A method for analyzing macro-micro damage of composite material case containment in service environment

Abstract

The application discloses a kind of composite material casing containment macro-microscopic damage analysis methods under service environment.The application calculates the containment capacity of composite material casing, damage morphology and damage mechanism by establishing the finite element model of composite material casing impact resistance.Compared with prior art, the application solves the problem that the blade loss resistance of the matrix and interface performance inside the composite material casing under the coupling action of various environmental factors during the service process of the engine is difficult to predict, and the damage mechanism inside the casing is complex, realizes the prediction of the containment of the composite material casing under service environment and the analysis of damage mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engine casings, and in particular to a method for analyzing inclusive macro-micro damage of composite material casings under service conditions. Background Art

[0002] Traditional aircraft engine metal casings are thickened to enhance their containment capacity. However, due to weight and flight cost considerations, more and more aircraft engines are beginning to use carbon fiber composite casings. Carbon fiber composites offer high specific strength, high specific modulus, low specific gravity, strong fatigue resistance, designability, and strong impact resistance. Carbon fiber composite casings offer superior impact resistance to some metal casings. Carbon fiber reinforced composite casings can also prevent corrosion, extending their service life. The composite's low weight also increases engine efficiency.

[0003] Aircraft engines are subject to complex environmental factors during their service life, including varying dry-wet cycles during ground parking, flight, and landing, as well as high temperatures, high humidity, and salt spray during flight in coastal areas. The damage mechanisms of composite materials in these environments primarily include: matrix moisture absorption, deformation due to high- and low-temperature cycling, and salt spray corrosion, leading to defects and performance degradation. The thermal expansion coefficients of the matrix and reinforcing fibers differ; the fibers are non-hygroscopic, while the matrix has a high hygroscopic capacity. Consequently, the differential deformation between the fiber and matrix generates stress at the interface, causing damage and even debonding at the fiber / matrix interface. Research has shown that damage and destruction to the matrix and interface caused by complex environments significantly impacts the performance of composite materials. Composite casings in service also face the threat of impact loads such as blade loss and uncontained debris, making the prediction of casing containment and damage mechanism analysis quite complex. Therefore, the development of new methods for casing containment prediction and damage mechanism analysis is necessary. Summary of the Invention

[0004] Purpose of the invention: To solve the above problems, the present invention provides a method for macro-micro damage analysis of composite casing inclusions under service environment, which solves the problem that the anti-blade loss capability is difficult to predict and the internal damage mechanism of the casing is complex due to the changes in the internal matrix and interface properties of the composite casing under the separate and coupled effects of various environmental factors during engine service.

[0005] Technical solution: To achieve the above-mentioned purpose, the method for analyzing the macro-micro damage of composite casings under service environment described in the present invention comprises the following steps:

[0006] S1 establishes a corresponding environmental test chamber based on the actual service environment characteristics, designs substrate mechanical properties test pieces and interface mechanical properties test pieces, and uses the environmental test chamber to carry out corresponding environmental tests; after the environmental tests, the corresponding substrate mechanical tests and interface mechanical tests are carried out to obtain the substrate and interface material parameters before and after the environmental tests;

[0007] S2 establishes a representative volume unit finite element model of carbon fiber reinforced composite materials, and characterizes the mechanical behavior of the composite matrix after the environmental test based on the composite matrix material parameters after the S1 environmental test and the constitutive model; then, based on the composite fiber matrix interface material parameters after the S1 environmental test, the bilinear cohesive constitutive model is used to characterize the mechanical behavior of the composite fiber / matrix interface, and the transversely isotropic linear elastic constitutive model is used to characterize the mechanical behavior of the composite fiber;

[0008] S3 obtains the transverse material parameters of the composite material through a dry transverse tensile test, and then brings the dry matrix material parameters and interface material parameters into the established representative volume unit finite element model to characterize the mechanical behavior of the composite material; compares the finite element analysis results of the corresponding test conditions with the corresponding transverse material parameters of the composite material, and then calculates the material parameters of the composite material under the service environment;

[0009] S4 established a finite element model of a composite material containment casing, used the generalized three-dimensional Hashin criterion to determine the initiation of in-plane damage of the composite material, and performed a progressive reduction of the material stiffness according to the Matzenmiller damage evolution equation; used a bilinear cohesive force constitutive relationship to describe the interlaminar interface damage of the composite material, and performed a containment simulation of the composite material casing based on the composite material parameters calculated in S3; the containment capacity, damage morphology, and damage mechanism of the composite material casing after environmental testing were calculated using the finite element model.

[0010] Furthermore, the actual service environment characteristics described in S1 include the hot and humid environment in high temperature and high humidity areas and the high salt and humidity environment in coastal areas.

[0011] Furthermore, the environmental test chamber described in S1 includes water bath, moisture, salt spray and other environmental test chambers.

[0012] Furthermore, the representative volume unit finite element model of the carbon fiber reinforced composite material described in S2 includes three components: matrix, fiber, and fiber / matrix interface.

[0013] Furthermore, the matrix constitutive model described in S2 includes a linear elastic-damage constitutive model, an elastoplastic-damage constitutive model, and a Zhu-Wang-Tang nonlinear viscoelastic constitutive model.

[0014] Furthermore, the elastic-plastic-damage constitutive model includes the Von-Mises constitutive model, the Mohr-Coulomb constitutive model, and the Drucker-Prager constitutive model.

[0015] Furthermore, the dry transverse tensile test result described in S3 is obtained by conducting a 90° transverse tensile test on the composite unidirectional plate in a dry state.

[0016] Furthermore, the step of calculating the material parameters of the representative volume unit model in S3 is to apply periodic boundary conditions to the representative volume unit model, apply displacement loads to the model in various directions until the model fails, obtain the stress-strain curve in the corresponding direction, and extract the modulus E and strength S in the corresponding direction.

[0017] Furthermore, the composite material parameters in S3 include the elastic modulus E1 and the strength value X in the Z direction based on the coordinate axis. T 、X C , elastic modulus E2 and strength value Y in the X direction T , elastic modulus E3 and strength value S in the Y direction FC , shear modulus G in ZX direction 12 and intensity value S 12 , shear modulus G in the ZY direction 13 and intensity value S FS , shear modulus G in XY direction 23 and intensity value S 23 .

[0018] Furthermore, after the environmental test described in S4, the damage morphology within the composite material containing the casing after impact includes fiber tensile failure, matrix tensile failure, fiber crushing failure, and in-plane shear failure.

[0019] Beneficial effects: Compared with the existing technology, the present invention has the following significant effects: by establishing a finite element model of the composite material casing to calculate the containment capacity, damage morphology and damage mechanism of the composite material casing; using the generalized three-dimensional Hashin criterion to determine the initiation of in-plane damage of the composite material during the impact process; using the energy-based bilinear cohesive force constitutive relationship to describe the interlaminar delamination damage of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the process of the present invention.

[0021] Figure 2 This is a schematic diagram of the resin and interface mechanical properties test piece involved in the present invention.

[0022] Figure 3 This is a representative volume unit model diagram described in the present invention.

[0023] Figure 4 This is a finite element model diagram of the real composite material housing casing described in the present invention.

[0024] Figure 5 This is a diagram showing the damage form within the composite material casing after impact after the environmental test described in the present invention. DETAILED DESCRIPTION

[0025] The present invention discloses a method for analyzing the macro-micro damage of composite casings under service conditions. Figures 1 to 5 As shown, the method for analyzing the inclusive macro-micro damage of a composite material casing under a service environment provided by the present invention is further described in detail below: The method for analyzing the inclusive macro-micro damage of a composite material casing under a service environment comprises the following steps:

[0026] S1 establishes corresponding environmental test chambers (water bath, humidity, salt spray, etc.) according to the actual service environment characteristics (hot and humid environment in high temperature and high humidity areas, high salt and humidity environment in coastal areas, etc.), and designs resin matrix mechanical properties test pieces and interface mechanical properties test pieces such as Figure 2 As shown, the corresponding environmental tests are carried out. After the environmental tests, the corresponding resin matrix and interface mechanical tests are carried out to obtain the material parameters of the resin matrix and interface mechanical properties before and after the environmental tests;

[0027] S2 uses the random distribution algorithm of Python language to establish a representative volume unit finite element model of carbon fiber reinforced resin matrix composite materials in ABAQUS finite element software. The model includes three components: matrix, fiber and fiber / matrix interface, such as Figure 3 As shown in Figure 1; Based on the resin matrix material parameters after the environmental test obtained in S1, combined with specific constitutive models, such as the linear elastic-damage constitutive model, the elastoplastic-damage constitutive model (Von-Mises constitutive model, the Mohr-Coulomb constitutive model and the Drucker-Prager constitutive model) and the Zhu-Wang-Tang (ZWT) nonlinear viscoelastic constitutive model, the mechanical behavior of the resin matrix after the environmental test is characterized; Based on the resin fiber matrix interface material parameters after the environmental test obtained in S1, the bilinear cohesive force constitutive model is used to characterize the mechanical behavior of the resin fiber matrix interface after the environmental test, and the transversely isotropic linear elastic constitutive model is used to characterize the mechanical behavior of the resin fiber;

[0028] S3 carried out a 90° transverse tensile test on a composite unidirectional plate in a dry state to obtain the elastic modulus parameters and transverse tensile strength values, and substituted the dry matrix and interface material parameters into the established micro-representative volume unit model; performed a finite element analysis of the corresponding test conditions in ABAQUS finite element software to obtain the transverse material parameters of the composite material corresponding to the test, and compared them with the test results to show the effectiveness of the representative volume unit model; then calculated the composite material parameters under the service environment, including Figure 3 The elastic modulus E1 and strength value X in the Z direction based on the coordinate axis T 、X C , elastic modulus E2 and strength value Y in the X direction T , elastic modulus E3 and strength value S in the Y direction FC , shear modulus G in ZX direction 12 and intensity value S 12 , shear modulus G in the ZY direction 13 and intensity value S FS , shear modulus G in XY direction 23 and intensity value S 23 The steps for calculating the material parameters of the representative volume unit model are to apply periodic boundary conditions to the representative volume unit model in the ABAQUS finite element software, then apply displacement loads to the model in each direction until the model fails, obtain the stress-strain curve in the corresponding direction, and extract the modulus E and strength S in the corresponding direction.

[0029] S4 establishes a finite element model of the composite material containing casing. Figure 4 As shown in the figure, the initiation of in-plane damage of the composite material is determined by the generalized three-dimensional Hashin criterion, and the progressive reduction of the material stiffness is performed according to the damage evolution equation proposed by Matzenmiller. The bilinear cohesive constitutive relationship is used to describe the interlaminar interface damage of the composite material, and the mechanical properties of the composite material calculated in S3 are input to perform the containment simulation of the composite material casing. After calculation, the containment capacity, damage morphology and damage mechanism of the composite material casing after environmental testing can be obtained, among which, as shown in the figure, Figure 5 As shown, the damage morphology includes fiber tensile failure, collective tensile failure, fiber crush failure, and in-plane shear failure; the comparison between the residual velocity of the projectile after the environmental test and the residual velocity of the projectile obtained by the test is shown in Table 1. The error results between the two are shown to be 5.5%, which meets the requirement of less than 10%, thereby verifying the effectiveness of the patent solution.

[0030]

[0031] Table 1

Claims

1. A method for analyzing the macro-micro damage of composite casings under service conditions, characterized by: The following steps are involved: S1 establishes a corresponding environmental test chamber based on the actual service environment characteristics, designs substrate mechanical properties test pieces and interface mechanical properties test pieces, and uses the environmental test chamber to carry out corresponding environmental tests; after the environmental tests, the corresponding substrate mechanical tests and interface mechanical tests are carried out to obtain the substrate and interface material parameters before and after the environmental tests; S2 establishes a representative volume unit finite element model of carbon fiber reinforced composite materials, and characterizes the mechanical behavior of the composite matrix after the environmental test based on the composite matrix material parameters after the S1 environmental test and the constitutive model; then, based on the composite fiber matrix interface material parameters after the S1 environmental test, the bilinear cohesive constitutive model is used to characterize the mechanical behavior of the composite fiber / matrix interface, and the transversely isotropic linear elastic constitutive model is used to characterize the mechanical behavior of the composite fiber; S3 obtains the transverse material parameters of the composite material through dry transverse tensile test, and then brings the dry matrix material parameters and interface material parameters into the established representative volume unit finite element model to characterize the mechanical behavior of the composite material; Compare the finite element analysis results of the corresponding test conditions with the corresponding lateral material parameters of the composite material, and then calculate the material parameters of the composite material under the service environment; S4 establishes a finite element model of a composite material containment casing, uses the generalized three-dimensional Hashin criterion to determine the onset of in-plane damage in the composite material, and performs a progressive reduction of the material stiffness according to the Matzenmiller damage evolution equation. A bilinear cohesive constitutive relation is used to describe the interlaminar interface damage of the composite material, and the containment simulation of the composite material casing is performed based on the composite material parameters calculated in S3. The containment capacity, damage morphology and damage mechanism of the composite material casing after environmental testing were obtained through finite element model calculation.

2. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1 is characterized in that: The actual service environment characteristics described in S1 include the hot and humid environment in high temperature and high humidity areas and the high salt and humid environment in coastal areas.

3. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1 is characterized in that: The environmental test chambers described in S1 include water bath, humidity, salt spray and other environmental test chambers.

4. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1, characterized in that: The representative volume unit finite element model of the carbon fiber reinforced composite material described in S2 includes three components: matrix, fiber, and fiber / matrix interface.

5. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1 is characterized in that: The matrix constitutive models described in S2 include the linear elastic-damage constitutive model, the elastoplastic-damage constitutive model, and the Zhu-Wang-Tang nonlinear viscoelastic constitutive model.

6. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1, characterized in that: The elastic-plastic-damage constitutive model includes the Von-Mises constitutive model, the Mohr-Coulomb constitutive model, and the Drucker-Prager constitutive model.

7. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1, characterized in that: The dry transverse tensile test results described in S3 are obtained by conducting a 90° transverse tensile test on the composite unidirectional plate in a dry state.

8. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1, characterized in that: The steps for calculating the material parameters of the representative volume unit model described in S3 are to apply periodic boundary conditions to the representative volume unit model, apply displacement loads to the model in various directions until the model fails, obtain the stress-strain curve in the corresponding direction, and extract the modulus E and strength S in the corresponding direction.

9. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1, characterized in that: The composite material parameters in S3 include the elastic modulus E1 and strength value X in the Z direction based on the coordinate axis. T 、X C , elastic modulus E2 and strength value Y in the X direction T , elastic modulus E3 and strength value S in the Y direction FC , shear modulus G in ZX direction 12 and intensity value S 12 , shear modulus G in the ZY direction 13 and intensity value S FS , shear modulus G in XY direction 23 and intensity value S 23 .

10. The method for analyzing the macro-micro damage of composite casings under service conditions according to claim 1, characterized in that: After the environmental test described in S4, the damage morphology of the composite material containing the casing after impact includes fiber tensile failure, matrix tensile failure, fiber crushing failure, and in-plane shear failure.

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