High-storage-ratio folding method for large conical film structure

Abstract

The invention discloses a high-storage-ratio folding method for a large conical film structure, and belongs to the technical field of space debris removal and satellite light shields. The problems that an existing plane deorbit sail is poor in attitude stability and low in deorbit efficiency are solved. Comprising the following steps: S1, drawing equidistant circumferential folding lines on a conical film structure, wherein the circumferential folding lines comprise a circumferential ridge line and a circumferential valley line; s2, circumferential folding is carried out, axial compression is carried out along the axis of the cone, and then circumferential contraction is carried out; and S3, folding from a cone to a cylinder. The three-dimensional conical film sail can be folded into the three-dimensional conical film sail which is high in posture stability, relatively high in unfolding reliability and capable of correcting the posture, and the folding efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of space debris removal and satellite sunshades, and particularly relates to a high storage ratio folding method for a large conical film structure. Background Art

[0002] Traditional planar deorbiting sail technology has the following shortcomings: 1. Due to the irregular rotation of satellites during deorbiting, the effective deorbiting area of ​​the planar deorbiting sail, that is, the area projected in the direction of the velocity vector, is likely to approach zero due to the rotation of the failed satellite, thereby significantly reducing the deorbiting effect of the planar sail; 2. Due to its air resistance shape characteristics, it is difficult for the planar deorbiting sail to always deorbit with the maximum effective area. The aerodynamic shape of the conical membrane sail enables the satellite to automatically correct its attitude, so that the abandoned satellite can always deorbit with the maximum effective area; 3. Even if the conical membrane sail undergoes an uncontrollable flip, it can ensure that it has a certain effective area to participate in deorbiting. Summary of the Invention

[0003] In order to solve the problems of poor attitude stability and low deorbit efficiency of existing planar deorbiting sails, the present invention provides a high storage ratio folding method for a large conical film structure.

[0004] The technical solution adopted by the present invention is:

[0005] A high storage ratio folding method for a large conical film structure comprises the following steps:

[0006] S1. Draw equidistant annular fold lines on the conical membrane structure, including annular ridge lines and annular valley lines;

[0007] S2. Circumferential folding is performed, first by axial compression along the cone axis, and then by circumferential contraction;

[0008] S3. Fold from cone to cylinder.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] The present invention can be folded into a three-dimensional conical film sail with strong posture stability, relatively high unfolding reliability, and the ability to correct posture, and has high folding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the folding and contraction of the conical membrane structure;

[0012] Figure 2 This is a design diagram of a one-time folding method for a conical membrane structure;

[0013] Figure 3 It is a folding design from cone to cylinder;

[0014] Figure 4 This is a diagram of the conical film folding experiment. DETAILED DESCRIPTION

[0015] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.

[0016] This invention primarily addresses aerospace missions involving three-dimensional conical membrane structures, such as conical sunshades, that can be deployed to rapidly increase resistance and deorbit low-orbit satellites at the end of their lifespans. The increasing amount of space debris poses a threat to the space environment. Therefore, there is an urgent need to develop a low-cost, three-dimensional deorbit membrane sail device that can be deployed and formed after the mission is completed, passively deorbiting the satellite using the drag of rarefied gases. Therefore, the key technology for achieving a high-folding ratio for a three-dimensional conical deorbit membrane sail is to fold it. Deployable membrane structures offer significant advantages in terms of low system mass, small storage space, and high folding-to-expanding ratio. Therefore, deployable membrane structures have become a key area of ​​aerospace development. In practical applications, deployable membrane structures typically require orderly folding and compact packaging on the ground. After the satellite completes its mission, the conical membrane structure is deployed using various methods, such as inflation, mechanical force, or shape memory, to rapidly deorbit the decommissioned satellite and cause it to fall into the atmosphere and burn up as quickly as possible. This approach can reduce the amount of space debris in a specific orbit, protect the space environment, and ensure the long-term sustainability of human space activities.

[0017] The present invention relates to the technical field of space debris removal and satellite sunshades, and is particularly suitable for the design of a passive deorbit device for low-Earth orbit satellites at the end of their service life. Through geometric three-dimensional structure design and origami design folding, a high storage ratio folding storage of any conical film sail is achieved.

[0018] The present invention is a centripetal progressive origami topology design that combines radial contraction with circumferential contraction.

[0019] The scheme of combining radial contraction with circumferential contraction is adopted, and it is achieved through multi-level nested folding:

[0020] a. Nesting of arbitrary conical membrane sails and folding them layer by layer;

[0021] b. With the help of the central tube, any conical membrane sail can be folded into a cylindrical shape.

[0022] Any conical film can be completely defined by its semi-apex angle α and base radius r, which gives the equation of the conical surface as:

[0023] (1.1)

[0024] In order to facilitate the study of folding schemes, the conical flexible film is projected along its axis to obtain a complete circular plane. According to the limitation of the folded envelope height h (since the folded film needs to be packed into a packaging box, the height of the packaging box is a fixed value h, and the radius r of the folded cylinder is difficult to estimate, while h is easier to control according to the number of folded equal parts. Therefore, here the number of equal parts n is determined based on h to ensure that the height of the folded cylinder meets the height limit of the packaging box so that it can be placed in the packaging box), it is necessary to divide the main line of the cone to be folded into n equal parts, and draw C1 to C n These n circles, such as Figure 1 As shown in (a) and (c), the distance between the intersection points M1 and M2 of the circumferential folding line and the zoy plane is less than the height h between the packaging boxes. According to equation (1.1), the coordinates of M2 satisfy: , in this way, the horizontal coordinate of the intersection of any annular folding line and the zoy plane can be obtained: , and with this, equidistant annular fold lines can be drawn, including annular ridge lines and annular valley lines. Then, C can be calculated i with C i+2 The perimeter difference is: ,The folding idea is to first compress axially along the axis of the cone, and then shrink circumferentially through the designed folding method.

[0025] When performing circumferential folding, the number of circumferential foldings needs to be determined based on actual conditions to ensure that the circumferential folding lines do not intersect with each other.

[0026] The specific single hoop folding design method is as follows: Figure 2 As shown, we first need to calculate the difference in the circumference of the two circles folded together, assuming the circumference is C i , C i-2 , then the perimeter difference is calculated according to the above, , determine the number of circumferential folds required to be k (k>3, an integer), and calculate based on the number of circumferential folds, the side length of each folding triangle is: , the specific folding scheme is as follows Figure 2 As shown in (a)(b)(b)(d), first, find C i , C i-2 The middle circle C between the two circles i-1 , and then move the outer edge of the cone along the middle circle C i-1 Fold it, and then calculate the folded triangle side length l ab Fold each small triangle and you will get Figure 2 (d) The morphology shown.

[0027] Will Figure 2 The small cone shown in (d) is turned inside out and can be obtained as follows Figure 2(a) shows a small cone. Repeat this step and fold it repeatedly, so that the cone surface is continuously reduced, and finally the cone is folded to a cylinder. Obviously, after the number of folds k in the annular direction and n in the axial direction is determined, the l of the folded triangle is ab is a constant, so that all the circumferential fold lines that need to be folded can be drawn at once, such as Figure 1 As shown in (a).

[0028] The next step is to fold from cone to cylinder, and we get Figure 2 After the small cone shown in (d), first turn the top of the cone over to obtain Figure 3 (a) Calculate the difference in perimeter between the upper and lower sides l2, and divide it into n equal parts according to the number of folds to calculate the length of the short side l of the folded small triangle ABC. BC = l2 / n Figure 3 (b), fold it to obtain Figure 3 (c) The cylindrical configuration is then folded along its outer edge toward the center to obtain Figure 3 (d) The radial cylindrical configuration is then rolled into the final folded state according to the Archimedean spiral. Figure 3 As shown in (e), similarly, in this step, the folding line can be drawn in advance on the top layer of the cone, as shown in Figure 1 As shown in (a).

[0029] In terms of specific operations, the film is first cut according to needs, and the folding lines are drawn according to the folding design, and then the folding operation is performed. This article conducted a folding experiment on a polyimide conical film with a diameter of 3m and a half-vertex angle of 45°, and successfully folded it into a smaller cylinder.

[0030] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A high storage ratio folding method for a large conical film structure, characterized by: The following steps are involved: S1. Draw equidistant annular fold lines on the conical membrane structure, including annular ridge lines and annular valley lines; S2. Circumferential folding is performed, first by axial compression along the cone axis, and then by circumferential contraction; S3. Fold from cone to cylinder.

2. A high storage ratio folding method for a large conical membrane structure according to claim 1, characterized in that: The specific process of drawing equidistant annular folding lines in S1 is as follows: The equation of the conical surface is: （1.1） S11. Projecting the conical flexible film along its axis to obtain a complete circular plane; S12. According to the limit of the folding envelope height h, divide the generatrix of the cone to be folded into n equal parts, and draw C1 to C n These n circles make the distance between the intersection points M1 and M2 of the annular folding line and the zoy plane less than the height h of the packaging box; S13. According to equation (1.1), the coordinates of M2 satisfy: , we can get the horizontal coordinate of the intersection of any annular folding line and the zoy plane: , and the equidistant annular folding lines can be drawn, including the annular ridge line and the annular valley line, and then C can be calculated. i with C i+2 The perimeter difference is: .

3. The high storage ratio folding method of a large conical membrane structure according to claim 2, characterized in that: The specific single hoop folding design method in S2 is: Calculate the difference in circumference of the two circles folded together, let the circumference be C i , C i-2 , then the perimeter difference is calculated according to the above, , determine the number of circumferential folds required to be performed as k, k>3, which is an integer. According to the number of circumferential folds, the side length of each folding triangle is calculated as: .

4. The high storage ratio folding method of a large conical membrane structure according to claim 3, characterized in that: The specific folding scheme in S2 is: Find C i , C i-2 The middle circle C between the two circles i-1 , and then move the outer edge of the cone along the middle circle C i-1 Fold it, and then calculate the folded triangle side length l ab Fold each small triangle, and after completing a single circumferential fold, turn the small cone inside out and repeat the single circumferential fold again. Repeat this folding process until the cone surface continues to shrink, and finally the cone is folded to transition to a cylinder.

5. The high storage ratio folding method of a large conical membrane structure according to claim 4, characterized in that: In S3, the folding from cone to cylinder is performed as follows: the top of the cone is turned over to obtain the initial configuration, the perimeter difference between the upper and lower sides l2 is calculated, and the short side length l of the folded small triangle ABC is calculated by dividing it into n parts according to the number of folding times. BC =l2 / n, fold it over to get a cylindrical configuration, then shrink and fold the cylinder along its outer edge toward the center to get a radial cylindrical configuration, and then curl it into the final folded state according to the Archimedean spiral.

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