Method for calculating shear modulus of each component of si c / si c fiber bundle composite material

Abstract

The application discloses a kind of SiC / SiC fiber bundle composite component shear modulus calculation method, the present application establishes the SiC / SiC fiber bundle composite fiber and matrix shear modulus calculation model considering temperature influence, and in calculation model, the influence of the number of fiber internal breakage on fiber shear modulus and the influence of matrix deposition uneven and pore on matrix shear modulus is added, the accurate calculation of SiC / SiC fiber bundle composite component shear modulus is realized.The method of the present application is not limited to single temperature, not limited to single material component content, and is applicable to the calculation of SiC / SiC fiber bundle composite shear modulus at different temperatures and different component contents.The method of the present application has clear process, and is easy to implement and calculate.

Description

Technical Field

[0001] This invention belongs to the field of mechanical behavior testing of composite materials, specifically relating to a method for calculating the shear modulus of each component of a SiC / SiC fiber bundle composite material. Background Technology

[0002] Fiber-reinforced ceramic matrix composites, especially ceramic matrix composites, possess lightweight, high strength, and high-temperature resistance, making them ideal high-temperature structural candidates to replace high-temperature alloys in hot-end components of aerospace vehicles. Currently, SiC / SiC composites have been successfully applied to hot-end components of aero-engines such as the F136, F414, and LEAP-X. When SiC / SiC composites are used as hot-end components in aerospace vehicles, their high-temperature in-plane shear performance is one of the important indicators characterizing the material's high-temperature performance and evaluating the component. Ceramic matrix fiber bundle composites are the main load-bearing units in braided ceramic matrix composites, and their mechanical properties are the main factors determining the overall mechanical properties of braided ceramic matrix composites.

[0003] Currently, there are three main methods for calculating the shear modulus of SiC / SiC fiber bundle composites: the series-parallel mixing ratio model, the Masuji Uemura model, and the Halpin-Tsai model. In all three models, the shear modulus of each component within the composite material must first be calculated. Due to the characteristics of the SiC / SiC fiber bundle composite material manufacturing process, defects such as partial fiber breakage, uneven matrix deposition, and porosity are unavoidable within the material. Furthermore, under high-temperature conditions, the thermal stress further exacerbates these internal defects, increasing their impact on the material's shear mechanical properties. For example, partial fiber breakage reduces the number of load-bearing fibers within the material, directly leading to a decrease in the overall shear modulus of the fibers. The number of broken fibers increases further at high temperatures compared to room temperature. Uneven matrix deposition causes inconsistent deformation between the material's interior and exterior, affecting the transmission of shear loads. The presence of pores reduces the effective cross-sectional area of ​​the material, resulting in a loose internal structure that significantly impacts the matrix's shear modulus. Furthermore, at high temperatures, the pores and loose matrix within the material are damaged by thermal stress, further reducing the shear modulus of the matrix components. However, current research lacks studies on the temperature-dependent changes in the shear modulus of various components in SiC / SiC fiber bundle composites under high-temperature, oxygen-free conditions, making accurate calculation of the shear modulus of ceramic matrix fiber bundle composites under high-temperature, oxygen-free conditions impossible.

[0004] Therefore, it is necessary to provide a method for calculating the shear modulus of each component of SiC / SiC fiber bundle composites under high temperature and oxygen-free conditions, so as to achieve accurate calculation of the shear elastic modulus of SiC / SiC fiber bundle composites. Summary of the Invention

[0005] To overcome the problems mentioned in the background art, this invention provides a method for calculating the shear modulus of each component in SiC / SiC fiber bundle composite materials. To achieve the above technical objective, the technical solution adopted by this invention is as follows:

[0006] A method for calculating the shear modulus of each component in a SiC / SiC fiber bundle composite material, characterized by the following steps:

[0007] Step 1: Establish a calculation model for the shear modulus of SiC / SiC fiber bundle composite materials considering the effect of temperature;

[0008] Step 2: In the fiber shear modulus calculation model section of Step 1, the influence of the number of internal fiber fractures on the fiber shear modulus is added to establish a calculation model for the fiber component shear modulus of SiC / SiC fiber bundle composite material under the combined influence of temperature and the number of internal fiber fractures.

[0009] Step 3: In the matrix shear modulus calculation model section of Step 1, the effects of matrix deposition inhomogeneity and porosity on the matrix shear modulus are added to establish a calculation model for the shear modulus of SiC / SiC fiber bundle composite matrix components under the combined influence of temperature and matrix damage.

[0010] Step 4: Determine the number of broken fibers inside the SiC / SiC fiber bundle composite material through testing;

[0011] Step 5: Determine the matrix density and porosity of the SiC / SiC fiber bundle composite material by testing;

[0012] Step 6: Substitute the data obtained in Step 4 into the model established in Step 2 to obtain the shear modulus of the fiber component of the SiC / SiC fiber bundle composite material;

[0013] Step 7: Substitute the data obtained in Step 5 into the model established in Step 3 to obtain the shear modulus of the SiC / SiC fiber bundle composite matrix components.

[0014] To optimize the above technical solution, the specific measures also include:

[0015] In step 1, the calculation model for the shear modulus of SiC / SiC fiber bundle composite fibers considering the effect of temperature is as follows:

[0016]

[0017] The calculation model for the shear modulus of the SiC / SiC fiber bundle composite matrix considering the effect of temperature is as follows:

[0018]

[0019] Among them G T-f G represents the high-temperature shear modulus of fiber. T-m E represents the high-temperature shear modulus of the matrix. T-f E represents the high-temperature elastic modulus of the fiber in a fiber bundle composite material. T-m E represents the high-temperature elastic modulus of the ceramic matrix fiber bundle composite matrix. f-0 E represents the room-temperature elastic modulus of the fibers in ceramic matrix fiber bundle composites. m-0 This represents the room-temperature elastic modulus of the ceramic matrix fiber bundle composite matrix, where T represents the ambient temperature of the material, R represents the fiber diameter, and μ is the unit of measurement. T-m μ represents the matrix Poisson's ratio. T-f k represents the Poisson's ratio of the fiber. T-f k represents the factor affecting fiber high-temperature fracture. T-m This indicates the matrix damage influencing factor.

[0020] In step 2, the calculation model for the shear modulus of the SiC / SiC fiber bundle composite material, which is affected by both temperature and the number of internal fiber fractures, is as follows:

[0021] k T-f =FBR;

[0022]

[0023]

[0024] Where FBR represents the fiber breakage ratio, n brk N represents the number of broken fibers. A This indicates the total number of fibers inside the material.

[0025] In step 3, the calculation model for the shear modulus of the SiC / SiC fiber bundle composite matrix component under the combined influence of temperature and matrix damage is as follows:

[0026] k T-m =MD+P;

[0027] MD=αρ m ;

[0028]

[0029]

[0030] Where MD represents matrix compactness, P represents porosity, α represents density influence factor, and ρ m A represents the matrix density. p A represents the void area. a A represents the total area of ​​the material. f This represents the total cross-sectional area of ​​the fiber.

[0031] In step 4, the specific method for determining the number of broken fibers inside the SiC / SiC fiber bundle composite material by detection is as follows:

[0032] S4.1 Use XCT technology to scan and capture images of the internal structure of SiC / SiC fiber bundle composite material after high-temperature oxygen-free treatment, and count the total number of fibers and the number of broken fibers under different slice views.

[0033] S4.2 Calculate the average number of broken fibers based on the total number of fibers and the number of broken fibers under different slices, and obtain the proportion of the number of broken fibers in the total number of fibers.

[0034] In step 5, the specific method for determining the matrix density and porosity of the SiC / SiC fiber bundle composite material by detection is as follows:

[0035] S5.1 The total volume of the material can be measured non-destructively using the drainage method. The total mass of the material is measured using a high-precision electronic scale, and the matrix density can be obtained by subtracting the fiber portion.

[0036] S5.2 Use a scanning electron microscope to take cross-sectional images of SiC / SiC fiber bundle composite materials after high-temperature oxygen-free treatment, and count the pore pixel area within the field of view;

[0037] S5.3 The actual pore area in S5.2 is calculated using the scale used when taking pictures with a scanning electron microscope, and the pore content is obtained.

[0038] The beneficial effects of this invention are:

[0039] 1. This invention takes into account the effects of temperature and internal material defects, and achieves accurate calculation of the shear modulus of each component of SiC / SiC fiber bundle composite material.

[0040] 2. The method of the present invention is not limited to a single temperature or a single material component content. It is applicable to the calculation of the shear modulus of SiC / SiC fiber bundle composite materials with different temperatures and different component contents.

[0041] 3. The method of this invention has a clear process and is easy to implement and calculate. Attached Figure Description

[0042] Figure 1 This is a flowchart of the calculation process of this invention;

[0043] Figure 2 This is a comparison chart of the calculation results of the model considering the effects of temperature and defects in this invention and the experimental results. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0045] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0046] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0047] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or units (elements) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms “multiple” / “several” used in this application refer to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can indicate: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0048] This embodiment uses a high-temperature oxygen-free shear modulus calculation model for 2K-SiC / SiC fiber bundle composite materials as an example.

[0049] Step 1: Establish a calculation model for the shear modulus of SiC / SiC fiber bundle composite material considering the influence of temperature, and obtain the influence law of temperature on each component.

[0050] In this embodiment, the calculation model is as follows:

[0051]

[0052]

[0053] Among them G T-f G represents the high-temperature shear modulus of fiber. T-m E represents the high-temperature shear modulus of the matrix. T-f E represents the high-temperature elastic modulus of the fiber in a fiber bundle composite material. T-m E represents the high-temperature elastic modulus of the ceramic matrix fiber bundle composite matrix. f-0 E represents the room-temperature elastic modulus of the fibers in ceramic matrix fiber bundle composites. m-0 This represents the room-temperature elastic modulus of the ceramic matrix fiber bundle composite matrix, where T represents the ambient temperature of the material, R represents the fiber diameter, and μ is the unit of measurement. T-mIndicates the Poisson's ratio of the matrix components, μ T-f k represents the Poisson's ratio of the fiber components. T-f k represents the factor affecting fiber high-temperature fracture. T-m This indicates the matrix damage influencing factor.

[0054] In this embodiment, the specific values ​​of the above parameters are: E f-0 =21.504 GPa, E m-0 =139.704 GPa, μ T-f =0.2, μ T-m =0.18, R=10μm.

[0055] Step 2: In the fiber shear modulus calculation model section of Step 1, establish a numerical model that includes fiber damage, calculate the influence of the number of internal fiber fractures on the fiber shear modulus, and establish a calculation model for the shear modulus of SiC / SiC fiber bundle composite fiber components that is affected by both temperature and the number of internal fractures.

[0056] In this embodiment, the calculation model is as follows:

[0057] k T-f =FBR

[0058]

[0059]

[0060] Where FBR represents the fiber breakage ratio, n brk N represents the number of broken fibers. A This indicates the total number of fibers inside the material.

[0061] Step 3: In the matrix shear modulus calculation model section of Step 1, establish a numerical model that includes matrix damage, calculate the influence of matrix deposition inhomogeneity and porosity on the matrix shear modulus, and establish a calculation model for the shear modulus of SiC / SiC fiber bundle composite matrix components under the combined influence of temperature and matrix damage.

[0062] In this embodiment, the calculation model is as follows:

[0063] k T-m =MD+P

[0064] MD=αρ m

[0065]

[0066]

[0067] Where MD represents matrix compactness, P represents porosity, α represents density influence factor, and ρm A represents the matrix density. p A represents the void area. a A represents the total area of ​​the material. f This represents the total cross-sectional area of ​​the fiber.

[0068] In this embodiment, the specific value of the above parameters is: α = 1.849.

[0069] Step 4: Determine the number of broken fibers inside the SiC / SiC fiber bundle composite material through testing:

[0070] 4.1 XCT technology was used to scan and capture images of the internal structure of SiC / SiC fiber bundle composite material after high-temperature oxygen-free treatment, and the number of broken fibers under different slice fields of view was counted.

[0071] 4.2 Count the number of fibers under different slices and calculate the average number of broken fibers n brk The percentage of broken fibers in the total number of fibers, FBR, is obtained.

[0072]

[0073] In this embodiment, the fibers used to prepare the SiC / SiC fiber bundle composite material are Shincolon-II-XS-2K, therefore N A =2000. The specific values ​​of the other parameters are, n brk =87, FBR=0.0435.

[0074] Step 5: Determine the matrix density and porosity of the SiC / SiC fiber bundle composite material by testing:

[0075] S5.1 The total volume of the material can be measured non-destructively using the displacement method. The total mass of the material is measured using a high-precision electronic scale, and the density ρ of the matrix component is obtained by subtracting the fiber portion. m ;

[0076] S5.2 Use a scanning electron microscope to take cross-sectional images of SiC / SiC fiber bundle composite materials after high-temperature oxygen-free treatment, and count the pore pixel area within the field of view;

[0077] S5.3 Calculate the actual pore area A in step S5.2 using the scale used when taking the image with a scanning electron microscope. p ;

[0078]

[0079] In this embodiment, the specific value of the parameter is ρ m =3.24g / cm 3 A p =69843.086μm2 A a =1415673.841μm 2 A f =157000μm 2 .

[0080] Step 6: Substitute the data obtained in Step 4 into the model established in Step 2 to obtain the shear modulus of the fiber component of the SiC / SiC fiber bundle composite material; substitute the data obtained in Step 5 into the model established in Step 3 to obtain the shear modulus of the matrix component of the SiC / SiC fiber bundle composite material.

[0081] Step 7: Substitute the shear modulus of each component into the Halpin-Tasi model to calculate the high-temperature oxygen-free shear modulus of the SiC / SiC fiber bundle composite material. Figure 2 ).

[0082] In this embodiment, the average absolute error between the experimental results and the model calculation results is 5.791%, which verifies that the method of the present invention is effective and highly accurate.

[0083] By using the final temperature-dependent shear modulus calculation model for SiC / SiC fiber bundle composites, combined with the Halpin-Tasi model, the shear modulus of SiC / SiC fiber bundle composites under high-temperature and oxygen-free conditions can be accurately calculated. This enables the assessment of the shear resistance of SiC / SiC fiber bundle composites under high-temperature and oxygen-free conditions, filling the gap in the calculation method of shear modulus of SiC / SiC fiber bundle composites under high-temperature conditions. It also solves the problem of accurately calculating the shear modulus of SiC / SiC fiber bundle composites under different ambient temperatures in practical engineering applications, providing theoretical and data support for the subsequent application of SiC / SiC composite structural components.

[0084] The above are preferred embodiments of this application. However, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0085] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for calculating the shear modulus of each component in a SiC / SiC fiber bundle composite material, characterized by: Includes the following steps: Step 1: Establish a calculation model for the shear modulus of SiC / SiC fiber bundle composite materials considering the effect of temperature; Step 2: In the fiber shear modulus calculation model section of Step 1, the influence of the number of internal fiber fractures on the fiber shear modulus is added to establish a calculation model for the fiber component shear modulus of SiC / SiC fiber bundle composite material under the combined influence of temperature and the number of internal fiber fractures. Step 3: In the matrix shear modulus calculation model section of Step 1, the effects of matrix deposition inhomogeneity and porosity on the matrix shear modulus are added to establish a calculation model for the shear modulus of SiC / SiC fiber bundle composite matrix components under the combined influence of temperature and matrix damage. Step 4: Determine the number of broken fibers inside the SiC / SiC fiber bundle composite material through testing; Step 5: Determine the matrix density and porosity of the SiC / SiC fiber bundle composite material by testing; Step 6: Substitute the data obtained in Step 4 into the model established in Step 2 to obtain the shear modulus of the fiber component of the SiC / SiC fiber bundle composite material; Step 7: Substitute the data obtained in Step 5 into the model established in Step 3 to obtain the shear modulus of the SiC / SiC fiber bundle composite matrix component; In step 1, the calculation model for the shear modulus of SiC / SiC fiber bundle composite fibers considering the effect of temperature is as follows: The calculation model for the shear modulus of the SiC / SiC fiber bundle composite matrix considering the effect of temperature is as follows: in This represents the high-temperature shear modulus of fiber. This represents the high-temperature shear modulus of the matrix. This indicates the high-temperature elastic modulus of the fibers in fiber bundle composite materials. This indicates the high-temperature elastic modulus of the ceramic matrix fiber bundle composite matrix. This represents the room-temperature elastic modulus of the fibers in ceramic matrix fiber bundle composites. This represents the room-temperature elastic modulus of a ceramic matrix fiber bundle composite matrix. Indicates the ambient temperature of the material. Indicates fiber diameter. Indicates the matrix Poisson's ratio. Indicates the Poisson's ratio of the fiber. This indicates the factor affecting fiber high-temperature fracture. Indicates the factors affecting matrix damage; In step 2, the calculation model for the shear modulus of the SiC / SiC fiber bundle composite material, which is affected by both temperature and the number of internal fiber fractures, is as follows: ； in, Indicates the fiber breakage ratio. Indicates the number of broken fibers. Indicates the total number of fibers inside the material; In step 3, the calculation model for the shear modulus of the SiC / SiC fiber bundle composite matrix component under the combined influence of temperature and matrix damage is as follows: ； ； in, Indicates matrix density. Indicates porosity. Indicates the density influence factor. Indicates matrix density. Indicates the area of ​​the voids. Indicates the total area of ​​the material. This represents the total cross-sectional area of ​​the fiber.

2. The method for calculating the shear modulus of each component of a SiC / SiC fiber bundle composite material according to claim 1, characterized in that: In step 4, the specific method for determining the number of broken fibers inside the SiC / SiC fiber bundle composite material by detection is as follows: S4.1 Use XCT technology to scan and capture images of the internal structure of SiC / SiC fiber bundle composite material after high-temperature oxygen-free treatment, and count the total number of fibers and the number of broken fibers under different slice views. S4.2 Calculate the average number of broken fibers based on the total number of fibers and the number of broken fibers under different slices, and obtain the proportion of the number of broken fibers in the total number of fibers.

3. The method for calculating the shear modulus of each component of a SiC / SiC fiber bundle composite material according to claim 1, characterized in that: In step 5, the specific method for determining the matrix density and porosity of the SiC / SiC fiber bundle composite material by detection is as follows: S5.1 The total volume of the material can be measured non-destructively using the drainage method. The total mass of the material is measured using a high-precision electronic scale, and the matrix density can be obtained by subtracting the fiber portion. S5.2 Use a scanning electron microscope to take cross-sectional images of SiC / SiC fiber bundle composite materials after high-temperature oxygen-free treatment, and count the pore pixel area within the field of view; S5.3 The actual pore area in S5.2 is calculated using the scale used when taking pictures with a scanning electron microscope, and the pore content is obtained.

Images