A macro-micro mechanical property parameter prediction method for three-dimensional woven composite materials
By using a method to predict the macro-micro mechanical properties of three-dimensional braided composite materials, the problem of inaccurate prediction of the mechanical properties of three-dimensional braided composite materials under high strain rates is solved, enabling more efficient and accurate analysis and improving the impact resistance design of aerospace structural components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
- Filing Date
- 2023-03-08
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies struggle to accurately predict the mechanical properties of three-dimensional braided composite materials under high strain rates, leading to large errors in the design and analysis of aerospace structural components and an inability to effectively cope with the threat of impact loads.
A method for predicting the macro- and micro-mechanical properties of three-dimensional braided composite materials was adopted. Through parametric modeling, finite element analysis, and continuous damage model, considering the strain rate effect, inner cell and surface cell models were established for simulation calculation and experimental verification.
It improves the accuracy of analysis of three-dimensional braided composite materials under impact loads, reduces computational costs, and provides effective design guidance for impact resistance performance.
Smart Images
Figure CN116227034B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of aerospace structural strength and safety design, and is a method for predicting the mechanical performance parameters of three-dimensional braided composite materials used in the safety design of structural components such as aero-engine blades and casings. Background Technology
[0002] Due to the urgent need for high-performance composite materials in the aerospace field, three-dimensional weaving technology has developed rapidly since the 1980s. Three-dimensional weaving technology first weaves the reinforcing fibers of the components into a three-dimensional integral fabric (preform), and then uses resin transfer molding (RTM) to inject resin as a matrix for composite curing. The advantage of three-dimensional weaving technology is that the weaving structure is the same in the thickness direction of the material. Compared with traditional laminated composite materials, it no longer has delamination characteristics, which also makes the material have good impact resistance in the thickness direction without delamination damage. At the same time, this weaving method allows the material to be directly woven into a preform according to the size and shape of the part, achieving integral weaving. This also allows the material itself to maintain its balance while ensuring the required shape, making it suitable for mass production of complex structural components such as wide-chord fan blades for aero engines. Moreover, three-dimensional weaving technology has strong designability. By designing reasonable weaving processes, including process parameters such as weaving angle, knot height, and fiber volume fraction, the properties of the material in a certain direction can be changed, achieving the effect of adjusting the mechanical and other properties of three-dimensional woven composite materials.
[0003] Three-dimensional braided composite materials are heterogeneous and anisotropic, with complex internal braided structures, making their mechanical properties generally difficult to predict. While mesoscale models offer relatively high accuracy in impact simulations of composite materials, they involve numerous elements, complex models, high computational costs, and long processing times. Macroscale models, on the other hand, have lower computational costs and are easier to establish, but their accuracy is relatively lower due to the anisotropy and internal inhomogeneity of composite materials. Furthermore, when three-dimensional braided composite materials are used in aerospace applications, such as in aircraft engine blades and casings, they are often threatened by impact loads, such as bird / ice impacts, foreign object damage, and blade loss. Under impact loads, composite materials are in a high strain rate state, and their mechanical properties, such as modulus and strength, differ significantly from those under quasi-static conditions. Existing macro-mesoscale analysis methods cannot effectively consider the strain rate effect of materials under impact loads. Therefore, there is an urgent need for a method for impact analysis of three-dimensional braided composite material structures that balances computational efficiency, high accuracy, and the ability to consider the strain rate effect. The analytical basis for this method is a macro-mesoscale mechanical property parameter prediction method that considers the strain rate effect. Summary of the Invention
[0004] Purpose of the invention: To address the above-mentioned shortcomings, this invention provides a method for predicting the macro-micro mechanical properties of three-dimensional braided composite materials. The purpose is to solve the problem of large analysis errors caused by inaccurate descriptions of the mechanical behavior and failure of three-dimensional braided composite materials in impact analysis, which makes it difficult to effectively guide the design of engine blades and casings.
[0005] Technical Solution: To solve the above problems, the method for predicting the macro- and micro-mechanical property parameters of three-dimensional braided composite materials provided by this invention includes the following steps:
[0006] (1) Based on the internal braiding structure and fiber volume fraction of the three-dimensional four-way braided composite material, parametric modeling of the unit cell is carried out, and the inner cell model and the face cell model are established respectively.
[0007] (2) Based on the unit cell model established in step (1), a mesoscopic finite element model is established and displacement periodic boundary conditions are applied. The matrix uses the Zhu-Wang-Tang isothermal nonlinear viscoelastic constitutive material model, and the fiber bundle adopts the transverse isotropic continuous damage material model established based on the Hashin failure criterion. The same strain is applied to the unit cell at different durations using the explicit dynamic method to carry out calculations and obtain the calculation results of the periodic unit cell.
[0008] (3) Based on the calculation results of the periodic unit cell in step (2), the modulus and strength of the material in the lower cell region and inner cell region under different strain rates are obtained. The strain rate strengthening effect parameter calculation method proposed in the macroscopic continuous medium model is used to perform curve fitting on the strain rate strengthening related parameters to determine the parameter values.
[0009] (4) Apply the mechanical property parameter values and strain rate related parameter values obtained in step (3) to the three-dimensional braided composite material homogenization macroscopic model, apply periodic boundary conditions to it, extract the overall stress-strain curve, and compare it with the calculation results of the unit cell model to determine the reliability of the mechanical property prediction method.
[0010] (5) Perform macroscopic finite element modeling of the three-dimensional braided composite material plate by region; and carry out high-speed impact simulation of ice hockey through the finite element model, and verify the prediction method by conducting ice hockey impact test on the three-dimensional braided composite material plate.
[0011] Beneficial effects: The three-dimensional braided composite material damage prediction method provided by this invention starts from the perspective of micro-braided structure and considers the nonlinear mechanical characteristics of matrix material and yarn material respectively. It can more accurately predict the mechanical property parameters of materials and their strain rate correlation, improve the accuracy of analysis, and reduce the calculation cost by applying the three-dimensional braided composite material continuous damage model. It can be applied to the calculation of high strain rate problems such as impact, and provides effective assistance for the impact resistance design of composite materials for aero-engine blades and casings. Attached Figure Description
[0012] Figure 1 This is a flowchart of a method for predicting the macro- and micro-mechanical properties of three-dimensional braided composite materials.
[0013] Figure 2 This is a schematic diagram of a three-dimensional four-way braided composite material unit cell model.
[0014] Figure 3 This is a curve showing the fitting of the strain rate effect parameters.
[0015] Figure 4 This is a schematic diagram comparing the stress-strain curves of the homogenized model with those of the mesoscopic unit cell model.
[0016] Figure 5 This is a schematic diagram of the division of different regions in the macroscopic finite element model of a 5mm thick three-dimensional braided composite material flat plate.
[0017] Figure 6 This is a simulation diagram of an ice hockey puck impacting a three-dimensional woven composite material plate.
[0018] Figure 7 This is a schematic diagram of a real ice hockey puck impacting a three-dimensional woven composite material plate.
[0019] Figure 8 This is a schematic diagram of the damage morphology of a three-dimensional woven composite material plate simulated by an ice hockey impact.
[0020] Figure 9 This is a schematic diagram of the simulated damage morphology of a three-dimensional woven composite material plate impacted by a real ice hockey puck. Detailed Implementation
[0021] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.
[0022] This embodiment discloses a method for predicting the macro- and micro-mechanical property parameters of carbon fiber reinforced resin matrix composites considering the nonlinear mechanical characteristics of the matrix and yarn.
[0023] like Figure 1 As shown, this embodiment uses T700 / TDE86 carbon fiber reinforced resin-based three-dimensional four-way braided composite material as an example to disclose the specific process of the prediction method, including the following steps:
[0024] (1) Based on the internal braiding structure and fiber volume fraction of the three-dimensional four-way braided composite material, parametric modeling of the unit cell was performed using TEXGEN, and the inner cell model and the surface cell model were established respectively. Figure 2 As shown in the figure, labels 1 and 2 represent the two yarns of the face cell, label 3 represents the face cell matrix, labels 4, 5, 6, and 7 represent the four yarns of the inner cell, and label 8 represents the inner cell matrix. Based on this microscopic model, a voxel element model of the single cell is generated for subsequent finite element calculations.
[0025] (2) Apply periodic boundary conditions to the unit cell finite element model for calculation. In equation (1), u i Characterizing the displacement field, For the average strain across the entire field, x k Let u be the coordinates of a point within the field, and the first term on the right side of the equation represents the linear displacement distribution. i * It characterizes the periodic part of the displacement, but this is an unknown quantity related to the global load, so it is difficult to use in practical analysis.
[0026]
[0027] The subsequent unit cell simulation work adopts a periodic boundary condition suitable for finite element analysis of periodic unit cells, proposed based on the above-mentioned research on periodic boundary conditions. In a periodic unit cell, the boundary surfaces appear in pairs and parallel, and the two pairs of boundary surfaces are in the X-axis. j The displacement fields in the directions are as follows:
[0028]
[0029]
[0030] In the formula, j+ and j- are X j The positive and negative directions of the axis, u i Let x be the displacement field at the boundary surface. k Let u be the coordinates of a point within the boundary surface. i * For periodic displacements, due to displacement continuity, u on the two boundary surfaces... i * They are equal, therefore:
[0031]
[0032] In a hexahedral periodic unit cell, opposite sides are parallel, therefore Δx k j If it is a constant, then in a given... In this case, equation (4) can be written as:
[0033]
[0034] In the above equation, the right side is a constant. and The average elongation or shortening of the periodic unit cell corresponding to the three normal stress components. This analytical method, which addresses the shear deformation caused by the three shear stress components, is relatively easy to implement in finite element analysis software.
[0035] If we assume that the periodic unit cell is a linear orthogonal anisotropic model, then the mechanical properties of the unit cell are the same as those of the whole. Therefore:
[0036]
[0037] In the formula, and Let S be the global average strain and global average stress of the unit cell, respectively, and S be the average compliance matrix. By applying displacement boundary conditions in different directions, the mechanical property parameters of the unit cell in each direction under different strain rates can be obtained.
[0038] (3) The progressive damage model considers the effects of strain rate hardening on material modulus and strength, respectively. The formula for the strain rate hardening effect on material strength is shown in equation (7), where... Let {S0} be the initial strain rate, and {S0} be the strength under the initial strain rate state. The strain rate actually used in the calculation is {S}. RT} represents the modulus of the material at the corresponding strain rate, C rate1 The strain rate effect parameter represents the strength.
[0039]
[0040] The formula for the strain rate effect of the modulus in the material model is as shown in (8), and the specific expression of each term in the formula is as shown in formula (9). Let {E0} be the initial strain rate and {E0} be the initial modulus value. The strain rate actually used in the calculation is {E}. RT} represents the modulus of the material at the corresponding strain rate, E a E b E c G ab G bc G ca, , and represent the elastic modulus and shear modulus values of the material in different directions, respectively. E is the elastic modulus, G is the shear modulus, and C is the shear modulus. rate2 C rate3 C rate4 For strain rate effect parameters of materials with different moduli, These represent the strain rates of the material in different directions during the calculation.
[0041]
[0042]
[0043] Using the modulus and strength of the material at different strain rates obtained from the periodic unit cell calculation in step (2) as iterative data points, the modulus and strength strain rate strengthening parameters in the macroscopic continuous damage model of the three-dimensional braided composite material are iteratively calculated, for example... Figure 3 This is the iterative result of the inner cell modulus.
[0044] (4) Substitute the strain rate strengthening parameters and mechanical parameters obtained in step (3) into a homogenized finite element model with the same size as the unit cell, and calculate it using the same method as in step (2). Compare the results with those from the unit cell model. The stress-strain curve comparison diagram is shown below. Figure 4 This confirmed the reliability of this mechanical property prediction method.
[0045] (5) Perform macroscopic finite element modeling of the three-dimensional braided composite material flat plate by region, such as Figure 5 As shown in the figure, label 1' represents the face cell region, and label 2' represents the inner cell region. This model was applied to simulate high-speed impacts of ice hockey pucks, and the prediction method was validated through three-dimensional braided composite plate impact tests. Figure 6 and Figure 7 The simulation and experimental processes of ice hockey impacting composite plates are respectively presented. Figure 8 and Figure 9 To compare the damage in simulation and experiment, the comparison shows that the macroscopic model of this three-dimensional braided composite material can predict the damage of the composite material after impact well, thus verifying the reliability of the method.
[0046] This method can be extended to other forms of three-dimensional woven composite materials, such as three-dimensional five-dimensional and three-dimensional six-dimensional composites. It can also be extended to solving other impact problems, including bird strikes, hard object impacts, sand impacts, and blade fragment impacts. Beyond applications in aero-engine blades and casings, this method can be extended to other impact fields, such as aircraft fuel tanks, spacecraft protective shields, and vehicle crash barriers.
Claims
1. A method for predicting macro- and micro-mechanical property parameters of three-dimensional braided composite materials, characterized in that, Includes the following steps: (1) Based on the internal braiding structure and fiber volume fraction of the three-dimensional four-way braided composite material, parametric modeling of the unit cell is carried out, and the inner cell model and the face cell model are established respectively; (2) Based on the unit cell model established in step (1), a finite element model at the mesoscopic level is established and displacement periodic boundary conditions are applied. The matrix uses the Zhu-Wang-Tang isothermal nonlinear viscoelastic constitutive material model, and the fiber bundle adopts the transversely isotropic continuous damage material model established based on the Hashin failure criterion. The same strain is applied to the unit cell at different durations using the explicit dynamic method to carry out calculations and obtain the calculation results of the periodic unit cell. ， In the formula, and Let S be the global average strain and global average stress of the unit cell, respectively, and S be the average compliance matrix. By applying displacement boundary conditions in different directions, the mechanical property parameters of the unit cell in each direction under different strain rates are obtained. (3) Based on the calculation results of the periodic unit cell in step (2), the modulus and strength of the material in the lower cell region and inner cell region under different strain rates are obtained. The strain rate strengthening effect parameter calculation method proposed in the macroscopic continuous medium model is used to perform curve fitting on the strain rate strengthening related parameters to determine the parameter values. The formula for the strain rate strengthening effect of material strength is: , In the formula The initial strain rate, The strength at the initial strain rate state. The strain rate actually used in the calculation. This represents the modulus of the material at the corresponding strain rate. The strain rate effect parameter represents the strength. The formula for the strain rate effect of modulus in the material model is: ， The specific expressions of each term in the formula are as follows: , , ， In the formula The initial strain rate, This is the initial modulus value. The strain rate actually used in the calculation. This represents the modulus of the material at the corresponding strain rate. , , , , , , , and represent the elastic modulus and shear modulus values of the material in different directions, respectively, where E is the elastic modulus and G is the shear modulus. , , For strain rate effect parameters of materials with different moduli, These represent the strain rates of the material in different directions during the calculation; Using the modulus and strength of the material at different strain rates obtained from the periodic unit cell calculation in step (2) as iterative data points, the modulus and strength strain rate strengthening parameters in the macroscopic continuous damage model of the three-dimensional braided composite material are iteratively calculated respectively. (4) The mechanical property parameters and strain rate related parameters obtained in step (3) are substituted into the three-dimensional braided composite material homogenization macroscopic model, and periodic boundary conditions are applied to it to carry out calculations. The overall stress-strain curve is extracted and compared with the calculation results of the unit cell model to determine the reliability of the mechanical property prediction method. (5) Perform macroscopic finite element modeling of the three-dimensional braided composite plate in different regions; and conduct high-speed impact simulation of ice hockey using the finite element model, and verify the prediction method by conducting ice hockey impact test on the three-dimensional braided composite plate.