Connecting structure for triangular area of stringer and construction method

Abstract

The invention provides a stringer triangular area connecting structure and a construction method, the connecting structure comprises short fibers, resin and wrapping fabric, the short fibers and the resin are mixed according to a set volume ratio to form a prefabricated body, and the surface of the prefabricated body is wrapped with the wrapping fabric. The connecting structure can enhance the shear load transmission in the triangular area and improve the strength of the triangular area.

Description

Technical Field

[0001] This invention relates to the field of girder manufacturing, and in particular to a girder triangular connection structure and construction method. Background Technology

[0002] Currently, in the manufacture of aircraft fuselage and wing shells, composite materials are used for both the panels and stringers to ensure lightweight construction. For example, when bonding the cap-shaped stringer and panel together, rounded corners are created when the stringer and panel are attached. Due to these rounded corners, a triangular cavity is formed between the stringer and the panel. Figure 1 During the load-bearing process, this triangular area will cause stress concentration. Therefore, unidirectional fibers are usually used to fill it using an extrusion preforming process.

[0003] This process currently has the following drawbacks:

[0004] 1) There is a large shear force at the interface between the precast infill and the composite structure. Since the infill is unidirectional fiber, it cannot effectively transfer the shear load, resulting in stress concentration and triangular zone failure.

[0005] 2) When cracks occur in the triangular area, the cracks will rapidly propagate along the web bonding surface, causing the girder to detach from the wall panel and resulting in the overall failure of the structure. Summary of the Invention

[0006] In view of the shortcomings of the above-mentioned related technologies, the purpose of this invention is to provide a long girder triangular area connection structure and construction method to solve the problem of damage to the triangular area due to stress concentration in the related technologies.

[0007] To achieve the above and other related objectives, the present invention provides a stringer triangular connection structure for enhancing the strength of the triangular area between the wall panel and the stringer. The connection structure includes short fibers, resin and outer fabric. The short fibers and the resin are mixed in a set volume ratio to form a preform, and the outer fabric is wrapped around the surface of the preform.

[0008] Optionally, the short fibers are carbon fibers, cotton fibers, aramid fibers, or plant fibers.

[0009] Optionally, the outer fabric is a glass fiber fabric.

[0010] Optionally, the volume of the short fibers accounts for 30%-40% of the volume of the resin.

[0011] Optionally, the surface of the outer fabric is coated with adhesive, and the outer fabric is bonded to the triangular area by adhesive under heating and pressure.

[0012] Optionally, both the wall panel and the stringer are provided with bonding areas, and the bonding areas on the wall panel and the stringer correspond to each other. The bonding areas on the wall panel and the bonding areas on the stringer are connected by adhesive. The connection structure also includes a connector, which sews the bonding areas of the wall panel and the bonding areas of the stringer together along the thickness direction of the wall panel.

[0013] Optionally, the connector is made of carbon fiber, glass fiber, or aramid fiber.

[0014] A construction method for a long truss triangular section connection structure, characterized by comprising:

[0015] Laying the newly installed wall panels;

[0016] The newly made stringer is laid on the tooling, with a triangular area reserved between the stringer and the tooling.

[0017] Position the filler in the triangular area;

[0018] The stringer and filler are positioned on the wall panel, and both the stringer and the wall panel have bonding areas, with the bonding areas on the wall panel corresponding to the bonding areas on the stringer.

[0019] The stringers, wall panels, and fillers are placed together in a sewing machine, which uses connectors to sew the bonded areas of the wall panels and the bonded areas of the stringers along the thickness direction of the wall panels.

[0020] After the stitching is completed, the parts are placed in a heating device for heating and pressurization. At this time, the stringers, wall panels and fillers are bonded, cured and formed into one.

[0021] As described above, the girder triangular connection structure and construction method of the present invention have the following beneficial effects: by setting filler in the triangular area, the present invention improves the efficiency of shear load transfer in the triangular area, avoids stress concentration, improves the effective control of crack propagation, and thus improves the structural mechanical performance. Attached Figure Description

[0022] Figure 1 The diagram shown is a schematic diagram of the stringer and wall panel before assembly in an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram showing the completed assembly of the stringer and wall panels in an embodiment of the present invention.

[0024] Component designation explanation

[0025] 1. Rig; 2. Panel; 3. Filler; 4. Connector; 5. Bonding area. Detailed Implementation

[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0027] In the detailed description of embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0028] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for the device in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or there may be one or more layers in between. The phrase “between” as used herein includes both endpoint values.

[0029] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0030] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0031] like Figure 1 and Figure 2 As shown, this embodiment provides a stringer triangular connection structure that fills the triangular area between stringer 1 and panel 2 to achieve effective load transfer. Panel 2 is a planar structure; this embodiment uses a cap-shaped stringer 1 as an example. In manufacturing the outer shell of structures such as fuselages and wings, both stringer 1 and panel 2 are made of composite materials, such as carbon fiber, to ensure lightweight construction. When stringer 1 and panel 2 are assembled together, a triangular area exists between them. This area is prone to stress concentration, leading to problems such as cracking in the triangular structure.

[0032] The connection structure in this embodiment includes a filler 3 and a connector 4. The filler 3 is disposed in the triangular area between the stringer 1 and the wall panel 2, and the filler 3 effectively transfers the shear load within the triangular area. The filler 3 includes short fibers, resin, and an outer fabric. The specific steps for manufacturing the filler 3 are as follows: first, the resin is heated to a liquid state, and then the short fibers are mixed into the resin, with the short fibers arranged arbitrarily. The volume of the short fibers accounts for 30%-40% of the resin volume. Since the triangular area between the stringer 1 and the wall panel 2 has a fixed shape, when mixing the short fibers and resin, the short fibers and resin can be directly molded into a preform with the same shape as the triangular area. After molding, adhesive is applied to the surface of the preform, and the outer fabric is wrapped around the outer surface of the preform. Then, medium-low temperature heating and curing are performed to form the filler 3. The medium-low temperature is 55-120℃. Here, "short fiber" is a technical term referring to fibers with a limited length, such as cotton-type short fibers with a length of 33-38mm.

[0033] The short fibers in this embodiment include, but are not limited to, carbon fiber, cotton fiber, aramid fiber, and plant fiber.

[0034] The outer fabric is made of fiberglass. In this embodiment, by setting the outer fabric outside the preform, the friction between the filler 3 and the triangular area can be increased, making the filler 3 bond more firmly to the triangular area.

[0035] When short fibers are mixed with resin in the filler 3, the short fibers are arranged arbitrarily in all directions, so the filler 3 can withstand a certain load in all directions. Compared with unidirectional fibers, the filler 3 can withstand shear stress and effectively transfer shear stress, thereby increasing the strength of the triangular area and avoiding cracking and other problems in this area.

[0036] This embodiment provides a construction method for a long girder triangular connection structure, specifically including:

[0037] First, lay the newly made wall panel 2.

[0038] Then, the newly made stringer 1 is laid on the tooling. After the stringer 1 is positioned, a triangular area will be reserved between the stringer 1 and the tooling. At this time, the filler 3 is placed in the triangular area. When filling the triangular area with the filler 3, first apply glue to the surface of the outer fabric, and then fill and position the filler 3 in the triangular area.

[0039] Next, the stringer 1 (with tooling) and the filler 3 are positioned on the wall panel 2. Both the stringer 1 and the wall panel 2 are provided with bonding areas 5. When the stringer 1 is positioned on the wall panel 2, the bonding areas 5 on the wall panel 2 correspond to the bonding areas 5 on the stringer 1. For example, each end of the stringer 1 is provided with a bonding area 5, and the wall panel 2 is provided with two spaced bonding areas 5, and these two bonding areas 5 correspond one-to-one with the bonding areas 5 on the stringer 1.

[0040] Finally, the stringer 1, wall panel 2, and filler 3 are placed together in a sewing device. This device uses a connector 4 to sew the bonding areas 5 of the wall panel 2 and the stringer 1 together along the thickness direction of the wall panel 2, thus joining the wall panel 2 and the stringer 1. After sewing, the stringer is placed in a heating device for heating and pressurization. The heating temperature can be 200℃, and the pressure can be 7-8 bar. At this point, the stringer 1, wall panel 2, and filler 3 are bonded, cured, and formed into a single unit. In this embodiment, sewing enhances the bonding strength between the wall panel 2 and the stringer 1, thereby preventing crack propagation.

[0041] Connector 4 includes, but is not limited to, carbon fiber, glass fiber, and aramid.

[0042] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A girder triangular connection structure for enhancing the strength of the triangular area between the wall panel and the girder, characterized in that, The connecting structure includes short fibers, resin and outer fabric. The short fibers and the resin are mixed in a set volume ratio to form a preform, and the outer fabric is wrapped around the surface of the preform.

2. The long girder triangular connection structure according to claim 1, characterized in that: The short fibers are carbon fibers, cotton fibers, aramid fibers, or plant fibers.

3. The long girder triangular connection structure according to claim 1, characterized in that: The outer fabric is a glass fiber fabric.

4. The long girder triangular connection structure according to claim 1, characterized in that: The volume of the short fibers accounts for 30%-40% of the volume of the resin.

5. The long girder triangular connection structure according to claim 1, characterized in that: The surface of the outer fabric is coated with adhesive, and the outer fabric is bonded to the triangular area by adhesive under heating and pressure.

6. The long girder triangular connection structure according to claim 1, characterized in that: Both the wall panel and the stringer are provided with bonding areas, and the bonding areas on the wall panel and the bonding areas on the stringer correspond to each other. The bonding areas on the wall panel and the bonding areas on the stringer are connected by adhesive. The connection structure also includes a connector, which sews the bonding areas of the wall panel and the bonding areas of the stringer together along the thickness direction of the wall panel.

7. The long girder triangular connection structure according to claim 1, characterized in that: The connector is made of carbon fiber, glass fiber, or aramid.

8. A construction method for a long girder triangular connection structure, characterized in that: include: Laying the newly installed wall panels; The newly made stringer is laid on the tooling, with a triangular area reserved between the stringer and the tooling. Position the filler in the triangular area; The stringer and filler are positioned on the wall panel, and both the stringer and the wall panel have bonding areas, with the bonding areas on the wall panel corresponding to the bonding areas on the stringer. The stringers, wall panels, and fillers are placed together in a sewing machine, which uses connectors to sew the bonded areas of the wall panels and the bonded areas of the stringers along the thickness direction of the wall panels. After the stitching is completed, the parts are placed in a heating device for heating and pressurization. At this time, the stringers, wall panels and fillers are bonded, cured and formed into one.

Images