A ring sample hoop compression test device and a testing method thereof

Abstract

The application discloses a kind of annular sample hoop compression test device and its testing method, belong to tubular member and annular structure mechanical property test technical field.The device includes base, lower support assembly, upper loading assembly and annular sample positioning assembly;Cylindrical pin shaft joint is provided with pin shaft hole along radial direction, for connecting with test machine pin shaft chuck, so that upper loading assembly is suspended by test machine before contacting annular sample Load bearing.Upper semicircular loading block and lower semicircular support block are arranged oppositely and contact with the opposite circular arc area of annular sample, to define hoop compression working section;Annular sample positioning assembly is used to limit sample lateral deviation.Record load-displacement curve during testing, obtain maximum compression load, and calculate hoop compression strength according to effective bearing cross-sectional area.The application can improve the centring and stability of annular sample hoop compression loading, reduce the influence of clamp self-weight preloading, local indentation, lateral deviation and additional bending moment on test results.

Description

Technical Field

[0001] This invention belongs to the technical field of mechanical property testing of tubular components and ring structures, specifically relating to a circumferential compression test device and its testing method for ring specimens, which can be used to evaluate the circumferential compression bearing capacity of composite material pipes, metal-composite material composite pipes, pressure-resistant pipes, bushings, and other ring specimens. Background Technology

[0002] Pipes, sleeves, bushings, pressure shells, and other annular or tubular structures may be subjected to external pressure, local radial compression, circumferential compression, and contact loads during service. For composite material pipes, deep-sea pressure-resistant components, and composite material bushings, circumferential load-bearing capacity directly affects the structure's instability, crushing, and local damage behavior, and is an important indicator for evaluating structural safety and the rationality of material design.

[0003] Existing compression tests on annular specimens typically employ flat plates, local indenters, or simple clamps to apply loads to the specimen. These methods have at least the following drawbacks: First, the contact area between the indenter and the annular specimen is small, easily leading to localized indentations, crushing, or stress concentration, making it difficult for the test results to represent the true circumferential compressive bearing capacity of the annular specimen. Second, the weight of the upper clamp or indenter may act on the specimen before the formal loading, resulting in uncontrolled pre-compression deformation in the initial stage. Third, the annular specimen is prone to lateral displacement, rotation, or eccentric compression during loading, introducing additional bending moments and frictional loads. Fourth, traditional clamps struggle to define a stable circumferential compression working section, resulting in unclear failure locations and effective bearing areas, leading to inconsistent calculation methods for circumferential compressive strength.

[0004] Therefore, there is a need for a testing device and method that can reliably connect with the pin chuck of the testing machine, reduce the influence of the preload of the fixture's own weight, perform arc contact loading and lateral limiting on the annular specimen, and form a clear circumferential compression working section. Summary of the Invention

[0005] The purpose of this invention is to provide a circumferential compression test apparatus and method for annular specimens, in order to solve the problems existing in the compression test of annular specimens, such as obvious local indentations, insufficient loading centering, the influence of the self-weight of the upper loading fixture on the initial loading, unstable lateral positioning of the specimen, and unclear calculation of circumferential compression strength.

[0006] To achieve the above objectives, the present invention provides a circumferential compression testing device for annular specimens. The device includes a base, a lower support assembly, an upper loading assembly, and an annular specimen positioning assembly. The lower support assembly is disposed on the base and includes a lower semi-circular support block. The upper loading assembly includes a cylindrical pin joint, a load-bearing connecting seat, an upper crossbeam, an intermediate loading plate, and an upper semi-circular loading block. The cylindrical pin joint has a radially arranged pin hole for connection with the pin clamp of the testing machine; the load-bearing connecting seat is disposed between the cylindrical pin joint and the upper crossbeam; the intermediate loading plate is connected below the upper crossbeam; and the upper semi-circular loading block is connected to the lower end of the intermediate loading plate. The upper semi-circular loading block and the lower semi-circular support block are arranged vertically opposite each other, and both contact the relative arc regions of the annular specimen to define the circumferential compression working section on the annular specimen. The annular specimen positioning assembly is disposed on the base or the lower support assembly to limit the lateral displacement of the annular specimen during loading.

[0007] In one embodiment, both the upper semicircular loading block and the lower semicircular support block are detachable structures, and the radius of their arc contact surfaces can be configured according to the outer diameter of the annular sample or the radius of the arc surface to be contacted. Thus, the device can be adapted to annular samples of different diameters, wall thicknesses, or axial widths.

[0008] In one embodiment, the relative position between the upper semicircular loading block and the lower semicircular support block causes the annular specimen to form a circumferential compression working section with a length of 8 mm to 15 mm, preferably 10 mm. This working section defines the free deformation zone and the main failure zone of the annular specimen.

[0009] In one embodiment, the load-bearing connection seat is a flange or a thickened platform, which is bolted to the upper crossbeam. Locating pins may be provided to improve the coaxiality or alignment between the cylindrical pin joint, the upper crossbeam, the intermediate loading plate, and the upper semi-circular loading block. A fillet transition may be provided between the cylindrical pin joint and the load-bearing connection seat to reduce stress concentration at the joint root.

[0010] In one embodiment, the annular specimen positioning assembly includes a lateral limiting block, a lateral support plate, a positioning groove, and a locking bolt. A 0.1 mm to 0.5 mm assembly gap is maintained between the lateral limiting block and the annular specimen, ensuring that the limiting structure only restricts lateral displacement of the specimen and does not participate in the main load-bearing.

[0011] The present invention also provides a method for circumferential compression testing of an annular specimen using the above-described device. The method includes: preparing and measuring the annular specimen; installing the lower support assembly and placing the annular specimen; adjusting the position of the annular specimen and the lateral limiting gap; connecting the upper loading assembly to the pin clamp of the testing machine via a cylindrical pin joint; bringing the upper semi-circular loading block into contact with the upper arc region of the annular specimen and applying a preload; performing circumferential compression loading according to a set loading rate and recording the load-displacement curve; obtaining the maximum compressive load and calculating the circumferential compressive strength based on the effective bearing cross-sectional area.

[0012] Specifically: The device of the present invention includes a base, a lower support assembly, an upper loading assembly, an annular sample positioning assembly, and a semi-circular loading / support block, wherein the semi-circular loading / support block includes an upper semi-circular loading block and a lower semi-circular loading block; the lower support assembly is disposed on the base; a support plate is disposed above the base for supporting the upper crossbeam and forming a clamp frame; the lower support assembly includes a lower semi-circular loading block for supporting the lower arc region of the annular sample to be tested; the upper loading assembly includes a cylindrical pin joint, a load-bearing connecting seat, an upper crossbeam, and an intermediate loading block. The test specimen includes a plate and an upper semi-circular loading block. A cylindrical pin joint is located above the upper crossbeam. The cylindrical pin joint has radially opened pin holes for connecting with the pin chuck of the testing machine. A bearing connecting seat is located between the cylindrical pin joint and the upper crossbeam. An intermediate loading plate is connected below the upper crossbeam, and the lower end of the intermediate loading plate is connected to the upper semi-circular loading block located above the semi-circular loading / support block. The intermediate loading plate is used to transfer the load from the upper crossbeam to the upper semi-circular loading block and keep the load application position corresponding to the target loading area of ​​the annular specimen.

[0013] The upper semicircular loading block and the lower semicircular support block of the semicircular loading / support block are arranged vertically opposite each other, and their arcuate contact surfaces respectively match the relative arcuate areas of the annular specimen to define a circumferential compression working section on the annular specimen. The upper semicircular loading block is connected to the intermediate loading plate and moves downward with the upper loading assembly. The lower semicircular support block is installed on the lower support assembly to support the annular specimen. Both are located on the inner side of the annular specimen, and their arcuate contact surfaces contact the inner arcuate areas on the upper and lower sides of the annular specimen, respectively.

[0014] The annular specimen positioning component is disposed on the base or the lower support component to limit the lateral displacement of the annular specimen during loading; when the cylindrical pin joint is connected to the testing machine pin chuck, the upper loading component is suspended and supported by the testing machine pin chuck before contacting the annular specimen.

[0015] Furthermore, both the upper semicircular loading block and the lower semicircular support block are detachable blocks. The radius of the arc contact surface of the upper semicircular loading block and the lower semicircular support block is configured according to the outer diameter of the annular sample or the radius of the arc surface to be contacted. The inner diameter of the annular sample is Di, and the radius of the arc contact surface of the upper semicircular loading block and the lower semicircular support block is R. Then, the dimensional relationship between the two is: R=Di / 2, that is, the radius of curvature of the arc contact surface matches the inner arc radius of the annular sample. The relative position between the upper semicircular loading block and the lower semicircular support block is set to make the circumferential compression working section have a length of 8 mm to 15 mm.

[0016] Furthermore, the cylindrical pin connector is a cylindrical structure with an outer diameter of 25 mm to 45 mm, and the diameter of the pin hole matches the diameter of the pin of the testing machine; a rounded transition is provided between the cylindrical pin connector and the bearing connection seat, and the radius of the rounded transition is 5 mm to 10 mm.

[0017] Furthermore, the bearing connection seat is a flange or a thickened platform, the outer diameter of which is 1.8 to 2.2 times the outer diameter of the cylindrical pin joint, and the thickness of which is 0.6 to 0.8 times the outer diameter of the cylindrical pin joint.

[0018] Furthermore, the load-bearing connecting seat is connected to the upper crossbeam by bolts, and a positioning pin is provided between the load-bearing connecting seat and the upper crossbeam to keep the center lines of the cylindrical pin joint, the intermediate loading plate and the upper semi-circular loading block consistent; the base may be provided with connecting holes, positioning grooves or other positioning structures to reliably connect with the lower platform of the testing machine; the intermediate loading plate may be provided with connecting holes for mating with connectors, pins or fasteners.

[0019] Furthermore, the annular specimen positioning assembly includes at least one of a lateral limiting block, a lateral support plate, a positioning groove, and a locking bolt. The lateral limiting block can be adjusted and locked in a direction close to or away from the annular specimen. An assembly gap of 0.1 mm to 0.5 mm is provided between the lateral limiting block and the annular specimen so that the lateral limiting block restricts the lateral displacement of the annular specimen and does not participate in the main load-bearing.

[0020] Furthermore, the cylindrical guide post, the limiting block connecting hole, and the positioning groove or guide structure that mates with the base constitute a lateral limiting structure; the cylindrical guide post is used to guide the lateral limiting block or adjustable limiting component, and the limiting block connecting hole is used to install, connect, or lock the lateral limiting block; the positioning groove on the base is used to limit the adjustment direction of the limiting component; through the lateral limiting structure, the position of the sample can be auxiliaryly limited when installing the annular sample.

[0021] The present invention also discloses a test method for the circumferential compression test apparatus for the annular specimen, comprising the following steps:

[0022] Prepare an annular specimen and measure its axial width, wall thickness, inner diameter, and outer diameter.

[0023] The lower support assembly is fixed to the lower platform or lower clamp of the testing machine, and the annular specimen is placed on the lower semicircular support block;

[0024] Adjust the position of the annular specimen so that the center line of the annular specimen is aligned with the center line of the lower semicircular support block; adjust the annular specimen positioning assembly so that the annular specimen is limited on both sides in the loading direction.

[0025] The upper loading component is connected to the testing machine pin chuck via the cylindrical pin joint, so that the upper loading component is suspended and supported by the testing machine pin chuck before it officially contacts the annular specimen; the testing machine is controlled to make the upper semi-circular loading block contact the upper arc area of ​​the annular specimen, apply a preload to eliminate assembly gaps and zero displacement;

[0026] Perform circumferential compression loading according to the set loading rate and record the load-displacement curve;

[0027] Obtain the maximum compressive load during the test, and calculate the circumferential compressive strength based on the maximum compressive load and the effective bearing cross-sectional area of ​​the annular specimen.

[0028] Furthermore, when adjusting the annular sample positioning assembly, an assembly gap of 0.1 mm to 0.5 mm is maintained between the lateral limiting block and the annular sample.

[0029] Furthermore, the circumferential compressive strength is calculated according to the formula Xθc=Pmax / (nAe), where Xθc is the circumferential compressive strength, Pmax is the maximum compressive load, Ae is the bearing cross-sectional area of ​​a single effective working segment, and n is the number of effective working segments participating in the bearing.

[0030] When the annular specimen has two symmetrical effective circumferential compression working sections and Ae=bt, the circumferential compression strength is calculated according to the formula Xθc=Pmax / (2bt), where b is the axial width of the annular specimen and t is the wall thickness of the annular specimen.

[0031] When the annular specimen has only one effective circumferential compression working section and Ae=bt, the circumferential compression strength is calculated according to the formula Xθc=Pmax / (bt), where b is the axial width of the annular specimen and t is the wall thickness of the annular specimen.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects: First, the cylindrical pin joint is connected to the pin clamp of the testing machine, so that the upper loading component is suspended and supported by the testing machine before contacting the specimen, which can reduce the uncontrolled preload of the specimen by the self-weight of the upper loading component; Second, the upper semi-circular loading block and the lower semi-circular support block adopt arc contact loading, which can reduce local indentation and contact stress concentration caused by flat pressure plate or local pressure head; Third, the intermediate loading plate and the upper and lower semi-circular blocks form a clear load transfer path, which is conducive to improving loading centering and failure mode stability; Fourth, the lateral limiting structure restricts the lateral displacement of the specimen while retaining the gap, which can reduce the influence of additional friction load and additional bending moment; Fifth, by defining the circumferential compression working section and giving the effective bearing cross-sectional area calculation method, the comparability of circumferential compression strength test results can be improved. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of a circumferential compression testing device for an annular specimen according to the present invention, wherein the left side is a three-dimensional structural diagram and the right side is a front view structural diagram. To clearly show the fixture body structure, Figure 1 The annular sample to be tested is not shown.

[0034] Explanation of reference numerals in the attached drawings: 1-Upper crossbeam; 2-Intermediate loading plate; 3-Supporting upright plate; 4-Flange; 5-Semi-circular loading / support block; 6-Base; 7-Cylindrical guide column; 8-Pin hole; 9-Connecting hole; 10-Loading plate connecting hole; 11-Cylindrical pin joint. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the following embodiments are only for illustrating the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Where there is no conflict, the technical features of the various embodiments of the present invention can be combined with each other.

[0036] like Figure 1 As shown, the annular specimen circumferential compression test device of this embodiment includes an upper crossbeam 1, an intermediate loading plate 2, a support plate 3, a flange 4, a semi-circular loading / support block 5, a base 6, a cylindrical guide column 7, a pin hole 8, a connecting hole 9, and a limiting block connecting hole 10. It should be noted that... Figure 1 This is a schematic diagram of the fixture body structure. The annular specimen placed between the semicircular loading / support blocks 5 during the test is not shown.

[0037] The base 6 is used for mounting on the lower platform or lower fixture of the testing machine. The base 6 may be provided with connecting holes, positioning slots, or other positioning structures to ensure reliable connection with the lower platform of the testing machine. The support plate 3 is positioned above the base 6 to support the upper crossbeam 1 and form the fixture frame. The semi-circular loading / support block 5, located at the bottom, is positioned on the base 6 or the support plate 3 to support the lower arc-shaped area of ​​the annular specimen during loading.

[0038] The upper loading assembly includes a cylindrical pin joint, a flange 4, an upper crossbeam 1, an intermediate loading plate 2, and a semi-circular loading / support block 5 located at the top. The cylindrical pin joint is positioned above the flange 4 and has a radially penetrating pin hole 8 for engaging with the pin of the testing machine's pin chuck. This connection method allows the upper loading assembly to be suspended and supported by the upper chuck of the testing machine before it comes into direct contact with the annular specimen, thus reducing the preload effect caused by the upper loading assembly's own weight directly pressing on the annular specimen.

[0039] Flange 4 is located between the cylindrical pin joint and the upper crossbeam 1. Flange 4 can be integrally machined with the cylindrical pin joint, or it can be connected by welding, bolting, or other fixed connection methods. Flange 4 is used to transfer the load from the pin clamp of the testing machine to the upper crossbeam 1 and to improve the load-bearing rigidity of the joint.

[0040] In one specific embodiment, the outer diameter of the cylindrical pin connector is 31 mm, and the diameter of the pin hole 8 is determined according to the pin diameter of the testing machine. When the pin diameter of the testing machine is 12 mm, the pin hole 8 can be machined to be 12.1 mm to 12.2 mm. The outer diameter of the flange 4 can be 60 mm to 65 mm, and the thickness can be 20 mm to 25 mm. A fillet transition of R5 mm to R8 mm can be provided between the cylindrical pin connector and the flange 4.

[0041] A middle loading plate 2 is connected below the upper crossbeam 1, and the lower end of the middle loading plate 2 is connected to the semi-circular loading / support block 5 located at the top. The middle loading plate 2 is used to transfer the load from the upper crossbeam 1 to the semi-circular loading / support block 5, and to keep the load application position corresponding to the target loading area of ​​the annular specimen. A connecting hole 9 may be provided on the middle loading plate 2 for mating with connectors, pins, or fasteners.

[0042] Two semicircular loading / support blocks 5 are arranged vertically opposite each other. During loading, the upper semicircular loading / support block 5 contacts the upper arc region of the annular specimen, and the lower semicircular loading / support block 5 contacts the lower arc region of the annular specimen. Together, they form an arc-shaped contact loading effect on the annular specimen. By adjusting the relative positions of the two semicircular loading / support blocks 5 or by selecting semicircular blocks of different sizes, a circumferential compression working section can be defined in the annular specimen. The length of the circumferential compression working section can be from 8 mm to 15 mm, preferably 10 mm.

[0043] The lateral limiting structure may include a cylindrical guide post 7, a limiting block connecting hole 10, and a positioning groove or guide structure that mates with the base 6. The cylindrical guide post 7 is used to guide the lateral limiting block or adjustable limiting component, and the limiting block connecting hole 10 is used to install, connect, or lock the lateral limiting block. Before the test, the lateral limiting block is brought close to both sides of the annular specimen, with an assembly gap of 0.1 mm to 0.5 mm maintained between the lateral limiting block and the annular specimen. This gap allows the lateral limiting structure to limit significant lateral displacement of the annular specimen, while preventing the lateral limiting structure from sharing the main compressive load or introducing excessive frictional load during loading.

[0044] When performing a circumferential compression test using this device, a ring-shaped specimen is first prepared from a pipe or ring-shaped component, and its outer diameter, inner diameter, wall thickness t, and axial width b are measured. Then, the base 6 is fixed to the lower platform of the testing machine, the lower semi-circular loading / support block 5 is installed on the base 6 or the support plate 3, and the ring-shaped specimen is placed on the lower semi-circular loading / support block 5, so that the center line of the ring-shaped specimen is aligned with the center line of the lower semi-circular loading / support block 5.

[0045] The position of the lateral limiting block is then adjusted via the cylindrical guide post 7 and the limiting block connection hole 10 to maintain a predetermined assembly gap between the lateral limiting block and the annular specimen. The upper loading assembly is connected to the testing machine's pin chuck via a cylindrical pin joint and pin hole 8, confirming that the pin connection is reliable and that the upper loading assembly can move up and down with the testing machine's upper chuck. The testing machine's upper chuck is then slowly lowered until the upper semi-circular loading / support block 5 contacts the upper arc region of the annular specimen. A preload of 50 N to 200 N is applied to eliminate the assembly gap, and the displacement is zeroed after the preload.

[0046] After completing the above steps, perform circumferential compression loading according to the set loading rate. The loading rate can be determined based on the size of the annular specimen, material type, and test standard requirements; displacement control is preferred. The load-displacement curve is recorded synchronously during loading. When the annular specimen shows significant failure, the load drops significantly, or the set termination condition is reached, the test is stopped, and the maximum compressive load Pmax is read from the load-displacement curve.

[0047] In this embodiment, the circumferential compressive strength of the annular specimen can be calculated according to the following formula: Xθc = Pmax / (nAe). Where Xθc is the circumferential compressive strength, Pmax is the maximum compressive load, Ae is the cross-sectional area of ​​a single effective working segment, and n is the number of effective working segments participating in the load-bearing process. When the annular specimen has two symmetrical effective circumferential compressive working segments and Ae = bt, the circumferential compressive strength can be calculated as Xθc = Pmax / (2bt). When the annular specimen has only one effective circumferential compressive working segment and Ae = bt, the circumferential compressive strength can be calculated as Xθc = Pmax / (bt).

[0048] Explanation of key symbols in this invention:

[0049] Xθc Circumferential compressive strength or apparent circumferential compressive strength MPa Pmax Maximum compressive load obtained during the test N Ae The load-bearing cross-sectional area of ​​a single effective working section mm² n Number of effective working segments involved in the operation - b axial width of the annular specimen mm t Annular sample wall thickness mm

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A circumferential compression test apparatus for annular specimens, characterized in that, The device includes a base (6), a lower support assembly, an upper loading assembly, an annular sample positioning assembly, and a semi-circular loading / support block (5), wherein the semi-circular loading / support block (5) includes an upper semi-circular loading block and a lower semi-circular loading block; The lower support assembly is disposed on the base (6); the support plate (3) is disposed above the base (6) to support the upper crossbeam (1) and form a clamp frame; The lower support assembly includes a lower semi-circular loading block for supporting the lower arc region of the annular specimen to be tested; the upper loading assembly includes a cylindrical pin joint (11), a bearing connecting seat, an upper crossbeam (1), an intermediate loading plate (2), and an upper semi-circular loading block. The cylindrical pin joint (11) is located above the upper crossbeam (1), and the cylindrical pin joint (11) has a pin hole (8) radially provided for connecting with the pin chuck of the testing machine. The bearing connecting seat is located between the cylindrical pin joint (11) and the upper crossbeam (1). The intermediate loading plate (2) is connected below the upper crossbeam (1). The lower end of the intermediate loading plate (2) is connected to the upper semi-circular loading block located on the upper part of the semi-circular loading / support block (5); the intermediate loading plate (2) is used to transfer the load from the upper crossbeam 1 to the upper semi-circular loading block and keep the load application position corresponding to the target loading area of ​​the annular specimen. The upper semicircular loading block and the lower semicircular support block in the semicircular loading / support block (5) are arranged opposite each other, and their arc contact surfaces are respectively matched with the relative arc areas of the annular sample to define the circumferential compression working section on the annular sample. The annular specimen positioning component is disposed on the base (6) or the lower support component to limit the lateral displacement of the annular specimen during loading; when the cylindrical pin joint is connected to the pin chuck of the testing machine, the upper loading component is suspended and supported by the pin chuck of the testing machine before contacting the annular specimen.

2. The annular specimen circumferential compression test apparatus according to claim 1, characterized in that, Both the upper semicircular loading block and the lower semicircular support block are detachable blocks. The radius of the arc contact surface of the upper semicircular loading block and the lower semicircular support block is configured according to the outer diameter of the annular sample or the radius of the arc surface to be contacted. The inner diameter of the annular sample is Di, and the radius of the arc contact surface of the upper semicircular loading block and the lower semicircular support block is R. Then the dimensional relationship between the two is: R=Di / 2, that is, the radius of curvature of the arc contact surface matches the inner arc radius of the annular sample. The relative position between the upper semicircular loading block and the lower semicircular support block is set to make the circumferential compression working section have a length of 8 mm to 15 mm.

3. The annular specimen circumferential compression test apparatus according to claim 1, characterized in that, The cylindrical pin joint (11) is a cylindrical structure with an outer diameter of 25 mm to 45 mm. The diameter of the pin hole (8) matches the diameter of the pin of the testing machine. A rounded transition is provided between the cylindrical pin joint and the bearing connection seat, with a radius of 5 mm to 10 mm.

4. The annular specimen circumferential compression test apparatus according to claim 1, characterized in that, The bearing connection seat is a flange (4) or a thickened platform. The outer diameter of the flange (4) or the thickened platform is 1.8 to 2.2 times the outer diameter of the cylindrical pin joint, and the thickness of the flange (4) or the thickened platform is 0.6 to 0.8 times the outer diameter of the cylindrical pin joint.

5. The annular specimen circumferential compression test apparatus according to claim 1, characterized in that, The bearing connecting seat is connected to the upper crossbeam by bolts, and a positioning pin is provided between the bearing connecting seat and the upper crossbeam to keep the center lines of the cylindrical pin joint, the intermediate loading plate and the upper semi-circular loading block consistent; the base (6) may be provided with a connecting hole (9), a positioning groove or other positioning structure to reliably connect with the lower platform of the testing machine; the intermediate loading plate (2) may be provided with a connecting hole (9) for cooperating with the connecting parts, pins or fasteners.

6. The annular specimen circumferential compression test apparatus according to claim 1, characterized in that, The annular specimen positioning assembly includes at least one of a lateral limiting block, a lateral support plate, a positioning groove, and a locking bolt. The lateral limiting block can be adjusted and locked in a direction close to or away from the annular specimen. An assembly gap of 0.1 mm to 0.5 mm is provided between the lateral limiting block and the annular specimen so that the lateral limiting block restricts the lateral displacement of the annular specimen and does not participate in the main load-bearing.

7. The annular specimen circumferential compression test apparatus according to claim 6, characterized in that, The cylindrical guide post (7), the limiting block connecting hole (10), and the positioning groove or guide structure that cooperates with the base (6) constitute the lateral limiting structure; the cylindrical guide post (7) is used to guide the lateral limiting block or adjustable limiting component, and the limiting block connecting hole (10) is used to install, connect or lock the lateral limiting block; the positioning groove on the base (6) is used to limit the adjustment direction of the limiting component; through the lateral limiting structure, the position of the sample can be assisted in limiting when installing the annular sample.

8. A test method using the annular specimen circumferential compression test apparatus according to any one of claims 1 to 7, characterized in that, Includes the following steps: Prepare an annular specimen and measure its axial width, wall thickness, inner diameter, and outer diameter. The lower support assembly is fixed to the lower platform or lower clamp of the testing machine, and the annular specimen is placed on the lower semicircular support block; Adjust the position of the annular specimen so that the center line of the annular specimen is aligned with the center line of the lower semicircular support block; adjust the annular specimen positioning assembly so that the annular specimen is limited on both sides in the loading direction. The upper loading component is connected to the testing machine pin chuck via the cylindrical pin joint, so that the upper loading component is suspended and supported by the testing machine pin chuck before it officially contacts the annular specimen; the testing machine is controlled to make the upper semi-circular loading block contact the upper arc area of ​​the annular specimen, apply a preload to eliminate assembly gaps and zero displacement; Perform circumferential compression loading according to the set loading rate and record the load-displacement curve; Obtain the maximum compressive load during the test, and calculate the circumferential compressive strength based on the maximum compressive load and the effective bearing cross-sectional area of ​​the annular specimen.

9. The test method according to claim 8, characterized in that, When adjusting the annular specimen positioning assembly, a gap of 0.1 mm to 0.5 mm is maintained between the lateral limiting block and the annular specimen.

10. The test method according to claim 8, characterized in that, The circumferential compressive strength is calculated according to the formula Xθc=Pmax / (nAe), where Xθc is the circumferential compressive strength, Pmax is the maximum compressive load, Ae is the bearing cross-sectional area of ​​a single effective working segment, and n is the number of effective working segments participating in the bearing. When the annular specimen has two symmetrical effective circumferential compression working sections and Ae=bt, the circumferential compression strength is calculated according to the formula Xθc=Pmax / (2bt), where b is the axial width of the annular specimen and t is the wall thickness of the annular specimen. When the annular specimen has only one effective circumferential compression working section and Ae=bt, the circumferential compression strength is calculated according to the formula Xθc=Pmax / (bt), where b is the axial width of the annular specimen and t is the wall thickness of the annular specimen.

Images