Three-dimensional curved fiber reinforced composite shell and method of manufacturing the same

Abstract

The present application belongs to the technical field of fiber reinforced composite material forming, and discloses a three-dimensional curved surface fiber reinforced composite material shell and a manufacturing method thereof.The overall shape of the three-dimensional curved surface fiber reinforced composite material shell is one or more of a head or a joint part of a human body covering structure and a device outer covering structure.The manufacturing method comprises the following steps: first, dividing a two-dimensional woven sleeve into a fixed section, a free section and an axial sliding section along the axial direction, arranging an uninflated air bag in the free section, inflating the air bag backward, driving the free section to deform mainly in the form of in-plane shear deformation, then releasing the air bag pressure, separating the deformed free section from the two-dimensional woven sleeve, processing the three-dimensional curved surface woven preform, then laminating and laying the three-dimensional curved surface woven preform on a three-dimensional curved surface rigid mold and seamlessly adhering the three-dimensional curved surface woven preform to the three-dimensional curved surface rigid mold, and curing and forming, thereby obtaining the three-dimensional curved surface fiber reinforced composite material shell.The present application takes into account high protection performance and light weight, and can avoid cutting openings, thereby ensuring fiber continuity and overall protection performance.

Description

Technical Field

[0001] This invention belongs to the field of fiber-reinforced composite material molding technology, and relates to a three-dimensional curved surface fiber-reinforced composite material shell and its manufacturing method. Background Technology

[0002] Helmets, safety helmets, and various three-dimensional curved protective shells are widely used in military, police, construction, transportation, and other fields. Their core function is to protect the human head, joints, and other critical parts of the body from injuries caused by projectiles, falling objects, and collisions.

[0003] Traditional protective shells are mostly made of metal sheets or thermoplastic injection molding. Although the technology is mature, they tend to be too heavy for the same level of protection, making it difficult to meet the dual requirements of lightweight and high protective performance. Therefore, fiber-reinforced composite shells made of high-performance continuous fibers and matrix materials have become the focus of current research and application in related fields.

[0004] Currently, the manufacturing of composite helmets and similar three-dimensional shells mainly uses planar woven fabrics, unidirectional fabrics, or multiaxial fabrics as reinforcements. The molding process involves first cutting the material into helmet-shaped pieces, then layering them in a metal mold that matches the shell shape, followed by impregnation with the matrix material and molding curing. However, helmet shells are complex spatial curved surfaces with double curvature. The in-plane shear deformation capacity of two-dimensional fabrics is limited. When laid directly, areas with large curvature changes are prone to wrinkles, bulges, and other defects. To eliminate these defects, adjustments are usually made by cutting openings and overlapping seams. However, this leads to fiber breaks and interruptions in fiber direction, weakening the local protective capacity of the shell and disrupting the overall load-bearing continuity. At the same time, cutting generates a large amount of waste material, and the manual laying and alignment of the pieces is labor-intensive, significantly limiting production efficiency.

[0005] To improve the molding quality of complex three-dimensional curved composite material shells, existing technologies propose an internal pressure expansion molding method (also known as pressure airbag molding). The core principle of this method is as follows: within a rigid mold cavity with the target three-dimensional shape, a fiber-reinforced composite material layup or fiber preform is placed between an inflatable flexible inner mold (such as a rubber airbag) and a rigid outer mold. By inflating and pressurizing the flexible inner mold, the fiber preform adheres to the inner wall of the rigid mold cavity under internal pressure. Then, heating completes the curing process, resulting in a composite material shell that matches the shape of the mold cavity in one step. For example, the patent with authorization announcement number EP2289360A2 proposes to use an inflatable airbag in conjunction with a rigid master mold. The composite material layup is pressed into the mold cavity surface and cured by the inflation pressure. The final three-dimensional shape of the shell is defined by the rigid mold cavity. The internal pressure of the airbag mainly plays the role of layup bonding and compaction. The patent application with application publication number US5366684A and the patent with authorization announcement number CN111391369B both use an inflatable inner mold to apply internal pressure to the composite material layup in the mold cavity, pushing it to fit the mold surface and complete the curing.

[0006] In summary, existing internal pressure expansion molding methods generally use rigid mold cavities as molding boundaries, and the core function of internal pressure is "compression, bonding and densification". The reinforcements used are mostly planar cut pieces, prepregs, or near-planar fiber preforms, rather than actively forming the target three-dimensional curved surface through the deformation of the fiber preform's own structure.

[0007] However, significant limitations still exist when applying the internal pressure expansion molding method to complex three-dimensional curved surface composite material shells:

[0008] Firstly, the fiber preform uses a rigid mold cavity as its forming boundary and is constrained by the mold cavity contour and trimming line position. During the expansion of the inner rubber mold, it passively adheres to the three-dimensional cavity surface. Due to the different degrees of curvature change in different areas of the shell, the yarns at each position need to withstand different degrees of tension or compression during the bonding process of the fiber preform. This can easily lead to a redistribution of local yarn density, resulting in deviations in areal density and thickness in different areas, affecting the consistency of the overall performance of the shell.

[0009] Secondly, the fiber preform is directly pressed into the rigid mold cavity under internal pressure. The radius of curvature and the laying path are different at different positions. When using flat cut pieces or pasted fiber preforms for laying, it is difficult to keep the tension and reorientation state of the yarn in the forming process consistent. This can easily lead to uneven distribution of yarn tension in different areas of the shell, causing local stiffness, strength and other mechanical properties to be discrete.

[0010] Third, this method often involves laying flat fabric pieces or near-flat prepreg layers on the inner surface of complex three-dimensional cavities such as helmets. However, two-dimensional flat fabrics and hyperbolic three-dimensional surfaces have geometric compatibility defects. In areas with large curvature changes, the fabric is prone to wrinkles, overlaps, or large tensile deformations during the molding process. Under the combined effect of rigid mold constraints and internal pressure, these situations increase the risk of yarn bending, wear, or localized damage, adversely affecting the structural integrity and protective performance of the shell.

[0011] Therefore, the need for a three-dimensional curved surface fiber-reinforced composite material shell and its manufacturing method to solve the above problems is of great significance. Summary of the Invention

[0012] The purpose of this invention is to solve the problems existing in the prior art and provide a three-dimensional curved surface fiber reinforced composite material shell and its manufacturing method, which is particularly suitable for the manufacture of protective helmet shells, construction safety helmets, motorcycle helmets, bicycle helmets and other three-dimensional curved surface protective components.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell includes the following steps:

[0015] (a) Divide the two-dimensional braided sleeve (i.e., the sleeve woven on the cylindrical surface) into a fixed section, a free section and an axial sliding section connected in sequence along the axial direction. All degrees of freedom of the fixed section are constrained, all degrees of freedom of the free section are not constrained, and only the radial degree of freedom of the axial sliding section is constrained. An uninflated airbag is arranged in the free section.

[0016] Two-dimensional braided sleeves are formed by weaving yarns at a braiding angle of 20°-70°. The yarns are non-metallic continuous fibers, and the braiding units are rhomboid. The bending stiffness of the two-dimensional braided sleeve is not less than 1×10⁻⁶. -5 N·m and not higher than 5×10 -3 N·m, the wall thickness of the two-dimensional braided sleeve is 0.1-2mm;

[0017] (b) Inflate the airbag to make it expand, causing the free section to undergo deformation mainly by in-plane shear deformation. During this process, the fixed section limits the position of the two-dimensional woven sleeve in the forming process, and the axial sliding section continuously provides the free section with the available fabric length. The deformation is controlled to be mainly by in-plane shear deformation, which is conducive to forming a uniform three-dimensional curved surface.

[0018] (c) Release the airbag pressure, separate the deformed free section from the two-dimensional braided sleeve, process it to obtain a three-dimensional curved surface braided preform, then stack the three-dimensional curved surface braided preform on the three-dimensional curved surface rigid mold and seamlessly fit it with the three-dimensional curved surface rigid mold, and then solidify it to obtain a three-dimensional curved surface fiber reinforced composite material shell.

[0019] Processing refers to longitudinal cutting along the axial direction of the deformed free segment to obtain a single-layer three-dimensional curved surface woven preform; or processing refers to folding inward or outward along the radial direction of the deformed free segment without cutting to obtain a double-layer three-dimensional curved surface woven preform.

[0020] The laminated structure contains a matrix material during curing and molding, which is one or more of metal, resin, ceramic and carbon.

[0021] This invention controls the two-dimensional braided sleeve to be formed by weaving yarn at a braiding angle of 20°-70°. The yarn is a non-metallic continuous fiber, and the braiding unit is rhomboid. The bending stiffness of the two-dimensional braided sleeve is not less than 1×10⁻⁶. -5 N·m and not higher than 5×10 - 3 N·m, the wall thickness of the two-dimensional braided sleeve is 0.1-2mm. This allows the free section to undergo deformation mainly by in-plane shear deformation when the airbag expands, rather than relying on the stretching deformation of the yarn, and also avoids severe wrinkles.

[0022] If the weaving angle is too small (<20°), the yarn is almost parallel to the axis of the two-dimensional weaving sleeve, and the degree of freedom of in-plane shear deformation is very small. When the air bladder expands, the free section mainly relies on the yarn stretching to deform into a three-dimensional curved surface, which can easily lead to excessive fiber tensile strain, resulting in decreased strength or even filament breakage. At the same time, the amount of stretching varies greatly in different areas, and the surface density is uneven.

[0023] If the weaving angle is too large (>70°), the yarn will almost loop in a circle, resulting in insufficient axial stiffness. Under the action of the air bladder, the free section tends to bulge as a whole rather than form a regular three-dimensional curved surface. Large circumferential compression and wrinkles will occur in local areas, making it impossible to achieve smooth curved surface forming mainly by in-plane shear deformation.

[0024] If the yarn is a continuous metal fiber, the continuous metal fiber has a high modulus and high density, and its bending stiffness is much greater than that of non-metallic continuous fibers such as aramid and UHMWPE. The free section is difficult to undergo sufficient in-plane shear deformation under limited internal pressure. It can only adapt to the curved surface by stretching the yarn or local buckling, which is prone to breakage or buckling instability and is not conducive to lightweighting.

[0025] The rhomboid unit consists of two sets of symmetrical yarns, which facilitates in-plane shear deformation through intersection rotation and relative yarn sliding, converting it into a three-dimensional curved surface while keeping the yarn length essentially unchanged. If an approximately rectangular or asymmetrical unit is used, a portion of the yarns will bear the main tensile or compressive deformation, resulting in insufficient freedom of in-plane shear deformation. This can lead to localized strain concentration, wrinkling, or creases, making it difficult to achieve the uniform curved surface forming required by this invention.

[0026] If the bending stiffness is too large (>5×10) -3 The free section, under internal pressure, can only rely on yarn stretching or local zigzag bending deformation, making it difficult to achieve the uniform curved surface forming required by this invention.

[0027] The bending stiffness of the two-dimensional braided sleeve is not less than 1×10. -5 N·m can avoid the difficulty in controlling the surface shape due to local instability and wrinkling of the free segment during expansion.

[0028] The wall thickness of the two-dimensional braided sleeve is 0.1-2mm. This avoids the problem that the air bladder needs extremely high internal pressure to bulge out the free section due to excessive wall thickness, which is difficult to achieve in actual manufacturing. It also avoids the problem that the free section will collapse locally and have fine wrinkles when the air bladder just begins to expand due to insufficient wall thickness, making it difficult to form a macroscopically smooth three-dimensional curved surface.

[0029] This invention solves the problems existing in the prior art of internal pressure expansion molding methods for the following reasons:

[0030] In this invention, after the airbag is inflated, the free section bulges outward, and the bulging area does not adhere to the rigid mold cavity inner wall point by point. When the airbag expands, the free section mainly relies on in-plane shear deformation to transition from a cylindrical surface to a spherical cap or other three-dimensional curved surfaces, basically maintaining the fiber length, with small and uniform changes in surface density. This is beneficial for obtaining three-dimensional curved woven preforms with more uniform surface density and more consistent performance.

[0031] This invention uses a two-dimensional braided sleeve as a reinforcement. During the bulging process, the deformation is mainly controlled by in-plane shear deformation, which can ensure that the length of each yarn remains basically unchanged. The tension caused by the internal pressure can be redistributed in a self-balancing manner within the braided structure, and the yarn tension state tends to be uniform. The overall mechanical properties of the three-dimensional curved surface braided preform after molding are more consistent.

[0032] This invention employs a two-step approach: first, a three-dimensional curved woven prefabricated sheet is obtained by locally bulging a two-dimensional woven sleeve, making the prefabricated sheet itself closely approximate the local curvature of the target shell; then, multiple prefabricated sheets are layered and cured onto a three-dimensional curved rigid mold of a helmet or other shell. In other words, this invention first obtains a three-dimensional curved woven prefabricated sheet adapted to the target surface, and then uses it to match the three-dimensional curved rigid mold, thus mitigating the wrinkles and yarn damage problems caused by directly "hard-fitting" two-dimensional fabric onto a complex three-dimensional surface.

[0033] In summary, compared with the existing internal pressure expansion molding method, the present invention obtains a three-dimensional curved surface woven preform by locally internally bulging a two-dimensional woven sleeve and then processing it, and then stacking and curing it into a shell. This not only reduces the dependence on complex rigid mold cavities, but also makes the fiber surface density and yarn tension distribution of the three-dimensional curved surface fiber reinforced composite material shell more uniform, with better structural performance consistency. The process is relatively simplified, which is conducive to ensuring molding quality and improving process flexibility.

[0034] As a preferred technical solution:

[0035] The manufacturing method of a three-dimensional curved fiber-reinforced composite material shell as described above, wherein the two-dimensional braided sleeve is formed by weaving yarn at a braiding angle of 40°-50°.

[0036] The manufacturing method of a three-dimensional curved fiber-reinforced composite material shell as described above, wherein the non-metallic continuous fiber is at least one of aramid fiber, carbon fiber, glass fiber, ultra-high molecular weight polyethylene fiber, polyacrylonitrile-based fiber, PBO fiber, PBI fiber, liquid crystal polymer fiber, basalt fiber and quartz fiber; the non-metallic continuous fiber is composed of multiple monofilaments, and the diameter of the monofilament is 3-30μm.

[0037] The manufacturing method of the three-dimensional curved fiber-reinforced composite shell described above uses a single filament with a diameter of 7-17 μm.

[0038] In the manufacturing method of a three-dimensional curved fiber-reinforced composite shell as described above, in step (a), all degrees of freedom of the fixed segment are constrained by applying axial, radial and rotational limiting or clamping actions to the fixed segment;

[0039] The axial sliding section is constrained only in the radial degree of freedom by fitting the axial sliding section onto the inner mold and then fitting the outer mold onto the axial sliding section. The inner mold is cylindrical or tubular, and its outer diameter is slightly smaller than the inner diameter of the axial sliding section (difference of 1-1.8 mm). The outer mold is tubular, and its inner diameter is larger than the outer diameter of the axial sliding section but smaller than the size that allows the axial sliding section to undergo radial free deformation, so that the axial sliding section is confined between the inner and outer molds and can slide relative to each other in the axial direction.

[0040] In the manufacturing method of the three-dimensional curved fiber-reinforced composite shell described above, in step (b), the outer diameter of the free segment before deformation is D0, where D0 is 50-500 mm, and the maximum outer diameter of the free segment after deformation is D... b 1.05≤D b / D0≤2.00; the airbag is a spherical airbag, an ellipsoidal airbag, or a spindle-shaped airbag;

[0041] At least 10 test points were taken on the deformed free segment for testing, and the maximum relative deviation of the areal density was measured. Maximum relative deviation of thickness not exceeding 10% No more than 15%, and The calculation formula is as follows:

[0042] ;

[0043] ;

[0044] In the formula, , , These correspond to the maximum, minimum, and average areal density of the test points, respectively. , , These correspond to the maximum thickness, minimum thickness, and average thickness of the test point, respectively.

[0045] At least five specimens were taken from the deformed free section and subjected to in-plane tensile and / or bending tests, with the coefficient of variation of the ultimate strength not exceeding 15%.

[0046] The outer surface of the deformed free section is smooth and continuous under natural light or equivalent lighting conditions at an observation distance of 0.5-1.0m, without any wrinkles or creases visible to the naked eye.

[0047] In the manufacturing method of a three-dimensional curved fiber-reinforced composite shell as described above, in step (c), before separating the deformed free segment from the two-dimensional braided sleeve, a matrix material is coated or impregnated on the outer surface of the deformed free segment so that the laminated structure contains the matrix material during curing.

[0048] Alternatively, during the layering process, a matrix material can be introduced between the layers so that the laminated structure contains a matrix material when it is cured and molded.

[0049] When the matrix material is resin, the matrix material can also be introduced before and after the stack is laid up by resin transfer molding, vacuum-assisted resin introduction, or in-situ melt impregnation of thermoplastic matrix, so that the stack structure contains matrix material when cured.

[0050] In the manufacturing method of the three-dimensional curved fiber reinforced composite material shell described above, in step (c), the volume fraction of fiber in the three-dimensional curved fiber reinforced composite material shell is 70%-99%; the curing conditions depend on the situation. When the matrix material is resin, heating and / or pressurization can be used. When the resin is thermosetting resin, the heating temperature is 80-220℃. When the resin is thermoplastic resin, the heating temperature is 10-80℃ higher than the melting point of the resin. The pressurization pressure is 0.2-10MPa, and the holding time after heating and / or pressurization is 0.5-6h.

[0051] The present invention also provides a three-dimensional curved surface fiber-reinforced composite material shell, which is manufactured by the manufacturing method of the three-dimensional curved surface fiber-reinforced composite material shell described above.

[0052] As a preferred technical solution:

[0053] As described above, the three-dimensional curved fiber-reinforced composite material shell has an overall shape that is either a head or human joint covering structure or an equipment outer covering structure, or a combination of both. Specifically, the shell can be applied to at least one of the following types: protective helmet shells (especially military or police bulletproof helmet shells), and head protection equipment such as construction safety helmet shells, motorcycle helmet shells, and bicycle helmet shells, or human joint protection equipment such as protective knee pad shells, protective elbow pad shells, and protective shoulder pad shells, or industrial equipment protective covers. In addition, the three-dimensional curved structure of the shell must include at least one section of a spherical or ellipsoidal curved surface region.

[0054] Beneficial effects:

[0055] (1) This invention utilizes two-dimensional circular tube braided material in conjunction with simple cylindrical inner and outer molds and inflatable airbags to directly obtain three-dimensional braided prefabricated parts that are close to the target curved surface without the need for special spherical rigid molds. These parts are then laminated and solidified into three-dimensional curved fiber reinforced composite material shells. This invention is particularly suitable for the preparation of protective helmet shells and other three-dimensional curved protective components, thereby shortening the process flow, improving the integrity and protective performance of the shell, and reducing material waste and manufacturing costs.

[0056] (2) The three-dimensional curved fiber-reinforced composite shell prepared by the present invention has both high protective performance and lightweight, and can avoid cutting openings, ensuring fiber continuity and overall protective performance. At the same time, the present invention is applicable to a wide range of materials and has a rich range of application scenarios.

[0057] (3) The structure and process of the present invention are more simplified, no complex spherical metal mold is required, and conformal three-dimensional curved surface preforms can be obtained while maintaining fiber continuity and are easy to laminate. The structure design has a high degree of freedom and is easy to optimize performance.

[0058] (4) The present invention overcomes the problems of wrinkles, extensive cutting and splicing, poor fiber continuity, and the need for precision spherical metal molds and complex equipment in the molding of complex three-dimensional curved shells by two-dimensional planar fabrics in the prior art. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the process flow for the three-dimensional curved surface woven preform of the present invention;

[0060] Figure 2 This is a physical image of the three-dimensional curved surface woven preform of the present invention;

[0061] In the figure, 1-inner mold, 2-outer mold, 3-two-dimensional braided sleeve, 4-airbag inlet tube, 5-airbag, 6-base material, 7-head end fixing device, 8-free section. Detailed Implementation

[0062] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0063] The manufacturers and brands mentioned in the following embodiments are merely examples. The core of this invention lies in the technical solution itself, and it is not intended to limit specific manufacturers or brands. Products from other manufacturers and brands that meet the technical requirements and performance indicators specified in this invention can also meet the application requirements of this invention and are all feasible choices.

[0064] The maximum relative deviation of areal density in the following embodiments Maximum relative deviation of thickness The calculation formula is as follows:

[0065] ;

[0066] ;

[0067] In the formula, , , These correspond to the maximum, minimum, and average areal density of the test points, respectively. , , These correspond to the maximum thickness, minimum thickness, and average thickness of the test point, respectively.

[0068] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0069] The coefficient of variation (CV) of the ultimate tensile strength in in-plane tensile test: After the deformed free section is cut open axially and laid flat, long strip specimens are taken in both the axial and circumferential directions. The width of the long strip specimen is greater than the target width. Then, the yarn is removed one by one from both sides of the long strip specimen by a yarn-pulling method to make the width of the long strip specimen reach 50 mm, so as to reduce yarn breakage and edge slippage caused by cutting. Then, end reinforcement plates are attached to both ends of the long strip specimen and clamped. Tensile test is performed according to ASTM D5035, with a gauge length of 100 mm and a loading rate of 100 mm / min. Five long strip specimens are taken in each direction. The breaking strength and the load (or equivalent stress) at the specified strain are recorded. Then, the coefficient of variation (CV) of the long strip specimen in the axial and circumferential directions are calculated based on the data obtained in each direction. Finally, the larger value is the coefficient of variation (CV) of the ultimate tensile strength in in-plane tensile test. The calculation formula is: CV = σ / μ × 100%, where σ represents the standard deviation of the test results of the five specimens and μ represents the arithmetic mean of the test results of the five specimens.

[0070] The coefficient of variation of the ultimate strength in the bending test: Following the cantilever method in ASTM D1388, "Standard Test Method for Bending Stiffness of Fabrics," the deformed free section is first axially cut and laid flat. Rectangular specimens (200mm × 25mm) are then cut along both the axial and circumferential directions. The cantilever extension length C of the rectangular specimen at the specified bending angle (41.5°) is measured. The bending length B is then calculated (using the formula B = C / 2). Finally, the bending stiffness G is calculated (using the formula G = W·B). 3 In the formula, W is the mass per unit area of ​​the sample. After testing 5 samples in each direction, the average is taken. Then, based on the data obtained in each direction, the coefficient of variation CV of the rectangular sample in the axial direction and the circumferential direction are calculated respectively. Finally, the larger value is taken as the coefficient of variation of the ultimate strength of the bending test. The calculation formula is: CV=σ / μ×100%, where σ represents the standard deviation of the test results of 5 samples, and μ represents the arithmetic mean of the test results of 5 samples.

[0071] Bending stiffness: The bending stiffness of the specimen was measured using the cantilever method in ASTM D1388, "Standard Test Method for Bending Stiffness of Fabrics," and calculated as G=W·B. 3 The calculation is performed, where W is the mass per unit area of ​​the sample and B is the bending length (B=C / 2), and the conversion is performed according to the unit system used (the unit is N·m).

[0072] Ballistic limit V50 and maximum relative deviation ΔV50: The ballistic limit V50 of each region of the sample was determined according to GB / T 44951-2024 "Test Method for V50 of Ballistic Materials and Products". During the test, hit points were set in each region, with a minimum distance of 50mm between adjacent hit points to avoid mutual interference. The maximum relative deviation ΔV50 was then calculated based on the measured results. The simulated projectile weight was 1.1g, and the evaluation method was six shots. The formula for calculating the maximum relative deviation ΔV50 is: ΔV50 = |V50| max -V50 min | / V50 avg ×100%, where V50 max V50 represents the maximum value of the ballistic limit V50 in each region. min V50 is the minimum value of the ballistic limit in each region. avg This represents the average value of the ballistic limit V50 for each region.

[0073] Example 1

[0074] A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell, comprising the following steps:

[0075] (1) A aramid fiber (specification 1100dtex, composed of 1000 monofilaments, monofilament diameter 12μm) is braided on a horizontal two-dimensional circular tube braiding machine to obtain a two-dimensional braided sleeve; wherein, the braiding angle of the two-dimensional braided sleeve is 40° and the braiding unit is rhomboid;

[0076] The resulting two-dimensional braided sleeve has a wall thickness of 0.8 mm, an inner diameter of 298.4 mm, and a bending stiffness of 8 × 10⁻⁶. -4 N·m;

[0077] (2) such as Figure 1 As shown, the two-dimensional braided sleeve 3 is divided axially into a fixed section, a free section 8, and an axial sliding section connected in sequence. First, the axial sliding section is fitted onto the inner mold 1, and then the outer mold 2 is fitted onto the axial sliding section to constrain the radial degree of freedom of the axial sliding section. Then, an uninflated airbag 5 (the airbag 5 is spherical, made of silicone rubber, with a wall thickness of 1.5mm, a hardness of Shore A40, and an uninflated outer diameter of 180mm) is arranged in the free section 8 with an outer diameter D0 of 300mm. Then, the fixed section is limited in axial, radial, and rotational directions by the three-jaw chuck, end face pressure plate, and anti-rotation pin of the head-end fixing device 7, so that all degrees of freedom of the fixed section are constrained and the airbag inlet pipe 4 is sealed. Among them, the inner mold 1 is cylindrical with an outer diameter of 297mm; the outer mold 2 is tubular with an inner diameter of 300.8mm.

[0078] (3) such as Figure 1As shown, the relative positions of the inner mold 1 and the outer mold 2 are adjusted so that the woven fabric area near the airbag 5 is no longer simultaneously constrained by the inner and outer molds. Then, the airbag 5 is inflated, causing it to expand and drive the free segment 8 to undergo deformation mainly characterized by in-plane shear deformation. The maximum outer diameter D of the deformed free segment 8 is... b Satisfy D b / D0=1.5;

[0079] Twelve test points were selected on the deformed free segment 8 for testing, and the maximum relative deviation of the surface density was measured. It is 6.5%, and the thickness is... The maximum relative deviation was 9.8%;

[0080] Five specimens were taken from the deformed free segment 8 for in-plane tensile and bending tests. The coefficient of variation of the ultimate strength in the in-plane tensile test was 11%, and the coefficient of variation of the ultimate strength in the bending test was 9%.

[0081] The outer surface of the deformed free segment 8 is smooth and continuous under natural light at an observation distance of 0.8m, with no wrinkles or creases visible to the naked eye.

[0082] (4) such as Figure 1 As shown, while the airbag 5 is under pressure, a base material 6 (obtained by degassing a mixture of epoxy resin (manufacturer Huntsman Group, brand name Araldite LY 1564) and curing agent (manufacturer Huntsman Group, brand name Aradur 3416) with a mass ratio of 1:0.37) is applied to the outer surface of the expansion area by brushing. This allows the base material 6 to penetrate into the gaps between the woven fibers. Then, the system is kept at 40°C for 20 minutes to increase the viscosity / enter a semi-gel state, so as to maintain the three-dimensional curved shape during the release of pressure from the airbag 5 and subsequent handling and cutting processes.

[0083] (5) Release the airbag pressure, separate the deformed free section from the two-dimensional braided sleeve, and cut longitudinally along the axial direction of the deformed free section to obtain a single-layer three-dimensional curved surface braided preform. Then, stack the single-layer three-dimensional curved surface braided preform on the three-dimensional curved surface rigid mold and seamlessly fit it with the three-dimensional curved surface rigid mold. After curing, a three-dimensional curved surface fiber reinforced composite material shell is obtained. The number of stacked layers is 20, the curing pressure is 5MPa, the curing temperature is 150℃, the curing time is 4h, and the volume fraction of fiber in the three-dimensional curved surface fiber reinforced composite material shell is 90%.

[0084] The final three-dimensional curved fiber-reinforced composite shell is a protective helmet shell with a mass of 0.9 kg. The ballistic limit V50 of the crown region of the protective helmet shell is 505 m / s, the ballistic limit V50 of the forehead region is 500 m / s, and the ballistic limit V50 of the sidewall region is 495 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 2.00%. It can be seen that the protective helmet shell prepared in this embodiment has better uniformity of performance in each region and better protection. This also proves that the prepared protective helmet shell maintains continuous fiber coverage and improves structural integrity.

[0085] Comparative Example 1

[0086] A method for manufacturing a three-dimensional curved fiber-reinforced composite shell is basically the same as in Example 1, except that the weaving angle in step (1) is 15°.

[0087] The bending stiffness of the obtained two-dimensional braided sleeve is 1.5 × 10⁻⁶. -3 N·m.

[0088] The maximum relative deviation of areal density in step (3) It is 16%, and the thickness is 16%. The maximum relative deviation is 20%;

[0089] The coefficient of variation for the ultimate strength in the in-plane tensile test is 28%, and the coefficient of variation for the ultimate strength in the bending test is 25%.

[0090] The outer surface of the deformed free section shows obvious wrinkles / stretch whitening texture under natural light at 0.8m, and there are localized neck areas caused by yarn tension.

[0091] The final three-dimensional curved fiber-reinforced composite material shell is a protective helmet shell. The ballistic limit V50 of the crown area of ​​the protective helmet shell is 465 m / s, the ballistic limit V50 of the forehead area is 438.51 m / s, and the ballistic limit V50 of the side wall area is 420 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 10.2%.

[0092] Comparative Example 2

[0093] A method for manufacturing a three-dimensional curved fiber-reinforced composite material shell is basically the same as in Example 1, except that the weaving angle in step (1) is 75°.

[0094] The bending stiffness of the obtained two-dimensional braided sleeve is 7.5 × 10⁻⁶. -4 N·m.

[0095] The maximum relative deviation of areal density in step (3) It is 14%, and the thickness is 14%. The maximum relative deviation was 18%;

[0096] The coefficient of variation for the ultimate strength in the in-plane tensile test is 20%, and the coefficient of variation for the ultimate strength in the bending test is 19%.

[0097] The outer surface of the deformed free section shows circumferential bulges and folds under natural light at 0.8m, with localized circumferential compression creases.

[0098] The final three-dimensional curved fiber-reinforced composite material shell is a protective helmet shell. The ballistic limit V50 of the crown area of ​​the protective helmet shell is 460 m / s, the ballistic limit V50 of the forehead area is 430 m / s, and the ballistic limit V50 of the side wall area is 415 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 10.34%.

[0099] Comparative Example 3

[0100] A method for manufacturing a three-dimensional curved fiber-reinforced composite material shell is basically the same as in Example 1, except that the non-metallic continuous fiber in step (1) is replaced with an equal mass of metallic continuous fiber (316L stainless steel continuous fiber filament, manufactured by Danyang Kaifuda Filter Material Co., Ltd., brand name Xikai).

[0101] The bending stiffness of the obtained two-dimensional braided sleeve is 9.0 × 10⁻⁶. -3 N·m.

[0102] The maximum relative deviation of areal density in step (3) It is 16%, and the thickness is 16%. The maximum relative deviation is 20%;

[0103] The coefficient of variation for the ultimate strength in the in-plane tensile test is 22%, and the coefficient of variation for the ultimate strength in the bending test is 24%.

[0104] The outer surface of the deformed free section: Under natural light at 0.8m, there are obvious zigzag creases and local arching, and yarn bending / abrasion marks can be observed in some areas.

[0105] The final three-dimensional curved fiber-reinforced composite material shell is a protective helmet shell. The ballistic limit V50 of the crown area of ​​the protective helmet shell is 430 m / s, the ballistic limit V50 of the forehead area is 414.9 m / s, and the ballistic limit V50 of the side wall area is 395 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 8.47%.

[0106] Comparative Example 4

[0107] A method for manufacturing a three-dimensional curved fiber-reinforced composite material shell is basically the same as in Example 1, except that the braiding unit in step (1) is an unequal-angle quadrilateral unit formed by the intersection of two sets of asymmetric yarns, wherein the absolute values ​​of the braiding angles of the two sets of intersecting yarns relative to the sleeve axis are different (|θ1|≠|θ2|).

[0108] The bending stiffness of the obtained two-dimensional braided sleeve is 8.5 × 10⁻⁶. -4 N·m.

[0109] The maximum relative deviation of areal density in step (3) It is 12%, and the thickness is 12%. The maximum relative deviation was 16%;

[0110] The coefficient of variation for the ultimate strength in the in-plane tensile test is 18%, and the coefficient of variation for the ultimate strength in the bending test is 17%.

[0111] The outer surface of the deformed free section shows local wrinkles / folds under natural light at 0.8m, and exhibits directional wrinkle bands.

[0112] The final three-dimensional curved fiber-reinforced composite shell is a protective helmet shell with a mass of 0.9 kg. The ballistic limit V50 of the crown area of ​​the protective helmet shell is 485 m / s, the ballistic limit V50 of the forehead area is 470 m / s, and the ballistic limit V50 of the side wall area is 455 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 6.38%.

[0113] Comparative Example 5

[0114] A method for manufacturing a three-dimensional curved fiber-reinforced composite material shell is basically the same as in Example 1, except that the wall thickness of the two-dimensional braided sleeve in step (1) is increased from 0.8 mm to 2.5 mm, and the yarn content per unit area is increased.

[0115] The bending stiffness of the obtained two-dimensional braided sleeve is 7.0 × 10⁻⁶. -3 N·m.

[0116] The maximum relative deviation of areal density in step (3) 15%, thickness The maximum relative deviation is 20%;

[0117] The coefficient of variation for the ultimate strength in the in-plane tensile test is 19%, and the coefficient of variation for the ultimate strength in the bending test is 21%.

[0118] The outer surface of the deformed free section shows obvious wrinkles and local arching under natural light at 0.8m, resulting in poor surface continuity.

[0119] The final three-dimensional curved fiber-reinforced composite material shell is a protective helmet shell with a mass of 0.9 kg. The ballistic limit V50 of the crown area of ​​the protective helmet shell is 445 m / s, the ballistic limit V50 of the forehead area is 425 m / s, and the ballistic limit V50 of the side wall area is 405 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 9.41%.

[0120] Comparative Examples 1 to 5 changed the weaving angle, yarn type, weaving unit type, and wall thickness of the two-dimensional weaving sleeve compared to Example 1. This caused the deformation in step (3) to no longer be mainly in-plane shear deformation, thus failing to form a uniform three-dimensional curved surface, resulting in deterioration of product performance. The specific analysis is as follows:

[0121] Comparing Comparative Example 1 and Example 1, it can be seen that the free segment prepared in this comparative example exhibits significantly worse uniformity in surface density and thickness during expansion molding, and its strength dispersion is significantly increased. Obvious wrinkles appear on the surface, and the protective performance and performance consistency of the three-dimensional curved fiber-reinforced composite shell prepared using it deteriorate. This is because the braiding angle is too small, causing the yarns to tend to align axially. The in-plane shearing freedom of the braided unit is insufficient, making it difficult for the free segment to achieve curved surface transformation through shearing during airbag expansion. It can only rely on uneven yarn stretching and local slippage to adapt to the curvature, resulting in large differences in stretching in different areas. This leads to uneven distribution of surface density, thickness, and tension, causing appearance defects, decreased mechanical properties, and reduced protective performance consistency. Furthermore, due to the obvious wrinkles, stretching whitening texture, and narrow neck areas that appear during the free segment molding process, the corresponding areas are prone to structural defects such as reduced effective fiber load-bearing capacity, fiber orientation deviation, and abnormal local thickness / surface density after curing. This creates local "weak areas," making the shell more prone to premature local failure during ballistic tests, resulting in a lower ballistic limit and worse spatial distribution uniformity of protective performance.

[0122] Comparing Comparative Example 2 with Example 1, it can be seen that the areal density and thickness uniformity of the free segment obtained in this comparative example are significantly worse, and the strength dispersion is significantly increased. The appearance shows obvious bulging and circumferential wrinkles. The protective performance and performance consistency of the three-dimensional curved fiber-reinforced composite shell prepared using it are worse. This is because when the weaving angle is too large, the yarn tends to loop circumferentially, resulting in insufficient axial load-bearing and constraint capacity. When the airbag inflates, the free segment is more prone to overall bulging and local circumferential compression, thus inducing wrinkles / creases. Simultaneously, the yarn reorientation and slippage are inconsistent in different areas, leading to a redistribution of tension and areal density. Uneven distribution, uneven areal density and thickness, and increased coefficient of variation of ultimate strength indicate that the load-bearing capacity of different areas of the shell fluctuates more and the overall mechanical properties become less consistent. In addition, due to the circumferential bulges, wrinkles and circumferential compression creases that occur during the free section forming process, the corresponding areas are prone to defects such as fiber arching / folding, local thickness abnormalities and resin enrichment after curing. This causes a decrease in the continuity of local effective load-bearing fibers, thus forming "weak areas". This makes the shell more prone to local premature failure in ballistic tests, resulting in a decrease in ballistic limit level and a worsening of the spatial distribution uniformity of protective performance.

[0123] Comparing Comparative Example 3 with Example 1, it can be seen that due to the excessive bending stiffness, the free section in this comparative example is unable to undergo sufficient in-plane shearing during expansion, resulting in a significant reduction in forming quality. The uniformity and consistency indicators both exceed the limits. This is because the high modulus and density of the metal fibers significantly increase the overall bending stiffness of the braided sleeve. Under limited internal pressure, the free section is unable to achieve shearing through intersection rotation and relative slippage. It can only adapt to the curved surface through local buckling or uneven slippage, which easily produces creases, arching, and local damage, thus leading to increased performance dispersion. In addition, due to the presence of zigzag creases, local arching, and yarn buckling / abrasion marks during the forming process of the free section, the above areas are prone to yarn bending damage, reduced effective fiber load-bearing capacity, and abnormal local thickness / areal density after curing. This may be accompanied by local resin enrichment or pore defects, resulting in obvious "weak areas." This makes the shell more prone to local premature failure in ballistic tests, leading to a reduction in ballistic limit level and a decrease in protective performance and spatial consistency.

[0124] Comparing Comparative Example 4 with Example 1, it can be seen that the free segment of this comparative example exhibits significantly worse uniformity in surface density and thickness during expansion molding, and significantly increased strength dispersion. It also shows obvious wrinkles, resulting in poorer protective performance and performance consistency of the three-dimensional curved fiber-reinforced composite shell. This is because when the weaving unit is an asymmetrical unequal-angle quadrilateral unit, the intersection angle and rotational degrees of freedom of the two sets of yarns are inconsistent in different directions, leading to directional bias in in-plane shear deformation. Some areas are more prone to yarn stretching, localized slip concentration, or localized compression wrinkling, resulting in uneven redistribution of surface density / thickness. This makes it difficult for the yarn tension state to self-balance in different areas, ultimately manifesting as increased performance dispersion and increased wrinkles and creases. Furthermore, due to the presence of directional wrinkles and localized folds during molding, structural defects such as fiber orientation bias, abnormal local thickness, and resin enrichment are easily formed in the corresponding areas after curing. This causes inconsistencies between the continuity of the effectively bearing fibers and the force path in different directions, resulting in directional "weak areas." In ballistic tests, these weak areas are more prone to premature local failure, which reduces the ballistic limit level, increases regional differences, and worsens the spatial uniformity of the protective performance.

[0125] Comparing Comparative Example 5 with Example 1 reveals that, due to excessive bending stiffness, the uniformity of surface density and thickness of the free segment during expansion molding significantly deteriorates, and the strength dispersion increases significantly. Obvious wrinkles and localized arching appear on the surface. The protective performance and performance consistency of the three-dimensional curved fiber-reinforced composite shell prepared using this example are worse. This is because the thicker wall of the two-dimensional braided sleeve in this comparison increases the yarn content per unit area, leading to an increase in overall bending stiffness. Under this condition, the free segment cannot achieve shearing through intersection rotation + relative slippage under limited internal pressure, and can only achieve shearing through localized buckling. Uneven slippage to adapt to curved surfaces can easily lead to creases, arching, and localized damage, resulting in increased performance dispersion and decreased shell protection performance and consistency. In addition, due to obvious wrinkles and localized arching during the free section forming process, and the deterioration of surface continuity, structural defects such as fiber arching and stacking, abnormal local thickness, and resin enrichment / porosity are easily formed in the corresponding areas after curing. This reduces the continuity of the effective load-bearing fibers and forms local "weak areas," making the shell more prone to premature local failure in ballistic tests. This further leads to a decrease in ballistic limit level and a deterioration in the spatial uniformity of protective performance.

[0126] Example 2

[0127] A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell, comprising the following steps:

[0128] (1) Glass fiber (specification is 1200dtex, consisting of 750 monofilaments, and the diameter of the monofilament is 9μm) is braided on a horizontal two-dimensional round tube braiding machine to obtain a two-dimensional braided sleeve; wherein, the braiding angle of the two-dimensional braided sleeve is 45° and the braiding unit is rhomboid;

[0129] The resulting two-dimensional braided sleeve has a wall thickness of 2 mm, an inner diameter of 46 mm, and a bending stiffness of 5 × 10⁻⁶. -3 N·m;

[0130] (2) After dividing the two-dimensional braided sleeve into a fixed section, a free section and an axial sliding section connected in sequence along the axial direction, first put the axial sliding section on the inner mold and then put the outer mold on the axial sliding section to constrain the radial degree of freedom of the axial sliding section. Then, arrange an uninflated airbag (the airbag is spindle-shaped, made of silicone rubber, with a wall thickness of 1.5 mm, a hardness of Shore A40, and a maximum outer diameter of 35 mm and a length of 120 mm when uninflated) in the free section with an outer diameter D0 of 50 mm. Then, apply axial, radial and rotational limiting effects to the fixed section through the ring clamp and end face pressure plate to constrain all degrees of freedom of the fixed section and seal the airbag inlet pipe. Among them, the inner mold is a round tube with an outer diameter of 45 mm; the outer mold is a round tube with an inner diameter of 50.6 mm.

[0131] (3) Adjust the relative positions of the inner and outer molds so that the woven fabric area near the airbag is no longer constrained by both the inner and outer molds at the same time. Then inflate the airbag to make it expand, causing the free segment to undergo deformation mainly by in-plane shear deformation. The maximum outer diameter D of the deformed free segment is... b Satisfy D b / D0=1.05;

[0132] Twelve test points were selected on the deformed free section for testing, and the maximum relative deviation of the areal density was measured. It is 9.5%, and the thickness is 9.5%. The maximum relative deviation was 14.5%;

[0133] Five specimens were taken from the deformed free section for in-plane tensile and bending tests. The coefficient of variation of the ultimate strength in the in-plane tensile test was 14%, and the coefficient of variation of the ultimate strength in the bending test was 14%.

[0134] The outer surface of the deformed free section is smooth and continuous under observation distance of 0.8m and equivalent lighting conditions, with no wrinkles or creases visible to the naked eye.

[0135] (4) First, heat the matrix material (low melting point alloy matrix, manufacturer: Rotor Metals, brand name: Field Metals) to 80°C to completely melt it, and hold it at 80°C for 10 min to stabilize the melt flowability; then degas it under vacuum for 5 min at -0.08 MPa to obtain the degassed molten matrix material.

[0136] (5) After releasing the airbag pressure, the deformed free segment is separated from the two-dimensional braided sleeve and folded inward along the radial direction of the deformed free segment to obtain a double-layer three-dimensional curved surface braided preform. The double-layer three-dimensional curved surface braided preform is then stacked and laid on a three-dimensional curved surface rigid mold and seamlessly attached to the three-dimensional curved surface rigid mold. Molten matrix material is introduced between adjacent layers of double-layer three-dimensional curved surface braided preforms. After the stacking is completed, it is solidified to obtain a three-dimensional curved surface fiber-reinforced composite material shell. The number of stacking layers of the double-layer three-dimensional curved surface braided preform is 14, and the areal density of the matrix material introduced each time is 60 g / m³. 2 The curing pressure is 5MPa. The molten alloy is fully impregnated and compacted by applying pressure and holding it at 120℃ for 1 hour. Then, the matrix is ​​cooled to room temperature after pressure is maintained or depressurized to solidify and form the matrix. The curing temperature is 120℃ and the curing time is 1 hour. The volume fraction of fiber in the three-dimensional curved fiber reinforced composite shell is 70%.

[0137] The final three-dimensional curved fiber-reinforced composite shell is an industrial equipment protective cover shell with a mass of 1.35 kg. The ballistic limit V50 of the front protection area of ​​the three-dimensional curved fiber-reinforced composite shell is 568 m / s, the ballistic limit V50 of the side protection area is 560 m / s, and the ballistic limit V50 of the top protection area is 552 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 2.86%. It can be seen that the industrial equipment protective cover shell prepared in this embodiment has better uniformity of performance in each area and better protection. This also proves that the prepared industrial equipment protective cover shell maintains continuous fiber coverage and improves structural integrity.

[0138] Example 3

[0139] A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell, comprising the following steps:

[0140] (1) UHMWPE fiber (specification is 1100dtex, composed of 1200 monofilaments, and the diameter of the monofilament is 11μm) is braided on a horizontal two-dimensional round tube braiding machine to obtain a two-dimensional braided sleeve; wherein, the braiding angle of the two-dimensional braided sleeve is 50° and the braiding unit is rhomboid;

[0141] The resulting two-dimensional braided sleeve has a wall thickness of 0.1 mm, an inner diameter of 499.8 mm, and a bending stiffness of 1 × 10⁻⁶. -5 N·m;

[0142] (2) After dividing the two-dimensional braided sleeve into a fixed section, a free section and an axial sliding section connected in sequence along the axial direction, first put the axial sliding section on the inner mold and then put the outer mold on the axial sliding section so that the radial degree of freedom of the axial sliding section is constrained. Then, an uninflated airbag (the airbag is ellipsoidal in shape, made of silicone rubber, with a wall thickness of 1.5 mm, a hardness of Shore A40, and a major axis of 350 mm and a minor axis of 220 mm when uninflated) is arranged in the free section with an outer diameter D0 of 500 mm. Then, the fixed section is clamped in the axial, radial and rotational directions by the clamping ring and the anti-rotation positioning key so that all degrees of freedom of the fixed section are constrained and the airbag inlet pipe is sealed. Among them, the inner mold is cylindrical with an outer diameter of 498 mm; the outer mold is tubular with an inner diameter of 500.6 mm.

[0143] (3) Adjust the relative positions of the inner and outer molds so that the woven fabric area near the airbag is no longer constrained by both the inner and outer molds at the same time. Then inflate the airbag to make it expand, causing the free segment to undergo deformation mainly by in-plane shear deformation. The maximum outer diameter D of the deformed free segment is... b Satisfy D b / D0=2;

[0144] Twelve test points were selected on the deformed free section for testing, and the maximum relative deviation of the areal density was measured. It is 7.0%, and the thickness is 7.0%. The maximum relative deviation is 10.0%;

[0145] Five specimens were taken from the deformed free section for in-plane tensile and bending tests. The coefficient of variation of the ultimate strength in the in-plane tensile test was 12%, and the coefficient of variation of the ultimate strength in the bending test was 13%.

[0146] The outer surface of the deformed free segment is smooth and continuous under natural light at an observation distance of 1m, with no wrinkles or creases visible to the naked eye.

[0147] (4) Prepare phosphate ceramic slurry;

[0148] Phosphate ceramic powder (industrial grade, manufacturer: Evonik Industries, Germany, brand name: HAP-100) and aluminum dihydrogen phosphate were mixed at a mass ratio of 55:45. Then, an aqueous dispersant solution (a polycarboxylate dispersant, manufacturer: BASF, brand name: Dispex® CX 4345, mass fraction of dispersant: 0.5%) was added and the mixture was dispersed and stirred at high speed for 15 min, followed by vacuum degassing for 5 min to obtain a phosphate ceramic slurry with a solid content of 55%.

[0149] The apparent viscosity of the phosphate ceramic slurry at 25°C is 1200 mPa·s.

[0150] (5) Lamination and curing;

[0151] (5.1) After releasing the airbag pressure and separating the deformed free segment from the two-dimensional braided sleeve, longitudinally cut along the axial direction of the deformed free segment to obtain a single-layer three-dimensional curved surface braided preform. The single-layer three-dimensional curved surface braided preform is then stacked and laid on a three-dimensional curved surface rigid mold and seamlessly bonded to the three-dimensional curved surface rigid mold. The number of layers is 18.

[0152] (5.2) The laminated preform after being laid up is placed in a vacuum bag. First, a vacuum of -0.08 MPa is drawn and maintained for 5 minutes. Then, the slurry inlet is opened to allow the phosphate ceramic slurry to be introduced and impregnated into the laminated preform under the action of pressure difference. After the slurry continuously flows out of the exhaust port, the slurry inlet and exhaust port are sealed. Finally, it is cured and formed in a mold to obtain a three-dimensional curved fiber reinforced composite shell. Among them, the vacuum bag is kept sealed and cured at 150℃ for 3 hours. The volume fraction of fiber in the three-dimensional curved fiber reinforced composite shell is 90%.

[0153] The final three-dimensional curved fiber-reinforced composite shell is a protective helmet shell with a mass of 0.85 kg. The ballistic limit V50 of the crown region of the protective helmet shell is 478 m / s, the ballistic limit V50 of the forehead region is 470 m / s, and the ballistic limit V50 of the sidewall region is 462 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 3.40%. It can be seen that the protective helmet shell prepared in this embodiment has better uniformity of performance in each region and better protection. This also proves that the prepared protective helmet shell maintains continuous fiber coverage and improves structural integrity.

[0154] Example 4

[0155] A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell, comprising the following steps:

[0156] (1) Carbon fiber (specification 12K, composed of 12,000 monofilaments, with a diameter of 7μm) is braided on a horizontal two-dimensional circular tube braiding machine to obtain a two-dimensional braided sleeve; wherein, the braiding angle of the two-dimensional braided sleeve is 45° and the braiding unit is rhomboid;

[0157] The resulting two-dimensional braided sleeve has a wall thickness of 1 mm, an inner diameter of 298 mm, and a bending stiffness of 6 × 10⁻⁶. -4 N·m;

[0158] (2) After dividing the two-dimensional braided sleeve into a fixed section, a free section and an axial sliding section connected in sequence along the axial direction, first put the axial sliding section on the inner mold and then put the outer mold on the axial sliding section so that the radial degree of freedom of the axial sliding section is constrained. Then, an uninflated airbag (the airbag is spherical, made of silicone rubber, with a wall thickness of 1.5 mm, a hardness of Shore A40, and an uninflated outer diameter of 180 mm) is placed in the free section with an outer diameter D0 of 300 mm. Then, the fixed section is clamped in the axial, radial and rotational directions by the wedge clamp and the ring pressure plate so that all the degrees of freedom of the fixed section are constrained and the airbag inlet pipe is sealed. Among them, the inner mold is cylindrical and the outer diameter of the inner mold is 297 mm; the outer mold is tubular and the inner diameter of the outer mold is 301 mm.

[0159] (3) Adjust the relative positions of the inner and outer molds so that the woven fabric area near the airbag is no longer constrained by both the inner and outer molds at the same time. Then inflate the airbag to make it expand, causing the free segment to undergo deformation mainly by in-plane shear deformation. The maximum outer diameter D of the deformed free segment is... b Satisfy D b / D0=1.6;

[0160] Twelve test points were selected on the deformed free section for testing, and the maximum relative deviation of the areal density was measured. It is 6.8%, and the thickness is... The maximum relative deviation was 11.0%;

[0161] Five specimens were taken from the deformed free section for in-plane tensile and bending tests. The coefficient of variation of the ultimate strength in the in-plane tensile test was 10%, and the coefficient of variation of the ultimate strength in the bending test was 11%.

[0162] The outer surface of the deformed free section is smooth and continuous under natural light at an observation distance of 0.8m, with no wrinkles or creases visible to the naked eye.

[0163] (4) While the airbag is under pressure, a base material (phenolic resin precursor, manufactured by Sumitomo Bakelite Co., Ltd. of Japan, grade PR-53195) is applied to the outer surface of the expansion area by brushing. This allows the base material to penetrate into the gaps between the braided fibers. Then, the system is kept at 40°C for 20 minutes to increase the viscosity of the system / to a semi-gel state, so as to maintain the three-dimensional curved shape during the release of airbag pressure and subsequent handling and cutting.

[0164] (5) Release the airbag pressure, separate the deformed free segment from the two-dimensional braided sleeve, and then longitudinally cut along the axial direction of the deformed free segment to obtain the following... Figure 2The single-layer three-dimensional curved surface woven preform shown is then stacked and laid on a three-dimensional curved surface rigid mold, and seamlessly bonded to the three-dimensional curved surface rigid mold. After curing, it is heated to 1000℃ at a heating rate of 4℃ / min and held for 2h under a nitrogen protective atmosphere, and then cooled in the furnace to obtain a three-dimensional curved surface fiber-reinforced composite material shell. The number of layers is 24, the curing pressure is 5MPa, the curing temperature is 180℃, the curing time is 4h, and the fiber volume fraction in the three-dimensional curved surface fiber-reinforced composite material shell is 92%.

[0165] The final three-dimensional curved fiber-reinforced composite material shell is a protective helmet shell with a mass of 0.95 kg. The ballistic limit V50 of the crown region of the protective helmet shell is 518 m / s, the ballistic limit V50 of the forehead region is 510 m / s, and the ballistic limit V50 of the sidewall region is 502 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 3.14%. It can be seen that the protective helmet shell prepared in this embodiment has better uniformity of performance in each region and better protection. This also proves that the prepared protective helmet shell maintains continuous fiber coverage and improves structural integrity.

[0166] Example 5

[0167] A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell, comprising the following steps:

[0168] (1) Aramid fiber (specification 1100dtex, composed of 1000 monofilaments, monofilament diameter 12μm) and carbon fiber (specification 12K, composed of 12000 monofilaments, monofilament diameter 7μm) are braided on a horizontal two-dimensional circular tube braiding machine to obtain aramid fiber two-dimensional braided sleeve and carbon fiber two-dimensional braided sleeve; wherein, the inner diameter of the two-dimensional braided sleeve of the aramid fiber two-dimensional braided sleeve and the two-dimensional braided sleeve of the carbon fiber two-dimensional braided sleeve are both 297mm, the braiding angle is both 45°, and the braiding unit is both rhomboid;

[0169] The resulting two-dimensional braided aramid fiber sleeve has a wall thickness of 1.5 mm, an inner diameter of 297 mm, and a bending stiffness of 1.2 × 10⁻⁶. -3 The carbon fiber two-dimensional braided sleeve has a wall thickness of 1.5 mm, an inner diameter of 297 mm, and a bending stiffness of 0.9 × 10 N·m. -3 N·m;

[0170] (2) After dividing the aramid fiber two-dimensional braided sleeve into a fixed section, a free section and an axial sliding section connected in sequence along the axial direction, the axial sliding section of the aramid fiber two-dimensional braided sleeve is placed on the inner mold I, and the outer mold I is placed on the axial sliding section to constrain the radial degree of freedom of the axial sliding section. Then, an uninflated airbag I (the airbag is spherical, made of silicone rubber, with a wall thickness of 1.5 mm, a hardness of Shore A40, and an uninflated outer diameter of 180 mm) is arranged in the free section with an outer diameter D0 of 300 mm. Then, the fixed section is radially clamped, axially positioned and circumferentially anti-rotation limited by a three-jaw chuck, an end face pressure plate and an anti-rotation pin, respectively, so that all degrees of freedom of the fixed section are constrained and the airbag inlet pipe is sealed. Among them, the inner mold I is a cylindrical tube with an outer diameter of 296 mm; the outer mold I is a cylindrical tube with an inner diameter of 300.8 mm.

[0171] After dividing the two-dimensional carbon fiber braided sleeve into a fixed section, a free section, and an axially sliding section connected sequentially along the axial direction, the axially sliding section of the two-dimensional carbon fiber braided sleeve is fitted onto the inner mold II, and the outer mold II is fitted onto the axially sliding section to constrain the radial degree of freedom of the axially sliding section. Then, an uninflated airbag II (spherical shape, silicone rubber material, wall thickness of 1.5mm, hardness of Shore A40, and uninflated outer diameter of 180mm) is arranged in the free section with an outer diameter D0 of 300mm. Then, the fixed section is radially clamped, axially positioned, and circumferentially anti-rotation limited by a three-jaw chuck, end face pressure plate, and anti-rotation pin, respectively, so that all degrees of freedom of the fixed section are constrained and the airbag inlet pipe is sealed. Among them, the inner mold II is cylindrical with an outer diameter of 296mm; the outer mold II is cylindrical with an inner diameter of 300.8mm.

[0172] (3) Adjust the relative positions of inner mold I and outer mold I, and inner mold II and outer mold II respectively, so that the woven areas near airbag I and airbag II are no longer simultaneously constrained by their respective inner and outer molds. Then inflate airbag I and airbag II respectively to make them expand, causing the free sections of the aramid fiber two-dimensional woven sleeve and the carbon fiber two-dimensional woven sleeve to undergo deformation mainly by in-plane shear deformation. The maximum outer diameter D of the free section after deformation b All satisfy D b / D0=1.7;

[0173] Twelve test points were taken on the free section of the deformed aramid fiber two-dimensional braided sleeve for testing, and the maximum relative deviation of the areal density was measured. The maximum relative deviation in thickness is 7.8%. It is 12.5%;

[0174] Twelve test points were taken on the free section of the deformed carbon fiber two-dimensional braided sleeve for testing, and the maximum relative deviation of the areal density was measured. The maximum relative deviation in thickness is 7.2%. It is 11.5%;

[0175] Five specimens were taken from the deformed free section of the aramid fiber two-dimensional braided sleeve and subjected to in-plane tensile and bending tests. The coefficient of variation of the tensile ultimate strength was 13%, and the coefficient of variation of the bending ultimate strength was 12%.

[0176] Five samples were taken from the deformed free section of the carbon fiber two-dimensional braided sleeve for testing. The coefficient of variation of the tensile ultimate strength was 12%, and the coefficient of variation of the flexural ultimate strength was 11%.

[0177] The outer surface of the free section after deformation on the aramid fiber two-dimensional braided sleeve and the carbon fiber two-dimensional braided sleeve is flat and continuous under the observation distance of 0.8m and equivalent lighting conditions, with no wrinkles or creases visible to the naked eye.

[0178] (4) Release the pressure of airbag I and airbag II, separate the deformed free sections on the aramid fiber two-dimensional braided sleeve and the carbon fiber two-dimensional braided sleeve respectively, and fold them inward along the radial direction of the deformed free sections to obtain aramid double-layer three-dimensional curved surface braided preform and carbon fiber double-layer three-dimensional curved surface braided preform respectively. Then, on the three-dimensional curved surface rigid mold, the aramid double-layer three-dimensional curved surface braided preform and the carbon fiber double-layer three-dimensional curved surface braided preform are stacked and repeated in sequence. A PPS film (manufacturer is Solvay Specialty Polymers, USA, brand name is Ryton®QA200P) is introduced between adjacent preforms. The total number of layers of aramid double-layer three-dimensional curved surface braided preform and carbon fiber double-layer three-dimensional curved surface braided preform is 12.

[0179] (5) After the layering is completed, hot pressing and curing are performed to obtain a three-dimensional curved fiber reinforced composite shell; wherein the curing pressure is 5MPa, the curing temperature is 320℃, the curing time is 1h, and the volume fraction of fiber in the three-dimensional curved fiber reinforced composite shell is 90%.

[0180] The final three-dimensional curved fiber-reinforced composite shell is a protective helmet shell with a mass of 0.92 kg. The ballistic limit V50 of the crown area of ​​the protective helmet shell is 530 m / s, the ballistic limit V50 of the forehead area is 522 m / s, and the ballistic limit V50 of the sidewall area is 515 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 2.87%. It can be seen that the protective helmet shell prepared in this embodiment has better uniformity of performance in each area and better protection. This also proves that the prepared protective helmet shell maintains continuous fiber coverage and improves structural integrity.

[0181] Example 6

[0182] A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell, comprising the following steps:

[0183] (1) Non-metallic continuous fibers (composed of 1100Dtex aramid fibers and 12K carbon fibers with a mass ratio of 1:1, the aramid fibers being composed of 1000 monofilaments with a diameter of 12μm and the carbon fibers being composed of 12000 monofilaments with a diameter of 7μm) are braided on a horizontal two-dimensional circular tube braiding machine to obtain a two-dimensional braided sleeve; wherein, the braiding angle of the two-dimensional braided sleeve is 45° and the braiding unit is rhomboid;

[0184] The resulting two-dimensional braided sleeve has a wall thickness of 0.5 mm, an inner diameter of 299 mm, and a bending stiffness of 2 × 10⁻⁶. -4 N·m;

[0185] (2) After dividing the two-dimensional braided sleeve into a fixed section, a free section and an axial sliding section connected in sequence along the axial direction, first put the axial sliding section on the inner mold and then put the outer mold on the axial sliding section so that the radial degree of freedom of the axial sliding section is constrained. Then, an uninflated airbag (the airbag is spherical, made of silicone rubber, with a wall thickness of 1.5 mm, a hardness of Shore A40, and an uninflated outer diameter of 180 mm) is placed in the free section with an outer diameter D0 of 300 mm. Then, the fixed section is clamped in the axial, radial and rotational directions by the ring clamp and the anti-rotation pin so that all the degrees of freedom of the fixed section are constrained and the airbag inlet pipe is sealed. Among them, the inner mold is a round tube with an outer diameter of 298 mm; the outer mold is a round tube with an inner diameter of 300.6 mm.

[0186] (3) Adjust the relative positions of the inner and outer molds so that the woven fabric area near the airbag is no longer constrained by both the inner and outer molds at the same time. Then inflate the airbag to make it expand, causing the free segment to undergo deformation mainly by in-plane shear deformation. The maximum outer diameter D of the deformed free segment is... b Satisfy D b / D0=1.8;

[0187] Twelve test points were selected on the deformed free section for testing, and the maximum relative deviation of the areal density was measured. It is 8.0%, and the thickness is 8.0%. The maximum relative deviation was 13.0%;

[0188] Five specimens were taken from the deformed free section for in-plane tensile and bending tests. The coefficient of variation of the ultimate strength in the in-plane tensile test was 12%, and the coefficient of variation of the ultimate strength in the bending test was 13%.

[0189] The outer surface of the deformed free section is smooth and continuous under natural light at an observation distance of 0.8m, with no wrinkles or creases visible to the naked eye.

[0190] (4) While the airbag is under pressure, a base material (obtained by degassing a mixture of epoxy resin (manufacturer Huntsman Group, brand name Araldite LY1564) and curing agent (manufacturer Huntsman Group, brand name Aradur3416) with a mass ratio of 1:0.37) is applied to the outer surface of the expansion area by brushing, so that the base material penetrates into the gaps between the braided fibers. Then, the system is kept at 40°C for 20 minutes to increase the viscosity of the system / to a semi-gel state, so as to maintain the three-dimensional curved shape during the release of airbag pressure and subsequent handling and cutting.

[0191] (5) Release the airbag pressure, separate the deformed free section from the two-dimensional braided sleeve, and cut longitudinally along the axial direction of the deformed free section to obtain a single-layer three-dimensional curved surface braided preform. Then, stack the single-layer three-dimensional curved surface braided preform on the three-dimensional curved surface rigid mold and seamlessly fit it with the three-dimensional curved surface rigid mold. After curing, a three-dimensional curved surface fiber reinforced composite material shell is obtained. The number of stacked layers is 24, the curing pressure is 5MPa, the curing temperature is 150℃, the curing time is 4h, and the fiber volume fraction in the three-dimensional curved surface fiber reinforced composite material shell is 99%.

[0192] The final three-dimensional curved fiber-reinforced composite shell is a protective helmet shell with a mass of 0.93 kg. The ballistic limit V50 of the crown region of the protective helmet shell is 508 m / s, the ballistic limit V50 of the forehead region is 503 m / s, and the ballistic limit V50 of the sidewall region is 498 m / s. The maximum relative deviation ΔV50 of the ballistic limit V50 is 1.99%. It can be seen that the protective helmet shell prepared in this embodiment has better uniformity of performance in each region and better protection. This also proves that the prepared protective helmet shell maintains continuous fiber coverage and improves structural integrity.

Claims

1. A method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell, characterized in that, Includes the following steps: (a) Divide the two-dimensional braided sleeve into a fixed section, a free section and an axial sliding section connected in sequence along the axial direction. All degrees of freedom of the fixed section are constrained, all degrees of freedom of the free section are not constrained, and only the radial degree of freedom of the axial sliding section is constrained. An uninflated airbag is arranged in the free section. Two-dimensional braided sleeves are formed by weaving yarns at a braiding angle of 20°-70°. The yarns are non-metallic continuous fibers, and the braiding units are rhomboid. The bending stiffness of the two-dimensional braided sleeve is not less than 1×10⁻⁶. -5 N·m and not higher than 5×10 -3 N·m, the wall thickness of the two-dimensional braided sleeve is 0.1-2mm; (b) Inflate the airbag to make it expand, causing the free segment to undergo deformation mainly in-plane shear deformation; In step (b), the outer diameter of the free section before deformation is D0, where D0 is 50-500 mm, and the maximum outer diameter of the free section after deformation is D. b 1.05≤D b / D0≤2.00; the airbag is a spherical airbag, an ellipsoidal airbag, or a spindle-shaped airbag; At least 10 test points were taken on the deformed free section for testing, and the maximum relative deviation of the areal density was measured. Maximum relative deviation of thickness not exceeding 10% No more than 15%, and The calculation formula is as follows: ； ； In the formula, , , These correspond to the maximum, minimum, and average areal density of the test points, respectively. , , These correspond to the maximum thickness, minimum thickness, and average thickness of the test point, respectively. At least five specimens were taken from the deformed free section and subjected to in-plane tensile and / or bending tests, with the coefficient of variation of the ultimate strength not exceeding 15%. The outer surface of the deformed free section is smooth and continuous under natural light or equivalent lighting conditions at an observation distance of 0.5-1.0m, without any wrinkles or creases visible to the naked eye. (c) Release the airbag pressure, separate the deformed free section from the two-dimensional braided sleeve, process it to obtain a three-dimensional curved surface braided preform, then stack the three-dimensional curved surface braided preform on the three-dimensional curved surface rigid mold and seamlessly fit it with the three-dimensional curved surface rigid mold, and then solidify it to obtain a three-dimensional curved surface fiber reinforced composite material shell. Processing refers to longitudinal cutting along the axial direction of the deformed free segment to obtain a single-layer three-dimensional curved surface woven preform; or processing refers to folding inward or outward along the radial direction of the deformed free segment to obtain a double-layer three-dimensional curved surface woven preform. The laminated structure contains a matrix material during curing and molding.

2. The method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell according to claim 1, characterized in that, The non-metallic continuous fiber is at least one of aramid fiber, carbon fiber, glass fiber, ultra-high molecular weight polyethylene fiber, polyacrylonitrile-based fiber, PBO fiber, PBI fiber, liquid crystal polymer fiber, basalt fiber and quartz fiber; the non-metallic continuous fiber is composed of multiple monofilaments, and the diameter of the monofilament is 3-30μm.

3. The method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell according to claim 1, characterized in that, In step (a), all degrees of freedom of the fixed segment are constrained by applying axial, radial and rotational limiting or clamping actions to the fixed segment; The radial degree of freedom of the axial sliding section is constrained only by fitting the axial sliding section onto the inner mold and then fitting the outer mold onto the axial sliding section. The inner mold is cylindrical or tubular, and its outer diameter is slightly smaller than the inner diameter of the axial sliding section. The outer mold is tubular, and its inner diameter is larger than the outer diameter of the axial sliding section but smaller than the size that allows the axial sliding section to undergo radial free deformation.

4. The method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell according to claim 1, characterized in that, In step (c), before separating the deformed free segment from the two-dimensional braided sleeve, a matrix material is coated or impregnated on the outer surface of the deformed free segment so that the laminated structure contains the matrix material during curing. Alternatively, during the layering process, a matrix material can be introduced between the layers so that the laminated structure contains the matrix material when it is cured and molded.

5. The method for manufacturing a three-dimensional curved surface fiber-reinforced composite material shell according to claim 1, characterized in that, In step (c), the volume fraction of fibers in the three-dimensional curved fiber-reinforced composite shell is 70%-99%.

6. A three-dimensional curved surface fiber-reinforced composite material shell, characterized in that, The shell is manufactured using the method described in any one of claims 1 to 5 for manufacturing a three-dimensional curved fiber-reinforced composite material shell.

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