CN111207644A - Interlayer cooperative gain active shock wave and fragment protection method and system - Google Patents

Interlayer cooperative gain active shock wave and fragment protection method and system Download PDF

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Publication number
CN111207644A
CN111207644A CN201911214572.9A CN201911214572A CN111207644A CN 111207644 A CN111207644 A CN 111207644A CN 201911214572 A CN201911214572 A CN 201911214572A CN 111207644 A CN111207644 A CN 111207644A
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layer
shock wave
fragment
protective layer
protection
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黄广炎
朱炜
黄风雷
陈鹏万
刘彦
王海福
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Beijing Institute of Technology BIT
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Beijing Institute of Technology BIT
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D5/00—Safety arrangements
    • F42D5/04—Rendering explosive charges harmless, e.g. destroying ammunition; Rendering detonation of explosive charges harmless
    • F42D5/045—Detonation-wave absorbing or damping means

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  • General Engineering & Computer Science (AREA)
  • Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)

Abstract

The invention provides an interlayer cooperative gain active shock wave and fragment protection method and system, which utilize the pre-acceleration active protection concept, realize the cooperative gain effect between protection layers and simultaneously improve the shock wave and fragment efficiency of two protection layers. The method specifically comprises the following steps: the method comprises the following steps that an explosive-faced surface weakens an incoming explosive shock wave through a shock wave protective layer, and a back explosive surface captures an incoming fragment through a fragment protective layer based on high-performance fibers; and before the explosive load reaches the shock wave protective layer, the shock wave protective layer and the fragment protective layer are pre-accelerated respectively, so that the shock wave protective layer has an initial speed opposite to the direction of the incoming explosive load, and the fragment protective layer has an initial speed the same as the direction of the incoming explosive load.

Description

Interlayer cooperative gain active shock wave and fragment protection method and system
Technical Field
The invention relates to a shock wave and fragment protection method, in particular to an active shock wave and fragment protection method based on interlayer synergistic gain, and belongs to the technical field of public safety protection.
Background
Shock waves and fragment loads generated in the explosion process of military or self-made simple explosive devices often cause great harm to personnel, equipment and facilities in the surrounding environment; the design of explosion protection structures has been the focus and key point of domestic and foreign research. In order to reduce the secondary damage of the fragment load, more and more research attention is being paid to the shift from the traditional high-strength materials to structurally fragile materials, such as fine sand, liquid, non-metal porous materials (polyurethane foam), non-metal particle materials (perlite), high-performance fiber cloth and the like. Most of the materials have the characteristics of low density and low structural strength (the materials are low in multi-finger shear, compression or tensile fracture strength and easy to break), and are easy to break into small particles (fragments) under the action of explosive load, so that secondary destructive fragments cannot be generated, and the explosion-proof structure based on the structurally fragile materials has the advantages of light dead weight, higher safety and the like.
How to combine different kinds of structurally weak materials to improve the impact protection efficiency of explosion-proof structures is the focus of current research.
Disclosure of Invention
In view of this, the invention provides an interlayer cooperative gain active shock wave and fragment protection method, which utilizes the pre-acceleration active protection concept, realizes an interlayer cooperative gain effect, and can simultaneously improve the shock wave and fragment protection efficiency of two layers of materials.
An active shock wave and fragment protection method with interlayer cooperative gain is characterized in that a shock wave protective layer is arranged on a blast-facing surface to weaken an incoming explosive shock wave, and a fragment protective layer is arranged on a back blast surface to capture the incoming fragment; and respectively pre-accelerating the shock wave protective layer and the fragment protective layer before the explosive load reaches the shock wave protective layer, so that the shock wave protective layer has an initial speed opposite to the direction of the incoming explosive load, and the fragment protective layer has an initial speed in the same direction as the direction of the incoming explosive load; the fragment protective layer is a protective layer based on high-performance fibers, and the shock wave protective layer is made of flexible protective materials.
As a preferable mode of the present invention, the shock wave shield layer and the fragment shield layer are pre-accelerated by igniting initiating explosive material between the shock wave shield layer and the fragment shield layer to apply work to the shock wave shield layer and the fragment shield layer, respectively.
In addition, the present invention provides an active shock wave and fragment protection system with interlayer cooperative gain, comprising: the device comprises a shock wave protective layer, a fragment protective layer and a pre-acceleration layer arranged between the shock wave protective layer and the fragment protective layer; the fragment protective layer is a protective layer based on high-performance fibers, and the shock wave protective layer is made of flexible protective materials; when the shock wave protection layer is used, the shock wave protection layer is used as a detonation facing surface;
an excitation device is arranged in the pre-acceleration layer and is electrically connected with a front-end trigger sensor arranged between the explosive and the protection system; when the front-end trigger sensor senses an explosive load, an excitation signal is sent to an excitation device in the pre-acceleration layer, the excitation device drives the pre-acceleration layer, the pre-acceleration layer does work on the shock wave protection layer and the fragment protection layer after being started, so that the shock wave protection layer has an initial speed opposite to the direction of the incoming explosive load, and the fragment protection layer has an initial speed the same as the direction of the incoming explosive load;
the front-end trigger sensor is arranged at a position which ensures that the pre-acceleration layer is started within a set time before the explosive load reaches the protection system.
In a preferred embodiment of the present invention, the excitation device includes two or more driving points disposed in the same plane inside the pre-acceleration layer, and after receiving the excitation signal of the front-end trigger sensor, the excitation device simultaneously starts to drive the pre-acceleration layer at all the driving points.
In a preferred embodiment of the present invention, a propellant is provided in the pre-acceleration layer, and the excitation device is an igniter of the propellant.
Advantageous effects
(1) The interlayer cooperative gain active shock wave and fragment protection method provided by the invention considers the shock wave and fragment load at the same time, considers the difference of shock wave/fragment protection mechanisms of different types of fragile materials with different structures, utilizes the pre-acceleration active protection concept, realizes the interlayer cooperative gain effect, and can simultaneously improve the shock wave and fragment protection efficiency of two layers of materials.
(2) The whole protection system comprises three layers, wherein the pre-acceleration layer converts the chemical energy or potential energy of the pre-acceleration layer into momentum of other two layers; since the pre-acceleration layer is located in the middle, the momentum obtained by the protective layer of the B-type material located at the front end of the pre-acceleration layer is opposite to that obtained by the protective layer of the P-type material located at the rear end of the pre-acceleration layer, and the respective momentums have promoting effects on the respective protective performances. And because the pre-acceleration layer is arranged in the middle, the whole protection system is in momentum conservation after energy conversion, so that momentum balance at two sides can be realized, secondary momentum can be effectively prevented from being introduced into the environment, and the protection system has more reasonable practical application.
Drawings
FIG. 1 is a diagram of a protection system configuration employing the shock wave and fragment protection method of the present invention;
fig. 2 is a schematic diagram of relative reverse acceleration of the protective layers on the two sides under the action of the pre-acceleration layer after the pre-acceleration layer is excited.
Wherein: 1-class B material protective layer, 2-pre-acceleration layer, 3-class P material protective layer, 4-excitation device, 5-front-end trigger sensor and 6-incoming explosive load
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the examples. The following structural examples are provided to illustrate the present invention, but are not intended to limit the scope of the present invention.
The embodiment provides an interlayer cooperative gain active shock wave and fragment protection method, which considers the difference of shock wave/fragment protection mechanisms of fragile materials with different types of structures, utilizes the pre-accelerated active protection concept to realize the cooperative gain effect between two protection layers, and can simultaneously improve the shock wave and fragment protection efficiency of two layers of materials.
The active protective structure with synergistic interlayer can simultaneously weaken the blast shock wave and greatly reduce the fragment speed, so the used structural fragile materials can be divided into two types according to the purposes: one is a typical fragment protection material (called as a P-type material), such as various high-performance fiber cloth, and the main protection mechanism is the fracture of a high-strength material; another class is typical blast protection materials (referred to as class B materials) such as fine sand, liquids, non-metallic cellular materials (polyurethane foam and perlite) and the like, which have good blast load attenuation properties, and an important point in the blast protection mechanism is the momentum extraction effect, which also reduces the fragment motion velocity.
For class P materials, high strength material breaks are classified into direct tension, out-of-plane shear, and indirect tension, and these failures are all dependent on the stress (pressure) level S that the fragments create in the material. For a stationary target plate, S is substantially dependent on the projectile impact velocity ViNamely: s-i(ii) a The research finds that: if the material is pre-accelerated (i.e. it attains an initial velocity V) before the fragment hits the P-type material target platepIts direction is equal to ViSame) V required to cause the material to breakiThe reason for this is: fundamentally S depends on the relative speed of the fragment and the target plate, i.e.: s-i－Vp(ii) a Whereby VpIs present so that the same hit target speed ViUnder the condition that S is smaller, the material P is more difficult to break, so that the anti-elasticity performance of the target plate is improved.
For B-class materials, the dominant protection mechanisms of shock waves and fragments are momentum extraction effects; the target plate made of the B-type material can obtain a maximum average speed V after the protection of the shock wavebcAfter a certain fragment protection, a maximum speed V is locally obtainedbp. For a stationary target plate, the rate of shock wave reduction C caused by the momentum extraction effectrAnd the rate of decrease P of the chipping speedrAll depending on the mass m of the target platebI.e. the larger the mass of the target plate made of the B-type material, the better the protection effect. For class B materials that are partially energy absorbing by plastic deformation itself,such as polyurethane foam, which additionally causes a reduction in the shock wave, also depends on the mass m of the target plate of class B materialb. Therefore, in order to provide good protection for the B-type material, the weight m of the target platebIt needs to be large enough.
If the target plate made of the B-type material is accelerated in advance before the impact wave and fragment load come on (even if the target plate obtains an initial velocity V)b0In a direction opposite to the incoming shock wave and fragment velocity). When the shock wave comes, the relative speed between the coming shock wave and the B-class material target plate is increased, and the B-class material target plate still obtains a maximum average speed V after the shock wave action is finishedbcIt is clear that this process dissipates more shock wave energy than in a stationary situation, i.e. CrAnd is increased. Similarly, when the fragment comes, the relative velocity between the fragment and the B-type material target plate becomes larger, and research shows that the fragment kinetic energy dissipated by the B-type material target plate with fixed areal density increases along with the increase of the relative velocity between the fragment and the B-type material target plate. The reason is that the drag resistance of the fragments in the B-type material target plate is increased, so that the energy dissipation efficiency of the B-type material target plate is improved, namely the fragment speed reduction rate PrAnd is increased. In summary, if the target plate made of the B-type material can be subjected to reverse pre-acceleration before the impact of the shock wave and the fragments, the protection efficiency of the shock wave and the fragments can be improved.
Aiming at the analysis of the protection characteristics of the P-type material and the B-type material, an active shock wave and fragment protection method based on cooperative gain is provided.
As shown in fig. 1, a class B material protective layer 1 is arranged on a blast-facing surface (i.e., an explosive load attack direction), a class P material protective layer 3 is arranged on one side of a back blast surface, and a pre-acceleration layer 2 is arranged between the class B material protective layer 1 and the class P material protective layer 3; in this example, the protective material in the protective layer 1 made of the B-type material is pure water, the protective material in the protective layer 3 made of the P-type material is an ultra-high molecular weight polyethylene fiberboard, which is structurally fragile, and the weight ratio of the two materials is 5: 1. a pre-acceleration layer 2 based on gunpowder propellant is clamped between a B-type material protective layer 1 and a P-type material protective layer 3, and the acting direction of the gunpowder propellant is limited to the normal direction of the protective layer (namely the spraying direction of the spray pipes is along the normal direction of the protective layer) in the pre-acceleration layer 2 through a plurality of independent spray pipes. When the fragment protection layer 3 is a fragile material with a structure which does not resist high temperature, a heat insulation (fire proof) material, such as fire proof cotton, is bonded on the end surface of one side of the fragment protection layer 3 facing the pre-acceleration layer 2, so as to prevent the high-performance fiber fabric from melting or burning in the working process of gunpowder. The excitation device 4 is arranged at the center of the pre-acceleration layer 2, and the excitation device 4 is an igniter of gunpowder propellant. The excitation device 4 is connected by a cable to a front-end trigger sensor 5 located close to the location of the incoming explosive load 6.
The function of the type B material armor layer 1 is to attenuate the incoming blast shock wave and to some extent reduce the speed of the fragment, while the function of the type P material armor layer 3 is to fully capture the incoming fragment, without regard to the pre-acceleration layer 2 layer. When the pre-acceleration layer 2 is considered, the front-end trigger sensor 5 is matched, when explosives explode, when the fastest load part in explosive loads (shock waves and fragments) reaches the position of the front-section trigger sensor 5, the front-end trigger sensor 5 is triggered, the front-end trigger sensor 5 immediately transmits an ignition signal to the excitation device 4 in the pre-acceleration layer 2 through a cable, the pre-acceleration layer 2 can be further excited before the explosive shock waves and the fragment loads come, the arrangement position of the front-end trigger sensor 5 is ensured to ensure that the pre-acceleration layer 2 works to the B-class material protective layer 1 and the P-class material protective layer 3 on two sides of the pre-acceleration layer in a gunpowder ignition mode within a set time (generally a few ms) before the explosive loads reach the protective structure, so that the B-class material protective layer 1 is reversely pre-accelerated, and the P-class material protective layer 3 is forwardly pre-accelerated, when the explosive load reaches the protective structure, the protective layer 1 made of the B-class material has an initial speed V opposite to the direction of the incoming explosive load 6bWhereas the protective layer 3 of a material of the P type has an initial velocity V opposite to the direction of the incoming explosive load 6pAs shown in fig. 2. Based on the protection characteristics of the P-type material and the B-type material, the pre-acceleration of the B-type material protection layer 1 and the P-type material protection layer 3 caused by the pre-acceleration layer 2 is beneficial to the improvement of the protection efficiency of respective shock waves and/or fragments.
From a practical point of view, the acceleration process of the layer 2 is accelerated beforehandThe time advance of the front-end trigger sensor 5 is matched, namely the acting time of the pre-acceleration layer 2 and the time interval of the explosion load reaching the protective structure are in the ms level; and the initial velocity V of the protective layer 3 made of P-type materialpCan reach the hundred meters per second grade, and the initial speed V of the protective layer 1 made of the B-class materialbCan reach the fifty meters/second level. In order to realize the function, a mode of igniting gunpowder propellant or exploding small-equivalent low-speed explosive is adopted in the pre-acceleration layer 2, and compared with mechanical structures such as springs, the initiating explosive has high work efficiency, but higher stress cannot be generated in the P-type material protective layer 3 and the B-type material protective layer 1 (mainly, stress accumulation cannot be generated in the P-type material protective layer 3, or transient pressure is not generated to enable the P-type material protective layer 3 to be damaged in advance). After the pre-acceleration, the pre-acceleration layer 2 is damaged and disappears, the B-class material protective layer 1 and the P-class material protective layer 3 are subjected to acceleration, the driving overload is low due to the fact that the driving time is in the ms level, and the two protective layers can keep good structural integrity as long as the driving load keeps good plane uniformity. And for the protective layer 3 made of the P-type material, due to the fact that the axial tensile strength of the protective layer is high (such as fiber composite materials), the low overload working condition is driven by gunpowder. Even if the planarity of the pre-driven load is poor, the self structure can transmit transverse shear waves, fiber breakage is difficult to occur, and good structural integrity can be maintained. For the protective layer 1 made of the B-type material, the structural integrity of the intermediate pre-acceleration layer 2 can be ensured not to be influenced in the following two ways; a. ensuring that the driving load maintains good planar uniformity (specifically, a plurality of driving points can be uniformly distributed at intervals in the plane of the excitation device 4 of the pre-acceleration layer 2, and simultaneously ignited); b. and a super-elastic layer such as polyurea is sprayed on one side of the B-type material protective layer 1 facing the pre-acceleration layer 2, so that the fracture caused by uneven driving load in a plane is inhibited, and the structural integrity is ensured.
As the protection mechanism of the protective layer 1 made of the B-class material on the blast shock wave and the broken piece is momentum extraction, the initial speed V of the protective layer 1 made of the B-class materialbThe protection efficiency of the anti-explosion device on the explosion shock waves and the fragments is improved; due to the protective layer 3 (ultra-high molecular weight polyethylene fiber board) of P-type materialThe breaking protection mechanism is that the stress in the fiber reaches the self strength to break, so the initial speed V of the P-type material protective layer 3pThe speed difference between an incoming fragment and the P-type material protective layer 3 can be reduced, the contact pressure (stress magnitude) formed in the P-type material protective layer 3 during fragment impact is reduced, and the fragment protection efficiency of the P-type material protective layer 3 is further improved.
In addition, because the B-class material protective layer 1 and the P-class material protective layer 3 are respectively positioned at two sides of the pre-acceleration layer 2, namely in the pre-acceleration process, the reaction force of the gunpowder propellant on the force of the B-class material protective layer 1 doing work is the force of the P-class material protective layer 3 doing work, and the opposite is also true. Therefore, the protective layers on the two sides are in a cooperative gain state, momentum self-balance of a protective system can be realized, and additional momentum damage to the surrounding environment is greatly reduced.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. An active shock wave and fragment protection method with interlayer synergistic gain is characterized in that an explosive shock wave is weakened on a blast-facing surface through a shock wave protection layer, and an explosive fragment is captured on a back blast surface through a fragment protection layer; and respectively pre-accelerating the shock wave protective layer and the fragment protective layer before the explosive load reaches the shock wave protective layer, so that the shock wave protective layer has an initial speed opposite to the direction of the incoming explosive load, and the fragment protective layer has an initial speed in the same direction as the direction of the incoming explosive load; the fragment protective layer is a protective layer based on high-performance fibers, and the shock wave protective layer is made of flexible protective materials.
2. The method of claim 1, wherein the shock wave shield and the fragmentation shield are pre-accelerated by initiating an initiating agent between the shock wave shield and the fragmentation shield to perform work on the shock wave shield and the fragmentation shield, respectively.
3. An active shock wave and fragment protection system with synergistic interlamination, comprising: the device comprises a shock wave protective layer, a fragment protective layer and a pre-acceleration layer arranged between the shock wave protective layer and the fragment protective layer; the fragment protective layer is a protective layer based on high-performance fibers, and the shock wave protective layer is made of flexible protective materials; when the shock wave protection layer is used, the shock wave protection layer is used as a detonation facing surface;
an excitation device is arranged in the pre-acceleration layer and is electrically connected with a front-end trigger sensor arranged between the explosive and the protection system; when the front-end trigger sensor senses an explosive load, an excitation signal is sent to an excitation device in the pre-acceleration layer, the excitation device drives the pre-acceleration layer, the pre-acceleration layer does work on the shock wave protection layer and the fragment protection layer after being started, so that the shock wave protection layer has an initial speed opposite to the direction of the incoming explosive load, and the fragment protection layer has an initial speed the same as the direction of the incoming explosive load;
the front-end trigger sensor is arranged at a position which ensures that the pre-acceleration layer is started within a set time before the explosive load reaches the protection system.
4. The inter-layer cooperative gain active blast and fragmentation protection system of claim 3 wherein said excitation means includes two or more drive points disposed in the same plane within said pre-acceleration layer, and wherein upon receipt of an excitation signal from said front-end trigger sensor by said excitation means, all of said drive points are simultaneously activated to drive said pre-acceleration layer.
5. An interlaminar synergy-gain active blast and fragment protection system as defined in claim 3 or 4, wherein said pre-acceleration layer is provided with a propellant powder therein, and said excitation means is an igniter for the propellant powder.
6. An active shock wave and fragment protection system with synergistic interlayer gain as claimed in claim 5, wherein more than two independent nozzles are provided in said pre-acceleration layer, so that the working direction of said propellant powder is along the normal direction of said shock wave protection layer and said fragment protection layer.
7. An interlaminar cooperative gain active blast and fragmentation protection system according to claim 3 or 4, wherein a superelastic layer is provided on the end face of the blast protection layer facing the pre-acceleration layer.
8. The interlaminar cooperative enhanced active blast and fragment protection system of claim 3, wherein a fire barrier is provided on an end surface of said fragment protection layer on a side facing the pre-acceleration layer.
9. The interlayer cooperative gain active blast and fragmentation protection system of claim 3, wherein the protection material in said blast protection layer is explosion-proof liquid or fine sand or non-metallic porous material or non-metallic lattice material or non-metallic granular material, and the material of said fragmentation protection layer is high performance fiber fabric.
CN201911214572.9A 2019-12-02 2019-12-02 Interlayer cooperative gain active shock wave and fragment protection method and system Pending CN111207644A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112781460A (en) * 2020-12-25 2021-05-11 清华大学 Device and method for actively controlling and protecting explosion shock waves

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112781460A (en) * 2020-12-25 2021-05-11 清华大学 Device and method for actively controlling and protecting explosion shock waves
CN112781460B (en) * 2020-12-25 2021-12-10 清华大学 Device and method for actively controlling and protecting explosion shock waves

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