A method and device for calibrating the effective bearing capacity of high-temperature slender thin-walled pipes

Abstract

The application provides a high-temperature slender thin-walled pipe effective bearing capacity calibration method and device, and relates to the technical field of thin-walled pipe bearing capacity calibration. The method is based on the thickness-length ratio, diameter-length ratio and the ratio of high-temperature yield strength and elastic modulus of the material, constructs a geometric-material coupling dimensionless composite characteristic parameter, so that the slender degree, thin-walled degree and high-temperature material deformation characteristics of the pipe material can be comprehensively characterized in the same parameter, the scale difference caused by different geometric sizes and material systems is reduced, and a unified basis is provided for the bearing capacity comparison of different specifications of high-temperature slender thin-walled pipes. At the same time, based on the linear matching method, the stable limit load multiplier and the ratchet limit load multiplier under different load conditions are determined respectively, and the bearing capacity calibration relationship between the composite characteristic parameters is established.

Description

Technical Field

[0001] This application relates to the field of thin-walled tube load-bearing capacity calibration technology, and more specifically, to a method and apparatus for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube. Background Technology

[0002] High-temperature slender thin-walled tubes are widely used in nuclear power, petrochemical and other fields. Under long-term high temperature and cyclic load, they are prone to plastic deformation accumulation, stability failure or ratchet failure. Therefore, it is necessary to accurately assess their effective load-bearing capacity to ensure the service safety of the pipeline structure.

[0003] Current load-bearing capacity assessment methods typically rely on analytical calculations, experiments, or cyclic incremental finite element analysis, which suffer from limited applicability, high computational cost, and convergence difficulties. For pipes with different geometries and material properties, separate modeling and calculations are often required, and the results are difficult to compare directly. Furthermore, existing methods struggle to balance stability limits and ratcheting limits, affecting the efficiency and accuracy of batch pipe load-bearing capacity assessments. Summary of the Invention

[0004] This application provides at least one method and apparatus for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube.

[0005] In a first aspect, embodiments of this application provide a method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube, including:

[0006] Multiple sets of basic parameter combinations are set for high-temperature slender thin-walled tubes, and each set of basic parameter combinations includes geometric characteristic parameters and material property parameters; Based on the product of the ratio of wall thickness to total pipe length, the ratio of outer diameter to total pipe length, and the ratio of yield strength to elastic modulus of the material at the preset service temperature in each group of basic parameter combinations, the dimensionless composite characteristic parameters of geometry-material coupling are determined. For each set of basic parameter combinations corresponding to high-temperature slender thin-walled tubes, the elastic stress fields under multiple preset load conditions are obtained, and the stability limit load multiplier and ratchet limit load multiplier under each preset load condition are determined based on the linear matching method. For each of the preset load conditions, based on the geometric-material coupling dimensionless composite characteristic parameters and their corresponding stability limit load multipliers and ratchet limit load multipliers under the preset load conditions, a corresponding bearing capacity calibration relationship is established. Obtain the geometric characteristic parameters, material property parameters, target load conditions and reference load of the high-temperature slender thin-walled tube to be calibrated, and determine the target composite characteristic parameters according to the determination method of the dimensionless composite characteristic parameters of the geometry-material coupling. Select the corresponding bearing capacity calibration relationship according to the target load condition, determine the target stability limit load multiplier and the target ratchet limit load multiplier based on the target composite characteristic parameters, and determine the effective bearing capacity boundary of the high temperature slender thin-walled tube to be calibrated in combination with the reference load.

[0007] In one optional embodiment, the geometric feature parameters include the total length of the pipe, the outer diameter, and the wall thickness, and the material performance parameters include the yield strength and elastic modulus of the material at the preset service temperature; The ratio of the total length of the high-temperature slender thin-walled tube to its outer diameter is not less than 20, and the ratio of its wall thickness to its outer diameter is not greater than 0.1. The determination of the dimensionless composite characteristic parameters of the geometry-material coupling includes: determining the product of the ratio of the wall thickness to the total length of the pipe, the ratio of the outer diameter to the total length of the pipe, and the ratio of the yield strength to the elastic modulus, and performing an order of magnitude correction on the product to obtain the dimensionless composite characteristic parameters of the geometry-material coupling.

[0008] In one optional implementation, obtaining the elastic stress field under multiple preset load conditions includes: Based on the combination of basic parameters described in each group, establish the corresponding high-temperature slender thin-walled tube finite element model; Preset boundary conditions are applied to the finite element model of the high-temperature slender thin-walled tube, and linear elastic finite element analysis is performed on the finite element model of the high-temperature slender thin-walled tube using the elastic parameters of the material at the preset service temperature to obtain the elastic stress field corresponding to each load moment under each preset load condition. Each of the preset load conditions includes a constant axial load component and a cyclic axial load component. The constant axial load component is set according to the preset multiple of the ultimate axial load of the corresponding high-temperature slender thin-walled tube finite element model under the preset static axial compression condition.

[0009] In one optional implementation, determining the stability limit load multiplier under each of the preset load conditions based on the linear matching method includes: The current true stress is determined based on the elastic stress field amplified by the current load multiplier and the current residual stress. Based on the current actual stress, the yield state of each material integration point is determined according to the Mises yield criterion, and for the material integration point where yielding occurs, the plastic strain increment is determined according to the correlation flow rule. The equivalent shear modulus is updated based on the ratio of the material's yield strength to the equivalent strain corresponding to the plastic strain increment, and the material stiffness matrix is ​​updated based on the updated equivalent shear modulus. Based on the updated material stiffness matrix, a linear elastic solution is performed to update the residual stress and the actual stress. Update the current load multiplier, and repeatedly determine the plastic strain increment, update the equivalent shear modulus, perform the linear elastic solution, and update the residual stress until the load multiplier change, equivalent shear modulus change, and residual stress change between adjacent iteration steps satisfy the corresponding preset convergence conditions. The converged load multiplier is then determined as the stability limit load multiplier. Among them, the converged residual stress constitutes a self-equilibrium residual stress field that satisfies the structural equilibrium condition under zero external load.

[0010] In one optional implementation, determining the ratchet ultimate load multiplier under each preset load condition based on the linear matching method includes: The elastic stress field corresponding to the preset load condition is divided into the elastic stress field corresponding to the constant axial load component and the elastic stress field corresponding to the cyclic axial load component. Based on the elastic stress field corresponding to the cyclic axial load component, the variable residual stress and plastic strain increment at each load moment within a single load cycle are iteratively determined until the variable residual stress satisfies the periodic closure condition where the beginning and end of the cycle are equal. Based on the converged variable residual stress and plastic strain increment, the elastic stress field corresponding to the constant axial load component is superimposed, and the load multiplier corresponding to the constant axial load component is adjusted. For each adjusted load multiplier, the average cumulative plastic strain rate is determined based on the sum of plastic strain increments over multiple load cycles, the number of load cycles, and the duration of a single load cycle. The load multiplier corresponding to the change of the average cumulative plastic strain rate from zero to a positive value is then determined as the ratchet limit load multiplier.

[0011] In one optional implementation, establishing a corresponding bearing capacity calibration relationship for each of the preset load conditions includes: For each of the preset load conditions, polynomial fitting is performed on each of the geometric-material coupling dimensionless composite characteristic parameters and the corresponding stability limit load multiplier under the preset load conditions to establish a first mapping relationship between the geometric-material coupling dimensionless composite characteristic parameters and the stability limit load multiplier. For each of the preset load conditions, a polynomial fitting is performed on each of the geometry-material coupling dimensionless composite characteristic parameters and the corresponding ratchet limit load multiplier under the preset load conditions to establish a second mapping relationship between the geometry-material coupling dimensionless composite characteristic parameters and the ratchet limit load multiplier. Based on the first mapping relationship and the second mapping relationship, a load-bearing capacity calibration map including the stability limit boundary and the ratchet limit boundary is generated, with the geometry-material coupling dimensionless composite characteristic parameter as the abscissa and the stability limit load multiplier and the ratchet limit load multiplier as the ordinate.

[0012] In one optional implementation, the reference load is the ultimate axial load of the high-temperature slender thin-walled tube to be calibrated under a preset static axial compression condition. The determination of the effective load-bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated, in conjunction with the reference load, includes: The reference load is multiplied by the target stability limit load multiplier and the target ratchet limit load multiplier, respectively, to obtain the stability limit load and ratchet limit load of the high-temperature slender thin-walled tube to be calibrated. The smaller of the stability limit load and the ratchet limit load is determined as the critical failure load, and the critical failure load is used as the effective bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated. The method further includes: dividing the critical failure load by a preset safety factor to obtain the safe working load of the high-temperature slender thin-walled tube to be calibrated.

[0013] Secondly, embodiments of this application also provide a device for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube, comprising: The setting module is used to set multiple sets of basic parameter combinations for high-temperature slender thin-walled tubes. Each set of basic parameter combinations includes geometric characteristic parameters and material performance parameters. The first determining module is used to determine the dimensionless composite characteristic parameters of geometry-material coupling based on the product of the ratio of wall thickness to total pipe length, the ratio of outer diameter to total pipe length, and the ratio of yield strength to elastic modulus of the material at a preset service temperature in each group of basic parameter combinations. The second determining module is used to obtain the elastic stress field under multiple preset load conditions for each high-temperature slender thin-walled tube corresponding to the basic parameter combination of each group, and to determine the stability limit load multiplier and ratchet limit load multiplier under each preset load condition based on the linear matching method. A module is established to establish a corresponding load-bearing capacity calibration relationship for each preset load condition based on the geometric-material coupling dimensionless composite characteristic parameters and their corresponding stability limit load multipliers and ratchet limit load multipliers under the preset load conditions. The acquisition module is used to acquire the geometric characteristic parameters, material performance parameters, target load conditions and reference load of the high-temperature slender thin-walled tube to be calibrated, and to determine the target composite characteristic parameters according to the determination method of the dimensionless composite characteristic parameters of the geometry-material coupling. The calibration module is used to select the corresponding bearing capacity calibration relationship according to the target load condition, determine the target stability limit load multiplier and the target ratchet limit load multiplier based on the target composite characteristic parameters, and determine the effective bearing capacity boundary of the high temperature slender thin-walled tube to be calibrated in combination with the reference load.

[0014] In one optional embodiment, the geometric feature parameters include the total length of the pipe, the outer diameter, and the wall thickness, and the material performance parameters include the yield strength and elastic modulus of the material at the preset service temperature; The ratio of the total length of the high-temperature slender thin-walled tube to its outer diameter is not less than 20, and the ratio of its wall thickness to its outer diameter is not greater than 0.1. The first determining module is specifically used to: determine the product of the ratio of the wall thickness to the total length of the pipe, the ratio of the outer diameter to the total length of the pipe, and the ratio of the yield strength to the elastic modulus, and perform an order of magnitude correction on the product to obtain the dimensionless composite characteristic parameters of the geometry-material coupling.

[0015] In one optional implementation, the second determining module is specifically used for: Based on the combination of basic parameters described in each group, establish the corresponding high-temperature slender thin-walled tube finite element model; Preset boundary conditions are applied to the finite element model of the high-temperature slender thin-walled tube, and linear elastic finite element analysis is performed on the finite element model of the high-temperature slender thin-walled tube using the elastic parameters of the material at the preset service temperature to obtain the elastic stress field corresponding to each load moment under each preset load condition. Each of the preset load conditions includes a constant axial load component and a cyclic axial load component. The constant axial load component is set according to the preset multiple of the ultimate axial load of the corresponding high-temperature slender thin-walled tube finite element model under the preset static axial compression condition.

[0016] In one optional implementation, the second determining module is specifically used for: The current true stress is determined based on the elastic stress field amplified by the current load multiplier and the current residual stress. Based on the current actual stress, the yield state of each material integration point is determined according to the Mises yield criterion, and for the material integration point where yielding occurs, the plastic strain increment is determined according to the correlation flow rule. The equivalent shear modulus is updated based on the ratio of the material's yield strength to the equivalent strain corresponding to the plastic strain increment, and the material stiffness matrix is ​​updated based on the updated equivalent shear modulus. Based on the updated material stiffness matrix, a linear elastic solution is performed to update the residual stress and the actual stress. Update the current load multiplier, and repeatedly determine the plastic strain increment, update the equivalent shear modulus, perform the linear elastic solution, and update the residual stress until the load multiplier change, equivalent shear modulus change, and residual stress change between adjacent iteration steps satisfy the corresponding preset convergence conditions. The converged load multiplier is then determined as the stability limit load multiplier. Among them, the converged residual stress constitutes a self-equilibrium residual stress field that satisfies the structural equilibrium condition under zero external load.

[0017] In one optional implementation, the second determining module is specifically used for: The elastic stress field corresponding to the preset load condition is divided into the elastic stress field corresponding to the constant axial load component and the elastic stress field corresponding to the cyclic axial load component. Based on the elastic stress field corresponding to the cyclic axial load component, the variable residual stress and plastic strain increment at each load moment within a single load cycle are iteratively determined until the variable residual stress satisfies the periodic closure condition where the beginning and end of the cycle are equal. Based on the converged variable residual stress and plastic strain increment, the elastic stress field corresponding to the constant axial load component is superimposed, and the load multiplier corresponding to the constant axial load component is adjusted. For each adjusted load multiplier, the average cumulative plastic strain rate is determined based on the sum of plastic strain increments over multiple load cycles, the number of load cycles, and the duration of a single load cycle. The load multiplier corresponding to the change of the average cumulative plastic strain rate from zero to a positive value is then determined as the ratchet limit load multiplier.

[0018] In one optional implementation, the establishment module is specifically used for: For each of the preset load conditions, polynomial fitting is performed on each of the geometric-material coupling dimensionless composite characteristic parameters and the corresponding stability limit load multiplier under the preset load conditions to establish a first mapping relationship between the geometric-material coupling dimensionless composite characteristic parameters and the stability limit load multiplier. For each of the preset load conditions, a polynomial fitting is performed on each of the geometry-material coupling dimensionless composite characteristic parameters and the corresponding ratchet limit load multiplier under the preset load conditions to establish a second mapping relationship between the geometry-material coupling dimensionless composite characteristic parameters and the ratchet limit load multiplier. Based on the first mapping relationship and the second mapping relationship, a load-bearing capacity calibration map including the stability limit boundary and the ratchet limit boundary is generated, with the geometry-material coupling dimensionless composite characteristic parameter as the abscissa and the stability limit load multiplier and the ratchet limit load multiplier as the ordinate.

[0019] In one optional implementation, the reference load is the ultimate axial load of the high-temperature slender thin-walled tube to be calibrated under a preset static axial compression condition. The calibration module is specifically used for: The reference load is multiplied by the target stability limit load multiplier and the target ratchet limit load multiplier, respectively, to obtain the stability limit load and ratchet limit load of the high-temperature slender thin-walled tube to be calibrated. The smaller of the stability limit load and the ratchet limit load is determined as the critical failure load, and the critical failure load is used as the effective bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated. The calibration module is also used to: divide the critical failure load by a preset safety factor to obtain the safe working load of the high-temperature slender thin-walled tube to be calibrated.

[0020] Thirdly, an optional implementation of this application also provides a computer device, including a processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and the processor is used to execute the machine-readable instructions stored in the memory. When the machine-readable instructions are executed by the processor, they perform the steps of the first aspect above, or any possible implementation of the first aspect.

[0021] Fourthly, an optional implementation of this application also provides a computer-readable storage medium storing a computer program that, when run, performs the steps of the first aspect or any possible implementation of the first aspect.

[0022] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this application.

[0023] The method and apparatus for calibrating the effective load-bearing capacity of high-temperature slender thin-walled tubes provided in this application construct a geometry-material coupled dimensionless composite characteristic parameter based on the thickness-to-length ratio, diameter-to-length ratio, and the ratio of the material's high-temperature yield strength to its elastic modulus. This allows the slenderness, thinness, and high-temperature material deformation characteristics of the tube to be comprehensively characterized within the same parameter, reducing dimensional differences caused by different geometric dimensions and material systems, and providing a unified basis for comparing the load-bearing capacity of high-temperature slender thin-walled tubes of different specifications. Simultaneously, based on the linear matching method, the stable ultimate load multiplier and ratchet ultimate load multiplier under different load conditions are determined, and a load-bearing capacity calibration relationship is established between them and the composite characteristic parameter. Therefore, for the tube to be calibrated, the corresponding stable and ratchet failure boundaries can be obtained according to its composite characteristic parameter and target load condition, reducing the computational workload of repeatedly performing complex cyclic plasticity analysis, and taking into account different failure modes, thus improving the efficiency, completeness, and reliability of the effective load-bearing capacity assessment.

[0024] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. These drawings are incorporated in and constitute a part of this specification. They illustrate embodiments conforming to this application and, together with the specification, serve to explain the technical solutions of this application. It should be understood that the following drawings only show some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 The flowchart illustrates a method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube according to some embodiments of this application; Figure 2 A schematic diagram of a high-temperature slender thin-walled tube provided in some embodiments of this application is shown; Figure 3 A schematic diagram illustrating the variation of mechanical load over time provided in some embodiments of this application is shown; Figure 4 Schematic diagrams of stability limit boundaries and ratchet limit boundaries provided in some embodiments of this application are shown; Figure 5 This illustration shows the ultimate load-bearing capacity of high-temperature slender thin-walled tubes under different geometric and material coupling characteristics provided in some embodiments of this application; Figure 6 This document illustrates a flowchart of another method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube, provided in some embodiments of this application. Figure 7 A flowchart illustrating the stability analysis provided in some embodiments of this application is shown; Figure 8 A schematic diagram of a high-temperature slender thin-walled tube effective load-bearing capacity calibration device provided in some embodiments of this application is shown; Figure 9 A schematic diagram of a computer device provided in some embodiments of this application is shown. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown herein can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] Research has revealed that existing load-bearing capacity assessment methods typically rely on analytical calculations, experiments, or cyclic incremental finite element analysis, which suffer from limited applicability, high computational complexity, and convergence difficulties. For pipes with different geometries and material properties, separate modeling and calculations are often required, making direct comparison of results difficult. Furthermore, existing methods struggle to balance stability limits and ratcheting limits, impacting the efficiency and accuracy of batch pipe load-bearing capacity assessments.

[0029] Based on the above research, this application provides a method and apparatus for calibrating the effective load-bearing capacity of high-temperature slender thin-walled tubes. The geometric characteristics and high-temperature material properties of the tube are uniformly characterized by a dimensionless composite characteristic parameter coupled with geometry and materials. The calibration relationship between the composite characteristic parameter and the stability and ratchet limit load multipliers is established by combining linear matching analysis. This enables the rapid determination of the effective load-bearing capacity boundary of tubes of different specifications, reduces redundant modeling calculations, and improves the consistency, efficiency and reliability of cross-size and cross-material evaluations.

[0030] The shortcomings of the above solutions are the result of the inventor's practical experience and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this application below should be considered as the inventor's contributions to this application.

[0031] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0032] To facilitate understanding of this embodiment, a detailed description of the method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube disclosed in this application embodiment will be provided first. The executing entity of the method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube provided in this application embodiment is generally a computer device with certain computing capabilities. This computer device may include, for example, a terminal device, a server, or other processing devices. In some possible implementations, the method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube can be implemented by a processor calling computer-readable instructions stored in memory.

[0033] The following describes the method for calibrating the effective load-bearing capacity of high-temperature slender thin-walled tubes provided in this application, using a server as the execution subject as an example. This embodiment takes homogeneous high-temperature slender thin-walled tubes such as nuclear power plant heat exchange tubes and petrochemical high-temperature process pipelines as examples. By setting multiple sets of geometric characteristic parameters and material performance parameters, a dimensionless composite characteristic parameter with geometric-material coupling is constructed. A linear matching method is then used to determine the stability limit load multiplier and the ratchet limit load multiplier, thereby establishing the load-bearing capacity calibration relationship.

[0034] See Figure 1 The diagram shows a flowchart of a method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube according to an embodiment of this application. The method includes steps S101 to S106, wherein: S101. Set multiple sets of basic parameter combinations for high-temperature slender thin-walled tubes, each set of basic parameter combinations including geometric characteristic parameters and material performance parameters.

[0035] The high-temperature slender thin-walled tube in this application refers to a tube with a hollow tubular structure that operates at a preset service temperature and whose geometry meets specific conditions. "High temperature" refers to the preset service temperature used to determine the material performance parameters; that is, this application uses the yield strength and elastic modulus of the material at this preset service temperature to calibrate its load-bearing capacity, rather than using the corresponding performance parameters of the material at room temperature. For example, the preset service temperature can be 600℃~700℃.

[0036] For example, in combination Figure 2 As shown, the geometric characteristic parameters of high-temperature slender thin-walled tubes can include the total length of the tube. , outer diameter , inner diameter and wall thickness . Figure 2 In this context, F represents the axial load, which can include a constant axial load component and a cyclic axial load component. The wall thickness... It can be based on the outer diameter With inner diameter Half of the difference is determined. High-temperature, slender, thin-walled tubes can meet the following criteria:

[0037]

[0038] in, Used to characterize the slenderness of pipes. These values ​​are used to characterize the thinness of the pipe walls. The values ​​described above are used to define the slender, thin-walled structure in this embodiment and do not constitute a limitation on the specific dimensions of the pipe.

[0039] Multiple sets of geometric feature parameters can be formed by using equal intervals, orthogonal combination, random selection, or other parameterized selection methods, based on a pre-defined range of pipe dimensions.

[0040] Material performance parameters may include the yield strength of the material at a preset service temperature. and elastic modulus When thermal analysis is required, material performance parameters may also include density, specific heat capacity, thermal conductivity, and coefficient of thermal expansion.

[0041] In one implementation, the material employs an ideal elastic-plastic model (EPP model) with a preset elastic modulus at the service temperature. and yield strength Describe the elastic and yield stages of the material. Optionally, when it is necessary to consider the nonlinear strengthening properties of the material after yielding, the Ramberg-Osgood model (RO model) or other cyclic plastic constitutive models can be used.

[0042] For each set of basic parameter combinations, corresponding preset load conditions are set. The preset load conditions include a constant axial load component and a cyclic axial load component. The constant axial load component can be denoted as... The cyclic axial load component that varies periodically with time is denoted as... The two are then superimposed to form the axial load borne by the high-temperature, slender, thin-walled tube. See also Figure 3 As shown, Figure 3 The mechanical load (i.e.) is shown in the figure. and A graph showing how the graph changes over time.

[0043] The cyclic axial load component can take the form of a triangular wave, sine wave, trapezoidal wave, or other periodic loads. A single load cycle can be divided into... There are 1 load point, and each load point corresponds to a load time. The load point can include the moment when the cyclic load reaches its maximum value, the moment when the load reaches its minimum value, and the moment when the loading direction changes.

[0044] The constant axial load component can be set according to a preset multiple of the reference load for the corresponding high-temperature slender thin-walled tube. For example, the initial constant axial load can be taken as a fraction of the ultimate axial load. Times, and superimposed cyclic axial load. The reference load can be determined based on the cross-sectional dimensions of the high-temperature slender thin-walled tube and the yield strength at the preset service temperature, or it can be determined through limit analysis, design specifications, or pre-conducted finite element analysis.

[0045] Each preset load condition can correspond to a predetermined proportional loading path. This proportional loading path is used to define the proportional relationship between the constant axial load component and the cyclic axial load component, and the subsequently obtained load multiplier is used to amplify the overall load along this proportional loading path.

[0046] This embodiment primarily uses the isothermal mechanical load condition at a preset service temperature as an example, where the preset service temperature is mainly used to determine the corresponding material performance parameters. In another optional embodiment, when there is a temperature gradient or periodic temperature change inside the tube, a corresponding thermal load can be set, and a thermo-mechanical coupling analysis can be performed.

[0047] S102. Based on the product of the ratio of wall thickness to total pipe length, the ratio of outer diameter to total pipe length, and the ratio of yield strength to elastic modulus of the material at the preset service temperature in each group of basic parameter combinations, determine the dimensionless composite characteristic parameters of geometry-material coupling.

[0048] Based on the ratios of wall thickness to total pipe length, outer diameter to total pipe length, and yield strength to elastic modulus in each set of basic parameter combinations, the corresponding dimensionless composite characteristic parameters of geometry-material coupling are determined. :

[0049] in, These are dimensionless composite characteristic parameters of geometry-material coupling; The thickness-to-length ratio; The aspect ratio; This represents the yield strength of the material at a preset service temperature. This refers to the elastic modulus of the material at a preset service temperature. This is a magnitude correction factor used to adjust composite characteristic parameters to a numerical range suitable for engineering applications. This magnitude correction factor can be adjusted according to actual conditions. As an example, composite characteristic parameters... The value can range from 0.1 to 10.

[0050] The magnitude correction factor is only used to adjust the numerical magnitude of the composite characteristic parameters and does not change the coupling relationship between the geometric characteristic parameters and the material performance parameters. The same magnitude correction method is used for all combinations of basic parameters in the same load-bearing capacity calibration relationship and for the high-temperature slender thin-walled tube to be calibrated.

[0051] The ratio of wall thickness to total pipe length characterizes the change in wall thickness relative to the axial dimension of the pipe; the ratio of outer diameter to total pipe length characterizes the change in radial dimension relative to the axial dimension; and the ratio of yield strength to elastic modulus characterizes the relative deformation capacity of the material as it transitions from an elastic to a plastic state. Therefore, the dimensionless composite characteristic parameters of the geometry-material coupling can simultaneously reflect the coupled influence of geometric dimensions and high-temperature material properties on cyclic load-bearing capacity.

[0052] S103. For each high-temperature slender thin-walled tube corresponding to the basic parameter combination, obtain the elastic stress field under multiple preset load conditions, and determine the stability limit load multiplier and ratchet limit load multiplier under each preset load condition based on the linear matching method.

[0053] For each combination of basic parameters, a corresponding finite element model of a high-temperature slender thin-walled tube is established. This model can be based on the total length of the tube. , outer diameter and inner diameter Establish a geometric model of the tube. Utilizing the symmetry of the circular tube structure, a half-symmetric model can be established; a complete tube model can also be established when the symmetry condition is not met or when a complete stress distribution is required.

[0054] In one embodiment, a discrete tube structure using three-dimensional 20-node quadratic solid elements (C3D20R) is employed, with four layers of structured mesh set in the wall thickness direction, and mesh refinement applied to the loading region at the tube end and the region of expected stress concentration. Mesh quality can be checked based on the degree of element distortion and the Jacobian determinant.

[0055] In one embodiment, the end face node of the fixed end of the tube is coupled to a first reference point, and the end face node of the loading end is coupled to a second reference point; the translational and rotational degrees of freedom are constrained at the first reference point, and only the axial translational degree of freedom is retained at the second reference point, and the axial load is applied through the second reference point.

[0056] Optionally, when directly constraining the end face nodes of the C3D20R solid element without setting a reference point, only the translational degrees of freedom of the end face nodes can be constrained, and the rotational degrees of freedom that the solid element nodes do not have can be set.

[0057] Preset boundary conditions and preset load conditions are applied to the finite element model. Using the elastic parameters of the material at the preset service temperature, linear elastic finite element analysis is performed at each load moment within a single load cycle to obtain the corresponding elastic stress field.

[0058] The linear matching method (LMM) is used to transform the cyclic plastic nonlinear problem into a series of linear elastic problems for iterative solution. The true stress field across the entire structure is expressed as:

[0059] in, This represents the true stress field across the entire structure. For load multipliers; This represents the linear elastic stress field corresponding to the alternating load. It is a self-balancing residual stress field used to compensate for the difference between elastic stress and material yield and plastic deformation.

[0060] For stability analysis, when external load and thermal load When the load changes cyclically according to a fixed period, if the residual stress does not change after a single load cycle, that is... The increase in plastic strain generated within the period To harmonize the strain field and satisfy the corresponding zero displacement boundary conditions.

[0061] In a cycle Within this range, the total strain increment satisfies:

[0062] in, The total strain increment tensor component over one load cycle; These are the elastic strain increment tensor components; For the plastic strain increment tensor components. and These are tensor component indices, corresponding to the coordinate directions in three-dimensional space. Elastic strain recovers after the cycle ends; therefore, the total strain increment per cycle is characterized by the unrecovered plastic strain increment.

[0063] The plastic strain increment satisfies the following geometric compatibility relationship:

[0064] in, The first of the plastic displacement increments Directional components; The first of the plastic displacement increments Directional components; For the first Spatial coordinates of direction; For the first Spatial coordinates of direction.

[0065] The plastic strain rate and the plastic strain increment satisfy the following relationship:

[0066] in, These are the components of the plastic strain rate tensor. It is a time infinitesimal element.

[0067] According to the upper bound theorem of stability, the plastic dissipation work inside the structure... Represented as:

[0068] During cyclic loading, the work done by the external load on the structure. Represented as:

[0069] in, For external loads that vary with time, For the corresponding displacement rate, The stress component is conjugate to the plastic strain rate.

[0070] The critical work balance relationship for a structure to reach a stable state is expressed as:

[0071] in, This is the upper bound of the stable load multiplier, representing the minimum load multiplier at which the structure loses its stable state; These are the components of the linear elastic stress field tensor.

[0072] The equivalent plastic strain rate is expressed as:

[0073] By combining the von Mises yield criterion and the associated plastic flow law, we obtain the stable upper limit load multiplier:

[0074] in, This represents the yield strength of the material.

[0075] In the linear matching iteration, the strain rate deviator and the stress deviator satisfy the following:

[0076] in, For the first The strain rate bias component of the iteration step; superscript " " indicates the partial component of the tensor; For the first The residual stress field of the iteration step; The equivalent shear modulus after iterative updates, satisfying:

[0077] in, For the first The equivalent strain corresponding to the iteration step.

[0078] For the iterative determination of the stability limit load multiplier, in the initial iteration step For the load variation region Initial values ​​are assigned to the elastic stress solution at each load vertex:

[0079] in, The first result obtained through linear elastic finite element analysis under external load. The elastic stress tensor components corresponding to each load vertex; ext "" indicates the linear elastic stress solution corresponding to the external load.

[0080] And order:

[0081] In the In the next iteration, the load multiplier is updated as follows:

[0082] Load variation region The equivalent shear modulus at each load vertex is expressed as:

[0083] in:

[0084] The above For the first Iteration step, the first The strain increment tensor components at each load vertex.

[0085] The overall equivalent compliance parameter is expressed as:

[0086] in, The total number of vertices in the load variation region. For the first The overall equivalent shear modulus of the iteration step.

[0087] Depend on Determine the Jacobian matrix Jacobian matrix This is the material tangent stiffness matrix in the UserMaterial (UMAT) subroutine that describes the relationship between stress and strain increments.

[0088] To reflect the incompressibility condition under plastic deformation, in one implementation, Poisson's ratio is set to 0.5. Alternatively, when the finite element solver is not suitable for directly using the completely incompressible parameter, the Poisson's ratio can be set to a value slightly less than 0.5, or an element or solution method suitable for incompressible materials can be used.

[0089] Define the weighted combined stress term:

[0090] The constant residual stress field is expressed as:

[0091] No. The strain increment at each load peak is expressed as:

[0092] in, According to A defined compliance matrix; For the first Iteration step, the first The strain increment tensor components at each load peak for Iteration step, for the load variation region Initial values ​​are assigned to the elastic stress solution at each load vertex.

[0093] Based on the equivalent strain increment at each Gaussian integration point, the corresponding volume integral term is extracted from the finite element energy output file, and the stability upper limit load multiplier for the next iteration step is determined:

[0094] in, No. Step, First Equivalent strain at each load vertex.

[0095] The above iterative process generates a series of gradually converging load multipliers. This iteration continues until a preset convergence condition is met, and the final convergence value is denoted as... Stable ultimate load multiplier Represented as:

[0096] In one engineering implementation, a load multiplier can be introduced. Its initial value is taken as 0.1, and the residual stress field is... The initial value is 0. The linear matching condition of the finite element integration points is expressed as:

[0097] in, The equivalent elastic modulus at the finite element integration point after iterative correction. This is the original elastic modulus of the material. It is modified... This ensures that the actual stress satisfies the Mises yield criterion.

[0098] In the above linear matching conditions, Used to represent the true stress characterization quantity involved in Mises yield matching.

[0099] Preset convergence criteria can include all integration points in adjacent iteration steps. The relative difference is no greater than 1%. Optionally, it can also be determined whether the change in load multiplier, residual stress field or plastic strain increment in adjacent iteration steps is no greater than the corresponding threshold.

[0100] After iterative convergence, the residual stress field is expressed as:

[0101] The self-equilibrium state of the residual stress field is verified using the following relationship:

[0102] in, This refers to the volume region occupied by the high-temperature, slender, thin-walled tube structure.

[0103] Optionally, it can also be checked whether the residual stress field satisfies the internal equilibrium conditions of the structure, and whether the resultant residual stress at the boundary surface, the overall residual force, and the overall residual moment are less than the corresponding thresholds, so as to further verify the self-equilibrium state of the residual stress field.

[0104] The first yielding at a finite element integration point only indicates that the structure has reached or exceeded the elastic limit, and is not directly equivalent to reaching the stability limit. The stability limit is determined based on whether a time-invariant self-equilibrium residual stress field satisfying the yield condition can be formed through the above iterations.

[0105] To determine the ratchet limit load multiplier, the cyclic stress field is decomposed into constant load components. and cyclic load components The linear matching method-direct steady-state cycle analysis (LMM-DSCA) is employed to determine the ratchet limit load multiplier through a two-step minimization calculation.

[0106] The first step is to solve for the evolution of residual stress and plastic strain of the structure under cyclic loading; the second step is to superimpose constant load components and solve for the maximum additional constant load that the structure can withstand.

[0107] In an alternative implementation considering thermo-mechanical coupled loads, the linear elastic stress field is expressed as:

[0108] in, For mechanical load multipliers; For each individual mechanical load, the linear elastic stress tensor component is represented. For thermal load multipliers; For each individual thermal load, the linear elastic stress tensor component is represented. These are spatial coordinate components; For time.

[0109] Assuming the material satisfies the Drucker stability condition, under cyclic loading, the stress and strain rate of the structure tend to reach a steady cyclic state. The total cyclic steady-state stress field is expressed as:

[0110] in, It is the loading factor; It is a constant residual stress field that does not change with time; It is a variable residual stress field that evolves dynamically over time within a single period.

[0111] The variable residual stress field satisfies the following periodic boundary conditions:

[0112] in, Duration of a single load cycle; This is a constant term for the variable residual stress field.

[0113] Based on the EPP model or RO model, the LMM-DSCA method is used to solve for residual stress and plastic strain. The load point, the first The partial form of the incremental equation for the iteration step is expressed as:

[0114] in, This represents the total strain increment offset. This represents the residual stress increment bias. This represents the plastic strain increment.

[0115] The incremental equation can be expressed in spherical or volumetric form as follows:

[0116] in, Bulk modulus of the material; The spherical portion of the total strain increment; This is the spherical portion of the residual stress increment.

[0117] The increment of plastic strain deviator is expressed as:

[0118] in, For the first The load point, the first The equivalent shear modulus of the iteration step; For the cyclic load component in Stress deviation at time; for The deviance of the accumulated residual stress at any given time.

[0119] Loading time point The cumulative residual stress at the point is expressed as:

[0120] in, For the first The residual stress increment for each load step.

[0121] Set the total number of loops. and the number of load points per cycle ,in, Indicates the first The loop, the first The variable residual stress increments correspond to each load point. When the iteration converges, the sum of the variable residual stress increments within a single period is zero. After the iteration is complete, the constant residual stress field is expressed as:

[0122] Load point The plastic strain amplitude at the point is expressed as:

[0123] in, For the first The iterative shear modulus corresponding to each load point; for The cumulative residual stress at any given time.

[0124] After obtaining the convergent residual stress field and plastic strain, the ratchet ultimate load multiplier... Represented as:

[0125] in, The linear elastic stress is the component of the cyclic load. Linear elastic stress for a constant load component; For the first The equivalent variable increment at each load point. The iterative process generates gradually converging... The final convergence value is used as the ratchet limit load multiplier.

[0126] The average cumulative plastic strain rate is expressed as:

[0127] in, This represents the average cumulative plastic strain rate. This is the sum of the plastic strain increments across multiple cycles; This represents the number of loop iterations. For a single cycle period.

[0128] when When the structure is determined to have ratchet failure, the load multiplier corresponding to the change of the average cumulative plastic strain rate from zero to a positive value is determined as the ratchet limit load multiplier.

[0129] In one implementation, for the same set of basic parameter combinations, the constant axial load component and the cyclic axial load component are adjusted separately, and the critical load combinations at which the structure reaches the stability limit and ratchet limit are determined according to the aforementioned linear matching analysis. For example... Figure 4 As shown, with the constant axial load component as the abscissa and the cyclic axial load component as the ordinate, the critical loads that reach the stability limit are combined and connected to form the stability limit boundary, and the critical loads that reach the ratchet limit are combined and connected to form the ratchet limit boundary.

[0130] S104. For each of the preset load conditions, based on the geometric-material coupling dimensionless composite characteristic parameters and their corresponding stability limit load multipliers and ratchet limit load multipliers under the preset load conditions, establish the corresponding load capacity calibration relationship.

[0131] For each preset load condition, the geometric-material coupled dimensionless composite characteristic parameters of each group can be associated with the corresponding stability limit load multiplier and ratchet limit load multiplier, respectively.

[0132] Polynomial fitting, piecewise function fitting, spline fitting, or interpolation can be used to establish the first mapping relationship between the composite characteristic parameters and the stability limit load multiplier, as well as the second mapping relationship between the composite characteristic parameters and the ratchet limit load multiplier.

[0133] For different constant axial load ratios, cyclic axial load amplitudes, load waveforms, or preset service temperatures, corresponding first and second mapping relationships can be established respectively.

[0134] composite feature parameters Using the horizontal axis as the abscissa and the vertical axis as the stability limit load multiplier and the ratchet limit load multiplier, a load-bearing capacity calibration map can be formed. The load-bearing capacity calibration map includes the stability limit boundary and the ratchet limit boundary, and different load-bearing state regions can be divided according to these boundaries.

[0135] S105. Obtain the geometric characteristic parameters, material performance parameters, target load conditions and reference load of the high-temperature slender thin-walled tube to be calibrated, and determine the target composite characteristic parameters according to the determination method of the dimensionless composite characteristic parameters of the geometry-material coupling.

[0136] Obtain the total length, outer diameter, wall thickness, yield strength and elastic modulus at the preset service temperature of the high-temperature slender thin-walled tube to be calibrated, and calculate the target composite characteristic parameters of the high-temperature slender thin-walled tube to be calibrated in the same way as in step S102.

[0137] Obtain the target load condition and reference load of the high-temperature slender thin-walled tube to be calibrated, and select the load capacity calibration relationship corresponding to the target load condition from multiple pre-established load capacity calibration relationships.

[0138] When the target composite characteristic parameter corresponds to an existing parameter point in the bearing capacity calibration relationship, the corresponding target stability limit load multiplier and target ratchet limit load multiplier can be directly determined; when the target composite characteristic parameter is located between adjacent parameter points, the corresponding target limit load multiplier can be determined by fitting relationship or interpolation method.

[0139] The target load condition corresponds to the preset load condition, meaning that the two use the same or equivalent constant load ratio, cyclic load amplitude, load waveform, service temperature and proportional loading path.

[0140] When the target composite characteristic parameters exceed the parameter range of the existing bearing capacity calibration relationship, corresponding basic parameter combinations can be added and the mapping relationship updated. Optionally, extrapolation can also be performed when preset extrapolation conditions are met.

[0141] S106. Select the corresponding bearing capacity calibration relationship according to the target load condition, determine the target stability limit load multiplier and the target ratchet limit load multiplier based on the target composite characteristic parameters, and determine the effective bearing capacity boundary of the high temperature slender thin-walled tube to be calibrated in combination with the reference load.

[0142] In this step, the reference load can be converted according to the target stable limit load multiplier and the target ratchet limit load multiplier to obtain the stable limit load and ratchet limit load of the high-temperature slender thin-walled tube to be calibrated.

[0143] like Figure 5 As shown, the stability limit load multiplier and ratchet limit load multiplier are converted into stability limit load and ratchet limit load respectively according to the corresponding reference load. Then, with the dimensionless composite characteristic parameter of geometry-material coupling as the abscissa and the stability limit load and ratchet limit load as the ordinate, corresponding mapping curves are formed to characterize the ultimate bearing capacity of high temperature slender thin-walled tubes under different geometric and material coupling characteristics.

[0144] When the stability limit load multiplier and the ratchet limit load multiplier are obtained along the same proportional loading path, the smaller value of the stability limit load and the ratchet limit load can be determined as the critical failure load.

[0145] The critical failure load is reduced by a preset safety factor to obtain the safe operating load for the high-temperature, slender, thin-walled tube to be calibrated. The preset safety factor can be, for example, 1.2 to 1.5.

[0146] For load conditions consisting of both constant axial load components and cyclic axial load components, a smaller ultimate load multiplier can be used to scale the corresponding proportional loading path as a whole, thereby obtaining both the critical constant axial load component and the critical cyclic axial load component simultaneously, instead of outputting only a single load value.

[0147] By comparing the safe working load with the actual working load of the high-temperature, slender, thin-walled tube to be calibrated, the load-bearing margin of the tube can be determined. When the actual working load does not exceed the safe working load, it indicates that the tube meets the preset safety requirements within the evaluation range of stability failure and ratchet failure; when the actual working load exceeds the safe working load, measures such as reducing the working load, replacing the tube, or adjusting the tube size can be taken.

[0148] Thus, by establishing the load-bearing capacity calibration relationship in advance, the stability limit and ratchet limit of the pipe can be quickly obtained based on the geometric characteristic parameters and material performance parameters of the pipe during the batch design or safety re-inspection of nuclear power heat exchange tube bundles and petrochemical multi-specification high-temperature pipelines, without having to re-perform a complete linear matching iterative analysis for each high-temperature slender thin-walled pipe to be calibrated.

[0149] The high-temperature slender thin-walled tube effective load-bearing capacity calibration method provided in this application constructs a geometry-material coupled dimensionless composite characteristic parameter based on the thickness-to-length ratio, diameter-to-length ratio, and the ratio of the material's high-temperature yield strength to its elastic modulus. This allows the tube's slenderness, thinness, and high-temperature material deformation characteristics to be comprehensively characterized within the same parameter, reducing dimensional differences caused by different geometric dimensions and material systems, and providing a unified basis for comparing the load-bearing capacity of high-temperature slender thin-walled tubes of different specifications. Simultaneously, based on the linear matching method, the stable ultimate load multiplier and ratchet ultimate load multiplier under different load conditions are determined, and a load-bearing capacity calibration relationship is established between them and the composite characteristic parameter. Therefore, for the tube to be calibrated, the corresponding stable and ratchet failure boundaries can be obtained based on its composite characteristic parameter and target load condition, reducing the computational burden of repeatedly performing complex cyclic plasticity analysis, and taking into account different failure modes, thus improving the efficiency, completeness, and reliability of effective load-bearing capacity assessment.

[0150] See Figure 6 The diagram illustrates another method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube according to an embodiment of this application. This method first sets geometric and material fundamental data (i.e., the aforementioned geometric characteristic parameters and material performance parameters), and then defines geometric parameters based on this data. The geometric parameters may include the total length of the tube, its outer diameter, inner diameter, and wall thickness; the material fundamental data may include the yield strength, elastic modulus, and Poisson's ratio of the material at a preset service temperature.

[0151] A finite element model (i.e., the aforementioned high-temperature slender thin-walled tube finite element model) is constructed based on the geometric parameters, and a thermo-mechanical coupled load (i.e., the aforementioned preset load conditions including mechanical loads and optional thermal loads) is applied to the finite element model. The mechanical load may include a constant axial load component and a cyclic axial load component. Without a thermal load, the thermo-mechanical coupled load can degenerate into a preset load condition including only mechanical loads. Further, a material model is constructed, and the thermo-mechanical coupled linear elastic stress field (i.e., the elastic stress field corresponding to each load moment under each of the aforementioned preset load conditions) is solved.

[0152] After obtaining the thermo-mechanical coupled linear elastic stress field, the outer loop is initiated, which is used to process multiple sets of parametric chemical conditions. These multiple sets of parametric chemical conditions (i.e., the aforementioned combinations of basic parameters and their corresponding preset load conditions) correspond to different geometric parameters, material fundamental data, or load combinations. The outer loop sequentially selects a set of parametric chemical conditions and inputs the finite element model, material model, and thermo-mechanical coupled linear elastic stress field corresponding to the current parametric chemical condition into the inner loop.

[0153] For the current parametric condition, the inner loop is initiated, i.e., the linear matching method iterative calculation is started. First, the initial stress of the iteration (i.e., the linear elastic stress field corresponding to each load vertex under the current parametric condition) is loaded, and load multipliers are introduced to construct the true stress formula. The true stress is determined based on the linear elastic stress field amplified by the load multipliers and the current residual stress field. Subsequently, linear matching constraints are set, and the equivalent elastic modulus at the integration point (i.e., the equivalent elastic modulus at the finite element integration point after the above iterative correction) is iteratively corrected according to the linear matching constraints. The equivalent shear modulus and material stiffness matrix are updated accordingly.

[0154] A linear elastic solution is performed based on the updated material stiffness matrix, updating the true stress, plastic strain increment, and residual stress. The current iteration result is then checked to determine if it meets the convergence criterion (i.e., the aforementioned preset convergence condition). If the convergence criterion is not met, the process returns to the step of iteratively correcting the equivalent elastic modulus at the integration point and continues with the inner loop. If the convergence criterion is met, the current inner loop ends, and the self-equilibrium residual stress field (i.e., the residual stress field that satisfies the structural equilibrium condition under zero external load) is obtained.

[0155] After obtaining the self-balancing residual stress field, two major failure analyses are performed in parallel: a stability analysis and a ratchet analysis. The stability analysis is used to determine the stability limit load multiplier corresponding to the current parametric condition; the ratchet analysis is used to determine the ratchet limit load multiplier corresponding to the current parametric condition. After completing the stability analysis and ratchet analysis for the current parametric condition, it is determined whether all parametric conditions have been completed. If not, the outer loop is returned and the next set of parametric conditions is selected; if all parametric conditions have been completed, the outer loop ends.

[0156] After completing all the parametric conditions, determine the corresponding dimensionless parameters based on the geometric and material fundamental data corresponding to each set of parametric conditions. (That is, the aforementioned geometry-material coupling dimensionless composite characteristic parameters), and each dimensionless parameter Correlate the load-bearing capacity with the corresponding stability ultimate load multiplier and ratchet ultimate load multiplier respectively, and establish the relationship between the load-bearing capacity and dimensionless parameters. The mapping relationship (i.e., the bearing capacity calibration relationship between the aforementioned dimensionless composite characteristic parameters of geometry-material coupling and the stability limit load multiplier and ratchet limit load multiplier) is described. The bearing capacity in this mapping relationship is characterized by the stability limit load multiplier and the ratchet limit load multiplier.

[0157] In the calibration process for engineering applications, the target dimensionless parameters are determined based on the geometric characteristic parameters and material property parameters of the high-temperature slender thin-walled tube to be calibrated. (That is, the aforementioned target composite characteristic parameters), select the corresponding mapping relationship according to the target load conditions, and based on the target dimensionless parameters. The target stable limit load multiplier and the target ratchet limit load multiplier are determined. Further, the reference load of the high-temperature slender thin-walled tube to be calibrated is multiplied by the target stable limit load multiplier and the target ratchet limit load multiplier, respectively, to obtain the corresponding stable limit load and ratchet limit load, and the effective load-bearing capacity boundary is determined accordingly. Based on the above mapping relationship, a high-temperature failure mechanism calibration map (i.e., the above load-bearing capacity calibration map) is drawn, which includes the stable limit boundary and the ratchet limit boundary.

[0158] Figure 7 Further shown Figure 6 The specific process of the stability analysis is as follows: First, prepare the elastic stress field corresponding to each load vertex; enter the current iteration step; set the initial value of the current stability limit load multiplier; update the equivalent shear modulus of each load vertex; determine the overall equivalent shear modulus; construct the Jacobian matrix characterizing the material stiffness; form the weighted combined stress field of each elastic stress field; solve the initial stress problem and obtain the strain increment; determine the constant self-equilibrium residual stress field; update the strain increment corresponding to each load vertex; read the finite element output results and update the stability limit load multiplier; then determine whether the preset convergence condition is met; otherwise, enter the next iteration step; if yes, output the stability limit load multiplier.

[0159] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0160] Based on the same inventive concept, this application also provides a calibration device for the effective load-bearing capacity of a high-temperature slender thin-walled tube, which corresponds to the calibration method for the effective load-bearing capacity of a high-temperature slender thin-walled tube. Since the principle of the device in this application is similar to the calibration method for the effective load-bearing capacity of a high-temperature slender thin-walled tube described above, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be described again.

[0161] Reference Figure 8 The diagram shown is a schematic of a high-temperature slender thin-walled tube effective load-bearing capacity calibration device provided in an embodiment of this application. The device includes: The setting module 810 is used to set multiple sets of basic parameter combinations for high-temperature slender thin-walled tubes, each set of basic parameter combinations including geometric feature parameters and material performance parameters; The first determining module 820 is used to determine the dimensionless composite characteristic parameters of geometry-material coupling based on the product of the ratio of wall thickness to total pipe length, the ratio of outer diameter to total pipe length, and the ratio of yield strength to elastic modulus of the material at a preset service temperature in each group of basic parameter combinations. The second determining module 830 is used to obtain the elastic stress field under multiple preset load conditions for the high-temperature slender thin-walled tubes corresponding to each group of basic parameter combinations, and to determine the stability limit load multiplier and ratchet limit load multiplier under each preset load condition based on the linear matching method. Module 840 is established to establish a corresponding bearing capacity calibration relationship for each preset load condition based on the geometric-material coupling dimensionless composite characteristic parameters and their corresponding stability limit load multipliers and ratchet limit load multipliers under the preset load conditions. The acquisition module 850 is used to acquire the geometric characteristic parameters, material performance parameters, target load conditions and reference load of the high temperature slender thin-walled tube to be calibrated, and to determine the target composite characteristic parameters according to the determination method of the geometric-material coupled dimensionless composite characteristic parameters. The calibration module 860 is used to select the corresponding bearing capacity calibration relationship according to the target load condition, determine the target stability limit load multiplier and the target ratchet limit load multiplier based on the target composite characteristic parameters, and determine the effective bearing capacity boundary of the high temperature slender thin-walled tube to be calibrated in combination with the reference load.

[0162] In one optional embodiment, the geometric feature parameters include the total length of the pipe, the outer diameter, and the wall thickness, and the material performance parameters include the yield strength and elastic modulus of the material at the preset service temperature; The ratio of the total length of the high-temperature slender thin-walled tube to its outer diameter is not less than 20, and the ratio of its wall thickness to its outer diameter is not greater than 0.1. The first determining module 820 is specifically used to: determine the product of the ratio of the wall thickness to the total length of the pipe, the ratio of the outer diameter to the total length of the pipe, and the ratio of the yield strength to the elastic modulus, and perform order-of-magnitude correction on the product to obtain the geometry-material coupling dimensionless composite characteristic parameters.

[0163] In one optional implementation, the second determining module 830 is specifically used for: Based on the combination of basic parameters described in each group, establish the corresponding high-temperature slender thin-walled tube finite element model; Preset boundary conditions are applied to the finite element model of the high-temperature slender thin-walled tube, and linear elastic finite element analysis is performed on the finite element model of the high-temperature slender thin-walled tube using the elastic parameters of the material at the preset service temperature to obtain the elastic stress field corresponding to each load moment under each preset load condition. Each of the preset load conditions includes a constant axial load component and a cyclic axial load component. The constant axial load component is set according to the preset multiple of the ultimate axial load of the corresponding high-temperature slender thin-walled tube finite element model under the preset static axial compression condition.

[0164] In one optional implementation, the second determining module 830 is specifically used for: The current true stress is determined based on the elastic stress field amplified by the current load multiplier and the current residual stress. Based on the current actual stress, the yield state of each material integration point is determined according to the Mises yield criterion, and for the material integration point where yielding occurs, the plastic strain increment is determined according to the correlation flow rule. The equivalent shear modulus is updated based on the ratio of the material's yield strength to the equivalent strain corresponding to the plastic strain increment, and the material stiffness matrix is ​​updated based on the updated equivalent shear modulus. Based on the updated material stiffness matrix, a linear elastic solution is performed to update the residual stress and the actual stress. Update the current load multiplier, and repeatedly determine the plastic strain increment, update the equivalent shear modulus, perform the linear elastic solution, and update the residual stress until the load multiplier change, equivalent shear modulus change, and residual stress change between adjacent iteration steps satisfy the corresponding preset convergence conditions. The converged load multiplier is then determined as the stability limit load multiplier. Among them, the converged residual stress constitutes a self-equilibrium residual stress field that satisfies the structural equilibrium condition under zero external load.

[0165] In one optional implementation, the second determining module 830 is specifically used for: The elastic stress field corresponding to the preset load condition is divided into the elastic stress field corresponding to the constant axial load component and the elastic stress field corresponding to the cyclic axial load component. Based on the elastic stress field corresponding to the cyclic axial load component, the variable residual stress and plastic strain increment at each load moment within a single load cycle are iteratively determined until the variable residual stress satisfies the periodic closure condition where the beginning and end of the cycle are equal. Based on the converged variable residual stress and plastic strain increment, the elastic stress field corresponding to the constant axial load component is superimposed, and the load multiplier corresponding to the constant axial load component is adjusted. For each adjusted load multiplier, the average cumulative plastic strain rate is determined based on the sum of plastic strain increments over multiple load cycles, the number of load cycles, and the duration of a single load cycle. The load multiplier corresponding to the change of the average cumulative plastic strain rate from zero to a positive value is then determined as the ratchet limit load multiplier.

[0166] In one optional implementation, the establishment module 840 is specifically used for: For each of the preset load conditions, polynomial fitting is performed on each of the geometric-material coupling dimensionless composite characteristic parameters and the corresponding stability limit load multiplier under the preset load conditions to establish a first mapping relationship between the geometric-material coupling dimensionless composite characteristic parameters and the stability limit load multiplier. For each of the preset load conditions, a polynomial fitting is performed on each of the geometry-material coupling dimensionless composite characteristic parameters and the corresponding ratchet limit load multiplier under the preset load conditions to establish a second mapping relationship between the geometry-material coupling dimensionless composite characteristic parameters and the ratchet limit load multiplier. Based on the first mapping relationship and the second mapping relationship, a load-bearing capacity calibration map including the stability limit boundary and the ratchet limit boundary is generated, with the geometry-material coupling dimensionless composite characteristic parameter as the abscissa and the stability limit load multiplier and the ratchet limit load multiplier as the ordinate.

[0167] In one optional implementation, the reference load is the ultimate axial load of the high-temperature slender thin-walled tube to be calibrated under a preset static axial compression condition. The calibration module 860 is specifically used for: The reference load is multiplied by the target stability limit load multiplier and the target ratchet limit load multiplier, respectively, to obtain the stability limit load and ratchet limit load of the high-temperature slender thin-walled tube to be calibrated. The smaller of the stability limit load and the ratchet limit load is determined as the critical failure load, and the critical failure load is used as the effective bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated. The calibration module 860 is also used to: divide the critical failure load by a preset safety factor to obtain the safe working load of the high-temperature slender thin-walled tube to be calibrated.

[0168] The processing flow of each module in the device and the interaction flow between each module can be referred to the relevant descriptions in the above method embodiments, and will not be detailed here.

[0169] The high-temperature slender thin-walled tube effective load-bearing capacity calibration device provided in this application constructs a geometry-material coupled dimensionless composite characteristic parameter based on the thickness-to-length ratio, diameter-to-length ratio, and the ratio of the material's high-temperature yield strength to its elastic modulus. This allows the tube's slenderness, thinness, and high-temperature material deformation characteristics to be comprehensively characterized within the same parameter, reducing dimensional differences caused by different geometric dimensions and material systems. This provides a unified basis for comparing the load-bearing capacity of high-temperature slender thin-walled tubes of different specifications. Simultaneously, based on the linear matching method, the stable ultimate load multiplier and ratchet ultimate load multiplier under different load conditions are determined, and a load-bearing capacity calibration relationship is established between them and the composite characteristic parameter. Therefore, for the tube to be calibrated, the corresponding stable and ratchet failure boundaries can be obtained based on its composite characteristic parameter and target load condition, reducing the computational burden of repeatedly performing complex cyclic plasticity analysis, and taking into account different failure modes, thus improving the efficiency, completeness, and reliability of effective load-bearing capacity assessment.

[0170] This application also provides a computer device, such as... Figure 9 The diagram shown is a schematic representation of a computer device structure provided in an embodiment of this application, including: A processor 91 and a memory 92; the memory 92 stores machine-readable instructions executable by the processor 91, and the processor 91 executes the machine-readable instructions stored in the memory 92. When the machine-readable instructions are executed by the processor 91, the processor 91 performs the following steps: Multiple sets of basic parameter combinations are set for high-temperature slender thin-walled tubes, and each set of basic parameter combinations includes geometric characteristic parameters and material property parameters; Based on the product of the ratio of wall thickness to total pipe length, the ratio of outer diameter to total pipe length, and the ratio of yield strength to elastic modulus of the material at the preset service temperature in each group of basic parameter combinations, the dimensionless composite characteristic parameters of geometry-material coupling are determined. For each set of basic parameter combinations corresponding to high-temperature slender thin-walled tubes, the elastic stress fields under multiple preset load conditions are obtained, and the stability limit load multiplier and ratchet limit load multiplier under each preset load condition are determined based on the linear matching method. For each of the preset load conditions, based on the geometric-material coupling dimensionless composite characteristic parameters and their corresponding stability limit load multipliers and ratchet limit load multipliers under the preset load conditions, a corresponding bearing capacity calibration relationship is established. Obtain the geometric characteristic parameters, material property parameters, target load conditions and reference load of the high temperature slender thin-walled tube to be calibrated, and determine the target composite characteristic parameters according to the determination method of the dimensionless composite characteristic parameters of the geometry-material coupling described above; Select the corresponding bearing capacity calibration relationship according to the target load condition, determine the target stability limit load multiplier and the target ratchet limit load multiplier based on the target composite characteristic parameters, and determine the effective bearing capacity boundary of the high temperature slender thin-walled tube to be calibrated in combination with the reference load.

[0171] In one optional embodiment, the geometric feature parameters include the total length of the pipe, the outer diameter, and the wall thickness, and the material performance parameters include the yield strength and elastic modulus of the material at the preset service temperature; The ratio of the total length of the high-temperature slender thin-walled tube to its outer diameter is not less than 20, and the ratio of its wall thickness to its outer diameter is not greater than 0.1. The determination of the dimensionless composite characteristic parameters of the geometry-material coupling includes: determining the product of the ratio of the wall thickness to the total length of the pipe, the ratio of the outer diameter to the total length of the pipe, and the ratio of the yield strength to the elastic modulus, and performing an order of magnitude correction on the product to obtain the dimensionless composite characteristic parameters of the geometry-material coupling.

[0172] In one optional implementation, obtaining the elastic stress field under multiple preset load conditions includes: Based on the combination of basic parameters described in each group, establish the corresponding high-temperature slender thin-walled tube finite element model; Preset boundary conditions are applied to the finite element model of the high-temperature slender thin-walled tube, and linear elastic finite element analysis is performed on the finite element model of the high-temperature slender thin-walled tube using the elastic parameters of the material at the preset service temperature to obtain the elastic stress field corresponding to each load moment under each preset load condition. Each of the preset load conditions includes a constant axial load component and a cyclic axial load component. The constant axial load component is set according to the preset multiple of the ultimate axial load of the corresponding high-temperature slender thin-walled tube finite element model under the preset static axial compression condition.

[0173] In one optional implementation, determining the stability limit load multiplier under each of the preset load conditions based on the linear matching method includes: The current true stress is determined based on the elastic stress field amplified by the current load multiplier and the current residual stress. Based on the current actual stress, the yield state of each material integration point is determined according to the Mises yield criterion, and for the material integration point where yielding occurs, the plastic strain increment is determined according to the correlation flow rule. The equivalent shear modulus is updated based on the ratio of the material's yield strength to the equivalent strain corresponding to the plastic strain increment, and the material stiffness matrix is ​​updated based on the updated equivalent shear modulus. Based on the updated material stiffness matrix, a linear elastic solution is performed to update the residual stress and the actual stress. Update the current load multiplier, and repeatedly determine the plastic strain increment, update the equivalent shear modulus, perform the linear elastic solution, and update the residual stress until the load multiplier change, equivalent shear modulus change, and residual stress change between adjacent iteration steps satisfy the corresponding preset convergence conditions. The converged load multiplier is then determined as the stability limit load multiplier. Among them, the converged residual stress constitutes a self-equilibrium residual stress field that satisfies the structural equilibrium condition under zero external load.

[0174] In one optional implementation, determining the ratchet ultimate load multiplier under each preset load condition based on the linear matching method includes: The elastic stress field corresponding to the preset load condition is divided into the elastic stress field corresponding to the constant axial load component and the elastic stress field corresponding to the cyclic axial load component. Based on the elastic stress field corresponding to the cyclic axial load component, the variable residual stress and plastic strain increment at each load moment within a single load cycle are iteratively determined until the variable residual stress satisfies the periodic closure condition where the beginning and end of the cycle are equal. Based on the converged variable residual stress and plastic strain increment, the elastic stress field corresponding to the constant axial load component is superimposed, and the load multiplier corresponding to the constant axial load component is adjusted. For each adjusted load multiplier, the average cumulative plastic strain rate is determined based on the sum of plastic strain increments over multiple load cycles, the number of load cycles, and the duration of a single load cycle. The load multiplier corresponding to the change of the average cumulative plastic strain rate from zero to a positive value is then determined as the ratchet limit load multiplier.

[0175] In one optional implementation, establishing a corresponding bearing capacity calibration relationship for each of the preset load conditions includes: For each of the preset load conditions, polynomial fitting is performed on each of the geometric-material coupling dimensionless composite characteristic parameters and the corresponding stability limit load multiplier under the preset load conditions to establish a first mapping relationship between the geometric-material coupling dimensionless composite characteristic parameters and the stability limit load multiplier. For each of the preset load conditions, a polynomial fitting is performed on each of the geometry-material coupling dimensionless composite characteristic parameters and the corresponding ratchet limit load multiplier under the preset load conditions to establish a second mapping relationship between the geometry-material coupling dimensionless composite characteristic parameters and the ratchet limit load multiplier. Based on the first mapping relationship and the second mapping relationship, a load-bearing capacity calibration map including the stability limit boundary and the ratchet limit boundary is generated, with the geometry-material coupling dimensionless composite characteristic parameter as the abscissa and the stability limit load multiplier and the ratchet limit load multiplier as the ordinate.

[0176] In one optional implementation, the reference load is the ultimate axial load of the high-temperature slender thin-walled tube to be calibrated under a preset static axial compression condition. The determination of the effective load-bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated in conjunction with the reference load includes: The reference load is multiplied by the target stability limit load multiplier and the target ratchet limit load multiplier, respectively, to obtain the stability limit load and ratchet limit load of the high-temperature slender thin-walled tube to be calibrated. The smaller of the stability limit load and the ratchet limit load is determined as the critical failure load, and the critical failure load is used as the effective bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated. The processor 91 also performs the following: dividing the critical failure load by a preset safety factor to obtain the safe working load of the high-temperature slender thin-walled tube to be calibrated.

[0177] The aforementioned memory 92 includes a main memory 921 and an external memory 922; the main memory 921, also known as internal memory, is used to temporarily store the computational data in the processor 91, as well as the data exchanged with external memory 922 such as a hard disk. The processor 91 exchanges data with the external memory 922 through the main memory 921.

[0178] The specific execution process of the above instructions can be referred to the steps of the high-temperature slender thin-walled tube effective load-bearing capacity calibration method described in the embodiments of this application, and will not be repeated here.

[0179] This application also provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program performs the steps of the high-temperature slender thin-walled tube effective load-bearing capacity calibration method described in the above-described method embodiments. The storage medium can be either volatile or non-volatile computer-readable storage.

[0180] This application also provides a computer program product carrying program code. The program code includes instructions that can be used to execute the steps of the high-temperature slender thin-walled tube effective load-bearing capacity calibration method described in the above method embodiments. For details, please refer to the above method embodiments, which will not be repeated here.

[0181] The aforementioned computer program product can be implemented through hardware, software, or a combination thereof. In one optional embodiment, the computer program product is specifically embodied in a computer storage medium; in another optional embodiment, the computer program product is specifically embodied in a software product, such as a software development kit (SDK), etc.

[0182] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division; in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection may be through some communication interfaces; the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0183] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0184] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0185] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0186] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for calibrating the effective load-bearing capacity of a high-temperature, slender, thin-walled tube, characterized in that, include: Multiple sets of basic parameter combinations are set for high-temperature slender thin-walled tubes, and each set of basic parameter combinations includes geometric characteristic parameters and material property parameters; Based on the product of the ratio of wall thickness to total pipe length, the ratio of outer diameter to total pipe length, and the ratio of yield strength to elastic modulus of the material at the preset service temperature in each group of basic parameter combinations, the dimensionless composite characteristic parameters of geometry-material coupling are determined. For each set of basic parameter combinations corresponding to high-temperature slender thin-walled tubes, the elastic stress fields under multiple preset load conditions are obtained, and the stability limit load multiplier and ratchet limit load multiplier under each preset load condition are determined based on the linear matching method. For each of the preset load conditions, based on the geometric-material coupling dimensionless composite characteristic parameters and their corresponding stability limit load multipliers and ratchet limit load multipliers under the preset load conditions, a corresponding bearing capacity calibration relationship is established. Obtain the geometric characteristic parameters, material property parameters, target load conditions and reference load of the high temperature slender thin-walled tube to be calibrated, and determine the target composite characteristic parameters according to the determination method of the dimensionless composite characteristic parameters of the geometry-material coupling described above; Select the corresponding bearing capacity calibration relationship according to the target load condition, determine the target stability limit load multiplier and the target ratchet limit load multiplier based on the target composite characteristic parameters, and determine the effective bearing capacity boundary of the high temperature slender thin-walled tube to be calibrated in combination with the reference load.

2. The method according to claim 1, characterized in that, The geometric characteristic parameters include the total length of the pipe, the outer diameter, and the wall thickness; the material performance parameters include the yield strength and elastic modulus of the material at the preset service temperature. The ratio of the total length of the high-temperature slender thin-walled tube to its outer diameter is not less than 20, and the ratio of its wall thickness to its outer diameter is not greater than 0.

1. The determination of the dimensionless composite characteristic parameters of the geometry-material coupling includes: determining the product of the ratio of the wall thickness to the total length of the pipe, the ratio of the outer diameter to the total length of the pipe, and the ratio of the yield strength to the elastic modulus, and performing an order of magnitude correction on the product to obtain the dimensionless composite characteristic parameters of the geometry-material coupling.

3. The method according to claim 1, characterized in that, The acquisition of elastic stress fields under multiple preset load conditions includes: Based on the combination of basic parameters described in each group, establish the corresponding high-temperature slender thin-walled tube finite element model; Preset boundary conditions are applied to the finite element model of the high-temperature slender thin-walled tube, and linear elastic finite element analysis is performed on the finite element model of the high-temperature slender thin-walled tube using the elastic parameters of the material at the preset service temperature to obtain the elastic stress field corresponding to each load moment under each preset load condition. Each of the preset load conditions includes a constant axial load component and a cyclic axial load component. The constant axial load component is set according to the preset multiple of the ultimate axial load of the corresponding high-temperature slender thin-walled tube finite element model under the preset static axial compression condition.

4. The method according to claim 3, characterized in that, The determination of the stability limit load multiplier under each preset load condition based on the linear matching method includes: The current true stress is determined based on the elastic stress field amplified by the current load multiplier and the current residual stress. Based on the current actual stress, the yield state of each material integration point is determined according to the Mises yield criterion, and for the material integration point where yielding occurs, the plastic strain increment is determined according to the correlation flow rule. The equivalent shear modulus is updated based on the ratio of the material's yield strength to the equivalent strain corresponding to the plastic strain increment, and the material stiffness matrix is ​​updated based on the updated equivalent shear modulus. Based on the updated material stiffness matrix, a linear elastic solution is performed to update the residual stress and the actual stress. Update the current load multiplier, and repeatedly determine the plastic strain increment, update the equivalent shear modulus, perform the linear elastic solution, and update the residual stress until the load multiplier change, equivalent shear modulus change, and residual stress change between adjacent iteration steps satisfy the corresponding preset convergence conditions. The converged load multiplier is then determined as the stability limit load multiplier. Among them, the converged residual stress constitutes a self-equilibrium residual stress field that satisfies the structural equilibrium condition under zero external load.

5. The method according to claim 3, characterized in that, The determination of the ratchet ultimate load multiplier under each preset load condition based on the linear matching method includes: The elastic stress field corresponding to the preset load condition is divided into the elastic stress field corresponding to the constant axial load component and the elastic stress field corresponding to the cyclic axial load component. Based on the elastic stress field corresponding to the cyclic axial load component, the variable residual stress and plastic strain increment at each load moment within a single load cycle are iteratively determined until the variable residual stress satisfies the periodic closure condition where the beginning and end of the cycle are equal. Based on the converged variable residual stress and plastic strain increment, the elastic stress field corresponding to the constant axial load component is superimposed, and the load multiplier corresponding to the constant axial load component is adjusted. For each adjusted load multiplier, the average cumulative plastic strain rate is determined based on the sum of plastic strain increments over multiple load cycles, the number of load cycles, and the duration of a single load cycle. The load multiplier corresponding to the change of the average cumulative plastic strain rate from zero to a positive value is then determined as the ratchet limit load multiplier.

6. The method according to claim 1, characterized in that, The establishment of a corresponding bearing capacity calibration relationship for each of the preset load conditions includes: For each of the preset load conditions, polynomial fitting is performed on each of the geometric-material coupling dimensionless composite characteristic parameters and the corresponding stability limit load multiplier under the preset load conditions to establish a first mapping relationship between the geometric-material coupling dimensionless composite characteristic parameters and the stability limit load multiplier. For each of the preset load conditions, a polynomial fitting is performed on each of the geometry-material coupling dimensionless composite characteristic parameters and the corresponding ratchet limit load multiplier under the preset load conditions to establish a second mapping relationship between the geometry-material coupling dimensionless composite characteristic parameters and the ratchet limit load multiplier. Based on the first mapping relationship and the second mapping relationship, a load-bearing capacity calibration map including the stability limit boundary and the ratchet limit boundary is generated, with the geometry-material coupling dimensionless composite characteristic parameter as the abscissa and the stability limit load multiplier and the ratchet limit load multiplier as the ordinate.

7. The method according to claim 6, characterized in that, The reference load is the ultimate axial load of the high-temperature slender thin-walled tube to be calibrated under a preset static axial compression condition. The determination of the effective load-bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated in conjunction with the reference load includes: The reference load is multiplied by the target stability limit load multiplier and the target ratchet limit load multiplier, respectively, to obtain the stability limit load and ratchet limit load of the high-temperature slender thin-walled tube to be calibrated. The smaller of the stability limit load and the ratchet limit load is determined as the critical failure load, and the critical failure load is used as the effective bearing capacity boundary of the high-temperature slender thin-walled tube to be calibrated. The method further includes: dividing the critical failure load by a preset safety factor to obtain the safe working load of the high-temperature slender thin-walled tube to be calibrated.

8. A device for calibrating the effective load-bearing capacity of a high-temperature, slender, thin-walled tube, characterized in that, include: The setting module is used to set multiple sets of basic parameter combinations for high-temperature slender thin-walled tubes. Each set of basic parameter combinations includes geometric characteristic parameters and material performance parameters. The first determining module is used to determine the dimensionless composite characteristic parameters of geometry-material coupling based on the product of the ratio of wall thickness to total pipe length, the ratio of outer diameter to total pipe length, and the ratio of yield strength to elastic modulus of the material at a preset service temperature in each group of basic parameter combinations. The second determining module is used to obtain the elastic stress field under multiple preset load conditions for each high-temperature slender thin-walled tube corresponding to the basic parameter combination of each group, and to determine the stability limit load multiplier and ratchet limit load multiplier under each preset load condition based on the linear matching method. A module is established to establish a corresponding load-bearing capacity calibration relationship for each preset load condition based on the geometric-material coupling dimensionless composite characteristic parameters and their corresponding stability limit load multipliers and ratchet limit load multipliers under the preset load conditions. The acquisition module is used to acquire the geometric characteristic parameters, material performance parameters, target load conditions and reference load of the high-temperature slender thin-walled tube to be calibrated, and to determine the target composite characteristic parameters according to the determination method of the dimensionless composite characteristic parameters of the geometry-material coupling. The calibration module is used to select the corresponding bearing capacity calibration relationship according to the target load condition, determine the target stability limit load multiplier and the target ratchet limit load multiplier based on the target composite characteristic parameters, and determine the effective bearing capacity boundary of the high temperature slender thin-walled tube to be calibrated in combination with the reference load.

9. A computer device, characterized in that, include: The processor and the memory, wherein the memory stores machine-readable instructions executable by the processor, the processor is used to execute the machine-readable instructions stored in the memory, and when the machine-readable instructions are executed by the processor, the processor performs the steps of the high-temperature slender thin-walled tube effective load-bearing capacity calibration method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a computer device, performs the steps of the method for calibrating the effective load-bearing capacity of a high-temperature slender thin-walled tube as described in any one of claims 1 to 7.

Images