Preparation method and application of a shear thickening self-aware material

Abstract

The application relates to the technical field of human protective equipment, and discloses a preparation method and application of a shear thickening self-sensing material. An anti-ballistic fabric layer base material is selected, shear thickening gel raw materials composed of inorganic oxide particles and a polyethylene glycol polymer matrix are prepared, and conductive sensing layer raw materials composed of conductive fillers and a polyurethane solution are prepared. After ultrasonic dispersion, film coating, fabric impregnation and gradient distribution treatment, the materials are stacked and aligned in the order of an upper conductive sensing layer, a middle shear thickening gel layer and a lower pretreated anti-ballistic fabric layer, and are hot-pressed and combined to form a sandwich structure composite material. The shear thickening material is extruded to generate resistance / capacitance changes in the conductive layer under the instantaneous hardening characteristics of the shear thickening material under high-speed impact. The prepared shear thickening self-sensing material has integrated protection and sensing functions and can be applied to an intelligent anti-ballistic clothing system.

Description

Technical Field

[0001] This invention relates to the field of personal protective equipment technology, specifically to a method for preparing and applying a shear-thickening self-sensing material. Background Technology

[0002] Shear-thickening materials are a typical class of smart materials. Under normal conditions, they are flexible or viscous, but their apparent viscosity increases sharply upon high-speed impact, exhibiting the impact resistance of a solid. They quickly return to their original state after the impact subsides. Based on this characteristic, shear-thickening materials have broad application prospects in the field of personal protective equipment. Currently, researchers both domestically and internationally have combined shear-thickening fluids (STFs) with high-performance fibers (such as aramid and ultra-high molecular weight polyethylene) to prepare lightweight bulletproof and stab-resistant materials. Studies have shown that fabrics impregnated with STFs can significantly reduce the number of layers required while maintaining or enhancing protective performance, reducing the weight of bulletproof vests by 50%.

[0003] However, the existing shear-thickened composite materials are still limited to passive protection and have the following technical defects: (1) lack of self-sensing ability - traditional shear-thickened bulletproof materials can only absorb impact energy and cannot sense whether they have been hit or pierced in real time. It is difficult for the wearer to automatically alarm after being hit by a bullet; (2) inability to distinguish impact type - existing materials cannot identify different threats such as pistol bullets, rifle bullets, shotgun bullets or knife daggers. The command center cannot obtain accurate injury information, which delays battlefield first aid; (3) low degree of intelligent integration - if external sensors (such as accelerometers and strain gauges) are added to achieve detection, there are problems such as increased weight, easy damage at the moment of impact, and difficulty in conformal integration with flexible protective layers; (4) lack of positioning and networking functions - existing bulletproof vests do not integrate positioning and communication modules. In GPS denied environments (indoor, underground, tunnel), the individual soldier's position cannot be obtained, and teammates cannot coordinate perception.

[0004] Therefore, developing a composite material that combines shear thickening protection properties with self-sensing function and can be seamlessly integrated with subsequent signal recognition and network positioning systems has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing and applying a shear-thickening self-sensing material, which integrates self-sensing, lightweight, projectile type identification, and self-organizing network positioning. This solves the problems of traditional bulletproof vests lacking real-time bullet impact detection capabilities, having easily damaged external sensors, being unable to distinguish threat types, and being unable to locate in environments without GPS.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a shear-thickening self-sensing material, comprising the following steps: Step 1: Raw material preparation and component pretreatment: Select the bulletproof fabric layer substrate, prepare the shear thickening gel raw material composed of inorganic oxide particles and polyethylene glycol polymer matrix, and prepare the conductive sensing layer raw material composed of conductive filler and polyurethane solution. Weigh and pretreat each raw material separately. Step 2, preparation of shear-thickening gel: Inorganic oxide particles are dispersed in a polyethylene glycol polymer matrix and ultrasonically treated to obtain a shear-thickening gel; Step 3: Preparation of conductive sensing layer: Disperse conductive filler in polyurethane solution, coat it into a film and dry it to obtain conductive sensing layer; Step 4, bulletproof fabric impregnation treatment: The bulletproof fabric substrate is completely immersed in the shear thickening gel prepared in Step 2. Multiple impregnation-extrusion processes are used to control the amount of gel adhering to the fabric surface and interior. Then it is dried to obtain the pretreated bulletproof fabric layer. Step 5: Stacking and Composite: Following the sandwich structure, stack the three layers of materials in an orderly manner to form a pre-composite body; Step 6: Hot-press composite molding: The three-layer materials are integrated and composited through temperature and pressure control processes to obtain a composite board. Step 7, Post-processing and molding: After hot pressing, the composite board is removed and placed in a dust-free environment at room temperature to cool and set naturally. After trimming the appearance, the shear-thickening self-sensing material is obtained.

[0007] Preferably, in step one: the bulletproof fabric layer substrate is ultra-high molecular weight polyethylene fiber fabric or has an areal density of 200 g / m³. 2 Aramid fiber fabric.

[0008] Preferably, the inorganic oxide particles are selected from either nano-silica or calcium carbonate, and their particle size is controlled between 100-500 nm; the conductive filler is selected from either carbon nanotubes or graphene.

[0009] Preferably, in step two: the inorganic oxide particles are dispersed in a polyethylene glycol polymer matrix and ultrasonically treated for 30-60 minutes to obtain a shear-thickened gel, wherein the mass fraction of inorganic oxide particles in the gel is controlled at 20%-40%.

[0010] Preferably, in step three: a conductive filler with a mass fraction of 5%-15% is uniformly dispersed in a polyurethane solution, and a flexible conductive film with a thickness of 0.1-0.3 mm is prepared by coating film forming process, and then dried at 60-80℃ for 1-3 hours to obtain the finished conductive sensing layer.

[0011] Preferably, in step four, the bulletproof fabric is impregnated by: completely immersing the bulletproof fabric substrate in the shear-thickening gel prepared in step two, using a multiple impregnation-extrusion process to control the amount of gel adhering to the fabric surface and interior, controlling the shear-thickening gel content to be 20%-40%, and then drying it at 55-60℃ for 1.5-2 hours to obtain the pretreated bulletproof fabric layer.

[0012] Preferably, the shear thickening gel content parameter in step four is: the mass fraction of shear thickening gel near the conductive sensing layer is 20%, gradually increasing along the thickness direction, reaching 40% near the bulletproof fabric layer.

[0013] Preferably, in step five, the stacking and compounding process involves stacking and aligning the three layers in sequence, with the upper layer being a conductive sensing layer, the middle layer being a shear-thickening gel layer, and the lower layer being a pre-treated bulletproof fabric layer, to form a pre-composite with a sandwich structure.

[0014] Preferably, the pre-composite material stacked in step six is ​​placed in a hot press for hot pressing and curing. The process parameters are set as follows: hot pressing temperature 100℃, hot pressing pressure 1MPa, and heat and pressure holding time 15 minutes.

[0015] An application of a shear-thickening self-sensing material: A shear-thickening self-sensing material prepared according to the above method is applied to an intelligent bulletproof vest system.

[0016] Compared with the prior art, the present invention provides a method for preparing and applying a shear-thickening self-sensing material, which has the following beneficial effects: 1. This invention forms a sandwich structure by combining a shear-thickening gel with a conductive sensing layer. It utilizes the instantaneous hardening properties of the shear-thickening material under high-speed impact to compress the conductive layer and generate a change in resistance / capacitance. This achieves the beneficial effects of real-time sensing of impact events without the need for external sensors, a response time ≤0.8ms, a resistance change rate of up to 180%, and a signal waveform correlation coefficient >0.92 after three cycles of drop hammer impact (can be reused).

[0017] 2. This invention achieves the beneficial effects of increasing energy absorption rate by 20-30% compared to a uniform stacking structure by using a gradient distribution structure in the bulletproof fabric impregnation treatment (the gel mass fraction gradually increases from 20% near the conductive sensing layer to 40% near the bulletproof fabric layer), and reducing the peak force by 35% and increasing the energy absorption rate by 42% under the same drop hammer impact energy (50J) compared to pure Kevlar (Note: This effect includes the contribution of gradient distribution, which has been verified by Example 1). Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the preparation process of the shear-thickening self-sensing material of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 A method for preparing a shear-thickening self-sensing material includes the following steps: Step 1: Raw material preparation and component pretreatment: Select the bulletproof fabric layer substrate, prepare the shear thickening gel raw material composed of inorganic oxide particles and polyethylene glycol polymer matrix, and prepare the conductive sensing layer raw material composed of conductive filler and polyurethane solution. Weigh and pretreat each raw material separately. Step 2: Preparation of shear-thickening gel: Inorganic oxide particles are dispersed in a polyethylene glycol polymer matrix and ultrasonically treated to obtain a shear-thickening gel (STG). Step 3: Preparation of conductive sensing layer: Disperse conductive filler in polyurethane solution, coat it into a film and dry it to obtain conductive sensing layer; Step 4, bulletproof fabric impregnation treatment: The bulletproof fabric layer substrate is completely immersed in the shear thickening gel prepared in Step 2. Multiple impregnation-extrusion processes are used to control the amount of gel adhering to the fabric surface and interior. Then, it is dried to remove moisture and residual solvent, and a pretreated bulletproof fabric layer is obtained. Step 5: Stacking and Composite: Following the sandwich structure, stack the three layers of materials in an orderly manner to form a pre-composite body; Step 6: Hot-press composite molding: The three-layer materials are integrated and composited through temperature and pressure control processes to obtain a composite board. Step 7, Post-processing and molding: After hot pressing, the composite board is removed and placed in a dust-free environment at room temperature to cool and solidify naturally. Excess substrate at the edges and corners is removed and the appearance is trimmed to finally obtain a shear-thickening self-sensing material that combines protective performance and self-sensing function.

[0021] Specifically, in step one: the base material of the bulletproof fabric layer is ultra-high molecular weight polyethylene fiber fabric or fabric with a surface density of 200-220 g / m³. 2 Aramid (Kevlar) fiber fabrics (such as Kevlar129 aramid fabrics).

[0022] Specifically, the inorganic oxide particles are selected from either nano-silica or calcium carbonate, with a particle size controlled between 100-500 nm; the conductive filler is selected from either carbon nanotubes or graphene.

[0023] Specifically, the roles of the raw materials are shown in the table below: Table 1 ; Specifically, in step two: inorganic oxide particles are dispersed in a polyethylene glycol polymer matrix (PEG200) and ultrasonically treated for 30-60 minutes to ensure uniform dispersion of the particles, thereby obtaining a shear-thickening gel (STG). The mass fraction of inorganic oxide particles in the gel is controlled at 20%-40% to ensure shear-thickening response performance and structural stability.

[0024] The advantages are: ultrasonic dispersion avoids particle agglomeration; controlling the particle mass fraction between 20% and 40% ensures sufficient shear thickening response strength while maintaining the material's flexible processing properties; and it gives the shear thickening gel (STG) reversible shear thickening properties, allowing for repeated use.

[0025] Specifically, in step three: 5%-15% by mass of conductive filler is uniformly dispersed in a polyurethane solution, and a flexible conductive film with a thickness of 0.1-0.3 mm is prepared by coating film forming process. After drying at 60-80℃ for 1-3 hours, the finished conductive sensing layer is obtained, ensuring flexible adhesion and electrical signal sensing sensitivity.

[0026] The advantages are: by controlling the mass fraction of conductive filler at 5%-15%, the integrity of the conductive network is ensured while avoiding the embrittlement of the film caused by excessive filler; the coating process can precisely control the film thickness (0.1-0.3mm), ensuring flexible adhesion and signal sensitivity; and the drying temperature of 60-80℃ can fully remove the solvent and form a stable conductive film.

[0027] Specifically, in step four, the bulletproof fabric is impregnated: the bulletproof fabric substrate is completely immersed in the shear-thickening gel prepared in step two, and the amount of gel adhering to the fabric surface and inside is controlled by multiple impregnation-extrusion processes, and the shear-thickening gel content is controlled to be 20%-40% (e.g., 25wt%). Then it is placed in an environment of 55-60℃ and dried for 1.5-2 hours to remove the system moisture and residual solvent, and the pretreated bulletproof fabric layer is obtained.

[0028] Specifically, in step four: a multiple impregnation-extrusion process is used to control the amount of gel adhering to the fabric surface and interior, and to control the shear-thickening gel content, so as to achieve a gradient distribution of gel mass fraction in the thickness direction of the composite material. The specific parameters are: the shear-thickening gel mass fraction on the side near the conductive sensing layer is 20%, which gradually increases along the thickness direction, reaching 40% on the side near the bulletproof fabric layer, thereby improving the material's impact energy absorption rate. Compared with a uniform stacking structure, the energy absorption performance is improved by 20-30%.

[0029] The advantages are: by adopting a gradient distribution structure (20%→40%), the material triggers a shear thickening effect step by step during impact: a lower concentration near the impact surface (conductive sensing layer side) provides a rapid response, while a higher concentration near the back (bulletproof fabric layer side) provides high-intensity energy absorption. Compared to uniform stacking, energy absorption performance is improved by 20-30%, and the number of fabric layers can be further reduced at the same level of protection.

[0030] Specifically, in step five, the materials are stacked and laminated in the following order: the upper layer is a conductive sensing layer, the middle layer is a shear-thickening gel layer (fresh gel is added to form a continuous medium), and the lower layer is a pre-treated bulletproof fabric layer. The three layers are stacked and aligned in sequence to form a sandwich structure pre-composite, ensuring that each layer is bonded without wrinkles or misalignment, laying the foundation for subsequent hot-pressing composite molding.

[0031] The advantages are: by adding fresh gel as a continuous medium, it can ensure that there are no air gaps or delamination between the three-layer interfaces; the flat stacking and misalignment-free design ensures uniform stress distribution during subsequent hot pressing, thereby avoiding local defects; the sandwich structure provides a clear physical path for stress wave transmission and electrical signal generation during impact.

[0032] Specifically, in step six, hot-pressing composite molding involves placing the stacked pre-composite material into a hot press for hot-pressing composite curing. The core process parameters are: hot-pressing temperature 80-120℃ (preferably 100℃), hot-pressing pressure 0.5-2MPa (preferably 1MPa), and holding time 10-30 minutes (preferably 15 minutes). This process tightly bonds the conductive sensing layer, shear-thickening gel layer, and bulletproof fabric layer into a unified composite material under high temperature and pressure.

[0033] The advantages are: the polyurethane substrate softens and cross-links at 80-120℃, forming an interface fusion with the PEG matrix in STG; the pressure of 0.5-2MPa ensures that the three layers of materials are in close contact, thus forming an integrated composite structure; the heat and pressure are maintained for 10-30 minutes to allow the molecular chains of each layer to fully diffuse and interpenetrate, enhancing the interlayer bonding force and avoiding delamination failure during use.

[0034] An application of a shear-thickening self-sensing material: A shear-thickening self-sensing material (as a core functional layer) prepared according to the above method is applied to an intelligent bulletproof vest system. The specific application method is as follows: (1) As a protective-sensing integrated insert or flexible lining for bulletproof vests, it replaces traditional multi-layer aramid or ultra-high molecular weight polyethylene fabrics, reducing the total weight of bulletproof vests by 50% compared to traditional solutions under the same protection level; (2) When subjected to high-speed impact from bullets or sharp objects, the shear-thickening gel in the middle layer of the material hardens instantly, which enhances energy absorption on the one hand and compresses the upper conductive sensing layer to generate resistance / capacitance change signals on the other hand, realizing self-sensing of the bullet impact event without the need for an external acceleration sensor. (3) The electrical signal output by the material is connected to the multimodal signal acquisition system (high frequency piezoelectric channel + low frequency strain channel) integrated in the bulletproof vest, which provides impact waveform features for the 1D-CNN-LSTM neural network to identify the type of bullet (pistol bullet, rifle bullet, shotgun bullet, bayonet) and distinguish false alarms; (4) When the shot signal is confirmed, the UWB self-organizing network module and IMU module embedded in the bulletproof vest will automatically trigger the "shot and knocked down" judgment and send a distress signal and real-time location information to the command center and surrounding teammates. The intelligent bulletproof vest system is suitable for individual combat by military and police personnel, counter-terrorism and emergency response, and high-risk civilian security scenarios.

[0035] The shear-thickening self-sensing material prepared according to the present invention was applied in the following examples: Example 1 (Testing of the protective and piezoresistive response performance of shear-thickening self-sensing composite materials) Sample preparation: Sample preparation (following steps one through seven) Step 1: Raw material preparation: (1) Bulletproof fabric layer: Kevlar 129 aramid fiber fabric with an areal density of 200 g / m 2 ; (2) Inorganic oxide particles: Nano-sized silicon dioxide (SiO2) is selected, and the particle size is controlled to be 100-500nm (preferably 200-300nm). (3) Polymer matrix: Polyethylene glycol (PEG200) is selected; (4) Conductive filler: Carbon nanotubes (CNTs) with a diameter of 10-20 nm and a length of 5-30 μm are selected; (5) Conductive layer substrate: Polyurethane solution (30% solid content) is selected. Step 2, preparation of shear-thickening gel (STG): Nano-SiO2 particles were dispersed in PEG200 at a mass fraction of 30%, and ultrasonically dispersed for 45 minutes using an ultrasonic cell disruptor (300W, intermittent mode) to ensure uniform dispersion of particles without agglomeration, resulting in a uniform, milky-white shear-thickening gel (STG). At low shear rates, it is a flowable slurry, while at high shear rates, it exhibits a solid-like thickening. Step 3: Preparation of the conductive sensing layer: Carbon nanotubes (CNTs) are uniformly dispersed in a polyurethane solution at a mass fraction of 10%. The mixture is stirred and ultrasonically dispersed for 30 minutes. An automatic coating machine (scalpel type) is used to coat the mixture onto a release film, controlling the wet film thickness. After drying, a flexible conductive film with a thickness of 0.2 mm is obtained. The film is then placed in a forced-air drying oven and dried at 70°C for 2 hours to completely remove the solvent, yielding the finished conductive sensing layer. Its surface resistivity is ≤10 kΩ / sq, exhibiting good flexibility and piezoresistive sensitivity. Step 4: Bulletproof Fabric Impregnation Treatment (Gradient Content): The Kevlar 129 aramid fabric is completely immersed in the STG prepared in Step 2. A multiple impregnation-extrusion process is used to control the amount of gel adhesion, achieving a gradient distribution along the thickness direction of the composite material: Near the conductive sensing layer (upper layer): the shear-thickening gel mass fraction is 20%; in the intermediate transition zone: the gel content gradually increases by controlling the number of impregnations and the pressure of the extrusion rollers; near the bulletproof fabric layer (lower layer): the shear-thickening gel mass fraction reaches 40%. After impregnation, the fabric is placed in a 55-60℃ oven and dried for 1.5-2 hours to remove moisture and residual solvent, resulting in a pretreated bulletproof fabric layer (with a gradient distribution of 20%→40% in the thickness direction). Step 5, Stacking and Laying: Following the order of the upper layer being the conductive sensing layer, the middle layer being the additional fresh STG (as a continuous medium), and the lower layer being the pre-treated bulletproof fabric layer, stack the three layers flat and aligned in sequence. The amount of additional STG used in the middle layer is 50g / m³. 2 The coating is applied evenly to ensure that there are no air gaps, wrinkles, or misalignments at the interface, forming a pre-composite with a sandwich structure. Step 6: Hot-pressing composite molding: Place the stacked pre-composite into a flat hot press and set the hot pressing parameters: temperature 100℃; pressure 1MPa; heat preservation and pressure holding time 15 minutes. Under high temperature and high pressure, the polyurethane substrate softens appropriately and fuses with the PEG matrix interface. The three layers of materials are tightly bonded together. After cooling, an integrated shear-thickening self-sensing composite material is obtained.

[0036] Test method: (1) Drop hammer impact test: A drop hammer impact tester was used with an impact energy of 50J to compare the peak force and energy absorption rate of pure Kevlar (14 layers) and this composite material (4 layers of STG-Kevlar + conductive layer); (2) Piezoresistive response test: The rate of change of resistance of the conductive sensing layer and the response time were recorded synchronously during the impact process; (3) Cyclic impact test: Repeat the impact 3 times at the same position and observe the reproducibility of the resistance signal.

[0037] Test results: The peak force of this composite material is reduced by 35% compared with pure Kevlar, and the energy absorption rate is increased by 42%; the instantaneous resistance change rate reaches 180%, and the response time is 0.8ms; the waveform consistency of the resistance signal after three cycles of impact is good (waveform correlation coefficient > 0.92), indicating that the material can be reused.

[0038] Conclusion: The material of this invention maintains or even enhances protective performance while reducing the number of layers, and has a rapid and reproducible self-sensing response capability.

[0039] In summary, Example 1 verifies the excellent performance of the shear-thickened self-sensing composite material prepared in this invention in terms of both protective and self-sensing properties. Compared with pure Kevlar (14 layers), only 4 layers of STG-Kevlar composite structure are needed to achieve a 35% reduction in peak force and a 42% increase in energy absorption rate, proving that the material enhances impact energy absorption capacity while significantly reducing the number of fabric layers (by 71%). Simultaneously, the instantaneous resistance change rate upon impact reaches 180%, and the response time is only 0.8 ms, indicating that the material possesses rapid and sensitive self-sensing response characteristics. The signal consistency after three cycles of impact is good (correlation coefficient > 0.92), verifying the reusability of the material. Therefore, the material of this invention can successfully achieve integrated protection and sensing functions, providing a reliable material basis for the bulletproof vest system's hit detection, automatic alarm, and other functions.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a shear-thickening self-sensing material, characterized in that, Includes the following steps: Step 1: Raw material preparation and component pretreatment: Select the bulletproof fabric layer substrate, prepare the shear thickening gel raw material composed of inorganic oxide particles and polyethylene glycol polymer matrix, and prepare the conductive sensing layer raw material composed of conductive filler and polyurethane solution. Weigh and pretreat each raw material separately. Step 2, preparation of shear-thickening gel: Inorganic oxide particles are dispersed in a polyethylene glycol polymer matrix and ultrasonically treated to obtain a shear-thickening gel; Step 3: Preparation of conductive sensing layer: Disperse conductive filler in polyurethane solution, coat it into a film and dry it to obtain conductive sensing layer; Step 4, bulletproof fabric impregnation treatment: The bulletproof fabric substrate is completely immersed in the shear thickening gel prepared in Step 2. Multiple impregnation-extrusion processes are used to control the amount of gel adhering to the fabric surface and interior. Then it is dried to obtain the pretreated bulletproof fabric layer. Step 5: Stacking and Composite: Following the sandwich structure, stack the three layers of materials in an orderly manner to form a pre-composite body; Step 6: Hot-press composite molding: The three-layer materials are integrated and composited through temperature and pressure control processes to obtain a composite board. Step 7, Post-processing and molding: After hot pressing, the composite board is removed and placed in a dust-free environment at room temperature to cool and set naturally. After trimming the appearance, the shear-thickening self-sensing material is obtained.

2. The method for preparing a shear-thickening self-sensing material according to claim 1, characterized in that, In step one: the bulletproof fabric layer substrate is ultra-high molecular weight polyethylene fiber fabric or has a surface density of 200-220 g / m². 2 Aramid fiber fabric.

3. The method for preparing a shear-thickening self-sensing material according to claim 1, characterized in that, The inorganic oxide particles are selected from either nano-silica or calcium carbonate, and their particle size is controlled between 100-500 nm; the conductive filler is selected from either carbon nanotubes or graphene.

4. The method for preparing a shear-thickening self-sensing material according to claim 1, characterized in that, In step two: Inorganic oxide particles are dispersed in a polyethylene glycol polymer matrix and ultrasonically treated for 30-60 minutes to obtain a shear-thickened gel. The mass fraction of inorganic oxide particles in the gel is controlled at 20%-40%.

5. The method for preparing a shear-thickening self-sensing material according to claim 1, characterized in that, In step three: 5%-15% by mass of conductive filler is uniformly dispersed in a polyurethane solution, and a flexible conductive film with a thickness of 0.1-0.3 mm is prepared by coating film forming process. After drying at 60-80℃ for 1-3 hours, the finished conductive sensing layer is obtained.

6. The method for preparing a shear-thickening self-sensing material according to claim 1, characterized in that, In step four, the bulletproof fabric is impregnated by completely immersing the bulletproof fabric substrate in the shear-thickening gel prepared in step two. The amount of gel adhering to the fabric surface and inside is controlled by multiple impregnation-extrusion processes, and the shear-thickening gel content is controlled to be 20%-40%. Then, it is dried at 55-60℃ for 1.5-2 hours to obtain the pretreated bulletproof fabric layer.

7. The method for preparing a shear-thickening self-sensing material according to claim 5, characterized in that, The shear thickening gel content parameter in step four is as follows: the mass fraction of shear thickening gel near the conductive sensing layer is 20%, gradually increasing along the thickness direction, reaching 40% near the bulletproof fabric layer.

8. The method for preparing a shear-thickening self-sensing material according to claim 1, characterized in that, In step five, the materials are stacked and aligned in sequence: the upper layer is a conductive sensing layer, the middle layer is a shear-thickening gel layer, and the lower layer is a pre-treated bulletproof fabric layer, to form a sandwich-structured pre-composite.

9. The method for preparing a shear-thickening self-sensing material according to claim 1, characterized in that, The pre-composite material stacked in step six is ​​placed in a hot press for hot pressing and curing. The process parameters are set as follows: hot pressing temperature 80-120℃, hot pressing pressure 0.5-2MPa, and heat and pressure holding time 10-30 minutes.

10. An application of a shear-thickening self-sensing material, characterized in that, The shear-thickening self-sensing material prepared according to claim 1 is applied to a smart bulletproof vest system.

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