Anti-eccentric stress adjusting device for tensile test of rock sample and test method

Abstract

The invention discloses a rock sample tensile test anti-eccentric stress adjusting device, which comprises two groups of connectors for fixing a tensile sample, each connector comprises a sample fixing seat, a first spherical seat, a second spherical seat, a support frame, a connecting frame, a plurality of groups of hanging ring assemblies and a plurality of connecting rods, one side of the sample fixing seat is used for fixing the tensile sample, and the other side of the sample fixing seat is used for fixing the tensile sample; the first spherical seat is located on the other side of the connector, and the first spherical seat and the sample fixing seat are connected through each group of lifting ring assemblies; the second spherical seat is located between the first spherical seat and the sample fixing seat, the supporting frame is fixedly connected to the second spherical seat, and during a tensile test, the first spherical surface and the second spherical surface abut against each other and can swing in a self-adaptive mode. Through spherical surface swing adjustment of the first spherical surface and the second spherical surface and self-adaptive adjustment of the lifting ring assembly, the tensile stress direction and the axial direction of a tensile sample can be basically in a coaxial state.

Description

Technical Field

[0001] The present invention relates to engineering test equipment, and more particularly to a rock sample tensile test anti-eccentric force adjustment device, and also to a test method using the rock sample tensile test anti-eccentric force adjustment device. Background Art

[0002] In rock tensile testing, many factors jointly affect the tensile strength of rock, mainly including: 1) the characteristics of the rock itself, including rock type, its mineral composition, particle size and cementation mode, which determine the basic strength of the rock; 2) rock structure, porosity, bedding and other characteristics will change the internal stress distribution; 3) test environment factors, such as changes in temperature and humidity have a significant impact on the physical and mechanical properties of rock; 4) specimen equipment and methods should not be ignored. The choice of fixture type and the size and shape of the specimen will affect the stress condition and failure mode of the rock.

[0003] Among them, the first three influencing factors are mainly determined by the rock sample itself and can be overcome by selecting and screening the rock sample, while the fourth influencing factor is determined by the test method and equipment. Similar or identical rock samples, using different clamping methods will also produce large test deviations. During the tensile test, after the two ends of the tensile specimen are fixed, the specimen holders on both sides may produce a small deflection, resulting in a certain angle error. If the specimen holders are directly fixed in the tensile test equipment, the two ends of the tensile specimen may form an eccentric force, and the tensile specimen may be torsionally affected, which makes it impossible to accurately reflect the accurate tensile test parameters of the tensile specimen.

[0004] Therefore, a new solution needs to be proposed to solve this problem. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide an anti-eccentric force adjustment device and a test method for a rock specimen tensile test.

[0006] To achieve the above-mentioned object, the present invention adopts the following technical solution: a rock specimen tensile test anti-eccentric force adjustment device, comprising two sets of connectors for fixing the tensile specimen, the connectors comprising a specimen fixing seat, a first spherical seat, a second spherical seat, a support frame, a connecting frame, several sets of lifting ring assemblies and several connecting rods, one side of the specimen fixing seat is used to fix the tensile specimen, the first spherical seat is located on the other side of the connector, the sets of lifting ring assemblies are annularly distributed around the outer periphery of the first spherical seat, and the first spherical seat and the specimen fixing seat are connected via the sets of lifting ring assemblies;

[0007] The second spherical seat is located between the first spherical seat and the sample fixing seat, the support frame is fixedly connected to the second spherical seat, and the connecting frame is located on the side of the first spherical seat facing away from the second spherical seat; the connecting rods are distributed in a ring around the outer circumference of the first spherical seat, and the second spherical seat and the connecting frame are connected and fixed by the connecting rods; the first spherical surface and the second spherical surface are respectively formed on the opposite sides of the first spherical seat and the second spherical seat, and the first spherical surface and the second spherical surface are adapted to each other; during the tensile test, the first spherical surface and the second spherical surface are pressed against each other and can swing relative to each other along the spherical surfaces.

[0008] The present invention is further configured such that the hanging ring assembly includes a first hanging ring, a second hanging ring and a third hanging ring, the first hanging ring is fixedly connected to the sample fixing seat, the second hanging ring is fixedly connected to the first spherical seat, and the third hanging ring is connected to the first hanging ring and the second hanging ring respectively.

[0009] The present invention is further configured such that the third lifting ring is a waist-shaped structure, with both ends respectively annularly connected to the first lifting ring and the second lifting ring; the number of the lifting ring components is equal to the number of the connecting rods, and they are distributed in an annular manner.

[0010] The present invention is further configured such that the number of the lifting ring assemblies and the connecting rods are both 3-6 groups.

[0011] The present invention is further configured such that the first spherical surface is a convex surface, the second spherical surface is a concave surface, and the first spherical surface is partially embedded in the second spherical surface.

[0012] The present invention is further configured such that the support frame is fixedly connected to the side of the second spherical seat facing the sample fixing seat, the outer periphery of the support frame is fixedly connected with an extension part 1, the outer periphery of the connecting frame is fixedly connected with an extension part 2, the extension part 1 and the extension part 2 correspond one to one, and are respectively fixedly connected to the two ends of the connecting rod.

[0013] The present invention is further configured such that a device connector is fixedly connected to a side of the connecting frame facing away from the specimen fixing seat, and the device connector is used to connect to a tensile test device.

[0014] The present invention is further configured such that the connecting frame is fixedly connected to a sleeve portion, and the end portion of the tensile specimen can extend into the sleeve portion and be fixed by an adhesive.

[0015] The present invention is further configured such that the tensile specimen has a cylindrical structure, and two sets of connectors are respectively installed at both ends of the tensile specimen; along the axis direction of the tensile specimen, the projections of the center positions of the first spherical surface and the second spherical surface are located within the projection range of the tensile specimen.

[0016] The present invention also provides a rock sample tensile test method, which uses the rock sample tensile test anti-eccentric force adjustment device as described above to perform a tensile test on the tensile sample; the two ends of the tensile sample are respectively fixedly mounted on the sample fixing seats of two sets of connectors, and the connecting frames of the two sets of connectors are then mounted on the tensile position of the tensile test equipment; by adjusting the tensile test equipment, the two sets of connectors are stretched in opposite directions, and the first spherical surface and the second spherical surface are pressed against each other and can swing relative to each other along the spherical surfaces;

[0017] In the lifting ring assembly, adjustment along the radial direction of the tensile specimen can be achieved through the relative movement between the lifting rings; along the axis direction of the tensile specimen, the projections of the center positions of the first spherical surface and the second spherical surface are located within the projection range of the tensile specimen.

[0018] In summary, the present invention has the following beneficial effects:

[0019] By adopting a first spherical seat and a second spherical seat that adapt to each other, a spherically swingable structure is formed, which can produce adaptive swing according to the direction of the tensile force, so that the length direction of the tensile specimen can be kept consistent with the direction of the tensile force; combined with the ring assembly, each ring of the ring assembly can achieve a small swing during the tensile process. The combination of the spherical structure and the ring material makes the tensile direction of the connector flexibly adapt to the state of the tensile specimen, so that the tensile force direction and the axial direction of the tensile specimen can be basically coaxial, avoiding the adverse effect of eccentric force on the tensile specimen during the tensile process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a rock specimen tensile test anti-eccentric force adjustment device in this embodiment;

[0021] Figure 2 This is a first cross-sectional view of a device for adjusting anti-eccentric force in a tensile test of a rock specimen in this embodiment;

[0022] Figure 3 This is a second cross-sectional view of a device for adjusting anti-eccentric force in a tensile test of a rock specimen in this embodiment;

[0023] Figure 4 Schematic diagram of the structure of the first spherical seat and the second spherical seat in this embodiment.

[0024] Figure numerals: connector 1; tensile specimen 2; specimen fixing seat 3; socket portion 31; first spherical seat 4; first spherical surface 41; second spherical seat 5; second spherical surface 51; support frame 6; extension portion 1 61; connecting frame 7; equipment connector 71; extension portion 2 72; lifting ring assembly 8; first lifting ring 81; second lifting ring 82; third lifting ring 83; connecting rod 9. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] This embodiment discloses a rock specimen tensile test anti-eccentric force adjustment device, referring to Figures 1-4 As shown, it includes two groups of connectors 1. The two groups of connectors 1 work together to fix the two ends of the tensile specimen 2. By stretching the two groups of connectors 1 in opposite directions, the tensile test can be performed on the tensile specimen 2.

[0027] The structures of the two groups of connectors 1 are basically the same, and both include a sample fixing seat 3, a first spherical seat 4, a second spherical seat 5, a support frame 6, a connecting frame 7, several groups of lifting ring assemblies 8 and several connecting rods 9.

[0028] One side of the specimen holder 3 is used to secure the tensile specimen 2. This is typically achieved by bonding with an adhesive. A sleeve 31 is fixedly attached to the corresponding position of the specimen holder 3. The dimensions of the sleeve 31 match those of the tensile specimen 2. The end of the tensile specimen 2 can be inserted into the sleeve 31 and secured with the adhesive, thus securing the specimen holder 3 to the tensile specimen 2 and allowing the tensile specimen 2 to be installed.

[0029] The first spherical seat 4 is located on the other side of the connector 1. The sets of lifting ring assemblies 8 are distributed annularly around the outer periphery of the first spherical seat 4. The first spherical seat 4 is connected to the specimen holder 3 via the sets of lifting ring assemblies 8. The lifting ring assembly 8 is composed of multiple lifting rings that are connected in sequence to form a chain-like structure. This structure can not only transmit tension but also achieve movable adjustment within a small range. Under the action of tension, it can adaptively adjust along the direction of tension.

[0030] The second spherical seat 5 is located between the first spherical seat 4 and the specimen holder 3. The support frame 6 is fixedly connected to the second spherical seat 5. The connecting frame 7 is located on the side of the first spherical seat 4 facing away from the second spherical seat 5. Connecting rods 9 are distributed annularly around the outer periphery of the first spherical seat 4. The second spherical seat 5 and the connecting frame 7 are connected and fixed by each connecting rod 9. Under the fixed support of the connecting rods 9, the support frame 6 and the connecting frame 7 can be fixedly connected to form a fixed whole. By stretching the connecting frame 7, a force can be applied to the second spherical seat 5.

[0031] Reference Figure 4As shown, a first spherical surface 41 and a second spherical surface 51 are formed on opposite sides of the first spherical seat 4 and the second spherical seat 5, respectively. The first spherical surface 41 and the second spherical surface 51 are adapted to each other. Specifically, the first spherical surface 41 is convex and the second spherical surface 51 is concave, and the first spherical surface 41 can be partially embedded in the second spherical surface 51.

[0032] During the process of fixing the two ends of the tensile specimen 2, epoxy resin glue is first applied to the ends of the tensile specimen 2, and then the ends of the tensile specimen 2 are inserted into the sleeve portion 31 of the specimen fixing seat 3, and the ends of the tensile specimen 2 and the specimen fixing seat 3 are pressed against each other flatly. After the epoxy resin glue is cured, the tensile specimen 2 and the specimen fixing seat 3 are fixed.

[0033] However, after the ends of the tensile specimen 2 are fixed, the specimen holders 3 on either side may deflect, resulting in a certain degree of error. This problem can be caused by factors such as unevenness of the ends of the tensile specimen 2, excessive glue at the bonding point, or the presence of foreign matter. If the specimen holders 3 are directly fixed to the tensile test equipment, the ends of the tensile specimen 2 may be subjected to eccentric force, making it impossible to accurately reflect the tensile test parameters of the tensile specimen 2.

[0034] During the tensile test, the first spherical surface 41 and the second spherical surface 51 press against each other. When the clamping at both ends of the tensile specimen 2 is eccentric, the first spherical surface 41 and the second spherical surface 51 automatically deflect and adjust each other, so that the forces at both ends of the tensile specimen 2 can be automatically adjusted to the opposite sides, thereby achieving automatic leveling.

[0035] In this embodiment, each set of hanging ring assemblies 8 is composed of three hanging rings, including a first hanging ring 81, a second hanging ring 82, and a third hanging ring 83. The first hanging ring 81 is fixedly connected to the sample holder 3, the second hanging ring 82 is fixedly connected to the first spherical seat 4, and the third hanging ring 83 is connected to the first hanging ring 81 and the second hanging ring 82, respectively. The third hanging ring 83 has a waist-shaped structure with a long distance, which can form sufficient installation space between the first hanging ring 81 and the second hanging ring 82 for the installation of various components of the connector 1. The waist-shaped third hanging ring 83 has its two ends annularly connected to the first hanging ring 81 and the second hanging ring 82, respectively. When subjected to a tensile force, the first hanging ring 81 and the second hanging ring 82 can actively move to positions close to the two ends of the third hanging ring 83, thereby forming a stable ring-in-ring structure.

[0036] The support frame 6 is fixedly connected to the side of the second spherical seat 5 facing the specimen holder 3. An extension 1 61 is fixedly connected to the outer periphery of the support frame 6, and an extension 2 72 is fixedly connected to the outer periphery of the connecting frame 7. The extension 1 61 and the extension 2 72 extend to the outer peripheries of the first spherical seat 4 and the second spherical seat 5. The extension 1 61 and the extension 2 72 correspond one-to-one and are respectively fixedly connected to the ends of the connecting rod 9. After the connecting rod 9 is fixedly installed, its direction is consistent with the tensile direction.

[0037] The number of the lifting ring components 8 and the connecting rods 9 are both 3-6 groups, and the number of the lifting ring components 8 and the connecting rods 9 are equal and distributed in a ring-shaped interval. Figure 1-Figure 3 As shown, in this embodiment, four sets of the lifting ring assemblies 8 and the connecting rods 9 are provided for illustration, and the supporting frame 6 and the connecting frame 7 form relative cross-shaped structures.

[0038] A device connector 71 is fixedly connected to the side of the connecting frame 7 facing away from the sample fixing seat 3. The shape of the device connector 71 is adapted to the clamping position of the tensile test equipment, so that the connecting frame 7 can be easily clamped and fixed.

[0039] In this embodiment, the tensile specimen 2 has a cylindrical structure, and two sets of connectors 1 are respectively installed at both ends of the tensile specimen 2. Along the axis of the tensile specimen 2, the projections of the center positions of the first spherical surface 41 and the second spherical surface 51 are located within the projection range of the tensile specimen 2. That is, the tensile force can be applied and can pass roughly through the center of the tensile specimen 2. The tensile force can be applied along the axis of the tensile specimen 2. Then, through the automatic deflection of the first spherical surface 41 and the second spherical surface 51, the axis of the tensile specimen 2 can be automatically maintained parallel to the tensile direction, thereby preventing the tensile specimen 2 from being eccentric and preventing the tensile specimen 2 from being affected by eccentricity during the test and affecting the accuracy of the test.

[0040] This embodiment provides a rock sample tensile test method, which uses the rock sample tensile test anti-eccentric force adjustment device as described in the above embodiment to perform a tensile test on the tensile sample 2.

[0041] Before the test, the ends of the tensile specimen 2 are fixed to the specimen holders 3 of the two sets of connectors 1. Then, the various components of the connectors 1 are assembled to form a complete connector 1 at both ends of the tensile specimen 2. The connecting frames 7 of the two sets of connectors 1 are installed in the tensile position of the tensile testing equipment, and the connectors 1 are clamped using the equipment connectors 71.

[0042] During the stretching process, by adjusting the tensile testing equipment, the two groups of connectors 1 are stretched in opposite directions, the first spherical surface 41 and the second spherical surface 51 are pressed against each other, and the various rings of the ring assembly 8 are also tightened from a relaxed state. The first spherical surface 41 and the second spherical surface 51 can swing along the spherical surface, and the axial direction of the tensile specimen 2 can be adjusted so that the direction of the tensile specimen 2 is substantially parallel to the direction of stretching. Moreover, in the ring assembly 8, the relative movement between the various rings can achieve adjustment along the radial direction of the tensile specimen 2. Through the spherical swing adjustment of the first spherical surface 41 and the second spherical surface 51, combined with the adaptive adjustment of the ring assembly 8, the tensile force direction and the axial direction of the tensile specimen 2 can be substantially coaxial.

[0043] Along the axis of tensile specimen 2, the projections of the centers of first spherical surface 41 and second spherical surface 51 are located within the projection of tensile specimen 2. During the deflection of first spherical surface 41 and second spherical surface 51, second spherical seat 5 is relatively fixed to support frame 6 and connecting frame 7, as well as to the clamping components of the tensile testing equipment. Therefore, second spherical surface 51 of second spherical seat 5 remains fixed. During the deflection, the deflection is primarily caused by first spherical seat 4, ensuring that the direction of the tensile force is substantially coaxial with the axis of tensile specimen 2, thereby ensuring the stability and accuracy of the tensile test of tensile specimen 2.

[0044] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A rock specimen tensile test anti-eccentric force adjustment device, characterized in that: The invention comprises two groups of connectors (1) for fixing a tensile specimen (2), wherein the connectors (1) comprise a specimen fixing seat (3), a first spherical seat (4), a second spherical seat (5), a support frame (6), a connecting frame (7), a plurality of groups of hanging ring assemblies (8) and a plurality of connecting rods (9); one side of the specimen fixing seat (3) is used to fix the tensile specimen (2); the first spherical seat (4) is located on the other side of the connector (1); the groups of hanging ring assemblies (8) are distributed in an annular manner on the outer periphery of the first spherical seat (4); and the first spherical seat (4) and the specimen fixing seat (3) are connected via the groups of hanging ring assemblies (8); The second spherical seat (5) is located between the first spherical seat (4) and the sample fixing seat (3); the support frame (6) is fixedly connected to the second spherical seat (5); the connecting frame (7) is located on the side of the first spherical seat (4) facing away from the second spherical seat (5); the connecting rods (9) are distributed in an annular manner on the outer periphery of the first spherical seat (4); the second spherical seat (5) and the connecting frame (7) are connected and fixed by the connecting rods (9); the first spherical surface (41) and the second spherical surface (51) are respectively formed on the opposite sides of the first spherical seat (4) and the second spherical seat (5), and the first spherical surface (41) and the second spherical surface (51) are adapted to each other; during the tensile test, the first spherical surface (41) and the second spherical surface (51) press against each other and can swing relative to each other along the spherical surfaces.

2. The rock specimen tensile test anti-eccentric force adjustment device according to claim 1 is characterized in that: The hanging ring assembly (8) comprises a first hanging ring (81), a second hanging ring (82) and a third hanging ring (83); the first hanging ring (81) is fixedly connected to the sample fixing seat (3); the second hanging ring (82) is fixedly connected to the first spherical seat (4); and the third hanging ring (83) is connected to the first hanging ring (81) and the second hanging ring (82) respectively.

3. The rock specimen tensile test anti-eccentric force adjustment device according to claim 2, characterized in that: The third lifting ring (83) is a waist-shaped structure, with two ends respectively connected in an annular manner to the first lifting ring (81) and the second lifting ring (82); the number of the lifting ring components (8) and the connecting rod (9) is equal, and they are distributed in an annular manner.

4. The rock specimen tensile test anti-eccentric force adjustment device according to claim 3 is characterized in that: The number of the lifting ring assemblies (8) and the connecting rods (9) is 3-6.

5. The rock specimen tensile test anti-eccentric force adjustment device according to claim 1, characterized in that: The first spherical surface (41) is a convex surface, the second spherical surface (51) is a concave surface, and the first spherical surface (41) is partially embedded in the second spherical surface (51).

6. The rock specimen tensile test anti-eccentric force adjustment device according to claim 1, characterized in that: The support frame (6) is fixedly connected to the side of the second spherical seat (5) facing the sample fixing seat (3), the outer periphery of the support frame (6) is fixedly connected to the extension part 1 (61), and the outer periphery of the connecting frame (7) is fixedly connected to the extension part 2 (72), and the extension part 1 (61) and the extension part 2 (72) correspond to each other one by one and are fixedly connected to the two ends of the connecting rod (9) respectively.

7. The rock specimen tensile test anti-eccentric force adjustment device according to claim 1, characterized in that: A device connector (71) is fixedly connected to a side of the connecting frame (7) facing away from the sample fixing seat (3), and the device connector (71) is used to connect to a tensile test device.

8. The rock specimen tensile test anti-eccentric force adjustment device according to claim 1, characterized in that: The connecting frame (7) is fixedly connected with a sleeve portion (31), and the end of the tensile specimen (2) can extend into the sleeve portion (31) and be fixed by an adhesive.

9. The rock specimen tensile test anti-eccentric force adjustment device according to claim 1, characterized in that: The tensile specimen (2) has a cylindrical structure, and two groups of connectors (1) are respectively installed at both ends of the tensile specimen (2); along the axis direction of the tensile specimen (2), the projections of the center positions of the first spherical surface (41) and the second spherical surface (51) are located within the projection range of the tensile specimen (2).

10. A rock sample tensile test method, characterized in that: A tensile test is performed on a tensile specimen (2) using the rock specimen tensile test anti-eccentric force adjustment device as described in any one of claims 1 to 9; the two ends of the tensile specimen (2) are respectively fixedly mounted on the specimen fixing seats (3) of the two groups of connectors (1), and the connecting frames (7) of the two groups of connectors (1) are then mounted on the tensile position of the tensile test equipment; by adjusting the tensile test equipment, the two groups of connectors (1) are stretched in opposite directions, and the first spherical surface (41) and the second spherical surface (51) are pressed against each other and can swing relative to each other along the spherical surfaces; In the lifting ring assembly (8), adjustment along the radial direction of the tensile specimen (2) can be achieved through relative movement between the lifting rings; along the axial direction of the tensile specimen (2), the projections of the center positions of the first spherical surface (41) and the second spherical surface (51) are located within the projection range of the tensile specimen (2).

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