Axial compression testing device and testing method for marine cable

Abstract

An embodiment of the present invention provides an axial compression test device and a test method for a marine cable, which relate to the field of marine cables. The axial compression test device for a marine cable includes a first end limit clamp, a second end limit clamp, an intermediate limit clamp, a force brake, and a rotation brake. The first end limit clamp is clamped at the first end of the marine cable, the second end limit clamp is clamped at the second end of the marine cable, and the intermediate limit clamp is clamped at the middle of the marine cable. The test device of the embodiment of the present invention utilizes the first end limit clamp and the second end limit clamp to clamp at both ends of the marine cable respectively, and then utilizes the rotation brake to place the marine cable in different bending conditions, while applying axial pressure to the marine cable through the force brake, thereby more realistically simulating the force on the marine cable under actual conditions, so as to more accurately measure the axial compression value of the marine cable. An embodiment of the present invention also provides a test method, which is implemented based on the axial compression test device.

Description

Technical Field

[0001] The present invention relates to the field of marine cables, and in particular to an axial compression testing device and a testing method for marine cables. Background Art

[0002] During installation or operation, submarine cables may be subjected to axial compressive loads. Large axial compressive loads may cause local buckling of the submarine cable, affecting the integrity and use of the submarine cable structure.

[0003] Currently, axial compression testing is often performed on short specimens, applying axial loads directly to both ends of the cable. Existing research indicates that localized buckling in cables is often associated with compressive loads and cyclic bending. However, this testing method ignores the effects of bending on cables during axial compression, leading to significant deviations from the actual permissible cable capacity. Summary of the Invention

[0004] The present invention provides an axial compression test device and a test method for a marine cable, which can perform an axial compression test when the cable is bent, thereby improving the accuracy of testing the actual axial compression value of the marine cable.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] An embodiment of the present invention provides an axial compression test device for a marine cable, comprising:

[0007] A first end limiting clamp, the first end limiting clamp is used to be arranged at the first end of the marine cable;

[0008] A second end limiting clamp, the second end limiting clamp is used to be arranged at the second end of the marine cable;

[0009] An intermediate limiting clamp is provided between the first end limiting clamp and the second end limiting clamp. The intermediate limiting clamp is used to clamp the middle part of the marine cable and can slide freely as the marine cable bends.

[0010] A force brake is provided at the end of the marine cable and is used to apply an axial compressive load to the marine cable;

[0011] Rotation brakes are used to apply cyclic bending loads to marine cables.

[0012] Optionally, there are multiple intermediate limiting clamps, and the multiple intermediate limiting clamps are arranged at intervals from each other.

[0013] Optionally, the axial compression test device further includes a test frame, the first end limit clamp and the second end limit clamp are fixedly arranged on the test frame, and the middle limit clamp is movably arranged on the test frame.

[0014] Optionally, a slide plate is provided on the test stand, a slide plate is provided with a slide groove, the middle limit clamp is connected to the slide plate and the middle limit clamp can slide along the slide groove.

[0015] Optionally, the test frame includes multiple vertical support beams, multiple transverse support beams and multiple connecting beams, the two ends of each transverse support beam are respectively connected to two adjacent vertical support beams, and the two ends of each connecting beam are respectively connected to two adjacent transverse support beams.

[0016] Optionally, there are two rotation brakes, which are respectively located at both ends of the marine cable, one of which is connected to the first end limit clamp, and the other is connected to the second end limit clamp.

[0017] Optionally, the axial compression testing device further includes a plurality of inclination sensors, which are respectively arranged at different positions of the outer side wall of the marine cable.

[0018] Optionally, the middle limiting clamp includes at least one pair of horizontal rollers and at least one pair of vertical rollers, wherein the pair of horizontal rollers are spaced apart and arranged in parallel, and the pair of vertical rollers are spaced apart and arranged in parallel.

[0019] An embodiment of the present invention further provides a testing method, using the above-mentioned axial compression testing device, comprising:

[0020] preparing a sample marine cable for testing and installing the sample marine cable into an axial compression testing device;

[0021] Apply an axial compressive load F1 to the sample marine cable through a force brake;

[0022] Apply a cyclic bending load to the sample ocean cable by rotating the brake, so that the sample ocean cable bends with a bending radius of R;

[0023] Obtain test results of the sample ocean cable, and evaluate the test results including whether the sample ocean cable is damaged.

[0024] Optionally, the step of evaluating the test results including whether the sample ocean cable is damaged comprises:

[0025] Visually inspect the appearance of the sample ocean cable to see if it is damaged, dissect the sample ocean cable and check if local buckling occurs inside the ocean cable.

[0026] Beneficial effects of the embodiments of the present invention:

[0027] The axial compression test device for a marine cable includes a first end limit clamp, a second end limit clamp, an intermediate limit clamp, a force brake, and a rotation brake. The first end limit clamp is clamped at the first end of the marine cable, the second end limit clamp is clamped at the second end of the marine cable, the intermediate limit clamp is arranged between the first end limit clamp and the second end limit clamp, and the intermediate limit clamp is clamped in the middle of the marine cable. The force brake applies an axial compression load to the marine cable. The test device of an embodiment of the present invention utilizes the first end limit clamp and the second end limit clamp to clamp the two ends of the marine cable respectively, then utilizes the rotation brake to place the marine cable in different bending conditions, and simultaneously applies axial pressure to the marine cable through the force brake, thereby more realistically simulating the force applied to the marine cable in actual conditions, so as to more accurately measure the axial compression value of the marine cable.

[0028] This testing method includes: preparing a sample marine cable for testing and installing the sample marine cable in an axial compression testing device; applying an axial compression load F1 to the sample marine cable via a force brake; applying a cyclic bending load to the sample marine cable via a rotary brake, causing the sample marine cable to bend with a bending radius R; obtaining test results for the sample marine cable and evaluating the test results, including whether the sample marine cable is damaged. Based on the aforementioned axial compression testing device, this testing method can accurately measure the actual axial compression value of the marine cable, thereby facilitating the understanding of the ultimate compression value and degree of damage to the marine cable. This testing method is simple to operate and can be repeated multiple times under different bending conditions or different axial compression loads, resulting in excellent functionality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 A schematic structural diagram of an axial compression testing device for a marine cable provided in an embodiment of the present invention;

[0031] Figure 2 A partially enlarged view of the intermediate limiting clip provided in an embodiment of the present invention;

[0032] Figure 3 A partially enlarged view of a first end limiting clip provided in an embodiment of the present invention;

[0033] Figure 4 A partially enlarged view of the second end limiting clip provided in an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the appearance of an umbilical cable provided in an embodiment of the present invention;

[0035] Figure 6 Schematic diagram of the cross-sectional structure of the umbilical cable provided in an embodiment of the present invention.

[0036] Icons: 1-first end limit clamp; 2-second end limit clamp; 3-middle limit clamp; 30-horizontal roller; 31-vertical roller; 4-test frame; 40-vertical support beam; 41-lateral support beam; 42-connecting beam; 5-slide plate; 50-chute; 6-umbilical cable; 60-end plate; 61-wire rope; 62-steel pipe; 63-hole; 7-force brake; 8-rotation brake. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0040] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0041] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0042] The terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0043] Unless otherwise expressly specified or limited, terms such as "disposed" and "connected" should be interpreted broadly. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] It should be noted that for the aforementioned various method embodiments, for simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, some steps can be performed in other orders or simultaneously. The steps in the method embodiments of this application can be adjusted in order, combined, or deleted according to actual needs.

[0045] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0046] At present, axial compression tests on submarine cables are mostly conducted using shorter sample submarine cables, such as those with a length of 0.5-1m. During the test, axial loads are directly applied to both ends of the sample submarine cable. This test method does not take into account that the submarine cable is not only subjected to a single axial compression load. In fact, the submarine cable is in a bent state while bearing the axial compression load. Therefore, the existing test method cannot accurately restore the load conditions that the submarine cable is subjected to during installation or operation. The test results deviate greatly from the actual allowable axial compression value of the submarine cable, and it is also impossible to accurately predict the failure or damage that may be caused by the axial compression load on the submarine cable.

[0047] Based on this, an embodiment of the present invention provides an axial compression test device and a test method for a marine cable. The test device and the test method can solve the above problems, which will be described in detail below.

[0048] Please refer to Figure 1The axial compression test device of the marine cable includes a first end limit clamp 1, a second end limit clamp 2, an intermediate limit clamp 3, a force brake 7 and a rotation brake 8. The first end limit clamp 1 is clamped at the first end of the marine cable, the second end limit clamp 2 is clamped at the second end of the marine cable, the intermediate limit clamp 3 is arranged between the first end limit clamp 1 and the second end limit clamp 2, the intermediate limit clamp 3 is clamped in the middle of the marine cable and can slide freely as the marine cable bends, the force brake 7 is arranged at one end of the second end limit clamp 2, the force brake 7 applies an axial compression load to the marine cable, and the rotation brake 8 is used to apply a cyclic bending load to the marine cable.

[0049] The testing device of the embodiment of the present invention utilizes a first end limit clamp 1 and a second end limit clamp 2 to clamp the ends of the marine cable, respectively. A rotary brake 8 is then used to place the marine cable in different bending conditions. Simultaneously, a force brake 7 is used to apply axial pressure to the marine cable, thereby more realistically simulating the forces acting on the marine cable under actual conditions and facilitating more accurate measurement of the axial compression value of the marine cable. It should be noted that the embodiment of the present invention, based on existing testing methods for marine cables, does not take into account that the marine cable is actually in a bent state. Therefore, the embodiment of the present invention uses a marine cable with a predetermined length for testing to simulate the changes in axial compression of the marine cable under different bending conditions.

[0050] In this embodiment, the middle limit clamp 3 includes a pair of horizontal rollers 30 and two pairs of vertical rollers 31. The pair of horizontal rollers 30 are spaced apart and arranged in parallel with each other, and the two pairs of vertical rollers 31 are also spaced apart and arranged in parallel with each other. The plane where the pair of horizontal rollers 30 are located is perpendicular to the plane where the two pairs of vertical rollers 31 are located, that is, the planes where the two pairs of vertical rollers 31 are located are parallel to each other; a pair of vertical rollers 31 is located at one end of the pair of horizontal rollers 30, and the other pair of vertical rollers 31 is located at the other end of the pair of horizontal rollers 30.

[0051] refer to Figure 2 The middle limit clamp 3 also includes a horizontal mounting seat and two vertical mounting seats, and the horizontal mounting seat is provided with four horizontal support ears, each horizontal support ear is provided with a slot hole, and the two ends of the horizontal roller 30 are sleeved with bearings and then installed in the slot holes of the horizontal support ears, so that the horizontal roller 30 can rotate; the two vertical mounting seats are perpendicular to the plane of the horizontal mounting seat, and the two vertical mounting seats are respectively located at the two ends of the horizontal roller 30. Each vertical mounting seat includes a top plate, a bottom plate and two side plates, and the two ends of the top plate are connected to one end of the two side plates, and the two ends of the bottom plate are connected to the other ends of the two side plates. A pair of vertical rollers 31 is arranged between the two side plates, and two top connecting holes are provided on the top plate, and two bottom connecting holes are provided on the bottom plate. The two top connecting holes correspond to the two bottom connecting holes, and bearings are installed in the top connecting hole and the bottom connecting hole. The two ends of the vertical roller 31 are inserted into the bearings, so that the vertical roller 31 can rotate.

[0052] When testing a sample marine cable using this testing device, the sample marine cable is placed through the gap between the two pairs of vertical rollers 31, with the surface of the sample marine cable in contact with a pair of horizontal rollers 30. The horizontal rollers 30 and vertical rollers 31 provided on the intermediate limit clamp 3 serve to support the sample marine cable and reduce friction between the sample marine cable and the outside world. This is because when bending and axially pressurizing the sample marine cable, it is necessary to eliminate other external forces to prevent external friction from adversely affecting the accuracy of the test results of the sample marine cable.

[0053] In this embodiment, a rotary brake 8 is provided at each end of the sample cable. By driving the rotary brake 8 to bend the cable, the intermediate limit clamp 3 can freely move according to the bending state of the cable. While more than two rotary brakes 8 are possible, at least one is provided at each end of the cable. Cyclic bending loads are applied to the cable to test the maximum axial compressive force it can withstand at a certain bending radius. The maximum axial compressive force that causes the cable to fail under the cyclic bending load is the maximum axial compressive force allowed by the cable at that bending radius.

[0054] In other embodiments, the sample marine cable can be bent by pulling the intermediate limit clamp 3. For example, the intermediate limit clamp 3 can be connected to a movable drive, which can be pulled and moved by the movable drive to thereby bend the sample marine cable. It is worth noting that the intermediate limit clamp 3 can be moved radially along the sample marine cable and in a unidirectional reciprocating manner. The movable drive can be pneumatic, hydraulic, or electric, such as using a cylinder or a push rod motor to move the intermediate limit clamp 3.

[0055] It should be known that the number of intermediate limit clamps 3 can be one or more, and the specific number of intermediate limit clamps 3 depends on the situation of the sample ocean cable. If the sample ocean cable is longer, more intermediate limit clamps 3 are required. When multiple intermediate limit clamps 3 are set, the multiple intermediate limit clamps 3 are arranged at intervals from each other.

[0056] In order to accurately grasp the degree of bending at various positions of the sample ocean cable during testing, multiple inclination sensors are set at different positions on the outer wall of the sample ocean cable. The multiple inclination sensors are used to detect the degree of bending deformation at various parts of the sample ocean cable.

[0057] refer to Figure 3 and Figure 4 The structures of the first end limit clamp 1 and the second end limit clamp 2 are similar to those of the middle limit clamp 3. The first end limit clamp 1 and the second end limit clamp 2 are also provided with horizontal rollers 30 and vertical rollers 31. The functions of the horizontal rollers 30 and the vertical rollers 31 are also the same as those in the middle limit clamp 3.

[0058] In other embodiments, the first end limit clamp 1 and the second end limit clamp 2 may also be other forms of clamping structures. The structures of the first end limit clamp 1 and the second end limit clamp 2 shown in the embodiments of the present invention are only for illustrative purposes and are not used to limit the structures of the first end limit clamp 1 and the second end limit clamp 2.

[0059] Continue to refer Figure 1 The axial compression test apparatus also includes a test frame 4, with a first end stopper 1 and a second end stopper 2 fixedly mounted on the test frame 4, and an intermediate stopper 3 movably mounted on the test frame 4. This facilitates manipulation of the sample marine cable during testing. To prepare for testing the sample marine cable, one end of the sample marine cable can be secured to the second end stopper 2, and an axial compressive load can then be applied via a force brake 7. The first end stopper 1 and the second end stopper 2 are fixed relative to each other and do not move.

[0060] In this embodiment, the test frame 4 includes four vertical support beams 40, two transverse support beams 41, and multiple connecting beams 42. The four vertical support beams 40 are of equal length, and the two transverse support beams 41 are of equal length. The two ends of one transverse support beam 41 are connected to the two vertical support beams 40, and the two ends of another transverse support beam 41 are connected to the other two vertical support beams 40. The two ends of the multiple connecting beams 42 are connected to the two transverse support beams 41, thereby connecting the four vertical support beams 40, the two transverse support beams 41, and the multiple connecting beams 42 to form a frame structure. Of course, the multiple connecting beams 42 are spaced apart and arranged in parallel.

[0061] Optionally, in order to reinforce the entire test frame 4 , a reinforcement rod may be provided between the four vertical support beams 40 , with both ends of the reinforcement rod being connected to two adjacent vertical support beams 40 .

[0062] In this embodiment, the first end limit clamp 1 and the second end limit clamp 2 are respectively located at the leftmost and rightmost ends of the test frame 4, that is, at the ends of the transverse support beam 41. The ends of the two transverse support beams 41 are connected to two fixing plates, with the first end limit clamp 1 fixed to one of the fixing plates and the second end limit clamp 2 fixed to the other fixing plate.

[0063] The intermediate limiting clamps 3 are arranged on the connecting beam 42 , and the intermediate limiting clamps 3 can be moved on the connecting beam 42 to facilitate carrying the sample ocean cable. The number of the intermediate limiting clamps 3 matches the number of the connecting beams 42 .

[0064] Optionally, the upper part of each connecting beam 42 is covered with a slide 5, the long side direction of the slide 5 is consistent with the long side direction of the connecting beam 42, and the slide 5 is provided with a slide groove 50 along its own long side direction. The lower part of the horizontal mounting seat of the middle limit clamp 3 is provided with a protruding slider, which is stuck in the slide groove 50 and can slide along the slide groove 50, thereby driving the entire middle limit clamp 3 to move.

[0065] After the test frame 4 of this embodiment is manufactured, its overall size and shape cannot be changed. Therefore, when designing the test frame 4, it is necessary to consider the types of sample ocean cables that may be tested and the length range of the sample ocean cables, so as to ensure that more types and more length ranges of sample ocean cables can be tested as much as possible.

[0066] In other embodiments, the test stand 4 may also have other forms of structures. This embodiment is merely described in an exemplary manner and is not intended to limit the structure and form of the test stand 4 .

[0067] The testing device of the embodiment of the present invention can be used to test a long sample ocean cable, placing the sample ocean cable in different bending conditions and applying an axial compression load to test the ultimate axial compression load allowed by the sample ocean cable.

[0068] An embodiment of the present invention further provides a testing method, which is implemented using the above-mentioned axial compression testing device and includes the following steps:

[0069] S1: Prepare a sample marine cable for testing and install the sample marine cable into the axial compression test device;

[0070] S2: Apply an axial compressive load F1 to the sample marine cable through the force brake 7;

[0071] S3: applying a cyclic bending load to the sample ocean cable by rotating the brake 8, so that the sample ocean cable bends with a bending radius of R;

[0072] S4: Obtain test results of the sample ocean cable, and evaluate the test results including whether the sample ocean cable is damaged.

[0073] Among them, in step S4, the test results of the sample marine cable are evaluated, and the evaluation content includes but is not limited to visually inspecting whether the appearance of the sample marine cable has overall twisting or wear, dissecting the sample marine cable to observe whether the armored steel wire has local buckling or "birdcaging" phenomena, and detecting whether the sample marine cable has electrical failure by measuring the conductor resistance and insulation resistance.

[0074] As an example, the umbilical cable 6 is taken as an example for further description.

[0075] The umbilical cable 6, a combination of electrical cables, optical cables, and hydraulic or chemical tubing, is a critical piece of equipment in fields such as subsea oil and gas exploration and production, and marine engineering. It primarily provides electricity, gas and hydraulic power, chemical injection, and data transmission for deep-sea production systems. During installation, the umbilical cable 6 is susceptible to compressive loads at the mud contact point due to the movement of the installation vessel and the influence of waves and currents. Related research indicates that this is closely related to the cyclic bending loads to which the umbilical cable 6 is subjected. Excessive compressive loads can easily cause local buckling of the umbilical cable 6, or even overall torsional failure.

[0076] The length of existing sample marine cables is mostly 0.5 to 1 meter, while the length of the umbilical cable 6 selected in this embodiment is 4 meters or longer. The longer length can make the umbilical cable 6 easier to bend, which is convenient for testing, and the test results obtained are more realistic.

[0077] refer to Figure 5 and Figure 6 The umbilical cable 6 includes two steel tubes 62, which are arranged along the axial direction of the umbilical cable 6. One end of the umbilical cable 6 used in the test is covered by an end plate 60, and two holes are provided in the end plate 60. A steel wire rope 61 is inserted from the other end of the umbilical cable 6 along one of the steel tubes 62. The steel wire rope 61 extends out of the end plate 60 and passes through the other steel tube 62. The steel wire rope 61 finally extends from the end of the umbilical cable 6 away from the end plate 60. When the steel wire rope 61 is pulled, an axial compressive load F1 is applied to the umbilical cable 6. Of course, if there is no steel tube 62 in the sample marine cable used in other tests, a hole 63 can be set in the filling body of the sample marine cable. The steel wire rope 61 is connected to the force brake 7 using the preset hole 63 to achieve the effect of applying an axial compressive load.

[0078] After the umbilical cable 6 is prepared, it is installed on the test device. The side of the umbilical cable 6 away from the end plate 60 is fixedly clamped on the second end limit clamp 2 and tightened. Then, the wire rope 61 is pulled by the force brake 7 to apply an axial compressive load F1 to the umbilical cable 6.

[0079] Alternatively, the maximum axial compressive load of the umbilical cable 6 can be estimated using previous test experience. Simulation software can then be used to simulate the minimum bending radius of the umbilical cable 6 during installation or operation, providing a basis for actual testing. A safety margin is included in the actual test, so the test axial compressive load is the estimated value multiplied by a safety factor, such as 2.5.

[0080] For example, during actual testing, a load of 2.5 times the estimated axial compression load is applied to the steel wire rope 61, and the rotary brakes 8 at both ends of the umbilical cable 6 are driven to make the curvature of the umbilical cable 6 along the cable length close to 1 / R. The maximum curvature of the umbilical cable 6 along the cable length is measured using multiple inclination sensors arranged on the outside of the umbilical cable 6.

[0081] Evaluate the test results of the umbilical cable 6 and observe whether the appearance of the umbilical cable 6 is damaged; dissect the umbilical cable 6 to check whether local buckling occurs inside; measure the conductor resistance and insulation resistance inside the umbilical cable 6 and compare them with the resistance values ​​before the test.

[0082] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An axial compression test device for a marine cable, characterized in that: include: A first end limiting clamp (1), the first end limiting clamp (1) being used for being arranged at a first end of a marine cable; A second end limiting clamp (2), the second end limiting clamp (2) being used for being arranged at the second end of the marine cable; An intermediate limiting clamp (3), the intermediate limiting clamp (3) being arranged between the first end limiting clamp (1) and the second end limiting clamp (2), the intermediate limiting clamp (3) being used to clamp the middle portion of the marine cable and being able to slide freely as the marine cable bends; A force brake (7), the force brake (7) being arranged at the end of the ocean cable, the force brake (7) being used to apply an axial compressive load to the ocean cable; A rotation brake (8), the rotation brake (8) being used to apply a cyclic bending load to the marine cable; When the marine cable is an umbilical cable (6), the umbilical cable (6) includes two steel pipes (62), which are arranged along the axial direction of the umbilical cable (6). One end of the umbilical cable (6) used for the test is covered by an end plate (60), and two holes are opened on the end plate (60). A steel wire rope (61) is inserted from the other end of the umbilical cable (6) along one of the steel pipes (62). The steel wire rope (61) extends out of the end plate (60) and passes through the other steel pipe (62). The steel wire rope (61) finally extends from the end of the umbilical cable (6) away from the end plate (60). When the force brake (7) is used to pull the steel wire rope (61), an axial compression load F1 is applied to the umbilical cable (6); When the sample ocean cable used in the test does not have a steel pipe (62), a hole (63) is set in the filling body of the sample ocean cable, and the steel wire rope (61) is connected to the force brake (7) using the preset hole (63) to achieve the effect of applying an axial compression load.

2. The axial compression testing device for marine cables according to claim 1, characterized in that: There are multiple intermediate limiting clamps (3), and the multiple intermediate limiting clamps (3) are arranged at intervals from each other.

3. The axial compression testing device for marine cables according to claim 1, characterized in that: The axial compression test device further comprises a test frame (4), the first end limit clamp (1) and the second end limit clamp (2) are fixedly arranged on the test frame (4), and the middle limit clamp (3) is movably arranged on the test frame (4).

4. The axial compression test device for marine cables according to claim 3, characterized in that: The test stand (4) is provided with a slide plate (5), the slide plate (5) is provided with a slide groove (50), the intermediate limiting clamp (3) is connected to the slide plate (5), and the intermediate limiting clamp (3) can slide along the slide groove (50).

5. The axial compression testing device for marine cables according to claim 3, characterized in that: The test frame (4) comprises a plurality of vertical support beams (40), a plurality of transverse support beams (41) and a plurality of connecting beams (42), wherein the two ends of each transverse support beam (41) are respectively connected to two adjacent vertical support beams (40), and the two ends of each connecting beam (42) are respectively connected to two adjacent transverse support beams (41).

6. The axial compression testing device for marine cables according to claim 1, characterized in that: There are two rotating brakes (8), which are respectively located at two ends of the ocean cable, one of which is connected to the first end limit clamp (1), and the other is connected to the second end limit clamp (2).

7. The axial compression testing device for marine cables according to claim 1, characterized in that: The axial compression testing device further includes a plurality of inclination sensors, which are respectively arranged at different positions of the outer side wall of the marine cable.

8. The axial compression testing device for marine cables according to any one of claims 1 to 7, characterized in that: The intermediate limiting clamp (3) comprises at least one pair of horizontal rollers (30) and at least one pair of vertical rollers (31), wherein the pair of horizontal rollers (30) are spaced apart and arranged in parallel, and the pair of vertical rollers (31) are spaced apart and arranged in parallel.

9. A testing method, characterized in that: The axial compression testing device according to any one of claims 1 to 8 is used, comprising: Preparing a sample marine cable for testing, and installing the sample marine cable into the axial compression testing device; Applying an axial compressive load F1 to the sample marine cable through the force brake (7); Applying a cyclic bending load to the sample ocean cable through the rotating brake (8) to bend the sample ocean cable with a bending radius of R; Obtain test results of the sample ocean cable, and evaluate the test results to determine whether the sample ocean cable is damaged.

10. The testing method according to claim 9, characterized in that: The steps of evaluating the test results, including whether the sample submarine cable is damaged, include: Visually inspect the appearance of the sample ocean cable to see if it is damaged, dissect the sample ocean cable and check if local buckling occurs inside the ocean cable.

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