Vibration fatigue test method for ducts

Abstract

The present invention discloses two catheter vibration fatigue test methods, which relate to the field of physical testing methods, and the purpose is to shorten the catheter test cycle and improve the test efficiency. The first catheter vibration fatigue test method is used for single stress multi-catheter vibration fatigue test at the same time. The multiple catheters to be tested are first processed into the same length, and then the first-order static frequency of each catheter is measured and divided into three categories: underfrequency state, satisfied state and overfrequency state. The catheters in the underfrequency state and overfrequency state are then frequency modulated, and finally all catheters are simultaneously subjected to cycle life test under fixed fatigue strength load. The second catheter vibration fatigue test method is to first process the catheter to a standard length, obtain the frequency-stress distribution diagram of the catheter, and then obtain the test frequency corresponding to each stress level through the frequency-stress distribution diagram, calculate the test length according to the formula according to each test frequency, and then process the catheter according to the test length and frequency modulate it, and finally all catheters are subjected to the lifting method to determine the fatigue limit test.

Description

Technical Field

[0001] The invention relates to the field of physical testing methods, and in particular to two methods for simultaneously performing vibration fatigue tests on a plurality of conduits. Background Art

[0002] Aircraft engine conduits are mainly used for the transfer of fuel or gas. Conduits are mainly composed of pipe bodies and pipe joints, which are usually fixed by flaring, brazing or argon arc welding. The operating conditions of aircraft engines are often accompanied by vibrations, which may cause cracks in the conduits and lead to failures. In order to ensure the safety and reliability of conduit connections, vibration fatigue tests on conduits are required to determine the weak points of pipeline strength and their fatigue limits.

[0003] The traditional catheter vibration fatigue test method is to test a single catheter separately, use a fixture to clamp the joint of the catheter, use the resonance method to measure the natural frequency and stress distribution of the first-order bending vibration of the catheter on an electromagnetic vibration table, and then use the lifting method to test each catheter one by one to determine the fatigue limit, or determine the cycle life of the catheter under a certain fixed fatigue strength load. Since the catheter is a thin-walled structure and has a long length, its natural frequency is low, making the test cycle very long. The vibration fatigue test time is generally 100 to 200 hours. Due to the uniformity of the wall thickness of the catheter and the processing error, the natural frequency of each catheter is different, and it is not possible to perform vibration fatigue tests on multiple samples at the same time. Summary of the invention

[0004] The present invention first provides a catheter vibration fatigue test method, which can realize single stress multi-catheter vibration fatigue test at the same time, aiming to improve the test efficiency of the catheter and shorten the test cycle. The technical scheme adopted is: the catheter vibration fatigue test method comprises the following steps:

[0005] S1. Process at least two catheters to be tested to have the same length. For example, the actual length difference between any two catheters is no more than 0.02 mm.

[0006] S2. Perform a frequency sweep test on each conduit to determine the first-order static frequency of each conduit, and then classify all conduits into three categories: under-frequency state, satisfied state, and over-frequency state according to the first-order static frequency according to the test error requirements. For example, after determining the first-order static frequency of each conduit, calculate the average first-order static frequency of all conduits, and then expand the average first-order static frequency according to the test error requirements, and then use it as the range of the first-order static frequency of the satisfied state.

[0007] S3. Perform frequency modulation on the catheter in the under-frequency state and the over-frequency state, and perform a frequency sweep test until the first-order static frequency of the catheter reaches a satisfactory state.

[0008] Specifically: grind one end of the under-frequency conduit, and perform a frequency sweep test after grinding. If the first-order static frequency reaches a satisfactory state, the frequency modulation process is completed. Otherwise, grind again and perform a frequency sweep test until the first-order static frequency reaches a satisfactory state. For example, the single grinding amount is 0.02-0.05mm.

[0009] Specifically: For the over-frequency state of the catheter, a frequency modulation ring is fixedly installed on the outside of the catheter so that the first-order static frequency of the catheter reaches a satisfactory state. For example, the finite element analysis method is used to calculate the parameters of the frequency modulation ring that makes the first-order static frequency of the catheter reach the under-frequency state according to the fixed position of the frequency modulation ring set in the catheter, and then the frequency modulation ring with corresponding parameters is welded and fixed to the corresponding position of the catheter, and then the catheter is swept, and then the frequency is modulated according to the above-mentioned processing method for the catheter in the under-frequency state until the first-order static frequency of the catheter reaches a satisfactory state. Generally, the frequency modulation ring is fixed to the catheter by brazing or spot welding at a position 5 to 10 mm away from the front end of the catheter.

[0010] S4. Perform a cycle life test under a fixed fatigue strength load on the catheter in the satisfied state and the catheter after frequency modulation treatment at the same time.

[0011] The above-mentioned catheter vibration fatigue test method performs a frequency sweep test on multiple catheters to obtain the first-order static frequency of each catheter, and then determines the acceptable first-order static frequency range in combination with the acceptable error of the test, classifies the catheters within the acceptable first-order static frequency range as satisfied, and performs frequency modulation processing on the catheters outside the acceptable first-order static frequency range so that their first-order static frequencies are within the acceptable first-order static frequency range. Finally, the first-order static frequencies of all catheters fall within the acceptable first-order static frequency range, so that all catheters can be subjected to vibration fatigue tests at the same time. The present invention adjusts the first-order static frequencies of multiple catheters to the range allowed by the test, and can simultaneously perform cycle life tests on multiple catheters under fixed fatigue strength loads, thereby improving the efficiency of the test. The frequency modulation processing method for catheters in overclocked states and satisfied states is simple and effective, and the processing is convenient and accurate.

[0012] The present invention also provides another catheter vibration fatigue test method for performing a vibration fatigue test with multi-stress level control, the purpose of which is to shorten the test cycle. The technical solution adopted is: the catheter vibration fatigue test method comprises the following steps:

[0013] B1. According to the test requirements, a typical piece of catheter is selected and processed to the standard length l0. For example, the difference between the actual length l of the catheter and the standard length l0 is no more than 0.02mm.

[0014] B2. Sweep the processed catheter and measure the stress σ at each frequency f to obtain a frequency-stress distribution diagram.

[0015] B3. According to the stress level σi and its level j required by the test, the test frequency fi corresponding to each stress level σi is obtained through the frequency-stress distribution diagram, where i is an integer from 1 to j, and j ≥ 2 and is an integer.

[0016] B4. Calculate the test length l corresponding to the test frequency fi i , the calculation formula is:

[0017] Where: E is the elastic modulus of the catheter material, I is the section inertia moment, ρ is the density of the catheter material, A is the cross-sectional area, k is the frequency coefficient, and k is generally taken as 1.875104.

[0018] B5. Place the catheter to be tested according to the test length l i After processing, we get j roots with a length of l i For example, the actual length error of j catheters is no more than 0.02 mm.

[0019] B6. Perform sweep frequency tests on j ducts respectively to determine the first-order static frequency of each duct. Then, according to the test error requirements, expand the test frequency fi and use it as the range of the first-order static frequency of the satisfied state. The j ducts are divided into three categories: satisfied state, under-frequency state and over-frequency state.

[0020] B7. Same as S3 mentioned above.

[0021] B8. Perform fatigue limit test of the satisfied conduit and j conduits after frequency modulation at the same time according to stress level σi by the lifting and lowering method.

[0022] The present invention is used for the catheter vibration fatigue test method for performing multi-stress level control, which enables multiple stress levels to be tested in one time, greatly shortens the time and reduces the test cost.

[0023] The present invention also provides a catheter clamping device for fixing multiple catheters on a vibration table to achieve vibration fatigue testing of the multiple catheters at the same time, with the aim of saving test time and thus improving test efficiency.

[0024] A catheter clamping device comprises a base and a cover plate, wherein the base comprises a top plate, a bottom plate and a connecting column connecting the top plate and the bottom plate, at least two mounting holes penetrating the bottom plate are arranged on the bottom plate, each mounting hole is equipped with a connecting bolt, at least two tensioning bolts are arranged between the cover plate and the top plate, and at least two half grooves are respectively arranged on the bottom surface of the cover plate and the top surface of the top plate, and the half grooves of the cover plate and the half grooves of the top plate are adapted to each other to form a card groove.

[0025] The catheter clamping device can be used to implement S4 and B8 of the above two catheter vibration fatigue test methods. The base is fixed to the vibration table by connecting bolts, and each catheter is placed in the groove formed by the base and the cover plate and clamped by tightening bolts before testing.

[0026] Furthermore, the bottom surface of the cover plate and the top surface of the top plate are both circular and have the same diameter, and the half grooves of the cover plate are arranged at equal central angles along the radius direction of the circle.

[0027] Furthermore, the half groove of the cover plate and the half groove of the top plate are in the shape of a bad arc in cross section.

[0028] Furthermore, the tension bolt is arranged between the half grooves, and a central bolt is arranged at the center of the cover plate to be connected with the base.

[0029] S4 and B8 of the above two conduit vibration fatigue test methods are implemented using a conduit clamping device, which can fix all conduits with the same number of slots on the vibration table to achieve the purpose of testing multiple conduits at the same time. The half slots of the cover plate and the half slots of the top plate are arranged at equal central angles along the radius direction of the circle, balancing the deflection load of the device during the vibration test and reducing the stiffness requirements of the device. The half slots of the cover plate and the half slots of the top plate are in the shape of a minor arc in cross section, ensuring that the conduit can be firmly clamped by the cover plate and the top plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the catheter clamping device in the present invention.

[0031] Figure 2 yes Figure 1 A schematic longitudinal section of the catheter clamping device shown.

[0032] Figure 3 yes Figure 1 Schematic diagram of the structure of the middle base.

[0033] Figure 4 yes Figure 1 Schematic diagram of the structure of the middle cover.

[0034] Figure 5 yes Figure 1 Schematic diagram of the structure of the center bolt.

[0035] Figure 6 yes Figure 1 Schematic diagram of the structure of the tension bolt.

[0036] Figure numerals: base 1, top plate 11, bottom plate 12, connecting column 13, mounting hole 14, cover plate 2, tightening bolt 3, center bolt 4, conduit 5, frequency modulation ring 6. DETAILED DESCRIPTION

[0037] Vibration fatigue tests can be divided into two types: single-stage stress control and multi-stress stage control. The two catheter vibration fatigue test methods provided by the present invention correspond to these two control modes respectively.

[0038] The first catheter vibration fatigue test method provided by the present invention is used to perform a single stress controlled vibration fatigue test on at least two catheters, comprising the following steps:

[0039] S1. Process at least two catheters to be tested into the same length. The lengths of the catheters are as consistent as possible, taking into account the actual processing accuracy, for example, the actual length difference between any two catheters is controlled to be no greater than 0.02 mm.

[0040] S2. Perform a frequency sweep test on each conduit to determine the first-order static frequency of each conduit. Then, based on the test error requirements, divide all conduits into three categories: under-frequency state, satisfied state, and over-frequency state according to the first-order static frequency.

[0041] Each conduit is classified into one of three categories according to its first-order static frequency: under-frequency state, satisfied state and over-frequency state. For example, after measuring the first-order static frequency of each conduit, the first-order static frequency average value of all conduits is calculated. The first-order static frequency average value can be the arithmetic mean of each conduit, and then the first-order static frequency average value is expanded according to the test error requirements. The interval obtained after the expansion is the range of the first-order static frequency of the satisfied state. Exceeding this range is the over-frequency state, and below this range is the under-frequency state.

[0042] S3. Perform frequency modulation on the catheter in the under-frequency state and over-frequency state, and conduct a frequency sweep test until the first-order static frequency of the catheter reaches a satisfactory state. Frequency modulation is to process the catheter so as to increase or decrease the first-order static frequency of the catheter.

[0043] The following is a method for frequency modulation of the catheter in the under-frequency state: polish one end of the catheter, and perform a frequency sweep test after polishing. If the first-order static frequency reaches a satisfactory state, the frequency modulation process is completed, otherwise polish again and perform a frequency sweep test until the first-order static frequency reaches a satisfactory state. Among them, the front end of the catheter is generally polished, the front end is the free end, and the rear end is the clamping end, and the rear end is used for clamping and testing. The polishing of the catheter is generally carried out in multiple times to avoid excessive frequency modulation processing. For example, the polishing amount is 0.02 to 0.05 mm as a gradient, that is, the single polishing amount is 0.02 to 0.05 mm. After each gradient is completed, the typical catheter is swept again until the first-order static frequency reaches a satisfactory state.

[0044] The following is a method for frequency modulation of the over-frequency state of the duct: a frequency modulation ring is fixedly installed on the outside of the duct to make the first-order static frequency of the duct reach a satisfactory state. Figure 1, frequency modulation, 6 is a circular ring structure, the inner diameter of the frequency modulation ring 6 is adapted to the outer diameter of the catheter, interference fitting, the interference amount is not greater than 0.05, the outer diameter and width of the frequency modulation ring 6 are determined according to the frequency modulation requirements of the ultra-frequency state catheter.

[0045] Considering the accuracy of frequency modulation processing, for over-frequency catheters, the frequency modulation ring can be used to modulate the catheter to an under-frequency state first, and then polished to a satisfactory state. For example, using the finite element analysis method, according to the fixed position of the frequency modulation ring in the catheter, the frequency modulation ring is generally fixed at a position 5 to 10 mm away from the front end of the catheter, and the parameters of the frequency modulation ring that makes the first-order static frequency of the catheter reach the under-frequency state are calculated. The parameters of the frequency modulation ring include the inner and outer diameters and the width, and then the frequency modulation ring with corresponding parameters is welded and fixed to the corresponding position of the catheter, for example, fixed to the catheter by brazing or spot welding, and then the catheter is swept, and then the frequency is modulated according to the above-mentioned method for processing the catheter in the under-frequency state until the first-order static frequency of the catheter reaches a satisfactory state.

[0046] S4. Perform cycle life test under fixed fatigue strength load on the tubes in the satisfied state and the tubes after frequency modulation treatment at the same time. After the frequency modulation treatment in step S3, all tubes are in the satisfied state, and all tubes are tested at the same time. Adjust the parameters of the electromagnetic vibration table and data acquisition system until the frequency, stress, etc. specified in the test requirements are met and start the formal test until the specified number of test cycles is completed.

[0047] The second catheter vibration fatigue test method provided by the present invention is used for performing a vibration fatigue test with multi-stress level control, and comprises the following steps:

[0048] B1. According to the test requirements, a typical piece of catheter is selected and processed to the standard length l0. The standard length l0 is determined according to the test requirements and is known data. Considering the actual processing accuracy, for example, the difference between the actual length l of the catheter and the standard length l0 is no more than 0.02mm.

[0049] B2. Perform a frequency sweep on the processed catheter and measure the stress σ at each frequency f to obtain a frequency-stress distribution diagram. The horizontal axis of the frequency-stress distribution diagram is the frequency f, and the vertical axis is the stress σ. The curve of the stress σ is normally distributed.

[0050] B3. According to the stress level σi and its level j required by the test, the test frequency fi corresponding to each stress level σi is obtained through the frequency-stress distribution diagram, where i is an integer from 1 to j, and j ≥ 2 and is an integer. Stress level σi represents j data, which are σ1 to σj; test frequency fi represents j data, which are f1 to fj. Through step B3, the stress control of the test is converted into test frequency control.

[0051] B4. Calculate the test length l corresponding to the test frequency fi i, the calculation formula is:

[0052] Where: E is the elastic modulus of the catheter material, I is the section inertia moment, ρ is the density of the catheter material, A is the cross-sectional area, k is the frequency coefficient, and k is generally taken as 1.875104. Test length l i Represents j data, which are l1~l j .

[0053] B5. Place the catheter to be tested according to the test length l i After processing, the lengths of j roots are l i Considering the actual processing accuracy, for example, the actual length error of j catheters is no more than 0.02mm.

[0054] B6. Perform sweep frequency tests on j ducts respectively to determine the first-order static frequency of each duct. Then, according to the test error requirements, expand the test frequency fi and use it as the range of the first-order static frequency of the satisfied state. The j ducts are divided into three categories: satisfied state, under-frequency state and over-frequency state.

[0055] For the j conduits obtained by B4, they are classified according to the difference between their first-order static frequency and the corresponding test frequency fi. The test frequency fi is expanded from a point value to a range according to the test error requirements. If the first-order static frequency of the conduit falls within the range, the conduit is judged to be in a satisfied state; if the first-order static frequency of the conduit is greater than the range, the conduit is judged to be in an over-frequency state; if the first-order static frequency of the conduit is less than the range, the conduit is judged to be in an under-frequency state.

[0056] B7. Same as S3 mentioned above.

[0057] B8. Perform fatigue limit test of j tubes in the satisfied state and tubes after frequency modulation at the same time according to stress level σi by ascending and descending method. Sort the tubes in descending order according to the test stress, and load each tube into the test device in turn, and then realize multi-stress level control. Adjust the parameters of the electromagnetic vibration table and data acquisition system until the frequency, stress, etc. specified in the test requirements are met and start the test until the specified number of test cycles is completed.

[0058] For the second duct vibration fatigue test method, the following is an example of three-level control, that is, the value of j is 3. According to the traditional single duct test method, three tests are required to complete three stress levels. With this method, only one test is required. Taking a typical part of a brazed pipeline with a diameter of 10mm for a certain type of engine as an example, the materials of the duct and the pipe joint are both 1Cr18Ni9Ti, and the cycle base N0 = 1×10 7, the frequency is 229Hz, and one test takes about 12.1h. According to the traditional test method, it takes 36.3h to complete three stress levels, while according to the method of the present invention, it only takes 12.1h to complete three stress levels, which greatly shortens the test cycle and reduces the test cost.

[0059] The present invention also provides a catheter clamping device, which is used to fix multiple catheters on a vibration table to achieve vibration fatigue testing of multiple catheters at the same time. Figure 1 The catheter clamping device can be used to implement S4 and B8 of the above two catheter vibration fatigue test methods. In step S4, the base 1 is fixedly installed on the vibration table by connecting bolts, and each catheter is placed in the slot formed by the base 1 and the cover plate 2 and clamped by the tightening bolts 3 before testing; in step B8, the base 1 is fixedly installed on the vibration table by connecting bolts, and each catheter is placed in the slot formed by the base 1 and the cover plate 2 and clamped by the tightening bolts 3 before testing.

[0060] See also Figure 1 The catheter clamping device includes a base 1 and a cover plate 2. The base 1 includes a top plate 11, a bottom plate 12, and a connecting column 13 connecting the top plate 11 and the bottom plate 12. The top plate 11, the bottom plate 12, and the connecting column 13 are preferably an integral body and made of metal. The bottom surface of the bottom plate 12 is preferably flat, so that it can be placed stably on the vibration table. At least two mounting holes 14 that pass through the bottom plate 12 are provided on the bottom plate 12, and each mounting hole 14 is equipped with a connecting bolt, which is used to fix the base 1 on the vibration table. For example, the base 1 is in the shape of a red wine glass, the bottom plate 12 is a circular plate with mounting holes 14 distributed along the circumference, and a cylindrical connecting column 13 is provided in the middle of the bottom plate 12. The connecting column 13 and the bottom plate 12 have an arc transition, and the arc diameter is not less than 10 mm.

[0061] At least two half grooves are respectively arranged on the top surface of the top plate 11 and the bottom surface of the cover plate 2. The half grooves of the cover plate 2 and the half grooves of the top plate 11 are adapted to each other and form a clamping groove. At least two tension bolts 3 are arranged between the cover plate 2 and the top plate 11. The top surface of the top plate 11 and the bottom surface of the cover plate 2 are consistent in shape. Based on the consideration of force balance, the bottom surface of the cover plate 2 and the top surface of the top plate 11 are both circular and have equal diameters. The half grooves of the cover plate 2 are arranged at equal central angles along the radius direction of the circle. There are multiple clamping grooves, preferably arranged at equal central angles along the circumference of the cover plate 2 and the top plate 11, and each half groove is located in the radius direction of the circle.

[0062] The two half grooves are combined to form a complete slot, and the half groove is preferably an arc groove. The slot formed by the two half grooves is circular in cross section, and the diameter of the circle is adapted to the outer diameter of the clamping end of the catheter. In order to enable the cover plate 2 and the top plate 11 to firmly clamp and fix the catheter 5, the half groove of the cover plate 2 and the half groove of the top plate 11 are in the shape of an inferior arc in cross section. For example, the center line of the half groove of the cover plate 2 is 1 mm lower than the bottom surface of the cover plate 2, and the center line of the half groove of the top plate 11 is 1 mm lower than the top surface of the top plate 11.

[0063] The cover plate 2 and the top plate 11 are connected by the tension bolt 3. For example, the tension bolt 3 is a hexagonal head universal bolt, and the length of the screw is not less than the sum of the thickness of the cover plate 2 and half of the thickness of the top plate 11. In order to improve the stability between the cover plate 2 and the top plate 11, a central bolt 4 is also provided at the center of the cover plate 2 to connect with the base 1, and the tension bolt 3 is provided between the half grooves. The depth of the central bolt 4 should be not less than 10 times the pitch size of the central bolt 4 thread.

Claims

1. A catheter vibration fatigue test method, characterized in that: The following steps are involved: S1. Processing at least two catheters to be tested into the same length; S2. Perform a frequency sweep test on each conduit to determine the first-order static frequency of each conduit. Then, according to the test error requirements, all conduits are divided into three categories: under-frequency state, satisfied state and over-frequency state according to the first-order static frequency. S3, frequency modulation processing is performed on the catheter in the under-frequency state and the over-frequency state, and a frequency sweep test is performed until the first-order static frequency of the catheter reaches a satisfactory state; The frequency modulation process is performed in at least one of the following two ways: Method 1: Grind one end of the under-frequency conduit, and then perform a frequency sweep test. If the first-order static frequency reaches a satisfactory state, the frequency modulation process is completed. Otherwise, grind again and perform a frequency sweep test until the first-order static frequency reaches a satisfactory state. Method 2: For the over-frequency conduit, a frequency modulation ring is fixedly installed on the outside of the conduit, and the finite element analysis method is used to calculate the parameters of the frequency modulation ring that makes the first-order static frequency of the conduit reach the under-frequency state according to the set fixed position of the frequency modulation ring on the conduit, and then the frequency modulation ring with corresponding parameters is welded and fixed to the corresponding position of the conduit, and then the conduit is swept, and then the frequency is modulated according to the treatment method of the conduit in the under-frequency state in method 1 until the first-order static frequency of the conduit reaches the satisfied state; S4. Perform a cycle life test under a fixed fatigue strength load on the catheter in the satisfied state and the catheter after frequency modulation treatment at the same time.

2. The catheter vibration fatigue test method according to claim 1, characterized in that: In step S2, after the first-order static frequency of each conduit is measured, the average first-order static frequency of all conduits is calculated, and then the average first-order static frequency is expanded according to the test error requirement, and then used as the range of the first-order static frequency of the satisfied state.

3. The catheter vibration fatigue test method according to claim 1 or 2, characterized in that: Satisfy at least one of the following three conditions: a. In step S1, the actual length difference between any two catheters is no more than 0.02 mm; b. In the frequency modulation processing method 1 of step S3, the single grinding amount is 0.02-0.05 mm; c. In the second frequency modulation processing method of step S3, the frequency modulation ring is fixed to the catheter at a position 5 to 10 mm away from the front end surface of the catheter by brazing or spot welding.

4. A catheter vibration fatigue test method, characterized in that: The following steps are involved: B1. According to the test requirements, select a typical piece of catheter and process it to the standard length l0; B2. Sweep the processed catheter and measure the stress σ at each frequency f to obtain a frequency-stress distribution diagram; B3. According to the stress level σi and its level j required by the test, the test frequency fi corresponding to each stress level σi is obtained through the frequency-stress distribution diagram, where i is an integer from 1 to j, and j ≥ 2 and is an integer; B4. Calculate the test length l corresponding to the test frequency fi i , the calculation formula is: Where: E is the elastic modulus of the catheter material, I is the section inertia moment, ρ is the density of the catheter material, A is the cross-sectional area, and k is the frequency coefficient; B5. Place the catheter to be tested according to the test length l i After processing, we get j roots with a length of l i of the catheter; B6. Perform sweep frequency tests on j conduits respectively to determine the first-order static frequency of each conduit. Then, according to the test error requirements, expand the test frequency fi and use it as the range of the first-order static frequency of the satisfied state. The j conduits are divided into three categories: satisfied state, under-frequency state and over-frequency state. B7, the same as step S3 of the catheter vibration fatigue test method according to any one of claims 1 to 3; B8. Perform fatigue limit test of the satisfied conduit and j conduits after frequency modulation at the same time according to stress level σi by the lifting and lowering method.

5. A catheter vibration fatigue test method, characterized in that: Conducting the test according to the catheter vibration fatigue test method according to any one of claims 1 to 4, When the test is performed according to the conduit vibration fatigue test method according to any one of claims 1 to 3, in step S4, the base (1) is fixedly mounted on the vibration table by connecting bolts, and each conduit is placed in a slot formed by the base (1) and the cover plate (2) and clamped by tightening bolts (3), and then the test is performed; When the test is conducted according to the conduit vibration fatigue test method of claim 4, in step B8, the base (1) is fixedly mounted on the vibration table by connecting bolts, and each conduit is placed in a slot formed by the base (1) and the cover plate (2) and clamped by tightening bolts (3), and then the test is conducted; The catheter clamping device comprises a base (1) and a cover plate (2), the base (1) comprises a top plate (11), a bottom plate (12) and a connecting column (13) connecting the top plate (11) and the bottom plate (12), at least two mounting holes (14) penetrating the bottom plate (12) are arranged on the bottom plate (12), each mounting hole (14) is equipped with a connecting bolt, at least two tensioning bolts (3) are arranged between the cover plate (2) and the top plate (11), and at least two half grooves are respectively arranged on the bottom surface of the cover plate (2) and the top surface of the top plate (11), and the half grooves of the cover plate (2) and the half grooves of the top plate (11) are mutually adapted to form a clamping groove.

6. The catheter vibration fatigue test method according to claim 5, characterized in that: The bottom surface of the cover plate (2) and the top surface of the top plate (11) are both circular and have the same diameter, and the half grooves of the cover plate (2) are arranged at equal central angles along the radius direction of the circle.

7. The catheter vibration fatigue test method according to claim 5, characterized in that: The half groove of the cover plate (2) and the half groove of the top plate (11) are in the shape of a bad arc in cross section.

8. The catheter vibration fatigue test method according to any one of claims 5 to 7, characterized in that: The tension bolt (3) is arranged between the half grooves, and a central bolt (4) is also arranged at the center of the cover plate (2) to be connected with the base (1).

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