A test device and method for measuring the modal state of a segmented ship model

Abstract

A test device and method for modal measurement of a segmented ship model. The rib frame of the segmented ship model is made of NdFeB permanent magnets and is magnetized. A first bow magnet is installed at the bow longitudinal section of the segmented ship model, and a first stern magnet is installed at the stern of the segmented ship model. The internal space of a suspension support frame matches the exterior of the ship model. A plurality of hull magnet assemblies are arranged on the frame, each hull magnet assembly corresponds to the position of the rib frame one by one. The frame also has a second bow magnet assembly and a second stern magnet assembly corresponding to the first stern magnet and the first bow magnet respectively. The magnetic field generated by the magnet on the suspension bracket suspends the segmented ship model above the inside of the suspension support, thereby avoiding searching for nodes, repeated unloading, lifting, and adjusting the lifting posture of the ship model during the test, and measuring the bending parameters of the two-node, three-node, four-node and other bending parameters of the segmented ship model trunk structure at one time, thereby improving work efficiency and avoiding dangerous factors and uncertain factors.

Description

Technical Field

[0001] The invention relates to the technical field of ship and ocean engineering model test and testing, in particular to a test device and method for modal measurement of a segmented ship model. Background Art

[0002] The modal test of the hull structure in the air is an important task that must be carried out before the tank model test of large ships and marine structures. It is the basis for the section load test and hydroelastic analysis. Since the mass distribution and stiffness distribution of the structure of large ships will change during the scaled production process, the vibration characteristics are the determining factors for the success or failure of its processing, and are also important parameters for the tank model test. At the same time, compared with the test of modal parameters in water, the dry structure modal test is the immediate predecessor of the wet mode test in water. If the dry structure modal test finds that the ship structure parameters are inconsistent with those before the conversion or the deviation is large, the cause should be found immediately, otherwise the results obtained by the tank test cannot be verified for accuracy.

[0003] Large ships are prone to wave-induced vibration due to their large size and low stiffness. The vibration test of their dry structures often needs to consider the first several modes, including vertical bending, horizontal bending and torsion, and the position of the suspension point is a key condition that affects the measurement results of each mode. In this case, the conventional practice is to analyze the first several vibration modes based on numerical modeling, obtain the vibration nodes of each order, and roughly measure the node positions before lifting the ship model. However, due to the error between the numerical calculation and the actual model, in the process of finding a node, it is necessary to try to change the node position many times to measure the relevant parameters. Each time the lifting position is changed, the tightness of the rope changes due to the movement of the lifting point, which will cause the center of gravity of the ship to change during lifting, which not only affects the normal modal test results, but also has the risk of overturning during lifting. In addition, in the process of changing from two nodes to three nodes and four nodes, it is still necessary to try to change the node position many times, which is time-consuming and laborious.

[0004] At the same time, after testing the vertical bending, the horizontal bending and torsion are tested. The lifting state of the ship model needs to be re-evaluated. Especially when measuring the horizontal bending of the ship model, its lifting posture requires the ship model to be flipped 90°. The fixation of the instruments and weights in the ship model is a very critical factor. For the measurement results, the best way is to fix it with screws, but it is not easy to operate. Another way is to bond it with high-strength glue. Once the weight is not fixed firmly, it is easy to fall or vibrate, which will affect the test results, so all test conditions are invalid. However, there are many test conditions for the ship model in the pool, and it is necessary to configure a variety of draft and ballast conditions, which means that there are different arrangements for the weights. In the dry modal test of the suspended ship model after flipping, the increase and decrease of the weights will be a very huge workload and have great uncertainty.

[0005] In addition, there are extra positions on the ship model structure or the measuring beam where sensors and connecting lines are arranged, which not only affects the position for lifting and threading, but also makes it inconvenient to change the lifting point. Summary of the invention

[0006] In view of the shortcomings in the above-mentioned existing production technology, the applicant provides a test device and method for modal measurement of segmented ship models, thereby avoiding the need to find nodes, repeatedly unload, lift, and adjust the lifting posture of the ship model during the modal test of the segmented ship model trunk structure, and measuring the bending parameters of the two-node, three-node, four-node, etc. of the segmented ship model trunk structure at one time, thereby improving work efficiency and avoiding dangerous and uncertain factors.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A test device for measuring the modal state of a segmented ship model, comprising a segmented ship model and a suspension support matched with the segmented ship model;

[0009] The structure of the segmented ship model is as follows: it includes segmented hulls arranged side by side in sequence, a plurality of rib frames are arranged at intervals along the length direction of the ship on the inner wall of each segmented hull, the rib frames are U-shaped, two ends of a single rib frame are connected by a transverse frame, a fixed base is arranged on the upper part of each transverse frame, and a plurality of fixed bases are simultaneously connected to a measuring beam arranged along the length direction of the ship, the rib frames are made of NdFeB permanent magnets and are magnetized,

[0010] A first bow magnet is installed at the bow longitudinal section of the segmented ship model, and a first stern magnet is installed at the stern longitudinal section of the segmented ship model, wherein the first bow magnet and the first stern magnet are both made of neodymium iron boron permanent magnets and are magnetized;

[0011] The structure of the suspension support is as follows: it includes a frame, the internal space of the frame matches the exterior of the ship model, a plurality of hull magnet assemblies are arranged on the frame at intervals along the length of the ship, and each hull magnet assembly corresponds to a rib frame position one by one.

[0012] A second bow magnet assembly is arranged on a frame corresponding to the first bow magnet, and a second stern magnet assembly is arranged on a frame corresponding to the first stern magnet;

[0013] When the segmented ship model is placed above the interior of the suspension support, the opposite magnetic poles of the hull magnet assembly and the rib frame are identical and facing each other, the opposite magnetic poles of the first bow magnet and the second bow magnet assembly are identical and facing each other, and the opposite magnetic poles of the first stern magnet and the second stern magnet assembly are identical and facing each other, and the magnetic fields generated by the hull magnet assembly, the second bow magnet assembly and the second stern magnet assembly repel the magnetic fields generated by the rib frame, the first bow magnet and the first stern magnet respectively, so that the segmented ship model is suspended above the interior of the suspension support.

[0014] Its further technical solution is:

[0015] A single hull magnet assembly is segmented, including a left section of the hull magnet and a right section of the hull magnet respectively located on both sides along the length of the ship, the left section of the hull magnet and the right section of the hull magnet respectively corresponding to the two side edges of the rib frame, and also including a middle section of the hull magnet located at the bottom of the suspension support, the middle section of the hull magnet corresponds to the bottom edge of the rib frame.

[0016] The second bow magnet assembly, the second stern magnet assembly, the left section of the hull magnet, the right section of the hull magnet and the middle section of the hull magnet have the same structure;

[0017] The structure of the middle section of the hull magnet is as follows: an open slot of a tubular structure, one side of the open slot is connected to the frame, one end of the open slot is closed by a fixed limit plate, an internal magnet is installed inside the open slot, and the internal magnet is a neodymium iron boron permanent magnet;

[0018] A movable limiting plate is symmetrically arranged at the opening of the other end of the opening slot, and the movable limiting plate is connected to the inner wall of the opening slot through an elastic element. Under the action of the elastic element, the two movable limiting plates close the opening of the opening slot so that the internal magnet is limited inside the opening slot;

[0019] The fixed limiting plate of the second bow magnet assembly and the fixed limiting plate of the second stern magnet assembly are both located at the lower part of the opening slot.

[0020] The side wall of the opening groove is provided with an observation through hole along the length direction of the opening groove.

[0021] The internal magnet is a block structure with multiple end-to-end connections.

[0022] The frame is a shell-like structure whose internal space matches the exterior of the ship model, and the second bow magnet assembly, the second stern magnet assembly and the hull magnet assembly are installed on the outer surface of the frame.

[0023] The frame is a female mold shell for making a ship model, and the female mold shell is copied from a male mold made by the molding line of the target ship model.

[0024] The frame is a frame structure, including a plurality of first frame structures corresponding to the rib frame, a second frame structure corresponding to the first bow magnet, and a third frame structure corresponding to the first stern magnet.

[0025] The first tire frame structure, the second tire frame structure, and the third tire frame structure are connected by connecting members to form a frame structure;

[0026] A hull magnet assembly is installed on the outer side of the first tire frame structure, a second bow magnet assembly is installed on the outer side of the first tire frame structure, and a second stern magnet assembly is installed on the outer side of the third tire frame structure.

[0027] A method for measuring the modal state of a segmented ship model comprises the following steps:

[0028] Preparation before the test:

[0029] A segmented ship model and a suspension support matching the segmented ship model are manufactured, wherein the suspension support is provided with a second bow magnet assembly, a second stern magnet assembly and a hull magnet assembly for suspending the segmented ship model above the interior thereof.

[0030] The rib frame of the segmented ship model is made of NdFeB permanent magnets and is magnetized. The rib frame corresponds to the hull magnet assembly. The first bow magnet and the first stern magnet are respectively installed at the bow longitudinal section and the stern longitudinal section of the segmented ship model. The first bow magnet and the first stern magnet are both made of NdFeB permanent magnets and are magnetized. The first bow magnet and the first stern magnet correspond to the second bow magnet assembly and the second stern magnet assembly respectively.

[0031] Place the segmented ship model:

[0032] Placing the segmented ship model inside the suspension support when the hull magnet assembly, the second bow magnet assembly and the second stern magnet assembly do not generate a magnetic field at the suspension support;

[0033] Suspended segmented ship model:

[0034] The hull magnet assembly, the second bow magnet assembly and the second stern magnet assembly are all combined structures in which an internal magnet is installed inside an open slot of a tubular structure. The material of the internal magnet is a neodymium iron boron permanent magnet.

[0035] After the segmented ship model is placed, the internal magnet is inserted into the open slot to suspend the segmented ship model in the suspension support, and each part of the segmented ship model is tested to confirm that it is detached from the suspension support;

[0036] Dry modal testing:

[0037] After the segmented ship model is suspended,

[0038] Use a hammer to hit the measuring beam vertically at the bow or stern of the segmented ship model, collect signals and test the vertical bending modal parameters.

[0039] Use a hammer to hit the measuring beam horizontally at the bow or stern of the segmented ship model, collect signals and test the horizontal bending modal parameters.

[0040] Use a hammer to vertically strike the outermost side of the ship at the bow or stern of the segmented ship model, and use a measuring beam to collect signals to test the torsional modal parameters;

[0041] De-suspending the segmented ship model:

[0042] Take out the magnet inside the opening slot,

[0043] The magnetism of the corresponding positions of the suspension support hull magnet assembly, the second bow magnet assembly and the second stern magnet assembly is removed, so that the segmented ship model steadily descends into the suspension support and is no longer suspended, completing the measurement work.

[0044] Its further technical solution is:

[0045] A single hull magnet assembly is segmented, including a left hull magnet section and a right hull magnet section respectively located on both sides along the length of the ship, the left hull magnet section and the right hull magnet section respectively corresponding to the two sides of the rib frame, and also including a middle hull magnet section located at the bottom of the suspension support, the middle hull magnet section corresponding to the bottom of the rib frame;

[0046] In the step of suspending the segmented ship model: the order of inserting the internal magnets is to first insert the internal magnets at the second bow magnet assembly and the second stern magnet assembly, then insert the internal magnets at the left section of the hull magnet and the right section of the hull magnet, and finally insert the internal magnet at the middle section of the hull magnet;

[0047] In the step of de-suspension of the segmented ship model: the order of removing the internal magnets is to first remove the internal magnets at the middle section of the hull magnet, then remove the internal magnets at the left section and the right section of the hull magnet, and finally remove the internal magnets at the second bow magnet assembly and the second stern magnet assembly.

[0048] The beneficial effects of the present invention are as follows:

[0049] The present invention has a compact and reasonable structure and is easy to operate. By arranging a suspension support under the segmented ship model and arranging magnets with opposite polarities at the bow and stern of the segmented ship model and at the rib positions, the suspension support generates a uniform reverse thrust on the outside of the segmented ship model. While overcoming the gravity of the segmented ship model, the segmented ship model is restricted on all sides so that the segmented ship model does not undergo horizontal displacement. The segmented ship model is suspended above the interior of the suspension support. Therefore, when performing a modal test on the dry structure of the ship model, it is avoided that the segmented ship model is in a state of contact with external components by using a suspension method, that the bending nodes are searched for, and that multiple repeated unloading and lifting are avoided, and that the lifting posture of the ship model is adjusted. The interference-free suspension of the segmented ship model is achieved at one time, and the bending parameters of the two-node, three-node, four-node and the like of the dry structure of the segmented ship model can be measured at one time. The horizontal bending and torsion modal parameters can be tested without adjusting the state, and the modal characteristics can be quickly and accurately obtained. While improving the work efficiency, the dangerous factors and uncertain factors in multiple liftings are avoided.

[0050] At the same time, the present invention also has the following advantages:

[0051] (1) The hull magnet assembly adopts a segmented type, which saves materials and facilitates the design and manufacture of the magnet structure while satisfying the repulsive force on the rib frame.

[0052] (2) The internal magnet is a plurality of NdFeB permanent magnets with block structures connected end to end. The internal magnet with this structure is easy to manufacture. The plurality of block structures are spliced ​​in an open slot with a certain curvature to form a magnet with a certain curvature requirement, thereby reducing the manufacturing difficulty and cost.

[0053] (3) The outer shell of the negative mold is used as a frame, and an opening groove is added to the outside of the negative mold shell. The perfect fit between the negative mold shell and the segmented ship model is utilized, which is also convenient for the design and production of the external opening groove. At the same time, the frame is more effective in carrying the segmented ship model, and the outer shell of the negative mold can be reused, thereby achieving the purpose of saving costs, improving quality and increasing efficiency.

[0054] (4) In the method of modal measurement of the segmented ship model, the order of inserting the internal magnets is based on the segmented ship model, that is, the bow and stern first, then the two sides, and finally the bottom of the ship; the order of removing the internal magnets is based on the segmented ship model, that is, the bottom of the ship first, then the two sides, and finally the bow and stern, so as to ensure the stable suspension and de-suspension of the segmented ship model. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a structural schematic diagram of the segmented ship model and the segmented hull of the present invention (Examples 1 and 2).

[0056] Figure 2 for Figure 1 Side view (section view).

[0057] Figure 3 for Figure 2 A partial enlarged view of point A in the middle.

[0058] Figure 4 It is a schematic diagram of the connection between the middle section of the hull magnet and the frame of the present invention.

[0059] Figure 5 This is a working principle diagram when the opposite surfaces of the segmented ship model and the suspension support magnet of the present invention are facing each other.

[0060] Figure 6 It is a schematic structural diagram of the middle section of the hull magnet of the present invention.

[0061] Figure 7 It is a structural schematic diagram of the segmented ship model and the segmented hull of the present invention (Example 3).

[0062] Figure 8 for Figure 7Side view (section view).

[0063] Among them: 1. Sectional ship model;

[0064] 11. Segmented hull; 12. First bow magnet; 13. Rib frame; 14. Measuring beam; 15. Fixed base; 16. Acceleration sensor; 17. First stern magnet; 18. Transverse frame;

[0065] 2. Suspended support;

[0066] 21. frame; 2101. first frame structure; 2102. second frame structure; 2103. third frame structure; 2104. connector; 22. second bow magnet assembly; 23. hull magnet assembly; 231. left section of hull magnet; 232. right section of hull magnet; 233. middle section of hull magnet; 23301. opening slot; 23302. observation through hole; 23303. internal magnet; 23304. fixed limit plate; 23305. elastic element; 23306. movable limit plate; 24. universal wheel; 27. second stern magnet assembly. DETAILED DESCRIPTION

[0067] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0068] like Figure 1-Figure 2 As shown, the test device for modal measurement of a segmented ship model of the first embodiment includes a segmented ship model 1 and a suspension support 2 matched with the segmented ship model 1. During the test, the suspension support 2 keeps the segmented ship model 1 in a suspended state.

[0069] The structure of the segmented ship model 1 is as follows: it includes segmented hulls 11 arranged side by side in sequence, and a plurality of rib frames 13 are arranged at intervals along the length direction of the ship on the inner wall of each segmented hull 11, and the rib frames 13 are U-shaped, and the two ends of a single rib frame 13 are connected by a transverse frame 18, and a fixed base 15 is arranged on the upper part of each transverse frame 18, and a plurality of fixed bases 15 are simultaneously connected to a measuring beam 14 arranged along the length direction of the ship, and the rib frames 13 are made of NdFeB permanent magnets and are magnetized. In order to collect the vibration frequency and modal vibration shape of the segmented ship model 1 in the suspended state during the test, an acceleration sensor 16 is generally arranged on the measuring beam 14, and a plurality of acceleration sensors 16 correspond to the upper end surface of the measuring beam 14 at the opening of the segmented ship model 1.

[0070] A first bow magnet 12 is installed at the bow longitudinal section of the segmented ship model 1, and a first stern magnet 17 is installed at the stern longitudinal section of the segmented ship model 1. The first bow magnet 12 and the first stern magnet 17 are both made of NdFeB permanent magnets and are magnetized.

[0071] The segmented hull 11 is made of glass fiber reinforced plastic coating and is designed in sections according to the test requirements. The rib frame 13, the first bow magnet 12 and the first stern magnet 17 are connected to the segmented hull 11 by multi-layer glass fiber reinforced plastic pasting. The rib frame 13 and the transverse frame 18 are connected by bonding or riveting. The connection between the transverse frame 18, the fixed base 15 and the measuring beam 14 can be welded. The rib frame 13, the first bow magnet 12 and the first stern magnet 17 not only serve as the skeleton of the segmented hull 11, but also have magnetism. The neodymium iron boron permanent magnet used in the production of the rib frame 13, the first bow magnet 12 and the first stern magnet 17 is calculated based on the weight of the segmented ship model 1 and its loading. The magnetic force of the neodymium iron boron permanent magnet is generally proportional to its volume. When calculating the size of the NdFeB permanent magnet, the total weight of all objects in the segmented ship model 1 (including the components and measuring instruments that make up the segmented ship model 1) should be fully estimated. According to the principle of force balance, the magnetic force generated by the NdFeB permanent magnet should be greater than the total weight of all objects in the segmented ship model 1, and a safety factor of 1.5 should be taken. Magnetize the NdFeB permanent magnet according to the structure and magnetic field distribution required by the design to ensure that the direction of the magnetic pole meets the requirements.

[0072] NdFeB permanent magnets can be made into single-sided magnets with zinc-plated surface.

[0073] The structure of the suspension support 2 is as follows: it includes a frame 21, the internal space of the frame 21 matches the exterior of the ship model, and a plurality of hull magnet assemblies 23 are arranged on the frame 21 at intervals along the length of the ship, and each hull magnet assembly 23 corresponds to the position of the rib frame 13 one by one.

[0074] A second bow magnet assembly 22 is disposed on the frame 21 corresponding to the first bow magnet 12 , and a second stern magnet assembly 27 is disposed on the frame 21 corresponding to the first stern magnet 17 .

[0075] The hull magnet assembly 23, the first stern magnet 17 and the second stern magnet assembly 27 are magnetic components, which are arranged on the frame 21 and generate a magnetic field corresponding to the segmented ship model 1, so that the segmented ship model 1 in the suspension support 2 is in a suspended state. The magnetic components referred to here can be permanent magnets or electromagnetic.

[0076] When the segmented ship model 1 is placed above the interior of the suspension support 2, the opposite magnetic poles of the hull magnet assembly 23 and the rib frame 13 are the same and face each other, and the opposite magnetic poles of the first bow magnet 12 and the second bow magnet assembly 22 are the same and face each other, and the magnetic fields generated by the hull magnet assembly 23, the second bow magnet assembly 22 and the second stern magnet assembly 27 repel the magnetic fields generated by the rib frame 13, the first bow magnet 12 and the first stern magnet 17, respectively, and the segmented ship model 1 is suspended above the interior of the suspension support 2. Figure 5As shown, the upper part represents the magnet of the segmented ship model, and the lower part represents the magnet of the suspension support 2. The opposite magnetic poles of the two are N poles and face each other. Of course, the opposite magnetic poles can also be S poles.

[0077] The rib frame 13 of the segmented ship model 1 interacts with the hull magnet assembly 23 of the suspension support 2 to generate vertical and horizontal forces, so that the segmented ship model 1 will not undergo horizontal displacement in the ship width direction after being lifted up; the first bow magnet 12 and the first stern magnet 17 of the segmented ship model 1 are respectively opposite to the second bow magnet assembly 22 and the second stern magnet assembly 27 of the suspension support 2, which are mainly used to limit the segmented ship model 1 from horizontal displacement in the ship length direction, so that the segmented ship model 1 can achieve suspension balance above the inside of the suspension support 2.

[0078] By arranging a suspension support 2 below the segmented ship model 1, and arranging magnets with the same poles facing each other at the bow and stern of the segmented ship model 1 and at the rib positions, the suspension support 2 generates a uniform reverse thrust on the outside of the segmented ship model 1, and while overcoming the gravity of the segmented ship model 1, the segmented ship model 1 is restricted on all sides so that the segmented ship model 1 does not undergo horizontal displacement, and the segmented ship model 1 is suspended above the inside of the suspension support 2. Therefore, when performing a modal test on the dry structure of the ship model, it is avoided that the segmented ship model 1 is in a state of contact with external components by using a suspension method, that the bending nodes are searched for, and that the ship model is repeatedly unloaded and lifted for many times, and that the lifting posture of the ship model is adjusted, and the interference-free suspension of the segmented ship model 1 is achieved at one time. The bending parameters of the two-node, three-node, four-node and other bending parameters of the dry structure of the segmented ship model 1 can be measured at one time, and the horizontal bending and torsion modal parameters can be tested without adjusting the state, so that the modal characteristics can be obtained quickly and accurately, and the work efficiency is improved while avoiding the dangerous factors and uncertain factors in multiple liftings.

[0079] In order to ensure that the magnetic fields generated by the segmented ship model 1 and the suspension support 2 do not interact with their respective components and affect the direction of the suspension force, further improvements can be made in the selection of materials for the segmented ship model 1 and the suspension support 2, and non-magnetic materials can be used as much as possible. The transverse frame 18, the fixed base 15 and the measuring beam 14 in the segmented ship model 1 can be made of aluminum, aluminum alloy or austenitic stainless steel, and the frame 21 of the suspension support 2 is made of non-magnetic material, and the material is selected according to the structural form.

[0080] In order to facilitate the movement of the suspension support 2 , a universal wheel 24 may be provided at the lower portion of the suspension support 2 .

[0081] like Figure 2As shown, a single hull magnet assembly 23 is segmented, including a hull magnet left section 231 and a hull magnet right section 232 respectively located on both sides along the length of the ship, the hull magnet left section 231 and the hull magnet right section 232 respectively corresponding to the two side edges of the rib frame 13, and also including a hull magnet middle section 233 located at the bottom of the suspension support 2, the hull magnet middle section 233 corresponds to the bottom edge of the rib frame 13.

[0082] The hull magnet assembly 23 is segmented, so that it can save materials and facilitate the design and manufacture of the magnet structure while satisfying the repulsive force on the rib frame 13.

[0083] like Figure 3-Figure 4 , Figure 6 As shown, the second bow magnet assembly 22, the second stern magnet assembly 27, the hull magnet left section 231, the hull magnet right section 232 and the hull magnet middle section 233 have the same structure.

[0084] The structure of the middle section 233 of the hull magnet is: it includes an opening slot 23301 of a tubular structure, one side of the opening slot 23301 is connected to the frame 21, one end of the opening slot 23301 is closed by a fixed limiting plate 23304, and an internal magnet 23303 is installed inside the opening slot 23301, and the internal magnet 23303 is a neodymium iron boron permanent magnet.

[0085] Specifically, the internal magnet 23303 is a neodymium iron boron permanent magnet, which provides magnetism for the second bow magnet assembly 22, the second stern magnet assembly 27, the left section 231 of the hull magnet, the right section 232 of the hull magnet and the middle section 233 of the hull magnet, thereby reducing the lines and related electronic control devices required for the use of electromagnetic components. The specific structure of the internal magnet 23303 and the tubular structure corresponding to the opening slot 23301 are adapted to the corresponding position structure of the segmented ship model 1.

[0086] A movable limiting plate 23306 is symmetrically arranged at the opening of the other end of the opening slot 23301. The movable limiting plate 23306 is connected to the inner wall of the opening slot 23301 through the elastic element 23305. The two movable limiting plates 23306 close the opening of the opening slot 23301 under the action of the elastic element 23305 so that the internal magnet 23303 is limited inside the opening slot 23301.

[0087] The elastic element 23305 is a right-angle spring made of polymer rubber or other elastic body of non-magnetic material that can rebound the movable limit plate 23306. When the internal magnet 23303 is inserted from the opening at the other end of the opening slot 23301, the elastic element 23305 is squeezed and opens inward. When the internal magnet 23303 completely enters the opening slot 23301, the elastic element 23305 is no longer squeezed and returns to the initial state, and the two movable limit plates 23306 close the opening of the opening slot 23301. After the test, the movable limit plate 23306 is pushed into the opening slot 23301 at a certain angle, so that the internal magnet 23303 can be completely taken out.

[0088] The material of the opening slot 23301 is non-magnetic material, and its tubular structure can be the tubular structure of the opening slot 23301 component, or it can be a tubular structure formed by combining the opening in the length direction of the opening slot 23301 with the connecting surface of the frame 21. The tubular structure of the opening slot 23301 is mainly used to load the internal magnet 23303.

[0089] The fixed limiting plate 23304 of the second bow magnet assembly 22 and the fixed limiting plate 23304 of the second stern magnet assembly 27 are both located at the lower part of the opening slot 23301 .

[0090] like Figure 3 As shown, the side wall of the opening slot 23301 is provided with an observation hole 23302 along the length direction of the opening slot 23301, so that the position and state of the internal magnet 23303 in the opening slot 23301 can be easily seen.

[0091] like Figure 3 As shown, the internal magnet 23303 is a plurality of NdFeB permanent magnets with block structures connected end to end. The internal magnet 23303 with this structure is easy to manufacture, and a plurality of block structures are spliced ​​in an open slot 23301 with a certain curvature to form a magnet with a certain curvature requirement, thereby reducing manufacturing difficulty and cost.

[0092] like Figure 1-Figure 2 As shown, the test device for modal measurement of the segmented ship model of the second embodiment is based on the first embodiment, and the frame 21 is set as a shell-like structure whose internal space matches the exterior of the ship model, and the second bow magnet assembly 22, the second stern magnet assembly 27 and the hull magnet assembly 23 are installed on the outer surface of the frame 21. After the segmented ship model 1 is placed in the internal space of the frame 21, the gap between the internal space of the frame 21 and the segmented ship model 1 is greater than or equal to zero.

[0093] The frame 21 of the shell structure can be a specially made shell that matches the segmented ship model 1, such as made of thermoplastic rubber. When the segmented ship model 1 is hoisted onto the shell, it is softened by heating and pasted onto the segmented ship model 1. It can fit any ship model shape. After cooling, the opening groove 23301 is pasted on the outside of the segmented ship model 1. After the test is completed, the shell structure is softened again and collapsed into a regular shape.

[0094] In addition, the shell-shaped frame 21 can be a negative mold shell for making a ship model, and the negative mold shell is copied from a positive mold made by the molding line of the target ship model.

[0095] The female mold shell 1 is generally made of fiberglass. Since ship models are often only made for related test performance analysis, the female mold shell is discarded after the hull line is finalized, and the utilization rate of the female mold is extremely low. The female film shell is used as the frame 21, and an opening groove 23301 is added to the outside of the female mold shell. Generally, the method of pasting is adopted. The perfect fit between the female mold shell and the segmented ship model 1 is now utilized, which is also convenient for the design and production of the external opening groove 23301. At the same time, the frame 21 has a better effect when carrying the segmented ship model 1, and the female film shell is also reused, achieving the purpose of saving costs, improving quality and increasing efficiency. The material of the opening groove 23301, the fixed limit plate 23304, and the movable limit plate 23306 can be made of fiberglass.

[0096] like Figure 7-Figure 8 As shown, the test device for modal measurement of segmented ship model of embodiment 3 is based on embodiment 1, and the frame 21 is a frame structure, including multiple first frame structures 2101 corresponding to the rib frame 13, the second frame structure 2102 corresponding to the first bow magnet 12 and the third frame structure 2103 corresponding to the first stern magnet 17. The first frame structure 2101, the second frame structure 2102 and the third frame structure 2103 are connected by a connecting piece 2104 to form a frame structure.

[0097] The frame structure may be an integrated frame structure or a split frame structure. The principle is that the frame structure provides an installation foundation for the hull magnet assembly 23 , the second bow magnet assembly 22 and the second stern magnet assembly 27 .

[0098] The hull magnet assembly 23 is installed on the outside of the first frame structure 2101, the second bow magnet assembly 22 is installed on the outside of the first frame structure 2101, and the second stern magnet assembly 27 is installed on the outside of the third frame structure 2103. The outside of the first frame structure 2101 is relative to the part close to the segmented ship model 1, the side facing the segmented ship model 1 is the inner side, and the side away from the segmented ship model 1 is the outer side. The frame body 21 of the frame structure can be made of aluminum, aluminum alloy or austenitic stainless steel, etc. The materials of the opening groove 23301 and the fixed limiting plate 23304 and the movable limiting plate 23306 can be correspondingly selected from aluminum, aluminum alloy or austenitic stainless steel, etc., so that the opening groove 23301 is easy to be installed on the frame body 21.

[0099] The method for measuring the modal state of a segmented ship model of the fourth embodiment comprises the following steps:

[0100] Preparation before testing: a segmented ship model 1 and a suspension support 2 matching the segmented ship model 1 are manufactured, the suspension support 2 is provided with a second bow magnet assembly 22, a second stern magnet assembly 27 and a hull magnet assembly 23 for suspending the segmented ship model 1 above the inside thereof, the rib frame 13 of the segmented ship model 1 is made of NdFeB permanent magnets and is magnetized, and the rib frame 13 corresponds to the hull magnet assembly 23, the first bow magnet 12 and the first stern magnet 17 are respectively installed at the bow longitudinal section and the stern longitudinal section of the segmented ship model 1, the first bow magnet 12 and the first stern magnet 17 are both made of NdFeB permanent magnets and are magnetized, and the first bow magnet 12 and the first stern magnet 17 correspond to the second bow magnet assembly 22 and the second stern magnet assembly 27, respectively. An acceleration sensor 16 is arranged on the measuring beam 14 and connected to a test data processing device.

[0101] Placing the segmented ship model 1: When the hull magnet assembly 23 , the second bow magnet assembly 22 and the second stern magnet assembly 27 do not generate a magnetic field at the suspension support 2 , the segmented ship model 1 is placed inside the suspension support 2 .

[0102] Suspending the segmented ship model 1: the hull magnet assembly 23, the second bow magnet assembly 22 and the second stern magnet assembly 27 are all combined structures of an open slot 23301 of a tubular structure with an internal magnet 23303 installed inside. The material of the internal magnet 23303 is a neodymium iron boron permanent magnet, and the internal magnet 23303 can be composed of a plurality of block structures connected end to end. After the segmented ship model 1 is placed, the internal magnet 23303 is inserted into the open slot 23301, so that the segmented ship model 1 is suspended in the suspension support 2, and each part of the segmented ship model 1 is detected and confirmed to be detached from the suspension support 2.

[0103] Dry modal test: After the segmented ship model 1 is suspended, a hammer is used to vertically strike the measuring beam 14 at the bow or stern of the segmented ship model 1, and signals are collected to test vertical bending modal parameters; a hammer is used to horizontally strike the measuring beam 14 at the bow or stern of the segmented ship model 1, and signals are collected to test horizontal bending modal parameters; a hammer is used to vertically strike the outermost side of the ship's side at the bow or stern of the segmented ship model 1, and signals are collected using the measuring beam 14 to test torsional modal parameters.

[0104] De-suspending the segmented ship model 1: taking out the magnet 23303 inside the opening slot 23301, removing the magnetism at the corresponding positions of the hull magnet assembly 23, the second bow magnet assembly 22 and the second stern magnet assembly 27 of the suspension support 2, so that the segmented ship model 1 steadily descends into the suspension support 2 and is no longer suspended, completing the measurement work.

[0105] The above method of measuring the modal of the segmented ship model is used to build a new suspended ship model dry structure modal test system. There is no need to find bending nodes, consider the tightness of the elastic rope, or repeatedly unload and lift the ship model. Only the internal magnet 23303 is inserted into the opening groove 23301 of the suspension support 2 to enable the segmented ship model 1 to be suspended in the suspension support 2. The vertical two-node, three-node, and four-node bending parameters of the dry structure can be measured at one time. At the same time, the bending parameters such as horizontal bending and torsion can be tested to accurately and quickly obtain the modal characteristics.

[0106] The method for measuring the modal state of a segmented ship model of the fifth embodiment comprises the following steps:

[0107] Preparation before testing: a segmented ship model 1 and a suspension support 2 matching the segmented ship model 1 are manufactured, the suspension support 2 is provided with a second bow magnet assembly 22, a second stern magnet assembly 27 and a hull magnet assembly 23 for suspending the segmented ship model 1 above the inside thereof, the rib frame 13 of the segmented ship model 1 is made of NdFeB permanent magnets and is magnetized, and the rib frame 13 corresponds to the hull magnet assembly 23, the first bow magnet 12 and the first stern magnet 17 are respectively installed at the bow longitudinal section and the stern longitudinal section of the segmented ship model 1, the first bow magnet 12 and the first stern magnet 17 are both made of NdFeB permanent magnets and are magnetized, and the first bow magnet 12 and the first stern magnet 17 correspond to the second bow magnet assembly 22 and the second stern magnet assembly 27, respectively. An acceleration sensor 16 is arranged on the measuring beam 14 and connected to a test data processing device.

[0108] like Figure 2 , Figure 8As shown, a single hull magnet assembly 23 is segmented, including a hull magnet left section 231 and a hull magnet right section 232 respectively located on both sides along the length direction of the ship, the hull magnet left section 231 and the hull magnet right section 232 respectively corresponding to the two sides of the rib frame 13, and also including a hull magnet middle section 233 located at the bottom of the suspension support 2, the hull magnet middle section 233 corresponding to the bottom side of the rib frame 13;

[0109] Placing the segmented ship model 1: When the hull magnet assembly 23 , the second bow magnet assembly 22 and the second stern magnet assembly 27 do not generate a magnetic field at the suspension support 2 , the segmented ship model 1 is placed inside the suspension support 2 .

[0110] Suspending the segmented ship model 1: the hull magnet assembly 23, the second bow magnet assembly 22 and the second stern magnet assembly 27 are all combined structures of an open slot 23301 of a tubular structure with an internal magnet 23303 installed inside. The material of the internal magnet 23303 is a neodymium iron boron permanent magnet, and the internal magnet 23303 can be composed of a plurality of block structures connected end to end. After the segmented ship model 1 is placed, the internal magnet 23303 is inserted into the open slot 23301, so that the segmented ship model 1 is suspended in the suspension support 2, and each part of the segmented ship model 1 is detected and confirmed to be detached from the suspension support 2.

[0111] The order of inserting the internal magnet 23303 is to first insert the internal magnet 23303 at the second bow magnet assembly 22 and the second stern magnet assembly 27, then insert the internal magnet 23303 at the left section 231 of the hull magnet and the right section 232 of the hull magnet, and finally insert the internal magnet 23303 at the middle section 233 of the hull magnet.

[0112] Dry modal test: After the segmented ship model 1 is suspended, a hammer is used to vertically strike the measuring beam 14 at the bow or stern of the segmented ship model 1, and signals are collected to test vertical bending modal parameters; a hammer is used to horizontally strike the measuring beam 14 at the bow or stern of the segmented ship model 1, and signals are collected to test horizontal bending modal parameters; a hammer is used to vertically strike the outermost side of the ship's side at the bow or stern of the segmented ship model 1, and signals are collected using the measuring beam 14 to test torsional modal parameters.

[0113] De-suspending the segmented ship model 1: taking out the magnet 23303 inside the opening slot 23301, removing the magnetism at the corresponding positions of the hull magnet assembly 23, the second bow magnet assembly 22 and the second stern magnet assembly 27 of the suspension support 2, so that the segmented ship model 1 steadily descends into the suspension support 2 and is no longer suspended, completing the measurement work.

[0114] The order of removing the internal magnet 23303 is to first remove the internal magnet 23303 at the middle section 233 of the hull magnet, then remove the internal magnet 23303 at the left section 231 of the hull magnet and the right section 232 of the hull magnet, and finally remove the internal magnet 23303 at the second bow magnet assembly 22 and the second stern magnet assembly 27.

[0115] In the above method for measuring the modal state of a segmented ship model, the order of inserting the internal magnets 23303 is based on the segmented ship model 1, and the order is first the bow and stern, then the two sides, and finally the bottom of the ship; the order of removing the internal magnets 23303 is based on the segmented ship model 1, and the order is first the bottom of the ship, then the two sides, and finally the bow and stern, so as to ensure the steady suspension and de-suspension of the segmented ship model 1.

[0116] In order to further ensure the stability of the segmented ship model during operation, the segmented ship model 1 is suspended: when inserting the internal magnets 23303 at the left section 231 and the right section 232 of the hull magnet, the left section 231 and the right section 232 of the hull magnet at the same rib position can be operated at the same time, and at the same time, the operation can be symmetrical with the middle right section 232 of the hull magnet as the center; when inserting the internal magnets 23303 at the left section 231 and the right section 232 of the hull magnet, the two places are operated at the same time; when inserting the internal magnets 23303 at the middle section 233 of the hull magnet, it is performed sequentially from one end to the other end along the length of the ship.

[0117] In order to further ensure the stability of the segmented ship model during operation, the segmented ship model 1 is de-suspended: when taking out the internal magnet 23303 at the middle section 233 of the hull magnet, proceed in sequence from one end to the other end along the length of the ship; when taking out the internal magnet 23303 at the left section 231 of the hull magnet and the right section 232 of the hull magnet, operate the left section 231 of the hull magnet and the right section 232 of the hull magnet at the same rib position at the same time, and can be operated symmetrically with the middle right section 232 of the hull magnet as the center; when taking out the internal magnet 23303 at the second bow magnet assembly 22 and the second stern magnet assembly 27, operate at both locations at the same time.

[0118] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. A test device for measuring the modal state of a segmented ship model, characterized in that: It comprises a segmented ship model (1) and a suspension support (2) matching the segmented ship model (1); The structure of the segmented ship model (1) is as follows: it comprises segmented hulls (11) arranged in sequence side by side, a plurality of rib frames (13) are arranged at intervals along the length direction of the ship on the inner wall of each segmented hull (11), the rib frames (13) are U-shaped, two ends of a single rib frame (13) are connected by a transverse frame (18), a fixed base (15) is arranged on the upper part of each transverse frame (18), and the plurality of fixed bases (15) are simultaneously connected to a measuring beam (14) arranged along the length direction of the ship, and the rib frames (13) are made of neodymium iron boron permanent magnets and are magnetized. A first bow magnet (12) is installed at the bow longitudinal section of the segmented ship model (1), and a first stern magnet (17) is installed at the stern longitudinal section of the segmented ship model (1), wherein the first bow magnet (12) and the first stern magnet (17) are both made of neodymium iron boron permanent magnets and are magnetized; The structure of the suspension support (2) is as follows: it comprises a frame (21), the internal space of the frame (21) matches the exterior of the ship model, a plurality of hull magnet assemblies (23) are arranged on the frame (21) at intervals along the length of the ship, and each hull magnet assembly (23) corresponds to a rib frame (13) in a one-to-one position. A second bow magnet assembly (22) is arranged on a frame (21) corresponding to the first bow magnet (12), and a second stern magnet assembly (27) is arranged on a frame (21) corresponding to the first stern magnet (17); When the segmented ship model (1) is placed above the interior of the suspension support (2), the opposite magnetic poles of the hull magnet assembly (23) and the rib frame (13) are identical and face each other, the opposite magnetic poles of the first bow magnet (12) and the second bow magnet assembly (22) are identical and face each other, and the opposite magnetic poles of the first stern magnet (17) and the second stern magnet assembly (27) are identical and face each other. The magnetic fields generated by the hull magnet assembly (23), the second bow magnet assembly (22) and the second stern magnet assembly (27) repel the magnetic fields generated by the rib frame (13), the first bow magnet (12) and the first stern magnet (17), respectively, and the segmented ship model (1) is suspended above the interior of the suspension support (2).

2. A test device for measuring the modal state of a segmented ship model according to claim 1, characterized in that: The single hull magnet assembly (23) is segmented, comprising a hull magnet left section (231) and a hull magnet right section (232) respectively located on both sides along the length of the ship, the hull magnet left section (231) and the hull magnet right section (232) respectively corresponding to the two side edges of the rib frame (13), and also comprising a hull magnet middle section (233) located at the bottom of the suspension support (2), the hull magnet middle section (233) corresponding to the bottom edge of the rib frame (13).

3. A test device for measuring the modal state of a segmented ship model according to claim 2, characterized in that: The second bow magnet assembly (22), the second stern magnet assembly (27), the left section of the hull magnet (231), the right section of the hull magnet (232), and the middle section of the hull magnet (233) have the same structure; The structure of the middle section (233) of the hull magnet is as follows: it comprises an open slot (23301) of a tubular structure, one side of the open slot (23301) is connected to the frame (21), one end of the open slot (23301) is closed by a fixed limiting plate (23304), an internal magnet (23303) is installed inside the open slot (23301), and the internal magnet (23303) is a neodymium iron boron permanent magnet; A movable limiting plate (23306) is symmetrically arranged at the opening of the other end of the opening slot (23301); the movable limiting plate (23306) is connected to the inner wall of the opening slot (23301) via an elastic element (23305); and under the action of the elastic element (23305), the two movable limiting plates (23306) seal the opening of the opening slot (23301) so that the internal magnet (23303) is limited inside the opening slot (23301); The fixed limiting plate (23304) of the second bow magnet assembly (22) and the fixed limiting plate (23304) of the second stern magnet assembly (27) are both located at the bottom of the opening slot (23301).

4. A test device for measuring the modal state of a segmented ship model according to claim 3, characterized in that: The side wall of the opening groove (23301) is provided with an observation through hole (23302) along the length direction of the opening groove (23301).

5. The test device for measuring the modal state of a segmented ship model according to claim 3, characterized in that: The internal magnet (23303) is a block structure with multiple ends connected.

6. A test device for measuring the modal state of a segmented ship model according to any one of claims 1 to 5, characterized in that: The frame (21) is a shell-like structure whose internal space matches the exterior of the ship model, and a second bow magnet assembly (22), a second stern magnet assembly (27) and a hull magnet assembly (23) are mounted on the outer surface of the frame (21).

7. A test device for measuring the modal state of a segmented ship model according to claim 6, characterized in that: The frame (21) is a female mold shell used to make a ship model, and the female mold shell is made by replicating a male mold made by the molding line of the target ship model.

8. A test device for measuring the modal state of a segmented ship model according to any one of claims 1 to 5, characterized in that: The frame (21) is a frame structure, comprising a plurality of first frame structures (2101) corresponding to the rib frame (13), a second frame structure (2102) corresponding to the first bow magnet (12), and a third frame structure (2103) corresponding to the first stern magnet (17). The first tire frame structure (2101), the second tire frame structure (2102), and the third tire frame structure (2103) are connected via a connecting piece (2104) to form a frame structure; A hull magnet assembly (23) is installed on the outside of the first tire frame structure (2101), a second bow magnet assembly (22) is installed on the outside of the first tire frame structure (2101), and a second stern magnet assembly (27) is installed on the outside of the third tire frame structure (2103).

9. A method for measuring the modal state of a segmented ship model, characterized in that: Using the test device for measuring the modal state of a segmented ship model according to claim 1, the method comprises the following steps: Preparation before the test: A segmented ship model (1) and a suspension support (2) matching the segmented ship model (1) are manufactured, wherein the suspension support (2) is provided with a second bow magnet assembly (22) for suspending the segmented ship model (1) above the interior thereof, a second stern magnet assembly (27) and a hull magnet assembly (23), The rib frame (13) of the segmented ship model (1) is made of neodymium iron boron permanent magnets and is magnetized, and the rib frame (13) corresponds to the hull magnet assembly (23). A first bow magnet (12) and a first stern magnet (17) are respectively installed at the bow longitudinal section and the stern longitudinal section of the segmented ship model (1). The first bow magnet (12) and the first stern magnet (17) are both made of neodymium iron boron permanent magnets and are magnetized, and the first bow magnet (12) and the first stern magnet (17) correspond to the second bow magnet assembly (22) and the second stern magnet assembly (27), respectively. Place the segmented ship model (1): When the hull magnet assembly (23), the second bow magnet assembly (22) and the second stern magnet assembly (27) do not generate a magnetic field at the suspension support (2), the segmented ship model (1) is placed inside the suspension support (2); Suspended segmented ship model (1): The hull magnet assembly (23), the second bow magnet assembly (22), and the second stern magnet assembly (27) are all composed of a tubular structure with an open slot (23301) containing an internal magnet (23303). The material of the internal magnet (23303) is a neodymium iron boron permanent magnet. After the segmented ship model (1) is placed, the internal magnet (23303) is inserted into the opening slot (23301) to suspend the segmented ship model (1) in the suspension support (2), and detection is performed to confirm that each part of the segmented ship model (1) is detached from the suspension support (2); Dry modal testing: After the segmented ship model (1) is suspended, A hammer is used to strike the measuring beam (14) in a vertical direction at the bow or stern of the segmented ship model (1) to collect signals for testing vertical bending modal parameters. A hammer is used to strike the measuring beam (14) in the horizontal direction at the bow or stern of the segmented ship model (1), and a signal is collected to test the horizontal bending modal parameters. Using a hammer to strike the outermost side of the ship's side in a vertical direction at the bow or stern of the segmented ship model (1), and using a measuring beam (14) to collect signals to test torsional modal parameters; Segmented ship model (1) De-suspension: Remove the magnet (23303) inside the opening slot (23301), The magnetism of the corresponding positions of the hull magnet assembly (23), the second bow magnet assembly (22) and the second stern magnet assembly (27) of the suspension support (2) is removed, so that the segmented ship model (1) steadily descends into the suspension support (2) and is no longer suspended, thereby completing the measurement work.

10. The method for measuring the modal state of a segmented ship model according to claim 9, characterized in that: The single hull magnet assembly (23) is segmented, comprising a hull magnet left section (231) and a hull magnet right section (232) respectively located on both sides along the length of the ship, the hull magnet left section (231) and the hull magnet right section (232) respectively corresponding to the two side edges of the rib frame (13), and also comprising a hull magnet middle section (233) located at the bottom of the suspension support (2), the hull magnet middle section (233) corresponding to the bottom edge of the rib frame (13); In the step of suspending the segmented ship model (1), the order of inserting the internal magnets (23303) is to first insert the internal magnets (23303) at the second bow magnet assembly (22) and the second stern magnet assembly (27), then insert the internal magnets (23303) at the left section (231) and the right section (232) of the hull magnet, and finally insert the internal magnets (23303) at the middle section (233) of the hull magnet. In the de-suspension step of the segmented ship model (1), the order of removing the internal magnets (23303) is to first remove the internal magnets (23303) at the middle section (233) of the hull magnet, then remove the internal magnets (23303) at the left section (231) and the right section (232) of the hull magnet, and finally remove the internal magnets (23303) at the second bow magnet assembly (22) and the second stern magnet assembly (27).

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