A Finite Element Calculation Method for Tank Displacement of a Very Large Liquefied Gas Carrier

Abstract

This invention relates to a finite element method for calculating the displacement of a liquid tank on a very large liquefied gas carrier. The method includes: meshing a three-dimensional model of the liquid tank; setting the material properties of the element meshes; adjusting the material density; performing model diagnosis on the adjusted finite element three-dimensional model; placing rotating supports at the bottom of the liquid tank's strong structure, with the rotating supports modeled using Gap elements; coupling the liquid tank and the modular vehicle assembly node by Rigid elements; performing a tilting analysis of the liquid tank based on the arrangement of the modular vehicle assembly to determine if the liquid tank has a tilting risk, and adjusting the modular vehicle assembly arrangement if so; performing a stress analysis of the rotating supports, and adjusting the supports if the rotating supports have excessive bearing capacity and may fracture, or if the stress and strain of the liquid tank are excessive. This invention utilizes finite element calculations for tilting analysis and support stress analysis during displacement, avoiding tilting during actual displacement, preventing damage to the liquid tank and modular vehicle assembly, and improving the overall safety of the liquid tank displacement.

Description

Technical Field

[0001] This invention relates to the field of liquefied gas carrier construction, and specifically to a finite element method for calculating the displacement of liquid tanks in a very large liquefied gas carrier. Background Technology

[0002] In the construction of liquefied gas carriers, to achieve efficient construction of independent liquefied gas tank sections for very large liquefied gas carriers, self-propelled modular transporters (SPMTs) are used to relocate the entire tank. This allows the construction of the tank insulation to be carried out in non-core shipyard areas, reducing the use of cranes and improving construction efficiency. Very large liquefied gas carriers are fully refrigerated vessels, also known as cryogenic ballast ships, with tank capacities generally exceeding 50,000 cubic meters.

[0003] During the relocation of the entire liquid tank, due to the high center of gravity of the liquid tanks on the ultra-large liquefied gas carrier and the fact that the tanks are mostly thin-plate structures, the modular vehicle assembly is subjected to the weight of the liquid tank itself, and the liquid tank is subjected to the support reaction force of the vehicle assembly. During the movement, the center of gravity of the liquid tank shifts left and right, which leads to a significant risk of overturning during transportation. In order to protect the vehicle assembly's platform, a certain number of rotating supports need to be placed between the modular vehicle assembly and the strong frame structure at the bottom of the liquid tank. The different placement positions of the rotating supports will also affect the structural safety of the liquid tank. During the relocation, the rotating supports may be damaged due to their small force projection area, which may be insufficient to support the weight of the entire liquid tank being moved. This could lead to the breakage of the bottom structure of the liquid tank and the platform of the modular vehicle assembly, causing a serious safety accident. Summary of the Invention

[0004] To avoid safety accidents during the relocation of liquid tanks, this invention provides a finite element calculation method for the relocation of liquid tanks on ultra-large liquefied gas carriers. A finite element model of the liquid tank is established using SFRT (Ship-Right Fast track, SRFT) software, and finite element calculations are performed on the relocation of the liquid tank. The structural strength and load-bearing capacity of the rotating piers during the relocation are analyzed, and adjustments are made based on the finite element calculation results to avoid safety accidents during the actual relocation process.

[0005] The technical objective of this invention is achieved through the following technical solution:

[0006] A finite element method for calculating the displacement of liquid tanks in a very large liquefied gas carrier, the method comprising:

[0007] Step 1: Create a 3D model of the liquid tank;

[0008] Step 2: Mesh the 3D model of the liquid tank using finite element analysis software to form a finite element 3D model;

[0009] Step 3: Set the material properties of the corresponding unit mesh according to the actual material properties of the liquid tank, eliminate overlapping points, and simplify the outfitting components inside the liquid tank;

[0010] Step 4: Adjust the material density of models with different mesh unit sizes so that the weight and center of gravity of the finite element 3D model are close to the actual weight and center of gravity of the liquid tank, with the deviation controlled within 5%.

[0011] Step 5: Perform model diagnosis on the adjusted finite element 3D model and modify any abnormal points;

[0012] Step 6: Place a rotating support at the bottom of the liquid tank in the finite element 3D model. The rotating support is modeled using Gap elements, and the stiffness coefficient of the Gap elements is... Where E is the elastic modulus of the rotating pier, A is the projected force-bearing area of ​​the rotating pier, and H is the height of the rotating pier;

[0013] Step 7: Couple the liquid tank and the modular vehicle assembly finite element models of the finite element 3D model with the rotating pier Gap element through Rigid rigid element bodies.

[0014] Step 8: The modular vehicle groups communicate with each other via bus signals to achieve coordination and synchronization between the modular vehicle groups, and the whole vehicle is raised and lowered through height sensors;

[0015] Step 9: Perform a tilting analysis on the layout of the modular vehicle group's liquid tanks to determine whether the liquid tanks pose a risk of tilting.

[0016] Step 10: Perform a stress analysis on the rotating pier and calculate the maximum shear force and negative bending moment of the rotating pier;

[0017] Step 11: If the liquid tank does not have the risk of overturning, and the maximum shear force and negative bending moment of the rotating pier are less than the allowable shear force and allowable negative bending moment of the modular vehicle assembly, then constrain the vertical degree of freedom of the upper and lower nodes of the Gap unit and all degrees of freedom of the bottom of the modular vehicle assembly. Set the gravity acceleration to a scaling factor of 1.2, and apply the reaction force in the form of surface load in the lifting area of ​​the rotating pier of the modular vehicle assembly.

[0018] If the rotating pier breaks due to its load-bearing capacity exceeding its own safety range, or if the stress and strain of the liquid tank exceed the set safety threshold, proceed to step 6 to readjust the size, number, and projected force-bearing area of ​​the rotating pier until the load-bearing capacity of the rotating pier meets its own safety range.

[0019] Furthermore, in step 2, when performing mesh generation, the mesh cell size is divided according to the rib spacing × longitudinal rib spacing.

[0020] Furthermore, in step 9, when performing an overturning analysis on the arrangement of the liquid tanks on the modular vehicle group, the wind load force, braking force, dynamic load force, ramp force, and centrifugal force are calculated when the liquid tanks are moved on the modular vehicle group. The resultant external force of the wind load force, braking force, dynamic load force, ramp force, and centrifugal force is calculated. Based on the resultant external force and the weight of the liquid tanks themselves, the overturning moment and anti-overturning moment of the entire displacement are calculated. If the overturning moment is greater than the anti-overturning moment, there is a risk of overturning.

[0021] Furthermore, when calculating wind load, braking force, dynamic load, and slope force, calculations are performed on the liquid tank in two horizontal directions, X and Y, which are perpendicular to each other. One direction is designated as the forward direction of the modular vehicle group, and centrifugal force is calculated in the other direction.

[0022] Furthermore, the length, width, and height of the liquid tank are L, W, and H, respectively. The X direction is perpendicular to the height and width directions, and the Y direction is perpendicular to the length and height directions. The X direction is designated as the forward direction of the modular vehicle group.

[0023] Wind load F in the X direction 1x =C×Kh×q×(W×H)×μ;

[0024] Wind load F in the Y direction 1Y =C×Kh×q×(L×H)×μ;

[0025] Where C is the wind load shape coefficient, Kh is the wind pressure height variation coefficient, q is the basic wind pressure, and μ is the wind vibration coefficient.

[0026] Furthermore, the braking force F in the X direction 2x =G0×i 2x Braking force F in the Y direction 2Y =G0×i 2y , where i 2x and i 2y These are the braking accelerations of the modular vehicle in the X and Y directions, respectively, and G0 is the weight of the liquid tank.

[0027] Dynamic load force F in the X direction 3x =G0×i 3x Dynamic load force F in the Y direction 3Y =G0×i 3y , where i 3x and i 3y These are the moving accelerations of the modular vehicle group in the X direction and the moving accelerations in the Y direction, respectively.

[0028] Force F on the ramp in the X direction 4x =G0×i 4x The slope in the Y direction is subjected to force F. 4Y =G0×i4y , where i 4x and i 4y These are the ramp angles in the X and Y directions, respectively.

[0029] Furthermore, centrifugal force Where G0 is the weight of the liquid tank, V is the turning speed of the modular vehicle group, and R is the turning radius of the modular vehicle group.

[0030] Furthermore, when calculating the net external force, the net external force F in the X direction is calculated separately. 0x The resultant external force F in the Y direction 0Y ,

[0031] F 0x =F 1x +F 2x +F 3x +F 4x ,

[0032] F 0Y =F 1Y +F 2Y +F 2Y +F 4Y +F 5Y .

[0033] Compared to existing technologies, the advantages of this invention are that it utilizes finite element analysis to perform displacement and overturning risk analysis and pier stress analysis on modular vehicle groups arranged at the bottom of the liquid tank. If there is a risk of overturning, the arrangement of the modular vehicle groups can be adjusted to prevent the liquid tank from overturning during the actual displacement process. By analyzing the stress on the piers, the size, number, and projected stress area of ​​the piers can be adjusted to prevent damage to the rotating piers themselves, which could damage the liquid tank and the modular vehicle groups, thus improving the overall safety of the liquid tank displacement. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the arrangement of the bottom module vehicle group and rotating support in the liquid tank in this invention.

[0035] Figure 2 This is a schematic diagram of the train axle numbering in this invention.

[0036] In the picture:

[0037] 1. Liquid tank; 2. Modular vehicle assembly; 3. Rotating support; 4. Anti-overturning lever arm. Detailed Implementation

[0038] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0039] A finite element method for calculating the displacement of liquid tanks in a very large liquefied gas carrier, the method comprising:

[0040] Step 1: Create a 3D model of the liquid tank using CATIA (Computer Aided Three-dimensional Interactive Application) software;

[0041] Step 2: Mesh the 3D model of the liquid tank using finite element analysis software to form a finite element 3D model. When meshing, the outer plate uses plate shell elements, and the strong frame and other components use beam elements. The mesh element size of the finite element 3D model of the liquid tank is divided according to the rib spacing × longitudinal rib spacing. The mesh is locally refined at some special structural locations such as openings.

[0042] Step 3: Set the material properties of the corresponding element mesh according to the actual material properties of the liquid tank, and eliminate overlapping points to avoid affecting the finite element calculation results. Preferably, without affecting the calculation, the outfitting components inside the liquid tank can be simplified to improve calculation efficiency.

[0043] Step 4: The simplification of the internal outfitting components caused the weight and center of gravity of the finite element 3D model to deviate from the actual weight and center of gravity. Therefore, the material density of the model with different mesh element sizes was adjusted so that the weight and center of gravity of the finite element 3D model were close to the actual weight and center of gravity of the liquid tank, and the deviation was controlled within 5%.

[0044] Step 5: Perform model diagnosis on the adjusted finite element 3D model using DIAG (Model Diagnosis, DIAG), modify any abnormal points, and continue until the finite element 3D model meets the requirements.

[0045] Step 6: Place a rotating support at the bottom of the liquid tank in the finite element 3D model. The rotating support is modeled using Gap elements, and the stiffness coefficient of the Gap elements is... Where E is the elastic modulus of the rotating pier, A is the projected force-bearing area of ​​the rotating pier, and H is the height of the rotating pier;

[0046] Step 7: Couple the liquid tank and the modular vehicle assembly finite element models of the finite element 3D model with the rotating pier Gap element through Rigid rigid element bodies to ensure continuous and uninterrupted force transmission, forming a closed loop.

[0047] Step 8: The modular vehicle groups communicate via bus signals to achieve coordination and synchronization. Height sensors enable the raising and lowering of the entire vehicle, facilitating both hard and soft paralleling, as well as longitudinal or lateral paralleling. The modular vehicle groups are preferably symmetrical about the port and starboard sides to minimize tank deformation.

[0048] Step 9: Perform a tilting analysis on the layout of the modular vehicle group's liquid tanks to determine whether the liquid tanks pose a risk of tilting.

[0049] When performing an overturning analysis of the liquid tank's position on the modular vehicle group, calculate the wind load, braking force, dynamic load, ramp force, and centrifugal force when the liquid tank moves on the modular vehicle group. Calculate the resultant external force of the wind load, braking force, dynamic load, ramp force, and centrifugal force. Based on the resultant external force and the weight of the liquid tank itself, calculate the overturning moment and anti-overturning moment of the entire displacement. If the overturning moment is greater than the anti-overturning moment, there is a risk of overturning. In this case, adjust the position of the modular vehicle group and repeat step 9.

[0050] When calculating wind load, braking force, dynamic load, and slope force, the liquid tank is calculated in two horizontal directions, X and Y, which are perpendicular to each other. One direction is designated as the forward direction of the modular vehicle group, and the centrifugal force is calculated in the other direction.

[0051] The length, width, and height of the liquid tank are L, W, and H, respectively. The X direction is perpendicular to the height and width directions, and the Y direction is perpendicular to the length and height directions. The X direction is specified as the forward direction of the modular vehicle group (the Y direction can also be specified as the forward direction of the modular vehicle group, in which case the centrifugal force is calculated in the X direction accordingly).

[0052] Wind load F in the X direction 1x =C×Kh×q×(W×H)×μ;

[0053] Wind load F in the Y direction 1Y =C×Kh×q×(L×H)×μ;

[0054] Where C is the wind load shape coefficient, Kh is the wind pressure height variation coefficient, q is the basic wind pressure, W×H is the windward area in the X direction, L×H is the windward area in the Y direction, and μ is the wind vibration coefficient.

[0055] The basic wind pressure q = 0.5 × ρ × V, where ρ is the air density and V is the wind speed.

[0056] Braking force F in the X direction 2x =G0×i 2x Braking force F in the Y direction 2Y =G0×i 2y , where i 2x and i 2y These are the braking accelerations of the modular vehicle in the X and Y directions, respectively, and G0 is the weight of the liquid tank.

[0057] Dynamic load force F in the X direction 3x =G0×i 3x Dynamic load force F in the Y direction 3Y=G0×i 3y , where i 3x and i 3y These are the moving accelerations of the modular vehicle group in the X direction and the moving accelerations in the Y direction, respectively.

[0058] Force F on the ramp in the X direction 4x =G0×i 4x The slope in the Y direction is subjected to force F. 4Y =G0×i 4y , where i 4x and i 4y These are the slopes in the X and Y directions, respectively.

[0059] centrifugal force Where G0 is the weight of the liquid tank, V is the turning speed of the modular vehicle group, and R is the turning radius of the modular vehicle group.

[0060] When calculating the net external force, calculate the net external force F in the X direction separately. 0x The resultant external force F in the Y direction 0Y ,

[0061] F 0x =F 1x +F 2x +F 3x +F 4x ,

[0062] F 0Y =F 1Y +F 2Y +F 3Y +F 4Y +F 5Y .

[0063] As a preferred option, the calculation of the static friction force f between the liquid tank and the modular vehicle group is also included, f = G0 × u0, where u0 is the static friction coefficient. If f is greater than the net external force and the braking force, the liquid tank will not slip during the movement of the modular vehicle group.

[0064] The overturning moment and anti-overturning moment during displacement are calculated based on the net external force received by the liquid tank and the weight of the liquid tank itself. Overturning moment = net external force × overall center of gravity height during displacement; anti-overturning moment = liquid tank weight × anti-overturning lever arm. Since the liquid tank's dimension in the X-axis direction is larger than its dimension in the Y-axis direction, it is more prone to tipping over in the Y-axis direction. The distance from the center of gravity of the liquid tank to the edge of the modular vehicle assembly in the Y-axis direction is selected as the anti-overturning lever arm length. Figure 1 As shown.

[0065] If the overturning moment is greater than or equal to the overturning resistance moment, there is a risk of overturning; if the overturning moment is less than the overturning resistance moment, there is no risk of overturning.

[0066] Step 10: Perform a stress analysis on the rotating pier and calculate the maximum shear force and negative bending moment of the rotating pier;

[0067] Specifically, such as Figure 1 and Figure 2 As shown, this embodiment uses four modular vehicle groups as an example. The four modular vehicle groups 2 are symmetrically distributed on the port and starboard sides, forming a triangular shape for support. The axle and rotating pier numbers are sequentially assigned from the bow modular vehicle group 2 towards the stern modular vehicle group. The number of axles in the vehicle group is N, and the axle numbers are N1, N2, N3, ..., Ni-1, Ni. The rotating pier numbers are N1″, N2″, N3″, ..., Ni-1″, Ni″. The rotating piers and axles are numbered consecutively from the bow modular vehicle group to the stern modular vehicle group, and the rotating piers and axles on the port and starboard sides have the same numbering. It should be noted that the rotating pier numbers and axle numbers are not one-to-one; one rotating pier may span several axles. The load above the rotating pier corresponds to the rotating pier number F. N1″ F N2″ F N3″ ..., F Ni-1″ F Ni″ ;

[0068] Then F Ni″ +F N2″ +F N3″ +...+F Ni-1″ +F Ni″ =G0.

[0069] In this embodiment, the front of the first two modular vehicle groups and the front of the last two modular vehicle groups face opposite directions. The distance between the front of the first modular vehicle group and the front of the last modular vehicle group is LN″. The distance between the front of the first modular vehicle group and the center between N1″ and N2″ is LN1″. The distance between the center between N1″ and N2″ and the center between N2″ and N3″ is LN2″, ..., the distance between the center between Ni-2″ and Ni-1″ and the center between Ni-1″ and Ni″ is LNi-1″. The distance between the center between Ni-1″ and Ni″ and the front of the last modular vehicle group is LNi″.

[0070] Then LN″=LN1″+LN2″+...+LNi-1″+LNi″;

[0071] The axle pressure of the first module car group is P1, and the axle pressure of the last module car group is P2.

[0072] Then the load F of the rotating pier Ni″ It can be represented as:

[0073] When the rotating pier is located at the head module group, P = P1; when the rotating pier is located at the tail module group, P = P2.

[0074] Therefore, the load at the first rotating pier N1″

[0075] Load at the second rotating pier N2″

[0076] …

[0077] Load at the (i-1)th rotating pier Ni-1″

[0078] Load at the i-th rotating pier Ni″

[0079] Combine F N1″ +F N2″ +F N3″ +...+F Ni-1″ +F Ni″ =G0 yields:

[0080]

[0081] Since there is no concentrated force, the shear force F acting on the rotating pier N1″ is... SN1 The axle pressure P1 of the modular train set is equal to the sum of the load F at the position of the rotating pier N1″, which is equal to the number of axles n in front of the rotating pier N1″ and the number of axles n downwards. N1″ The downward mutation is defined as negative, i.e., F SN1 = -n×P1+F N1″ ,

[0082] Starting from the second rotating pier, the shear force F acting on the rotating pier Ni″ position SNi The load is equal to the number of axes m between rotating piers Ni″ and Ni-1″, which decreases downward by m module train axle pressures plus the load F at the location of rotating pier Ni-1″. Ni-1″ If the rotating pier Ni″ is located at the head of the modular train, the axle load of the modular train is P1; if the rotating pier Ni″ is located at the tail of the modular train, the axle load of the modular train is P2; this can be represented as F. SNi =-m×P1+F Ni-1″ or F SNi = -m×P2+F Ni-1″ , i≥2.

[0083] At the location of the pier where the shear force is greatest, the bending moment M is also greatest. Since the integral of the shear force dx is the bending moment, the bending moment dM at the corresponding pier is calculated using the bending moment calculation formula: Bending moment calculation formula:

[0084] When calculating the bending moment, the x-axis is established with the front of the first module vehicle as the origin O and the direction from the first module vehicle to the rear module vehicle. The y-axis is established with the direction perpendicular to the x-axis and intersecting the origin. The z-axis is established with the direction perpendicular to the x-axis and the y-axis. The x-axis and y-axis are located in the horizontal direction, and the z-axis is located in the direction of the liquid tank height.

[0085] Step 11: If the liquid tank does not have the risk of overturning, and the maximum shear force and negative bending moment of the rotating pier are less than the allowable shear force and allowable negative bending moment of the modular vehicle assembly, then constrain the vertical degree of freedom of the upper and lower nodes of the Gap unit and all degrees of freedom of the bottom of the modular vehicle assembly. Set the gravity acceleration to a scaling factor of 1.2, and apply the reaction force in the form of surface load in the lifting area of ​​the rotating pier of the modular vehicle assembly.

[0086] If the rotating pier breaks due to its load-bearing capacity exceeding its safe range, or if the stress and strain of the liquid tank exceed the set safety threshold, then proceed to step 6 to readjust the size, quantity, and projected bearing area of ​​the rotating piers until the load-bearing capacity of the rotating piers meets its safe range. For example, if the maximum load-bearing capacity of the rotating pier is 200t, and the actual load-bearing capacity exceeds the maximum safe load-bearing capacity, the stress of the liquid tank exceeds the Q235 yield strength of 235MPa, and the strain of the liquid tank exceeds 10mm, then it is necessary to readjust the size, quantity, and projected bearing area of ​​the piers until the load-bearing capacity of the rotating piers meets its safe range.

[0087] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A finite element method for calculating the displacement of liquid tanks in a very large liquefied gas carrier, characterized in that, The method includes: Step 1: Create a 3D model of the liquid tank; Step 2: Mesh the 3D model of the liquid tank using finite element analysis software to form a finite element 3D model; Step 3: Set the material properties of the corresponding unit mesh according to the actual material properties of the liquid tank, eliminate overlapping points, and simplify the outfitting components inside the liquid tank; Step 4: Adjust the material density of models with different mesh unit sizes so that the weight and center of gravity of the finite element 3D model are close to the actual weight and center of gravity of the liquid tank, with the deviation controlled within 5%. Step 5: Perform model diagnosis on the adjusted finite element 3D model and modify any abnormal points; Step 6: Place a rotating support at the bottom of the liquid tank in the finite element 3D model. The rotating support is modeled using Gap elements, and the stiffness coefficient of the Gap elements is... Where E is the elastic modulus of the rotating pier, A is the projected force-bearing area of ​​the rotating pier, and H is the height of the rotating pier; Step 7: Couple the liquid tank and the modular vehicle assembly finite element models of the finite element 3D model with the rotating pier Gap element through Rigid rigid element bodies. Step 8: The modular vehicle groups communicate with each other via bus signals to achieve coordination and synchronization between the modular vehicle groups, and the whole vehicle is raised and lowered through height sensors; Step 9: Perform a tilting analysis on the layout of the modular vehicle group's liquid tanks to determine whether the liquid tanks pose a risk of tilting. Step 10: Perform a stress analysis on the rotating pier and calculate the maximum shear force and negative bending moment of the rotating pier; Step 11: If the liquid tank does not have the risk of overturning, and the maximum shear force and negative bending moment of the rotating pier are less than the allowable shear force and allowable negative bending moment of the modular vehicle assembly, then constrain the vertical degree of freedom of the upper and lower nodes of the Gap unit and all degrees of freedom of the bottom of the modular vehicle assembly. Set the gravity acceleration to a scaling factor of 1.2, and apply the reaction force in the form of surface load in the lifting area of ​​the rotating pier of the modular vehicle assembly. If the rotating pier breaks due to its load-bearing capacity exceeding its own safety range, or if the stress and strain of the liquid tank exceed the set safety threshold, proceed to step 6 to readjust the size, number, and projected force-bearing area of ​​the rotating pier until the load-bearing capacity of the rotating pier meets its own safety range.

2. The finite element method for calculating the displacement of liquid tanks in a super-large liquefied gas carrier according to claim 1, characterized in that, In step 2, when dividing the grid, the grid cell size is divided according to the rib spacing × longitudinal rib spacing.

3. The finite element method for calculating the displacement of liquid tanks in a super-large liquefied gas carrier according to claim 1, characterized in that, In step 9, when performing an overturning analysis of the liquid tank's location on the modular vehicle group, the wind load, braking force, dynamic load, ramp force, and centrifugal force are calculated when the liquid tank moves on the modular vehicle group. The resultant external force of the wind load, braking force, dynamic load, ramp force, and centrifugal force is calculated. Based on the resultant external force and the weight of the liquid tank itself, the overturning moment and anti-overturning moment of the entire displacement are calculated. If the overturning moment is greater than the anti-overturning moment, there is a risk of overturning.

4. The finite element method for calculating the displacement of liquid tanks in a super-large liquefied gas carrier according to claim 3, characterized in that, When calculating wind load, braking force, dynamic load, and slope force, the liquid tank is calculated in two horizontal directions, X and Y, which are perpendicular to each other. One direction is designated as the forward direction of the modular vehicle group, and the centrifugal force is calculated in the other direction.

5. The finite element method for calculating the displacement of liquid tanks in a super-large liquefied gas carrier according to claim 4, characterized in that, The length, width, and height of the liquid tank are L, W, and H, respectively. The X direction is perpendicular to the height and width directions, and the Y direction is perpendicular to the length and height directions. The X direction is designated as the forward direction of the modular vehicle group. Wind load F in the X direction 1x =C×Kh×q×(W×H)×μ; Wind load F in the Y direction 1Y =C×Kh×q×(L×H)×μ; Where C is the wind load shape coefficient, Kh is the wind pressure height variation coefficient, q is the basic wind pressure, and μ is the wind vibration coefficient.

6. The finite element method for calculating the displacement of liquid tanks in a super-large liquefied gas carrier according to claim 5, characterized in that, Braking force F in the X direction 2x =G0×i 2x Braking force F in the Y direction 2Y =G0×i 2y , where i 2x and i 2y These are the braking accelerations of the modular vehicle in the X and Y directions, respectively, and G0 is the weight of the liquid tank. Dynamic load force F in the X direction 3x =G0×i 3x Dynamic load force F in the Y direction 3Y =G0×i 3y , where i 3x and i 3y These are the moving accelerations of the modular vehicle group in the X direction and the moving accelerations in the Y direction, respectively. Force F on the ramp in the X direction 4x =G0×i 4x The slope in the Y direction is subjected to force F. 4Y =G0×i 4y , where i 4x and i 4y These are the ramp angles in the X and Y directions, respectively.

7. The finite element method for calculating the displacement of liquid tanks in a super-large liquefied gas carrier according to claim 6, characterized in that, centrifugal force Where G0 is the weight of the liquid tank, V is the turning speed of the modular vehicle group, and R is the turning radius of the modular vehicle group.

8. The finite element method for calculating the displacement of liquid tanks in a super-large liquefied gas carrier according to claim 7, characterized in that, When calculating the net external force, calculate the net external force F in the X direction separately. 0x The resultant external force F in the Y direction 0Y , F 0x =F 1x +F 2x +F 3x +F 4x , F 0Y =F 1Y +F 2Y +F 3Y +F 4Y +F 5Y 。

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