Low thermal expansion sandwich panel structure for metal thermal protection systems

Abstract

The present invention relates to a low-thermal expansion sandwich panel structure for a metal thermal protection system. The structure comprises at least one hybrid core layer unit, which comprises four sequentially connected structural units arranged in mirror images, left and right, and top and bottom. Each structural unit comprises two outer straight wall panels with a larger thermal expansion coefficient, two inner straight wall panels, and an X-shaped wall panel with a smaller thermal expansion coefficient. The waist of the X-shaped wall panel is flanked by two first-section panels and two second-section panels, with the two first-section panels correspondingly connected to the first ends of the two inner straight wall panels, the two second-section panels correspondingly connected to the first ends of the two outer straight wall panels, and the second ends of the two inner straight wall panels correspondingly connected to the second ends of adjacent outer straight wall panels. The first sections of two adjacent structural units are connected. The outer straight wall panels of the hybrid core layer unit are connected to the panel on both sides, while the remaining portion of the hybrid core layer unit does not contact the panel. The present invention can suppress thermal deformation under high-temperature loads.

Description

Technical Field

[0001] The present invention relates to the technical field of metal thermal protection systems, in particular to a low thermal expansion sandwich panel structure for metal thermal protection systems. Background Art

[0002] Metal thermal protection systems offer significant advantages, including high reusability, low maintenance costs, strong climate adaptability, and excellent impact resistance. They are a preferred solution for large-area thermal protection of the fuselage of new, reusable, high-speed aircraft. Conventional metal thermal protection structures are primarily composite structures consisting of an outer high-temperature alloy panel, a thermal insulation structure, mechanical fastening mechanisms, and an overall sealing structure.

[0003] As the outermost component of the metal thermal protection system, the performance stability of the sandwich panel structure is extremely important to the entire metal thermal protection system. Conventional metal sandwich panel structures mostly adopt a honeycomb configuration, which is made of upper and lower panels and a middle honeycomb core brazed together. Under high temperature conditions, the metal thermal protection system has a significant temperature gradient in the thickness direction, resulting in a large difference in deformation between the hot surface and the cold surface, which makes the connectors affected by thermal expansion and thermal stress. Thermal deformation can cause interference between adjacent thermal protection systems and affect the aerodynamic characteristics of the aircraft; and high-level thermal stress can easily cause plastic deformation of the thermal protection structure and even damage it. Therefore, it is necessary to conduct research on the thermal matching problem of the metal thermal protection system and design a solution that can effectively suppress the thermal deformation of the sandwich panel structure under high temperature loads to ensure structural stability and reliability. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a low thermal expansion sandwich panel structure for a metal thermal protection system, the purpose of which is to effectively suppress the thermal deformation of the sandwich panel structure under high temperature load and improve the thermal matching problem of the metal thermal protection system.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A low thermal expansion sandwich panel structure for a metal thermal protection system, comprising at least one hybrid core layer unit, wherein two sides of the at least one hybrid core layer unit are connected to a panel;

[0007] The hybrid core layer unit includes four sequentially connected structural units, which are arranged in mirror images left and right and up and down. The structure of each structural unit is:

[0008] It comprises two outer straight wall panels, two inner straight wall panels and an X-shaped wall panel, wherein the two outer straight wall panels and the two inner straight wall panels surround the X-shaped wall panel;

[0009] The two outer straight wall plates are perpendicular to each other, and a gap is formed between the first ends of the two outer straight wall plates; the two inner straight wall plates are perpendicular to each other, and a gap is formed between the first ends of the two inner straight wall plates;

[0010] The waist of the X-shaped wall panel is provided with two V-shaped first sections and two V-shaped second sections, the two first sections are respectively connected to the first ends of the two inner straight wall panels, the two second sections are respectively connected to the first ends of the two outer straight wall panels, and the second ends of the two inner straight wall panels are respectively connected to the second ends of adjacent outer straight wall panels; the first sections of two adjacent structural units are connected to form a star-shaped cavity located in the center of the mixed core layer unit along the circumferential direction;

[0011] The X-shaped wall panels are made of material one, and the outer straight wall panels and the inner straight wall panels are made of material two, and the thermal expansion coefficient of material two is greater than the thermal expansion coefficient of material one;

[0012] Both sides of the outer straight wall plate of the hybrid core layer unit are connected to the face plate respectively, and the rest of the hybrid core layer unit is not in contact with the face plate.

[0013] Further technical solutions are:

[0014] The gap between the two sides of the inner straight wall plate and the X-shaped wall plate and the panel is 1 to 5 mm.

[0015] When two or more hybrid core layer units are provided, they are closely arranged according to a set rule; two adjacent hybrid core layer units are bonded together by the outer straight wall panels.

[0016] The two first section plates have the same length, and the two second section plates have the same length.

[0017] The lengths of the first section of the plate and the second section of the plate are the same or different.

[0018] The material of the face plate and the mixed core layer unit is a high temperature alloy.

[0019] The first material is a high-temperature alloy with a low thermal expansion coefficient, and the second material is a high-temperature alloy with a high thermal expansion coefficient.

[0020] The outer straight wall panels of two adjacent structural units are fixedly connected or integrally formed, and the inner straight wall panels of two adjacent structural units are tightly fitted or integrally formed.

[0021] The hybrid core layer unit and the panel are welded or integrally formed through additive manufacturing.

[0022] The X-shaped wall panels are welded to the outer straight wall panels, the inner straight wall panels, and the outer straight wall panels and the inner straight wall panels, or are integrally formed by additive manufacturing.

[0023] The beneficial effects of the present invention are as follows:

[0024] The present invention has low thermal expansion characteristics. The inner and outer straight wall panels of the hybrid core unit have greater thermal expansion coefficients than the X-shaped wall panels. When heated, the thermal strain of the outer and inner straight wall panels is greater than that of the X-shaped wall panel. The X-shaped wall panels are squeezed from all sides, causing them to undergo elastic tensile deformation, allowing them to rotate around their waist center axis, causing the inner and outer straight wall panels to move inward. The inward movement of the outer straight wall panels of the hybrid core unit limits the thermal deformation of the upper and lower panels outward, thereby reducing the equivalent thermal expansion coefficient of the upper and lower panels. This effectively suppresses thermal deformation under high-temperature loads.

[0025] The panel of the present invention is only connected to the outer straight wall panels around the hybrid core layer unit. Compared with the structure in which the panel is connected to all the wall panels of the hybrid core layer unit, the restrictive effect of the panel on the thermal shrinkage response of the hybrid core layer unit is greatly reduced. At the same time, the hybrid core layer unit will still act on the panel, so that the entire sandwich panel structure can fully exert its low thermal expansion characteristics.

[0026] The sandwich panel structure of this invention is constructed entirely of high-temperature alloys. Compared to ordinary metals, their superior high-temperature resistance and oxidation resistance ensure stable operation under extreme heat conditions and extend service life. Their high strength and rigidity enable them to withstand significant mechanical loads, while their low density reduces overall weight. Furthermore, the structural design is simple, making it easy to weld multiple straight panels together or to design and fabricate the entire structure, facilitating its construction for use in metal thermal protection systems.

[0027] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the panel structure with a single hybrid core layer unit according to an embodiment of the present invention.

[0029] Figure 2 for Figure 1 The schematic diagram of the structure after one side panel is hidden.

[0030] Figure 3 Schematic diagram of an exploded view of a panel structure having multiple hybrid core layer units according to an embodiment of the present invention.

[0031] Figure 4 Schematic diagram of the structure of a single hybrid core layer unit before and after thermal deformation in an embodiment of the present invention.

[0032] In the figure: 1, panel; 2, hybrid core unit; 21, outer straight wall panel; 23, inner straight wall panel; 22, X-shaped wall panel; 222, first section panel; 221, second section panel; 24, star-shaped cavity. DETAILED DESCRIPTION

[0033] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0034] like Figure 1 and Figure 2 As shown, the low thermal expansion sandwich panel structure for the metal thermal protection system of this embodiment includes at least one hybrid core layer unit 2, and a panel 1 is connected to each of the upper and lower sides of the at least one hybrid core layer unit 2;

[0035] A single hybrid core layer unit 2 includes four sequentially connected structural units, which are arranged in mirror images left and right and up and down. The structure of each structural unit is:

[0036] It includes two outer straight wall panels 21, two inner straight wall panels 23 and an X-shaped wall panel 22. The two outer straight wall panels 21 and the two inner straight wall panels 23 surround the X-shaped wall panel 22.

[0037] The two outer straight wall plates 21 are perpendicular to each other, and a gap is formed between the first ends of the two outer straight wall plates 21; the two inner straight wall plates 23 are perpendicular to each other, and a gap is formed between the first ends of the two inner straight wall plates 23;

[0038] On both sides of the waist of the X-shaped wall panel 22 are two V-shaped first section panels 222 and two V-shaped second section panels 221. The two first section panels 222 are respectively connected to the first ends of the two inner straight wall panels 23, the two second section panels 221 are respectively connected to the first ends of the two outer straight wall panels 21, and the second ends of the two inner straight wall panels 23 are respectively connected to the second ends of adjacent outer straight wall panels 21. The first section panels 222 of two adjacent structural units are connected to form a star-shaped cavity 24 located in the center of the hybrid core layer unit 2 along the circumferential direction.

[0039] The X-shaped wall plate 22 is made of material one, and the outer straight wall plate 21 and the inner straight wall plate 23 are made of material two. The thermal expansion coefficient of material two is greater than the thermal expansion coefficient of material one.

[0040] The upper and lower sides of the outer straight wall plate 21 of the hybrid core layer unit 2 are respectively connected to the upper and lower panel plates 1 , while the rest of the hybrid core layer unit 2 is not in contact with the upper and lower panel plates 1 .

[0041] As a preferred embodiment, the gaps between the upper and lower sides of the inner straight wall plate 23 and the X-shaped wall plate 22 and the panel 1 are 1 to 5 mm.

[0042] As a specific embodiment, Figure 3As shown, when two or more hybrid core layer units 2 are provided, they are closely arranged according to a predetermined pattern. In this embodiment, the hybrid core layer units 2 are arranged in an array, with adjacent hybrid core layer units 2 being bonded together by the outer straight wall panels 21. The outer straight wall panels 21 serve as the common surface between the two adjacent hybrid core layer units 2. A single panel 1 is provided on either side of the multiple hybrid core layer units 2, thereby forming the outer structure of the metal thermal protection system.

[0043] As a preferred embodiment, the two first section plates 222 have the same length, and the two second section plates 221 have the same length.

[0044] As a specific implementation, the lengths of the first section plate 222 and the second section plate 221 are the same or different.

[0045] As a specific embodiment, the material of the panel 1 is a high-temperature alloy, and the material of the mixed core layer unit 2 is a high-temperature alloy.

[0046] As a preferred embodiment, the first material is GH903 and the second material is GH2036.

[0047] As a specific embodiment, the outer straight wall panels 21 of two adjacent structural units are fixedly connected or integrally formed, and the inner straight wall panels 23 of two adjacent structural units are tightly fitted or integrally formed.

[0048] As a specific embodiment, the hybrid core layer unit 2 and the panel 1 are welded or integrally formed by additive manufacturing.

[0049] As a specific embodiment, the X-shaped wall panel 22 is welded to the outer straight wall panel 21 and the inner straight wall panel 23 , and the outer straight wall panel 21 and the inner straight wall panel 23 are welded to each other, or are integrally formed by additive manufacturing.

[0050] The sandwich panel structure of this embodiment has low thermal expansion characteristics, which are specifically reflected in the following aspects:

[0051] See also Figure 4 The solid line in the figure shows the structure before deformation, and the dotted line shows the structure after deformation. When the sandwich panel is heated, because the thermal expansion coefficient of the outer straight wall panels and inner straight wall panels made of Material 2 is greater than that of the X-shaped wall panels made of Material 1, the thermal strain of the outer straight wall panels and inner straight wall panels is greater than that of the X-shaped wall panels. The outer straight wall panels and inner straight wall panels squeeze the X-shaped wall panels from all sides, causing the X-shaped wall panels to undergo elastic tensile deformation, thereby rotating around the central axis of its waist (the junction of the two first-section panels and the two second-section panels). This causes the outer straight wall panels and inner straight wall panels on all sides to move inward. The inward movement of the outer straight wall panels of the hybrid core unit then limits the thermal deformation of the upper and lower panels in the outward direction. This makes the equivalent thermal expansion coefficient of the upper and lower panels smaller than the thermal expansion coefficient of the panels themselves, effectively suppressing the thermal deformation of the sandwich panel structure of the metal thermal protection system under high-temperature loads.

[0052] Among them, the X-shaped wall panel produces elastic tensile deformation so that it can rotate around the central axis of its waist, such as Figure 4 As shown, the two first sections and the two second sections move toward each other around the central axis of the waist, that is, after deformation, the angle between the two first sections and the second sections becomes smaller.

[0053] Because the upper and lower panels are connected to the outer straight panels and not in contact with the inner straight panels or the X-shaped panels, and preferably, the gap between the inner straight panels and the X-shaped panels and their corresponding panels is 1 to 5 mm, the rotational deformation of the X-shaped panels and the deformation of the inner straight panels will not affect the upper and lower panels, thereby ensuring uniform and stable force on the panels and better leveraging the low expansion characteristics of the panel structure.

[0054] The low-thermal expansion sandwich panel structure for a metal thermal protection system in this embodiment can be designed to achieve the desired contraction distance of the outer straight wall panels by adjusting the geometric and material parameters of the hybrid core unit and the panel as needed. By adjusting these geometric and material parameters, the contraction distance can be adjusted, thereby adjusting the thermal expansion coefficient of the panel structure to meet the needs of different application scenarios.

[0055] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will be able to modify the technical solutions described in the foregoing embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A low thermal expansion sandwich panel structure for a metal thermal protection system, characterized in that: It comprises at least one hybrid core layer unit (2), wherein two sides of the at least one hybrid core layer unit (2) are respectively connected to a panel (1); The hybrid core layer unit (2) comprises four sequentially connected structural units, the four structural units are arranged in a mirror image left and right, and up and down, and the structure of each structural unit is: It comprises two outer straight wall panels (21), two inner straight wall panels (23) and an X-shaped wall panel (22), wherein the two outer straight wall panels (21) and the two inner straight wall panels (23) surround the X-shaped wall panel (22); The two outer straight wall plates (21) are perpendicular to each other, and a gap is formed between the first ends of the two outer straight wall plates (21); the two inner straight wall plates (23) are perpendicular to each other, and a gap is formed between the first ends of the two inner straight wall plates (23); The waist of the X-shaped wall panel (22) is provided with two V-shaped first section panels (222) and two V-shaped second section panels (221) on both sides, the two first section panels (222) are respectively connected to the first ends of the two inner straight wall panels (23), the two second section panels (221) are respectively connected to the first ends of the two outer straight wall panels (21), and the second ends of the two inner straight wall panels (23) are respectively connected to the second ends of the adjacent outer straight wall panels (21); the first section panels (222) of two adjacent structural units are connected to form a star-shaped cavity (24) located at the center of the mixed core layer unit (2) along the circumferential direction; The X-shaped wall plate (22) is made of material one, and the outer straight wall plate (21) and the inner straight wall plate (23) are made of material two, and the thermal expansion coefficient of material two is greater than the thermal expansion coefficient of material one; Both sides of the outer straight wall plate (21) of the hybrid core layer unit (2) are respectively connected to the panel (1), and the remaining part of the hybrid core layer unit (2) is not in contact with the panel (1).

2. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The gap between the two sides of the inner straight wall plate (23) and the X-shaped wall plate (22) and the panel (1) is 1 to 5 mm.

3. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: When two or more hybrid core layer units (2) are provided, they are closely arranged according to a set rule; two adjacent hybrid core layer units (2) are bonded together via the outer straight wall plate (21).

4. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The two first section plates (222) have the same length, and the two second section plates (221) have the same length.

5. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The lengths of the first section plate (222) and the second section plate (221) are the same or different.

6. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The material of the face plate (1) and the mixed core layer unit (2) is a high-temperature alloy.

7. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The first material is a high-temperature alloy with a low thermal expansion coefficient, and the second material is a high-temperature alloy with a high thermal expansion coefficient.

8. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The outer straight wall panels (21) of two adjacent structural units are fixedly connected or integrally formed, and the inner straight wall panels (23) of two adjacent structural units are tightly fitted or integrally formed.

9. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The mixed core layer unit (2) and the panel (1) are welded or integrally formed through additive manufacturing.

10. The low thermal expansion sandwich panel structure for a metal thermal protection system according to claim 1, characterized in that: The X-shaped wall plate (22) is welded to the outer straight wall plate (21) and the inner straight wall plate (23), and the outer straight wall plate (21) and the inner straight wall plate (23) are welded to each other, or are integrally formed by additive manufacturing.

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