Solidification and heating coupling solving method for CMC (Carboxy Methylated Cellulose) material containing probability model

Abstract

The invention discloses a probabilistic model-containing CMC material solid-thermal coupling solving method, and belongs to the field of engineering thermophysics. According to the method, for mechanical damage of a CMC high-temperature component after long-time service, CMC material micro-scale representative unit cell RVE modeling considering mechanical damage random characteristics is established, and a mechanical damage characteristic mode of the CMC material after long-time service is introduced into an intact RVE model. On the basis of the model, axial and radial thermal boundary conditions are applied respectively, so that the axial heat conductivity coefficient and the radial heat conductivity coefficient of the microscale of the CMC material are obtained, and the corresponding elastic modulus is calculated through a CMC material matrix crack density formula and a stress-strain relation; and establishing a mapping relation between the thermophysical property parameters and the mechanical property parameters of the CMC material when the mechanical damage occurs, and realizing solid-thermal coupling analysis solution of the CMC material after the random mechanical damage occurs. Therefore, the method can improve the temperature field estimation precision of the CMC high-temperature component in a long-time service environment.

Description

Technical Field

[0001] The invention relates to the technical field of engineering thermal physics, and in particular to a solid-thermal coupling solution method for CMC materials including a probability model. Background Art

[0002] CMC material is a high-performance composite material composed of a ceramic matrix, a fiber reinforcement phase, and an interface layer between the matrix and the fiber. It has the characteristics of high temperature resistance, low density, and strong thermal stability. However, its temperature resistance limit of 1623K is still lower than the ultra-high temperature of more than 2200K before the turbine of future advanced aircraft engines. In order to avoid material damage or even failure caused by overheating, corresponding cooling technology is still required to cool the CMC high-temperature components. Therefore, it is necessary to establish a high-precision thermal analysis model of CMC high-temperature components to accurately obtain its temperature field and other characteristics. Due to the microscopic characteristics of the reinforcing fibers in the CMC material itself, there will be obvious differences in the axial thermal conductivity and radial thermal conductivity inside the fiber. Due to the significant differences in strength and thermal conductivity between the reinforcing fibers and the matrix inside the material, the inhomogeneous characteristics lead to the material physical properties such as strength and thermal conductivity of CMC materials showing obvious anisotropy. Therefore, in the design process of high-temperature components of aircraft engines, the thermal analysis method for traditional isotropic metal alloy materials is no longer applicable, and it is necessary to establish an estimation and analysis method for thermal physical parameters such as anisotropic thermal conductivity suitable for CMC materials.

[0003] When an aircraft engine is in operation, its aero-thermal parameters are usually variable. In addition to high thermal loads, the real service environment of CMC materials as high-temperature components also faces aerodynamic loads. Since the temperature of the high-temperature gas discharged from the combustion chamber is non-uniform, there is a large temperature gradient in the hot end components of the aircraft engine. However, CMC materials are more sensitive to thermal stress due to the large difference in thermal expansion coefficients between the fiber and the matrix. NASA reported that when the turbine inlet temperature is higher than 1750K, it is necessary to conduct a detailed analysis of the stress level of the CMC turbine components and have strict requirements. This is because the internal stress caused by the temperature difference has a significant effect on the strength of the internal reinforcing fibers of the CMC. Under the coupling of complex alternating thermal loads, CMC materials will have different characteristic forms and degrees of mechanical damage such as matrix cracks, interface layer debonding and fiber breakage, resulting in changes in the microstructure of the material, affecting the mechanical properties and thermophysical properties of the material, and thus affecting the temperature field of the CMC high-temperature components. In actual engineering applications, CMC materials will inevitably suffer mechanical damage, and due to the heterogeneous characteristics of the material, the equivalent thermal conductivity of CMC materials will show obvious anisotropic characteristics. If the impact of damage is not considered, it will be difficult to accurately predict the temperature field of CMC materials under service conditions. Summary of the invention

[0004] The present invention provides a method for solving the solid-thermal coupling of CMC materials including a probability model. In order to accurately estimate the temperature field of CMC materials after mechanical damage occurs, considering the heterogeneous and anisotropic characteristics of CMC materials, the traditional thermal analysis method based on homogeneous metal materials and without considering the mechanical damage of materials will be difficult to reflect the influence of the mechanical damage characteristics of materials on internal heat transfer, temperature field distribution and thermal stress distribution. Therefore, a solid-thermal coupling solution of CMC materials including a probability model is carried out to achieve accurate estimation of the temperature field and thermal stress of CMC materials after mechanical damage occurs.

[0005] The embodiment of the present invention provides a method for solving the solid-thermal coupling of CMC materials including a probabilistic model, comprising the following steps:

[0006] Step 1: Use the commercial software COMSOL to construct a parametric model of the intact CMC material microstructure RVE;

[0007] Step 2: Based on the mechanical damage characteristics of CMC materials, the random function in COMSOL is used to randomly introduce the mechanical damage characteristics into the intact and undamaged CMC material micro-foundation RVE parameterized model;

[0008] Step 3: Apply thermal boundary conditions in the axial and radial directions of the micro-foundation RVE model, and use COMSOL to analyze the effects of different mechanical damages and their mechanical damage characteristics on the axial thermal conductivity and radial thermal conductivity of the CMC material after mechanical damage occurs;

[0009] Step 4: By changing the size of the fiber diameter, the influence of the random distribution of fiber diameter on the radial thermal conductivity and axial thermal conductivity of the CMC material is studied. By changing the amount of damage introduced into the intact CMC material microfoundation RVE parametric model, the damage rate of the CMC material is changed. The influence of the damage rate on the axial thermal conductivity and radial thermal conductivity of the CMC material is studied and analyzed. The elastic modulus of the CMC material at different damage rates is calculated through the crack density of the CMC material matrix and the stress-strain relationship. The mapping function relationship between the thermophysical properties and the mechanical performance parameters of the CMC material after mechanical damage is established, and the solid-thermal coupling analysis and solution of the CMC material after mechanical damage is realized.

[0010] Optionally, in one embodiment of the present invention, in step 1, the commercial software COMSOL is used to construct an intact and undamaged parameterized micro-foundation RVE model of CMC materials. The micro-foundation RVE model is established based on the SEM photograph of the CMC material, and includes fibers, an interface layer and a matrix. The various dimensional parameters of the micro-foundation RVE model are assigned through the defined parameters in COMSOL to achieve parametric modeling.

[0011] Optionally, in one embodiment of the present invention, in step 2, the mechanical damage characteristics of the CMC material are obtained based on the SEM photograph of the CMC material, a random function is generated in COMSOL, the damage position is assigned by the generated random function, and the mechanical damage characteristics are introduced into the micro-foundation RVE parameterized model of the intact and undamaged CMC material.

[0012] Optionally, in one embodiment of the present invention, in step 3, the mechanical damage feature refers to the position where the mechanical damage occurs in the CMC material and the fiber diameter of the CMC material. By generating a random function in COMSOL, the mechanical damage position of the CMC material and the fiber diameter of the CMC material are randomly assigned. By setting two different axial and radial thermal boundary conditions for the micro-foundation RVE model, the physical field information of the axial temperature field, heat flux density field and radial temperature field of the CMC material after mechanical damage is obtained, the influence of different damage forms on the internal heat transfer of the CMC material is analyzed, and the axial thermal conductivity and radial thermal conductivity of the CMC material are calculated using the Fourier formula.

[0013] Optionally, in one embodiment of the present invention, in step 3, the axial thermal conductivity and radial thermal conductivity of the CMC material are calculated using the Fourier formula as follows:

[0014]

[0015] Where k is the axial thermal conductivity and radial thermal conductivity, q is the amount of heat passing through a unit area section per unit time, Δx is the length change perpendicular to the unit area section, and ΔT is the temperature change perpendicular to the unit area section.

[0016] Optionally, in one embodiment of the present invention, in step 4, the calculation method of the crack density of the CMC material matrix is:

[0017]

[0018] Where D is the matrix crack density, D sat is the final density when the crack reaches saturation, σ is the stress on the CMC material, and σ m and m are statistical parameters;

[0019] The stress-strain relationship is:

[0020]

[0021] Where ε is the strain of the CMC material, E f is the fiber elastic modulus, L is the matrix crack spacing, V f is the volume fraction of the fiber, d is the debonding length of the CMC material interface layer, r f is the diameter of the fiber, σf0 is the normal stress of the CMC material when it is not damaged, α f is the thermal expansion coefficient of the fiber, α c is the thermal expansion coefficient of the CMC material, ΔT 1 The temperature difference from the preparation of CMC material to cooling to room temperature;

[0022] The elastic modulus of CMC materials at different damage rates is calculated by the crack density of CMC material matrix and the stress-strain relationship:

[0023]

[0024] Where, E is the elastic modulus of CMC material;

[0025] The mapping function relationship between the thermophysical parameters and mechanical performance parameters of CMC materials after mechanical damage is established to achieve the solid-thermal coupling analysis and solution of CMC materials after mechanical damage:

[0026] σ T =E(ε-αΔT 1 )

[0027] In the formula, σ T is the thermal stress on the CMC material, and α is the thermal expansion coefficient of the CMC material.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention aims to accurately estimate the temperature field and thermal stress requirements of high-temperature parts of CMC materials of aircraft engines after mechanical damage occurs. Based on the establishment of a parametric model of CMC materials considering mechanical damage, the influence of mechanical damage on the temperature field distribution and internal heat transfer of CMC materials is studied, and then a solid-thermal coupling solution method for CMC materials including a probabilistic model is established. The present invention establishes a material microscopic model considering mechanical damage of CMC materials, solves the modeling problem considering mechanical damage of CMC materials, and can improve the accuracy of temperature field estimation of CMC high-temperature parts under long-term service environment.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0032] Figure 1 A flowchart of a method for solving solid-thermal coupling of CMC materials including a probabilistic model provided according to an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a micro-foundation RVE parameterized model of an intact and undamaged CMC material according to an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of a micro-foundation RVE parameterized model of a CMC material that introduces mechanical damage according to an embodiment of the present invention;

[0035] Figure 4 It is a structured grid division diagram of the micro-foundation RVE parameterized model of an embodiment of the present invention;

[0036] Figure 5 It is a diagram for setting boundary conditions of the micro-foundation RVE parameterized model of an embodiment of the present invention;

[0037] Figure 6 This is a CMC material turbine blade model according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0039] The following describes a method for solving the solid-thermal coupling of CMC materials including a probabilistic model in an embodiment of the present invention with reference to the accompanying drawings. In view of the problem that the equivalent thermal conductivity of CMC materials mentioned in the background technology center will show obvious anisotropic characteristics, if the influence caused by damage is not considered, it will be difficult to accurately estimate the temperature field of CMC materials in the service state, the present invention provides a method for solving the solid-thermal coupling of CMC materials including a probabilistic model, in which an analysis of the anisotropic thermal conductivity of CMC materials considering mechanical damage is carried out, and a micro-scale analysis model reflecting the mechanical damage characteristics of the material is established, and under constant temperature boundary conditions in different directions, the influence of different damage characteristics and different degrees of damage rates on the thermal conductivity of the material in different directions is analyzed, and the influence of mechanical damage on the equivalent thermal conductivity of the material and the internal heat transfer mechanism is explored, and then a method for solving the solid-thermal coupling of CMC materials considering mechanical damage is established.

[0040] Figure 1 The present invention provides a flowchart of a method for solving the solid-thermal coupling of CMC materials including a probabilistic model according to an embodiment of the present invention.

[0041] like Figure 1 As shown, the solid-thermal coupling solution method of CMC material including the probability model includes the following steps:

[0042] Step 1: Use the commercial software COMSOL to construct a parametric model of the intact CMC material microfoundation RVE.

[0043] In one embodiment of the present invention, in step 1, the commercial software COMSOL is used to construct an intact and undamaged parameterized micro-foundation RVE model of CMC materials. The micro-foundation RVE model is established based on the SEM photograph of the CMC material, and includes fibers, an interface layer and a matrix. The various dimensional parameters of the micro-foundation RVE model are assigned through the defined parameters in COMSOL to achieve parametric modeling.

[0044] Step 2: Based on the mechanical damage characteristics of CMC materials, the random function in COMSOL is used to randomly introduce the mechanical damage characteristics into the intact and undamaged CMC material microfoundation RVE parameterized model.

[0045] In one embodiment of the present invention, in step 2, the mechanical damage characteristics of the CMC material are obtained based on the SEM photograph of the CMC material, a random function is generated in COMSOL, the damage position is assigned by the generated random function, and the mechanical damage characteristics are introduced into the micro-foundation RVE parameterized model of the intact and undamaged CMC material.

[0046] Step 3: Apply thermal boundary conditions in the axial and radial directions of the micro-foundation RVE model, and use COMSOL to analyze the effects of different mechanical damages and their mechanical damage characteristics on the axial thermal conductivity and radial thermal conductivity of the CMC material after mechanical damage occurs.

[0047] In one embodiment of the present invention, in step 3, the mechanical damage feature refers to the position where the mechanical damage occurs in the CMC material and the fiber diameter of the CMC material. By generating a random function in COMSOL, the mechanical damage position of the CMC material and the fiber diameter of the CMC material are randomly assigned. By setting two different axial and radial thermal boundary conditions for the micro-foundation RVE model, the physical field information of the axial temperature field, heat flux density field and radial temperature field of the CMC material after mechanical damage is obtained, the influence of different damage forms on the internal heat transfer of the CMC material is analyzed, and the axial thermal conductivity and radial thermal conductivity of the CMC material are calculated using the Fourier formula.

[0048] Furthermore, the axial thermal conductivity and radial thermal conductivity of the CMC material are calculated using the Fourier formula:

[0049]

[0050] Where k is the axial thermal conductivity and radial thermal conductivity, q is the amount of heat passing through a unit area section per unit time, Δx is the length change perpendicular to the unit area section, and ΔT is the temperature change perpendicular to the unit area section.

[0051] Step 4: By changing the size of the fiber diameter, the influence of the random distribution of fiber diameter on the radial thermal conductivity and axial thermal conductivity of the CMC material is studied. By changing the amount of damage introduced into the intact CMC material microfoundation RVE parametric model, the damage rate of the CMC material is changed. The influence of the damage rate on the axial thermal conductivity and radial thermal conductivity of the CMC material is studied and analyzed. The elastic modulus of the CMC material at different damage rates is calculated through the crack density of the CMC material matrix and the stress-strain relationship. The mapping function relationship between the thermophysical properties and the mechanical performance parameters of the CMC material after mechanical damage is established, and the solid-thermal coupling analysis and solution of the CMC material after mechanical damage is realized.

[0052] In step 4, mechanical damage with different characteristics is introduced to study the effects of different mechanical damage forms on CMC materials. The damage rate of CMC materials is changed by introducing different numbers of damage characteristics. The calculation conditions with damage rates of 0%, 1%, 2%, 3% and 5% are set to study the effects of different damage degrees on CMC materials.

[0053] In one embodiment of the present invention, in step 4, the calculation method of the crack density of the CMC material matrix is:

[0054]

[0055] Where D is the matrix crack density, D sat is the final density when the crack reaches saturation, σ is the stress on the CMC material, and σ m and m are statistical parameters. In this example, m = 5, σ m =160MPa,D sat =2.5mm -1 .

[0056] The stress-strain relationship is:

[0057]

[0058] Where ε is the strain of the CMC material, E f is the fiber elastic modulus, L is the matrix crack spacing, V f is the volume fraction of the fiber, d is the debonding length of the CMC material interface layer, r f is the diameter of the fiber, σ f0 is the normal stress of the CMC material when it is not damaged, α f is the thermal expansion coefficient of the fiber, α c is the thermal expansion coefficient of the CMC material, ΔT 1 The temperature difference from the preparation of CMC material to cooling to room temperature;

[0059] The elastic modulus of CMC materials at different damage rates is calculated by the crack density of CMC material matrix and the stress-strain relationship:

[0060]

[0061] Where, E is the elastic modulus of CMC material;

[0062] The mapping function relationship between the thermophysical parameters and mechanical performance parameters of CMC materials after mechanical damage is established to achieve the solid-thermal coupling analysis and solution of CMC materials after mechanical damage:

[0063] σ T =E(ε-αΔT 1 )

[0064] In the formula, σ T is the thermal stress on the CMC material, and α is the thermal expansion coefficient of the CMC material.

[0065] The method of the embodiment of the present invention aims at the mechanical damage of CMC high-temperature components after long-term service, establishes a representative single-cell RVE model of CMC materials at the microscale taking into account the random characteristics of mechanical damage, and introduces the characteristic modes of mechanical damage such as matrix cracks, interface layer debonding and fiber fracture that occur in CMC materials after long-term service into the intact RVE model, and the spacing of different damage characteristics is generated by random functions. Based on this model, by applying axial and radial thermal boundary conditions respectively, the microscale axial thermal conductivity and radial thermal conductivity of CMC materials are obtained, and the corresponding elastic modulus is calculated by the formula of matrix crack density of CMC materials and the stress-strain relationship, and the mapping relationship between the thermal physical property parameters and mechanical performance parameters of CMC materials when mechanical damage occurs is established, so as to realize the solid-thermal coupling analysis and solution of CMC materials after random mechanical damage occurs.

[0066] The present invention is further described below in conjunction with an embodiment. This example demonstrates the specific implementation steps of the CMC material solid-thermal coupling solution method including a probabilistic model. The model used in this example is as follows: Figure 2 and Figure 3 As shown in the figure, the model is the micro-basic RVE parameterized model of intact CMC material and the micro-basic RVE parameterized model of CMC material with mechanical damage. The length of the basic RVE parameterized model is L, the width of the basic RVE parameterized model is W, and the width of the matrix crack is l m , the debonding length of the interface layer is l i , the width of the fiber break is l f , the diameter of the fiber is d f The thickness of the interface layer is d i , the volume fraction of the fiber is V f,The detailed dimensions of the basic RVE parameterized model are shown in Table 1. The spacing of mechanical damage of CMC materials is generated by the random function of COMSOL.

[0067] Table 1 Detailed size parameters of basic RVE parameterized model

[0068]

[0069] First, the parameters are input in the global definition of COMSOL to define the size parameters of the above RVE model, which is convenient for the parametric modeling of the basic intact model. Then, the random function is selected to randomly introduce the mechanical damage of the CMC material into the basic intact RVE model. Then the material parameters are assigned and the thermal boundary conditions are set. The matrix and interface layer are isotropic materials, and the thermal conductivities are set to 16 and 25 W / (K·m), respectively. The fiber is anisotropic material, and the thermal conductivity is set to {4,40,4} W / (K·m), where the axial thermal conductivity is 40 W / (K·m) and the radial thermal conductivity is 4 W / (K·m). In order to study and analyze the effect of mechanical damage on the anisotropic thermal conductivity of CMC materials, it is necessary to set the axial thermal boundary conditions and radial thermal boundary conditions respectively to obtain the axial heat flux and radial heat flux of CMC materials, and then the axial thermal conductivity and radial thermal conductivity are obtained by Fourier formula. The axial thermal boundary conditions are set as follows: one of the two surfaces on the XOZ plane is set as a low-temperature surface of 1900K, and the other is set as a high-temperature surface of 1200K. The remaining four outer surfaces of the RVE model are set as periodic boundary conditions. Similarly, the radial thermal boundary conditions are set as follows: one of the two surfaces on the XOY plane is set as a low-temperature surface of 1900K, and the other is set as a high-temperature surface of 1200K. The remaining four outer surfaces of the RVE model are set as periodic boundary conditions. The mechanical damage site of the CMC material is air, and air is selected as the material assignment. In meshing, in order to improve the calculation accuracy and reduce unnecessary consumption of computing resources, the heat flux density value on the center line of the RVE model is taken as a reference for mesh independence verification. At the same time, due to the small characteristic size of the damage, the mesh of the mechanical damage site of the CMC material needs to be encrypted. Structured grids are generated for fibers, interface layers and mechanical damage, and unstructured grids are generated for the matrix, such as Figure 4 and Figure 5 shown.

[0070] After calculating and analyzing the heat flux cloud map of CMC material after mechanical damage, it is found that mechanical damage will change the heat transfer path inside the CMC material, and the heat flux of CMC material will increase suddenly where the mechanical damage contacts the material area, which indicates that mechanical damage will increase the potential high thermal stress area inside the CMC material. In this example calculation condition, when the material damage rate is 5%, the axial thermal conductivity and radial thermal conductivity of the material are the minimum values ​​in all calculation conditions, which are 16.2456W / (m·K) and 10.1733W / (m·K), respectively, which are 34.5% and 5.32% lower than those of the intact material. By changing the material fiber diameter between 6 and 7μm, the average axial thermal conductivity of the material is calculated to be 23.72W / (m·K), with a standard deviation of 0.9385; the average radial thermal conductivity of the material is 11.34W / (m·K), with a standard deviation of 0.519.

[0071] In this example, the following two formulas were used to calculate the mechanical properties of CMC materials. Formula (1) can be used to calculate the normal stress received by the material from the matrix crack density, and then formula (2) can be used to calculate the strain of the material at this time, and thus the elastic modulus of the material can be calculated.

[0072]

[0073] Among them, m and σ m is a statistical parameter, D sat is the final density when the crack is saturated. In this example, m = 5, σ m =160MPa,D sat =2.5mm -1 The remaining parameters are shown in Table 2.

[0074] Table 2 CMC material parameters

[0075]

[0076] The thermal conductivity and Young's modulus of the material are calculated, and the fitted thermal conductivity and Young's modulus functional relationships in the X, Y and Z directions are: K X =0.0401E X +5.5512, K Y =0.0102E Y +6.7896, K Z =0.0616E Z +3.0644.

[0077] CMC material turbine blade simulation calculation model Figure 6As shown in the figure, the calculation results show that the average temperature of the blade with a 5% damage rate is 447.2K, and the average temperature of the blade with an intact blade is 441.6K, an increase of 1.27%. The maximum stress of the blade with a 5% damage rate is 8.02MPa, and the maximum stress of the intact blade is 7.71MPa, an increase of 4.02%. This is because as the material damage increases, the thermal conductivity and elastic modulus of the material decrease, making it easier to have local high temperature and high stress areas.

[0078] The present invention aims at accurately estimating the temperature field of CMC materials after mechanical damage occurs. Considering the heterogeneous and anisotropic characteristics of CMC materials, the traditional thermal analysis method based on homogeneous metal materials and without considering the mechanical damage of materials will be difficult to reflect the influence of the mechanical damage characteristics of materials on internal heat transfer, temperature field distribution and thermal stress distribution. Therefore, it is necessary to carry out the solid-thermal coupling solution of CMC materials including probabilistic models to achieve accurate estimation of thermal conductivity, temperature field and thermal stress of CMC materials after mechanical damage occurs.

[0079] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0080] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0081] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

Claims

1. A method for solving the solid-thermal coupling of CMC materials including a probabilistic model, characterized in that: The following steps are involved: Step 1: Use the commercial software COMSOL to construct a parametric model of the intact CMC material microstructure RVE; Step 2: Based on the mechanical damage characteristics of CMC materials, the random function in COMSOL is used to randomly introduce the mechanical damage characteristics into the intact and undamaged CMC material micro-foundation RVE parameterized model; Step 3: Apply thermal boundary conditions in the axial and radial directions of the micro-foundation RVE model, and use COMSOL to analyze the effects of different mechanical damages and their mechanical damage characteristics on the axial thermal conductivity and radial thermal conductivity of the CMC material after mechanical damage occurs; Step 4: By changing the size of the fiber diameter, the influence of the random distribution of fiber diameter on the radial thermal conductivity and axial thermal conductivity of the CMC material is studied. By changing the amount of damage introduced into the intact CMC material microfoundation RVE parametric model, the damage rate of the CMC material is changed. The influence of the damage rate on the axial thermal conductivity and radial thermal conductivity of the CMC material is studied and analyzed. The elastic modulus of the CMC material at different damage rates is calculated through the crack density of the CMC material matrix and the stress-strain relationship. The mapping function relationship between the thermophysical properties and the mechanical performance parameters of the CMC material after mechanical damage is established, and the solid-thermal coupling analysis and solution of the CMC material after mechanical damage is realized.

2. The method according to claim 1, characterized in that In step 1, the commercial software COMSOL is used to construct an intact and undamaged parametric micro-foundation RVE model of CMC materials. The micro-foundation RVE model is established based on the SEM photograph of the CMC material and includes fibers, interface layers and matrix. The various dimensional parameters of the micro-foundation RVE model are assigned through the defined parameters in COMSOL to achieve parametric modeling.

3. The method according to claim 1, characterized in that In step 2, the mechanical damage characteristics of the CMC material are obtained based on the SEM photos of the CMC material, and a random function is generated in COMSOL. The damage position is assigned by the generated random function, and the mechanical damage characteristics are introduced into the micro-foundation RVE parameterized model of the intact and undamaged CMC material.

4. The method according to claim 1, characterized in that In step 3, the mechanical damage characteristics refer to the location where the mechanical damage of the CMC material occurs and the fiber diameter of the CMC material. By generating a random function in COMSOL, the mechanical damage location of the CMC material and the fiber diameter of the CMC material are randomly assigned. By setting two different axial and radial thermal boundary conditions for the micro-foundation RVE model, the physical field information of the axial temperature field, heat flux density field and radial temperature field of the CMC material after mechanical damage is obtained, and the influence of different damage forms on the internal heat transfer of the CMC material is analyzed. The axial thermal conductivity and radial thermal conductivity of the CMC material are calculated using the Fourier formula.

5. The method according to claim 4, characterized in that In step 3, the axial thermal conductivity and radial thermal conductivity of the CMC material are calculated using the Fourier formula: Where k is the axial thermal conductivity and radial thermal conductivity, q is the amount of heat passing through a unit area section per unit time, Δx is the length change perpendicular to the unit area section, and ΔT is the temperature change perpendicular to the unit area section.

6. The method according to claim 1, characterized in that In step 4, the crack density of the CMC material matrix is ​​calculated as: Where D is the matrix crack density, D sat is the final density when the crack reaches saturation, σ is the stress on the CMC material, and σ m and m are statistical parameters; The stress-strain relationship is: Where ε is the strain of the CMC material, E f is the fiber elastic modulus, L is the matrix crack spacing, V f is the volume fraction of the fiber, d is the debonding length of the CMC material interface layer, r f is the diameter of the fiber, σ f0 is the normal stress of the CMC material when it is not damaged, α f is the thermal expansion coefficient of the fiber, α c is the thermal expansion coefficient of CMC material, ΔT1 is the temperature difference from the preparation of CMC material to cooling to room temperature; The elastic modulus of CMC materials at different damage rates is calculated by the crack density of CMC material matrix and the stress-strain relationship: Where, E is the elastic modulus of CMC material; The mapping function relationship between the thermophysical parameters and mechanical performance parameters of CMC materials after mechanical damage is established to achieve the solid-thermal coupling analysis and solution of CMC materials after mechanical damage: s T =E(ε-αΔT1) In the formula, σ T is the thermal stress on the CMC material, and α is the thermal expansion coefficient of the CMC material.

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