Simulation method for thermal constitutive damage failure of 3D printing fiber reinforced composite material

Abstract

The invention discloses a 3D printing fiber reinforced composite material thermal constitutive damage failure simulation method, which comprises the following steps: adopting an XCT slice scanning result to construct a three-dimensional simulation model, and carrying out grid division on the three-dimensional simulation model; describing a finite deformation constitutive relation of the gridded three-dimensional simulation model based on a work conjugate pair of a second Piola Kirchhoff stress and Green Lagrange strain combination, and constructing a 3D printing fiber reinforced composite constitutive model; a 3D printing fiber reinforced composite material damage failure model is developed on the basis of the maximum stress criterion; a Kriging agent model is adopted to describe the influence of the temperature on the mechanical property, and the elastic constant, the yield stress and the correlation equation of the maximum strength and the temperature of the 3D printing fiber reinforced composite material damage failure model are established; under transverse stretching, the temperature condition is changed for simulation. The method has the remarkable effects that a simulation result is basically consistent with an experimental result, and the simulation effect is relatively good.

Description

Technical Field

[0001] The present invention relates to the technical field of simulation calculation of 3D printed fiber reinforced composite materials, and in particular to a simulation method for thermal constitutive damage failure of 3D printed fiber reinforced composite materials. Background Art

[0002] Additive manufacturing technology, or 3D printing technology, has become a powerful tool in the field of rapid prototyping and has also been a research hotspot in this field in the past decade. Its manufacturing principle is to use metal powder or wire as raw materials based on computer-aided design models or data generated by tomography. The energy source (electron beam, laser beam and other heat sources) is controlled by a computer system to scan and solidify the discrete materials spread layer by layer, thereby directly forming three-dimensional parts. The microstructure is precisely controlled in the material forming process, and 3D complex objects of any shape can be quickly processed and manufactured.

[0003] Continuous fiber reinforced composite materials are high-strength, high-rigidity, and high-toughness composite materials made from continuous fibers as reinforcing materials and thermoplastic resins as matrices through a process of melt impregnation of thermoplastic resins.

[0004] As far as the current research status is concerned, the performance prediction of 3D printed fiber-reinforced composite structures under thermal-mechanical coupling is limited by the lack of experimental data and theoretical models, which limits the accuracy and reliability of the prediction model.

[0005] Therefore, it is necessary to propose a simulation calculation method suitable for 3D printed fiber reinforced composite materials, that is, it is necessary to provide a simulation method for the constitutive damage failure model of 3D printed fiber reinforced composites under thermal-mechanical coupling, aiming to enrich the theoretical model and improve accuracy and reliability. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a simulation method for thermal constitutive damage failure of 3D printed fiber reinforced composites, which can overcome the limitations brought about by the lack of current experimental data and theoretical models and improve the simulation accuracy and reliability.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A simulation method for thermal constitutive damage failure of 3D printed fiber reinforced composites, the key of which is to include the following steps:

[0009] Step 1: construct a three-dimensional simulation model using XCT slice scanning results, and mesh the three-dimensional simulation model;

[0010] Step 2, based on the work conjugate of the second Piola Kirchhoff stress and Green Lagrange strain combination, the finite deformation constitutive relation of the three-dimensional simulation model after meshing is described, and the constitutive model of 3D printed fiber reinforced composites is constructed;

[0011] Step 3: Based on the constitutive model of 3D printed fiber reinforced composites, develop a damage failure model of 3D printed fiber reinforced composites based on the maximum stress criterion;

[0012] Step 4: Use the Kriging proxy model to describe the effect of temperature on mechanical properties, and establish the correlation equations of elastic constants, yield stress, maximum strength and temperature of the 3D printed fiber reinforced composite damage failure model;

[0013] Step 5: Under transverse stretching, change the temperature conditions to perform simulation.

[0014] Furthermore, the specific steps of constructing a three-dimensional simulation model using the XCT slice scanning results in step 1 are as follows:

[0015] According to the RGB values ​​of the XCT slice images, the contour features of the sample that do not contain pores are extracted;

[0016] According to the contour feature form and combined with the pore content of the sample obtained by XCT analysis, the contour features are converted into an actual three-dimensional model.

[0017] Furthermore, when the three-dimensional simulation model is meshed in step 1, the radial surface meshing of the specimen is performed by a mixed meshing method of quadrilaterals and triangles, and the specimen body mesh is created by a surface mesh stretching method.

[0018] Furthermore, in step 2, the finite deformation constitutive relation of the meshed three-dimensional simulation model is described based on the work conjugate pair of the second Piola Kirchhoff stress and the Green Lagrange strain combination. When constructing the constitutive model of 3D printed fiber reinforced composites, the Liu-Huang-Stout yield criterion is used to describe the anisotropic yield surface of the 3D printed fiber reinforced composites, and the associated flow criterion is used to describe the nonlinear evolution of the 3D printed fiber reinforced composites.

[0019] Furthermore, the expression for describing the anisotropic yield surface of the 3D printed fiber reinforced composite using the Liu-Huang-Stout yield criterion is:

[0020]

[0021] Among them, F, G, H, L, M, N, I, J, and K are the anisotropic parameters of 3D printed fiber-reinforced composite filaments at different temperatures, and σ 11 , σ22 , σ 33 is the isotropic normal stress component, are the isotropic shear stress components.

[0022] Furthermore, the expression for describing the nonlinear evolution of 3D printed fiber reinforced composites using the associated flow criterion is:

[0023]

[0024] in, is the rate of change of the strain tensor; It is the change rate of plastic hardening coefficient of 3D printed fiber reinforced composites.

[0025] Furthermore, when developing the damage failure model of 3D printed fiber reinforced composites based on the maximum stress criterion in step 3, the axial failure model acts on the overall area, and the lateral failure model and the shear failure model are only applied to the bonding area between the wires.

[0026] Furthermore, the mathematical expression of the damage failure model of the 3D printed fiber reinforced composite is:

[0027]

[0028] Among them, σ f1t,T , σ f1c,T are the maximum strength of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ f2t,T , σ f2c,T They are the maximum strength of the 3D printed fiber-reinforced composite filament in transverse tension and compression at temperature T, respectively; It is the maximum in-plane shear strength of 3D printed fiber-reinforced composite filament at temperature T.

[0029] Furthermore, the correlation equation between the elastic constant and temperature of the 3D printed fiber reinforced composite damage failure model in step 4 is:

[0030]

[0031] Among them, E 11 is the elastic modulus in direction 1, E 22 is the elastic modulus in two directions, G 12 is the shear modulus of the 12-plane, T is the temperature;

[0032] The correlation equation between yield stress and temperature of the damage failure model of 3D printed fiber reinforced composites is:

[0033]

[0034] Among them, σ 1t,T , σ1c，T are the yield stress of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ 2t,T , σ 2c，T They are the yield stress of 3D printed fiber reinforced composite filaments in transverse tension and compression at temperature T; is the in-plane shear yield stress of the 3D printed fiber reinforced composite wire at temperature T; the correlation equation between the maximum strength and temperature of the 3D printed fiber reinforced composite damage failure model is:

[0035]

[0036] Among them, σ f1t,T , σ f1c，t are the maximum strength of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ f2t,T , σ f2c，T They are the maximum strength of the 3D printed fiber-reinforced composite filament in transverse tension and compression at temperature T, respectively; It is the maximum in-plane shear strength of 3D printed fiber reinforced composite filament at temperature T.

[0037] Furthermore, the temperature change range of the temperature condition in step 5 is 23°C to 230°C.

[0038] The remarkable effects of the present invention are:

[0039] The present invention combines the 3D printed fiber reinforced composite finite element model, the 3D printed fiber reinforced composite filament constitutive and damage model, and takes into account the temperature effect and anisotropy influence, and performs simulation calculations on the 3D printed fiber reinforced composite structure to obtain effective simulation prediction results and experimental data that conform to real conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of the method of the present invention;

[0041] Figure 2 It is the sample feature extraction and three-dimensional model conversion process of the present invention;

[0042] Figure 3 The grid division method of the present invention;

[0043] Figure 4 It is a schematic diagram of a model of the present invention;

[0044] Figure 5 This is a schematic diagram of the material parameters changing with temperature in the present invention;

[0045] Figure 6 This is a simulation result diagram of the present invention at different temperatures under transverse (90 degree) stretching. DETAILED DESCRIPTION

[0046] The specific implementation manner and working principle of the present invention are further described in detail below with reference to the accompanying drawings.

[0047] like Figure 1 As shown, an embodiment of the present invention provides a simulation method for thermal constitutive damage failure of 3D printed fiber reinforced composites, and the specific steps are as follows:

[0048] Step 1: construct a three-dimensional simulation model using XCT slice scanning results, and mesh the three-dimensional simulation model;

[0049] In this example, the specific steps for constructing a 3D simulation model using XCT slice scanning results are as follows:

[0050] The XCT slice images are processed by the computer vision library in Python software, and the contour features of the sample that do not contain pores are extracted according to the RGB values ​​of the XCT slice images;

[0051] According to the form of contour features and the pore content of the sample obtained by XCT analysis, the contour features are converted into an actual three-dimensional model through SOLIDWORKS software. To ensure the accuracy and feasibility of the simulation calculation, the contour features are replaced by regular filament features. The two sides of the filament are represented by elliptical features, and the middle part is represented by a quadrilateral. The sample feature extraction and three-dimensional model conversion process is shown in the figure below. Figure 2 .

[0052] In this example, the specific steps for meshing the 3D simulation model are:

[0053] In this embodiment, considering that some regions have small features, the radial surface mesh of the specimen is divided by a mixed quadrilateral and triangle mesh, and the volume mesh is created by surface mesh stretching. Figure 3 All simulation calculations of different loading types use displacement loading, and the calculation method is explicit. The six end faces of the specimen are shown in Figure 4As shown, the right end face of the three-dimensional simulation model is set1, and the left end face is set2; the upper end face of the model is set3, and the lower end face is set4; the front end face of the model is set5, and the rear end face is set6. The boundary conditions for axial tension and compression are as follows: the x direction of the set1 surface is used as the direction of tension or compression, the displacement distance is set to 0.1mm / -0.1mm, and the set2 surface imposes constraints in the x direction; the boundary conditions for transverse tension or compression are as follows: the y direction of the set3 surface is used as the direction of tension or compression, the displacement distance is set to 0.1mm for tension and -0.5mm for compression, and the set4 surface imposes constraints in the y direction; the boundary conditions for shear are as follows: the action surface of the shear loading is set1, the direction is the y direction, the displacement distance is set to 0.1mm, the set2 surface, the set3 surface and the set4 surface all impose constraints in the y direction, and the set6 end surface imposes constraints in the z direction and remains stationary.

[0054] Step 2, based on the work conjugate of the second Piola Kirchhoff stress and Green Lagrange strain combination, the finite deformation constitutive relation of the three-dimensional simulation model after meshing is described, and the constitutive model of 3D printed fiber reinforced composites is constructed;

[0055] Among them, the Green-Lagrange strain tensor E is calculated based on the deformation gradient F, and the calculation formula is as follows:

[0056]

[0057] Where I is the unit tensor. The deformation gradient F takes into account thermal expansion deformation, elastic deformation, and plastic deformation. Thermal expansion deformation takes into account the anisotropy of 3D printed fiber reinforcement, and the thermal eigenstrain α is calculated as follows:

[0058]

[0059] When there is no temperature change effect in the numerical simulation analysis process, the effect of thermal expansion deformation can be ignored. Therefore, the calculation formula of the second Piola-Kirchhoff stress S is as follows:

[0060] S=C T (E-α-E p )

[0061] Among them, C T is the elastic matrix at temperature T, E p It is thermoplastic deformation.

[0062] Since 3D printed fiber reinforced composites have obvious anisotropy under axial tension and compression and transverse tension and compression loading under different temperature conditions, the Liu-Huang-Stout yield criterion is used to describe the anisotropic yield surface of 3D printed fiber reinforced composites. The calculation formula is as follows:

[0063]

[0064] Among them, F, G, H, L, M, N, I, J, and K are the anisotropic parameters of 3D printed fiber-reinforced composite filaments at different temperature conditions, σ 11 , σ 22 , σ 33 is the isotropic normal stress component, are the isotropic shear stress components.

[0065] Considering that the 3D printed fiber-reinforced composite filament is transversely isotropic, the calculation formulas for the anisotropic parameters are as follows:

[0066]

[0067]

[0068] Among them, σ 1t,T , σ 1c,T are the yield stress of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ 2t,T , σ 2c，T In particular, the yield stress of the 3D printed fiber-reinforced composite filament in transverse tension and compression at temperature T; is the in-plane shear yield stress of the 3D printed fiber-reinforced composite filament at temperature T; It is the out-of-plane shear yield stress of 3D printed fiber reinforced composite filament at temperature T.

[0069] The expression for describing the nonlinear evolution of 3D printed fiber reinforced composites using the associated flow criterion is:

[0070]

[0071] in, is the rate of change of the strain tensor; is the change rate of the plastic hardening coefficient of the 3D printed fiber reinforced composite. The hardening coefficient is calculated by Newton-Raphson iteration.

[0072] Step 3: Based on the constitutive model of 3D printed fiber reinforced composites, a damage failure model of 3D printed fiber reinforced composites is developed on the basis of the maximum stress criterion, in which the axial failure model acts on the entire area, and the lateral failure model and shear failure model are only applied to the bonding area between the wires;

[0073] The mathematical expression of the damage failure model of the 3D printed fiber reinforced composite is:

[0074]

[0075] Among them, σ f1t,T , σ f1c,T are the maximum strength of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ f2t,T , σ f2c，T They are the maximum strength of the 3D printed fiber-reinforced composite filament in transverse tension and compression at temperature T, respectively; It is the maximum in-plane shear strength of 3D printed fiber reinforced composite filament at temperature T.

[0076] Step 4: Use the Kriging proxy model to describe the effect of temperature on mechanical properties, and establish the correlation equations of elastic constants, yield stress, maximum strength and temperature of the 3D printed fiber reinforced composite damage failure model;

[0077] In this example, the correlation equation between the elastic constant and temperature of the 3D printed fiber reinforced composite damage failure model is:

[0078]

[0079] Among them, E 11 is the elastic modulus in direction 1, E 22 is the elastic modulus in two directions, G 12 is the shear modulus of the 12-plane, T is the temperature;

[0080] In this example, the correlation equation between the yield stress and temperature of the 3D printed fiber reinforced composite damage failure model is:

[0081]

[0082] Among them, σ 1t,T , σ 1c，T are the yield stress of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ 2t,T , σ 2c，T They are the yield stress of 3D printed fiber reinforced silk composites in transverse tension and compression at temperature T; is the in-plane shear yield stress of the 3D printed fiber reinforced silk composite at temperature T;

[0083] In this example, the correlation equation between the maximum strength and temperature of the 3D printed fiber reinforced composite damage failure model is:

[0084]

[0085] Among them, σ f1t,T , σ f1c，T are the maximum strength of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ f2t,T , σ f2c，T They are the maximum strength of the 3D printed fiber-reinforced composite filament in transverse tension and compression at temperature T, respectively; It is the maximum in-plane shear strength of 3D printed fiber-reinforced composite filament at temperature T.

[0086] After experiments, the results of material parameters changing with temperature are as follows Figure 5 .

[0087] Step 5: Under transverse (90 degree) stretching, simulations were performed at 23°C, 80°C, 130°C, 180°C, and 230°C respectively. The simulation results are as follows: Figure 6 shown.

[0088] In summary, the embodiment of the present invention combines the 3D printed fiber reinforced composite finite element model, the wire constitutive and damage models, and takes into account the temperature effect and anisotropy, and performs simulation calculations on the 3D printed fiber reinforced composite structure to obtain effective simulation prediction results and experimental data that conform to the actual situation.

[0089] The above only describes in detail the preferred embodiments of the present invention, which is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0090] It should be understood that, although each step in the flow chart of the embodiment of the present invention is shown in sequence according to the indication of the arrow, these steps are not necessarily performed in sequence according to the order indicated by the arrow. Unless there is a clear explanation in this article, the execution of these steps does not have strict order restrictions, and these steps can be performed in other orders. Moreover, at least a portion of the steps in each embodiment may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these sub-steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0091] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the disclosure in the specification and examples. This application is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the claims.

Claims

1. A simulation method for thermal constitutive damage failure of 3D printed fiber reinforced composites, characterized in that: The steps include: Step 1: construct a three-dimensional simulation model using XCT slice scanning results, and mesh the three-dimensional simulation model; Step 2, based on the work conjugate of the second Piola Kirchhoff stress and Green Lagrange strain combination, the finite deformation constitutive relation of the three-dimensional simulation model after meshing is described, and the constitutive model of 3D printed fiber reinforced composites is constructed; Step 3: Based on the constitutive model of 3D printed fiber reinforced composites, develop a damage failure model of 3D printed fiber reinforced composites on the basis of the maximum stress criterion; Step 4: Use the Kriging proxy model to describe the effect of temperature on mechanical properties, and establish the correlation equations of elastic constants, yield stress, maximum strength and temperature of the 3D printed fiber reinforced composite damage failure model; Step 5: Under transverse stretching, change the temperature conditions to perform simulation.

2. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 1, characterized in that: The specific steps of constructing a three-dimensional simulation model using XCT slice scanning results in step 1 are as follows: According to the RGB values ​​of the XCT slice images, the contour features of the sample that do not contain pores are extracted; According to the contour feature form and combined with the pore content of the sample obtained by XCT analysis, the contour features are converted into an actual three-dimensional model.

3. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 2, characterized in that: When meshing the three-dimensional simulation model in step 1, the radial surface meshing of the specimen is performed by a mixed meshing method of quadrilaterals and triangles, and the specimen body mesh is created by surface mesh stretching.

4. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 1, characterized in that: In step 2, the work conjugate pair based on the second Piola Kirchhoff stress and Green Lagrange strain combination is used to describe the finite deformation constitutive relation of the three-dimensional simulation model after meshing. When constructing the constitutive model of 3D printed fiber reinforced composites, the Liu-Huang-Stout yield criterion is used to describe the anisotropic yield surface of the 3D printed fiber reinforced composites, and the associated flow criterion is used to describe the nonlinear evolution of the 3D printed fiber reinforced composites.

5. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 4, characterized in that: The expression for describing the anisotropic yield surface of 3D printed fiber reinforced composites using the Liu-Huang-Stout yield criterion is: Among them, F, G, H, L, M, N, I, J, and K are the anisotropic parameters of 3D printed fiber-reinforced composite filaments at different temperature conditions, σ 11 , σ 22 , σ 33 is the isotropic normal stress component, are the isotropic shear stress components.

6. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 4, characterized in that: The expression for describing the nonlinear evolution of 3D printed fiber reinforced composites using the associated flow criterion is: in, is the rate of change of the strain tensor; It is the change rate of plastic hardening coefficient of 3D printed fiber reinforced composites.

7. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 1, characterized in that: When developing the damage failure model of 3D printed fiber reinforced composites based on the maximum stress criterion in step 3, the axial failure model acts on the overall area, and the lateral failure model and shear failure model are only applied to the bonding area between the wires.

8. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 7, characterized in that: The mathematical expression of the damage failure model of the 3D printed fiber reinforced composite is: Among them, σ f1t,T , σ f1c,T are the maximum strength of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ f2t,T , σ f2c,T They are the maximum strength of the 3D printed fiber-reinforced composite filament in transverse tension and compression at temperature T, respectively; It is the maximum in-plane shear strength of 3D printed fiber-reinforced composite filament at temperature T.

9. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 1, characterized in that: The correlation equation between the elastic constant and temperature of the 3D printed fiber reinforced composite damage failure model in step 4 is: Among them, E 11 is the elastic modulus in direction 1, E 22 is the elastic modulus in two directions, G 12 is the shear modulus of the 12-plane, T is the temperature; The correlation equation between yield stress and temperature of the damage failure model of 3D printed fiber reinforced composites is: Among them, σ 1t,T , σ 1c,T are the yield stress of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ 2t,T , σ 2c,T They are the yield stress of 3D printed fiber reinforced composite filaments in transverse tension and compression at temperature T; is the in-plane shear yield stress of the 3D printed fiber-reinforced composite filament at temperature T; The correlation equation between the maximum strength and temperature of the 3D printed fiber reinforced composite damage failure model is: Among them, σ f1t,T , σ f1c,T are the maximum strength of 3D printed fiber reinforced composite filaments under axial tension and compression at temperature T; σ f2t,T , σ f2c,T They are the maximum strength of the 3D printed fiber-reinforced composite filament in transverse tension and compression at temperature T, respectively; It is the maximum in-plane shear strength of 3D printed fiber-reinforced composite filament at temperature T.

10. The method for simulating thermal constitutive damage failure of 3D printed fiber reinforced composites according to claim 1, characterized in that: The temperature change range of the temperature condition in step 5 is 23°C to 230°C.

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