Device and method for testing torsional shear mechanical property of hollow cylinder structure

Abstract

The invention discloses a torsional shear mechanical property testing device and method for a hollow cylinder structure, and belongs to the technical field of mechanical structure testing. The device comprises an axial driving mechanism, a radial driving mechanism and a fixed supporting mechanism. The axial driving mechanism is connected with the axial actuating pressure plate through an actuating main shaft; the radial driving mechanism comprises a radial driving mandrel of an inverted conical structure and a driving sliding plate matched with the radial driving mandrel, and axial movement of the main shaft is converted into radial expansion movement through conical face fit. The fixed supporting mechanism is a closed supporting system composed of an outer sleeve, an upper cover plate and a base. Through the unique inverted conical structure design, independent or synchronous application of axial compression, radial expansion and torsional shear loads can be achieved, and the complex stress working condition is effectively simulated. The device has the advantages of being stable in structure, high in testing precision, easy and convenient to operate and the like, meanwhile, equipment universality and maintenance convenience are remarkably improved through the replaceable design of the driving sliding plate, and the device is suitable for mechanical property testing of various hollow cylindrical structural parts.

Description

Technical Field

[0001] This invention belongs to the technical field of mechanical performance testing devices, and particularly relates to a testing device and method for testing the torsional shear mechanical properties of a hollow cylindrical structure. Background Technology

[0002] In modern industrial structures, tubular structures are a common form of basic load-bearing and functional transmission. Their hollow circular tube shape, due to its excellent mechanical properties and multifunctional integration capabilities, is widely used in critical fields requiring high safety and stability. For example, chemical fluid transportation pipelines, automotive transmission linkages, precision machine tool support guides, and experimental instrument clamping components all rely on hollow circular tubes to achieve force transmission, structural support, and media transport. These structures often withstand complex loads in actual working conditions, and their torsional and shear mechanical properties are key indicators for evaluating their reliability, durability, and safety margins.

[0003] However, due to the significant differences in materials, dimensions, wall thickness, and connection methods of hollow cylindrical structures, as well as their diverse application scenarios and complex stress environments, existing testing devices often suffer from low versatility and poor adaptability, making it difficult to efficiently and accurately complete torsional shear performance tests on specimens of various specifications. Currently, the mechanical evaluation of various tubular components typically relies on dedicated test benches or the repeated construction of testing systems, resulting in problems such as long testing cycles, insufficient system compatibility, and difficulty in ensuring data consistency. Therefore, there is an urgent need for a specialized testing device that can adapt to various hollow cylindrical structures and integrate torsional shear loading and measurement functions to improve testing efficiency, unify evaluation standards, ensure structural design quality and operational safety, thereby meeting the pressing needs of modern industry for high-performance testing and reliability verification of tubular components. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a testing device and method for testing the torsional shear mechanical properties of a hollow cylindrical structure, which solves the problems of low versatility, poor adaptability, and long testing cycle of existing testing devices.

[0005] This invention is implemented as follows: a testing device for the torsional shear mechanical properties of a hollow cylindrical structure, characterized by comprising an axial drive mechanism, a radial drive mechanism, and a fixed support mechanism; the axial drive mechanism provides an axial test load; the radial drive mechanism converts the axial motion provided by the axial drive mechanism into radial expansion motion to apply a radial load to the inner wall of the hollow cylindrical specimen; the radial drive mechanism includes a radial drive spindle and multiple drive slide plates; the fixed support mechanism provides motion guidance for the radial drive mechanism and supports the entire device; the radial drive spindle is connected to the axial drive mechanism to receive axial motion, and its outer wall is an inverted conical structure with a larger upper part and a smaller lower part; the inner wall of the drive slide plates is provided with an inverted conical structure that matches the outer wall of the radial drive spindle, forming a conical mating pair, so that the downward axial motion of the radial drive spindle can be converted into the outward radial motion of the drive slide plates; the drive slide plates are provided with rolling elements, forming a rolling friction pair with the fixed support mechanism.

[0006] The hollow cylindrical structure torsion-shear mechanical performance testing device provided by this invention, based on mechanical design theory, transmission theory, and dynamic design theory, exhibits comprehensive advantages through scientific overall design and innovative detailed structure. The device adopts a design concept of coordinated operation of axial drive, radial drive, and fixed support. The axial drive section uses multiple double-ended studs to form a stable three-point support structure between the actuating spindle and the axial actuating pressure plate, significantly improving system stiffness and load uniformity. The radial drive section innovatively utilizes an inverted conical structure combined with a T-shaped transmission mechanism to efficiently and accurately convert axial linear motion into radial expansion motion, achieving uniform loading of the specimen's inner wall. Simultaneously, rolling elements on the upper and lower end faces of the drive slide effectively reduce motion friction, ensuring high precision and efficiency in the testing process. The fixed section adopts a closed rigid support structure, providing a stable installation benchmark and reliable safety protection for the entire testing system.

[0007] This device not only boasts a scientifically sound structural design and stable, reliable operation, but also possesses powerful testing capabilities and wide applicability. It can independently or simultaneously perform various mechanical property tests, including axial compression, radial expansion, and torsional shear, perfectly simulating complex stress conditions in actual engineering projects. Its modular design, particularly the quick-change feature of the drive slide, allows the equipment to flexibly adapt to specimens of different sizes and specifications, significantly improving testing efficiency. In summary, this device combines the advantages of simple structure, convenient operation, accurate testing, and high safety and reliability, greatly improving the testing methods for hollow cylindrical structures, enhancing testing accuracy and safety. It has significant application value and broad market prospects in industrial fields such as machinery manufacturing, civil engineering, and petrochemicals.

[0008] In the above technical solution, preferably, the drive slide plate and the radial drive spindle are connected by a separable sliding pair, so that the drive slide plate can be disassembled and replaced.

[0009] In the above technical solution, preferably, the separable sliding pair is a mating structure consisting of T-shaped protrusions evenly distributed along the circumferential direction on the radial drive spindle and T-shaped grooves provided on the drive slide plate.

[0010] In the above technical solution, preferably, the axial drive mechanism includes an actuating spindle and an axial actuating pressure plate. The actuating spindle is connected to the axial actuating pressure plate through multiple connecting parts, and the actuating spindle has a connecting part at its center for connecting to the radial drive spindle.

[0011] In the above technical solution, preferably, the outer side of the actuating spindle is provided with a multi-jaw structure for connecting with the axial actuating pressure plate through multiple connecting parts to form a multi-jaw axial drive system.

[0012] In the above technical solution, preferably, the fixed support mechanism includes: The outer sleeve forms the main framework of the device; The upper cover plate is connected to the upper part of the outer sleeve; The base is connected to the lower part of the outer sleeve and is used to fix the entire device to the workbench; The top cover and the base together provide guiding constraints for the radial movement of the drive slide plate.

[0013] In the above technical solution, preferably, the rolling elements provided on the upper and lower end faces of the drive slide plate are balls, and the lower surface of the upper cover plate and the upper surface of the base form a smooth track for the balls to move.

[0014] In the above technical solution, preferably, the axial drive mechanism and the radial drive mechanism can be driven by the actuating spindle to operate individually or together, so as to independently apply axial compressive load, radial internal support load or synchronously apply composite load.

[0015] In the above technical solution, preferably, it further includes a data acquisition system, which includes a sensor for detecting at least one parameter among torque, axial force and displacement, and the sensor is disposed on the axial drive mechanism.

[0016] A second objective of this invention is to provide a method for testing the mechanical properties of a hollow cylindrical structure using the aforementioned apparatus, characterized by comprising the following steps: The test specimen is fitted onto the outside of the fixed support mechanism; Drive the axial drive mechanism to move downward; The downward movement of the radial drive spindle and its inverted conical structure force the drive slide plate to expand radially outward until it contacts the inner wall of the specimen and applies a set radial load. The downward movement of the axially actuated pressure plate applies a set axial load to the end face of the specimen. Real-time acquisition of mechanical parameters during the testing process; The steps of applying axial load and radial load can be performed individually or simultaneously. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the actuating spindle in this invention; Figure 3 This is a schematic diagram of the double-ended stud in this invention; Figure 4 This is a schematic diagram of the axially actuated pressure plate in this invention; Figure 5 This is a schematic diagram of the radial drive mandrel in this invention; Figure 6 This is a schematic diagram of the structure of the drive slide plate in this invention; Figure 7 This is a schematic diagram of the structure of the three-arm cover plate in this invention; Figure 8 This is a schematic diagram of the outer sleeve structure in this invention; Figure 9 This is a schematic diagram of the base structure in this invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] To address existing shortcomings, this invention provides a testing device and method for testing the torsional shear mechanical properties of a hollow cylindrical structure. To further illustrate the structure of this invention, a detailed description is provided below in conjunction with the accompanying drawings: Example 1, Please see Figure 1-9 A test device for the torsional shear mechanical properties of a hollow cylindrical structure, mainly comprising an axial drive mechanism, a radial drive mechanism, and a fixed support mechanism.

[0020] The axial drive mechanism is used to provide axial test loads. It consists of an actuating spindle 1 and an axial actuating pressure plate 3. The outer side of the actuating spindle 1 has a typical three-jaw structure, with bolt holes on each jaw. Three double-ended studs 2 pass through these bolt holes, connecting the actuating spindle 1 and the axial actuating pressure plate 3 to form a stable three-jaw axial drive system. The connection is secured with lock nuts to prevent loosening under vibration. The actuating spindle 1 also has a central bolt hole for connecting a radial drive mechanism.

[0021] The radial drive mechanism converts the axial motion of the actuating spindle 1 into radial expansion motion. Its core comprises a radial drive spindle 4 and three drive slide plates 5. The radial drive spindle 4 is fixedly connected to the central bolt hole of the actuating spindle 1 via a threaded structure at its top. The outer wall of the radial drive spindle 4 is an inverted conical structure, wider at the top and narrower at the bottom. Three protruding T-shaped blocks are evenly distributed along its circumference. Each T-shaped block mates with one drive slide plate 5. The inner wall of the drive slide plate 5 is an inner conical structure matching the taper of the outer wall of the radial drive spindle 4, with a conical T-groove machined at its center. The T-shaped blocks are embedded in the T-groove, forming a separable sliding pair connection, allowing the drive slide plates 5 to be individually disassembled and replaced. When the actuating spindle 1 drives the radial drive spindle 4 downwards, the downward axial motion is forcibly converted into a synchronous and uniform outward radial motion of the drive slide plates 5 through the action of these mating inverted conical surfaces.

[0022] The fixed support mechanism provides support and guidance for the entire device. It consists of an outer sleeve 7, a three-arm cover plate 6, and a base 8. The outer sleeve 7 serves as the skeleton of the entire device. The three-arm cover plate 6 is bolted to the upper end face of the outer sleeve 7, and the base 8 is bolted to the lower end face of the outer sleeve 7, together forming a closed, highly rigid support system. The lower part of the base 8 is provided with mounting holes, which can be firmly fixed to an external workbench using high-strength bolts. To ensure smooth radial movement of the drive slide plate 5 and minimize friction, several rolling balls are embedded in the upper and lower end faces of each drive slide plate 5. These balls use the smooth lower surface of the three-arm cover plate 6 and the smooth upper surface of the boss of the base 8 as tracks, forming a highly efficient rolling friction pair.

[0023] Working principle: An external actuator drives the actuating spindle 1 downwards. This motion is simultaneously transmitted through two paths: (Path 1) The double-ended stud 2 pushes the axial actuating pressure plate 3, applying an axial compressive load to the end face of the specimen, compressing and deforming it, and continuing to compress it; (Path 2) The radial drive spindle 4 is pulled downwards, forcing the three drive slide plates 5 to expand radially outwards through its inverted conical surface, thus internally tightening the inner wall of the compressed specimen to apply a radial load. If the spindle rotates simultaneously, torque is transmitted to the drive slide plates 5 through the T-slot, generating shear stress. Force sensors, displacement sensors, and torque sensors mounted on the actuating spindle 1 can collect and analyze all mechanical parameters in real time.

[0024] This comprehensive loading test on cylindrical specimens under axial compression, radial internal support, and torsional loads can realistically simulate the complex stress states experienced by hollow circular tube structures in actual working conditions, such as the stress behavior of pressure vessels, pipe joints, marine risers, and composite material pipe fittings under compression, bulging, and torsional loads, under laboratory conditions. By simultaneously testing axial force-displacement, radial force-displacement, and shear force-rotation, the stress-strain relationship, yield and failure modes, and cooperative deformation characteristics of the material under multiaxial coupled loads can be obtained. This provides experimental basis for optimizing pipe material selection, wall thickness design, strength assessment of connection structures, and fatigue life prediction, thereby improving the safety and reliability of hollow circular tube structures under high pressure, high torsion, and dynamic load environments.

[0025] Example 2: This embodiment further optimizes and integrates the data acquisition system based on the structure of Embodiment 1.

[0026] The device in this embodiment has the same axial drive mechanism, radial drive mechanism, and fixed support mechanism as in Embodiment 1. The improvement lies in the additional integration of a high-precision sensing and measurement unit onto the input flange of the actuating spindle 1. This unit includes: A torque sensor is used to measure and feedback the input spindle torque in real time; An axial force sensor is used to measure and provide feedback on the applied axial load in real time. A displacement sensor (such as a linear encoder or LVDT) is used to monitor the axial displacement stroke of the actuating spindle 1 in real time.

[0027] All sensors are connected to an external data acquisition unit via shielded cables. The data acquisition unit communicates with a host computer via USB or Ethernet interface. Dedicated control and analysis software runs on the host computer, which is capable of: Real-time display of curves such as torque-time, axial force-displacement, and radial displacement-time; Set up test programs, such as force control, displacement control, and their hybrid control modes; Record and store all raw data, and automatically calculate and generate reports on key mechanical properties of the material, such as yield strength, elastic modulus, and shear strength, after the test is completed.

[0028] Example 3: This embodiment aims to explain in detail the specific implementation of the drive skateboard 5 as a detachable accessory and the resulting technical effects.

[0029] The main structure of the device in this embodiment is the same as that in Embodiment 1. Its core lies in the detachable connection design between the drive slide plate 5 and the radial drive spindle 4.

[0030] The specific disassembly and replacement procedure is as follows: Loosen the bolts connecting the three-arm cover plate 6 and the outer sleeve 7, and remove the entire upper cover plate assembly.

[0031] At this point, the internal radial drive mechanism is fully exposed. Manually pull the radial drive spindle 4 upward to its highest point, and the drive slide plate 5 will retract inward to its minimum diameter.

[0032] The operator can use their hands or tools to slide the drive slide plate 5 directly off the T-shaped block of the radial drive spindle 4 along the axial direction to complete the disassembly.

[0033] To test a new specimen with a smaller inner diameter, a drive slide plate 5 with the same outer dimensions but increased thickness can be prepared. Align the T-slot inside the slide plate with the T-strip of the mandrel and slide it in axially to complete the replacement.

[0034] Finally, reinstall the three-arm cover plate 6 and tighten the bolts, and the device has completed the adaptation adjustment.

[0035] Beneficial effects: This design allows a single main unit to adapt to the testing needs of hollow cylindrical specimens with different inner diameters and wall thicknesses within a range by replacing different series and sizes of drive slide plates 5. This not only greatly expands the versatility of the device, but also, when the working surface of the drive slide plate 5 wears due to long-term use, only these slide plate components need to be replaced, without scrapping the expensive core spindle and mandrel components, significantly reducing the long-term maintenance costs of the equipment.

[0036] Example 4: This embodiment describes in detail a method for testing the mechanical properties of a hollow cylindrical structure using the device described in this invention, which corresponds to the technical solution protected by claim 10.

[0037] Test preparation phase: First, the operator selects and installs a suitable drive slide plate 5 based on the inner diameter of the hollow cylindrical specimen to be tested. As described in Example 3, the selected drive slide plate 5 is slid axially onto the T-shaped block of the radial drive spindle 4, ensuring proper fit. Then, the three-arm cover plate 6 and the outer sleeve 7 are fastened with bolts to complete the assembly of the device. The assembled device is then securely mounted on the worktable of the material testing machine using high-strength bolts through the mounting holes of the base 8.

[0038] Test execution phase: Specimen clamping: Carefully place the hollow cylindrical specimen onto the outside of the fixed support mechanism, ensuring that there is an appropriate gap between the inner wall of the specimen and the drive slide plate 5, and that the upper end face of the specimen is aligned with the axially actuating pressure plate 3.

[0039] Applying load: Start the material testing machine, driving the actuated spindle 1 downward. This single input motion is simultaneously distributed to two load paths: Application of radial inner support load: The downward movement of the actuating spindle 1 drives the radial drive spindle 4 to move downward synchronously. Due to its inverted conical structure, the downward movement of the spindle 4 forces the drive slide plate 5, which is in contact with its conical surface, to overcome rolling friction and expand radially outward until it is in complete contact with the inner wall of the specimen and applies the preset radial expansion load.

[0040] Application of axial compressive load: The downward movement of the actuating spindle 1 simultaneously pushes the axially actuating pressure plate 3 through the double-ended stud 2, so that it applies a downward axial compressive load to the upper end face of the specimen.

[0041] (Optional) Application of torsional shear load: If a torsional shear test is required, the material testing machine is controlled to apply a rotational torque to the actuating spindle 1 while providing downward pressure. This torque is transmitted to the drive slide plate 5 through the T-shaped blocks on the radial drive spindle 4, and is ultimately converted into shear stress on the inner wall of the specimen.

[0042] Load control mode: The steps of applying axial and radial loads described above can be performed individually under the control of the testing machine, depending on the experimental design (e.g., performing only a pure axial compression or pure radial expansion test), or simultaneously to simulate complex working conditions with combined loads. The test can adopt force control, displacement control, or hybrid control modes.

[0043] Data Acquisition and Monitoring: Throughout the loading process, the torque sensor, axial force sensor, and displacement sensor installed on the actuating spindle 1 continuously operate, acquiring torque, axial force, axial displacement, and radial displacement data calculated by algorithms in real time. All data is transmitted in real time to the data acquisition instrument and the host computer software. The software interface synchronously displays key information such as load-displacement curves and torque-rotation angle curves, allowing the operator to monitor the experimental progress.

[0044] Test End and Reset: Once the preset loading conditions are reached or the specimen fails, the testing machine stops loading. The control actuation spindle 1 moves upward, driving the radial drive spindle 4 upward. Due to its inverted conical structure, the drive slide plate 5 retracts radially inward under guiding constraints, disengaging from the specimen (or specimen debris). The specimen is removed, the device is cleaned, and preparation for the next test is made.

[0045] Advantages of the method: This testing method efficiently and synchronously excites both radial and axial loads through a single, controllable downward axial drive, perfectly replicating the complex stress states that hollow cylindrical structures may experience in practical applications. This method simplifies complex multi-axis loading tests into easily controllable single-axis drives, significantly improving testing efficiency, repeatability, and accuracy. It is particularly suitable for studying the mechanical properties of components such as pipes, bushings, and shaft sleeves under combined loads.

[0046] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0047] This embodiment integrates the mechanical body with the measurement and control system to form a complete and intelligent experimental system for testing the mechanical properties of materials, which greatly improves the automation level of the test and the reliability of the results.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hollow cylindrical structure torsional shear mechanical property testing device, characterized in that, Comprise: an axial driving mechanism for providing axial test load; a radial driving mechanism for converting axial movement provided by the axial driving mechanism into radial expansion movement to exert radial load on the inner wall of the hollow cylindrical structure specimen; the radial driving mechanism comprises a radial driving mandrel and a plurality of driving sliding plates; a fixed support mechanism for providing movement guidance for the radial driving mechanism and support for the entire device; the radial driving mandrel is connected with the axial driving mechanism to receive axial movement, and the outer wall thereof is in an inverted conical structure with the upper part larger and the lower part smaller; the inner wall of the driving sliding plate is provided with an inverted conical structure matched with the outer wall of the radial driving mandrel to form a conical surface matching pair, so that the downward axial movement of the radial driving mandrel can be converted into the outward radial movement of the driving sliding plate; the driving sliding plate is provided with rolling elements to form a rolling friction pair with the fixed support mechanism.

2. The hollow cylinder structure torsional shear mechanical property testing device of claim 1, wherein, the driving sliding plate is connected with the radial driving mandrel through a separable sliding pair, so that the driving sliding plate can be detached and replaced.

3. The hollow cylinder structure torsional shear mechanical property testing device of claim 2, wherein, the separable sliding pair is a matching structure of T-shaped protrusions uniformly distributed on the radial driving mandrel in the circumferential direction and T-shaped grooves provided on the driving sliding plate.

4. The hollow cylinder structure torsional shear mechanical property testing device of claim 1, wherein, the axial driving mechanism comprises an actuating main shaft and an axial actuating pressure plate, the actuating main shaft is connected with the axial actuating pressure plate through a plurality of connecting members, and the center of the actuating main shaft is provided with a connecting part for connecting with the radial driving mandrel.

5. The hollow cylinder structure torsional shear mechanical property testing device of claim 4, wherein, the outer side of the actuating main shaft is provided with a multi-jaw structure for connecting with the axial actuating pressure plate through a plurality of connecting members to form a multi-jaw axial driving system.

6. The hollow cylinder structure torsional shear mechanical property testing device of claim 1, wherein, the fixed support mechanism comprises: an outer sleeve constituting the main framework of the device; an upper cover plate connected with the upper part of the outer sleeve; a base connected with the lower part of the outer sleeve and used for fixing the entire device on a workbench; the upper cover plate and the base jointly provide guidance and constraint for the radial movement of the driving sliding plate.

7. The hollow cylinder structure torsional shear mechanical property testing device of claim 6, wherein, the rolling elements provided on the upper and lower end faces of the driving sliding plate are balls, and the lower surface of the upper cover plate and the upper surface of the base constitute a smooth track for the movement of the balls.

8. The hollow cylinder structure torsional shear mechanical property testing device of claim 4, wherein, the axial driving mechanism and the radial driving mechanism can be driven by the actuating main shaft to act individually or jointly to independently exert axial compression load, radial internal support load or synchronously exert composite load. 9.The hollow cylinder structure torsional shear mechanical property testing device of claim 1, wherein, a data acquisition system is further included, which comprises sensors for detecting at least one parameter of torque, axial force and displacement, and the sensors are arranged on the axial driving mechanism.

10. A method for testing the mechanical properties of a hollow cylindrical structure using the apparatus of any one of claims 1-9, wherein, Comprise the following steps: sleeving the specimen outside the fixed support mechanism; driving the axial driving mechanism to move downward; forcing the driving sliding plate to expand radially outward through the downward movement of the radial driving mandrel and its inverted conical structure until it contacts the inner wall of the specimen and exerts a set radial load; exerting a set axial load on the end face of the specimen through the downward movement of the axial actuating pressure plate; real-time acquisition of mechanical parameters during the test; wherein the steps of exerting axial load and radial load can be performed individually or synchronously.

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