Finite element-based single-working-condition internal force calculation method and system

Abstract

The embodiment of the invention provides a finite element-based single-working-condition internal force calculation method and a finite element-based single-working-condition internal force calculation system. The method is applied to the technical field of multi-physics field coupling simulation and finite element analysis and comprises the steps that after a single working condition is received, a preset finite element model is input for structural-thermal coupling numerical solution, and strain, temperature and material evolution state data are obtained. And calculating the inherent force of the structure according to the strain-displacement matrix and the heat conduction coefficient. And fluid-structure interaction solution is carried out to obtain a pressure field, a velocity field and frequency response data, and the fluid acting force is calculated. Structural dynamics solution is carried out, acceleration, speed and deformation data are obtained, structural dynamic additional force is calculated, and finally total internal force is obtained. According to the scheme, the stress state of the structure can be comprehensively predicted and accurately evaluated, the accuracy of structure safety analysis is improved, the test cost is saved, and the design optimization and intelligent decision-making capability is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of multi-physical field coupling simulation and finite element analysis, and particularly relates to a single working condition internal force calculation method and system based on finite elements. BACKGROUND

[0002] In many engineering fields such as aerospace, ship engineering, energy power and civil construction, the internal force distribution and evolution law of complex structures under a single working condition is a key scientific problem to ensure the safety and reliability of the structure. For example, during high-speed flight, the fuselage structure of an aircraft will bear complex aerodynamic loads and thermal loads; when sailing, the ship body structure needs to cope with the impact of waves and the corrosion of seawater; the key components in energy power equipment will face extreme conditions such as high temperature and high pressure during operation; and the internal force distribution of civil construction structures under the action of natural disasters such as earthquakes and wind loads will directly affect the seismic and wind resistance performance of the structure. Therefore, accurately calculating the internal force of the structure under a single working condition is of great significance to the optimal design, safety evaluation and life prediction of the structure.

[0003] Nowadays, engineers mainly rely on manually consulting structural mechanics manuals to obtain empirical formulas. In the face of specific structures, the geometric size parameters (such as the span and cross-sectional size of the beam) and various load conditions (including the size, distribution and action position of dead load, live load, etc.) are analyzed in detail, and then according to the structure type and the type of internal force to be calculated (bending moment, shear force, etc.), the corresponding empirical formula is found from the manual, and the internal force value is calculated by substituting the parameters.

[0004] However, this method is only suitable for simple structures and conventional load conditions, and when faced with complex structures, complex boundary conditions or nonlinear material behavior, it is difficult to accurately describe the internal force distribution, and manual calculation is prone to errors and low efficiency, which has been difficult to meet the requirements of modern engineering for calculation accuracy and speed. SUMMARY

[0005] In order to solve the problems of the prior art, the present disclosure provides a single working condition internal force calculation method and system based on finite elements. The present disclosure solves the problem that the existing technology calculates the internal force by the method which is only suitable for simple structures and conventional load conditions, and when faced with complex structures, complex boundary conditions or nonlinear material behavior, it is difficult to accurately describe the internal force distribution, and manual calculation is prone to errors and low efficiency, which has been difficult to meet the requirements of modern engineering for calculation accuracy and speed.

[0006] According to a first aspect of the present disclosure, a single-operating-condition internal force calculation method based on finite elements is provided, comprising: upon receiving a single-operating-condition condition transmitted by a control center, inputting the single-operating-condition condition into a preset finite element model, obtaining strain data, temperature data, and material evolution state variable data of each unit in a structural domain by performing a structural-thermal coupling numerical solution based on the single-operating-condition on the preset finite element model; Obtaining a preset strain-displacement matrix and a preset heat transfer coefficient in a preset finite element model, and calculating the structural inherent force according to the strain data, temperature data, material evolution state variable data, the preset strain-displacement matrix, the preset heat transfer coefficient, and the preset structural inherent force calculation formula; Obtaining a preset finite element model and performing a fluid-solid coupling solution based on the single working condition to obtain pressure field data, velocity field data, multi-time-step pressure sequence data, and local frequency response characteristic data for each unit in the fluid domain, and calculating the fluid force based on the pressure field data, velocity field data, multi-time-step pressure sequence data, local frequency response characteristic data, and a preset fluid force calculation formula; Obtaining the acceleration, velocity, local deformation, and local rotation data of each node in the structural domain by performing structural dynamics solution based on the single working condition of the preset finite element model; Obtain a preset shape function matrix, a preset mass matrix, and a preset damping matrix in a preset finite element model, calculate the structural dynamic additional force according to the acceleration, velocity, local deformation, local rotation data, the preset shape function matrix, the preset mass matrix, the preset damping matrix, and the preset structural dynamic additional force calculation formula, and obtain the total internal force according to the structural inherent force, the fluid force, and the structural dynamic additional force.

[0007] According to a second aspect of the present disclosure, a finite element-based single-operating-condition internal force calculation system is provided, which is used to execute the method according to the first aspect, including: a structure-thermal coupling solution module, which is used to, upon receiving a single-operating-condition condition transmitted by a control center, input the single-operating-condition condition into a preset finite element model, obtain strain data, temperature data, and material evolution state variable data of each unit in the structural domain by performing a structure-thermal coupling numerical solution based on the single-operating-condition on the preset finite element model; A structural inherent force calculation module is used to obtain a preset strain-displacement matrix and a preset heat transfer coefficient in a preset finite element model, and calculate the structural inherent force based on the strain data, temperature data, material evolution state variable data, the preset strain-displacement matrix, the preset heat transfer coefficient, and the preset structural inherent force calculation formula; a fluid-structure interaction solving module, configured to obtain fluid-structure interaction solving of the preset finite element model based on the single working condition, to obtain pressure field data, velocity field data, multi-time-step pressure sequence data, and local frequency response characteristic data of each element in the fluid domain, and to calculate fluid force according to the pressure field data, the velocity field data, the multi-time-step pressure sequence data, the local frequency response characteristic data, and a preset fluid force calculation formula; a structure dynamics solving module, configured to obtain structure dynamics solving of the preset finite element model based on the single working condition, to obtain acceleration, velocity, local deformation, and local rotation data of each node in the structure domain; a total internal force calculating module, configured to obtain a preset shape function matrix, a preset mass matrix, and a preset damping matrix in the preset finite element model, to calculate structure dynamics additional force according to the acceleration, the velocity, the local deformation, the local rotation data, the preset shape function matrix, the preset mass matrix, the preset damping matrix, and a preset structure dynamics additional force calculation formula, and to obtain total internal force according to the structure inherent force, the fluid force, and the structure dynamics additional force.

[0008] According to a third aspect of the present disclosure, an electronic device is provided, which comprises a memory and a processor, the memory having a computer program stored thereon, and the processor implementing the method as described above when executing the program.

[0009] In the finite element-based single working condition internal force calculation method and system as provided above, the embodiments of the present disclosure can realize comprehensive prediction and accurate evaluation of the stress state of a structure, which is beneficial to improving the accuracy of structural safety analysis, saving test cost, and improving design optimization and intelligent decision-making capability. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without creative labor.

[0011] Figure 1 a finite element-based single working condition internal force calculation method according to an embodiment of the present disclosure is shown; Figure 2 a finite element-based single working condition internal force calculation method according to an embodiment of the present disclosure is shown; Figure 3 a finite element-based single working condition internal force calculation system according to an embodiment of the present disclosure is shown; Figure 4 A block diagram of an example electronic device according to embodiments of the disclosure is shown. DETAILED DESCRIPTION

[0012] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. Note that the relative arrangement, numerical expressions, and numerical values of components and steps set forth in these embodiments are not limiting to the scope of the present disclosure unless specifically stated otherwise.

[0013] Those skilled in the art can understand that the terms "first", "second", and the like in the embodiments of the present disclosure are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor indicate their logical order. It should also be understood that in the embodiments of the present disclosure, "multiple" can mean two or more, and "at least one" can mean one, two, or more. It should also be understood that for any component, data, or structure mentioned in the embodiments of the present disclosure, unless specifically limited or given the opposite implication by the context, it can be understood as one or more in general. In addition, the term "and / or" in the present disclosure is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the existence of A alone, the existence of A and B together, and the existence of B alone. In addition, the character " / " in the present disclosure generally represents an "or" relationship between the front and rear associated objects. It should also be understood that the description of various embodiments of the present disclosure emphasizes the differences between the various embodiments, and the same or similar parts can be referred to each other, and for the sake of brevity, they will not be repeated.

[0014] Meanwhile, it should be understood that the sizes of the various portions shown in the drawings are not drawn in accordance with the actual proportional relationship for the sake of convenience in description. The following description of at least one exemplary embodiment is merely illustrative in nature and in no way limiting to the disclosure and its applications or uses. Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but where appropriate, the described techniques, methods, and devices should be considered as part of the specification. It should be noted that similar reference numbers and letters in the following drawings represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0015] In order to make the purposes, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present disclosure.

[0016] Figure 1 A finite element-based single working condition internal force calculation method flowchart is provided for the embodiments of the present disclosure. The method of the embodiments of the present disclosure aims to realize accurate detection of large and small targets of pictures.

[0017] In S101, if a single working condition transmitted by the control center is received, the single working condition is input to a preset finite element model, and strain data, temperature data and material evolution state variable data of each element in the structure domain obtained by structure-thermal coupling numerical solving of the preset finite element model based on the single working condition are obtained.

[0018] The control center can be an instruction scheduling core in the whole structure analysis or equipment monitoring system.

[0019] The single working condition can refer to a parameter set of a specific loading, running or environmental scene. For example, thermal load: temperature field is 300°C, lasts for 10 min; force load: concentrated load in a certain direction is 500N; flow field boundary: inlet velocity is 20 m / s; contact working condition, friction condition, etc. It is a combination of input boundary conditions for structure calculation, thermal calculation and flow calculation.

[0020] The preset finite element model can be a pre-constructed finite element simulation model, including mesh division (structure domain and / or fluid domain); material properties (elastic modulus, thermal conductivity, etc.); contact relationship, boundary constraint; can be used for coupling analysis (structure-thermal, flow-solid, etc.). It is used as a carrier to receive the “single working condition” and complete the simulation solving core.

[0021] The structure domain can be a grid area in the finite element model, which is used to represent the grid area of the solid structure body, corresponding to the shell, beam, member, etc.; represents the heat conduction channel in structure-thermal coupling; contacts with the fluid domain in fluid-solid coupling and feels the fluid pressure.

[0022] The strain data can be the deformation information of each element of the structure domain.

[0023] The temperature data can be the temperature distribution result of each element of the structure domain, which is obtained by structure-thermal coupling solving. Each element has its local temperature value; it can be instantaneous temperature (different time steps); The material evolution state variable data can represent the state index of the performance change of the material under the influence of load, thermal environment, etc. It can include damage variables (such as D value: 0 no damage, 1 complete damage); strain hardening variables, plastic accumulation variables; fatigue damage index; phase change variable (such as crystal structure conversion); stress relaxation, creep evolution coefficient, etc.

[0024] When the system receives the data instruction from the control center, it first parses the single working condition condition therein, which includes the mechanical load boundary condition (such as concentrated force, surface force, constraint) of the structure, the thermal boundary condition (such as temperature field, heat flux density, convection coefficient), the environmental parameter (such as initial environmental temperature, humidity, radiation intensity), and the working condition duration (that is, the time interval and time step of simulation duration). Subsequently, the system loads the above-mentioned single working condition condition as input into the preset finite element model. The finite element model is a structure simulation model established in advance, which includes basic information such as geometric information, discrete grid partition, material properties, boundary identification, node and element relationship, and has multi-physical field coupling capability, especially structure-thermal coupling capability. On this basis, the structure-thermal coupling solving module is called to start the numerical simulation process. This process considers the influence of the temperature field on the material properties of the structure (such as elastic modulus, yield strength, thermal expansion coefficient, etc.), and simultaneously calculates the thermal conduction, temperature field diffusion and structure response caused by thermal stress, and adopts a method such as finite element method (FEM) for coupled iteration. In the simulation process, at each time step, the system performs thermal-mechanical coupling solving on each element in the structure domain (that is, the part of the model representing the physical structure), and extracts strain data, temperature data and material evolution state variable data.

[0025] On the basis of the above technical solution, after obtaining the strain data, temperature data and material evolution state variable data of each element in the obtained structure domain, the method further comprises: The element corresponding to the temperature data exceeding the preset temperature threshold value is regarded as a target high-temperature element, the preset material performance parameter and the preset material temperature sensitivity parameter in the preset finite element model are obtained, the preset thermal conductivity coefficient, the temperature data of the target high-temperature element, the preset material performance parameter and the preset material temperature sensitivity parameter are input into the preset temperature coupling degradation model, the degradation state of the target high-temperature element is obtained, and the target high-temperature element and the degradation state of the target high-temperature element are sent to the control center.

[0026] In this scheme, the preset temperature threshold value can be a critical temperature value for identifying the performance degradation or failure of the material under the action of high temperature, which is usually given by experiment or standard material manual. For example, for a certain alloy material, when the temperature exceeds 600°C, the strength of the material decreases greatly, so 600°C can be used as the temperature threshold value. This value is used as a reference standard for determining the target high-temperature region in the model.

[0027] The target high-temperature element can refer to the finite element element whose element temperature exceeds the preset temperature threshold value in the temperature field data. Since high temperature can easily cause material degradation, stress relaxation, creep and other phenomena, these elements are identified as the focus for further thermal-material performance coupling analysis.

[0028] The preset material property parameters can be basic performance indicators describing the material in a standard or initial state, and can include elastic modulus, Poisson's ratio, yield strength, thermal expansion coefficient, and thermal conductivity.

[0029] The preset material temperature sensitivity parameters can be used to describe parameters of how the material properties change with temperature, including thermal softening coefficient, creep rate parameter at high temperature, and temperature-dependent modulus reduction rate.

[0030] The preset temperature-coupled degradation model can be a thermal-mechanical degradation prediction model that combines temperature field and material property changes.

[0031] The degradation state can refer to the degree of material performance degradation of the target high-temperature unit, usually represented by a degradation factor D or a damage variable ω, for example: : where 0 represents no degradation and 1 represents complete failure First, the temperature data of each finite element unit in the domain is scanned one by one, and the units with temperature values exceeding the preset temperature threshold are identified as target high-temperature units, which can have thermal-induced performance degradation. Subsequently, material property parameters (such as elastic modulus, yield strength, thermal expansion coefficient, etc.) and material temperature sensitivity parameters (such as thermal softening coefficient, temperature-dependent modulus decay parameter, etc.) related to the material are extracted from the preset finite element model. Combine the preset thermal conductivity coefficient with the actual temperature data of the target high-temperature units, and input the above parameters into the temperature-coupled degradation model. The model outputs the degradation state of each target high-temperature unit according to the thermal response law of the material, to quantify the degree of attenuation of its mechanical properties. Finally, the number of target high-temperature units and their corresponding degradation state results are packaged and sent to the control center for real-time structure state monitoring, risk warning, and operation and maintenance strategy adjustment.

[0032] The training process of the preset temperature-coupled degradation model includes: The training process of the preset temperature-coupled degradation model is usually based on a large amount of historical simulation and experimental data, and supervised learning modeling combined with the physical mechanism of material degradation at high temperature. First, thermal-structural coupling finite element simulation and physical test are carried out on different material samples in a high temperature environment, and the real degradation performance of each element after the temperature exceeds the preset temperature threshold is recorded. These high temperature regions are defined as target high temperature elements, and the corresponding temperature data, preset thermal conductivity, material performance parameters (such as elastic modulus, yield strength) and temperature sensitivity parameters (such as thermal softening coefficient, thermal expansion response factor) are extracted. The above multi-source data is used as the input feature of the model training sample, and the material degradation state (such as modulus reduction ratio, fracture risk score, etc.) verified by experiment or high-precision simulation is used as the supervision label to construct the training data set. Through multiple rounds of training and parameter adjustment, models such as neural networks, support vector machines or degradation prediction regression models are used for training, so that the model can accurately predict the degradation state from the input temperature field and material property data. In practical applications, the trained temperature-coupled degradation model can receive real-time or simulated working condition inputs of target high temperature elements, output corresponding degradation state results, and automatically send these results to the control center for structure life assessment and maintenance decision-making.

[0033] In this scheme, by identifying elements exceeding the preset temperature threshold as target high temperature elements and combining parameters related to material thermal response in the finite element model, potential thermal damage areas in the structure can be identified in real time. By introducing a temperature-coupled degradation model for reasoning, the nonlinear coupling between temperature, thermal conductivity characteristics, material mechanical properties and temperature sensitivity can be considered comprehensively, so as to accurately predict the material degradation state in a high temperature environment. This prediction method has the advantages of efficiency, intelligence and traceability compared to traditional manual judgment or periodic detection. Finally, the degradation information is sent to the control center, which helps maintenance personnel to take maintenance or replacement measures in advance, avoids performance degradation or failure of the structure, and improves the safety, reliability and life management level of the system. At the same time, it also provides data support for intelligent operation and maintenance and autonomous decision-making.

[0034] S102, obtain a preset strain-displacement matrix and a preset thermal conductivity coefficient in a preset finite element model, and calculate a structure inherent force according to strain data, temperature data, material evolution state variable data, the preset strain-displacement matrix, the preset thermal conductivity coefficient, and a preset structure inherent force calculation formula.

[0035] In the finite element method, the strain-displacement matrix is used to convert the node displacement in the element to the strain in the element, which is derived from the partial derivative of the element shape function with respect to the spatial coordinates. It is a local parameter of each element, usually determined by the element type (such as triangle, tetrahedron, hexahedron) and mesh division, and is one of the cores of the finite element discretization process.

[0036] The preset thermal conductivity coefficient represents the heat conduction capacity of a material per unit temperature gradient per unit time, and is part of the material properties, which is usually a parameter of the overall model or each element, depending on whether the material is uniform.

[0037] In finite element analysis, the structural inherent force can be the reaction force generated by the material under the action of external force, temperature, deformation, etc., for resisting external load.

[0038] After receiving the strain data, temperature data, and material evolution state variable data, the corresponding strain-displacement matrix of each element is first extracted from the preset finite element model, which is determined by the element type and grid structure and can convert node displacement into element strain. At the same time, the thermal conductivity coefficient defined in the model is extracted, which is used to represent the heat conduction capacity of the material under different temperature conditions. Then, according to the thermal conductivity coefficient and the temperature data, the parameters related to heat in the material properties, such as elastic modulus, yield strength, etc., are corrected; and the current stage of the material mechanical behavior is characterized in combination with the material evolution state variable. On this basis, the strain-displacement matrix and the stress tensor after thermal-mechanical coupling are operated by using the structural inherent force calculation formula, and the numerical solution of stress-strain reaction force is carried out in the element volume by integral method, and finally the structural inherent force of each element or node is obtained, which is used to reflect the force response distribution of the structure under the current thermal-mechanical state.

[0039] On the basis of the above technical solutions, optionally, the preset structural inherent force calculation formula is: wherein, is the structural inherent force; is the transpose of the preset strain-displacement matrix; is the strain data; is the temperature data; is the material evolution state variable data; is the preset strain-displacement matrix; is the preset material parameter; is a nonlinear material stiffness matrix composed of the strain data, the temperature data, and the material evolution state variable data; is a heat flow driving term based on the temperature data and the preset material parameter; and Ωstructure represents that this integral operation is carried out in the structure domain.

[0040] The nonlinear material stiffness matrix reflects the changes in the mechanical response of the material under the influence of different strains, temperatures, and material evolution states (such as plasticity, damage, or microstructure evolution). It is constructed by inputting strain data, temperature data, and material evolution state variables into the material constitutive model, combined with elastic modulus, Poisson's ratio, thermal softening behavior, strain hardening law, and damage degradation model, to dynamically adjust the stiffness characteristics of the structural unit and achieve the ability to accurately reflect the nonlinear mechanical behavior of the material.

[0041] The heat flow driving term characterizes the equivalent internal force generated by the thermal expansion effect of the material due to temperature field changes. It is based on temperature data and material thermal parameters (such as thermal expansion coefficient, reference temperature, etc.). It is usually mapped to the stress space and multiplied by the nonlinear stiffness matrix to form the thermal-induced load term, which is used to accurately describe the influence of temperature on the stress state of the structure in thermal-structural coupling.

[0042] S103, obtain the fluid action force based on the pressure field data, velocity field data, multi-time step pressure sequence data, and local frequency response characteristic data of each element in the fluid domain obtained by solving the fluid-structure coupling of the preset finite element model under the single working condition, and a preset fluid action force calculation formula.

[0043] The fluid domain can be a part of the finite element model used to represent the fluid flow space, usually including the flow area of air, water or other media. It is the corresponding area of the solid structure domain and is one of the key components in fluid-structure coupling analysis. In actual modeling, the fluid domain is usually divided into finite volumes or finite elements, and corresponding flow boundary conditions (such as inlet and outlet, wall surface, etc.) are set.

[0044] The pressure field data can refer to the pressure distribution of each element or node in the fluid domain. It is one of the most critical physical quantities in numerical solution, representing the normal stress generated by the fluid per unit area, which is the fundamental source of fluid action force on the structure.

[0045] The velocity field data can be the velocity vector information (usually three-dimensional components vx, vy, vz) of fluid particles in space over time in the fluid domain. The velocity field reflects the dynamic behavior of the fluid and is the basis for analyzing fluid mechanics characteristics such as vortex, shear, and impact.

[0046] The multi-time step pressure sequence data can refer to the sequence data formed by sampling the pressure of each element or node at multiple time points in fluid-structure coupling analysis. It reflects the trend of pressure change over time at a certain location and can be used to identify impact loading, fatigue loading, or transient disturbance. ​

[0047] Local frequency response characteristic data can be frequency response characteristics obtained by frequency domain analysis (such as Fourier transform, power spectral density analysis, etc.) on the multi-time step pressure sequence, and is usually used to identify whether there is a periodic impact, high-frequency disturbance, etc. in a specific position.

[0048] Fluid acting force can refer to forces such as pressure and shear stress in the fluid domain that are transmitted to the structure domain through the fluid-solid interface.

[0049] A unit can be a geometric body composed of several nodes, and structural stress, strain, energy density, etc. are usually integrated or averaged at the unit level.

[0050] After receiving the single working condition transmitted by the control center, the system loads the single working condition as input into the preset finite element model, calls the preset fluid-structure coupling numerical solving module, and performs multi-physical field coupling simulation calculation. In the solving process, the model maps the structure domain and the fluid domain with the grid and coordinates the boundary conditions, and realizes the dynamic coupling between the structure response and the fluid load through the iterative method. After the calculation is completed, the pressure field data and the velocity field data of each unit are extracted from the fluid domain, and the multi-time step pressure response of the key area nodes is time-series sampled to obtain the multi-time step pressure sequence data. Subsequently, the frequency spectrum analysis method (such as fast Fourier transform FFT) is used to convert the pressure sequence to the frequency domain, and the local frequency response characteristic data of each unit is extracted. Finally, the pressure field data, the velocity field data, the multi-time step pressure sequence data and the local frequency response characteristic data are input into the preset fluid acting force calculation formula, and the fluid-structure interface stress transmission relationship and the fluid load mapping rule in the model are calculated to obtain the fluid acting force of each unit of the fluid domain on the structure domain.

[0051] On the basis of the above technical solutions, optionally, the fluid acting force is calculated according to the pressure field data, the velocity field data, the multi-time step pressure sequence data, the local frequency response characteristic data, and the preset fluid acting force calculation formula, comprising: The pressure field data is subjected to spatial difference processing to obtain the pressure gradient and the fluid density of each unit; The local velocity vector of each unit in the velocity field data is extracted; The multi-time step pressure sequence data is subjected to time difference processing to calculate the unsteady pressure change rate of each unit; The local frequency variable of each unit in the local frequency response characteristic data is extracted, and the local frequency variable is fitted to obtain a frequency response function; The fluid acting force is calculated according to the fluid density, the pressure gradient, the local velocity vector, the unsteady pressure change rate, the frequency response function, and the preset fluid acting force calculation formula.

[0052] In this scheme, the pressure gradient can be the pressure change rate per unit length, which is the change trend of the pressure field in space.

[0053] The fluid density can be the mass of fluid per unit volume.

[0054] The local velocity vector can be the speed and direction of the fluid inside each element or at the node.

[0055] The unsteady pressure change rate can be the derivative of the pressure of a point in the fluid with respect to time.

[0056] The local frequency variable can represent the main frequency component at each element caused by fluid disturbance, which can be extracted by Fourier transform or frequency domain analysis.

[0057] The frequency response function can describe the response relationship between the input and output of the system in the frequency domain.

[0058] After receiving the single working condition, the fluid-structure coupling of the preset finite element model is solved based on the working condition, and the pressure field data, velocity field data, multi-time step pressure sequence data and local frequency response characteristic data of each element in the fluid domain are obtained. First, the spatial difference processing method is used for the pressure field data, such as first-order central difference or finite difference format, to calculate the pressure gradient of each element in the spatial dimension, and the boundary conditions or state equation (such as ideal gas state equation) are further combined to calculate the fluid density of each element. Then, the local velocity vector in each element is extracted from the velocity field data, which represents the velocity amplitude and direction characteristics of the fluid in the element. Next, the multi-time step pressure sequence data is processed by time difference, such as forward difference, central difference and other methods, to calculate the unsteady pressure change rate of each element between different time steps, which reflects the change trend of fluid disturbance characteristics with time. At the same time, the local frequency variable of each element is extracted from the local frequency response characteristic data, and the least squares method, polynomial fitting or Fourier fitting method is used to construct the frequency domain response function, so as to obtain the dynamic response law of each element under different frequency excitations. Finally, the calculated fluid density, pressure gradient, local velocity vector, unsteady pressure change rate and frequency response function are input into the preset fluid force calculation formula, and the fluid force acting on each element is obtained by coupling solution, which provides accurate input for subsequent total internal force calculation.

[0059] In this scheme, through the joint processing of pressure field, velocity field, multi-time step response and frequency characteristics, the physical reality, local analysis force and engineering applicability of numerical simulation are improved, which is an important support means for structure response prediction in high requirement fluid-structure coupling environment.

[0060] On the basis of the above technical solutions, optionally, the preset fluid force calculation formula is: wherein, is the fluid force; is the fluid density; is the local velocity vector; is the pressure gradient; is the frequency response function; is the unsteady pressure change rate; Ωstructure indicates that this integral operation is performed in the fluid domain.

[0061] On the basis of the above technical solutions, optionally, after calculating the fluid force, the method further comprises: identifying high pressure gradient units according to the pressure gradient of each unit, the multi-time step pressure sequence data, and the local frequency response characteristic data; determining the position information of the high pressure gradient units, and updating the flow field boundary conditions in the preset finite element model according to the local frequency response characteristic data, the position information, and the unsteady pressure change rate of the high pressure gradient units.

[0062] In this scheme, the high pressure gradient unit can refer to a unit in the calculation domain, whose internal or adjacent region pressure field change rate (i.e. pressure gradient) exceeds a preset threshold. These units usually appear in the boundary layer, shock region, turbulent disturbance region or rapid flow change region, reflecting the severe pressure change in the flow field, which has a significant impact on the fluid behavior.

[0063] The position information can be the spatial coordinates (such as Cartesian coordinates) or grid number information of each high pressure gradient unit in the entire calculation grid or domain, which is used to locate the key region; The flow field boundary condition can be a constraint or input condition of the fluid physical quantity on the boundary in the finite element model or computational fluid dynamics simulation.

[0064] Firstly, the pressure gradient of each unit is calculated by spatial difference, and the time difference processing is combined with multi-time step pressure sequence data to obtain the pressure change characteristics of each unit in the spatial and time dimensions. Then, the local frequency response characteristic data is extracted, the pressure gradient amplitude, unsteady pressure change rate and frequency response index are compared and analyzed, and the units exceeding the preset pressure gradient threshold are identified as high pressure gradient units. In order to update the flow field boundary conditions in the finite element model, three types of key data need to be extracted from the identified high pressure gradient units: first, spatial position information is used to accurately locate the boundary area or adjacent boundary position of these units in the simulation model, so as to determine the range of the boundary area that needs to be adjusted; second, local frequency response characteristic data is used to extract dominant frequency, frequency distribution, resonance peak value and other indicators through Fourier transform of the local pressure change with time, reflecting the frequency characteristics and coupling ability of the disturbance; third, the unsteady pressure change rate, that is, the degree of pressure change in unit time, represents the degree of transient flow and local impact response. In the boundary condition updating process, the following strategies are adopted: using position information to determine the area that needs to be applied to the boundary adjustment, dividing the model boundary into static boundary area and dynamic boundary response area; using frequency response characteristic data to construct frequency sensitive boundary condition function for dynamic boundary response area, such as frequency modulation boundary (such as frequency dependent velocity inlet) or dynamic impedance boundary, so that it can respond to a specific disturbance frequency range; combining the unsteady pressure change rate to dynamically adjust the strength amplitude or response speed of the boundary condition, such as applying time-varying term (such as dP / dt type Neumann boundary) in the area with high pressure change rate, or weighted disturbance excitation function, so that it can produce more physical response with time; combining the three types of data to construct boundary disturbance function wherein the boundary application strength is determined by spatial position, then the time-varying form is set according to frequency and transient characteristics, so that the boundary can simulate the coupling effect of real complex flow disturbance.

[0065] In this scheme, the intelligent updating of boundary conditions based on local response characteristics and dynamic behavior is realized, which can significantly improve the accuracy and physical consistency of flow field simulation. By identifying high-pressure gradient elements, combining their position information, local frequency response characteristics and unsteady pressure change rate, the severe flow disturbance and periodic response characteristics of the local area can be accurately described, and these information can be fed back to the boundary setting of the finite element model, so that the boundary conditions have spatial distribution adaptability, frequency response ability and dynamic adjustment mechanism. This can more realistically reflect the unsteady disturbance propagation and coupling effect in complex flow processes, improve the modeling capability of the severe change area, effectively enhance the capture ability of vortex street, acoustic excitation, boundary layer instability and other phenomena, and thus improve the accuracy, stability and engineering practicability of the overall simulation.

[0066] In S104, a preset finite element model is solved based on the single working condition to obtain acceleration, velocity, local deformation and local rotation data of each node in the structure domain.

[0067] The node can be a discrete point in the finite element model, which is the basic definition position of displacement, velocity, acceleration and other dynamic variables. The results of structural dynamics calculation are usually based on nodes.

[0068] Acceleration can be the second-order displacement derivative of nodes with respect to time, and the unit is generally m / s², which is used to analyze the source of inertial force.

[0069] Velocity can be the first-order displacement derivative of nodes with respect to time, and the unit is m / s, which is very important in vibration, impact and fatigue analysis.

[0070] Local deformation can be the local displacement of nodes or elements relative to the initial configuration, which reflects the response degree of the structure under loading, and can be the displacement vector module or projection value.

[0071] Local rotation can be the rotation angle or angular velocity of the local coordinate system of nodes or elements, which is mainly used for beam, shell, rigid body and other models with rotational degrees of freedom.

[0072] After receiving the simplex condition transmitted by the control center, the system inputs the simplex condition as a boundary load or an initial condition into a preset finite element model, and calls a structural dynamics solving module. Based on the condition, the module uses an explicit or implicit integration algorithm to perform dynamic response analysis on the structure domain, and sequentially solves the motion response of each node in the structure domain at different time steps. In the solving process, the acceleration data (i.e., the second derivative of displacement with respect to time), the velocity data (i.e., the first derivative of displacement with respect to time), the local deformation data (i.e., the spatial displacement amplitude of the node relative to the initial position), and the rotation angle or angular velocity data in the local coordinate system or the element coordinate system of each node in the model with rotational degrees of freedom are calculated respectively by combining the node mass matrix, the damping matrix and the stiffness matrix, and finally the complete structural dynamics response result is output.

[0073] In S105, a preset shape function matrix, a preset mass matrix and a preset damping matrix in the preset finite element model are obtained, and a structural dynamic additional force is calculated according to the acceleration, velocity, local deformation, local rotation data, the preset shape function matrix, the preset mass matrix, the preset damping matrix and a preset structural dynamic additional force calculation formula. The total internal force is obtained according to the structural inherent force, the fluid acting force and the structural dynamic additional force.

[0074] The preset shape function matrix can be used to describe the geometric shape and physical behavior of elements in finite element analysis, and it is a basic component in solving system equations in the finite element method. The shape function determines how the displacement or other field quantities (such as strain, temperature, etc.) of each node are interpolated within the element. The shape function of each element is associated with the degrees of freedom of its nodes, and is usually represented in the form of a matrix, which maps the transformation relationship from the local coordinate system to the global coordinate system.

[0075] The preset mass matrix can reflect the inertial characteristics of the structure, and contains the mass distribution information corresponding to all degrees of freedom. In dynamic analysis, the mass matrix relates the acceleration of the nodes to the external load, so as to calculate the dynamic response of the nodes. The form of the mass matrix usually depends on the element type used, and common ones include consistent mass matrix and lumped mass matrix.

[0076] The preset damping matrix can describe the energy loss characteristics of the structure during vibration, and reflects the influence of non-conservative forces such as friction and viscous resistance. In dynamic analysis, the damping matrix is associated with the velocity field, and is used to calculate the energy attenuation of the structure. The damping matrix is usually symmetric, and can be parameterized by different models (such as constant damping, Rayleigh damping, etc.).

[0077] Structural dynamic additional forces can refer to additional forces in structural dynamics analysis due to external excitations or internal nonlinear behaviors (such as large deformation, contact, plastic behavior, etc.). These forces are not from traditional external loads, but additional effects due to the dynamic response of the structure itself, changes in material properties or changes in boundary conditions. For example, in frequency response analysis, additional forces can come from instantaneous mass loading or resonance effects caused by specific frequencies.

[0078] Total internal forces can be the collection of all forces inside the structure.

[0079] After receiving the acceleration, velocity, local deformation, and local rotation data of each node in the structure domain, the pre-set shape function matrix, mass matrix, and damping matrix corresponding to the current element type and discretization format are first extracted from the pre-set finite element model. Then, using these pre-set matrices and the acquired dynamic response data, the structural dynamic additional forces of each node or each element under the current load are calculated according to the pre-set structural dynamic additional force calculation formula. Combined with the previously calculated structural inherent forces and fluid action forces based on structure-thermal coupling and fluid-structure coupling, the three are unified and synthesized according to the internal force superposition relationship, and finally the total internal force of the structure under the working condition is obtained for subsequent structural response analysis or safety evaluation.

[0080] The steps for establishing the pre-set finite element model are as follows: The pre-set finite element model is established by abstract modeling and parameterization of the real physical properties of the target structure and its operating environment. A three-dimensional modeling tool is used to establish the geometric model of the structure domain and the fluid domain, and a meshing technique is used to discretize the structure domain and the fluid domain into multiple finite element units, defining the element types (such as tetrahedral elements, hexahedral elements, etc.) and their connection relationships at the coupled boundary. To ensure accuracy and computational efficiency, the model is pre-set with material performance parameters (such as Young's modulus, Poisson's ratio, density, thermal expansion coefficient, specific heat capacity, thermal conductivity, etc.), material temperature sensitivity parameters (reflecting the law of material performance change with temperature), and material evolution state variable parameters (such as damage variable, hardening variable, phase change variable) for structure-thermal coupling simulation.

[0081] At the same time, strain-displacement matrices are pre-set for converting node displacements to element strains, thermal conductivity coefficients are pre-set for thermal conduction calculations, and fluid physical parameters (such as viscosity coefficient, density, velocity boundary conditions) and fluid-structure interface conditions (such as coupled surface boundary types, normal projection relationships) are pre-set to realize fluid-structure coupling solution.

[0082] In the structural dynamics analysis part, the shape function matrix (used for the interpolation calculation of physical quantities between nodes), the mass matrix (describing the mass distribution characteristics of the nodes), and the damping matrix (modeling the energy dissipation process) are pre-set in the model, and the initial boundary conditions and time integration format (such as the Newmark-beta method) for dynamic response solving are configured. The finite element model also embeds structural inherent force calculation formulas (such as based on stress-strain relationship), fluid force calculation formulas (such as based on the integral form of pressure and velocity distribution), and structural dynamic additional force calculation formulas, etc., to realize fast calling and multi-field coupling calculation when receiving single working condition. Specifically, the establishment of the pre-set finite element model is a process of abstracting a digital simulation model from a real physical system, aiming to realize structural-thermal-fluid multi-physical field coupling analysis and prediction. First of all, according to the operating environment and physical response characteristics of the target structure, systematic abstract modeling is needed. This process includes modeling the mechanical properties, thermal properties, and flow boundary characteristics of the structural material, as well as defining the mathematical expression of its response behavior under specific working conditions. On this basis, a three-dimensional modeling tool is used to build the geometric model of the structure domain and the fluid domain, and to clearly define their contact and coupling relationship, laying the foundation for subsequent discretization processing.

[0083] Subsequently, finite element meshing is performed on the established geometric model, and the structure domain and fluid domain are divided into multiple finite element units, and appropriate element types (such as tetrahedral elements, hexahedral elements, etc.) are selected according to specific analysis requirements. At the same time, element connection relationships are defined at the fluid-structure interface to ensure boundary continuity and correct transmission of coupled interaction. In this stage, the strain-displacement matrix is also pre-set for the conversion of node displacement to element strain; and the shape function matrix is set to realize the interpolation calculation of physical quantities between nodes. In order to improve the solving efficiency and accuracy, local grid refinement areas need to be set, especially in the high gradient area or fluid-structure coupling boundary.

[0084] In order to accurately simulate the response behavior of materials under actual working conditions, a variety of material parameters are pre-set in the model, including basic material performance parameters (such as Young's modulus, Poisson's ratio, density, specific heat capacity, thermal conductivity, thermal expansion coefficient, etc.), temperature sensitivity parameters (used to describe the variation of material properties with temperature), and material evolution state variable parameters (such as damage variable, hardening variable, phase change variable, etc.). These parameters support the dynamic updating of material degradation and thermal response in subsequent structural-thermal coupling simulation. At the same time, to meet the needs of heat conduction analysis, the model sets the thermal conductivity coefficient for heat field solving under different temperature fields; and considers the dynamic correction mechanism of temperature-related properties.

[0085] In the structure-thermal coupling solving module, a two-way coupling mechanism between the heat conduction control equation and the structural mechanics equation is introduced into the model. The coupling calculation is realized by the mutual driving of the temperature field and the stress field. The change of the temperature distribution will cause additional stress and deformation of the structure through thermal expansion effect, while the local stress state of the structure will also affect the conduction behavior of the heat flow flux on the interface. In the modeling process, the heat conduction term and the thermal strain term are introduced into the structure field control equation, and the structure stiffness matrix and the heat conduction matrix are connected with each other through a nonlinear coupling matrix, realizing the joint iterative solution under the coupling incremental method. The steady-state and transient coupling thermal boundary conditions are supported in the boundary condition aspect, including fixed temperature boundary, constant heat flow boundary, surface convection boundary and radiation heat transfer condition, etc., and the definition of boundary heat source and thermal contact impedance is allowed to enhance the adaptability under actual engineering conditions. The model also supports the dynamic updating mechanism of the material thermal physical property parameters with temperature change, so as to realize the whole process simulation of complex thermal-mechanical response behaviors such as structure thermal fatigue, thermal buckling and thermal creep.

[0086] In the structure dynamics solving module, mass matrix, stiffness matrix and damping matrix are preset to describe the node mass distribution, structure stiffness characteristics and energy dissipation mechanism. At the same time, initial boundary conditions, time integration format (such as Newmark-beta method, explicit or implicit integration) and other time domain solving control strategies are configured for dynamic response analysis. For the fluid domain, the model is configured with fluid physical parameters (such as density, viscosity coefficient, velocity boundary condition) and their boundary condition definitions for coupling with the structure, such as normal projection relationship and boundary coupling surface type.

[0087] In the multi-field coupling part, the model is embedded with structural inherent force calculation formula (such as integral form based on stress-strain relationship), fluid force calculation formula (area integral expression based on pressure and velocity distribution), and structural dynamic additional force calculation formula (based on acceleration, velocity, damping, etc.). In addition, the model also has a built-in fluid-structure coupling solving module, which supports grid mapping, boundary coordination and coupling iteration calculation, and can realize response analysis after inputting specific boundary conditions or single working condition.

[0088] To support subsequent high-performance prediction and identification analysis, the model has special added frequency domain analysis and response extraction capability. In the calculation process, the local frequency response characteristic data of each element are extracted by extracting multi-time step pressure sequence data and applying fast Fourier transform (FFT) and other spectrum analysis methods. These data, together with the position information of the element and the unsteady pressure change rate, are used to identify high-pressure gradient elements and assist in updating the model boundary conditions, to ensure that the simulation results can be closer to the real physical system state.

[0089] Ultimately, this pre-built finite element model not only possesses comprehensive structural-thermal-fluid-structure coupling capabilities but also integrates modules such as material state evolution, dynamic boundary adjustment, and frequency response identification, forming a reusable, iterative, and predictive multi-physics digital twin simulation platform. This model provides a solid data foundation and solution support for intelligent identification, structural health prediction, adaptive boundary condition adjustment, and the development of operation and maintenance strategies.

[0090] On the basis of the above technical solution, the optional, preset structural dynamic additional force calculation formula is: in, Add forces to structural dynamics; is the transpose of the preset shape function; is the preset mass matrix; is the acceleration; for speed; is the preset damping matrix; is the local deformation; is the local rotation data; It is the internal force response function composed of local deformation and local rotation data; Ωstructure indicates that this integration operation is performed in the structural domain.

[0091] In this scheme, the internal force response function is used to describe the nonlinear additional internal force term generated by the structure under the action of local deformation and local rotation. It is constructed by establishing a coupling relationship between local geometric nonlinearity and material nonlinear response. Specifically, the local displacement gradient is first coupled with the change in rotation angle to form a nonlinear geometric stiffness term (such as the geometric stiffness matrix caused by large deformation); secondly, the stress response of the material under the local strain path (which can be based on an elastic-plastic model, a damage model, or a hyperelastic model) is combined to construct an internal force expression related to deformation and rotation; finally, it is encapsulated as a function as an additional nonlinear internal force term in the dynamic response equation to compensate for the insufficient accuracy of the linear model in the local strong deformation area, thereby improving the accuracy and stability of the solution of the structural dynamic response.

[0092] In the embodiments of the present application, if the single working condition transmitted by the control center is received, the single working condition is input into the preset finite element model, the strain data, temperature data and material evolution state variable data of each element in the structure domain obtained by the structure-thermal coupling numerical solving of the preset finite element model based on the single working condition are obtained, the preset strain-displacement matrix and the preset thermal conductivity coefficient in the preset finite element model are obtained, the structural inherent force is calculated according to the strain data, temperature data, material evolution state variable data, preset strain-displacement matrix, preset thermal conductivity coefficient and preset structural inherent force calculation formula, the fluid-structure coupling solving of the preset finite element model based on the single working condition is obtained, the pressure field data, velocity field data, multi-time step pressure sequence data and local frequency response characteristic data of each element in the fluid domain obtained are obtained, the fluid action force is calculated according to the pressure field data, velocity field data, multi-time step pressure sequence data, local frequency response characteristic data and preset fluid action force calculation formula, the acceleration, velocity, local deformation and local rotation data of each node in the structure domain obtained by the structure dynamics solving of the preset finite element model based on the single working condition are obtained, the preset shape function matrix, preset mass matrix and preset damping matrix in the preset finite element model are obtained, the structural dynamic additional force is calculated according to the acceleration, velocity, local deformation, local rotation data, preset shape function matrix, preset mass matrix, preset damping matrix and preset structural dynamic additional force calculation formula, and the total internal force is obtained according to the structural inherent force, fluid action force and structural dynamic additional force. Through the above single working condition internal force calculation method based on finite element, by inputting the single working condition into the preset multi-physical field finite element model, the structure-thermal coupling, fluid-structure coupling and structure dynamics analysis are integrated, the structural response behavior under complex working conditions can be accurately simulated, the key physical quantities such as strain, temperature, fluid pressure and local deformation are comprehensively obtained, the structural inherent force, fluid action force and structural dynamic additional force are efficiently calculated by combining the preset physical parameter matrix and calculation formula, and the total internal force is uniformly solved, so that the comprehensive prediction and accurate evaluation of the structural stress state are realized, which is beneficial to improving the accuracy of structural safety analysis, saving test cost and improving design optimization and intelligent decision-making ability.

[0093] Figure 2 The flowchart of the single working condition internal force calculation method based on finite element provided by the embodiments of the present application. The method can include the following steps: S201, if the single working condition transmitted by the control center is received, the single working condition is input into the preset finite element model, the strain data, temperature data and material evolution state variable data of each element in the structure domain obtained by the structure-thermal coupling numerical solving of the preset finite element model based on the single working condition are obtained.

[0094] S202, calculate the principal strain of each unit according to the strain data of each unit, and the unit whose principal strain exceeding the preset strain threshold is the target high strain unit.

[0095] The principal strain can refer to the eigenvalue obtained after the strain tensor in a unit is subjected to eigenvalue decomposition, which reflects the maximum, minimum and intermediate degree of stretching or compression deformation of the material in the unit in three main directions, and is an important indicator for describing local deformation intensity, which is usually represented by three principal strain values (maximum principal strain, minimum principal strain, and intermediate principal strain), wherein the maximum principal strain is most commonly used to judge the failure trend.

[0096] The preset strain threshold can be a reference value set in advance according to material performance experiment, fatigue limit or design standard, which is used as a dividing line to determine whether the unit reaches a dangerous or significant deformation state.

[0097] The target high strain unit can be a finite element unit whose principal strain value exceeds the preset threshold during the structural analysis process. These units may have risks such as material yield, damage, micro-crack formation, and thus are marked as the key attention area in the structural safety assessment, which can be used to guide subsequent local refined modeling, fatigue life assessment or structural reinforcement design.

[0098] First, the principal strain of each unit in the finite element model is calculated through the strain tensor of the unit. The strain tensor is usually composed of three orthogonal direction strain components, and the principal strain value is obtained by performing eigenvalue decomposition on the strain tensor. The eigenvalue is the strain size of the unit in three directions, and the maximum principal strain is usually selected to evaluate the deformation degree of the unit. When calculating, the principal value formula of the strain tensor can be used to obtain the principal strain value, which represents the deformation degree of the unit in the principal axis direction. Next, according to the known preset strain threshold (usually a critical value set according to the yield strength, fatigue limit and other design standards of the material), the principal strain of each unit is compared. When the maximum principal strain of a unit exceeds the preset threshold, it indicates that the unit may face a greater deformation or damage risk. Therefore, the unit exceeding the threshold will be identified as a "target high strain unit".

[0099] S203, performing mesh subdivision on the target high strain unit according to a preset adaptive refinement strategy.

[0100] The preset adaptive refinement strategy can be a local mesh optimization method based on error driving or physical index driving. After identifying the target high strain element, the method determines whether to refine the element according to the degree of principal strain exceeding the threshold, the gradient strength of the element in the stress field or the energy field, or other evaluation function values. The refinement rules usually include the element splitting method (such as quadtree, octree), the refinement depth (such as the maximum refinement level), the boundary continuity processing method (such as the common node interpolation), and the propagation range of the refinement region (such as whether to refine the adjacent elements to ensure the transition smoothness). The strategy can be combined with an adaptive controller to dynamically adjust the refinement standard according to the overall response change of the structure, so as to control the calculation cost while ensuring the calculation accuracy.

[0101] When the target high strain element is meshed, the system first determines the region and the refinement level that need to be refined according to the preset adaptive refinement strategy. In specific operation, after identifying the target high strain element whose principal strain exceeds the preset threshold, the element is divided into multiple sub-elements according to the refinement rules, such as a two-dimensional quadrilateral element can be refined into four small elements, and a three-dimensional hexahedral element can be refined into eight sub-elements. In the refinement process, new nodes are generated and the local topology structure is updated to ensure the geometric continuity and calculation compatibility between the newly generated elements. To avoid calculation instability caused by sudden changes, the system can also perform auxiliary refinement on the adjacent region of the target element according to the refinement propagation criteria, so as to maintain the coordination and smoothness of the overall mesh. After the refinement is completed, the initial state variables are re-assigned to the newly generated elements, and the element connection relationship and the solving matrix of the finite element model are updated to ensure the accuracy and stability of the subsequent coupled calculation.

[0102] S204, obtain a preset strain-displacement matrix and a preset thermal conductivity coefficient in a preset finite element model, and calculate a structure inherent force according to strain data, temperature data, material evolution state variable data, the preset strain-displacement matrix, the preset thermal conductivity coefficient, and a preset structure inherent force calculation formula.

[0103] S205, obtain a fluid-structure coupling solution of the preset finite element model based on the single working condition, to obtain pressure field data, velocity field data, multi-time step pressure sequence data, and local frequency response characteristic data of each element in the fluid domain, and calculate a fluid force according to the pressure field data, the velocity field data, the multi-time step pressure sequence data, the local frequency response characteristic data, and a preset fluid force calculation formula.

[0104] S206, obtain a structure dynamics solution of the preset finite element model based on the single working condition, to obtain acceleration, velocity, local deformation, and local rotation data of each node in the structure domain.

[0105] S207, obtain a preset shape function matrix, a preset mass matrix and a preset damping matrix in the preset finite element model, calculate a structure dynamic additional force according to the acceleration, the speed, the local deformation, the local rotation data, the preset shape function matrix, the preset mass matrix, the preset damping matrix and a preset structure dynamic additional force calculation formula, and obtain a total internal force according to the structure inherent force, the fluid acting force and the structure dynamic additional force.

[0106] In the embodiment, the accurate positioning of the key stress areas of the structure is realized by calculating the principal strain of each unit and identifying the target high-strain unit exceeding the preset strain threshold, and the local mesh subdivision of these areas is performed by using the adaptive refinement strategy, which not only significantly improves the numerical accuracy and reliability of the solution of the finite element model in the high-gradient area, but also avoids the invalid encryption of the global mesh, reduces the consumption of computing resources and time cost, and balances the accuracy and efficiency, so that the model is more stable, sensitive and efficient when dealing with complex load and local damage evolution analysis.

[0107] Figure 3 A finite element-based single working condition internal force calculation system schematic block diagram is provided for the embodiments of the present disclosure. The system comprises: The structure-thermal coupling solving module 301 is configured to input the single working condition to the preset finite element model if the single working condition transmitted by the control center is received, obtain strain data, temperature data and material evolution state variable data of each unit in the structure domain obtained by the structure-thermal coupling numerical solving of the preset finite element model based on the single working condition; The structure inherent force calculation module 302 is configured to obtain a preset strain-displacement matrix and a preset thermal conductivity coefficient in the preset finite element model, and calculate the structure inherent force according to the strain data, the temperature data, the material evolution state variable data, the preset strain-displacement matrix, the preset thermal conductivity coefficient and a preset structure inherent force calculation formula; The fluid-structure coupling solving module 303 is configured to obtain pressure field data, velocity field data, multi-time step pressure sequence data and local frequency response characteristic data of each unit in the fluid domain obtained by the fluid-structure coupling solving of the preset finite element model based on the single working condition, and calculate the fluid acting force according to the pressure field data, the velocity field data, the multi-time step pressure sequence data, the local frequency response characteristic data and a preset fluid acting force calculation formula; The structure dynamics solving module 304 is configured to obtain acceleration, speed, local deformation and local rotation data of each node in the structure domain obtained by the structure dynamics solving of the preset finite element model based on the single working condition; The total internal force calculation module 305 is configured to acquire a preset shape function matrix, a preset mass matrix and a preset damping matrix in a preset finite element model, calculate a structure dynamic additional force according to the acceleration, the speed, the local deformation, the local rotation data, the preset shape function matrix, the preset mass matrix, the preset damping matrix and a preset structure dynamic additional force calculation formula, and obtain the total internal force according to the structure inherent force, the fluid acting force and the structure dynamic additional force.

[0108] Figure 4 A schematic block diagram of an electronic device 400 that can be used to implement embodiments of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptops, desktops, tablets, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device can also represent various forms of mobile devices, such as personal digital assistants, cellular telephones, smartphones, wearable devices, and other similar computing devices. The components shown here, their connections and relationships, and their functions, are meant to be examples only, and are not meant to limit implementations of the present disclosure described and / or claimed in this document.

[0109] The electronic device 400 includes a computing unit 401 that can perform various appropriate actions and processes in accordance with a computer program stored in a ROM 402 or loaded into a RAM 403 from a storage unit 408. Various programs and data required for the operation of the electronic device 400 can also be stored in the RAM 403. The computing unit 401, the ROM 402, and the RAM 403 are connected to each other through a bus 404. An I / O interface 405 is also connected to the bus 404.

[0110] Various components in the electronic device 400 are connected to the I / O interface 405, including an input unit 406, such as a keyboard, a mouse, and the like, an output unit 407, such as various types of displays, speakers, and the like, a storage unit 408, such as a magnetic disk, an optical disk, and the like, and a communication unit 409, such as a network card, a modem, a wireless communication transceiver, and the like. The communication unit 409 allows the electronic device 400 to exchange information / data with other devices through a computer network, such as the Internet, and / or various telecommunication networks.

[0111] The computing unit 401 can be various general and / or special purpose processing components with processing and computing capabilities. Some examples of the computing unit 401 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The computing unit 401 performs various methods and processes described above, such as the finite element based single working condition internal force calculation method. For example, in some embodiments, the finite element based single working condition internal force calculation method can be implemented as a computer software program, which is tangibly embodied in a machine-readable medium, such as the storage unit 408. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 400 via the ROM 402 and / or the communication unit 409. When the computer program is loaded onto the RAM 403 and executed by the computing unit 401, one or more steps of the finite element based single working condition internal force calculation method described above can be performed. Alternatively, in other embodiments, the computing unit 401 can be configured to perform the finite element based single working condition internal force calculation method by any other appropriate means, such as by means of firmware.

[0112] Various implementations of the systems and techniques described above can be realized in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on a chip (SOC), a programmable logic device (CPLD), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0113] Program code for carrying out methods of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, produces a means for implementing the functions / acts specified in the flowcharts and / or block diagrams. The program code can be executed entirely on a machine, partially on a machine, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0114] In the context of the present disclosure, a machine-readable medium can be a tangible medium that contains or stores a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include one or more lines of electrical connections, portable computer disks, hard disk drives, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fibers, portable compact disc read-only memories (CD-ROMs), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0115] To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having a display device for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0116] The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a user computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN), a wide area network (WAN), and the Internet.

[0117] The computer system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server can arise by virtue of computer programs running on the respective computers and having a client-server relationship to each other. The server can be a cloud server, a server of a distributed system, or a server combined with a blockchain.

[0118] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved. This is not limited herein.

[0119] The above specific embodiments do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure shall be included within the scope of protection of this disclosure.

Claims

1. A single-condition internal force calculation method based on finite element method, characterized in that: The method comprises: If a single operating condition is received from the control center, the single operating condition is input into a preset finite element model, and the preset finite element model is numerically solved for structural-thermal coupling based on the single operating condition to obtain strain data, temperature data, and material evolution state variable data of each unit in the structural domain; Obtaining a preset strain-displacement matrix and a preset heat transfer coefficient in a preset finite element model, and calculating the structural inherent force according to the strain data, temperature data, material evolution state variable data, the preset strain-displacement matrix, the preset heat transfer coefficient, and the preset structural inherent force calculation formula; Obtaining a preset finite element model and performing a fluid-solid coupling solution based on the single working condition to obtain pressure field data, velocity field data, multi-time-step pressure sequence data, and local frequency response characteristic data for each unit in the fluid domain, and calculating the fluid force based on the pressure field data, velocity field data, multi-time-step pressure sequence data, local frequency response characteristic data, and a preset fluid force calculation formula; Obtaining the acceleration, velocity, local deformation, and local rotation data of each node in the structural domain by performing structural dynamics solution based on the single working condition of the preset finite element model; Obtain a preset shape function matrix, a preset mass matrix, and a preset damping matrix in a preset finite element model, calculate the structural dynamic additional force according to the acceleration, velocity, local deformation, local rotation data, the preset shape function matrix, the preset mass matrix, the preset damping matrix, and the preset structural dynamic additional force calculation formula, and obtain the total internal force according to the structural inherent force, the fluid force, and the structural dynamic additional force.

2. The method according to claim 1, characterized in that in, Calculating the fluid force based on the pressure field data, velocity field data, multi-time-step pressure sequence data, local frequency response characteristic data, and a preset fluid force calculation formula includes: Performing spatial difference processing on the pressure field data to obtain the pressure gradient and fluid density of each unit; Extracting the local velocity vector of each unit in the velocity field data; Performing time difference processing on the multi-time-step pressure series data to calculate the unsteady pressure change rate of each unit; Extracting the local frequency variables of each unit in the local frequency response characteristic data, fitting the local frequency variables, and obtaining a frequency response function; The fluid force is calculated based on the fluid density, pressure gradient, local velocity vector, unsteady pressure change rate, frequency response function and the preset fluid force calculation formula.

3. The method according to claim 1, characterized in that in, The preset formula for calculating the structural inherent force is: in, is the inherent force of the structure; is the transpose of the preset strain-displacement matrix; is strain data; Temperature data is the material evolution state variable data; is the preset strain-displacement matrix; are the preset material parameters; is the nonlinear material stiffness matrix composed of strain data, temperature data and material evolution state variable data; is a heat flow driven term based on temperature data and preset material parameters; Ωstructure indicates that this integration operation is performed in the structure domain.

4. The method according to claim 2, characterized in that in, The preset fluid force calculation formula is: in, is the fluid force; is the fluid density; is the local velocity vector; is the pressure gradient; is the frequency response function; is the unsteady pressure change rate; Ωstructure indicates that this integration operation is performed in the fluid domain.

5. The method according to claim 1, wherein in, The preset calculation formula for the structural dynamic additional force is: in, Add forces to structural dynamics; is the transpose of the preset shape function; is the preset mass matrix; is the acceleration; for speed; is the preset damping matrix; is the local deformation; is the local rotation data; It is the internal force response function composed of local deformation and local rotation data; Ωstructure indicates that this integration operation is performed in the structural domain.

6. The method according to claim 1, characterized in that in, After obtaining the strain data, temperature data, and material evolution state variable data of each unit in the structural domain, the method further includes: Calculate the principal strain of each unit based on the strain data of each unit, and define the unit corresponding to the principal strain exceeding the preset strain threshold as the target high-strain unit; The target high strain unit is meshed according to the preset adaptive refinement strategy.

7. The method according to claim 1, characterized in that in, After obtaining the strain data, temperature data, and material evolution state variable data of each unit in the structural domain, the method further includes: The unit corresponding to the temperature data exceeding the preset temperature threshold is taken as the target high-temperature unit, the preset material performance parameters and the preset material temperature sensitivity parameters in the preset finite element model are obtained, the preset thermal conductivity coefficient, the temperature data of the target high-temperature unit, the preset material performance parameters and the preset material temperature sensitivity parameters are input into the preset temperature coupling degradation model, the degradation state of the target high-temperature unit is obtained, and the target high-temperature unit and the degradation state of the target high-temperature unit are sent to the control center.

8. The method according to claim 2, characterized in that in, After calculating the fluid force, the method further includes: Identify high pressure gradient units according to the pressure gradients, multi-time-step pressure sequence data, and local frequency response characteristic data of each unit; The position information of the high pressure gradient unit is determined, and the flow field boundary conditions in the preset finite element model are updated according to the local frequency response characteristic data, position information and unsteady pressure change rate of the high pressure gradient unit.

9. A single-working-condition internal force calculation system based on finite element method, used to execute the method according to any one of claims 1 to 8, characterized in that: The system comprises: A structure-thermal coupling solution module is used to input the single working condition transmitted by the control center into a preset finite element model, obtain the strain data, temperature data and material evolution state variable data of each unit in the structural domain by performing a structure-thermal coupling numerical solution based on the single working condition on the preset finite element model; A structural inherent force calculation module is used to obtain a preset strain-displacement matrix and a preset heat transfer coefficient in a preset finite element model, and calculate the structural inherent force based on the strain data, temperature data, material evolution state variable data, the preset strain-displacement matrix, the preset heat transfer coefficient, and the preset structural inherent force calculation formula; a fluid-solid coupling solution module, configured to obtain pressure field data, velocity field data, multi-time-step pressure sequence data, and local frequency response characteristic data of each unit in the fluid domain by performing fluid-solid coupling solution based on the single working condition of a preset finite element model, and calculate the fluid force based on the pressure field data, velocity field data, multi-time-step pressure sequence data, local frequency response characteristic data, and a preset fluid force calculation formula; A structural dynamics solution module is used to obtain the acceleration, velocity, local deformation and local rotation data of each node in the structural domain by performing structural dynamics solution based on the single working condition of the preset finite element model; The total internal force calculation module is used to obtain the preset shape function matrix, the preset mass matrix and the preset damping matrix in the preset finite element model, calculate the structural dynamic additional force according to the acceleration, velocity, local deformation, local rotation data, the preset shape function matrix, the preset mass matrix, the preset damping matrix and the preset structural dynamic additional force calculation formula, and obtain the total internal force according to the structural inherent force, the fluid force and the structural dynamic additional force.

10. An electronic device comprising: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 8.

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