Fluid-structure coupling analysis method, system and model for cross-scale evolution of marine structures

Abstract

The application discloses a kind of fluid-structure coupling analysis method, system and model of ocean structure cross-scale evolution, method includes establishing numerical wave flume;A plurality of reinforcing layer materials RVE models are established, the macroscopic mechanical property curve of reinforcing layer material is obtained, and the corresponding stress-strain constitutive relation is obtained;Based on the stress-strain constitutive relation, the reinforcing layer component model of laminated structure is established, and the light deformable layer component model of laminated structure is established, and the reinforcing layer component model and light deformable layer component model are assembled to obtain the overall laminated floating structure;Laminated floating structure is incorporated into numerical wave flume in step S100, and fluid-structure coupling numerical simulation under wave action is carried out, and the working condition of plastic deformation of floating structure is judged according to the result, and the plastic damage area and elastoplastic evolution response of laminated floating structure are obtained.The method of the application can solve and optimize the hydroelastic-plastic response of large floating structure under wave action.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fluid-structure coupling, and more particularly relates to a fluid-structure coupling analysis method, system and model for cross-scale evolution of a marine structure. BACKGROUND

[0002] The super large floating structure is a new type of marine engineering structure developed in recent decades, which plays an important role in marine space utilization and provides a development foundation for emerging marine industries such as offshore photovoltaic. In view of the problem of deploying large floating structures in complex marine environments, floating structures under wave action will face the safety test of local plastic damage and even overall collapse and destruction.

[0003] At present, the methods for fluid-structure coupling analysis of large floating structures mainly include theoretical analysis method, semi-analytical and semi-numerical method and numerical simulation method. Compared with the theoretical analysis method and the semi-analytical and semi-numerical method, the numerical simulation method provides a more effective means for calculating the hydrodynamic-structure coupling response of the floating structure under wave action, which can more accurately and intuitively obtain the overall motion, local deformation, load distribution and even the influence on the overall flow field of the structure under wave action. Many numerical methods, such as the coupling of computational fluid dynamics and computational solid mechanics (CFD+CSM) method, the smoothed particle hydrodynamics (SPH) method and the coupled Euler-Lagrange (CEL) method, have been proposed to solve the interaction problem between the solid domain and the fluid domain. The above numerical simulation methods usually only focus on the hydroelastic effect caused by the interaction between the fluid and the elastic structure, ignoring the plastic deformation, damage evolution and the resulting flow field changes of the floating structure caused by large strain. For super large floating structures, when the wave load exceeds the linear elastic boundary of the structure itself, plastic deformation occurs in the local area of the floating structure, and the overall structure enters the elastic-plastic deformation stage. At the same time, the super large floating structure is usually designed as a floating composite structure made of composite materials.

[0004] However, for floating composite structures, many previous numerical methods first need to perform equivalent homogenization on different components of the overall structure, and then use numerical calculation programs to solve the wave-structure interaction, which obviously cannot intuitively explain the mechanical response of local components in the floating composite structure under wave load, such as stress distribution of reinforcing components and damage evolution of local weak sections. In addition, the existing numerical calculation methods for hydroplasticity problems usually need to pre-set the position of plasticity or structure collapse, and cannot comprehensively study the plasticity generation mechanism (such as yield position) of large floating structures and the evolution process of subsequent hydroplasticity phenomena. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a fluid-structure coupling analysis method, system and model for cross-scale evolution of marine structures, according to specific parameters of an initial design of a large floating structure, modeling and calculation are performed to obtain a wave working condition in which plastic deformation can be generated and a corresponding plastic damage area; if the plastic damage area is null, it indicates that the floating structure has no safety risk under the corresponding working condition and meets the design requirements; otherwise, it indicates that the floating structure has a safety risk under the corresponding working condition, and the hydro-elastoplastic response of the large floating structure under wave action is solved and optimized.

[0006] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a fluid-structure coupling analysis method for cross-scale evolution of marine structures is provided, comprising:

[0007] S100: establishing a numerical wave tank;

[0008] S200: establishing a plurality of RVE models of reinforced layer materials, obtaining a macroscopic mechanical property curve of the reinforced layer materials, and obtaining a corresponding stress-strain constitutive relationship;

[0009] S300: establishing a reinforced layer component model of the laminated structure based on the stress-strain constitutive relationship, and establishing a lightweight deformable layer component model of the laminated structure, and assembling the reinforced layer component model and the lightweight deformable layer component model to obtain an overall laminated floating structure;

[0010] S400: incorporating the laminated floating structure into the numerical wave tank in step S100, performing fluid-structure coupling numerical simulation under wave action, judging the working condition in which plastic deformation of the floating structure occurs according to the result, and obtaining the plastic damage area and the elastoplastic evolution response of the laminated floating structure.

[0011] Further, in step 100, the establishment of the numerical wave tank comprises:

[0012] S101, according to the design size of the tank, an Euler component is established, i.e. an Euler region is specified, and the control equations of the Euler region are divided into continuity equation, momentum equation and energy equation:

[0013]

[0014] Wherein, ρ is the density of Euler material (such as water or air), Dt is the time increment, ▽ is the Hamiltonian operator, v is the velocity vector, t is the time, σ is the stress tensor, b is the unit joint force tensor in the fluid domain, E is the energy, ε represents the strain rate, and Q represents the thermal conductivity.

[0015] Further, in step 100, the establishment of the numerical wave tank comprises:

[0016] S102, the fluid domain grid in the Euler region is defined as an eight-node hexahedral linear reduced integration Euler element, and local encryption measures are adopted for Euler grid region division, and the grid near the free water surface region needs to be gradually fine, and the grid density of the fluid-structure coupling region is encrypted.

[0017] Further, in step 100, the establishment of the numerical wave tank comprises:

[0018] S103, according to the design size, a rigid wave plate component model is established to simulate the actual physical wave making effect.

[0019] Further, in step 100, the establishment of the numerical wave tank comprises:

[0020] S104, the state attributes of the water body, air and wave absorbing zone water body are established, the air adopts an ideal gas state equation, including environmental pressure setting, and the ideal gas state equation is:

[0021] p+p0=ρR(θ-θ Z ) (5)

[0022] Wherein, ρ in the gas state equation refers to the air density, p is the gas pressure, p0 is the environmental pressure, θ is the current temperature, θ Z is the temperature corresponding to absolute 0°, and R is the gas constant.

[0023] Further, the EOS state equation of the wave absorbing zone water body is established, the wave absorbing zone water body is set to have a higher dynamic viscosity coefficient, so as to meet the wave propagation into the water body and gradually dissipate, and the EOS in the water body modeling is:

[0024]

[0025] U s =C0+sU p (8)

[0026] Wherein, P is the water body pressure, P H is the Hugoniot pressure, Γ0 is an approximate constant, η represents the normal volume compression strain, E m is the specific internal energy, ρ0 is the initial volume, C0 is the water wave velocity, U s and U p represent linear impact velocity and particle velocity, and s is a related parameter of U s and U p .

[0027] Further, in step 100, the establishment of the numerical wave tank comprises:

[0028] S105, divide the Euler grid area into a wave making area, a fluid-solid coupling area and a wave absorbing area, respectively give the water body, air and the water body Euler material properties of the wave absorbing area to the wave making area, the fluid-solid coupling area and the wave absorbing area, and assemble a rigid wave making plate component at the front end of the water tank.

[0029] Further, in step 200, establishing a plurality of reinforced layer material RVE models comprises:

[0030] S201, establishing a matrix model according to the performance parameters of the matrix material;

[0031] S202, establishing a plurality of groups of randomly distributed steel fiber components according to the volume fraction of the steel fiber, generating an interface transition layer on the surface of all the fibers, setting the material properties of the steel fiber and the interface transition layer, and giving the corresponding components;

[0032] S203, embedding the steel fiber and the corresponding transition layer into the matrix model to complete the assembly of the reinforced layer material RVE model;

[0033] S204, dividing the matrix, the steel fiber and the interface transition layer into grids, all of which are eight-node hexahedral linear reduced integration elements, to form a reinforced layer RVE model with different mesoscopic components.

[0034] Further, in step 200, obtaining the macroscopic mechanical property curve of the reinforced layer material to obtain the corresponding stress-strain constitutive relationship comprises the following steps:

[0035] S205, performing displacement loading analysis on each RVE model under periodic boundary conditions to obtain the macroscopic mechanical property curve of each RVE model;

[0036] S206, according to the macroscopic mechanical property curve of each RVE model and the mesoscopic component parameters, obtaining the corresponding relationship between the macroscopic stress-strain constitutive relationship of the reinforced layer material and the mesoscopic components, and establishing a numerical calculation model of the elastic-plastic damage constitutive relationship of the reinforced layer material.

[0037] Further, in step 300, establishing a reinforced layer component model in the laminated structure comprises:

[0038] S301, establishing a reinforced layer component according to the design size, giving the material elastic-plastic damage evolution constitutive property obtained in S206;

[0039] S302, establishing a high-strength reinforcement component according to the design size, setting the embedded condition in the constraint numerical setting, embedding the high-strength reinforcement in the reinforced layer to improve the bearing capacity, and giving the elastic-plastic constitutive property of the material to which the high-strength reinforcement belongs;

[0040] S303, respectively, on the reinforcing material layer and the reinforcement are divided into grid, the reinforcing material layer grid type is eight node hexahedral linear reduced integration unit, the reinforcement component grid type is three-dimensional two node truss unit, obtain high stiffness reinforcement layer component model.

[0041] Further, the step S300 of establishing the lightweight deformable layer component model of the laminated structure includes:

[0042] S304, according to the design size, establish lightweight deformable layer component, give lightweight layer material elastoplasticity constitutive attribute;

[0043] S305, the lightweight layer material component is divided into grid, and the grid type is eight node hexahedral linear reduced integration unit, and the lightweight deformable layer component model is obtained.

[0044] Further, the step S300 of assembling the reinforcing layer component model and the lightweight deformable layer component model includes:

[0045] S306, the reinforcing layer component model and the lightweight deformable layer component model are assembled, and the binding constraint numerical setting is adopted, so that the double-layer structure is closely combined into an integral laminated floating structure.

[0046] Further, the Lagrange domain calculation basic control equation of the laminated floating structure is:

[0047]

[0048] Wherein ρ is density, v is velocity vector, σ is stress tensor, E is energy, t is time, and ▽ is Hamilton operator, Is the Kronecker product.

[0049] Further, the step 400 of fluid-structure coupling numerical simulation under wave action includes:

[0050] S401, the ocean structure model with Lagrange grid is placed in the Euler domain at a predetermined position, and the self-contact interaction is set, that is, the normal behavior is set as hard contact setting, the tangential behavior is set as penalty function coupling setting, and the friction coefficient is selected as 0.1-0.2;

[0051] S402, the lateral displacement constraint is set on both sides of the Lagrange calculation area, that is, it can move freely in the vertical direction or longitudinal direction, but it cannot move laterally, and the four boundaries of the Euler calculation area are set as velocity wall boundary conditions;

[0052] S403, static water balance analysis is carried out, and gravity is applied to the floating structure, and the gravity acceleration is 9.81 m / s 2 After the ocean structure model sinks from the free water surface, the vertical displacement history is obtained along the plate length direction, and gradually tends to be stable to enter the next step;

[0053] S404, calculate the rigid wave board time function based on the linear wave push plate wave making theory, input the wave board motion time curve, the wave board moves according to the set time curve, the linear micro-amplitude wave is generated, and the fluid-structure coupling numerical calculation under wave action is carried out, the working condition of plastic deformation of the floating structure can be judged according to the result, and the plastic damage area and elastic-plastic evolution response of the floating structure can be obtained, and the fluid-structure coupling numerical simulation of the ocean structure model under wave action is realized.

[0054] Further, the velocity equation and transfer function of the wave board component motion are:

[0055]

[0056]

[0057] Where x is the position of the wave board, k is the wave number, h is the water depth, ζ represents the wave surface function, t is the time, T is the ratio of wave amplitude to wave board motion amplitude, U is the wave board velocity, and ω is the circular frequency.

[0058] According to the second aspect of the present application, a fluid-structure coupling analysis system for ocean structure cross-scale evolution is provided, comprising:

[0059] A numerical wave tank module is configured to establish a numerical wave tank.

[0060] A constitutive relation module is configured to establish a plurality of RVE models of reinforced layer materials, obtain macroscopic mechanical property curves of the reinforced layer materials, and obtain corresponding stress-strain constitutive relations.

[0061] A laminated floating structure module is configured to establish a reinforced layer component model of a laminated structure based on the stress-strain constitutive relations, establish a lightweight deformable layer component model of the laminated structure, and assemble the reinforced layer component model and the lightweight deformable layer component model to obtain an overall laminated floating structure.

[0062] A fluid-structure coupling numerical simulation module is configured to incorporate the laminated floating structure into the numerical wave tank in step S100, perform fluid-structure coupling numerical simulation under wave action, judge the working condition of plastic deformation of the floating structure according to the result, and obtain the plastic damage area and elastic-plastic evolution response of the laminated floating structure.

[0063] According to the third aspect of the present application, an equivalent model for fluid-structure coupling analysis of ocean structure cross-scale evolution is provided, comprising:

[0064] The enhanced layer material RVE model is established according to the performance parameters of the UHPC matrix material, the UHPC matrix model is established, the steel fiber units with different volume fractions are embedded into the corresponding UHPC matrix model, the enhanced layer component is established according to the initial design size, the enhanced layer UHPC material is endowed with the elastic-plastic damage evolution constitutive property, and the enhanced layer component model is obtained;

[0065] The high-strength FRP reinforced component is established, the FRP reinforcement is embedded in the enhanced layer UHPC material to improve the bearing capacity based on the embedding condition setting in the constraint numerical setting, and the elastic-plastic constitutive model of the material to which the FRP reinforcement belongs is endowed;

[0066] The light-weight deformable EPP layer component is established according to the initial design size, the light-weight layer material is endowed with the elastic-plastic constitutive property, the light-weight layer material component is divided into grids, and the light-weight deformable layer component model is obtained;

[0067] The embedding constraint method of setting the built-in area is adopted to make the interface transition layer region and the UHPC matrix model interact with each other, so that the UHPC matrix, the interface transition layer and the steel fiber can be individually divided into structured grids, and an equivalent model with different micro components is obtained.

[0068] Further, the UHPC matrix material constitutive relationship model is:

[0069] σ(ε)=E0(1-D k )ε ,(k=t,c) (9)

[0070]

[0071] Wherein, E0 is the initial elastic modulus of the UHPC matrix, D k is the tensile or compressive damage factor, k is the force stage indicator, t indicates the tensile stage, c indicates the compressive stage, ε is the strain of the UHPC matrix, ε k0 is the strain corresponding to the peak strength of the UHPC matrix, f t0 and f c0 represent the tensile and compressive strength of the UHPC matrix, ε t0 and ε c0 represent the tensile and compressive strain of the UHPC matrix at f t0 and f c0 , D t and D c represent the tensile and compressive damage factors of the UHPC matrix, a t , a c and a d are the parameters of the hardening and softening stages of the uniaxial stress-strain curve of the UHPC matrix.

[0072] Further, the steel fiber is embedded in the UHPC matrix, and the volume of the steel fiber accounts for 1%-3% of the total volume of the surface layer.

[0073] Further, the steel fiber material constitutive relation model is:

[0074]

[0075] wherein, T respectively represents the equivalent plastic strain, the normalized equivalent plastic strain, and the initial temperature, T tr is the indoor temperature, T m is the plasticizing temperature, A, B, C, m, and n are material parameters calibrated using experimental data, the first term on the right side of the above formula represents strain hardening, the second term represents strain rate hardening, and the third term represents thermal softening.

[0076] Further, the volume of the steel fiber accounts for 0%-3% of the total volume of the surface layer.

[0077] The total volume of the surface layer is the sum of the volume of the UHPC matrix and the volume of the steel fiber.

[0078] Further, the macroscopic stress-strain constitutive relation of the reinforced layer UHPC material with different steel fiber contents is fitted through the macroscopic mechanical property evolution curves of the multiple RVE models.

[0079] Based on the obtained stress-strain curve, the elastoplastic damage constitutive relation numerical model of the reinforced layer UHPC material corresponding to a steel fiber volume fraction of 2% is established as:

[0080]

[0081]

[0082] wherein, σ c0 represents the ultimate compressive strength of the UHPC ε c0 represents the compressive strain of the UHPC at σ c0 , σ t0 represents the tensile yield strength of the UHPC ε t0 represents the compressive strain of the UHPC at σ t0 , σ t represents the tensile strength of the UHPC (ε t0 <ε≤ε tu ), ε tu represents the ultimate tensile strain of the UHPC, and d cand d t are the concrete compression and tension damage factors, respectively; σ c and σ t are the compressive and tensile stresses, respectively; E is the elastic modulus of concrete; and correspond to the inelastic strains under compression and tension, respectively; and are the maximum values of and ; t0 is the exponential evolution rate of the damage parameter with the inelastic strain; the damage factor calculation formula is based on the first-order exponential decay relationship between the damage factor and the inelastic strain, b c and b t are the empirical coefficients of the compression and tension segment damage relationship of the UHPC material.

[0083] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0084] 1. The method of the present application, according to the specific parameters of the initial design of the large floating structure, models and calculates the wave conditions that can produce plastic deformation of the large floating structure and the corresponding plastic damage area; if the plastic damage area is null, it means that the floating structure has no safety risk under the corresponding working condition, which meets the design requirements; otherwise, it means that the floating structure has a safety risk under the corresponding working condition, and the hydro-elastoplastic response of the large floating structure under wave action is solved and optimized.

[0085] 2. The method of the present application can introduce the ultra-high performance concrete material with steel fibers into the large floating laminated structure at the material scale, and can also improve the thickness of the high-stiffness reinforcing layer in the large floating laminated structure at the component scale, which can be used to improve the strength, stiffness and ductility of the floating structure across scales, and prevent the destruction of the floating structure under specific wave conditions.

[0086] 3. The method of the present application, the application of ultra-high performance concrete reinforcing layer in engineering will no longer completely rely on a large number of material mechanical property tests, and the material batching ratio and structure size parameters in production and construction can be adjusted and optimized through basic numerical calculation.

[0087] 4. The method of the present application can not only perform hydrodynamic-structure-component-material cross-scale numerical simulation analysis on the large floating structure, but also effectively realize the safety optimization design of the large floating structure. BRIEF DESCRIPTION OF DRAWINGS

[0088] Figure 1 is a flowchart of the fluid-structure coupling method of the embodiment of the present application for the cross-scale evolution of the marine structure;

[0089] Figure 2 Principle diagram for the fluid-structure coupling system of the ocean structure cross-scale evolution of the embodiments of the present application;

[0090] Figure 3 Principle diagram of the coupling Euler-Lagrange (CEL) method used in the embodiments of the present application;

[0091] Figure 4 Setting diagram of the numerical tank in the embodiments of the present application (WG is the wave height measurement position);

[0092] Figure 5 Grid division diagram of the numerical model in the embodiments of the present application;

[0093] Figure 6 Modeling diagram of the RVE model of the reinforced layer material described in the present application;

[0094] Figure 7 The compressive and tensile stress-strain curves of the UHPC material with different steel fiber contents calculated by the RVE model in the embodiments of the present application;

[0095] Figure 8 Detailed design drawing of the laminated floating structure composed of the high-stiffness UHPC-FRP reinforced layer and the light-weight deformable EPP layer in the embodiments of the present application (taking the unit width as a two-dimensional numerical calculation example);

[0096] Figure 9 Numerical setting of the reinforcement embedded in the floating structure reinforcement layer and numerical setting of the binding constraint between layers in the embodiments of the present application;

[0097] Figure 10 The deflection deformation of the laminated floating structure (Model 1) under the action of waves, the pressure field at the bottom of the structure, and the deflection deformation of the reinforcement in the reinforcement layer;

[0098] Figure 11 The velocity field distribution when the wave initially acts on the laminated floating structure ((a) Model 1, (b) Model 2, (c) Model 3);

[0099] Figure 12 The plastic damage area and the corresponding internal reinforcement load enhancement of the initial model (Model 1) of the laminated floating structure in the embodiments of the present application under specific wave conditions;

[0100] Figure 13 The plastic dissipation energy evolution and the stress distribution evolution in the corresponding flow field of the initial model (Model 1) of the laminated floating structure in the embodiments of the present application after plastic damage under specific wave conditions;

[0101] Figure 14 (a) reflection coefficients, (b) transmission coefficients, and (c) energy dissipation coefficients calculated for all the layered floating structures in the embodiments of the present application;

[0102] Figure 15 maximum structural deflection response evolution curves along the length direction of the structures calculated for all the layered floating structures in the embodiments of the present application under different wave conditions;

[0103] Figure 16 maximum bending moment response evolution curves along the length direction of the structures calculated for all the layered floating structures in the embodiments of the present application under different wave conditions;

[0104] Figure 17 maximum shear force response evolution curves along the length direction of the structures calculated for all the layered floating structures in the embodiments of the present application under different wave conditions. DETAILED DESCRIPTION

[0105] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0106] Embodiment 1

[0107] As Figure 2As shown, this embodiment provides a fluid-structure interaction (FSI) analysis system for the cross-scale evolution of marine structures. It achieves cross-scale numerical calculations of FSI from the material scale to the component scale and then to the structural scale. The representative volume element (RVE) model calculation at the material scale primarily addresses the physical coupling relationship between the microscopic composition and macroscopic mechanical properties of fiber-reinforced composite materials. Component and structural scale calculations are mainly optimized through parameter adjustments and the embedding of reinforcing bars in engineering design. Macroscopic wave and floating structure FSI calculations are primarily based on a numerical wave tank established using the Coupled Euler-Lagrange (CEL) method. In this embodiment, the laminated floating structure consists of an upper reinforcing layer and a bottom layer. The top layer is composed of an ultra-high performance concrete (UHPC) matrix or steel fibers embedded within the matrix, with the steel fibers accounting for 1%-3% of the total volume of the top layer. The bottom layer is made of expanded polypropylene (EPP) foam. This invention is used to solve and optimize the hydroelastic-plastic response of large floating structures under wave action. Based on the specific parameters of the initially designed large floating structure, it models and calculates the wave conditions that can produce plastic deformation and the corresponding plastic damage areas. If there is no plastic damage area, it indicates that the floating structure has no safety risk under the corresponding conditions and meets the design requirements; otherwise, it indicates that the floating structure has a safety risk under the corresponding conditions. At the material scale, ultra-high performance concrete with added steel fibers can be introduced into large floating laminated structures. At the component scale, the thickness of the high-stiffness reinforcing layer in large floating laminated structures can be improved, which can be used to improve the strength, stiffness, and ductility of floating structures across scales, preventing the failure of floating structures under specific wave conditions. The application of ultra-high performance concrete reinforcing layers in engineering will no longer rely entirely on a large number of material mechanical property tests. The material proportions and structural dimensional parameters in production and construction can be adjusted and optimized through basic numerical calculations. It can perform cross-scale numerical simulation analysis of large floating structures (hydrodynamics, structure, components, and materials) and effectively realize the safety optimization design of large floating structures.

[0108] Example 2

[0109] like Figure 1 As shown, the fluid-structure interaction analysis method for the cross-scale evolution of marine structures under wave action includes the following steps:

[0110] Step S100: Establish a numerical wave tank. This tank is built based on the CEL method, and the basic principle is as follows: Figure 3As shown, the overall calculation domain includes: wave making area, fluid-structure coupling area, wave absorbing area, a numerical wave tank model is established in the simulation software, according to the water tank design size and the numerical setting of the water tank (such as Figure 4 As shown, the Euler component is established, that is, the Euler region is specified, and the control equation of the Euler region can be divided into continuity equation, momentum equation and energy equation respectively:

[0111]

[0112] Wherein, ρ is the density of the Euler material (such as water or air), Dt is the time increment, ▽ is the Hamiltonian operator, v is the velocity vector, t is the time, σ is the stress tensor, b is the unit joint force tensor in the fluid domain, E is the energy, ε represents the strain rate, and Q represents the thermal conductivity.

[0113] The fluid domain grid is defined as an eight-node hexahedral linear reduced integration Euler (EC3D8R) element, and local encryption measures need to be taken for Euler grid region division, the grid near the free water surface area needs to be gradually fine, and the grid density of the fluid-structure coupling area also needs to be encrypted, the grid division mode in the embodiment is as shown in Figure 5 According to the design size, the rigid wave making plate component model is established to simulate the actual physical wave making effect, the state properties of the water body, air and the water body in the wave absorbing area are established, the ideal gas state equation is adopted for the air, including the environmental pressure setting, and the ideal gas state equation is:

[0114] p+p0=ρR(θ-θ Z ) (5)

[0115] Wherein, ρ in the gas state equation refers to the air density, p is the gas pressure, p0 is the environmental pressure, θ is the current temperature, θ Z is the temperature corresponding to absolute 0°, and R is the gas constant, in the numerical calculation of the embodiment, p0=101325Pa, ρ=1.225kg / m 3 , R=287J / (kg·K). The water body and the water body in the wave absorbing area need to adopt the equation of state (EOS), the water body in the wave absorbing area is set to have a higher dynamic viscosity coefficient, which needs to meet the wave propagation into the wave absorbing area and gradually dissipate, and the EOS in the water body modeling is:

[0116]

[0117] U s =C0+sU p (8)

[0118] Wherein, P is the water body pressure, P H is the Hugoniot pressure, Γ0 is an approximate constant, η represents the normal volume compression strain, and Em is the specific internal energy, p0 is the initial volume, C0 is the water wave speed, U s and U p represent the linear impact velocity and particle velocity, s is the U s and U p related parameters. In the embodiment of the present application, C0 = 1450 m / s, p0 = 1025 kg / m 3 , the parameter s = 0, and the constant Γ0 = 0. The Euler grid region is divided into a wave making area, a fluid-structure coupling area, and a wave absorbing area, and the water body, air, and water body in the wave absorbing area are respectively assigned with Euler material properties in different division areas of the Euler domain, and a rigid wave making plate component is assembled at the front end of the water tank. In this embodiment, the numerical wave tank has a length of 30 m and a height of 10 m, and is mainly required to solve two-dimensional hydroelastic problems, so the water tank width needs to be set the same as the floating structure, the wave making plate has a height of 10 m and a length of 3 m, and the wave making plate width is consistent with the water tank width.

[0119] Step S200: Establishing a plurality of reinforced layer material RVE models (steel fiber content is 0%, 1%, 2% and 3%), obtaining the corresponding relationship between the macroscopic mechanical property evolution curve of the reinforced layer and the micro component according to the reinforced layer material RVE model, and obtaining the corresponding stress-strain constitutive relationship. Specifically, in step S200, a plurality of RVE models are established in a simulation software, a UHPC matrix model is established according to the UHPC matrix material performance parameters, the UHPC matrix material performance parameters can be obtained according to the matrix material performance test, mainly including the elastic modulus, yield strength and peak strength of the UHPC matrix, and a UHPC matrix constitutive relationship model is established according to the UHPC matrix material performance parameters obtained by the test. In this embodiment, the UHPC matrix material constitutive relationship model is:

[0120] σ(ε) = E0(1-D k )ε, (k = t, c) (9)

[0121]

[0122] wherein E0 is the initial elastic modulus of the UHPC matrix, D k is the tensile or compressive damage factor, k is the stress stage indicator, t indicates the tensile stage, c indicates the compressive stage, ε is the strain of the UHPC matrix, ε k0 is the peak strength corresponding strain of the UHPC matrix, f t0 and f c0 represent the tensile and compressive strength of the UHPC matrix, ε t0 and ε c0 represent the tensile and compressive strength of the UHPC matrix, f t0 and f c0the tensile and compressive strain at time t, D t and D c denotes the tensile and compressive damage factor of the UHPC matrix, a t , a c and a d are parameters of the hardening and softening stages of the uniaxial stress-strain curve of the UHPC matrix. In this example, the UHPC matrix material has a density of 2400 kg / m 3 , an elastic modulus of 40000 MPa, a tensile yield strength of 7.92 MPa, a compressive yield strength of 98.87 MPa, and a compressive ultimate strength of 128.09 MPa. According to the volume fraction of steel fibers, a plurality of groups of randomly distributed steel fiber components are established, and at the same time, an interface transition layer is generated on the surface of all the fibers, the material properties of the steel fibers and the interface transition layer are set and the corresponding components are endowed, the basic formula of the interface transition layer material constitutive model is consistent with that of the matrix material constitutive model, but the main parameters such as the elastic modulus, the yield strength and the peak strength need to be set to 1.2 times of the matrix material. In this example, the steel fiber material constitutive relationship model is:

[0123]

[0124] wherein, T respectively denotes the equivalent plastic strain, the normalized equivalent plastic strain and the initial temperature, T tr is the room temperature, T m is the plasticizing temperature, A, B, C, m and n are material parameters calibrated using experimental data, the first term on the right side of the above formula represents strain hardening, the second term represents strain rate hardening, and the third term represents thermal softening. The volume fraction of steel fibers is the percentage of the volume of steel fibers in the total volume of the surface layer. In this example, the volume of steel fibers in the total volume of the surface layer (the total volume of the surface layer is the sum of the volume of the UHPC matrix and the volume of the steel fibers) is 0%-3%. Specifically, the volume fraction of steel fibers can be 0%, 1%, 2% and 3% respectively, the steel fibers and the corresponding interface transition layer are embedded in the UHPC matrix model, and the assembly of the reinforced layer material RVE model is completed.

[0125] Specifically, different volume fractions of steel fiber units are embedded in corresponding UHPC matrix models to complete the assembly of various reinforced layer materials. During the assembly, the embedded constraint method of setting the built-in area is adopted to enable the interaction between the interface transition layer area and the UHPC matrix model, so that the UHPC matrix, the interface transition layer and the steel fiber can be individually divided into structured grids. The UHPC matrix and the steel fiber are divided into grids to form a reinforced layer material model with different mesoscopic components, which refers to the volume fraction content of steel fiber in the reinforced layer material RVE model. In this embodiment, the reinforced layer material RVE model modeling and the corresponding numerical settings are as shown in Figure 6 The fibers and the interface transition layer are set with shared nodes, and the transition layer area and the matrix model are constrained by the embedded unit technology.

[0126] According to the correspondence between the macroscopic mechanical property evolution curve of the reinforced layer and the mesoscopic component, the displacement loading analysis of each RVE model is performed under the periodic boundary condition to obtain the macroscopic mechanical property evolution curve (load-displacement curve) of each RVE model. Through the micro-mechanical plug-in of the simulation software, the material periodic boundary condition is applied to the RVE model for displacement loading analysis. At the same time, the stress and strain continuity of the material RVE model can be verified, and the macroscopic mechanical property evolution curve of the RVE model with different mesoscopic components is obtained by processing the above analysis results. The macroscopic mechanical property parameters of the RVE model include: the homogenized elastic modulus, the compression and tensile yield strength, the compression peak strength and the peak strength corresponding strain. According to the correspondence between the macroscopic mechanical property evolution curve of each material RVE model and the mesoscopic component, the macroscopic stress-strain constitutive relationship of the material with different mesoscopic components is constructed and obtained.

[0127] The macroscopic stress-strain constitutive relationship of the reinforced layer UHPC material with different steel fiber contents is obtained by fitting the macroscopic mechanical property evolution curves of multiple RVE models. After obtaining the correspondence between the macroscopic stress-strain constitutive relationship of the reinforced layer material and the mesoscopic component, the accuracy of the above correspondence can also be verified through physical experiments, as shown in Figure 7 The compression and tensile stress-strain curves of the reinforced layer UHPC material with different steel fiber contents obtained by the RVE model calculation in the embodiment of the application are in good agreement with the test results and numerical results. In this embodiment, based on the obtained stress-strain curve, an elastic-plastic damage constitutive relationship numerical model of the reinforced layer UHPC material corresponding to 2% steel fiber volume fraction is established, which can be used for subsequent floating structure cross-scale hydroelasticity problem solving. The elastic-plastic damage constitutive model of the UHPC material corresponding to 2% steel fiber content is:

[0128]

[0129]

[0130] Where, σ c0 Indicates the ultimate compressive strength of UHPC ε c0 Indicates UHPC at σ c0 The compressive strain at the point, σ t0 Indicates the tensile yield strength of UHPC ε t0 Indicates UHPC at σ t0 The compressive strain at the point, σ t The tensile strength (ε) of UHPC t0 <ε≤ε tu ), ε tu d represents the ultimate tensile strain of UHPC. c and d t These are the concrete compression and tensile damage factors, respectively; σ c and σ t These represent compressive stress and tensile stress, respectively; E is the elastic modulus of concrete. and These correspond to inelastic strains under compression and tension, respectively; and They are respectively and The maximum value; t0 is the exponential evolution rate of the damage parameter with inelastic strain; this damage factor calculation formula is based on the first-order exponential decay relationship between the damage factor and inelastic strain, b c and b t These are empirical coefficients relating to the damage relationship between the compressive and tensile sections of UHPC materials.

[0131] Step S300: Based on the initial design dimensions (length: 5m, width: 0.2m, thickness: 0.02m), construct the reinforcing layer components. Figure 8 This assigns elastoplastic damage evolution constitutive properties to the reinforced UHPC material obtained in S200. Based on the design dimensions, a high-strength FRP reinforced component is constructed. Based on the embedding conditions set in the constraint numerical settings, FRP reinforcement is embedded in the reinforced UHPC material to enhance its load-bearing capacity. Figure 9An elastoplastic constitutive model is assigned to the FRP reinforcement material, specifically a simplified linear elastic constitutive relation with elastic modulus, Poisson's ratio, ultimate yield strength, and corresponding ultimate yield strain. This constitutive relation has stress and strain thresholds. Meshments are generated for the reinforcement layer and the reinforcement itself. The reinforcement layer uses eight-node hexahedral linear reduced integral (C3D8R) elements, and the reinforcement component uses three-dimensional two-node truss (T3D2) elements, forming a high-stiffness reinforced layer component model. In this embodiment, to save computational costs, the FRP reinforcement protective layer is not considered. Furthermore, due to the small thickness of the reinforcement layer, only the longitudinal reinforcement distribution is considered, with the FRP reinforcement ratio set to 1.4% and kept constant. The density is 2200 kg / m³. 3 Its elastic modulus is 53100MPa, its yield strength is 1274.4MPa, and its yield strain is 0.024.

[0132] Step S400: Based on the initial design dimensions (length: 5m, width: 0.2m, thickness: 0.14m), construct a lightweight deformable EPP layer component. Figure 8 This study assigns elastoplastic constitutive properties to lightweight layer materials, specifically a simplified linear elastic constitutive relation with elastic modulus, Poisson's ratio, ultimate yield strength, and corresponding ultimate yield strain. This constitutive relation has stress and strain thresholds. The lightweight layer material component is meshed using eight-node hexahedral linear reduced integral (C3D8R) elements to form a lightweight deformable layer component model. The EPP material has a density of 2200 kg / m³, an elastic modulus of 53100 MPa, a yield strength of 1274.4 MPa, and a yield strain of 0.024.

[0133] Step S500: Assemble the component models from steps S300 and S400, using binding constraint numerical settings ( Figure 9 This allows the two-layer structure to be tightly integrated into a single laminated floating structure. The fundamental governing equations for the Lagrange domain calculation of the floating structure are:

[0134]

[0135] Where ρ is density, v is velocity vector, σ is stress tensor, E is energy, t is time, and ▽ is Hamiltonian operator. is the Kronecker product. In this embodiment, the initial design model of the laminated floating structure (Model 1) is established, the reinforcing layer has an initial design size (length: 5 m, width: 0.2 m, thickness: 0.02 m), the reinforcing layer UHPC material is a non-fiber UHPC base material, the FRP reinforcement ratio is 1.4%, the FRP bar diameter is 6 mm, and the EPP layer has an initial design size (length: 5 m, width: 0.2 m, thickness: 0.14 m). Based on the macro stress-strain constitutive relationship of the reinforcing layer UHPC material with different steel fiber contents obtained in the S2 step, the material optimization design model of the laminated floating structure (Model 2) is established, the size characteristics of the reinforcing layer, FRP reinforcement and EPP layer remain unchanged, and the reinforcing layer UHPC material is optimized to be a 2% steel fiber-containing UHPC material. Based on the UHPC-FRP reinforcing layer component obtained in the S3 step, the component optimization design model of the laminated floating structure (Model 3) is established. The size characteristics of the EPP layer remain unchanged, the reinforcing layer UHPC material is a non-steel fiber-containing UHPC base material, the reinforcing layer component thickness is increased (length: 5 m, width: 0.2 m, thickness: 0.036 m), and the FRP bar diameter is changed to 8 mm to keep the FRP reinforcement ratio unchanged. At this time, the size of the laminated floating structure is changed to: length 5 m, width 0.2 m, and thickness 0.176 m. In order to directly compare the wave-structure coupling responses between the elastic and elastoplastic laminated floating structures, a laminated floating structure model with complete elastic properties (Model R1) is established. The detailed size of Model R1 is the same as that of Model 1, and the elastic mechanics parameters of all materials in Model R1 are consistent with those of Model 1. Therefore, Model R1 only has elastic modulus, Poisson's ratio, etc., and does not have plastic mechanics performance parameters.

[0136] Step S600: The floating structure model with the Lagrangian grid is set at a predetermined position in the Euler domain, and self-contact interaction is set, i.e., the normal behavior is set as hard contact, and the tangential behavior is set as penalty function coupling. In this embodiment, the friction coefficient is selected as 0.1. The lateral displacement constraints are set on both sides of the Lagrangian calculation area, i.e., the vertical direction or the longitudinal direction can be freely moved, but the lateral direction cannot be moved. The boundaries of the Euler calculation area are set as velocity wall boundary conditions. Static equilibrium analysis is performed, and gravity is applied to the floating structure, and the gravity acceleration is 9.81 m / s 2 After the free water surface sinks, the vertical displacement history along the length direction of the plate is obtained, and after gradually tending to be stable, the next step can be entered.

[0137] Based on the linear wave push plate wave making theory formula, the time history function of the rigid wave making plate is calculated, the time history curve of the wave making plate motion is input, and the wave making plate moves to generate waves according to the time history curve. The velocity equation and the transfer function of the wave making plate motion are:

[0138]

[0139] where x is the position of the wave maker, k is the wave number, h is the water depth, ζ represents the wave function, t is time, T is the ratio of wave amplitude to the wave maker motion amplitude, U is the velocity of the wave maker, and ω is the circular frequency.

[0140] The wave maker moves according to the set time history curve, and the linear small amplitude wave is generated. Then the fluid-structure interaction numerical calculation under wave action is carried out. According to the results, the working conditions of the plastic deformation of the floating structure can be determined, and the plastic damage area and the elastic-plastic evolution response of the floating structure can be obtained. The wave conditions in the present example are designed as follows: the wave height H is between 0.153 m and 0.226 m, the wave period T is between 1.4 s and 1.7 s, and the water depth h of all wave conditions is 5 m. In order to meet the linear small amplitude wave condition, the wave steepness H / L of all wave conditions is kept at 0.05. Working condition 1: H = 0.153 m; T = 1.4 s; working condition 2: H = 0.176 m; T = 1.5 s; working condition 3: H = 0.2 m; T = 1.6 s; working condition 4: H = 0.226 m; T = 1.7 s. In order to save the calculation cost, only the wave conditions of working conditions 3 and 4 which can produce hydroelastic-plastic response are used in the numerical simulation of model R1.

[0141] Figure 10 It is shown that the initial laminated floating structure model gradually deforms under wave action, and the internal FRP tendon also produces coordinated deformation due to the bearing effect. At the same time, Figure 10 (b) shows the instantaneous pressure field near the laminated floating structure under wave conditions (working condition 2: t = 12 s). Figure 11 The velocity field of the laminated floating structure model (models 1, 2 and 3) under wave action at the initial time is shown. With the introduction of the reinforcing fiber and the thickening of the high stiffness layer, the draft of the laminated floating structure increases, thereby further enhancing the influence of the floating structure on the bottom flow field when it bends under wave action. In the present numerical results, when the wave conditions reach the design conditions of working conditions 3 and 4, the initial model (model 1) enters the elastic-plastic deformation state. Under all wave conditions, the optimized models (models 2 and 3) are always in the elastic deformation stage under wave load. Under the wave action of working conditions 3 and 4, plastic deformation and the corresponding damage area appear near the middle of the laminated floating structure model 1 ( Figure 11 (a) and (b)). As Figure 12 shown, the initial crack gradually expands, and some of the cracked concrete is completely disconnected. With the increase of wave height and wave period, the damage area of the laminated floating structure model increases ( Figure 12 (a) and (b)). After the upper reinforcement layer of model 1 appears damage cracking, the stress distribution of the internal FRP tendon evolves with the enhancement of the local bearing effect ( Figure 12 (c)). Figure 13(a) shows the evolution of plastic dissipation energy of Model 1 under wave action of wave cases 3 and 4. Under more severe wave conditions (larger wave height and longer wave length), the plastic dissipation energy of the laminated floating structure model in Case 4 is greater than that in Case 3. When the damage area of the laminated floating structure appears, the plastic dissipation energy increases sharply Figure 13 (a)). Then, after t = 25 s, the trend of damage area expansion and plastic dissipation energy increase slows down. The reason for the above phenomenon may be that the elasto-plastic UHPC components of the upper reinforcement layer gradually break at the damage location, while the corresponding internal FRP tendons and deformable EPP layers always exhibit elastic connection. The fluid-structure elasto-plastic process of the laminated floating structure can be defined by energy evolution: the elastic laminated floating structure initially enters the elasto-plastic deformation state, and the plastic dissipation energy of the structure first increases sharply, and then the increasing trend gradually slows down and tends to be stable. When the plastic dissipation energy increases sharply with the structure elasto-plastic deflection, it can be observed that there is a significant stress concentration phenomenon in the fluid domain at the bottom of the laminated floating structure Figure 13 (b) and (c)). After the plastic evolution process slows down, the stress concentration phenomenon in the fluid domain gradually disappears Figure 13 (d)). It should be noted that as the structure plastic deformation increases sharply, the boundary conditions of the fluid region covered by the floating structure change rapidly, resulting in stress concentration in the fluid domain.

[0142] The reflection coefficient K r , transmission coefficient K t and energy dissipation coefficient K d of all models under various wave conditions are calculated, as shown in Figure 14 . Due to the increase in the thickness and draft of the laminated floating structure, the reflection and energy dissipation effects of Model 3 on waves are improved compared to other models, while the transmission effect is correspondingly reduced. For the laminated floating structure models that exhibit fully hydroelastic behavior in the fluid-structure coupling process (Models 2, 3 and R1), the reflection coefficient increases with the increase of the dimensionless wave number Figure 14 (a)). As shown in Figure 14 (a), the reflection coefficient of the elasto-plastic Model 1 is greater than that of the elastic Model R1 in Cases 3 and 4. Under specific wave conditions, the laminated floating structure enters the elasto-plastic deformation state, which may enhance the reflection effect of the floating structure on waves Figure 14 (a).

[0143] It should be noted that the plastic deformation of the structure may sharply increase the local deflection of the damage area of the laminated floating structure, affecting the reflection effect of the structure. Figure 14(b) shows that the transmission coefficients of the laminated floating structure models with hydroelastic behavior (models 2, 3 and R1) gradually decrease with the increase of the non-dimensional wave number. The structural elastic-plastic behavior suppresses the wave transmission effect of model 1 under wave conditions of cases 3 and 4. Figure 14 (c) shows that the energy dissipation coefficients of model 2 are significantly smaller than those of models 1 and 3. This is because the laminated floating structure models with large draft or low bending stiffness (model 3 or 1) can cause more significant changes in viscous flow in the fluid domain when the structure produces bending vibration. In cases 3 and 4, the energy dissipation coefficients of model 1 are greater than those of the fully elastic model R1. Due to the damage area of the laminated floating structure appearing Figure 12 (a) and (b)) and the evolution of stress concentration in the flow field Figure 13 (b) and (c)), the energy dissipation caused by hydro-elastoplastic response is greater than the energy dissipation caused by hydroelastic behavior.

[0144] Figure 15 The maximum structural deflections of the laminated floating structure models at different longitudinal locations are shown (t = 0-40 s). For all laminated floating structure models, the maximum structural deflection at the middle location is significantly smaller than that at other locations Figure 15 ). The amplitude of the structural deflection response of model 3 is smaller than that of models 1 and 2 in the middle and leeside regions of the structure. Under wave conditions of cases 1 and 2, the maximum structural deflection of model 1 is close to that of model 2. However, in cases 3 and 4, the structural elastic-plastic behavior has a significant impact on the structural deflection response of model 1. As shown in Figure 15 (c) and (d), the structural deflection at the damaged location of model 1 is greater than that at the same location of model R1 with hydroelastic behavior. At the same time, the structural deflection response of model 1 at other elastic locations is affected by the hydro-elastoplastic behavior, which is different from the deflection response of model R1.

[0145] Figure 16 The maximum bending moments of the laminated floating structure models at different longitudinal locations are shown (t = 0-40 s). For all laminated floating structure models, the peak of the maximum bending moment is located in the middle region Figure 16 ). In wave cases 1, 2 and 3, the maximum bending moment of model 3 in the middle and leeside regions is smaller than that of models 1 and 2. Without considering the plastic deformation of the structure, the maximum bending moment peak of the initial design is always the largest compared to other laminated floating structure models Figure 16 Figure 16 ​(c) and (d) show that the maximum bending moment at the damage location of Model 1 is smaller than that of the elastic model R1 at the same location. It can be explained by elastoplastic mechanics that after the corresponding location of the laminated floating structure model enters the plastic state, the bending moment gradually exceeds the yield bending moment and finally reaches the ultimate bending moment, which cannot continue to increase. Therefore, compared with the actual results, the bending moment amplitude of the fluid-structure coupling response at the yield location of Model R1 is overestimated (black curve in FIG. 6). Figure 16 Compared with Model 1 designed initially, Models 2 and 3 show significant advantages in bearing capacity (such as maximum bending moment) since the floating structure is always in the elastic deformation stage Figure 16 (d)). Figure 17 The maximum shear force at different longitudinal locations of the laminated floating structure model is shown (t = 0-40 s). As shown in Figure 17 (a) and (b), the shear force response amplitude of Model 3 is smaller than that of Models 1 and 2. As shown in Figure 17 (c) and (d), the appearance of the damage area makes the maximum shear force at the plastic location of Model 1 smaller than that of the elastic model R1 at the same location.

[0146] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fluid-structure coupling analysis method for cross-scale evolution of a marine structure, characterized in that, Comprise: S100: Establish a numerical wave tank; S200: Establish a plurality of reinforced layer material RVE models, obtain the macroscopic mechanical property curve of the reinforced layer material, and obtain the corresponding stress-strain constitutive relation; S300: Based on the stress-strain constitutive relation, establish a reinforced layer component model of the laminated structure, and establish a light deformable layer component model of the laminated structure, assemble the reinforced layer component model and the light deformable layer component model to obtain the overall laminated floating structure; S400: Incorporate the laminated floating structure into the numerical wave tank in step S100, perform fluid-structure coupling numerical simulation under wave action, judge the working condition of plastic deformation of the floating structure according to the result, and obtain the plastic damage area and elastic-plastic evolution response of the laminated floating structure; S401: Place the ocean structure model with Lagrangian grid in the Euler domain at a predetermined position, set self-contact interaction, i.e. set hard contact for normal behavior and set penalty function coupling for tangential behavior, and select the friction coefficient as 0.1-0.2; S402: Set lateral displacement constraints on both sides of the Lagrangian calculation area, i.e. it can move freely in the vertical or longitudinal direction, but it cannot move laterally, and set the boundary of the Euler calculation area as a velocity wall boundary condition; S403: Perform static equilibrium analysis, apply gravity to the floating structure, and the gravitational acceleration is 9.81 m / s2. After the ocean structure model sinks from the free water surface, the vertical displacement history is obtained along the plate length direction, and after gradually tending to be stable, the next step is entered; S404: Calculate the rigid wave board time function based on the linear wave board theory, input the wave board motion time curve, and the wave board moves according to the set time curve. After linear micro-amplitude waves are generated, fluid-structure coupling numerical calculation under wave action is performed. According to the result, the working condition of plastic deformation of the floating structure can be judged, and the plastic damage area and elastic-plastic evolution response of the floating structure can be obtained, realizing the fluid-structure coupling numerical simulation of the ocean structure model under wave action.

2. The fluid-structure interaction analysis method for cross-scale evolution of a marine structure according to claim 1, wherein, In step 100, the establishment of the numerical wave tank comprises: S101, according to the design size of the tank, establish an Euler component, i.e. specify an Euler region, and the control equation of the Euler region is divided into continuity equation, momentum equation and energy equation: where p is the Euler material density, Dt is the time increment, is the Hamiltonian, v is the velocity vector, t is time, s is the stress tensor, b is the unit joint force tensor in the fluid domain, E is the energy, e represents the strain rate, and Q represents the heat conductivity.

3. The fluid-structure interaction analysis method for cross-scale evolution of a marine structure according to claim 2, wherein, In step 100, the establishment of the numerical wave tank comprises: S102, the fluid domain grid in the Euler region is defined as an eight-node hexahedral linear reduced integration Euler element, and local encryption measures are adopted for Euler grid region division. The grid near the free water surface area needs to be gradually fine, and the grid density of the fluid-structure coupling area is also encrypted.

4. The fluid-structure interaction analysis method for cross-scale evolution of a marine structure according to claim 3, characterized in that, In step 100, the establishment of the numerical wave tank comprises: S103, according to the design size, establish a rigid wave board component model to simulate the actual physical wave making effect.

5. The fluid-structure interaction analysis method for cross-scale evolution of a marine structure according to claim 2, wherein, In step 100, the establishment of the numerical wave tank comprises: S104, establish the state attributes of water, air and wave absorbing zone water, and the air adopts ideal gas state equation, including environmental pressure setting. The ideal gas state equation is: p + p0= pR(0 - 0 Z ) (5) where p denotes air density in the gas state equation, p is the gas pressure, p0 is the ambient pressure, Q is the current temperature, Q Z is the temperature corresponding to absolute 0°, and R is the gas constant.

6. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to claim 5, characterized in that, The EOS state equation of the water body in the wave absorbing zone is established, and a higher dynamic viscosity coefficient is set for the water body in the wave absorbing zone, so that the wave propagation gradually dissipates after entering the water body, and the EOS in the water body modeling is: U s = C0+ sU p (8) where P is the water pressure, P H is the Hugoniot pressure, Γ0 is an approximate constant, η represents the normal volumetric compression strain, E m is the specific internal energy, ρ0 is the initial volume, C0 is the water wave speed, U s and U p represent the linear impact velocity and particle velocity, s is a correlation parameter of U s and U p .

7. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to claim 6, characterized in that, In step 100, the establishment of the numerical wave water tank includes: S105, dividing the Euler grid area into a wave making area, a fluid-structure coupling area and a wave absorbing area, respectively assigning water, air and wave absorbing water body Euler material properties to the wave making area, the fluid-structure coupling area and the wave absorbing area, and assembling a rigid wave making plate component at the front end of the water tank.

8. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to any one of claims 1-7, characterized in that, In step 200, establishing a plurality of RVE models of the reinforcing layer material includes: S201, establishing a matrix model according to the performance parameters of the matrix material; S202, establishing a plurality of groups of randomly distributed steel fiber components according to the volume fraction of the steel fiber, and generating an interface transition layer on the surface of all the fibers, setting the material properties of the steel fiber and the interface transition layer, and assigning the corresponding components; S203, embedding the steel fiber and the corresponding transition layer into the matrix model to complete the assembly of the RVE model of the reinforcing layer material; S204, dividing the matrix, steel fiber and interface transition layer into grids, and the grid type is an eight-node hexahedral linear reduced integration element, forming a reinforcing layer RVE model with different micro components.

9. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to claim 8, characterized in that, In step 200, obtaining the macroscopic mechanical property curve of the reinforcing layer material to obtain the corresponding stress-strain constitutive relationship includes the following steps: S205, performing displacement loading analysis on each RVE model under periodic boundary conditions to obtain the macroscopic mechanical property curve of each RVE model; S206, obtaining the corresponding relationship between the macroscopic stress-strain constitutive relationship of the reinforcing layer material and the micro components according to the macroscopic mechanical property curve of each RVE model and the micro component parameters, and establishing a numerical calculation model of the elastic-plastic damage constitutive relationship of the reinforcing layer material.

10. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to claim 9, wherein, In step S300, establishing a reinforcing layer component model in the laminated structure includes: S301, establishing a reinforcing layer component according to the design size, and assigning the material elastic-plastic damage evolution constitutive property obtained in S206; S302, establishing a high-strength reinforcement component according to the design size, and setting the embedded condition in the constraint numerical setting, embedding the high-strength reinforcement in the reinforcing layer to improve the bearing capacity, and assigning the elastic-plastic constitutive property of the material belonging to the high-strength reinforcement; S303, dividing the reinforcing material layer and the reinforcement into grids, the grid type of the reinforcing material layer is an eight-node hexahedral linear reduced integration element, and the grid type of the reinforcement component is a three-dimensional two-node truss element, to obtain a high-stiffness reinforcement reinforcing layer component model.

11. The method for cross-scale coupled analysis of the elasto-plastic evolution of a floating offshore structure according to any one of claims 1-7, characterized in that, In step S300, establishing a lightweight deformable layer component model of the laminated structure includes: S304, establishing a lightweight deformable layer component according to the design size, and assigning the lightweight layer material elastic-plastic constitutive property; S305, dividing the lightweight layer material component into grids, and the grid type is an eight-node hexahedral linear reduced integration element, to obtain a lightweight deformable layer component model.

12. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to any one of claims 1-7, characterized in that, In step S300, assembling the reinforcing layer component model and the lightweight deformable layer component model includes: S306, assemble the reinforced layer component model and the lightweight deformable layer component model, and set a binding constraint value so that the double-layer structure is tightly combined into an integral laminated floating structure.

13. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to claim 12, characterized in that, The Lagrange domain calculation basic control equation of the laminated floating structure is: wherein p is density, v is velocity vector, s is stress tensor, E is energy, t is time, is a Hamiltonian operator, is a Kronecker product.

14. The fluid-structure interaction analysis method of cross-scale evolution of a marine structure according to claim 13, characterized in that, The velocity equation and transfer function of the wave board component motion are: wherein x is the position of the wave board, k is wave number, h is water depth, zeta represents wave function, t is time, T is the ratio of wave amplitude to wave board motion amplitude, U is the velocity of the wave board, and w is circular frequency.

15. A fluid-structure coupling analysis system for the cross-scale evolution of marine structures, characterized by, The method comprises the following steps: a numerical wave tank module for establishing a numerical wave tank; a constitutive relation module for establishing a plurality of reinforced layer material RVE models, obtaining a macroscopic mechanical property curve of the reinforced layer material, and obtaining a corresponding stress-strain constitutive relation; a laminated floating structure module for establishing a reinforced layer component model of the laminated structure based on the stress-strain constitutive relation, establishing a lightweight deformable layer component model of the laminated structure, and assembling the reinforced layer component model and the lightweight deformable layer component model to obtain an integral laminated floating structure; a fluid-structure coupling numerical simulation module for incorporating the laminated floating structure into the numerical wave tank in step S100, performing fluid-structure coupling numerical simulation under wave action, judging the working condition of plastic deformation of the floating structure according to the result, and obtaining a plastic damage area and an elastic-plastic evolution response of the laminated floating structure; a self-contact interaction module for setting a hard contact setting for normal behavior, setting a penalty function coupling setting for tangential behavior, and selecting a friction coefficient of 0.1-0.2; a lateral displacement constraint module for ensuring that the floating structure can move freely in the vertical direction or the longitudinal direction, but cannot move laterally; a static equilibrium analysis module for applying gravity to the floating structure, obtaining a vertical displacement history along the length of the plate after the ocean structure model sinks from the free water surface, and gradually tending to be stable before entering the next step; a fluid-structure coupling numerical calculation module for inputting a wave board motion time curve, and moving the wave board according to the set time curve to complete linear micro-amplitude wave generation and then perform fluid-structure coupling numerical calculation under wave action.

16. A fluid-structure coupling analysis equivalent model of the cross-scale evolution of a marine structure, characterized in that, The method comprises the following steps: establishing a reinforced layer component model by establishing a UHPC matrix model according to the performance parameters of the UHPC matrix material, embedding steel fiber units with different volume fractions into the corresponding UHPC matrix model, establishing a reinforced layer component according to the initial design size, assigning the reinforced layer UHPC material with an elastic-plastic damage evolution constitutive property, and obtaining the reinforced layer component model; establishing a high-strength FRP reinforcing component by embedding FRP reinforcement in the reinforced layer UHPC material based on the embedding condition setting in the constraint value setting to improve the bearing capacity, and assigning the elastic-plastic constitutive model of the material to which the FRP reinforcement belongs; establishing a lightweight deformable EPP layer component according to the initial design size, assigning the lightweight layer material with an elastic-plastic constitutive property, dividing the lightweight layer material component into grids, and obtaining a lightweight deformable layer component model. The embedded constraint method of setting the built-in area is used to make the interface transition layer region interact with the UHPC matrix model, so that the UHPC matrix, the interface transition layer and the steel fiber can be separately divided into structured grids, and an equivalent model with different micro components is obtained.

17. The fluid-structure interaction analysis equivalent model of the cross-scale evolution of a marine structure according to claim 16, characterized in that, The constitutive relationship model of the UHPC matrix material is: σ(ε) = E0(1 - D k )ε, (k = t, c) (9) where E0is the initial elastic modulus of the UHPC matrix, D k is the tensile or compressive damage factor, k is the stress stage indicator, t refers to the tensile stage, c refers to the compressive stage, ε is the strain of the UHPC matrix, ε k0 is the strain corresponding to the peak strength of the UHPC matrix, f t0 and f c0 represent the tensile and compressive strength of the UHPC matrix, ε t0 and ε c0 represent the tensile and compressive strain of the UHPC matrix at f t0 and f c0 , D t and D c represent the tensile and compressive damage factor of the UHPC matrix, a t , a c and a d are the parameters of the hardening and softening stages of the uniaxial stress-strain curve of the UHPC matrix.

18. The fluid-structure interaction analysis equivalent model of the cross-scale evolution of a marine structure according to claim 16, characterized in that, The steel fiber is embedded in the UHPC matrix, and the volume of the steel fiber accounts for 1%-3% of the total volume of the surface layer.

19. The fluid-structure interaction analysis equivalent model of cross-scale evolution of a marine structure according to claim 17, characterized in that, The constitutive relationship model of the steel fiber material is: wherein, T respectively denotes the equivalent plastic strain, the normalized equivalent plastic strain and the initial temperature, T tr is the indoor temperature, T m is the plasticization temperature, A, B, C, m and n are material parameters calibrated using experimental data, the first term on the right side of the above equation denotes the strain hardening, the second term denotes the strain rate hardening, and the third term denotes the thermal softening.

20. The fluid-structure interaction analysis equivalent model of the cross-scale evolution of a marine structure according to claim 19, wherein, The volume of the steel fiber accounts for 0%-3% of the total volume of the surface layer; The total volume of the surface layer is the sum of the volume of the UHPC matrix and the volume of the steel fiber.

21. The fluid-structure coupling analysis equivalent model of the cross-scale evolution of the marine structure according to any one of claims 16-20, characterized in that, Through the macroscopic mechanical property evolution curve of the plurality of RVE models, the macroscopic stress-strain constitutive relationship of the reinforced layer UHPC material with different steel fiber contents is fitted; Based on the obtained stress-strain curve, the numerical model of the elastic-plastic damage constitutive relationship corresponding to the reinforced layer UHPC material with a steel fiber volume fraction of 2% is established as: where σ c0 represents the ultimate compressive strength of UHPC ε c0 represents the compressive strain of UHPC at σ c0 , σ t0 represents the tensile yield strength of UHPC ε t0 represents the compressive strain of UHPC at σ t0 , σ t represents the tensile strength of UHPC (ε t0 ≤ ε tu ), ε tu represents the ultimate tensile strain of UHPC, d c and d t are the compressive and tensile damage factors of concrete, respectively; σ c and σ t are the compressive and tensile stresses, respectively; E is the elastic modulus of concrete; ε are the inelastic strains under compression and tension, respectively; ε are the maximum values of ε and ε , respectively; t0 is the exponential evolution rate of the damage parameter with the inelastic strain; the damage factor calculation formula is based on the first-order exponential decay relationship between the damage factor and the inelastic strain, b c and b t are the empirical coefficients of the compressive and tensile segment damage relationships of UHPC material, respectively.

Images