Modeling method for randomly-arranged continuous carbon fiber reinforced ceramic matrix composite material

Abstract

The invention belongs to the technical field of discrete element modeling and numerical simulation, and provides a modeling method of a random arrangement continuous carbon fiber reinforced ceramic matrix composite material. Comprising the following steps: (1) specifying a modeling area, setting an allowable volume fraction and a relative error of carbon fibers in a model, and obtaining the radius and the number of carbon fiber models; (2) randomly generating non-coincident carbon fiber end surface center coordinates on a certain boundary surface of the modeling area; (3) generating a plurality of bonded carbon fiber cylindrical particles along the axial direction of the end face circle of the carbon fiber; (4) filling ceramic-based particles; (5) endowing carbon fiber and ceramic matrix model parameters; (6) generating a continuous carbon fiber reinforced ceramic-based material model with specified fractions in random arrangement; compared with a sample generated by using an electron micrograph, the method has the advantages that the modeling speed is higher, and the carbon fiber ceramic-based models with different arrangements inside can be quickly generated. The method has a certain significance for researching the influence of internal carbon fiber arrangement on the mechanical property of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of discrete element modeling and numerical simulation, and specifically relates to a modeling method for a randomly arranged continuous carbon fiber reinforced ceramic matrix composite material. Background Art

[0002] Fiber-reinforced silicon carbide composite materials have a series of advantages such as high strength, high modulus, high temperature resistance, oxidation resistance, corrosion resistance, radiation resistance and creep resistance. As a high-temperature resistant structure, it has a very broad application prospect in the fields of aerospace, nuclear energy, etc. In addition, the components of silicon carbide fiber-reinforced composite materials are adjustable, and it is a high-temperature resistant structural absorbing material with strong designability and excellent performance. Therefore, fiber-reinforced silicon carbide composite materials have been one of the hot topics of research at home and abroad in recent years.

[0003] Ceramic matrix composites are generally prepared by near-net-shape forming technology, but secondary processing is still required to meet the dimensional accuracy and geometric tolerance of the final assembly. Due to the characteristics of anisotropy, high hardness, and high brittleness of ceramic matrix composites, the material removal mechanism during processing is different from that of previous homogeneous materials, and there are certain differences in the surface integrity and fatigue performance between the two. Many scholars at home and abroad have conducted a lot of research on the processing mechanism, damage detection and characterization, surface integrity, and processing technology of ceramic matrix composites, and combined with special energy field processing technology, introduced non-traditional processing technologies such as ultrasonic vibration, laser, water jet, and electric spark to improve processing efficiency and processing quality. However, there are still problems such as severe tool wear, low surface quality and processing efficiency, and difficult to control processing damage.

[0004] The random arrangement of continuous carbon fiber reinforced ceramic matrix materials can be quickly generated by specifying the volume fraction, which is of certain significance for studying the influence of the internal arrangement of carbon fiber on the mechanical properties of the material. Summary of the invention

[0005] Purpose of the invention: The present invention provides a modeling method for randomly arranged continuous carbon fiber reinforced ceramic matrix composites, which can quickly generate a carbon fiber ceramic matrix model with a specified volume fraction and different internal arrangements through a uniform distribution algorithm, which is of certain significance for the study of continuous carbon fiber reinforced ceramic matrix materials with different carbon fiber distributions.

[0006] Technical solution: The present invention comprises the following steps:

[0007] (1) In the PFC3D software, select the required discrete element modeling area size, set the volume fraction and relative error conditions of the carbon fiber in the continuous carbon fiber reinforced ceramic matrix composite model, specify the range of the carbon fiber model end face circle radius generation, and calculate the number and radius of the carbon fiber model required to meet the specified volume fraction and relative error;

[0008] (2) Using the uniform distribution function in the Fish function library, the coordinates of the center of the carbon fiber end face circle are randomly generated with a specified boundary surface in the modeling area as the end face, and the area of ​​the carbon fiber model end face circle is obtained by combining the obtained carbon fiber model radius, and the edge of the area of ​​each carbon fiber end face circle is at least one ceramic-based particle diameter away;

[0009] (3) generating a plurality of carbon fiber cylindrical particles along the axial direction of the carbon fiber end face, and setting a linear parallel bond contact model (Linear Parallel Bond Model) between the contacting carbon fiber cylindrical particles, so as to bond the plurality of carbon fiber cylindrical particles to form a continuous carbon fiber discrete element model;

[0010] (4) Using the range fish function to generate densely packed ceramic-based spherical particles within the selected modeling area and outside the generated carbon fiber discrete element model area;

[0011] (5) Setting up the linear parallel bond contact model of ceramic-based spherical particles-spherical particles and ceramic-based spherical particles-carbon fiber cylindrical particles, and assigning the corresponding particle microscopic contact parameters;

[0012] (6) Finally, a discrete element model of randomly arranged continuous carbon fiber reinforced ceramic matrix composites that meets the required volume fraction and relative error conditions is generated.

[0013] The beneficial effects of the present invention are as follows: the present invention provides a modeling method for a randomly arranged continuous carbon fiber reinforced ceramic matrix composite material, which quickly generates a continuous carbon fiber reinforced ceramic matrix discrete element model with an error not exceeding the specified error value by specifying the volume fraction. For the same volume fraction, the influence of different carbon fiber arrangements on the mechanical properties of the continuous carbon fiber reinforced ceramic matrix material has a certain significance.

[0014] Further, in step (1), the volume fraction and relative error conditions of the carbon fiber in the continuous carbon fiber reinforced ceramic matrix composite model are set, and the uniform distribution function in the fish function library is called in the PFC3D software so that the end face circle radius of the carbon fiber model Take the value within a reasonable range, the formula is:

[0015]

[0016] in, The minimum value generated for the end radius of the carbon fiber model. The maximum value of the radius of the end face of the carbon fiber model is generated. It is the uniform distribution function of the fish function library in the PFC3D software. This function randomly takes values ​​in the range of 0.0-1.0.

[0017] Combined with the loop instruction, the formula is used to calculate the appropriate carbon fiber model end face radius and the appropriate number of carbon fiber models, so that the generated randomly arranged continuous carbon fiber reinforced ceramic matrix material reaches the specified volume fraction and is within the specified error range. The formula is:

[0018]

[0019] in,

[0020] in, is the number of carbon fiber models, for Rounded values, is the length of the modeling area in the x-coordinate direction, is the length of the modeling area in the y-coordinate direction, is the length of the modeling area in the z-coordinate direction, is the specified volume fraction, is the allowable volume fraction error (when When the volume fraction of carbon fiber in the material model and the relative error conditions are met, the end face radius of the carbon fiber model can be found. is the end face radius of the carbon fiber model, is the axial length of the carbon fiber model.

[0021] The above further beneficial effect is that by specifying the model of different carbon fiber distributions generated by the volume fraction and controlling the volume fraction error range, a more optimal fiber arrangement can be found to improve the mechanical properties and stability of the material.

[0022] Further: In the step (2), the uniform distribution function in the Fish function library of the PFC software is used to randomly generate the coordinates of the center of the end face circle of the carbon fiber model within a specified boundary surface of the required modeling area. The distance between the coordinates of the center of the end face circle of the carbon fiber model and the boundary of the modeling area leaves at least the sum of the radius length of the end face circle of the carbon fiber model and the diameter length of the ceramic-based spherical particles, so that the carbon fiber is wrapped inside the material. The formula for randomly generating the coordinates of the center of the end face circle of the carbon fiber model is as follows:

[0023]

[0024] in, The center of the circle of the carbon fiber model end face is in the modeling area The coordinates of the axis direction, For modeling area Length in the coordinate direction, is the radius length of the end circle of the carbon fiber model, is the radius length of the ceramic-based spherical particles, It is the uniform distribution function of the fish function library in the PFC3D software. This function randomly takes values ​​in the range of 0.0-1.0.

[0025] Before generating the center of the next carbon fiber model end face circle, use the loop instruction to determine the distance from the center of all generated carbon fiber model end face circles. If the conditions are met, generate it. The judgment formula is as follows:

[0026]

[0027] in, For the next carbon fiber model, the center of the end circle is in the modeling area The coordinates of the coordinate direction, For the next carbon fiber model, the center of the end circle is in the modeling area The coordinates of the coordinate direction, The center of the end circle of the generated carbon fiber model is in the modeling area The coordinates of the coordinate direction, The center of the end circle of the generated carbon fiber model is in the modeling area The coordinates of the coordinate direction, is the radius length of the end circle of the carbon fiber model, is the radius length of the ceramic-based spherical particles.

[0028] When the number of generated carbon fiber model end face circle center coordinates reaches the number of carbon fiber models required to meet the specified volume fraction and relative error, the generation of the carbon fiber model end face circle center is stopped.

[0029] Furthermore, in step (4), the rblock.inside instruction of the fish function library in the PFC3D software is used to detect whether the ceramic-based spherical particles are inside the carbon fiber cylindrical particles, and the range fish instruction for generating the ceramic-based spherical particles is combined to make the generation range of the ceramic-based spherical particles outside the carbon fiber cylindrical particles, and the box instruction for generating the ceramic-based spherical particles is combined to make the generation range of the ceramic-based spherical particles within the required discrete element modeling area.

[0030] The above further beneficial effect is that the absence of ceramic-based particles inside the carbon fiber model is beneficial to the stability of the entire model and is more in line with reality.

[0031] Furthermore, in the step (5), all contact models are assigned as Linear Paralle Bond linear parallel bond contact models, and bond gap parameters are assigned, and emod, kratio, pb_emod, pb_kratio, pb_ten, pb_coh, dp_nratio, and firc are assigned respectively between the linear contacts of carbon fiber cylindrical particles and between the contacts of ceramic-based circular particles.

[0032] The above further beneficial effects are: more effective simulation of the forces generated by various bonding and particle contact inside the material, which is conducive to studying the influence of internal particle arrangement on mechanical properties under certain conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0034] Figure 1 It is a flow chart of a modeling method of a randomly arranged continuous carbon fiber reinforced ceramic-based material provided by an embodiment of the present invention;

[0035] Figure 2 is an end view of a randomly arranged continuous carbon fiber reinforced ceramic-based material according to an embodiment of the present invention;

[0036] Figure 3 is a diagram of a continuous carbon fiber discrete element model of a randomly arranged continuous carbon fiber reinforced ceramic-based material according to an embodiment of the present invention;

[0037] Figure 4 is a three-dimensional image of a randomly arranged continuous carbon fiber reinforced ceramic-based material according to an embodiment of the present invention;

[0038] Figure 5 It is an isometric cross-sectional view of a randomly arranged continuous carbon fiber reinforced ceramic-based material according to an embodiment of the present invention. Specific implementation methods

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0041] The embodiment of the present invention provides a modeling method for a randomly arranged continuous carbon fiber reinforced ceramic matrix composite material, such as Figure 1 As shown, the following steps are included:

[0042] 1. Select the required discrete element modeling area size in the PFC3D software, set the volume fraction and relative error conditions of the carbon fiber in the continuous carbon fiber reinforced ceramic matrix composite model, specify the range of the carbon fiber model end face circle radius generation, and calculate the number and radius of the carbon fiber model required to meet the specified volume fraction and relative error;

[0043] 2. Using the uniform distribution function in the Fish function library, the coordinates of the center of the carbon fiber end face circle are randomly generated with a specified boundary surface in the modeling area as the end face, and the area of ​​the carbon fiber model end face circle is obtained by combining the obtained carbon fiber model radius, and the edge of the area of ​​each carbon fiber end face circle is at least one ceramic-based particle diameter away;

[0044] 3. Generate multiple carbon fiber cylindrical particles along the axial direction of the carbon fiber end face, and set a linear parallel bond contact model (Linear Parallel Bond Model) between the contacting carbon fiber cylindrical particles, so as to bond the multiple carbon fiber cylindrical particles to form a continuous carbon fiber discrete element model;

[0045] 4. Within the selected modeling area and outside the generated carbon fiber discrete element model area, use the range fish function to generate densely arranged ceramic-based spherical particles;

[0046] 5. Set up the linear parallel bond contact model of ceramic-based spherical particles-spherical particles and ceramic-based spherical particles-carbon fiber cylindrical particles, and assign corresponding particle microscopic contact parameters;

[0047] 6. Finally, a discrete element model of randomly arranged continuous carbon fiber reinforced ceramic matrix composites that meets the required volume fraction and relative error conditions is generated.

[0048] Step 1 of the embodiment of the present invention is specifically:

[0049] 1-1. Select the required discrete element modeling area size in the PFC3D software, and set the volume fraction and relative error conditions of the carbon fiber in the continuous carbon fiber reinforced ceramic matrix composite model;

[0050] 1-2. Call the uniform distribution function of the fish function library in PFC3D to make the end face radius of the carbon fiber model Take the value within a reasonable range, the formula is:

[0051]

[0052] in, The minimum value generated for the end radius of the carbon fiber model. The maximum value of the radius of the end face of the carbon fiber model is generated. It is the uniform distribution function of the fish function library in the PFC3D software. This function randomly takes values ​​in the range of 0.0-1.0.

[0053] 1-3. Use the loop command in the PFC3D software to input the end face radius of the carbon fiber model randomly obtained within a reasonable range in 1-2, and calculate the number of carbon fiber models. The formula is as follows:

[0054]

[0055] in, The ideal number for carbon fiber models, is the length of the modeling area in the x-coordinate direction, is the length of the modeling area in the y-coordinate direction, is the length of the modeling area in the z-coordinate direction, is the specified volume fraction, is the cross-sectional radius of the carbon fiber model, is the axial length of the carbon fiber model.

[0056] 1-4. Since the number of carbon fiber roots can only be an integer, calculate the rounded value of the carbon fiber model quantity and substitute it into the formula to obtain the error of the volume fraction under the conditions of the end circle radius of the carbon fiber model obtained in 1-2 and the carbon fiber volume fraction in the continuous carbon fiber reinforced ceramic matrix composite material model set in 1-1. The formula is as follows:

[0057]

[0058] in, The ideal number for carbon fiber models, for Rounded values, is the length of the modeling area in the x-coordinate direction, is the length of the modeling area in the y-coordinate direction, is the length of the modeling area in the z-coordinate direction, is the allowed volume fraction error, is the cross-sectional radius of the carbon fiber model, is the axial length of the carbon fiber model.

[0059] 1-5. If the allowed volume fraction error can be met, the value of the carbon fiber model end face circle radius that meets the volume fraction of carbon fiber in the material model and the relative error conditions is set as the carbon fiber model end face circle radius, and the rounded value of the carbon fiber number is set as the number of carbon fiber models to be generated in the next step.

[0060] Step 2 of the embodiment of the present invention is specifically:

[0061] 2-1. Call the uniform distribution function of the fish function library in the PFC3D software to randomly generate the center coordinates of the end face circle of the carbon fiber model within a specified boundary surface of the required modeling area. The distance between the center coordinates of the end face circle of the carbon fiber model and the boundary of the modeling area should be at least the sum of the radius length of the end face circle of the carbon fiber model and the diameter length of the ceramic-based spherical particles, so that the carbon fiber is wrapped inside the material. The formula for randomly generating the center coordinates of the end face circle of the carbon fiber model is as follows:

[0062] in, The center of the circle of the carbon fiber model end face is in the modeling area The coordinates of the axis direction, For modeling area Length in the coordinate direction, is the radius length of the end circle of the carbon fiber model, is the radius length of the ceramic-based spherical particles, It is the uniform distribution function of the fish function library in the PFC3D software. This function randomly takes values ​​in the range of 0.0-1.0.

[0063] 2-2. Before generating the coordinates of the center of the end circle of the next carbon fiber model, use the loop instruction to determine the distance from the center of all the generated carbon fiber model end circles. If the conditions are met, generate it. The judgment formula is as follows:

[0064] in, For the next carbon fiber model, the center of the end circle is in the modeling area The coordinates of the coordinate direction, For the next carbon fiber model, the center of the end circle is in the modeling area The coordinates of the coordinate direction, The center of the end circle of the generated carbon fiber model is in the modeling area The coordinates of the coordinate direction, The center of the end circle of the generated carbon fiber model is in the modeling area The coordinates of the coordinate direction, is the radius length of the end circle of the carbon fiber model, is the radius length of the ceramic-based spherical particles.

[0065] 2-3. When the number of generated carbon fiber model end face circle center coordinates reaches the number of carbon fiber models required to meet the specified volume fraction and relative error, the generation of carbon fiber model end face circle center coordinates is stopped.

[0066] Step 3 of the embodiment of the present invention is specifically:

[0067] 3-1. Call the loop instruction of the fish function library in PFC3D to generate multiple carbon fiber cylindrical particles along the axial direction according to the center of the end circle of the generated carbon fiber model and the carbon fiber radius that meets the conditions;

[0068] 3-2. A linear parallel bond contact model is set between the contacting carbon fiber cylindrical particles, so that a plurality of carbon fiber cylindrical particles are bonded to form a Figure 3 The discrete element model of the continuous carbon fiber is shown.

[0069] Step 4 of the embodiment of the present invention is specifically:

[0070] 4-1. Define a function in the PFC3D software and call the rblock.inside instruction of the fish function library in the PFC3D software to detect whether the ceramic-based spherical particles are inside the carbon fiber cylindrical particles. When the ceramic-based spherical particles are inside the carbon fiber cylindrical particles, the output function value is 1;

[0071] 4-2. Use the range fish command in the sphere generation in the PFC3D software to make the ceramic-based spherical particles generate in a range other than the function value 1 output in 4-1;

[0072] 4-3. Using the box command in the sphere generation in the PFC3D software, the length, width and height of the box are equal to the length, width and height of the discrete element modeling area, and the ceramic matrix particles are filled in the discrete element modeling area;

[0073] 4-4. Finally, the ceramic-based particle filling range is outside the carbon fiber cylindrical particles and within the required discrete element modeling area;

[0074] 4-5. Build a wall at the edge of the modeling area, whose length, width and height are equal to the length, width and height of the discrete element modeling area;

[0075] 4-6. Use the solve command in PFC3D software to make the particles densely arranged;

[0076] 4-7, the final result is as follows Figure 4 The discrete element model diagram of continuous carbon fiber reinforced ceramic matrix material is shown.

[0077] Step 5 of the embodiment of the present invention is specifically:

[0078] All contact models are assigned the Linear Paralle Bond linear parallel bond contact model, and the bond gap parameters are assigned, and emod, kratio, pb_emod, pb_kratio, pb_ten, pb_coh, dp_nratio, and firc are assigned respectively between the linear contacts of carbon fibers and between the contacts of ceramic matrix particles.

Claims

1. A modeling method for randomly arranged continuous carbon fiber reinforced ceramic matrix composite materials, the modeling steps are as follows: (1) In the PFC3D software, select the required discrete element modeling area size, set the volume fraction and relative error conditions of the carbon fiber in the continuous carbon fiber reinforced ceramic matrix composite model, specify the range of the carbon fiber model end face circle radius generation, and calculate the number and radius of the carbon fiber model required to meet the specified volume fraction and relative error; (2) Using the uniform distribution function in the Fish function library, the coordinates of the center of the carbon fiber end face circle are randomly generated with a specified boundary surface in the modeling area as the end face, and the area of ​​the carbon fiber model end face circle is obtained by combining the obtained carbon fiber model radius, and the edge of the area of ​​each carbon fiber end face circle is at least one ceramic-based particle diameter away; (3) generating a plurality of carbon fiber cylindrical particles along the axial direction of the carbon fiber end face, and setting a linear parallel bond contact model (Linear Parallel Bond Model) between the contacting carbon fiber cylindrical particles, so as to bond the plurality of carbon fiber cylindrical particles to form a continuous carbon fiber discrete element model; (4) Using the range fish function to generate densely packed ceramic-based spherical particles within the selected modeling area and outside the generated carbon fiber discrete element model area; (5) Setting up the linear parallel bond contact model of ceramic-based spherical particles-spherical particles and ceramic-based spherical particles-carbon fiber cylindrical particles, and assigning the corresponding particle microscopic contact parameters; (6) Finally, a discrete element model of randomly arranged continuous carbon fiber reinforced ceramic matrix composites that meets the required volume fraction and relative error conditions is generated.

2. The modeling method of a randomly arranged continuous carbon fiber reinforced ceramic matrix composite material according to claim 1, characterized in that: In step (1), the uniform distribution function in the fish function library is called in the PFC3D software to make the end face radius of the carbon fiber model Take the value within a reasonable range, the formula is: in, The minimum value generated for the end face radius of the carbon fiber model. The maximum value of the radius of the end face of the carbon fiber model is generated. It is the uniform distribution function of the fish function library in the PFC3D software. This function randomly takes values ​​in the range of 0.0-1.

0. Combined with the loop instruction, the formula is used to calculate the appropriate carbon fiber model end face radius and the appropriate number of carbon fiber models, so that the generated randomly arranged continuous carbon fiber reinforced ceramic matrix material reaches the specified volume fraction and is within the specified error range. The formula is: in, in, is the number of carbon fiber models, for Rounded values, is the length of the modeling area in the x-coordinate direction, is the length of the modeling area in the y-coordinate direction, is the length of the modeling area in the z-coordinate direction, is the specified volume fraction, is the allowable volume fraction error (when When the volume fraction of carbon fiber in the material model and the relative error conditions are met, the end face radius of the carbon fiber model can be found. is the end face radius of the carbon fiber model, is the axial length of the carbon fiber model.

3. The modeling method of a randomly arranged continuous carbon fiber reinforced ceramic matrix composite material according to claim 1, characterized in that: In the step (2), the uniform distribution function in the Fish function library of the PFC software is used to randomly generate the coordinates of the center of the end face circle of the carbon fiber model within a specified boundary surface of the required modeling area. The distance between the coordinates of the center of the end face circle of the carbon fiber model and the boundary of the modeling area leaves at least the sum of the radius length of the end face circle of the carbon fiber model and the diameter length of the ceramic-based spherical particles, so that the carbon fiber is wrapped inside the material. The formula for randomly generating the coordinates of the center of the end face circle of the carbon fiber model is as follows: in, The center of the circle of the carbon fiber model end face is in the modeling area The coordinates of the axis direction, For modeling area Length in the coordinate direction, is the radius length of the end circle of the carbon fiber model, is the radius length of the ceramic-based spherical particles, It is the uniform distribution function of the fish function library in the PFC3D software. This function randomly takes values ​​in the range of 0.0-1.

0. Before generating the center of the next carbon fiber model end face circle, use the loop instruction to determine the distance from the center of all generated carbon fiber model end face circles. If the conditions are met, generate it. The judgment formula is as follows: in, For the next carbon fiber model, the center of the end circle is in the modeling area The coordinates of the coordinate direction, For the next carbon fiber model, the center of the end circle is in the modeling area The coordinates of the coordinate direction, The center of the end circle of the generated carbon fiber model is in the modeling area The coordinates of the coordinate direction, The center of the end circle of the generated carbon fiber model is in the modeling area The coordinates of the coordinate direction, is the radius length of the end circle of the carbon fiber model, is the radius length of the ceramic-based spherical particles. When the number of generated carbon fiber model end face circle center coordinates reaches the number of carbon fiber models required to meet the specified volume fraction and relative error, the generation of the carbon fiber model end face circle center is stopped.

4. The modeling method of a randomly arranged continuous carbon fiber reinforced ceramic matrix composite material according to claim 1, characterized in that: In the step (4), the rblock.inside instruction of the fish function library in the PFC3D software is used to detect whether the ceramic-based spherical particles are inside the carbon fiber cylindrical particles. The range fish instruction for generating the ceramic-based spherical particles is combined to make the generation range of the ceramic-based spherical particles outside the carbon fiber cylindrical particles. The box instruction for generating the ceramic-based spherical particles is combined to make the generation range of the ceramic-based spherical particles within the required discrete element modeling area.

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