A carbon fiber composite material tank bracket and a manufacturing method thereof

Abstract

A carbon fiber composite tank bracket and a manufacturing method thereof, which relate to the technical field of aerospace vehicle structures. The present invention solves the problem that the existing launch vehicle tank bracket adopts a metal tank bracket and cannot meet the high performance and lightweight requirements of aerospace. The carbon fiber composite tank bracket of the present invention comprises a tank bracket shell and two metal ears, the left rib plate, the right rib plate and the web plate are connected end to end in sequence to form a tank bracket frame, the reinforcing plate is obliquely arranged inside the tank bracket frame, and the left rib plate, the right rib plate, the web plate and the reinforcing plate are integrated; the molding method of the present invention for manufacturing a carbon fiber composite tank bracket is realized by the following steps: step one, re-inspection of prepreg; step two, unloading of prepreg; step three, preparation of molding mold; step four, laying of prepreg; step five, mold closing; step six, curing; step seven, demolding and finishing. The present invention is used to manufacture a carbon fiber composite tank bracket.

Description

Technical Field

[0001] The invention relates to the technical field of aerospace vehicle structures, and in particular to a carbon fiber composite material tank bracket and a manufacturing method thereof. Background Art

[0002] Composite materials are the material basis of high-performance products and an important guarantee for the realization of advanced design concepts and technologies. Due to their lightweight and high-strength structural advantages, high-performance composite materials have been successfully used in many national key areas. The tank brackets supporting the power system currently use metal engines and tank brackets, which cannot meet the high-performance and lightweight requirements of aerospace. Carbon fiber composite tank brackets are used to design launch vehicle tank brackets and research on a series of key technologies. Previously, there was no precedent in China for the use of composite materials in aerospace bracket products. High-performance and lightweight launch vehicles are the upgrading and replacement projects of my country's launch vehicles. They have many innovative difficulties, a large technical span, and a high degree of complexity. They represent the highest level of my country's launch vehicles. The composite bracket product has high structural efficiency and good reliability, which fully meets the high-performance and lightweight requirements of aerospace, ensures the smooth progress of the series of models, and promotes the application of carbon fiber composite brackets in aerospace.

[0003] In summary, the existing launch vehicle tank bracket adopts a metal tank bracket, which has the problem of failing to meet the high performance and lightweight requirements of aerospace. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing launch vehicle tank bracket adopts a metal tank bracket and cannot meet the high performance and lightweight requirements of aerospace, and further provide a carbon fiber composite tank bracket and a manufacturing method thereof.

[0005] The technical solution of the present invention is:

[0006] A carbon fiber composite tank support, comprising a tank support shell and two metal ears 5, the tank support shell comprising a left rib plate 1, a right rib plate 2, a web plate 3 and a reinforcing plate 4, the web plate 3 being arranged horizontally, a circular arc groove 31 matching the outer circle of the tank being arranged in the middle of the upper end surface of the web plate 3, a metal ear 5 being arranged on both sides of the upper end surface of the web plate 3, a steel belt connecting hole 51 being arranged on the metal ear 5, the right rib plate 2 being arranged vertically at the lower right side of the web plate 3, the upper end of the right rib plate 2 being connected to the right end of the web plate 3, the left rib plate 1 being arranged obliquely between the web plate 3 and the right rib plate 2, the left rib plate The upper end of the left rib plate 1 is connected to the left end of the web 3, the lower end of the left rib plate 1 is connected to the lower end of the right rib plate 2, the left rib plate 1, the right rib plate 2 and the web 3 are connected end to end in sequence to form a tank support frame, the tank support frame is a hollow right triangle structure, the reinforcing plate 4 is obliquely arranged inside the tank support frame, the lower end of the reinforcing plate 4 is connected to the middle of the left rib plate 1, the upper end of the reinforcing plate 4 is connected to the intersection of the web 3 and the right rib plate 2, the outer sides of the left rib plate 1, the right rib plate 2 and the web 3 are simultaneously extended with wing plates at both ends, and the left rib plate 1, the right rib plate 2, the web 3 and the reinforcing plate 4 are an integrated structure.

[0007] Furthermore, the angle between the reinforcing plate 4 and the upper end surface of the web 3 is α, α=40°.

[0008] Furthermore, the metal lug 5 is made of titanium alloy TC4 material, and the tank bracket shell is a carbon fiber reinforced epoxy resin-based composite material shell, wherein the carbon fiber is M40 material; and the resin is epoxy resin material.

[0009] Furthermore, the length of the tank support shell is L, L=435 mm, and the height of the tank support shell is H, H=448 mm.

[0010] Furthermore, it also includes four first bolts. Two first screw holes 32 are respectively provided on both sides of the upper end surface of the web 3 along the vertical direction. Each metal lug 5 is connected to the web 3 through two first bolts.

[0011] Furthermore, the lower end surface of the metal ear 5 is fixedly connected to the upper end surface of the web 3 by gluing, and the adhesive is J-133 adhesive.

[0012] Furthermore, it also includes four second bolts. Two second screw holes 33 are respectively provided at the upper parts of both ends of the web 3. Both ends of the web 3 are connected to the external compartment section through the two second bolts.

[0013] A method for manufacturing a carbon fiber composite material tank bracket, the method is achieved by the following steps:

[0014] Step 1: Re-inspection of prepreg:

[0015] Environmental conditions for re-inspection of prepregs: ambient temperature (10-35)℃, relative humidity ≤65%; prepare materials, tools and measuring tools required for re-inspection, test the thickness, carbon fiber volume content, unit area mass, volatile content and gel time of prepregs, re-inspect the epoxy value of epoxy resin in prepregs, and re-inspect the tensile strength and tensile modulus of carbon fiber bundles in prepregs;

[0016] Step 2: Prepreg cutting:

[0017] Environmental conditions for prepreg cutting: ambient temperature (15-35)℃, humidity ≤65%; take the prepreg out of the freezer and place it at room temperature for 2-4 hours before use. The cutting angle is 0° with the reference line as 0°, and the cutting angle is in the directions of 0°, 90°, +45°, and -45°, and records should be kept;

[0018] Step 3: Preparation of molding mold:

[0019] Use tools to clean the mold and apply mold release agent on the mold surface;

[0020] Step 4: Prepreg laying;

[0021] a. Divide the tank support shell into four small pieces, namely the left rib plate 1, the right rib plate 2, the web plate 3 and the reinforcing plate 4. Lay the four small surfaces separately, and define the direction parallel to the frame as 0° and the direction perpendicular to the frame as 90°.

[0022] First, lay out the left rib 1. The laying angle takes the short straight side as 0°, and the laying is carried out in the directions of 0°, 90°, +45°, -45°, 0°, and 90°, and keep a record. The laying angle takes the long straight side as 0°, and the laying is carried out in the directions of 0°, 90°, +45°, -45°, 0°, and 90°, and keep a record. The laying angle takes the curved side as 0°, and the laying is carried out in the directions of 0°, 90°, 0°, 90°, and keep a record.

[0023] Then, the right rib plate 2 is laid, and the specific steps of laying the right rib plate 2 are the same as those of laying the left rib plate 1;

[0024] Then, the web plate 3 is laid, and the specific steps of laying the web plate 3 are the same as those of laying the left rib plate 1;

[0025] Finally, the reinforcing plate 4 is laid. The specific steps of laying the reinforcing plate 4 are the same as those of laying the left rib plate 1.

[0026] So far, the separate laying of the left rib 1, the right rib 2, the web 3 and the reinforcing plate 4 has been completed;

[0027] b. Combine all small pieces and then lay the reinforcement area ply;

[0028] c. After paving the reinforcement area, pre-press, then lay the combined small pieces and then lay the layers;

[0029] Step 5: Mold closing:

[0030] Use bolt pressure mold closing, ensure the front and rear positions of the mold are aligned when closing the mold, tighten the pressure bolts symmetrically when closing the mold, so as to close the upper and lower molds. After closing the mold, put the mold into the curing oven, heat it at 100℃ in the curing oven for 3 hours, then take out the product, and the mold gap is less than 0.1mm when the mold is in place;

[0031] Step 6: Curing:

[0032] Cure according to the curing system (100±5)℃ / (1±10min)h→(150±5)℃ / (2±10min)h→(170±5)℃ / (4±10min)h, increase the temperature at a uniform rate, and save the curing curve data;

[0033] Step 7: Demolding and trimming:

[0034] d. Take out the cured product and mold from the curing oven, cool it naturally to room temperature and then demould it.

[0035] e. Remove all bolts, remove the upper and lower molds and the left and right molds, remove the blocks inside the cover in order, take out the product, and do not scratch the mold surface when demolding;

[0036] f. Clean the mold and clean the mold surface with copper or aluminum sheets;

[0037] g. For molds that are not to be used in the short term, apply silicone grease evenly on the molding surface to prevent rust; when storing the molds, place the male and female molds in a closed position and pay attention to dust and moisture prevention;

[0038] h. Use a file or sandpaper to trim the rough edges of the product;

[0039] At this point, the manufacturing of the carbon fiber composite tank bracket has been completed.

[0040] Furthermore, the prepreg described in step 1 is a carbon fiber hot-melt prepreg, with a single layer thickness of 0.15 mm, a carbon fiber volume content of (58±2)%, and a unit area mass of (305±5) g / m 2 , volatile content ≤2%, gel time (150℃) (40±5)min; the epoxy value of the epoxy resin in the carbon fiber hot-melt prepreg is ≥0.85; the tensile strength of the carbon fiber bundle in the carbon fiber hot-melt prepreg is ≥3000MPa, and the tensile modulus is ≥330Gpa.

[0041] Furthermore, the tool used for cleaning the mold described in step three is a copper sheet or an aluminum sheet. After the mold is cleaned and there is no residual impurities on the working surface, wipe the surface of the mold with industrial-grade acetone, and then evenly apply a layer of release agent with a flat brush, and wait for it to be completely dried for use.

[0042] Compared with the prior art, the present invention has the following effects:

[0043] 1. The carbon fiber composite tank bracket structure of the present invention has high efficiency and good reliability, which fully meets the high performance and lightweight requirements of aerospace, ensures the smooth progress of the series of models, and promotes the application of carbon fiber composite material series brackets in aerospace. The carbon fiber composite tank bracket of the present invention is a triangular-shaped special-shaped shape, with a T-shaped and cross-shaped cross-section and a narrow width. Two carbon fiber composite tank brackets carry a tank at the same time. The overall structure of the carbon fiber composite tank bracket is overloaded by 11g in the axial direction and 4g in the lateral direction. Steel-wrapped belts are used to connect the carbon fiber composite tank bracket and the tank, and prestress is increased to improve the integrity of the tank and the bracket when bearing loads. When loaded, each component is loaded as a whole, and the strength and stiffness are calculated to meet the design requirements.

[0044] 2. The method for manufacturing a carbon fiber composite tank bracket of the present invention solves the technical problem of integrated design and molding of a carbon fiber composite tank bracket. The molding process adopts a hot melt prepreg mold compression molding method. When designing the layers, it is necessary to consider that the fiber continuity must be ensured during the molding process, and the layer angle reference must be reasonable and easy to implement. First, the left and right ribs and the web are separately molded, and then assembled into a whole, and the reinforcement area and the side wing panels are molded. The carbon fiber composite tank bracket manufactured by this method has high structural efficiency and good reliability, and fully meets the high performance and lightweight requirements of aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a front view of the carbon fiber composite material tank bracket of the present invention;

[0046] Figure 2 It is a right side view of the carbon fiber composite material tank bracket of the present invention;

[0047] Figure 3 is a top view of the carbon fiber composite material tank bracket of the present invention;

[0048] Figure 4 is the ply coordinate system and ply partition diagram of the present invention;

[0049] Figure 5 It is a preliminary analysis of the stress check value distribution cloud diagram;

[0050] Figure 6 It is a schematic diagram of the finite element analysis model of the tank bracket constraints and connections. DETAILED DESCRIPTION

[0051] Specific implementation method 1: Combination Figures 1 to 3The present embodiment is described. A carbon fiber composite tank support of the present embodiment comprises a tank support shell and two metal ears 5. The tank support shell comprises a left rib plate 1, a right rib plate 2, a web plate 3 and a reinforcing plate 4. The web plate 3 is arranged horizontally. A circular arc groove 31 matching the outer circle of the tank is arranged in the middle of the upper end surface of the web plate 3. A metal ear 5 is respectively arranged on both sides of the upper end surface of the web plate 3. A steel belt connecting hole 51 is provided on the metal ear 5. The right rib plate 2 is vertically arranged at the lower right side of the web plate 3. The upper end of the right rib plate 2 is connected to the right end of the web plate 3. The left rib plate 1 is obliquely arranged between the web plate 3 and the right rib plate. 2, the upper end of the left rib plate 1 is connected to the left end of the web 3, the lower end of the left rib plate 1 is connected to the lower end of the right rib plate 2, the left rib plate 1, the right rib plate 2 and the web 3 are connected end to end in sequence to form a tank bracket frame, the tank bracket frame is a hollow right triangle structure, the reinforcing plate 4 is obliquely arranged inside the tank bracket frame, the lower end of the reinforcing plate 4 is connected to the middle of the left rib plate 1, the upper end of the reinforcing plate 4 is connected to the intersection of the web 3 and the right rib plate 2, the outer sides of the left rib plate 1, the right rib plate 2 and the web 3 are simultaneously extended with wing plates at both ends, and the left rib plate 1, the right rib plate 2, the web 3 and the reinforcing plate 4 are an integrated structure.

[0052] The outer sides of the left rib plate 1, the right rib plate 2 and the web plate 3 of this embodiment are all provided with wing plates extending to both ends at the same time, and a composite material reinforcement area is designed and optimized at the connection between the bracket and other structures, and is integrally formed.

[0053] Specific implementation method 2: Combination Figure 1 This embodiment is described. The angle between the reinforcing plate 4 and the upper end surface of the web 3 is α, α = 40°. In this way, in the design process of the tank support structure, the overall outer dimensions are guaranteed to remain unchanged, the reinforcing plate 4 is designed, and its position is optimized. After analyzing the structure with angles ranging from 0° to 180°, it is determined that the angle position of 40° is the best. The other components and connection relationships are the same as those of the first embodiment.

[0054] Specific implementation method three: Combination Figures 1 to 3 This embodiment is described. The metal lug 5 of this embodiment is made of titanium alloy TC4 material, the tank bracket shell is a carbon fiber reinforced epoxy resin composite material shell, the carbon fiber is M40 material; the resin is epoxy resin material. Other components and connection relationships are the same as those of the first or second embodiment.

[0055] Specific implementation method four: Combination Figure 1 To explain this embodiment, the length of the tank support shell of this embodiment is L, L=435mm, and the height of the tank support shell is H, H=448mm. Other components and connection relationships are the same as those of the first, second or third embodiments.

[0056] Specific implementation method five: Combination Figures 1 to 3This embodiment is described. This embodiment also includes four first bolts. Two first screw holes 32 are respectively provided on both sides of the upper end surface of the web 3 in the vertical direction. Each metal lug 5 is connected to the web 3 through two first bolts. In this way, the weak strength area is designed and optimized. The metal reinforcement is locally designed and optimized at the bolt position connecting the tank. The other components and connection relationships are the same as those of the first, second, third or fourth embodiments.

[0057] Specific implementation method six: Combination Figures 1 to 3 To explain this embodiment, the lower end surface of the metal lug 5 of this embodiment is fixedly connected to the upper end surface of the web 3 by gluing, and the adhesive is J-133 adhesive. Other components and connection relationships are the same as those of the specific embodiments one, two, three, four or five.

[0058] Specific implementation method seven: Combination Figures 1 to 3 This embodiment further includes four second bolts, and two second screw holes 33 are respectively provided at the upper parts of the two ends of the web 3, and the two ends of the web 3 are respectively connected to the external compartment through the two second bolts. Other components and connection relationships are the same as those of the specific embodiments 1, 2, 3, 4, 5 or 6.

[0059] Specific implementation method eight: Combination Figures 1 to 6 This embodiment is described. This embodiment is a method for manufacturing a carbon fiber composite material tank bracket. The method is implemented by the following steps:

[0060] Step 1: Re-inspection of prepreg:

[0061] Environmental conditions for re-inspection of prepregs: ambient temperature (10-35)℃, relative humidity ≤65%; prepare materials, tools and measuring tools required for re-inspection, test the thickness, carbon fiber volume content, unit area mass, volatile content and gel time of prepregs, re-inspect the epoxy value of epoxy resin in prepregs, and re-inspect the tensile strength and tensile modulus of carbon fiber bundles in prepregs;

[0062] Step 2: Prepreg cutting:

[0063] Environmental conditions for prepreg cutting: ambient temperature (15-35)℃, humidity ≤65%; take the prepreg out of the freezer and place it at room temperature for 2-4 hours before use. The cutting angle is 0° with the reference line as 0°, and the cutting angle is in the directions of 0°, 90°, +45°, and -45°, and records should be kept;

[0064] Step 3: Preparation of molding mold:

[0065] Use tools to clean the mold and apply mold release agent on the mold surface;

[0066] Step 4: Prepreg laying;

[0067] a. Divide the tank support shell into four small pieces, namely the left rib plate 1, the right rib plate 2, the web plate 3 and the reinforcing plate 4. Lay the four small surfaces separately, and define the direction parallel to the frame as 0° and the direction perpendicular to the frame as 90°.

[0068] First, lay out the left rib 1. The laying angle takes the short straight side as 0°, and the laying is carried out in the directions of 0°, 90°, +45°, -45°, 0°, and 90°, and keep a record. The laying angle takes the long straight side as 0°, and the laying is carried out in the directions of 0°, 90°, +45°, -45°, 0°, and 90°, and keep a record. The laying angle takes the curved side as 0°, and the laying is carried out in the directions of 0°, 90°, 0°, 90°, and keep a record.

[0069] Then, the right rib plate 2 is laid, and the specific steps of laying the right rib plate 2 are the same as those of laying the left rib plate 1;

[0070] Then, the web plate 3 is laid, and the specific steps of laying the web plate 3 are the same as those of laying the left rib plate 1;

[0071] Finally, the reinforcing plate 4 is laid. The specific steps of laying the reinforcing plate 4 are the same as those of laying the left rib plate 1.

[0072] So far, the separate laying of the left rib 1, the right rib 2, the web 3 and the reinforcing plate 4 has been completed;

[0073] b. Combine all small pieces and then lay the reinforcement area ply;

[0074] c. After paving the reinforcement area, pre-press, then lay the combined small pieces and then lay the layers;

[0075] Step 5: Mold closing:

[0076] Use bolt pressure mold closing, ensure the front and rear positions of the mold are aligned when closing the mold, tighten the pressure bolts symmetrically when closing the mold, so as to close the upper and lower molds. After closing the mold, put the mold into the curing oven, heat it at 100℃ in the curing oven for 3 hours, then take out the product, and the mold gap is less than 0.1mm when the mold is in place;

[0077] Step 6: Curing:

[0078] Cure according to the curing system (100±5)℃ / (1±10min)h→(150±5)℃ / (2±10min)h→(170±5)℃ / (4±10min)h, increase the temperature at a uniform rate, and save the curing curve data;

[0079] Step 7: Demolding and trimming:

[0080] d. Take out the cured product and mold from the curing oven, cool it naturally to room temperature and then demould it.

[0081] e. Remove all bolts, remove the upper and lower molds and the left and right molds, remove the blocks inside the cover in order, take out the product, and do not scratch the mold surface when demolding;

[0082] f. Clean the mold and clean the mold surface with copper or aluminum sheets;

[0083] g. For molds that are not to be used in the short term, apply silicone grease evenly on the molding surface to prevent rust; when storing the molds, place the male and female molds in a closed position and pay attention to dust and moisture prevention;

[0084] h. Use a file or sandpaper to trim the rough edges of the product;

[0085] At this point, the manufacture of the carbon fiber composite material tank bracket is completed. Other components and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth or seventh specific embodiments.

[0086] The performance data of prepreg unidirectional board shall meet the index requirements specified in the "Technical Requirements for Manufacturing and Acceptance of Composite Material Brackets". TDE-85 epoxy resin shall be retested for epoxy value according to "Q / HBY015-2002 Epoxy Resin Factory Retest Standard", and only those with epoxy value ≥0.85 can be used; M40 carbon fiber shall be retested for bundle tensile strength and tensile modulus according to "Q / HBY016-2002 Carbon Fiber Factory Retest Standard", and only those with bundle tensile strength ≥3000MPa and tensile modulus ≥330GPa can be used. Before the product goes into production, the prepreg used for bracket production shall be tested for unidirectional board mechanical properties. The test items and indicators are shown in Table 1, and the test method shall be carried out in accordance with the corresponding national standard or industry standard.

[0087] Table 1 Material one-way plate performance data

[0088] project unit M40 / 8485 performance data 0° tensile strength MPa ≥1050 0° tensile modulus GPa ≥200 90° tensile strength MPa ≥19 90° tensile modulus GPa ≥8.2 0° compression strength MPa ≥800 0° compression modulus GPa ≥120 90° compression strength MPa ≥92.9 90° compression modulus GPa ≥8.2 Interlaminar shear strength MPa ≥40 Shear modulus GPa ≥4.16 Fiber volume content ％ 60±3 Curing degree ％ ≥92

[0089] The prepreg used in the production of brackets should be from the same batch. When re-inspecting the prepreg, 10 layers of prepreg should be cut into small pieces and overlapped, compacted, and the thickness measured with a digital vernier caliper. The average value divided by 10 is the thickness of a single layer of prepreg.

[0090] The prepreg unloading environment described in step 2 is: a clean, tidy, dust-free, constant temperature and humidity room.

[0091] The specific requirements of the prepreg laying process described in step 4 are as follows: Paste the resin film on the mold, requiring the molding surface to be fully and evenly covered. After each layer is laid, use a putty knife to press hard to drive out bubbles. Trim the prepreg at the closed edge to ensure that the edges are neat and the mold is closed smoothly.

[0092] Specific implementation method nine: Combination Figures 1 to 6The prepreg described in step 1 of this embodiment is a carbon fiber hot-melt prepreg, with a single layer thickness of 0.15 mm, a carbon fiber volume content of (58±2)%, and a unit area mass of (305±5) g / m 2 , volatile content ≤ 2%, gel time (150°C) (40±5) min; epoxy value of epoxy resin in carbon fiber hot-melt prepreg ≥ 0.85; tensile strength of carbon fiber bundle in carbon fiber hot-melt prepreg ≥ 3000MPa, tensile modulus ≥ 330Gpa. Other components and connection relationships are the same as those in specific embodiments one, two, three, four, five, six, seven or eight.

[0093] The epoxy resin in the carbon fiber hot-melt prepreg in step one is TDE-85, and the carbon fiber in the carbon fiber hot-melt prepreg is M40.

[0094] Specific implementation method ten: Combination Figures 1 to 6 To explain this embodiment, the tool used for cleaning the mold in step 3 of this embodiment is a copper sheet or an aluminum sheet, which cannot damage the working surface (product surface) of the mold. After the mold is cleaned and no impurities remain on the working surface, the mold surface is wiped clean with industrial grade acetone, and then a layer of mold release agent is evenly applied with a flat brush, and it is ready for use after being completely dried. Other components and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth, seventh, eighth or ninth embodiments.

[0095] The manufacturer of the release agent in step 3 is CHEMLEASE, and the model is PMR.

[0096] How it works

[0097] The method for manufacturing a carbon fiber composite tank bracket of the present invention adopts a hot melt prepreg mold pressing method. When designing the ply, it is necessary to consider that the fiber continuity must be ensured during the laying process molding, and the ply angle reference must be reasonable and easy to implement. Therefore, four ply coordinate systems are defined, and the 0° direction of each ply coordinate system is parallel to the bracket wing plate and the reinforcing rib. Then the composite tank bracket is divided into 4 parts, and the ply angles are defined respectively, but the relationship between the ply angles of the 4 parts must be coordinated, because the ply angles of the continuous fibers in each part are different. Figure 4 It is the ply coordinate system and ply partition diagram, and the arrow direction is the ply angle 0° direction.

[0098] The result of finite element calculation requires high bending stiffness of the wing and rib, and more 0° plies are designed for the side position parallel to the wing and rib. When laying, 2-3 layers of continuous fiber are designed at this position, mixed with other angles to reduce the difficulty of mold closing when there are many concave and convex surfaces of continuous fiber. Because the structure is also overloaded laterally, 90° plies are required on the side wing.

[0099] When designing the mold, we first considered forming the left and right ribs and the belly plate separately, and then assembled them into a whole to form the reinforcement area and the side wing plate. According to the structural characteristics of the product, after repeated design and modification, the mold design adopts a multi-piece design, which is divided into three parts: upper, lower and side pressurization. The three parts are based on the upper and lower base plates. After the individual parts are laid and formed, they are positioned and fastened on the base plate, and the side wing plates are formed. The side pressurization plates are used to pressurize the wing plates, and the base plate provides a slideway for pressurizing the wing plates.

[0100] Precision composite material structure dimensional accuracy guarantee:

[0101] The dimensional accuracy requirements of carbon fiber composite tank brackets are very strict. First of all, two pieces are grouped together, which requires that the verticality of the bracket reference surface in the same group be consistent. During the laying process, a processing amount is reserved on the reference surface, and the tooling is designed to position the bracket. The reference surface is fine-machined using a CNC milling machine to ensure the verticality of the reference surface. At the same time, it is also necessary to ensure that the dimensional accuracy of the strap lug and the reference mounting hole after bonding is consistent. The overall bonding tooling is designed to be responsible for processing the reference hole and also plays a role in the overall bonding.

[0102] Design and implementation of complex stent destruction and identification test plan:

[0103] A 110kg cylinder was used to simulate the engine tank, and a hydraulic cylinder was used to pressurize it to achieve various levels of loading under actual working conditions. The computer controlled the loading step by step, and strain gauges were used to measure the displacement. When the load was added to about 2360kg, the product began to have a gradually increasing cracking sound. When the load was added to 2715kg, the loading system automatically unloaded and the test was terminated. At this time, the corresponding destructive load was about the 22nd level load (about 24.2g), which was much larger than the design load. After careful observation, no obvious visible damage was found on the surface of the product. The experimental results are consistent with the design calculation results.

[0104] Carbon fiber composite tank bracket structure design technology:

[0105] The carbon fiber composite tank bracket of the present invention is a triangular-shaped special-shaped structure with a T-shaped and cross-shaped cross section and a narrow width. Two carbon fiber composite tank brackets carry a tank at the same time. The overall structure of the carbon fiber composite tank bracket is overloaded by 11g in the axial direction and 4g in the lateral direction. The result of preliminary analysis using finite element software is that the maximum displacement of the carbon fiber composite tank bracket is 11.8mm, and the maximum value of the stress failure criterion is 1.3. Through finite element calculation and analysis, the strength of the overall structure of the flexible connection does not meet the requirements, and the bracket structure is damaged. In order to ensure the stability and safety of the bracket structure, it is considered to design a connecting strut between the two brackets. However, it was not adopted due to installation problems. Finally, a steel-clad belt is used to connect the carbon fiber composite tank bracket and the tank, and the prestress is increased to improve the integrity of the tank and the bracket when bearing loads. When loaded, each component is loaded as a whole, and the strength and stiffness are calculated to meet the design requirements.

[0106] Carbon fiber composite tank bracket simulation analysis technology:

[0107] Through analysis and calculation, the maximum deformation of the composite tank bracket is 0.635mm. The tank bracket is checked by Cai-Wu criterion, and the maximum value is 0.493. The structural strength and stiffness of the composite tank bracket meet the design requirements. Through real and effective finite element simulation calculation, time and cost are saved for the development of the composite tank bracket project. The composite tank bracket was tested, and the calculated failure load result was 22.3g, and the failure load test result was 24g, with a deviation of 7%. The analysis predicted the failure position is the same as the test. The comparison of the calculation results and the test results is shown in Table 2.

[0108] Table 2 Comparison of calculation results and test results

[0109]

[0110]

Claims

1. A carbon fiber composite material tank bracket, characterized in that: The invention comprises a tank support shell and two metal ears (5). The tank support shell comprises a left rib plate (1), a right rib plate (2), a web plate (3) and a reinforcing plate (4). The web plate (3) is arranged horizontally. A circular arc groove (31) matching the outer circle of the tank is arranged in the middle of the upper end surface of the web plate (3). A metal ear (5) is arranged on both sides of the upper end surface of the web plate (3). A steel belt connecting hole (51) is provided on the metal ear (5). The right rib plate (2) is arranged vertically at the lower right side of the web plate (3). The upper end of the right rib plate (2) is connected to the right end of the web plate (3). The left rib plate (1) is arranged obliquely between the web plate (3) and the right rib plate (2). The upper end of the left rib plate (1) is connected to the left end of the web plate (3). The lower end of the plate (1) is connected to the lower end of the right rib plate (2); the left rib plate (1), the right rib plate (2) and the web plate (3) are connected end to end in sequence to form a tank support frame; the tank support frame is a hollow right-angled triangle structure; the reinforcing plate (4) is obliquely arranged inside the tank support frame; the lower end of the reinforcing plate (4) is connected to the middle of the left rib plate (1); the upper end of the reinforcing plate (4) is connected to the intersection of the web plate (3) and the right rib plate (2); the outer sides of the left rib plate (1), the right rib plate (2) and the web plate (3) are all provided with wing plates extending to both ends at the same time; the left rib plate (1), the right rib plate (2), the web plate (3) and the reinforcing plate (4) are an integrated structure; and the tank support shell is a carbon fiber reinforced epoxy resin-based composite shell.

2. A carbon fiber composite material tank bracket according to claim 1, characterized in that: The included angle between the reinforcing plate (4) and the upper end surface of the web (3) is α, α=40°.

3. A carbon fiber composite material tank bracket according to claim 2, characterized in that: The metal lug (5) is made of titanium alloy TC4 material, the carbon fiber is made of M40 material, and the resin is made of epoxy resin material.

4. A carbon fiber composite material tank bracket according to claim 3, characterized in that: The length of the tank support shell is L, L=435mm, and the height of the tank support shell is H, H=448mm.

5. A carbon fiber composite material tank bracket according to claim 4, characterized in that: It also includes four first bolts. Two first screw holes 32 are respectively provided on both sides of the upper end surface of the web (3) in the vertical direction. Each metal support ear (5) is connected to the web (3) through two first bolts.

6. A carbon fiber composite material tank bracket according to claim 5, characterized in that: The lower end surface of the metal support ear (5) is fixedly connected to the upper end surface of the web (3) by means of adhesive bonding, and the adhesive is J-133 adhesive.

7. A carbon fiber composite material tank bracket according to claim 6, characterized in that: It also includes four second bolts. Two second screw holes 33 are respectively arranged at the upper parts of both ends of the web (3). The two ends of the web (3) are respectively connected to the external compartment through the two second bolts.

8. A method for manufacturing a carbon fiber composite material tank bracket according to any one of claims 1 to 7, characterized in that: The method is implemented by the following steps: Step 1: Prepreg re-inspection: Environmental conditions for re-inspection of prepregs: ambient temperature (10-35)℃, relative humidity ≤65%; prepare materials, tools and measuring tools required for re-inspection, test the thickness, carbon fiber volume content, unit area mass, volatile content and gel time of prepregs, re-inspect the epoxy value of epoxy resin in prepregs, and re-inspect the tensile strength and tensile modulus of carbon fiber bundles in prepregs; Step 2: Prepreg cutting: Environmental conditions for prepreg cutting: ambient temperature (15-35)℃, humidity ≤65%; take the prepreg out of the freezer and place it at room temperature for 2-4 hours before use. The cutting angle is 0° with the reference line as 0°, 90°, Cut materials at +45° and -45° directions and keep records; Step 3: Preparation of molding mold: Use tools to clean the mold and apply mold release agent on the mold surface; Step 4: Prepreg laying; a. Divide the tank support shell into four small pieces, namely the left rib plate (1), the right rib plate (2), the web plate (3) and the reinforcing plate (4). Lay the four small surfaces separately, and define the direction parallel to the frame as 0° and the direction perpendicular to the frame as 90°. First, lay the left rib plate (1), with the short straight side as 0° for the laying angle, and lay it in the directions of 0°, 90°, +45°, -45°, 0°, and 90°, and keep a record; with the long straight side as 0° for the laying angle, and lay it in the directions of 0°, 90°, +45°, -45°, 0°, and 90°, and keep a record; with the curved side as 0° for the laying angle, and lay it in the directions of 0°, 90°, 0°, 90°, and keep a record; Then, the right rib plate (2) is laid, and the specific steps of laying the right rib plate (2) are the same as those of laying the left rib plate (1); Then, the web plate (3) is laid, and the specific steps of laying the web plate (3) are the same as those of laying the left rib plate (1); Finally, the reinforcing plate (4) is laid. The specific steps of laying the reinforcing plate (4) are the same as those of laying the left rib plate (1). At this point, the individual laying of the left rib plate (1), the right rib plate (2), the web plate (3) and the reinforcing plate (4) has been completed; b. Combine all small pieces and then lay the reinforcement area ply; c. After paving the reinforcement area, pre-press, then lay the combined small pieces and then lay the layers; Step 5: Mold closing: Use bolt pressure mold closing, ensure the front and rear positions of the mold are aligned when closing the mold, tighten the pressure bolts symmetrically when closing the mold, so as to close the upper and lower molds. After closing the mold, put the mold into the curing oven, heat it at 100℃ in the curing oven for 3 hours, then take out the product, and the mold gap is less than 0.1mm when the mold is in place; Step 6: Curing: According to the solidification system (100±5)℃ / (1±10min)h→(150±5)℃ / (2±10min)h→(170±5)℃ / (4±10min)h for curing, increase the temperature at a uniform rate, and save the curing curve data; Step 7: Demolding and trimming: d. Take out the cured product and mold from the curing oven, cool it naturally to room temperature and then demould it. e. Remove all bolts, remove the upper and lower molds and the left and right molds, remove the blocks inside the cover in order, take out the product, and do not scratch the mold surface when demolding; f. Clean the mold and clean the mold surface with copper or aluminum sheets; g. For molds that are not to be used in the short term, apply silicone grease evenly on the molding surface to prevent rust; when storing the molds, place the male and female molds in a closed position and pay attention to dust and moisture prevention; h. Use a file or sandpaper to trim the rough edges of the product; At this point, the manufacture of the carbon fiber composite tank bracket has been completed.

9. The method according to claim 8, characterized in that: The prepreg described in step 1 is a carbon fiber hot-melt prepreg, with a single layer thickness of 0.15 mm, a carbon fiber volume content of (58 ± 2)%, and a unit area mass of (305 ± 5) g / m 2 , volatile content ≤2%, gel time (150℃) (40±5)min; the epoxy value of the epoxy resin in the carbon fiber hot-melt prepreg is ≥0.85; the tensile strength of the carbon fiber bundle in the carbon fiber hot-melt prepreg is ≥3000MPa, and the tensile modulus is ≥330Gpa.

10. The method according to claim 9, characterized in that: The tool used for mold cleaning described in step three is a copper sheet or an aluminum sheet. After the mold is cleaned and there is no residual impurities on the working surface, wipe the mold surface with industrial-grade acetone, and then evenly apply a layer of release agent with a flat brush. After it is completely dried, set it aside.

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