a fatigue testing machine of the present invention overcomes the problem that room temperature and low-temperature material tests cannot be performed on the same set of testing devices. The polyurethane inner liner allows the test sample to be directly immersed in a refrigerant such as liquid nitrogen to perform a low-temperature mechanical test, which is easy to operate. At the same time, without affecting the test environment, the purpose of further reducing the internal volume is achieved, and space is left for the extensometer to be placed, thereby reducing the amount of refrigerants such as liquid nitrogen, making the test safer, the temperature more stable, and the data more accurate.

[0017] (2) The present invention relates to a low-temperature fracture toughness testing device for a metal material used in a fatigue testing machine. The clamping screw and the fixture are connected by threads. Different fixtures can be matched under the condition that the size specifications are met. Not only can low-temperature fracture toughness tests be performed, but also low-temperature tensile tests can be performed by replacing the fixtures.

[0018] (3) In the low-temperature fracture toughness testing device for metal materials used in a fatigue testing machine described in the present invention, the sealing structure obtains the extrusion force by the threaded connection of the lower clamp, so that the gap between the polyurethane liner and the lower clamping screw is well sealed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] In the attached picture:

[0021] Figure 1 It is a three-dimensional structural schematic diagram of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0022] Figure 2 It is a schematic diagram of the three-dimensional structure of a test barrel of a metal material low-temperature fracture toughness test device for a fatigue testing machine according to the present invention;

[0023] Figure 3 It is a three-dimensional structural schematic diagram of the inner shell of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0024] Figure 4 It is a three-dimensional structural schematic diagram of an upper joint and a lower joint of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0025] Figure 5 It is a structural schematic diagram of a fixture of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0026] Figure 6 It is a three-dimensional structural schematic diagram of a lower joint (excluding a lower clamp and a lower clamping screw) of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0027] Figure 7 It is a structural schematic diagram of a sealing structure of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0028] Figure 8 It is a three-dimensional structural schematic diagram of a fracture fixture of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0029] Fig. 9 It is a three-dimensional structural schematic diagram of a tensile fixture of a metal material low-temperature fracture toughness testing device for a fatigue testing machine according to the present invention;

[0030] Among them: 1-test barrel, 2-inner liner, 3-extensometer, 4-upper clamping screw, 5-clamp, 51-upper clamp, 52-lower clamp, 6-lower clamping screw, 7-clamp base, 8-top flange, 9-connecting screw, 10-bottom connecting rod, 11-adapter, 12-lower joint, 13-locking nut, 14-pin, 15-washer, 16-O-ring, 17-fracture fixture, 18-fracture specimen, 19-tensile fixture, 20-tensile specimen. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0033] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0034] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Specific implementation method 1: See Figure 1-Figure 9The present embodiment is described in detail. A low-temperature fracture toughness test device for a metal material used in a fatigue testing machine described in the present embodiment specifically includes a test barrel 1, an inner liner 2, an extensometer 3, an upper joint and a lower joint 12. The test barrel 1 is mainly used for the rigid connection of the entire test device while preventing leakage of low-temperature liquid and keeping it warm. The barrel body is made of 316 stainless steel and is a double-layer hollow structure that can be directly in contact with liquid nitrogen for insulation. The upper joint and the lower joint 12 connecting the test machine are the main force-bearing components of the device, both of which are made of 30Cr13 martensitic stainless steel; the inner liner 2 is made of polyurethane. Compared with stainless steel, polyurethane material has better machinability and good thermal insulation performance; the inner liner 2 is designed according to the space matching required by the sample and the extensometer 3 during the test, and the inner liner 2 is designed as a special-shaped structure to further reduce the internal space for the test; and the asymmetric internal space can not only meet the space required for the test, but also further reduce the amount of refrigerant, reduce the cost of use and improve the safety of the test;

[0036] The liner 2 is arranged inside the test barrel 1, forming a double-layer hollow structure. The bottoms of the test barrel 1 and the liner 2 are both provided with through holes. The upper end of the upper joint is connected to the hydraulic chuck above the fatigue testing machine, and the lower end of the lower joint 12 passes through the through holes at the bottom of the liner 2 and the test barrel 1 and is connected to the hydraulic chuck below the fatigue testing machine. The upper joint and the lower joint 12 are opposite to each other to clamp the sample. The liner 2 is filled with liquid nitrogen and other refrigerants, and a sealing structure is provided between the lower joint 12 and the liner 2 to prevent refrigerant leakage. The extensometer 3 is arranged inside the liner 2 and in contact with the sample, and returns real-time mechanical signals.

[0037] The upper joint includes an upper clamping screw 4 and an upper clamp 51. The hydraulic chuck above the fatigue testing machine clamps the upper clamping screw 4. The lower end of the upper clamping screw 4 and the upper clamp 51 are connected by threads.

[0038] The lower joint 12 includes a lower clamp 52, a lower clamping screw 6, a clamp base 7, a top flange 8 and a transition structure; the clamp base 7 and the top flange 8 are arranged between the test barrel 1 and the inner liner 2; the lower end of the lower clamp 52 is connected to the lower clamping screw 6 by a threaded connection, the lower end of the lower clamping screw 6 passes through the inner liner 2 and is connected to the clamp base 7 by a threaded connection, and the bottom of the clamp base 7 is connected to the top flange 8 by a plurality of M8 bolts; the upper end of the transition structure passes through the bottom of the test barrel 1 and is connected to the top flange 8, and the lower end is connected to the hydraulic chuck below the fatigue testing machine; the sealing structure is arranged between the lower clamp 52 and the bottom of the inner liner 2, and is sleeved on the lower clamping screw 6; the upper clamp 51 and the lower clamp 52 have the same structure, and the upper clamp 51 and the lower clamp 52 are placed relatively spaced apart to form a clamp 5 together, which is connected to the sample.

[0039] The adapter structure includes a connecting screw 9, a bottom connecting rod 10 and an adapter 11; the upper end of the connecting screw 9 passes through the bottom of the test barrel 1 and is threadedly connected to the top flange 8, and the lower end is connected to the bottom connecting rod 10 through multiple M8 bolts; the lower end of the bottom connecting rod 10 is connected to the adapter 11.

[0040] The lower end of the bottom connecting rod 10 and the adapter 11 are connected by a pin 14. A locking nut 13 is provided on the bottom connecting rod 10, and the locking nut 13 locks the pin 14. The adapter 11 is a two-section integrated structure, the upper part is connected by a pin, and the lower part is fixed to the lower end of the testing machine by a thread, so that the force of the testing machine acts axially on the lower joint 12, thereby driving the clamp 5 to move.

[0041] A sealing ring is provided between the top flange 8 and the test barrel 1 , and a sealing ring is provided between the connecting screw 9 and the test barrel 1 , so as to achieve further sealing and prevent refrigerant leakage.

[0042] The sealing structure includes a plurality of gaskets 15, and the plurality of gaskets 15 are stacked between the lower clamp 52 and the inner liner 2. A plurality of O-rings 16 are arranged between the gaskets 15, and a plurality of O-rings 16 are arranged between the lowest gasket 15 and the inner liner 2; the O-rings 16 are filled in the annular groove on the surface of the gasket 15. The plurality of O-rings 16 and the lower clamping screw 6 are coaxially arranged, and the diameter gradually increases from the inside to the outside; the sealing structure achieves the purpose of sealing by applying an extrusion force through the lower clamp at the top of the lower clamping screw. The gasket 15 is made of fluororubber, and the O-ring 16 is made of silicone rubber. The gasket 15 adopts two different thicknesses, which are 2mm and 3mm respectively. The overall sealing structure can add or subtract the stacking thickness according to the actual situation to obtain a good extrusion sealing effect.

[0043] The outer wall of the inner liner 2 is provided with a plurality of side grooves, which run through the upper and lower parts. The side grooves can prevent the formation of a negative pressure zone in the bottom space when taking out due to the inner liner and the inner wall of the test barrel being too close, and at the same time provide a gripping space for installation and taking out.

[0044] The present invention is not limited to low temperature fracture toughness tests on metal materials. Figure 8-Figure 9 Shown are the fracture fixture 17, tensile fixture 19 and their corresponding fracture specimens 18 and tensile specimens 20 used in the present device, which are connected to the upper clamping screw 4 and the lower clamping screw 6 by threads, and the test specimens are fixed by means of pins 14. In actual use, the fixture structure size can be changed according to the properties of different materials to meet the test requirements.

[0045] The specific installation process of the metal material low temperature fracture toughness testing device for a fatigue testing machine described in the present invention is as follows:

[0046] During installation and use, the upper clamping screw 4 is clamped and fixed by the hydraulic chuck of the testing machine, and the upper clamp 51 is threadedly connected to the upper clamping screw 4; the lower screw of the adapter 11 is directly rigidly connected to the testing machine cylinder and fixed by setting a locking nut; the connecting screw 9 passes through the reserved through hole at the bottom of the test barrel 1 from the bottom, and is fixed with the top flange 8 inside the test barrel 1, and both and the test barrel 1 are sealed with sealing gaskets; the clamp base 7 is fixed to the top flange 8 by four M8 bolts, and the lower clamping screw 4 is fixed in the threaded hole of the clamp base 7; the bottom connecting rod 10 is connected to the bottom of the connecting screw 9 with four M8 bolts, At this time, the test barrel 1 and the lower joint 12 except the adapter 11 are connected and fixed as a whole, which is convenient for the disassembly and assembly of the device; the bottom connecting rod 10 is connected to the adapter 11 by a pin connection and locked with the locking nut 13 of the bottom connecting rod 10. At this time, the force of the test machine cylinder can drive the clamp 5 to move up and down through the lower joint 12; the polyurethane inner liner 2 is installed into the test barrel 1, and the lower clamp screw 6 will pass through the bottom through hole of the inner liner 2. In order to prevent the refrigerant from leaking out from the gap between the lower clamp screw 6 and the inner liner 2, a sealing kit is inserted into the lower clamp screw 6, and tightened with the lower clamp 52 to achieve the effect of extrusion sealing.

[0047] To summarize the above implementation cases, the low-temperature fracture toughness testing device for metal materials used in a fatigue testing machine described in the present invention overcomes the problem that room temperature and low-temperature material tests cannot be performed on the same set of testing devices. By setting the inner liner 2 made of polyurethane material, the test sample can be directly immersed in a refrigerant liquid such as liquid nitrogen for low-temperature mechanical testing, which is easy to operate; at the same time, without affecting the test environment, by installing anisotropic polyurethane inner liner, the purpose of further reducing the internal volume is achieved, and a placement space is reserved for the extensometer 3, so that the amount of refrigerants such as liquid nitrogen is reduced, the test is safer, the temperature is more stable, and the data is more accurate; the low-temperature fracture toughness testing device for metal materials used in a fatigue testing machine described in the present invention, the clamping screw and the clamp 5 are connected by threads, and different clamps 5 can be matched under the condition of meeting the size specifications, not only can low-temperature fracture toughness tests be performed, but also low-temperature tensile tests can be performed by replacing the clamp 5; the low-temperature fracture toughness testing device for metal materials used in a fatigue testing machine described in the present invention, the sealing structure uses the threaded connection of the lower clamp 52 to obtain the extrusion force, so that the gap between the inner liner 2 made of polyurethane material and the lower clamping screw 6 is well sealed.

[0048] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the invention. It can also be a reasonable combination of the features recorded in the above implementation methods. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low temperature fracture toughness testing device for metal materials used in fatigue testing machines, characterized in that: The invention comprises a test barrel (1), an inner liner (2), an extensometer (3), an upper joint and a lower joint (12); the inner liner (2) is arranged inside the test barrel (1); the extensometer (3) contacts the sample and returns a real-time mechanical signal; the upper end of the upper joint is connected to a hydraulic chuck above a fatigue testing machine, and the lower end of the lower joint (12) passes through the inner liner (2) and the test barrel (1) and is connected to the hydraulic chuck below the fatigue testing machine; the upper joint and the lower joint (12) are opposite to each other and clamp the sample; a sealing structure is arranged between the lower joint (12) and the inner liner (2).

2. The low temperature fracture toughness testing device for metal materials for fatigue testing machine according to claim 1, characterized in that: The upper joint comprises an upper clamping screw (4) and an upper clamp (51); a hydraulic clamp on the upper side of the fatigue testing machine clamps the upper clamping screw (4); and the lower end of the upper clamping screw (4) is connected to the upper clamp (51).

3. The low temperature fracture toughness testing device for metal materials for fatigue testing machine according to claim 1, characterized in that: The lower joint (12) comprises a lower clamp (52), a lower clamping screw (6), a clamp base (7), a top flange (8) and a transition structure; the clamp base (7) and the top flange (8) are arranged between the test barrel (1) and the inner liner (2); the lower end of the lower clamp (52) is connected to the lower clamping screw (6), the lower end of the lower clamping screw (6) passes through the inner liner (2) and is connected to the clamp base (7), and the clamp base (7) is connected to the top flange (8); the upper end of the transition structure passes through the bottom of the test barrel (1) and is connected to the top flange (8), and the lower end is connected to the hydraulic chuck below the fatigue testing machine; the sealing structure is arranged between the lower clamp (52) and the bottom of the inner liner (2), and is sleeved on the lower clamping screw (6).

4. The low temperature fracture toughness testing device for metal materials for fatigue testing machine according to claim 3, characterized in that: The adapter structure comprises a connecting screw (9), a bottom connecting rod (10) and an adapter (11); the upper end of the connecting screw (9) passes through the bottom of the test barrel (1) and is connected to the top flange (8), and the lower end is connected to the bottom connecting rod (10); the lower end of the bottom connecting rod (10) is connected to the adapter (11).

5. The low temperature fracture toughness testing device for metal materials used in a fatigue testing machine according to claim 4, characterized in that: The lower end of the bottom connecting rod (10) and the adapter (11) are connected via a pin (14).

6. The low temperature fracture toughness testing device for metal materials for fatigue testing machine according to claim 5, characterized in that: The bottom connecting rod (10) is provided with a locking nut (13), and the locking nut (13) locks the pin (14).

7. The low temperature fracture toughness testing device for metal materials for fatigue testing machine according to claim 4, characterized in that: A sealing ring is provided between the top flange (8) and the test barrel (1), and a sealing ring is provided between the connecting screw (9) and the test barrel (1).

8. The metal material low temperature fracture toughness testing device for fatigue testing machine according to claim 3, characterized in that: The sealing structure comprises a plurality of gaskets (15), wherein the plurality of gaskets (15) are stacked and arranged between the lower clamp (52) and the inner container (2).

9. The metal material low temperature fracture toughness testing device for fatigue testing machine according to claim 8, characterized in that: A plurality of O-rings (16) are arranged between the washers (15), and a plurality of O-rings (16) are arranged between the washers (15) and the inner container (2).

10. The metal material low temperature fracture toughness testing device for fatigue testing machine according to claim 1, characterized in that: A plurality of side grooves are arranged on the outer wall of the inner container (2).

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