Space large-aperture reflector flexible support design method and support structure

Abstract

The invention discloses a flexible support design method for a spatial large-aperture reflector and a support structure, and relates to the field of quasi-kinematics support design of large-aperture spatial reflectors. According to the method, a titanium alloy material is selected, parameters such as the size of a connecting frame and the total height of a Bipod support are determined according to the quality of a reflector, the size of a glue spot and an installation space, a cross-shaped blade flexible element is designed to serve as a flexible knot, a three-dimensional parameterized model is established and imported into finite element analysis software, and the three-dimensional parameterized model is obtained. And optimizing structural parameters by taking the RMS value of the optical surface deformation of the reflector as a judgment standard, and finally carrying out dynamic verification such as modal analysis and random vibration analysis. According to the supporting structure, rigidity and flexibility are balanced through a flexible joint, thermal stress can be released, rigidity in the optical axis direction is guaranteed, the bending moment and the influence of machining and assembling errors are reduced, the supporting structure is suitable for reliable supporting of the spatial large-aperture silicon carbide reflector, and the positioning precision and the surface shape precision of the reflector during on-orbit work are effectively guaranteed.

Description

Technical Field

[0001] The present application belongs to the technical field of support for large-aperture space mirrors, and in particular relates to a flexible support design method and support structure for large-aperture space mirrors. Background Art

[0002] In the field of space optics, large-aperture mirrors serve as core optical components, and the design of their support structures is directly related to the performance of the optical system. The optical component's support structure must connect it to the main structure of the space telescope. This requires not only ensuring the spatial position of the optical component during on-orbit operation, as well as the relative positional relationships of the components, such as optical spacing and positional attitude, but also ensuring the surface accuracy of the optical component to safeguard the light deflection effect and wavefront quality in the optical path. This requires, during design, treating the optical component as a rigid body, applying the principles of kinematics to constrain its six degrees of freedom in space to ensure a fixed spatial position; and, secondly, treating it as an elastic body, applying the principles of elastic mechanics to establish the elastic deformation relationship between the support and the optical surface, minimizing deformation of the mirror surface under the support structure. The goal of mirror support design is to simultaneously ensure both the positioning accuracy of the optical component and the surface accuracy of the optical surface to meet on-orbit operation requirements, while also taking into account the differences between various ground-based development links and the varying on-orbit environments.

[0003] Kinematic support design is essential for precision optical components to ensure precise positioning and prevent deformation of the optical surface caused by the support structure. Kinematic supports independently constrain the six degrees of freedom of the optical component in space without redundancy, achieving statically determinate support. This is an ideal support method, allowing the optical component to move horizontally or rotationally along or around the support contact point or line, while maintaining rigid body motion without deformation.

[0004] However, fully kinematic supports have drawbacks. They rely on point and line contact, which are high-pair contacts and generate high stresses under load. Furthermore, each individual support can rotate, and friction and adhesion between rotating contacts can overconstrain the optical element. The frictional influence mechanism is complex. Minor differences in contact surface polish, coating properties, temperature, contamination, and stress conditions can cause drastic fluctuations in friction. These factors are difficult to effectively control, making it difficult to accurately measure and describe friction, which in turn affects the performance budget prediction of optomechanical structures.

[0005] In order to avoid the friction caused by the use of hinges in the support structure due to the decoupling of degrees of freedom, a compliant structure can be used to release the excess degrees of freedom to form a quasi-kinematic support. Compliant support is generally achieved through flexible design. A flexible link is set in the support structure, and the bending deformation of the metal is used to release stress, so that the deformation is controlled in the supporting flexible link instead of being transmitted to the mirror surface. The flexible structure is not completely unconstrained in the direction where the degrees of freedom do not need to be restricted, but it exhibits high compliance, so it is called a quasi-kinematic support. Its compliance is based on the bending deformation of the metal sheet and has good predictability. Bipod support is a commonly used flexible support form in large-aperture mirrors. It is a key structure to ensure that the shape accuracy of the mirror meets the requirements under various working conditions. Summary of the Invention

[0006] The purpose of the embodiments of this application is to provide a flexible support design method and support structure for a large-aperture space mirror. This is to address the issues raised in the background art above, such as the high stress, overconstraint, and friction of fully kinematic supports that affect performance prediction, as well as the difficulty of the support structure in simultaneously ensuring both positioning accuracy and surface accuracy, and its inability to adapt to differences between ground and on-orbit environments.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, a method for designing a flexible support for a large-aperture space mirror is provided, comprising the following steps:

[0009] Titanium alloy was chosen as the support material for the Bipod;

[0010] Determine the size of the connection frame between the Bipod and the SiC reflector support boss based on the reflector's mass and adhesive spot size;

[0011] Determine the total height of the Bipod based on the installation space;

[0012] Determine the Bipod knot distribution pattern;

[0013] Determine the Bipod support rod dimensions, the size of the flexible knot, and the angle between the two Bipod support rods;

[0014] Create parametric models of the reflector and bipod in 3D modeling software, and mark the bipod's flexible knot size and the angle between the two support rods as important dimensions;

[0015] The parametric model was transferred to the finite element analysis software to calculate the RMS value of the optical surface deformation of the reflector under different loads. The RMS value of the optical surface was used as the evaluation criterion to optimize the structural parameters of the Bipod.

[0016] Dynamic simulation verification of the reflector and flexible junction components.

[0017] In one possible implementation, the step of determining the size of the connection frame between the Bipod and the silicon carbide reflector support boss is performed by calculating the size of the adhesive spot and the minimum bonding area according to the overload during launch. The minimum bonding area calculation formula is:

[0018]

[0019] Among them, Q min is the minimum bonding area, W is the weight of the reflector, g is the acceleration of gravity, a G The maximum acceleration that the reflector can withstand is 30 g, f s is the safety factor, and J is the shear strength of the glue.

[0020] In a possible implementation, the dynamic simulation verification includes modal analysis and random vibration analysis;

[0021] During modal analysis, fixed constraints were set on the bolt holes at the bottom of the three Bipods to calculate the natural frequency of the components, which was required to be greater than 150 Hz.

[0022] During random vibration analysis, the impact curve is loaded along the optical axis to examine the stress value at the thinnest part of the Bipod junction, requiring the stress value to be less than the yield strength of the material.

[0023] In a possible implementation, the flexible knot distribution is in the form of using a group of cross-blade flexible elements at the end of each support rod, so that the three Bipods have equal stiffness along the optical axis.

[0024] In a possible implementation, when optimizing the structural parameters of the Bipod, both gravity load and forced displacement along the axial direction are applied, and the RMS value of the optical surface deformation is required to be less than 7 nm.

[0025] In a second aspect, a flexible support structure for a large-aperture space mirror is provided, which adopts the design method of the first aspect and includes a Bipod support member;

[0026] The Bipod support is made of titanium alloy and includes a connection frame connected to the reflector support boss and two support rods;

[0027] One end of the two support rods is connected to the connection frame, and the other end is connected to the Bipod connection base. A flexible knot is provided on the support rod, and the flexible knot is a cross-blade flexible element. A certain angle is formed between the two support rods, and the initial value of the angle is 35°.

[0028] In a possible implementation, the width of the connection frame is not less than 8 mm, specifically 18 mm.

[0029] In one possible implementation, the Bipod support has a total height of 73.2 mm and a total length of 156.5 mm.

[0030] In a possible implementation, the thickness of the flexible knot is 2 mm, the width is 9 mm, and the heights of the first to fourth sections of flexible knots are 5.6 mm, 6.4 mm, 4.8 mm, and 11 mm, respectively.

[0031] In a possible implementation, the Bipod support is connected to the reflector support boss via adhesive spots, the adhesive spots have a diameter of 8 mm, there are 8 adhesive spots on each Bipod support, and there are 24 adhesive spots in total for three Bipod support members.

[0032] Compared with the prior art, this application has the following beneficial effects:

[0033] This application provides a design method for flexible supports for large-aperture space mirrors. By selecting suitable titanium alloy materials, determining the key parameters of the Bipod in combination with the characteristics of the mirror and the installation space, and adopting parametric modeling and finite element optimization, and through dynamic verification, a precise balance between the stiffness and flexibility of the Bipod support is achieved. The method can effectively release thermal stress and reduce processing and assembly errors and the influence of dynamic loads through flexible joints, while ensuring the positioning accuracy in the direction of the optical axis, ensuring that the mirror has stable surface accuracy and spatial position accuracy in different environments both on the ground and in orbit, and fully meeting the support requirements of large-aperture space mirrors.

[0034] In one possible implementation, the minimum bonding area is accurately calculated using a formula to determine the glue spot size and the connection frame size based on the reflector weight, launch overload, safety factor, and shear strength of the glue. This ensures that the bonding strength between the Bipod and the reflector support boss is sufficient to withstand the dynamic load during launch, avoiding reflector position displacement or surface deformation due to connection failure. This provides a scientific and quantitative design basis for the reliable connection between the support structure and the reflector, and ensures the stability and safety of the support system.

[0035] In one possible implementation, dynamic simulation verification ensures that the support structure can withstand dynamic loads during launch, modal analysis avoids the risk of resonance, and random vibration analysis ensures the strength of the flexible joint, significantly improving the reliability of the structure's on-orbit operation.

[0036] In one possible implementation, the cross-blade flexible knot achieves equal stiffness characteristics at three positions along the optical axis, ensuring uniform force on the reflector and reducing mirror deformation caused by stiffness imbalance. At the same time, it releases redundant degrees of freedom through directional flexibility and avoids additional stress caused by over-constraint.

[0037] A flexible support structure for a large-aperture space mirror. The combination of titanium alloy material and cross-blade flexible joints ensures the lightweight and high-strength support structure, while releasing thermal stress and assembly errors through flexible links. At the same time, the virtual intersection position of the two support rods can be optimized by adjusting the support rod angle, reducing the bending moment of the mirror surface, making it suitable for the long-term stable operation of large-aperture space mirrors.

[0038] In one possible implementation, sufficient connection frame width provides sufficient redundancy for gluing, avoiding insufficient connection strength due to irregular glue spot shape or glue injection hole influence, while facilitating position adjustment during assembly and improving the fault tolerance of the structure.

[0039] In one possible implementation, the optimized flexible knot size takes into account both flexibility and rigidity, which can not only release thermal stress and assembly errors through bending deformation, but also provide sufficient support force in the optical axis direction, effectively controlling mirror deformation and ensuring optical performance.

[0040] In one possible implementation, the multi-glue spot distribution design disperses the weight and dynamic load of the reflector, improving the shear resistance of the connection structure. The 8mm diameter glue spot not only ensures strength but also adapts to the requirements of the glue injection process to ensure that the bonding layer is uniform and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the overall structure of a flexible support structure for a large-aperture space reflector provided in this application;

[0042] Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle;

[0043] Figure 3 A schematic diagram of the overall structure of a Bipod support provided in this application;

[0044] Figure 4 A front view of a Bipod support provided in this application;

[0045] Figure 5 for Figure 4 Cross-sectional view of the middle BB surface;

[0046] Figure 6 Schematic diagram of the RMS value of the optical surface deformation of the mirror body and Bipod support under 1G gravity of this application;

[0047] Figure 7 This is a schematic diagram of the RMS value of optical surface deformation when there is a 0.003mm installation error between the three Bipod supports and the mounting surface in this application;

[0048] Figure 8This is a schematic diagram of the RMS value of the optical surface deformation of the Bipod support and mirror body under a 1°C temperature change in this application;

[0049] Figure 9 Schematic diagram of the power density spectrum curve of random vibration in this application;

[0050] Figure 10 This is the stress distribution cloud diagram of the random vibration analysis results of the Bipod and reflector.

[0051] Reference numerals in the figure: 1. Bipod support; 2. Reflector; 3. Support boss; 4. Connecting frame; 5. Support rod; 6. Soft knot; 7. Glue spot; 8. Glue injection hole. DETAILED DESCRIPTION

[0052] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0053] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0055] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0056] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0057] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0058] like Figure 1 、 Figure 2 and Figure 3 As shown, the present application provides a flexible support structure for a large-aperture space reflector 2. The flexible support design method for the large-aperture space reflector 2 may include the following steps:

[0059] Titanium alloy was chosen as the support material for the Bipod.

[0060] Specifically, TC4 titanium alloy can be selected as the Bipod support material, which has a density of 4.43g / cm3, a tensile strength of 1000MPa, a yield strength of 800MPa, an elastic modulus of 110GPa, and a linear expansion coefficient of 9×10-6 / °C.

[0061] The size of the connection frame 4 between the Bipod and the supporting boss 3 of the silicon carbide reflector 2 is determined according to the quality of the reflector 2 and the size of the adhesive spot 7 .

[0062] Optionally, based on the mass of the reflector 2 of 12 kg, the maximum acceleration of the emission of 30 g, the safety factor of 4, and the shear strength of the 2216 adhesive of 22.08 MPa, the minimum diameter of each adhesive spot 7 can be calculated to be 8 mm, and the width of the connection frame 4 can be determined to be 18 mm.

[0063] Determine the total height of the Bipod based on the installation space.

[0064] like Figure 4 As shown, optionally, due to installation space limitations, the Bipod has a total height of 73.2 mm and a total length of 156.5 mm. A cross-blade flexible element can be used as the flexible knot 6, and the initial value of the bottom angle can be 35°.

[0065] Determine the distribution of Bipod 6.

[0066] Optionally, the size of the Bipod support rod 5 , the size of the flexible knot 6 , and the angle between the two Bipod support rods 5 may be determined.

[0067] A parametric model was established in the 3D modeling software, and important parameters such as the thickness t, width w, height h1-h4 and bottom angle α of the flexible knot 6 were marked.

[0068] A parametric model of the reflector 2 and the Bipod is created in a three-dimensional modeling software, and the size of the Bipod's flexible knot 6 and the angle between the two support rods 5 are marked as important dimensions.

[0069] Specifically, the model was imported into the finite element analysis software, and gravity, axial forced displacement and temperature loads were applied. The optimization results were t = 2mm, w = 9mm, h1 = 5.6mm, h2 = 6.4mm, h3 = 4.8mm, and h4 = 11mm. At this time, the RMS value of the mirror deformation was 4.83nm under 1G gravity, 1.15nm under 0.003mm installation error, and 1.51nm under 1°C temperature difference.

[0070] The parameterized model was transferred to the finite element analysis software to calculate the RMS value of the optical surface deformation of the reflector 2 under different loads, and the structural parameters of the Bipod were optimized based on the optical surface RMS value.

[0071] Dynamic simulation verification of the reflector 2 and flexible junction 6 components is performed.

[0072] Specifically, dynamic verification shows that the first-order natural frequency is 456.1 Hz and the maximum random vibration stress is 205.5 MPa.

[0073] In the embodiment of the present application, by selecting suitable titanium alloy materials, combining the characteristics of the reflector and the installation space to determine the key parameters of the Bipod, using parametric modeling and finite element optimization, and through dynamic verification, a precise balance between the stiffness and flexibility of the Bipod support is achieved. It can not only effectively release thermal stress through the flexible knot 6, reduce processing and assembly errors and the influence of dynamic loads, but also ensure the positioning accuracy in the direction of the optical axis, ensuring that the reflector 2 has stable surface accuracy and spatial position accuracy in different environments both on the ground and in orbit, and fully meet the support requirements of the large-aperture reflector 2 in space.

[0074] In one possible embodiment, Figure 5 As shown, in the step of determining the size of the connection frame 4 between the Bipod and the support boss 3 of the silicon carbide reflector 2, the size of the connection frame 4 is determined by calculating the size of the adhesive spot 7 and the minimum adhesive area according to the overload during launch. The minimum adhesive area calculation formula is:

[0075]

[0076] Among them, Q min is the minimum bonding area, W is the weight of the reflector 2, g is the acceleration of gravity, a G The maximum acceleration that the reflector 2 can withstand is 30 g, f s is the safety factor, and J is the shear strength of the glue.

[0077] For the 12KG reflector 2, the minimum bonding area is calculated according to the formula, where the maximum acceleration is 30g, the safety factor is 4, the shear strength of the 2216 glue is 22.08MPa, and there are 24 glue spots 7 in three Bipods. The minimum area of ​​each glue spot 7 is 26.64mm2 and the diameter is 6mm. After considering the influence of the glue injection hole 8, the diameter is 8mm, corresponding to the width of the connecting frame 4 is 18mm.

[0078] In the embodiment of the present application, the minimum bonding area is accurately calculated using a formula based on the weight of the reflector 2, the launch overload, the safety factor and the shear strength of the glue to determine the size of the glue spot 7 and the size of the connecting frame 4, thereby ensuring that the bonding strength between the Bipod and the support boss 3 of the reflector 2 is sufficient to withstand the dynamic load during the launch process, avoiding position displacement or surface deformation of the reflector 2 due to connection failure, providing a scientific and quantitative design basis for the reliable connection between the support structure and the reflector 2, and ensuring the stability and safety of the support system.

[0079] In a possible embodiment, the dynamic simulation verification includes modal analysis and random vibration analysis.

[0080] During the modal analysis, fixed constraints are set on the bolt holes at the bottom of the three Bipods to calculate the natural frequency of the components, which is required to be greater than 150 Hz.

[0081] During the modal analysis, the 24 bolt holes on the bottom of the Bipod were fixed, and the first-order natural frequency of the component was measured to be 456.1 Hz (>150 Hz).

[0082] During random vibration analysis, the impact curve is loaded along the optical axis to examine the stress value at the thinnest part of the Bipod flexible junction 6, which is required to be less than the yield strength of the material.

[0083] Random vibration analysis shows that the stress at the thinnest point of Bipod flexible knot 6 is 205.5MPa (less than TC4 yield strength 800MPa).

[0084] In the embodiment of the present application, dynamic simulation verification ensures that the support structure can withstand dynamic loads during launch, modal analysis avoids the risk of resonance, and random vibration analysis ensures the strength of the flexible junction 6, significantly improving the reliability of the structure's on-orbit operation.

[0085] In a possible embodiment, the flexible knot 6 is distributed in the form of a group of cross-blade flexible elements at the end of each support rod 5, so that the Bipod has equal stiffness at three positions along the optical axis.

[0086] A cross-blade flexible element is set at the end of each support rod 5 of the Bipod. A single blade is flexible in a specific direction and rigid in other directions. The initial value of the base angle is 35°.

[0087] In the embodiment of the present application, the cross-blade flexible knot 6 realizes equal stiffness characteristics at three positions along the optical axis, ensuring that the reflector 2 is subjected to uniform force, reducing the deformation of the mirror surface caused by stiffness imbalance, and at the same time releasing redundant degrees of freedom through directional flexibility to avoid additional stress caused by over-constraint.

[0088] In a possible embodiment, when optimizing the structural parameters of the Bipod, both gravity load and forced displacement along the axial direction are applied, and the RMS value of the optical surface deformation is required to be less than 7 nm.

[0089] Optionally, a 1G gravity load is applied during the optimization process to simulate the gravity difference between the ground and on-orbit and a 0.003mm axial forced displacement to simulate the assembly error. The parameters of the flexible knot 6 are adjusted so that the RMS value of the mirror deformation is less than 7nm under both working conditions. The final optimized values ​​are 4.83nm and 1.15nm, respectively.

[0090] Alternatively, you can fix the three bipod bottoms, apply a 1G gravity field to the entire model, and calculate the RMS value of the optical surface deformation. If the RMS value is less than 7nm, the bipod has good static stiffness.

[0091] like Figure 6As shown in Figure 3, under the condition of 1G gravity field, the RMS value of the optical surface deformation is 4.83nm.

[0092] Optionally, constrain the displacement of the two bipods along the optical axis by applying a forced displacement of 0.003mm to the bottom surface of the other bipod. This simulates optical surface deformation caused by machining and assembly errors between the bipod bottom and the mounting surface. The resulting optical surface deformation should be within 5nm.

[0093] like Figure 7 As shown in the figure, when there is a 0.003mm unevenness error in the optical axis direction, the RMS value of the optical surface deformation is 1.15nm.

[0094] In the embodiment of the present application, the indicator constraints for key working conditions ensure that the reflector 2 can still maintain a high-precision surface shape under the influence of gravity changes and assembly errors, avoid optical path deviation or wavefront distortion, and ensure the imaging quality of the optical system.

[0095] In a possible embodiment, a flexible support structure for a spatial large-aperture reflector 2 is provided, which adopts the design method of the first aspect and includes a Bipod support member 1.

[0096] The Bipod support 1 is made of titanium alloy and includes a connection frame 4 connected to a support boss 3 of a reflector 2 and two support rods 5 .

[0097] One end of the two support rods 5 is connected to the connecting frame 4, and the other end is connected to the Bipod connecting base. A flexible knot 6 is provided on the support rod 5, and the flexible knot 6 is a cross-blade flexible element. A certain angle is formed between the two support rods 5, and the initial value of the angle is 35°.

[0098] The structure is made of TC4 titanium alloy and includes a connecting frame 4 with a width of 18 mm, two support rods 5 with an angle of 35°, and a cross-blade flexible knot 6 at the end of the rod. It has a thickness of 2 mm, a width of 9 mm, and heights h1-h4 of 5.6 mm, 6.4 mm, 4.8 mm, and 11 mm respectively. It is connected to the reflector 2 through 24 adhesive spots 7 with a diameter of 8 mm. The total height is 73.2 mm and the total length is 156.5 mm.

[0099] In the embodiment of the present application, the combination of titanium alloy material and the cross-blade flexible knot 6 not only ensures the lightweight and high strength of the supporting structure, but also releases thermal stress and assembly errors through the flexible link. At the same time, the virtual intersection position can be optimized by adjusting the angle of the support rod 5 to reduce the bending moment of the mirror, which is suitable for the long-term stable operation of the large-aperture space reflector 2.

[0100] In a possible embodiment, the width of the connecting frame 4 is not less than 8 mm.

[0101] Optionally, the width of the connecting frame 4 can be designed to be 18 mm, which is 8 mm larger than the diameter of the glue spot 7 , with a 5 mm margin reserved on each side to adapt to the shape of the irregular glue spot 7 and the space occupied by the glue injection hole 8 .

[0102] In the embodiment of the present application, sufficient width of the connecting frame 4 provides sufficient redundancy for gluing, avoiding insufficient connection strength caused by irregular shape of glue spot 7 or influence of glue injection hole 8, and at the same time facilitates position adjustment during assembly, thereby improving the fault tolerance of the structure.

[0103] In a possible embodiment, the Bipod support 1 has a total height of 73.2 mm and a total length of 156.5 mm.

[0104] The Bipod has a total height of 73.2 mm and a total length of 156.5 mm, which fully fits the installation space limited by the optical system and has no interference with the reflector 2 support boss 3 and the main structure of the telescope.

[0105] In the embodiment of the present application, the dimensions customized according to the installation space ensure the compatibility of the support structure and the optical system, avoiding mechanical interference with other components. At the same time, the compact layout helps to reduce the overall volume and weight of the telescope.

[0106] In a possible embodiment, the thickness of the flexible knot 6 is 2 mm, the width is 9 mm, and the heights of the first to fourth sections of the flexible knot 6 are 5.6 mm, 6.4 mm, 4.8 mm, and 11 mm, respectively.

[0107] Optionally, the flexible knot 6 has a thickness of 2 mm, a width of 9 mm, and four height sections of 5.6 mm, 6.4 mm, 4.8 mm, and 11 mm, respectively. Finite element analysis has shown that this size can make the RMS value of the mirror deformation less than 5 nm under all loads.

[0108] Optionally, constrain the bottom surfaces of the three bipods and apply a 1°C temperature change to the entire assembly. Since the bipods are made of TC4 with a linear expansion coefficient of 9 × 10⁻⁶ / °C, and the reflector is made of SiC with a linear expansion coefficient of 2.4 × 10⁻⁶ / °C, there's a significant difference between the two. Thermal stress can cause deformation of the mirror surface during temperature changes. The flexible junctions can release thermal stress through deformation, preventing this from causing deformation. Under these conditions, the mirror surface deformation should be no greater than 5nm.

[0109] like Figure 7 As shown in Figure 1, when a 1°C temperature rise is applied to the support and reflector assembly, the RMS value of the optical surface deformation is 1.51 nm.

[0110] In the embodiment of the present application, the optimized size of the flexible knot 6 takes into account both flexibility and rigidity. It can not only release thermal stress and assembly errors through bending deformation, but also provide sufficient supporting force in the optical axis direction, effectively controlling the deformation of the mirror and ensuring optical performance.

[0111] In a possible embodiment, the Bipod support 1 is connected to the support boss 3 of the reflector 2 via adhesive spots 7 . The diameter of the adhesive spots 7 is 8 mm. There are 8 adhesive spots 7 on each Bipod support 1 , and there are a total of 24 adhesive spots 7 on three Bipod support members 1 .

[0112] Optionally, each Bipod is provided with 8 adhesive spots 7, and three Bipods have a total of 24 adhesive spots. The adhesive spots 7 have a diameter of 8 mm and are connected to the bosses of the reflector 2 using 2216 adhesive. The bearing capacity of a single adhesive spot 7 meets the 30g overload requirement.

[0113] In this embodiment, the distribution design of multiple adhesive spots 7 disperses the weight and dynamic load of the reflector 2, and improves the shear resistance of the connection structure. The 8mm diameter adhesive spots 7 not only ensure strength, but also adapt to the requirements of the adhesive injection process to ensure that the adhesive layer is uniform and reliable.

[0114] Optionally, a dynamic analysis is performed on the reflector 2 and the Bipod support 1, including modal analysis and random vibration analysis.

[0115] A modal analysis was performed on reflector 2 to calculate its natural frequency, ensuring that the component could withstand the mechanical loads during launch and minimizing the dynamic coupling effects of the optical components. The component structure's natural frequency should be greater than 150Hz. In the modal analysis module of the finite element software, fixed constraints were set for the 24 bolt holes on the bottom of the three bipods. A modal analysis was run, and the component's first-order natural frequency was found to be 456.1Hz, meeting the design requirements.

[0116] Random vibration analysis is performed on the reflector 2 to examine whether the thinnest part of the Bipod flexible junction 6 can withstand the mechanical load during launch. The random vibration analysis module in the finite element software loads the component along the optical axis as follows: Figure 9 The shock curve shown, Figure 10 The stress value at the thinnest point of the Bipod shown is 205.5 MPa, which is less than the yield strength of TC4 material of 800 MPa, and therefore meets the design requirements.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that modifications to the technical solutions described in the aforementioned embodiments, or equivalent replacement of some or all of the technical features therein, do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for designing flexible supports for large-aperture space mirrors, characterized in that: The following steps are involved: Titanium alloy was chosen as the support material for the Bipod; The size of the connection frame (4) between the Bipod and the support boss (3) of the reflector (2) is determined according to the mass of the reflector (2) and the size of the adhesive spot (7); Determine the total height of the Bipod based on the installation space; Determine the distribution pattern of Bipod soft knots (6); Determine the size of the Bipod support rod (5), the size of the flexible knot (6), and the angle between the two Bipod support rods (5); A parametric model of the reflector (2) and the Bipod is established in a three-dimensional modeling software, and the size of the Bipod's flexible knot (6) and the angle between the two support rods (5) are marked as important dimensions; The parameterized model is transferred to the finite element analysis software to calculate the RMS value of the optical surface deformation of the reflector (2) under different loads, and the structural parameters of the Bipod are optimized based on the optical surface RMS value as the evaluation standard; Dynamic simulation verification is performed on the reflector (2) and the flexible junction (6) components.

2. The flexible support design method for a large-aperture space mirror according to claim 1 is characterized in that: In the step of determining the size of the connection frame (4) between the Bipod and the supporting boss (3) of the silicon carbide reflector (2), the size of the connection frame (4) is determined by calculating the size of the adhesive spot (7) and the minimum adhesive area according to the overload during emission, wherein the minimum adhesive area calculation formula is: Among them, Q min is the minimum bonding area, W is the weight of the reflector (2), g is the acceleration of gravity, a G The maximum acceleration that the reflector (2) bears is 30 acceleration g, f s is the safety factor, and J is the shear strength of the glue.

3. The flexible support design method for a large-aperture space mirror according to claim 1 is characterized in that: The dynamic simulation verification includes modal analysis and random vibration analysis; During modal analysis, fixed constraints were set on the bolt holes at the bottom of the three Bipods to calculate the natural frequency of the components, which was required to be greater than 150 Hz. During random vibration analysis, the impact curve is loaded along the optical axis and the stress value at the thinnest part of the Bipod flexible junction (6) is examined. The stress value is required to be less than the yield strength of the material.

4. The flexible support design method for a large-aperture space mirror according to claim 1 is characterized in that: The distribution form of the flexible knot (6) is to use a group of cross-blade flexible elements at the end of each support rod (5), so that the Bipod has equal stiffness in three vertical directions.

5. The flexible support design method for a large-aperture space mirror according to claim 1 is characterized in that: When optimizing the structural parameters of the Bipod, both gravity load and forced displacement along the axial direction are applied, and the RMS value of the optical surface deformation is required to be less than 7 nm.

6. A flexible support structure for a large-aperture space reflector designed using the design method according to any one of claims 1 to 5, characterized in that: comprising a Bipod support (1); The Bipod support (1) is made of titanium alloy and comprises a connection frame (4) connected to the support boss (3) of the reflector (2) and two support rods (5); One end of the two support rods (5) is connected to the connection frame (4), and the other end is fixed to the connection base plate of the Bipod support (1). A flexible knot (6) is provided on the support rod (5), and the flexible knot (6) is a cross-blade flexible element. A certain angle is formed between the two support rods (5), and the initial value of the angle is 35°.

7. The flexible support structure for a large-aperture space mirror according to claim 6, characterized in that: The width of the connecting frame (4) is not less than 8 mm, specifically 18 mm.

8. The flexible support structure for a large-aperture space mirror according to claim 6, characterized in that: The total height of the Bipod support (1) is 73.2 mm and the total length is 156.5 mm.

9. The flexible support structure for a large-aperture space mirror according to claim 6, characterized in that: The thickness of the flexible knot (6) is 2 mm, the width is 9 mm, and the heights of the first to fourth sections of the flexible knot (6) are 5.6 mm, 6.4 mm, 4.8 mm, and 11 mm, respectively.

10. The flexible support structure for a large-aperture space mirror according to claim 6, characterized in that: The Bipod support (1) is connected to the support boss (3) of the reflector (2) via adhesive spots (7). The diameter of the adhesive spots (7) is 8 mm. There are 8 adhesive spots (7) on each Bipod support (1), and there are a total of 24 adhesive spots (7) on the three Bipod support members (1).

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