Method for calculating anisotropic conductivity of carbon fiber composite material based on partial element equivalent circuit method

Abstract

The invention relates to the technical field of numerical modeling, and discloses a method for calculating anisotropic conductivity of a carbon fiber composite material based on a partial element equivalent circuit method, which comprises the following steps of: establishing a resistance matrix, a capacitance matrix and an inductance matrix under a microstructure of the carbon fiber composite material through the partial element equivalent circuit method; setting contact points of fibers by using a concept of fiber ripple degree, and forming grid nodes of PEEC by using the contact points; establishing a PEEC grid and an electric field and magnetic field decoupling method under the microscopic condition of the carbon fiber composite material; establishing a PEEC equation based on the established parameter matrix and the overlap resistance, and adding an excitation source by identifying the position of an electrode; calculating the anisotropic conductivity of the carbon fiber composite material by solving a PEEC equation; according to the method, the problems that finite elements and time domain finite difference grids are not applicable, microstructure solution is easy to diverge and full waves of an electrical network method are not applicable are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of numerical modeling, and more particularly to a method for calculating the anisotropic conductivity of carbon fiber composite materials based on a partial element equivalent circuit method. Background Art

[0002] The development of numerical modeling technology is the result of the cross-integration of mathematics, computer science and application fields. It plays an increasingly important role in scientific research, engineering design and decision support.

[0003] At present, numerical simulation technology is relatively mature, but research on electrical network modeling of carbon fiber composite materials is lacking. The establishment of carbon fiber μm-level scale and plate cm-level scale grids is difficult and time-consuming.

[0004] The existing finite element method and time-domain finite difference method are difficult to quickly and automatically set the overlap position, and the matrix constructed using the electrical network method is difficult to simulate the full-wave process. These defects of existing methods are the main aspects that limit the research on electrical network modeling of carbon fiber composites. Summary of the Invention

[0005] The present invention provides a method for calculating the anisotropic electrical conductivity of carbon fiber composite materials based on the partial element equivalent circuit method, which solves the technical problems in related technologies such as the limitations of traditional finite element and time-domain finite difference methods in mesh division, the easy divergence of microstructure solutions, and the unsuitability of traditional electrical network methods for full-wave modeling, which require manual mesh division.

[0006] The present invention provides a method for calculating the anisotropic conductivity of carbon fiber composite materials based on a partial element equivalent circuit method, comprising:

[0007] Determine the fiber center node coordinate matrix and adjacent index matrix under the initial cross section;

[0008] Obtain fiber contact point increment matrix according to fiber waviness and fiber cell size;

[0009] Based on the above matrix, a partial element equivalent circuit method spatial double grid is formed to establish the fiber lap resistance position matrix and calculate the lap resistance value;

[0010] The impedance element matrix of the fiber network is calculated by Gauss-Legendre quadrature formula, and the resistance matrix, inductance matrix and capacitance matrix are established;

[0011] The current nodes are established based on the spatial scale semi-grid form of the overlap position, thereby decoupling the electric field and the magnetic field;

[0012] Establish the partial element equivalent circuit method equation and add the excitation source by identifying the electrode position;

[0013] Solve the partial element equivalent circuit method equations to obtain the voltage and current results in the time and frequency domains;

[0014] Calculate the anisotropic electrical conductivity of carbon fiber composites;

[0015] Furthermore, the step of determining the fiber center node coordinate matrix at the initial cross section includes:

[0016] Obtain microstructural information of carbon fiber composite materials;

[0017] Determine the coordinates of the fiber center node under the initial cross section;

[0018] The fiber filament center node coordinates are stored as a coordinate matrix.

[0019] Furthermore, the adjacent index matrix is ​​established based on the adjacent relationship of fibers and is used to represent the connection relationship between fibers.

[0020] Furthermore, the fiber contact point increment matrix is ​​calculated based on the fiber waviness and fiber cell size, and is used to determine the contact positions between fibers.

[0021] Furthermore, the step of calculating the impedance element matrix of the fiber network by using the Gauss-Legendre quadrature formula includes:

[0022] Apply the Gauss-Legendre quadrature formula for each pair of adjacent fibers;

[0023] Calculate the impedance value between each element in the fiber network;

[0024] The impedance values ​​are organized into a matrix of impedance elements.

[0025] Furthermore, the steps of establishing the resistance matrix, the inductance matrix and the capacitance matrix include:

[0026] Establish inductance matrix and resistance matrix through current nodes;

[0027] Create a capacitance matrix using potential nodes.

[0028] Furthermore, the step of solving the partial element equivalent circuit method equation includes:

[0029] For frequency domain excitation, use matrix inversion or least squares method to solve;

[0030] For time domain excitation, the θ method is used to solve the partial element equivalent circuit method equations.

[0031] Furthermore, the step of calculating the anisotropic conductivity of the carbon fiber composite material includes:

[0032] Calculate the conductivity based on the voltage and current results in the time and frequency domains;

[0033] By changing the electrode position and excitation direction, the conductivity in three orthogonal directions is calculated separately to form an anisotropic conductivity tensor.

[0034] Furthermore, the anisotropic conductivity tensor includes conductivity components in three orthogonal directions, which is used to characterize the electrical conduction properties of the carbon fiber composite material in three-dimensional space.

[0035] The present invention provides a system for calculating the anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method, which is used to execute the aforementioned method for calculating the anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method, comprising:

[0036] The microstructure modeling module is used to determine the fiber center node coordinate matrix and adjacent index matrix under the initial cross section, and obtain the fiber contact point increment matrix based on the fiber waviness and fiber cell size;

[0037] A grid generation module is used to form a partial element equivalent circuit method spatial double grid based on the above matrix, establish a fiber splice resistance position matrix and calculate the splice resistance value;

[0038] A parameter matrix establishment module is used to calculate the impedance element matrix of the fiber network through the Gauss-Legendre quadrature formula and establish the resistance matrix, inductance matrix and capacitance matrix;

[0039] The electromagnetic field decoupling module is used to establish current nodes in a spatial scale semi-grid form based on the overlap position, thereby decoupling the electric field and the magnetic field;

[0040] The equation solving module is used to establish the partial element equivalent circuit method equation. By identifying the electrode position and adding the excitation source, the partial element equivalent circuit method equation is solved to obtain the voltage and current results in the time and frequency domains.

[0041] The electrical conductivity calculation module is used to calculate the anisotropic electrical conductivity of carbon fiber composite materials.

[0042] The beneficial effects of the present invention are: the fiber overlap position can be quickly determined to form a PEEC grid without manual grid division; the characterization of carbon fiber composite materials accurately includes parameters such as capacitance, resistance, inductance, etc., and the calculation efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart of a method for calculating anisotropic conductivity of carbon fiber composite materials based on a partial element equivalent circuit method of the present invention;

[0044] Figure 2 is a schematic diagram of a fiber cross section of the present invention;

[0045] Figure 3 It is the overlap point increment diagram of the present invention;

[0046] Figure 4 This is a physical model diagram of the resistance, capacitance and inductance network formed based on the overlap point increment of the present invention;

[0047] Figure 5 It is a PEEC network diagram of a resistance, capacitance and inductance network formed based on the incremental overlap points of the present invention;

[0048] Figure 6 This is a PEEC circuit diagram of a resistance, capacitance and inductance network formed based on an incremental overlap point according to the present invention;

[0049] Figure 7 is an xy matrix diagram of the present invention;

[0050] Figure 8 It is the fiber three-dimensional space and PEEC grid point diagram of the present invention;

[0051] Figure 9 This is a three-dimensional internal current diagram of the fiber of the present invention;

[0052] Figure 10 This is a three-dimensional internal potential distribution diagram of the fiber of the present invention;

[0053] Figure 11 The anisotropic current distribution of the present invention Figure 1 ;

[0054] Figure 12 The anisotropic current distribution of the present invention Figure 2 . DETAILED DESCRIPTION

[0055] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that these embodiments are discussed solely to enable those skilled in the art to better understand and implement the subject matter described herein, and that the functions and arrangements of the elements discussed may be varied without departing from the scope of this specification. Various examples may omit, substitute, or add various processes or components as needed. Furthermore, features described in some examples may be combined in other examples.

[0056] Example 1

[0057] This embodiment provides a method for calculating the anisotropic conductivity of carbon fiber composite materials based on a partial element equivalent circuit method, comprising the following steps:

[0058] Step 101: establishing a resistance, capacitance, and inductance matrix under the carbon fiber composite material microstructure, wherein the establishing method includes but is not limited to using a Gauss-Legendre quadrature formula, a geometric mean distance method, and a fitting formula.

[0059] Based on the established PEEC grid, the inductance matrix L and the resistance matrix R are established through the current nodes, and the capacitance matrix P is established through the potential nodes.

[0060] As mentioned above, the internal elements of the inductance matrix L are calculated by the following formula:

[0061]

[0062] and are weights and Gaussian points (where is the number of Gaussian points used), It is The length of the root line, For the The line segment and The mutual inductance between the line segments is When , the element represents the self-inductance of the line, is and The angle formed by the directions of the two lines, is a logarithmic term, is the magnetic permeability of the matrix.

[0063] As mentioned above, the internal elements of the capacitance matrix P are calculated by the following formula:

[0064]

[0065] in, is the first nodes and The mutual capacitance coefficient between nodes is and Respectively Root segment and The length of the root segment, is the substrate dielectric constant, is the number of Gaussian integration points, For the The weight of the Gaussian points, For the The location of the Gaussian point, is a logarithmic term.

[0066] As mentioned above, the internal elements of the resistance matrix R are calculated by the following formula:

[0067]

[0068] in, For the The self-resistance of the root segment, For the The length of the root segment, is the resistivity of carbon fiber, is the radius of the carbon fiber.

[0069] The establishment of PEEC grid and the decoupling method of electric and magnetic fields under the microscopic conditions of carbon fiber composite materials include:

[0070] The establishment of the PEEC grid under the microscopic condition of the carbon fiber composite material includes:

[0071] First, determine the fiber center node coordinate matrix xy under the initial cross section, and establish the adjacent index matrix Neigber based on the adjacent relationship of the fibers. Then, obtain the fiber contact point increment matrix according to the fiber corrugation beta and fiber cell size. , then based on the matrix xy, Neigber, A PEEC spatial double grid is formed, and finally the fiber overlap resistance position matrix Cont is established and the overlap resistance value is calculated.

[0072] The establishment of the fiber center node coordinate matrix xy under the initial cross section includes:

[0073] First, based on the fiber volume ratio , fiber distribution coefficient , determine the fiber spacing . Square arrangement , when arranged in hexagonal .Sure The method is obtained by solving the following formula:

[0074]

[0075] based on Establish the fiber center node coordinate matrix The fiber center node coordinate matrix Methods for establishing include but are not limited to the above-mentioned methods, for example, a cross-sectional microscopic image can be obtained through a microscope and established using an image recognition method.

[0076] The method of establishing a neighboring index matrix Neigber based on the neighboring relationship of fibers includes:

[0077] By traversing the matrix xy and determining whether the Euclidean distance of the coordinates is less than or equal to the cell side length, the adjacent fiber index subscripts of the fibers are obtained. Neigber's claims include but are not limited to non-sparse subscript storage.

[0078] The fiber contact point increment matrix Used to store the overlap position of fibers and adjacent fibers, and the overlap interval of fibers like Figure 2 As shown, it is calculated by the following formula

[0079]

[0080] In the above formula is the fiber corrugation, is the distance increment of the overlap point, b is the fiber arc height. The first overlap point between each adjacent fiber is randomly distributed in (0, ), the distance increment of subsequent overlap points is ;

[0081] when , the overlap point setting is completed;

[0082] in For initial overlap, is the number of overlaps.

[0083] Sort the increments of the joining points for each fiber and insert the initial position 0 and the end length , which constitutes the incremental matrix of fiber contact points , as shown below:

[0084]

[0085] The matrix-based 、 、 Forming a PEEC spatial double grid refers to establishing the three-dimensional spatial node coordinates of the fiber and node association matrix process. The matrix is ​​composed of and Splicing to form, The node association matrix is ​​constructed as follows:

[0086]

[0087] In the above formula is the total number of nodes.

[0088] The fiber bonding resistance position matrix pass Construct an index for storing overlapping points, The necessary and sufficient condition for a lap point in the matrix is ​​that there are adjacent fibers and The values ​​in the matrix are equal. The resistance value is calculated by the following formula:

[0089]

[0090] in, is the fiber lap resistance value, is the resistivity of carbon fiber, Apply pressure to the process, is the fiber radius, is the fiber spacing, is the fiber corrugation, is the elastic modulus of the fiber.

[0091] Step 102: Establish a PEEC equation based on the matrix Cont and the parameter matrices L, R, P and the strapping resistance R. Add an excitation source by identifying the electrode position. For frequency domain excitation, it includes but is not limited to using matrix inverse operations and least squares method to solve. For time domain excitation, it includes but is not limited to using the θ method to solve the PEEC equation. Finally, calculate the conductivity based on the voltage and current results in the time and frequency domains.

[0092] The time domain equation and frequency domain equation are shown as follows:

[0093]

[0094]

[0095] in: is the node association matrix, is the transpose of the node association matrix, is the resistance matrix, is the inductance matrix, is the capacitance matrix, is the inductance admittance matrix, is the imaginary unit, is the angular frequency, is the node voltage vector, is the branch current vector, is the voltage source vector, is the current source vector, is the time derivative of the node voltage, is the time derivative of the branch current.

[0096] described To solve the PEEC equation, the frequency domain equation needs to be rewritten as a general formula:

[0097]

[0098] in: is the system matrix, is the time derivative coefficient matrix, is the state variable vector, is the time derivative of the state variable, is the source term vector.

[0099] The solution is an iterative process:

[0100]

[0101] in: is the time integration parameter, and its value range is [0,1]. is the system matrix, is the time derivative coefficient matrix, is the time step, is the state variable vector at the current moment, is the state variable vector at the next moment, is the source term vector at the current moment, is the source term vector at the next moment.

[0102] Used to store the PEEC solution, by identifying the electrode position and reading the vector The voltage and current of the inner electrode are used to calculate the resistivity and conductivity based on the dimensional parameters of the composite material plate.

[0103] In this embodiment, the transverse resistivity is calculated by taking 9 fibers with a diameter of 7 μm, a plate length of 10 cm, VF=0.43, and a square with equal intervals as an example.

[0104] like Figure 2-12 As shown, the implementation process is as follows:

[0105] Step 100, generate an xy matrix based on the fiber volume fraction such as Figure 7 As shown;

[0106] Step 200: Generate a fiber overlap point increment matrix based on the fiber waviness and the fiber adjacent relationship, and form a three-dimensional space of the fiber, such as Figure 8 As shown;

[0107] Step 300: After adding additional nodes including the bridge resistor additional node, current excitation additional node, and electrode additional node, assemble the PEEC equation and solve it in the time domain. Figure 9 and 10 shown.

[0108] Example 2

[0109] This embodiment provides a method for calculating the anisotropic conductivity of carbon fiber composite materials based on a partial element equivalent circuit method, comprising the following steps:

[0110] Step 2100: Establish stress-damage mapping relationship

[0111] The stress-damage mapping algorithm is used to analyze the mechanical stress field distribution of carbon fiber composite materials and generate damage parameter fields. Specifically, it includes:

[0112] Step 2101: Obtain the mechanical stress field distribution of the carbon fiber composite material ,in is the three-dimensional space coordinate;

[0113] Step 2102: Determine the stress-damage mapping function based on material properties , the function can be expressed as:

[0114]

[0115] in, is the damage threshold stress, is the critical failure stress, and are material-related parameters, obtained through experimental calibration;

[0116] Step 2103: transform the mechanical stress field Substitute into the mapping function , calculate the spatially distributed damage parameter field .

[0117] Step 2200, design a bidirectional coupling equation system

[0118] Construct a set of bidirectional coupling equations for the damage-conductivity coupled multi-physics model and establish the interaction mechanism between the mechanical field and the electrical field. Specifically, it includes:

[0119] Step 2201, establish correction function , which is used to adjust the parameter matrix in the PEEC equation according to the damage parameter, can be expressed as:

[0120]

[0121]

[0122]

[0123] in, 、 、 is the correction factor, 、 、 is the damage sensitivity index, determined according to the material properties;

[0124] Step 2202: Modify the parameter matrix in the PEEC equation based on the correction function:

[0125]

[0126]

[0127]

[0128] in, 、 and are the modified resistance matrix, inductance matrix and capacitance matrix;

[0129] Step 2203: Establish the reverse effect equation of the electric field on the mechanical field, taking into account the stress change caused by the thermoelectric effect:

[0130]

[0131] in, is the additional stress caused by the electric field, is the electric field strength, is the thermoelectric coupling coefficient, which reflects the ability of the material to convert electric field energy into thermal energy and then generate thermal stress.

[0132] Step 2300: Introduce fiber break probability distribution function

[0133] Apply the fiber break probability distribution function to process the fracture behavior of carbon fiber composite materials under stress and generate the fiber break distribution results. Specifically including:

[0134] Step 2301: Establish fiber break probability distribution function , used to describe the stress state Lower space position The fracture probability of the carbon fiber at can be expressed as:

[0135]

[0136] in, is the characteristic stress parameter, is the Weibull modulus, is the effective volume factor;

[0137] Step 2302, combining fiber geometry distribution information, based on the node coordinate matrix and fiber overlap position matrix , calculate the probability of each fiber breaking;

[0138] Step 2303: Use the Monte Carlo method to determine the fiber break location, compare the fiber break probability value with the random number, and generate a fiber break distribution matrix. , whose elements are defined as:

[0139]

[0140] Step 2304: According to the fiber cut distribution matrix , modify the PEEC grid node association matrix , reflecting the changes in grid connectivity caused by fiber breakage:

[0141]

[0142] in, Represents the Hadamard product (element-wise product).

[0143] Step 2400: Develop a hierarchical iterative solution algorithm

[0144] Design and implement a hierarchical iterative solution algorithm to alternately solve the mechanical field and the electrical field and output the field distribution in the equilibrium state. Specifically including:

[0145] Step 2401, initialize the mechanical field distribution and electrical field distribution ;

[0146] Step 2402, establish the iterative update equation:

[0147]

[0148]

[0149]

[0150]

[0151]

[0152] in, is the number of iteration steps; The function represents the additional stress caused by the electric field, which is specifically realized by multiplying the square of the electric field strength by the thermoelectric coupling coefficient, that is:

[0153]

[0154] in is the thermoelectric coupling coefficient, which reflects the ability of the material to convert electric field energy into thermal energy and then generate thermal stress; is the stress-damage mapping function defined in step 2102, used to convert the updated stress field into the corresponding damage parameter field;

[0155] Step 2403: Solve the PEEC equation based on the modified parameter matrix to obtain a new electric field distribution. The PEEC equation can be expressed in the frequency domain as:

[0156]

[0157] in, 、 、 are the admittance matrices corresponding to inductance, capacitance, and resistance, respectively. is the electric potential vector, is the current source vector; these admittance matrices can be calculated from the modified parameter matrix as follows:

[0158]

[0159]

[0160]

[0161] in, is the modified grid node association matrix, is the potential correlation matrix, is the imaginary unit, is the angular frequency; the solution is the electric potential vector After that, the new electric field distribution can be calculated by the following formula:

[0162]

[0163] in, It is based on the node potential vector The space potential scalar field obtained by interpolation is represents the gradient operator;

[0164] Step 2404, calculate the convergence criterion :

[0165]

[0166] in, Represents the Euclidean norm (L2 norm), which is used to measure the amplitude of the field distribution change. For the discretized field distribution, it is calculated as the square root of the sum of the squares of the corresponding physical quantities at each grid node, that is, for the vector , whose L2 norm is defined as The convergence criterion takes into account the relative variation of the mechanical and electrical fields. The iterative process converges when both tend to be stable.

[0167] Step 2405, if (in is the preset convergence threshold), the iteration ends and the mechanical field distribution in the equilibrium state is output and electrical field distribution ; Otherwise, return to step 2402 to continue iteration.

[0168] Step 2500, calculate anisotropic conductivity

[0169] The anisotropic electrical conductivity of carbon fiber composites under damage conditions is calculated based on the equilibrium PEEC solution. Specifically, it includes:

[0170] Step 2501: Under equilibrium conditions, extract the solution of the PEEC equation to obtain the potential distribution. and current distribution ;

[0171] Step 2502: Identify the set of electrode locations where voltage is applied , calculate the voltage difference between the electrodes :

[0172]

[0173] Step 2503, calculate the total current passing through the electrode :

[0174]

[0175] Step 2504, based on the sample size parameter (length , cross-sectional area ), calculate along a specific direction Conductivity :

[0176]

[0177] in, is the sample size in the direction of current flow, is the cross-sectional area perpendicular to the direction of current flow;

[0178] Step 2505, by changing the electrode position and the excitation direction, calculate the three orthogonal directions ( 、 、 ) on the conductivity 、 and , forming the anisotropic conductivity tensor :

[0179]

[0180] Step 2506 can be expanded to a complete anisotropic conductivity tensor for samples with more complex anisotropic properties:

[0181]

[0182] By applying an electric field in different combinations of directions and measuring the response current, the individual components of the anisotropic conductivity tensor are determined.

[0183] It is understandable that the data preprocessing methods known to those skilled in the art include data cleaning, data conversion, and data reduction, among which data conversion includes type conversion and normalization and standardization. Although the dimension and type of the data are ignored in the description of the previous embodiment, data preprocessing is technical knowledge known to those skilled in the art and a prerequisite for data processing. Therefore, the well-known data preprocessing steps are not independently described in the previous content.

[0184] The above describes an embodiment of the present invention, but this embodiment is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Ordinary technicians in this field can also make more forms of equivalent embodiments based on the inspiration of this embodiment, all of which are protected by this embodiment.

Claims

1. A method for calculating the anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method, characterized in that: The following steps are involved: Determine the fiber center node coordinate matrix and adjacent index matrix under the initial cross section; Obtain fiber contact point increment matrix according to fiber waviness and fiber cell size; Based on the above matrix, a partial element equivalent circuit method spatial double grid is formed to establish the fiber lap resistance position matrix and calculate the lap resistance value; The impedance element matrix of the fiber network is calculated by Gauss-Legendre quadrature formula, and the resistance matrix, inductance matrix and capacitance matrix are established; The current nodes are established based on the spatial scale semi-grid form of the overlap position, thereby decoupling the electric field and the magnetic field; Establish the partial element equivalent circuit method equation and add the excitation source by identifying the electrode position; Solve the partial element equivalent circuit method equations to obtain the voltage and current results in the time and frequency domains; Calculate the anisotropic electrical conductivity of carbon fiber composites; Among them, the partial element equivalent circuit method spatial double grid adds additional nodes to the partial element equivalent circuit method equation through fiber overlap points and establishes electric potential nodes, and uses the overlap positions to form a spatial scale half-grid form to establish current nodes to decouple the electric field and magnetic field.

2. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 1, characterized in that: The step of determining the fiber center node coordinate matrix at the initial cross section includes: Obtain microstructural information of carbon fiber composite materials; Determine the coordinates of the fiber center node under the initial cross section; The fiber filament center node coordinates are stored as a coordinate matrix.

3. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 1, characterized in that: The adjacent index matrix is ​​established based on the adjacent relationship of fibers and is used to represent the connection relationship between fibers.

4. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 1, characterized in that: The fiber contact point increment matrix is ​​calculated based on the fiber waviness and fiber cell size, and is used to determine the contact positions between fibers.

5. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 1, characterized in that: The step of calculating the impedance element matrix of the fiber network by using the Gauss-Legendre quadrature formula includes: Apply the Gauss-Legendre quadrature formula for each pair of adjacent fibers; Calculate the impedance value between each element in the fiber network; The impedance values ​​are organized into a matrix of impedance elements.

6. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 1, characterized in that: The steps of establishing the resistance matrix, the inductance matrix and the capacitance matrix include: Establish inductance matrix and resistance matrix through current nodes; Create a capacitance matrix using potential nodes.

7. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 1, characterized in that: The step of solving the partial element equivalent circuit method equation comprises: For frequency domain excitation, use matrix inversion or least squares method to solve; For time domain excitation, the θ method is used to solve the partial element equivalent circuit method equations.

8. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 1, characterized in that: The step of calculating the anisotropic conductivity of the carbon fiber composite material comprises: Calculate the conductivity based on the voltage and current results in the time and frequency domains; By changing the electrode position and excitation direction, the conductivity in three orthogonal directions is calculated separately to form an anisotropic conductivity tensor.

9. The method for calculating anisotropic conductivity of carbon fiber composite materials based on the partial element equivalent circuit method according to claim 8, characterized in that: The anisotropic conductivity tensor includes conductivity components in three orthogonal directions and is used to characterize the electrical conduction properties of the carbon fiber composite material in three-dimensional space.

10. A system for calculating anisotropic conductivity of carbon fiber composite materials based on a partial element equivalent circuit method, for executing a method for calculating anisotropic conductivity of carbon fiber composite materials based on a partial element equivalent circuit method according to any one of claims 1 to 9, characterized in that: include: The microstructure modeling module is used to determine the fiber center node coordinate matrix and adjacent index matrix under the initial cross section, and obtain the fiber contact point increment matrix based on the fiber waviness and fiber cell size; A grid generation module is used to form a partial element equivalent circuit method spatial double grid based on the above matrix, establish a fiber splice resistance position matrix and calculate the splice resistance value; A parameter matrix establishment module is used to calculate the impedance element matrix of the fiber network through the Gauss-Legendre quadrature formula and establish the resistance matrix, inductance matrix and capacitance matrix; The electromagnetic field decoupling module is used to establish current nodes in a spatial scale semi-grid form based on the overlap position, thereby decoupling the electric field and the magnetic field; The equation solving module is used to establish the partial element equivalent circuit method equation. By identifying the electrode position and adding the excitation source, the partial element equivalent circuit method equation is solved to obtain the voltage and current results in the time and frequency domains. The electrical conductivity calculation module is used to calculate the anisotropic electrical conductivity of carbon fiber composite materials.

Images