Preparation method of fiber reinforced composite material based on shearing force induction

Abstract

The invention relates to a preparation method of a fiber reinforced composite material based on shearing force induction, belongs to the technical field of manufacturing of high-performance composite materials, and solves the problems that in the prior art, fiber orientation control is insufficient, an anti-impact structure is difficult to prepare, and association between a fracture mechanism and performance is deficient. The method comprises the following steps: firstly, pre-mixing short cut fibers activated by plasmas with a resin matrix added with a nano SiO2 toughening agent; then enabling the mixture to pass through a multi-stage shearing runner comprising a conical pre-dispersion area and a narrow slit orientation area, and realizing efficient dispersion and high orientation (the orientation degree is greater than or equal to 90%) of the fibers at a specific shearing rate (50-200s <-1 > and 800-2000s <-1 >); then, the 3D printing technology is adopted to control the interlayer deflection angle (35-45 degrees) to be stacked layer by layer, and a Bouligand structure prefabricated body is constructed; and finally, carrying out curing and supercritical CO2 foaming treatment to form a micropore-compact alternate layered structure. The method is suitable for the field of high-performance requirements such as aerospace protection components.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-performance composite material manufacturing, and particularly relates to a fiber-reinforced composite material preparation method based on shear force induction. BACKGROUND

[0002] Fiber-reinforced composites are widely used in the field of impact resistance, but their performance is limited by three major bottlenecks: low fiber orientation (usually less than 75% in traditional injection molding / lamination process), difficulty in preparing biomimetic structures, and lack of correlation between fracture mechanism and performance. These problems lead to rapid crack propagation and low energy absorption efficiency (typical value <1.5 kJ / m 2 , and traditional lamination process is difficult to optimize crack path and interface failure mode.

[0003] Theoretical research shows that constructing a Bouligand structure with a specific interlaminar deflection angle is an effective way to improve toughness. The performance of the structure is closely related to the deflection angle (θ): under low deflection angle (θ < 30°), the crack propagates along the fiber, and the energy absorption is low; under high deflection angle (θ > 50°), crack bridging is dominant, and the toughness is limitedly improved; and when θ is in the optimal interval of 35°-45°, crack twisting and fiber pull-out can be synergistically excited, and the energy absorption potential can be increased by more than 140% compared with isotropic structure.

[0004] However, existing manufacturing techniques cannot precisely and reliably realize this optimal deflection angle structure while ensuring high fiber orientation (≥90%) and uniform dispersion. This causes a technical dilemma of "clear mechanism but lack of preparation", and there is an urgent need for a method that can integrate microstructure design, fiber orientation control and quantitative performance prediction. SUMMARY

[0005] In view of the above analysis, the present application aims to provide a fiber-reinforced composite material preparation method based on shear force induction, system and product, to solve at least one of the problems of insufficient fiber orientation control, difficulty in preparing impact-resistant structures, and lack of correlation between fracture mechanism and performance in the prior art.

[0006] In a first aspect, the present application provides a fiber-reinforced composite material preparation method based on shear force induction, comprising the following steps:

[0007] S1. Pre-mixing chopped fibers activated by plasma with a resin matrix added with nano-SiO2 toughening agent to form a fiber-resin mixed slurry;

[0008] S2. Inducing orientation of the mixed slurry by passing through a conical pre-dispersion zone (FAME) and a narrow slit orientation zone in sequence, wherein the shear rate of the conical pre-dispersion zone is 50-200 s -1, the shear rate of the narrow slit orientation zone is 800-2000 s -1 , the gap is 0.1-0.3 mm, and the fiber orientation degree is ≥ 90%;

[0009] S3. Layer-by-layer accumulation is performed by using a 3D printing technology of programmed control of interlayer deflection angle, the interlayer deflection angle is controlled to be 35°-45°, and a preform with a Bouligand structure is constructed;

[0010] S4. The preform is subjected to a curing treatment to lock the fiber orientation, and then subjected to a supercritical CO2 foaming treatment, to form a composite material with a micro-pore-dense alternating layered structure, and the porosity is 30%-85%.

[0011] Further, the chopped fibers are glass fibers or carbon fibers, the length is 200-500 μm, the diameter is 7-15 μm, and the plasma activation treatment adopts an atmospheric pressure plasma, the power is 500-1500 W, and the treatment time is 5-15 min.

[0012] Further, the resin matrix is an epoxy resin or a polyurethane, the particle size of the nano-SiO2 toughening agent is 20-50 nm, and the addition amount is 3-8 wt%.

[0013] Further, in the supercritical CO2 foaming treatment, the foaming pressure is 10-20 MPa, the foaming temperature is 40-60℃, and the foaming time is 1-4 hours.

[0014] Further, the process parameters of the 3D printing include: a layer thickness of 0.1-0.3 mm, a printing speed of 10-30 mm / s, a nozzle temperature of 80-120℃, and a printing path that is programmed to be deflected according to the Bouligand structure.

[0015] Further, the curing treatment is ultraviolet curing or thermal curing; the thermal curing is performed in two stages: the first stage is curing at 60-80℃ for 1-2 hours, and the second stage is curing at 100-120℃ for 2-3 hours.

[0016] In a second aspect, the present application provides a fiber-reinforced composite material prepared by the above method, the composite material has a Bouligand structure, the interlayer deflection angle is 35°-45°, the fracture surface roughness Ra is ≥ 15 μm, and the energy absorption capacity is ≥ 2.0 kJ / m 2 .

[0017] In a third aspect, the present application provides a 3D printing system for implementing the above method, comprising:

[0018] A multi-stage shear flow channel module comprising a conical pre-dispersion zone and a narrow slit orientation zone, the gap of the narrow slit orientation zone being adjustable in a range of 0.1-0.3mm;

[0019] A high-precision deflection platform with a rotation resolution of ≤±0.5°;

[0020] An online ultrasonic monitor for real-time monitoring of fiber dispersion state;

[0021] And an online roughness monitor for real-time detection of the surface morphology of the printed structure.

[0022] In a fourth aspect, the present application proposes an impact-resistant protective component made of the above-mentioned fiber-reinforced composite material, which is a bionic armor plate, a bulletproof insert plate or an aerospace buffer energy-absorbing structure.

[0023] In a fifth aspect, the present application proposes an application of the above-mentioned fiber-reinforced composite material in the field of high-end sports equipment, automobile lightweighting or human body protection.

[0024] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0025] 1) By designing a multi-stage shear flow channel comprising a conical pre-dispersion zone and a narrow slit orientation zone, the medium shear rate (50-200s -1 ) in the pre-dispersion zone effectively breaks the fiber agglomeration, significantly reducing the agglomeration rate; the high shear rate (800-2000s -1 ) and the small gap (0.1-0.3mm) in the orientation zone create a strong shear field, which promotes the fiber to be highly oriented along the flow direction, and finally makes the overall fiber orientation degree stable at more than 90%, which is much higher than the usual level (<75%) of traditional injection molding or layering process, fundamentally improving the mechanical properties of the composite material.

[0026] 2) The high-precision programmed deflection printing platform with a rotation resolution of ≤±0.5° realizes accurate control of the interlayer deflection angle in the range of 35°-45°, and successfully constructs a bionic Bouligand multi-layer structure. This structure can effectively guide the crack to expand along a spiral path, greatly increasing the crack propagation length and the fracture surface roughness, thereby significantly improving the fracture toughness and energy absorption performance of the material, making its energy absorption capacity reach 2.0kJ / m 2 The above is more than twice that of the traditional unidirectional laminated structure, which demonstrates excellent impact resistance.

[0027] 3) Based on systematic experiments, a quantitative relationship model between the roughness (Ra) of the fracture surface and the energy absorption capacity can be established, and the online monitoring system integrated in the printing system can realize real-time feedback and regulation of the surface morphology during the printing process. This method effectively avoids the problems of long research and development cycle and large fluctuation of results caused by the traditional "trial and error method", significantly improving the repeatability of the process and the consistency of the product performance.

[0028] 4) By introducing nano-SiO2 toughening agent (particle size 20-50nm) into the resin matrix and subsequent supercritical CO2 foaming process, a gradient layered structure of alternating micro-porous-dense is formed inside the material. This structure, while maintaining the lightweight characteristics of the material (porosity 30-85%), further improves the toughness and energy dissipation capacity of the matrix through the synergistic effect of matrix toughening, interface optimization and multi-level pore structure deformation, etc. The foaming structure can significantly contribute to the total energy absorption.

[0029] 5) The present application realizes precise control and good consistency of the preparation process of high-performance composite materials by closely combining the printing system with the material process, and successfully manufactures practical protective components with lightweight advantage and excellent impact resistance. The printing system solves the key problem of accurate manufacturing of bionic structures, and the protective components developed based on the material of the present application have the characteristics of strong designability, lightweight and high toughness, and show broad application prospects in high-end application fields such as aerospace and human body protection armor.

[0030] In the present application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and serve to explain the principles of the application, and are not intended to limit the scope of the application.

[0032] Figure 1 The structure principle of the multi-stage shear flow channel module and the fiber dispersion and orientation evolution process of the present application are shown in the figure. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, wherein the drawings constitute a part of this application and are used to illustrate the principles of the embodiments of the present application, and are not intended to limit the scope of the present application.

[0034] In a first aspect, the present application provides a method for preparing fiber-reinforced composite materials based on shear-induced orientation, comprising the following steps:

[0035] S1. Pre-mixing the plasma-activated chopped fibers with the resin matrix to which nano-SiO2 toughening agent is added to form a fiber-resin mixed slurry;

[0036] S2. Subjecting the mixed slurry to shear-induced orientation by passing it through a conical pre-dispersion zone and a narrow-slit orientation zone in sequence, wherein the shear rate of the conical pre-dispersion zone is 50-200 s -1 (eg. 50 s -1 , 80 s -1 , 100 s -1 , 120 s -1 , 150 s -1 , 180 s -1 , 200 s -1 ) and the shear rate of the narrow-slit orientation zone is 800-2000 s -1 (eg. 800 s -1 , 1000 s -1 , 1200 s -1 , 1500 s -1 , 1800 s -1 , 2000 s -1 ), the gap is 0.1-0.3 mm (eg. 0.1 mm, 0.2 mm, 0.3 mm), so that the fiber orientation degree reaches ≥ 90% (eg. 91%, 92%, 93%, 94%, 95%, 95%);

[0037] S3. Using a 3D printing technology with programmed control of interlayer deflection angle to accumulate layer by layer, controlling the interlayer deflection angle to be 35°-45° (eg. 35°, 38°, 40°, 42°, 45°), to construct a preform with Bouligand structure;

[0038] S4. Subjecting the preform to curing treatment to lock the fiber orientation, and then to supercritical CO2 foaming treatment, to form a composite material with a micro-pore-dense alternating layered structure, the porosity being 30%-85% (eg. 30%, 40%, 50%, 60%, 70%, 80%, 85%).

[0039] Further, the short fibers are glass fibers or carbon fibers, with a length of 200-500 μm (e.g. 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm) and a diameter of 7-15 μm (e.g. 7 μm, 9 μm, 10 μm, 12 μm, 13 μm, 15 μm). The fibers need to be treated by plasma activation before use to enhance the interfacial bonding with the resin matrix. Preferably, the plasma activation treatment uses atmospheric plasma with a power of 500-1500 W (e.g. 500 W, 800 W, 1000 W, 1200 W, 1500 W) and a treatment time of 5-15 min (e.g. 5 min, 8 min, 10 min, 12 min, 15 min). This treatment can introduce oxygen-containing active functional groups on the fiber surface, allowing stronger chemical bonding with the resin matrix, and the interfacial shear strength can thus be improved by more than 30%, as measured.

[0040] Further, the resin matrix is an epoxy resin or a polyurethane. The nano-SiO2 toughening agent has a particle size of 20-50 nm (e.g. 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm) and an addition amount of 3-8 wt% (e.g. 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%) of the mass of the resin matrix. The addition of nano-SiO2 particles mainly improves the toughness of the matrix by inducing crack deflection and bridging cracks. In addition, a supercritical CO2 foaming agent is also added in the resin matrix in advance, with an addition amount of 0.5-2 wt%, for forming a microcellular structure in the subsequent step.

[0041] In one specific embodiment of S1, after the plasma-activated short fibers are premixed with the resin matrix containing nano-SiO2, an ultrasonic dispersion technique (frequency 20-40 kHz) is also used to assist the treatment of the mixture, to thoroughly break up the fiber agglomerates and promote the uniform distribution of the components, so as to finally form a homogeneous fiber-resin mixed slurry.

[0042] Further, in S2, the multi-stage shear flow channel is the core for achieving efficient dispersion and precise orientation of the fibers. Referring to Figure 1 , the multi-stage shear flow channel system includes a conical pre-dispersion zone and a narrow-gap orientation zone connected in sequence. The fiber / resin mixture enters from the inlet, first passes through the conical pre-dispersion zone, which applies a moderate shear rate of 50-200 s -1 -1, and its function is to break up the fiber agglomerates. Ultrasonic transducers (frequency 20 kHz) are integrated on the outer wall of this zone, and through the synergistic effect of ultrasonic cavitation and shear field, the dispersion effect is further enhanced. Subsequently, the slurry enters the narrow-gap orientation zone, which has a gap of 0.1-0.3 mm (preferably 0.2 mm) and applies a high shear rate of 800-2000 s-1 The high shear rate of the device forces the fibers to highly orient along the flow direction by the strong shear flow field generated. After the treatment, the fibers in the slurry obtained from the outlet are highly oriented and uniformly dispersed, with an orientation degree of more than 90%. The multi-stage design successfully improves the average orientation degree of the fibers to more than 90% through the synergy of different shear regions, providing an excellent mechanical property basis for the material.

[0043] Further, in the S3 step, a 3D printing technology is used for layer-by-layer accumulation and structure construction. The process parameters of the 3D printing include: layer thickness 0.1-0.3 mm (for example, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm), printing speed 10-30 mm / s (for example, 10 mm / s, 15 mm / s, 20 mm / s, 25 mm / s, 30 mm / s), nozzle temperature 80-120°C (for example, 80°C, 90°C, 100°C, 110°C, 120°C), wherein the epoxy resin is preferably 80-100°C, and the polyurethane is preferably 100-120°C. Crucially, the printing direction of each layer is accurately controlled by a high-precision programmed deflection platform (rotational resolution ≤±0.5°), so that the interlayer deflection angle is stably controlled between 35° and 45° (preferably 40°), to successfully construct the biomimetic Bouligand structure.

[0044] 100-120°C. Crucially, the printing direction of each layer is accurately controlled by a high-precision programmed deflection platform (rotational resolution ≤±0.5°), so that the interlayer deflection angle is stably controlled between 35° and 45° (preferably 40°), to successfully construct the biomimetic Bouligand structure.

[0045] In a preferred embodiment, after each layer is completed, it is immediately pre-cured by irradiation with ultraviolet light (wavelength 365 nm, intensity 50 mW / cm 2 ) for 10-30 seconds, so that the resin is initially cured (curing degree of 30%-40%), thereby locking the fiber orientation and geometry of the layer and preventing disturbance during subsequent printing.

[0046] It should be noted that the rotational movement of the programmed deflection platform and the extrusion movement of the printing head are synchronously controlled by high-precision pulse signals, with a synchronization error of ≤±0.1 seconds. This high-precision synchronization avoids the problem of weakened interlayer bonding caused by interlayer pauses or asynchronous movement, ensuring the consistency of the overall structure and the stability of its mechanical properties.

[0047] Further, in the S4 step, the curing treatment is ultraviolet curing or thermal curing. Preferably, an ultraviolet-thermal synergistic curing process is used. First, a relatively strong ultraviolet light (wavelength 365 nm, intensity 80 mW / cm 2) irradiation for 30-60 minutes to achieve a curing degree of 70%-80%; then, two-stage thermal curing in an oven: the first stage is curing at 60-80℃ (for example, 60℃, 65℃, 70℃, 75℃, 80℃) for 1-2 hours (for example, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours), and the second stage is curing at 100-120℃ (for example, 100℃, 105℃, 110℃, 115℃, 120℃) for 2-3 hours (for example, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours), so that the resin is finally completely crosslinked (total curing degree ≥95%). This strategy effectively reduces internal stress and improves the dimensional stability of the product.

[0048] After curing, supercritical CO2 foaming treatment is performed. Preferably, the foaming pressure is 10-20 MPa (for example, 10 MPa, 12 MPa, 15 MPa, 18 MPa, 20 MPa), the foaming temperature is 40-60℃ (for example, 40℃, 45℃, 50℃, 55℃, 60℃), and the foaming time is 1-4 hours (for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours). Under these conditions, a microporous-dense alternating layered structure with uniform pore size (10-100 μm) and controllable porosity gradient (porosity 30%-85%) can be formed inside the material.

[0049] In a second aspect, the present application provides a fiber-reinforced composite material prepared by the above method, which has a Bouligand structure, an interlayer deflection angle of 35°-45° (for example, 35°, 38°, 40°, 42°, 45°), a fracture surface roughness Ra≥15 μm (for example, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm), and an energy absorption capacity ≥2.0 kJ / m 2 (for example, 2.0 kJ / m 2 , 2.1 kJ / m 2 , 2.2 kJ / m 2 , 2.3 kJ / m 2 , 2.4 kJ / m 2 , 2.5 kJ / m 2 , 2.6 kJ / m 2 ), and exhibits excellent impact resistance.

[0050] In a third aspect, the present application provides a 3D printing system for implementing the above method, comprising:

[0051] a multi-stage shear flow channel module comprising a conical pre-dispersion zone and a narrow slit orientation zone, the gap of the narrow slit orientation zone being adjustable in the range of 0.1-0.3 mm (for example, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm);

[0052] high-precision deflection platform with a rotation resolution of ≤±0.5° (e.g., 0.01°, 0.02°, 0.05°, 0.1°, 0.2°, 0.25°, 0.5°);

[0053] an online monitoring and feedback control module including an online ultrasonic monitor and an online roughness monitor; the online ultrasonic monitor is used to monitor the dispersion state of the fibers in real time; the online roughness monitor is used to detect the surface morphology of the printed structure in real time;

[0054] and a central controller connected to the above-mentioned modules for receiving monitoring data and sending control instructions.

[0055] Further, the multi-stage shear flow channel module is the core component for realizing efficient dispersion and precise orientation of the fibers. The conical pre-dispersion zone is a conical flow channel with a cone angle of 15°-30°, and the shear rate in the conical pre-dispersion zone is controllable within the range of 50-200 s -1 , which is used to initially break the fiber agglomerates. The narrow-slit orientation zone is a parallel-plate narrow-slit flow channel with adjustable gap, and the gap is adjusted by a precision micrometer-level gasket or a servo motor. The shear rate in the narrow-slit orientation zone is controllable within the range of 800-2000 s -1 , which is used to induce high orientation of the fibers under strong shear field.

[0056] Preferably, an ultrasonic transducer (frequency 20 kHz) is integrated on the outer wall of the conical pre-dispersion zone, and the dispersion effect is further enhanced by the synergistic effect of ultrasonic cavitation and shear flow.

[0057] Further, the high-precision deflection platform is used to realize precise construction of Bouligand biomimetic structures. The platform is composed of a high-precision servo motor, a speed reducer, and an absolute value encoder to form a closed-loop control system, ensuring that the rotation resolution is ≤±0.5° and the repeat positioning accuracy is ≤±0.1°. The motion of the printing nozzle is synchronized with the high-precision pulse signal sent by the central controller, and the synchronization timing error is ≤±0.1 seconds, so as to ensure that the platform can automatically and accurately rotate a preset angle (35°-45°) after each layer of printing is completed.

[0058] Further, the online monitoring and feedback control module is the key to realizing process stability and product consistency.

[0059] The probe of the online ultrasonic monitor is placed in the flow channel before the mixed slurry is delivered to the printing nozzle, which is used to monitor the acoustic properties of the slurry in real time, so as to indirectly evaluate the dispersion state of the fibers;

[0060] The online roughness monitor adopts a laser confocal microscopic probe integrated on the side of the printing nozzle, which scans the surface of each layer after printing and pre-curing, and measures the arithmetic mean deviation Ra value of the surface topography.

[0061] The central controller receives real-time data stream from the above monitoring instrument, and has a built-in control algorithm, which can dynamically fine-tune the shear rate, ultrasonic power, printing speed or layer thickness according to the monitoring data.

[0062] In a fourth aspect, the present application provides an impact-resistant protective component made of the fiber-reinforced composite material prepared by the method of the present application. The composite material has a Bouligand structure and a micropore-dense alternating layered feature, making it particularly suitable for scenarios requiring high energy absorption, such as but not limited to bionic armor plate, bulletproof plate, aerospace buffer energy absorption structure, high-end sports protective equipment, automobile anti-collision component and human body protective equipment.

[0063] The present application will be described in more detail by specific examples. The examples are only a description of the best mode of the present application, and do not have any limitation on the scope of the present application.

[0064] Example 1

[0065] A method for preparing a fiber-reinforced composite material based on shear force induction, using raw materials:

[0066] Resin matrix: bisphenol A type epoxy resin with a viscosity of 50 Pa·s.

[0067] Toughening agent: nano-SiO2 (particle size 30 nm), added amount is 5% of the mass of the resin matrix.

[0068] Fiber: chopped glass fiber treated by normal pressure plasma (power 1000 W, treatment time 10 min), diameter 10 μm, length 500 μm (aspect ratio 50).

[0069] Foaming agent: supercritical CO2, used in subsequent foaming treatment.

[0070] Preparation method, including the following steps:

[0071] S1. Add nano-SiO2 to bisphenol A type epoxy resin, mechanically stir and mix uniformly. Then add the plasma-activated glass fiber, and use ultrasonic dispersion treatment at a frequency of 20 kHz for 60 s to obtain a fiber-resin mixed slurry with uniform fiber dispersion.

[0072] S2. Send the mixed slurry into a multi-stage shear flow channel system. First pass through a conical pre-dispersion zone (shear rate 200 s -1) preliminary dispersion, followed by a narrow slit orientation zone (gap 0.2 mm, shear rate 1000 s -1 ) induce highly oriented arrangement of fibers.

[0073] S3. The oriented slurry was transferred into a 3D printing system for layer-by-layer accumulation. The printing process parameters were: nozzle temperature 90°C, layer thickness 0.2 mm, printing speed 20 mm / s. After each layer was completed, the programmed deflection platform was precisely rotated by 40° (rotation accuracy ± 0.5°) to build a preform with a Bouligand structure.

[0074] S4. After printing was completed, thermal curing was performed: the first stage was curing at 70°C for 2 hours, and the second stage was curing at 110°C for 3 hours. Subsequently, supercritical CO2 foaming treatment was performed (pressure 15 MPa, temperature 50°C, time 2 hours), and finally a micro-porous-dense alternating layered structure was formed inside the material, with a porosity of 65%.

[0075] The fiber-reinforced composite material prepared according to the method of this embodiment has a Bouligand structure, and the interlayer deflection angle is 40°.

[0076] The 3D printing system used in this embodiment includes:

[0077] A multi-stage shear flow channel module, which includes a conical pre-dispersion zone (cone angle 20°) and a narrow slit orientation zone, the gap of the narrow slit orientation zone being 0.2 mm;

[0078] An ultrasonic transducer (frequency 20 kHz) is integrated on the outer wall of the conical pre-dispersion zone for auxiliary dispersion.

[0079] A high-precision deflection printing module for precise construction of a biomimetic Bouligand structure, which includes a high-precision deflection platform that constitutes a closed-loop control system with a high-precision servo motor, a speed reducer, and an absolute value encoder. The rotation resolution of the platform is ± 0.1°.

[0080] An online monitoring and feedback control module, which includes an online ultrasonic monitor with a probe placed in the flow channel before the mixed slurry is delivered to the printing nozzle for real-time monitoring of the dispersion state of the fibers, and an online roughness monitor (laser confocal microscopic probe, measurement range Ra 0.05-25 μm) integrated on the side of the printing nozzle for real-time detection of the surface morphology of the printed layer.

[0081] A central controller connected to the signal lines of the above-mentioned modules for receiving monitoring data and sending control instructions.

[0082] The composite material obtained in the embodiment is suitable for preparing impact protection components such as bionic armor plates, safety helmet linings and the like, and can be widely applied to high-end sports equipment, automobile lightweight or human body protection fields.

[0083] Example 2

[0084] The difference from example 1 is that S3 adopts a high-precision deflection platform of the 3D printing system of the application, and the printing deflection angle of each layer is dynamically adjusted during the printing process to prepare a functional component with the following structure:

[0085] Surface layer (0-1mm thickness): interlayer deflection angle is 0° unidirectional layup, used for high modulus bearing;

[0086] Core layer (1-8mm thickness): interlayer deflection angle is 40° Bouligand spiral structure, used for high efficiency energy absorption;

[0087] Back layer (8-10mm thickness): interlayer deflection angle linearly changes from 40° to 0°, variable stiffness gradient layer, and the fiber volume content linearly increases from 50% to 80%.

[0088] A fiber-reinforced composite bionic bulletproof plate is prepared by the method of the embodiment.

[0089] Example 3

[0090] The difference from example 1 is only that:

[0091] S1. The plasma activation treatment power is 500W, and the treatment time is 15min.

[0092] S2. The shear rate of the conical pre-dispersion zone is set to 50s -1 . The gap of the narrow slit orientation zone is 0.3mm, and the shear rate is set to 800s -1 . The measured fiber orientation degree is 90%.

[0093] S3. The printing layer thickness is 0.3mm, the printing speed is 10mm / s, and the nozzle temperature is 80℃. The programmed deflection platform rotates 35°.

[0094] S4. Heat curing: the first stage is cured at 60℃ for 2 hours, and the second stage is cured at 100℃ for 3 hours. Supercritical CO2 foaming treatment parameters: pressure 10MPa, temperature 40℃, time 4 hours. The final porosity is 85%.

[0095] The material is directly 3D printed into a light energy-absorbing pad in a human body protection armor plate.

[0096] Example 4

[0097] The difference from example 1 is that:

[0098] Raw materials: resin matrix is polyurethane; fiber is short-cut carbon fiber (diameter 7 μm, length 300 μm) activated by plasma (power 1500 W, treatment 5 min); nano-SiO2 addition amount is 3 wt%.

[0099] S2. The shear rate of the conical pre-dispersion zone is set to 200 s -1 . The gap of the narrow slit orientation zone is 0.1 mm, and the shear rate is set to 2000 s -1 .

[0100] S3. The printing layer thickness is 0.1 mm, the printing speed is 30 mm / s, and the nozzle temperature is 120°C. The programmed deflection platform is rotated by 45°.

[0101] S4. UV curing is used. The supercritical CO2 foaming treatment parameters are: pressure 20 MPa, temperature 60°C, and time 1 hour. The final porosity is 30%.

[0102] The obtained carbon fiber reinforced composite material has higher strength and modulus, and the material is used to manufacture high-end racing car body parts.

[0103] Example 5

[0104] The carbon fiber reinforced composite material prepared according to the method of Example 4 is used to manufacture a crash beam of an electric vehicle battery pack. The component is once-formed by 3D printing into a complex geometry with hollow reinforcing ribs, and the inside is a 45° Bouligand structure, which meets the requirements of harsh mechanical properties while reducing the weight of the traditional metal component by more than 40%.

[0105] Comparative Example 1

[0106] The difference from Example 1 is that during the 3D printing process, the interlayer deflection angle is set to 0° (no deflection), and the rest of the process parameters and raw materials are exactly the same as Example 1.

[0107] Comparative Example 2

[0108] The difference from Example 1 is that during the 3D printing process, the interlayer deflection angle is set to 90°, and the rest of the process parameters and raw materials are exactly the same as Example 1.

[0109] Comparative Example 3

[0110] The difference from Example 1 is that in the S2 step, the fiber-resin mixed slurry is not treated in a multi-stage shear channel module, but is directly placed in a single shear channel (gap 0.2 mm, shear rate 1000 s -1 ) for treatment. The rest of the raw materials, process parameters and conditions are exactly the same as Example 1.

[0111] Comparative Example 4

[0112] The difference from Example 1 is that in the S3 step, instead of using a high-precision deflection platform, a traditional 3D printing parallel path layering method (all layers are printed along the 0° direction) is used, and the rest of the raw materials, process parameters and conditions are exactly the same as those in Example 1.

[0113] Characterization results

[0114] The composite components prepared in the examples and comparative examples were tested under multi-directional impact load, and the key performance comparison results are shown in Table 1.

[0115] Table 1 Performance comparison of examples and comparative examples

[0116]

[0117] Table 1 data shows that by combining multi-stage shear flow field with programmed deflection 3D printing, the present application successfully realizes the highly directional arrangement of fibers (orientation degree ≥ 90%) and the synergistic construction of biomimetic Bouligand structure, so that the prepared composite material under 35°-45° interlayer deflection angle shows excellent energy absorption performance (energy absorption capacity ≥ 2.3 kJ / m 2 ) and fracture surface roughness (Ra> 16.5 μm).

[0118] The results of the comparative examples show that deviating from the 35°-45° deflection angle range or simplifying the shear flow channel design, or canceling the biomimetic structure design, will all lead to a significant decline in material performance. The present application effectively solves the problems of uneven fiber dispersion, orientation control difficulty and insufficient impact resistance structure forming precision in traditional processes, and provides a reliable and efficient solution for the controllable preparation of high-performance fiber reinforced composites.

[0119] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for producing a fiber-reinforced composite material based on shear force induction, characterized by, The method comprises the following steps: S1. Pre-mixing plasma-activated chopped fibers with a resin matrix added with nano-SiO2 toughening agent to form a fiber-resin mixed slurry; S2. Shearing force induced orientation of the mixed slurry through a conical pre-dispersion zone and a narrow slit orientation zone in sequence, wherein the shear rate of the conical pre-dispersion zone is 50-200 s -1 , the shear rate of the narrow slit orientation zone is 800-2000 s -1 , the gap is 0.1-0.3 mm, so that the fiber orientation degree reaches ≥ 90%; S3. Using 3D printing with programmed control of interlayer deflection angle to build a preform with Bouligand structure by layer-by-layer accumulation, with the interlayer deflection angle controlled at 35°-45°; S4. Locking the fiber orientation by curing treatment of the preform, followed by supercritical CO2 foaming treatment to form the fiber-reinforced composite material.

2. The method of claim 1, wherein, In S1, the chopped fibers are glass fibers or carbon fibers, with a length of 200-500 μm and a diameter of 7-15 μm, and the plasma activation treatment uses atmospheric pressure plasma with a power of 500-1500 W and a treatment time of 5-15 min.

3. The method of claim 1, wherein, In S1, the resin matrix is epoxy resin or polyurethane, and the nano-SiO2 toughening agent has a particle size of 20-50 nm and an addition amount of 3-8% of the mass of the resin matrix.

4. The method of claim 1, wherein, In S4, in the supercritical CO2 foaming treatment, the foaming pressure is 10-20 MPa, the foaming temperature is 40-60℃, and the foaming time is 1-4 hours.

5. The method of claim 1, wherein, In S3, the process parameters of the 3D printing include a layer thickness of 0.1-0.3 mm, a printing speed of 10-30 mm / s, a nozzle temperature of 80-120℃, and a printing path designed by programmed deflection according to the Bouligand structure.

6. The method of claim 1, wherein, In S4, the curing treatment is ultraviolet curing or thermal curing; the thermal curing is divided into two stages: the first stage is curing at 60-80℃ for 1-2 hours, and the second stage is curing at 100-120℃ for 2-3 hours.

7. A fiber reinforced composite material produced by the method of any one of claims 1 to 6, characterized by, The composite material has Bouligand structure, interlayer deflection angle is 35-45°, breaking surface roughness Ra is greater than or equal to 15μm, and energy absorption capacity is greater than or equal to 2.0kJ / m 2 .

8. A dedicated 3D printing system for carrying out the method according to any one of claims 1 to 6, characterized in that The method comprises: a multi-stage shear flow channel module, which comprises a conical pre-dispersion zone and a narrow slit orientation zone, and the gap of the narrow slit orientation zone is adjustable in the range of 0.1-0.3 mm; a high-precision deflection platform, which has a rotation resolution of ≤±0.5°; an online monitoring and feedback control module, which comprises an online ultrasonic monitor and an online roughness monitor; the online ultrasonic monitor is used for real-time monitoring of the fiber dispersion state; and the online roughness monitor is used for real-time detection of the surface morphology of the printed structure; and a central controller, which is signal-connected with the multi-stage shear flow channel module, the high-precision deflection platform, and the online monitoring and feedback control module, respectively, for receiving monitoring data and sending control instructions.

9. An impact protection member, characterized by The fiber-reinforced composite material of claim 7.

10. Use of the fiber-reinforced composite material of claim 7 in the field of high-end sports equipment, automotive lightweighting, or human body protection.

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