A floating body test method based on three-dimensional hydroelastic analysis

Abstract

A floating body testing method based on three-dimensional hydroelastic analysis includes the following steps: acquiring the topography of the large floating body's deployment location; designing a large floating body digital model; determining the structure and cross-sectional dimensions of the three-dimensional beam; calculating the vibration frequency of the large floating body digital model; performing error analysis between the vibration frequency of the large floating body digital model and the actual floating body frequency; determining the scale ratio of the small floating body model; establishing a small floating body model and a small floating body digital model based on the scale ratio and obtaining load data; comparing the calculated loads of the small floating body digital model and the actual floating body with the experimental load data after dimensionless transformation; comparing the calculated loads with the experimental load data to analyze the difference between the calculated loads and the experimental loads, and verifying the correctness of the calculation results. This facilitates the calibration and improvement of the segmented floating body model and the design optimization of the actual floating body mathematical model, effectively verifying the mathematical model of the floating body structure.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding and marine engineering technology, and in particular to a floating body testing method based on three-dimensional hydroelastic analysis. Background Technology

[0002] In the past decade, several accidents involving ship structural failures at sea have occurred. Giant ocean-going vessels exceeding 300 meters in length can be easily broken or twisted like chopsticks at sea. This has led to a research topic: how to effectively determine the effective external load on such large container ships while ensuring sufficient safety margins in the ship's structural design. Three-dimensional hydroelastic analysis is undoubtedly a primary means of solving this thorny problem. Numerous studies have found that the hydroelastic effects on ultra-large ships are very significant, and have different impacts on the overall longitudinal bending and fatigue damage of the hull structure. Flutter can increase the midship bending moment and shear force by 20%-25%, and wave-induced vibration increases the cumulative fatigue damage of the ship by nearly 20%.

[0003] In the design of large floating bodies, three-dimensional hydroelasticity analysis is commonly used to simplify the ship's structural mathematical model into a three-dimensional beam model. This method forms the basis for rapid analysis of hydroelasticity. Segmented ship models fabricated at scale based on the ship's structural mathematical model are an effective experimental method for measuring wave loads. Conducting wave load tests on these segmented ship models effectively verifies the results of the three-dimensional hydroelasticity analysis. In small floating body models, the measuring beam is a continuous component connecting several hull segments, simulating both the stiffness at the ship segments and the transmission of wave loads.

[0004] However, the mathematical model of ship structure designed by the three-dimensional hydroelastic analysis method does not fully consider the influence of seabed topography, and the boundary values ​​of the three-dimensional hydroelastic analysis method are not rich enough to effectively verify the mathematical model of ship structure. In addition, the three-dimensional hydroelastic mechanical analysis only stays at the theoretical level. Usually, load tests are carried out after the ship structure mathematical model is scaled down and segmented ship models are made. The load analysis in the segmented ship model test process is completely separated from the three-dimensional hydroelastic mechanical analysis in the ship structure mathematical model, which is not convenient for the calibration and improvement of the segmented ship model, nor for the design optimization of the ship structure mathematical model.

[0005] Therefore, it is necessary to unify the mathematical model of ship structure based on three-dimensional hydroelastic analysis with the measurement beam of segmented water tank ship model and establish a standardized design process. Such a design has not yet been publicly disclosed. Summary of the Invention

[0006] To address the shortcomings of existing production technologies, this applicant provides a floating body testing method based on three-dimensional hydroelastic analysis. This method fully considers the influence of seabed topography, increases the boundary values ​​of the three-dimensional hydroelastic analysis method, and introduces the calculated loads of the small-scale floating body model and the actual floating body during the test of the scaled-down small floating body model. This facilitates the calibration and improvement of the segmented floating body model and the design optimization of the actual floating body mathematical model, and effectively verifies the mathematical model of the floating body structure.

[0007] The technical solution adopted in this invention is as follows:

[0008] A floating body test method based on three-dimensional hydroelastic analysis includes the following steps:

[0009] Obtain the topography of the large floating body deployment location: Conduct on-site measurements of the three-dimensional topography data of the sea area where the actual floating body is deployed, including wave conditions and seabed topography;

[0010] Large-scale floating body digital model design: Under the condition of the terrain at the deployment location, a three-dimensional beam model of the large floating body is designed through three-dimensional hydroelastic analysis. First, the actual floating body profile is input to establish the outer shell of the large-scale floating body digital model. Then, the large-scale floating body digital model is divided into N segments along the length direction, with the initial state being N≥2. Finally, the mass of each segment structure is obtained using finite element software. and the stiffness I of each section j i = natural numbers from 1 to N, j = natural numbers from 1 to (N-1); the section is located on the three-dimensional beam at the segment point, I j Including torsional moment of inertia I xj Vertical moment of inertia I yj Horizontal moment of inertia I zj ;

[0011] Determine the structure and cross-sectional dimensions of the three-dimensional beam: Based on the type of load to be analyzed, select the cross-sectional structure of the three-dimensional beam in the three-dimensional beam model, and calculate the cross-sectional dimensions of N-1 beams;

[0012] Calculate the vibration frequency of a large floating body digital model: calculate the vibration frequency under the load type to be analyzed through modal analysis;

[0013] Error analysis is performed between the vibration frequency of the large floating body digital model and the actual floating body frequency: the actual floating body frequency is the design target value, and the error results are obtained by comparing each order frequency of the actual floating body with the vibration frequency of the large floating body digital model. ε is the upper limit of the error. If the error result is greater than ε, the large floating body digital model needs to be further subdivided and the value of N needs to be increased; if the error result is less than or equal to ε, the design of the large floating body digital model is completed.

[0014] Determine the scale ratio of the small floating body model: Determine the scale ratio of the small floating body model based on the shortest wavelength of the water tank. The water tank is used for wave-induced vibration tests of the small floating body model. The shortest wavelength of the water tank is the shortest wavelength of the water tank wave generator.

[0015] Based on the scale ratio, a small-scale floating body model and a small-scale floating body numerical model were established, and load data were obtained:

[0016] A small floating model is manufactured according to the scale. The small floating model includes a measuring beam. A false bottom is built in the water tank. The false bottom is the scaled-down terrain. Wave-induced vibration test is carried out on the small floating model in the water tank to obtain the test load data of the small floating model.

[0017] A small floating body numerical model was established, which is similar in structure and size to the small floating body model. Modal analysis and hydroelastic response calculation were performed on the small floating body numerical model under scaled-down three-dimensional terrain conditions to obtain the calculated load of the small floating body numerical model.

[0018] Load analysis: The calculated loads of the small floating body digital model and the actual floating body are compared with the experimental load data after being dimensionless. The comparison is based on the experimental load data to analyze the difference between the calculated load and the experimental load and verify whether the calculation results are correct.

[0019] The three-dimensional beam is a variable cross-section beam with N segments, and its cross-sectional structure is the same as that of the measuring beam.

[0020] When the type of load to be analyzed is vertical bending load, the cross-sectional structure of the three-dimensional beam is a hollow circular tube or a hollow rectangle;

[0021] When the loads to be analyzed are vertical and horizontal bending loads, the cross-sectional structure of the three-dimensional beam is a hollow rectangle or a hollow elliptical tube.

[0022] When the types of loads to be analyzed are vertical, horizontal bending loads and torsional loads, the cross-sectional structure of the three-dimensional beam is a hollow open rectangle or a hollow open elliptical tube.

[0023] When the load to be analyzed is a vertical bending load, the three-dimensional beam adopts a hollow rectangular cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical bending modal calculations:

[0024] Assume the outer width B of the hollow rectangle j external height H j Inner width b j , inner height h j And H j =6B j h j =6b j B j =2b jLet j be a natural number from 1 to (N-1), and let I be the vertical moment of inertia of the j-th segment of the three-dimensional beam. yj :

[0025]

[0026] From equation (1.1), the inner width b of the three-dimensional beam with a hollow rectangle can be obtained. j :

[0027]

[0028] The stiffness I can be determined based on the actual cross-section of the floating body. yj The numerical value of b is calculated using equation (1.2). j This allows us to obtain all the dimensions of the hollow rectangle.

[0029] When the load to be analyzed is a vertical bending load, the three-dimensional beam adopts a hollow circular tube cross-section structure, and the structural calculation of each segment of the three-dimensional beam is performed through vertical bending modal calculation:

[0030] Assume the outer diameter D of the hollow circular tube j , inner diameter d j And D j =3d j Let j be a natural number from 1 to (N-1), and let I be the vertical moment of inertia of the j-th segment of the three-dimensional beam. yj :

[0031]

[0032] The inner diameter d of the hollow circular tube can be obtained from equation (2.1). j :

[0033]

[0034] Based on the stiffness of the actual floating body cross-section, I yj The numerical value d is calculated using equation (2.2). j This allows us to obtain all the dimensions of the hollow circular tube.

[0035] When the load types to be analyzed are vertical and horizontal bending loads, or vertical, horizontal bending and torsional loads, the three-dimensional beam adopts a hollow rectangular cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical and horizontal bending modal calculations:

[0036] Assume the outer width B of the hollow rectangle j external height H j Inner width b j , inner height h j And H j =α j B j h j =αj b j Let j be a natural number from 1 to (N-1), and let I be the vertical moment of inertia of the j-th segment of the three-dimensional beam. yj With horizontal moment of inertia I zj The ratio is:

[0037]

[0038] From equation (3.1), the aspect ratio parameter α of the hollow rectangle can be obtained. j :

[0039]

[0040] Based on the stiffness of the actual floating body cross-section, I yj and I zj The aspect ratio parameter α can be calculated from equation (3.2). j Furthermore, based on the vertical moment of inertia I yj With horizontal moment of inertia I zj Calculate all dimensions of the hollow rectangle.

[0041] When the load types to be analyzed are vertical and horizontal bending loads, or vertical, horizontal bending and torsional loads, the three-dimensional beam adopts a hollow elliptical tube cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical and horizontal bending modal calculations:

[0042] Assume the outer major axis A of the hollow elliptical tube j outer minor axis B j Inner major axis a j Inner short axis b j And A j =β j B j a j =β j b j Then the vertical moment of inertia I yj With horizontal moment of inertia I zj The ratio is:

[0043]

[0044] Based on the stiffness of the actual floating body cross-section, I yj and I zj The numerical value is based on the stiffness I of the actual ship profile. yj and I zj The aspect ratio parameter β of the hollow rectangular hull beam can be determined according to the following formula. j :

[0045]

[0046] Furthermore, based on the vertical moment of inertia Iyj With horizontal moment of inertia I zj The calculation formula yields all dimensions of the hollow elliptical tube.

[0047] The structure of the small floating body model is as follows: it includes an outer shell, which is divided into N sections. Multiple rib frames are set inside the outer shell and are arranged at intervals along the length of the ship. Each rib frame is equipped with a base at its upper end. It also includes a measuring beam, which is fixedly connected to the rib frame through the base. The two ends of the upper part of a single rib frame are connected by a crossbeam. The middle part of the crossbeam is fixedly connected to the lower end of the rib frame through a column. A mass loading device is installed on the rib frame.

[0048] The mass loading device is used to adjust the mass distribution of small floating body models;

[0049] The number of mass loading devices inside each section of the outer shell is four, two on each of the port and starboard sides.

[0050] The structure of the mass loading device is as follows: it includes a vertical rod, a lower base is provided at the lower end of the vertical rod, a first set of weights is placed on the lower base, an upper base is provided at the upper part of the vertical rod and a second set of weights is placed on the upper base, and the relative height of the vertical rod relative to the crossbeam is fixed and adjusted by a lifting and locking device.

[0051] During the process of manufacturing a small floating model according to a scale:

[0052] Based on the scale ratio and the mass of each segment of the large floating body digital model By considering the center of gravity, the overall mass M of each segment of the small floating model can be obtained. i And the overall center of gravity (x) of each segment of the small floating model. ic y ic , z ic ).

[0053] After constructing the main structure of each small floating body model, the mass m of each section was obtained by weighing it. i0 The center of gravity of the main structure of each small floating model is measured as (x i0 y i0 , z i0 ),

[0054] Then, a mass loading device was installed on each small floating model section, and the total weight of the weights on the four vertical rods was adjusted to be m. i1 m i2 m i3 m i4 The corresponding centroids are (x i1 y i1 , z i1 ), (x i2 yi2 , z i2 ), (x i3 y i3 , z i3 ), (x i4 y i4 , z i4 ), its centroid is (x ic y ic , z ic This yields the following system of equations:

[0055]

[0056] The total mass m of the first and second weight sets on each vertical rod, calculated based on the above equations, is... i1 m i2 m i3 m i4 .

[0057] The lifting and locking device comprises a gear component rotatably mounted below the crossbeam via a support column. One side of the support column is the vertical rod, and the middle of the vertical rod is provided with a single-sided tooth structure that meshes with the gear component. A rotating shaft is mounted on the crossbeam on the other side of the support column. The middle of the rotating shaft is provided with a screw portion that meshes with the gear component. The upper end of the rotating shaft is rotatably connected to the crossbeam, and the lower end of the rotating shaft is supported and limited by a support plate installed inside the rib frame. The length directions of the rotating shaft and the vertical rod are both vertical, and a hand crank is provided at the upper end of the rotating shaft.

[0058] Based on the total mass m of the first and second weight groups i1 m i2 m i3 m i4 Vertical coordinate z of the center of gravity i1 , z i2 , z i3 , z i4 The specific weights on the first and second weight groups are adjusted in position. At the same time, the screw is rotated by turning the hand crank, and the rotation is transmitted to the vertical rod through the gear mechanism, causing the vertical rod to move up and down. After adjusting the overall height of the first and second weight groups to meet the vertical coordinate position of the center of gravity, a braking structure is used to fix the rotation position of the rotating shaft relative to the crossbeam.

[0059] The braking structure includes a plug and a first insertion hole disposed on the upper surface of the crossbeam. The upper end face of the rotating shaft is provided with a plurality of second insertion holes, which are evenly distributed along the circumference of the rotating shaft. When the vertical rod moves up and down into place, one end of the plug is inserted into the first insertion hole, and the other end of the plug is inserted into the second insertion hole when the plug is aligned, thereby fixing the rotational position of the rotating shaft relative to the crossbeam.

[0060] The beneficial effects of this invention are as follows:

[0061] This invention features a compact and reasonable structure, and is easy to operate. By fully considering the influence of seabed topography, it increases the boundary values ​​of the three-dimensional hydroelastic analysis method. Simultaneously with the scaled-down small floating body model test, it introduces the calculation loads of the small floating body numerical model and the actual floating body, which facilitates the calibration and improvement of the segmented floating body model and the design optimization of the actual floating body mathematical model, and effectively verifies the mathematical model of the floating body structure.

[0062] Furthermore, the present invention also has the following advantages:

[0063] (1) For floating bodies that require consideration of seabed topography for hydroelastic analysis and pool testing, this method is time-saving and labor-saving, allowing for the rapid construction of a three-dimensional hydroelastic analysis floating body beam model and a measuring beam for segmented ship model testing. Different shapes of hull beams can be selected as needed, and the specific shape and dimensions of the three-dimensional beam can be determined according to the corresponding formulas. A set of three-dimensional beams that can consider the mass distribution and stiffness distribution of the floating body can be designed. This can be used as a structural model for calculating the vertical wave load in three-dimensional hydroelastic analysis, and can also be used to design a measuring beam for segmented ship model testing in a pool. It is a dual-purpose system with higher efficiency.

[0064] (2) Since the vertical load, horizontal load and torsional load of the floating body are related to the mass distribution and stiffness distribution of the floating body structure, the establishment of the three-dimensional beam model of the floating body is the key to the analysis of external loads and segmented model tests. The method of this embodiment can combine the small floating body model, the mass loading device 2 to adjust the parameters of the orthocenter, base, variable cross-section hull beam, and the arrangement of strain sensors to form a set of test methods for the floating body model in a simulated seabed topography pool, which is suitable for three-dimensional hydroelasticity analysis. Attached Figure Description

[0065] Figure 1 This is a flowchart of the test method steps of the present invention.

[0066] Figure 2 This is a schematic diagram of the structure of the small float of the present invention.

[0067] Figure 3 for Figure 2 Side view.

[0068] Figure 4 for Figure 2 A partial top view (a segment).

[0069] Figure 5 This is a schematic diagram of the lifting and locking device of the present invention.

[0070] Figure 6 This is a top view (an external gear) of the lifting and locking device of the present invention.

[0071] Figure 7 This is a top view of the lifting and locking device of the present invention (two external gears).

[0072] Figure 8 for Figure 5 Enlarged view of a portion of point A in the middle.

[0073] Figure 9 This is a schematic diagram of the braking structure of the present invention.

[0074] Figure 10 This is a schematic diagram of the structure of a three-dimensional beam with a hollow rectangle when the load type is vertical bending load, as analyzed in this invention.

[0075] Figure 11 This is a schematic diagram of the structure of a three-dimensional beam using a hollow circular tube when the load type is vertical bending load, as analyzed in this invention.

[0076] Figure 12 This is a schematic diagram of the structure of a three-dimensional beam using a hollow rectangle when the load types are vertical and horizontal bending loads, as analyzed in this invention.

[0077] Figure 13 This is a schematic diagram of the structure of a three-dimensional beam using a hollow circular tube when the load types are vertical and horizontal bending loads, as analyzed in this invention.

[0078] Figure 14 This is a schematic diagram of the structure of a three-dimensional beam with a hollow open rectangle when the load types are vertical, horizontal bending and torsional loads, as analyzed in this invention.

[0079] Figure 15 This is a schematic diagram of the structure of a three-dimensional beam using a hollow open elliptical tube when the load types are vertical, horizontal bending and torsional loads, as analyzed in this invention.

[0080] Among them: 1. Outer shell; 11. Rib frame; 12. Crossbeam;

[0081] 2. Mass loading device; 21. Vertical rod; 22. Lower base; 23. First weight set; 24. Upper base; 25. Second weight set; 26. Lifting and locking device;

[0082] 261. Hand crank handle; 262. Rotating shaft; 263. Screw section; 264. Braking structure; 2641. Second insertion hole; 2642. Insert; 2643. First insertion hole; 265. Support plate; 266. Support column; 267. Gear component; 2671. First external gear; 2672. Second external gear; 268. Single-sided gear structure;

[0083] 3. Column; 4. Base;

[0084] 5. Measuring beam; 6. Strain sensor; 631. Strain sensor one; 632. Strain sensor two; 633. Strain sensor three. Detailed Implementation

[0085] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0086] Example 1:

[0087] like Figures 1-4 As shown, the floating body test method based on three-dimensional hydroelastic analysis in this embodiment includes the following steps:

[0088] Obtain the topography of the large floating body deployment location: Conduct on-site measurements of the three-dimensional topography data of the sea area where the actual floating body is deployed, including wave conditions and seabed topography;

[0089] Specifically, when measuring the three-dimensional topography in the field, the water depth information of the water area around the actual floating body location is obtained by using side-scan sounding based on the actual seawater depth. On the one hand, the water depth information is used for numerical modeling as the seabed boundary in the three-dimensional hydroelastic analysis; on the other hand, the topography is used as the original data for the false bottom of the water tank used in the wave-induced vibration test. The three-dimensional topography includes the channel structure that interacts with the actual floating body, as well as the wave load on the actual floating body, to ensure that the three-dimensional hydroelastic calculation structure fits the stress situation of the actual ship.

[0090] Large-scale floating body digital model design: Under the condition of the terrain at the deployment location, a three-dimensional beam model of the large floating body is designed through three-dimensional hydroelastic analysis. First, the actual floating body profile is input to establish the outer shell of the large-scale floating body digital model. Then, the large-scale floating body digital model is divided into N segments along the length direction, with the initial state being N≥2. Finally, the mass of each segment structure is obtained using finite element software. and the stiffness I of each section j i = natural numbers from 1 to N, j = natural numbers from 1 to (N-1); the section is located on the three-dimensional beam at the segment point, I j Including torsional moment of inertia I xj Vertical moment of inertia I yj Horizontal moment of inertia I zj ;I xj I yj I zjThe three are respectively as follows Figures 1-4 The diagram shows the moments of inertia of the floating body rotating about the x, y, and z axes. The origin of the coordinate system shown is located at the bottom of the outer shell 1, where the x-axis points in the direction of the ship's length, the y-axis points in the direction of the ship's width, and the z-axis points vertically upwards.

[0091] Determine the structure and cross-sectional dimensions of the three-dimensional beam: Based on the type of load to be analyzed, select the cross-sectional structure of the three-dimensional beam in the three-dimensional beam model, and calculate the cross-sectional dimensions of N-1 beams.

[0092] Calculate the vibration frequency of a large floating body digital model: calculate the vibration frequency under the load type conditions to be analyzed through modal analysis.

[0093] Error analysis is performed between the vibration frequency of the large floating body digital model and the actual floating body frequency: the actual floating body frequency is the design target value, and the error results are obtained by comparing the frequency of each order of the actual floating body with the vibration frequency of the large floating body digital model. ε is the upper limit of the error. If the error result is greater than ε, the large floating body digital model needs to be further subdivided and the value of N needs to be increased; if the error result is less than or equal to ε, the design of the large floating body digital model is completed.

[0094] Determine the scale ratio of the small floating body model: Determine the scale ratio of the small floating body model based on the shortest wavelength of the water tank. The water tank is used for wave-induced vibration tests of the small floating body model. The shortest wavelength of the water tank is the shortest wavelength of the water tank wave generator.

[0095] Specifically, scaling is used to proportionally reduce a large floating body model to a small floating body model, so that the natural frequency of the small floating body model is consistent with the shortest wave in the pool, making the wave-induced vibration most obvious.

[0096] Based on the scale ratio, a small-scale floating body model and a small-scale floating body numerical model were established, and load data were obtained:

[0097] A small floating model is manufactured according to a scale. The small floating model includes a measuring beam 5. A false bottom is set up in a water tank. The false bottom is a scaled-down terrain. Wave-induced vibration test is conducted on the small floating model in the water tank to obtain the test load data of the small floating model. The load data is measured by strain sensors 6 attached to the measuring beam 5. The measurement positions are located at each cross-sectional position of the measuring beam 5.

[0098] A small floating body numerical model was established, which is similar in structure and size to the small floating body model. Modal analysis and hydroelastic response calculation were performed on the small floating body numerical model under scaled-down three-dimensional terrain conditions to obtain the calculated load of the small floating body numerical model.

[0099] Load Analysis: The calculated loads from the digital model of the small floating body and the calculated loads from the actual floating body are compared with the experimental load data after being dimensionless. The comparison is based on the experimental load data to analyze the difference between the calculated and experimental loads and verify the accuracy of the calculation results. The calculated loads for the actual floating body are obtained by modal analysis and hydroelastic response calculations of the actual floating body under known three-dimensional terrain conditions before scaling down.

[0100] The floating body test method based on three-dimensional hydroelastic analysis in this embodiment fully considers the influence of seabed topography, increases the boundary values ​​of the three-dimensional hydroelastic analysis method, and introduces the calculation load of the small floating body numerical model and the actual floating body while testing the scaled-down small floating body model. This facilitates the calibration and improvement of the segmented floating body model and the design optimization of the actual floating body mathematical model, and effectively verifies the mathematical model of the floating body structure.

[0101] Example 2:

[0102] Furthermore, such as Figure 1 As shown, in the step of determining the structure and cross-sectional dimensions of the three-dimensional beam in the floating body test method based on three-dimensional hydroelastic analysis in Example 1, the three-dimensional beam is a variable cross-section beam with N segments, and the cross-sectional structure of the three-dimensional beam is the same as that of the measuring beam 5.

[0103] When the type of load to be analyzed is vertical bending load, the cross-sectional structure of the three-dimensional beam is a hollow circular tube or a hollow rectangle;

[0104] When the loads to be analyzed are vertical and horizontal bending loads, the cross-sectional structure of the three-dimensional beam is a hollow rectangle or a hollow elliptical tube.

[0105] When the types of loads to be analyzed are vertical, horizontal bending loads and torsional loads, the cross-sectional structure of the three-dimensional beam is a hollow open rectangle or a hollow open elliptical tube.

[0106] The selection of the cross-sectional structure of the above three-dimensional beam facilitates both processing and manufacturing, and load transfer.

[0107] The three-dimensional beam is a variable cross-section beam, which can be in the form of a hollow rectangular beam. The centroid height of the variable cross-section hollow rectangular beam is consistent, and the height and width need to be changed simultaneously. This form is suitable for three load modes: vertical bending, vertical bending and horizontal bending, and vertical bending, horizontal bending and torsion.

[0108] The three-dimensional beam is a variable cross-section beam, which can adopt the cross-sectional form of a hollow circular tube beam. Variable cross-section hollow circular tube beams require a consistent centerline, thus necessitating adjustment of the base height. This form is suitable for vertical bending load modes.

[0109] The three-dimensional beam is a variable cross-section beam, which can adopt the cross-sectional form of a hollow elliptical tube beam. Typically, variable cross-section hollow elliptical tube beams require a consistent centerline, thus necessitating adjustment of the base height. This form is suitable for vertical and horizontal bending, as well as vertical bending, horizontal bending, and torsional load modes.

[0110] Furthermore, such as Figure 10 As shown, when the load to be analyzed is a vertical bending load, the three-dimensional beam adopts a hollow rectangular cross-section structure, and the structural calculation of each segment of the three-dimensional beam is performed through vertical bending modal calculation:

[0111] Assume the outer width B of the hollow rectangle j external height H j Inner width b j , inner height h j And H j =6B j h j =6b j B j =2b j Let j be a natural number from 1 to (N-1), and let I be the vertical moment of inertia of the j-th segment of the three-dimensional beam. yj :

[0112]

[0113] From equation (1.1), the inner width b of the three-dimensional beam with a hollow rectangle can be obtained. j :

[0114]

[0115] The stiffness I can be determined based on the actual cross-section of the floating body. yj The numerical value of b is calculated using equation (1.2). j This allows us to obtain all the dimensions of the hollow rectangle.

[0116] Assuming the aspect ratio of the hollow rectangle is 6, this is because the moment of inertia of the rectangle is bh. 3 / 12, so that it can be divided evenly, is less likely to have a large error in material selection. On the other hand, the aspect ratio should be greater than 5, which is related to the final simulated measurement beam frequency. It is less than 10 to take into account the poor stability of the material when it is too narrow.

[0117] like Figure 10 The figure shows N = 6, the number of segments and cross-sections, and the adhesive position of strain sensor 6 is located above the center of the variable cross-section hull beam.

[0118] By assuming the aspect ratio of the hollow rectangle, and based on the vertical moment of inertia being I... yj This tool performs dimension calculations for hollow rectangles, while also making the calculation results more accurate and convenient.

[0119] Furthermore, such as Figure 11 As shown, when the load to be analyzed is a vertical bending load, the three-dimensional beam adopts a hollow circular tube cross-section structure, and the structural calculation of each segment of the three-dimensional beam is performed through vertical bending modal calculation:

[0120] Assume the outer diameter D of the hollow circular tube j , inner diameter d j And D j =3d j Let j be a natural number from 1 to (N-1), and let I be the vertical moment of inertia of the j-th segment of the three-dimensional beam. yj :

[0121]

[0122] The inner diameter d of the hollow circular tube can be obtained from equation (2.1). j :

[0123]

[0124] Based on the stiffness of the actual floating body cross-section, I yj The numerical value d is calculated using equation (2.2). j This allows us to obtain all the dimensions of the hollow circular tube.

[0125] Assuming the ratio of the outer diameter to the inner diameter of the hollow circular tube is 3, on the one hand, because the moment of inertia of the circular tube is π×(D) 4 -d 4 The ratio is 64 / 64, which reduces the number of decimal places and makes it less likely to have large errors in material selection. On the other hand, if the ratio is too small, the measuring beam will become unstable, and if the ratio is too large, the measuring beam wall will be too thick and difficult to process.

[0126] like Figure 11 As shown, N is 6, the number of segments and cross-sections, and the adhesive position of strain sensor 6 are located at the center above the variable cross-section hull beam.

[0127] By assuming the ratio of the major and minor axes, and based on the vertical moment of inertia being I... yj To perform dimensional calculations for hollow circular tubes, and to make the calculation results more accurate and convenient.

[0128] Furthermore, such as Figure 12 As shown, when the loads to be analyzed are vertical and horizontal bending loads, the three-dimensional beam adopts a hollow rectangular cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical and horizontal bending modal calculations:

[0129] Assume the outer width B of the hollow rectangle j external height H j Inner width b j , inner height h j And Hj =α j B j h j =α j b j Let j be a natural number from 1 to (N-1), and let I be the vertical moment of inertia of the j-th segment of the three-dimensional beam. yj With horizontal moment of inertia I zj The ratio is:

[0130]

[0131] From equation (3.1), the aspect ratio parameter α of the hollow rectangle can be obtained. j :

[0132]

[0133] Based on the stiffness of the actual floating body cross-section, I yj and I zj The aspect ratio parameter α can be calculated from equation (3.2). j Furthermore, based on the vertical moment of inertia I yj With horizontal moment of inertia I zj Calculate all dimensions of the hollow rectangle.

[0134] like Figure 12 The figure shows N = 6, the number of segments and cross-sections, and the adhesive positions of strain sensor 6 are located at the center of the top and the center of the side of the variable cross-section hull beam.

[0135] By assuming the aspect ratio parameter of the hollow rectangle and using the vertical moment of inertia I... yj With horizontal moment of inertia I zj The aspect ratio parameter can be calculated from the ratio, which facilitates the calculation of the dimensions of the hollow rectangle.

[0136] Furthermore, such as Figure 13 As shown, when the loads to be analyzed are vertical and horizontal bending loads, the three-dimensional beam adopts a hollow elliptical tube cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical and horizontal bending modal calculations:

[0137] Assume the outer major axis A of the hollow elliptical tube j outer minor axis B j Inner major axis a j Inner short axis b j And A j =β j B j a j =β j b j Then the vertical moment of inertia I yj With horizontal moment of inertia I zj The ratio is:

[0138]

[0139] Based on the stiffness of the actual floating body cross-section, I yj and I zj The numerical value is based on the stiffness I of the actual ship profile. yj and I zj The aspect ratio parameter β of the hollow rectangular hull beam can be determined according to the following formula. j :

[0140]

[0141] Furthermore, based on the vertical moment of inertia I yj With horizontal moment of inertia I zj The calculation formula yields all dimensions of the hollow elliptical tube.

[0142] like Figure 13 The figure shows N = 6, the number of segments and cross-sections, and the adhesive positions of strain sensor 6 are located at the center of the top and the center of the side of the variable cross-section hull beam.

[0143] By assuming the ratio of the major and minor axes of the hollow elliptical tube, and through the vertical moment of inertia I... yj With horizontal moment of inertia I zj The ratio of the major axis to the minor axis is calculated, which facilitates the calculation of the dimensions of the hollow rectangle.

[0144] Furthermore, such as Figure 14 As shown, when the types of loads to be analyzed are vertical, horizontal bending, and torsional loads, the three-dimensional beam adopts a hollow open rectangular cross-section structure, and the number of segments and sections is as follows. Figure 14 As shown, strain sensor 6 includes strain sensor 1 631 attached to the center of the lower part of the variable cross-section hull beam, strain sensor 2 632 attached to the center of the side of the variable cross-section hull beam, and strain sensor 3 633 with two attached to each of the four sides of the variable cross-section hull beam. The opening direction of the hollow rectangular opening is located at the center of the upper part of the variable cross-section hull beam.

[0145] Assume the outer width B of the hollow rectangle j external height H j Inner width b j , inner height h j And H j =α j B j h j =α j b j If j is a natural number in the range 1 to (N-1), then the centroid vertical coordinates are:

[0146]

[0147] Among them, W j Let S be the cross-sectional area of ​​a hollow, open rectangular beam. Assuming the origin of the coordinate system is an auxiliary pole, the static moment S of the sectoral line about the pole can be calculated. ωzj Then the vertical coordinate of the torsion center is:

[0148]

[0149] Since the opening size is very small, the influence of this opening on the calculation of the vertical and horizontal moments of inertia can be ignored. Therefore, the vertical moment of inertia I of the j-th segment of the three-dimensional beam is... yj With horizontal moment of inertia I zj The ratio is:

[0150]

[0151] From equation (3.1), the aspect ratio parameter α of the hollow rectangle can be obtained. j :

[0152]

[0153] Therefore, the cross-sectional structure of a hollow open rectangle can also be obtained through vertical and horizontal bending mode calculations. Based on the stiffness of the actual floating body cross-section, I... yj and I zj The aspect ratio parameter α can be calculated from equation (3.2). j Furthermore, based on the vertical moment of inertia I yj With horizontal moment of inertia I zj Calculate all dimensions of the hollow open rectangle.

[0154] By ignoring the opening portion of the hollow rectangle, assuming the aspect ratio parameter of the hollow rectangle, and using the vertical moment of inertia I... yj With horizontal moment of inertia I zj The aspect ratio parameter can be calculated from the ratio, which facilitates the calculation of the dimensions of the hollow rectangle.

[0155] Furthermore, such as Figure 15 As shown, when the types of loads to be analyzed are vertical, horizontal bending, and torsional loads, the three-dimensional beam adopts a hollow open elliptical tube cross-section structure, and the number of segments and sections is as follows. Figure 15 As shown, strain sensor 6 includes strain sensor 1 631 attached to the center of the lower part of the variable cross-section hull beam, strain sensor 2 632 attached to the center of the side of the variable cross-section hull beam, and strain sensor 3 633 attached at 45° angles of the variable cross-section hull beam. The opening direction of the hollow rectangular opening is located at the center of the upper part of the variable cross-section hull beam.

[0156] Structural calculations were performed on each three-dimensional beam segment using vertical and horizontal bending modal calculations.

[0157] Assume the major axis A of the hollow open elliptical tube j outer minor axis B j Inner major axis a j Inner short axis b j And A j =β j B j a j =β j b j The calculation of the centroid and torsion center is the same as that of a hollow open rectangle.

[0158] Since the opening size is very small, the influence of this opening on the calculation of the vertical and horizontal moments of inertia can be ignored. Therefore, the vertical moment of inertia I... yj With horizontal moment of inertia I zj The ratio is:

[0159]

[0160] Therefore, the cross-sectional structure of a hollow open elliptical tube can also be obtained through vertical and horizontal bending mode calculations. Based on the stiffness of the actual floating body cross-section, I... yj and I zj The numerical value is based on the stiffness I of the actual ship profile. yj and I zj The aspect ratio parameter β of the hollow rectangular hull beam can be determined according to the following formula. j :

[0161]

[0162] Furthermore, based on the vertical moment of inertia I yj With horizontal moment of inertia I zj The calculation formula is used to calculate all dimensions of a hollow open elliptical tube.

[0163] Ignoring the opening portion of the hollow open elliptical tube, assume the ratio of its major and minor axes, and consider the vertical moment of inertia I. yj With horizontal moment of inertia I zj The ratio of the major axis to the minor axis is calculated, which facilitates the calculation of the dimensions of the hollow rectangle.

[0164] After calculating the dimensions of the three-dimensional beams with the above various structures, the cross-sectional dimensions of the measuring beam 5 can be obtained based on the scaling ratio of the small floating body model.

[0165] Traditionally, the variable cross-section measuring beam 5 should be designed before manufacturing. However, in practice, readily available steel sections are often used as the measuring beam 5. Although the measuring beam 5 is relatively easy to purchase, it brings cumbersome work to the design and analysis. Therefore, establishing an orderly and standardized process design method is an inevitable trend in the design and manufacturing of the variable cross-section measuring beam 5. This embodiment provides the dimensional parameter calculation formula for the vertical measuring device on the segmented ship model, which can effectively synchronize the digital model and the physical model, realizing the function of digital twin.

[0166] For floating bodies requiring hydroelastic analysis and tank testing that take into account seabed topography, this system is time-saving and labor-saving, enabling the rapid construction of a three-dimensional hydroelastic analysis floating body beam model and a measuring beam for segmented ship model testing. Different hull beam shapes can be selected as needed, and the specific shape and dimensions of the three-dimensional beam can be determined according to the corresponding formulas. A set of three-dimensional beams that can consider the mass and stiffness distribution of the floating body can be designed, serving both as a structural model for calculating vertical wave loads in three-dimensional hydroelastic analysis and as a measuring beam for designing segmented ship model tests in a tank—a dual-purpose system with higher efficiency.

[0167] Example 3:

[0168] Furthermore, such as Figures 1-3 As shown, in the scaled-down manufacturing steps of the floating body test method based on three-dimensional hydroelastic analysis in Example 1:

[0169] The structure of the small floating body model is as follows: it includes an outer shell 1, which is divided into N sections. Multiple rib frames 11 are set inside the outer shell 1. The multiple rib frames 11 are arranged at intervals along the length of the ship. A base 4 is installed on the upper end of each rib frame 11. It also includes the measuring beam 5, which is fixedly connected to the rib frame 11 through the base 4. The two ends of the upper part of a single rib frame 11 are connected by a crossbeam 12. The middle part of the crossbeam 12 is fixedly connected to the lower end of the rib frame 11 through a column 3.

[0170] Specifically, the base 4 is installed on the deck surface of the outer shell 1. To ensure a stable connection between the base 4 and the outer shell 1 and to completely transfer the load, the base 4 adopts a metal structure and is welded to the crossbeam 12 of the segmented ship model 1. The hull beam 5 is a continuous metal component that characterizes the vertical bending characteristics of the floating structure. Since the stiffness of the floating structure is inconsistent along the length of the ship, a variable cross-section measuring beam 5 is often used. This variable cross-section measuring beam 5 needs to bear the longitudinal load of the floating structure and is often welded. The base 4 is generally at the same vertical height as the center of the cross-section of the variable cross-section measuring beam 5. The base 4 is the supporting and fixing structure for installing the variable cross-section measuring beam 5, and its strength and stiffness should be greater than those of the hull beam 5. A strain sensor 6 is attached to the variable cross-section measuring beam 5. The strain sensor 6 is a strain gauge that uses a dynamic acquisition method to test the strain of the measuring beam 5 when it bends vertically, and then derives the vertical bending load.

[0171] A mass loading device 2 is installed on the rib frame 11;

[0172] Mass loading device 2 is used to adjust the mass distribution of the small floating body model;

[0173] The number of mass loading devices 2 inside the outer shell 1 of each section is four, two on each of the port and starboard sides.

[0174] A small floating body model is used to simulate the weight distribution of an actual ship. Since the outer hull 1 contains no other structures besides the transverse frame structure composed of rib frames 11 and crossbeams 12 (where rib frames 11, crossbeams 12, and columns 3 are all made of steel or aluminum and welded together, while being attached to the outer hull 1 by adhesive or riveting), the weight center of gravity of the small floating body model is crucial to the accuracy of the simulation and the verification of the calculation's rationality. During the design and preparation of the small floating body model, its weight center of gravity often cannot be effectively simulated. It is usually manually adjusted using weight plates. On the one hand, manually changing the position of the weight plates inevitably introduces errors, leading to differences between the pre-test and numerical model values. On the other hand, even if the adjusted weight plate position is recorded, unavoidable errors will still occur during measurement. In particular, the measurement beam 5 of the segmented ship model using three-dimensional hydroelastic analysis and the measurement beam of the segmented ship model are inconsistent in terms of operation. In such cases, there is no way to compare them, and the numerical model must be rebuilt according to the ship model, resulting in rework, which is time-consuming and laborious. Therefore, the method and structure of adjusting the center of gravity by loading mass through the mass loading device 2 are further optimized. The further scheme is as follows.

[0175] Furthermore, such as Figures 3-4 As shown, the structure of the mass loading device 2 is as follows: it includes a vertical rod 21, a lower base 22 is provided at the lower end of the vertical rod 21, a first weight set 23 is placed on the lower base 22, an upper base 24 is provided at the upper part of the vertical rod 21 and a second weight set 25 is placed on the upper base 24, and the relative height of the vertical rod 21 relative to the crossbeam 12 is fixed and adjusted by the lifting locking device 26;

[0176] During the process of manufacturing a small floating model according to a scale:

[0177] Based on the scale ratio and the mass of each segment of the large floating body digital model By considering the center of gravity, the overall mass M of each segment of the small floating model can be obtained. i And the overall center of gravity (x) of each segment of the small floating model. ic y ic , z ic ).

[0178] Specifically, the mass of each segment of the large floating digital model The center of gravity is consistent with the mass distribution of the actual floating body; the positions of the first weight group 23 and the second weight group 25 relative to the vertical rod 21 can be fixed, such as being positioned and installed at the upper end of the vertical rod 21, or the position of the second weight group 25 on the upper base 24 relative to the crossbeam 12 remains unchanged when the height of the lower base 22 is adjusted with the vertical rod 21.

[0179] After constructing the main structure of each small floating body model, the mass m of each section was obtained by weighing it. i0 The center of gravity of the main structure of each small floating model is measured as (x i0 y i0 , z i0 Each small floating body model consists of a single segmented outer shell 1 and its internal rib frame 11, crossbeam 12 and column 3.

[0180] Then, a mass loading device 2 is installed on each small floating model section, and the total weight of the weights on the four vertical rods 21 is adjusted to be m. i1 m i2 m i3 m i4 The corresponding centroids are (x i1 y i1 , z i1 ), (x i2 y i2 , z i2 ), (x i3 y i3 , z i3 ), (x i4 y i4 , z i4 ), its centroid is (x ic y ic , z ic This yields the following system of equations:

[0181]

[0182] The total mass m of the first weight group 23 and the second weight group 25 on each vertical rod 21, calculated based on the above equations, is... i1 m i2 m i3 m i4 .

[0183] Specifically, since the longitudinal and lateral positions of the four vertical members 21 are fixed and known, x i1 x i2 x i3 x i4 and y i1 yi2 y i3 y i4 It is known. Also, since the weights are of standard size, therefore z... i1 , z i2 , z i3 , z i4 respectively with m i1 m i2 m i3 m i4 There exists a fixed linear proportional relationship, i.e., z i1 , z i2 , z i3 , z i4 They are m i1 m i2 m i3 m i4 A fixed coefficient. Additionally, the mass m of the segmented ship model. i0 and its center of gravity (x) i0 y i0 , z i0 and overall quality M i and its center of gravity (x) ic y ic , z ic It is also known that, therefore, solving the four equations simultaneously can completely solve for the mass m of the weights at the four vertical rods at point 21. i1 m i2 m i3 m i4 Thus, z was obtained. i1 , z i2 , z i3 , z i4 The value.

[0184] Furthermore, such as Figures 5-6 As shown, the lifting and locking device 26 has the following structure: it includes a gear 267 rotatably mounted below the crossbeam 12 via a support column 266; one side of the support column 266 is the vertical rod 21; the middle of the vertical rod 21 is provided with a single-sided tooth structure 268 that meshes with the gear 267; a rotating shaft 262 is mounted on the crossbeam 12 on the other side of the support column 266; the middle of the rotating shaft 262 is provided with a screw part 263; the screw part 263 meshes with the gear 267; the upper end of the rotating shaft 262 is rotatably connected to the crossbeam 12; the lower end of the rotating shaft 262 is supported and limited by a support plate 265 installed inside the rib frame 11; the length directions of the rotating shaft 262 and the vertical rod 21 are both vertical; and a hand crank 261 is provided at the upper end of the rotating shaft 262.

[0185] Based on the total mass m of the first weight group 23 and the second weight group 25i1 m i2 m i3 m i4 Vertical coordinate z of the center of gravity i1 , z i2 , z i3 , z i4 The specific weights on the first weight group 23 and the second weight group 25 are adjusted in position. At the same time, the screw part 263 is rotated by turning the hand crank 261, and then the rotation is transmitted to the vertical rod 21 through the gear part 267, so that the vertical rod 21 moves up and down. After adjusting the overall height of the first weight group 23 and the second weight group 25, the vertical coordinate position of the center of gravity is satisfied. Then, the braking structure 264 is used to fix the rotation position of the rotating shaft 262 relative to the crossbeam 12.

[0186] Traditional methods for adjusting the mass and inertia of segmented ship models often involve manually moving weights, which is inaccurate and limited by the internal structure of the small floating model. This embodiment uses a mass loading device 2, which can accurately calculate the mass and position of the weights at each segment from the initial design stage, making the adjustment of the ship model's mass and inertia more precise.

[0187] Since the vertical, horizontal, and torsional loads of the floating body are related to the mass and stiffness distribution of the floating body structure, the establishment of a three-dimensional beam model of the floating body is the key to analyzing external loads and conducting segmented model tests. The method in this embodiment can combine multiple construction parameters such as a small floating body model, mass loading device 2, adjustment of the orthocenter, base, parameter design of the variable cross-section hull beam, and arrangement of strain sensors to form a set of experimental methods suitable for three-dimensional hydroelasticity analysis and floating body model tests in a simulated seabed topography pool.

[0188] The method in this embodiment has the advantage of precisely adjusting the center of gravity of the small floating model, and has high accuracy. By using the mass loading device 2 with a center-of-gravity adjustment function, and providing the weight ratio according to the formula, the practicality of this device in adjusting the center of gravity position is largely demonstrated.

[0189] In this embodiment, the transmission structure between the screw portion 263, the gear component 267, and the single-sided tooth structure 268 can be as follows: Figure 6 As shown, gear component 267 is an external gear, which can be a helical gear, a single-sided tooth structure, or a helical rack structure; it can also be as shown in the image. Figure 6 The gear component 267 shown is a pair of external gears, namely a first external gear 2671 and a second external gear 2672 that are concentrically and rotatably mounted on the support column 266. The transmission structure of the first external gear 2671 and the screw part 263 can be a worm gear structure, the second external gear 2672 can be a spur gear, and the single-sided tooth structure 268 is located in the spur rack structure that meshes with the second external gear 2672.

[0190] Furthermore, such as Figures 8-9 As shown, the braking structure 264 includes a plug 2642 and a first insertion hole 2643 disposed on the upper surface of the crossbeam 12. The upper end face of the rotating shaft 262 is provided with multiple second insertion holes 2641, which are evenly distributed along the circumference of the rotating shaft 262. When the vertical rod 21 moves vertically into position, one end of the plug 2642 is inserted into the first insertion hole 2643, and the other end of the plug 2642 is inserted into the second insertion hole 2641 when the plug 2642 is aligned, thus fixing the rotational orientation of the rotating shaft 262 relative to the crossbeam 12. Specifically, the plug 2642 is made of sheet-type bent hook metal, and the distribution density of the multiple second insertion holes 2641 meets the vertical adjustment accuracy of the vertical rod 21.

[0191] The lifting locking device 26 and the adjustment process for the specific center of gravity position are as follows:

[0192] Turning the hand crank 261 clockwise causes the screw 263 to rotate clockwise, which in turn causes the gear 267 to rotate clockwise. The single-sided tooth structure 268 moves downward, which in turn causes the vertical rod 21 to move the lower base 22 downward. The position of the upper base 24 can be adjusted according to the specific situation. The upper base 24 and the second weight on the upper base 24 can be placed directly on the crossbeam 12.

[0193] The hand crank 261 is turned counterclockwise, which drives the screw part 263 to rotate counterclockwise, which drives the gear part 267 to rotate counterclockwise, and the single-sided tooth structure 268 moves upward. In turn, the vertical rod 21 drives the lower base 22 to move upward. The position of the upper base 24 is adjusted according to the specific situation. The upper base 24 and the second weight on the upper base 24 can be placed directly on the crossbeam 12.

[0194] When the hand crank 261 is rotated to adjust the target position of the first weight group 23, the other end of the plug 2642 is inserted into the second socket 2641 when the plug 2642 is aligned, thereby fixing the rotational orientation of the rotating shaft 262 relative to the crossbeam 12.

[0195] The adjustment ends when the overall height of the first weight group 23 and the second weight group 25 satisfies the vertical coordinate position of the center of gravity.

[0196] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A floating body test method based on three-dimensional hydroelastic analysis, characterized in that: Includes the following steps, Obtain the topography of the large floating body deployment location: Conduct on-site measurements of the three-dimensional topography data of the sea area where the actual floating body is deployed, including wave conditions and seabed topography; Large Floating Body Digital Model Design: Under the condition of the terrain at the deployment location, a three-dimensional beam model of the large floating body is designed through three-dimensional hydroelastic analysis. First, the actual floating body profile is input to establish the outer shell of the large floating body digital model. Then, the large floating body digital model is divided along the length direction. N Segment, initial state is N ≥2, and then obtain the mass of each segment structure using finite element software. and the stiffness of each section I j , i =1~ N The natural numbers in the middle, j =1~( N-1 The natural numbers in the section; the section is located on the three-dimensional beam at the segmentation point. I j Including torsional moment of inertia I xj Vertical moment of inertia I yj Horizontal moment of inertia I zj ; Determine the structure and cross-sectional dimensions of the 3D beam: Based on the type of load to be analyzed, select the cross-sectional structure of the 3D beam in the 3D beam model and calculate... N-1 The cross-sectional dimensions of each; Calculate the vibration frequency of a large floating body digital model: calculate the vibration frequency under the load type to be analyzed through modal analysis; Error analysis is performed between the vibration frequency of the large floating body digital model and the actual floating body frequency. The actual floating body frequency is the design target value. The error results are obtained by comparing each order frequency of the actual floating body with the vibration frequency of the large floating body digital model. ε is the upper limit of the error. If the error result is greater than ε, the large floating body digital model needs to be further subdivided and increased. N The numerical value; if the error result is less than or equal to ε, the large floating body digital model design is completed; Determine the scale ratio of the small floating body model: Determine the scale ratio of the small floating body model based on the shortest wavelength of the water tank. The water tank is used for wave-induced vibration tests of the small floating body model. The shortest wavelength of the water tank is the shortest wavelength of the water tank wave generator. Based on the scale ratio, a small-scale floating body model and a small-scale floating body numerical model were established, and load data were obtained: A small floating model is manufactured according to the scale ratio. The small floating model includes a measuring beam (5). A false bottom is built in the pool. The false bottom is the scaled-down terrain. Wave-induced vibration test is conducted on the small floating model in the pool to obtain the test load data of the small floating model. A small floating body numerical model was established, which is similar in structure and size to the small floating body model. Modal analysis and hydroelastic response calculation were performed on the small floating body numerical model under scaled-down three-dimensional terrain conditions to obtain the calculated load of the small floating body numerical model. Load analysis: The calculated loads of the small floating body digital model and the actual floating body are compared with the experimental load data after being dimensionless. The comparison is based on the experimental load data to analyze the difference between the calculated load and the experimental load and to verify whether the calculation results are correct. The x-axis points in the direction of the ship's length, the y-axis points in the direction of the ship's width, and the z-axis points vertically upwards.

2. The floating body test method based on three-dimensional hydroelastic analysis as described in claim 1, characterized in that: The three-dimensional beam is a variable cross-section beam with N segments, and its cross-sectional structure is the same as that of the three-dimensional beam and the measuring beam (5). When the type of load to be analyzed is vertical bending load, the cross-sectional structure of the three-dimensional beam is a hollow circular tube or a hollow rectangle; When the loads to be analyzed are vertical and horizontal bending loads, the cross-sectional structure of the three-dimensional beam is a hollow rectangle or a hollow elliptical tube. When the types of loads to be analyzed are vertical, horizontal bending loads and torsional loads, the cross-sectional structure of the three-dimensional beam is a hollow open rectangle or a hollow open elliptical tube.

3. The floating body test method based on three-dimensional hydroelastic analysis as described in claim 2, characterized in that: When the load to be analyzed is a vertical bending load, the three-dimensional beam adopts a hollow rectangular cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical bending modal calculations: Assuming the outer width of the hollow rectangle B j , Wai Gao H j Inner width b j , inner high h j ,and H j =6 B j , h j =6 b j , B j =2 b j , j =1~( N-1 The natural numbers in the given information, the vertical moment of inertia of the j-th segment of the three-dimensional beam is: I yj : （1.1） The inner width of the hollow rectangular three-dimensional beam can be obtained from equation (1.1) b j : （1.2） The stiffness can be determined based on the actual cross-section of the floating body. I yj The numerical value is calculated using equation (1.2). b j This allows us to obtain all the dimensions of the hollow rectangle.

4. The floating body test method based on three-dimensional hydroelastic analysis as described in claim 2, characterized in that: When the load to be analyzed is a vertical bending load, the three-dimensional beam adopts a hollow circular tube cross-section structure, and the structural calculation of each segment of the three-dimensional beam is performed through vertical bending modal calculation: Assuming the outer diameter of the hollow circular tube D j , inner diameter d j ,and D j =3 d j , j =1~( N-1 The natural numbers in the given information, the vertical moment of inertia of the j-th segment of the three-dimensional beam is: I yj : （2.1） The inner diameter of the hollow circular pipe can be obtained from equation (2.1) d j : （2.2） The stiffness of the actual floating body section is known I yj The numerical value is calculated from equation (2.2) d j All dimensions of the hollow circular tube are obtained.

5. The floating body test method based on three-dimensional hydroelastic analysis as described in claim 2, characterized in that: When the load types to be analyzed are vertical and horizontal bending loads, or vertical, horizontal bending and torsional loads, the three-dimensional beam adopts a hollow rectangular cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical and horizontal bending modal calculations: Assuming the outer width of the hollow rectangle B j , Wai Gao H j Inner width b j , inner high h j ,and H j = B j , h j = b j , j =1~( N-1 The natural number in ), the vertical moment of inertia of the j-th segment of the three-dimensional beam. I yj With horizontal moment of inertia I zj The ratio is: （3.1） The aspect ratio parameter of the hollow rectangle can be obtained from equation (3.1) : （3.2） Based on the stiffness of the actual floating body cross-section, it can be known that I yj and I zj The aspect ratio parameter can be calculated using equation (3.2). Furthermore, based on the vertical moment of inertia I yj With horizontal moment of inertia I zj Calculate all dimensions of the hollow rectangle.

6. The floating body test method based on three-dimensional hydroelastic analysis as described in claim 2, characterized in that: When the load types to be analyzed are vertical and horizontal bending loads, or vertical, horizontal bending and torsional loads, the three-dimensional beam adopts a hollow elliptical tube cross-section structure, and structural calculations are performed on each segment of the three-dimensional beam through vertical and horizontal bending modal calculations: Assuming the outer major axis of the hollow elliptical tube A j outer short axis B j Inner long axis a j inner short axis b j ,and A j = B j , a j = b j Then the vertical moment of inertia I yj With horizontal moment of inertia I zj The ratio is: （4.1） Based on the stiffness of the actual floating body cross-section, it can be known that I yj and I zj The value is based on the stiffness of the actual ship profile. I yj and I zj The aspect ratio parameter of the hollow rectangular hull beam can be determined according to the following formula. : （4.2） Furthermore, based on the vertical moment of inertia I yj With horizontal moment of inertia I zj The calculation formula yields all dimensions of the hollow elliptical tube.

7. A method of testing a floating body based on three-dimensional hydroelastic analysis according to claim 1, characterized in that: The structure of the small floating body model is as follows: it includes an outer shell (1), which is divided into N sections. Multiple rib frames (11) are set inside the outer shell (1). The multiple rib frames (11) are arranged at intervals along the length of the ship. A base (4) is installed on the upper end of each rib frame (11). It also includes the measuring beam (5). The measuring beam (5) is fixedly connected to the rib frame (11) through the base (4). The upper two ends of a single rib frame (11) are connected by a crossbeam (12). The middle part of the crossbeam (12) is fixedly connected to the lower end of the rib frame (11) through a column (3). A mass loading device (2) is installed on the rib frame (11). The mass loading device (2) is used to adjust the mass distribution of the small floating body model; The number of mass loading devices (2) inside the outer shell (1) of each segment is four, two on each side.

8. A method of testing a floating body based on three-dimensional hydroelastic analysis according to claim 7, characterized in that: The structure of the mass loading device (2) is as follows: it includes a vertical rod (21), a lower base (22) is provided at the lower end of the vertical rod (21), a first weight group (23) is placed on the lower base (22), an upper base (24) is provided at the upper part of the vertical rod (21) above the crossbeam (12), a second weight group (25) is placed on the upper base (24), and the relative height of the vertical rod (21) relative to the crossbeam (12) is fixed and adjusted by a lifting locking device (26); During the process of manufacturing a small floating model according to a scale: Based on the scale ratio and the mass of each segment of the large floating body digital model By determining the center of gravity, the overall mass of each segment of the small floating model can be obtained. And the overall center of gravity of each segment of the small floating model ( , , ), After constructing the main structure of each small floating body model, the mass of each section was obtained by weighing it. The center of gravity of the main structure of each small floating model is measured to be ( , , ), Then, a mass loading device (2) is installed on each small floating model, and the total weights of the weights on the four vertical rods (21) are adjusted to be as follows: , , , The corresponding centers of gravity are ( , , (), , , (), , , (), , , Its center of gravity is ( , , The following system of equations is obtained: The total mass of the first weight group (23) and the second weight group (25) on each vertical rod (21) is calculated based on the above equations. , , , .

9. A method of testing a floating body based on three-dimensional hydroelastic analysis according to claim 8, characterized in that: The lifting locking device (26) has the following structure: it includes a gear (267) rotatably mounted below the crossbeam (12) via a support column (266). One side of the support column (266) is the vertical rod (21), and the middle of the vertical rod (21) is provided with a single-sided tooth structure (268) that meshes with the gear (267). A rotating shaft (262) is mounted on the crossbeam (12) on the other side of the support column (266). A screw section (263) is provided in the middle, which meshes with the gear component (267). The upper end of the rotating shaft (262) is rotatably connected to the crossbeam (12). The lower end of the rotating shaft (262) is supported and limited by a support plate (265) installed inside the rib frame (11). The length directions of the rotating shaft (262) and the vertical rod (21) are both vertical. A hand crank handle (261) is provided at the upper end of the rotating shaft (262). Based on the total mass of the first weight group (23) and the second weight group (25) , , , Vertical coordinates of the center of gravity , , , The specific weights on the first weight group (23) and the second weight group (25) are adjusted. At the same time, the screw part (263) is rotated by turning the hand crank (261), and the rotation is transmitted to the vertical rod (21) through the gear part (267), so that the vertical rod (21) moves up and down. After adjusting the overall height of the first weight group (23) and the second weight group (25), the vertical coordinate position of the center of gravity is satisfied. Then, the braking structure (264) is used to fix the rotation position of the rotating shaft (262) relative to the crossbeam (12).

10. A method of testing a floating body based on three-dimensional hydroelastic analysis according to claim 9, characterized in that: The braking structure (264) includes a plug (2642) and a first insertion hole (2643) disposed on the upper surface of the crossbeam (12). The upper end face of the rotating shaft (262) is provided with a plurality of second insertion holes (2641). The plurality of second insertion holes (2641) are evenly distributed along the circumferential direction of the rotating shaft (262). When the vertical rod (21) moves up and down into place, one end of the plug (2642) is inserted into the first insertion hole (2643), and the other end of the plug (2642) is inserted into the second insertion hole (2641) when the plug (2642) is aligned, thereby fixing the rotational orientation of the rotating shaft (262) relative to the crossbeam (12).

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