CN112161540B - Hollow annular flexible explosion-proof structure and design method thereof - Google Patents
Hollow annular flexible explosion-proof structure and design method thereof Download PDFInfo
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Abstract
The invention discloses a hollow annular flexible explosion-proof structure and a design method thereof. The invention deeply understands and comprehensively analyzes the joint action rule of the internal explosion shock wave and fragments of the hollow annular flexible explosion-proof structure, and further provides the design process and the design result of the explosion-proof structure based on the explosion-proof mechanism of the explosion-proof structure, and the design process not only considers the joint action effect, but also grasps the main control factor of each parameter; the parameter determination idea is clear and clear, reliable and efficient. Therefore, the design method disclosed by the invention is comprehensive and deep, has strong logicality, and can provide scientific and systematic guidance for efficient and economic design of flexible explosion-proof equipment.
Description
Technical Field
The invention relates to the technical field of structural design of explosion-proof devices, in particular to a hollow annular flexible explosion-proof structure and a design method thereof.
Background
In recent years, flexible explosion-proof equipment is based on low-density fragile structural materials, is easy to disintegrate and break under the action of explosive load, does not generate secondary destructive fragments, has stronger safety and application prospect, and is increasingly applied to explosive disposal. Common hollow annular flexible explosion-proof equipment, such as explosion-proof bucket, explosion-proof jar, explosion-proof rail (blanket) and explosion-proof retaining wall etc. mainly comprise one end open-ended cavity staving and supporting lid, through the design such as material, size of staving, lid, reach the effect that prevents the explosion and reveal. In the existing hollow annular flexible explosion-proof equipment, a main body protection structure of a barrel body consists of an internal liquid layer and an external fiber composite material layer; the protection main body protection structure of the cover body is a liquid layer. The liquid layer of the barrel body is matched with the cover body and used for weakening the internal explosion shock wave and extinguishing explosion flame, and the liquid of the barrel body also has the function of reducing the high-speed fragment speed; while the fiber layer of the barrel serves to completely capture the fragments. The existing design method of the hollow annular flexible explosion-proof equipment is designed based on single load (fragments or shock waves) from the economical point of view, and the coupling effect of the fragments and the shock waves is not considered, so that a design method considering the coupling effect of the fragments and the shock waves is still lacked at present and is used for guiding the scientific and reasonable design of the hollow annular flexible explosion-proof equipment.
Disclosure of Invention
In view of the above, the invention provides a hollow annular flexible explosion-proof structure and a design method thereof, which can fully consider the coupling effect of fragments and shock waves, can effectively intercept all explosion fragments, has a safety distance of 3.5m, can reduce the pressure peak value of the shock waves to be below the human body injury-free standard of 0.03MPa, and has a good protection effect.
The hollow annular flexible explosion-proof structure comprises a hollow barrel body with an opening at one end and a cover body, wherein the barrel body comprises a liquid layer and a fiber layer from inside to outside; the inner diameter of the barrel body is the minimum size capable of accommodating explosives or explosive storage equipment; the height of the barrel body is the minimum height capable of intercepting all fragments; the surface density of the barrel body liquid layer is the minimum surface density for avoiding the outward leakage of the initial shock wave; the surface density of the fiber layer of the barrel body is the minimum surface density for completely capturing the fragments; the areal density of the cap is the critical areal density that results in the least lateral momentum.
Preferably, the height H of the barrel body is
H＝(D+2T)·tanθ+150
Wherein D is the inner diameter of the barrel body (1); t is the thickness of the barrel body (1) and is taken as 100 mm; theta is the explosive dispersion angle.
Preferably, the minimum areal density of the barrel liquid layer to avoid the outward leakage of the initial shock wave is determined by numerical simulation or experiment.
Preferably, the liquid layer density AbComprises the following steps:
Ab＝Abmin,r(me/me,r)1/3(H/Hr)/(D/Dr)
wherein m ise,rTNT equivalent for a known specific explosive; hrAnd DrRespectively the height and inner diameter of the particular explosion proof device known; m iseThe equivalent weight of explosive TNT to be protected by the explosion-proof structure, H and D are the height and the inner diameter of the explosion-proof structure respectively.
Preferably, the minimum surface density of the fully-captured fragments of the fiber layer of the barrel body is determined by ballistic impact experiments; in ballistic impact experiments, the fragments are at an initial velocity VbrImpacting a target plate made of the material of the fiber layer,
wherein, V0maxThe maximum initial velocity of the fragment under the drive of the explosive; vb0The average initial speed of the barrel liquid layer under the loading of explosive blast waves is adopted; m isPFor fragment mass, S is the maximum fragment cross-sectional area, CdIs a dimensionless drag coefficient, AbIs the liquid level density.
The invention also provides a design method of the hollow annular flexible explosion-proof structure, wherein the explosion-proof structure comprises a hollow barrel body with an opening at one end and a cover body, and the barrel body comprises a liquid layer and a fiber layer from inside to outside; the design method comprises the following steps:
step 5, determining the surface density of the cover body: the surface density of the cover body is the critical surface density with the minimum combined impact quantity for realizing lateral air shock waves and liquid drop flying of the explosion-proof structure.
Preferably, in the step 2, the minimum height H of the barrel body for intercepting all fragments is calculated by adopting the following formulamin：
Hmin＝(D+2T)·tanθ+150
Wherein D is the inner diameter of the barrel body determined in the step 1; t is the thickness of the barrel body and is taken as 100 mm; theta is the explosive dispersion angle.
Preferably, in step 3, the minimum areal density at which the initial shock wave is prevented from leaking at the bottom of the explosion-proof structure when the explosive is detonated on the ground is determined by numerical simulation or experiments; in the numerical simulation or the experiment, the method,
s1, placing explosives at the center of the bottom of the explosion-proof structure;
s2, gradually increasing the area density of the liquid layer of the barrel body, and finding out the minimum area density when no pressure leaks outside the bottom of the explosion-proof structure before the initial shock wave is transmitted to the top of the explosion-proof structure through simulation or experiments.
Preferably, first, the liquid level density A of a specific explosive in a specific explosion-proof device of the same structure is determined by using S1 and S2bmin,r(ii) a Then obtaining the liquid layer density A of the explosion-proof structure according to the following formulab：
Ab＝Abmin,r(me/me,r)1/3(H/Hr)/(D/Dr)
Wherein m ise,rTNT equivalent for a particular explosive; hrAnd DrThe height and the inner diameter of the specific explosion-proof device are respectively; m iseThe equivalent weight of explosive TNT to be protected by the explosion-proof structure, H and D are the height and the inner diameter of the explosion-proof structure respectively.
Preferably, in the step 4, the minimum area density for completely capturing the fragments is determined by ballistic impact experiments; in the ballistic impact test, the fragments are at an initial velocity VbrImpacting the target plate prepared by the material of the fiber layer, and continuously increasing the surface density of the target plate of the fiber layer to obtain the minimum surface density of the target plate of the fiber layer which is not penetrated by fragments; wherein the content of the first and second substances,
wherein, V0maxThe maximum initial velocity of the fragment under the drive of the explosive; vb0The average initial speed of the barrel liquid layer under the loading of explosive blast waves is adopted; m isPFor fragment mass, S is the maximum fragment cross-sectional area, CdIs a dimensionless drag coefficient, AbIs the liquid level density.
Has the advantages that:
the invention deeply understands and comprehensively analyzes the joint action rule of the internal explosion shock wave and fragments of the hollow annular flexible explosion-proof structure, and further provides the design process and the design result of the explosion-proof structure based on the explosion-proof mechanism of the explosion-proof structure, and the design process not only considers the joint action effect, but also grasps the main control factor of each parameter; the parameter determination idea is clear and clear, reliable and efficient. Therefore, the design method disclosed by the invention is comprehensive and deep, has strong logicality, and can provide scientific and systematic guidance for efficient and economic design of flexible explosion-proof equipment.
Drawings
Fig. 1 is a schematic view of an explosion-proof structure of the present invention.
FIG. 2 shows the specific process and parameter design indexes of the design method of the present invention.
The device comprises a barrel body 1, a cover body 2, a barrel body liquid layer 3 and a barrel body fiber layer 4.
Detailed Description
The invention is described in detail below by way of example with reference to the accompanying drawings.
The invention provides a hollow annular flexible explosion-proof structure and a design method thereof, wherein the hollow annular flexible explosion-proof structure is shown in figure 1 and comprises a hollow annular barrel body 1 with an opening at one end and a cake-shaped cover body 2, and the hollow annular flexible explosion-proof structure is in a shape of an actual common explosion-proof structure. The barrel body 1 comprises a liquid layer 3 and an external fiber layer 4 which are arranged in equal heights, the inner diameter of the barrel body 1 is D, the height of the barrel body is H, and the area density of the liquid layer 3 is AbThe surface density of the fiber layer 4 is Af. The diameter of the cover body 2 is close to the outer diameter of the barrel body 1, liquid is arranged in the cover body 2, and the surface density of the cover body 2 is Ac. The explosive to be protected is formed by TNT equivalent MeThe mass of the explosive uniformly wrapped around the explosive is MfThe composition of the broken pieces. The protection problem of the invention is the protection problem of the near field of internal explosion, namely, explosives are positioned in the hollow annular flexible explosion-proof structure, the shock wave load generated by explosion can reach the protection structure before the fragment load, and the fragment protection performance of the explosion-proof structure can be influenced by the shock wave load. The specific design process of the protective structure is as follows:
step 0: fragmentation of explosives and analysis of shock wave loading
The good and reliable explosion-proof structure design should determine the explosive load parameters to be protected through unprotected explosion experiments, including overpressure peak value P and impulse I of shock waves reaching the inner surface of the liquid layer of the barrel body with different inner diameters,and initial velocity V of the fragment0Weight m ofpAnd a divergence angle θ. From the viewpoint of economic cost reduction, specific values can also be determined for reference by some classical theoretical calculations, but reliability is much worse. The invention mainly provides a design method of the flexible explosion-proof structure, so that the formulas are not repeated, and the explosion load can be taken as a known parameter.
Step 1: and (5) determining the inner diameter D of the barrel body.
For shock wave protection, under the same weight, the smaller the inner diameter D of the barrel body is, the better the weakening effect of the explosion shock wave outside the flexible explosion-proof structure is.
For fragment protection, from the equal weight design principle, the internal diameter D of the barrel body can cause two effects while reducing: (i) the wall thickness of the barrel body is increased, so that the fragment protection performance can be improved; (ii) the increased shock wave action (i.e., increased peak P and impulse I) to the inner surface of the liquid layer impairs fragment protection. But in combination, the former effect is stronger than the latter.
Therefore, the smaller the barrel body inner diameter D is, the better the fragment and shock wave protection are integrated. However, from the practical point of view, there is a minimum D, i.e. DminTo provide sufficient disposal space to ensure unobstructed placement of explosives or containers containing explosives (e.g., luggage, parcel boxes, etc.) into the blast-resistant equipment. Thus, the barrel inner diameter D is selected to be D constrained by the outer dimension of the explosivemin。
Step 2: and (5) determining the height H of the barrel body.
From the perspective of shock wave protection, the larger the height H of the barrel body is, the more protection is facilitated;
from a fragment protection perspective, the height of the barrel should be sufficient to intercept all fragments. On the premise of intercepting all fragments, the height of the barrel body is reduced, and two effects exist: (i) the cover body reflects the shock wave in the barrel to reach a barrel wall fragment impact area earlier, and the vertical component of the movement speed of the liquid layer of the barrel body caused by the shock wave faces downwards, so that the fragment with the vertical component of the speed being the upper speed can be accelerated to decelerate in the liquid layer of the barrel body, and the fragment protection performance of the barrel body can be improved; (ii) the bucket body is descended by self weight.
In summary, the bucket height H should be taken to be a minimum height H sufficient to intercept all fragmentsmin. Since the explosive scattering angle is known as θ, there are:
Hmin＝(D+2T)·tanθ+150 (1)
wherein, T is the barrel body thickness, and the increase item of 150mm is the compensation length for avoiding the highest broken piece to slip off at the outer layer fiber layer. Because the barrel body thickness T is unknown at the moment, the commonly used maximum thickness of 100mm is firstly adopted.
Step 3: areal density A of barrel liquid layer 3bAnd (4) determining.
The function of the barrel liquid layer 3 is mainly two points: (i) the high wave impedance of the shock wave self restrains the transmission of the shock wave, and the shock wave energy is continuously converted into self kinetic energy through multiple times of shock wave reflection, so that the shock wave load reaching the outside of the protective structure is weakened; (ii) the chipping speed can be reduced from a high speed to a medium-low speed. However, although the burst protection efficiency of the liquid layer 3 is continuously increased along with the rising of the burst speed, the burst protection efficiency is still lower than the protection performance of the fiber composite material (i.e. the barrel fiber layer 4). Therefore, in consideration of light protection requirements, more fiber composite materials should be adopted as much as possible, namely, the surface density of the fiber layer of the barrel body is increased; in other words, the areal density of the liquid layer 3 is selected primarily based on its shock wave protection requirements.
A good blast-proof installation should ensure that the installation is able to dissipate more blast shock wave energy without very strict deadweight constraints. For the barrel liquid layer 3 of the flexible explosion-proof structure, at least before the initial shock wave is transmitted to the whole barrel body, the liquid layer part loaded firstly cannot generate gaps due to the fact that too much speed is obtained, and then the shock wave is leaked out of the barrel prematurely. It is clear that the greater the areal density of the liquid layer 3, the less likely initial leakage will occur and that the areal density of the liquid layer 3 is designed independently of the areal density of the cover 1. Consider the worst case, namely: the explosive is placed on the ground, the shock wave firstly acts on the bottom of the liquid layer 3 and the shock wave is enhanced due to the reflection of the ground, so that the liquid at the bottom of the liquid layer obtains larger speed, and in addition, the initial shock wave needs to be from bottom to topThe pressure can be transmitted to the whole barrel body only after the pressure passes through the height of the whole barrel body, namely the time for maintaining the bottom not to generate pressure leakage is longest; therefore, the minimum areal density of the barrel liquid layer should be: it is possible to ensure such an areal density that the corresponding initial shock wave does not leak out in the worst case. Because the problem of initial shock wave leakage is complex and is difficult to calculate accurately through simple theoretical calculation, the critical surface density A of leakage of the initial shock wave at the bottom of the liquid layer of the barrel body can be determined through numerical simulation or experimentbmin。
In addition, similar analysis can also be used to generalize individual experimental results. According to a reference case result which we already have, namely: an inner diameter Dr300mm, height Hr400mm hollow annular barrel liquid layer for weakening me,rDetermining the minimum area density of the liquid layer of the barrel body as A through experiments and numerical simulation analysis when the TNT explosive is 500gbmin,r≈60kg/m2. Then, based on the explosion similarity law, the reference case can be simply generalized to a general case, that is, for a barrel liquid layer with an inner diameter D and a height H, the minimum critical surface density of the barrel liquid layer is as follows:
Abmin＝Abmin,r(me/me,r)1/3(H/Hr)/(D/Dr) (2)
wherein m iseIs the equivalent of the explosive TNT to be protected by the invention.
Then, the surface density of the barrel liquid layer is taken as Ab＝Abmin。
After the surface density of the barrel body liquid layer is obtained, the thickness of the barrel body liquid layer can be obtained according to the liquid density of the barrel body liquid layer.
S4: areal density A of fiber layer 4 of barrel bodyfAnd (4) determining.
The main function of the fiber layer 4 of the barrel body is to completely capture medium-low speed fragments penetrating out of the liquid layer, namely the maximum initial speed V0maxThe fragments of (a) also cannot penetrate the fibrous layer 4. Since the fragment penetration process occurs after the initial shock wave action, the barrel wall is affected by the pre-acceleration of the shock wave. The numerical analysis shows that the liquid layer can be caused byThe situation that the fragment protection effect is weakened due to the pre-acceleration of the initial shock wave occurs; and the fiber layer is also pre-accelerated by the initial shock wave and liquid layer liquid before the fragment penetration, and under the condition that the fiber layer is penetrated, the existing speed (residual speed) of the fragment penetrating the fiber layer is reduced, but the ballistic limit speed (namely the speed of the fragment just penetrating the fiber layer) of the fragment is basically not influenced. In addition, the invention relates to the problem of multi-fragment protection, and numerical analysis shows that the multi-fragment effect slightly improves the protection effect of the liquid layer, because the similar fragments can make the liquid in the middle of the fragments obtain opposite transverse speeds, thereby increasing the drag force of the liquid on the fragments; but the interaction between such multiple fragment penetrations is small and therefore negligible.
Assuming that the explosive loading parameter is known, i.e. maximum initial velocity V of fragment0maxMagnitude of initial shock wave impulse I corresponding to the position at which the fragment having the greatest initial velocity strikes (penetrates) the inner surface of the liquid layer0Are known. Firstly, the average initial velocity V of the liquid under the action of the initial shock wave is calculatedb0：
Vb0＝2I0/Ab (3)
Wherein 2I0Is the momentum gained by the liquid (i.e. the magnitude of the impulse of the reflected shock wave). In the case of high-speed impact, the penetration of fragments through the liquid layer is mainly dominated by the momentum extraction effect, and the penetration process of fragments in the liquid layer should satisfy the following two conditions:
VP＝dxp/dt (4)
mPdVP/dt＝-0.5·ρbSCdVP 2 (5)
wherein, VPFor breaking the velocity in the liquid layer, xPThe displacement of the fragments in the liquid layer, t being the time, mPFor fragment quality, ρbThe liquid density of the liquid layer, S is the maximum sectional area of the broken piece, CdFor a dimensionless drag coefficient, 0.4 is typically taken. Since the liquid in the liquid layer obtains a certain initial velocity under the action of the shock wave, the fragment-liquid relative velocity V needs to be usedP–Vb0Substitution of V in formula (4) and formula (5)P(ii) a According to the boundary conditions: t is 0, VP＝V0max，xP＝0；VP＝Vbr，xP＝Ab/ρbThe velocity V of the broken piece passing through the liquid layer can be obtainedbrComprises the following steps:
therefore, the areal density A of the fiber layer 4fIt should satisfy: breaking into pieces with VbrWhen the fiber layer is impacted at the initial speed, the fiber layer can not be penetrated; corresponding to a penetration critical area density of AfminI.e. ballistic limit velocity. There are many theoretical models in the literature for determining the ballistic limit of fiber composite target plates, but theoretical analysis is used to determine AfminPoor feasibility exists because (i) the theoretical model between different fiber composite materials (such as UHMWPE non-woven cloth and aramid woven cloth) has obvious difference, and a general formula is difficult to be given; (ii) the penetration mechanism of the fiber composite material is complex, the corresponding theoretical model needs to obtain enough material parameters, and even if the fiber composite material is the same type of material, the corresponding parameters of the fiber composite materials produced by different manufacturers have larger difference, so enough mechanical tests need to be carried out to determine the specific parameters. Therefore, from the viewpoint of reliability, the present invention determines A by using a ballistic impact testfminI.e. selecting fragments same as or close to the explosion condition by VbrThe broken piece is launched at the initial speed, the number of fiber cloth layers is continuously increased, and the number of fiber layers which just meet the requirement that the fiber target plate is not penetrated is determined finally. Finally, the areal density A of the fibre layer 4fIs selected to satisfy Af≥Afmin。
S5: areal density A of the lid body 2cAnd (4) determining.
The cover body 2 is used for matching with the barrel body to form an initial closed space, so that shock waves in the barrel are prevented from being leaked or diffracted outwards too early, and the momentum extraction energy consumption effect of the explosion-proof equipment can be further improved. Numerical analysis shows that the existence of the cover body can effectively reduce flexible explosion preventionThe overpressure peak value and impulse of air shock wave outside the equipment occur, but the obvious effect caused by the overpressure peak value and impulse appears after the penetration of fragments, so that the surface density A of the cover body is finally determined during the structural designc。
Numerical values and experimental researches show that for a specific barrel body, the larger the surface density of the cover body is, the better the reduction effect of the overpressure peak value and the impulse of the air shock wave outside the flexible explosion-proof equipment is. At the same time, the impulse applied by the flexible rig itself to the surrounding environment (i.e., resulting from the impact of the laterally scattered droplets) rises significantly as more shock wave energy is converted into lateral kinetic energy of the liquid layer of the barrel. Thus, when the cover is present, the surrounding environment, personnel, equipment or buildings are subjected to successively attenuated air shock wave impulses and increased side-to-side spray droplet impulses, the sum of which is the actual side impulse. The results of explosion experiments which we have carried out show that when flexible explosion-proof equipment is used for disposing explosives, the lateral impulse borne by the simulation target vertically placed around the flexible explosion-proof equipment firstly falls and then rises along with the increase of the surface density of the cover body. There will therefore be a critical areal density AccThe minimization of the lateral momentum, which is the design principle of the areal density of the cap, can be achieved. Due to the complex process of driving the liquid by explosion, the liquid drops are broken and scattered, and reasonable results are difficult to be given from a theoretical point of view. Thus, the critical area density A of the cap is determinedccIn the invention, an experiment or numerical simulation method is adopted. Meanwhile, the invention finds that Acc≤0.5AbTherefore, during experimental debugging, A can be determined according to the range screeningcc。
The following is described with reference to a specific example:
example 1
It is now necessary to design a flexible explosion-proof barrel which can safely handle TNT equivalent of 500g containing fragment explosives. The test standard provides an explosive of 500g TNT equivalent, evenly surrounding about 450g of steel balls of 8mm diameter. The inner diameter D of the explosion-proof barrel is required to be not less than 400mm so as to adapt to the explosive wrapped in the small-sized luggage case. Further, it is known that each fragment weighs 1.8g, has a maximum initial velocity of 930m/s and a fly angle of about 20 °, and the fragment having the maximum initial velocity strikes the liquid layer of the barrel wall at a distance of 200mm from the center of the detonation, where the impulse is 9MPa · ms.
S1, the smaller the inner diameter of the barrel body is, the better the explosion-proof effect is, so the inner diameter D of the barrel body is 400 mm.
S2, the height of the barrel body needs to cover the fragments at all heights, so H is:
H＝(400+200)·tan20+150mm＝368mm。
s3. based on the explosion similarity law and the reference result,
Abmin＝60×((500/500)1/3·(368/400)/(400/300)＝41.4kg/m2
in order to reduce the dead weight of the barrel body as much as possible, the density of the liquid layer surface is directly 41.4kg/m2。
S4, calculating the storage speed V when the maximum initial speed is broken and penetrates out of the liquid layer by using a theoretical formula:
S5, based on the principle of minimizing lateral impulse, providing the barrel body with liquid cover bodies with different surface densities, wherein the fiber layer of the barrel body adopts cheap oxford cloth to realize counterweight, and the surface density of the cover bodies is from 10kg/m2Change to 21kg/m2And carrying out an implosion experiment, and representing the lateral impulse size by utilizing the lateral displacement of the vertically placed simulation target. Final experimental estimation of the areal density A of the cap to achieve minimum lateral momentumcminAbout 18kg/m2And the surface density of the cover body is the value.
The flexible explosion-proof barrel designed by utilizing the 5 parameters determined in the steps can effectively intercept all explosion fragments, the safety distance is 3.5m, and the pressure peak value of the shock wave can be reduced to be below 0.03MPa of the human body injury-free standard. The design method disclosed by the invention is reliable in system and has strong implementation.
In summary, 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 (7)
1. A hollow annular flexible explosion-proof structure comprises a hollow barrel body (1) with an opening at one end and a cover body (2), wherein the barrel body (1) comprises a liquid layer (3) and a fiber layer (4) from inside to outside; the explosive barrel is characterized in that the inner diameter of the barrel body (1) is the minimum size capable of accommodating explosives or explosive storage equipment; the height of the barrel body (1) is the minimum height capable of intercepting all fragments; the surface density of the barrel body liquid layer (3) is the minimum surface density for avoiding the outward leakage of the initial shock wave; the surface density of the fiber layer (4) of the barrel body is the minimum surface density for completely capturing the fragments; the surface density of the cover body (2) is the critical surface density which causes the minimum lateral impulse;
wherein the liquid layer density AbComprises the following steps:
Ab＝Abmin,r(me/me,r)1/3(H/Hr)/(D/Dr)
wherein A isbmin,rIs the minimum areal density of a liquid layer of a particular explosive in a particular explosion protection device of the same construction; m ise,rTNT equivalent for a known specific explosive; hrAnd DrRespectively the height and inner diameter of the particular explosion proof device known; m iseThe equivalent weight of explosive TNT to be protected by the explosion-proof structure, H and D are the height and the inner diameter of the explosion-proof structure respectively.
2. The hollow annular flexible explosion-proof structure according to claim 1, wherein the height H of the tub (1) is
H＝(D+2T)·tanθ+150
Wherein D is the inner diameter of the barrel body (1); t is the thickness of the barrel body (1) and is taken as 100 mm; theta is the explosive dispersion angle.
3. The hollow ring-shaped flexible explosion-proof structure of claim 1, wherein the minimum areal density of the liquid layer of the barrel to avoid the leakage of the initial shock wave outward is determined by numerical simulation or experiment.
4. The hollow annular flexible blast protected construction according to claim 1, characterized in that the minimum areal density of fully captured fragments of the barrel fiber layer (4) is determined by ballistic impact testing; in ballistic impact experiments, the fragments are at an initial velocity VbrImpacting a target plate made of the material of the fiber layer,
wherein, V0maxThe maximum initial velocity of the fragment under the drive of the explosive; vb0The average initial speed of the barrel liquid layer under the loading of explosive blast waves is adopted; m isPFor fragment mass, S is the maximum fragment cross-sectional area, CdIs a dimensionless drag coefficient, AbIs the liquid level density.
5. A design method of a hollow annular flexible explosion-proof structure comprises a hollow barrel body (1) with an opening at one end and a cover body (2), wherein the barrel body (1) comprises a liquid layer (3) and a fiber layer (4) from inside to outside, and is characterized by comprising the following steps:
step 1, determining the inner diameter of a barrel body (1): the inner diameter of the barrel body (1) is the minimum size capable of accommodating explosives or explosive storage equipment;
step 2, determining the height of the barrel body (1): the height of the barrel body (1) is the minimum height capable of intercepting all fragments;
step 3, determining the area density of the barrel body liquid layer (3): the surface density of the barrel body liquid layer (3) is the minimum surface density for preventing leakage caused by air gaps at the bottom of the explosion-proof structure due to initial shock waves when an explosive is positioned on the ground for detonation;
the minimum area density for preventing the initial shock wave from leaking at the bottom of the explosion-proof structure when the explosive is positioned on the ground for detonation is determined by numerical simulation or experiments; in the numerical simulation or the experiment, the method,
s1, placing explosives at the center of the bottom of the explosion-proof structure;
s2, gradually increasing the surface density of the barrel liquid layer (3), and finding out the minimum surface density when no pressure leakage exists on the outer side of the bottom of the explosion-proof structure before the initial shock wave is transmitted to the top of the explosion-proof structure through simulation or experiments;
first, the liquid layer density A of a specific explosive in a specific explosion-proof device with the same structure is determined by adopting S1 and S2bmin,r(ii) a Then obtaining the liquid layer density A of the explosion-proof structure according to the following formulab：
Ab＝Abmin,r(me/me,r)1/3(H/Hr)/(D/Dr)
Wherein m ise,rTNT equivalent for a particular explosive; hrAnd DrThe height and the inner diameter of the specific explosion-proof device are respectively; m iseThe equivalent weight of explosive TNT to be protected by the explosion-proof structure, H and D are respectively the height and the inner diameter of the explosion-proof structure;
step 4, determining the surface density of the fiber layer (4) of the barrel body: the surface density of the fiber layer (4) of the barrel body is the minimum surface density of the maximum fragment with the maximum speed penetrating out from the back of the liquid layer determined in the step (3) under the ballistic impact condition;
step 5, determining the surface density of the cover body (2): the surface density of the cover body (2) is the critical surface density which realizes the minimum combined impact of lateral air shock waves and liquid drop flying of the explosion-proof structure.
6. The design method of the hollow annular flexible explosion-proof structure as claimed in claim 5, wherein in the step 2, the minimum height H of the barrel body (1) capable of intercepting all fragments is calculated by the following formulamin：
Hmin＝(D+2T)·tanθ+150
Wherein D is the inner diameter of the barrel body (1) determined in the step 1; t is the thickness of the barrel body (1) and is taken as 100 mm; theta is the explosive dispersion angle.
7. The design method of the hollow annular flexible explosion-proof structure as claimed in claim 5, wherein in the step 4, the minimum area density of the completely captured fragments is determined by ballistic impact test; in the ballistic impact test, the fragments are at an initial velocity VbrImpacting the target plate prepared by the material of the fiber layer, and continuously increasing the surface density of the target plate of the fiber layer to obtain the minimum surface density of the target plate of the fiber layer which is not penetrated by fragments; wherein the content of the first and second substances,
wherein, V0maxThe maximum initial velocity of the fragment under the drive of the explosive; vb0The average initial speed of the barrel liquid layer under the loading of explosive blast waves is adopted; m isPFor fragment mass, S is the maximum fragment cross-sectional area, CdIs a dimensionless drag coefficient, AbIs the liquid level density.
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| CN114963914B (en) * | 2022-04-21 | 2024-01-26 | 靖江荣平警用装备制造有限公司 | Flexible sound-insulation explosion-proof barrel |
| CN115342699A (en) * | 2022-07-08 | 2022-11-15 | 北京理工大学重庆创新中心 | Combined protection structure and design method thereof |
| CN115342700A (en) * | 2022-07-08 | 2022-11-15 | 北京理工大学重庆创新中心 | Design method of non-crushing type explosion-proof structure and non-crushing type explosion-proof structure |
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| CN111174657A (en) | 2020-05-19 |
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