A method for designing an insulating encapsulation layer for an electro-thermal in-situ cured composite shell

Abstract

The application discloses a kind of insulation encapsulation layer design methods for electrothermal in-situ curing composite shell, specifically relates to the field of shell packaging.It includes: determining the curvature of the ellipse at different polar angles;Along the circumference of the closure section, it is symmetrically divided into four petal structures, and each petal structure is divided into at least three sections;Determine the distance from the point on the ellipse at the corresponding polar angle to the short semi-axis as the radius of the profile circle corresponding to the polar angle, and determine the profile arc length of each petal structure at the corresponding polar angle;Determine the elliptic arc length of the point on the ellipse at the corresponding polar angle to the vertex of the short semi-axis, and take it as the radius, determine the central angle according to the profile arc length, radius;According to the profile arc length, central angle, radius, the insulation encapsulation layer of the closure section is obtained by fitting. Through the above method, not only can the wrinkles generated in the process of film laying be reduced, but also the multi-energy field synergistic curing process can be applied to the special-shaped variable-curvature composite shell with feasibility and repeatability.

Description

Technical Field

[0001] This invention relates to the field of housing encapsulation, and more particularly to a design method for an insulating encapsulation layer for an electrothermal in-situ cured composite housing. Background Technology

[0002] Carbon fiber composite shells are core components for achieving lightweight and high-strength structures. Their complex, irregularly shaped curvature significantly increases the difficulty of manufacturing. These shells are typically manufactured using a fiber winding-curing process. For the curing stage, the CNT film electrothermal in-situ curing process offers advantages such as rapid heating rate, good temperature uniformity, and high energy utilization. This process uses an electric field to drive the CNT film to generate Joule heat, thereby initiating a resin curing reaction. It is a multi-energy field synergistic manufacturing technology route involving electric, thermal, and chemical fields, becoming an important technological direction to overcome the limitations of traditional oven curing and improve manufacturing efficiency and quality. During the CNT film electrothermal curing process, CNT film circuits are laid between layers of carbon fiber prepreg and heated by copper foil electrodes, thus enabling the prepreg to gradually cure according to the curing regime. However, under the influence of winding tension, the carbon fiber prepreg is in close contact with the CNT film. When there is a certain angle between the winding direction of the carbon fiber prepreg and the direction of the current inside the CNT film (β≠90°), The electrical conductivity of carbon fiber prepregs easily leads to a significant current diffusion effect in CNT films during energization, preventing the effective confinement of electrical energy within the CNT film. This results in uncontrolled Joule thermal conversion and uneven thermal field distribution, leading to inconsistent curing temperatures and affecting the quality of the composite shell molding. The insulating encapsulation layer, acting as a dielectric barrier, constructs electrical boundaries and blocks the diffusion of current from the CNT film into the carbon fiber prepreg, achieving directional conversion of the electric and thermal fields and controlling temperature uniformity. This is the key physical basis for the multi-energy field synergistic curing process.

[0003] To ensure successful electrothermal curing of the composite shell, introducing a high-performance insulating layer between the CNT film and the carbon fiber prepreg is crucial. Existing technologies use polyimide (PI) film as the encapsulation layer; however, applying PI encapsulation technology to aerospace composite shell manufacturing still faces significant engineering challenges. The end caps of the composite shell are typical ellipsoidal variable curvature irregular structures. Traditional two-dimensional planar PI encapsulation technology is mostly used for flat components. For irregular variable curvature structures like composite shells, it relies heavily on empirical cutting and forced layup, lacking quantitative encapsulation layer design. This leads to wrinkles during curved surface layup, which evolve into delamination defects after curing. Summary of the Invention

[0004] The main objective of this application is to provide a design method for an insulating encapsulation layer for an electrothermal in-situ cured composite housing, which aims to solve the problem that existing encapsulation layer designs are prone to wrinkling during curved surface layup.

[0005] To achieve the above objectives, this application provides a design method for an insulating encapsulation layer of an electrothermal in-situ cured composite shell. The electrothermal in-situ cured composite shell includes a cylindrical section and a head section. The outer contour of the head section is elliptical. The method includes: cutting a polyimide film according to the length and circumferential length of the cylindrical section to obtain the insulating encapsulation layer of the cylindrical section; determining the curvature of the ellipse at different polar angles based on the length of the major semi-axis, the length of the minor semi-axis, and the polar angle; symmetrically dividing the head section into four petal structures along its circumference, and dividing each petal structure into at least three segments according to the curvature of the ellipse; and further dividing the head section into four petal structures based on the length of the major semi-axis, the length of the minor semi-axis, and the polar angle .... The distance from a point on the ellipse at the corresponding polar angle to the minor axis is determined, and this distance is used as the radius of the cross-sectional circle corresponding to that polar angle. Based on the radius of the cross-sectional circle, the length of the cross-sectional arc of each petal structure at the corresponding polar angle is determined. Based on the length of the major axis, the length of the minor axis, and the polar angle, the length of the elliptical arc from a point on the ellipse at the corresponding polar angle to the vertex of the minor axis is determined. Using the length of the elliptical arc from a point on the ellipse at the corresponding polar angle to the vertex of the minor axis as the radius, the central angle is determined based on the length of the cross-sectional arc and the radius. Based on the length of the cross-sectional arc, the central angle, and the radius, the arc of each region is constructed using the concentric circle mapping method, and the fitting is performed to obtain the insulating encapsulation layer of the end cap segment.

[0006] Optionally, each petal structure is divided into at least three regions according to the curvature of the ellipse, including: dividing each petal structure into a near-equatorial segment, a transition segment, and a near-polar hole segment along the axial direction of the end cap segment according to the curvature of the ellipse.

[0007] Optionally, after determining the central angle based on the length and radius of the cross-sectional arc, the method further includes: for each petal structure, reducing the central angle of the near-equatorial segment and increasing the central angle of the near-polar segment.

[0008] Optionally, the expression for the curvature of the ellipse at each polar angle is: ; In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. Let be the curvature of the ellipse at each polar angle.

[0009] Optionally, the expression for the distance from a point on the ellipse at each polar angle to the minor semi-axis is: ; In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. This represents the distance from a point on the ellipse at each polar angle to the minor semi-axis.

[0010] Optionally, the length of the cross-sectional arc of each petal structure at the corresponding polar angle is determined based on the radius of the cross-sectional circle, including: determining the circumference of the cross-sectional circle based on the radius of the cross-sectional circle, and taking one-quarter of the circumference of the cross-sectional circle as the length of the cross-sectional arc of each petal structure at the corresponding polar angle.

[0011] Optionally, the expression for the arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis is: ; In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. The arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis.

[0012] Alternatively, the expression for the central angle is: ; In the formula, For the central angle, The length of the cross-sectional arc at the corresponding polar angle for each petal structure. The arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis.

[0013] Compared with the prior art, the beneficial effects of this application are as follows: The present invention provides a design method for an insulating encapsulation layer for an electrothermal in-situ cured composite housing. This method establishes a quantitative insulating encapsulation layer design based on the irregular curvature characteristics of the composite housing's end cap segment, employing a "four-petal + three-segment + central angle compensation" approach. By circumferentially dividing the end cap segment into four petal structures, and utilizing the radial evolution of the elliptical generatrix curvature, the end cap is divided into three characteristic regions: a near-equatorial segment, a transition segment, and a near-electrode segment. An analytical mapping relationship is established between the three-dimensional spatial curvature of each characteristic region and the two-dimensional arc radius and central angle. This allows for the quantitative calculation of the endpoint coordinates (arc length, radius, and central angle) of each segment's cross-sectional arc, resulting in a two-dimensional unfolded pattern of the insulating encapsulation layer for the end cap segment. This effectively reduces wrinkles caused by curvature variations during film deposition, thereby reducing interface delamination defects induced by wrinkles during curvature. This not only ensures the adhesion of the insulating layer at the irregular curvature end cap but also provides standardized quantitative criteria and implementation paths for the integrated structural-functional encapsulation of high-precision components. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the electrothermal in-situ curing composite shell; Figure 2This is a flowchart illustrating a design method for an insulating encapsulation layer of an electrothermal in-situ cured composite housing according to this application. Figure 3 This is a two-dimensional unfolded view of the insulating encapsulation layer of the end cap segment obtained by the insulating encapsulation layer design method for an electrothermal in-situ curing composite shell according to this application; Figure 4 This is a diagram showing the variation of the elliptical curvature of the end cap segment obtained from the design method of the insulating encapsulation layer for an electrothermal in-situ cured composite shell according to this application. Figure 5 This is a two-dimensional plan view of a single petal structure obtained from the insulating encapsulation layer design method for an electrothermal in-situ cured composite housing according to this application; Figure 6 This is a schematic diagram of the heating circuit of the encapsulated head section obtained by the insulating encapsulation layer design method for electrothermal in-situ curing composite shell of this application; In the figure, 1. Encapsulation layer of the end cap, 2. CNT thin film circuit.

[0015] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] It is worth noting that, such as Figure 1As shown, the electrothermal in-situ curing composite housing includes a cylindrical section and a head section. The head section has an elliptical outer contour. For the insulation layer encapsulation design of the electrothermal in-situ curing composite housing, both the cylindrical section and the head section are encapsulated with polyimide. The cylindrical section uses a single rectangular CNT film to construct the heating circuit, while the head section typically arranges four independent heating circuits. Each heating circuit uses a narrow, meandering circuit of equal width. The encapsulation layer design ensures that each heating circuit is completely covered by the polyimide film. Appropriate gaps are reserved between the circuits in the head section to allow the heating electrodes from the cylindrical section to be led out from this area. The head section is designed with four encapsulation units to maximize the coverage of the polyimide film while ensuring complete coverage of the heating circuit. However, the end cap is an ellipsoidal variable curvature irregular surface that cannot be unfolded into a two-dimensional plane, resulting in a complex encapsulation layer design. Therefore, this invention proposes a non-developable ellipsoidal surface encapsulation layer design method based on "four petals + three segments + central angle compensation", which realizes the leap from empirical tailoring to geometric quantitative design of PI insulation encapsulation, as detailed below.

[0018] Embodiments of the present invention provide a method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing, such as... Figure 2 As shown, the specific steps include: Step S1: Cut the polyimide film according to the length and circumferential length of the cylindrical section to obtain the insulating encapsulation layer of the cylindrical section; Specifically, for the cylindrical section, since the two-dimensional unfolded plane is rectangular, a rectangular polyimide film of length n and width m is simply cut according to the length m and circumferential length n of the cylindrical section to obtain the insulating encapsulation layer for the cylindrical section. A whole rectangular CNT film is used as the heating circuit. The width of the CNT film is smaller than the width of the polyimide film to ensure that the heating circuit can be completely encapsulated. Flat copper wires (copper foil) are used as the electrodes of the heating circuit of the cylindrical section. During encapsulation, the CNT film is first placed over the cylindrical section, and the copper foil is connected to the CNT film using conductive silver paste. Finally, the copper foil and the CNT film are encapsulated together within the polyimide film.

[0019] Step S2: Determine the curvature of the ellipse at different polar angles based on the lengths of the major and minor axes and the polar angle. Specifically, the formula for an ellipse curve is: ; Establish a polar coordinate system on the ellipse, and the curvature of the ellipse at different polar angles is: ; In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. Let be the curvature of the ellipse at each polar angle.

[0020] Step S3, as follows Figure 3 As shown, the end cap is symmetrically divided into four petal structures along its circumference. Based on the curvature of the ellipse, each petal structure is divided into at least three segments. Specifically, the end cap segment is circumferentially divided into four petal structures. Therefore, the specific dimensions of the end cap segment can be determined based on the dimensions of only one petal structure. According to the curvature variation of the ellipse, along the axial direction of the electrothermally cured composite shell, the end cap segment can be divided into multiple segments from the inside out, resulting in multiple concentric cross-sectional circles. Correspondingly, each petal structure is divided into multiple regions. For example, based on the curvature of the ellipse, each petal structure can be divided into a near-equatorial segment, a transition segment, and a near-aperture segment along the axial direction of the end cap segment, resulting in four concentric cross-sectional circles, as shown in its two-dimensional unfolded diagram. Through the above-mentioned circumferential symmetrical partitioning and radial curvature segmentation mapping, the geometric distortion problem in the laying of non-developable curved surfaces is effectively solved.

[0021] Step S4: Based on the length of the major semi-axis, the length of the minor semi-axis, and the polar angle of the ellipse, determine the distance from the point on the ellipse at the corresponding polar angle to the minor semi-axis, which is used as the radius of the cross-sectional circle corresponding to that polar angle; based on the radius of the cross-sectional circle, determine the length of the cross-sectional arc of each petal structure at the corresponding polar angle. Specifically, the expression for the distance from a point on the ellipse at each polar angle to the minor semi-axis is: ; In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. This represents the distance from a point on the ellipse at each polar angle to the minor semi-axis.

[0022] The distance from a point on the ellipse at each polar angle to the minor axis, calculated using the above formula, is actually the radius of the cross-sectional circle corresponding to each polar angle. Therefore, based on the radius of the cross-sectional circle, the circumference of the cross-sectional circle can be determined. One-quarter of this circumference is the arc length of the cross-sectional circle at the corresponding polar angle for each petal structure. The expression is: ; Step S5: Based on the lengths of the major and minor axes and the polar angle of the ellipse, determine the arc length of the ellipse from the point on the ellipse at the corresponding polar angle to the vertex of the minor axis; its expression is: ; In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. bLet be the length of the minor semi-axis of the ellipse. The arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis.

[0023] Step S6: Take the ellipse arc length from the point on the ellipse at the corresponding polar angle to the vertex of the minor semi-axis as the radius, and determine the central angle based on the arc length and radius of the cross section. Specifically, the arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis is the radius of the corresponding section circle. The central angle of each section circle is determined based on the arc length and radius, expressed as: ; In the formula, For the central angle, The length of the cross-sectional arc at the corresponding polar angle for each petal structure. The arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis.

[0024] After determining the central angle based on the above formula, considering the geometric characteristics of the non-developable surface of the elliptical end cap segment, the curvature of the near-equatorial segment is smaller and the surface tends to be flatter. The initial arc length calculated based on the theoretical circumference often has material redundancy, which can easily lead to compressive stress wrinkles during installation. Therefore, the central angle needs to be reduced to decrease the circumferential allowance. Conversely, the curvature of the near-aperture segment increases dramatically, resulting in severe surface bending. The initial theoretical arc length is insufficient to cover its actual spatial extension, which can easily cause excessive film tension or adhesion suspension. Therefore, the central angle needs to be increased to achieve circumferential length compensation. In this embodiment, a compensation coefficient is introduced to compensate for the central angle, obtaining optimized central angles for the near-equatorial and near-aperture segments. The specific size and method of the compensation coefficient vary for different shells and are not specifically limited here.

[0025] Step S7: Based on the arc length, central angle, and radius of the cross section, the arc of each region is constructed using the concentric circle mapping method, and the fitting is performed to obtain the insulating encapsulation layer of the end cap section. Using the optimized central angle, as well as the length and radius of the cross-sectional arc, the arc of each segment is constructed using the concentric circle mapping method. A two-dimensional unfolded pattern is then fitted to this pattern. Based on this pattern, a physical installation verification is performed to complete the encapsulation of the end cap segment. The wrinkle rate of the insulating encapsulation layer and the overall coverage of the insulating encapsulation layer are evaluated using the following formulas: The wrinkle rate and coverage calculation formulas are as follows: ; ; In the formula, S 褶皱 S represents the total area of ​​the folds in the end cap section after the insulating encapsulation layer has been applied. 封装层 S represents the total area of ​​the insulating encapsulation layer of the end cap section. 总封装层 S represents the total area of ​​the encapsulation layer. 复材壳体The surface area of ​​the composite shell is defined as the area of ​​the material that is electrothermally cured in situ.

[0026] After designing the insulating encapsulation layer according to the above method, in the actual fabrication stage, the polyimide film is first precisely cut according to the optimized geometric pattern, and a matching CNT film heating circuit is designed simultaneously to ensure that the CNT film heating circuit adopts a meandering circuit layout with equal width and narrow bands and is completely located within the encapsulation boundary of the PI film. Specific structural gaps need to be reserved between the encapsulation bodies of each petal structure so that the copper foil electrodes of the barrel section can be accurately led out and connected to the circuit. Finally, four sets of encapsulation circuits are symmetrically arranged on each of the end cap sections on both sides, and together with the barrel section circuit, they are attached to the surface of the electrothermal in-situ curing composite shell, thereby constructing an integrated in-situ electrothermal curing system covering the entire component.

[0027] In this embodiment, a quantitative insulating encapsulation layer design method of "four petals + three segments + central angle compensation" was established based on the irregular curvature characteristics of the end cap section of the electrothermal in-situ cured composite shell. By circumferentially dividing the end cap section into four petal structures, the radial evolution of the elliptical generatrix curvature is used to divide the end cap into three characteristic regions: a near-equatorial segment, a transition segment, and a near-electrode segment. An analytical mapping relationship between the three-dimensional spatial curvature of each characteristic region and the two-dimensional arc radius and central angle is established, thereby quantitatively calculating the endpoint coordinates (arc length, radius, and central angle) of each segment's cross-sectional arc, thus obtaining the two-dimensional unfolded pattern of the insulating encapsulation layer of the end cap section. The "central angle compensation mechanism" is introduced, using smooth curves to reconstruct the boundaries of each characteristic region, effectively reducing wrinkles caused by curvature changes during film layup, thereby reducing interface delamination defects induced by wrinkles during curvature. This design method not only ensures the adhesion of the insulating layer at the irregular curvature end cap but also provides standardized quantitative criteria and implementation paths for the integrated structural-functional encapsulation of high-precision components. Polyimide film has advantages such as high temperature resistance up to 240℃ and strong insulation. The maximum curing temperature of carbon fiber composite shell is 160℃. At this curing temperature, polyimide film can maintain a stable insulation effect for a long time, ensuring the normal curing of the electrothermal in-situ curing composite shell.

[0028] The heating circuit encapsulated using the encapsulation layer obtained by this invention is easy to attach to the electrothermal in-situ curing composite shell. Under high winding tension, the polyimide film can protect the heating circuit from damage, improving the success rate of experiments. This encapsulation layer design method is simple, the process is efficient, and the production time of the encapsulation layer is significantly shortened, reducing labor costs and material waste, improving production efficiency, and lowering overall manufacturing costs. Furthermore, the invented insulating encapsulation layer design method ensures the controllable conversion of the electric field to the thermal field. The quantitatively designed insulating encapsulation layer provides a clear electric field boundary for the CNT film heating circuit, completely confining electrical energy within the CNT film heating circuit and directionally converting it into uniform Joule heat. This fundamentally solves the problem of current diffusion and temperature field inhomogeneity caused by the conductivity of carbon fibers in complex components, making the multi-energy field synergistic curing process engineering feasible and repeatable on irregularly shaped variable curvature composite shells.

[0029] Example A composite shell with a diameter of 150mm was selected, and its parameters are shown in Table 1.

[0030] Table 1 Parameters of Ф150mm Composite Shell

[0031] In step S10, a rectangular CNT film with a length of 196 and a width of 487 is cut according to the length m and circumference n of the cylindrical section. A flat copper foil with a width of 10 mm and a thickness of 0.05 mm is selected as the electrode. The copper foil is attached to both ends of the CNT film along the axial direction of the cylindrical section, and the two are connected by conductive silver paste. Then, the CNT film and the copper foil are encapsulated together inside the polyimide film.

[0032] Step S20: Based on the lengths of the major and minor axes and the polar angle of the ellipse, determine the curvature of the ellipse at different polar angles, see... Figure 4 .

[0033] In step S30, the end cap segment is symmetrically divided into four petal structures along its circumference. Based on the curvature of the ellipse, each petal structure is divided into three segments with corresponding polar angles of 45°, 60°, 75°, and 90°.

[0034] Step S40: Based on the length of the major semi-axis, the length of the minor semi-axis, and the polar angle of the ellipse, determine the distance from the point on the ellipse at the corresponding polar angle to the minor semi-axis, which is used as the radius of the cross-sectional circle corresponding to the polar angle; based on the radius of the cross-sectional circle, determine the length of the cross-sectional arc of each petal structure at the corresponding polar angle. Step S50: Based on the length of the major semi-axis, the length of the minor semi-axis, and the polar angle of the ellipse, determine the elliptical arc length from the point on the ellipse at the corresponding polar angle to the vertex of the minor semi-axis. Step S60: Take the elliptical arc length from the point on the ellipse at the corresponding polar angle to the vertex of the minor semi-axis as the radius, and determine the central angle based on the arc length and radius of the cross section.

[0035] The cross-sectional arc length, elliptical arc length, and central angle at different polar angles obtained through steps S40-60 are shown in Table 2. Table 2 Two-dimensional plane parameters at different polar angles

[0036] Step S70: Based on the arc lengths W(90°), W(75°), W(60°), and W(45°) and their corresponding central angles obtained above, the concentric circle method is used to draw each arc segment with radii L(90°), L(75°), L(60°), and L(45°), respectively. Finally, the two endpoints of the arcs are connected by a smooth curve to obtain the initial two-dimensional unfolded petals. Since the ellipsoidal surface has a variable curvature structure, the curvature at the equator is small, the surface tends to be flat, and the required circumferential unfolding length is small; the curvature at the pole is the largest, the surface is most severely curved, and the required circumferential unfolding length is large. Therefore, a central angle compensation design is performed for different segments to reduce wrinkles. Using the initial α(θ) as a reference, the central angles of α(90°) and α(75°) are appropriately reduced to decrease the circumferential arc length near the equator, and the central angles of α(90°) and α(75°) are appropriately increased to obtain the final central angles. , , , See Table 2. The values ​​are L(90°), L(75°), L(60°), L(45°), and... , , , Draw the corresponding two-dimensional planar arc for each segment, and finally connect the endpoints of each arc with a smooth curve to obtain the final two-dimensional unfolded pattern of the petal structure, as shown below. Figure 5 As shown in Table 3, the wrinkle rate before and after central angle compensation was verified.

[0037] Table 3. Parameters of a single petal pattern before and after compensation in Example 1

[0038] Step S80: Based on the two-dimensional unfolded pattern of the petal structure obtained in the above steps, cut the polyimide film to obtain the end cap segment encapsulation layer 1, and design the corresponding CNT film circuit 2 according to the shape of the polyimide film, ensuring that the CNT film circuit 2 is inside the polyimide film. Then, encapsulate the CNT film circuit 2, as shown below. Figure 6As shown. A certain gap is reserved between the CNT thin film circuits 2 between each petal structure to ensure that the electrodes of the cylinder section are led out from this gap. Finally, four sets of CNT thin film circuits 2 are symmetrically arranged on each of the end cap sections on both sides, and are attached to the shell surface together with the cylinder section circuits.

[0039] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for designing an insulating encapsulation layer for an electrothermal in-situ cured composite housing, the electrothermal in-situ cured composite housing comprising a cylindrical section and a head section, the head section having an elliptical outer contour shape, characterized in that, The methods include: Cut the polyimide film according to the length and circumferential length of the cylindrical section to obtain the insulating encapsulation layer of the cylindrical section; Determine the curvature of the ellipse at different polar angles based on the lengths of its major and minor axes and its polar angle. The end cap is symmetrically divided into four petal structures along its circumference, and each petal structure is divided into at least three segments according to the curvature of the ellipse. Based on the lengths of the major and minor axes of the ellipse and the polar angle, determine the distance from the point on the ellipse at the corresponding polar angle to the minor axis, which is then used as the radius of the cross-sectional circle corresponding to that polar angle. Based on the radius of the cross-sectional circle, determine the length of the cross-sectional arc at the corresponding polar angle for each petal structure; Based on the lengths of the major and minor axes and the polar angle of the ellipse, determine the arc length of the ellipse from the point on the ellipse at the corresponding polar angle to the vertex of the minor axis. Take the ellipse arc length from the point on the ellipse at the corresponding polar angle to the vertex of the minor semi-axis as the radius, and determine the central angle based on the arc length and radius of the cross section. Based on the arc length, central angle, and radius of the cross section, the arc of each region is constructed using the concentric circle mapping method, and the insulating encapsulation layer of the end cap is obtained by fitting.

2. The method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing according to claim 1, characterized in that, Based on the curvature of the ellipse, each petal structure is divided into at least three regions, including: Based on the curvature of the ellipse, each petal structure is divided into a near-equatorial segment, a transition segment, and a near-polar hole segment along the axial direction of the end cap.

3. The method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing according to claim 2, characterized in that, After determining the central angle based on the length and radius of the cross-sectional arc, the process also includes: For each petal structure, decrease the central angle of the near-equatorial segment and increase the central angle of the near-polar segment.

4. The method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing according to claim 1, characterized in that, The expression for the curvature of the ellipse at each polar angle is: ； In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. Let be the curvature of the ellipse at each polar angle.

5. The method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing according to claim 1, characterized in that, The expression for the distance from a point on the ellipse at each polar angle to the minor semi-axis is: ； In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. This represents the distance from a point on the ellipse at each polar angle to the minor semi-axis.

6. The method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing according to claim 1, characterized in that, Based on the radius of the cross-sectional circle, determine the length of the cross-sectional arc at the corresponding polar angle for each petal structure, including: Determine the circumference of the cross-sectional circle based on its radius, and take one-quarter of the circumference of the cross-sectional circle as the arc length of the cross-sectional circle at the corresponding polar angle for each petal structure.

7. The method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing according to claim 1, characterized in that, The expression for the arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor axis is: ； In the formula, θ The polar angle of the ellipse. Let be the length of the semi-major axis of the ellipse. b Let be the length of the minor semi-axis of the ellipse. The arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis.

8. The method for designing an insulating encapsulation layer for an electrothermally in-situ cured composite housing according to claim 1, characterized in that, The expression for a central angle is: ； In the formula, For the central angle, The length of the cross-sectional arc at the corresponding polar angle for each petal structure. The arc length of the ellipse from a point on the ellipse at each polar angle to the vertex of the minor semi-axis.

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