A method and application of constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials

Abstract

The invention discloses a method and application for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials. A rectangular coordinate system is constructed with the center position of the connection point between the fuselage and the wing as the coordinate origin, the wing span direction as the X-axis, the wing heading direction as the Y-axis, and the wing vertical direction as the Z-axis. The electrical conductivity in the X, Y and Z directions is derived based on the anisotropy of the CFRP material on the cross section, and the influence of influencing factors such as force and temperature on the electrical conductivity of the CFRP component in the aircraft wing is considered, so as to respectively construct the damage influencing factors of force and temperature. Thus, a damage determination model of the aircraft during operation is obtained; and the structural health monitoring of the CFRP component in the aircraft wing is performed using the damage determination model.

Description

Technical Field

[0001] The present invention belongs to the technical field of structural health monitoring of composite material components for aircraft, and in particular relates to a method and application of constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials. Background Art

[0002] During the service of an aircraft, each component of the aircraft is subjected to high temperature, high pressure, fatigue load, etc., so the structure is prone to various damages, which in turn cause the destruction of the aircraft structure. At present, the detection methods for aircraft structures include buried sensor element method, visual method, tapping method, X-ray photography method, ultrasonic imaging method, ultrasonic pulse penetration method, etc., but these methods have the disadvantages of destroying structural integrity, complex operation, long test cycle, and inability to achieve full-field and full-time continuous monitoring.

[0003] CFRP (carbon fiber composite material) is widely used in the engineering field, especially in the aerospace field, due to its unique high specific stiffness, high specific strength, light weight, high efficiency and non-metallic properties. Looking at the development of CFRP in large aircraft structures, whether it is the Boeing 787, Airbus A380 abroad, or the COMAC C919 in China, its usage is on the rise, and the application level is getting higher and higher. The structural application is expanding from non-load-bearing structures to load-bearing structures and then to main load-bearing structures.

[0004] In addition to the above-mentioned excellent mechanical properties, CFRP also has the intelligent characteristics of self-perception, self-sensing and self-monitoring. Therefore, for aircraft components that use CFRP materials, how to utilize the structural material's own sensing characteristics to achieve accurate, reliable, convenient, and full life cycle detection of the structure is a technical problem that urgently needs to be solved. Summary of the invention

[0005] In order to address the deficiencies in the prior art, the present invention proposes a method and application for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials; the present application constructs its three-dimensional conductive mechanism based on CFRP laminates; then constructs its stress / strain distribution function based on the force characteristics of the aircraft structure; constructs temperature influencing factors during aircraft driving; arranges electrode monitoring points at equidistant intervals; implements monitoring in combination with parking and driving conditions; and realizes self-perception, self-sensing and self-monitoring of aircraft wings and other components.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials, comprising:

[0008] S1, construct a rectangular coordinate system (X, Y, Z) with the center of the connection point between the fuselage and the wing as the coordinate origin, the wing span direction as the X axis, the wing heading as the Y axis, and the wing vertical direction as the Z axis;

[0009] S2, based on the anisotropy of CFRP material on the cross section, the current density in each direction in the rectangular coordinate system is obtained, and the current density in each direction is converted to spherical coordinates (α, β, γ). Based on the current density after coordinate conversion, the conductivity in the three directions of X, Y and Z is further derived, expressed as:

[0010]

[0011] Among them, I x ,I y ,I z are the current densities in the X-axis, Y-axis and Z-axis directions respectively, and ψ(x, y, z) is the potential function.

[0012] S3, considering the influence of factors such as force and temperature on the conductivity of CFRP components in aircraft wings, the damage influence factors C of force and temperature are constructed respectively. F (x,y,z),C T (x,y,z);

[0013] S4, based on S1, S2, and S3, the damage determination model of the aircraft during operation is expressed as:

[0014] M C =C I (x,y,z)+C F (x,y,z)+C T (x,y,z)

[0015] The above damage determination model is used to perform structural health monitoring on CFRP components in aircraft wings.

[0016] Furthermore, the current density in each direction in the rectangular coordinate system is expressed as:

[0017]

[0018] Among them, C xx ,C yy ,C zz They are the conductivity in the X-axis, Y-axis and Z-axis directions respectively.

[0019] Furthermore, the current density in spherical coordinates (α, β, γ) is expressed as:

[0020]

[0021] Among them, I α ,Iβ ,I γ is the current density in the longitudinal, transverse and thickness directions after coordinate transformation, Q e is the source intensity, r is the sphere radius, C xx ,C yy ,C zz They are the conductivity in the X-axis, Y-axis and Z-axis directions respectively.

[0022] Furthermore, the stress damage influence factor C is constructed F (x,y,z) is represented as:

[0023] Taking the wing as the analysis object, the force on the wing is analyzed to obtain the resultant force on the wing, and the control equation between the strain generated by the resultant force on the wing and the conductivity is constructed. Therefore, the damage influence factor of the resultant force on the wing on the conductivity of the CFRP material is expressed as:

[0024]

[0025] Among them, k e is the correction factor, F e is the directional force, A e is the directional area, and E is the elastic modulus of the material.

[0026] Furthermore, the damage influence factor C of temperature is constructed T The process of (x,y,z) is:

[0027] Due to the different effective thermal expansion coefficients of the fiber reinforcement term and the epoxy resin matrix term in the carbon fiber, the CFRP material will produce thermal stress and then strain under the influence of the temperature change Δt. The effect of temperature on the electrical conductivity of the CFRP material can be expressed as:

[0028]

[0029] Among them, k e ′ is the correction coefficient.

[0030] A structural health monitoring method based on self-sensing of CFRP aircraft wings includes the following steps:

[0031] S1, construct a rectangular coordinate system (X, Y, Z) with the center position of the connection point between the fuselage and the wing as the coordinate origin, the wing span direction as the X-axis, the wing heading direction as the Y-axis, and the wing vertical direction as the Z-axis; select monitoring points on the aircraft wing, and each monitoring point is equipped with 3 monitoring electrodes; the 3 monitoring electrodes respectively obtain the conductivity values ​​of the monitoring point corresponding to the wing span direction, wing heading direction, and wing vertical direction;

[0032] S2, obtaining the temperature and stress conditions of the wing under the current working condition;

[0033] S3. Using the above-mentioned method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials and applying the damage determination model, the data obtained by S1 and S2 are input into the damage determination model of the aircraft wing, and the current conductivity value is output; the current conductivity value is compared with the data in the conductivity-damage database, and the damage determination result is output.

[0034] Furthermore, for the three monitoring electrodes corresponding to any monitoring point (x, y, z), the distances between the monitoring point and the centers of the three corresponding electrodes are expressed as:

[0035] {L x =∫a1dx L y =∫a2dy L z =∫a3dz}

[0036] Among them, L x ,L y ,L z are the distances from any monitoring point to the center of the electrodes in the three directions, and a1, a2, and a3 are the results of partial differential solutions of the displacements in the X, Y, and Z directions in the strain coordination equation.

[0037] Furthermore, a conductivity-damage database is constructed:

[0038] In the experimental / simulation environment, the conductivity values ​​on the wing are tested under different temperatures and different stress conditions, and the corresponding damage states under the conditions are recorded to form a database.

[0039] The beneficial effects of the present invention are as follows:

[0040] 1. The present invention proposes a method and application for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials. In this method, a three-dimensional electrical conductivity model and potential distribution law of CFRP laminates are constructed through theoretical deduction, providing a theoretical model for revealing the conductive mechanism of CFRP and using the resistance method for structural health monitoring.

[0041] 2. The present invention proposes a method and application for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials. In this method, the relationship between CFRP temperature and electrical conductivity is constructed through mathematical and physical methods, which can effectively correct the accuracy of the monitoring data of the aircraft during operation.

[0042] 3. The present invention proposes a method and application for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials. Compared with other monitoring methods, this method constructs a method for arranging electrodes in three directions of any monitoring point through theoretical deduction, making damage monitoring more accurate.

[0043] 4. The method and application of constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials proposed in the present invention is based on the monitoring concept of structural self-sensing, has good feasibility, excellence and reliability, and can realize monitoring and early warning in the fuselage structure, tail structure and other parts, providing technical support for the intelligent operation and maintenance of aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of aircraft lift;

[0045] Figure 2 It is the conductivity analysis diagram of CFRP laminate in direct coordinate system;

[0046] Figure 3 It is the conductivity analysis diagram of CFRP laminate in spherical coordinate system;

[0047] Figure 4 This is the force analysis diagram of the wing;

[0048] Figure 5 This is an analysis diagram of the wing measurement points and electrode layout.

[0049] In the figure: 41, wing; 51 monitoring point; 52 electrode; 53 electrode center. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention clear, the present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0051] Example 1

[0052] Existing studies have shown that CFRP not only has excellent electrical conductivity, but also has anisotropic mechanical properties in the cross section. This causes CFRP to have different electrical conductivities in different directions after being subjected to force. Based on this mechanical property, the present invention proposes a method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials, comprising the following steps:

[0053] S1, such as Figure 1 As shown, a rectangular coordinate system (X, Y, Z) is constructed with the center position of the connection point between the fuselage and the wing as the coordinate origin, the wing span direction as the X-axis, the wing heading as the Y-axis, and the wing vertical direction as the Z-axis.

[0054] S2, such as Figure 2 As shown, because the CFRP material is anisotropic on the cross section, the conductivity tensor composed of the rectangular coordinate system established based on S1 and the isotropic conductivity on the cross section of the CFRP material is:

[0055]

[0056] Among them, C xx ,C yy ,C zz are the conductivity in the X-axis (longitudinal), Y-axis (transverse) and Z-axis (thickness) directions, θ is the angle of fiber arrangement in the laminate, σ xx , σ yy , σ zz They are the stresses in the X-axis (longitudinal), Y-axis (transverse) and Z-axis (thickness) directions respectively.

[0057] According to Ohm's law, the current density in each direction in the coordinate system (X, Y, Z) can be expressed by the differential form of the potential function ψ(x, y, z):

[0058]

[0059] Among them, I x ,I y ,I z They are the current density in the X-axis (longitudinal), Y-axis (transverse) and Z-axis (thickness) directions respectively.

[0060] When no current flows through the CFRP laminate:

[0061]

[0062] Among them, ▽ is the Laplace operator.

[0063] Since the electric current can be considered as an irrotational, incompressible, and non-viscous fluid, its potential function can be used to flow in three dimensions inside the CFRP material. Figure 3 As shown, the anisotropic coordinates (X, Y, Z) can be transformed into isotropic coordinates (α, β, γ), then equation (3) can be transformed into the Laplace equation, that is:

[0064]

[0065] Since the two coordinates are in the same direction, the current density can be interchanged, and we have:

[0066]

[0067] Among them, I α ,I β ,I γ is the current density in the longitudinal, transverse and thickness directions after coordinate transformation, and I0 is the initial total current in the circuit.

[0068] In an infinitely long CFRP laminate, the current source is located at the origin. When the power is turned on, the current source flows uniformly in all directions from the origin at a certain flow rate. In the spherical coordinates (α, β, γ), the velocity potential function of the current in the radial direction is:

[0069]

[0070] Among them, ζ(x,y,z) is the current velocity potential function, Q e is the source intensity, r is the sphere radius. In spherical coordinates (α, β, γ), the isotropic current density is:

[0071]

[0072] Then the current density I in the direction of radius r is r for:

[0073] I r =I α l1+I β l2+I γ l3 (8)

[0074] Among them, l1, l2, l3 are the cosine values ​​of the angles between OP (the line between the origin O and any point P in the spherical coordinates) and the principal axes Oα, Oβ, Oγ.

[0075] At this time, the total current I T is the integral of the current density in all directions:

[0076]

[0077] Among them, θ′ is the angle between OP and γ axis, and ω′ is the angle between Oα and OM axis.

[0078] According to formula (9), the three-dimensional current source intensity can be obtained as follows:

[0079]

[0080] Substituting equation (7) into equation (4) and combining equation (10) in parallel, we can obtain the three-dimensional potential function of current:

[0081]

[0082] When a steady current is input, the conductivity of a point with coordinates (x, y, z) in the three directions of X, Y and Z can be obtained:

[0083]

[0084] S3, during the service of the aircraft, the two factors of force and temperature will have a great impact on the conductivity of the structure, and thus affect the accuracy of the structural damage judgment. To address this problem, the present invention fully considers the influence of the two factors of force and temperature on the conductivity of the CFRP components in the aircraft wing, and thus constructs the damage influence factors C of force and temperature respectively. F (x,y,z),C T (x,y,z).

[0085] S3.1, such as Figure 4 As shown, the effect of stress on the electrical conductivity of CFRP components is considered.

[0086] Take the wing as the analysis object, take the microelement segment dx in the span direction (X direction), and the arc length ds on the microelement segment t , arc length of lower surface ds b , the angles between their tangents and the chord are θ t ,θ b , the windward angle of the wing is θ f , air velocity in front of the wing v f , then the lift dF generated by the pressure difference between the upper and lower surfaces of the wing s for:

[0087] dF s =(F b ·ds b ·cosθ b -F t ·ds t ·cosθ t )·cosθ f (13)

[0088] Among them, F b ,F t are the pressures on the lower and upper surfaces of the wing respectively.

[0089] According to Bernoulli's equation, we have:

[0090]

[0091] Among them, ρ f is the air density, a p,b ,a p,t are the lift coefficients of the lower and upper surfaces of the wing, respectively.

[0092] At the same time, the following geometric relationship is satisfied on the micro segment:

[0093] ds t ·cosθ t ≈ds b ·cosθ b ≈dx(15)

[0094] According to formula (13) and (14), we have:

[0095]

[0096] Where L is the wingspan length.

[0097] Then the governing equation for lift is:

[0098]

[0099] Where a′ is the lift coefficient difference between the upper and lower surfaces of the wing; A(x) is the wing area.

[0100] The force equations in the other two directions (Y direction and Z direction) can be obtained in the same way, so there is a resultant force:

[0101]

[0102] According to the control equation of conductivity and strain (the derivation of this equation can refer to the corresponding content disclosed in ZL202310581898.5):

[0103]

[0104] Among them, B, η, ξ are all material constant coefficients, C0 is a constant, ε x ,ε y ,γ xy are the normal strain and shear strain in the X and Y directions respectively.

[0105] Since only the independent conductivity generated by deformation in three directions is monitored, the strain effect caused by deformation in other directions can be ignored. The effect of the combined force on the wing on the conductivity of the CFRP material can be expressed as:

[0106]

[0107] Among them, k e is the correction factor, F e is the directional force, A e is the directional area, and E is the elastic modulus of the material.

[0108] S3.2, consider the effect of temperature on the electrical conductivity of CFRP components.

[0109] Civil aircraft generally cruise in the stratosphere (at an altitude of 10,000 to 12,000 meters, and temperatures are usually between -60°C and -40°C). Due to the different effective thermal expansion coefficients of the fiber reinforcement and epoxy resin matrix in the carbon fiber, the CFRP material will produce thermal stress under the influence of the temperature change Δt. The average strain is:

[0110]

[0111] in, is the average strain of CFRP material, ε′ is the disturbance strain caused by the interaction between matrix and fiber and between fibers, ε″ is the strain caused by the disturbance of single fiber, ε″′ is the equivalent internal strain of fiber, S i,j is the Eshellby tensor of the fiber, V p ′ is the volume fraction of the fiber, V cfrp ,V p are the volume of CFRP material and the volume of single fiber respectively, v is the volume, It is the strain caused by thermal mismatch between fiber and CFRP material matrix.

[0112] The strain between the fiber and the matrix due to thermal mismatch is:

[0113]

[0114] Since the disturbance strain of the fiber satisfies:

[0115]

[0116] Therefore, the self-equilibrium condition of the internal disturbance of CFRP material is:

[0117]

[0118] Among them, ε1 and ε0 are the strain after temperature change and the initial strain respectively, Δt is the temperature change, α′ is the CFRP expansion coefficient, are the average stress in the matrix and the average stress in the fiber inclusions, respectively.

[0119] From equations (21)-(24), the average strain tensor of CFRP in a certain direction after heating can be obtained as:

[0120]

[0121] in, are the strain tensor after temperature change and the initial strain tensor, respectively.

[0122] The effect of temperature on the electrical conductivity of CFRP materials can be expressed as:

[0123]

[0124] Among them, k e ′ is the correction coefficient.

[0125] S4, based on the theoretical derivation of S1, S2, and S3, the damage determination model of the aircraft during operation can be obtained as follows:

[0126] M C=C I (x,y,z)+C F (x,y,z)+C T (x,y,z) (27)

[0127] The damage identification model can be used to monitor the wing in the full time domain and full field domain during the operation of the aircraft.

[0128] Example 2

[0129] The present invention also proposes a structural health monitoring method based on self-sensing of CFRP aircraft wings. The method uses the aircraft wing damage determination model constructed by the method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials proposed in Example 1 to achieve self-sensing structural health monitoring of aircraft wings. The specific steps of the method are as follows:

[0130] S1, select monitoring points on the aircraft wing at equal or variable intervals, each monitoring point is equipped with 3 monitoring electrodes, and the conductivity values ​​of the wing span, wing heading, and wing vertical corresponding to the monitoring point can be obtained by using the 3 monitoring electrodes corresponding to the monitoring point.

[0131] More specifically, the three monitoring electrodes are arranged in three directions of the rectangular coordinate system (X, Y, Z) constructed in Example 1.

[0132] More preferably, according to the three-dimensional stress state of any point in elastic mechanics after being stressed and the anisotropic properties of the cross section of the CFRP material, the stress at any point (x, y, z) on the wing will cause the point to have different electrical conductivities in the X-axis, Y-axis, and Z-axis directions. Therefore, the positions of the three monitoring electrodes need to be optimized, so that the three-dimensional data of the damage at the monitoring point can be calculated more accurately. Therefore, the arrangement method of the three electrodes at any monitoring point in the wing is as follows:

[0133] According to formula (18), the stress state of any point on the wing can be known. According to the stress state of any point, combined with the different conductivity of any point (x, y, z) in the CFRP material in three directions in S3.1, the electrode positions in the three directions of any monitoring point can be reasonably arranged. Figure 5 As shown in the figure, according to the theory of strain state after a point is subjected to force in elastic mechanics:

[0134]

[0135] According to the wing force distribution function of formula (18), the strain of any monitoring point (x, y, z) in the three directions of X-axis, Y-axis and Z-axis can be obtained from the above formula. According to the strain coordination equation, we can get:

[0136]

[0137] Among them, ε is the principal strain, l, m, n are direction cosines, ε x ,ε y ,ε z are the normal strains in three directions, γ xy ,γ yz ,γ xz are the shear strains in three directions, u, v, w are the displacements in three directions, and a1, a2, a3 are the results of partial differential solutions of the displacements in the X, Y and Z directions in the strain coordination equation.

[0138] Based on the solution of the above partial differential equation, the distance between any monitoring point and the corresponding three electrode centers can be expressed as:

[0139] {L x =∫a1dx L y =∫a2dy L z =∫a3dz} (30)

[0140] Among them, L x ,L y ,L z are the distances from any monitoring point to the centers of electrodes in three directions.

[0141] S2. Obtain the temperature and stress conditions of the wing under the current working condition.

[0142] S3, input the data obtained by S1 and S2 into the aircraft wing damage determination model, output the current conductivity value, compare the current conductivity value with the data in the conductivity-damage database, and output the damage determination result.

[0143] More specifically, the method for constructing a conductivity-damage database is as follows:

[0144] In the experimental / simulation environment, the conductivity value on the wing is tested under different temperatures and different stress conditions, and the corresponding damage status under the condition is recorded to form a database.

[0145]

[0146] Refer to the above table to form a database. The damage state can be divided into level I, level II, level III, and level IV according to the development trend of the crack, corresponding to microcrack generation, microcrack extension, initial damage, and final damage respectively.

[0147] The CFRP component mentioned in this embodiment includes a single-layer plate or a laminated plate with a certain thickness made of CFRP material, or other forms of CFRP material.

[0148] The above embodiments are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable scientific research and engineering technicians in the field to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments, so all equivalent changes or modifications made based on the theories, technologies and methods disclosed in the present invention are within the protection scope of the present invention.

Claims

1. A method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials, characterized in that: include: S1, construct a rectangular coordinate system (X, Y, Z) with the center of the connection point between the fuselage and the wing as the coordinate origin, the wing span direction as the X axis, the wing heading as the Y axis, and the wing vertical direction as the Z axis; S2, based on the anisotropy of CFRP material on the cross section, the current density in each direction in the rectangular coordinate system is obtained, and the current density in each direction is converted to spherical coordinates (α, β, γ). Based on the current density after coordinate conversion, the conductivity in the three directions of X, Y and Z is further derived, expressed as: Among them, I x ,I y ,I z are the current density in the X-axis, Y-axis and Z-axis directions respectively, and ψ(x,y,z) is the potential function; S3, considering the influence of stress and temperature on the conductivity of CFRP components in aircraft wings, the damage influence factors C of stress and temperature are constructed respectively. F (x,y,z),C T (x,y,z); S4, based on S1, S2, and S3, the damage determination model of the aircraft during operation is expressed as: M C =C I (x,y,z)+C F (x,y,z)+C T (x,y,z) The above damage determination model is used to perform structural health monitoring on CFRP components in aircraft wings.

2. The method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials according to claim 1, characterized in that: The current density in each direction in the rectangular coordinate system is expressed as: Among them, C xx ,C yy ,C zz They are the conductivity in the X-axis, Y-axis and Z-axis directions respectively.

3. The method and application of constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials according to claim 1, characterized in that: The current density in spherical coordinates (α, β, γ) is expressed as: Among them, I α ,I β ,I γ is the current density in the longitudinal, transverse and thickness directions after coordinate transformation, Q e is the source intensity, r is the sphere radius, C xx ,C yy ,C zz They are the conductivity in the X-axis, Y-axis and Z-axis directions respectively.

4. The method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials according to claim 1, characterized in that: Construction of the damage influence factor C F (x,y,z) is represented as: Taking the wing as the analysis object, the force on the wing is analyzed to obtain the resultant force on the wing, and the control equation between the strain generated by the resultant force on the wing and the conductivity is constructed. Therefore, the damage influence factor of the resultant force on the wing on the conductivity of the CFRP material is expressed as: Among them, k e is the correction factor, F e is the directional force, A e is the directional area, E is the elastic modulus of the material, and B, η, ξ are all constant coefficients of the material.

5. The method for constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials according to claim 1, characterized in that: Damage influence factor C of construction temperature T The process of (x,y,z) is: Due to the different effective thermal expansion coefficients of the fiber reinforcement term and the epoxy resin matrix term in the carbon fiber, the CFRP material will produce thermal stress and then strain under the influence of the temperature change Δt. The effect of temperature on the electrical conductivity of the CFRP material can be expressed as: Among them, k e ′ is the correction coefficient, B, η, ξ are all constant coefficients of materials, is the average strain tensor of CFRP in a certain direction after heating.

6. A structural health monitoring method based on self-sensing of CFRP aircraft wings, characterized in that: The steps include: S1, construct a rectangular coordinate system (X, Y, Z) with the center position of the connection point between the fuselage and the wing as the coordinate origin, the wing span direction as the X-axis, the wing heading direction as the Y-axis, and the wing vertical direction as the Z-axis; select monitoring points on the aircraft wing, and each monitoring point is equipped with 3 monitoring electrodes; the 3 monitoring electrodes respectively obtain the conductivity values ​​of the monitoring point corresponding to the wing span direction, wing heading direction, and wing vertical direction; S2, obtaining the temperature and stress conditions of the wing under the current working condition; S3. Use the method of constructing an aircraft wing damage determination model based on the electrical conductivity characteristics of CFRP materials as described in claim 1, input the data obtained by S1 and S2 into the damage determination model of the aircraft wing, and output the current conductivity value; compare the current conductivity value with the data in the conductivity-damage database, and output the damage determination result.

7. A structural health monitoring method based on self-sensing of CFRP aircraft wings according to claim 6, characterized in that: For the three monitoring electrodes corresponding to any monitoring point (x, y, z), the distances between the monitoring point and the centers of the three corresponding electrodes are expressed as: {L x =∫a1dx L y =∫a2dy L z =∫a3dz} Among them, L x ,L y ,L z are the distances from any monitoring point to the center of the electrodes in the three directions, and a1, a2, and a3 are the results of partial differential solutions of the displacements in the X, Y, and Z directions in the strain coordination equation.

8. The structural health monitoring method based on self-sensing of CFRP aircraft wings according to claim 6 is characterized in that: Build a conductivity-damage database: In the experimental / simulation environment, the conductivity values ​​on the wing are tested under different temperatures and different stress conditions, and the corresponding damage states under the conditions are recorded to form a database.

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