Composite T-shaped stringer

Abstract

The utility model provides a composite material T-shaped stringer which comprises a left L-shaped layer plate, a right L-shaped layer plate and a bottom layer plate arranged at the bottom of the left L-shaped layer plate and the bottom of the right L-shaped layer plate, the left L-shaped layer plate and the right L-shaped layer plate are symmetrically arranged relative to the longitudinal center face of the composite material T-shaped stringer, and each of the left L-shaped layer plate and the right L-shaped layer plate comprises a plurality of prepreg laying layers. The left L-shaped laminate and the right L-shaped laminate are respectively provided with edge structures which are positioned at two ends of the composite T-shaped stringer along the width direction of the composite T-shaped stringer, and a plurality of prepreg paving layers in the edge structures are constructed to coat the bottom laminate layer by layer from inside to outside so as to form a wedge-shaped oblique angle structure of which the edges are coated layer by layer; and the tail parts of the plurality of prepreg paving layers in the edge structure are in contact with the bottom laminate. The wedge-shaped oblique angle structure wrapping the edge of the bottom of the T-shaped stringer layer by layer can effectively avoid the skin wrinkling problem of the stiffened wall plate prepared by adopting a dry stringer-wet skin co-bonding forming process, and can also avoid the risk of layering of the edge of the bottom of the stringer.

Description

Technical Field

[0001] This utility model relates to the field of composite material parts, and in particular to a composite material T-shaped stringer. Background Technology

[0002] Composite material T-stiffened structures are widely used in the design of main load-bearing components of aircraft, such as wing panels, stabilizer panels, and beam web columns, due to their excellent bending and shear resistance and good load-bearing capacity. Figure 1 As shown, T-shaped parts are typically composed of a left L-shaped layer 1', a right L-shaped layer 2', a bottom layer 3', and a twist strip 4' in structural design. The existing T-shaped stringer bottom edge ply boundary is a straight, flush, and right-angled form.

[0003] according to Figure 1 When the T-shaped part prepared with the bottom edge structure shown is co-bonded and cured with the wet skin, the auxiliary materials such as the vacuum bag sealing breathable felt at the bottom edge of the stringer and the corner of the skin are difficult to be placed completely in accordance with the shape. As a result, fiber wrinkles easily appear on the skin near the bottom edge of the stringer, which does not meet the acceptance requirements.

[0004] Therefore, there is a need to provide a composite material T-shaped stringer to at least partially solve the above problems. Utility Model Content

[0005] The composite material T-shaped stringer proposed in this invention can effectively avoid the problem of skin wrinkling in stiffened wall panels prepared using the "dry stringer-wet skin" co-bonding molding process. The composite material T-shaped stringer includes: a left L-shaped layer, a right L-shaped layer, and a bottom layer disposed at the bottom of the left and right L-shaped layers. The left and right L-shaped layers are symmetrically arranged with respect to the longitudinal center plane of the composite material T-shaped stringer, and both the left and right L-shaped layers include multiple layers of prepreg.

[0006] The left L-shaped layer and the right L-shaped layer each have edge structures located at both ends of the composite material T-shaped stringer along the width direction of the composite material T-shaped stringer. The multi-layer prepreg layup in the edge structure is configured to wrap around the bottom layer from the inside out to form a wedge-shaped oblique angle structure with the edge layer by layer, and the ends of the multi-layer prepreg layup in the edge structure are in contact with the bottom layer.

[0007] Preferably, the outer side of the edge structure is inclined relative to the bottom layer.

[0008] Preferably, the multilayer prepreg plies of the left L-shaped and right L-shaped plies located in the edge structure are bent relative to the flat multilayer prepreg plies located in the bottom remainder in a direction toward the bottom plies.

[0009] Preferably, the outer side of the edge structure has an inclination angle a of 30°-35° with respect to the bottom panel.

[0010] Preferably, the outer side of the edge structure has an inclination angle a of 32.2° with respect to the bottom panel.

[0011] Preferably, the length of the bent portion of the multi-layer prepreg ply in the edge structure is set to increase from inside to outside.

[0012] Preferably, the left L-shaped panel and the right L-shaped panel each have a rounded corner transition at the corner.

[0013] Preferably, the composite T-stringer further comprises a twist strip filled in a space surrounded by the innermost layer of prepreg ply of the left L-shaped panel and the right L-shaped panel at the rounded corner transition and the uppermost layer of prepreg ply of the bottom panel.

[0014] The composite T-stringer according to the above scheme can effectively avoid the problem of skin wrinkling of the stiffened panel prepared by the "dry stringer-wet skin" co-bonding forming process, and the structure of the T-stringer structure bottom edge edge layer by layer covering can effectively reduce the edge stress concentration of the T-shaped part and the skin after bonding, thereby avoiding the risk of delamination of the stringer bottom edge edge. BRIEF DESCRIPTION OF DRAWINGS

[0015] For better understanding of the above and other purposes, features, advantages and functions of the present application, reference can be made to the preferred embodiments shown in the accompanying drawings. The same or similar reference signs in the drawings refer to the same or similar parts. Those skilled in the art should understand that the drawings are intended to illustrate the preferred embodiments of the present application, and have no limiting effect on the scope of the present application, and the various parts in the drawings are not drawn to scale.

[0016] Figure 1 is a schematic view of a composite T-stringer according to the prior art.

[0017] Figure 2 is a schematic view of a composite T-stringer according to one preferred embodiment of the present application.

[0018] Figures 3-8 are process diagrams for manufacturing a composite T-stringer according to one preferred embodiment of the present application, respectively. DETAILED DESCRIPTION

[0019] The retaining mechanism according to a preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. It is understood that the following description is merely a preferred embodiment of the present invention, and those skilled in the art can conceive of other ways to implement the present invention based on the preferred embodiments; such other ways also fall within the scope of the present invention.

[0020] First, it should be noted that the directional and positional terms used in this utility model should be understood as relative directions and positions, rather than absolute directions and positions.

[0021] The following text will mainly refer to Figure 2 A detailed description of the composite material T-shaped stringer according to a preferred embodiment of the present invention is provided.

[0022] like Figure 2 As shown, the composite material T-string includes a left L-shaped layer 1, a right L-shaped layer 2, and a bottom layer 3 disposed at the bottom of the left L-shaped layer 1 and the right L-shaped layer 2. The left L-shaped layer 1 and the right L-shaped layer 2 are symmetrically arranged with respect to the longitudinal center plane of the composite material T-string. Both the left L-shaped layer 1 and the right L-shaped layer 2 include multiple layers of prepreg, and the bottom layer 3 also includes multiple layers of prepreg. In the illustrated embodiment, the left L-shaped layer 1 and the right L-shaped layer 2 each include 8 layers of prepreg, and the bottom layer 3 includes 2 layers of prepreg. It is understood that in other embodiments not shown, the left L-shaped shelf 1, the right L-shaped shelf 2, and the bottom shelf 3 may also be provided with other numbers of prepreg layers. For example, the left L-shaped shelf 1 and the right L-shaped shelf 2 may be provided with 6 or 10 layers of prepreg, and the bottom shelf 3 may be provided with 3 or 4 layers of prepreg, etc. Those skilled in the art can make the settings according to the actual structural strength design requirements of the parts.

[0023] like Figure 2 As shown, the left L-shaped shelf 1 and the right L-shaped shelf 2 each have edge structures 22 located at both ends of the composite T-shaped stringer along the width direction of the composite T-shaped stringer. That is, the left L-shaped shelf 1 has an edge structure 22 located at the left end of the composite T-shaped stringer along the width direction of the composite T-shaped stringer, and the right L-shaped shelf 1 has an edge structure 22 located at the right end of the composite T-shaped stringer along the width direction of the composite T-shaped stringer.

[0024] The left L-shaped shelf 1 and the right L-shaped shelf 2 have the same but mirror-like structures. Therefore, for the sake of simplicity, only the right L-shaped shelf 2 will be described in detail below. It can be understood that the left L-shaped shelf 1 has a similar structure.

[0025] like Figure 2As shown, the edge structure 22 is wedge-shaped, and the multiple layers of prepreg plies in the edge structure 22 are configured to be wrapped layer by layer from inside to outside towards the bottom panel 3 to form a wedge-shaped bevel structure wrapped layer by layer, that is, the outer prepreg plies of the multiple layers of prepreg plies wrap the inner prepreg plies adjacent thereto. In the illustrated embodiment, only the outermost prepreg plies are exposed to the outside, and the other prepreg plies are wrapped inside. This scheme can effectively reduce the edge stress concentration of the T-shaped part after the skin is bonded to the T-shaped stringer structure, thereby avoiding the risk of delamination of the bottom edge of the stringer structure. Further reference Figure 2 As shown, the edge structure 22 is wedge-shaped, and the multiple layers of prepreg plies in the edge structure 22 are configured to be wrapped layer by layer from inside to outside towards the bottom panel 3 to form a wedge-shaped bevel structure wrapped layer by layer, that is, the outer prepreg plies of the multiple layers of prepreg plies wrap the inner prepreg plies adjacent thereto. In the illustrated embodiment, only the outermost prepreg plies are exposed to the outside, and the other prepreg plies are wrapped inside. This scheme can effectively reduce the edge stress concentration of the T-shaped part after the skin is bonded to the T-shaped stringer structure, thereby avoiding the risk of delamination of the bottom edge of the stringer structure. Further reference

[0026] Further reference Figure 2 As shown, the edge structure 22 is wedge-shaped, and the multiple layers of prepreg plies in the edge structure 22 are configured to be wrapped layer by layer from inside to outside towards the bottom panel 3 to form a wedge-shaped bevel structure wrapped layer by layer, that is, the outer prepreg plies of the multiple layers of prepreg plies wrap the inner prepreg plies adjacent thereto. In the illustrated embodiment, only the outermost prepreg plies are exposed to the outside, and the other prepreg plies are wrapped inside. This scheme can effectively reduce the edge stress concentration of the T-shaped part after the skin is bonded to the T-shaped stringer structure, thereby avoiding the risk of delamination of the bottom edge of the stringer structure. Further reference

[0027] As shown, the edge structure 22 is wedge-shaped, and the multiple layers of prepreg plies in the edge structure 22 are configured to be wrapped layer by layer from inside to outside towards the bottom panel 3 to form a wedge-shaped bevel structure wrapped layer by layer, that is, the outer prepreg plies of the multiple layers of prepreg plies wrap the inner prepreg plies adjacent thereto. In the illustrated embodiment, only the outermost prepreg plies are exposed to the outside, and the other prepreg plies are wrapped inside. This scheme can effectively reduce the edge stress concentration of the T-shaped part after the skin is bonded to the T-shaped stringer structure, thereby avoiding the risk of delamination of the bottom edge of the stringer structure. Further reference Figure 2 As shown, the edge structure 22 is wedge-shaped, and the multiple layers of prepreg plies in the edge structure 22 are configured to be wrapped layer by layer from inside to outside towards the bottom panel 3 to form a wedge-shaped bevel structure wrapped layer by layer, that is, the outer prepreg plies of the multiple layers of prepreg plies wrap the inner prepreg plies adjacent thereto. In the illustrated embodiment, only the outermost prepreg plies are exposed to the outside, and the other prepreg plies are wrapped inside. This scheme can effectively reduce the edge stress concentration of the T-shaped part after the skin is bonded to the T-shaped stringer structure, thereby avoiding the risk of delamination of the bottom edge of the stringer structure. Further reference

[0028] Further reference Figure 2 As shown, the edge structure 22 is wedge-shaped, and the multiple layers of prepreg plies in the edge structure 22 are configured to be wrapped layer by layer from inside to outside towards the bottom panel 3 to form a wedge-shaped bevel structure wrapped layer by layer, that is, the outer prepreg plies of the multiple layers of prepreg plies wrap the inner prepreg plies adjacent thereto. In the illustrated embodiment, only the outermost prepreg plies are exposed to the outside, and the other prepreg plies are wrapped inside. This scheme can effectively reduce the edge stress concentration of the T-shaped part after the skin is bonded to the T-shaped stringer structure, thereby avoiding the risk of delamination of the bottom edge of the stringer structure. Further reference

[0029] The method for manufacturing the composite T-shaped stringer according to the preferred embodiment of the present application will be described in detail below. The method comprises the following steps: Figures 3-8 As shown, the edge structure 22 is wedge-shaped, and the multiple layers of prepreg plies in the edge structure 22 are configured to be wrapped layer by layer from inside to outside towards the bottom panel 3 to form a wedge-shaped bevel structure wrapped layer by layer, that is, the outer prepreg plies of the multiple layers of prepreg plies wrap the inner prepreg plies adjacent thereto. In the illustrated embodiment, only the outermost prepreg plies are exposed to the outside, and the other prepreg plies are wrapped inside. This scheme can effectively reduce the edge stress concentration of the T-shaped part after the skin is bonded to the T-shaped stringer structure, thereby avoiding the risk of delamination of the bottom edge of the stringer structure. Further reference

[0030] Figure 3 ​As shown, firstly, an automatic tape-laying machine is used to lay the prepreg into prepreg ply 5, and then the prepreg ply 5 is cut into the following shapes: Figure 3 The edge layup boundaries are flush, and positioning references (such as positioning round holes, triangular positioning holes, etc.) are cut out in the web allowance area of ​​the prepreg 5.

[0031] Next, as Figure 4 As shown, the prepreg layer 5 is positioned and placed onto the preforming fixture 7 using the positioning reference, such as the positioning hole, in the above steps via the positioning pin 8. The preforming fixture 7 adopts a segmented structure, mainly composed of three parts: a lower mold body 7-1 (e.g., made of aluminum), an upper mold body 7-2 (e.g., made of N1007, WB-700, or epoxy EP978), and a fixing plate 7-3 (e.g., made of aluminum). The edge of the fixing plate 7-3 preferably has a chamfered design, for example, a 20° bevel angle, and the chamfered edge is far from the preform 6 (e.g., ...). Figure 5 The radius (R) of the corner is approximately 5mm. After the material layer is placed, the prepreg layer 5 is bent into a roughly C-shaped preform 6 using a heat-insulating preforming process. Figure 5 As shown, after the preforming is completed, a page-gradient wedge-shaped beveled edge structure is formed on the edge of the C-shaped preform 6, and the bevel angle of the page-gradient wedge-shaped beveled edge structure is 32.2°.

[0032] like Figure 6 As shown, the C-shaped preform 6 can then be transferred to the solidified molding core 10. After the transfer, the page-gradient wedge-shaped edge structure of the C-shaped preform 6 can be reverse-bent. Then, the C-shaped preform 6 is vacuum-packed and compacted to fit against the solidified molding core 10, ultimately resulting in a C-shaped molded body 9 with a wedge-shaped oblique structure where the edge structure 22 is layered. The solidified molding core has a profile that matches the bottom edge shape of the T-shaped part.

[0033] Next, the upper and lower solidified molding core molds 10 and the C-shaped molded body 9 can be arranged according to... Figure 7 The materials are combined as shown, then the twist strip 4, bottom layer 3, and equalizing plate 21 are placed. Finally, the above materials are vacuum-sealed and cured according to the curing requirements of prepreg. After demolding, the desired result is obtained. Figure 8 The H-shaped composite material blank 12 is shown. Then, it can be processed and cut according to the web contour of the T-shaped part by manual processing or CNC machining, so as to obtain the T-shaped stringer part with the bottom edge of the flange covered layer by layer as involved in this utility model.

[0034] The composite material T-shaped stringer and its molding method according to this application have the following main advantages:

[0035] 1) can high quality, high efficiency to achieve the net size forming of T type stringer structure bottom edge edge.

[0036] 2) can effectively avoid the problem of the stiffened wall panel skin wrinkle prepared by using the "dry stringer-wet skin" co-bonding forming process.

[0037] 3) the structure form of the bottom edge edge layer by layer covering can effectively reduce the edge stress concentration after the T type part and the skin are bonded, and avoid the risk of delamination of the bottom edge edge of the stringer structure.

[0038] The above description of various embodiments of the present application is provided to a person of ordinary skill in the relevant art for the purpose of description. It is not intended to exclude or limit the present application to a single disclosed embodiment. As above, a person of ordinary skill in the art will understand various alternatives and modifications of the present application. Therefore, although some alternative embodiments are specifically described, a person of ordinary skill in the art will understand or relatively easily develop other embodiments. The present application is intended to include all alternatives, modifications and variations of the present application described herein, and other embodiments falling within the spirit and scope of the present application described above.

Claims

1. A composite T-stringer, characterized by, The composite T-stringer comprises a left L-shaped panel (1), a right L-shaped panel (2) and a bottom panel (3) arranged at the bottom of the left L-shaped panel (1) and the right L-shaped panel (2), the left L-shaped panel (1) and the right L-shaped panel (2) are arranged symmetrically with respect to the longitudinal center of the composite T-stringer, and the left L-shaped panel (1) and the right L-shaped panel (2) each comprise a plurality of layers of prepreg plies, The left L-shaped panel (1) and the right L-shaped panel (2) each have an edge structure (22) at both ends of the composite T-stringer along the width direction of the composite T-stringer, the plurality of layers of prepreg plies in the edge structure (22) are configured to be wrapped layer by layer from the inside to the outside towards the bottom panel (3) to form an edge layer-by-layer wrapped wedge-shaped oblique angle structure, and the end part of the plurality of layers of prepreg plies in the edge structure (22) is in contact with the bottom panel (3).

2. The composite T-stringer of claim 1, wherein, The outer side surface (2a) of the edge structure (22) is inclined with respect to the bottom panel (3).

3. The composite T-stringer of Claim 1, wherein, The plurality of layers of prepreg plies in the edge structure (22) of the left L-shaped panel (1) and the right L-shaped panel (2) are bent in the direction towards the bottom panel (3) with respect to the flat plurality of layers of prepreg plies in the remaining part of the bottom.

4. The composite T-stringer of Claim 2, wherein, The inclination angle α of the outer side surface (2a) of the edge structure (22) with respect to the bottom panel (3) is 30°-35°.

5. The composite T-stringer of Claim 4, wherein, The inclination angle α of the outer side surface of the edge structure (22) with respect to the bottom panel (3) is 32.2°.

6. The composite T-stringer of Claim 3, wherein, The length of the bent part of the plurality of layers of prepreg plies in the edge structure (22) is set to increase from the inside to the outside.

7. The composite T-stringer of Claim 1, wherein, The left L-shaped panel (1) and the right L-shaped panel (2) each have a round corner transition (11) at the corner.

8. The composite T-stringer of Claim 7, wherein, The composite T-stringer further comprises a twist strip (4) filled in the space surrounded by the innermost layer of prepreg plies of the left L-shaped panel (1) and the right L-shaped panel (2) at the round corner transition (11) and the uppermost layer of prepreg plies of the bottom panel (3).

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