A spray polyurea inner panel-free civil air defense equipment

Abstract

The present application belongs to the field of civil air defense engineering and anti-blast protection technology, and relates to a non-internal panel civil air defense equipment sprayed with polyurea, comprising a force-bearing outer panel, a reinforcing framework, an elastic damping connecting piece, an internal pouring body, an arc-shaped elastic support rod and a support plate; the arc-shaped protruding arc surface of the arc-shaped elastic support rod is in contact with the inner side of the support plate, so that the arc-shaped elastic support rod is forced to elastically compress and deform; the arc-shaped structure design of the arc-shaped elastic support rod makes it produce a progressive stiffness response when being compressed: in the initial stage, the arc-shaped structure is easy to deform, providing a larger displacement stroke to absorb energy; as the compression amount increases, the stiffness of the arc-shaped elastic support rod gradually increases, effectively inhibiting excessive deformation. The arc-shaped elastic support rod produces a reaction force to the reinforcing framework during the deformation process, and the reaction force is uniformly dispersed to the internal pouring body through the three-dimensional grid structure of the reinforcing framework; the structural design is scientific and reasonable, the use is convenient, the protection performance is excellent, and the application environment is friendly.

Description

Technical Field

[0001] This invention belongs to the field of civil defense engineering and explosion-proof protection technology. It relates to a civil defense device without an inner panel that is coated with polyurea. In particular, it aims to prepare a new type of anti-theft and damage-resistant door structure with new materials and structure, realize an integrated structure and save raw materials for civil defense devices, and replace existing technology products. Background Technology

[0002] Traditionally, air-raid shelter doors or blast doors typically consist of two layers of steel panels on the front and back, with concrete or cushioning material filling the space between them, forming a "sandwich" structure. From a protective performance perspective, this structure is indeed reliable and can withstand external impacts and damage to a certain extent. However, it also brings significant drawbacks. Due to its enormous weight, it presents numerous inconveniences in actual use and operation. Furthermore, it consumes a large amount of materials, especially steel, which not only increases costs but also wastes resources. Simultaneously, its production process is highly complex, involving multiple stages and steps, requiring substantial investment of manpower, resources, and time. Transportation and installation also present significant difficulties, necessitating specialized equipment and personnel.

[0003] The performance improvement mainly relies on increasing the thickness of the steel plate and the weight of the structure. However, this method has a very low efficiency ratio, meaning that the cost invested is not proportional to the protective effect obtained, which does not conform to the trend of modern equipment development towards lightweight and high performance.

[0004] At the same time, new requirements have been put forward for the technological development of civil defense equipment. Related enterprises and research institutions are carrying out technological innovations with the aim of improving product performance while conserving resources. Therefore, there is an urgent need in this field for a new type of civil defense equipment that can significantly reduce its weight, simplify its structure, and facilitate customized production to meet the needs of different scenarios and users, while ensuring or even improving the protection level; moreover, it must also have excellent blast-resistant energy absorption characteristics on the basis of lightweight design.

[0005] Polyurea elastomers, as a novel polymeric protective material, have demonstrated unique application value in the field of military protection in recent years. Its molecular structure consists of alternating soft and hard segments forming a microphase-separated structure. The soft segments provide excellent flexibility and elastic recovery, while the hard segments impart sufficient strength and wear resistance. When an explosive shock wave acts on the surface of the polyurea coating, the polymer chains within the material rapidly orient and slip, converting the impact kinetic energy into heat dissipation through intermolecular friction. Simultaneously, the coating's large deformation capacity effectively delays crack propagation, preventing brittle fracture of the load-bearing outer panel. Compared to traditional steel panels, the areal density of polyurea coatings is only about one-tenth that of steel, yet it provides comparable or even superior blast resistance under the same thickness conditions. This provides a crucial material basis for the design of structures without inner panels. Traditional air-raid shelter doors often use a structure welded from a steel frame to inner and outer panels. This structure not only has a cumbersome production process and numerous quality control points, but also results in a large door weight and high material consumption.

[0006] To address the aforementioned shortcomings, existing technologies have proposed various improvement schemes. For example, Chinese patent document CN111188562A discloses an integrated cast steel air-raid shelter door structure, which uses a casting process to integrally cast the inner panel, main beam, secondary beam, and door frame, completely eliminating the outer panel. This scheme simplifies the process, improves the overall precision and flatness of the door leaf, and effectively reduces weight. However, this structure is a rigid, integral cast steel component, lacking an effective buffering and energy dissipation mechanism when facing dynamic loads such as blast shock waves, potentially limiting its shock wave resistance and tolerance to repeated impacts. Furthermore, the large, integrally cast components present certain challenges in terms of transportation and on-site installation flexibility.

[0007] Another Chinese patent document, CN110924824B, discloses a steel structure air-raid shelter door and its processing technology. It adopts a modular design, dividing the door body into a detachable frame and prefabricated concrete modules, facilitating transportation and on-site assembly. However, in this design, the protective function mainly relies on the weight of the concrete modules themselves and their mechanical connection to the steel frame. The connections between components are rigid or semi-rigid, making these connections vulnerable to high-intensity, high-frequency impacts. Furthermore, the overall structure lacks sufficient design for energy absorption and stress wave dissipation, making it difficult to meet the extremely high requirements for blast resistance in application scenarios.

[0008] In summary, while existing technologies have made progress in lightweighting and modularizing air-raid shelter doors, significant shortcomings remain in systematically improving the energy dissipation efficiency, interface reliability, overall intelligent response capabilities, and ease of on-site construction of door panels under extreme dynamic loads such as explosions. Therefore, an innovative solution is urgently needed that, while inheriting the advantages of modularity and lightweighting, incorporates technologies such as multi-level buffering, active energy dissipation, intelligent sensing, and high-performance composite material protection to comprehensively enhance the overall protective performance, environmental adaptability, and production and installation efficiency of air-raid shelter equipment. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art, solve the technical problems of excessive weight, high material consumption, complex production process and low efficiency of traditional civil defense equipment, and at the same time meet the development needs of lightweight and high performance of modern protective equipment, and provide a civil defense equipment without inner panel with sprayed polyurea.

[0010] To achieve the aforementioned objectives, this invention provides a polyurea-coated, panelless civil defense device. Its main structure includes a load-bearing outer panel, a reinforcing frame, elastic damping connectors, an internal cast-in-place body, arc-shaped elastic support rods, and a support plate. The load-bearing outer panel and the three-dimensional mesh-like reinforcing frame are non-rigidly connected via the elastic damping connectors. The arc-shaped elastic support rods are pre-installed within the cavity of the reinforcing frame before the internal cast-in-place body is poured. The arc-shaped elastic support rods are evenly spaced within the cavity of the reinforcing frame. The arc-shaped elastic support rods bulge towards the load-bearing outer panel, and both ends of the arc-shaped elastic support rods are supported on the inner wall of the cavity of the reinforcing frame. The support plate engages with the frame of the reinforcing frame near the load-bearing outer panel, and the inner side of the support plate abuts against the arc-shaped protruding surface of the arc-shaped elastic support rods. The internal cast-in-place body is poured into the cavity of the reinforcing frame. The outer surface of the load-bearing outer panel is coated with a continuous polyurea elastomer protective coating.

[0011] In the application of this invention, when the explosive shock wave acts on the load-bearing outer panel, the impact load is initially dissipated by the continuous polyurea elastomer protective coating. Due to its excellent tensile strength and elongation at break, the polyurea elastomer can undergo large deformations in a very short time without breaking. Through the stretching, orientation, and friction of the molecular chains, it converts the impact kinetic energy into heat energy, significantly weakening the peak pressure of the shock wave. Subsequently, the remaining impact energy is transferred to the load-bearing outer panel. Since the load-bearing outer panel and the reinforcing frame are non-rigidly connected through elastic damping connectors, these connectors allow for controllable relative displacement between the two, forming a first buffer mechanism to prevent the impact load from being directly and rigidly transferred to the main structure.

[0012] In application of this invention, the load-bearing outer panel deforms inward under impact, pushing the support plate into the reinforcing skeleton. The inner side of the support plate abuts against the arc-shaped protruding surface of the arc-shaped elastic support rod, forcing the arc-shaped elastic support rod to undergo elastic compression deformation. The arc-shaped structure design of the arc-shaped elastic support rod enables it to produce a progressive stiffness response under compression: in the initial stage, the arc-shaped structure is easy to deform, providing a large displacement stroke to absorb energy; as the compression increases, the stiffness of the arc-shaped elastic support rod gradually increases, effectively suppressing excessive deformation. The two ends of the arc-shaped elastic support rod are supported on the inner wall of the cavity of the reinforcing skeleton, and its deformation process generates a reaction force on the reinforcing skeleton. This reaction force is evenly distributed to the internal casting through the three-dimensional grid structure of the reinforcing skeleton.

[0013] The internal cast-in-place structure involved in this invention utilizes high-performance fiber-reinforced concrete or polymer-modified concrete, forming a composite load-bearing system under the constraint of arc-shaped elastic support rods and a reinforcing skeleton. The three-dimensional grid structure of the reinforcing skeleton not only improves the integrity and crack resistance of the internal cast-in-place structure but also works in conjunction with it to jointly bear and transmit impact loads. The elastic damping connector continuously dissipates energy during the relative movement between the load-bearing outer panel and the reinforcing skeleton, further absorbing vibration energy through the hysteresis effect of its viscoelastic material, thus reducing the structure's dynamic response.

[0014] In the application of this invention, after the impact load is removed, the arc-shaped elastic support rod pushes the support plate and the load-bearing outer panel to spring back to their original position using its elastic restoring force. The elastic damping connector also provides a restoring torque to assist in the structural reset, giving the protective equipment the characteristic of being reusable. Throughout the entire working process, the continuous polyurea elastomer protective coating, the load-bearing outer panel, the elastic damping connector, the support plate, the arc-shaped elastic support rod, the reinforcing frame, and the internal casting form a multi-level synergistic blast-resistant protection system, realizing the layered dissipation of impact energy and effective control of structural deformation, significantly improving the blast-resistant performance and survivability of civil defense equipment.

[0015] The internal casting body involved in this invention adopts a zoned composite casting method, and the energy-consuming cavity in different locations is filled with impact-resistant materials with different properties; the cavity in the central area that is directly subjected to impact is filled with a first impact-resistant material, which is fiber-reinforced polymer mortar; the secondary surrounding areas are filled with a second impact-resistant material, which is high-strength concrete.

[0016] In the application of this invention, when the explosive shock wave acts on the central area of ​​the load-bearing outer panel, the corresponding support plate and arc-shaped elastic support rod bear the maximum impact load. The arc-shaped elastic support rod transfers the impact energy to the first impact-resistant material within the central cavity. Fiber-reinforced polymer mortar, with its high toughness and excellent bonding properties, effectively inhibits crack initiation and propagation through the synergistic effect of the fiber and polymer matrix. It absorbs a large amount of impact energy through the bridging effect of the fibers and the viscoelastic deformation of the polymer, forming a localized high-energy-dissipation zone. Simultaneously, the severe deformation of the central area is transmitted to the surrounding areas through the three-dimensional grid structure of the reinforced skeleton. However, since the secondary areas are filled with high-strength concrete, which has a higher elastic modulus and relatively lower deformation capacity, it provides stable stiffness support for the overall structure, limiting the excessive deformation of the central area from spreading to the edges and ensuring the overall stability of the structure.

[0017] The partitioned composite casting design of this invention enables optimized functional matching of protective equipment in different areas: the central area primarily dissipates energy, extending the impact time and reducing peak stress through the large deformation capacity of fiber-reinforced polymer mortar; the peripheral area primarily bears load, maintaining the structural geometry using the high compressive strength of high-strength concrete. The grid separation of the reinforcing skeleton ensures effective bonding between the two materials, preventing delamination under impact loads. The differentiated deformation response of the arc-shaped elastic support rods in the central and peripheral areas further enhances this partitioned energy dissipation effect. The arc-shaped elastic support rods in the central area deform more significantly, fully utilizing their nonlinear stiffness characteristics, while the arc-shaped elastic support rods in the peripheral areas deform less, primarily serving load transfer and structural repositioning functions. This partitioned composite casting strategy significantly improves material utilization efficiency, reducing overall weight and cost while ensuring blast resistance.

[0018] The arc-shaped elastic support rod of this invention has a cross-sectional shape of circular, elliptical, or rectangular, and is made of spring steel, fiber-reinforced composite material, or shape memory alloy. The ratio of arc height to chord length is 1:5 to 1:10, and the wall thickness or diameter is selected within the range of 3mm to 15mm according to the designed explosion-proof level. The arc-shaped elastic support rod made of spring steel has the advantages of low cost and mature technology, and is suitable for conventional protection level requirements. The arc-shaped elastic support rod made of fiber-reinforced composite material is lightweight and high-strength, suitable for occasions with strict weight restrictions on equipment. The arc-shaped elastic support rod made of shape memory alloy possesses superelastic deformation capability and self-resetting characteristics, and can completely restore its original shape after undergoing large deformation, significantly improving the reusability of the equipment. The optimized design of the arc height to chord length ratio ensures that the arc-shaped elastic support rod provides sufficient deformation stroke while possessing reasonable load-bearing capacity and stability.

[0019] The elastic damping connector of this invention includes a metal connecting plate, a viscoelastic damping layer, and a preload bolt assembly. The metal connecting plate is fixedly connected to the inner surface of the load-bearing outer panel and the outer frame of the reinforcing skeleton, respectively. The viscoelastic damping layer is sandwiched between two metal connecting plates and is made of butyl rubber, neoprene rubber, or high-damping silicone rubber, with a thickness of 3mm to 8mm. The preload bolt assembly penetrates the metal connecting plate and the viscoelastic damping layer, and the initial stiffness and energy dissipation capacity of the elastic damping connector are controlled by adjusting the preload force. The preload bolt assembly is made of high-strength stainless steel, and a disc spring washer is placed between the bolt head and the metal connecting plate to maintain the stability of the preload force during long-term service. The dynamic shear modulus and loss factor of the viscoelastic damping layer are controlled according to the target blast resistance performance through material formulation and vulcanization process to achieve optimal energy dissipation effect within the typical frequency range of explosive impact.

[0020] The support plate of this invention has a flexible energy dissipation layer on its outer surface, which forms a gap fit with the inner surface of the load-bearing outer panel. The flexible energy dissipation layer is made of high-damping rubber or polyurethane foam, with a thickness of 5mm to 20mm and a Shore hardness controlled within the range of 30A to 60A. When the load-bearing outer panel is impacted and deforms inward, the flexible energy dissipation layer first contacts the load-bearing outer panel and undergoes compression deformation, absorbing part of the impact energy using its high damping characteristics, while simultaneously avoiding rigid collisions between the load-bearing outer panel and the support plate. The gap fit design of the flexible energy dissipation layer provides initial deformation space for the load-bearing outer panel, ensuring that the polyurea elastomer protective coating and the load-bearing outer panel can fully exert their energy dissipation function, achieving phased and orderly energy absorption.

[0021] The reinforcing skeleton of this invention is a three-dimensional grid structure formed by welding crisscrossing steel sections or steel pipes. The grid size is 500mm×500mm to 1000mm×1000mm, and the cavity depth of the reinforcing skeleton 2 is 80mm to 200mm. The three-dimensional grid structure of the reinforcing skeleton provides a three-dimensional constraint effect for the internal cast-in-place material, effectively suppressing brittle cracking and fragmentation of concrete under impact loads. Shear keys or roughening treatment are provided at the contact points between the frame of the reinforcing skeleton and the internal cast-in-place material to enhance the bond strength and anti-slip capability between the two. A locking groove adapted to the support plate is opened on the frame of the reinforcing skeleton near the load-bearing outer panel. The locking groove depth is 10mm to 20mm. The edge of the support plate is embedded in the locking groove for positioning, while allowing the support plate to slip to a limited extent along the locking groove direction under impact, preventing the support plate from dislodging under extreme deformation.

[0022] The continuous polyurea elastomer protective coating of this invention has a thickness of 2mm to 5mm and is formed by the reaction and curing of isocyanate semi-prepolymer with terminal amino polyether and amine chain extender through a spraying process. The continuous polyurea elastomer protective coating has a tensile strength of not less than 16MPa, an elongation at break of not less than 300%, a tear strength of not less than 50kN / m, and an adhesion to the load-bearing outer panel of not less than 2.5MPa. Before spraying, the surface of the load-bearing outer panel is sandblasted to Sa2.5 grade and treated with a special primer. During the spraying process, a two-component high-pressure airless spraying device is used, with the raw material temperature controlled at 65℃ to 75℃ and the spraying pressure at 15MPa to 25MPa to ensure that the coating is formed in one step without seams. The continuous polyurea elastomer protective coating not only acts as the first line of defense to dissipate impact energy but also provides excellent corrosion resistance, wear resistance, and aging resistance protection for the load-bearing outer panel, extending the service life of the equipment.

[0023] The load-bearing outer panel of this invention is made of high-strength low-alloy steel plate or fiber-reinforced metal laminate, with a thickness of 6mm to 20mm. Its outer surface is a continuous smooth curved surface or a curved surface structure with shallow ribs. High-strength low-alloy steel plate has excellent strength, toughness, and weldability, making it suitable for most protection scenarios. Fiber-reinforced metal laminate achieves a synergistic improvement in in-plane stiffness and impact resistance by embedding fiber-reinforced composite material layers between the metal layers. The curved surface structure design helps guide the flow and reflection of the blast shock wave, reducing local peak pressure, while enhancing the overall stiffness and dent resistance of the load-bearing outer panel. The four edges of the load-bearing outer panel are provided with a flanged structure, forming an overlapping fit with the peripheral frame of the protective equipment to ensure overall stability under impact.

[0024] The support plate described in this invention is a channel-shaped or corrugated component formed by stamping steel plate, and the material of the support plate is spring steel. Its flanges engage with the grooves of the frame of the reinforcing skeleton and a sliding gap is reserved. The thickness of the support plate is 3mm to 8mm, and its surface is provided with small holes for pouring and venting, with a hole diameter of 8mm to 15mm and an opening ratio of 5% to 15%. The channel-shaped or corrugated cross-section design of the support plate significantly improves its out-of-plane stiffness and resistance to local buckling, ensuring stable force transmission performance under the reaction force of the arc-shaped elastic support rod. The selection of spring steel material gives the support plate a certain elastic deformation capacity, which can absorb additional energy through its own plastic deformation under extreme impact conditions, serving as the last line of defense for the structure. The reserved sliding gap allows the support plate to slide controllably relative to the frame of the reinforcing skeleton during impact, avoiding stress concentration caused by boundary constraints. The small vent holes on the surface of the support plate serve to remove air from the cavity during the pouring of the internal casting, preventing air pore defects from affecting the overall structure. At the same time, the presence of the small holes allows the concrete slurry to penetrate the support plate and form a mechanical interlock, enhancing the reliability of the connection between the support plate and the internal casting.

[0025] The support plate described in this invention can also be a hollow aluminum profile, with its internal cavity filled with foamed aluminum or aluminum foam material. The aluminum profile has a wall thickness of 2mm to 5mm, and its outer surface is anodized to form an oxide film layer with a thickness of 10μm to 25μm. The hollow aluminum profile structure significantly reduces the self-weight of the support plate while ensuring sufficient rigidity, making it suitable for applications sensitive to the overall weight of the equipment. The foamed aluminum or aluminum foam filling material has excellent energy absorption characteristics; its unique cellular structure achieves progressive energy dissipation under pressure through the bending, folding, and densification of the cell walls, forming a series energy dissipation mechanism with the arc-shaped elastic support rod. The dense oxide film layer formed by the anodizing treatment gives the aluminum profile excellent corrosion resistance and surface hardness, ensuring the long-term service performance of the support plate in humid or corrosive environments. The cross-sectional shape of the aluminum profile is designed as a rectangular or irregular structure with reinforcing ribs, and the arrangement direction of the reinforcing ribs corresponds to the support points of the arc-shaped elastic support rod to optimize local load-bearing capacity and force transmission path.

[0026] This invention also provides a method for manufacturing a panelless civil defense device with sprayed polyurea coating, the main process of which includes the following steps:

[0027] S1. Preparation of load-bearing outer panel: Select high-strength low-alloy steel plate or fiber-reinforced metal laminate, and make the load-bearing outer panel of the design shape by cutting, bending and forming and edge flanging. Then, sandblasting and rust removal and primer coating are performed on its outer surface.

[0028] S2. Preparation of the reinforcing skeleton: Cut the steel profiles or steel pipes to the design dimensions and assemble them into a three-dimensional grid-like reinforcing skeleton by welding. On the side of the reinforcing skeleton near the load-bearing outer panel, a groove for engaging the support plate is precision machined.

[0029] S3. Install arc-shaped elastic support rods: Arrange the arc-shaped elastic support rods at the designed spacing in the cavity of the reinforcing frame, so that both ends are supported and fixed on the inner wall of the cavity of the reinforcing frame, and the arc shape protrudes towards the load-bearing outer panel.

[0030] S4. Install the support plate: Fit the support plate into the groove of the reinforcing frame, and adjust the position so that the inner side of the support plate is in close contact with the arc-shaped protruding arc surface of the arc-shaped elastic support rod.

[0031] S5. Install elastic damping connectors: Fix metal connecting plates at corresponding positions on the inner surface of the load-bearing outer panel and the outer frame of the reinforcing frame, clamp the viscoelastic damping layer, and then assemble them into elastic damping connectors by pre-tightening bolt assemblies to achieve a non-rigid connection between the load-bearing outer panel and the reinforcing frame.

[0032] S6. Pouring the internal casting body: Pour high-performance fiber-reinforced concrete or polymer-modified concrete into the cavity of the reinforcing skeleton, and use an immersion vibrator to compact it in layers, and cure it to the design strength.

[0033] In step S6, the pouring of the internal casting body is carried out in two stages. The first pouring is carried out to 2 / 3 of the height of the reinforcing skeleton cavity, and the second pouring is carried out to the design height before the concrete initially sets. The interval between the two pouring is controlled between 30 and 60 minutes to ensure good interlayer bonding.

[0034] S7. Spraying polyurea protective coating: After the internal cast body reaches the design strength, a continuous polyurea elastomer protective coating is sprayed onto the outer surface of the load-bearing outer panel using a two-component high-pressure airless spraying device. The coating thickness is controlled to be uniform and consistent, and a complete protective system is formed after curing.

[0035] In step S7, the ambient temperature for spraying is controlled between 10°C and 35°C, the relative humidity is below 85%, and the surface temperature of the substrate is more than 3°C above the dew point temperature. The coating is applied in 2 to 3 coats, with the interval between each coat adjusted according to the ambient temperature and humidity to ensure full bonding between layers and that the total thickness meets the design requirements.

[0036] Compared with existing technologies, this invention offers at least the following advantages: First, it constructs a multi-layered energy dissipation mechanism through a combined support system of arc-shaped elastic support rods and support plates. The nonlinear stiffness characteristics of the arc-shaped elastic support rods enable them to play a suitable energy dissipation role under different impact intensities, providing elastic support during small deformations and absorbing a large amount of energy during large deformations by entering a plastic strengthening stage. The support plate, as an intermediate force transmission component, ensures effective contact between the arc-shaped elastic support rods and the load-bearing outer panel, and also achieves additional energy absorption through its own deformation or the densification of the pores in the filling material. The gap fit design of the flexible energy dissipation layer further realizes the phased and orderly energy absorption, avoiding mutual interference between various energy-dissipating components. Second, it adopts a zoned composite casting strategy, configuring fiber-reinforced polymer mortar and high-strength concrete in the central area and the peripheral secondary areas respectively, fully leveraging the mechanical properties of different materials to achieve precise design of blast resistance. The central area is dominated by high-toughness materials, which prolong the impact time and reduce peak stress through large deformation capacity; the peripheral area is supported by high-strength materials to ensure structural geometric stability and overall stiffness. This synergistic optimization of material functional zoning and structural component layout significantly improves material utilization efficiency, effectively controlling equipment weight and manufacturing costs while ensuring protective performance. Thirdly, the use of sprayed polyurea elastomer as the outer protective coating combines multiple functions such as energy dissipation, corrosion resistance, and wear resistance. The high elongation at break and excellent adhesion of polyurea material ensure that it does not crack or peel off during large deformations of the load-bearing outer panel, thus continuously providing protection. The seamless forming characteristics of the spraying process eliminate the weak points of traditional protective coatings, improving the reliability of the protective system. The rapid curing characteristics of the polyurea coating also help to shorten the manufacturing cycle and improve production efficiency. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the civil defense equipment without an inner panel, which is involved in this invention.

[0038] Figure 2 This is a schematic diagram of the internal structure of the civil defense equipment without an inner panel, which is involved in this invention.

[0039] Figure 3 yes Figure 2 A schematic diagram of the enlarged structure at point A in the middle.

[0040] Figure 4 This is a schematic diagram illustrating the structural principle of the internal casting body and the arc-shaped elastic support rod involved in this invention.

[0041] Figure 5 This is a schematic diagram illustrating the connection and arrangement structure of the arc-shaped elastic support rod involved in this invention.

[0042] Figure 6This is a schematic diagram illustrating the structural principle of the arc-shaped elastic support rod involved in this invention.

[0043] Figure 7 This is a schematic diagram of the structural principle of one embodiment of the support plate involved in the present invention; the diagram includes: a load-bearing outer panel 1, a reinforcing frame 2, an elastic damping connector 3, an internal casting body 4, an arc-shaped elastic support rod 5, a support plate 6, and a flexible energy dissipation layer 7. Detailed Implementation

[0044] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings.

[0045] Example 1:

[0046] This embodiment discloses a non-internal panel civil defense device with sprayed polyurea coating, such as... Figures 1 to 6 As shown, its main structure includes a load-bearing outer panel 1, a reinforcing frame 2, an elastic damping connector 3, an internal cast-in-place body 4, an arc-shaped elastic support rod 5, and a support plate 6. The load-bearing outer panel 1 and the three-dimensional mesh-like reinforcing frame 2 are non-rigidly connected by the elastic damping connector 3. The arc-shaped elastic support rod 5 is pre-installed in the cavity of the reinforcing frame 2 before the internal cast-in-place body 4 is poured. The arc-shaped elastic support rod 5 is evenly spaced in the cavity of the reinforcing frame 2. The arc-shaped elastic support rod 5 protrudes towards the load-bearing outer panel 1, and both ends of the arc-shaped elastic support rod 5 are supported on the inner wall of the cavity of the reinforcing frame 2. The support plate 6 is engaged with the frame of the reinforcing frame 2 on the side close to the load-bearing outer panel 1, and the inner side of the support plate 6 abuts against the arc-shaped protruding arc surface of the arc-shaped elastic support rod 5. The internal cast-in-place body 4 is poured into the cavity of the reinforcing frame 2. The outer surface of the load-bearing outer panel 1 is sprayed with a continuous polyurea elastomer protective coating.

[0047] During operation, when the blast shock wave acts on the load-bearing outer panel 1, the impact load is initially dissipated by the continuous polyurea elastomer protective coating. Due to its excellent tensile strength and elongation at break, the polyurea elastomer can undergo large deformations in a very short time without breaking. Through the stretching, orientation, and friction of the molecular chains, it converts the impact kinetic energy into heat energy, significantly weakening the peak pressure of the shock wave. Subsequently, the remaining impact energy is transferred to the load-bearing outer panel 1. Since the load-bearing outer panel 1 and the reinforcing frame 2 are non-rigidly connected by an elastic damping connector 3, this connector allows for controllable relative displacement between the two, forming the first buffer mechanism and preventing the impact load from being directly and rigidly transferred to the main structure.

[0048] Under impact, the load-bearing outer panel 1 deforms inward, pushing the support plate 6 into the interior of the reinforcing skeleton 2. The inner side of the support plate 6 abuts against the arc-shaped protruding surface of the arc-shaped elastic support rod 5, forcing the arc-shaped elastic support rod 5 to undergo elastic compression deformation. The arc-shaped structure design of the arc-shaped elastic support rod 5 enables it to produce a progressive stiffness response under compression: in the initial stage, the arc-shaped structure is easy to deform, providing a large displacement stroke to absorb energy; as the compression increases, the stiffness of the arc-shaped elastic support rod 5 gradually increases, effectively suppressing excessive deformation. The two ends of the arc-shaped elastic support rod 5 are supported on the inner wall of the cavity of the reinforcing skeleton 2, and its deformation process generates a reaction force on the reinforcing skeleton 2. This reaction force is evenly distributed to the internal cast body 4 through the three-dimensional grid structure of the reinforcing skeleton 2.

[0049] The internal cast-in-place 4 is constructed using high-performance fiber-reinforced concrete or polymer-modified concrete, forming a composite load-bearing system under the constraint of the arc-shaped elastic support rod 5 and the reinforcing skeleton 2. The three-dimensional grid structure of the reinforcing skeleton 2 not only improves the integrity and crack resistance of the internal cast-in-place 4 but also works in conjunction with it to jointly bear and transmit impact loads. The elastic damping connector 3 continuously dissipates energy during the relative movement between the load-bearing outer panel 1 and the reinforcing skeleton 2, further absorbing vibration energy through the hysteresis effect of its viscoelastic material, thus reducing the structure's dynamic response.

[0050] After the impact load is removed, the arc-shaped elastic support rod 5, with its elastic restoring force, pushes the support plate 6 and the load-bearing outer panel 1 to spring back to their original positions. The elastic damping connector 3 also provides a restoring torque to assist in the structural reset, giving the protective equipment the characteristic of being reusable. Throughout the entire operation, the continuous polyurea elastomer protective coating, the load-bearing outer panel 1, the elastic damping connector 3, the support plate 6, the arc-shaped elastic support rod 5, the reinforcing frame 2, and the internal cast-in-place body 4 form a multi-level synergistic blast-resistant protection system, achieving layered dissipation of impact energy and effective control of structural deformation, significantly improving the blast resistance and survivability of the civil defense equipment.

[0051] The preparation process steps of the fiber-reinforced polymer mortar described in this embodiment are as follows:

[0052] ① Weigh out 350 parts of 42.5R ordinary Portland cement, 450 parts of quartz sand (40-70 mesh), 100 parts of fly ash (Class F, Grade II), and 50 parts of silica fume according to the mass ratio, and pour them into a forced mixer and dry mix for 2 minutes until they are evenly mixed.

[0053] ② Add 6 parts of polycarboxylate superplasticizer (20% solid content) and 1.5 parts of defoamer (organosilicon) to 160 parts of deionized water and stir to dissolve, forming a mixed solution;

[0054] ③ Slowly add the mixed solution to the dry material while stirring for 3 minutes. Then add 12mm long hook-shaped steel fibers (volume dosage 2%) and 6mm long basalt fibers (volume dosage 0.8%). Continue stirring for 4 minutes until the fibers are evenly dispersed. Control the spread of the fresh mortar to 220±10mm.

[0055] ④ Pour the mixed mortar into the energy-consuming cavity mold of the pre-set arch support, and vibrate it for 30 seconds with a high-frequency vibrator (vibration frequency 50Hz) to ensure that the mortar is fully filled to every corner. After covering the surface with plastic film, place it in a standard curing room (temperature 20±2℃, relative humidity ≥95%) for curing for 7 days, and then allow it to cure naturally for 21 days. Finally, a first impact-resistant material with compressive strength ≥85MPa, flexural strength ≥15MPa, and elastic modulus 38-42GPa is formed.

[0056] The internal casting body 4 adopts a zoned composite casting method, and the energy-consuming cavity at different locations is filled with impact-resistant materials with different properties; the cavity in the central area that is directly impacted is filled with a first impact-resistant material, which is fiber-reinforced polymer mortar; the secondary surrounding areas are filled with a second impact-resistant material, which is high-strength concrete.

[0057] During operation, when the shock wave from the explosion acts on the central area of ​​the load-bearing outer panel 1, the corresponding support plate 6 and arc-shaped elastic support rod 5 bear the maximum impact load. The arc-shaped elastic support rod 5 transfers the impact energy to the first impact-resistant material within the central cavity. Fiber-reinforced polymer mortar, with its high toughness and excellent bonding properties, effectively inhibits crack initiation and propagation through the synergistic effect of the fiber and polymer matrix. It absorbs a large amount of impact energy through the bridging effect of the fibers and the viscoelastic deformation of the polymer, forming a localized high-energy-dissipation zone. Simultaneously, the severe deformation in the central area is transmitted to the surrounding areas through the three-dimensional grid structure of the reinforcing skeleton 2. However, since the secondary areas are filled with high-strength concrete, which has a higher elastic modulus and relatively lower deformation capacity, it provides stable stiffness support for the overall structure, limiting the excessive deformation of the central area from spreading to the edges and ensuring the overall stability of the structure.

[0058] The zoned composite casting design enables optimized functional matching of the protective equipment in different areas: the central area primarily dissipates energy, extending the impact time and reducing peak stress through the large deformation capacity of fiber-reinforced polymer mortar; the peripheral area primarily bears load, maintaining the structural geometry using the high compressive strength of high-strength concrete. The grid separation of the reinforcing skeleton 2 ensures effective bonding between the two materials, preventing delamination under impact loads. The differentiated deformation response of the arc-shaped elastic support rods 5 in the central and peripheral areas further enhances this zoned energy dissipation effect. The arc-shaped elastic support rods 5 in the central area deform more significantly, fully utilizing their nonlinear stiffness characteristics, while the arc-shaped elastic support rods 5 in the peripheral areas deform less, mainly serving the functions of load transfer and structural repositioning. This zoned composite casting strategy significantly improves material utilization efficiency, reducing overall weight and cost while ensuring blast resistance.

[0059] like Figure 6 As shown, the cross-sectional shape of the arc-shaped elastic support rod 5 is one of circular, elliptical, or rectangular, and its material is spring steel, fiber-reinforced composite material, or shape memory alloy. The ratio of the arc height to the chord length of the arc-shaped elastic support rod 5 is 1:5 to 1:10, and the wall thickness or diameter is selected within the range of 3mm to 15mm according to the design explosion-proof level. The arc-shaped elastic support rod 5 made of spring steel has the advantages of low cost and mature technology, and is suitable for conventional protection level requirements; the arc-shaped elastic support rod 5 made of fiber-reinforced composite material has the characteristics of being lightweight and high-strength, and is suitable for occasions with strict restrictions on equipment weight; the arc-shaped elastic support rod 5 made of shape memory alloy has superelastic deformation capacity and self-resetting characteristics, and can completely restore its original shape after undergoing large deformation, significantly improving the reusability of the equipment. The optimized design of the arc height to chord length ratio ensures that the arc-shaped elastic support rod 5 provides sufficient deformation stroke while having reasonable load-bearing capacity and stability.

[0060] Example 2:

[0061] This embodiment discloses an elastic damping connector 3 comprising a metal connecting plate, a viscoelastic damping layer, and a preload bolt assembly. The metal connecting plate is fixedly connected to the inner surface of the load-bearing outer panel 1 and the outer frame of the reinforcing skeleton 2, respectively. The viscoelastic damping layer, sandwiched between the two metal connecting plates, is made of butyl rubber, neoprene rubber, or high-damping silicone rubber, with a thickness of 3mm to 8mm. The preload bolt assembly penetrates the metal connecting plate and the viscoelastic damping layer, and the initial stiffness and energy dissipation capacity of the elastic damping connector 3 are controlled by adjusting the preload force. The preload bolt assembly is made of high-strength stainless steel, and a disc spring washer is placed between the bolt head and the metal connecting plate to maintain the stability of the preload force during long-term service. The dynamic shear modulus and loss factor of the viscoelastic damping layer are controlled according to the target blast resistance performance through material formulation and vulcanization process to achieve optimal energy dissipation effect within the typical frequency range of explosive impact.

[0062] like Figure 3 As shown, a flexible energy dissipation layer 7 is provided on the outer surface of the support plate 6, and a gap fit is formed between the flexible energy dissipation layer 7 and the inner surface of the load-bearing outer panel 1. The flexible energy dissipation layer 7 is made of high-damping rubber or polyurethane foam material, with a thickness of 5mm to 20mm and a Shore hardness controlled within the range of 30A to 60A. When the load-bearing outer panel 1 is impacted and deforms inward, the flexible energy dissipation layer 7 first contacts the load-bearing outer panel 1 and undergoes compression deformation, using its high damping characteristics to absorb part of the impact energy, while avoiding rigid collision between the load-bearing outer panel 1 and the support plate 6. The gap fit design of the flexible energy dissipation layer 7 provides initial deformation space for the load-bearing outer panel 1, ensuring that the polyurea elastomer protective coating and the load-bearing outer panel 1 can fully exert their energy dissipation function, realizing the phased and orderly energy absorption.

[0063] The fabrication process steps of the flexible energy dissipation layer 7 described in this embodiment are as follows:

[0064] ① Weigh out 100 parts of hydroxyl-terminated polyether polyol (molecular weight 2000), 45 parts of diphenylmethane diisocyanate (MDI, purity ≥99.5%), 8 parts of 1,4-butanediol chain extender, 0.3 parts of triethylenediamine catalyst, 1.2 parts of organosilicon foam stabilizer, and 0.8 parts of deionized water according to the mass ratio. Preheat each component to 40±2℃ for later use.

[0065] ② Add hydroxyl-terminated polyether polyol, chain extender, catalyst, foam stabilizer and deionized water into a high-speed stirred tank and stir at 1500 rpm for 3 minutes to form a uniform polyol component;

[0066] ③ Quickly add MDI to the polyol component, immediately increase the stirring speed to 3000 rpm, and continue stirring for 8-10 seconds until the mixture is uniform in color and the viscosity increases significantly. At this time, the milky white time is about 12-15 seconds.

[0067] ④ Quickly inject the reaction mixture into a mold preheated to 50°C. Coat the mold cavity surface with a release agent and lay a 0.5mm thick release film. After injection, close the mold and apply a molding pressure of 0.3MPa.

[0068] ⑤ Place the mold in an 80℃ oven for 30 minutes to cure, and after demolding, place it in a 100℃ environment for 4 hours to cure again, in order to eliminate residual stress and stabilize material properties;

[0069] ⑥ Cut the cured polyurethane foam into shape according to the design size, and treat the surface with plasma or apply a primer to enhance the adhesion to the support plate 6, so as to finally form a flexible energy dissipation layer 7 with a density of 280-350kg / m³, a resilience of 55-70%, and a compression set of ≤8%.

[0070] If a high-damping rubber material is used, natural rubber and butyl rubber are blended at a mass ratio of 6:4, and 50 parts of carbon black N330, 5 parts of naphthenic oil, 2 parts of zinc oxide, 1.5 parts of stearic acid, 1.2 parts of sulfur and 1.5 parts of accelerator CZ are added. The mixture is then subjected to intensive mixing, open milling and vulcanization molding. The vulcanization conditions are 150℃×15 minutes, and a high-damping rubber material with a Shore hardness of 45A and a loss factor tanδ≥0.25 (under the conditions of 10Hz frequency and 5% strain) is finally obtained.

[0071] like Figure 1 and Figure 4 As shown, the reinforcing skeleton 2 is a three-dimensional grid structure formed by welding crisscrossing steel sections or steel pipes. The grid size is 500mm×500mm to 1000mm×1000mm, and the cavity depth of the reinforcing skeleton 2 is 80mm to 200mm. The three-dimensional grid structure of the reinforcing skeleton 2 provides a three-dimensional constraint effect for the internal cast-in-place body 4, effectively suppressing brittle cracking and fragmentation of concrete under impact loads. Shear keys or roughening treatment are provided at the contact points between the frame of the reinforcing skeleton 2 and the internal cast-in-place body 4 to enhance the bond strength and anti-slip ability between the two. A locking groove adapted to the support plate 6 is opened on the frame of the reinforcing skeleton 2 near the load-bearing outer panel 1. The locking groove depth is 10mm to 20mm. The edge of the support plate 6 is embedded in the locking groove for positioning, while allowing the support plate 6 to slide to a limited extent along the locking groove direction under impact, preventing the support plate 6 from dislodging under extreme deformation.

[0072] The continuous polyurea elastomer protective coating has a thickness of 2mm to 5mm and is formed by the reaction and curing of isocyanate semi-prepolymer with terminal amino polyether and amine chain extender through a spraying process. The continuous polyurea elastomer protective coating has a tensile strength of not less than 16MPa, an elongation at break of not less than 300%, a tear strength of not less than 50kN / m, and an adhesion to the load-bearing outer panel 1 of not less than 2.5MPa. Before spraying, the surface of the load-bearing outer panel 1 is sandblasted to Sa2.5 grade and treated with a special primer. During the spraying process, a two-component high-pressure airless spraying device is used, with the raw material temperature controlled at 65℃ to 75℃ and the spraying pressure at 15MPa to 25MPa to ensure that the coating is formed in one step without seams. The continuous polyurea elastomer protective coating not only serves as the first line of defense to dissipate impact energy but also provides excellent corrosion resistance, wear resistance, and aging resistance for the load-bearing outer panel 1, extending the service life of the equipment.

[0073] The spraying process steps for the continuous polyurea elastomer protective coating described in this embodiment are as follows:

[0074] ① Thoroughly clean the outer surface of the load-bearing outer panel 1, wipe off the oil stains with acetone, and spray epoxy primer after drying. The primer should be cured for 24 hours until it is surface dry.

[0075] ② A two-component high-pressure airless spraying equipment is used to heat component A (a mixture of amino-terminated polyether and amine chain extender) and component B (polyisocyanate prepolymer) to 65±5℃ and 70±5℃ respectively, and deliver them to the mixing chamber at a volume ratio of 1:1 through a precise metering pump, and mix them thoroughly under a pressure of 15-20MPa.

[0076] ③ The mixed polyurea raw material is sprayed into the surface of the load-bearing outer panel 1 in a fan-shaped mist. The spray gun moving speed is controlled at 0.5-1.0m / s, the spraying distance is maintained at 400-600mm, and the wet film thickness of a single spray is 1.0-1.5mm.

[0077] ④ Apply multiple layers of spray according to the design protection level, with an interval of no more than 30 seconds between layers to ensure chemical bonding. The total dry film thickness should be controlled within the range of 2mm to 5mm. The coating gel time is about 10 seconds, and the walking strength time is about 60 seconds.

[0078] ⑤ After spraying, allow the polyurea coating to cure naturally for 7 days to fully cross-link and solidify, ultimately forming a continuous protective coating with tensile strength ≥25MPa, elongation at break ≥450%, tear strength ≥80kN / m, and adhesion to steel ≥12MPa.

[0079] The load-bearing outer panel 1 is made of high-strength low-alloy steel plate or fiber-reinforced metal laminate, with a thickness of 6mm to 20mm. Its outer surface is a continuous smooth curved surface or a curved surface structure with shallow ribs. High-strength low-alloy steel plate has excellent strength, toughness, and weldability, making it suitable for most protection scenarios. Fiber-reinforced metal laminate achieves a synergistic improvement in in-plane stiffness and impact resistance by embedding fiber-reinforced composite material layers between the metal layers. The curved surface structure design helps guide the flow and reflection of the blast shock wave, reducing local peak pressure, while enhancing the overall stiffness and dent resistance of the load-bearing outer panel 1. The four edges of the load-bearing outer panel 1 are provided with flanged structures, forming an overlapping fit with the peripheral frame of the protective equipment to ensure overall stability under impact.

[0080] The support plate 6 is a channel-shaped or corrugated component formed by stamping steel plate, and the material of the support plate 6 is spring steel. Its flanges are engaged in the groove of the frame of the reinforcing skeleton 2 and a sliding gap is reserved. The thickness of the support plate 6 is 3mm to 8mm, and its surface is provided with small holes for pouring and venting, with a hole diameter of 8mm to 15mm and an opening ratio of 5% to 15%. The channel-shaped or corrugated cross-section design of the support plate 6 significantly improves its out-of-plane stiffness and resistance to local buckling, ensuring stable force transmission performance under the reaction force of the arc-shaped elastic support rod 5. The selection of spring steel material gives the support plate 6 a certain elastic deformation capacity, which can absorb additional energy through its own plastic deformation under extreme impact conditions, serving as the last line of defense for the structure. The reserved sliding gap allows the support plate 6 to slide controllably relative to the frame of the reinforcing skeleton 2 during impact, avoiding stress concentration caused by boundary constraints. The small vent holes on the surface of the support plate 6 play a role in removing air from the cavity during the pouring of the internal casting body 4, preventing air pore defects from affecting the overall structure. At the same time, the presence of the small holes allows the concrete slurry to penetrate the support plate 6 to form a mechanical interlock, enhancing the connection reliability between the support plate 6 and the internal casting body 4.

[0081] like Figure 3 and Figure 7As shown, the support plate 6 can also be a hollow aluminum profile, with its internal cavity filled with foamed aluminum or aluminum foam material. The wall thickness of the aluminum profile is 2mm to 5mm, and its outer surface is anodized to form an oxide film layer with a thickness of 10μm to 25μm. The hollow aluminum profile structure significantly reduces the self-weight of the support plate 6 while ensuring sufficient rigidity, making it suitable for applications sensitive to the overall weight of the equipment. The foamed aluminum or aluminum foam filling material has excellent energy absorption characteristics. Its unique cellular structure achieves progressive energy dissipation under pressure through the bending, folding, and densification of the cell walls, forming a series energy dissipation mechanism with the arc-shaped elastic support rod 5. The dense oxide film layer formed by the anodizing treatment gives the aluminum profile excellent corrosion resistance and surface hardness, ensuring the long-term service performance of the support plate 6 in humid or corrosive environments. The cross-sectional shape of the aluminum profile is designed as a rectangular or irregular structure with reinforcing ribs. The arrangement direction of the reinforcing ribs corresponds to the support point of the arc-shaped elastic support rod 5 to optimize local load-bearing capacity and force transmission path.

[0082] Example 3:

[0083] This embodiment discloses a method for manufacturing a panelless civil defense device with sprayed polyurea, comprising the following steps:

[0084] S1. Preparation of load-bearing outer panel 1: Select high-strength low-alloy steel plate or fiber-reinforced metal laminate, and make the load-bearing outer panel 1 of the designed shape by cutting, bending and forming and edge flanging. Then, perform sandblasting and rust removal and primer coating on its outer surface.

[0085] S2. Preparation of reinforcing skeleton 2: Cut the steel profile or steel pipe into the design size and assemble them into a three-dimensional grid-like reinforcing skeleton 2 by welding. On the side of the reinforcing skeleton 2 near the load-bearing outer panel 1, the groove for locking the support plate 6 is finely machined.

[0086] S3. Install the arc-shaped elastic support rods 5: Arrange the arc-shaped elastic support rods 5 at the designed intervals in the cavity of the reinforcing frame 2, so that both ends are supported and fixed on the inner wall of the cavity of the reinforcing frame 2, and the arc shape protrudes towards the load-bearing outer panel 1.

[0087] S4. Install support plate 6: Fit support plate 6 into the groove of reinforcing frame 2, and adjust the position so that the inner side of support plate 6 is in close contact with the arc-shaped protruding arc surface of arc-shaped elastic support rod 5.

[0088] S5. Install the elastic damping connector 3: Fix metal connecting plates at corresponding positions on the inner surface of the load-bearing outer panel 1 and the outer frame of the reinforcing frame 2, clamp the viscoelastic damping layer, and then assemble the elastic damping connector 3 by pre-tightening bolt assembly to achieve a non-rigid connection between the load-bearing outer panel 1 and the reinforcing frame 2.

[0089] S6. Pouring the internal casting body 4: Pouring high-performance fiber-reinforced concrete or polymer-modified concrete into the cavity of the reinforcing skeleton 2, using an immersion vibrator to compact it in layers, and curing it to the design strength.

[0090] In step S6, the pouring of the internal casting body 4 is carried out in two stages. The first pouring is carried out to 2 / 3 of the height of the cavity of the reinforcing skeleton 2. The second pouring is carried out to the design height before the concrete initially sets. The interval between the two pouring is controlled between 30 and 60 minutes to ensure good interlayer bonding.

[0091] S7. Spraying polyurea protective coating: After the internal cast body 4 reaches the design strength, a continuous polyurea elastomer protective coating is sprayed on the outer surface of the load-bearing outer panel 1 using a two-component high-pressure airless spraying equipment. The coating thickness is controlled to be uniform and consistent. After curing, a complete protective system is formed.

[0092] In step S7, the ambient temperature for spraying is controlled between 10°C and 35°C, the relative humidity is below 85%, and the surface temperature of the substrate is more than 3°C above the dew point temperature. The coating is applied in 2 to 3 coats, with the interval between each coat adjusted according to the ambient temperature and humidity to ensure full bonding between layers and that the total thickness meets the design requirements.

[0093] During operation: The explosive shock wave first acts on the continuous polyurea elastomer protective coating on the outer surface of the load-bearing outer panel 1. Due to its extremely high elongation at break and excellent elastic deformation capacity, the polyurea coating rapidly undergoes large deformation in the initial stage of impact, absorbing a large amount of impact energy through molecular chain orientation and viscoelastic dissipation. Simultaneously, it effectively reduces the peak pressure of the shock wave and prolongs the impact time. The impact load, initially attenuated by the polyurea coating, is then transferred to the load-bearing outer panel 1. The high-strength low-alloy steel plate or fiber-reinforced metal laminate further dissipates energy through overall elastic bending deformation and localized plastic deformation. Its curved surface structure guides the shock wave to a uniform distribution, avoiding stress concentration.

[0094] During the inward deformation of the load-bearing outer panel 1, it first comes into contact with the flexible energy dissipation layer 7. The high-damping rubber or polyurethane foam absorbs some energy through compression deformation and hysteresis effect, preventing a rigid collision between the load-bearing outer panel 1 and the support plate 6. Subsequently, the impact load is transferred to the arc-shaped elastic support rod 5 through the support plate 6. The arc-shaped elastic support rod 5 undergoes nonlinear elastic deformation under compression. Its arc-shaped structure converts axial pressure into bending deformation, utilizing the high elastic energy storage characteristics of spring steel, fiber-reinforced composite materials, or shape memory alloys to achieve temporary energy storage and controllable release. The arc-shaped elastic support rod 5 in the central area has the largest deformation, transferring the impact energy to the first impact-resistant material, namely fiber-reinforced polymer mortar. The bridging effect of the fibers and the viscoelastic deformation of the polymer form a highly efficient energy dissipation zone. The arc-shaped elastic support rod 5 in the peripheral area has smaller deformation, transferring the residual load to the second impact-resistant material, namely high-strength concrete, maintaining the overall rigidity of the structure.

[0095] The three-dimensional grid structure of the reinforcing frame 2 provides three-dimensional constraints for the internal cast-in-place 4, suppressing brittle fracture and debris splashing of concrete, while ensuring coordinated operation with the internal cast-in-place 4 through shear keys or roughened interfaces. The elastic damping connector 3 forms a non-rigid connection between the load-bearing outer panel 1 and the reinforcing frame 2. The viscoelastic damping layer dissipates vibrational energy to the reinforcing frame 2 through shear deformation. The pre-tightening force design of the pre-tightened bolt assembly ensures sufficient stiffness of the connector under normal operating conditions, allowing controlled slippage under extreme impacts to prevent connection failure. When the impact energy exceeds the design threshold, the reserved sliding gap between the support plate 6 and the frame of the reinforcing frame 2 comes into play. The support plate 6 undergoes limited slippage along the engagement groove, protecting critical connection points through frictional energy dissipation. The spring steel support plate 6 can also act as a final safety barrier through its own plastic deformation.

[0096] For the support plate 6 using hollow aluminum profiles, the foamed aluminum or aluminum foam filling material achieves stable energy absorption through the gradual densification of its cellular structure under pressure, forming a series energy dissipation mechanism with the arc-shaped elastic support rod 5, further improving the equipment's blast resistance redundancy. After the explosion, the arc-shaped elastic support rod 5, made of shape memory alloy, uses its superelastic restoring force to drive the structure to reset, and the polyurea elastomer protective coating and flexible energy dissipation layer 7 return to their original shape, enabling the equipment to be reused and significantly reducing post-war repair costs and time.

Claims

1. A spray polyurea interior panel-free civil defense equipment, characterized in that: The main structure includes a load-bearing outer panel (1), a reinforcing frame (2), an elastic damping connector (3), an internal cast-in-place body (4), an arc-shaped elastic support rod (5), and a support plate (6); the load-bearing outer panel (1) and the three-dimensional mesh-like reinforcing frame (2) are non-rigidly connected by the elastic damping connector (3); the arc-shaped elastic support rod (5) is pre-set in the cavity of the reinforcing frame (2) before the internal cast-in-place body (4) is poured; the arc-shaped elastic support rod (5) is evenly spaced in the cavity of the reinforcing frame (2). The arc-shaped elastic support rod (5) protrudes towards the load-bearing outer panel (1) and both ends of the arc-shaped elastic support rod (5) are supported on the inner wall of the cavity of the reinforcing skeleton (2); the support plate (6) is engaged with the frame of the reinforcing skeleton (2) near the load-bearing outer panel (1), and the inner side of the support plate (6) abuts against the arc-shaped protruding arc surface of the arc-shaped elastic support rod (5); the cavity of the reinforcing skeleton (2) is filled with an internal casting body (4); the outer surface of the load-bearing outer panel (1) is sprayed with a continuous polyurea elastomer protective coating; The internal casting body (4) adopts a zoned composite casting method, and the energy-consuming cavities at different locations are filled with impact-resistant materials with different properties; the cavity in the central area that is directly impacted is filled with the first impact-resistant material, which is fiber-reinforced polymer mortar; the secondary areas around are filled with the second impact-resistant material, which is high-strength concrete. The elastic damping connector (3) includes a metal connecting plate, a viscoelastic damping layer and a pre-tightening bolt assembly; the metal connecting plate is fixedly connected to the inner surface of the load-bearing outer panel (1) and the outer frame of the reinforcing frame (2) respectively; the viscoelastic damping layer is sandwiched between the two metal connecting plates; the pre-tightening bolt assembly passes through the metal connecting plate and the viscoelastic damping layer; A flexible energy dissipation layer (7) is provided on the outer surface of the support plate (6), and a gap fit is formed between the flexible energy dissipation layer (7) and the inner surface of the load-bearing outer panel (1); the flexible energy dissipation layer (7) is made of high-damping rubber or polyurethane foam material, with a thickness of 5 mm to 20 mm and a Shore hardness controlled within the range of 30A to 60A.

2. The non-internal panel civil defense equipment with sprayed polyurea as described in claim 1, characterized in that: The cross-sectional shape of the arc-shaped elastic support rod (5) is one of circular, elliptical or rectangular, and its material is spring steel, fiber reinforced composite material or shape memory alloy; the ratio of arc height to chord length of the arc-shaped elastic support rod (5) is 1:5 to 1:10, and the wall thickness or diameter is selected in the range of 3mm to 15mm according to the design explosion-proof level.

3. The non-internal panel civil defense equipment with sprayed polyurea as described in claim 1, characterized in that: The reinforcing skeleton (2) is a three-dimensional grid structure made of intersecting steel sections or steel pipes welded together. The grid size is 500mm×500mm to 1000mm×1000mm, and the cavity depth of the reinforcing skeleton (2) is 80mm to 200mm.

4. A polyurea-coated, panelless civil defense device according to claim 1, characterized in that: The thickness of the continuous polyurea elastomer protective coating is 2mm to 5mm. It is formed by the reaction and curing of isocyanate semi-prepolymer with terminal amino polyether and amine chain extender through spraying process. The tensile strength of the continuous polyurea elastomer protective coating is not less than 16MPa, the elongation at break is not less than 300%, the tear strength is not less than 50kN / m, and the adhesion to the load-bearing outer panel (1) is not less than 2.5MPa.

5. A polyurea-coated, panelless civil defense device according to claim 1, characterized in that: The load-bearing outer panel (1) is made of high-strength low-alloy steel plate or fiber-reinforced metal laminate with a thickness of 6mm to 20mm. Its outer surface is a continuous smooth curved surface or a curved surface structure with shallow ribs.

6. A polyurea-coated, panelless civil defense device according to claim 1, characterized in that: The support plate (6) is a grooved or corrugated component formed by stamping steel plate, and the material of the support plate (6) is spring steel; its flange is engaged in the frame groove of the reinforcing frame (2) and a sliding gap is reserved; the thickness of the support plate (6) is 3mm to 8mm, and its surface is provided with small holes for pouring and venting, with a hole diameter of 8mm to 15mm and an opening rate of 5% to 15%.

7. A non-internal panel civil defense equipment with sprayed polyurea coating according to any one of claims 1-6, characterized in that: The manufacturing method of a polyurea-coated, panelless civil defense equipment includes the following steps: S1. Preparation of load-bearing outer panel (1): Select high-strength low-alloy steel plate or fiber-reinforced metal laminate, and make the load-bearing outer panel (1) of the design shape by cutting, bending and forming and edge flanging. Then, perform sandblasting and rust removal and primer coating on its outer surface. S2. Preparation of reinforcing skeleton (2): Cut the steel profile or steel pipe into the design size and assemble them into a three-dimensional grid-like reinforcing skeleton (2) by welding. On the side of the reinforcing skeleton (2) near the load-bearing outer panel (1), a groove for locking the support plate (6) is finely machined. S3. Install the arc-shaped elastic support rod (5): Arrange the arc-shaped elastic support rod (5) at the designed spacing in the cavity of the reinforcing frame (2), so that its two ends are supported and fixed on the inner wall of the cavity of the reinforcing frame (2), and arc-shaped protrusion towards the load-bearing outer panel (1) side. S4. Install the support plate (6): Fit the support plate (6) into the groove of the reinforcing frame (2), and adjust the position so that the inner side of the support plate (6) is in close contact with the arc-shaped protruding arc surface of the arc-shaped elastic support rod (5). S5. Install elastic damping connector (3): Fix metal connecting plates at corresponding positions on the inner surface of the load-bearing outer panel (1) and the outer frame of the reinforcing frame (2), clamp the viscoelastic damping layer, and then assemble the elastic damping connector (3) by pre-tightening bolt assembly to achieve a non-rigid connection between the load-bearing outer panel (1) and the reinforcing frame (2). S6. Pouring the internal casting body (4): Pouring high-performance fiber-reinforced concrete or polymer-modified concrete into the cavity of the reinforcing skeleton (2), using an immersion vibrator to compact it in layers, and curing it to the design strength. S7. Spraying polyurea protective coating: After the internal cast body (4) reaches the design strength, a continuous polyurea elastomer protective coating is sprayed on the outer surface of the load-bearing outer panel (1) using a two-component high-pressure airless spraying equipment. The coating thickness is controlled to be uniform and consistent. After curing, a complete protective system is formed.

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