A flexible metal composite skin structure with controllable local out-of-plane deformation

Abstract

The application discloses a flexible metal composite skin structure capable of regulating local out-of-plane deformation and belongs to the technical field of metal skin structures. The application introduces a paper-cut structure on the surface of a metal skin, regulates mechanical response by changing characteristic parameters such as a paper-cut pattern and a metal skin thickness, so that the structure has high ductility and small plastic deformation characteristics, and the structure can recover to original deformation after the expansion of a protrusion of a driving device, thereby ensuring the continuity of a wing aerodynamic shape. The application meets the basic requirements of application to a flexible skin of a deformation wing, provides a feasible selection for the fusion of a gasbag anti-icing mechanism and a deformation wing, and is expected to be widely applied in the fields of aircraft deicing, spacecraft deicing and deformation wings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal skin structure, and in particular to a flexible metal composite skin structure capable of adjusting and controlling local out-of-plane deformation. BACKGROUND

[0002] In the field of aerospace, the deicing system is related to the flight safety, aerodynamic performance and service life of the aircraft, and has a very important influence on the normal work of the aircraft, and is an indispensable part of modern aircraft.

[0003] Among the various deicing technologies, the airbag deicing technology is one of the most widely used mechanical deicing technologies.

[0004] However, the airbag deicing device also has some shortcomings. Since the airbag device for deicing is installed on the surface of the aircraft wing, when not inflated, the deicing airbag is difficult to completely conform to the smooth aerodynamic shape of the wing even if it is tightly attached to the surface of the wing, which will cause the flatness of the wing surface to decrease and change the original streamlined shape of the wing. Studies have shown that the airbag on the outer side of the wing has a significant impact on the aerodynamic performance of the aircraft, with a maximum lift coefficient loss of more than 60%, which needs to be improved. SUMMARY

[0005] The purpose of the present application is to solve the problems existing in the prior art, to combine the deformed wing technology with the wing deicing technology, to integrate the airbag into the wing and hide it inside the wing, so as to ensure the smooth aerodynamic shape of the wing and improve the aerodynamic performance of the aircraft to a certain extent, that is, to propose a flexible metal composite skin structure capable of adjusting and controlling local out-of-plane deformation.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A flexible metal composite skin structure capable of adjusting and controlling local out-of-plane deformation, comprising a locally deformed metal matrix workpiece, a driving device for driving the local deformation of the metal matrix workpiece, and a surface continuous material wrapped outside the locally deformed area of the metal matrix workpiece.

[0008] The metal matrix workpiece is a thin workpiece with a thickness t, t is 0.04-0.10mm;

[0009] The surface of the metal matrix workpiece is divided into an outer fixed area, an intermediate paper cutting area and a central raised area in sequence, the driving device is arranged on the inner side of the central raised area, for driving the central raised area to protrude in the vertical direction out of the plane, and at the same time driving the intermediate paper cutting area to produce gradient deformation, and the surface continuous material is covered outside the intermediate paper cutting area and the central raised area to improve the toughness of the two locally deformed areas.

[0010] Preferably, the material of the metal matrix workpiece includes but is not limited to 304 stainless steel metal material.

[0011] Preferably, the driving device includes an air bag, a mechanical skeleton or an actuator, which generates out-of-plane deformation and then removes ice on the surface.

[0012] Preferably, the material of the surface continuous material includes but is not limited to rubber material.

[0013] Preferably, the edge part of the peripheral fixed region is provided with a mounting member, which includes uniformly distributed through holes and screws or rivets fixed therewith, or the mounting member adopts some seals to cover and fix the peripheral fixed region, so as to realize the installation of the skin structure.

[0014] Preferably, the intermediate paper-cutting region includes a reserved area and a paper-cutting gap belt, forming a hollow paper-cutting structure, so as to form a central raised area and isolate it from the peripheral fixed region, and the driving device is arranged in advance before installation, and the edge of the surface continuous material is installed on the surface of the peripheral fixed region through the adhesive after installation, that is, the paper-cutting principle is adopted to realize the out-of-plane deformation perpendicular to the plane direction of the skin.

[0015] A further optimized scheme is that the paper-cutting gap belt is an arc-shaped gap with a width of d, wherein 5t≤d≤25t, t is the thickness of the metal matrix workpiece, and the ring width must be much larger than the material thickness to ensure that the intermediate paper-cutting region has sufficient length for bending deformation. If the width is too small, it will cause local stiffness to be too large and difficult to manufacture. If the ring width is too large, it will cause the single ring belt to be too "soft", which has poor stability under in-plane load, and may cause the overall deformation mode of the structure to be out of control.

[0016] 3-6 of the paper-cutting gap belts are arranged outside the central raised area in a ring shape, and form a ring belt with equal intervals between the connecting section and the cutting section, and the ratio of the length of the cutting section to the total length of the ring belt, that is, the gap length ratio, is e, wherein 0.65≤e≤0.88. Within this range, the structure can achieve the best balance between large deformation and ensuring the integrity and fatigue life of the structure. e=0.86 is a verified value that can produce excellent deformation effect. If the gap ratio is too small, the flexibility of the structure is insufficient, which is more close to a rigid ring with a narrow gap, and it is difficult to achieve large deformation. If the gap ratio is too large, the connecting bridge becomes very short and small, and its strength is insufficient to withstand cyclic load, which is prone to fracture during deformation, resulting in structural failure.

[0017] The plurality of annular strips are equidistantly distributed outside the central convex region, and the gap between adjacent annular strips is c, wherein 2t≤c≤10t, t is the thickness of the metal matrix workpiece, and the ring spacing in the range can ensure smooth transition of deformation to form a continuous and controllable convex curved surface, for example, the convex height requirement of the central convex region is 5mm, so as to realize sufficient deformation to remove ice, and a corresponding number n of annular strips may be arranged according to the gap c to meet the strength requirement of the deformation amount, and numerical simulation test is carried out on the deformation condition, such as Figures 3-5 If the ring spacing is too small, the material area between adjacent rings will be too narrow, becoming a weak link of stress concentration, and being prone to fatigue failure, and the precision requirement of the precision manufacturing process such as laser cutting is extremely high; if the ring spacing is too large, the deformation area will be sparse, the convex shape will be discontinuous, and the smooth aerodynamic surface will be difficult to form. Deformation will also be excessively concentrated on a few rings.

[0018] Further, the paper-cutting method: the cutting gap strip is cut by an arc-shaped cutter with a width of d.

[0019] Compared with the prior art, the beneficial effects of the present application are:

[0020] 1. The present application combines the paper-cutting pattern with the traditional flexible material skin structure, realizes out-of-plane deformation of the metal skin in the vertical plane direction through plastic deformation of the paper-cutting area, changes the workpiece thickness, and designs the paper-cutting pattern parameters and the workpiece thickness to meet the corresponding mechanical response parameters, so as to realize a stable and repeatable deformation mode.

[0021] 2. The present application can accurately customize the force-displacement response curve and the final deformation shape of the structure according to product requirements by adjusting the geometric parameters (thickness t, ring spacing c, ring width d, gap ratio e, etc.) of the paper-cutting pattern.

[0022] For example, the thickness t is the main control factor of stiffness, the gap ratio e directly determines the length of the connecting bridge, and the ring width d and the spacing c jointly determine the deformation cooperativity and gradient. A suitable d / c ratio can ensure that the deformation is smoothly transmitted from the inside to the outside to form an ideal spherical crown convex, rather than a stepped or conical distortion. These geometric parameters directly control the equivalent stiffness and deformation instability mode of the structure, and the parameterized design method of the present application changes the trial-and-error design into a predictable and optimized scientific design. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A plane schematic view of a controllable local out-of-plane deformation flexible metal composite skin structure before local deformation is provided for the present application;

[0024] Figure 2A three-dimensional schematic view of a flexible metal composite skin structure capable of adjusting local out-of-plane deformation according to the present application after local deformation;

[0025] Figure 3 A numerical simulation schematic diagram of the deformation of a flexible metal composite skin structure capable of adjusting local out-of-plane deformation according to the present application obtained in Example 1;

[0026] Figure 4 A numerical simulation schematic diagram of the deformation of a flexible metal composite skin structure capable of adjusting local out-of-plane deformation according to the present application obtained in Example 2;

[0027] Figure 5 A numerical simulation schematic diagram of the deformation of a flexible metal composite skin structure capable of adjusting local out-of-plane deformation according to the present application obtained in Comparative Example 1;

[0028] Figure 6 A force-displacement response curve diagram of a flexible metal composite skin structure capable of adjusting local out-of-plane deformation according to the present application under different thicknesses t;

[0029] Figure 7 A force-displacement response curve diagram of a flexible metal composite skin structure capable of adjusting local out-of-plane deformation according to the present application obtained under different paper cutting patterns.

[0030] In the figure: 1: peripheral fixed area; 2: middle paper cutting area; 201: reserved area; 202: paper cutting gap; 3: center protruding area. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described in detail below in combination with the prior known technology. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments.

[0032] Basic scheme:

[0033] A flexible metal composite skin structure capable of adjusting local out-of-plane deformation, comprising a locally deformed metal matrix workpiece, a driving device for driving the local deformation of the metal matrix workpiece, and a surface continuous material wrapped outside the local deformation area of the metal matrix workpiece;

[0034] The metal matrix workpiece is a thin workpiece with a thickness of t, t is 0.04-0.10mm;

[0035] The surface of the metal matrix workpiece is divided into an outer fixed region 1, an intermediate paper cutting region 2, and a central protruding region 3 in sequence. A driving device is arranged inside the central protruding region 3, which is used to drive the central protruding region 3 to protrude in the out-of-plane vertical direction, and simultaneously drive the intermediate paper cutting region 2 to produce gradient deformation. A surface continuous material is covered outside the intermediate paper cutting region 2 and the central protruding region 3 to improve the toughness of the two local deformation regions.

[0036] The material of the metal matrix workpiece includes but is not limited to 304 stainless steel metal material.

[0037] The driving device includes an air bag, a mechanical skeleton, or an actuator, which produces out-of-plane deformation by driving, and then performs surface deicing.

[0038] The material of the surface continuous material includes but is not limited to rubber material.

[0039] The edge part of the outer fixed region 1 is provided with a mounting part, which includes uniformly distributed through holes and screws or rivets fixed therewith, or the mounting part adopts some seals to cover and fix the outer fixed region 1, so as to realize the installation of the skin structure.

[0040] The intermediate paper cutting region 2 includes a reserved area 201 and a cutting gap belt 202, forming a hollow paper cutting structure, so as to form the central protruding region 3 and isolate it from the outer fixed region 1, that is, the paper cutting principle is adopted to realize the out-of-plane deformation in the vertical skin plane direction.

[0041] Embodiment 1: According to the above basic scheme, the following parameters are further set:

[0042] The metal matrix workpiece is 304 stainless steel metal material with a thickness of t=0.04mm;

[0043] The driving device is an actuator;

[0044] The surface continuous material is selected from nitrile rubber;

[0045] The structure is set as follows:

[0046] The mounting part of the edge part of the outer fixed region 1 is a riveting structure matched with rivets and through holes; the driving device is arranged before installation, and the edge of the surface continuous material is installed on the surface of the outer fixed region 1 after installation through a metal adhesive;

[0047] The cutting gap belt 202 is an arc-shaped gap with a width of d=1mm (25t), and four cutting gap belts 202 are annularly distributed outside the central protruding region 3, and form an annular belt with equal intervals between the connecting sections and the cutting sections. The ratio of the length of the cutting section to the total length of the annular belt, that is, the length ratio of the gap, is e=0.86 (that is, the length of the gap accounts for about 6 / 7 of the total length).

[0048] 4 annular bands are equidistantly distributed outside the central raised area 3, the gap between adjacent annular bands is c = 0.4 mm (10t), the raised height requirement of the central raised area 3 is 5 mm. The deformation analysis is as shown in Figure 3 .

[0049] Example 2: On the basis of Example 1, the parameters are modified as follows:

[0050] t = 0.07 mm, d = 1.05 mm (15t), c = 0.35 mm (5t), and the rest are the same as Example 1. The deformation analysis is as shown in Figure 4 .

[0051] Comparative Example 1: On the basis of Example 1, the parameters are modified as follows:

[0052] t = 0.10 mm, d = 0.5 mm (5t), c = 0.20 mm (2t), and the rest are the same as Example 1. The deformation analysis is as shown in Figure 5 .

[0053] Comparative Example 2: On the basis of Example 2, the parameters are modified as follows: e = 0.9 (i.e. the gap length is about 9 / 10 of the total length).

[0054] Comparative Example 3: On the basis of Example 1, the parameters are modified as follows:

[0055] e = 0.58, and the rest are the same as Example 2.

[0056] Example 3: On the basis of Example 2, the parameters are modified as follows:

[0057] t = 0.07 mm, d = 0.35 mm (5t), c = 0.14 mm (2t), e = 0.65, and the rest are the same as Example 1.

[0058] Example 4: On the basis of Example 1, the parameters are modified as follows:

[0059] e = 0.88, and the rest are the same as Example 2.

[0060] Comparative Example 4: On the basis of Example 1, the parameters are modified as follows:

[0061] d = 3.5 mm (50t), and the rest are the same as Example 2.

[0062] Comparative Example 5: On the basis of Example 1, the parameters are modified as follows:

[0063] c = 1.4 mm (20t), and the rest are the same as Example 2.

[0064] The data of Examples 1-4 and Comparative Examples 1-5 are summarized, and combined with Figures 3-7, the following data are obtained as shown in Table 1:

[0065] Table 1. Influence of structural parameters on the performance of the skin structure

[0066]

[0067] According to the above analysis, the following design rules can be summarized:

[0068] 1. Comparative Examples 1-2 and Comparative Example 1 are compared, and reference is made to Figure 6 , which shows that the thickness (t) is a determining factor for stiffness, and the bending stiffness of the structure is proportional to t 3 . Therefore, a slight increase in t will cause a sharp increase in stiffness; under the premise of meeting the bearing requirements, a smaller t should be preferred to achieve low actuating force and large deformation.

[0069] and reference is made to Figures 3-5 , the slope of the force-displacement curve of the central raised area 3 gradually increases with the increase of the thickness, which is related to the shape of the paper cutting pattern. At the beginning of deformation, the outer ring cell unit will preferentially deform due to its longer gap length in the single cell, requiring less force for deformation. After a certain amount of deformation, the load reaches the critical buckling load of the inner ring gap, and the inner ring gap begins to buckle and deform, resulting in an increase in the slope of the curve. This phenomenon is beneficial to maintaining the continuity of the surface. This will provide a reference for structures with good deformation characteristics.

[0070] 2. Comparative Example 2 and Comparative Examples 2-3 are compared, and reference is made to Figure 7 , which shows that the gap length ratio e is an important factor for the balance of rigidity and flexibility, and e directly determines the length of the connecting bridge. The e of Comparative Example 3 is too low, the connecting bridge is too long, causing the stiffness to be too large, and the e of Comparative Example 2 is too high, the connecting bridge is short, which may cause stress concentration, short fatigue life, and unstable deformation. There is a golden interval (about 0.65~0.88) for e, within which the structure can simultaneously obtain good deformation capacity and durability. Example 4 significantly improves the performance by fine-tuning e from 0.9 to 0.88, truly embodying this principle.

[0071] 3. Comparative Example 2 and Comparative Examples 1, 4-5 are compared, which shows that the ring width (d) and the ring spacing (c) jointly determine the deformation gradient:

[0072] d affects local flexibility: the d of Comparative Example 1 is too small, and the cell cannot fully expand; the d of Comparative Example 4 is too large, and the ring belt itself is unstable.

[0073] c affects deformation coordination: the c of Comparative Example 1 is too small, and the deformation is not coordinated, showing a stepped shape; the c of Comparative Example 5 is too large, and the deformation area is too small, showing a conical shape.

[0074] Therefore, d and c need to match in proportion to t. Preferably, d is between 5t~25t, and c is between 2t~10t, which can ensure that the deformation is the result of the coordinated flexure of multiple annular bands, thereby forming a smooth transition surface. Example 3 achieves acceptable performance on the basis of the failure of Comparative Example 1 by parameter rebalancing, which is exactly the use of this proportional relationship.

[0075] 4. Conclusion:

[0076] Through the above systematic example and comparative example analysis, it is fully proved that the various geometric parameters (t, d, c, e) in the application are not isolated, but are mutually coupled and jointly determine the final performance of the skin structure. The successful design is to find a set of optimal balanced solution within the limit range of the above parameters for the target application (such as low driving force, high smoothness).

[0077] The above is only the preferred specific embodiment of the application, but the protection scope of the application is not limited to this. Any person skilled in the art, within the technical range disclosed by the application, according to the technical scheme and the inventive concept of the application, makes equivalent replacement or change, which should be covered within the protection scope of the application.

Claims

1. A flexible metal composite skin structure with controllable local out-of-plane deformation, characterized in that, A metal matrix workpiece including a local deformation, a driving device for driving the metal matrix workpiece to locally deform, and a surface continuous material wrapped outside the locally deformed area of the metal matrix workpiece; The metal matrix workpiece is a thin workpiece with a thickness t, and t is 0.04-0.10 mm; The surface of the metal matrix workpiece is divided into an outer peripheral fixed area (1), an intermediate paper cutting area (2), and a central protruding area (3) in sequence, and the driving device is arranged inside the central protruding area (3); The intermediate paper cutting area (2) includes a reserved area (201) and a cutting gap belt (202); The cutting gap belt (202) is an arc-shaped gap with a width d, and 5t≤d≤25t, t being the thickness of the metal matrix workpiece; 3-6 cutting gap belts (202) are annularly distributed outside the central protruding area (3) and form annular belts with equal distances between the connecting sections and the cutting sections, and the ratio of the length of the cutting section to the total length of the annular belt, i.e. the length ratio of the gap, is e, and 0.65≤e≤0.88; A plurality of annular belts are equally distributed outside the central protruding area (3), and the gap between adjacent annular belts is c, and 2t≤c≤10t, t being the thickness of the metal matrix workpiece.

2. The compliant, locally anisotropic, flexible metal composite skin structure of claim 1, wherein, The material of the metal matrix workpiece includes but is not limited to 304 stainless steel metal material.

3. The compliant, locally anisotropic, flexible metal composite skin structure of claim 1, wherein, The driving device includes an air bag, a mechanical skeleton, or an actuator.

4. The compliant, locally anisotropic, flexible metal composite skin structure of claim 1, wherein, The material of the surface continuous material includes but is not limited to rubber material.

5. The compliant, locally anisotropic flexible composite skin structure of claim 1, wherein, The edge part of the outer peripheral fixed area (1) is provided with a mounting part, and the mounting part includes uniformly distributed through holes and screws or rivets fixed therewith.

6. The compliant, locally anisotropic flexible composite skin structure of claim 1, wherein, The cutting gap belt (202) is cut by an arc-shaped cutter with a width d.

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