A system for testing the dynamic stiffness of a kinked hose

Abstract

The application discloses a kind of bending hose dynamic stiffness test systems, the test system mainly includes exciter, air bearing, three-dimensional adjustment platform, force sensor, laser displacement sensor several parts.Between the bending hose dynamic stiffness test system of exciter and bending hose, excitation rod and air bearing are arranged, lateral overturning force generated by bending hose during testing process will be received by air bearing, to prevent lateral overturning force from affecting exciter and excitation force, excitation rod has smaller lateral bending stiffness, can isolate lateral vibration from the side of exciter, so that excitation force is completely output along single axial direction, ensure detection accuracy;Meanwhile, excitation rod can also reduce the assembly difficulty of exciter and air bearing, compensate assembly coaxial error, avoid the adverse effects of additional load caused by installation error on test accuracy.

Description

Technical Field

[0001] This invention relates to the field of pipeline stiffness testing technology, and in particular to a dynamic stiffness testing system and method for a bent flexible hose. Background Technology

[0002] In industrial applications such as pneumatic pipelines and media transport pipelines, flexible hoses are often designed with specific bending angles due to space constraints to achieve fluid diversion and transport. These bent hoses are widely used in many industrial settings due to their compact space adaptability. However, because of the geometric abrupt changes at the bends, these areas are prone to stress concentration and deformation sensitivity. In actual operation, they not only have to withstand internal media pressure but are also inevitably subjected to external vibrations and bending loads, resulting in highly complex stress conditions. To ensure the long-term safe and reliable operation of pipeline systems under complex conditions, it is necessary to test the dynamic stiffness of bent hoses. Dynamic stiffness testing quantifies their ability to resist deformation under dynamic loads and assesses their deformation characteristics under stress, thus providing accurate basic parameters for pipeline system dynamics simulation, vibration reduction optimization design, and fatigue life verification.

[0003] Dynamic stiffness is a key indicator measuring the ability of a structure or material to resist deformation under dynamic loads that vary with frequency. Numerically, it is equal to the ratio of the dynamic force amplitude to the dynamic displacement amplitude generated by that force. When testing the dynamic stiffness of a flexible hose, one end of the hose is connected to a vibrator, and the other end to a force sensor. The vibrator provides an excitation force to the hose, causing one end to vibrate back and forth at a set displacement amplitude. Simultaneously, the force sensor measures the vibration force on the other end of the hose, thus calculating the hose's dynamic stiffness. In a bent flexible hose, the axes of the loaded and fixed ends do not coincide, generating lateral overturning forces during vibration. These lateral overturning forces react on the vibrator, interfering with its excitation force and potentially damaging the vibrator, affecting the normal operation of the equipment. Furthermore, flexible hoses are flexible components, and their mechanical response is highly sensitive to load fluctuations. Various external coupling interference forces can reduce the accuracy of dynamic stiffness test results. Therefore, the testing system must have a higher ability to suppress external disturbance loads.

[0004] Existing hose stiffness testing devices, such as the hose stiffness measuring device disclosed in Chinese Utility Model Patent CN209085873U, are mainly designed for straight pipe structures and are mostly limited to measuring static stiffness, making it difficult to meet the testing requirements for the dynamic stiffness of bent hoses. Therefore, to address the shortcomings of the existing technology, it is necessary to design a dynamic stiffness testing system specifically designed for the structural characteristics of bent hoses to meet the dynamic stiffness testing requirements of bent hoses. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a testing system specifically designed for testing the dynamic stiffness of bent flexible tubes.

[0006] A dynamic stiffness testing system for a bent flexible hose includes: a vibrator for providing the excitation force required for dynamic stiffness testing; an air bearing with a guide shaft inside, the first end of which is connected to the vibrator via an excitation rod, and the second end of which has a first specimen mounting seat for fixing one end of the bent flexible hose; a three-dimensional adjustment platform with a second specimen mounting seat, the platform being able to adjust the position of the second specimen mounting seat in the X, Y, and Z directions, a force sensor connected to the second specimen mounting seat for fixing the other end of the bent flexible hose; a laser displacement sensor for detecting the displacement of the first specimen mounting seat; and a controller connected to the vibrator, force sensor, and laser displacement sensor, the controller controlling the excitation force output of the vibrator and calculating the corresponding dynamic stiffness value based on the feedback signals from the force sensor and laser displacement sensor.

[0007] Preferably, the first end of the guide shaft is provided with a tapered sleeve, one end of the tapered sleeve is fixedly connected to the first end of the guide shaft, the other end of the tapered sleeve is provided with a tapered hole, an elastic clamp is provided in the tapered hole, a pressure cap is fitted on the tapered sleeve, the pressure cap is threadedly connected to the tapered sleeve, the pressure cap can be rotated to push the elastic clamp into the tapered hole, the excitation rod passes through the pressure cap and extends into the elastic clamp, the pressure cap is tightened to fix the excitation rod to the tapered sleeve.

[0008] Preferably, the three-dimensional adjustment platform includes three single-axis slides, which are arranged sequentially from bottom to top along the X, Y, and Z directions, and adjacent single-axis slides are fixedly connected.

[0009] Preferably, the single-axis slide includes a base and a slider, the base and the slider are slidably connected, and the sides of the base and the slider can be fixedly connected by a fixing plate.

[0010] Preferably, the first specimen mounting base is provided with an outwardly extending diamond-shaped stop, the diamond-shaped stop corresponding to the position of the laser displacement sensor.

[0011] Preferably, it also includes a rigid positioning ruler for simulating the shape of a bent hose.

[0012] Preferably, the force sensor is a six-component force sensor.

[0013] Preferably, the laser displacement sensor is mounted on a support frame, and the bottom of the support frame is provided with a shock-absorbing pad.

[0014] The above technical solution has the following beneficial effects: The dynamic stiffness testing system for the bent hose has an excitation rod and an air bearing installed between the exciter and the bent hose. During the test, the lateral overturning force generated by the bent hose is absorbed by the air bearing, preventing the lateral overturning force from adversely affecting the exciter and the excitation force. The excitation rod has a small lateral bending stiffness, which can isolate the lateral vibration originating from one side of the exciter, so that the excitation force is output entirely in a single axial direction, ensuring the detection accuracy. At the same time, the excitation rod can also reduce the assembly difficulty of the exciter and the air bearing, compensate for the coaxial error of the assembly, and avoid the adverse effects of the additional load caused by the installation error on the test accuracy. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the connection between the excitation rod and the air bearing guide shaft in an embodiment of the present invention.

[0017] Figure 3 This is a schematic diagram of the structure of the elastic clamp according to an embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram of the structure of the three-dimensional adjustment platform according to an embodiment of the present invention (without the fixing plate installed).

[0019] Figure 5 This is a schematic diagram of the structure of the three-dimensional adjustment platform (mounting and fixing plate) according to an embodiment of the present invention.

[0020] Figure 6 This is a schematic diagram of the structure of the present invention, which uses a rigid positioning ruler for positioning.

[0021] Figure 7 This is the Y-axis dynamic stiffness frequency response curve of the flexible hose measured in an embodiment of the present invention.

[0022] Figure 8 This is a schematic diagram of the structure for measuring the dynamic stiffness of a hose in the Z direction according to an embodiment of the present invention.

[0023] Figure 9 This is the Z-axis dynamic stiffness frequency response curve of the flexible hose measured in an embodiment of the present invention.

[0024] Original component numbering descriptions: 1. Vibrator; 2. Vibration rod; 3. Air bearing; 31. Tapered ferrule; 32. Elastic chuck; 33. Pressure cap; 34. Elastic arm; 35. Tapered hole; 4. Guide shaft; 5. First specimen mounting base; 51. Diamond-shaped stop; 6. Laser displacement sensor; 61. Support frame; 62. Vibration damping pad; 7. Three-dimensional adjustment platform; 71. First single-axis slide; 72. Second single-axis slide; 73. Third single-axis slide; 74. Fixing plate; 8. Second specimen mounting base; 9. Force sensor; 10. Hoose; 11. First horizontal base plate; 12. Second horizontal base plate; 13. Pad; 14. Height adjustment block; 15. Rigid positioning ruler. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0026] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the invention will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of the invention.

[0027] like Figure 1 As shown, this invention discloses a dynamic stiffness testing system for a bent flexible hose. The system mainly comprises a vibrator 1, an air bearing 3, a laser displacement sensor 6, and a three-dimensional adjustment platform 7. The air bearing 3 contains a guide shaft 4. The air bearing 3 utilizes high-pressure gas to form a high-pressure gas film between the guide shaft 4 and the bearing ring, achieving contactless support for the guide shaft 4. The guide shaft 4 can move back and forth within the air bearing 3 along the axial direction. The vibrator 1 is connected to the first end of the guide shaft 4 via a vibration rod 2. A first specimen mounting seat 5 is provided on the second end of the guide shaft 4.

[0028] A three-dimensional adjustment platform 7 is located on one side of the air bearing 3. A second specimen mounting seat 8 is mounted on the three-dimensional adjustment platform 7. The three-dimensional adjustment platform 7 can adjust the position of the second specimen mounting seat 8 in the X, Y, and Z directions. A force sensor 9 is also mounted on the three-dimensional adjustment platform 7, connected to the second specimen mounting seat 8. The force sensor 9 is used to detect the force acting on the second specimen mounting seat 8. A laser displacement sensor 6 is mounted on the support frame 61, opposite to the air bearing 3. The laser displacement sensor 6 is used to detect the displacement of the first specimen mounting seat 5. The vibrator 1, laser displacement sensor 6, and force sensor 9 are all connected to a controller, which can be a PC, an industrial control computer, or a dedicated vibration controller.

[0029] like Figure 1 As shown, when the test system performs dynamic stiffness testing, the two ends of the hose 10 are fixedly connected to the first specimen mounting base 5 and the second specimen mounting base 8 respectively according to the test requirements and the specified shape (including bending angle and bending direction). The controller controls the excitation force transmission of the vibrator 1 according to the test requirements, and the corresponding dynamic stiffness can be calculated based on the feedback signals of the laser displacement sensor 6 and the force sensor 9.

[0030] The flexible hose 10 is a flexible component, which is extremely sensitive to the mechanical response to load fluctuations. This is especially true for slender hoses made of silicone or plastic. Even a small non-axial disturbance component in the excitation force can cause a significant deviation in the hose's stress response characteristics, severely affecting the accuracy of the test results. Therefore, ensuring that the excitation force applied to the hose 10 is transmitted only along a single axis (uniaxiality) and is not disturbed by loads in other directions is an important prerequisite for obtaining reliable dynamic stiffness parameters.

[0031] Because the flexible hose 10 has a bent structure and its two ends are not aligned, it generates a lateral load component when subjected to excitation load. If this lateral load component is not restricted, it will form a lateral overturning moment, which will act on the exciter. This will not only affect the single axiality of the excitation force but also damage the exciter body. In this invention, the air bearing 3 and the guide shaft 4 are supported non-contactly by a high-pressure air film. The lateral load generated by the flexible hose 10 is transmitted to the guide shaft 4 through the first specimen mounting seat 5. The lateral load is absorbed by the high-pressure air film of the air bearing 3, thus blocking the transmission path of the lateral load to the exciter end. This prevents the lateral load from interfering with the axial excitation force, ensuring the single axiality of the excitation force, and avoiding the impact of the lateral load on the exciter body. This achieves overload protection for the exciter and ensures the long-term stable operation of the test system.

[0032] The exciter and the air bearing 3 are connected by a guide shaft 4 via an exciter rod 2. The exciter rod 2 is a slender rod with high axial stiffness, enabling efficient and stable transmission of axial excitation force. Simultaneously, its low lateral bending stiffness effectively blocks lateral disturbances caused by factors such as exciter coil resonance and housing vibration, preventing lateral vibrations generated at the exciter end from being transmitted to the guide shaft 4 via the exciter rod 2. This also prevents interference loads at the exciter end from superimposing on the excitation signal. Furthermore, the exciter rod 2 provides further mechanical isolation for residual lateral loads that the air bearing 3 fails to fully absorb, forming a double-isolation protection structure. This ensures that the excitation force applied to the hose is a single axial force, thereby guaranteeing the system's testing accuracy. Additionally, the exciter rod 2 reduces the assembly difficulty of the exciter and air bearing, compensates for assembly coaxiality errors, avoids additional loads caused by installation errors, and prevents these additional loads from interfering with the axial excitation force.

[0033] like Figure 2 , 3 As shown in the illustration, in one specific embodiment, a tapered sleeve 31 is provided at the first end of the guide shaft 4. One end of the tapered sleeve 31 is fixedly connected to the first end of the guide shaft 4, and the other end of the tapered sleeve 31 is provided with a tapered hole 35. An elastic chuck 32 is provided inside the tapered hole 35. The elastic chuck 32 is a slotted spring sleeve with a taper, composed of multiple elastic arms 34 spaced apart along the circumferential direction. The inner circumferential surface of the elastic chuck 32 is a cylindrical surface, and the outer circumferential surface is a conical surface. Its outer circumferential surface is adapted to the inner conical surface of the tapered hole 35. A pressure cap 33 is fitted on the tapered sleeve 31. The pressure cap 33 is connected to the outer circumferential surface of the tapered sleeve 31 by a thread. Rotation of the pressure cap 33 can push the elastic chuck 32 to move into the tapered hole.

[0034] When using this structure to connect the excitation rod 2 and the guide shaft 4, one end of the excitation rod 2 is first fixedly connected to the vibrator 1. Then, the other end of the excitation rod 2 passes through the pressure cap 33 and extends into the elastic chuck 32 near the bottom of the chuck. Rotating the pressure cap 33 pushes the elastic chuck 32 into the tapered hole. As the elastic chuck 32 moves into the tapered hole, the elastic arm 34 is squeezed inward by the inner conical surface of the tapered hole, generating radial inward elastic deformation. This causes the inner cylindrical surface of the elastic chuck to synchronously contract inward and clamp the excitation rod 2, thus fixing the excitation rod 2 to the tapered sleeve 31 and the guide shaft 4. With this connection method, the multiple elastic arms 34 of the elastic chuck 32 contract inward synchronously when clamping, achieving a high-precision concentric connection between the vibrator, the excitation rod, and the guide shaft 4, effectively improving the transmission accuracy of the excitation force.

[0035] The three-dimensional adjustment platform 7 is used to quickly adjust the position of the second specimen mounting base 8, facilitating rapid clamping of the hose 10 during testing. Figure 4As shown in the figure, in a specific embodiment of the present invention, the three-dimensional adjustment platform 7 consists of a first single-axis slide 71 with a ball screw, a second single-axis slide 72, and a third single-axis slide 73. Each single-axis slide includes a slider and a base, which can slide relative to each other. A dovetail-shaped guide structure is used between the slider and the base. The first single-axis slide 71 is set in the X direction, the second single-axis slide 72 is set in the Y direction, and the third single-axis slide 73 is set in the Z direction. The second single-axis slide 72 is mounted on the first single-axis slide 71 and fixedly connected to it, and the third single-axis slide 73 is mounted on the second single-axis slide 72 and fixedly connected to it. In this way, the position adjustment of the second specimen mounting seat 8 in the X, Y, and Z directions can be achieved by the cooperation of the three single-axis slides.

[0036] During the test, one end (vibration end) of the hose 10 can be fixed to the first specimen mounting seat 5. Then, the position of the other end of the hose 10 is determined according to the bending shape and bending angle required by the hose during the test. The second specimen mounting seat 8 is adjusted to this position through the three-dimensional adjustment platform 7, and the other end (force-bearing end) of the hose is fixed to the second specimen mounting seat 8. This completes the clamping of the hose 10.

[0037] To enable rapid adjustment of the position of the second specimen mounting base 8, this invention also includes a coarse adjustment assembly. This assembly comprises a pad 13 and multiple height adjustment blocks 14. The pad 13 is movably mounted on the second horizontal base plate 12. A three-dimensional adjustment platform 7 is mounted on the pad 13. After determining the position of the force-bearing end of the hose 10, the pad 13 can be moved along the X and Y axes, and the height adjustment blocks 14 are positioned at the bottom of the three-dimensional adjustment platform 7. This adjusts the second specimen mounting base 8 to the approximate position of the force-bearing end of the hose 10, fixing the pad 13 and the three-dimensional adjustment platform 7. Then, the second specimen mounting base 8 is adjusted to the accurate position via the three-dimensional adjustment platform 7, significantly improving the hose clamping speed. The height adjustment blocks 14 can also be set to different tilt angles to facilitate adjustment of the tilt angle of the second specimen mounting base 8.

[0038] During hose clamping, for some slender and flexible hoses, the shape of the hose can easily deform when determining the position of its stressed end, making it difficult to accurately determine the position of the stressed end and thus affecting the test results. To address this, the present invention also designs a rigid positioning ruler 15 (e.g., Figure 6 As shown, the rigid positioning ruler 15 is designed as a high-strength structural component with the same shape as the test pipe. Before clamping the hose, the rigid positioning ruler 15 can be used to adjust the three-dimensional adjustment platform 7 and the coarse adjustment component to determine the specific position of the second specimen mounting seat 8, and then the hose can be installed to avoid deformation of the hose during the installation process.

[0039] The three-dimensional adjustment platform 7 has play, and it will also vibrate during testing, which will act on the force sensor and affect the testing accuracy. Therefore, it can be addressed as follows: Figure 5 As shown, threaded holes can be opened on the side of the slider and base of each single-axis slide. When the three-dimensional adjustment platform 7 is adjusted into place, the slider and base of each single-axis slide are fixed by the fixing plate 74, so that the entire three-dimensional adjustment platform 7 becomes a rigid body structure. This can avoid the impact of vibration of the three-dimensional adjustment platform 7 on the test accuracy during the test.

[0040] As a specific embodiment of the present invention, the vibrator 1 and the air bearing 3 are mounted on the first horizontal base plate 11, and the three-dimensional adjustment platform 7 is mounted on the second horizontal base plate 12. The first horizontal base plate and the second horizontal base plate are respectively mounted on two different marble horizontal bases. The first horizontal base plate 11 and the second horizontal base plate 12 are set separately, which can prevent the vibration of the platform caused by the vibrator 1 when it is working from being transmitted to the three-dimensional adjustment platform 7 through the foundation and affecting the test accuracy.

[0041] The vibration of the platform caused by the vibrator 1 when it is working will also affect the support frame 61 and affect the measurement accuracy of the laser displacement sensor 6. Therefore, a shock-absorbing pad 62 can be set at the bottom of the support frame 61. The shock-absorbing pad 62 can reduce the interference of the vibrator 1 on the laser displacement sensor 6.

[0042] A laser displacement sensor 6 is positioned opposite the air bearing 3 and is used to detect the displacement in the direction of the excitation force of the first specimen mounting base 5. During testing, the position of the flexible tube needs to be adjusted according to the test requirements. Sometimes, the flexible tube may block the propagation of the light signal from the laser displacement sensor 6, requiring adjustment of the position of the laser displacement sensor 6, making the system debugging process complex. This invention provides a diamond-shaped stop 51 on the first specimen mounting base 5, extending outwards from the first specimen mounting base 5. The laser displacement sensor 6 is positioned opposite the diamond-shaped stop 51. By detecting the displacement of the diamond-shaped stop 51, the displacement of the first specimen mounting base 5 is obtained. This eliminates the need to frequently change the position of the laser displacement sensor 6 when testing the flexible tube in different directions, greatly improving work efficiency. The diamond-shaped stop 51 and the first specimen mounting base 5 are designed as an integral structure, and its first-order bending frequency is designed to be more than five times the system's operating frequency, ensuring that the displacement of the diamond-shaped stop 51 and the first specimen mounting base 5 is the same during vibration.

[0043] As a preferred embodiment of the present invention, the force sensor 9 adopts a six-component force sensor, which can simultaneously measure the force in three orthogonal directions and the torque around three axes, obtain the magnitude of the force borne by the hose in each direction, meet the testing requirements of the hose in different directions, and eliminate the need to frequently change the sensor position during the testing process, making system debugging more convenient.

[0044] like Figure 1 As shown, when using this testing system, the hose 10 is first fixed between the first specimen mounting base 5 and the second specimen mounting base 8 according to the shape and bending angle required for the test. The section of the hose 10 connected to the first specimen mounting base 5 is perpendicular to the direction of the excitation force in the horizontal direction (this clamping method is defined as the Y-direction dynamic stiffness test). The controller drives the exciter 1 to output the excitation force according to the dynamic stiffness test conditions shown in Table 1. Simultaneously, the corresponding dynamic stiffness is calculated based on the feedback signals from the laser displacement sensor 6 and the force sensor 9, resulting in the following... Figure 7 The Y-axis dynamic stiffness frequency response curve is shown. The horizontal axis represents the vibration excitation frequency, and the vertical axis represents the dynamic stiffness of the hose. As can be seen from the curve, the dynamic stiffness of the hose is greatly affected by the vibration frequency. The multiple stiffness troughs on the curve correspond to the natural resonant frequencies of the hose. Near the resonant frequency, the hose's ability to resist lateral deformation decreases. The maximum dynamic stiffness of the hose in the Y direction is approximately 1830 N / m.

[0045] Table 1

[0046]

[0047] For example Figure 8 As shown, in another embodiment of the present invention, the section connecting the hose 10 to the first specimen mounting base 5 is perpendicular to the direction of the excitation force in the vertical direction (this clamping method is defined as the Z-axis dynamic stiffness test). The controller drives the exciter 1 to output excitation force according to the dynamic stiffness test conditions shown in Table 1, and simultaneously calculates the corresponding dynamic stiffness based on the feedback signals from the laser displacement sensor 6 and the force sensor 9, obtaining the following... Figure 9 The figure shows the Z-direction dynamic stiffness frequency response curve. The dynamic stiffness generally increases with the increase of vibration frequency. The peaks and troughs of the curve correspond to the resonant frequencies of the hose along the axial direction. The dynamic stiffness of the hose in the Z direction is greater than that in the Y direction. The maximum dynamic stiffness of the hose in the Z direction is about 6900 N / m.

[0048] As can be seen from the two sets of dynamic stiffness frequency response curves above, the curves obtained by the test are smooth overall and without obvious serrations or burrs. This proves that the test device uses a combination of air bearings and slender excitation rods to complete the lateral load decoupling, which can effectively isolate the lateral overturning force generated by bending the hose and the lateral vibration disturbance at the exciter end. The excitation force is almost unaffected by loads in other directions, and the data stability and test accuracy of the dynamic stiffness test are excellent.

[0049] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A dynamic stiffness testing system for a bent flexible hose, characterized in that, It includes: A vibrator, the vibrator being used to provide the excitation force required during dynamic stiffness testing; An air bearing, wherein a guide shaft is provided inside the air bearing, the first end of the guide shaft is connected to the vibrator through a vibration rod, and the second end of the guide shaft is provided with a first specimen mounting seat, which is used to fix one end of a bent hose; A three-dimensional adjustment platform is provided, which is equipped with a second specimen mounting seat. The three-dimensional adjustment platform can drive the second specimen mounting seat to adjust its position in the X, Y, and Z directions. The three-dimensional adjustment platform is equipped with a force sensor, which is connected to the second specimen mounting seat. The second specimen mounting seat is used to fix the other end of the bent hose. A laser displacement sensor is used to detect the displacement of the first specimen mounting base; The controller is connected to the vibrator, force sensor, and laser displacement sensor. The controller is used to control the excitation force output of the vibrator and calculate the corresponding dynamic stiffness value based on the feedback signals from the force sensor and laser displacement sensor.

2. The dynamic stiffness testing system for bent flexible tubes according to claim 1, characterized in that, The first end of the guide shaft is provided with a tapered sleeve. One end of the tapered sleeve is fixedly connected to the first end of the guide shaft. The other end of the tapered sleeve is provided with a tapered hole. An elastic clamp is provided in the tapered hole. A pressure cap is fitted on the tapered sleeve. The pressure cap is threadedly connected to the tapered sleeve. Rotating the pressure cap can push the elastic clamp into the tapered hole. The excitation rod passes through the pressure cap and extends into the elastic clamp. Tightening the pressure cap fixes the excitation rod to the tapered sleeve.

3. The dynamic stiffness testing system for bent flexible tubes according to claim 1, characterized in that, The three-dimensional adjustment platform includes three single-axis slides, which are arranged sequentially from bottom to top along the X, Y, and Z directions, and adjacent single-axis slides are fixedly connected.

4. The dynamic stiffness testing system for bent flexible tubes according to claim 3, characterized in that, The single-axis slide table includes a base and a slider. The base and the slider are slidably connected, and the sides of the base and the slider can be fixedly connected by a fixing plate.

5. The dynamic stiffness testing system for bent flexible tubes according to claim 1, characterized in that, The first specimen mounting base is provided with an outwardly protruding diamond-shaped stop, which corresponds to the position of the laser displacement sensor.

6. The dynamic stiffness testing system for bent flexible tubes according to claim 1, characterized in that, It also includes a rigid positioning ruler for simulating the shape of a bent hose.

7. The dynamic stiffness testing system for bent flexible tubes according to claim 1, characterized in that, The vibrator and air bearing are mounted on the first horizontal base plate, and the three-dimensional adjustment platform is mounted on the second horizontal base plate. The first horizontal base plate and the second horizontal base plate are separately mounted.

8. The dynamic stiffness testing system for bent flexible tubes according to claim 1, characterized in that, The force sensor is a six-component force sensor.

9. The dynamic stiffness testing system for bent flexible tubes according to claim 1, characterized in that, The laser displacement sensor is mounted on a support frame, and the bottom of the support frame is provided with a shock-absorbing pad.

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