A modeling method for predicting the electromechanical response of ceramic-based fiber bundle composites

Abstract

The present invention discloses a modeling method for predicting the electromechanical response of a ceramic-based fiber bundle composite material. The method comprises the following steps: obtaining the force, deformation, acoustic emission, and resistance data of a ceramic-based fiber bundle composite material sample during stretching through experiments; testing the ceramic-based fiber bundle composite material sample after partial breaking to obtain basic material performance parameters; calculating the load-crack density correspondence of the ceramic-based fiber bundle composite material; establishing a deformation unit model after cracking of the ceramic-based fiber bundle composite material matrix to obtain interface debonding length, crack opening distance, and fiber and matrix deformation data under arbitrary loads; establishing a damage-considered stress-strain-resistance coupling model for the ceramic-based fiber bundle composite material, and calculating the load, deformation, damage, and resistance relationship of the ceramic-based fiber bundle composite material as the electromechanical response characteristic of the ceramic-based fiber bundle composite material. The present invention can predict the electromechanical response law of ceramic-based fiber bundle composite materials.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material hot end structure health monitoring, and in particular to a method for modeling a prediction model of a mechanoelectric response of a ceramic-based fiber bundle composite material. Background Art

[0002] Ceramic matrix composites (CMCs) have broad application prospects in advanced aero-engine hot-end components, high-speed aircraft thermal protection, and other fields due to their excellent high-temperature mechanical properties and thermal stability. At the same time, CMCs possess certain electrical conductivity, resulting in a corresponding relationship between the resistance change and the degree of damage in CMC components. Using resistance to detect the structural health of CMC components has become an emerging structural health monitoring and non-destructive testing technology. Ceramic matrix fiber bundle composites (CMFBs) are a special form of CMFBs prepared with a single fiber bundle as the reinforcement phase. They can be considered the basic unit in woven and laminated CMFB structures, serving as both a key load-bearing unit and a conductive unit. Therefore, the electromechanical response characteristics of CMFBs determine the overall electromechanical response characteristics of CMFB components. Obtaining the electromechanical response law of CMFBs is also a prerequisite for further realizing multi-scale electromechanical coupling simulation of CMFBs.

[0003] Ceramic-based fiber bundle composites (CMFBs) deform and suffer damage under external loads. Damage forms include matrix cracking, interfacial debonding, fiber pullout, and fiber breakage. These damages further affect the material's deformation behavior and significantly alter its overall electrical resistance, resulting in complex electromechanical responses. Because the specific damage form, damage propagation patterns, component ratios, processing, and the mechanical and electrical parameters of the material's components all significantly influence its electromechanical response, the cost of simply permuting and combining experimental methods to determine the electromechanical response of CMFBs under all conditions is unacceptable. Establishing a predictive model for the electromechanical response of CMFBs that takes into account damage, component parameters, and other factors with clear physical meaning would be cost-effective and rapid. Material test results under specific parameters could be used to predict the electromechanical response of the material under other conditions. However, no existing models or methods for predicting the electromechanical response of CMFBs exist.

[0004] Therefore, it is urgent to establish a mechanoelectric response model that can accurately describe the damage-resistance correspondence of ceramic-based fiber bundle composites, has a clear physical meaning, and can be used for damage detection, so as to predict the mechanoelectric response law of ceramic-based fiber bundle composites. Summary of the Invention

[0005] The purpose of the present invention is to disclose a modeling method for predicting the electromechanical response of a ceramic-based fiber bundle composite material, which can predict the electromechanical response law of the ceramic-based fiber bundle composite material.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A method for modeling a mechanoelectric response prediction model of a ceramic-based fiber bundle composite material, the method comprising the following steps:

[0008] S1, obtaining the force, deformation, acoustic emission, and resistance data of the ceramic-based fiber bundle composite material sample during the stretching process through the test, and saving the ceramic-based fiber bundle composite material sample after being broken;

[0009] S2, taking some broken ceramic-based fiber bundle composite samples and testing them to obtain the basic material performance parameters, including: elastic modulus of each component in the sample, interface shear stress parameters, and volume fraction and cross-sectional area of ​​each component in the sample;

[0010] S3, calculating the matrix crack density after the sample is broken as the maximum matrix crack density during the material damage process, and calculating the load-crack density correspondence of the ceramic-based fiber bundle composite material based on the acoustic emission data recorded in step S1;

[0011] S4, establish a deformation unit model of the ceramic fiber bundle composite matrix after cracking, and obtain the interface debonding length, crack opening distance and fiber and matrix deformation data under arbitrary loads through an iterative calculation method;

[0012] S5. Establish a stress-strain-resistance coupling model of ceramic-based fiber bundle composite materials considering damage, substitute the basic material performance parameters obtained in step S2, the load-crack density correspondence obtained in step S3, and the interface debonding length, crack opening distance and fiber and matrix deformation data under arbitrary load obtained in step S4, as well as the component resistivity parameters, adjust the interface retention rate for fitting, and calculate the load, deformation, damage and resistance relationship of the ceramic-based fiber bundle composite material as the electromechanical response characteristics of the ceramic-based fiber bundle composite material.

[0013] Furthermore, step S2 further includes:

[0014] S21, taking some broken ceramic-based fiber bundle composite samples, polishing them to prepare metallographic samples, and using nanoindentation technology to measure the elastic modulus, hardness, and interfacial shear stress of the fiber, interface, and matrix components in the samples;

[0015] S22, use X-ray computed tomography technology to scan some of the ceramic-based fiber bundle composite materials after they are pulled apart, take the images of the cross sections at different positions in the results, segment them, remove the pores, and measure and average the areas of each component to obtain the material cross-sectional area and component ratio parameters.

[0016] Furthermore, step S3 further includes:

[0017] S31, take the remaining longest possible specimen of the ceramic-based fiber bundle composite material after breaking, adhere reinforcement sheets to both ends of the specimen, and reload it to a 50% fracture stress level. Count the number of cracks under an optical microscope or an electron microscope as the maximum number of matrix cracks in the material;

[0018] S32, averaging the maximum number of matrix cracks of the selected sample by length to obtain an average matrix crack density, accumulating the measured acoustic emission event energy and normalizing it by the maximum value, and then multiplying it by the maximum matrix crack density to obtain the matrix crack density of the material at different times;

[0019] S33, corresponding matrix crack density and force based on the test time, to obtain the load-crack density correspondence of the ceramic matrix fiber bundle composite material specimen;

[0020] S34, based on the continuous curve of the total number of matrix cracks changing with matrix stress, the matrix defects are graded to obtain the matrix stress and the number of new matrix cracks corresponding to each level of defects. The matrix strength distribution is obtained by combining the random numbers generated by the Monte Carlo method with the comparison results of the probability of existence of each defect. The matrix strength distribution is compared with the matrix stress distribution to judge the matrix cracking situation, and the load-crack density correspondence of the ceramic-based fiber bundle composite material under other component parameters and volume fractions is obtained.

[0021] Furthermore, step S4 further includes:

[0022] The load force F is gradually increased from 0, and the slip band length L is calculated in the nth load step n slip , and then calculate the fiber deformation D in the slip band area n f-slip , matrix deformation in the slip band region D n m-sli ;

[0023] A small amount of interface-matrix slip has little effect on deformation. Therefore, in the mechanical model, it is assumed that there is no slip between the matrix and the interface. The displacement D of the combined part of the matrix and the interface is n mix-slip =D n m-slip ;

[0024] The fiber deformation in the slip band region at the nth load step is subtracted from the matrix deformation to obtain the fiber pulled out length L at this load step. n f-pullou , the calculation formula is:

[0025] L n f-pullou =D n f-slip -D n mix-slip

[0026] The crack opening distance under the nth load step is calculated by adding the newly stretched length of the fiber already in the crack calculated in the n-1 step to the fiber pull-out length under the current load step:

[0027] L n crack / 2=L n-1 crack ·ε n crack +L n f-pullout

[0028] By repeating the above process, the crack opening distance and the matrix and fiber deformation in the slip band under any load can be calculated.

[0029] Furthermore, the specific slip band length, fiber and matrix deformation are calculated by the following method. First, the stress distribution of the fiber and matrix-interface combination is calculated when there is only one positive slip zone and bonding zone:

[0030]

[0031] Where α is the coefficient of thermal expansion, E is the elastic modulus of the material; subscript f represents the fiber, subscript m represents the matrix, subscript mix represents the combination of the matrix and the interface, and subscript c represents the composite material as a whole; ΔT is the difference between the material preparation temperature and the test temperature, the superscript n represents the parameter at the nth load step (that is, the superscript n represents the value of the nth step in the iterative calculation, and the value without the superscript n is the original meaning), σ f0 represents the stress in the fiber bonding area, σ mix0 represents the stress in the bonding area between the matrix and the interface, and σ represents the overall average stress calculated at the nth load step when the fiber bundle composite material is intact;

[0032] The overall elastic modulus E of the composite material is calculated by the law of mixtures c and its thermal expansion coefficient α c , elastic modulus E at the combination of matrix and interface mix and its thermal expansion coefficient α mix :

[0033]

[0034]

[0035] Where v represents the volume fraction of the component, and the subscript i indicates that the parameter is an interface parameter;

[0036] Calculate the slip band length L n slip :

[0037]

[0038] Where τ is the interface shear stress, r f is the fiber radius;

[0039] The fiber slip zone deformation D is calculated n f-slip Deformation D in the matrix slip zone n mix-slip :

[0040]

[0041]

[0042] Calculate the matrix crack opening distance L under any load n crack :

[0043]

[0044] Furthermore, step S5 further includes:

[0045] Calculate the total deformation ΔL when there is no damage under the current load init , L is the length of the material test section, the formula is as follows:

[0046]

[0047] Assuming that the cracks are evenly distributed, except for the first and last two outer units that have only one slip band, the remaining inner units all have two slip bands. The strain response ε is:

[0048]

[0049] where N c is the number of cracks;

[0050] The part between cracks is considered as a parallel circuit consisting of fiber, interface and matrix, and additional resistance is introduced between the components to simulate the increase of contact resistance;

[0051] The resistance R of the inner unitin Expressed as:

[0052]

[0053] The subscripts f, i, and m of the resistor R represent the fiber, interface, and matrix, respectively. r Represents the contact resistance between the fiber and the interface due to debonding; R f 、R i and R m represent the fiber, interface, and matrix resistances, respectively;

[0054] External unit body resistance R out Expressed as:

[0055]

[0056] Inner unit length L in and the outer unit length L out Respectively expressed as:

[0057]

[0058] The calculation formula for the inner and outer unit body resistance is:

[0059]

[0060] where ρ f , ρ i and ρ m represent the resistivity of fiber, interface and matrix respectively, S is the cross-sectional area of ​​fiber bundle composite material;

[0061] The crack is equivalent to the crack resistivity ρ crack :

[0062]

[0063] Among them, R f-crack is the fiber resistance at the crack, R i-crack is the interfacial resistance at the crack, v i-cra is the volume fraction of the interface that remains electrically conductive at the crack, which can be obtained by simplification:

[0064]

[0065] The specific value of the equivalent crack resistivity is calibrated according to a specific ceramic-based fiber bundle composite material test result obtained in step S1;

[0066] Crack resistance R crack Expressed as:

[0067]

[0068] The total resistance R of the material changes with increasing load as follows:

[0069]

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] First, the modeling method of the electromechanical response prediction model of the ceramic-based fiber bundle composite material of the present invention takes into account the influence of damage factors such as matrix cracks, interface debonding, crack opening, and interface residue, and establishes a prediction model corresponding to load-deformation-damage-resistance. It has a clear physical meaning, includes the main damage modes of the material, is rich in connotation, and is both simple and efficient.

[0072] Second, the modeling method of the electromechanical response prediction model of the ceramic-based fiber bundle composite material of the present invention can predict the electromechanical response characteristics of ceramic-based fiber bundle composite materials with different material systems, component mechanical properties, and component proportions. When the material system remains unchanged, it is only necessary to test the ceramic-based fiber bundle composite material with the mechanical properties and component proportion of one component, which significantly reduces the experimental workload and reduces costs.

[0073] Third, the modeling method of the electromechanical response prediction model of the ceramic-based fiber bundle composite material of the present invention can quickly and accurately predict the electromechanical response characteristic curve of the material, providing a feasible method for realizing multi-scale electromechanical coupling simulation of ceramic-based composite materials and using resistance to monitor the health of the hot end structure of aerospace ceramic-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a schematic diagram of the deformation calculation process of the ceramic-based fiber bundle composite unit.

[0075] Figure 2 It is a schematic diagram of the resistance model of ceramic-based fiber bundle composite materials.

[0076] Figure 3 Comparison of prediction results of the electromechanical properties of ceramic-based fiber bundle composite materials using the electromechanical response prediction model established by the present invention;

[0077] Figure 4 This is a flow chart of the modeling method for predicting the electromechanical response of the ceramic-based fiber bundle composite material of the present invention. DETAILED DESCRIPTION

[0078] The embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0079] See also Figure 4 The present invention discloses a method for modeling a mechanoelectric response prediction model of a ceramic-based fiber bundle composite material, the method comprising the following steps:

[0080] S1, obtaining the force, deformation, acoustic emission, and resistance data of the ceramic-based fiber bundle composite material sample during the stretching process through the test, and saving the ceramic-based fiber bundle composite material sample after being broken;

[0081] S2, taking some broken ceramic-based fiber bundle composite samples and testing them to obtain the basic material performance parameters, including: elastic modulus of each component in the sample, interface shear stress parameters, and volume fraction and cross-sectional area of ​​each component in the sample;

[0082] S3, calculating the matrix crack density after the sample is broken as the maximum matrix crack density during the material damage process, and calculating the load-crack density correspondence of the ceramic-based fiber bundle composite material based on the acoustic emission data recorded in step S1;

[0083] S4, establish a deformation unit model of the ceramic fiber bundle composite matrix after cracking, and obtain the interface debonding length, crack opening distance and fiber and matrix deformation data under arbitrary loads through an iterative calculation method;

[0084] S5. Establish a stress-strain-resistance coupling model of ceramic-based fiber bundle composite materials considering damage, substitute the basic material performance parameters obtained in step S2, the load-crack density correspondence obtained in step S3, and the interface debonding length, crack opening distance and fiber and matrix deformation data under arbitrary load obtained in step S4, as well as the component resistivity parameters, adjust the interface retention rate for fitting, and calculate the load, deformation, damage and resistance relationship of the ceramic-based fiber bundle composite material as the electromechanical response characteristics of the ceramic-based fiber bundle composite material.

[0085] The following is a prediction model of the electromechanical response of a ceramic-based fiber bundle composite material prepared by a CVI process silicon carbide matrix reinforced with third-generation silicon carbide fiber, using the method of the present invention. The modeling process includes the following steps:

[0086] Step 1: Obtain force, deformation, acoustic emission, and resistance data of the ceramic-based fiber bundle composite material sample during the tensile process through a quasi-static tensile test, and save the ceramic-based fiber bundle composite material sample after breaking.

[0087] Step 2: Take a partially broken ceramic fiber bundle composite sample, polish it to prepare a metallographic sample, and use nanoindentation technology to measure the elastic modulus, hardness, and interfacial shear stress of the fiber, interface, and matrix components in the sample. Use X-ray computed tomography technology to scan the partially broken ceramic fiber bundle composite sample, take the image of the cross section at different locations in the result, segment it, remove the pores, and measure and average the area of ​​each component to obtain the material cross-sectional area and component ratio parameters;

[0088] Step 3: Take the remaining, as long as possible, broken ceramic-based fiber bundle composite specimen, attach reinforcement sheets to both ends, and reload to 50% of the breaking force. Count the number of cracks under an optical microscope or electron microscope as the maximum number of matrix cracks in the material. Averaging the lengths yields the average matrix crack density, which is used to calculate the number of matrix cracks in specimens of any length. Accumulate the measured acoustic emission event energy, normalize it by the maximum value, and multiply it by the maximum matrix crack density to obtain the matrix crack density of the material at different times. Then, based on the test time, correlate the matrix crack density with the force to obtain the load-crack density relationship for the ceramic-based fiber bundle composite material. Based on the continuous curve showing the total number of matrix cracks changing with matrix stress, matrix defects are graded to obtain the matrix stress and number of new cracks corresponding to each defect level. The matrix strength distribution is obtained by comparing the random numbers generated by the Monte Carlo method with the probability of each defect. The matrix strength distribution is then compared with the matrix stress distribution to determine the matrix cracking situation and obtain the load-crack density correspondence under other component parameters and volume fractions.

[0089] Step 4: Establish a deformation unit model of the ceramic-based fiber bundle composite matrix after cracking, and obtain the interface debonding length, crack opening distance, and fiber and matrix deformation data under arbitrary loads through an iterative calculation method.

[0090] The deformation unit model and calculation process of the ceramic-based fiber bundle composite material matrix after cracking are as follows: Figure 2 As shown in Figure 1, this element represents half of the region between two adjacent cracks after a small composite material crack has occurred. Due to symmetry, the central symmetry plane can be considered a fixed constraint. The load F applied to the material during tension is entirely borne by the fibers at the crack and gradually transferred to the matrix through interfacial slip friction. When the composite material is intact, the cross-sectional area is S, and the average stress magnitude σ = F / S.

[0091] The increase in the crack opening displacement (COD) is caused by the non-uniform deformation of the fibers and matrix at the crack, which includes the fibers in the slip band being pulled out and the fibers in the crack being stretched again after being pulled out. To simulate this process, the load F is gradually increased from 0, and the slip band length L is calculated in the nth load step. n slip , and then calculate the fiber deformation D in the slip band area n f-slip , matrix deformation in the slip band region D n m-sli .

[0092] The fiber deformation in the slip band region at the nth load step is subtracted from the matrix deformation to obtain the fiber pulled out length L at this load step.n f-pullout , the calculation formula is:

[0093] L n f-pullout =D n f-sl -D n mix-slip

[0094] The final crack opening distance under the nth load step is calculated by the newly stretched length of the fiber already in the crack under the current load calculated in the n-1 step, and the crack opening distance under the nth load step is calculated as:

[0095]

[0096] The crack opening distance and the matrix and fiber deformation in the slip band under arbitrary loads are obtained by cyclic calculation.

[0097] The process for calculating the slip band length, fiber deformation in the slip band region, and matrix deformation in the slip band region includes the following steps:

[0098] The stress distribution of the fiber and matrix-interface combination when there is only one positive slip zone and bonding zone is calculated as follows:

[0099]

[0100] Where α is the coefficient of thermal expansion, E is the elastic modulus of the material. Subscript f represents the fiber, subscript m represents the matrix, subscript mix represents the combination of the matrix and the interface, and subscript c represents the composite material as a whole. ΔT is the difference between the material preparation temperature and the test temperature, superscript n represents the parameter at the nth load step, and σ f0 represents the stress in the fiber bonding area, σ mix0 Represents the stress in the bonding area between the substrate and the interface.

[0101] The overall elastic modulus of the composite material E c and its thermal expansion coefficient α c , elastic modulus E at the combination of matrix and interface mix and its thermal expansion coefficient α mi It can be calculated by the law of mixing, the formula is as follows:

[0102]

[0103]

[0104] Where v represents the volume fraction of the component, and the subscript i indicates that the parameter is an interface parameter.

[0105] The slip band length is calculated by the following formula:

[0106]

[0107] Where τ is the interface shear stress, r f is the fiber radius.

[0108] Fiber slip zone deformation D n f-sli Deformation D in the slip zone of the matrix n mix-slip can be calculated by the following formula:

[0109]

[0110]

[0111] Based on the calculation results of the above formula, the calculation formula for the matrix crack opening distance under any load is:

[0112]

[0113] Step 5: Establish a stress-strain-resistance coupling model of the ceramic-based fiber bundle composite material considering damage, and input the basic material performance parameters obtained in step 2, the load-crack density correspondence obtained in step 3, the crack opening distance and other parameters under arbitrary load obtained in step 4, and the component resistivity parameters. Adjust the interface retention rate for fitting, and calculate the load, deformation, damage and resistance relationship of the ceramic-based fiber bundle composite material, which is the electromechanical response characteristic.

[0114] The specific values ​​of the basic parameters of the material obtained in step 2 in this embodiment are shown in Table 1:

[0115] Table 1 Basic parameters and component proportions of ceramic-based fiber bundle composites

[0116]

[0117] Table 2 Other parameters used in the model

[0118]

[0119] First calculate the total deformation ΔL under the current load without damage init , L is the length of the material test section, the formula is as follows:

[0120]

[0121] Assuming that the cracks are evenly distributed, except for the first and last outer units, which have only one slip band, the remaining inner units all have two slip bands. The strain response can be calculated as follows:

[0122]

[0123] where N c is the number of cracks.

[0124] The model used to further calculate the material resistance response is as follows Figure 3 As shown in Figure 2, the area between cracks is considered as a parallel circuit consisting of the fiber, interface, and matrix. Due to poor electrical contact caused by interfacial slip or the fiber Poisson effect, additional resistance is introduced between the components to simulate the increase in contact resistance.

[0125] The resistance R of the inner unit in It can be calculated by the following formula:

[0126]

[0127] The subscripts f, i, m, and c of the resistance R represent the fiber, interface, matrix, and composite material as a whole, respectively. r It represents the contact resistance between the fiber and the interface due to debonding.

[0128] External unit body resistance R out It can be expressed as:

[0129]

[0130] Inner unit length L in , outer unit length L out It can be calculated based on the result of step 4, using the following formula:

[0131]

[0132] Based on the above formula, the calculation formula for the inner and outer unit body resistance is:

[0133]

[0134] The subscripts f, i, and m of the resistivity ρ represent the fiber, interface, and matrix, respectively. The crack is equivalent to the crack resistivity ρ crack , the calculation method is as follows:

[0135]

[0136] Among them, R f-cra is the fiber resistance at the crack, R i-cra is the interfacial resistance at the crack, v i-cra is the volume fraction of the interface that remains electrically conductive at the crack, which can be obtained by simplification:

[0137]

[0138] At this time, the resistance at the crack is R crackIt can be expressed as:

[0139]

[0140] Based on the above calculation results, the change of the total resistance R of the material with the increase of load can be calculated by the following formula:

[0141]

[0142] The interface retention rate is defined as: v i-crack / v i In this example, 0.6% is used, which means that 0.6% of the interface is not disconnected at the crack and can still conduct electricity. At this time, the equivalent crack resistivity is 4.3Ω·mm.

[0143] Finally, the model was used to predict the test results. Figure 3 shown.

[0144] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiment of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal translation scripting language JavaScript, etc.

[0145] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0146] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0147] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions for executing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0148] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0149] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for predicting the electromechanical response of a ceramic-based fiber bundle composite material, characterized in that: The electromechanical response prediction model modeling method comprises the following steps: S1, obtaining the force, deformation, acoustic emission, and resistance data of the ceramic-based fiber bundle composite material sample during the stretching process through the test, and saving the ceramic-based fiber bundle composite material sample after being broken; S2, taking some broken ceramic-based fiber bundle composite samples and testing them to obtain the basic material performance parameters, including: elastic modulus of each component in the sample, interface shear stress parameters, and volume fraction and cross-sectional area of ​​each component in the sample; S3, calculating the matrix crack density after the sample is broken as the maximum matrix crack density during the material damage process, and calculating the load-crack density correspondence of the ceramic-based fiber bundle composite material based on the acoustic emission data recorded in step S1; S4, establish a deformation unit model of the ceramic fiber bundle composite matrix after cracking, and obtain the interface debonding length, crack opening distance and fiber and matrix deformation data under arbitrary loads through an iterative calculation method; S5. Establish a stress-strain-resistance coupling model of ceramic-based fiber bundle composite materials considering damage, substitute the basic material performance parameters obtained in step S2, the load-crack density correspondence obtained in step S3, and the interface debonding length, crack opening distance and fiber and matrix deformation data under arbitrary load obtained in step S4, as well as the component resistivity parameters, adjust the interface retention rate for fitting, and calculate the load, deformation, damage and resistance relationship of the ceramic-based fiber bundle composite material as the electromechanical response characteristics of the ceramic-based fiber bundle composite material.

2. The method for predicting the electromechanical response of a ceramic-based fiber bundle composite material according to claim 1, characterized in that: Step S2 further comprises: S21, taking some broken ceramic-based fiber bundle composite samples, polishing them to prepare metallographic samples, and using nanoindentation technology to measure the elastic modulus, hardness, and interfacial shear stress of the fiber, interface, and matrix components in the samples; S22, use X-ray computed tomography technology to scan some of the ceramic-based fiber bundle composite materials after they are pulled apart, take the images of the cross sections at different positions in the results, segment them, remove the pores, and measure and average the areas of each component to obtain the material cross-sectional area and component ratio parameters.

3. The method for predicting the electromechanical response of a ceramic-based fiber bundle composite material according to claim 1, characterized in that: Step S3 further comprises: S31, take the remaining longest possible specimen of the ceramic-based fiber bundle composite material after breaking, adhere reinforcement sheets to both ends of the specimen, and reload it to a 50% fracture stress level. Count the number of cracks under an optical microscope or an electron microscope as the maximum number of matrix cracks in the material; S32, averaging the maximum number of matrix cracks of the selected sample by length to obtain an average matrix crack density, accumulating the measured acoustic emission event energy and normalizing it by the maximum value, and then multiplying it by the maximum matrix crack density to obtain the matrix crack density of the material at different times; S33, based on the test time, the matrix crack density and force are matched to obtain the load-crack density correspondence of the ceramic-based fiber bundle composite material specimen; S34, based on the continuous curve of the total number of matrix cracks changing with matrix stress, the matrix defects are graded to obtain the matrix stress and the number of new matrix cracks corresponding to each level of defects. The matrix strength distribution is obtained by combining the random numbers generated by the Monte Carlo method with the comparison results of the probability of existence of each defect. The matrix strength distribution is compared with the matrix stress distribution to judge the matrix cracking situation, and the load-crack density correspondence of the ceramic-based fiber bundle composite material under other component parameters and volume fractions is obtained.

4. The method for predicting the electromechanical response of a ceramic-based fiber bundle composite material according to claim 1, wherein: Step S4 further comprises: The load force F is gradually increased from 0, and the slip band length L is calculated in the nth load step n slip , and then calculate the fiber deformation D in the slip band area n f-slip , matrix deformation in the slip band region D m-slip ; In the mechanical model, it is assumed that there is no slip between the matrix and the interface, so the displacement D of the matrix and interface combination is n mix-slip =D n m-slip ; The fiber deformation in the slip band region at the nth load step is subtracted from the matrix deformation to obtain the fiber pulled out length L at this load step. n f-pullout , the calculation formula is: L n f-pullout =D n f-sli -D n mix-slip The crack opening distance under the nth load step is calculated by adding the newly stretched length of the fiber already in the crack calculated in the n-1 step to the fiber pull-out length under the current load step: The crack opening distance and the matrix and fiber deformation in the slip band under arbitrary loads are obtained by cyclic calculation.

5. The method for predicting the electromechanical response of a ceramic-based fiber bundle composite material according to claim 4, characterized in that: The process for calculating the slip band length, fiber deformation in the slip band region, and matrix deformation in the slip band region includes the following steps: Compute the stress distribution in the combined fiber and matrix-interface region when there is only one positive slip and bonding region: Where α is the coefficient of thermal expansion, E is the elastic modulus of the material; subscript f represents the fiber, subscript m represents the matrix, subscript mix represents the combination of the matrix and the interface, and subscript c represents the composite material as a whole; ΔT is the difference between the material preparation temperature and the test temperature, superscript n represents the parameter at the nth load step, and σ f0 represents the stress in the fiber bonding area, σ mix0 Represents the stress in the bonding area between the matrix and the interface, σ represents the overall average stress of the composite material calculated at the nth load step when the fiber bundle composite material is intact, σ = F / S, F is the load, S is the cross-sectional area; The overall elastic modulus E of the composite material is calculated by the law of mixtures c and its thermal expansion coefficient α c , elastic modulus E at the combination of matrix and interface mix and its thermal expansion coefficient α mix : Where v represents the volume fraction of the component, and the subscript i indicates that the parameter is an interface parameter; Calculate the slip band length L n slip : Where τ is the interface shear stress, r f is the fiber radius; The fiber slip zone deformation D is calculated n f-sli Deformation D in the matrix slip zone n mix-slip : Calculate the matrix crack opening distance L under any load n crack :

6. The method for predicting the electromechanical response of a ceramic-based fiber bundle composite material according to claim 1, characterized in that: Step S5 further comprises: Calculate the total deformation △L when there is no damage under the current load init , L is the length of the material test section, the formula is as follows: Assuming that the cracks are evenly distributed, except for the first and last two outer units that have only one slip band, the remaining inner units all have two slip bands. The strain response ε is: where N c is the number of cracks; The part between cracks is considered as a parallel circuit consisting of fiber, interface and matrix, and additional resistance is introduced between the components to simulate the increase of contact resistance; The resistance R of the inner unit in Expressed as: The subscripts f, i, and m of the resistor R represent the fiber, interface, and matrix, respectively. r Represents the contact resistance between the fiber and the interface due to debonding; R f 、R i and R m represent the fiber, interface, and matrix resistances, respectively; External unit body resistance R out Expressed as: Inner unit length L in and the outer unit length L out Respectively expressed as: The calculation formula for the inner and outer unit body resistance is: where ρ f , ρ i and ρ m represent the resistivity of fiber, interface and matrix respectively, S is the measured cross-sectional area of ​​fiber bundle composite material; The crack is equivalent to the crack resistivity ρ crack : Among them, R f-cra is the fiber resistance at the crack, R i-cra is the interfacial resistance at the crack, v i-cra is the volume fraction of the interface that remains electrically conductive at the crack, which can be obtained by simplification: Crack resistance R crack Expressed as: The total resistance R of the material changes with increasing load as follows:

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