A method of integrally forming a composite material stiffened panel

Abstract

The application discloses a kind of composite stiffened panel integral forming methods;Including: S1, the composite material prepreg needed for forming composite skin is laid to form composite skin preform;S2, the composite material prepreg is laid to form composite stringer preform A;S3, the two ends of stringer on composite stringer preform A are cut to form bevel, obtain composite stringer preform;S4, composite stringer preform is fixed on composite skin preform, then again on composite stringer preform Laid composite material prepreg with stringer via hole, obtain stiffened panel preform;S5, after heating and curing, composite stiffened panel is prepared.The stiffened panel prepared by the application is the integrated structure of stringer and skin, and the stiffened panel formed by layer combination of the application avoids the risk of degumming compared with the panel manufactured by the existing process, and improves the structural stability and strength of the panel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material forming, in particular to a kind of composite material stiffened panel integral forming method. BACKGROUND

[0002] As an advanced means of transportation, civil aircraft, in addition to extremely strict safety requirements, more importantly, has greater profitability, and the main cost of aviation operation is maintenance and fuel. Thus civil aircraft has extremely strong demand for improving aircraft reliability and light weight. Composite materials are applied to aircraft structures, not only reduce the weight of aircraft flight, but also have extremely strong corrosion resistance and fatigue resistance, improve the safety of aircraft, and reduce the maintenance cost of aircraft. Boeing and Airbus, two aircraft manufacturers, have adopted composite materials in large quantities, achieving the purpose of structural weight reduction in design, cost reduction in manufacturing and energy saving in use, obtaining huge economic benefits and good social benefits.

[0003] The integral stiffened panel composed of composite stringers and skin has been widely used as a main force component in fuselage, wing, tail and other parts, which bears various loads including compression, tension, shear and other loads together with the skin during the entire life of the aircraft, to improve the bending and tensile capacity of the panel and enhance the stability.

[0004] In the prior art, the skin and stringer of the stiffened panel are generally separately cured and formed, and then combined by adhesive film bonding, and after bonding, it needs to be cured again in a hot press tank. The traditional composite material preparation process using a hot press tank has the defects of size limitation, high cost and low efficiency. At the same time, the stringer and skin may be delaminated, which affects the structure of the entire stiffened panel. Therefore, for the forming and manufacturing of composite panels, a new method is needed to achieve high efficiency and low cost manufacturing requirements. SUMMARY

[0005] The present application aims to provide a composite material stiffened panel integral forming method to overcome the defects of the existing composite material stiffened panel manufacturing process. The method of the present application lays the composite material stringer and skin together, and only needs to be put into the tank once, saving processing cost and improving forming efficiency. At the same time, the composite material stiffened panel manufactured by the method of the present application avoids the risk of delamination of the stringer and skin, and improves the structural stability and strength of the obtained panel.

[0006] The present application is realized by the following technical solutions:

[0007] A kind of composite material stiffened panel integral forming method, characterized in that the composite material stiffened panel includes a composite material skin and a composite material stringer arranged on the composite material skin;The two ends of the composite material stringer are arranged as bevelled ends.

[0008] The integral forming method of the composite stiffened panel comprises the following steps:

[0009] S1, skin laying: laying a plurality of composite prepregs required for forming the composite skin to form a composite skin preform;

[0010] S2, stringer laying: laying a plurality of composite prepregs to form a composite stringer preform A;

[0011] S3, stringer cutting: cutting the two ends of the stringer on the composite stringer preform A to form a chamfer, thereby obtaining a composite stringer preform;

[0012] S4, positioning and assembling: fixing the composite stringer preform on the composite skin preform, and then laying a composite prepreg with a stringer via hole on the composite stringer preform to obtain a stiffened panel preform;

[0013] S5, one-step curing: curing the stiffened panel preform to obtain a composite stiffened panel.

[0014] Specifically, in the process step S4 of the present application, the composite prepreg with a stringer via hole is laid on the composite stringer preform, which is used to ensure that the surface of the stiffened panel after cutting and forming a chamfer is still covered with continuous composite prepreg, thereby ensuring the structural strength of the obtained composite stiffened panel.

[0015] Specifically, the skin and the stringer in the existing composite stiffened panel are generally formed by separate curing, and then combined by adhesive film bonding, and after bonding, it needs to be cured in a hot press tank again. The traditional composite material preparation process using a hot press tank has defects such as size limitation, high cost, and low efficiency, and the stringer and the skin may be delaminated, which affects the structure of the entire panel. The integral forming method designed in the present application only needs to be put into the tank once, saving the curing cost and improving the production efficiency. At the same time, the stringer will not produce a step difference with the skin due to separate bonding, which makes the design and installation of rib and frame structure more convenient, and the load transfer path of rib and frame structure is shorter and more efficient. At the same time, the risk of skin wrinkling caused by stringer bonding can be avoided, and the bonding area of the stringer and the skin in the stiffened panel manufactured in the present application is increased, avoiding the risk of stringer delamination.

[0016] Further, an integral forming method of a composite stiffened panel: the composite stringer preform in step S3 is a continuous whole composed of a first L-shaped layer, a U-shaped layer, and a second L-shaped layer connected in sequence.

[0017] Still further, an integral forming method of a composite stiffened panel: further comprising an interlayer for increasing the thickness of the stringer web.

[0018] The intercalation is arranged between the first L-shaped layer and the U-shaped layer, and arranged between the second L-shaped layer and the U-shaped layer.

[0019] Further, a composite material stiffened panel integral forming method, the forming process of the composite material stringer prefabricated body is:

[0020] S3-1, lay the composite material prepreg on the L-shaped tool to form the first L-shaped layer and the second L-shaped layer respectively;

[0021] S3-2, lay the composite material prepreg on the U-shaped tool to form the U-shaped layer;

[0022] S3-3, lay the composite material prepreg on the flat plate tool to form the interlayer and compact the interlayer;

[0023] S3-4, the first L-shaped layer, the interlayer, the U-shaped layer, the interlayer and the second L-shaped layer are sequentially spliced to form a continuous whole, and the orientations of the first L-shaped layer and the second L-shaped layer are opposite;

[0024] Wherein: the connecting parts of the first L-shaped layer, the interlayer and the U-shaped layer, and the connecting parts of the U-shaped layer, the interlayer and the second L-shaped layer form the stringer, and the end of the stringer is cut to obtain the composite material stringer prefabricated body with beveling.

[0025] Further, a composite material stiffened panel integral forming method, the first L-shaped layer and the U-shaped layer, and the second L-shaped layer and the U-shaped layer all have a triangular blank area, and the triangular blank area is located below the interlayer.

[0026] Further, a composite material stiffened panel integral forming method, a unidirectional tape twist sub strip is filled into the triangular blank area.

[0027] Specifically, the composite material stiffened panel integral forming method provided by the application comprises the following steps:

[0028] The composite material stiffened panel integral forming method comprises the following steps:

[0029] S1, skin laying: lay a plurality of composite material prepregs required for forming the composite material skin to form a composite material skin prefabricated body;

[0030] S2, stringer laying: lay a plurality of composite material prepregs to form a composite material stringer prefabricated body A;

[0031] S3, long string cutting: cutting the two ends of the long string of the composite long string preform A to form a chamfer, to obtain a composite long string preform;

[0032] The forming process of the composite long string preform comprises the following steps:

[0033] S3-1, laying the composite prepreg on the L-shaped tool to form a first L-shaped layer and a second L-shaped layer respectively;

[0034] S3-2, laying the composite prepreg on the U-shaped tool to form a U-shaped layer;

[0035] S3-3, laying the composite prepreg on the flat plate tool to form an interlayer and compacting the interlayer;

[0036] S3-4, sequentially splicing the first L-shaped layer, the interlayer, the U-shaped layer, the interlayer and the second L-shaped layer to form a continuous whole, and keeping the first L-shaped layer and the second L-shaped layer opposite in direction;

[0037] Wherein: the connecting parts of the first L-shaped layer, the interlayer and the U-shaped layer, and the connecting parts of the U-shaped layer, the interlayer and the second L-shaped layer constitute a long string, and the end of the long string is cut to obtain a composite long string preform with chamfer;

[0038] S4, positioning and assembling: fixing the composite long string preform on the composite skin preform, and then laying the composite prepreg with long string via hole on the composite long string preform to obtain a stiffened panel preform;

[0039] S5, one-step curing: heating and curing the stiffened panel preform to obtain a composite stiffened panel.

[0040] The composite stiffened panel generally needs to be connected with other structural members for use, and the long string is generally shorter than the skin to leave a corresponding assembly area. The traditional long string and skin are separately formed, which can easily meet this requirement, while the integrated forming of the long string and the skin requires machining treatment of the end of the long string after forming, and the excess long string is milled off, but this may cause damage to the composite skin during machining, and there is no complete composite cover layer after machining, so there is a risk of fracture at the machining site. The present application adopts a new layering method, which adopts net size forming to avoid a series of risks caused by machining after forming.

[0041] The present application lays the composite long string and the skin together, which only needs one-time tank curing to save processing cost, and the long string and the skin are integrally formed without adhesive bonding to avoid the risk of adhesive separation.

[0042] The integral forming method provided by the present application has the following beneficial effects:

[0043] (1) The structure of the composite stiffened panel prepared by the method of the present application is a long string and skin integrated structure. The forming method of the present application forms the entire stiffened panel by layer combination, which is equivalent to expanding the bonding area of the long string edge strip and the skin. Compared with the existing process for manufacturing the stiffened panel, the method of the present application avoids the risk of delamination, and improves the structural stability and strength of the panel.

[0044] (2) The end of the composite long string needs to be cut into an inclined cut during the forming process, considering the position of the subsequent assembly area. However, the cutting will result in the discontinuity of the upper surface of the final panel, which will affect the stress of the entire panel and reduce the strength of the panel. The forming method of the present application first forms a long string preform by laying and pasting, and reduces the number of layers of the composite prepreg during the laying and pasting process of the long string preform, which is beneficial to the subsequent cutting to form an inclined cut. The end of the long string is cut to form an inclined cut end by hand after laying and pasting, and then the composite layer with a long string web hole is laid. In this way, the upper surface of the panel can be covered with continuous composite material, thereby increasing the strength of the panel. Since the number of layers of the long string is reduced, the thickness of the long string web is not enough. Therefore, the present application further increases the interlayer at the long string web to ensure the thickness of the long string web, thereby ensuring the rigidity and stability of the entire panel.

[0045] (3) The long string and the skin of the traditional process manufactured stiffened panel will have a depression. During the subsequent use of the panel (i.e. during the installation with the rib or frame structure), the existence of the depression will result in high assembly precision requirement with the rib or frame structure, and also result in higher manufacturing requirement and higher cost of the rib and frame structure. However, the present application improves the forming method and adopts an integral shaping process, which only needs one-time tank curing, thereby saving the curing cost, and the long string will not produce a step difference (depression) with the skin due to separate gluing, which is more convenient for the design and installation of the rib or frame structure.

[0046] (4) The stiffened panel manufactured by the integral forming method of the present application has no depression structure, which can make the force transmission path of the rib and frame structure shorter and more efficient, and can reduce the manufacturing requirement, cost and assembly precision requirement of the rib or frame structure, thereby improving the efficiency. The stiffened panel manufactured by the method of the present application can also avoid the risk of skin wrinkling caused by long string gluing, thereby improving the product quality. The stiffened panel manufactured by the method of the present application has no depression on the surface, which is easier to manufacture and install, and has higher load transmission efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.

[0048] Figure 1 Structure diagram of composite stiffened panel manufactured by traditional process;

[0049] Figure 2 Structure diagram of composite stiffened panel manufactured by the method of the present application;

[0050] Figures 3-5 Structure diagram of composite stiffened panel manufactured by the method of the present application;

[0051] Figure 6 Sectional view of composite stiffened panel manufactured by the method of example 1;

[0052] Figure 7 Assembly diagram of composite stiffened panel manufactured by traditional process and rib or frame structure;

[0053] Figure 8 Assembly diagram of composite stiffened panel manufactured by the method of example 1 and rib or frame structure.

[0054] Markings in the drawings: 1 composite skin, 2 composite stringer, 3 composite skin preform, 4 composite stringer preform, 5 composite prepreg with stringer via, 6 adhesive film, 7 depression, 8 rib or frame structure, 2-1 bevelled end, 4-1 first L-shaped ply, 4-2 U-shaped ply, 4-3 second L-shaped ply, 4-4 interlayer, 4-5 triangular blank area. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0056] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc. indicate the orientation or positional relationship, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. Moreover, the terms "first", "second" and the like are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0057] As shown in the composite material stiffened panel structure manufactured by the conventional process, the composite material skin 1 and the composite material stringer 2 are separately formed, the skin 1 and the stringer 2 need to be separately laid into the tank for curing, and then bonded by the adhesive film 6, and after bonding, the adhesive film needs to be cured again by entering the tank, which has high curing cost, and the bonding area of the stringer 2 and the skin 1 is limited, which has the risk of delamination. Figure 1 As shown in the composite material stiffened panel structure manufactured by the conventional process, the composite material skin 1 and the composite material stringer 2 are separately formed, the skin 1 and the stringer 2 need to be separately laid into the tank for curing, and then bonded by the adhesive film 6, and after bonding, the adhesive film needs to be cured again by entering the tank, which has high curing cost, and the bonding area of the stringer 2 and the skin 1 is limited, which has the risk of delamination.

[0058] Figure 7 As shown in the composite material stiffened panel structure manufactured by the conventional process, the composite material skin 1 and the composite material stringer 2 are separately formed, the skin 1 and the stringer 2 need to be separately laid into the tank for curing, and then bonded by the adhesive film 6, and after bonding, the adhesive film needs to be cured again by entering the tank, which has high curing cost, and the bonding area of the stringer 2 and the skin 1 is limited, which has the risk of delamination.

[0059] Embodiment 1

[0060] As shown in the composite material stiffened panel structure manufactured by the conventional process, the composite material skin 1 and the composite material stringer 2 are separately formed, the skin 1 and the stringer 2 need to be separately laid into the tank for curing, and then bonded by the adhesive film 6, and after bonding, the adhesive film needs to be cured again by entering the tank, which has high curing cost, and the bonding area of the stringer 2 and the skin 1 is limited, which has the risk of delamination. Figures 1-8 Figure 2 and Figure 6 As shown in the composite material stiffened panel structure manufactured by the conventional process, the composite material skin 1 and the composite material stringer 2 are separately formed, the skin 1 and the stringer 2 need to be separately laid into the tank for curing, and then bonded by the adhesive film 6, and after bonding, the adhesive film needs to be cured again by entering the tank, which has high curing cost, and the bonding area of the stringer 2 and the skin 1 is limited, which has the risk of delamination.

[0061] The above-mentioned composite material stiffened panel integral forming method comprises the following steps:

[0062] ​​S1, skin laying: lay several composite prepregs required for forming the composite skin 1 to form a composite skin preform 3;

[0063] S2, stringer laying: lay several composite prepregs to form a composite stringer preform A; wherein: the composite stringer preform A has a stringer structure;

[0064] S3, stringer cutting: cutting the two ends of the stringer on the composite stringer preform A to form a bevel, obtaining a composite stringer preform (as shown in Figure 3

[0065] Specifically, the forming process of the composite stringer preform includes the following steps:

[0066] S3-1, lay composite prepregs on L-shaped tooling to form first L-shaped layer 4-1 and second L-shaped layer 4-3 respectively;

[0067] S3-2, lay composite prepregs on U-shaped tooling to form U-shaped layer 4-2;

[0068] S3-3, lay composite prepregs on flat tooling to form interlayer 4-4 and compact the interlayer 4-4;

[0069] S3-4, then splice the first L-shaped layer 4-1, the compacted interlayer 4-4, the U-shaped layer 4-2, the compacted interlayer 4-4 and the second L-shaped layer 4-3 in turn to form a continuous whole, and keep the first L-shaped layer and the second L-shaped layer opposite in direction; At the same time, a triangular blank area 4-5 will be formed between the first L-shaped layer 4-1 and the U-shaped layer 4-2, and between the second L-shaped layer 4-3 and the U-shaped layer 4-2, and the triangular blank area 4-5 is located below the interlayer 4-4 (as shown in Figure 6

[0070] Wherein: the connection parts of the first L-shaped layer 4-1, the interlayer 4-4 and the U-shaped layer 4-2, and the connection parts of the U-shaped layer 4-2, the interlayer 4-4 and the second L-shaped layer 4-3 constitute the stringer 2, and cutting the end part of the stringer can obtain the composite stringer preform 4 with bevel (as shown in Figure 3

[0071] S4, positioning and assembling: fix the composite stringer preform 4 on the composite skin preform 3, and then lay the composite prepreg 5 with stringer via hole on the composite stringer preform 4 to obtain the stiffened panel preform (as shown in Figure 4 and 5 ​​​​

[0072] S5. One-step curing: The reinforced wall panel preform is heated and cured to obtain a composite material reinforced wall panel.

[0073] The composite material reinforced wall panel prepared by the method of the present invention is an integrated structure of stringer 2 and skin 1. The present invention forms the entire reinforced wall panel through a layup combination, which is equivalent to expanding the bonding area between the stringer edge strip and the skin. Compared with the reinforced wall panel manufactured by the existing process, it avoids the risk of delamination and improves the structural stability and strength of the wall panel.

[0074] In the integral molding method of the present invention, after the end of the stringer is cut, a composite material layup with through holes in the stringer web is laid. This ensures that the upper surface of the final wall panel is covered with a continuous composite material, avoiding the risk of breakage and increasing the strength of the stiffened wall panel.

[0075] like Figure 8 As shown, the composite material stiffened wall panel manufactured using the integral molding method of this invention has a composite material stringer 2 laid together with the skin 1 without the need for adhesive film 6. No sinking 7 (step difference) will occur between the stringer 2 and the skin 1. The assembly accuracy requirements are lower when assembling with the rib or frame structural members 8, making installation more convenient and load transfer more efficient. At the same time, due to the reduced assembly accuracy requirements, the manufacturing requirements for the rib or frame structural members are also reduced, thus reducing manufacturing costs.

[0076] The above-described preferred embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the invention. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for integral molding of a composite material reinforced wall panel, characterized in that, The composite material reinforced wall panel includes a composite material skin (1) and a composite material stringer (2) disposed on the composite material skin (1); the two ends of the composite material stringer (2) are set as beveled ends (2-1). The integral molding method for composite material reinforced wall panels includes the following steps: S1, Skin laying: Several composite prepregs required for forming the composite skin (1) are laid to form a composite skin preform (3). S2, stringer laying: Several composite material prepregs are laid to form a composite material stringer prefabrication A; S3, stringer cutting: cut the two ends of the stringer on the composite material stringer prefabricated body A to form a bevel, and obtain the composite material stringer prefabricated body (4). The composite material stringer prefabricated body (4) is a continuous whole composed of a first L-shaped ply (4-1), a U-shaped ply (4-2), and a second L-shaped ply (4-3) connected in sequence; S4. Positioning and assembly: Fix the composite material stringer prefabricated body (4) onto the composite material skin prefabricated body (3), and then lay composite material prepreg with stringer through holes on the composite material stringer prefabricated body (4) to obtain a reinforced wall panel prefabricated body. S5. One-step curing: The reinforced wall panel preform is heated and cured to obtain a composite material reinforced wall panel.

2. The method for integral molding of a composite material reinforced wall panel according to claim 1, characterized in that, It also includes inserts (4-4) for increasing the thickness of the girder web. The intercalation layer (4-4) is disposed between the first L-shaped ply (4-1) and the U-shaped ply (4-2), and between the second L-shaped ply (4-3) and the U-shaped ply (4-2).

3. The method for integral molding of a composite material reinforced wall panel according to claim 2, characterized in that, The molding process of the composite material stringer prefabricated body (4) is as follows: S3-1. Lay the composite prepreg on the L-shaped tooling to form the first L-shaped layup (4-1) and the second L-shaped layup (4-3). S3-2. Lay the composite prepreg on the U-shaped tooling to form the U-shaped layup (4-2). S3-3. Lay the composite prepreg on the flat tooling to form an intercalation layer (4-4) and compact the intercalation layer (4-4); S3-4. The first L-shaped ply (4-1), intercalation layer (4-4), U-shaped ply (4-2), intercalation layer (4-4) and the second L-shaped ply (4-3) are sequentially spliced ​​together to form a continuous whole, while keeping the orientation of the first L-shaped ply (4-1) and the second L-shaped ply (4-3) opposite. Among them, the connection parts of the first L-shaped ply (4-1), the intercalation layer (4-4) and the U-shaped ply (4-2), and the connection parts of the U-shaped ply (4-2), the intercalation layer (4-4) and the second L-shaped ply (4-3) constitute a stringer. The ends of the stringer are cut to obtain a composite material stringer prefabricated body (4) with beveled edges.

4. The method for integral molding of a composite material reinforced wall panel according to claim 2, characterized in that, There are triangular blank areas (4-5) between the first L-shaped ply (4-1) and the U-shaped ply (4-2) and between the second L-shaped ply (4-3) and the U-shaped ply (4-2), and the triangular blank areas (4-5) are located below the intercalation layer (4-4).

5. The method for integral molding of a composite material reinforced wall panel according to claim 4, characterized in that, Fill the triangular blank area (4-5) with a unidirectional twisted strip.

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