A mooring line break simulation device for a tank model test of a floating offshore structure

Abstract

The application belongs to the technical field of ship and ocean engineering pool test, and particularly discloses a floating ocean structure pool model test mooring cable breaking simulation device, which comprises an electromagnet assembly, a clamp and a programmable logic controller. The electromagnet assembly is arranged on a platform of a floating ocean structure model and comprises a push-pull electromagnet and a steel wire rope controlled in tension by the push-pull electromagnet. The clamp is connected with the end of the steel wire rope at the side and has a cavity at the head for suspending the mooring cable. The cavity is closed and opened by the tension of the steel wire rope, so as to clamp and simulate the breaking of the mooring cable. The programmable logic controller is used in combination with a single force sensor to automatically control the push-pull action of the push-pull electromagnet and realize automatic breaking. The device can realize transient breaking test and has the advantages of high breaking time control precision, small influence on the force measurement of the mooring cable, water-electric separation, convenient installation, simple operation and the like.

Description

Technical Field

[0001] This invention relates to the field of water tank testing technology for ships and marine engineering, and specifically to a device for simulating mooring cable breakage in a floating marine structure water tank model test. Background Technology

[0002] As marine resource development gradually moves into deeper waters, the application of floating marine structures is becoming increasingly widespread. Marine structures operate in a particular sea area for extended periods, enduring the constantly changing winds and waves, including extremely harsh sea conditions. Under such conditions, mooring systems may be damaged, leading to hull drift, riser breakage, forced shutdowns, potential hydrocarbon leaks, and even platform destruction. In particular, the failure of a single anchor chain typically increases the burden on other anchor chains, potentially causing cascading mooring cable breakage and a possible catastrophic collision.

[0003] To predict the dynamic response of offshore platform mooring systems in the event of failure, mooring system failure tests need to be conducted during the platform design phase. This allows for advance analysis and examination of data such as transient and steady-state responses, mooring line tension, and anchor winch performance. Testing the transient effects of mooring system failure requires the construction of a testing apparatus to continuously and accurately monitor test data during failure.

[0004] Currently, there are two types of mooring system failure testing devices: one uses a control circuit device consisting of a comparison circuit, a de-energized electromagnet, and an iron block to separate the anchor cable above water, thereby achieving the purpose of anchor cable failure; the other uses air pressure changes, that is, high-pressure gas in the high-pressure cylinder pushes away the piston connecting the mooring line and the tension sensor in the low-pressure cylinder, thereby achieving the purpose of mooring failure.

[0005] The above-mentioned fracture test apparatus has the following problems:

[0006] 1. A control circuit device consisting of a comparator circuit, a de-energized electromagnet, and an iron block is used to separate the anchor cable above water. This requires fixing a bracket above the water tank and using pulleys installed on the bottom to guide the anchor cable from the bottom to the fixed bracket above the water, where it is connected and secured to the control circuit device. This installation method is effective in a water tank, but in pool tests, the horizontal distance and water depth are large, requiring excessive redundant materials, which significantly increases the risk to system reliability.

[0007] 2. A solenoid valve controls the high-pressure gas in the high-pressure cylinder to push the piston in the low-pressure cylinder away from the mooring line. The piston is connected to the mooring line and tension sensor, achieving the mooring line breakage effect. This method of breaking the line by adjusting the air pressure has a certain time delay, and the piston in the low-pressure cylinder may shift under the significant tension of the mooring line, affecting the accuracy and reliability of the data. Furthermore, the tension sensor and mooring line sink together, and the mooring line is retrieved using the sensor signal line. These operations significantly impact the sensor's lifespan. In deep water, excessively long redundant sensor signal lines, along with their weight and volume, affect the model, hindering the design of a lightweight and reliable device. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a mooring cable breakage simulation device for floating marine structure pool model tests. This device enables transient breakage testing and features high precision in controlling the breakage timing, minimal impact on mooring cable stress measurement, water-electricity separation, convenient installation, and simple operation.

[0009] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:

[0010] A simulation device for mooring cable breakage in a floating marine structure pool model test includes:

[0011] An electromagnet assembly, set on a platform of a floating marine structure model, includes a push-pull electromagnet and a steel wire rope whose tension is controlled by pushing and pulling at the front end of the push-pull electromagnet.

[0012] The clamp has a side connected to the end of the wire rope and a head with a cavity for suspending the mooring cable. The cavity is closed and opened by the tension of the wire rope, thereby simulating the clamping and breaking of the mooring cable.

[0013] A programmable logic controller (PLC) is used to control the on / off state of the push-pull electromagnet, and to control the push-pull action of the push-pull electromagnet by disconnecting and connecting the current.

[0014] The operation of the above-mentioned device is as follows: When the push-pull electromagnet is energized, it pulls the steel wire rope inward, opening the cavity of the clamp and releasing the suspended mooring cable, thus completing the breaking motion. The energization and de-energization of the push-pull electromagnet are instantaneous. After the mooring cable is released, the steel wire rope immediately relaxes under the outward pushing and resetting action of the push-pull electromagnet, allowing the cavity of the clamp to close via a manual or automatic reset structure. The programmable logic controller can use real-time acquired tension data, a built-in timing module, or a manual button on the control interface to determine whether to energize the electromagnet to trigger the release function of the clamp and perform a simulated breaking operation of the mooring line.

[0015] Preferably, the floating marine structure pool model test mooring cable breakage simulation device further includes a single-component force sensor for measuring the tension on the mooring cable. The single-component force sensor is mounted on the cable guide hole on the side wall of the floating marine structure model and can rotate around the cable guide hole. Its bottom is the measuring end, which is connected to the clamp. Installing the single-component force sensor in this position can better simulate the state of the mooring cable. The single-component force sensor transmits the tension signal to the programmable logic controller. The programmable logic controller determines whether to energize the push-pull electromagnet based on the tension signal. If the controller determines that the mooring tension has reached the set value, it energizes the push-pull electromagnet.

[0016] Preferably, the outer periphery of the wire rope is fitted with a wire sleeve at both ends, which are respectively fixed to the electromagnet assembly and the clamp. This invention requires the automatic release of the mooring cable model with minimal impact on the mooring cable tension measurement. This necessitates a fast-responding trigger mechanism for the clamp without affecting force measurement (i.e., high axial stiffness and low bending stiffness). Therefore, a wire sleeve with fixed ends is provided on the wire rope. The wire sleeve has high axial stiffness, allowing it to act as a support point for the clamp when the wire rope is pulled inside, and the high stiffness is transmitted quickly. Simultaneously, the wire sleeve has low bending stiffness, meaning it is relatively flexible and does not affect normal testing. The wire rope inside also exhibits low bending stiffness and high axial stiffness. The wire rope can slide along a fixed trajectory within the sleeve. During operation, the wire sleeve and wire rope are longitudinally tightened without affecting the movement of the clamp and the mooring cable.

[0017] Preferably, the push-pull electromagnet includes:

[0018] The electrostatic core is set horizontally.

[0019] A movable sliding rod is horizontally positioned relative to the electrostatic core, with its front end connected to the steel wire rope.

[0020] In the de-energized state, there is a gap between the electrostatic core and the moving slide rod, and the moving slide rod is in an outward pushing state, thus loosening the wire rope; after the power is turned on, the electrostatic core becomes magnetic, magnetically connecting to the moving slide rod, causing it to change to an inward pulling state, thus tightening the wire rope.

[0021] Preferably, in the electromagnet assembly, a baffle is further provided in front of the push-pull electromagnet, and the first end of the wire sleeve is fixed to the baffle.

[0022] Preferably, the clamp includes:

[0023] The clamping arms have two oppositely arranged arms, with their head ends fitting together to form the cavity described above;

[0024] A clamping spring is embedded therein, connecting the two clamping arms;

[0025] A fulcrum is provided between the two clamping arms and behind the clamping spring, and the clamping arms can rotate around it;

[0026] A roller is mounted at the end of a clamping arm;

[0027] The hook has its inner end rotatably connected to the end of another clamping arm, and its outer end connected to the end of the wire rope. The hook body has a limiting groove for accommodating the roller.

[0028] When the wire rope is slack, the roller is in the limiting groove, the clamp spring is compressed, the cavity is closed, and the mooring cable is suspended; when the wire rope is tightened, the hook rotates, the roller disengages from the limiting groove, the clamp spring returns to its original position, the cavity opens, and the mooring cable is released.

[0029] Preferably, the clamp further includes a frame for clamping the two clamping arms. The front of the frame has an opening for accommodating the clamping arms, and the outer end of the hook extends from the side of the frame. The two clamping arms are connected to the frame by two limiting posts passing through the front of the frame and the frame itself. The two limiting posts are symmetrically distributed on both sides of the fulcrum post. The limiting posts connect the clamping arms to the frame without hindering the rotational opening movement of the clamping arms around the fulcrum post.

[0030] Preferably, the tail of the frame is provided with a cross brace behind the position where the outer end of the hook extends, the end of the wire sleeve is fixed to the cross brace to provide a support point for the clamp, and the end of the wire rope passes through the cross brace and the hook in sequence by the wire sleeve and is limited by a wire knot.

[0031] Preferably, the single-component force sensor transmits the tension signal to the programmable logic controller (PLC) via a signal transmission line. The PLC is installed in a control room, which is mounted on a trolley spanning the water tank. During mooring tests, the trolley is moved to the vicinity of the floating marine structure model for easy instrument connection.

[0032] Preferably, the frame is further provided with several weight-reducing holes (at least one). In order to automatically release the mooring cable model, on the one hand, the action mechanism of the triggering clamp needs to be fast enough and not affect the force measurement; on the other hand, the clamp for releasing the mooring cable needs to be light enough and able to withstand a large force. By adding weight-reducing holes based on the clamp structure described above in this invention, these requirements can be fully met.

[0033] The present invention has the following beneficial effects:

[0034] 1. The device can achieve water and electricity separation. The electromagnet that needs to be energized is placed on a model platform that does not enter the water. The clamp that realizes the breaking motion can be installed underwater or above the water as needed. The electromagnet and the clamp directly transmit power with steel wire rope. The water-entry parts do not need to be waterproofed. It is easier to meet the characteristics of small size and light weight of the parts. It is easy to install, safe to use, and has almost no impact on tension measurement. It can be used in different water depths.

[0035] 2. When the device is reused, simply place the mooring cable to be broken into the cavity of the clamp, move the hook down to lock the roller, close the cavity of the clamp, and the mooring cable is suspended. The operation is simple.

[0036] 3. The programmable logic controller (PLC) determines the breaking motion based on the set mooring tension, specific test time, and manual triggering at any time. Through the instantaneous switching on and off of the electromagnet and the force transmission of the wire rope, the automatic breaking process can be completed in a short time, ensuring high precision in controlling the breaking timing of the device.

[0037] 4. Utilizing the multi-channel and easily expandable features of programmable logic controllers, multiple devices can be controlled simultaneously to conduct experimental research on single cable breakage, simultaneous breakage of multiple cables, and spliced ​​breakage of multiple cables. The input signal can be extended from mooring tension to analog signals such as platform motion and wave height, making it widely applicable and promising for future applications. Attached Figure Description

[0038] Figure 1 : Schematic diagram of the location of the fracture simulation device described in Example 1 in the floating marine structure model.

[0039] Figure 2 : Figure 1 Enlarged diagram of point A in the middle.

[0040] Figure 3 : A three-dimensional structural diagram of the electromagnet assembly described in Example 1.

[0041] Figure 4 : A three-dimensional structural diagram of the fixture described in Example 1.

[0042] Figure 5 : Schematic diagram of the internal structure of the fixture described in Example 1.

[0043] Figure 6 : Schematic diagram of the motion process of the fixture described in Example 1.

[0044] In the diagram: 1-Floating marine structure model, 2-Mooring cable, 3-Electromagnet assembly, 4-Clamp, 5-Single force sensor; 11-Cable guide hole, 31-Push-pull electromagnet, 32-Wire rope, 33-Mounting base, 41-Frame, 42-Clamping arm, 43-Cavity, 44-Clamping spring, 45-Pivot column, 46-Roller, 47-Hook, 48-Shaft, 51-Signal transmission line; 311-Shell, 312-Electrostatic core, 313-Moving slide bar, 314-Coil, 315-Magnetic spring, 321-Wire sleeve, 331-Baffle, 332-Base plate, 411-First limiting hole, 412-Cross brace, 413-Connecting hole, 414-Weight reduction hole, 421-Second limiting hole, 471-Limiting groove. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1

[0047] A floating marine structure pool model test mooring cable breakage simulation device, such as Figure 1-2 As shown, a breakage simulation device is installed between a floating marine structure model 1 and a mooring line model. The mooring line model includes several mooring cables 2. The device includes an electromagnet assembly 3, a clamp 4, a single-component force sensor 5, and a programmable logic controller (PLC). The electromagnet assembly 3 is installed on the platform of the floating marine structure model 1. The single-component force sensor 5 is used to measure the tension of the mooring cables 2. It is attached to the cable guide hole 11 on the side wall of the floating marine structure model 1 and can rotate around the cable guide hole 11. Its bottom is the measuring end, which is connected to the clamp 4. The PLC is installed in the control room, which is mounted on a mobile trolley spanning the pool.

[0048] The electromagnet assembly 3, as described above Figure 3 As shown, it includes a push-pull electromagnet 31, a steel wire rope 32 disposed at the front end of the push-pull electromagnet 31 and whose tension is controlled by its push-pull action, and a mounting base 33 for mounting the push-pull electromagnet 31.

[0049] The push-pull electromagnet 31 includes a housing 311, an electrostatic core 312, a movable slide rod 313, a coil 314, and a magnetic spring 315. The housing 311 is hollow inside; the electrostatic core 312 and the movable slide rod 313 are arranged horizontally and opposite to each other. The electrostatic core 312 extends into the housing 311 through its rear end face, and the movable slide rod 313 extends into the housing 311 through its front end face, with its front end bound to the steel wire rope 32; the coil 314 is located inside the housing 311 and surrounds the electrostatic core 312 and the movable slide rod 313; the magnetic spring 315 is installed on the front end face of the housing 311, is wound around the movable slide rod 313, and its front end is fixed to the movable slide rod 313.

[0050] The mounting base 33 includes a baffle 331 and a base plate 332. The bottom of the outer shell 311 of the push-pull electromagnet 31 is fixedly installed on the base plate 332. The baffle 331 is located in front of the push-pull electromagnet 31 and is erected on the base plate 332. A wire sleeve 321 is sleeved on the outer periphery of the wire rope 32. The first end of the wire sleeve 321 is fixed to the baffle 331, and the second end is fixed to the clamp 4.

[0051] The working principle of the electromagnet assembly 3 is as follows: In the power-off state, there is a gap between the electrostatic core 312 and the movable slide rod 313, the magnetic spring 315 is in a relaxed state and relaxes the wire rope 32, and the movable slide rod 313 is in an outward push state; after power is applied, the electrostatic core 312 becomes magnetic and magnetically connects to the movable slide rod 313, causing it to change to an inward pull (retract) state and tighten the wire rope 32.

[0052] The clamp 4 is as follows Figure 4-6 As shown, it includes a frame 41, a clamping arm 42, a cavity 43, a clamping spring 44, a fulcrum column 45, a roller 46, a pull hook 47, and a rotating shaft 48.

[0053] The clamping arms 42 are arranged opposite each other, with their heads fitting together to form a cavity 43. The cavity 43 is used to clamp and release (i.e. simulate breaking) the mooring cable 2. The clamping spring 44 is embedded and connected to the two clamping arms 42 at both ends. The fulcrum post 45 is located between the two clamping arms 42 and behind the clamping spring 44, and the clamping arms 42 can rotate around it. The tails of the two clamping arms 42 are both concave downwards. A roller 46 is installed in the concave area of ​​one clamping arm 42, and a hook 47 is rotatably connected to the concave area of ​​the other clamping arm 42. The roller 46 and the hook 47 are both installed on the clamping arm 42 through a rotating shaft 48. The inner end of the hook 47 is connected to the clamping arm 42, and the outer end is connected to the end of the wire rope 32. The hook body has a limiting groove 471 for accommodating the roller 46.

[0054] The frame 41 clamps two clamping arms 42, each with an opening at its head to accommodate the clamping arms 42. The outer end of the hook 47 extends from the side of the frame 41. Two first limiting holes 411, symmetrically distributed about the fulcrum post 45, are respectively opened at the same position on the front and back of the frame 41. A second limiting hole 421 is opened at the corresponding position of each clamping arm 42. The clamping arm 42 is connected to the frame 41 by limiting posts passing through the first and second limiting holes 411 and 421. A cross brace 412 is provided at the rear of the frame 41 behind the position where the outer end of the hook 47 extends. The end of the wire sleeve 321 is fixed to the cross brace 412. The end of the wire rope 32 passes through the wire sleeve 321 sequentially through the cross brace 412 and the hook 47, and is limited by a wire knot. The frame 41 has a connecting hole 413 extending from the front to the back, through which a rope is passed to bind and fix the clamp 4 to the bottom of the single force sensor 5. The frame 41 also has four weight-reducing holes 414.

[0055] The working principle of the clamp 4 is as follows: When the wire rope 32 is in a slack state, the roller 46 is located in the limiting groove 471, the clamp spring 44 is in a compressed state, the cavity 43 is closed, and the mooring cable 2 is suspended; when the wire rope 32 is tightened, the hook 47 rotates, the roller 46 disengages from the limiting groove 471, the clamp spring 44 resets, the cavity 43 opens, and the mooring cable 2 is released.

[0056] The single-component force sensor 5 transmits the tension signal to the programmable logic controller (PLC) via signal transmission line 51. The PLC receives the tension signal from the single-component force sensor 5 and determines whether to energize the push-pull electromagnet 31 based on the tension signal. It controls the pushing-pull action of the electromagnet 31 by opening and closing the current. The lengths of both the power cord of the push-pull electromagnet 31 and the signal transmission line 51 must exceed the distance from the equipment to the control room to minimize the impact on the model test data results.

[0057] The working principle of the entire device is as follows: the electromagnet assembly 3 controls the tension of the wire rope 32 by switching the power on and off; the cavity 43 of the clamp 4 is manually closed and automatically opened by the tension of the wire rope 32, thereby realizing the clamping and breaking simulation of the mooring cable 2; the single force sensor 5 measures the tension of the mooring cable 2 and transmits the tension signal to the programmable logic controller; the controller determines whether to energize the electromagnet assembly 3 based on the breaking condition.

[0058] More specifically, the single-force sensor 5 inputs the real-time tension data of the mooring cable 2 into the programmable logic controller. If the controller determines that the mooring tension has reached the set value, it controls the push-pull electromagnet 31 to be energized, the sliding rod 313 retracts to tighten the wire rope 32, and drives the clamping arm 42 in the clamp 4 to open, releasing the mooring cable 2 and completing the simulated breaking motion. The energization and de-energization of the push-pull electromagnet are instantaneous. After the mooring cable 2 is released, the wire rope 32 immediately relaxes due to the outward pushing and resetting action of the push-pull electromagnet 31 after the power is cut off. At this time, the mooring cable 2 is placed back into the cavity 43 of the clamp 4, and the hook 47 is manually moved down to lock the roller 46, causing the clamping arm 42 in the clamp 4 to close, closing the cavity 43, and the mooring cable 2 is suspended again, ready for the next breaking motion.

[0059] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. Any changes made by those skilled in the art after reading the specification of the present invention, as long as they are within the scope of the claims of the present invention, will be protected by patent law.

Claims

1. A device for simulating mooring cable breakage in a floating marine structure pool model test, characterized in that: include: An electromagnet assembly (3) is set on the platform of a floating marine structure model (1), including a push-pull electromagnet (31) and a wire rope (32) whose tension is controlled by pushing and pulling at the front end of the push-pull electromagnet (31). A clamp (4), the side of which is connected to the end of the wire rope (32), comprises: The clamp arm (42) has two oppositely arranged arms, the head ends of which fit together to form a cavity (43) for suspending the mooring cable (2). A clamping spring (44) is embedded in the clamping spring and connects the two clamping arms (42). A fulcrum (45) is provided between the two clamping arms (42) and behind the clamping spring (44), around which the clamping arms (42) can rotate; A roller (46) is mounted at the end of a clamping arm (42); The hook (47) has its inner end rotatably connected to the end of another clamping arm (42) and its outer end connected to the end of the wire rope (32). The hook body has a limiting groove (471) for the roller (46) to be accommodated. The cavity (43) is closed and opened by the tension of the wire rope (32), thereby simulating the clamping and breaking of the mooring cable (2): when the wire rope (32) is in a slack state, the roller (46) is located in the limiting groove (471), the clamping spring (44) is in a compressed state, and the cavity (43) is closed; when the wire rope (32) is tightened, the hook (47) rotates, the roller (46) disengages from the limiting groove (471), the clamping spring (44) resets, and the cavity (43) opens; A programmable logic controller is used to control the power supply of the push-pull electromagnet (31) and to control the push-pull action of the push-pull electromagnet (31) by disconnecting and connecting the current.

2. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 1, characterized in that: It also includes a single-component force sensor (5) for measuring the tension on the mooring cable (2). The single-component force sensor (5) is mounted on the cable guide hole (11) on the side wall of the floating marine structure model (1) and can rotate around the cable guide hole (11). Its bottom is the measuring end, which is connected to the clamp (4). The single-component force sensor (5) transmits the tension signal to the programmable logic controller. The programmable logic controller determines whether to energize the push-pull electromagnet (31) based on the tension signal.

3. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 2, characterized in that: The outer periphery of the wire rope (32) is fitted with a wire sleeve (321) whose two ends are respectively fixed to the electromagnet assembly (3) and the clamp (4).

4. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 3, characterized in that: The push-pull electromagnet (31) includes: Static core (312), horizontal setting; The movable slide bar (313) is horizontal and opposite to the electrostatic core (312), and its front end is connected to the steel wire rope (32). In the de-energized state, there is a gap between the electrostatic core (312) and the movable slide rod (313), and the movable slide rod (313) is in the outward pushing state; after the power is turned on, the electrostatic core (312) becomes magnetic and magnetically connects to the movable slide rod (313), causing it to change to the inward pulling state.

5. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 4, characterized in that: In the electromagnet assembly (3), a baffle (331) is also erected in front of the push-pull electromagnet (31), and the first end of the wire sleeve (321) is fixed to the baffle (331).

6. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 3, characterized in that: The clamp (4) further includes a frame (41) for clamping the two clamping arms (42). The head of the frame (41) has an opening for accommodating the clamping arms (42). The outer end of the hook (47) extends from the side of the frame (41). The two clamping arms (42) are connected to the frame (41) by two limiting posts passing through the head of the frame (41) and themselves. The two limiting posts are symmetrically distributed on both sides of the fulcrum post (45).

7. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 6, characterized in that: The tail of the frame (41) is provided with a cross brace (412) behind the position where the outer end of the hook (47) extends, and the end of the wire sleeve (321) is fixed to the cross brace (412). The end of the wire rope (32) is passed through the cross brace (412) and the hook (47) in sequence by the wire sleeve (321) and is limited by the wire knot.

8. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 6, characterized in that: The frame (41) also has several weight-reducing holes (414) on its frame.

9. The mooring cable breakage simulation device for floating marine structure pool model test according to claim 2, characterized in that: The single-component force sensor (5) transmits the tension signal to the programmable logic controller (PLC) via a signal transmission line (51). The PLC is installed in the control room, which is mounted on a crane that spans the pool.

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