A heat-driven liquid crystal solar sail deployment device
By using a liquid crystal elastomer skeleton to drive thermal deformation, the problems of complex deployment methods and excessive weight of solar sails have been solved, enabling the programmable deployment and folding of thin, large-area solar sails, which are suitable for aerospace deep space exploration.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FUDAN UNIVERSITY
- Filing Date
- 2024-01-22
- Publication Date
- 2026-05-29
AI Technical Summary
Existing solar sail deployment methods suffer from complex structures and excessive weight, making it difficult to achieve lightweight, large-area solar sail deployment in deep space exploration.
Using liquid crystal elastomer as a framework, the optical sail film is driven to unfold and fold under thermal stimulation. The double-layer film structure of the liquid crystal elastomer and the bending deformation of liquid crystal oligomer inks with different compositions under temperature changes are utilized to achieve programmable unfolding and folding.
It achieves self-deployment and folding of the light sail, with high storage ratio, fast response, low energy consumption, and controllable deployment degree and attitude adjustment, making it suitable for intelligent operation in the space environment.
Smart Images
Figure CN117742029B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solar sail technology, specifically relating to a thermally driven liquid crystal solar sail deployment device. Background Technology
[0002] Liquid crystal elastomers are smart materials that couple entropic elasticity and liquid crystal ordering, typically composed of cross-linked liquid crystals and polymers. Due to their high energy density, rapid stimulus response, and large-scale reversible deformation capabilities, they are an excellent choice for constructing flexible actuators. When a liquid crystal elastomer is heated to a specific transition temperature, the phase-arrayed liquid crystal polymers within it transform into an isotropic arrangement, macroscopically exhibiting significant recoverable deformation.
[0003] The idea of using solar sails for propulsion in deep space exploration has been around for a long time. Research shows that when photons strike a smooth surface, they generate a reaction force, thus creating light pressure when a beam of light hits a solar sail. Theoretically, if the spacecraft is light enough and the solar sail is large enough, and the shape and angle of the sail are suitable, high-speed space travel could be achieved for a certain period under the influence of solar light pressure. Because solar sails require a large and very thin membrane, a key issue is the deployment method in space. Current deployment methods mainly include mast-structure stretching and spin deployment; however, these methods suffer from structural complexity and excessive weight—precisely the most critical problem for solar sails. Summary of the Invention
[0004] The purpose of this invention is to provide a thermally driven liquid crystal solar sail deployment device that enables programmable unfolding and folding.
[0005] The thermally driven liquid crystal solar sail deployment device provided by this invention consists of a liquid crystal elastomer as a framework adhered to a solar sail film. The solar sail film folds and unfolds through the deformation of the liquid crystal elastomer under thermal stimulation, thus achieving programmable deployment and folding; wherein:
[0006] The specific shape of the light sail film includes a large equilateral triangle and three small squares. One vertex of each of the three small square films is located at the vertex of the equilateral triangle. Each square film is symmetrical to the triangular film (the axis of symmetry is the diagonal of each square film).
[0007] The liquid crystal elastomer is strip-shaped and has a double-layer film structure.
[0008] Liquid crystal elastomers are printed into strips using a direct-write 3D printer, such as... Figure 1As shown, the liquid crystal ink used for printing is prepared based on the classic Michael addition reaction method. The liquid crystal printing ink is placed in a sealed syringe, and the ink is uniformly extruded from the needle tip by controlling the pressure of an air pump. During LCE printing, the viscous ink composed of uncrosslinked liquid crystal oligomers is subjected to nozzle shear stress when ejected from the printhead, spontaneously aligning along the printing path. With the aid of ultraviolet crosslinking to fix the precursor, liquid crystal strips with good orientation properties are obtained. Under a thermal field, the liquid crystal elastomer contracts in the horizontal direction and expands in the vertical direction, reaching its maximum rate of contraction and expansion near 110°C (slightly above the nematic-isotropic transition temperature). The bottom layer is printed horizontally, and the top layer is printed vertically. This results in different coefficients of thermal expansion of the two layers when the temperature changes, causing overall bending deformation.
[0009] To ensure the orderly unfolding and folding of the light sail, by synthesizing liquid crystal oligomer inks with different compositions, their main chain flexibility and cross-linking chemical properties can be changed, thereby altering the critical temperature at which bending deformation occurs, thus achieving significant two-step or multi-step deformation.
[0010] The liquid crystal strips are attached and connected along the lines from the center of the central triangular film to its three corners. A strong connection between the film and the liquid crystal matrix can be ensured through methods such as thread sewing, adhesive bonding, or double-sided tape. The protruding portion of the liquid crystal strip is used to connect to the square films. Similarly, the liquid crystal strips are attached and connected along one diagonal of the square films, ensuring that the diagonals of the three square films are collinear with the lines from the center of the central triangle to its corners, and that one corner of each square coincides with a corner of the triangle. See also... Figure 3 .
[0011] The above describes the basic structure of a light sail.
[0012] In this invention, the dimensions of the double-layer rectangular strip are (4-6cm)*(0.8-1.2cm)*(0.6-1.0)cm. Preferably, it is 5cm*1cm*0.8cm.
[0013] In this invention, the side length of the equilateral triangular film is 8.5-9.2cm, preferably 8.7cm.
[0014] In this invention, the side length of the square film is 3-4 cm, preferably 3.5 cm.
[0015] The deployment and folding of the optical sail structure can then be controlled by adjusting the thermal radiation load. The entire optical sail and liquid crystal framework initially form a rolled-up folded structure, and its deployment process consists of two stages:
[0016] Phase 1: The triangular strips on the central triangular sail film are heated to the critical value of deformation by light or heating equipment and then unfold into a straight state. At the same time, the outer square sail film is gradually exposed to light and the temperature begins to rise.
[0017] Phase Two: The strips attached to the square sail on the outside reach the critical deformation value and unfold into a straight state, and the sail is fully unfolded.
[0018] Similarly, when it is necessary to fold and store the optical sail in certain situations, auxiliary equipment can be used to adjust the sail to a position where it is not exposed to radiation. The sail then begins to cool down. Because the critical deformation temperatures of the two liquid crystal strips are different, the outer square sail curls up and stores first, followed by the central triangular sail. The scale of the diagram below is irrelevant; the actual large scale of the optical sail does not affect the structural deformation process and mechanism.
[0019] The main technical features and performance advantages of this invention are as follows:
[0020] (1) The structure can spontaneously return from a bent state to a straight state after the temperature changes and reaches a critical value, which drives the film to unfold. This is a clever control method of non-contact thermal radiation.
[0021] (2) The degree of expansion can be controlled in stages by different temperatures to achieve different requirements.
[0022] (3) It has a high storage ratio while realizing intelligent storage and unfolding functions.
[0023] (4) Achieve ultra-low energy and fast response deployment and storage of light sails in space environment.
[0024] (5) The structure is flexible and controllable, and the unfolding and retraction of a certain sail surface can be controlled to adjust the overall attitude and forward direction. Attached Figure Description
[0025] Figure 1 This diagram illustrates the deformation principle of a liquid crystal elastomer double-layer film structure. (a) shows the initial configuration at temperature T0 with the upper and lower layers bonded together, with a length of l0. (b) shows the deformation when the temperature is increased to T; if the upper and lower layers are not bonded, they extend by different lengths. (c) shows the deformation when the temperature is increased to T; with the upper and lower layers bonded together, the overall structure undergoes bending deformation.
[0026] Figure 2 This is a schematic diagram illustrating the deployment and retraction of a liquid crystal strip driven by thermal radiation.
[0027] Figure 3 This is a schematic diagram of the fully deployed optical sail driven by a liquid crystal strip. The left view is a top view, and the right view is a bottom view.
[0028] Figure 4Schematic diagram of the structure of a liquid crystal strip-driven optical sail in half-deployment (stage one). The left side is a three-view drawing, and the right side is an isometric drawing.
[0029] Figure 5 This is a schematic diagram of the structure of the liquid crystal strip driving the optical sail to fully converge (stage two). The top left is a top view, the top right is a cross-sectional view, the bottom left is a front view, and the bottom right is an isometric view.
[0030] In the diagram, 1 represents a triangular thin film, 2, 3, and 4 represent three square thin films, 5, 6, and 7 represent three triangular thin film skeleton liquid crystal strips, and 8, 9, and 10 represent three square thin film skeleton liquid crystal strips. Detailed Implementation
[0031] Example 1:
[0032] A direct-write ink 3D printer was used, with the ink composed of liquid crystal oligomer precursors. Two types of inks used different components to synthesize the precursors. In the first internal stage of precursor synthesis, the following were added: liquid crystal monomer RM82 (2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate), alkaline catalyst TEA (triethylamine), free radical inhibitor BHT (butylated hydroxytoluene), photoinitiator I-369, and vinyl crosslinking agent TATATO. The proportions of these five raw materials are shown in Table 1. In the second external stage of precursor synthesis, the following were added: liquid crystal monomer RM82 (2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate), photoinitiator I-369 (2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone), and chain extender n-butylamine. The proportions of these three raw materials are shown in Table 2.
[0033] Table 1. Mass ratio of raw materials used in the first-stage LCE synthesis process
[0034]
[0035] Table 2. Mass ratio of raw materials used in the second-order LCE synthesis process
[0036]
[0037] The precursor phase transition temperature in the first stage after synthesis is 24℃, and the precursor phase transition temperature in the second stage is 80℃. The oligomers are treated with heating and light-protected settling to form precursor ink, which is then transferred to a syringe for 3D ink direct writing printing. A gcode program is written to print a double-layered rectangular strip with dimensions of 5cm*1cm*0.8cm. The bottom layer has a horizontal direction arrow, and the top layer has a vertical direction arrow, exhibiting pure bending deformation. Six identical strips are printed repeatedly (e.g.,...). Figure 3(5-7 and 8-10) Installation Figure 3 The method shown is similar to a square PDMS film with dimensions of 3.5cm x 3.5cm (e.g., ...). Figure 3 (2, 3, 4) An equilateral triangular PDMS film with a side length of 8.7cm is pasted on (e.g.) Figure 3 (The dimensions shown in section 1) are for demonstration purposes; the actual size of the solar sail does not affect the structural deformation process and mechanism. The three central strips connect the center and vertices of the triangle, and the three outer strips are attached to the diagonals of the square. After attachment, it looks like... Figure 3 As shown. The light sail structure is then rolled up from the outside to the center along the three liquid crystal supports and left to stand; this is the retracted state. The configuration in the retracted state is as follows: Figure 5 As shown, the inks from the two stages print strips with two different deformation temperatures.
[0038] When the optical sail needs to be deployed, it is suspended in the air by a thin thread and irradiated with a heat radiator. The liquid crystal strips on the central triangular sail, directly exposed to the radiation, reach their critical deformation temperature first and begin to deploy. The surrounding square sails then gradually heat up and deploy as well. Afterward, the heat radiator is turned off, and the optical sail structure begins to cool. The outer square sails reach their critical temperature and curl up, followed by the central triangular sail, until the entire structure is fully retracted. Figure 2 As shown.
Claims
1. A thermally driven liquid crystal solar sail deployment device, characterized in that, It consists of a liquid crystal elastomer as a framework adhered to a light sail film. The light sail film folds and unfolds through the deformation of the liquid crystal elastomer under thermal stimulation, achieving programmable unfolding and folding; wherein: The specific shape of the light sail film includes a large equilateral triangle and three smaller squares outside the equilateral triangle. One vertex of each of the three square films is located at the vertex of the equilateral triangle, and each square film is symmetrically arranged with the triangular film. The liquid crystal elastomer is strip-shaped and has a double-layer film structure; Liquid crystal elastomers are printed into strips using a direct-write 3D printer. Under a thermal field, the liquid crystal elastomers contract along the parallel direction and expand in the perpendicular direction. The bottom layer is printed horizontally, and the top layer is printed vertically. Thus, when the temperature changes, the thermal expansion coefficients of the two layers are different, causing the whole to bend and deform. The liquid crystal strips are attached and connected according to the lines from the center of the central triangle film to the three corners; the protruding part of the liquid crystal strips is attached and connected to one diagonal of the square film, ensuring that the diagonals of the three square films are collinear with the straight lines from the center of the central triangle to the corners, and that one corner of the square coincides with the triangle.
2. The thermally driven liquid crystal solar sail deployment device according to claim 1, characterized in that, To ensure the orderly unfolding and folding of the light sail, by synthesizing liquid crystal oligomer inks with different compositions, their main chain flexibility and cross-linking chemical properties can be changed, thereby altering the critical temperature at which bending deformation occurs, thus achieving two-step or multi-step deformation.
3. The thermally driven liquid crystal solar sail deployment device according to claim 1, characterized in that: The dimensions of the double-layered rectangular strip are (4-6cm) * (0.8-1.2cm) * (0.6-1.0)cm; The side length of the equilateral triangular membrane is 8.5-9.2 cm; The side length of the square film is 3-4 cm.
4. The thermally driven liquid crystal solar sail deployment device according to claim 1, characterized in that, The unfolding and folding of the optical sail structure are controlled by adjusting the thermal radiation load; the entire optical sail and liquid crystal skeleton are initially a rolled-up folded structure, and its unfolding process is divided into two stages: Phase 1: The triangular strips on the central triangular sail film are heated to the critical value of deformation by light or heating equipment and then unfold into a straight state. At the same time, the outer square sail film is gradually exposed to light and the temperature begins to rise. Phase Two: The strips attached to the square sail on the outside reach the critical deformation value and unfold into a straight state, and the sail is fully unfolded.