A method for suppressing curing deformation of composite material stringer stiffened wall panels

Abstract

This invention belongs to the field of composite material manufacturing and curing deformation control technology. It discloses a method for suppressing curing deformation of composite stringer-stiffened panels. By designing and controlling the thermal expansion coefficient of the molding die, the interfacial interaction behavior between the die and the composite material part is adjusted, thereby achieving control over the curing deformation of the stringer-stiffened panel. This solves the technical problems caused by curing deformation of stringer-stiffened panels, such as out-of-tolerance dimensions and prestressed assembly. This invention has a significant effect on suppressing curing deformation of thin, weak-stiffness panels.

Description

Technical Field

[0001] This invention application belongs to the field of composite material manufacturing and curing deformation control technology, specifically relating to a process method for suppressing curing deformation of composite material stringer stiffened panels by means of the interaction between the mold and the composite material. Background Technology

[0002] Composite material panels are core components of aircraft wings, fuselages, and tail sections, and their manufacturing quality represents the highest level of my country's aviation equipment. Panels often employ T-shaped, cap-shaped, or J-shaped stringers to increase bending stiffness, becoming stringer-reinforced panels. Due to factors such as panel structural asymmetry, mismatched fiber-resin properties, resin curing shrinkage, and thermal expansion and contraction, stringer-reinforced panels manufactured using autoclave molding processes typically exhibit concave deformation laterally towards the skin and convex deformation longitudinally towards the stringer, severely affecting the product's shape accuracy and assembly.

[0003] Methods for controlling curing deformation of composite materials typically include optimizing curing process parameters, using molding dies made of materials with a coefficient of thermal expansion close to that of the composite material, die surface compensation, and molding process optimization. Existing methods are effective for thin-walled structures with simple structures and linear curing deformation, but their effectiveness in controlling the nonlinear curing deformation of stiffened panels with long stringers is limited, and their practical implementation is unsatisfactory.

[0004] Therefore, it is necessary to propose a process to suppress the solidification deformation of stiffened wall panels with stringers, so as to achieve high-quality manufacturing of wall panel structures. Summary of the Invention

[0005] This invention application addresses the technical problems of shape deviation and prestressed assembly caused by curing deformation of stiffened composite material ...

[0006] To achieve the aforementioned objectives, the technical solution adopted in this application is as follows:

[0007] A method for suppressing curing deformation of a composite material stringer-reinforced wall panel includes the following steps:

[0008] Step 1: For the stiffened wall panel to be manufactured, determine its curing deformation form through typical component trial production or finite element simulation.

[0009] Step 2: Select a prepreg system suitable for use as a molding die. Based on the curing deformation form of the stringer stiffened wall panel obtained in Step 1, design the layup form of the composite material on the molding die according to the principle of symmetry.

[0010] Step 3: Prepare the forming mold for the stiffened wall panel of the long stringer in Step 1;

[0011] Step 4: Following the prepreg material and layup sequence in Step 2, lay and cure the prepreg material on the surface of the molding die prepared in Step 3 to obtain a composite material template fixed to the surface of the molding die.

[0012] Step 5: Process the composite material template from Step 4 according to the geometric parameters of the membrane surface of the stiffened wall panel in Step 1, so that its surface roughness is ≤Ra1.6, and obtain the mold for forming the stiffened wall panel with the composite material template.

[0013] Step 6: Apply release agent or attach release cloth to the working area of ​​the long stringer stiffened wall panel forming mold obtained in Step 5, and complete the manufacturing of the long stringer stiffened wall panel according to the manufacturing process.

[0014] As a further aspect of the present invention: in step 2, the working temperature of the selected prepreg system should be at least 10 degrees higher than the curing temperature of the stringer stiffened wall panel.

[0015] As a further aspect of the present invention: In step 2, the mold layup design should be based on unidirectional prepreg as the main material and fabric prepreg as the auxiliary material. In principle, the fabric prepreg is only placed in the last layer of the layup to prevent splitting damage during processing.

[0016] As a further aspect of the present invention: In step 2, the principle of layup design based on the curing deformation form of the stringer stiffened wall panel is as follows: observe the curing deformation form of the stringer stiffened wall panel from both the transverse and longitudinal directions; for concave deformation toward the molding die, increase the proportion of unidirectional prepreg layup perpendicular to the observation surface; for convex deformation away from the molding die, reduce the proportion of unidirectional prepreg layup perpendicular to the observation surface.

[0017] As a further aspect of the present invention: in step 2, the total thickness of the designed layup should not be less than 2 mm.

[0018] As a further aspect of the present invention: in step 3, it is necessary to grind away dirt, residual release agent and other debris from the surface of the molding mold.

[0019] As a further aspect of the present invention: in step 4, the composite material profile fixed to the surface of the molding die should be cured according to the curing parameters recommended by the supplier of the prepreg system selected in step 2.

[0020] As a further aspect of the present invention: in step 4, the composite material template fixed to the surface of the molding die can be cured and formed on the metal molding die template of the part, or it can be installed on the metal frame after forming.

[0021] As a further aspect of the present invention: in step 5, the net dimension lines and lay-up lines of the parts are imprinted on the surface of the composite material template.

[0022] As a further aspect of the present invention: in step 5, the length and width dimensions of the composite material template should take into account the space required for the laying line, bag making area and tooling accessories.

[0023] Compared with the prior art, the beneficial effects of this application are:

[0024] 1. This invention combines the curing deformation characteristics of stiffened stringer panels and fully leverages the designability advantages of composite materials. By adjusting the thermal expansion coefficient of the molding die and utilizing the interaction between the die and the composite material parts, the curing deformation of stiffened stringer panels can be controlled, thereby achieving high-quality manufacturing of panel-type parts.

[0025] 2. This invention has a significant effect on inhibiting curing deformation in thin, weak-rigid wall panels.

[0026] The present application will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0028] In the attached diagram:

[0029] Figure 1 This is a schematic diagram of the structure of the stiffened wall panel with long stringers required for this invention;

[0030] Figure 2 This is a schematic diagram of the curing deformation of the stiffened wall panel of the stringer according to the present invention;

[0031] Figure 3 This is a schematic diagram of the molding die for the stringer stiffened wall panel with composite material profile of the present invention.

[0032] The following are the annotations in the figure: stringer 11, wall panel 10, stringer reinforced wall panel 20, concave deformation 21, convex deformation 22, molding die 30, composite material profile 31. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] A method for suppressing curing deformation of composite stringer stiffened panels, applicable to autoclave molding processes of thermosetting resin-based composite materials, comprising the following steps:

[0035] Step 1: For the stiffened wall panel to be manufactured, determine its curing deformation form through typical component trial production or finite element simulation.

[0036] Step 2: Select a suitable prepreg system for the molding die. Based on the curing deformation pattern of the stringer-reinforced wall panel obtained in Step 1, design the composite material layup on the molding die according to the principle of symmetry. The working temperature of the selected prepreg system should be at least 10 degrees Celsius higher than the curing temperature of the stringer-reinforced wall panel. The mold layup design should primarily use unidirectional prepreg and secondarily use woven prepreg. The woven prepreg should ideally be placed only as the last layer to prevent damage such as fiber splitting during processing. The total designed layup thickness should not be less than 2 mm.

[0037] The principle for layup design based on the curing deformation pattern of the stringer-reinforced wall panel is as follows: observe the curing deformation pattern of the stringer-reinforced wall panel from both the transverse and longitudinal directions. For concave deformation towards the mold, increase the proportion of unidirectional prepreg layup perpendicular to the observation surface; for convex deformation away from the mold, reduce the proportion of unidirectional prepreg layup perpendicular to the observation surface.

[0038] Step 3: Prepare the forming mold for the stiffened wall panel of the long stringer in Step 1; the surface of the forming mold needs to be sanded to remove stains, residual release agent and other debris.

[0039] Step 4: Following the prepreg material and layup sequence from Step 2, lay and cure the prepreg material onto the mold surface prepared in Step 3 to obtain a composite material template fixed to the mold surface. The composite material template fixed to the mold surface should be cured according to the curing parameters recommended by the supplier of the prepreg system selected in Step 2. The composite material template fixed to the mold surface can be cured and formed on the metal mold plate of the part, or it can be installed on a metal frame after forming.

[0040] Step 5: Process the composite material template from Step 4 according to the geometric parameters of the film-coating surface of the stringer stiffened wall panel in Step 1, so that its surface roughness is ≤Ra1.6, and mark the net dimension lines and laying lines of the parts to obtain the forming mold of the stringer stiffened wall panel with the composite material template; the length and width dimensions of the composite material template should take into account the space required for the laying lines, bag making area and tooling accessories.

[0041] Step 6: Apply release agent or attach release cloth to the working area of ​​the long stringer stiffened wall panel forming mold obtained in Step 5, and complete the manufacturing of the long stringer stiffened wall panel according to the manufacturing process.

[0042] Figure 1-3 This is a schematic diagram illustrating one embodiment of the present invention.

[0043] A method for suppressing curing deformation of composite stringer-reinforced wall panels, applicable to autoclave molding processes of thermosetting resin-based composite materials, specifically includes the following steps:

[0044] Step 1: For the T-shaped stringer 11 stiffened wall panel 10 to be manufactured, the forming mold is located on the lower side of the wall panel away from the stringer. The stringer stiffened wall panel 20 after curing deformation is obtained through wall panel trial production. It can be found that the deformation form of the wall panel is: transversely, it is a concave deformation 21 towards the forming mold, and longitudinally, it is an upward convex deformation 22 away from the mold.

[0045] Step 2: Select a domestically produced unidirectional carbon fiber prepreg and a glass fiber fabric prepreg with single-layer cured thicknesses of 0.14 mm and 0.12 mm, respectively, for layup design. Define the stringer direction as the 0° direction and the direction perpendicular to the stringer as the 90° direction. Combining the deformation form of the stringer-reinforced wall panel obtained in Step 1, design the layup as [O 14 / (±45)].

[0046] Step 3: Prepare the molding mold 30 for the long stringer reinforced wall panel, and grind away surface stains, residual release agent and other debris.

[0047] Step 4: Follow the prepreg material and layup sequence selected in Step 2 [O] 14 [ / (±45)] The composite material template 31 is laid on and cured on the surface of the prepared molding mold 30 to obtain a composite material template 31 fixed on the surface of the molding mold.

[0048] Step 5: Machining the composite material template from Step 4 according to the geometric parameters of the stiffened wall panel film surface from Step 1, ensuring its surface roughness is ≤ Ra 1.6, and marking the net dimension lines and layup lines of the parts, resulting in the following: Figure 3 The mold shown is for forming a long stringer stiffened wall panel with a composite profile.

[0049] Step 6: Apply release agent to the working area of ​​the long stringer stiffened wall panel forming mold obtained in Step 5, and complete the manufacturing of the long stringer stiffened wall panel according to the manufacturing process.

[0050] This method combines the anisotropic curing deformation characteristics of stringer-reinforced wall panels, fully utilizes the designability of composite materials, and controls the curing deformation by adjusting the thermal expansion behavior of the forming mold of stringer-reinforced wall panels. It has low manufacturing cost and a significant curing deformation suppression effect on thin, weak stiffness wall panels, and has strong engineering application value.

[0051] Thus, the objective of this invention has been achieved.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for suppressing the curing deformation of a composite material stringer-reinforced wall panel, characterized in that, Includes the following steps: Step 1: For the stiffened wall panel to be manufactured, determine its curing deformation form through typical component trial production or finite element simulation. Step 2: Select a prepreg system suitable for use as a molding die. Based on the curing deformation form of the stringer stiffened panel obtained in Step 1, design the layup form of the composite material on the molding die according to the principle of symmetry. Specifically, observe the curing deformation form of the stringer stiffened panel from both the transverse and longitudinal directions. For the concave deformation towards the molding die, increase the proportion of unidirectional prepreg layup perpendicular to the observation surface. For upward convex deformations away from the molding die, reduce the proportion of unidirectional prepreg layup perpendicular to the observation surface. Step 3: Prepare the forming mold for the stiffened wall panel of the long stringer in Step 1: Step 4: Following the prepreg material and layup sequence in Step 2, lay and cure the prepreg material on the surface of the molding die prepared in Step 3 to obtain a composite material template fixed to the surface of the molding die; Step 5: Process the composite material template from Step 4 according to the geometric parameters of the membrane surface of the stiffened wall panel in Step 1, so that its surface roughness is ≤Ra1.6, and obtain the mold for forming the stiffened wall panel with the composite material template. Step 6: Apply release agent or attach release cloth to the working area of ​​the long stringer stiffened wall panel forming mold with composite material profile obtained in Step 5, and complete the manufacturing of the long stringer stiffened wall panel according to the manufacturing process.

2. The method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 1, characterized in that, In step 2, the operating temperature of the selected prepreg system should be at least 10 degrees higher than the curing temperature of the stringer stiffened panel.

3. The method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 1, characterized in that, In step 2, the mold layup design should be based on unidirectional prepreg as the main material and fabric prepreg as the auxiliary material. In principle, the fabric prepreg should only be placed in the last layer of the layup to prevent splitting damage during processing.

4. The method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 1, characterized in that, In step 2, the total thickness of the designed layup should not be less than 2 mm.

5. The method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 1, characterized in that, In step 3, it is necessary to grind and remove stains and residual release agent from the surface of the molding mold.

6. The method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 3, characterized in that, In step 4, the composite material template fixed to the surface of the molding die should be cured according to the curing parameters recommended by the supplier of the prepreg system selected in step 2.

7. A method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 1 or 6, characterized in that, In step 4, the composite material template fixed to the surface of the molding die can be cured and formed on the metal molding die template of the part, or it can be installed on the metal frame after forming.

8. The method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 1, characterized in that, In step 5, the net dimension lines and lay-up lines of the parts are imprinted on the surface of the composite material template.

9. The method for suppressing curing deformation of a composite material stringer-reinforced wall panel according to claim 8, characterized in that, In step 5, the length and width dimensions of the composite material template should take into account the space required for the laying line, bag making area, and tooling accessories.

Images