Recoverable structure for impact deformation and aircraft
By using shape memory alloy skin and reinforced structure in the easily impacted parts of the aircraft, the problem of local deformation and high maintenance costs caused by impact during high-speed movements is solved, and the recovery of impact deformation and the simplicity of maintenance is achieved.
Patent Information
- Application Number
- CN202311619838.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-29
- Publication Date
- 2025-05-30
AI Technical Summary
Aircraft are easily impacted by external objects during high-speed movement, resulting in local deformation and high maintenance costs.
A skin structure made of shape memory alloy is equipped with a reinforced structure on the inside, and the skin is restored to its original shape by heating, simplifying the maintenance process.
It effectively reduces the degree of impact deformation, simplifies the maintenance process, and reduces time and costs.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of aircraft structural design, and more particularly, to a recoverable structure for impact deformation and an aircraft. Background Art
[0002] Vehicles such as aircraft, trains, and cars may be damaged by foreign objects during high-speed movement. For an aircraft, the most vulnerable parts to impact are the head, wings, and the inlet lip of the engine nacelle. The most common foreign object is a bird, and such an impact is also called a "bird strike". Figure 1 And Figure 2 respectively show schematic diagrams of the deformation of the nose and the inlet lip of the nacelle due to a bird strike.
[0003] To cope with bird strikes, in traditional aircraft design, the positions vulnerable to impact are generally structurally strengthened or replaced with stronger materials, so that even if an impact occurs, the damage to the local or overall aircraft is reduced to a level that does not affect flight safety. However, traditional structural strengthening or material improvement has led to an increase in the weight and cost of the aircraft. In addition, even if a bird strike only causes damage to the appearance of the aircraft (such as the skin), the damaged components need to be repaired or replaced, resulting in high economic and time costs for maintenance. Summary of the Invention
[0004] The present disclosure is provided to introduce some concepts in a simplified form that will be further described in the following detailed embodiments. The present disclosure is not intended to identify the key features or essential features of the claimed subject matter, nor is it intended to be used to help determine the scope of the claimed subject matter.
[0005] One of the objectives of the present disclosure is to address the problems of depression deformation, high maintenance cost, and long time caused by bird strikes on parts such as the aircraft nose, wings, and engine nacelle lip. By using the property of shape memory alloy to deform and recover at high temperature, a skin structure is prepared, and a stiffening structure is arranged inside the skin structure to spread the impact load and reduce the degree of impact deformation. In the case where typical impacts such as bird strikes only cause plastic deformation, it can be restored to its original shape by heating, such as spraying hot water / hot oil, with simple, time-saving, and low-cost maintenance.
[0006] According to one aspect of the present disclosure, a recoverable structure for impact deformation is provided, including:
[0007] A skin made of shape memory alloy; and
[0008] A stiffening structure arranged inside the skin for spreading the impact received by the skin.
[0009] According to a further embodiment of the present invention, the stiffening structure adopts a uniformly distributed grid structure.
[0010] According to a further embodiment of the present invention, the grid structure is a diamond grid structure, a hexahedron grid structure or a triangular grid.
[0011] According to a further embodiment of the present invention, the cross-sections of the grid structure are equal.
[0012] According to a further embodiment of the present invention, the cross-section is a semi-cylindrical cross-sectional shape, a rectangular cross-sectional shape or a triangular cross-sectional shape.
[0013] According to a further embodiment of the present invention, the shape memory alloy has a one-way memory effect.
[0014] According to a further embodiment of the present invention, the skin is formed through the following process:
[0015] The parent phase of the shape memory alloy is made into a desired skin shape at a high temperature;
[0016] The parent phase is cooled to cause martensitic transformation, and the martensite is deformed arbitrarily;
[0017] It is reheated to above the phase transformation point to completely eliminate the martensite, and the material restores the parent phase shape; and
[0018] It is cooled again and the parent phase shape is maintained.
[0019] According to a further embodiment of the present invention, after the skin is deformed by impact, it is restored to the shape before deformation by heating to the phase transformation temperature of its shape memory alloy.
[0020] According to a further embodiment of the present invention, the heating method includes spraying hot water or hot oil.
[0021] According to another aspect of the present invention, there is provided an aircraft including a recoverable structure as described in the present invention.
[0022] According to a further embodiment of the present invention, the recoverable structure is applied to one or more of the following positions in the aircraft:
[0023] The nose skin of the aircraft;
[0024] The wing skin of the aircraft; or
[0025] The outer shell of the nacelle inlet lip of the aircraft.
[0026] By reading the following detailed description and referring to the associated drawings, these and other features and advantages will become apparent. It should be understood that the foregoing general description and the following detailed description are illustrative only and do not limit the various aspects claimed. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to understand the manner in which the above-described features of the present disclosure are used in detail, the above briefly summarized content may be described in more specific detail with reference to the various embodiments, some aspects of which are shown in the accompanying drawings. It should be noted, however, that the drawings only show some typical aspects of the present disclosure and should not be considered to limit its scope, as the description may allow other equally effective aspects.
[0028] Figure 1 A schematic diagram of the impact deformation of the aircraft nose is shown.
[0029] Figure 2 A schematic diagram of the impact deformation of the inlet lip of the engine nacelle is shown.
[0030] Figure 3 A partial cross-sectional view of a recoverable structure according to an embodiment of the present invention is shown.
[0031] Figure 4 A schematic diagram of a stiffened structure according to an embodiment of the present invention is shown.
[0032] Figure 5 A schematic diagram of the deformation recovery principle of a recoverable structure according to an embodiment of the present invention is shown.
[0033] Among them, the above-mentioned drawings include the following reference numerals:
[0034] 1 Skin
[0035] 2 Stiffened structure
[0036] 3 Reinforcing rib DETAILED DESCRIPTION OF THE EMBODIMENTS
[0037] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.
[0038] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way restricts the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.
[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0040] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and values set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not require further discussion in subsequent drawings.
[0041] In the description of the present application, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Without contrary instructions, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present application; the orientation words "inner, outer" refer to the inside and outside relative to the contour of each component itself.
[0042] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper", etc. may be used herein to describe the spatial positional relationship of a device or feature shown in the figures with respect to other devices or features. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures will then be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both orientations of "above" and "below". The device may also be positioned in other different ways, rotated 90 degrees or in other orientations, and the corresponding explanations are made for the spatial relative descriptions used herein.
[0043] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is merely for the convenience of distinguishing the corresponding components. Without further statement, the above terms have no special meaning, and thus should not be construed as limiting the scope of protection of the present application. In addition, although the terms used in the present application are selected from well-known and commonly used terms, some of the terms mentioned in the specification of the present application may be selected by the applicant according to his or her judgment, and their detailed meanings are described in the relevant parts of the present description. In addition, it is required to understand the present application not only through the actual terms used, but also through the meaning implied by each term.
[0044] Figure 3 A partial sectional view of a recoverable structure against impact deformation according to an embodiment of the present invention is shown. As Figure 3 shown, the recoverable structure includes a skin 1 and a stiffening structure 2 disposed inside the skin 1.
[0045] The skin 1 is made of a shape memory alloy. Shape Memory Alloys (SMA) is a new type of functional material composed of two or more metal elements that can undergo phase transformation under the action of temperature and stress. It has unique shape memory effect, phase transformation pseudoelasticity and other characteristics through thermoelasticity and martensitic phase transformation and its reverse transformation, and is widely used in the fields of aerospace, biomedicine, mechatronics, automotive industry, construction engineering, etc. The physical and mechanical properties of shape memory alloys essentially depend on temperature. The phase transformation temperatures of commonly used shape memory alloys are generally not high, generally in the temperature range of -50 to 150 °C.
[0046] Shape memory alloys are mainly classified into three categories according to alloy types: nickel-titanium-based shape memory alloys (Ni-Ti SMA), copper-based shape memory alloys (Cu SMA), and iron-based shape memory alloys (Fe SMA). Among them, nickel-titanium-based shape memory alloys include memory alloys with high practical value such as Ni-Ti-Cu, Ni-Ti-Co, Ni-Ti-Fe, Ni-Ti-Nb, etc. Copper-based shape memory alloys mainly include types such as Cu-Zn, Cu-Zn-Al, Cu-Zn-Sn, Cu-Zn-Si, Cu-Zn-Ga, Cu-Sn, etc. Iron-based shape memory alloys mainly include types such as Fe-Pt, Fe-Mn-Si, Fe-Ni-Co-Ti, Fe-Mn-Al-Ni, Fe-C-Mn-Si-Cr-Ni, etc.
[0047] The low-temperature phase of shape memory alloy is martensite, which is soft and easy to deform, and the high-temperature phase is austenite, which is relatively hard. During the cooling process, the parent phase will transform into twinned martensite, which is easily deformed into a specific shape under the action of external force. When heated, the deformed martensite will return to the original austenite state, and this phenomenon is the macroscopic shape memory phenomenon.
[0048] The deformation and recovery modes of shape memory alloys are generally divided into one-way shape memory effect, two-way shape memory effect, and full-range shape memory effect. According to an embodiment of the present invention, the shape memory alloy of the skin 1 has a deformation and recovery mode of one-way memory effect. In one example, the skin 1 can be formed through the following process:
[0049] 1. The parent phase of the shape memory alloy is made into the desired skin shape at high temperature. The specific shape can depend on the position where the skin 1 is installed, including but not limited to the nose skin of the aircraft, the wing skin, the shell of the nacelle inlet lip, or any other thin shell or thin wall location;
[0050] 2. Cool the parent phase or apply stress to cause martensite transformation, and deform the martensite arbitrarily;
[0051] 3. Reheat to above the phase transition point to make the martensite completely disappear. At this time, the material can recover the parent phase shape (i.e., the desired skin shape initially processed);
[0052] 4. Re-cool, and at this time the material can maintain the parent phase shape, and the deformation at low temperature will be eliminated.
[0053] The stiffening structure 2 is arranged inside the skin 1 to diffuse the impact that the skin 1 may receive. In an ideal situation, it can make the skin 1 only undergo plastic deformation and not material failure when receiving typical impacts (such as bird strikes, especially the strikes of small birds and medium-sized birds with the highest occurrence frequency). Figure 3In the example, the skin 1 is the outer shell of the inlet lip of the engine nacelle. Therefore, in the local sectional view along the lip, the skin 1 is roughly circular, and the stiffening structure 2 is arranged inside the skin 1.
[0054] The stiffening structure 2 is also called the reinforcing rib structure. According to an example of the present invention, the stiffening structure 2 can adopt a grid structure, that is, each reinforcing rib 3 forms a grid. Figure 4 The schematic diagram of the stiffening structure according to an embodiment of the present invention is shown. As Figure 4 shown in, the grid structure can be a diamond structure. Alternatively, the grid structure can also be a hexahedron grid structure, a triangular grid or other grid structures. According to an example of the present invention, the grid structure of the stiffening structure 2 is uniformly distributed inside the entire skin 1, which is beneficial to ensuring that the force is uniform in any area when impacted by foreign objects. As Figure 3 shown in, depending on the shape of the reinforcing rib, the cross-section of the reinforcing rib can be semi-circular, or it can also be rectangular, triangular or other suitable shapes. In one example, all the ribs have the same cross-section, which is beneficial to ensuring the continuity and uniformity of the transmission of impact loads.
[0055] The various parameters of the above-mentioned stiffening structure 2, including the rib distribution structure, grid density, cross-section shape, etc., are only exemplary. These parameters or other parameters of the stiffening structure 2 can be specifically determined according to the actual protected area, the type of the main protected impact situation and the impact load range, etc., with the aim of ensuring that the skin can spread the local transient impact load to a larger range when suffering the envisaged impact, so that even if the shape memory alloy of the skin at the impacted part deforms, it is only plastic deformation and no material failure will occur.
[0056] When the skin only undergoes plastic deformation, it will be much simpler to repair the deformed skin. Figure 5 The schematic diagram of the deformation recovery principle of the recoverable structure according to an embodiment of the present invention is shown. As Figure 5 shown in, the process of the recoverable structure from processing and forming to being impacted and deformed to recovering its shape is shown from left to right in sequence. In the first stage on the far left, it corresponds to step 3 in the forming process of the skin described above. After reheating, the skin returns to the parent phase shape (and the martensite is completely eliminated). Subsequently, in the second stage, the structure is cooled to maintain its parent phase shape. The cooled component can then be used as a component for assembly and use. In the third stage, the structure is deformed due to impact. Subsequently, in the fourth stage, the component is reheated again. When heated above the phase transition temperature of the shape memory alloy, the material will gradually return to the memorized parent phase shape. Finally, in the fifth stage, the entire structure completely returns to the form before deformation.
[0057] It is worth mentioning that in the fourth stage mentioned above, that is, the process of heating and modifying the deformation, it can be restored by spraying hot water / hot oil. In other words, when the degree of deformation caused by the impact is within the expected range, it is generally not necessary to disassemble the body, which will significantly save time and cost compared with the traditional maintenance methods. Therefore, when selecting the specific material type of the shape memory alloy, this factor can be taken into account, and while meeting the strength and safety requirements, select a material whose phase change temperature allows the shape to be restored only by spraying hot water / hot oil, for example.
[0058] The foregoing has described examples of aspects of the claimed subject matter. Of course, it is not possible to describe every conceivable combination of components or methods for the purpose of depicting the claimed subject matter, but one of ordinary skill in the art should recognize that many further combinations and permutations of the claimed subject matter are possible. Thus, the disclosed subject matter is intended to cover all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.
Claims
1. A recoverable structure for impact deformation, characterized in that, comprising: a skin, the skin being made of a shape memory alloy; and a stiffening structure disposed inside the skin for diffusing the impact received by the skin.
2. The recoverable structure according to claim 1, characterized in that, the stiffening structure adopts a uniformly distributed grid structure.
3. The recoverable structure according to claim 2, characterized in that, the grid structure is a diamond grid structure, a hexahedron grid structure or a triangular grid.
4. The recoverable structure according to claim 2, characterized in that, the cross-sections of the grid structure are equal.
5. The recoverable structure according to claim 4, characterized in that, the cross-section is in the shape of a semi-cylindrical section, a rectangular section or a triangular section.
6. The recoverable structure according to claim 1, characterized in that, the shape memory alloy has a one-way memory effect.
7. The recoverable structure according to claim 6, characterized in that, the skin is formed through the following process: forming the parent phase of the shape memory alloy into a desired skin shape at a high temperature; cooling the parent phase to cause martensite transformation and arbitrarily deforming the martensite; reheating to above the phase transformation point to completely disappear the martensite and the material returns to the parent phase shape; and re-cooling and maintaining the parent phase shape.
8. The recoverable structure according to claim 7, characterized in that, after being impacted and deformed, the skin is restored to the shape before deformation by heating to the phase transformation temperature of its shape memory alloy.
9. The recoverable structure according to claim 8, characterized in that, the heating method includes spraying hot water or hot oil.
10. An aircraft comprising the recoverable structure according to any one of claims 1-9.
11. The aircraft according to claim 10, characterized in that, the recoverable structure is applied to one or more of the following positions in the aircraft: the nose skin of the aircraft; the wing skin of the aircraft; or the outer shell of the nacelle inlet lip of the aircraft.