Layering design method for carbon fiber composite large-scale frame structural member

Abstract

The invention relates to a carbon fiber composite material large-scale frame structural member layering design method which is characterized by comprising the following steps: step 1, structure splitting design: splitting a large-scale frame structural member into four layering structures including an inner layering area, a middle layering area, an outer layering area and a bending reinforcing area, the four-part layering structure is specifically designed as follows: in an inner layering area, the layering area is an inner side annular layering area, namely, a structure whole continuous and through layering related to the innermost side surface of the large frame structural part, so that loading force borne by all positions can be dispersed and transmitted to the whole structure in the fiber direction; through strict and ingenious design, the layering design method of the carbon fiber composite large-scale frame structural member is changed from original rough design and manual on-site modification and cutting into a machine cutting one-cutting type, so that secondary cutting of the carbon fiber prepreg is not needed in the laying process, and the precision of a finished product is guaranteed.

Description

Technical Field

[0001] The invention relates to a layup design method for a large composite material frame structure, and belongs to the field of composite material molding. Background Art

[0002] Carbon fiber composite materials refer to a material composed of carbon fiber reinforcement and resin matrix. Compared with traditional metal materials, structural parts made of carbon fiber composite materials have the characteristics of low density, high strength, impact resistance, and low thermal expansion coefficient. Since the 1990s, it has been widely used in high-tech fields such as aerospace and automobile manufacturing.

[0003] Large frame structural parts are load-bearing parts on satellites that bear all the loads of the products. In order to ensure the structural strength while meeting the requirements of lightweight products, the load-bearing beams are designed into C-shaped and H-shaped structures, which are then assembled together to form an integral structural frame. There are currently two methods for forming such complex large frame structural parts. One is to use a metal forming solution, where the load-bearing beams are mainly made of aluminum alloy to achieve joints and bends, and are usually assembled by welding. The other is to use a composite material forming solution, where the relatively simple load-bearing beams are first solidified and formed separately, and then assembled as a whole by screwing or riveting. Both solutions are relatively heavy and do not meet the lightweight requirements of the design. Summary of the invention

[0004] The purpose of the present invention is to provide a layup design method for large-scale frame structural parts of carbon fiber composite materials, after the carbon fiber prepreg layup in each internal laying area is completed, the external laying is carried out, and then integrated assembly, mold closing, and curing are carried out, so that the product production process is fast and the finished product structure strength is high.

[0005] A carbon fiber composite large-scale frame structure layup design method, characterized by comprising the following steps:

[0006] Step 1: Structural split design: Split the large frame structure into four layers of ply structure: inner ply area, middle ply area, outer ply area and bending reinforcement area. The design of the four-layer structure is as follows:

[0007] Inner ply area: This ply area is the inner circumferential ply area, that is, the ply that continuously penetrates the structure as a whole involved in the innermost surface of the large frame structure, so that the load force borne at each position can be dispersed and transmitted to the overall structure along the fiber direction;

[0008] Middle ply area: This ply area is the middle area of ​​the load-bearing beam of a large frame structure. The middle ply area is composed of multiple relatively independent middle ply sub-areas. Through ply design, multiple independent structures are wrapped into an integral structure.

[0009] External ply area: This ply area is the circumferential ply area on the outer side and upper and lower end surfaces of the large frame structure, that is, the ply that continuously penetrates the entire structure involved in the outermost surface of the large frame structure, so that the load force borne at each position can be dispersed and transmitted to the overall structure along the fiber direction;

[0010] Bending reinforcement area: This ply area is the area that runs through the two combined middle ply areas of the large frame structure. The bending reinforcement area is divided into multiple bending reinforcement sub-areas, which are used to strengthen the overall connection strength of the large frame structure from top to bottom;

[0011] Step 2: Split the layup structure into four parts, namely, the inner layup area, the middle layup area, the outer layup area and the bending reinforcement area, and unfold each part of the layup structure into a plane structure; design the structure of each layer of the layup structure of the inner layup area, the middle layup area, the outer layup area and the bending reinforcement area, split the entire sheet into multiple small sheets that are easy to lay according to the fiber direction and geometric shape characteristics, and then lay out the small sheets according to the fiber direction; wherein, the unfolded disconnection points of each layer in the inner layup area and the outer layup area are different to ensure that the connection points of each layer do not overlap when they are laid; wherein, the inner mold layup area, the middle mold layup area and the bending reinforcement area are laid by multiple layers of carbon fiber prepreg plies, the fiber directions of two adjacent carbon fiber prepreg plies are different, and the positions of the fiber connections of the carbon fiber prepreg plies between each layer do not overlap;

[0012] Step 3: Cutting of small pieces: Use a cutting machine to cut according to the arranged small piece layout, and number each small piece according to the corresponding shape, and use a marking pen to draw the bending schematic line on the cut small piece isolation film, group and bundle the small pieces according to the numbering, and finally stack and place them according to the order of laying the pieces;

[0013] Step 4, complete three layup areas independently: use respective molds to lay up carbon fiber prepreg in the inner mold layup area, the middle mold layup area and the bending reinforcement area respectively, so that the inner mold layup area, the middle mold layup area and the bending reinforcement area are laid up separately; the laying of the middle mold layup area means that each middle mold layup sub-area is laid up separately; the laying of the bending reinforcement area means that each bending reinforcement sub-area is laid up separately;

[0014] Step 5, overall assembly: Lay the laid middle mold ply area and bending reinforcement area on the inner mold ply area, wherein, firstly, lay a plurality of middle mold ply sub-areas on a plurality of designed positions of the inner mold ply area, and then respectively inlay a plurality of bending reinforcement sub-areas in the gap between two adjacent middle mold ply sub-areas, so that the middle mold ply sub-areas and the bending reinforcement sub-areas surround the outer surface of the inner mold ply area, and the bending reinforcement sub-area is laid on the inner ply area between two adjacent middle mold ply sub-areas, and the adjacent middle mold ply sub-areas and bending reinforcement sub-areas are also laid together, so that there is no exposed part on the outer side of the inner mold ply area;

[0015] Step 6: Laying the outer layer area: Laying the outer layer area on the outer surface of the three areas of the inner mold layer area, the middle mold layer area and the bending reinforcement area assembled together. The fiber directions of the two adjacent layers are different, and the positions of the fiber connections of the carbon fiber prepreg layers between the layers do not overlap;

[0016] Step 7: The large frame structure parts in the outer layer area are molded and cured, and the net size molded products can be obtained after demoulding.

[0017] 2. A method for designing the layup of a large-scale frame structure of carbon fiber composite materials according to claim 1, characterized in that, in step 1, when laying the four-part layup structure of the inner layup area, the middle layup area, the outer layup area and the bending reinforcement area, every two adjacent prepreg layups are different types of prepreg layups; after completing the laying of 2 to 3 layers, a vacuum compaction treatment is performed to ensure that there are no protrusions, wrinkles or bubbles.

[0018] When laying the four-part ply structure of the inner ply area, the middle ply area, the outer ply area and the bending reinforcement area described in step 2, six typical ply unfolding fiber forms can be selected and laid alternately; the specific structures of the six typical plies are:

[0019] 0° characteristic ply structure A: specially designed based on the fiber direction of large composite frame structures in non-enclosed areas, with the direction of each load-bearing beam being 0°; characteristic ply A is based on the normal direction of large composite frame structures, with the 0° fibers in the longitudinal direction of all load-bearing beams continuous from top to bottom, and the plies of the transverse load-bearing beams perpendicular to the normal direction are butt-jointed at the longitudinal load-bearing beam position, and the fibers in other parts are continuous;

[0020] 0° characteristic ply structure B: specially designed based on the fiber direction of large composite frame structural parts in non-enclosed areas, with the direction of each load-bearing beam being 0°; characteristic ply B is based on the direction perpendicular to the normal line of large composite frame structural parts, with 0° fibers in the transverse direction of all load-bearing beams being continuous in the circumferential direction, and the ply of the longitudinal load-bearing beams in the normal direction being butt-jointed at the transverse load-bearing beam position, and the fibers in other parts being continuous;

[0021] ±45° characteristic ply structure C: The large frame structure of composite materials in the non-enclosed area rotates 45° counterclockwise along the normal direction to +45°, and rotates 45° clockwise along the normal direction to -45°; all fiber directions are 45° or -45°, and the outer side is spliced ​​with the geometric shapes on the upper and lower sides. At the corner position, the geometric figures are split and re-spliced ​​to make the fiber continuous to the greatest extent;

[0022] 90° characteristic ply structure D: The vertical direction of each load-bearing beam of the large frame structure of composite materials in the non-enclosed area is 90°; when the characteristic ply D is a middle ply area, the ply docking position and the docking position of the upper and lower layers of the sheet are offset by more than 20mm at the protruding angle, and the splicing position is reciprocated and staggered;

[0023] 0° characteristic ply structure E: Specially designed based on the fiber direction of the large frame structure of the closed area composite material, the direction of each load-bearing beam is 0°, and the geometric shapes of the six faces are re-joined to form a fiber coating layer, and the joint positions are mirror-symmetrical; at the position with a protruding angle, the fibers on three sides are continuous, and the faces corresponding to the protruding angle are disconnected in the middle and respectively joined to the sheet on the reverse side, thereby achieving circumferential continuity of the fibers; at multiple corner positions, the fibers are alternately butt-jointed to avoid multiple disconnections at one place, which would cause a decrease in the bearing capacity of the area;

[0024] ±45° characteristic ply structure F: Specially designed based on the fiber direction of large composite frame structural parts in closed areas, the hexahedron rotates 45° counterclockwise along the normal direction to +45°, and rotates 45° clockwise along the normal direction to -45°; the geometric shapes of the six faces are re-joined to form a fiber coating layer; at the position with a protruding angle, the position where the fibers are continuous on one side of the protruding angle is selected for re-joining, so as to achieve the fiber continuity in the 45° direction as much as possible; at multiple corner positions, the fibers are alternately butt-jointed, and the butt-jointing position is selected in the straight large surface area to avoid multiple disconnections at one place, which causes the load-bearing capacity of the area to decrease;

[0025] During the ply disassembly process, one of the methods is selected to disassemble the ply according to the ply angle and geometric structure.

[0026] In the step three, the entire sheet is split into multiple small sheets that are easy to lay according to the fiber direction and geometric shape characteristics, and a cutting machine is used to accurately cut and number the sheets according to the corresponding shapes. The numbering rule is: the initials of the area name - the current number of layers - the sheet number, that is, from left to right, from top to bottom, they are numbered in sequence: 1, 2, 3...; the split small sheets are characterized by continuous fibers. According to the numbers on the numbered sheets, the positional relationship between the sheets can be quickly sorted out, and when laying on large surfaces and corner joints, the areas that need to be laid can be completely covered without missing or overlapping positions.

[0027] During the ply design process, a bending line schematic line is drawn at the corresponding position, and the bending schematic line is drawn on the cut sheet isolation film with an automatic cutting machine pen. During the paving process, the corresponding reference position is found according to the bending schematic line, and whether the bending schematic line and the actual bending line can coincide with each other, the correctness of the sheet paving position is verified again in reverse.

[0028] Beneficial effects:

[0029] The present invention adopts a method for integrally forming carbon fiber composite materials. During the forming process, the large frame structure is innovatively disassembled into an inner mold plying area, a middle mold plying area, an outer mold plying area, and a bending reinforcement area. Each plying area is a separate paving module. After the carbon fiber prepregs of each paving module are laid, they are assembled, molded, and cured. After demolding, a net-size molded product can be obtained without any additional weight for connection, and the quality is lighter. At the same time, in order to achieve a stable and effective connection at the bend, a special splicing design is performed on the sheets with different plying angles, so that the fibers of the frame structure product are as continuous as possible in the force direction at the connection and bend, ensuring the effective transmission of the load, so as to meet the strength of the overall frame at the connection and bend and other stress concentrations to meet the design requirements. The present invention provides a plying design method for large-scale frame structures of carbon fiber composite materials, which realizes the net size and lightweight molding of complex large-scale frame structures of carbon fiber composite materials, and solves the problem of insufficient strength at the connection and bend and other stress concentrations during the integral molding of large-scale frame structures of carbon fiber composite materials. At the same time, the materials are systematically numbered and the bending lines are drawn. Compared with the previous simple marking method on the materials, the position deviation and angle deviation of the laid materials are minimized to the greatest extent, making construction operations easier.

[0030] Through strict and ingenious design, the present invention changes the layup design method of large-scale frame structural parts of carbon fiber composite materials from the original rough design plus manual on-site modification and cutting to a machine cutting and cutting type, so that the laying process no longer requires secondary cutting of carbon fiber prepreg, thereby ensuring the accuracy of the finished product and greatly reducing the skill level requirements for construction personnel; the net size molding of large-scale frame structural parts of carbon fiber composite materials is achieved, and its mechanical properties meet the requirements.

[0031] The present invention uses a large frame structure formed by paving carbon fiber prepreg to replace the original aluminum alloy large frame structure and the composite material split and then riveted or screwed large frame structure; its weight is reduced by 30.2%-38.8% compared with aluminum alloy, and reduced by 20.6%-10.4% compared with the composite material split and then riveted or screwed. The present invention can be applied to the ply of other types of composite material products with similar structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 , a schematic diagram of a ply structure according to an embodiment of the present invention;

[0033] Figure 2 , a schematic diagram of the bending reinforcement area, the inner ply area, the middle ply area, and the outer ply area of ​​the ply structure of an embodiment of the present invention;

[0034] Figure 3 , a schematic diagram of the unfolding of the characteristic prepreg ply A in the ply area in the embodiment of the present invention;

[0035] Figure 4 , a schematic diagram of the deployment of the characteristic prepreg ply B in the ply area in an embodiment of the present invention;

[0036] Figure 5 , a schematic diagram of the unfolding of the characteristic prepreg ply C in the outer ply area according to an embodiment of the present invention;

[0037] Figure 6 , a schematic diagram of the unfolding and splicing process of one of the characteristic plies D in the ply area in an embodiment of the present invention;

[0038] Figure 7 , a schematic diagram of unfolding a prepreg characteristic ply E in the ply area in an embodiment of the present invention;

[0039] Figure 8 , a schematic diagram of unfolding a prepreg characteristic ply F in the ply area in an embodiment of the present invention;

[0040] Fig. 9 , schematic diagram of the structure of each paving area according to an embodiment of the present invention;

[0041] Fig.10 , schematic diagram of the paving lines of the outer paving area on the outer isolation film and the markings of the corresponding area sheets in the embodiment of the present invention;

[0042] Fig.11 Schematic diagram of re-splitting and re-assembling the ply features in the outer ply area of ​​the embodiment of the present invention Figure 1 ;

[0043] Fig.12 Schematic diagram of re-splitting and re-assembling the ply features in the outer ply area of ​​the embodiment of the present invention Figure 2 ;

[0044] Fig.13 Schematic diagram of re-splitting and re-assembling the ply features in the outer ply area of ​​the embodiment of the present invention Figure 3 ;

[0045] The corresponding figures are as follows:

[0046] 1-front lower middle layer area, 2-front middle lower middle layer area, 3-front middle upper middle layer area, 4-front upper middle layer area, 5-lower right middle layer area, 6-upper right middle layer area, 7-upper left middle layer area, 8-lower left middle layer area, 9-rear lower middle layer area, 10-rear middle lower middle layer area, 11-rear middle upper middle layer area, 12-rear upper middle layer area, 13-inner layer area, 14-outer layer area, 15-bending reinforcement area, 20-circumferential outer layer, 21-lower end outer layer, 22-upper end outer layer, 23-disassembly of upper end outer layer, 24 - Disassembly of the lower end outer layer, 25- Splicing of the outer layer, 26-45° outer layer, 27- Partial re-splicing of the material pieces, 28- Position of the raw material piece, 29- Position of the current material piece, 30- Transverse through-splicing position, 31- Transverse through-splicing position, 32- Upper end splicing position 1, 33- Upper end splicing position 2, 34- Front end splitting position, 35- Lower end splicing position 1, 36- Lower end splicing position 2, 37- Rear end splitting position, 40- Small pieces split from the end face corner, 41- The remaining long strips from the end face split, 43- Material rotation point. DETAILED DESCRIPTION

[0047] The present invention innovatively disassembles the large frame structure into the inner mold layer area, the middle mold layer area, the outer mold layer area and the bending reinforcement area during the molding process. After the carbon fiber prepreg layers in each paving area are laid, they are assembled, molded and cured, and the net size molded product can be obtained after demolding. At the same time, in order to achieve a stable and effective connection at the bend, the material pieces with different laying angles are specially spliced ​​and designed, so that the fibers of the frame at the connection and bend are as continuous as possible in the force direction, and the fibers of the large frame structure of carbon fiber composite materials are as continuous as possible in the force direction at the connection and bend, which is conducive to the transmission and dispersion of load force. During the process of laying out and cutting the ply sheets, the entire ply is split into multiple small sheets that are easy to lay according to the fiber direction and geometric shape characteristics. The sheets are cut and numbered according to the corresponding shapes using a cutter. During the cutting process, the automatic cutter pen draws bending schematic lines on the isolation film of the cut sheets. Compared with the previous simple marking method on the sheets, it is more convenient for sheet laying and comparison, and minimizes the position deviation and angle deviation of the laid sheets, making construction operations easier.

[0048] A carbon fiber composite large-scale frame structure layup design method, characterized by comprising the following steps:

[0049] Step 1: Attach Figure 1 The large-scale frame structure of the carbon fiber composite material of the embodiment, such as the attached Figure 2 As shown in the figure, the ply structure is divided into four parts, which are the bending reinforcement area, the inner ply area, the middle ply area, and the outer ply area from left to right. The specific description of the above four ply structures is as follows:

[0050] Inner layup area: This layup area is the inner circumferential layup area of ​​the large-scale carbon fiber composite frame structure of the embodiment, and its purpose is to realize the overall continuous penetration of fibers in the layup areas of the twelve groups on the inner side of the splicing and corner positions, so that the load force borne at each position can be dispersed and transmitted to the overall structure along the fiber direction, effectively preventing the large-scale carbon fiber composite frame structure of the embodiment from stress concentration on one side of the inner wall, causing local instability and damage.

[0051] Middle ply area: This ply area is the middle area of ​​the load-bearing beam of the large-scale frame structure of carbon fiber composite materials in the embodiment, which is divided into twelve groups of relatively independent middle ply areas. Each relatively independent middle ply area is wrapped into an integral structure through ply design. The purpose of the middle ply design is to quickly and effectively disperse the load force along the fiber direction to the entire relatively independent whole when any one or more directions of the middle ply area are subjected to load force, and then disperse the force to the whole frame through the surface that fits with the inner ply area and the outer ply area, so as to effectively prevent the large-scale frame structure of carbon fiber composite materials in the embodiment from stress concentration in the middle ply area and local instability and damage.

[0052] Outer layup area: This layup area is the circumferential layup area on the outer side and upper and lower end faces of the large-scale carbon fiber composite frame structure of the embodiment. The purpose is to realize the overall continuous penetration of the fibers in the layup areas of the twelve groups on the outer side of the splicing and corner positions, so that the load force borne at each position can be dispersed and transmitted to the overall structure along the fiber direction, effectively preventing the large-scale carbon fiber composite frame structure of the embodiment from stress concentration on one side of the outer wall, resulting in local instability and damage.

[0053] Bending reinforcement area: This ply area is the area that runs through the two combined middle ply areas of the large-scale frame structure of the carbon fiber composite material of the embodiment, and its purpose is to strengthen the overall connection strength of the large-scale frame structure of the carbon fiber composite material of the embodiment from top to bottom.

[0054] Step 2: Design the plies of the inner, middle and outer plies of the large-scale carbon fiber composite frame structure of the embodiment according to the structural characteristics and load conditions. First, simply geometrically unfold the ply shapes of the corresponding areas, and then re-cut and splice the ply shapes at the corresponding ply angles to achieve the purpose of making the fibers as continuous as possible (especially at bends and corners) at the current ply angle, staggering the ply joints regularly, and strengthening the longitudinal bearing performance of each load-bearing beam. Six typical ply unfolding forms in the large-scale carbon fiber composite frame structure of the embodiment are selected for illustration:

[0055] The prepreg 0° characteristic ply A in the inner and outer ply areas is specially designed based on the fiber direction of the large frame structure of the carbon fiber composite material in the embodiment, with the direction of each load-bearing beam being 0°. Figure 3 As shown, characteristic ply A is in the normal direction of the large carbon fiber composite frame structure of the embodiment, the longitudinal 0° fibers of all load-bearing beams are continuous from top to bottom, the plies of the transverse load-bearing beams perpendicular to the normal direction are butt-jointed at the longitudinal load-bearing beams, and the fibers in other parts are continuous.

[0056] The inner and outer prepreg 0° characteristic ply B is specially designed based on the fiber direction of the large frame structure of the carbon fiber composite material in the embodiment, with the direction of each load-bearing beam being 0°. Figure 4 As shown, characteristic ply B is a large frame structure of carbon fiber composite materials perpendicular to the normal direction of the embodiment, the 0° fibers in the transverse direction of all load-bearing beams are circumferentially continuous, the plies of the longitudinal load-bearing beams in the normal direction are butt-jointed at the transverse load-bearing beams, and the fibers in other parts are continuous.

[0057] ±45° characteristic ply C of the prepreg in the inner and outer ply areas: the large carbon fiber composite frame structure of the embodiment rotates 45° counterclockwise along the normal direction to +45°, and rotates 45° clockwise along the normal direction to -45°. Figure 5 As shown, characteristic ply C takes the 45° ply of the outer ply area of ​​the large frame structure of the carbon fiber composite material of the embodiment as an example, in which all the fiber directions are 45°, and the outer side is spliced ​​with the geometric shapes on the upper and lower sides. At the corner position, the fibers are made continuous to the greatest extent by splitting and re-splicing the geometric figures.

[0058] 90° characteristic ply D of the prepreg in the inner ply area, the middle ply area, and the outer ply area: The vertical direction of each load-bearing beam of the large carbon fiber composite material frame structure of the embodiment is 90°. Figure 6 As shown, characteristic ply D is an example of a middle ply area of ​​a large carbon fiber composite frame structure of an embodiment, and the ply docking position is offset by more than 20 mm from the docking position of the upper and lower layers of material at the corner position, and the splicing position is reciprocatingly offset and docked.

[0059] Prepreg 0° characteristic ply E in the middle ply area: Example Figure 7As shown, characteristic ply E is a 0° sheet in the middle ply area of ​​a large frame structure of a carbon fiber composite material in the embodiment as an example, and the direction of each load-bearing beam is 0°. The geometric shapes of the six faces are re-spliced ​​to form a fiber coating layer, and the splicing positions are mirror-symmetrical. At the position with a protruding angle, the fibers on three sides are continuous, and the faces corresponding to the protruding angle are disconnected in the middle position and spliced ​​on the sheets on the opposite side, respectively, so as to achieve the circumferential continuity of the fibers. At multiple corner positions, the fibers are alternately butt-jointed to avoid multiple disconnections at one place, which causes a decrease in the bearing capacity of the area.

[0060] Prepreg ±45° characteristic ply F in the middle ply area: Example Figure 8 As shown, the characteristic ply F is a -45° sheet in the middle ply area of ​​a large frame structure of a carbon fiber composite material in the embodiment as an example. The counterclockwise rotation of 45° along the normal direction is +45°, and the clockwise rotation of 45° along the normal direction is -45°. The geometric shapes of the six faces are rejoined to form a fiber coating layer. At the position with a protruding angle, the position where the fibers are continuous on one side of the protruding angle is selected for rejoining, so that the fibers in the 45° direction are as continuous as possible. At multiple corner positions, the fibers are alternately butt-jointed, and the butt-jointing position is selected in a large straight surface area to avoid multiple disconnections at one place, which causes a decrease in the bearing capacity of the area.

[0061] Step 3: Split the entire sheet into multiple small sheets that are easy to lay out according to the fiber direction and geometric shape characteristics, and then arrange the fiber direction of the sheets to Fig.10 For example, use a cutting machine to cut and number the sheet according to the corresponding shape, and use a marking pen to draw a bending schematic line on the cut sheet isolation film (on Fig. 9 The dotted line in the middle can be used as a reference line for paving during the paving process). The pieces are grouped and bundled according to their numbers, and finally stacked and placed in the order of paving.

[0062] Step 4: The order of laying the sheets in different parts is as follows:

[0063] Process 1: Lay the sheets in the inner layer area in order. First, lay the first layer of prepreg on the inner film forming mold. After the laying is completed, lay the second layer of prepreg. The second layer of prepreg is laid on the first layer of prepreg; the third layer of prepreg is laid on the second layer of prepreg, and so on; wherein, every two adjacent layers of prepreg are different types of prepreg; after every 2 to 3 layers of laying, vacuum compaction treatment is performed to ensure that there are no bulges, wrinkles or bubbles;

[0064] Step 2: Lay out the sheets of each independent middle mold area of ​​the middle layer area in sequence. The specific laying method refers to step 1;

[0065] Step 3: Combine the twelve independently laid middle molds with the inner molds in sequence according to their corresponding positions;

[0066] Step 4: Fill the four bending reinforcement areas with continuous 5mm prepreg sheets until the bending reinforcement areas are flat and there is no missing material, and then perform vacuum compaction to ensure that there are no bulges, wrinkles or bubbles in the overall sheet after assembly;

[0067] Step 5: Lay the sheets of the outer layer area in order. The specific laying method refers to step 1;

[0068] Step 6: After paving is completed, assemble the outer mold of the mold.

[0069] Step 7: Perform step-temperature pressurization and high-temperature curing molding on the entire product.

[0070] Example:

[0071] A carbon fiber composite large-scale frame structure layup design method, characterized by comprising the following steps:

[0072] Step 1: Attach Figure 1 The large-scale frame structure of the carbon fiber composite material of the embodiment, such as the attached Figure 2 As shown in the figure, the ply structure is divided into four parts, which are the bending reinforcement area, the inner ply area, the middle ply area, and the outer ply area from left to right. The specific description of the above four ply structures is as follows:

[0073] Inner layup area 13: This layup area is the inner circumferential layup area of ​​the large-scale frame structure of carbon fiber composite materials of the embodiment, and its purpose is to realize the overall continuous penetration of fibers in the layup areas of the twelve groups 1-12 on the inner side of the splicing and corner positions, so that the load force borne at each position can be dispersed and transmitted to the overall structure along the fiber direction, effectively preventing the large-scale frame structure of carbon fiber composite materials of the embodiment from stress concentration on one side of the inner wall, and causing local instability and damage.

[0074] Middle layup area: This layup area is the middle area of ​​the load-bearing beam of the large-scale frame structure of the carbon fiber composite material of the embodiment, and is divided into twelve relatively independent middle layup areas: middle layup area front lower 1, middle layup area front middle lower 2, middle layup area front middle upper 3, middle layup area front upper 4, middle layup area lower right 5, middle layup area upper right 6, middle layup area upper left 7, middle layup area lower left 8, middle layup area rear lower 9, middle layup area rear middle lower 10, middle layup area rear middle upper 11, middle layup area rear upper 12. Each relatively independent middle layup area is wrapped into an integral structure through layup design. The purpose of designing the middle layer in this way is that when the middle layer area is subjected to load force in any one or multiple directions, it can quickly and effectively disperse the load force along the fiber direction to the entire relatively independent whole, and then disperse the force to the whole frame through the surface in contact with the inner layer area and the outer layer area, so as to effectively prevent the large carbon fiber composite material frame structure of the embodiment from stress concentration in the middle layer area and causing local instability and damage.

[0075] Outer ply area 14: This ply area is the circumferential ply area of ​​the outer side and upper and lower end faces of the large frame structure of carbon fiber composite materials of the embodiment, and its purpose is to realize the overall continuous penetration of fibers in the ply areas of the twelve groups on the outer side of the splicing and corner positions, so that the load force borne by each position can be dispersed and transmitted to the overall structure along the fiber direction, effectively preventing the large frame structure of carbon fiber composite materials of the embodiment from stress concentration on one side of the outer wall, and causing local instability and damage.

[0076] Bending reinforcement zone 15: This ply zone is the area that runs through the two combined middle ply zones of the large carbon fiber composite material frame structure of the embodiment, and both are through-ply 0° fiber plies. Its purpose is to strengthen the overall connection strength of the large carbon fiber composite material frame structure of the embodiment from top to bottom.

[0077] Step 2: Design the plies of the inner, middle and outer plies of the large-scale carbon fiber composite frame structure of the embodiment according to the structural characteristics and load conditions. First, simply geometrically unfold the ply shapes of the corresponding areas, and then re-cut and splice the ply shapes at the corresponding ply angles to achieve the purpose of making the fibers as continuous as possible (especially at bends and corners) at the current ply angle, staggering the ply joints regularly, and strengthening the longitudinal bearing performance of each load-bearing beam. Six typical ply unfolding forms in the large-scale carbon fiber composite frame structure of the embodiment are selected for illustration:

[0078] 0° characteristic ply A of the prepreg in the inner and outer ply regions: The direction of the bearing beams of the large carbon fiber composite frame structure of the embodiment is 0°. Figure 3The figure shows a ply in the inner ply area 13, wherein the characteristic ply A is in the normal direction of the large carbon fiber composite frame structure of the embodiment, the longitudinal 0° fibers of all the load-bearing beams are continuous from top to bottom, the ply of the transverse load-bearing beam perpendicular to the normal direction is butted against the longitudinal load-bearing beam at position 31, and the fibers in other parts are continuous.

[0079] 0° characteristic ply B of the prepreg in the inner and outer ply regions: The direction of the bearing beams of the large carbon fiber composite frame structure of the embodiment is 0°. Figure 4 Shown is a type of ply in the inner ply area 13, wherein the characteristic ply B is a large carbon fiber composite frame structure member of the embodiment, perpendicular to the normal direction, with the 0° fibers of all the transverse load-bearing beams being circumferentially continuous, the ply of the longitudinal load-bearing beam in the normal direction being butted against the transverse load-bearing beam at 30, and the fibers in other locations being continuous.

[0080] ±45° characteristic ply C of the prepreg in the inner and outer ply areas: the large carbon fiber composite frame structure of the embodiment rotates 45° counterclockwise along the normal direction to +45°, and rotates 45° clockwise along the normal direction to -45°. Figure 5 As shown, taking a 45° ply in the outer ply area 14 of the large carbon fiber composite material frame structure of the embodiment as an example:

[0081] 1) Split: First, according to its geometric expansion structure, we can get Fig.11 The right side of the circumferential outer layer 20, the lower end outer layer 21, and the upper end outer layer 22 are split as an example Fig.11 On the left side, the upper outer ply disassembly 23 and the lower outer ply disassembly 24 are both split into a number of small pieces 40 split from the end face corners and a long strip 41 remaining from the end face splitting.

[0082] 2) Splicing: Splice the outer layer 20 of the ring and the small piece 40 split from the end corner, and the long strip 41 remaining after the end split to the example Fig.12 The position shown constitutes a spliced ​​outer layer 25.

[0083] 3) Fiber continuity Fiber splitting and splicing: as shown in the example Fig.13 As shown, a typical local piece is rejoined 27 to perform fiber splitting and splicing for fiber continuity. The raw material piece position 28 on the spliced ​​outer layer 25 has fibers that are cut and cannot be continuous. The raw material piece position 28 is rotated 32° clockwise with the raw material piece rotation point 43 as the origin to obtain the current raw material piece position 29, so that the raw material piece fibers at the raw material piece position 28 are continuous with the large surface. The fiber continuity of other positions is similarly performed by fiber splitting and splicing to obtain the 45° outer layer 26 with the maximum degree of fiber continuity.

[0084] 90° characteristic ply D of the prepreg in the inner ply area, the middle ply area, and the outer ply area: The vertical direction of each load-bearing beam of the large carbon fiber composite material frame structure of the embodiment is 90°. Figure 6 As shown, taking one of the 4 layers with a 90° angle in the front upper middle layer area of ​​the large carbon fiber composite material frame structure of the embodiment as an example:

[0085] 1) Split: First, according to its geometric expansion structure, we can get Figure 6 The unfolded pattern of the front upper 4 of the middle layer area on the right side is split at the front split position 34 and the rear split position 37 .

[0086] 2) Fiber continuity Fiber splitting and splicing: as shown in the example Figure 6 As shown, the example Figure 6 The right side is spliced ​​at the upper splicing position 132, the upper splicing position 2 33, the lower splicing position 135, and the lower splicing position 2 36 to obtain the example Figure 6 As shown in the figure on the left, select one side of the long fiber as the 90° fiber direction, and the joint position of the ply is offset by more than 20mm from the joint position of the upper and lower layers of the sheet at the corner position, and the splicing position is reciprocated and staggered to obtain the final ply shape. This makes the 90° fiber continuous at the corner. The fiber continuity of other positions is similarly performed by fiber splitting and splicing to obtain a 90° ply with the maximum degree of fiber continuity.

[0087] Prepreg 0° characteristic ply E in the middle ply area: Example Figure 7 As shown, characteristic ply E is a 0° sheet in the middle ply area of ​​a large frame structure of a carbon fiber composite material in the embodiment as an example, and the direction of each load-bearing beam is 0°. The geometric shapes of the six faces are re-spliced ​​to form a fiber coating layer, and the splicing positions are mirror-symmetrical. At the position with a protruding angle, the fibers on three sides are continuous, and the faces corresponding to the protruding angle are disconnected in the middle position and spliced ​​on the sheets on the opposite side, respectively, so as to achieve the circumferential continuity of the fibers. At multiple corner positions, the fibers are alternately butt-jointed to avoid multiple disconnections at one place, which causes a decrease in the bearing capacity of the area.

[0088] Prepreg ±45° characteristic ply F in the middle ply area: Example Figure 8As shown, the characteristic ply F is a -45° sheet in the middle ply area of ​​a large frame structure of a carbon fiber composite material in the embodiment as an example. The counterclockwise rotation of 45° along the normal direction is +45°, and the clockwise rotation of 45° along the normal direction is -45°. The geometric shapes of the six faces are rejoined to form a fiber coating layer. At positions with protruding corners, the positions where the fibers are continuous on one side of the protruding corners are selected for rejoining, so that the fibers in the 45° direction are as continuous as possible. At multiple corner positions, the fibers are alternately butt-jointed, and the butt-jointing positions are selected in the straight large surface area to avoid multiple disconnections at one place, which causes a decrease in the bearing capacity of the area.

[0089] Step 3: Split the entire sheet into multiple small sheets that are easy to lay out according to the fiber direction and geometric shape characteristics, and then arrange the fiber direction of the sheets to Fig.10 For example, use a cutting machine to cut and number the sheet according to the corresponding shape, and use a marking pen to draw a bending schematic line on the cut sheet isolation film (on Fig. 9 The dotted line in the middle can be used as a reference line for paving during the paving process). The pieces are grouped and bundled according to their numbers, and finally stacked and placed in the order of paving.

[0090] Step 4: The order of laying the sheets in different parts is as follows:

[0091] Step 1: Lay the sheets of the inner layer area 13 in order, first lay the first layer of prepreg on the inner film forming mold, and then lay the second layer of prepreg, the second layer of prepreg on the first layer of prepreg; the third layer of prepreg on the second layer of prepreg, and so on; wherein every two adjacent layers of prepreg are different types of prepreg; after every 2 to 3 layers of laying, vacuum compaction treatment is performed to ensure that there are no bulges, wrinkles or bubbles;

[0092] Step 2: Lay the sheets of each independent middle mold area of ​​the middle layer areas 1-12 in sequence. The specific laying method refers to step 1;

[0093] Step 3: Place the twelve independently laid middle molds according to the example Fig. 9 The corresponding positions are combined with the inner mold in sequence;

[0094] Step 4: Fill the four bending reinforcement areas 15 with continuous 5mm prepreg sheets until the bending reinforcement areas are flat and without missing materials, and perform vacuum compaction to ensure that there are no bulges, wrinkles or bubbles in the overall sheet after assembly;

[0095] Step 5: Lay the sheets of the outer paving area 14 in order. The specific paving method is as described in step 1.

[0096] Step 6: After paving is completed, assemble the outer mold of the mold.

[0097] Step 7: Perform step-temperature pressurization and high-temperature curing molding on the entire product.

[0098] The design of the present invention strictly complies with the carbon fiber composite material molding specifications, and adds the design ideas of fiber continuity at the bend of the ingenious layered fiber and modularized split construction of the product, which greatly ensures the continuity of the fiber and the accuracy of the laying position during construction, and greatly reduces the skill level requirements for the construction personnel. Effectively improve the overall structural strength of the product, wherein the inner layer area and the outer layer area are overall continuous fibers, the middle layer area is a local continuous coated fiber, and the fibers in the bending reinforcement area are mainly longitudinal continuous fibers. Through the local continuous coated fibers in the middle layer area, the strength of the corresponding parts can meet the design index requirements. The fibers in the bending reinforcement area can effectively improve the bending area, the longitudinal bearing capacity and the longitudinal load transfer performance. The inner layer area and the outer layer area sandwich the middle layer area and the bending reinforcement area in the middle to form a "sandwich" structure, so that the load force borne by each position can be dispersed and transferred to the overall structure along the fiber direction. The large-scale frame structure of the embodiment is relatively complex. After the product is divided into multiple modular areas, the difficulty of integrated molding can be effectively reduced, which is convenient for construction. Multiple areas can be constructed at the same time, which effectively improves the molding efficiency.

[0099] The method of the present invention can realize the net size molding of large-scale frame structural parts of carbon fiber composite materials, and its mechanical properties meet the requirements. The present invention is a large-scale frame structural part formed by paving carbon fiber prepreg, and its weight is reduced by 30.2%-38.8% compared with aluminum alloy, and reduced by 20.6%-10.4% compared with riveting or screwing after the composite material is split. The results of non-destructive testing show that the defect area is less than 0.2%. Under the conditions of 8g overload in the normal direction and 2g overload in the lateral direction, the overall structure is stable, and no debonding and delamination phenomena occur. Non-destructive testing again shows that no mechanical damage visible to the naked eye occurs, the defect area does not expand, and no new defect area is generated.

[0100] A layup design method for a large-scale frame structure of a carbon fiber composite material, characterized by comprising:

[0101] During the molding process, the large frame structure is innovatively disassembled into the inner mold ply area, the middle mold ply area, the outer mold ply area and the bending reinforcement area. After the carbon fiber prepreg ply is laid in each ply area, it is assembled, molded and cured. After demolding, the net size molded product can be obtained. At the same time, in order to achieve a stable and effective connection at the bend, six typical ply expansion forms are specially spliced ​​for the sheets with different ply angles, so that the fiber of the frame at the connection and bend is as continuous as possible in the force direction, and the fiber of the large frame structure of carbon fiber composite materials is as continuous as possible in the force direction at the connection and bend, which is conducive to the transmission and dispersion of load force. The overall ply is divided into multiple small sheets that are easy to lay according to the fiber direction and geometric shape characteristics. The sheets are cut and numbered according to the corresponding shapes by a cutting machine. During the unloading process, the automatic cutting machine pen draws the bending schematic line on the isolation film of the cut sheet.

[0102] Among them, the modular molding method first disassembles the large frame structure into multiple areas such as the inner mold laying area, the middle mold laying area, the outer mold laying area and the bending reinforcement area. The middle mold laying area can be divided into twelve small modules, which can be laid separately. After laying, they are assembled as a whole, molded and cured. After demolding, the net size molded product can be obtained.

[0103] The present invention has six typical ply deployment forms with special splicing designs, and the six typical ply deployment forms are all specific deployment methods based on the characteristics of unidirectional carbon fiber cloth reinforced resin-based prepreg; the six typical ply deployment forms are as follows:

[0104] The prepreg 0° characteristic ply A in the inner and outer ply areas is specially designed based on the fiber direction of the large frame structure of the carbon fiber composite material in the embodiment, with the direction of each load-bearing beam being 0°. Figure 3 As shown, characteristic ply A is in the normal direction of the large carbon fiber composite frame structure of the embodiment, the longitudinal 0° fibers of all load-bearing beams are continuous from top to bottom, the plies of the transverse load-bearing beams perpendicular to the normal direction are butt-jointed at the longitudinal load-bearing beams, and the fibers in other parts are continuous.

[0105] The inner and outer prepreg 0° characteristic ply B is specially designed based on the fiber direction of the large frame structure of the carbon fiber composite material in the embodiment, with the direction of each load-bearing beam being 0°. Figure 4 As shown, characteristic ply B is a large frame structure of carbon fiber composite materials perpendicular to the normal direction of the embodiment, the 0° fibers in the transverse direction of all load-bearing beams are circumferentially continuous, the plies of the longitudinal load-bearing beams in the normal direction are butt-jointed at the transverse load-bearing beams, and the fibers in other parts are continuous.

[0106] ±45° characteristic ply C of the prepreg in the inner and outer ply areas: the large carbon fiber composite frame structure of the embodiment rotates 45° counterclockwise along the normal direction to +45°, and rotates 45° clockwise along the normal direction to -45°. Figure 5 As shown, characteristic ply C takes the 45° ply of the outer ply area of ​​the large frame structure of the carbon fiber composite material of the embodiment as an example, in which all the fiber directions are 45°, and the outer side is spliced ​​with the geometric shapes on the upper and lower sides. At the corner position, the fibers are made continuous to the greatest extent by splitting and re-splicing the geometric figures.

[0107] 90° characteristic ply D of the prepreg in the inner ply area, the middle ply area, and the outer ply area: The vertical direction of each load-bearing beam of the large carbon fiber composite material frame structure of the embodiment is 90°. Figure 6 As shown, characteristic ply D is an example of a middle ply area of ​​a large carbon fiber composite frame structure of an embodiment, and the ply docking position is offset by more than 20 mm from the docking position of the upper and lower layers of material at the corner position, and the splicing position is reciprocatingly offset and docked.

[0108] Prepreg 0° characteristic ply E in the middle ply area: Example Figure 7 As shown, characteristic ply E is a 0° sheet in the middle ply area of ​​a large frame structure of a carbon fiber composite material in the embodiment as an example, and the direction of each load-bearing beam is 0°. The geometric shapes of the six faces are re-spliced ​​to form a fiber coating layer, and the splicing positions are mirror-symmetrical. At the position with a protruding angle, the fibers on three sides are continuous, and the faces corresponding to the protruding angle are disconnected in the middle position and spliced ​​on the sheets on the opposite side, respectively, so as to achieve the circumferential continuity of the fibers. At multiple corner positions, the fibers are alternately butt-jointed to avoid multiple disconnections at one place, which causes a decrease in the bearing capacity of the area.

[0109] Prepreg ±45° characteristic ply F in the middle ply area: Example Figure 8 As shown, the characteristic ply F is a -45° sheet in the middle ply area of ​​a large frame structure of a carbon fiber composite material in the embodiment as an example. The counterclockwise rotation of 45° along the normal direction is +45°, and the clockwise rotation of 45° along the normal direction is -45°. The geometric shapes of the six faces are rejoined to form a fiber coating layer. At the position with a protruding angle, the position where the fibers are continuous on one side of the protruding angle is selected for rejoining, so that the fibers in the 45° direction are as continuous as possible. At multiple corner positions, the fibers are alternately butt-jointed, and the butt-jointing position is selected in a large straight surface area to avoid multiple disconnections at one place, which causes a decrease in the bearing capacity of the area.

[0110] During the ply disassembly process, one of the methods is selected to disassemble the ply according to the ply angle and geometric structure;

[0111] According to the fiber direction and geometric shape characteristics, the whole sheet is split into multiple small sheets that are easy to lay. The sheets are cut and numbered according to the corresponding shapes using a cutting machine. The numbering rule is: the initials of the area name - the number of the current layer - the sheet number (from left to right, from top to bottom, numbered in sequence: 1, 2, 3...). The split small sheets are characterized by continuous fibers. According to the numbers on the numbered sheets, the positional relationship between the sheets can be quickly sorted out. When laying on large surfaces and corner joints, the required paving area can be completely covered without missing or overlapping positions.

[0112] Use the automatic cutting machine pen to draw the bending schematic line on the cut sheet isolation film. During the paving process, the reference position can be easily found according to the bending schematic line. And according to whether the bending schematic line and the actual bending line can coincide, the correctness of the sheet paving position can be reversely verified again.

[0113] The above descriptions are merely representative embodiments of the method of the present invention, which can be applied to laminate design of composite materials products with similar structures, and do not limit the technical scope of the present invention in any way.

Claims

1. A layup design method for large-scale frame structural components of carbon fiber composite materials, characterized in that: The following steps are involved: Step 1: Structural split design: Split the large frame structure into four layers of ply structure: inner ply area, middle ply area, outer ply area and bending reinforcement area. The design of the four-layer structure is as follows: Inner ply area: This ply area is the inner circumferential ply area, that is, the ply that continuously penetrates the structure as a whole involved in the innermost surface of the large frame structure, so that the load force borne at each position can be dispersed and transmitted to the overall structure along the fiber direction; Middle ply area: This ply area is the middle area of ​​the load-bearing beam of a large frame structure. The middle ply area is composed of multiple relatively independent middle ply sub-areas. Through ply design, multiple independent structures are wrapped into an integral structure. External ply area: This ply area is the circumferential ply area on the outer side and upper and lower end surfaces of the large frame structure, that is, the ply that continuously penetrates the entire structure involved in the outermost surface of the large frame structure, so that the load force borne at each position can be dispersed and transmitted to the overall structure along the fiber direction; Bending reinforcement area: This ply area is the area that runs through the two combined middle ply areas of the large frame structure. The bending reinforcement area is divided into multiple bending reinforcement sub-areas, which are used to strengthen the overall connection strength of the large frame structure from top to bottom; Step 2: Split the layup structure into four parts, namely, the inner layup area, the middle layup area, the outer layup area and the bending reinforcement area, and unfold each part of the layup structure into a plane structure; design the structure of each layer of the layup structure of the inner layup area, the middle layup area, the outer layup area and the bending reinforcement area, split the entire sheet into multiple small sheets that are easy to lay according to the fiber direction and geometric shape characteristics, and then lay out the small sheets according to the fiber direction; wherein, the unfolded disconnection points of each layer in the inner layup area and the outer layup area are different to ensure that the connection points of each layer do not overlap when they are laid; wherein, the inner mold layup area, the middle mold layup area and the bending reinforcement area are laid by multiple layers of carbon fiber prepreg plies, the fiber directions of two adjacent carbon fiber prepreg plies are different, and the positions of the fiber connections of the carbon fiber prepreg plies between each layer do not overlap; Step 3: Cutting of small pieces: Use a cutting machine to cut according to the arranged small piece layout, and number each small piece according to the corresponding shape, and use a marking pen to draw the bending schematic line on the cut small piece isolation film, group and bundle the small pieces according to the numbering, and finally stack and place them according to the order of laying the pieces; Step 4, complete three layup areas independently: use respective molds to lay up carbon fiber prepreg in the inner mold layup area, the middle mold layup area and the bending reinforcement area respectively, so that the inner mold layup area, the middle mold layup area and the bending reinforcement area are laid up separately; the laying of the middle mold layup area means that each middle mold layup sub-area is laid up separately; the laying of the bending reinforcement area means that each bending reinforcement sub-area is laid up separately; Step 5, overall assembly: Lay the laid middle mold ply area and bending reinforcement area on the inner mold ply area, wherein, firstly, lay a plurality of middle mold ply sub-areas on a plurality of designed positions of the inner mold ply area, and then respectively inlay a plurality of bending reinforcement sub-areas in the gap between two adjacent middle mold ply sub-areas, so that the middle mold ply sub-areas and the bending reinforcement sub-areas surround the outer surface of the inner mold ply area, and the bending reinforcement sub-area is laid on the inner ply area between two adjacent middle mold ply sub-areas, and the adjacent middle mold ply sub-areas and bending reinforcement sub-areas are also laid together, so that there is no exposed part on the outer side of the inner mold ply area; Step 6: Laying the outer layer area: Laying the outer layer area on the outer surface of the three areas of the inner mold layer area, the middle mold layer area and the bending reinforcement area assembled together. The fiber directions of the two adjacent layers are different, and the positions of the fiber connections of the carbon fiber prepreg layers between the layers do not overlap; Step 7: The large frame structure parts in the outer layer area are molded and cured, and the net size molded products can be obtained after demoulding.

2. The method for designing the layup of a large carbon fiber composite frame structure according to claim 1, characterized in that: In step one, when laying the four-part ply structure of the inner ply area, the middle ply area, the outer ply area and the bending reinforcement area, every two adjacent prepreg plies are prepreg plies of different types; after completing the laying of 2 to 3 layers, vacuum compaction treatment is performed to ensure that there are no bulges, wrinkles or bubbles.

3. The method for designing the layup of a large carbon fiber composite frame structure according to claim 1, characterized in that: When laying the four-part ply structure of the inner ply area, the middle ply area, the outer ply area and the bending reinforcement area described in step 2, six typical ply unfolding fiber forms can be selected and laid alternately; the specific structures of the six typical plies are: 0° characteristic ply structure A: specially designed based on the fiber direction of large composite frame structures in non-enclosed areas, with the direction of each load-bearing beam being 0°; characteristic ply A is based on the normal direction of large composite frame structures, with the 0° fibers in the longitudinal direction of all load-bearing beams continuous from top to bottom, and the plies of the transverse load-bearing beams perpendicular to the normal direction are butt-jointed at the longitudinal load-bearing beam position, and the fibers in other parts are continuous; 0° characteristic ply structure B: specially designed based on the fiber direction of large composite frame structural parts in non-enclosed areas, with the direction of each load-bearing beam being 0°; characteristic ply B is based on the direction perpendicular to the normal line of large composite frame structural parts, with 0° fibers in the transverse direction of all load-bearing beams being continuous in the circumferential direction, and the ply of the longitudinal load-bearing beams in the normal direction being butt-jointed at the transverse load-bearing beam position, and the fibers in other parts being continuous; ±45° characteristic ply structure C: The large frame structure of composite materials in the non-enclosed area rotates 45° counterclockwise along the normal direction to +45°, and rotates 45° clockwise along the normal direction to -45°; all fiber directions are 45° or -45°, and the outer side is spliced ​​with the geometric shapes on the upper and lower sides. At the corner position, the geometric figures are split and re-spliced ​​to make the fiber continuous to the greatest extent; 90° characteristic ply structure D: The vertical direction of each load-bearing beam of the large frame structure of composite materials in the non-enclosed area is 90°; when the characteristic ply D is a middle ply area, the ply docking position and the docking position of the upper and lower layers of the sheet are offset by more than 20mm at the protruding angle, and the splicing position is reciprocated and staggered; 0° characteristic ply structure E: Specially designed based on the fiber direction of the closed area composite large frame structure, with the direction of each load-bearing beam at 0°, the geometric shapes of the six faces are re-joined to form a fiber coating layer, and the joint positions are mirror-symmetrical; at the position with protruding corners, the fibers on three faces are continuous, and the faces corresponding to the protruding corners are disconnected in the middle and respectively joined to the sheet on the reverse side, thereby achieving circumferential continuity of the fibers; At multiple corners, the fibers are alternately butted to avoid multiple disconnections at one location, which would reduce the load-bearing capacity of the area. ±45° characteristic ply structure F: Specially designed based on the fiber direction of large composite frame structural parts in closed areas, the hexahedron rotates 45° counterclockwise along the normal direction to +45°, and rotates 45° clockwise along the normal direction to -45°; the geometric shapes of the six faces are reassembled to form a fiber coating layer; at the position with a protruding angle, the position where the fibers are continuous on one side of the protruding angle is selected for reassembly, so that the fibers in the 45° direction are as continuous as possible; At multiple corners, the fibers are alternately butted, and the butt joints are located in a straight large area to avoid multiple disconnections at one location, which would reduce the load-bearing capacity of the area. During the ply disassembly process, one of the methods is selected to disassemble the ply according to the ply angle and geometric structure.

4. The method for laying up a large carbon fiber composite material frame structure according to claim 1, characterized in that: In step three, the entire sheet is split into multiple small sheets that are easy to lay according to the fiber direction and geometric shape characteristics. The sheets are accurately cut and numbered according to the corresponding shapes using a cutting machine. The numbering rule is: the initials of the area name - the current number of layers - the sheet number, that is, from left to right, from top to bottom, they are numbered in sequence: 1, 2, 3...; the split small sheets are characterized by continuous fibers. According to the numbers on the numbered sheets, the positional relationship between the sheets can be quickly sorted out, and when laid on large surfaces and corner joints, they can completely cover the areas that need to be laid without missing or overlapping positions.

5. The method for laying up large carbon fiber composite material frame structures according to claim 1, characterized in that: During the ply design process, the bending line is drawn at the corresponding position, and the bending line is drawn on the cut sheet isolation film with an automatic cutting machine pen. During the paving process, the corresponding reference position is found according to the bending line, and whether the bending line coincides with the actual bending line is verified again in reverse to see if the sheet paving position is correct.

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