Deployable shade structure based on shape memory material and its molding and deploying method

Abstract

This invention relates to the field of space deployable structure technology, and more particularly to a deployable light-shielding structure based on shape memory materials and its shaping and deployment method. The structure comprises an outer frame and an inner light-shielding cover. The outer frame consists of a top frame, a bottom frame, and multiple shape memory L-shaped beams connecting the two, forming a frustum-shaped boundary after unfolding. The number of inner light-shielding covers matches the sides of the frame; each includes a fan-shaped shape memory skeleton with concentric annular curved lines and a light-shielding cloth. The skeleton can be folded along the curved lines into a radially corrugated laminated ring shell to achieve ultra-high axial compression, and after heating, it can be deterministically unfolded into a planar fan-shaped ring to fill the boundary. This invention adopts a two-stage unfolding method of "boundary first, then filling." This structure integrates the geometric determinism, high folding-to-unfold ratio, and high energy storage characteristics of curved origami with the active controllability of shape memory materials, possessing advantages such as lightweight, high reliability, high precision, smooth and impact-free unfolding, and customizable structure.

Description

Technical Field

[0001] This invention relates to the field of space deployable structure technology, and in particular to a deployable light-shielding structure based on shape memory material and its shaping and deployment method. Background Technology

[0002] The sunshade structure is a critical protective mechanism used by spacecraft to shield them from direct sunlight and stray radiation during their on-orbit operation. This structure is typically located in front of optical payloads or sensitive detection equipment, and its core function is to isolate strong light and thermal radiation interference, providing a long-term, stable dark environment and thermal equilibrium for precision instruments. This directly affects the accuracy of observational data and the lifespan of the equipment.

[0003] Due to the extremely limited space in the launch vehicle fairing, the sunshade must be compressed or folded to its minimum volume during launch to meet stringent launch envelope restrictions. After the spacecraft enters its designated orbit, it must be deployed via ground or onboard commands and ultimately reliably locked into its predetermined configuration, forming a reliable barrier with specific shading angles, protection range, and surface accuracy.

[0004] With the continuous development of space science observation, Earth remote sensing, and deep space exploration missions, the requirements for the resolution, sensitivity, and thermal stability of optical systems are increasing, posing unprecedented comprehensive challenges to the structural design of light shields: First, the structure must be highly reliable to ensure successful deployment on the first attempt and long-term shape and position retention. Any deployment failure or deformation after deployment could lead to the failure of the entire optical mission.

[0005] Secondly, the structure must possess excellent vibration suppression and shock resistance capabilities to withstand the severe mechanical environment during the launch phase and maintain structural stability under orbital micro-vibrations.

[0006] Furthermore, while meeting functional requirements, it is essential to achieve extreme lightweighting and high rigidity to conserve valuable launch weight and provide a stable support foundation for optical payloads, enabling them to withstand the long-term challenges of the extreme space environment.

[0007] Faced with the aforementioned complex requirements, traditional rigid deployment mechanisms based on mechanical transmission components such as hinges, linkages, and springs are increasingly showing their limitations: they are complex in structure, heavy in mass, relatively unreliable, and may generate impacts or asynchronous phenomena during deployment.

[0008] Therefore, developing a new type of deployable light shield technology that is simpler and more reliable in principle, can achieve a larger folding-to-spread ratio, has a smoother unfolding process, and can balance high rigidity and surface accuracy after unfolding has become a clear and urgent technological development direction in the field of aerospace optics. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing deployable light shield technology in terms of reliability, folding ratio, deployment accuracy and rigidity after deployment, and to provide a deployable light shield structure and method based on shape memory material.

[0010] To achieve the above objectives, in a first aspect, the present invention provides a deployable light-shielding structure based on shape memory material, comprising: The external frame structure includes a top frame, a bottom frame, and multiple shape memory L-shaped beams connecting the top frame and the bottom frame. When fully unfolded, the external frame structure forms a truncated pyramidal spatial boundary. The internal light shield structure is multiple and corresponds to the side of the space boundary. Each internal light shield structure includes a fan-shaped shape memory skeleton and a light shielding cloth connected to the shape memory skeleton. The shape memory skeleton is provided with concentric ring-shaped curves. The skeleton can be folded and gathered along the curves into a radially corrugated stacked ring shell structure, and can be unfolded into a planar fan-shaped ring under thermal excitation to fill the spatial boundary. The creases are concentric annular grooves cut at fixed intervals on the fan-shaped annular plate of the shape memory skeleton, and the material thickness at the grooves is less than the thickness of the skeleton body.

[0011] Optionally, when the shape memory L-shaped beam is in the folded state, the fixed sections at both ends connected to the top frame and the bottom frame can maintain their shape, while the part between the fixed sections can deform, so that the two originally perpendicular plates can change to a state of being parallel or nearly parallel to each other.

[0012] Optionally, the shape memory L-shaped beam has a clearance groove along its length at the inner corner connection of its two plates. The clearance groove makes the material at the connection easy to deform when the beam is bent, thereby realizing the transformation of the two plates from a perpendicular state to a parallel or nearly parallel state.

[0013] Optionally, the clearance groove is a V-shaped groove, a U-shaped groove, an arc-shaped groove, or a rectangular groove, and its depth is such that the remaining material thickness at the connection is less than the thickness of the main plate of the L-shaped beam.

[0014] Optionally, the corners of the top frame and the bottom frame are provided with mounting grooves, and the two ends of the shape memory L-shaped beam are respectively embedded and fixed in the corresponding mounting grooves; The shape memory L-shaped beam is fixedly connected to the top frame and the bottom frame by bolts that pass through the side wall of the mounting groove and the end of the L-shaped beam.

[0015] Optionally, the external frame structure is a frustum-shaped quadrangular frame, and the number of shape memory L-shaped beams is four, which are respectively connected to the four corners of the top frame and the bottom frame.

[0016] Optionally, the shape memory skeleton is made of shape memory polymer composite material, with a heater attached to its surface, and the bottom center of the shape memory skeleton is fixed to the bottom frame by bolts; and / or The shape memory L-shaped beam is made of shape memory polymer composite material, and a heater is attached to its surface.

[0017] Optionally, the deployable light-shielding structure also includes a locking device for locking the relative position of the inner light-shielding structure with the outer frame structure after the inner light-shielding structure is fully deployed; The locking device includes magnetic material disposed on the outer edge of the shape memory skeleton and at corresponding positions of the top frame and bottom frame.

[0018] In a second aspect, the present invention also provides a method for shaping the deployable light-shielding structure for any implementation of the first aspect, comprising the following steps: Shape memory L-shaped beam shaping: Heat it to above its glass transition temperature, apply external force to change the two plates from a vertical state to a parallel or nearly parallel state, and further bend the whole into a predetermined folded shape, and then cool it below the glass transition temperature to fix the shape; Shape memory skeleton shaping: It is heated to above its glass transition temperature, folded along its curves and gathered into a radially corrugated stacked ring shell structure, and then cooled to below its glass transition temperature for shaping.

[0019] Thirdly, the present invention also provides a method for controlling the deployment of a deployable light-shielding structure according to any implementation of the first aspect, comprising the following steps performed sequentially: S1. Apply a first thermal excitation to the multiple shape memory L-shaped beams to drive them to recover from the folded state to the unfolded state, so that the top frame moves to the predetermined working position and establishes the pyramidal spatial boundary. S2. After step S1 is completed, a second thermal excitation is applied to the shape memory skeleton of each of the internal light shield structures in sequence, driving it to unfold from a corrugated shell-like state into a planar fan-shaped ring, filling the side of the spatial boundary.

[0020] The above-described technical solution of the present invention has the following advantages: The deployable light-shielding structure provided by this invention solves the challenge of simultaneously achieving a high fold-to-fold ratio and high deployment accuracy in spatial light-shielding structures through a modular design of an external frame structure and an internal light-shielding cover structure. The external frame, driven by shape-memory L-shaped beams, can pre-deploy and precisely construct a rigid frustum-shaped workspace boundary, serving a defining and guiding function. The internal light-shielding cover employs a unique annular curved origami skeleton; the geometric design of its curved lines endows the skeleton with a deterministic folding / deploying motion path and extremely high axial compression capability, allowing it to seamlessly fill the established boundary. The decoupled yet synergistic function of these two components ensures both a high fold-to-fold ratio and the accuracy and repeatability of the final deployed form, while avoiding motion interference between components, significantly improving system reliability. Simultaneously, the "bending strain energy" stored in the folded state provides a greater driving force reserve for on-orbit self-deployment, making the deployment process smooth and highly controllable.

[0021] The shaping method for the unfoldable light-shielding structure provided by this invention offers a repeatable and mass-producible shape setting process, ensuring the consistency of the product's folded state.

[0022] The unfolding control method for the unfoldable light-shielding structure provided by this invention ensures low impact, high synchronization, and high precision of the final configuration during the unfolding process. Attached Figure Description

[0023] The accompanying drawings are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not be consistent with the actual product.

[0024] Figure 1 This is a schematic diagram of the retracted state of an expandable light-shielding structure according to an embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of the unfolded light-shielding external frame structure. Figure 3 yes Figure 1 A schematic diagram of the unfolded light-shielding structure in its unfolded state; Figure 4 This is a schematic diagram of the unfolded state structure of a shape memory L-shaped beam according to an embodiment of the present invention; Figure 5 yes Figure 4 A schematic diagram of the cross-section of a shape memory L-shaped beam; Figure 6 yes Figure 4 A schematic diagram of the structure of a shape memory L-shaped beam after the two plates are closed. Figure 7 yes Figure 6 A schematic diagram of the cross-section of a shape memory L-shaped beam; Figure 8 yes Figure 6A schematic diagram of a bending state of a shape memory L-shaped beam; Figure 9 This is a schematic diagram illustrating the process of a shape memory skeleton changing from a folded state to an unfolded state in an embodiment of the present invention; Figure 10 yes Figure 9 A schematic diagram of the longitudinal section of the shape memory skeleton in each state as it transitions from the collapsed state to the unfolded state. Figure 11 This is a schematic diagram of one state of an internal light shield structure in an embodiment of the present invention; Figure 12 yes Figure 11 Enlarged schematic diagram of part A in the diagram.

[0025] In the picture: 1: External frame structure; 11: Top frame; 12: Bottom frame; 13: Shape memory L-shaped beam; 131: Clearance groove; 2: Internal light shield structure; 21: Shape memory skeleton; 211: Curves; 22: Blackout cloth. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] See Figures 1 to 3 As shown, the deployable light-shielding structure based on shape memory material provided in this embodiment of the invention includes an outer frame structure 1 and an inner light-shielding structure 2.

[0028] The external frame structure 1 includes a top frame 11, a bottom frame 12, and multiple shape-memory L-shaped beams 13 connecting the two. When unfolded, the frame forms a frustum-shaped spatial boundary (see...). Figure 2 and Figure 3 The number of internal light-shielding structures 2 is the same as the number of sides of the frame, and each includes a fan-shaped shape memory skeleton 21 and a light-shielding cloth 22. In this embodiment, the light-shielding cloth 22 is disposed inside the shape memory skeleton 21 (see...). Figure 12 The shape memory skeleton 21 has concentric annular curved lines 211 (see...). Figure 12The frame is formed by annular grooves cut into a flat fan-shaped plate, with the thickness at the grooves being less than that of the main body. The frame can be folded along the curves into a radially corrugated, multi-layered ring-shell structure, and can unfold into a planar fan-shaped ring upon heating (see...). Figure 9 and Figure 10 The unfolding process in this embodiment is as follows: first, the outer frame structure 1 is driven to unfold, and then the inner light shield structure 2 is driven to unfold.

[0029] The deployable light-shielding structure in this embodiment combines shape memory polymer composite material with an origami-like configuration, eliminating the need for complex mechanical transmission mechanisms. This results in a compact, lightweight structure, and the material itself can withstand the space environment. It employs a two-stage deployment paradigm: "first establish boundaries, then fill in systematically." The outer frame deploys first to form precise boundaries, and the inner light-shielding shield then deploys under its constraints, avoiding mutual interference. The deployment process is highly synchronized, smooth, and impact-free.

[0030] In this embodiment, the annular curved crease (zigzag crease) origami configuration used in the internal light shield is fundamentally different from a straight crease. Geometrically, it achieves "multi-layered axial infinite nesting compression" and "rotational unfolding along a defined axis within fixed boundaries," endowing the structure with extremely high axial compression capacity (high fold-to-unfold ratio) and geometrically built-in deterministic motion constraints. From the folded state to the unfolded state, the structure moves along a uniquely determined geometric path, eliminating motion ambiguity and ensuring extremely high unfolding accuracy and repeatability. Strong geometric coupling gives the structure higher overall stiffness in the folded state, enabling it to more effectively resist and dissipate external impact or vibration energy. During folding, the structure not only stores "folding energy" at the crease but also stores additional "bending strain energy" due to its curved surface, providing a larger driving force reserve for self-unfolding and making the unfolding process more controllable. This is particularly suitable for light shields for spacecraft optical payloads.

[0031] In one embodiment, see Figures 4 to 8 The fixed sections at both ends of the shape memory L-shaped beam 13, which are connected to the frame, maintain their shape when retracted, while the middle section is deformable. Through heat softening, its two originally perpendicular plates can become parallel or nearly parallel to each other, and then the shape memory L-shaped beam 13 as a whole bends (see...). Figure 8 ), until its height dimensions meet the storage requirements of the light shield, and do not exceed the outer envelope of the light shield (see Figure 1 This allows for significant bending and folding of the beams, greatly reducing the frame's folding height and significantly improving the folding-out ratio of the external frame.

[0032] In one embodiment, the shape memory L-shaped beam 13 is made of shape memory polymer composite material (SMP), for example, a composite of a matrix material such as resin and a high-strength fiber material such as carbon fiber or glass fiber, and a flexible thin film heater (not shown in the figure) is attached to the outer wall using silicone rubber.

[0033] In one embodiment, see Figure 5 and Figure 7 At the inner corner connection of the two plates of the shape memory L-shaped beam 13, a clearance groove 131 is formed along the length direction. This clearance groove 131 makes the material in this local area easier to bend and deform after being heated, thus smoothly realizing the transformation of the two plates from perpendicular to parallel. The clearance groove guides the deformation position, reduces the torque required for folding, and makes the folding process more controllable and repeatable.

[0034] More preferably, the clearance groove 131 can be selected from cross-sectional shapes such as V-shaped, U-shaped, arc-shaped, or rectangular. A key parameter is its depth, which must ensure that the remaining material thickness at the bottom of the clearance groove 131 is less than the plate thickness of the main body of the shape memory L-shaped beam 13. For example, when the main body thickness is 2mm, the remaining thickness at the bottom of the clearance groove 131 can be 0.8-1.2mm. Different groove shapes can adapt to different bending radii and fatigue life requirements.

[0035] See Figures 1 to 3 In one embodiment, mounting grooves are provided at the corners of the top frame 11 and the bottom frame 12. The two ends of the shape memory L-shaped beam 13 are machined to match the shapes of the mounting grooves. After being embedded in the grooves, bolts are used to secure it through the through holes in the frame sidewalls and beam ends. This connection method is robust and reliable, and facilitates assembly and disassembly.

[0036] Based on the concept of this invention, the external frame structure can be in the shape of a triangular frustum, a square frustum, a pentagonal frustum, or a hexagonal frustum, with an internal light-shielding structure provided on each side. In this preferred embodiment, the external frame structure 1 is a square frustum, meaning the top frame 11 and bottom frame 12 are square, and four shape-memory L-shaped beams 13 connect to the four corners. Four internal light-shielding structures 2 correspond to the four sides. This shape is suitable for the general and symmetrical design of most rectangular optical payloads, resulting in uniform stress distribution during structural deployment and simple control, making it a preferred embodiment that is easy to implement and optimize in engineering.

[0037] In one embodiment, the shape memory skeleton 21 is made of shape memory polymer composite material (SMP), for example, a composite of a matrix material such as resin and a high-strength fiber material such as carbon fiber or glass fiber, with a thickness of approximately 1 mm. A flexible thin-film heater (not shown in the figure) is attached to its outer side (or integrated inside). The bottom center of the shape memory skeleton 21 is fixed to the bottom frame 12 by bolts. Preferably, the heater and the light-shielding cloth 22 are respectively disposed on both sides of the shape memory skeleton 21; for example, the light-shielding cloth 22 is disposed on the inner side of the shape memory skeleton 21, and the heater is disposed on the outer side of the shape memory skeleton 21. The light-shielding cloth 22 can be connected to the shape memory skeleton 21 by means of adhesion, riveting, bolting, etc.

[0038] To ensure that the internal light-shielding structure 2 can be fully deployed, in one embodiment, the deployable light-shielding structure is equipped with a locking device. Small magnets are pre-embedded at key positions on the outer edge of the shape memory skeleton 21 after it is fully deployed (such as the two ends of the outer arc of the fan ring and the midpoint of the two sides). Magnets or magnetic conductive sheets are also provided at corresponding positions on the inner surfaces of the top frame 11, the bottom frame 12, and the L-shaped beam 13. When fully deployed, magnetic attraction locks the skeleton 21 to the frame.

[0039] This embodiment also provides a shaping method for the above-mentioned deployable light-shielding structure, which includes two independent steps: Shape memory L-shaped beam shaping: Heat the shape memory L-shaped beam 13 as a whole or its deformed section to above Tg (e.g., 80°C), use a clamp to bend its two plates to parallel, then bend it into a predetermined folded shape, and cool (e.g., to 20°C) to set the shape.

[0040] Shape memory skeleton shaping: The fan-shaped shape memory skeleton 21 is heated to above Tg, and then alternately folded along the curve 211 to form a radially corrugated layered ring shell structure, which is then cooled and shaped. This method provides a repeatable and mass-producible shape setting process, ensuring the consistency of the product's folded state.

[0041] This embodiment also provides a method for controlling the deployment of the above-mentioned deployable light-shielding structure, including the following steps executed sequentially: S1: The heaters of the four shape memory L-shaped beams 13 are simultaneously energized and heated to above Tg. The shape memory L-shaped beams 13 restore their original L-shape, push the top frame 11 into place, and establish the boundary of the four-sided pyramidal frustum.

[0042] S2: The heaters of the four frames 21 are energized sequentially in a predetermined order (e.g., clockwise). After each frame is heated, under the geometric constraints of its curved lines, it smoothly unfolds from a corrugated shell into a planar fan ring, filling the corresponding side. After all frames are unfolded, they are magnetically locked. This method ensures low impact, high synchronization, and high precision of the final configuration during the unfolding process.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that not every embodiment contains only one independent technical solution, and in the absence of conflict between solutions, the various technical features mentioned in each embodiment can be combined in any way to form other implementation methods that can be understood by those skilled in the art.

[0044] Furthermore, without departing from the scope of the present invention, modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, shall not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A deployable light-shielding structure based on shape memory material, characterized in that, include: The external frame structure includes a top frame, a bottom frame, and multiple shape memory L-shaped beams connecting the top frame and the bottom frame. When fully unfolded, the external frame structure forms a truncated pyramidal spatial boundary. The internal light shield structure is multiple and corresponds to the side of the space boundary. Each internal light shield structure includes a fan-shaped shape memory skeleton and a light shielding cloth connected to the shape memory skeleton. The shape memory skeleton is provided with concentric ring-shaped curves. The skeleton can be folded and gathered along the curves into a radially corrugated stacked ring shell structure, and can be unfolded into a planar fan-shaped ring under thermal excitation to fill the spatial boundary. The creases are concentric annular grooves cut at fixed intervals on the fan-shaped annular plate of the shape memory skeleton, and the material thickness at the grooves is less than the thickness of the skeleton body.

2. The deployable light-shielding structure according to claim 1, characterized in that: When the shape memory L-shaped beam is in the folded state, the fixed sections at both ends that are connected to the top and bottom frames can maintain their shape, while the part between the fixed sections can deform, so that the two originally perpendicular plates can be changed to a state of being parallel or nearly parallel to each other.

3. The deployable light-shielding structure according to claim 2, characterized in that: The shape memory L-shaped beam has a clearance groove along its length at the inner corner connection of its two plates. The clearance groove makes the material at the connection easy to deform when the beam is bent, thereby realizing the transformation of the two plates from a perpendicular state to a parallel or nearly parallel state.

4. The deployable light-shielding structure according to claim 3, characterized in that: The clearance groove is a V-shaped groove, U-shaped groove, arc groove or rectangular groove, and its depth is such that the remaining material thickness at the connection is less than the thickness of the main plate of the L-shaped beam.

5. The deployable light-shielding structure according to claim 1, characterized in that: The top frame and bottom frame are provided with mounting grooves at their corners, and the two ends of the shape memory L-shaped beam are respectively embedded and fixed in the corresponding mounting grooves; The shape memory L-shaped beam is fixedly connected to the top frame and the bottom frame by bolts that pass through the side wall of the mounting groove and the end of the L-shaped beam.

6. The deployable light-shielding structure according to any one of claims 1 to 5, characterized in that: The external frame structure is a frustum-shaped four-sided pyramid frame, and there are four shape memory L-shaped beams, which are respectively connected to the four corners of the top frame and the bottom frame.

7. The deployable light-shielding structure according to claim 1, characterized in that: The shape memory skeleton is made of shape memory polymer composite material, with heaters attached to its surface, and the bottom center of the shape memory skeleton is fixed to the bottom frame by bolts; and / or The shape memory L-shaped beam is made of shape memory polymer composite material, and a heater is attached to its surface.

8. The deployable light-shielding structure according to claim 1, characterized in that: It also includes a locking device for locking the relative position of the inner light shield structure with the outer frame structure after the inner light shield structure is fully deployed; The locking device includes magnetic material disposed on the outer edge of the shape memory skeleton and at corresponding positions of the top frame and bottom frame.

9. A method for shaping a deployable light-shielding structure as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Shape memory L-shaped beam shaping: Heat it to above its glass transition temperature, apply external force to change the two plates from a vertical state to a parallel or nearly parallel state, and further bend the whole into a predetermined folded shape, and then cool it below the glass transition temperature to fix the shape; Shape memory skeleton shaping: It is heated to above its glass transition temperature, folded along its curves and gathered into a radially corrugated stacked ring shell structure, and then cooled to below its glass transition temperature for shaping.

10. A method for controlling the deployment of a deployable light-shielding structure as described in any one of claims 1 to 8, characterized in that, The following steps are executed sequentially: S1. Apply a first thermal excitation to the multiple shape memory L-shaped beams to drive them to recover from the folded state to the unfolded state, so that the top frame moves to the predetermined working position and establishes the pyramidal spatial boundary. S2. After step S1 is completed, a second thermal excitation is applied to the shape memory skeleton of each of the internal light shield structures in sequence, driving it to unfold from a corrugated shell-like state into a planar fan-shaped ring, filling the side of the spatial boundary.

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