Numerical simulation method for predicting circumferential strength of metal-SiCf / SiC multilayer heterogeneous composite cladding tube under expansion plug test
Through detailed geometric model establishment and mechanical constitutive equation solution, the problem of ignoring the direction differences between the interface layer and fiber bundle in the prior art is solved, and the high circumferential strength of the metal-SiCf/SiC multi-layer heterogeneous composite enclosed tube is achieved. Accuracy prediction reduces material testing costs and guides the performance optimization of clad tubes.
Patent Information
- Application Number
- CN202411319021.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-21
- Publication Date
- 2025-01-14
AI Technical Summary
When the existing numerical simulation method predicts the circumferential strength of metal-SiCf/SiC multi-layer heterogeneous composite encapsulated tube, it ignores the influence of the interface layer and treats the circumferential fiber bundle and the axial fiber bundle as a whole, resulting in The failure order analysis is inconsistent, which affects the prediction accuracy.
By obtaining the geometric dimension information of metal-SiCf/SiC samples, a geometric model including metal lining, interface, matrix and fiber bundle was established, and each component was meshed and curved coordinate system was established, and the solution was made based on the radial displacement sequence. Mechanical constitutive equations, obtain stress-strain curves to predict the loop intensity.
This method can accurately predict the component failure sequence, improve the accuracy of the prediction of circumferential strength, with a relative error of about 10%, and reduce material testing costs, guiding the performance optimization of clad tubes and structural design.
Smart Images
Figure CN119312421A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of composite cladding tube performance prediction, and in particular to a method for predicting the performance of metal-SiC composite cladding tubes under expansion test. f Numerical simulation method for the circumferential strength of / SiC multilayer heterogeneous composite cladding tubes. Background Art
[0002] Metal-SiC f / SiC multilayer heterogeneous composite cladding tubes will be subjected to internal pressure during service, so it is necessary to evaluate their mechanical properties and failure behavior under internal pressure in order to design cladding tubes with better performance. Among various methods of applying pressure, elastic expansion plug (expansion plug test) based on pressure burst test is widely used because of its convenience and efficiency. Most of the existing numerical simulation methods only consider the main components of the cladding tube, such as metal lining, fiber and matrix, but ignore the influence of the interface layer on the cladding tube. In addition, in the existing numerical simulation methods, the circumferential fiber bundle and the axial fiber bundle are defined as a whole through the mechanical constitutive equation, and the fiber bundles in different directions have different damage failure modes under the action of internal pressure, which will cause the failure sequence of the components of the cladding tube to be inconsistent with the experimental observation, thereby affecting the prediction accuracy of the circumferential strength. Summary of the invention
[0003] The main purpose of this application is to provide a method for predicting the metal-SiC f The numerical simulation method of the circumferential strength of / SiC multi-layer heterogeneous composite cladding tube is aimed at solving the defect of low accuracy in predicting the circumferential strength of cladding tube in existing numerical simulation methods.
[0004] To achieve the above objectives, the present application provides a method for predicting the metal-SiC f / SiC multilayer heterogeneous composite cladding tube circumferential strength numerical simulation method, including: obtaining metal-SiC f / SiC sample's geometric size information, establish a geometric model based on the geometric size information, wherein the components of the geometric model include metal lining, interface, matrix, and fiber bundle; mesh each component separately; establish a curvilinear coordinate system for each meshed component; based on the curvilinear coordinate system, apply a radial displacement series to the inner wall surface of the geometric model, and use the remaining surfaces of the geometric model as free surfaces; determine the corresponding mechanical constitutive equation according to the material properties of each component; solve the mechanical constitutive equation based on the radial displacement series, obtain the stress-strain curve of each component after applying the radial displacement series, and determine the predicted circumferential strength based on the stress-strain curve.
[0005] Optionally, the mesh division method is: the metal lining and the interface are divided by hexahedral meshes, and the fiber bundle and the matrix are divided by tetrahedral meshes.
[0006] Optionally, the fiber bundle includes a circumferential fiber bundle and an axial fiber bundle; the curvilinear coordinate system includes a first coordinate system and a second coordinate system, the curvilinear coordinate system of the axial fiber bundle is the first coordinate system, and the curvilinear coordinate system of the metal lining, interface, matrix and circumferential fiber bundle is the second coordinate system.
[0007] Optionally, the method for establishing the first coordinate system includes: using the Laplace equation to solve the first basis vector of the circumferential fiber bundle, and determining the second basis vector and the third basis vector according to the first basis vector to obtain the first coordinate system.
[0008] Optionally, the method for establishing the second coordinate system includes: converting the Cartesian coordinate system of the component into a cylindrical coordinate system, that is, the second coordinate system.
[0009] Optionally, the mechanical constitutive equations corresponding to each component are: the mechanical constitutive equation of the metal lining includes the fourth strength theory and the direct stiffness degradation criterion; the mechanical constitutive equation of the interface includes the Mohr strength criterion and the direct stiffness degradation criterion; the mechanical constitutive equation of the fiber bundle includes the Hashin criterion, the direct stiffness degradation criterion corresponding to the axial fiber bundle and the exponential softening equation corresponding to the circumferential fiber bundle; the mechanical constitutive equation of the matrix includes the first strength theory and the direct stiffness degradation criterion.
[0010] Optionally, the geometry information includes the thickness of the metal liner, interface, matrix and fiber bundle, metal-SiC f / Height, inner diameter and outer diameter of SiC samples.
[0011] Optionally, after the geometric model is established, the following steps are further included: modifying the relative tolerance value of the geometric model to remove overlaps and gaps in the geometric model.
[0012] Optionally, the displacement series is: starting with 0 mm, mm is the step length, mm is an increasing sequence of terminal values.
[0013] Optionally, the mechanical constitutive equations are solved using a constant Newton iteration method.
[0014] Compared with the prior art, the present invention has the following beneficial effects: A method for predicting metal-SiC under expansion and plugging test of the present invention fThe numerical simulation method of the hoop strength of the metal-SiC multilayer heterogeneous composite cladding tube comprehensively considers the different components of the cladding tube, defines the mechanical constitutive equations of the axial fiber bundle and the hoop fiber bundle respectively, and can obtain the component failure sequence consistent with the experimental test, thereby revealing the loss process of the cladding tube; the predicted metal-SiC f The relative error between the circumferential strength of SiC / SiC multilayer heterogeneous composite cladding tube and the actual circumferential strength is about 10%, which has a high prediction accuracy. In addition, the numerical simulation method can reduce the cost of material testing and guide the optimization of cladding tube performance and structural design. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 This application is a method for predicting the expansion of metal-SiC f Schematic diagram of the flow chart of the numerical simulation method for the hoop strength of / SiC multilayer heterogeneous composite cladding tube; Figure 2 This application is a method for predicting the expansion of metal-SiC f The geometric model diagram obtained by the numerical simulation method of the hoop strength of / SiC multilayer heterogeneous composite cladding tube; Figure 3 This application is a method for predicting the expansion of metal-SiC f Simulation results of the numerical simulation method for the circumferential strength of / SiC multi-layer heterogeneous composite cladding tube.
[0016] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0017] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0018] The present invention provides a method for predicting metal-SiC under expansion and plugging test f Numerical simulation method for the hoop strength of SiC multilayer heterogeneous composite cladding tubes, such as Figure 1 As shown, the specific steps include: Step S1, obtaining metal-SiC fThe geometric dimension information of the / SiC sample is obtained, and a geometric model is established based on the geometric dimension information, wherein the components of the geometric model include metal lining, interface, matrix, fiber bundle, and the fiber bundle includes annular fiber bundle and axial fiber bundle; the geometric dimension information includes the thickness of the metal lining, interface, matrix and fiber bundle, metal-SiC f / Height, inner diameter and outer diameter of SiC samples.
[0019] Specifically, the geometric size information can be obtained based on the sample image actually observed by X-ray computed tomography (X-CT), and the geometric shape of the sample can be reconstructed using COMSOL Multiphysics software to establish a geometric model that can reflect the actual structure of the sample.
[0020] Step S2, modifying the relative tolerance value of the geometric model to remove detail defects such as overlaps and gaps in the geometric model that affect mesh division; Step S3, meshing each component separately; specifically, the metal lining and the interface are meshed using hexahedral meshes, and the fiber bundles and the matrix are meshed using tetrahedral meshes.
[0021] Step S4, respectively establish a curvilinear coordinate system for each component after meshing; since the directions of the axial fiber bundle and the metal lining, interface, matrix, and circumferential fiber bundle are different, the curvilinear coordinate systems established for the axial fiber bundle and other components are also different. The specific establishment method is as follows: the axial fiber bundle establishes a first coordinate system, and the metal lining, interface, matrix, and circumferential fiber bundle all establish second coordinate systems. The Laplace equation is used to solve the first basis vector of the axial fiber bundle, and the second basis vector and the third basis vector are determined according to the first basis vector to obtain the first coordinate system; the Laplace equation is as follows:
[0022]
[0023] In the formula, is the Laplace operator, is a harmonic function, is a vector field, is the Hamiltonian operator, and are the unit basis vectors of the x-axis and y-axis in the Cartesian coordinate system, respectively.
[0024] Then the three basis vectors of the first coordinate system are as follows:
[0025] In the formula, , , are the first, second and third basis vectors in the first coordinate system respectively.
[0026] The Cartesian coordinate system of the components other than the axial fiber bundle is converted into a cylindrical coordinate system, which is the second coordinate system. The conversion formula is as follows:
[0027]
[0028]
[0029] In the formula, , , are the first, second and third basis vectors in the Cartesian coordinate system, , , are the first, second and third basis vectors in the cylindrical coordinate system, , y and x are the coordinates of any point in the Cartesian coordinate system.
[0030] Step S5, based on the second coordinate system, Direction, apply displacement series to the inner wall surface of the geometric model, and take the rest of the geometric model as free surface; the displacement series takes 0mm as the starting value, mm is the step length, mm is an increasing sequence of terminal values; Step S6, determining the corresponding mechanical constitutive equation according to the material properties of each component, wherein the material properties of each component in different directions are defined based on three basis vectors of the curvilinear coordinate system; since the material properties of the metal lining, interface, fiber bundle, and matrix are elastic-plastic material, brittle material, ductile material, and brittle material, respectively, the mechanical constitutive equations corresponding to each component are respectively: the mechanical constitutive equation of the metal lining includes the fourth strength theory for determining initial damage and the direct stiffness degradation criterion for describing failure behavior; the mechanical constitutive equation of the interface includes the Mohr strength criterion for determining initial damage and the direct stiffness degradation criterion for describing failure behavior; the mechanical constitutive equation of the fiber bundle includes the Hashin criterion for determining initial damage, the direct stiffness degradation criterion for describing failure behavior corresponding to the axial fiber bundle, and the exponential softening equation for describing damage evolution corresponding to the circumferential fiber bundle; the mechanical constitutive equation of the matrix includes the first strength theory for determining initial damage and the direct stiffness degradation criterion for describing failure behavior.
[0031] The fourth strength theory:
[0032] In the formula, , , are the first, second and third principal stresses respectively, is the shear strength.
[0033] Direct stiffness degradation criterion:
[0034] In the formula, is the stress tensor, d is a constant equal to 0.9, C is the stiffness matrix, is the strain tensor.
[0035] Mohr's strength criterion:
[0036] In the formula, is the tensile strength, For compressive strength.
[0037] Hashin Guidelines:
[0038] In the formula, for The tensile stress in the direction for Tensile strength in the direction is the shear strength on the cross section, is the shear strength of the cross section, is the shear stress contribution coefficient, which is 0 under circumferential tension.
[0039] Exponential softening equation:
[0040] in,
[0041] In the formula, is the characteristic length, for Young's modulus in the direction, is the fracture energy at the end of the linear change stage, is the fracture energy at the end of the exponential change stage.
[0042] First Strength Theory:
[0043] Step S7, using the constant Newton iteration method to solve the mechanical constitutive equation, to obtain the stress-strain curve of each component, the circumferential stress corresponding to the highest point in the curve is the predicted circumferential strength. Analyze and compare each stress-strain curve, if the curve shows a turning point of a downward trend, the turning point is considered to be a damage point, and the smaller the circumferential strain value corresponding to the damage point, the more the corresponding component is damaged first. Among them, the termination judgment method of the iteration is "number of iterations or relative error", the maximum number of iterations is 15 times, and the maximum relative error is 0.05.
[0044] Example 1 Hoop strength simulation of multilayer heterogeneous composite cladding tube with molybdenum (Mo) as metal lining Step S10, Mo-SiC provided by the sample image actually observed by X-ray computed tomography (X-CT) f The geometrical dimension information of the SiC / SiC sample includes the thickness of molybdenum (Mo), interface, matrix, and fiber bundle, which are 0.399 mm, 0.100 mm, 0.475 mm, and 0.205 mm, respectively, the height is 10.000 mm, the inner diameter is 11.000 mm, and the outer diameter is 14.860 mm. The geometrical shape of the sample is reconstructed using COMSOL Multiphysics software to obtain the geometrical model, which also includes the three-layer fiber preform and the interface layer, such as Figure 2 As shown, Figure 2 (a) Mo-SiC f / SiC geometric model stereogram, Figure 2 (b) Mo-SiC f / Top view of SiC geometric model, Figure 2 (c) is a three-layer fiber preform formed by axial fibers and annular fibers, Figure 2 (d) is a partial enlarged view of the three-layer fiber preform.
[0045] Step S20, modifying the relative tolerance value of the geometric model to remove detail defects such as overlaps and gaps in the geometric model that affect mesh division; Step S30, using hexahedral meshes to divide the metal lining into 7270 meshes; using hexahedral meshes to divide the interface into 4362 meshes; using tetrahedral meshes to divide the fiber bundle into 123560 meshes; using tetrahedral meshes to divide the substrate into 167716 meshes.
[0046] Step S40, establishing a curvilinear coordinate system for each component after grid division; Step S50, based on the second coordinate system, Direction, apply to the inner side of the Mo metal lining with 0mm as the starting value, mm is the step length, mm is an increasing series of terminal values, and the remaining faces of the geometric model are regarded as free faces; Step S60, applying the incremental sequence makes the geometric model The displacement in the direction causes strain in each component, which in turn forms stress. As the strain changes, the stress also changes. Therefore, it is necessary to use mechanical constitutive equations suitable for different components to describe the changing stress and strain. The details are as follows: the fourth strength theory is used to determine the initial damage of the metal lining, and the direct stiffness degradation criterion is used to describe its failure behavior; among them, , , are the first, second and third principal stresses of the metal lining, is the shear strength of the metal lining, is the stress tensor of the metal lining, is the strain tensor of the metal lining; The Mohr strength criterion is used to identify the initial damage of the interface, and the direct stiffness degradation criterion is used to describe its failure behavior; is the tensile strength of the interface, is the compressive strength of the interface, , are the first and third principal stresses of the interface, is the stress tensor of the interface, is the strain tensor of the interface; The Hashin criterion is used to identify the initial damage of the circumferential fiber bundle and the axial fiber bundle, and the direct stiffness degradation criterion is used to describe the failure behavior of the axial fiber bundle, and the exponential softening equation is used to describe the damage evolution process of the circumferential fiber bundle. For axial fiber bundles The tensile stress in the direction For axial fiber bundles Tensile strength in the direction is the stress tensor of the axial fiber bundle, is the strain tensor of the axial fiber bundle, is the characteristic length of the annular fiber bundle, for Young's modulus in the direction, is the fracture energy of the annular fiber bundle at the end of the linear change stage, is the fracture energy of the annular fiber bundle at the end of the exponential change stage; The first strength theory is used to determine the initial damage of the matrix, and the direct stiffness degradation criterion is used to describe its failure behavior; For the matrix The tensile stress in the direction of is the tensile strength of the matrix.
[0047] Step S70, using the constant Newton iteration method, solve the above formula to obtain the stress-strain curve of each component after applying the radial displacement series, see Figure 3 ,pass Figure 3 It can be found that the hoop ultimate strength obtained by numerical simulation is 225MPa, which is slightly lower than the ultimate strength of 249.4MPa obtained by experiment, and the relative error is about 10%, indicating that it has high accuracy. When the hoop strain reaches 0.035%, the stress-strain curve obtained by experiment enters a new nonlinear stage from the linear stage, and the stress-strain curve obtained by numerical simulation also has a turning point at this point, that is, it also enters a new stage. When the hoop strain reaches 0.06%, both the experimental and numerical simulation results reach the hoop ultimate strength of the material. In addition, it can be found that the SiC matrix begins to be damaged first (the hoop strain is 0.02%), followed by the axial SiC fiber damage (the hoop strain is 0.022%), then the metal molybdenum liner and interface damage (the hoop strain is 0.06%), and finally the hoop SiC fiber damage, which is consistent with the damage order observed in the experiment.
[0048] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A method for predicting the metal-SiC under the plugging test f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: include: Get Metal-SiC f / Geometric size information of SiC sample, and establishing a geometric model according to the geometric size information, wherein the components of the geometric model include metal lining, interface, matrix, and fiber bundle; Grid division is performed on each component separately; Establish a curvilinear coordinate system for each component after grid division; Based on the curvilinear coordinate system, a radial displacement series is applied to the inner wall surface of the geometric model, and the remaining surfaces of the geometric model are used as free surfaces; Determine the corresponding mechanical constitutive equation according to the material properties of each component; The mechanical constitutive equation is solved to obtain the stress-strain curve of each component after applying the radial displacement series, and the predicted hoop strength is determined based on the stress-strain curve.
2. The method for predicting the expansion and plugging of metal-SiC according to claim 1 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The grid division method is: The metal lining and the interface are divided by a hexahedral grid, and the fiber bundle and the matrix are divided by a tetrahedral grid.
3. The method for predicting the expansion and plugging of metal-SiC according to claim 1 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The fiber bundle includes a circumferential fiber bundle and an axial fiber bundle; the curvilinear coordinate system includes a first coordinate system and a second coordinate system, the curvilinear coordinate system of the axial fiber bundle is the first coordinate system, and the curvilinear coordinate system of the metal lining, interface, matrix and circumferential fiber bundle is the second coordinate system.
4. The method for predicting the metal-SiC under the plugging test according to claim 3 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The method for establishing the first coordinate system includes: The first basis vector of the toroidal fiber bundle is solved by using the Laplace equation, and the second basis vector and the third basis vector are determined according to the first basis vector to obtain the first coordinate system.
5. The method for predicting the metal-SiC under the plugging test according to claim 3 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The method for establishing the second coordinate system includes: converting the Cartesian coordinate system of the component into a cylindrical coordinate system, that is, the second coordinate system.
6. The method for predicting the metal-SiC under the plugging test according to claim 1 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The mechanical constitutive equations corresponding to each component are: The mechanical constitutive equations of metal linings include the fourth strength theory and direct stiffness degradation criterion; The mechanical constitutive equations of the interface include Mohr's strength criterion and direct stiffness degradation criterion; The mechanical constitutive equations of fiber bundles include the Hashin criterion, the direct stiffness degradation criterion corresponding to the axial fiber bundle, and the exponential softening equation corresponding to the circumferential fiber bundle. The mechanical constitutive equation of the matrix includes the first strength theory and the direct stiffness degradation criterion.
7. The method for predicting the metal-SiC under the plugging test according to claim 1. f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The geometric dimension information includes the thickness of the metal liner, interface, matrix and fiber bundle, metal-SiC f / Height, inner diameter and outer diameter of SiC samples.
8. The method for predicting the metal-SiC under the plugging test according to claim 1 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: After the geometric model is established, the following steps are also included: The relative tolerance value of the geometric model is modified to remove overlaps and gaps in the geometric model.
9. The method for predicting the metal-SiC under the plugging test according to claim 1 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The displacement series is: starting with 0 mm, mm is the step length, mm is an increasing sequence of terminal values.
10. The method for predicting the metal-SiC under the plugging test according to claim 1 f A numerical simulation method for the hoop strength of a SiC / SiC multilayer heterogeneous composite cladding tube is characterized in that: The constant Newton iteration method is used to solve the mechanical constitutive equation.