A lattice sandwich thermal protection structure having low thermal expansion properties

Abstract

The application discloses a dot-matrix sandwich heat protection structure with low thermal expansion characteristics, and relates to the technical field of dot-matrix sandwich panels.The dot-matrix sandwich heat protection structure comprises an upper skin, a lower skin and a sandwich panel unit arranged between the upper skin and the lower skin, wherein the sandwich panel unit comprises a plurality of honeycomb assemblies, the plurality of honeycomb assemblies are connected in concave-convex mode, two adjacent honeycomb assemblies are arranged in uniform mode with their side edges coinciding with each other, and the thermal expansion coefficients of the two sides of the side edges of the honeycomb assemblies are different.The distance change when the protrusions at two ends are deformed can be controlled by adjusting the size of the linear structure parameters and the difference of the selected materials, so that the change of the overall thermal expansion coefficient of the sandwich panel unit is regulated and controlled, the difference between the thermal expansion coefficients of the sandwich panel unit and the upper skin and the lower skin is reduced, the thermal stress caused by the mismatch of thermal deformation is avoided, the upper skin and the lower skin are prevented from being separated from the sandwich panel unit, and the overall stable structure is prevented from being damaged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dot matrix sandwich panel, in particular to a dot matrix sandwich heat protection structure with low thermal expansion characteristics. BACKGROUND

[0002] The honeycomb sandwich structure is a structure widely used in the field of aerospace. Taking a common honeycomb sandwich panel applied to the satellite reflecting surface as an example, the upper and lower surfaces of the honeycomb sandwich panel are made of anisotropic carbon fiber skin, and the core in the middle is a hexagonal hard aluminum alloy honeycomb. The skin is used as the mounting surface of the structure, and the local deformation of the skin is used as an important index, which will directly affect the installation accuracy and performance of the structure. Such a structure will inevitably produce a large thermal stress during the curing process and the temperature rising and falling process of the working environment due to the order of magnitude difference between the thermal expansion coefficients of the skin and the sandwich panel, which may even cause structural damage such as debonding or cause a large thermal deformation to affect the structural accuracy and cause functional damage. Therefore, we propose a dot matrix sandwich heat protection structure with low thermal expansion characteristics. SUMMARY

[0003] The present application relates to the technical field of dot matrix sandwich panel, in particular to a dot matrix sandwich heat protection structure with low thermal expansion characteristics.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a dot matrix sandwich heat protection structure with low thermal expansion characteristics, comprising an upper skin, a lower skin and a sandwich panel unit arranged between the upper skin and the lower skin, the sandwich panel unit comprising a plurality of honeycomb assemblies, the plurality of honeycomb assemblies being connected in concave-convex manner, and the side edges of adjacent two honeycomb assemblies being coincided with each other and being uniformly arranged as a whole.

[0005] The thermal expansion coefficients of the two sides of the plurality of side edges of the honeycomb assembly are different, and the protrusion degrees of the plurality of side edges of the honeycomb assembly are the same under the same heating deformation condition.

[0006] Further, the upper skin, the lower skin and the sandwich panel unit are parallel to each other, and the surface of the sandwich panel unit in contact with the upper skin and the lower skin is a low thermal expansion surface.

[0007] Further, the upper skin and the lower skin are made of carbon fiber material, and the upper skin, the lower skin and the sandwich panel unit are fixedly connected in a glue bonding manner.

[0008] Further, the number of side edges of the honeycomb assembly is set to be multiple, and each side edge is a linear structure.

[0009] Further, the linear structure comprises a straight plate one, protrusions are fixedly connected to both ends of one side of the straight plate one, and the protrusions are in the shape of a cuboid as a whole.

[0010] The two ends of the other side of the straight plate are provided with grooves, and the straight plate two is embedded in the grooves, and the side surface of the straight plate two is in contact with the side surface of the straight plate one.

[0011] Further, the straight plate two is located at one side of the side edge of the honeycomb assembly, the straight plate one is located at the other side of the side edge of the honeycomb assembly, the straight plate two is made of aluminum alloy, the straight plate one is made of stainless steel, and the thermal expansion coefficient of the straight plate two is greater than that of the straight plate one.

[0012] Further, the set parameters of the low thermal expansion performance of the linear structure are:

[0013]

[0014] Wherein:

[0015]

[0016]

[0017] Wherein l is the original length before expansion, h is the height of the protrusion, a1 and a2 are the widths of the two materials, m is the width ratio a1 / a2 of the two materials, E1 and E2 are the Young's moduli of the two materials, n is the Young's modulus ratio E1 / E2 of the two materials, α1 and α2 are the thermal expansion coefficients of the two materials, k is the thermal expansion coefficient ratio α1 / α2 of the two materials, and T is the temperature change.

[0018] Further, a plurality of the linear structures share the inner side edges of the protrusions as common edges, the straight plates one are arranged alternately to form a whole and constitute a honeycomb assembly.

[0019] Further, the overall shape of the honeycomb assembly is set as any one of a regular triangle, a square or a regular hexagon.

[0020] Further, the plurality of honeycomb assemblies share the inner side edges of the protrusions as common edges to form a whole and constitute a sandwich panel unit.

[0021] The present application has at least the following advantages:

[0022] 1. In the present application, since each linear structure is completely the same, the bending degree of the protrusion after thermal deformation is also completely the same, and the deformation of the linear structure will not produce additional stress due to the deformation of the adjacent linear structure, and the thermal expansion coefficient description of the adjacent edges in the overall honeycomb assembly is completely consistent with the thermal expansion coefficient of the two edges inside the protrusion of the isolated linear structure in theory.

[0023] 2. The present application can control the distance change when the protrusions at both ends are deformed by adjusting the size of the linear structure parameter and the difference of the selected material, thereby realizing the regulation and control of the overall thermal expansion coefficient change of the sandwich panel unit, reducing the difference of the thermal expansion coefficient between the sandwich panel unit and the upper and lower skins, avoiding thermal stress due to thermal deformation mismatch, causing the upper and lower skins and the sandwich panel unit to separate, and destroying the overall stable structure.

[0024] 3. In the present application, a groove is designed, and the two materials with different thermal expansion coefficients are connected in a locking manner. The advantage of this design is that only a single material straight plate needs to be prepared, without the need to prepare a curved plate or joint different materials, effectively reducing the preparation difficulty; at the same time, after being heated and bent, a gap is generated between the two materials, which can effectively reduce the stress concentration of the bending surface compared with the contact surface of the two materials.

[0025] 4. In the present application, by setting a protrusion on the straight plate, compared with an ordinary double-material straight rod, the influence of bending on the thermal expansion coefficient of the structure is effectively amplified, the change range of the thermal expansion coefficient of the structure is expanded, the continuous regulation and control of the thermal expansion coefficient from positive, zero, and negative values can be realized, and the structural thermal stress is reduced; at the same time, since the protrusion realizing low thermal expansion is of the same material, welding between multiple straight plates or direct overall design and preparation can be easily realized, which is convenient for constructing a low-thermal-expansion dot matrix structure.

[0026] Of course, any product implementing the present application does not necessarily need to achieve all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a three-dimensional schematic diagram of the overall structure of the present application.

[0028] Figure 2 It is a three-dimensional schematic diagram of the honeycomb assembly structure of the present application.

[0029] Figure 3 It is a schematic diagram of the mutual connection state of the honeycomb assembly structure of the present application.

[0030] Figure 4 It is a schematic diagram of the thermal state of the sandwich panel unit structure of the present application.

[0031] Figure 5 It is a schematic diagram of the thermal state of the linear structure of the present application.

[0032] REFERENCE NUMERALS:

[0033] 1, upper panel; 2, lower panel; 3, sandwich panel unit; 4, honeycomb assembly; 5, linear structure; 6, straight plate one; 7, protrusion; 8, groove; 9, straight plate two. DETAILED DESCRIPTION

[0034] With reference to the drawings of the embodiments of the present disclosure, the technical solutions in the embodiments of the present disclosure will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present disclosure.

[0035] Please refer to Figures 1-5 The present disclosure provides a technical solution: a dot matrix sandwich heat protection structure with low thermal expansion characteristics, comprising an upper skin, a lower skin and a sandwich plate unit 3 arranged between the upper skin and the lower skin, the sandwich plate unit 3 comprising a plurality of honeycomb assemblies 4, the plurality of honeycomb assemblies 4 being connected in concave-convex, and the side edges of the adjacent two honeycomb assemblies 4 coinciding with each other, and being uniformly arranged as a whole.

[0036] The thermal expansion coefficients of the two sides of the plurality of side edges of the honeycomb assembly 4 are different, and the plurality of side edges of the honeycomb assembly 4 are deformed to the same extent under the same heating condition.

[0037] The upper skin, the lower skin and the sandwich plate unit 3 are parallel to each other, and the surface of the sandwich plate unit 3 in contact with the upper skin and the lower skin is a low thermal expansion surface. For the technical solution of the present embodiment, the upper skin and the lower skin are made of carbon fiber material, and the upper skin, the lower skin and the sandwich plate unit 3 are fixedly connected by adhesive.

[0038] The overall shape of the honeycomb assembly is set as any one of a regular triangle, a square or a regular hexagon, that is, the number of side edges of the honeycomb assembly can be set as a triangle, a quadrilateral or a hexagon. When the number of side edges of the honeycomb assembly is a triangle, the directions of the side edges are the same, and when the number of side edges of the honeycomb assembly is a quadrilateral or a hexagon, the opposite side edges are symmetrically arranged. For the technical solution of the present embodiment, the number of side edges of the honeycomb assembly 4 is set to four, and each side edge is a linear structure 5, as shown in Figure 2 .

[0039] Further, as shown in Figure 5 , the linear structure 5 comprises a straight plate one 6, both ends of one side of the straight plate one 6 are fixedly connected with protrusions 7, and the protrusions 7 are in the shape of a cuboid as a whole.

[0040] Grooves 8 are formed at both ends of the other side of the straight plate one 6, and a straight plate two 9 is embedded in the grooves 8, and the side surface of the straight plate two 9 is in contact with the side surface of the straight plate one 6.

[0041] According to the technical scheme of the embodiment, the straight plate two 9 is located at one side of the side edge of the honeycomb assembly 4, and the straight plate one 6 is located at the other side of the side edge of the honeycomb assembly 4. According to the technical scheme of the embodiment, the straight plate two 9 is made of aluminum alloy, and the straight plate one 6 is made of stainless steel. The thermal expansion coefficient of the straight plate two 9 is greater than that of the straight plate one 6. Due to the difference in the thermal expansion coefficients of the two materials, when heated, the linear structure 5 as a whole protrudes to the side of the straight plate two 9, that is, protrudes to one side of the straight plate two 9. At this time, the bending deformation causes the distance between the two end protrusions 7 to change, as shown in Figure 5 By adjusting the size of the linear structure 5 and the selected material, the distance change of the two end protrusions 7 when deformed can be controlled, thereby realizing the adjustment and control of the overall thermal expansion coefficient of the sandwich panel unit 3, reducing the difference in the thermal expansion coefficients between the sandwich panel unit 3 and the upper and lower skins, avoiding thermal stress due to thermal deformation mismatch, and preventing the upper and lower skins from separating from the sandwich panel unit 3, thereby destroying the overall stable structure.

[0042] Further, the width of the straight plate one 6 is equal at each position in the low thermal expansion plane, the width of the straight plate one 6 is equal to that of the straight plate two 9, and the corners and grooves 8 of the overall structure are chamfered to avoid stress concentration, facilitate processing, and make the stress uniformly distributed.

[0043] Further, as shown in Figure 2 The four linear structures 5 share the inner side edges of the protrusions 7 as a common edge, the multiple straight plates one 6 are arranged alternately in concave and convex shapes to form an overall structure, and constitute a honeycomb assembly 4. The opposite linear structures 5 of the honeycomb assembly 4 are symmetrical to each other, and the overall structure is an anti-symmetrical curved structure, which meets the performance requirement of high stiffness.

[0044] Further, the set parameters of the low thermal expansion performance of the linear structure 5 are as follows:

[0045]

[0046] Wherein:

[0047]

[0048]

[0049] Wherein, l is the original length before expansion between the protrusions 7, h is the height of the protrusion 7, a1 and a2 are the widths of the straight plate one 6 and the straight plate two 9, m is the ratio a1 / a2 of the widths of the straight plate one 6 and the straight plate two 9, E1 and E2 are the Young's moduli of the straight plate one 6 and the straight plate two 9, n is the ratio E1 / E2 of the Young's moduli of the straight plate one 6 and the straight plate two 9, α1 and α2 are the thermal expansion coefficients of the straight plate one 6 and the straight plate two 9, k is the ratio α1 / α2 of the thermal expansion coefficients of the straight plate one 6 and the straight plate two 9, and T is the temperature change.

[0050] For the technical scheme of the embodiment, as shown in Figure 3 The multiple honeycomb assemblies 4 form an integral whole with the inner side edges of the protrusions 7 as the common edges, constituting the sandwich panel unit 3. Since the linear structures 5 deform to the same extent after being heated, the sandwich panel unit 3 will not generate additional stress after being heated and deformed.

[0051] It should be noted that the entire sandwich panel unit 3 can be prepared by welding or hinging the multiple linear structures 5 to form the honeycomb assemblies 4, and then welding or hinging the multiple honeycomb assemblies 4 to form an integral whole. Alternatively, the entire sandwich panel unit 3 can be prepared by integral wire cutting or 3D printing. For the technical scheme of the embodiment, since the straight plates one 6 contained in the sandwich panel unit 3 are made of the same material, the sandwich panel unit 3 is prepared by wire cutting or 3D printing to form an integral frame composed of multiple straight plates one 6. For local damage, local welding can be used for repair, and then 3D printing or wire cutting can be used to prepare multiple straight plates two 9, which are embedded in the grooves to form the entire sandwich panel unit 3.

[0052] Wire cutting is developed on the basis of electric spark perforation and forming processing. It is a processing method that uses a moving metal wire (molybdenum wire, copper wire or alloy wire) as an electrode wire, relies on the pulse electric spark discharge between the electrode wire and the workpiece to generate high temperature to melt or vaporize the metal, forms a cutting seam, and thus cuts out a part. Wire cutting is prior art and will not be described here.

[0053] 3D printing (3DP) is a kind of rapid prototyping technology, also known as additive manufacturing. It is a technology that uses digital model files as the basis, uses powder-like metal or plastic, and other materials that can be bonded, and constructs objects through layer-by-layer printing. This will not be described here.

[0054] The points on the two edges of the inner side of the top end of the protrusion 7 of the straight plate one 6 have a set low thermal expansion property in the planes parallel to the heat protection point array sandwich panel.

[0055] In summary, in the present application, since each linear structure 5 is completely identical, the bending degree of the protrusion 7 after thermal deformation is also completely identical, the deformation of the linear structure 5 will not generate additional stress due to the deformation of the adjacent linear structure 5, the thermal expansion coefficient of the adjacent edges in the overall honeycomb assembly 4 is theoretically completely consistent with the thermal expansion coefficient of the two edges inside the protrusion 7 of the isolated linear structure 5, and by adjusting the size of the linear structure 5 parameters and the difference of the selected materials, the distance change when the protrusion 7 at both ends deforms can be controlled, thereby realizing the adjustment and control of the overall thermal expansion coefficient change of the sandwich panel unit 3, thereby reducing the thermal expansion coefficient difference between the sandwich panel unit 3 and the upper skin and the lower skin, avoiding thermal stress due to thermal deformation mismatch, causing the upper skin, the lower skin and the sandwich panel unit 3 to separate, and the overall stable structure is damaged.

[0056] It should be noted that in this document, the terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0057] For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to specific circumstances. When an element is referred to as "assembled", "mounted", "fixed" or "disposed" on another element, it can be directly on another element or there can be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and are not the only implementation.

[0058] Although embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

[0059] In the description of the disclosure, the description of the terms "one embodiment", "an example", "a specific example", and the like, means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the disclosure. In the description of the disclosure, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. A lattice sandwich thermal protection structure having low thermal expansion characteristics, comprising an upper skin, a lower skin, and a sandwich panel unit disposed between the upper skin and the lower skin, characterized in that, The sandwich plate unit comprises a plurality of honeycomb assemblies, the plurality of honeycomb assemblies are connected in concave-convex mode, and the side edges of two adjacent honeycomb assemblies coincide with each other and are uniformly arranged as a whole; The thermal expansion coefficients of the two sides of the plurality of side edges of the honeycomb assembly are different, and the plurality of side edges of the honeycomb assembly are deformed to the same extent under the same heating condition; The number of the side edges of the honeycomb assembly is set to be multiple, and each side edge is a linear structure; The linear structure comprises a straight plate one, protrusions are fixedly connected to the two ends of one side of the straight plate one, and the protrusions are in the shape of a cuboid as a whole; Grooves are formed in the two ends of the other side of the straight plate one, a straight plate two is embedded in the grooves, and the side surface of the straight plate two is in contact with the side surface of the straight plate one; The plurality of linear structures take the inner side edges of the protrusions as common edges, the plurality of straight plates one are arranged in concave-convex mode, form a whole, and constitute a honeycomb assembly; The plurality of honeycomb assemblies take the inner side edges of the protrusions as common edges, form a whole, and constitute a sandwich plate unit.

2. The lattice sandwich thermal protection structure with low thermal expansion characteristics according to claim 1, characterized in that: The upper skin, the lower skin and the sandwich plate unit are parallel to each other, and the surface of the sandwich plate unit in contact with the upper skin and the lower skin is the low-thermal-expansion surface.

3. A lattice sandwich thermal protection structure having low thermal expansion properties according to claim 2, characterized in that: The upper skin and the lower skin are made of carbon fiber material, and the upper skin, the lower skin and the sandwich plate unit are fixedly connected in adhesive mode.

4. The lattice sandwich thermal protection structure according to claim 3, wherein: The straight plate two is located on one side of the side edge of the honeycomb assembly, the straight plate one is located on the other side of the side edge of the honeycomb assembly, the straight plate two is made of aluminum alloy material, the straight plate one is made of stainless steel material, and the thermal expansion coefficient of the straight plate two is greater than that of the straight plate one.

5. A lattice sandwich thermal protection structure having low thermal expansion characteristics according to claim 4, characterized in that: The overall shape of the honeycomb assembly is set to be any one of a regular triangle, a square or a regular hexagon.

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