Dynamic stiffness test bed for large-diameter flexible connecting pipe

Abstract

The invention relates to a large-diameter flexible connecting pipe dynamic stiffness test bench, and relates to the field of test detection equipment, the large-diameter flexible connecting pipe dynamic stiffness test bench comprises a flexible connecting pipe direct test bench and a flexible connecting pipe indirect test bench, the flexible connecting pipe direct test bench comprises a direct test pedestal, the direct test pedestal is provided with a direct force measuring plate, and the direct force measuring plate is provided with a flexible connecting pipe. The direct force measuring plate is provided with a direct transition installation assembly, and the direct installation assembly is used for installing a flexible connecting pipe. The flexible connecting pipe indirect test bench comprises an indirect test base, a blocking mass block is arranged on the indirect test base, an indirect transition installation assembly is arranged above the blocking mass block, and the indirect transition installation assembly is used for installing a flexible connecting pipe. The indirect transition installation assembly and the direct transition installation assembly are provided with excitation test assemblies. According to the invention, the accuracy of test data is ensured, and the design cost, the processing cost and the test difficulty of the test bench are reduced.

Description

Technical Field

[0001] The present application relates to the field of testing and inspection equipment, and in particular to a dynamic stiffness test bench for large-diameter flexible pipes. Background Art

[0002] The pipeline system is called the "blood vessels" of the ship. It is mainly used to transport various media such as oil, water, and steam. It plays a vital role in ensuring the navigation of the ship and the operation of mechanical equipment. However, while realizing the medium transmission function, vibration and noise are also transmitted to the hull structure, becoming an important factor restricting the acoustic stealth performance of the ship. Flexible pipe technology is one of the important methods to effectively suppress the vibration and noise of the pipeline system. It has been widely used in the field of ships and has formed relatively detailed standards in design, inspection, installation and maintenance. However, due to its diverse structural forms and different materials, its vibration characteristics are also particularly complex. Therefore, the research on the vibration dynamic characteristics of flexible pipes is still in the development stage.

[0003] In order to evaluate the vibration reduction performance of flexible pipes, researchers usually directly build a platform to simulate the environment of actual ship installation and evaluate the characteristics of flexible pipes by measuring insertion loss. However, in actual operation, it is found that the insertion loss is greatly affected by the installation conditions, and the consistency of test results under different installation conditions is poor. In the end, the insertion loss of the simulated actual ship platform is inconsistent with that of the actual ship installation. In the analysis stage of flexible pipe design, transfer matrix analysis or finite element method is usually used, and the results of insertion loss cannot directly verify or guide the design results.

[0004] Based on this, most domestic research institutions gradually separated the flexible pipe from the use environment and began to evaluate the source characteristics of the flexible pipe with dynamic stiffness. Since the flexible pipe and the vibration isolator are both vibration reduction components, the direct impedance test method or the indirect impedance test method is usually used to test and analyze its dynamic stiffness.

[0005] With respect to the above-mentioned related technologies, the inventors believe that the direct impedance test method requires that the impedance of the blocking end mounting base is large enough. For large-diameter winding pipes, due to their large installation dimensions, it is difficult to design and process a mounting base with a first-order free mode greater than 1000Hz, resulting in a low upper limit frequency of the test. The indirect impedance test method requires that the component to be tested and the blocking mass block have a large impedance mismatch, and the lower limit frequency of the test is generally about three times the overall installation frequency of the system. Although increasing the mass of the blocking mass block can broaden the lower limit frequency of the test, excessive blocking mass will increase the manufacturing cost of the test bench and the difficulty of testing. Summary of the invention

[0006] In order to ensure the accuracy of the test data and reduce the design cost, processing cost and test difficulty of the test bench, the present application provides a large-diameter flexible pipe dynamic stiffness test bench.

[0007] The large-diameter flexible pipe dynamic stiffness test bench provided in this application adopts the following technical solution:

[0008] A large-diameter flexible pipe dynamic stiffness test bench includes a flexible pipe direct test bench and a flexible pipe indirect test bench. The flexible pipe direct test bench includes a direct test base, a direct force plate is provided on the direct test base, a direct transition mounting assembly is provided on the direct force plate, and the direct mounting assembly is installed on the flexible pipe; the flexible pipe indirect test bench includes an indirect test base, a blocking mass block is provided on the indirect test base, an indirect transition mounting assembly is provided above the blocking mass block, the indirect transition mounting assembly is installed on the flexible pipe, and an excitation test assembly is provided on the indirect transition mounting assembly and the direct transition mounting assembly.

[0009] Optionally, the test range of the flexible pipe direct test bench is 10Hz-f L , f L The range is 200Hz-300Hz.

[0010] Optionally, the direct transition installation assembly includes a direct upper cover plate, which is fixedly connected to the flexible pipe, and the bottom end of the flexible pipe is fixedly connected to a direct lower cover plate, and the direct upper cover plate and the direct lower cover plate seal the interior of the flexible pipe.

[0011] Optionally, a direct adapter plate is arranged between the direct lower cover plate and the direct force measuring plate, the top end of the direct adapter plate is fixed to the direct lower cover plate, and the bottom end of the direct adapter plate is fixed to the direct force measuring plate.

[0012] Optionally, the test range of the flexible pipe indirect test bench is f H -1000Hz, f H The range is 200Hz-300Hz.

[0013] Optionally, the indirect transition mounting assembly includes an indirect upper cover plate, which is fixedly connected to the flexible pipe, and the bottom end of the flexible pipe is fixedly connected to an indirect adapter plate, and the indirect adapter plate and the upper cover plate seal the interior of the flexible pipe.

[0014] Optionally, a support frame is provided at the bottom end of the blocking mass block, and an airbag is provided between the bottom end of the support frame and the indirect testing base, and the airbag supports the support frame.

[0015] Optionally, a first indirect acceleration sensor is fixedly connected to the indirect upper cover plate, and a second indirect acceleration sensor is fixedly connected to the indirect adapter plate.

[0016] Optionally, when the vibration acceleration level at the input end is 20 dB higher than the vibration acceleration at the output end, the calculation formula for the dynamic stiffness of the flexible tube is as follows:

[0017]

[0018] Where: m2 is the mass of the blocking mass block; m f is the mass of the transition tooling; a2 is the acceleration at the output end; a1 is the acceleration at the input end; Z n is the impedance of the flexible pipe; Z t is the airbag impedance; Z m is the blocking mass impedance.

[0019] Optionally, the vibration test assembly includes a gantry, and a vibration machine is suspended on the gantry, and the excitation ends of the vibration machine are respectively connected to the direct transition installation assembly and the indirect transition installation assembly.

[0020] In summary, the present application includes at least one of the following beneficial technical effects:

[0021] 1. By reasonably splitting the test frequency bands, according to the test mechanisms of the direct method and the indirect method, the test benches are designed in their advantageous frequency bands respectively, so as to solve the problem that a single test bench is difficult to meet the needs of wide-band dynamic stiffness testing.

[0022] 2. Since the two test methods avoid their disadvantageous frequency bands, the design difficulty, manufacturing cost and test difficulty of the test bench will be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of a flexible pipe direct test bench in a large-diameter flexible pipe dynamic stiffness test bench in an embodiment of the present application.

[0024] Figure 2 It is a schematic diagram of the overall structure of the flexible pipe indirect test bench in the large-diameter flexible pipe dynamic stiffness test bench in the embodiment of the present application.

[0025] Figure 3 It is a three-dimensional schematic diagram of a flexible pipe direct test bench in a large-diameter flexible pipe dynamic stiffness test bench in an embodiment of the present application.

[0026] Figure 4 It is a side view of a flexible pipe direct test bench in a large-diameter flexible pipe dynamic stiffness test bench in an embodiment of the present application.

[0027] Figure 5It is a side view of the flexible pipe indirect test bench in the large-diameter flexible pipe dynamic stiffness test bench in the embodiment of the present application.

[0028] Explanation of the reference numerals: 1. Flexible tube direct test bench; 11. Direct test base; 12. Direct force plate; 13. Direct adapter plate; 14. Direct upper cover plate; 15. Direct lower cover plate; 2. Flexible tube indirect test bench; 21. Indirect test base; 22. Support frame; 23. Airbag; 24. Blocking mass block; 25. Indirect upper cover plate; 26. Indirect adapter plate; 3. Flexible tube; 4. Gantry; 41. Vibrator. DETAILED DESCRIPTION

[0029] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0031] The following is combined with Figure 1-5 This application is described in further detail.

[0032] The present application embodiment discloses a large-diameter flexible pipe dynamic stiffness test bench. Figure 1 , Figure 2 The large-diameter flexible pipe dynamic stiffness test bench includes a flexible pipe direct test bench 1 and a flexible pipe indirect test bench 2. The flexible pipe direct test bench 1 is used to test the low frequency band of the flexible pipe 3, and the test range is 10Hz-f L ,f L The flexible pipe indirect test bench 2 is used to test the high frequency band of the flexible pipe 3, and the test range is f H -1000Hz, f H About 200Hz-300Hz.

[0033] Reference Figure 3 , Figure 4 The flexible tube direct test bench 1 includes a direct test base 11 located at the bottom, the direct test base 11 is a rigid base, and a direct force plate 12 is arranged above the direct test base 11. The direct force plate 12 is rigidly fixed on the low-frequency band test base by pressure plates around it, and the direct force plate 12 is used to obtain the blocking force at the output end of the flexible tube 3.

[0034] A direct adapter plate 13 is also arranged at the top of the direct force plate 12. The direct adapter plate 13 is arranged vertically, and a plurality of direct adapter plates 13 are arranged. The plurality of direct adapter plates 13 are arranged along the circumferential direction, and one ends of the plurality of direct adapter plates 13 are all located at the center position of the flexible tube 3, and the other ends of the plurality of direct adapter plates 13 are arranged to diverge outward along the circumferential direction in which they are arranged.

[0035] A direct upper cover plate 14 is coaxially arranged at the top end of the flexible pipe 3, and a direct lower cover plate 15 is coaxially arranged at the bottom end of the flexible pipe 3. The direct upper cover plate 14 is fixedly connected to the flexible pipe 3, and the direct lower cover plate 15 is fixedly connected to the flexible pipe 3. The flexible pipe 3 is sealed by the direct upper cover plate 14 and the direct lower cover plate 15, so as to facilitate injection and pressure maintenance inside the flexible pipe 3.

[0036] The bottom side wall of the direct lower cover plate 15 is fixedly connected to the top wall of the direct adapter plate 13, so that the direct adapter plate 13 relatively connects the direct lower cover plate 15 to the direct force plate 12. The first direct acceleration sensor is fixedly connected to the direct upper cover plate 14, and the second direct acceleration sensor is fixedly connected to the direct lower cover plate 15.

[0037] By reasonably designing the direct upper cover plate 14, the direct lower cover plate 15, the direct force plate 12 and the direct test base 11, such as increasing the plate thickness, increasing the number of ribs and other measures, the first-order free modal frequency of the test fixture is increased, thereby increasing the upper limit frequency of the direct method test.

[0038] Reference Figure 2 , Figure 5 The flexible pipe indirect test bench 2 includes an indirect test base 21, which is a rigid base. A support frame 22 is relatively arranged above the indirect test base 21. An air bag 23 is arranged between the support frame 22 and the indirect test base 21. A plurality of air bags 23 are arranged, and the air bags 23 are respectively located at the connection positions of the support frame 22 and the indirect test base 21, and the support frame 22 is supported by the air bags 23.

[0039] A blocking mass block 24 is provided at the top of the support frame 22, and the bottom wall of the blocking mass block 24 abuts against the top wall of the support frame 22. The blocking mass block 24 is used to simulate the blocking of the output end of the flexible tube 3, and the blocking force value is indirectly calculated through the mass of the blocking mass block 24 and the vibration acceleration level.

[0040] An indirect upper cover plate 25 is disposed at the top of the flexible pipe 3, the indirect upper cover plate 25 is coaxially disposed with the flexible structure, and the indirect upper cover plate 25 is fixedly connected to the flexible pipe 3. An indirect adapter plate 26 is coaxially disposed at the bottom of the flexible structure, and the indirect adapter plate 26 is fixedly connected to the flexible pipe 3. The interior of the flexible pipe 3 is sealed and fixed by the indirect upper cover plate 25 and the indirect adapter plate 26.

[0041] The top end of the indirect adapter plate 26 is connected to the flexible structure, and the bottom end of the indirect adapter plate 26 is connected to the blocking mass block 24 . The flexible connecting pipe 3 is relatively connected to the blocking mass block 24 through the indirect adapter plate 26 .

[0042] A first indirect acceleration sensor is fixedly connected to the indirect upper cover plate 25 , and a second indirect acceleration sensor is fixedly connected to the indirect adapter plate 26 .

[0043] According to ISO 10846-3, when the vibration acceleration level at the input end is 20dB higher than the vibration acceleration at the output end, the dynamic stiffness of the flexible pipe 3 can be calculated by the following formula:

[0044]

[0045] Where: m2 is the mass of the blocking mass block, m f is the mass of the transition tooling, a2 is the acceleration at the output end, and a1 is the acceleration at the input end.

[0046] In the system composed of the flexible pipe 3, the blocking mass block 24, and the airbag 23, the dynamic stiffness of the flexible pipe 3 is rewritten from the above formula as follows:

[0047]

[0048] Where: m2 is the mass of the blocking mass block, m f is the mass of the transition tooling, a2 is the acceleration at the output end, a1 is the acceleration at the input end; Z n is the impedance of the flexible pipe; Z t is the airbag impedance; Z m is the blocking mass impedance.

[0049] When Z n -(2πf) 2 (m2+m f )+Z t=0, the measured dynamic stiffness value will have a peak value, which is the anti-resonance point of the system. When the blocking mass increases or the dynamic stiffness of the flexible tube to be tested decreases, the anti-resonance point of the system will shift to the low frequency band. The lower limit frequency of the indirect method test needs to avoid the anti-resonance point of the system, and at the same time ensure that the vibration acceleration level of the input end is 20dB higher than the vibration acceleration of the output end. Increasing the lower limit frequency of the indirect method test frequency band is conducive to reducing the weight of the blocking mass, reducing the bench design cost and test difficulty.

[0050] By reasonably splitting the test frequency bands and designing test benches in their advantageous frequency bands according to the test mechanisms of the direct and indirect methods, the problem that a single test bench is difficult to meet the needs of wide-band dynamic stiffness testing is solved.

[0051] Reference Figure 1 , Figure 2 A gantry 4 is provided on the outside of the flexible tube 3 for the direct test bench 1 and the indirect test bench 2 for the flexible tube. The height of the top crossbeam of the gantry 4 is higher than that of the direct upper cover plate 14 and the indirect upper cover plate 25. A vibration machine 41 is suspended on the gantry 4, and the vibration ends of the vibration machine 41 are respectively fixed to the direct upper cover plate 14 or the indirect upper cover plate 25.

[0052] In this application, the term "plurality" means at least two or more than two, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0053] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. Large-caliber flexible pipe dynamic stiffness test bench, characterized by: The invention comprises a flexible pipe direct test bench (1) and a flexible pipe indirect test bench (2), wherein the flexible pipe direct test bench (1) comprises a direct test base (11), a direct force plate (12) is arranged on the direct test base (11), a direct transition installation component is arranged on the direct force plate (12), and the direct installation component is installed on the flexible pipe (3); the flexible pipe indirect test bench (2) comprises an indirect test base (21), a blocking mass block (24) is arranged on the indirect test base (21), an indirect transition installation component is arranged above the blocking mass block (24), and the indirect transition installation component is installed on the flexible pipe (3), and the indirect transition installation component and the direct transition installation component are provided with vibration test components.

2. The large-diameter flexible pipe dynamic stiffness test bench according to claim 1 is characterized in that: The test range of the flexible pipe direct test bench (1) is 10Hz-f L , f L The range is 200Hz-300Hz.

3. The large-diameter flexible pipe dynamic stiffness test bench according to claim 1 is characterized by: The direct transition installation assembly comprises a direct upper cover plate (14), the direct upper cover plate (14) is fixedly connected to the flexible pipe (3), the bottom end of the flexible pipe (3) is fixedly connected to a direct lower cover plate (15), and the direct upper cover plate (14) and the direct lower cover plate (15) seal the interior of the flexible pipe (3).

4. The large-diameter flexible pipe dynamic stiffness test bench according to claim 3 is characterized by: A direct adapter plate (13) is arranged between the direct lower cover plate (15) and the direct force measuring plate (12); the top end of the direct adapter plate (13) is fixed to the direct lower cover plate (15), and the bottom end of the direct adapter plate (13) is fixed to the direct force measuring plate (12).

5. The large-diameter flexible pipe dynamic stiffness test bench according to claim 1 is characterized by: The test range of the flexible pipe indirect test bench (2) is f H -1000Hz, f H The range is 200Hz-300Hz.

6. The large-diameter flexible pipe dynamic stiffness test bench according to claim 1 is characterized by: The indirect transition installation assembly comprises an indirect upper cover plate (25), the indirect upper cover plate (25) is fixedly connected to the flexible pipe (3), the bottom end of the flexible pipe (3) is fixedly connected to an indirect adapter plate (26), and the indirect adapter plate (26) and the upper cover plate seal the interior of the flexible pipe (3).

7. The large-diameter flexible pipe dynamic stiffness test bench according to claim 6 is characterized by: A support frame (22) is provided at the bottom end of the blocking mass block (24), an air bag (23) is provided between the bottom end of the support frame (22) and the indirect testing base (21), and the air bag (23) supports the support frame (22).

8. The large-diameter flexible pipe dynamic stiffness test bench according to claim 6 is characterized by: The indirect upper cover plate (25) is fixedly connected to a first indirect acceleration sensor, and the indirect adapter plate (26) is fixedly connected to a second indirect acceleration sensor.

9. The large-diameter flexible pipe dynamic stiffness test bench according to claim 8 is characterized by: When the vibration acceleration level at the input end is 20dB higher than the vibration acceleration at the output end, the calculation formula for the dynamic stiffness of the flexible tube is as follows: Where: m2 is the mass of the blocking mass block; m f is the mass of the transition tooling; a2 is the acceleration at the output end; a1 is the acceleration at the input end; Z n is the impedance of the flexible pipe; Z t is the airbag impedance; Z m is the blocking mass impedance.

10. The large-diameter flexible pipe dynamic stiffness test bench according to claim 1 is characterized by: The vibration test assembly comprises a gantry (4), a vibration exciter (41) is suspended on the gantry (4), and the excitation end of the vibration exciter (41) is respectively connected to the direct transition installation assembly and the indirect transition installation assembly.

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