Method, equipment and medium for detecting internal crack defects of epoxy composite material

Abstract

The invention relates to the technical field of gas insulation, in particular to an epoxy composite material internal crack defect detection method, equipment and a medium, structural parameters of a 110kV epoxy basin-type insulator are measured, and three-dimensional modeling software is adopted to construct a three-dimensional structural model equal to a real object in proportion; applying a thermal boundary condition to the three-dimensional structure model body, respectively setting the depth and the deflection angle of the crack defect as h and theta, and setting the material attribute of the bubble defect area as air; the method comprises the following steps: acquiring surface thermal imaging characteristics of the defect of the epoxy basin-type insulator based on a solid heat transfer theory, outputting the surface thermal imaging characteristics of the defect of the epoxy basin-type insulator, and acquiring surface thermal imaging characteristics of the crack defect at different deflection angles under different defect depths by changing the depth and the deflection angle of the crack defect for many times based on the solid heat transfer theory. Equipment temperature resolution is used as a judgment basis, and feasibility exploration of crack defect detection at different deflection angles under different defect depths is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas insulation, and in particular to an epoxy composite internal crack defect detection method, device and medium. BACKGROUND

[0002] The epoxy pot-type insulator not only bears the insulation function, but also supports the center conductor in the gas insulated switchgear (GIS), and the stability of its structure and performance is crucial to the safe operation of the GIS device. In actual production and service process, due to the coupling of epoxy resin and curing agent formula, curing process control and thermal-mechanical stress and other factors, the epoxy pot-type insulator is prone to crack defects. These cracks not only weaken the overall structural integrity of the insulator, but also easily form local electric field concentration under the action of operating electric field. Especially in the crack tip area, electric field distortion will cause local temperature rise and may cause electrochemical corrosion. Long-term local overheating and material decomposition will further aggravate crack propagation, accelerate the aging of insulating materials, significantly reduce their dielectric strength, and thus pose a potential threat to the reliable operation of the GIS device.

[0003] Existing researches are less about the detection of small size defects inside the epoxy pot-type insulator, and it is difficult to detect defects inside low thermal conductivity non-metallic materials. Therefore, it is urgent to study the detection method of small size defects inside the epoxy pot-type insulator to improve the detection accuracy of bubble defects inside the epoxy pot-type insulator. SUMMARY

[0004] In view of the above existing problems, the present application is proposed.

[0005] Therefore, the present application provides an epoxy composite internal crack defect detection method, device and medium to solve the problem that existing researches are less about the detection of small size defects inside the epoxy pot-type insulator, and it is difficult to detect defects inside low thermal conductivity non-metallic materials.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides an epoxy composite internal crack defect detection method, comprising:

[0008] The structure parameters of the 110kV epoxy pot-type insulator are measured, and a three-dimensional structure model with the same proportion as the actual object is constructed by using a three-dimensional modeling software;

[0009] A thermal boundary condition is applied to the three-dimensional structure model, the depth and deflection angle of the crack defect are set respectively, and the material properties of the bubble defect area are set;

[0010] The surface thermal imaging features of the epoxy pot-type insulator defect are obtained based on the solid heat transfer theory, and the surface thermal imaging features of the epoxy pot-type insulator defect are output.

[0011] As a preferred scheme of the epoxy composite internal crack defect detection method, the three-dimensional structure model comprises:

[0012] The metal flange, the center insert and the epoxy body.

[0013] The metal flange connects the epoxy body and the external equipment mechanically.

[0014] The center insert provides an electrical connection interface.

[0015] The epoxy body provides overall insulation performance and mechanical support strength.

[0016] As a preferred scheme of the epoxy composite internal crack defect detection method, the three-dimensional structure model is subjected to a thermal boundary condition, which comprises:

[0017] The metal flange, the center insert and the epoxy body are subjected to a thermal boundary condition.

[0018] The convex surface of the epoxy pot-type insulator is set as a thermal excitation application surface, i.e., a detection surface, a heat flow density of 10000 W / m 2 is applied to the surface as a heat source excitation, and the excitation duration is 6s.

[0019] The concave surface is set as an adiabatic boundary, and it is assumed that the heat flow cannot be transmitted through the surface to realize the unidirectionality of heat conduction.

[0020] As a preferred scheme of the epoxy composite internal crack defect detection method, the surface thermal imaging features of the epoxy pot-type insulator defect are obtained based on the solid heat transfer theory, which comprises:

[0021] A surface temperature collection interval is set.

[0022] The surface thermal imaging features of the epoxy pot-type insulator are characterized by the surface temperature difference between the defect area and the non-defect area.

[0023] According to the thermal circuit theory, the relationship between the surface temperature of the defect and the surface temperature of the non-defect is obtained, and the difference between the surface temperature of the defect and the surface temperature of the non-defect is determined.

[0024] As a preferred scheme of the epoxy composite internal crack defect detection method, the surface temperature collection interval comprises:

[0025] The temperature collection interval comprises the surface temperature of the defect and the surface temperature of the non-defect, and a defect detection sensitivity TL is set.

[0026] The beneficial effects of the preferred technical solution are: by defining the temperature collection interval covering the surface temperature of the defect and non-defect, and setting the defect detection sensitivity, a standardized data collection and analysis benchmark is established for the thermal imaging detection of the internal crack defects of the epoxy composite material.

[0027] As a preferred scheme of the method for detecting internal crack defects of an epoxy composite material, the surface thermal imaging features of the epoxy pot-type insulator are characterized by the surface temperature difference between the defect area and the non-defect area, including:

[0028] The surface thermal imaging features of the epoxy pot-type insulator can be characterized by the surface temperature difference between the defect area and the non-defect area, and the temperature difference is defined as:

[0029] ΔT=Tqc-Tf

[0030] In the formula, Tqc is the surface temperature of the defect, Tf is the surface temperature of the non-defect, and ΔT represents the temperature difference between the defect and the normal part in the infrared thermal image.

[0031] As a preferred scheme of the method for detecting internal crack defects of an epoxy composite material, the relationship between the surface temperature of the defect and the surface temperature of the non-defect is obtained according to the thermal circuit theory, including:

[0032] According to the thermal circuit theory, the heat flow Q through the thermal resistance is:

[0033]

[0034] In the formula, Q represents the heat flow, ΔT is the temperature gradient, and R is the thermal resistance.

[0035] According to the heat flow continuity principle, under the steady state condition, the heat flow on any heat conduction path must be continuous, and the heat flow through any cross section at the same time is equal between different materials or areas. The heat flow Q through the cross section S per unit time remains constant. The upper surface temperature of the tested sample is T1, the cross section temperature is T2, the heat flow direction is mainly from top to bottom, and in the heat path L1, the thermal resistance of the two epoxy materials is Rh1 and Rh2 respectively, and the total thermal resistance is R1=Rh1+Rh2. In the heat path L2 where the bubble defect exists, the second layer of material is a bubble, and the thermal resistance of the bubble is Rq. The total thermal resistance of this path is R2=Rh1+Rq. The thermal conductivity of air in the bubble is much lower than that of epoxy material, so Rq>Rh2, and therefore R2>R1.

[0036] According to the thermal resistance formula:

[0037]

[0038] Under the condition of the same heat flow Q, the greater the thermal resistance, the greater the temperature gradient ΔT, resulting in the temperature difference of the path where the bubble defect is located increases, and the surface temperature of the defect area is higher than that of the non-defect area.

[0039] As a preferred scheme of the epoxy composite internal crack defect detection method, the difference between the surface temperature of the defect and the surface temperature of the non-defect is determined, including:

[0040] The difference ΔT between the surface temperature of the defect and the surface temperature of the non-defect is determined, and the defect detection sensitivity TL is determined, if ΔT≥TL, the defect recognition requirement is met, and the defect can be detected, if ΔT<TL, the defect recognition requirement is not met, and the defect cannot be detected.

[0041] The beneficial effect of the preferred technical scheme is that by constructing the comparison judgment logic of the difference between the surface temperature of the defect and the surface temperature of the non-defect and the defect detection sensitivity, the problem of fuzzy definition of the detectability of the epoxy composite internal defect is effectively solved.

[0042] In a second aspect, the present application provides an electronic device, comprising:

[0043] a memory and a processor;

[0044] The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions, and the computer executable instructions realize the steps of the epoxy composite internal crack defect detection method when executed by the processor.

[0045] In a third aspect, the present application provides a computer readable storage medium, which stores computer executable instructions, and the computer executable instructions realize the steps of the epoxy composite internal crack defect detection method when executed by the processor.

[0046] Compared with the prior art, the beneficial effect of the present application is that the present application precisely restores the structural characteristics of the metal flange, the center insert and the epoxy body by performing equal proportion three-dimensional modeling on the 110kV epoxy pot-type insulator, lays a basis for analyzing the real object for defect detection, and effectively avoids the detection deviation caused by model distortion. By setting the thermal boundary condition, the convex surface is used as the thermal excitation application surface and a specific heat flux density and excitation time are applied, and the concave surface is set as the adiabatic boundary to realize one-way heat conduction, which strengthens the difference in thermal response between the defect area and the non-defect area, and improves the recognition degree of the thermal imaging features. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and all other drawings obtained by those skilled in the art without creative effort based on these drawings should also fall within the protection scope of the present application.

[0048] Figure 1 The whole flowchart of the method for detecting internal crack defects of an epoxy composite material according to an embodiment of the present application.

[0049] Figure 2 The internal heat flow of an epoxy sample containing a bubble defect according to the method for detecting internal crack defects of an epoxy composite material according to an embodiment of the present application.

[0050] Figure 3 The detection result at the 6th second of the collection time according to the method for detecting internal crack defects of an epoxy composite material according to an embodiment of the present application.

[0051] Figure 4 The detection result at the 12th second of the collection time according to the method for detecting internal crack defects of an epoxy composite material according to an embodiment of the present application.

[0052] Figure 5 The detection result at the 18th second of the collection time according to the method for detecting internal crack defects of an epoxy composite material according to an embodiment of the present application.

[0053] Figure 6 The detection result at the 24th second of the collection time according to the method for detecting internal crack defects of an epoxy composite material according to an embodiment of the present application. DETAILED DESCRIPTION

[0054] In order to make the above objectives, features and advantages of the present application more apparent and comprehensible, the specific embodiments of the present application will be described in detail below with reference to the drawings in the specification. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present application.

[0055] Embodiment 1, refer to Figures 1-2 According to an embodiment of the present application, the embodiment provides a method for detecting internal crack defects of an epoxy composite material, which comprises the following steps.

[0056] The structural parameters of the 110kV epoxy pot-type insulator are measured, and a three-dimensional structural model with the same proportion as the actual object is constructed by using a three-dimensional modeling software.

[0057] A thermal boundary condition is applied to the three-dimensional structure model body, and the depth and deflection angle of the crack defect are set respectively, and the material properties of the bubble defect area are set;

[0058] Based on the solid heat transfer theory, the surface thermal imaging characteristics of the epoxy pot-type insulator defect are obtained, and the surface thermal imaging characteristics of the epoxy pot-type insulator defect are output.

[0059] The three-dimensional structure model comprises,

[0060] Metal flange, center insert, epoxy body;

[0061] The metal flange connects the epoxy body and the external equipment mechanically;

[0062] The center insert provides an electrical connection interface;

[0063] The epoxy body provides overall insulation performance and mechanical support strength.

[0064] The thermal boundary condition applied to the three-dimensional structure model body comprises,

[0065] The thermal boundary condition is applied to the metal flange, the center insert and the epoxy body;

[0066] The convex surface of the epoxy pot-type insulator is set as a thermal excitation application surface, i.e. a detection surface, a heat flux of 10000W / m 2 is applied to the surface to excite the heat source, and the excitation duration is 6s;

[0067] The concave surface is set as an adiabatic boundary, and it is assumed that the heat flow cannot be transmitted through the surface to realize the unidirectionality of heat conduction.

[0068] It should be noted that when the thermal boundary condition is applied to the three-dimensional structure model body, the corresponding conditions are applied to the metal flange, the center insert and the epoxy body respectively, and the convex surface is set as the thermal excitation application surface and the specific heat flux and excitation time are applied, and the concave surface is set as the adiabatic boundary, which ensures the stability and repeatability of heat input, and the adiabatic treatment of the concave surface effectively limits the heat flow transmission direction, realizes the unidirectionality of heat conduction, reduces the interference of heat loss and multidirectional conduction on the detection result, makes the heat flow mainly transmit along the preset path, enhances the significance of temperature difference between the defect area and the non-defect area, provides a clear thermodynamic environment for subsequent defect identification through temperature difference, and improves the recognition degree of thermal imaging characteristics and the accuracy of detection method.

[0069] The depth and deflection angle of the crack defect are set as h and θ respectively, wherein h represents the extension depth of the crack from the surface to the inside, θ represents the deflection angle of the crack relative to the vertical direction, and the material properties of the bubble defect area are set as air, and the thermal physical parameters are consistent with air.

[0070] The surface thermal imaging feature of the epoxy pot-type insulator at the defect is obtained based on the solid heat transfer theory,

[0071] The surface temperature collection interval is set;

[0072] The surface thermal imaging feature of the epoxy pot-type insulator is characterized by the surface temperature difference between the defect area and the non-defect area;

[0073] The relationship between the surface temperature at the defect and the surface temperature at the non-defect is obtained according to the thermal circuit theory, and the surface temperature difference between the defect and the non-defect is determined.

[0074] The surface temperature collection interval is set;

[0075] The temperature collection interval includes the surface temperature at the defect and the surface temperature at the non-defect, and the defect detection sensitivity TL is set.

[0076] The surface thermal imaging feature of the epoxy pot-type insulator is characterized by the surface temperature difference between the defect area and the non-defect area;

[0077] The surface thermal imaging feature of the epoxy pot-type insulator is characterized by the surface temperature difference between the defect area and the non-defect area, and the temperature difference is defined as:

[0078] ΔT = Tqc - Tf

[0079] In the formula, the surface temperature at the defect is Tqc, the surface temperature at the non-defect is Tf, and ΔT represents the temperature difference between the defect part and the normal part in the infrared thermal image.

[0080] It should be noted that the surface thermal imaging feature of the epoxy pot-type insulator is characterized by the surface temperature difference between the defect area and the non-defect area, and the core is to accurately capture the traces of defects by using the temperature difference as a quantifiable physical quantity. The difference between the surface temperature at the defect and the surface temperature at the non-defect is defined as a characteristic parameter, which directly relates to the temperature difference between the defect part and the normal part in the infrared thermal image, converts the abstract thermal imaging feature into a specific numerical index, provides a clear and comparable basis for defect identification, reduces the influence of subjective judgment on the detection result, and ensures the accuracy and consistency of the description of the surface thermal imaging feature of the epoxy pot-type insulator.

[0081] Referring to Figure 2 , the relationship between the surface temperature at the defect and the surface temperature at the non-defect is obtained according to the thermal circuit theory,

[0082] According to the thermal circuit theory, the heat flow Q through the thermal resistance is:

[0083]

[0084] In the formula, Q represents the heat flux, ΔT is the temperature gradient, and R is the thermal resistance;

[0085] According to the principle of heat flow continuity, under steady-state conditions, the heat flow on any heat conduction path must be continuous. The heat flux passing through any cross-section at the same moment between different materials or regions is equal, and the heat flux Q passing through the cross-section S per unit time remains constant. Let the temperature of the upper surface of the tested sample be T1 and the temperature of the cross-section be T2. The heat flow direction is mainly from top to bottom. In the heat path L1, it consists of two sections of epoxy materials, and their thermal resistances are Rh1 and Rh2 respectively. The total thermal resistance is denoted as R1 = Rh1 + Rh2. In the heat path L2 with a bubble defect, the second layer of material is a bubble, and its thermal resistance is Rq. The total thermal resistance of this path is R2 = Rh1 + Rq. The thermal conductivity of the air in the bubble is much lower than that of the epoxy material, and Rq > Rh2. Therefore, R2 > R1;

[0086] According to the thermal resistance formula:

[0087]

[0088] Under the condition of the same heat flux Q, the greater the thermal resistance, the greater the temperature gradient ΔT, resulting in an increase in the temperature difference in the path where the bubble defect is located, and the surface temperature of the defect area is higher than that of the defect-free area.

[0089] The difference in the surface temperature between the defect location and the non-defect location includes

[0090] Judging the size of the difference in surface temperature ΔT between the defect location and the non-defect location and the defect detection sensitivity TL. If ΔT ≥ TL, the defect recognition requirement is met, and the defect can be detected. If ΔT < TL, the defect recognition requirement is not met, and the defect cannot be detected;

[0091] Repeat the detection steps to detect crack defects with different depths and different deflection angles in the shallow surface layer within 2 mm depth.

[0092] It should be noted that by constructing a three-dimensional structural model proportional to the 110 kV epoxy basin insulator in-kind, accurately restoring the combined structure of the metal flange, the central insert, and the epoxy body, a reliable foundation is laid for subsequent detection; when applying the thermal boundary conditions, it is specified that the convex surface is the thermal excitation application surface and a specific heat flux density and excitation duration are set, and the concave surface is set as the adiabatic boundary to ensure the unidirectionality of heat conduction, ensuring that the thermal excitation process is controllable and meets the requirements of the actual detection scenario. Combining three-dimensional modeling, thermal boundary control, heat transfer theory analysis, and defect judgment logic organically not only ensures the accuracy and reliability of the detection results but also can effectively meet the detection requirements for various shallow surface layer crack defects of epoxy basin insulators in practice.

[0093] Example 2, refer to Figures 3-6, which is an embodiment of the present invention, provides a method for detecting internal crack defects in epoxy composites. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0094] Step 101: Obtain a simplified three-dimensional structure model of an epoxy pot insulator. The three-dimensional structure model includes an epoxy material body and crack defects. The epoxy material body is made of epoxy, and the bubble defects are made of air.

[0095] Step 102: Apply boundary conditions to the epoxy material body and bubble defect structure, and obtain the surface temperatures at the defect and non-defect locations through a solid heat transfer model. Set the heat source excitation power to 10000 W / m 2 , set the heat source excitation time to 6 s, and select boundary heat source control as the excitation method.

[0096] Step 103: Set the crack defect depth and crack defect deflection angle to h and θ, respectively. Analyze the surface thermal imaging characteristics of the epoxy material model by changing the structural parameters multiple times. The control variables are h and θ as shown in Table 1, and obtain the surface temperature difference ΔT between the defect and non-defect locations.

[0097] Table 1 Different crack defect arrangements

[0098]

[0099] Step 104: Apply a heat excitation to the surface of the epoxy pot insulator, calculate the surface temperature difference ΔT between the defect location and the non-defect location, and judge the size of the surface temperature difference ΔT between the defect location and the non-defect location and the defect detection sensitivity TL. If ΔT≥TL, the defect recognition requirement is met, and the defect can be detected. If ΔT<TL, the defect recognition requirement is not met, and the defect cannot be detected.

[0100] Step 105: Repeat the above steps to detect crack defects with different depths and different deflection angles in the shallow surface layer within 2 mm depth.

[0101] Example 3, which is an embodiment of the present invention, provides a method for detecting internal crack defects in epoxy composites, and provides the basis for selecting the parameters of "heat source excitation power of 10000 W / m2 and heat source excitation time of 6 s" in the present invention, and scientific demonstration is carried out through experiments.

[0102] Through simulation experiments, it is found that as the power of the excitation heat source increases and the excitation time increases, the detection effect becomes more significant, but when it reaches a certain value, the detection effect no longer changes significantly. At this time, the excitation heat source power is 10000 W / m 2 , and the excitation time is 6 s.

[0103] Table 2 Defect surface temperature values at each power

[0104]

[0105]

[0106] Table 3. Defect surface temperature values ​​at various excitation times.

[0107]

[0108]

[0109]

[0110] As the excitation power increases, the material temperature rises. However, due to the heat transfer effect, heat diffuses from the high-temperature region to the low-temperature region. Defect points have lower thermal conductivity, resulting in a slower temperature rise around them, while non-defect points have higher thermal conductivity and a faster temperature rise. Although the absolute peak temperature at the defect point increases, the relative temperature between the defect point and the non-defect point decreases. Table 2 shows the defect surface temperature values ​​at various power levels. Based on the change in the surface temperature at the defect point over time, the half-width at each excitation power was calculated. At an excitation power of 10000 W / m², the half-width is relatively large, indicating that the temperature decreases slowly after reaching its peak. This suggests that the material responds slowly to heat input and dissipates heat slowly. A larger temperature difference peak value is beneficial for defect detection, while a larger half-width helps avoid missed defects. Considering both, a larger excitation power of 10000 W / m² is preferable. 2 The excitation power can effectively detect defects and ensure the detection integrity rate.

[0111] As the excitation time increases, both the peak surface temperature at the defect and the baseline temperature at the non-defect location increase. Table 3 shows the temperature values ​​collected within ±5 mm of a horizontal line along the surface with the defect center as the origin. The temperature difference between the defect and the non-defect location is calculated using the baseline and peak temperatures within this range. The temperature difference between the defect and the non-defect location increases from 0.09℃ to 1.65℃.

[0112] According to the principle of heat diffusion:

[0113]

[0114] In the formula, L is the thermal diffusion distance, α is the thermal diffusivity, and t is the time. As the excitation time increases, the diffusion distance and the degree of ambiguity of the defect boundary also increase, and the affected surface area increases from 2.95 mm. 2 Increased to 19.16mm 2 The affected area increases significantly, and an excessively large affected surface area is not conducive to the identification of defect size. Therefore, choosing a 6s excitation time can both ensure the determination of defect location and obtain a relatively clear defect boundary.

[0115] Example 4 is an embodiment of the present invention, including,

[0116] This embodiment also provides an electronic device applicable to a method for detecting internal crack defects in epoxy composite materials, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for detecting internal crack defects in epoxy composite materials as proposed in the above embodiment.

[0117] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a method for detecting internal crack defects in epoxy composite materials as proposed in the above embodiments.

[0118] The storage medium proposed in this embodiment belongs to the same inventive concept as the method for detecting internal crack defects in epoxy composite materials proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0119] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0120] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for detecting internal crack defects in epoxy composite materials, characterized in that, include: The structural parameters of the 110kV epoxy basin insulator were measured, and a three-dimensional structural model with the same scale as the physical object was constructed using three-dimensional modeling software. Thermal boundary conditions are applied to the three-dimensional structural model, and the depth and deflection angle of the crack defects are set, and the material properties of the bubble defect region are set. Based on the solid heat transfer theory, the surface thermal imaging characteristics of the epoxy basin insulator at the defect location are obtained and output.

2. The method for detecting internal crack defects in epoxy composite materials as described in claim 1, characterized in that, The three-dimensional structural model includes: Metal flange, center insert, epoxy body; Metal flanges connect the epoxy resin body to external equipment via mechanical means. The central insert provides an electrical connection interface; The epoxy matrix provides overall insulation performance and mechanical support strength.

3. The method for detecting internal crack defects in epoxy composite materials as described in claim 2, characterized in that, Applying thermal boundary conditions to the three-dimensional structural model includes: Apply thermal boundary conditions to the metal flange, center insert, and epoxy body; The convex surface of the epoxy basin insulator is designated as the thermal excitation application surface, i.e., the detection surface, and a heat flux density of 10000 W / m is applied to this surface. 2 The heat source excitation lasts for 6 seconds; The concave surface is set as the adiabatic boundary, assuming that heat flow cannot be transferred through this surface, so as to achieve unidirectional heat conduction.

4. The method for detecting internal crack defects in epoxy composite materials as described in claim 3, characterized in that, The method for obtaining surface thermal imaging features at defects in epoxy basin insulators based on solid heat transfer theory includes: Set the surface temperature acquisition range; The surface thermal imaging characteristics of epoxy basin insulators are characterized by the surface temperature difference between defective and non-defective regions. Based on the thermal circuit theory, the relationship between the surface temperature at the defect and the surface temperature at the non-defect is derived, and the difference between the surface temperature at the defect and the surface temperature at the non-defect is determined.

5. The method for detecting internal crack defects in epoxy composite materials as described in claim 4, characterized in that, The setting of the surface temperature acquisition range includes: The temperature acquisition range includes the surface temperature at the defect and the surface temperature at the non-defect location, and the defect detection sensitivity TL is set.

6. The method for detecting internal crack defects in epoxy composite materials as described in claim 5, characterized in that, The method of characterizing the surface thermal imaging features of epoxy basin insulators by measuring the surface temperature difference between defective and non-defective regions includes: The surface thermal imaging characteristics of epoxy basin insulators can be characterized by the surface temperature difference between defective and non-defective regions, where the temperature difference is defined as: ΔT=Tqc-Tf In the formula, the surface temperature at the defect is Tqc, the surface temperature at the non-defect is Tf, and ΔT represents the temperature difference between the defective and normal parts in the infrared thermogram.

7. The method for detecting internal crack defects in epoxy composite materials as described in claim 6, characterized in that, The relationship between the surface temperature at the defect and the surface temperature at the non-defect location, derived from thermal circuit theory, includes: According to thermal circuit theory, the heat flow Q through the thermal resistance is: In the formula, Q represents heat flow, ΔT is the temperature gradient, and R is the thermal resistance; According to the principle of heat flow continuity, under steady-state conditions, the heat flow on any heat conduction path must be continuous. The heat flow through any cross-section is equal between different materials or regions at the same time, and the heat flow Q through cross-section S per unit time remains constant. Let the upper surface temperature of the tested sample be T1, the cross-sectional temperature be T2, and the heat flow direction be mainly from top to bottom. In the heat path L1, it is composed of two epoxy materials with thermal resistances Rh1 and Rh2, respectively. The total thermal resistance is denoted as R1 = Rh1 + Rh2. In the heat path L2 with bubble defects, the second layer of material is a bubble with a thermal resistance of Rq. The total thermal resistance of this path is R2 = Rh1 + Rq. The thermal conductivity of air in the bubble is much lower than that of epoxy material, Rq > Rh2, therefore R2 > R1. According to the thermal resistance formula: Under the condition that the heat flux Q is the same, the greater the thermal resistance, the greater the temperature gradient ΔT, resulting in an increase in the temperature difference along the path where the bubble defect is located, and the surface temperature of the defect area is higher than that of the defect-free area.

8. The method for detecting internal crack defects in epoxy composite materials as described in claim 7, characterized in that, Judging the temperature difference between the surface temperature at the defect and the surface temperature at the non-defect includes: Judging the magnitude relationship between the temperature difference ΔT between the surface temperature at the defect and the surface temperature at the non-defect and the defect detection sensitivity TL. If ΔT≥TL, the defect recognition requirement is met and the defect can be detected. If ΔT<TL, the defect recognition requirement is not met and the defect cannot be detected.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method described in any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method described in any one of claims 1 to 8.

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