A SiC main support structure for large-aperture full-spectrum hyperspectral payloads

Abstract

The present invention provides a SiC main support structure for large-aperture full-spectrum hyperspectral loads, which solves the problem that the existing main support structure is difficult to meet the stringent requirements of lightweight, high precision and high stability under large-aperture and multi-load conditions. The main support structure includes a substrate made of SiC material; the front of the substrate is divided into a left area, a middle area and a right area by two mutually parallel first reinforcing ribs; a lens group mounting hole is provided in the middle of the middle area, and a plurality of triangular weight-reducing grooves are provided in the part other than the lens group mounting hole; the left area and the right area have the same structure and are symmetrically distributed in the middle area, and a plurality of triangular weight-reducing grooves are provided in both the left area and the right area; the reverse side of the substrate is a plane, on which a plurality of threaded holes for mounting optical components are provided, and the plurality of threaded holes are provided on the groove wall of the triangular weight-reducing groove.

Description

Technical Field

[0001] The invention relates to a main supporting structure of an aerospace optical-mechanical payload system, and in particular to a SiC main supporting structure for a large-aperture, full-spectrum, and hyperspectral payload. Background Art

[0002] With the development of aerospace remote sensing technology, the action distance is getting farther and farther, and the measurement accuracy is getting higher and higher, which will inevitably lead to larger optical apertures. For large-aperture optical remote sensing equipment, the main support structure, as the skeleton structure of the remote sensing equipment, must ensure the high stability and high reliability of the optical system. The main support structure of remote sensing equipment mainly includes thin-walled cylinder type, box type, frame type, truss type and other forms.

[0003] The thin-walled cylindrical main support structure has the characteristics of high rigidity, good overall structural stability, convenient detection and installation, and is conducive to temperature control and suppression of stray light. It is generally used in support structures that have high requirements for structural stability and relatively loose weight control. Its disadvantage is that it is heavy and has a low weight reduction rate. It is not suitable for lightweight, high-precision, and high-stability remote sensing cameras.

[0004] The box-type main support structure has high rigidity and strength, good overall stability, and is mainly used in multi-reflector off-axis complex optical system cameras. The high-strength box-type structure is heavy, and as the lightweight degree of space cameras increases, the box-type structure is gradually replaced by a lighter structure.

[0005] The frame-type main support structure has excellent rigidity, good spatial stability, and a low degree of lightweight. It is suitable for the main support structure of small and medium-sized off-axis systems, but is not suitable for remote sensing cameras with a high degree of lightweight.

[0006] The truss support structure is characterized by high specific stiffness, flexible assembly, simple form, and strong designability. It is generally suitable for large and medium-sized, SLR and multi-reflex, coaxial and off-axis space cameras, but is not suitable for lightweight, high-precision, and high-stability remote sensing cameras.

[0007] With the stringent requirements for remote sensing cameras to be lightweight, high-precision, and high-stability, the main support structure needs to have the following characteristics: (1) Good dynamic mechanical properties and modal distribution to avoid resonance between the optical load and the satellite platform and cause structural damage; (2) Good mechanical properties. The deformation and position change of the optical elements caused by the deformation of the main support structure must be within the design requirements; (3) High thermal stability. When the ambient temperature changes, the main support structure must ensure a stable shape and size; (4) Due to the large number of loads, the main support structure must be easy to debug with multiple optical loads; (5) The interface between the main support structure and the optical elements must be reasonable to reduce the transfer of assembly stress; (6) Good processing and assembly performance. The above main support structure has more or less shortcomings and is difficult to meet actual needs.

[0008] The development of the main support structure of space remote sensing cameras presents the following characteristics: the structural form is integrated and combined. The integrated design of the main support structure is to integrate the support parts of each part of the optical element together (integrated molding), which can remove a large number of embedded parts and connectors, reducing the weight and weakening the connection stress and deformation of the support parts. However, the local integrated support structure is currently only applicable to small space cameras.

[0009] The combined main support structure is a new support structure that combines two or more support forms through complementary advantages. The typical thin-walled tube and rod combination structure has good dynamic stiffness and overall stability, and is easy to process and assemble. The more traditional and commonly used main support structure materials at home and abroad are mainly hard aluminum alloy, titanium alloy and Invar. Hard aluminum alloy is mainly used in the main support structure of space cameras with a high degree of lightweight and low thermal stability requirements; titanium alloy has a small linear expansion coefficient and is widely used in space cameras; Invar has the characteristics of high strength and designable linear expansion coefficient, and is used in the main support structure of space cameras with different reflector materials.

[0010] The above are the more traditional materials for the main support structure of space cameras. With the development of the materials industry, various new materials are constantly being used to make the main support structure of space cameras. At present, the main materials with high specific stiffness and whose material forming processes have been greatly developed are carbon fibers. Carbon fiber composite materials have the characteristics of high specific stiffness, high strength, high damping, low density, low expansion coefficient and designable performance. They meet the requirements of the integrated design of light, machine and heat of space optical cameras and have been widely used in the main support structure of space cameras. Due to the anisotropy of carbon fiber materials, the main support structure of space requires a large number of metal embedded parts, which leads to an increase in the overall quality of the support structure. It is difficult to meet the requirements of high stiffness and ultra-lightness at the same time. At the same time, it is difficult to ensure the overall stability of the support structure under complex working conditions. Summary of the invention

[0011] The purpose of the present invention is to solve the problem that the structural form of the existing main support structure is difficult to meet the stringent requirements of lightweight, high precision and high stability of large-aperture cameras, and to provide a SiC main support structure for large-aperture full-spectrum hyperspectral loads, which can achieve high stability while ensuring stiffness, strength and lightweight.

[0012] To achieve the above purpose, the technical solution provided by the present invention is:

[0013] A SiC main support structure for large-aperture full-spectrum hyperspectral loads, which is special in that: it includes a substrate made of SiC material; the front side of the substrate is divided into a left area, a middle area and a right area by two mutually parallel first reinforcing ribs; a lens group mounting hole is opened in the middle of the middle area, and a plurality of triangular weight-reducing grooves are provided in the part other than the lens group mounting hole; the left area and the right area have the same structure and are symmetrically distributed with respect to the middle area, and a plurality of triangular weight-reducing grooves are provided in both the left area and the right area; the reverse side of the substrate is a plane, on which a plurality of threaded holes for mounting optical components are provided, and the plurality of threaded holes are all opened on the groove wall of the triangular weight-reducing groove.

[0014] Furthermore, the heights of the left area and the right area gradually decrease from close to the middle area to far away from the middle area, which can reduce the weight of the product while ensuring the overall strength.

[0015] Furthermore, the left region is provided with N second reinforcing ribs perpendicular to the first reinforcing ribs, thereby dividing the left region into N+1 units; the height of the second reinforcing ribs is equal to the height of the first reinforcing ribs.

[0016] Furthermore, the middle area is also provided with two third reinforcing ribs that are perpendicular to the first reinforcing rib and parallel to each other. The two third reinforcing ribs are respectively located on both sides of the lens group mounting hole, and the height of the third reinforcing ribs is equal to the height of the first reinforcing ribs; and multiple fourth reinforcing ribs are arranged between the lens group mounting hole and the first and third reinforcing ribs.

[0017] Furthermore, the lens assembly mounting hole is a stepped hole, the large hole of the stepped hole is located on the front side of the substrate, the small hole of the stepped hole is located on the back side of the substrate, and a plurality of fifth reinforcing ribs are provided along the circumferential direction between the hole wall and the hole bottom of the large hole of the stepped hole.

[0018] Furthermore, the groove wall heights of all triangular weight-reducing grooves are lower than the height of the first reinforcing ribs.

[0019] Furthermore, a plurality of optical component installation interfaces are provided on the middle region and on two end surfaces perpendicular to the first reinforcing rib.

[0020] Furthermore, N is 3, and the three second reinforcing ribs are evenly distributed in the left area.

[0021] Furthermore, the second reinforcing rib and the third reinforcing rib are both arranged at positions overlapping with the groove wall of the triangular weight-reducing groove.

[0022] Furthermore, the substrate has a length of 2600 mm, a width of 2100 mm, and a thickness of 150 mm.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] 1. The support substrate of the present invention is made of SiC material, which has the characteristics of high specific stiffness, high thermal conductivity, good thermal control performance, moderate thermal expansion coefficient, and isotropic properties. The substrate can achieve homogeneity of the optical components and support structures installed thereon, reduce stress and deformation between structures, avoid structural deformation and surface shape changes caused by different thermal expansion coefficients of materials, and can adapt well to temperature changes to ensure the imaging quality of the optical system;

[0025] The reverse side of the substrate is a plane for mounting multiple optical components. The multiple optical components are on the same reference plane, which enables convenient installation and adjustment between the optical components. The front side of the substrate is provided with weight-reducing triangular grooves and reinforcing ribs, which can meet the high rigidity and high stability requirements for mounting optical components while achieving lightweight requirements.

[0026] 2. The heights of the left and right areas on the front side of the substrate of the present invention gradually decrease from close to the middle area to far away from the middle area, which can reduce the weight of the product while ensuring the overall strength.

[0027] 3. The front side of the base plate of the present invention is provided with reinforcing ribs, which improves the stability of the base plate.

[0028] 4. The lens assembly mounting hole of the present invention is a stepped hole, which is convenient for installing the optical lens assembly.

[0029] 5. The present invention provides optical component installation interfaces at both end surfaces of the middle area, so that multiple load installations can be achieved.

[0030] 6. The substrate of the present invention has high rigidity and a high structural fundamental frequency, which can reach above 200 Hz. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of a SiC main support substrate according to an embodiment of the present invention;

[0032] Figure 2 This is a front view of a SiC main support substrate according to an embodiment of the present invention;

[0033] Figure 3 FIG. 1 is a top view of a SiC main support substrate according to an embodiment of the present invention.

[0034] The descriptions of the numbers in the figure are as follows:

[0035] 1-rear side, 2-front side, 21-left area, 22-middle area, 23-right area, 24-mirror assembly mounting hole;

[0036] 3-triangular weight-reducing groove; 4-first reinforcing rib, 5-second reinforcing rib, 6-third reinforcing rib, 7-fourth reinforcing rib, 8-fifth reinforcing rib, 9-optical component mounting interface. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0038] SiC material has the characteristics of high specific stiffness, high thermal conductivity, good thermal stability, moderate thermal expansion coefficient, and isotropy. Lightweight optical reflectors are mostly made of sintered silicon carbide. By using sintered silicon carbide as the main support structure for the load, the homogeneous design reduces the stress and deformation between the structures, which is beneficial for ensuring the surface accuracy and overall stability of the reflector. Therefore, this example selects SiC material for the main support structure of large-aperture full-spectrum spectral loads to achieve the high lightweight and high stability requirements of the main support structure. SiC material not only has a high specific stiffness, but also has outstanding advantages in mechanical properties and thermal properties. It can not only reduce the weight of the structure, but also improve the structure's ability to resist deformation under complex working conditions, thereby ensuring the overall stability of the structure.

[0039] like Figures 1 to 3 As shown, this example provides a SiC main support structure for large-aperture full-spectrum hyperspectral payloads, including the use of Si The invention relates to a substrate made of C material; the front side 2 of the substrate is divided into a left area 21, a middle area 22 and a right area 23 by two mutually parallel first reinforcing ribs 4; a lens assembly mounting hole 24 is opened in the middle of the middle area 22, and a plurality of triangular weight-reducing grooves 3 are arranged in the part other than the lens assembly mounting hole 24; the left area 21 and the right area 23 have the same structure and are symmetrically distributed with respect to the middle area 22, and a plurality of triangular weight-reducing grooves 3 are arranged in both the left area 21 and the right area 23; the height of the triangular weight-reducing grooves 3 is lower than the height of the first reinforcing rib 4, and the front side 2 of the substrate adopts the triangular weight-reducing grooves 3 to achieve lightweight design and the arrangement of the first reinforcing rib 4, which can meet the design requirements of high stiffness and high stability of the load through theoretical calculation simulation; the back side 1 of the substrate is a plane, on which a plurality of threaded holes for mounting optical components (optical loads) are arranged, and the plurality of threaded holes are opened on the groove wall of the triangular weight-reducing grooves 3, and the back side 1 of the substrate can bear a plurality of optical loads, so as to realize the convenience of installation and adjustment between the plurality of loads.

[0040] At present, the main reflectors of large-aperture optical systems and most relay reflectors use SiC as the mirror blank material. The design of the SiC support substrate can achieve homogeneous design of the mirror body and the supporting structure, avoid structural deformation and surface shape changes caused by different thermal expansion coefficients of the materials, and can adapt well to temperature changes to ensure the imaging quality of the optical system.

[0041] In the support structure of this embodiment, the heights of the left area 21 and the right area 23 gradually decrease from close to the middle area 22 to far away from the middle area 22; the left area 21 is provided with two second reinforcing ribs 5 perpendicular to the first reinforcing ribs 4, thereby dividing the left area 21 into three units, and the two second reinforcing ribs 5 are evenly distributed in the left area 21, and the height of the second reinforcing ribs 5 is equal to the height of the first reinforcing ribs 4; the middle area 22 is also provided with two third reinforcing ribs 6 perpendicular to the first reinforcing ribs 4 and parallel to each other, and the two third reinforcing ribs 6 are respectively located on both sides of the lens assembly mounting hole 24, and the height of the third reinforcing ribs 6 is equal to the height of the first reinforcing ribs 4; a plurality of fourth reinforcing ribs 7 are provided between the lens assembly mounting hole 24 and the first reinforcing ribs 4 and the third reinforcing ribs 6, preferably 6, and the 6 fourth reinforcing ribs 7 are distributed in a "M" shape on the periphery of the lens assembly mounting hole 24;

[0042] In order to facilitate the installation of the optical mirror on the lens group mounting hole 24, the lens group mounting hole 24 is a stepped hole, the large hole of the stepped hole is located on the front side 2 of the substrate, the small hole of the stepped hole is located on the back side 1 of the substrate, and a plurality of fifth reinforcing ribs 8 are arranged in the circumferential direction in the large hole of the stepped hole. Preferably, there are six fifth reinforcing ribs 8, and the vertical section of the fifth reinforcing rib 8 is a right triangle, and the two right-angled sides of the right triangle are fixedly connected to the substrate outside the large hole of the stepped hole.

[0043] In this embodiment, optical component installation interfaces are provided at both end surfaces of the middle area, and their function is to realize multi-load installation. The front mirror system is installed on the front end surface, and each optical load module is installed on the rear end.

[0044] In this embodiment, a plurality of optical component mounting interfaces 9 are provided on the middle region 22 and on two end faces perpendicular to the first reinforcing rib 4 ; the second reinforcing rib 5 and the third reinforcing rib 6 are arranged at positions overlapping with the groove walls of the triangular weight-reducing groove 3 .

[0045] The substrate of this embodiment has a high load-bearing capacity and can carry an optical load of up to 700kg; the substrate of this embodiment has high stability under overload, and the maximum deformation due to its own weight does not exceed 0.005mm. Under an overload of 10g, the maximum deformation does not exceed 0.05mm.

[0046] Function of the main support substrate

[0047] The main supporting substrate structure serves as the "skeleton structure" of the remote sensing equipment, on which the optical payload needs to be installed. The large-size structure requires high stability and is the structural foundation of the entire optical payload. Its main functions include: 1) The back side 1 of the substrate directly provides structural support and installation interface for the optical payload. The back side of the substrate is a plane. The back surface of the substrate is used as the test benchmark for each optical payload, the overall test benchmark for the payload, and the payload and satellite installation benchmark with high precision; and the threaded holes on the back side are used as the installation interface; 2) The front side 2 of the substrate provides structural support for the optical mirror assembly; 3) It undertakes the interface structure function between the entire optical payload and the satellite platform; 4) It undertakes the interface structure function between the optical payload and the ground tooling during the final assembly operation.

[0048] The structural design of the main supporting substrate can achieve high-position precision and stable support for optical elements. The substrate structure adopts a flat reinforced support structure to increase strength.

[0049] Lightweight design of main support base structure

[0050] The design dimensions of the support substrate are: length: 2600mm, width: 2100mm, height (overall thickness): 150mm. As a common connection platform for optical components, the high rigidity and high stability of the support substrate are the key to ensuring the imaging quality of the entire optical system. While ensuring rigidity and strength, it is lightweight. The overall triangular weight-reducing groove design is adopted. The average thickness of the reinforcement ribs is 5mm to 8mm, and the thickness of the front panel is not more than 10mm (the total thickness minus the height of the reinforcement ribs, that is, the pure thickness without the reinforcement ribs). The substrate material is sintered SiC, and the overall weight is 320kg.

[0051] The front side 2 of the support substrate is used to connect the primary mirror and secondary mirror components, and fix the light shield component through the truss structure, and the other side is used to connect the optical components; a common reference is established on the upper and lower surfaces, center circle, side surface, etc. of the substrate, which serves as the processing reference of the substrate, the installation and positioning reference of each optical module, the test reference of each optical module, the overall test reference of the load, and the reference for the installation of the load and the satellite, etc. The use of a unified reference for the installation and testing of each optical load can achieve a higher position accuracy and facilitate installation and adjustment.

[0052] Finite element simulation analysis and verification of the main support base

[0053] In order to verify the design status of the SiC main support substrate, the substrate was subjected to finite element simulation analysis and verification to study the free mode and gravity deformation of the main support substrate. The SiC material parameters used in the design are shown in Table 1

[0054] Table 1 Material properties

[0055]

[0056] Through analysis, the first ten modes of the main support substrate are extracted. The modal analysis is shown in Table 2. The fundamental frequency of the part is 206.8 Hz. The large-sized main support substrate has high structural stiffness and can meet the support requirements for optical loads.

[0057] Table 2 Modal analysis results

[0058] Degree frequency 1 206.8 2 354.7 3 528.2 4 881.1 5 1184.1 6 1244.6 7 1427.5 8 1678.5 9 1855.8 10 1931.4

[0059] By applying its own gravity load to the main support substrate in the normal direction and performing static simulation analysis, the deformation of the main support substrate under gravity load is obtained. The maximum deformation at the upper and lower parts of the center is 0.007mm, and the deformation gradually decreases to both sides. The deformation of the main mirror installation position on the front side 2 is 0.0037mm, and the deformation of the optical component installation platform position on the back side 1 is 0.0018mm, which can meet the positional dimensional accuracy between the loads carried.

Claims

1. A SiC main support structure for large-aperture full-spectrum hyperspectral payloads, characterized by: Including a substrate made of SiC material; The front side (2) of the substrate is divided into a left area (21), a middle area (22) and a right area (23) by two mutually parallel first reinforcing ribs (4); A lens assembly mounting hole (24) is provided in the middle of the middle region (22), and a plurality of triangular weight-reducing grooves (3) are provided in the portion outside the lens assembly mounting hole (24); The left area (21) and the right area (23) have the same structure and are symmetrically distributed around the middle area (22). Both the left area (21) and the right area (23) are provided with a plurality of triangular weight-reducing grooves (3); The reverse side (1) of the substrate is a plane, on which a plurality of threaded holes for mounting optical components are provided, and the plurality of threaded holes are all opened on the groove wall of the triangular weight-reducing groove (3); The heights of the left region (21) and the right region (23) gradually decrease from being close to the middle region (22) to being away from the middle region (22); The left region (21) is provided with N second reinforcing ribs (5) perpendicular to the first reinforcing ribs (4), thereby dividing the left region (21) into N+1 units; The height of the second reinforcing rib (5) is equal to the height of the first reinforcing rib (4); The middle area (22) is further provided with two third reinforcing ribs (6) perpendicular to the first reinforcing rib (4) and parallel to each other, the two third reinforcing ribs (6) being respectively located on both sides of the lens assembly mounting hole (24), and the height of the third reinforcing rib (6) being equal to the height of the first reinforcing rib (4); A plurality of fourth reinforcing ribs (7) are arranged between the lens assembly mounting hole (24) and the first reinforcing rib (4) and the third reinforcing rib (6); The second reinforcing rib (5) and the third reinforcing rib (6) are both arranged at positions that coincide with the groove wall of the triangular weight-reducing groove (3).

2. The SiC main support structure for large-aperture full-spectrum hyperspectral payload according to claim 1, characterized in that: The lens assembly mounting hole (24) is a stepped hole, the large hole of the stepped hole is located on the front side (2) of the substrate, the small hole of the stepped hole is located on the back side (1) of the substrate, and a plurality of fifth reinforcing ribs (8) are provided along the circumferential direction between the hole wall and the hole bottom of the large hole of the stepped hole.

3. A SiC main support structure for large-aperture full-spectrum hyperspectral payload according to claim 2, characterized in that: The groove wall heights of all triangular weight-reducing grooves (3) are lower than the height of the first reinforcing ribs (4).

4. The SiC main support structure for large-aperture full-spectrum hyperspectral payload according to claim 3, characterized in that: A plurality of optical component mounting interfaces (9) are provided on the middle area (22) and on two end surfaces perpendicular to the first reinforcing rib (4).

5. The SiC main support structure for large-aperture full-spectrum hyperspectral payload according to claim 1, characterized in that: The N is 3, and the three second reinforcing ribs (5) are evenly distributed in the left area (21).

6. The SiC main support structure for large-aperture full-spectrum hyperspectral payload according to claim 1, characterized in that: The substrate has a length of 2600 mm, a width of 2100 mm, and a thickness of 150 mm.

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