Double cone embedded prestressed restrained elastic shielding layer

Abstract

The present invention discloses a double-cone embedded prestressed constrained bullet-proof layer, which is mainly assembled from a double-cone filling block and a matching constrained ferrule. Two interlocking ferrules are respectively assembled on the two conical surfaces of the double-cone filling block, and the inner ring of the ferrule and the outer conical surface of the corresponding cone are wedged and tightened by the cone surface matching, and the ferrules of the two cones are fixedly connected. The present invention is very convenient to apply radial prestress or three-way prestress to brittle materials such as ceramics, concrete, and glass at room temperature, and is suitable for applying prestress to protective components of various sizes. It can also use lighter and higher-strength fiber-reinforced polymers as constraining materials, which can reduce the unevenness of the wall thickness of the ferrule to a certain extent, save materials, and have a limiting effect. When any side of the prestressed constraint block is impacted, the two interlocking ferrules can effectively prevent the cone from falling out of the ferrule.

Description

Technical Field

[0001] The invention relates to a double-cone embedded extruded prestressed restrained bullet-proof layer. Background Art

[0002] With the continuous upgrading and development of anti-armor weapons and equipment, as well as the development and application of artificial intelligence automatic aiming firearms, the protective performance and protective structure of armored equipment such as tanks, infantry fighting vehicles, and bulletproof vehicles have been challenged more severely. The research and development of lighter and more effective protective armor and protective structures is a long way to go. Since Wilkins et al. conducted a pioneering study on the small aspect ratio armor-piercing projectile test on ceramic thin plates and aluminum back plates with limited thickness, the research on the anti-ballistic performance of ceramic armor has been attracting everyone's attention in the past few decades. Since ceramic materials (such as Al2O3, B4C, SiC, TiB2 and AlN, etc.) have the characteristics of low density, high hardness, and high compressive strength, they can effectively passivate and abrade projectiles. Combined with the absorption of fragment kinetic energy by the tough back plate, the anti-penetration performance of armor is significantly improved, making ceramic composite armor widely used. However, since ceramics are brittle materials with low toughness and low tensile strength, they are prone to collapse and splashing under the impact of the projectile. If they are constrained by tough materials, this phenomenon can be significantly improved.

[0003] Research shows that the high-strength, high-hardness segmented ceramic target, under the constraint of the lateral plate, the constraint force generated during the projectile penetration process effectively curbs the crack propagation of the ceramic target and improves the penetration resistance of the ceramic target. With the deepening of the research, the ceramic target is further subjected to biaxial prestress (confining pressure) on the basis of the lateral plate constraint, and its static, dynamic strength and hardness increase with the increase of prestress. The prestress applied to the ceramic target can offset the transient tensile stress of the local impact of the projectile and effectively inhibit the initiation and propagation of cracks inside the target body. Even if the ceramic breaks or breaks under high-speed impact, the cracks are squeezed tightly together, and there are only cracks but no expansion, which makes the broken ceramic area have greater penetration resistance, which effectively improves the penetration and impact resistance of the ceramic.

[0004] At present, the prestressed constraints of segmented ceramics are mainly mechanical extrusion and hot-installation. The mechanical extrusion method is to push the lateral plate in the direction of the ceramic panel surface to directly squeeze the side of the ceramic plate to apply lateral prestress to the ceramic; the hot-installation method is to assemble the ceramic block and the metal constraint ring with an excess difference at high temperature, and compress the ceramic to apply prestress after the metal with a larger thermal expansion coefficient and faster contraction is cooled as a whole, such as a constrained ceramic-metal composite bulletproof armor plate and its preparation method disclosed in the Chinese patent application with application number 201810777211.4. However, these methods are difficult to apply prestress to ceramic materials, and it is even more difficult to impose block prestress on brittle materials such as concrete and glass with poor heat resistance.

[0005] The Chinese invention patent application with application number 202010591444.2 discloses a prestressed constraint block for a composite armor structure. The single-cone filler body is wedged with the conical surface of the constraint ring to apply radial prestress to the filler body, and prestress can be applied to filling materials such as ceramics, concrete or glass at room temperature. However, after the single-cone filler body is pushed in from the large port of the constraint ring, if the single-cone is not effectively fixed, the filler body is easy to loosen under the impact load, and may move or pop out from the large port of the constraint ring, causing prestress loss and adversely affecting the performance against multiple strikes. Moreover, for the constraint ring (hoop) whose outer side is perpendicular to the end face, its side wall gradually thickens from the large port to the small port. The higher the constraint ring is, the greater the difference in wall thickness between the two ports. Therefore, for thicker constraint blocks, the difference in wall thickness between the large port and the small port of the constraint ring is too large, which will cause waste of material and excessive uneven distribution of prestress. Summary of the invention

[0006] The technical problem solved by the present invention is: in view of the above problems existing in the existing bulletproof armor structure, a novel double-cone embedded prestressed constrained bullet-proof layer is provided.

[0007] The present invention is implemented by the following technical solutions:

[0008] A double-cone embedded prestressed constrained bullet-proof layer comprises a double-cone filling block and a hoop for embedding the double-cone filling block, wherein the double-cone filling block comprises two coaxial reverse cones, the two reverse cones of the double-cone filling block are connected by a large end face, forming a double frustum with a large middle and small ends, and the outer cone surfaces of the two reverse cones are respectively surrounded by a hoop, the hoop has an inner ring of the same shape as the outer cone surface of the corresponding cone, and the inner ring of the hoop and the outer cone surface of the corresponding cone are wedged by cone surface matching; the hoop of the two cones is fixedly connected.

[0009] As a preferred embodiment of the present invention, the ferrule is a cylindrical ferrule having a continuous through-hole cavity with openings at both ends. After the cylindrical ferrule and the corresponding cone are wedged into place, the small end face of the corresponding cone is flush with the end face of the cavity of the cylindrical ferrule.

[0010] As another preferred embodiment of the present invention, the ferrule is a grooved ferrule, the large end of the barrel cavity of the grooved ferrule is open, and the small end is closed by a panel. After the grooved ferrule and the corresponding cone are wedged into place, the small end face of the corresponding cone abuts against the panel.

[0011] The double-cone embedded prestressed constrained bullet-proof layer in the above scheme, further, a retaining layer or a buffering cushion layer is provided between the small ends of the two reverse cones of the double-cone filling block and the panel.

[0012] As another preferred embodiment of the present invention, the hoop is a clamping edge hoop, the large end of the barrel cavity of the clamping edge hoop is open, and an annular clamping edge is arranged on the circumference of the small end. After the grooved hoop is wedged into place with the corresponding frustum, the small end face of the corresponding frustum is limited by the annular clamping edge.

[0013] In the double-truncated cone extruded prestressed constrained bullet-proof layer of the present invention, preferably, the double-truncated cone filling blocks are respectively fixed to the hoops of the two reverse cones by welding or bonding.

[0014] The double-cone embedded prestressed constrained bullet-proof layer in the above scheme is further provided with a wrapping layer outside the wedged double-cone filling block and the hoop.

[0015] In the double-cone embedded prestressed constrained bullet-proof layer of the present invention, preferably, an anchor plate is provided on the circumferential extension of the hoop, and corresponding screw holes are provided on the hoop anchor plates corresponding to the two reverse cones on the same double-cone filling block, and the hoops are fixedly connected by bolts passing through the screw holes on the anchor plates.

[0016] The double-cone embedded prestressed constrained bullet-proof layer in the above scheme, further, a plurality of the hoops are arranged on the constraint frame, the corresponding hoops on the two groups of constraint frames are respectively mounted on two reverse cones of a plurality of conical filling blocks, and all the hoops are fixedly connected by anchor plates arranged on the constraint frame.

[0017] The double-cone embedded prestressed constrained bullet-proof layer in the above scheme, further, the outer wall of the cone of the double-cone filling block and the inner wall of the hoop are respectively matching conical surfaces, or matching polygonal pyramid surfaces, and the small end face of the cone facing outward of the double-cone filling block is a plane or an outer convex surface.

[0018] The double-cone embedded prestressed constrained bullet-proof layer in the above scheme, further, the double-cone filling block is a multi-layer structure, and the double-cone filling block is formed by stacking one or more materials of ceramic, concrete, and glass, and a retaining layer, a buffer layer or a toughness enhancement layer is arranged between the layers of materials or on the end faces.

[0019] The double-cone-embedded prestressed constrained bullet-proof layer in the above scheme is further provided with a surface of the double-cone-filling block wrapped with a fiber-reinforced polymer or a metal sheet to form a surface reinforcement layer.

[0020] The present invention combines two buckled ferrules with a double-cone filling block, and pushes the double-cone filling block into the upper and lower ferrules. The two are wedged against each other through the cone surface, and the prestress applied by the ferrule to the side of the frustum filling block increases with the increase of the pushing depth. However, after the double-ferrule prestressed double-cone filling block is subjected to high-speed impact, the joint between the two ferrules is very easy to form a weak zone of the constraint block, which then causes fracture and damage. Therefore, in order to prevent the filling block from being damaged at the joint, it is best to connect the two ferrules by cold welding or bonding the wrapping layer, so that the two ferrules are connected as a whole to play a better constraint role. In addition to welding or bonding, the ferrules can also be connected by bolt anchoring, and the size of the prestress can be more conveniently adjusted by the looseness of the bolts, and three-way prestressed constraint can be easily achieved. Bolt anchoring connection generally requires an anchor plate with screw holes on the outside of the ferrule for anchoring each component. The welding can be quickly welded by cold welding technology such as laser and arc to reduce the influence of temperature on the strength of the ferrule.

[0021] Different types of ferrules have different restraining effects. The types of ferrules used in the present invention include cylindrical ferrules, grooved ferrules, and edge ferrules. The cylindrical ferrule has side panels but no panel, and can provide lateral prestressed restraint; the grooved ferrule is an integrated restraining component with a panel attached to the cylindrical ferrule, and can be used in combination with another grooved ferrule to achieve three-way prestressed restraint; the edge ferrule is a ferrule with a hole smaller than the panel size in the center area of ​​the panel of the grooved ferrule, forming a circular edge at the small end of the ferrule, which mainly provides lateral prestressed restraint, and leaves a circle of edge for supporting and fixing the restrained frustum filling block, increasing the bending and impact resistance of the frustum filling block, and can be used for transparent armor. In combination with the double frustum filling block of the present invention, two identical ferrules are used to form a restraining assembly, or three ferrules are used in combination of two to restrain the double frustum filling block. Applying radial prestress to the frustum filling block can improve its anti-penetration performance to a certain extent. If the frustum filling block can obtain three-way prestress constraint, its anti-penetration performance will be further improved. Since transparent armor cannot have a cover, it is generally bidirectional prestress constraint, while other armors are preferably three-way prestress constraint. The wall thickness variation of the hoop includes variable wall thickness and equal wall thickness. The hoop of a small-sized or thinner constraint block can generally be a variable wall thickness hoop, and the hoop of a large-sized or thicker constraint block can be a equal wall thickness hoop.

[0022] The double-cone filling block is a single-layer structure or a multi-layer structure, and can be made of at least one main material such as ceramics, concrete, glass, etc. The multi-layer structure can be combined with functional materials such as a retention layer (graphite layer) and a cushion layer (foamed aluminum, honeycomb material, polymer flexible material) to achieve higher protection performance; the hoop can be made of metal or fiber-reinforced composite materials, wherein the fiber-reinforced composite materials include fiber-reinforced metal-based composite materials or fiber-reinforced polymers. Since the corners of the frustum filling block made of materials such as ceramics and concrete are prone to local damage when being pushed into the hoop, before the frustum filling block is pushed into the hoop, a fiber-reinforced polymer can be wrapped on its surface or a metal sheet material can be set to reinforce the surface to prevent damage due to excessive local stress during the pushing process, or to prevent the fragments of the filling block without panel constraints from splashing.

[0023] The present invention combines a double-cone filling block with a matching hoop to form a prestressed restraint block of the bullet-proof layer, and assembles it into an integral door, board, wall or other structure, or uses a certain hoop as a unit to make a multi-grid restraint frame, and then fills the cone filling block and installs other various matching components to assemble a larger area prestressed restraint assembled protective plate structure. The use of two interlocking hoops to restrain the double-cone filling block can reduce the unevenness of the hoop wall thickness to a certain extent, save materials, and also have a limiting effect. When any side of the prestressed restraint block is impacted, the two interlocking hoops can effectively prevent the cone from escaping from the hoop.

[0024] Compared with the prior art, the present invention uses the principle of hoop constraint. The hoop constrains the frustum filling block to have a self-tightening function. The more it is pressed, the tighter it is. The more it is hit, the tighter it is. The strength of the filling block increases accordingly with the increase of prestress. The present invention controls and adjusts the radial prestress by two parameters, the push-in depth or the cone inclination angle of the frustum filling block. The prestress in the third direction can be applied by the tightening force of the bolt. It is very easy to apply radial prestress or three-way prestress to brittle materials such as concrete, ceramics, and glass at room temperature. It is suitable for applying prestress to protective components of various sizes. Lighter and higher-strength fiber-reinforced polymers can also be used as constraint materials. Since the outer diameter of the bottom surface of the frustum filling block and the inner diameter of the top surface of the hoop have a larger tolerance, a higher processing error can be allowed. Compared with other assembly methods, it is more environmentally friendly and easier to implement. It is also easier to apply prestress or adjust the prestress. The assembled protective structure composed of multiple frustum filling blocks will have the damage range after penetration greatly reduced under the action of block prestressing constraint, can withstand multiple attacks, and the damaged frustum filling blocks are easy to disassemble, remove and replace, and the repair is simple and quick. It has broad application prospects in various protection fields such as aircraft hangars, missile manhole covers, ships, armed helicopters, armored vehicles and tanks.

[0025] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a top view of the double-cone embedded prestressed constrained bullet-proof layer of the first embodiment.

[0027] Figure 2 This is a front view in the direction of A of a double-cone embedded prestressed constrained bullet-proof layer of Example 1.

[0028] Figure 3 This is a front view in the direction of A of another double-cone extruded prestressed constrained bullet-proof layer of the first embodiment.

[0029] Figure 4 This is the force relationship between the frustum and the hoop in Example 1 before they are wedged.

[0030] Figure 5 This is the force relationship between the frustum and the hoop after being wedged in the first embodiment.

[0031] Figure 6 It is a top view of the double-cone embedded prestressed constrained bullet-proof layer of the second embodiment.

[0032] Figure 7 This is a front view in the direction of A of a double-cone embedded prestressed constrained bullet-proof layer of Example 2.

[0033] Figure 8 This is the front view in the direction of A of the second double-cone embedded prestressed constrained bullet-proof layer of the second embodiment.

[0034] Fig. 9 This is the front view in the direction of A of the third double-cone embedded prestressed constrained bullet-proof layer of the second embodiment.

[0035] Fig.10 It is a top view of a double-cone embedded prestressed constrained bullet-proof layer in the third embodiment.

[0036] Fig.11 It is a top view of another double-cone extruded prestressed constrained bullet-proof layer in the third embodiment.

[0037] Fig.12 This is the front view in the direction of A of the double-cone embedded prestressed constrained bullet-proof layer in the third embodiment.

[0038] Fig.13 This is the B-direction front view of the double-cone embedded prestressed constrained bullet-proof layer in the third embodiment.

[0039] Fig.14 It is a top view of a double-cone extruded prestressed constrained bullet-proof layer in the fourth embodiment.

[0040] Fig.15 It is a top view of another double-cone extruded prestressed constrained bullet-proof layer in the fourth embodiment.

[0041] Fig.16 This is the front view in the direction of A of the double-cone embedded prestressed constrained bullet-proof layer in the fourth embodiment.

[0042] Fig.17 This is the B-direction front view of the double-cone embedded prestressed constrained bullet-proof layer in the fourth embodiment.

[0043] Fig.18 It is a top view of a double-cone extruded prestressed constrained bullet-proof layer in Example 5.

[0044] Fig.19 It is a top view of another double-cone embedded prestressed constrained bullet-proof layer in the fifth embodiment.

[0045] Fig. 20 This is the front view in the direction of A of the double-cone embedded prestressed constrained bullet-proof layer in the fifth embodiment.

[0046] Fig.21 This is the B-direction front view of the double-cone embedded prestressed constrained bullet-proof layer in Example 5.

[0047] Fig. 22 It is a top view of a double-cone embedded prestressed constrained bullet-proof layer in Example 6.

[0048] Fig.23 It is a top view of another double-cone embedded prestressed constrained bullet-proof layer in Example 6.

[0049] Fig.24 This is the front view in the direction of A of the double-cone embedded prestressed constrained bullet-proof layer in Example 6.

[0050] Fig.25 This is the B-direction front view of the double-cone embedded prestressed constrained bullet-proof layer in Example 6.

[0051] Fig.26 This is a schematic diagram of the double-cone extruded prestressed constrained bullet-proof layer in Example 7 before assembly.

[0052] Fig. 27 This is a schematic diagram of the double-cone embedded prestressed constrained bullet-proof layer after assembly in Example 7.

[0053] Fig.28 This is the cross section of the central axis of the double-structure layer double-cone filling block in Example 8.

[0054] Fig.29 This is the cross section of the central axis of the double-frustum filling block of the surface reinforcement layer in Example 9.

[0055] Fig.30 This is the relationship curve between prestress and insertion depth in the simulation.

[0056] Fig.31 This is the stress cloud diagram of the concrete cone penetration process in the simulation.

[0057] Fig.32 This is the relationship curve between the projectile penetration depth and the penetration depth reduction rate and prestress in the simulation.

[0058] Numbers in the figure: 1-double-cone filling block, 11-first structural layer, 12-second structural layer, 2-constraint frame, 21-cylindrical hoop, 22-grooved hoop, 23-edge hoop, 24-anchor plate, 27-face plate, 28-edge;

[0059] 3-bolts, 31-wrapping layer, 32-retaining layer, 33-buffering layer, 34-surface reinforcement layer. DETAILED DESCRIPTION

[0060] Embodiment 1

[0061] See also Figure 1 and Figure 2 The double-cone embedded prestressed constrained shielding layer shown in the figure is a specific embodiment of the present invention. The prestressed structure of the shielding layer includes a double-cone filling block 1 and a cylindrical hoop 21 for embedding and assembling the double-cone filling block 1. Figure 2 As shown, the double-frustum filling block 1 is a double-frustum structure, including two coaxial reverse frustums, the large ends of the frustums between the two reverse frustums are integrally connected, and the small ends face the two sides of the double-frustum filling block 1, that is, the two end surfaces of the double-frustum filling block 1 are the small ends of the two reverse frustums, and the same double-frustum filling block 1 is equipped with two cylindrical hoops 21 fixedly connected together, which are respectively wrapped around the outer cone surfaces of the two reverse frustums of the double-frustum filling block 1, and the cylindrical hoops 21 have a conical inner ring with the same shape as the outer cone surface of the corresponding frustum. The inner ring conical surface of the cylindrical hoops 21 on the same double-frustum filling block 1 is a reverse conical surface, corresponding to the two reverse frustums on the double-frustum filling block 1, and the inner ring of the cylindrical hoops 21 and the outer cone surface of the corresponding frustum are wedged by cone surface matching; then the cylindrical hoops 21 of the two frustums on the same double-frustum filling block 1 are fixedly connected, that is, assembled to form the prestressed constraint block as a whole of this embodiment.

[0062] The inner ring of the cylindrical hoop 21 in this embodiment is a continuous through-cylindrical cavity with openings at both ends, and the inner ring is a conical surface. After the cylindrical hoop 21 is wedged into place with the corresponding cone of the double-cone filling block 1 through the inner ring, the small end face of the corresponding cone is flush with the small end cylinder cavity end face of the cylindrical hoop, and the large end of the cylindrical hoop 21 does not exceed the large end of the corresponding cone, thereby ensuring the normal assembly of the cylindrical hoop on the other cone of the double-cone filling block 1.

[0063] After the double-cone filling block 1 in this embodiment corresponds to the cylindrical sleeves 21 of the two reverse cones and is wedged and assembled, the cylindrical sleeves 21 are cold-welded or bonded between the large ends of the inner rings, such as Figure 2 As shown in , in order to further improve the integrity of the prestressed constraint block, a layer of fiber cloth is bonded and wrapped around the wedged double-cone filling block 1 and the cylindrical hoop 21 as a wrapping layer 31, as shown in Figure 3 shown.

[0064] The double-cone filling block can be made of at least one main material such as ceramic, concrete, glass, etc. Since the corner areas of the filling block that are in contact with the cylindrical hoop are prone to local damage during the process of pushing the cone of ceramic, concrete, etc. into the cylindrical hoop, before the cone filling block is pushed into the hoop, its surface can be wrapped with fiber-reinforced polymer or metal sheet material can be set to reinforce the surface to prevent damage or stratification due to excessive local stress during the pushing process.

[0065] See also Figure 4 and Figure 5 In order to ensure that the double-cone filling block 1 can generate extrusion prestress when it is pressed into the cylindrical hoop 21, the size between the frustum of the double-cone filling block 1 and the cylindrical hoop 21 should meet the following conditions:

[0066] For the cross-sectional dimensions of the frustum and the corresponding cylindrical hoop 21, the outer wall of the frustum is a conical surface, that is, the frustum is set as a large end and a small end at the two axial ends, the large end diameter of the frustum is set as d1, and the small end diameter of the frustum is set as d2, d1>d2, and the diameter referred to here is the outer circle diameter of the cross section of the frustum and the diameter of the circumscribed circle of the regular hexagon of the cross section of the frustum; similarly, the inner ring wall of the cylindrical hoop 21 is a conical surface, and the large end and the small end are set at the two axial ends of the inner ring wall of the cylindrical hoop 21, wherein the large end diameter of the cylindrical hoop 21 is set as R1, and the small end diameter of the cylindrical hoop 21 is set as R2, R1>R2, and the diameter referred to here is the inner circle diameter of the cross section of the inner ring wall of the cylindrical hoop 21 and the diameter of the circumscribed circle of the regular hexagon of the cross section of the inner ring wall of the cylindrical hoop 21, preferably, R2<d2<R1≤d1. δ is the interference between the frustum and the corresponding cylindrical hoop 21, δ=htanα.

[0067] Regarding the inclination angle of the wedging cone and the cylindrical hoop 21, the inclination angle α of the cone outer wall is in the range of 0.5° to 10°, preferably 2° to 6°, and the inclination angle β of the cone inner wall of the cylindrical hoop 21 is in the range of 0.5° to 10°, preferably 2° to 6°. The inclination angle of the cone referred to here is the angle between the cone generatrix of the outer wall of the cone and the inner wall of the cylindrical hoop 21 and the vertical direction, or the angle between the pyramid ridgeline of the outer wall of the cone and the inner wall of the cylindrical hoop 21 and the vertical direction.

[0068] As for the axial dimensions of the frustum and the cylindrical ferrule 21 , the axial heights of a single frustum and its corresponding cylindrical ferrule 21 are set to be h1 and h2 respectively, wherein h1≤h2.

[0069] The assembly method and the basic principle of prestressing of the double-cone filling block 1 and the cylindrical hoop 21 are as follows:

[0070] First, place the cone on one side of the double cone filling block 1 into the corresponding inner ring of the cylindrical hoop 21. In order to facilitate pressure application, the large end of the inner ring of the cylindrical hoop 21 is generally opened upward, and one end of the double cone is pushed downward into the inner ring of the cylindrical hoop 21. Then, thrust is applied to the cone in the height direction. The elastic restoring force of the cylindrical hoop 21 squeezes the pre-tightened cone inward, and pre-stress is applied in its radial direction. The deeper the cone is pushed into the inner ring of the cylindrical hoop 21, the greater the radial pre-stress applied to the cone by the cylindrical hoop 21. After the filling body is pushed into the predetermined position, a prestressed constraint block is obtained. The cone can be pushed in by a jack, a hydraulic press, or bolt tightening. In order to reduce the push resistance, a temporary lubricant can be applied to the contact cone surface of the two. After pushing into the predetermined position, the lubricant is removed. The radial prestress of the frustum can be adjusted by designing the angle between the cone generatrix or the prism line of the outer wall of the platform and the height, as well as the insertion depth of the filling platform. When the angle is constant, before the cylindrical hoop 21 yields or fails, the greater the insertion depth of the frustum, the greater the prestress. After completing the installation of the frustum on one side of the double frustum filling block 1 and the corresponding cylindrical hoop 21, turn the double frustum filling block 1, and perform the same installation on the frustum on the other side of the double frustum filling block 1 and the other cylindrical hoop 21. After both cylindrical hoop 21 on the double frustum filling block 1 are installed in place, the two cylindrical hoop 21 are fixedly connected together by cold welding.

[0071] The frustum can be made of ceramic, concrete or glass, and the cylindrical sleeve 21 is made of metal or fiber-reinforced composite material. The fiber-reinforced composite material includes a fiber-reinforced metal-based composite material or a fiber-reinforced polymer.

[0072] For the prestressed constraint block of the frustum made of concrete, the frustum can be directly cast and formed using the cylindrical hoop 21 as a template. Before pouring the concrete, isolation oil is applied or an isolation film is arranged on the inside of the cylindrical hoop 21. The bottom of the cylindrical hoop 21 reserves a pushing space for the concrete after it is formed. When the concrete reaches a certain strength, the bottom of the cylindrical hoop is supported or fixed, and the frustum is further pushed into the cylindrical hoop 21, so that the frustum generates radial prestress.

[0073] During the assembly process of the frustum and the cylindrical hoop 21, the diameter d2 of the small end of the bottom surface of the frustum is less than the diameter R1 of the large end opening at the top of the inner ring of the cylindrical hoop 21, so that the frustum body can be easily installed in the cylindrical hoop. The diameter-to-thickness ratio or the diameter-to-height ratio d1 / (2h1) of the frustum is 0.5-40, preferably 3-12. The wall thickness of the inner ring of the cylindrical hoop 21 can be variable thickness or constant thickness, that is, the top wall thickness t1 of the cylindrical hoop 21 ≤ the bottom wall thickness t2. The wall thickness and yield strength of the cylindrical hoop 21 are determined according to the prestress that needs to be applied to the frustum. The larger the ratio t / d of the wall thickness of the cylindrical hoop 21 to the diameter of the frustum, and the greater the yield strength of the cylindrical hoop 21, the greater the potential for constrained prestress that can be provided. Affected by the inconsistent diameters of the upper and lower cross sections of the cone and the inconsistent wall thickness of the cylindrical hoop 21 in the height direction, the prestress of the cone is uneven in the height direction. The change in the upper and lower prestress can be adjusted by designing a slight difference between the angle α of the cone surface of the outer wall of the cone and the angle β of the cone surface of the inner ring wall of the cylindrical hoop 21. In the process of pushing the cone into the cylindrical hoop 21, the prestress of the prestressed constraint block gradually increases from top to bottom. By appropriately increasing the angle difference Δα between α and β, the upper and lower prestress differences of the cone body can be reduced. The value range of Δα is 0° to 0.5°, preferably 0° to 0.2°. When α=β, the cone is placed in the cylindrical hoop 21, and the outer wall of the cone fits the contact surface of the inner ring wall of the constraint block 12. Put the frustum into the cylindrical hoop 21, the contact stress between the outer wall of the frustum and the inner wall of the cylindrical hoop 21 is very small. At this time, the height difference between the top surface of the frustum and the top surface of the cylindrical hoop 21 is h, that is, the pushing depth, and the height difference between the connecting surface of the double frustum and the small end surface of the cylindrical hoop is h3.

[0074] Embodiment 2

[0075] See also Figure 6 and Figure 7 The double-truncated cone-shaped prestressed constraint shielding layer shown in the figure is another specific embodiment of the present invention. The prestressed constraint block includes a double-truncated cone filling block 1 and a grooved sleeve 22 for inserting and extruding the double-truncated cone filling block 1. Figure 7As shown, the double-truncated cone filling block 1 of this embodiment has the same double-truncated cone structure as that of the first embodiment. Two grooved ferrules 22 are fixedly connected together and assembled on the same double-truncated cone filling block 1. The grooved ferrules 22 are respectively wrapped around the outer cone surfaces and small end surfaces of the two reverse cones of the double-truncated cone filling block 1. The grooved ferrule 22 has a cone surface inner ring with the same shape as the outer cone surface of the corresponding cone and a panel 27 covering the small end surface of the cone. The inner cone surface of the grooved ferrule 22 on the same double-truncated cone filling block 1 is a reverse cone surface. Corresponding to the two reverse cones on the double-cone filling block 1, the inner ring of the grooved hoop 22 and the outer cone surface of the corresponding cone are wedged through the cone surface cooperation, and at the same time, its panel 27 covers the small end surface of the cone, and the force condition of the cone on the inner ring side of the grooved hoop 22 is the same as that of the cylindrical hoop; after the two cones of the double-cone filling block 1 are both equipped with the grooved hoop 22, the grooved hoop 22 of the two cones on the same double-cone filling block 1 are fixedly connected and assembled to form the prestressed constraint block as a whole of this embodiment.

[0076] The grooved hoop 22 in this embodiment is additionally provided with a panel 27 covering the small end panel of the frustum on the basis of the cylindrical hoop 21 in the first embodiment. The large end of the cylindrical cavity of the grooved hoop 22 is open, and the small end is closed by the panel 27 to form an open groove for accommodating the frustum. After the grooved hoop 22 and the corresponding frustum are wedged into place, the small end face of the corresponding frustum abuts against the panel 27, and the large end of the grooved hoop 22 also does not exceed the large end of the corresponding frustum, thereby ensuring the normal assembly of the grooved hoop on the other frustum of the double frustum filling block 1.

[0077] In this embodiment, the double-cone filling block 1 corresponds to the grooved ferrules 22 of the two reverse cones respectively. After the grooved ferrules 22 are wedged and assembled, the grooved ferrules 22 are cold-welded or bonded together through the large ends. Figure 7 As shown in , in order to further improve the integrity of the prestressed constraint block, a layer of fiber cloth is bonded and wrapped around the wedged double-cone filling block 1 and the grooved sleeve 22 as a wrapping layer 31, as shown in Figure 8 shown.

[0078] In order to achieve higher protection performance of the prestressed constraint block in this embodiment, the double-cone filling block 1 adopts a multi-layer structure, wherein a retaining layer 32 is padded between the small end of one section of the cone and the panel 27 of the corresponding groove-type hoop 22, and a buffer cushion layer 33 is padded between the small end of the other section of the cone and the panel 27 of the corresponding groove-type hoop 22. Fig. 9 As shown in . The retention layer 32 is made of graphite layer, and the buffer pad layer 33 is made of functional materials such as foam aluminum, honeycomb material, polymer flexible material, etc., to achieve higher protection performance.

[0079] Embodiment 3

[0080] See also Figure 10-13The double-cone-embedded prestressed constraint shielding layer shown in the figure is another specific implementation scheme of the present invention. This embodiment is an extension of the first embodiment. The prestressed constraint block includes a double-cone filling block 1 and a cylindrical hoop 21 for embedding and extruding the double-cone filling block 1. Fig.12 and Fig.13 As shown, the double-frustum filling block 1 is a double-frustum structure, including two coaxial reverse frustums, the large ends of the frustums between the two reverse frustums are integrally connected, and the small ends face the two sides of the double-frustum filling block 1, that is, the two end surfaces of the double-frustum filling block 1 are the small ends of the two reverse frustums, and the same double-frustum filling block 1 is equipped with two cylindrical hoops 21 fixedly connected together, which are respectively wrapped around the outer cone surfaces of the two reverse frustums of the double-frustum filling block 1, and the cylindrical hoops 21 have a conical inner ring with the same shape as the outer cone surface of the corresponding frustum. The inner ring conical surface of the cylindrical hoops 21 on the same double-frustum filling block 1 is a reverse conical surface, corresponding to the two reverse frustums on the double-frustum filling block 1, and the inner ring of the cylindrical hoops 21 and the outer cone surface of the corresponding frustum are wedged by cone surface matching; then the cylindrical hoops 21 of the two frustums on the same double-frustum filling block 1 are fixedly connected, that is, assembled to form the prestressed constraint block as a whole of this embodiment.

[0081] In this embodiment, the fixed connection between the cylindrical ferrules 21 is achieved by arranging an anchor plate 24 extending circumferentially of the cylindrical ferrule 21. This embodiment is described by taking the inner ring of the ferrule of the double-ferrule filling block 1 and the cylindrical ferrule 21 as a pyramidal surface with a regular octagonal cross section and a conical surface with a circular cross section, respectively.

[0082] See also Fig.10 The cone of the double-cone filling block 1 is a prism with a regular octagonal cross section, and the corresponding inner ring of the cylindrical hoop 21 is a matching regular octagonal pyramid surface. The regular octagonal outer ring of the cylindrical hoop 21 extends four triangular anchor plates 24 outward, forming a square frame with the other four sides of the regular octagon. The anchor plate 24 is close to the large end of the cylindrical hoop 21, and the end face is flush with the large end face of the cylindrical hoop 21. Screw holes are respectively provided on the four anchor plates, and the screw holes corresponding to the cylindrical hoop anchor plates 24 of the two reverse cones on the same double-cone filling block 1 correspond one to one. After the two cylindrical hoop 21 on the double-cone filling block 1 are assembled in place, the screw holes on the anchor plate 24 are aligned in the circumferential direction, and the bolts 3 are passed through the screw holes on the two cylindrical hoop 21 on the double-cone filling block 1 to be locked and fixed. The screw hole 3 on the anchor plate 24 can be a bolt through hole, which is locked by the combination of a bolt and a nut, or a bolt through hole on one side of the anchor plate and a threaded hole on the other side. The bolt 3 passes through the bolt through hole on one side of the anchor plate and is directly screwed and locked with the threaded hole on the other side of the anchor plate. Fig.13 shown.

[0083] See also Fig.11The cone of the double-cone filling block 1 is a circular cone with a circular cross-section, and the corresponding inner ring of the cylindrical hoop 21 is a matching conical surface. The circular outer ring of the cylindrical hoop 21 extends outward to form a positive direction frame. The side length of the square frame is the same as the diameter of the circular outer ring of the cylindrical hoop 21. The anchor plates 24 are respectively located at the four corners of the square frame. The anchor plates 24 are close to the large end of the cylindrical hoop 21, and the end face is flush with the large end face of the cylindrical hoop 21. Screw holes are respectively opened on the anchor plates at the four corners of the square frame. The screw holes set on the cylindrical hoop anchor plates 24 corresponding to the two reverse cones on the same double-cone filling block 1 correspond one to one. After the two cylindrical hoop 21 on the double-cone filling block 1 are assembled in place, the screw holes on the anchor plate 24 are aligned in the circumferential direction, and the bolts 3 are passed through the screw holes on the two cylindrical hoop 21 on the double-cone filling block 1 to lock and fix them. The screw hole 3 on the anchor plate 24 can be a bolt through hole, which is locked by the combination of a bolt and a nut, or a bolt through hole on one side of the anchor plate and a threaded hole on the other side. The bolt 3 passes through the bolt through hole on one side of the anchor plate and is directly screwed and locked with the threaded hole on the other side of the anchor plate. Fig.13 As shown, radial prestress is applied to the double-cone filling block 1 through the cylindrical hoop 21. The size of the prestress can be adjusted by the tightening force of the bolts to ensure the embedding effect of the cylindrical hoop 21 on the respective cone structures while effectively preventing the hoop from falling out.

[0084] Embodiment 4

[0085] See also Figure 14-17 The double-cone-shaped prestressed constraint shielding layer shown in the figure is another specific implementation scheme of the present invention. This embodiment is an extension of the second embodiment. The prestressed constraint block includes a double-cone-shaped filling block 1 and a grooved sleeve 22 for inserting and extruding the double-cone-shaped filling block 1. Fig.16 and Fig.17 As shown, the double-truncated cone filling block 1 of this embodiment has the same double-truncated cone structure as that of the second embodiment. Two grooved ferrules 22 are fixedly connected together and assembled on the same double-truncated cone filling block 1. The grooved ferrules 22 are respectively wrapped around the outer cone surfaces and small end surfaces of the two reverse cones of the double-truncated cone filling block 1. The grooved ferrule 22 has a cone surface inner ring with the same shape as the outer cone surface of the corresponding cone and a panel 27 covering the small end surface of the cone. The inner cone surface of the grooved ferrule 22 on the same double-truncated cone filling block 1 is a reverse cone surface. Corresponding to the two reverse cones on the double-cone filling block 1, the inner ring of the grooved hoop 22 and the outer cone surface of the corresponding cone are wedged through the cone surface cooperation, and at the same time, its panel 27 covers the small end surface of the cone, and the force condition of the cone on the inner ring side of the grooved hoop 22 is the same as that of the cylindrical hoop; after the two cones of the double-cone filling block 1 are both equipped with the grooved hoop 22, the grooved hoop 22 of the two cones on the same double-cone filling block 1 are fixedly connected and assembled to form the prestressed constraint block as a whole of this embodiment.

[0086] In this embodiment, the fixed connection between the grooved ferrules 22 is achieved by arranging an anchor plate 24 extending circumferentially of the grooved ferrule 22. This embodiment is described by taking the inner ring of the frustum of the double frustum filling block 1 and the grooved ferrule 22 as a pyramidal surface with a regular octagonal cross section and a conical surface with a circular cross section, respectively.

[0087] See also Fig.14 The cone of the double-cone filling block 1 is a prism with a regular octagonal cross section, and the corresponding inner ring of the grooved hoop 22 is a matching regular octagonal pyramid surface. The regular octagonal outer ring of the grooved hoop 22 extends four triangular anchor plates 24 outward, forming a square frame with the other four sides of the regular octagon. The anchor plate 24 is close to the large end of the grooved hoop 22, and the end face is flush with the large end face of the grooved hoop 22. Screw holes are respectively provided on the four anchor plates, and the screw holes corresponding to the cylindrical hoop anchor plates 24 of the two reverse cones on the same double-cone filling block 1 correspond one to one. After the two grooved hoops 22 on the double-cone filling block 1 are assembled in place, the screw holes on the anchor plate 24 are aligned in the circumferential direction, and the bolts 3 are passed through the screw holes on the two grooved hoops 22 on the double-cone filling block 1 and locked and fixed. The screw hole 3 on the anchor plate 24 can be a bolt through hole, which is locked by the combination of a bolt and a nut, or a bolt through hole on one side of the anchor plate and a threaded hole on the other side. The bolt 3 passes through the bolt through hole on one side of the anchor plate and is directly screwed and locked with the threaded hole on the other side of the anchor plate. The two grooved hoops 22 on the double frustum filling block 1 are axially locked by the bolt 3, such as Fig.16 shown.

[0088] See also Fig.15 The cone of the double-cone filling block 1 is a circular cone with a circular cross-section, and the corresponding inner ring of the grooved hoop 22 is a matching conical surface. The circular outer ring of the grooved hoop 22 extends outward to form a positive direction frame. The side length of the square frame is the same as the diameter of the circular outer ring of the grooved hoop 22. The anchor plates 24 are respectively located at the four corners of the square frame. The anchor plates 24 are close to the large end of the grooved hoop 22, and the end face is flush with the large end face of the grooved hoop 22. Screw holes are respectively opened on the anchor plates at the four corners of the square frame. The screw holes set on the cylindrical hoop anchor plates 24 corresponding to the two reverse cones on the same double-cone filling block 1 correspond one to one. After the two grooved hoops 22 on the double-cone filling block 1 are assembled in place, the screw holes on the anchor plate 24 are aligned in the circumferential direction, and the bolts 3 are passed through the screw holes on the two grooved hoops 22 on the double-cone filling block 1 and locked and fixed. The screw hole 3 on the anchor plate 24 can be a bolt through hole, which is locked by the combination of a bolt and a nut, or a bolt through hole on one side of the anchor plate and a threaded hole on the other side. The bolt 3 passes through the bolt through hole on one side of the anchor plate and is directly screwed and locked with the threaded hole on the other side of the anchor plate. Fig.17As shown, the double-cone filling block 1 is subjected to axial prestressing in opposite directions through the grooved hoop 22. The magnitude of the prestressing can be adjusted by the tightening force of the bolts to ensure the embedding effect of the grooved hoop 22 on the respective cone structures while effectively preventing the hoop from coming out.

[0089] Embodiment 5

[0090] See also Figure 18-21 The double-truncated cone-shaped prestressed constraint shielding layer shown in the figure is another specific implementation scheme of the present invention. This embodiment is an extension of the fourth embodiment. The prestressed constraint block includes a double-truncated cone filling block 1 and a grooved sleeve 22 for inserting and extruding the double-truncated cone filling block 1. Fig. 20 and Fig.21 As shown, the double-truncated cone filling block 1 of this embodiment has the same double-truncated cone structure as that of the second embodiment. Two grooved ferrules 22 are fixedly connected together and assembled on the same double-truncated cone filling block 1. The grooved ferrules 22 are respectively wrapped around the outer cone surfaces and small end surfaces of the two reverse cones of the double-truncated cone filling block 1. The grooved ferrule 22 has a cone surface inner ring with the same shape as the outer cone surface of the corresponding cone and a panel 27 covering the small end surface of the cone. The inner cone surface of the grooved ferrule 22 on the same double-truncated cone filling block 1 is a reverse cone surface. Corresponding to the two reverse cones on the double-cone filling block 1, the inner ring of the grooved hoop 22 and the outer cone surface of the corresponding cone are wedged through the cone surface cooperation, and at the same time, its panel 27 covers the small end surface of the cone, and the force condition of the cone on the inner ring side of the grooved hoop 22 is the same as that of the cylindrical hoop; after the two cones of the double-cone filling block 1 are both equipped with the grooved hoop 22, the grooved hoop 22 of the two cones on the same double-cone filling block 1 are fixedly connected and assembled to form the prestressed constraint block as a whole of this embodiment.

[0091] Different from the fourth embodiment, the small end faces of the two reverse cones of the double-cone filling block 1 in the fourth embodiment are planes, and the corresponding panel 27 on the grooved sleeve 22 is a corresponding flat plate. The small end faces of the two reverse cones of the double-cone filling block 1 in this embodiment are convex surfaces, and the convex surfaces include convex arc spherical crown surfaces or convex pyramidal surfaces, which are beneficial to the yaw of the projectile and improve the anti-penetration ability of the prestressed constraint block.

[0092] Embodiment 6

[0093] See also Figure 22-25 The double-cone-shaped prestressed constrained shielding layer in the figure is another specific implementation scheme of the present invention. This embodiment adopts a clamping edge hoop 23 different from the above embodiment to assemble the double-cone filling block 1. The prestressed constraining block includes a double-cone-shaped filling block 1 and a clamping edge hoop 23 for assembling the double-cone-shaped filling block 1. Fig.24 and Fig.25As shown, the double-frustum filling block 1 of this embodiment has the same double-frustum structure as that of the second embodiment. Two clamping edge hoops 23 fixedly connected together are assembled on the same double-frustum filling block 1, which are respectively wrapped around the outer cone surface and the small end surface of the two reverse cones of the double-frustum filling block 1. The clamping edge hoops 23 have a conical inner ring with the same shape as the outer cone surface of the corresponding cone and an annular clamping edge 28 arranged on the circumference of the small end surface of the cone. The annular clamping edge 28 can be regarded as the groove-type hoop 22 in the second embodiment formed in a circular area smaller than the inner ring diameter at the center of the panel 27. The clamping edge hoops 23 on the same double-frustum filling block 1 The inner ring conical surface of is a reverse conical surface, corresponding to the two reverse frustums on the double frustum filling block 1, the inner ring of the clamping edge hoop 23 and the outer conical surface of the corresponding frustum are wedged through the conical surface cooperation, and at the same time, the clamping edge hoop 23 positions the outer circle of the small end surface of the frustum, but exposes most of the center area of ​​the small end surface of the frustum, and the force condition of the frustum on the inner ring side of the clamping edge hoop 23 is the same as that of the cylindrical hoop; after the two frustums of the double frustum filling block 1 are both equipped with the clamping edge hoop 23, the clamping edge hoop 23 of the two frustums on the same double frustum filling block 1 are fixedly connected, that is, assembled to form the prestressed constraint block as a whole of this embodiment.

[0094] See also Fig.24 and Fig.25 In the present embodiment, the fixed connection between the edge clamps 23 is achieved by arranging an anchor plate 24 extending circumferentially from the edge clamps 23, which will not be described in detail in this embodiment.

[0095] Since most of the two end surfaces of the double-cone filling block 1 of this embodiment are not blocked by the clamping edges, it can be used for transparent armor while providing axial prestress through bolt connection.

[0096] Embodiment 7

[0097] Embodiments 1 to 6 provide a prestressed constraint block unit of the bullet-proof layer composed of a single double-cone filling block. On this basis, the implementation scheme of this embodiment adopts a prestressed constraint block unit of multiple double-cone filling blocks.

[0098] See also Fig.26 and Fig. 27The double-cone embedded prestressed constrained bullet-proof layer shown in the figure includes seven double-cone filling blocks 1 and two constraint frames 2. The constraint frame 2 is a circular plate-like structure. The constraint frame 2 is provided with seven cylindrical hoops 21 for embedding the double-cone filling blocks 1. The cone of the double-cone filling block 1 adopts a hexagonal cone with a regular hexagonal cross section. The inner circle of the cylindrical hoop 21 is a hexagonal cone with a corresponding regular hexagonal cross section. The assembly and embodiment 1 between a single cylindrical hoop 21 and a double-cone filling block 1. The six cylindrical hoops 21 on the constraint frame 2 are arranged in a manner of one center and six peripheries, and the adjacent cylindrical hoops 21 share the same side edges, and are laid into a continuous plane. The outer circumference of the constraint frame 2 is connected to the outer cylindrical hoops 21, and the outer circumference is avoided. The outer area of ​​the outer cylindrical hoops 21 is set as an anchor plate 24, and screw holes are set on the anchor plate 24. Six screw holes are evenly distributed along the circumferential direction of the constraint frame 2. During assembly, first push all the double-cone filling blocks 1 into all the cylindrical hoops in the lower constraint frame 2, cover the upper constraint frame 2 and apply thrust, push the other cone of all the double-cone filling blocks 1 into all the cylindrical hoops in the upper constraint frame 2, and then lock the two constraint frames by passing bolts through the aligned screw holes on the two constraint frames 2 in turn.

[0099] The multiple double-cone filling blocks in the prestressed constraint block of this embodiment share a set of constraint frames, which increases the protection area. When only one filling block is damaged, there is no need to replace other prestressed constraint blocks. Only the damaged filling block needs to be taken out and replaced. This is more cost-effective than replacing the entire large-area prestressed constraint block.

[0100] Embodiment 8

[0101] See also Fig.28 The double-cone filling block 1 in the above scheme is a two-layer structure, the two-layer structure is divided into two reverse cones with the maximum cross section of the double cone as the dividing surface, the two-layer structure of the cone is made of ceramic for superposition, a graphite retention layer 32 is arranged between the cones of the two-layer structure, and a graphite retention layer 32 is arranged on the surface of the ceramic plate of the first layer structure 11 in the projectile direction. If the double-cone filling block 1 with a two-layer structure is assembled with a grooved sleeve 22, a cushioning layer or a toughness enhancement layer can be padded between the small end face of the cone of the two-layer structure and the panel 27 of the grooved sleeve 22. For the cone of the multi-layer structure, one or more materials of ceramic, concrete, and glass can be selected for lamination according to the application of the bullet-shielding layer.

[0102] Embodiment 9

[0103] In order to prevent the multi-layer structure frustum from being delaminated or partially damaged during the process of being pushed into the hoop to apply prestress, the surface of the double frustum filling block 1 shown in the eighth embodiment is wrapped with a surface reinforcement layer 34 for overall reinforcement, such as Fig.29As shown, the surface reinforcement layer 34 is one or more materials selected from polymer, fiber reinforced polymer or metal sheet. If the double-cone embedded prestressed constrained bullet-proof layer is a transparent armor, then the multi-layer main material is transparent ceramic, glass or other transparent materials, and the surface reinforcement layer 34 is made of transparent polymer materials such as organic glass (polymethyl methacrylate); or only the non-transparent surface reinforcement layer 34 is wrapped on the side, and the upper and lower surface layers are missing. The retention layer is made of transparent material, such as PVB (polyvinyl butyral) or organic glass, or other interlayer film materials (SGP, EVA, PU).

[0104] The above are only some specific implementation methods of the present invention, but the design concept of the present invention is not limited to them. Any non-substantial changes to the present invention using this concept shall be deemed as an act that infringes the protection scope of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments in any form according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.

[0105] The technical effect of the present invention is described below by performing a model simulation on the first embodiment.

[0106] The materials of the hoop and double truncated cone of the prestressed constraint block are steel and concrete, respectively. The height and inner diameter of the large end of a single steel hoop are 50 mm and 100 mm, respectively. The height of the double truncated cone is 100 mm, and the inclination angle α of each cone surface is 3°. The design of the prestressed working condition is shown in Table 1. There are 8 working conditions in total. The insertion depth h of a single steel hoop designed for each working condition corresponds to the surplus δ. The insertion depth of the target body is divided into 7 levels, 2 mm as a level. The radial prestress of the target body increases with the insertion depth, and the working condition with the maximum insertion depth is 14 mm. The tolerance range of the small end diameter of the truncated cone and the inner diameter of the large end of the hoop in each working condition is 3.8 to 5.2 mm.

[0107] Table 1 Prestressing conditions

[0108]

[0109] The explicit finite element program LS-DYNA was used for numerical simulation. The impact projectile is a round-headed projectile with a diameter of 7.62 mm and a length of 25 mm. The finite element model was established based on the geometric dimensions of the steel ferrule and the double-cone concrete target. The entire model consists of a ferrule, a double-cone, a projectile, a pad and a thrust block, a total of 5 parts, modeled with 8-node solid hexahedron units (*SECTION_SOLID). According to the symmetry conditions, only a 1 / 4 model symmetrical along the YZ plane and the XZ plane was established. The average grid size of the projectile is 1 mm, and a total of 284 units are divided. In order to improve the simulation accuracy, the core area of ​​the double-cone where the projectile enters is meshed, and the mesh of the remaining parts is gradually thickened around. Within the radius (15mm) of the core concrete center of the double cone, the unit size is 0.5mm×0.5mm×0.5mm, and a total of 171,600 units are divided. The unit size of the edge of the double cone is about 5mm×0.5mm×0.5mm, and a total of 65,800 units are divided. The average unit size of a single steel hoop is about 2mm×2mm×0.5, and a total of 14,400 units are divided. The entire finite element model has a total of 266,484 units. Automatic surface contact (keyword *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE) is used between the hoop, double cone, pad, and thrust block. The static friction coefficient between the two is set to 0.1 and the dynamic friction coefficient is 0.08. The contact between the projectile and the concrete is realized using the keyword *CONTACT_ERODING_SURFACE_TO_SURFACE.

[0110] The concrete material adopts HJC model, and the concrete density is 2400kg / m 3 , the axial compressive strength is 120 MPa, and the specific parameters are shown in Table 2. The *MAT_ADD_EROSION erosion failure criterion is introduced to avoid the hourglass effect caused by unit distortion affecting the stability of the calculation. The maximum principal strain is used to control the unit failure. When the maximum principal strain of the target unit exceeds the set failure strain, the unit failure is deleted.

[0111] Table 2 Parameters of HJC constitutive model of concrete

[0112]

[0113]

[0114] The steel hoop material uses the plastic-dynamic model (*MAT_PLASTIC_KINEMATIC / MAT_003) in LS-DYNA to simulate the dynamic behavior of the hoop. According to the von Mises yield criterion, an elastic-plastic model with dynamic hardening plasticity is established. The main parameters of the model are shown in Table 3.

[0115] Table 3 Steel ferrule material parameters

[0116]

[0117] During the penetration process, the projectile will experience failure under large strain, high strain rate and high temperature environment. This simulation uses the Johnson-Cook material model tungsten alloy projectile, and the specific parameters are shown in Table 4.

[0118] Table 4 Main parameters of round-headed long-rod projectile material model

[0119]

[0120] The loading system and test process are divided into two stages. In the first stage, the prestressed cone is pushed into the cone for simulation test, and then the anti-penetration simulation test is carried out in the second stage. In the first stage, the keyword *BOUNDARY_PRESCRIBED_MOTION_SET is used to assign the displacement of the thrust block to push the concrete cone into the steel hoop. The loading rate is 1mm / ms. It reaches the specified depth of the hoop and stabilizes for 10ms to generate the corresponding restart file. Subsequently, the projectile penetration stage (the second stage) is entered. The full restart function in LS-DYNA is used to simulate the second stage. The original k file is modified, and the units and boundaries irrelevant to the penetration process are deleted. The projectile unit and its corresponding material parameters and velocity parameters are added. The projectile velocity is assigned by the keyword *CHANGE_VELOCITY_GENERATION, and the stress state of each component in the previous process is transferred to the corresponding components in the restart process by the keyword *STRESS_INITIALIZATION.

[0121] (1) Prestressed loading

[0122] After prestressing in each working condition, it can be found that the prestress of the concrete double truncated cone increases with the increase of the insertion depth. Except for the local damage and cracks of the lower end unit of the truncated cone in the last working condition due to excessive prestress, no damage was found in the truncated cones of other working conditions. The relationship curve between the average prestress of the unit at a height of 25mm and 75mm on the central axis of the double truncated cone and the insertion depth is shown in the figure below: Fig.30As shown, the prestress increases linearly with the increase of the insertion depth. The prestress can be adjusted by the insertion depth, and a sufficiently large prestress can be applied. In addition to predicting the size of the prestress by the insertion depth, the size of the prestress can also be predicted by establishing the relationship between the thrust and the prestress, and the size of the prestress can be controlled by the insertion depth and the thrust. It is noted that when the target is pushed in 12mm, the average prestress applied to the target is 253MPa, which is 2.1 times the axial compressive strength of concrete, and the concrete target is almost not damaged. This is because the hoop effect of the steel ring increases the strength of the concrete. In addition, the strength of the concrete is further improved by the effect of the prestress, and there is almost no damage even if the radial stress reaches 253MPa.

[0123] (2) Analysis of penetration simulation results

[0124] The penetration simulation was carried out with a round-headed bullet at a speed of 1000m / s. The stress cloud diagrams of each target at 0.025ms after the projectile started to penetrate and 0.225ms after the penetration ended are shown in the following figure. Fig.31 As shown, combined Fig.32 The relationship curves of the penetration depth and penetration depth reduction rate of the target body and the prestress shown in the figure show that with the increase of prestress, the penetration depth gradually decreases. When the pushing depth is 12mm, that is, the average prestress applied to the truncated cone is 253MPa, the penetration depth is 35% lower than that of the concrete double truncated cone with constraint but no prestress, and the anti-penetration performance reaches the best. However, with the further increase of prestress, the anti-penetration performance decreases rapidly. Therefore, applying appropriate prestress by the method of the present invention can significantly improve the anti-penetration performance of the filling block.

Claims

1. Double cone-embedded prestressed constrained bullet-proof layer, characterized by: It includes a double frustum filling block and a hoop for embedding and extruding the double frustum filling block. The double-frustum filling block comprises two coaxial reverse frustums, the two reverse frustums of the double-frustum filling block are connected by a large end face to form a double frustum with a large middle and small ends, and a ferrule is respectively surrounded and sleeved on the outer conical surfaces of the two reverse frustums, the ferrule has an inner ring of the same shape as the outer conical surface of the corresponding frustum, and the inner ring of the ferrule and the outer conical surface of the corresponding frustum are wedged and tightened by the matching of the conical surfaces; the ferrules of the two frustums are fixedly connected.

2. According to the double-cone embedded prestressed constrained bullet-proof layer described in claim 1, the hoop is a cylindrical hoop, and the cylindrical hoop has a continuous through-tube cavity with openings at both ends. After the cylindrical hoop and the corresponding cone are wedged into place, the small end face of the corresponding cone is flush with the end face of the tube cavity of the cylindrical hoop.

3. According to the double-cone embedded prestressed constrained bullet-proof layer of claim 1, the hoop is a groove-type hoop, the large end of the barrel cavity of the groove-type hoop is open, and the small end is closed by a panel, and after the groove-type hoop and the corresponding cone are wedged into place, the small end face of the corresponding cone abuts against the panel.

4. According to the double-cone embedded prestressed constrained bullet-proof layer of claim 3, a retaining layer or a buffering cushion layer is provided between the small ends of the two reverse cones of the double-cone filling block and the panel.

5. According to the double-cone embedded prestressed constrained bullet-proof layer described in claim 1, the hoop is a clamping edge hoop, the large end of the barrel cavity of the clamping edge hoop is open, and an annular clamping edge is arranged on the circumference of the small end. After the clamping edge hoop and the corresponding cone are wedged into place, the small end face of the corresponding cone is limited by the annular clamping edge.

6. According to the double-cone embedded prestressed constrained bullet-proof layer described in claim 2, 3 or 5, the double-cone filling blocks correspond to the hoops of two reverse cones and are fixed by welding or bonding.

7. According to the double-cone embedded prestressed constrained bullet-proof layer of claim 6, a wrapping layer is arranged outside the wedged double-cone filling block and the hoop.

8. According to the double-cone embedded prestressed constrained bullet-proof layer of claim 2, 3 or 5, an anchor plate is provided in the circumferential direction of the hoop, and corresponding screw holes are provided on the hoop anchor plates corresponding to the two reverse cones on the same double-cone filling block, and the hoop is fixedly connected by bolts passing through the screw holes on the anchor plates.

9. According to the double-cone embedded prestressed constrained bullet-proof layer of claim 8, a plurality of said hoops are arranged on a constraint frame, and the corresponding hoops on the two groups of constraint frames are respectively mounted on two reverse cones of a plurality of conical filling blocks, and all the hoops are fixedly connected by anchor plates arranged on the constraint frames.

10. According to the double-cone embedded prestressed constrained bullet-proof layer described in claim 1, the outer wall of the cone of the double-cone filling block and the inner wall of the hoop are respectively matching conical surfaces, or matching polygonal pyramid surfaces, and the outward small end face of the cone of the double-cone filling block is a plane or an outer convex surface.

11. According to the double-cone embedded prestressed constrained bullet-proof layer of claim 1, the double-cone filling block is a multi-layer structure, and the double-cone filling block is formed by stacking one or more materials selected from ceramics, concrete, and glass, and a retaining layer, a buffer layer, or a toughness enhancement layer is arranged between each layer of material or on the end surface.

12. The double-truncated cone extruded prestressed constrained bullet-proof layer according to claim 11, wherein the surface of the double-truncated cone filling block is wrapped with a fiber-reinforced polymer or a metal sheet to form a surface reinforcement layer.

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