A woven ceramic matrix composite sub-crack opening displacement prediction method and system

Abstract

The application discloses a woven ceramic matrix composite sub-crack opening displacement prediction method and system, and comprises the following steps: obtaining the micro stress field of the woven ceramic matrix composite sub-crack by using the micro mechanics method according to the material parameters of the woven ceramic matrix composite; obtaining the axial displacement of the fiber and the matrix in the interface debonding area range by using the axial displacement calculation method according to the micro stress field of the woven ceramic matrix composite sub-crack; obtaining the interface debonding length of the woven ceramic matrix composite sub-crack by using the fracture mechanics method according to the axial displacement of the fiber and the matrix in the interface debonding area range; and obtaining the woven ceramic matrix composite sub-crack opening displacement according to the interface debonding length and the axial displacement of the fiber and the matrix in the interface debonding area range. The application can improve the precision of the woven ceramic matrix composite sub-crack opening displacement prediction result, ensure the high-temperature environment use reliability and safety of the ceramic matrix composite structure, and has low cost.

Description

Technical Field

[0001] This invention relates to the field of composite material crack opening displacement prediction technology, and in particular to a method and system for predicting secondary crack opening displacement in braided ceramic matrix composite materials. Background Technology

[0002] Ceramic matrix composites possess advantages such as high temperature resistance, corrosion resistance, low density, high specific strength, and high specific modulus. Compared to high-temperature alloys, they can withstand higher temperatures, reduce cooling airflow, and improve turbine efficiency. They are currently used in aero-engine combustion chambers, turbine guide vanes, turbine casing rings, and exhaust nozzles. The LEAP (Leading Edge Aviation Propulsion) series engines developed by CFM International utilize braided ceramic matrix composite components in their high-pressure turbines. The LEAP-1B engine powers the Airbus A320 and Boeing 737 MAX, while the LEAP-X1C engine is the sole power plant selected for China's large aircraft, the C919.

[0003] To ensure the reliability and safety of braided ceramic matrix composites (CMCs) in aircraft and aero-engine structures, the Federal Aviation Administration (FAA) considers the development of CMC performance evaluation, damage evolution, strength, and life prediction tools as crucial for the airworthiness certification of CMC structural components. To ensure the reliability and safety of CMC structures during use, in-depth research on crack opening displacement under load is necessary. Secondary cracks, which form in axially laid layers, will propagate under load, leading to a decline in the composite's modulus and strength. At high temperatures, oxidizing gases will enter the composite through secondary cracks, oxidizing the interface phase and fibers. Establishing a method for predicting the secondary crack opening displacement of braided CMCs is a prerequisite for ensuring the reliability and safety of CMC structural components in high-temperature environments.

[0004] Existing technologies rely on experimental prediction of secondary crack opening displacement in woven ceramic matrix composites. However, due to the small scale of secondary crack opening displacement, obtaining it through experiments is costly and has low accuracy. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for predicting the secondary crack opening displacement of braided ceramic matrix composites, which can improve the accuracy of the prediction results of secondary crack opening displacement of braided ceramic matrix composites, ensure the reliability and safety of ceramic matrix composite structural components in high-temperature environments, and is low in cost.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for predicting the secondary crack opening displacement in braided ceramic matrix composites, the method comprising:

[0008] Obtain the material parameters of the woven ceramic matrix composite material; the material parameters include fiber material parameters and matrix material parameters;

[0009] Based on the material parameters, a micromechanical method was used to obtain the micro-stress field of secondary cracks in the braided ceramic matrix composite material. The micro-stress field of secondary cracks in the braided ceramic matrix composite material includes the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage, and the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage. The axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage includes the axial stress distribution of the fibers in the interfacial debonding zone and the interfacial bonding zone. The axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage includes the axial stress distribution of the matrix in the interfacial debonding zone and the interfacial bonding zone.

[0010] Based on the microscopic stress field of the secondary crack in the braided ceramic matrix composite material, the axial displacement of the fiber and the axial displacement of the matrix within the interface debonding zone are obtained by axial displacement calculation method.

[0011] The interface debonding length of the secondary crack in the braided ceramic matrix composite material is obtained by fracture mechanics method based on the axial displacement of the fiber within the interface debonding zone and the axial displacement of the matrix within the interface debonding zone.

[0012] The opening displacement of the secondary crack in the woven ceramic matrix composite material is obtained based on the interfacial debonding length of the secondary crack, the axial displacement of the fiber within the interfacial debonding zone, and the axial displacement of the matrix within the interfacial debonding zone.

[0013] Optionally, obtaining the micro-stress field of the braided ceramic matrix composite material exhibiting secondary cracks using micromechanical methods based on the material parameters specifically includes:

[0014] Based on the fiber material parameters, the formula is used. Calculate the axial micro-stress field σ of fibers in composite materials after matrix cracking and interfacial debonding damage. f (x); where V f η is the fiber volume content, σ is the external stress, and η is the ratio of axial yarn thickness to the thickness of both axial and transverse yarns. to τ represents the axial stress of the transverse yarn in the bonding zone, γ is the ratio of the axial to the transverse yarn thickness, and τ is the axial stress of the transverse yarn. i For the interfacial shear stress, r f L represents the fiber radius, x represents the fiber axial coordinate, and L represents the fiber radius. d σ is the interfacial debonding length of secondary cracks in woven ceramic matrix composites. foρ represents the axial stress of the fiber in the interfacial bonding zone, ρ is the shear lag model parameter, and L is the shear stress. c The distance between matrix cracks;

[0015] Based on the matrix material parameters, the formula is used. Calculate the axial micro-stress field σ of the matrix after matrix cracking and interfacial debonding damage in the composite material. m (x); where V m σ is the matrix volume content. mo This indicates the stress in the bonding zone at the matrix interface.

[0016] Optionally, the step of calculating the axial displacement of the fibers and the matrix within the interface debonding zone based on the microscopic stress field of the secondary crack in the braided ceramic matrix composite material using an axial displacement calculation method specifically includes:

[0017] Based on the axial microscopic stress field of the fibers after matrix cracking and interfacial debonding damage in the composite material, the formula is used. Calculate the axial displacement Ψ of the fiber within the debonding zone of the interface. AFD (x); where E f E represents the fiber's elastic modulus. c Indicates the elastic modulus of a composite material;

[0018] Based on the axial microscopic stress field of the matrix after matrix cracking and interfacial debonding damage in the composite material, the formula is used. Calculate the axial displacement Ψ of the matrix within the debonding zone of the interface. AMD (x); where E m This represents the elastic modulus of the matrix.

[0019] Optionally, the step of obtaining the interfacial debonding length of the secondary crack in the braided ceramic matrix composite material using fracture mechanics methods based on the axial displacement of the fibers within the interfacial debonding zone and the axial displacement of the matrix within the interfacial debonding zone specifically includes:

[0020] The axial displacement Ψ of the fibers within the debonding zone of the interface AFD (x) and the axial displacement Ψ of the substrate within the debonding zone of the interface. AMD Calculate the fiber displacement U(x) relative to the matrix by subtracting (x);

[0021] Based on the fiber's relative displacement to the matrix U(x) and the fiber's axial displacement Ψ within the interface debonding zone... AFD (x), using the formula Calculate the interfacial debonding length L of secondary cracks in braided ceramic matrix composites d In the formula, Γ iFor interfacial debonding energy, F represents the load borne by the fiber in the matrix crack plane, and Ψ represents the debonding energy. AFD (x=0) represents the axial displacement of the fiber in the matrix crack plane.

[0022] Optionally, obtaining the secondary crack opening displacement of the braided ceramic matrix composite material based on the interfacial debonding length of the secondary crack, the axial displacement of the fibers within the interfacial debonding zone, and the axial displacement of the matrix within the interfacial debonding zone specifically includes:

[0023] According to the interface debonding length L of the secondary crack in the woven ceramic matrix composite material d The fiber's displacement relative to the matrix, U(x), is expressed using the formula... Calculate the secondary crack opening displacement Ψ in braided ceramic matrix composites COD In the formula, E1 represents the elastic modulus of the composite material along the fiber direction.

[0024] The present invention also provides the following solutions:

[0025] A secondary crack opening displacement prediction system for braided ceramic matrix composites, the system comprising:

[0026] A material parameter acquisition module is used to acquire the material parameters of the woven ceramic matrix composite material; the material parameters include fiber material parameters and matrix material parameters.

[0027] The module for obtaining the micro-stress field of secondary cracks is used to obtain the micro-stress field of secondary cracks in braided ceramic matrix composites using micromechanical methods based on the material parameters. The micro-stress field of secondary cracks in the braided ceramic matrix composite includes the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage, and the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage. The axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage includes the axial stress distribution of the fibers in the interfacial debonding zone and the interfacial bonding zone. The axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage includes the axial stress distribution of the matrix in the interfacial debonding zone and the interfacial bonding zone.

[0028] The axial displacement module of the fiber and the matrix is ​​used to calculate the axial displacement of the fiber and the axial displacement of the matrix within the interface debonding zone based on the micro-stress field of the secondary crack in the woven ceramic matrix composite material.

[0029] The interface debonding length obtaining module is used to obtain the interface debonding length of the secondary crack in the braided ceramic matrix composite material by means of fracture mechanics based on the axial displacement of the fiber within the interface debonding zone and the axial displacement of the matrix within the interface debonding zone.

[0030] The secondary crack opening displacement acquisition module is used to obtain the secondary crack opening displacement of the braided ceramic matrix composite material based on the interface debonding length of the secondary crack, the axial displacement of the fiber within the interface debonding zone, and the axial displacement of the matrix within the interface debonding zone.

[0031] Optionally, the module for obtaining the mesoscopic stress field of the secondary crack specifically includes:

[0032] The axial micro-stress field calculation unit for the fiber is used to calculate the fiber material parameters using the formula... Calculate the axial micro-stress field σ of fibers in composite materials after matrix cracking and interfacial debonding damage. f (x); where V f η is the fiber volume content, σ is the external stress, and η is the ratio of axial yarn thickness to the thickness of both axial and transverse yarns. to τ represents the axial stress of the transverse yarn in the bonding zone, γ is the ratio of the axial to the transverse yarn thickness, and τ is the axial stress of the transverse yarn. i For the interfacial shear stress, r f L represents the fiber radius, x represents the fiber axial coordinate, and L represents the fiber radius. d σ is the interfacial debonding length of secondary cracks in woven ceramic matrix composites. fo ρ represents the axial stress of the fiber in the interfacial bonding zone, ρ is the shear lag model parameter, and L is the shear stress. c The distance between matrix cracks;

[0033] The axial micro-stress field calculation unit of the matrix is ​​used to calculate the matrix material parameters using the formula... Calculate the axial micro-stress field σ of the matrix after matrix cracking and interfacial debonding damage in the composite material. m (x); where V m σ is the matrix volume content. mo This indicates the stress in the bonding zone at the matrix interface.

[0034] Optionally, the module for obtaining the axial displacement of the fiber and the matrix specifically includes:

[0035] The fiber axial displacement calculation unit is used to calculate the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage in the composite material, using the formula... Calculate the axial displacement Ψ of the fiber within the debonding zone of the interface. AFD (x); where E f E represents the fiber's elastic modulus. c Indicates the elastic modulus of a composite material;

[0036] The matrix axial displacement calculation unit is used to calculate the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage in the composite material, using the formula... Calculate the axial displacement Ψ of the matrix within the debonding zone of the interface. AMD (x); where E m This represents the elastic modulus of the matrix.

[0037] Optionally, the module for obtaining the interface debonding length specifically includes:

[0038] The fiber-matrix displacement calculation unit is used to calculate the axial displacement Ψ of the fibers within the debonding zone of the interface. AFD (x) and the axial displacement Ψ of the substrate within the debonding zone of the interface. AMD Calculate the fiber displacement U(x) relative to the matrix by subtracting (x);

[0039] The interface debonding length calculation unit is used to calculate the fiber's displacement relative to the matrix U(x) and the axial displacement Ψ of the fiber within the interface debonding zone. AFD (x), using the formula Calculate the interfacial debonding length L of secondary cracks in braided ceramic matrix composites d In the formula, Γ i For interfacial debonding energy, F represents the load borne by the fiber in the matrix crack plane, and Ψ represents the debonding energy. AFD (x=0) represents the axial displacement of the fiber in the matrix crack plane.

[0040] Optionally, the module for obtaining the secondary crack opening displacement specifically includes:

[0041] The secondary crack opening displacement calculation unit is used to calculate the interface debonding length L of the secondary crack in the woven ceramic matrix composite material. d The fiber's displacement relative to the matrix, U(x), is expressed using the formula... Calculate the secondary crack opening displacement Ψ in braided ceramic matrix composites COD In the formula, E1 represents the elastic modulus of the composite material along the fiber direction.

[0042] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0043] This invention discloses a method and system for predicting the secondary crack opening displacement of braided ceramic matrix composites. It employs micromechanics to obtain the microscopic stress field of the secondary crack in the braided ceramic matrix composite. Based on this microscopic stress field, it uses axial displacement calculation to obtain the axial displacement of the fibers and the matrix within the interface debonding zone. Then, based on these axial displacements, it uses fracture mechanics to obtain the interface debonding length of the secondary crack. Finally, based on the interface debonding length, the axial displacements of the fibers and the matrix within the interface debonding zone, it obtains the secondary crack opening displacement. This method predicts the secondary crack opening displacement of braided ceramic matrix composites through these steps, avoiding the need for experimental predictions. This improves the accuracy of the predicted results, ensuring the reliability and safety of ceramic matrix composite structural components in high-temperature environments, and is cost-effective. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a flowchart illustrating an embodiment of the method for predicting the secondary crack opening displacement in woven ceramic matrix composites according to the present invention;

[0046] Figure 2 A schematic diagram of secondary cracks in a woven ceramic matrix composite material;

[0047] Figure 3 A comparison diagram of the experimental and predicted secondary crack opening displacements in braided ceramic matrix composites;

[0048] Figure 4 This is a structural diagram of an embodiment of the woven ceramic matrix composite secondary crack opening displacement prediction system of the present invention. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The purpose of this invention is to provide a method and system for predicting the secondary crack opening displacement of braided ceramic matrix composites, which can improve the accuracy of the prediction results of secondary crack opening displacement of braided ceramic matrix composites, ensure the reliability and safety of ceramic matrix composite structural components in high-temperature environments, and is low in cost.

[0051] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Figure 1 This is a flowchart illustrating an embodiment of the method for predicting the secondary crack opening displacement in woven ceramic matrix composites according to the present invention. See also... Figure 1 The method for predicting the secondary crack opening displacement of the braided ceramic matrix composite material includes:

[0053] Step 101: Obtain the material parameters of the braided ceramic matrix composite material; the material parameters include fiber material parameters and matrix material parameters.

[0054] Step 101 requires obtaining basic material properties of the woven ceramic matrix composite, such as fiber volume content and fiber elastic modulus.

[0055] Step 102: Based on the material parameters, the micro-stress field of the braided ceramic matrix composite material with secondary cracks is obtained using micromechanical methods. The micro-stress field of the braided ceramic matrix composite material with secondary cracks includes the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage, and the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage. The axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage includes the axial stress distribution of the fibers in the interfacial debonding zone and the interfacial bonding zone. The axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage includes the axial stress distribution of the matrix in the interfacial debonding zone and the interfacial bonding zone.

[0056] Step 102 specifically includes:

[0057] Based on the fiber material parameters, the formula is used. Calculate the axial micro-stress field σ of fibers in composite materials after matrix cracking and interfacial debonding damage. f (x); where V f η is the fiber volume content, σ is the external stress, and η is the ratio of axial yarn thickness to the thickness of both axial and transverse yarns. to τ represents the axial stress of the transverse yarn in the bonding zone, γ is the ratio of the axial to the transverse yarn thickness, and τ is the axial stress of the transverse yarn. i For the interfacial shear stress, r f L represents the fiber radius, x represents the fiber axial coordinate, and L represents the fiber radius. dσ is the interfacial debonding length of secondary cracks in woven ceramic matrix composites. fo ρ represents the axial stress of the fiber in the interfacial bonding zone, ρ is the shear lag model parameter, and L is the shear stress. c The distance between cracks in the matrix is ​​denoted as .

[0058] Based on the matrix material parameters, the formula is used. Calculate the axial micro-stress field σ of the matrix after matrix cracking and interfacial debonding damage in the composite material. m (x); where V m σ is the matrix volume content. mo This indicates the stress in the bonding zone at the matrix interface.

[0059] This refers to the composite material experiencing matrix cracking followed by interfacial debonding damage. Specifically, the composite material first undergoes matrix cracking, then interfacial debonding damage (the composite material sequentially experiences matrix cracking and interfacial debonding damage). The axial mesoscopic stress field of the fibers after matrix cracking and interfacial debonding damage is also described. Finally, the axial mesoscopic stress field of the matrix after matrix cracking and interfacial debonding damage is also described.

[0060] In step 102, the stress field of the secondary crack in the braided ceramic matrix composite material (i.e., the micro-stress field of the fiber and the matrix) is obtained using a micromechanical method (i.e., the shear lag method):

[0061]

[0062]

[0063] In the formula, σ f (x) represents the mesoscopic stress field of the fiber, σ m (x) represents the microscopic stress field of the matrix, σ represents the external stress, and V represents the microscopic stress field of the matrix. f V is the fiber volume content. m r represents the matrix volume content. f Where τ is the fiber radius i For the interfacial shear stress, L d L is the interface debonding length (used to calculate the stress field of the secondary crack in the braided ceramic matrix composite in step 102). c σ represents the matrix crack spacing. fo η represents the axial stress of the fiber in the interfacial bonding zone, η is the ratio of the axial yarn thickness to the thickness of both the axial and transverse yarns, γ is the ratio of the axial to the transverse yarn thickness, ρ is the shear lag model parameter, and σ is the shear lag model parameter. to σ represents the axial stress of the transverse yarn in the bonding area. t (x) represents the axial stress of the transverse yarn, σ t (x)=σto , x represents the fiber axial coordinate, σ mo This indicates the stress in the bonding zone at the matrix interface.

[0064] Step 103: Based on the microscopic stress field of secondary cracks in the braided ceramic matrix composite material, the axial displacement of the fibers and the matrix within the interface debonding zone are obtained using the axial displacement calculation method.

[0065] Step 103 specifically includes:

[0066] Based on the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage in composite materials, the formula is used. Calculate the axial displacement Ψ of the fiber within the debonding zone of the interface. AFD (x); where E f E represents the fiber's elastic modulus. c This indicates the elastic modulus of the composite material.

[0067] Based on the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage in composite materials, the formula is used. Calculate the axial displacement Ψ of the matrix within the debonding zone of the interface. AMD (x); where E m This represents the elastic modulus of the matrix.

[0068] In step 103, the axial displacement of the fiber and the matrix is ​​obtained using an axial displacement calculation method, that is, based on the microscopic stress field of the fiber and the matrix, the axial displacement of the fiber and the matrix is ​​obtained:

[0069]

[0070]

[0071] Step 104: Based on the axial displacement of the fibers and the axial displacement of the matrix within the interface debonding zone, the interface debonding length of the secondary crack in the braided ceramic matrix composite material is obtained using fracture mechanics methods.

[0072] Step 104 specifically includes:

[0073] Axial displacement Ψ of fibers within the debonding zone of the interface AFD (x) and the axial displacement Ψ of the matrix within the interface debonding zone. AMD (x) is subtracted to calculate the fiber displacement U(x) relative to the matrix.

[0074] Based on the fiber's relative displacement to the matrix U(x) and the fiber's axial displacement Ψ within the interfacial debonding zone... AFD (x), using the formula Calculate the interfacial debonding length L of secondary cracks in braided ceramic matrix composites d In the formula, Γ i For interfacial debonding energy, F represents the load borne by the fiber in the matrix crack plane, and Ψ represents the debonding energy. AFD (x=0) represents the axial displacement of the fiber in the matrix crack plane.

[0075] In step 104, the interface debonding length of the secondary crack is obtained using fracture mechanics methods. The fracture mechanics interface debonding criterion (fracture mechanics method) is as follows:

[0076]

[0077] In the formula, Γ i Ψ represents the interfacial debonding energy (an interfacial debonding energy is a parameter used to calculate the interfacial debonding length), F represents the load borne by the fiber in the matrix crack plane, and Ψ represents the interfacial debonding energy. AFD (x=0) represents the axial displacement of the fiber in the matrix crack plane, and U(x) represents the displacement of the fiber relative to the matrix.

[0078] The interfacial debonding length is obtained by substituting the fiber axial displacement (axial displacement of the fiber) and relative displacement (displacement of the fiber relative to the matrix) into the fracture mechanics interfacial debonding criterion. Calculate the debonding length at the interface.

[0079]

[0080]

[0081] In the formula, E f E represents the fiber's elastic modulus. c E1 represents the elastic modulus of the composite material, and E represents the elastic modulus of the composite material along the fiber direction. m This represents the elastic modulus of the matrix.

[0082] Ψ AFD Substituting (x=0) and U(x) into the fracture mechanics interface debonding criterion, we obtain the interface debonding length as:

[0083]

[0084] Step 105: Based on the interfacial debonding length of the secondary crack in the braided ceramic matrix composite material, the axial displacement of the fiber within the interfacial debonding zone, and the axial displacement of the matrix within the interfacial debonding zone, the opening displacement of the secondary crack in the braided ceramic matrix composite material is obtained.

[0085] Step 105 specifically includes:

[0086] Based on the interfacial debonding length L of the secondary crack in the braided ceramic matrix composite material d The fiber-matrix displacement U(x) is expressed by the formula... Calculate the secondary crack opening displacement Ψ in braided ceramic matrix composites COD In the formula, E1 represents the elastic modulus of the composite material along the fiber direction.

[0087] In step 105, based on the axial displacement difference between the fiber and the matrix (fiber displacement relative to the matrix), the opening displacement of the matrix crack plane (secondary crack opening displacement of the braided ceramic matrix composite) is obtained. The opening displacement of the matrix crack plane is:

[0088]

[0089] The method for predicting the secondary crack opening displacement of woven ceramic matrix composites using the present invention can be applied to predict, for example, Figure 2 The diagram shows the opening displacement of a secondary crack in a braided ceramic matrix composite material (braided ceramic matrix composite secondary crack opening displacement). The specific material property values ​​for the braided ceramic matrix composite material are: V f =0.3, r f =7.5μm, E f =350GPa, E m =400GPa, fiber thermal expansion coefficient α f =4.5×10 -6 / ℃, coefficient of thermal expansion of the matrix α m =4.6×10 -6 / ℃, the difference between the test temperature and the preparation temperature ΔT=-1000℃, τ i =25MPa,Γ i =0.5J / m 2 Meanwhile, based on experimental results, such as... Figure 2 The opening displacement of secondary cracks in the braided ceramic matrix composite material shown is compared with experimental data and the prediction results obtained by applying the prediction method for the opening displacement of secondary cracks in braided ceramic matrix composite materials of this invention, as follows: Figure 3 The image shows a comparison of the experimental and predicted secondary crack opening displacements in braided ceramic matrix composites. Figure 3 As can be seen, compared with the experiment, the secondary crack opening displacement prediction method of the woven ceramic matrix composite material of the present invention can accurately obtain the secondary crack opening displacement of the woven ceramic matrix composite material.

[0090] This invention addresses the shortcomings of existing technologies that predict the secondary crack opening displacement of woven ceramic matrix composites based on experiments. Due to the small scale of the crack opening displacement, experiments struggle to accurately obtain the displacement. This invention proposes a method for predicting the secondary crack opening displacement of woven ceramic matrix composites, solving the problem of inaccurate monitoring of this displacement in existing technologies. This method first uses micromechanics to obtain the stress field of the secondary crack in the woven ceramic matrix composite. Then, it uses fracture mechanics to obtain the interfacial debonding length of the secondary crack. Next, it uses axial displacement calculation methods to obtain the axial displacements of the fiber and matrix respectively. Finally, based on the difference in axial displacements between the fiber and matrix, it obtains the crack opening displacement in the matrix. Compared to existing technologies, this invention can accurately obtain the secondary crack opening displacement of woven ceramic matrix composites.

[0091] Figure 4 This is a structural diagram of an embodiment of the secondary crack opening displacement prediction system for woven ceramic matrix composites according to the present invention. See also... Figure 4 The secondary crack opening displacement prediction system for braided ceramic matrix composites includes:

[0092] The material parameter acquisition module 401 is used to acquire the material parameters of the woven ceramic matrix composite material; the material parameters include fiber material parameters and matrix material parameters.

[0093] The module 402 for obtaining the micro-stress field of secondary cracks is used to obtain the micro-stress field of secondary cracks in braided ceramic matrix composites using micromechanical methods based on material parameters. The micro-stress field of secondary cracks in braided ceramic matrix composites includes the axial micro-stress field of fibers after matrix cracking and interfacial debonding damage, and the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage. The axial micro-stress field of fibers after matrix cracking and interfacial debonding damage includes the axial stress distribution of fibers in the interfacial debonding zone and the interfacial bonding zone. The axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage includes the axial stress distribution of the matrix in the interfacial debonding zone and the interfacial bonding zone.

[0094] The microscopic stress field of this crack is obtained by module 402, which specifically includes:

[0095] The axial micro-stress field calculation unit for fibers is used to calculate the axial micro-stress field based on fiber material parameters using formulas. Calculate the axial micro-stress field σ of fibers in composite materials after matrix cracking and interfacial debonding damage. f (x); where V f η is the fiber volume content, σ is the external stress, and η is the ratio of axial yarn thickness to the thickness of both axial and transverse yarns. toτ represents the axial stress of the transverse yarn in the bonding zone, γ is the ratio of the axial to the transverse yarn thickness, and τ is the axial stress of the transverse yarn. i For the interfacial shear stress, r f L represents the fiber radius, x represents the fiber axial coordinate, and L represents the fiber radius. d σ is the interfacial debonding length of secondary cracks in woven ceramic matrix composites. fo ρ represents the axial stress of the fiber in the interfacial bonding zone, ρ is the shear lag model parameter, and L is the shear stress. c The distance between cracks in the matrix is ​​denoted as .

[0096] The axial micro-stress field calculation unit of the matrix is ​​used to calculate the matrix material parameters using formulas. Calculate the axial micro-stress field σ of the matrix after matrix cracking and interfacial debonding damage in the composite material. m (x); where V m σ is the matrix volume content. mo This indicates the stress in the bonding zone at the matrix interface.

[0097] The axial displacement of the fiber and the matrix is ​​obtained by module 403, which is used to calculate the axial displacement of the fiber and the axial displacement of the matrix within the interface debonding zone based on the micro-stress field of the secondary crack in the woven ceramic matrix composite material.

[0098] The axial displacement of the fiber and the matrix is ​​achieved by module 403, which specifically includes:

[0099] The fiber axial displacement calculation unit is used to calculate the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage in the composite material, using the formula... Calculate the axial displacement Ψ of the fiber within the debonding zone of the interface. AFD (x); where E f E represents the fiber's elastic modulus. c This indicates the elastic modulus of the composite material.

[0100] The matrix axial displacement calculation unit is used to calculate the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage in the composite material, using the formula... Calculate the axial displacement Ψ of the matrix within the debonding zone of the interface. AMD (x); where E m This represents the elastic modulus of the matrix.

[0101] The interface debonding length acquisition module 404 is used to obtain the interface debonding length of the secondary crack in the braided ceramic matrix composite material by means of fracture mechanics based on the axial displacement of the fiber and the axial displacement of the matrix within the interface debonding zone.

[0102] The interface debonding length is obtained by module 404, which specifically includes:

[0103] The fiber-matrix displacement calculation unit is used to calculate the axial displacement Ψ of the fiber within the debonding zone of the interface. AFD (x) and the axial displacement Ψ of the matrix within the interface debonding zone. AMD (x) is subtracted to calculate the fiber displacement U(x) relative to the matrix.

[0104] The interface debonding length calculation unit is used to calculate the fiber-matrix displacement U(x) and the axial displacement Ψ of the fiber within the interface debonding zone. AFD (x), using the formula Calculate the interfacial debonding length L of secondary cracks in braided ceramic matrix composites d In the formula, Γ i For interfacial debonding energy, F represents the load borne by the fiber in the matrix crack plane, and Ψ represents the debonding energy. AFD (x=0) represents the axial displacement of the fiber in the matrix crack plane.

[0105] The secondary crack opening displacement acquisition module 405 is used to obtain the secondary crack opening displacement of the braided ceramic matrix composite material based on the interface debonding length of the secondary crack, the axial displacement of the fiber within the interface debonding zone, and the axial displacement of the matrix within the interface debonding zone.

[0106] The crack opening displacement obtained by module 405 specifically includes:

[0107] The secondary crack opening displacement calculation unit is used to calculate the interfacial debonding length L of the secondary crack in the braided ceramic matrix composite material. d The fiber-matrix displacement U(x) is expressed by the formula... Calculate the secondary crack opening displacement Ψ in braided ceramic matrix composites COD In the formula, E1 represents the elastic modulus of the composite material along the fiber direction.

[0108] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0109] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for predicting the secondary crack opening displacement in woven ceramic matrix composites, characterized in that, The method includes: Obtain the material parameters of the woven ceramic matrix composite material; the material parameters include fiber material parameters and matrix material parameters; Based on the material parameters, a micromechanical method is used to obtain the micro-stress field of secondary cracks in the braided ceramic matrix composite material. The micro-stress field of secondary cracks in the braided ceramic matrix composite material includes the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage, and the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage. The axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage includes the axial stress distribution of the fibers in the interfacial debonding zone and the interfacial bonding zone. The axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage includes the axial stress distribution of the matrix in the interfacial debonding zone and the interfacial bonding zone. Specifically, obtaining the micro-stress field of secondary cracks in the braided ceramic matrix composite material using a micromechanical method based on the material parameters includes: using the formula... Calculate the axial micro-stress field of fibers in composite materials after matrix cracking and interfacial debonding damage. In the formula, V f This refers to the fiber volume content. External stress, η It is the ratio of the thickness of the axial yarn to the thickness of both the axial and transverse yarns. For the axial stress of the transverse yarn in the bonding area, It is the ratio of the axial to the transverse yarn thickness. τ i For interfacial shear stress, r f Where is the fiber radius, x Indicates the axial coordinate of the fiber. L d To determine the interfacial debonding length of secondary cracks in braided ceramic matrix composites. For the axial stress of the fibers in the interfacial bonding zone, ρ For shear hysteresis model parameters, L c The crack spacing in the matrix is ​​given by the formula; based on the matrix material parameters, the formula is used. Calculate the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage in the composite material. In the formula, V m This refers to the matrix volume content. This indicates the stress in the bonding zone at the matrix interface; Based on the microscopic stress field of the secondary crack in the braided ceramic matrix composite material, the axial displacement of the fiber and the axial displacement of the matrix within the interface debonding zone are obtained by axial displacement calculation method. The interface debonding length of the secondary crack in the braided ceramic matrix composite material is obtained by fracture mechanics method based on the axial displacement of the fiber within the interface debonding zone and the axial displacement of the matrix within the interface debonding zone. The opening displacement of the secondary crack in the woven ceramic matrix composite material is obtained based on the interfacial debonding length of the secondary crack, the axial displacement of the fibers within the interfacial debonding zone, and the axial displacement of the matrix within the interfacial debonding zone. Specifically, obtaining the opening displacement of the secondary crack in the woven ceramic matrix composite material based on the interfacial debonding length of the secondary crack, the axial displacement of the fibers within the interfacial debonding zone, and the axial displacement of the matrix within the interfacial debonding zone includes: based on the interfacial debonding length of the secondary crack in the woven ceramic matrix composite material... L d and the fiber displacement relative to the matrix U ( x ), using the formula Calculate the secondary crack opening displacement Ψ in braided ceramic matrix composites COD In the formula, E 1 represents the elastic modulus of the composite material along the fiber direction. E f Indicates the fiber's elastic modulus. E c Indicates the elastic modulus of composite materials. E m This represents the elastic modulus of the matrix. L d This indicates the interfacial debonding length of secondary cracks in woven ceramic matrix composites.

2. The method for predicting the secondary crack opening displacement of braided ceramic matrix composites according to claim 1, characterized in that, The method for calculating the axial displacement of fibers and the matrix within the interface debonding zone based on the microscopic stress field of the secondary crack in the braided ceramic matrix composite material includes: Based on the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage in the composite material, the formula is used. Calculate the axial displacement Ψ of the fiber within the debonding zone of the interface. AFD ( x In the formula, E f Indicates the fiber's elastic modulus. E c Indicates the elastic modulus of a composite material; Based on the axial microscopic stress field of the matrix after matrix cracking and interfacial debonding damage in the composite material, the formula is used. Calculate the axial displacement Ψ of the matrix within the debonding zone of the interface. AMD ( x In the formula, E m This represents the elastic modulus of the matrix.

3. The method for predicting the secondary crack opening displacement of braided ceramic matrix composites according to claim 2, characterized in that, The step of obtaining the interfacial debonding length of the secondary crack in the braided ceramic matrix composite material using fracture mechanics methods, based on the axial displacement of the fibers within the interface debonding zone and the axial displacement of the matrix within the interface debonding zone, specifically includes: The axial displacement Ψ of the fibers within the debonding zone of the interface AFD ( x and the axial displacement Ψ of the substrate within the debonding zone of the interface. AMD ( x Calculate the difference between the fiber and the matrix displacement. U ( x ); According to the fiber relative to the matrix displacement U ( x ) and the axial displacement Ψ of the fibers within the debonding zone of the interface. AFD ( x ), using the formula Calculate the interfacial debonding length of secondary cracks in braided ceramic matrix composites L d In the formula, Γ i For interfacial debonding energy, F To bear the load for the planar fibers in the matrix crack, Ψ AFD ( x =0) represents the axial displacement of the fiber in the matrix crack plane.

4. A secondary crack opening displacement prediction system for braided ceramic matrix composites, characterized in that, The system includes: A material parameter acquisition module is used to acquire the material parameters of the woven ceramic matrix composite material; the material parameters include fiber material parameters and matrix material parameters. The module for obtaining the micro-stress field of secondary cracks is used to obtain the micro-stress field of secondary cracks in braided ceramic matrix composites using micromechanical methods based on the material parameters. The micro-stress field of secondary cracks in the braided ceramic matrix composites includes the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage, and the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage. The axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage includes the axial stress distribution of the fibers in the interfacial debonding and interfacial bonding zones. The axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage includes the axial stress distribution of the matrix in the interfacial debonding and interfacial bonding zones. Specifically, the module for obtaining the micro-stress field of secondary cracks includes: an axial micro-stress field calculation unit for fibers, used to calculate the axial micro-stress field of the fibers based on the fiber material parameters using formulas... Calculate the axial micro-stress field of fibers in composite materials after matrix cracking and interfacial debonding damage. In the formula, V f This refers to the fiber volume content. External stress, η It is the ratio of the thickness of the axial yarn to the thickness of both the axial and transverse yarns. For the axial stress of the transverse yarn in the bonding area, It is the ratio of the axial to the transverse yarn thickness. τ i For interfacial shear stress, r f Where is the fiber radius, x Indicates the axial coordinate of the fiber. L d To determine the interfacial debonding length of secondary cracks in braided ceramic matrix composites. For the axial stress of the fibers in the interfacial bonding zone, ρ For shear hysteresis model parameters, L c The matrix crack spacing; the axial micro-stress field calculation unit of the matrix, used to calculate the matrix material parameters using the formula... Calculate the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage in the composite material. In the formula, V m This refers to the matrix volume content. This indicates the stress in the bonding zone at the matrix interface; The axial displacement module of the fiber and the matrix is ​​used to calculate the axial displacement of the fiber and the axial displacement of the matrix within the interface debonding zone based on the micro-stress field of the secondary crack in the woven ceramic matrix composite material. The interface debonding length obtaining module is used to obtain the interface debonding length of the secondary crack in the braided ceramic matrix composite material by means of fracture mechanics based on the axial displacement of the fiber within the interface debonding zone and the axial displacement of the matrix within the interface debonding zone. The secondary crack opening displacement acquisition module is used to obtain the secondary crack opening displacement of the braided ceramic matrix composite material based on the interfacial debonding length of the secondary crack, the axial displacement of the fibers within the interfacial debonding zone, and the axial displacement of the matrix within the interfacial debonding zone. The secondary crack opening displacement acquisition module specifically includes a secondary crack opening displacement calculation unit, used to calculate the secondary crack opening displacement based on the interfacial debonding length of the secondary crack in the braided ceramic matrix composite material. L d and the fiber displacement relative to the matrix U ( x ), using the formula Calculate the secondary crack opening displacement Ψ in braided ceramic matrix composites COD In the formula, E 1 represents the elastic modulus of the composite material along the fiber direction. E f Indicates the fiber's elastic modulus. E c Indicates the elastic modulus of composite materials. E m This represents the elastic modulus of the matrix. L d This indicates the interfacial debonding length of secondary cracks in woven ceramic matrix composites.

5. The secondary crack opening displacement prediction system for braided ceramic matrix composites according to claim 4, characterized in that, The module for obtaining the axial displacement of the fiber and the matrix specifically includes: The fiber axial displacement calculation unit is used to calculate the axial micro-stress field of the fibers after matrix cracking and interfacial debonding damage in the composite material, using the formula... Calculate the axial displacement Ψ of the fiber within the debonding zone of the interface. AFD ( x In the formula, E f Indicates the fiber's elastic modulus. E c Indicates the elastic modulus of a composite material; The matrix axial displacement calculation unit is used to calculate the axial micro-stress field of the matrix after matrix cracking and interfacial debonding damage in the composite material, using the formula... Calculate the axial displacement Ψ of the matrix within the debonding zone of the interface. AMD ( x In the formula, E m This represents the elastic modulus of the matrix.

6. The secondary crack opening displacement prediction system for braided ceramic matrix composites according to claim 5, characterized in that, The module for obtaining the interface debonding length specifically includes: The fiber-matrix displacement calculation unit is used to calculate the axial displacement Ψ of the fibers within the debonding zone of the interface. AFD ( x and the axial displacement Ψ of the substrate within the debonding zone of the interface. AMD ( x Calculate the difference between the fiber and the matrix displacement. U ( x ); The interface debonding length calculation unit is used to calculate the fiber's displacement relative to the matrix. U ( x ) and the axial displacement Ψ of the fibers within the debonding zone of the interface. AFD ( x ), using the formula Calculate the interfacial debonding length of secondary cracks in braided ceramic matrix composites L d In the formula, Γ i For interfacial debonding energy, F To bear the load for the planar fibers in the matrix crack, Ψ AFD ( x =0) represents the axial displacement of the fiber in the matrix crack plane.

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