A cross-scale simulation method for continuous fiber reinforced porous composite materials

Abstract

This invention relates to the field of 3D printing continuous fiber technology, specifically a cross-scale simulation method for continuous fiber reinforced porous composite materials. The specific steps are as follows: Step S1: Establish a representative volumetric unit model of the porous composite across scales; Step S2: Add a pore structure to the representative volumetric unit model; Step S3: Establish a homogenization model of the composite. By establishing a representative volumetric unit model of the porous composite across scales, this invention addresses the relatively blank area in the current field of continuous fiber simulation and meets the needs for simulation solutions. The results obtained by this invention in conjunction with experimental data are relatively accurate. The method disclosed in this invention is applicable to the performance prediction of novel composites under various conditions and parameter indices.

Description

Technical Field

[0001] This invention relates to the field of 3D printing continuous fiber technology, specifically a cross-scale simulation method for continuous fiber reinforced porous composite materials. Background Technology

[0002] In the development of continuous fiber composite materials, it is often necessary to test the mechanical properties of composites with different parameters. However, in actual experimental operations, the slippage of the connection structure and systematic errors often make it difficult to test the ultimate performance of the material or obtain accurate mechanical property data. To address this problem, this invention proposes a cross-scale simulation method to simulate the cross-scale simulation of porous composite materials with different continuous fiber contents. This provides guidance and reference for experimental data, increasing the accuracy and reliability of mechanical property test results. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a cross-scale simulation method for continuous fiber-reinforced porous composite materials.

[0004] A cross-scale simulation method for continuous fiber-reinforced porous composite materials, the specific steps of which are as follows:

[0005] Step S1: Establish a representative volumetric unit model for porous composites across scales: Construct a mechanical characterization of the filament for cross-scale analysis, replace the complex microstructure model with a homogenized equivalent model, and explore the mathematical relationship between fiber content and mechanical constitutive model.

[0006] Step S2: Add a porous structure to the representative volume element model to establish a representative element of the porous composite material, and simulate the element to solve for the required anisotropic parameters.

[0007] Step S3: Establish a homogenization model for the composite material, use the homogenization model to equivalently replace the porous composite material, and combine it with periodic boundary conditions to solve the problem through simulation.

[0008] In step S1, the representative volume unit cell size is selected as 50×50×50μm, the fiber diameter is 7μm, and the fiber content is 50wt.%.

[0009] In step S1, the fiber arrangement is simulated and selected to be parallel to the matrix material according to the actual situation, and it is in an irregular random dispersion form. The fiber content percentage is adjusted as needed.

[0010] In step S1, the mathematical relationship between fiber content and mechanical constitutive model is as follows:

[0011] Establish the fiber content conversion expression as shown below:

[0012]

[0013] In the formula, υ f It is the fiber volume content, w f It is its mass content, ρ f It is the fiber density, ρ c ψ is the density of the filament, and ψ is the correction factor.

[0014] The longitudinal modulus of the filament is typically predicted using a hybrid method. Based on the static equilibrium equations and one-dimensional Hooke's law, the longitudinal modulus of the equivalent model can be solved:

[0015]

[0016] The transverse modulus of the filament is solved using the sub-region method, employing a square instead of a circular fiber cross-section, and then using the inverse mixing rule and the mixing rule to determine its transverse modulus.

[0017]

[0018] In the formula, E2 is the transverse modulus of the wire, E f2 It is the transverse modulus of the fiber.

[0019] The filament is a transversely isotropic material with equal planar shear effects (G). 12 =G 13 The shear deformation mode involves relative slippage of the fibers, while the effect of planar shear deformation is relative rolling of the fibers. It is approximated that the shear moduli in the three directions are equal, i.e., G. 12 =G 13 =G 23 Combining this with empirical formulas, we can obtain:

[0020]

[0021] In the formula, G f It is the fiber shear modulus, G m It is the matrix shear modulus.

[0022] The composite material has a Poisson's ratio u 12 u 13 and u 23 Also controlled by fiber movement patterns, where u 12 The mixed rule can be used to calculate (u) 13 =u 12 ), u 23 Then, we use empirical formulas to solve the problem:

[0023]

[0024]

[0025] In step 2, the pore diameter is 5-10 μm and the porosity is about 2%. A representative unit cell of the porous composite is established, and then the required anisotropic parameters are obtained by simulation of the unit cell.

[0026] In step 3, the porous composite material used is a 200×15×1mm sample, printed in 4 layers, and verified by static analysis simulation combined with periodic boundary conditions.

[0027] The beneficial effects of this invention are: by establishing a representative volumetric unit model of porous composites across scales, it solves the problem of the relative gap in the current field of continuous fiber simulation and meets the needs of simulation solutions; the results of this invention in conjunction with experimental data are relatively accurate; and the method disclosed in this invention is applicable to the performance prediction of novel composites under various different situations and parameter indices. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Figure 1 This is a composite material representative structural unit model of the present invention;

[0030] Figure 2 This is a representative structural unit model of the porous composite material of the present invention;

[0031] Figure 3 This is the composite material cross-sectional model established for this invention. Detailed Implementation

[0032] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below.

[0033] like Figures 1 to 3 As shown, a cross-scale simulation method for continuous fiber reinforced porous composite materials is presented, and its specific steps are as follows:

[0034] Step S1: Establish a representative volumetric unit model for porous composites across scales: Construct a mechanical characterization of the filament for cross-scale analysis, replace the complex microstructure model with a homogenized equivalent model, and explore the mathematical relationship between fiber content and mechanical constitutive model.

[0035] Step S2: Add a porous structure to the representative volume element model to establish a representative element of the porous composite material, and simulate the element to solve for the required anisotropic parameters.

[0036] Step S3: Establish a homogenization model for the composite material, use the homogenization model to equivalently replace the porous composite material, and combine it with periodic boundary conditions to solve the problem through simulation.

[0037] In step S1, the representative volume unit cell size is selected as 50×50×50μm, the fiber diameter is 7μm, and the fiber content is 50wt.%.

[0038] In step S1, the fiber arrangement is simulated and selected to be parallel to the matrix material according to the actual situation, and it is in an irregular random dispersion form. The fiber content percentage is adjusted as needed.

[0039] By establishing a representative volumetric unit model of porous composites across scales, this invention addresses the relatively blank area in the field of continuous fiber simulation and meets the needs of simulation solutions. The results obtained by this invention in conjunction with experimental data are relatively accurate. The method disclosed in this invention is applicable to the performance prediction of novel composites under various conditions and parameter indices.

[0040] In step S1, the mathematical relationship between fiber content and mechanical constitutive model is as follows:

[0041] Establish the fiber content conversion expression as shown below:

[0042]

[0043] In the formula, υ f It is the fiber volume content, w f It is its mass content, ρ f It is the fiber density, ρ c ψ is the density of the filament, and ψ is the correction factor.

[0044] The longitudinal modulus of the filament is typically predicted using a hybrid method. Based on the static equilibrium equations and one-dimensional Hooke's law, the longitudinal modulus of the equivalent model can be solved:

[0045]

[0046] The transverse modulus of the filament is solved using the sub-region method, employing a square instead of a circular fiber cross-section, and then using the inverse mixing rule and the mixing rule to determine its transverse modulus.

[0047]

[0048] In the formula, E2 is the transverse modulus of the wire, E f2 It is the transverse modulus of the fiber.

[0049] The filament is a transversely isotropic material with equal planar shear effects (G). 12 =G 13 The shear deformation mode involves relative fiber slippage. Although the effect of planar shear deformation is relative fiber rolling, the shearing action mainly depends on the matrix deformation. Therefore, the shear modulus in the three directions can be approximated as equal, i.e., G. 12 =G 13=G 23 Combining this with empirical formulas, we can obtain:

[0050]

[0051] In the formula, G f It is the fiber shear modulus, G m It is the matrix shear modulus.

[0052] The composite material has a Poisson's ratio u 12 u 13 and u 23 Also controlled by fiber movement patterns, where u 12 The mixed rule can be used to calculate (u) 13 =u 12 ), u 23 Then, we use empirical formulas to solve the problem:

[0053]

[0054]

[0055] In step 2, the pore diameter is 5-10 μm and the porosity is about 2%. A representative unit cell of the porous composite is established, and then the required anisotropic parameters are obtained by simulation of the unit cell.

[0056] like Figure 1 As shown, an instance model representing a structural unit is created.

[0057] like Figure 2 The image shows the result after the representative structural unit has been porousized.

[0058] like Figure 3 The image shows the cross-sectional structure of the composite material. The image illustrates its layup pattern. In this example, there are a total of 6 layers, symmetrically distributed. The angles marked are the layup angles used during printing.

[0059] In step 2, the unit volume is solved, and the specific parameters are: a representative volume unit model is created and processed to simulate the pore structure generated in actual printing. Then, the data of the representative unit with pores is simulated, and the data is finally applied to the performance simulation of the composite material.

[0060] Specifically, in step 2, the model is derived to simulate the representative volume element structure with pores through secondary processing. The mechanical constitutive model of the element is solved and modeled to simulate the porous continuous fiber composite material in actual production. The content and arrangement of pores need to be designed according to the actual situation of the material in order to obtain the simulation results that are closest to reality.

[0061] In step 3, the porous composite material used is a 200×15×1mm sample, printed in 4 layers, and verified by static analysis simulation combined with periodic boundary conditions.

[0062] Specifically, in step 3, the porous geometric model is subjected to mechanical simulation to obtain simulation data under specified boundary conditions and the required mechanical performance indicators, thereby aligning theoretical and practical data and achieving ideal experimental results.

[0063] Specifically, in step 3, the desired shape is modeled using modeling software during simulation, such as a tensile specimen with fixed supports at both ends. A tensile force of 1000N is applied to one end, and the stress-strain condition is solved. The result is then compared with the actual tensile data.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely prisms of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A cross-scale simulation method for continuous fiber-reinforced porous composite materials, characterized in that: The specific steps are as follows: Step S1: Establish a representative volumetric unit model for porous composites across scales: Construct a mechanical characterization of the filament for cross-scale analysis, replace the complex microstructure model with a homogenized equivalent model, and explore the mathematical relationship between fiber content and mechanical constitutive model. Step S2: Add a porous structure to the representative volume element model to establish a representative element of the porous composite material, and simulate the element to solve for the required anisotropic parameters. Step S3: Establish a homogenization model for the composite material, use the homogenization model to equivalently replace the porous composite material, and combine it with periodic boundary conditions to solve the problem through simulation. In step S1, the fiber arrangement is simulated and selected to be parallel to the matrix material according to the actual situation, and it is in an irregular random dispersion form. The fiber content percentage is adjusted as needed. In step S1, the mathematical relationship between fiber content and mechanical constitutive model is as follows: Establish the fiber content conversion expression as shown below: （1） In the formula, It is the fiber volume content. It is its quality content, It is fiber density. That is the density of the silk material. It is a correction factor.

2. The cross-scale simulation method for continuous fiber-reinforced porous composite materials according to claim 1, characterized in that: In step S1, the representative volume unit cell size is selected as 50×50×50μm, the fiber diameter is 7μm, and the fiber content is 50wt.%.

3. The cross-scale simulation method for continuous fiber-reinforced porous composite materials according to claim 1, characterized in that: The longitudinal modulus of the filament is predicted using a hybrid method. Based on the static equilibrium equations and one-dimensional Hooke's law, the longitudinal modulus of the equivalent model can be solved: （2）； E f1 It is the fiber longitudinal modulus, E m It is the matrix modulus.

4. The cross-scale simulation method for continuous fiber-reinforced porous composite materials according to claim 3, characterized in that: The transverse modulus of the filament is solved using the sub-region method, employing a square instead of a circular fiber cross-section, and then using the inverse mixing rule and the mixing rule to determine its transverse modulus. （3） In the formula, It is the transverse modulus of the filament. It is the transverse modulus of the fiber.

5. The cross-scale simulation method for continuous fiber-reinforced porous composite materials according to claim 4, characterized in that: The filament is transversely isotropic, with equal shear effects between its surfaces. The shear deformation mode involves relative slippage of the fibers. The effect of shear deformation is relative rolling of the fibers. It is approximated that the shear moduli in the three directions are equal, i.e., Combining this with empirical formulas, we can obtain: （4） In the formula, It is the fiber shear modulus. It is the matrix shear modulus.

6. The cross-scale simulation method for continuous fiber-reinforced porous composite materials according to claim 5, characterized in that: The Poisson's ratio of the composite material Also controlled by fiber movement patterns, among which... The mixed rule can be used for calculation. Then, an empirical formula is used to solve the problem: （5） （6） u f It is the Poisson's ratio of the fiber, u m It is the matrix Poisson's ratio.

7. The cross-scale simulation method for continuous fiber-reinforced porous composite materials according to claim 1, characterized in that: In step 2, the pore diameter is 5~10μm and the porosity is 2%. A representative unit cell of the porous composite is established, and then the required anisotropic parameters are obtained by simulation of the unit cell.

8. The cross-scale simulation method for continuous fiber reinforced porous composite materials according to claim 1, characterized in that: In step 3, the porous composite material used is a 200×15×1mm sample, printed in 4 layers, and verified by static analysis simulation combined with periodic boundary conditions.

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