A method for assessing the danger of ammunition

Abstract

The present application relates to a kind of ammunition danger assessment method, belong to the technical field of shell explosive. Including: the reaction intensity expression of constrained charge and its normalized function are constructed;Based on energy method, shell crushing energy, shell kinetic energy, air shock wave overpressure and its corresponding reaction degree are obtained, and terminal state reaction degree is obtained;Based on terminal state reaction degree and reaction time, maximum reaction rate is obtained;Based on terminal state reaction degree and maximum reaction rate, the reaction intensity of constrained charge and its normalized value are obtained;Based on the normalized value of the reaction intensity of constrained charge, the corresponding danger score of constrained charge under different IM accidental stimulation and the total score of danger are obtained.The method obtains the reaction intensity of constrained charge and its normalized value by establishing the reaction intensity expression of constrained charge, and obtains the corresponding danger score under different IM accidental stimulation and the total score of danger based on the normalized value, solves the problem of lacking the method for quantitatively evaluating the danger of ammunition under accidental stimulation.

Description

Technical Field

[0001] This invention relates to the field of projectile explosives technology, and more particularly to a method for assessing the hazard of munitions. Background Technology

[0002] Throughout their lifespan, ammunition is frequently subjected to unexpected stimuli such as drops, impacts, friction, fragmentation, shock waves, heat, and static electricity. These stimuli trigger mechanical-chemical-thermal responses within the ammunition structure, leading to uncontrolled chemical reactions and energy releases. These reactions can cause typical accident reactions, such as ignition, combustion, explosion, or even detonation of the propellant, resulting in severe environmental damage and potentially catastrophic consequences including numerous casualties. Therefore, it is crucial to assess the hazards of loaded ammunition under unexpected stimuli to provide a basis for the selection, storage, protection, emergency response, and damage control measures for insensitive ammunition.

[0003] Currently, the risk assessment of munitions under accidental stimuli usually divides the reaction intensity into several levels. Each reaction intensity level is judged by the degree of shell rupture and fragmentation velocity, shock wave overpressure, witness plate, energetic materials and ground craters, images and sounds, etc., and is comprehensively qualitatively determined by combining expert experience.

[0004] However, existing assessments of the hazards of munitions under unexpected stimuli are mostly subjective descriptions, failing to classify the intensity of munition reactions into graded ranges based on munition reaction intensity mechanism models. This makes it impossible to quantitatively assess the hazards of munitions under unexpected stimuli, severely hindering the development of insensitive munitions.

[0005] Therefore, providing a method for assessing the hazard of munitions is an urgent problem to be solved. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a method for assessing the hazards of ammunition, in order to solve the problem of the current lack of a method for quantitatively assessing the hazards of ammunition under accidental stimuli.

[0007] This invention provides a method for assessing the hazard of ammunition, the method comprising the following steps:

[0008] Construct a reaction intensity expression for a constrained charge, and obtain a reaction intensity normalization function for the constrained charge based on this expression;

[0009] The shell breakage energy, shell kinetic energy, and air shock wave overpressure are obtained based on the energy method, and the corresponding reactivity is obtained based on the shell breakage energy, shell kinetic energy, and air shock wave overpressure, respectively.

[0010] The final state reactivity is obtained based on the reactivity corresponding to the shell breakage energy, shell kinetic energy, and air shock wave overpressure, or based on the reactivity corresponding to the air shock wave overpressure and the IM accident total energy estimation method; the maximum reaction rate is obtained based on the final state reactivity and reaction time; the final state reactivity and maximum reaction rate are substituted into the reaction intensity expression to obtain the reaction intensity of the restrained charge; the reaction intensity of the restrained charge is substituted into the reaction intensity normalization function of the restrained charge to obtain the normalized value of the reaction intensity of the restrained charge;

[0011] Based on the normalized value of the reaction intensity of the restrained charge, the probability factor of the unexpected environmental stimulus, and the explosive weight factor, the hazard score of the restrained charge under different unexpected IM stimuli is obtained, and then the total hazard score of the restrained charge is obtained.

[0012] Furthermore, the normalized function for the reaction intensity of the constrained charge is:

[0013]

[0014] Or:

[0015] F NEW =100+10log(F) new ),

[0016] Among them, F new F represents the reaction intensity of the restrained charge. NEW This represents the normalized value of the reaction intensity of the restrained charge.

[0017] Furthermore, the final reactivity λ and the maximum reaction rate for:

[0018]

[0019] Where, λ c λ represents the reactivity corresponding to the shell breakage energy. v λ represents the degree of reactivity corresponding to the shell's kinetic energy. s w represents the reactivity corresponding to the overpressure of the air shock wave. e E represents the amount of explosive charge reacting in response to an air shock wave. c E represents the shell fracture energy. v Q represents the kinetic energy of the shell. f ρ represents the heat of reaction in an IM accident. 0e V represents the initial density of the charge. 0e t represents the initial volume of the charge. m Indicates reaction time.

[0020] Furthermore, if only shock wave overpressure data is obtained without acquiring the shell fragmentation energy and shell kinetic energy, then the appropriate TNT equivalent ω corresponding to the air shock wave overpressure during the IM accident response is determined based on the shock wave overpressure data, using either the TNT equivalent method, the direct overpressure assessment method, or the shock wave velocity method. be Based on ω be The total reactive amount ω of the charge is obtained, and the final reactive power λ is obtained by the following formula:

[0021] λ=ω / C,

[0022] Where C represents the propellant charge in the ammunition casing.

[0023] Furthermore, the expression for the total hazard score of the constrained charge is:

[0024]

[0025] Among them, F NEWi L represents the normalized response intensity value corresponding to the i-th IM assessment test, where i∈[1,6], L Ei NEW represents the probability factor of unexpected environmental stimuli corresponding to the i-th IM assessment test. w This indicates the weight factor of the explosive.

[0026] Furthermore, the process of obtaining the shell breakage energy, shell kinetic energy, and air shock wave overpressure based on the energy method, and obtaining the corresponding reactivity based on the shell breakage energy, shell kinetic energy, and air shock wave overpressure respectively, includes: obtaining the shell breakage energy through the total breakage energy estimation method or the breakage energy comparison method, and obtaining the reactivity corresponding to the shell breakage energy based on the shell breakage energy;

[0027] The shell kinetic energy is obtained by total kinetic energy measurement estimation, specific kinetic energy comparison, or Grenfell's energy method, and the corresponding reactivity is obtained based on the shell kinetic energy.

[0028] The air shock wave overpressure is obtained by the TNT equivalent method, the direct overpressure assessment method, or the shock wave velocity method, and the corresponding reactivity is obtained based on the air shock wave overpressure.

[0029] Furthermore, the expression for the shell crushing energy obtained through the total crushing energy estimation method is as follows:

[0030] E c =Sγ s ,

[0031] Among them, E c γ represents the shell fragmentation energy, S represents the sum of the fracture surface areas of all fragments, and γ represents the energy of the shell fragmentation. s This represents the surface fracture energy of the shell material;

[0032] The degree of reactivity corresponding to the shell breakage energy is:

[0033]

[0034] Where, λ c ρ represents the degree of reactivity corresponding to the shell breakage energy. 0e V represents the density of explosives. 0e Q represents the volume of the propellant charge. f This indicates the heat of reaction in an IM accident.

[0035] Furthermore, the expression for the shell's kinetic energy, obtained through the total kinetic energy measurement estimation method, is as follows:

[0036]

[0037] Among them, E v The kinetic energy of the shell is represented by γ, the kinetic energy ratio of the shell head is represented by ρ, the density of the shell material is represented by R, the radius of the warhead is represented by h, and the average thickness of the shell is represented by L. i h represents the length of the i-th segment of the warhead. i v represents the average thickness of the i-th segment of the shell. i R represents the shell expansion velocity at the i-th test position. L h represents the end cap radius. L Indicates end cap thickness, v L This indicates the speed at which the tail cap flies out.

[0038] Furthermore, the expression for the overpressure of the air shock wave, obtained through the TNT equivalent method, is as follows:

[0039]

[0040] ΔP m ω represents the overpressure of the air shock wave, r represents the distance from the explosion center, and ω represents the distance from the explosion center. be Indicates loading of explosives

[0041] in,

[0042] The equivalent weight of explosives left to the reaction products after an explosion or deflagration, expressed in atm based on standard atmospheric pressure;

[0043] The reactivity corresponding to the overpressure of the air shock wave is:

[0044] λ s =C R / C,

[0045] Where, λ s Indicates the degree of reactivity corresponding to the overpressure of the air shock wave; C R C represents the mass of the reactant charge in the reaction. R =ω be / β, where β represents the shock wave TNT equivalent coefficient of the ammunition charge formulation; C represents the total mass of the charge.

[0046] Furthermore, the expression for the overpressure of the air shock wave, obtained through the shock wave velocity method, is as follows:

[0047]

[0048] Where P0 represents the initial pressure of the low-pressure section, M represents the Mach number of the shock wave, and C... a The initial speed of sound in the low-pressure section during calibration is represented by , and D represents the air shock wave velocity.

[0049] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0050] 1. This invention obtains the reaction intensity of a restrained charge by establishing a reaction intensity expression, and obtains the corresponding hazard score and the total hazard score of the restrained charge under different IM unexpected stimuli based on the reaction intensity. This solves the problem of lacking a method for quantitatively assessing the hazard of ammunition under unexpected stimuli, and also solves the problem of ranking the hazard of different types of ammunition, providing a basis for the selection of insensitive ammunition.

[0051] 2. This invention establishes a reaction intensity expression for constrained charges, obtains the shell breakage energy, shell kinetic energy, air shock wave overpressure and their corresponding reactivity based on the energy method, and obtains the final state reactivity and maximum reaction rate, thereby obtaining the reaction intensity of constrained charges, and proposes a new reaction intensity expression.

[0052] 3. The reaction intensity normalization function established in this invention normalizes the reaction intensity value to the range of [0, 100], which facilitates the subsequent quantitative evaluation of the reaction intensity level of ammunition.

[0053] 4. Based on different known conditions and test data, this invention provides a variety of methods and expressions for obtaining shell breakage energy, shell kinetic energy, and air shock wave overpressure, which have wider adaptability and practicality.

[0054] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0055] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0056] Figure 1 This is a flowchart of the ammunition hazard assessment method according to an embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram of the projectile shell velocity (PDV) test according to an embodiment of the present invention. Detailed Implementation

[0058] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0059] Example 1:

[0060] One specific embodiment of the present invention discloses a method for assessing the hazard of ammunition. For example... Figure 1 As shown, the method includes the following steps:

[0061] Step S1: Construct the reaction intensity expression for the constrained charge, and obtain the reaction intensity normalization function for the constrained charge based on this reaction intensity expression;

[0062] Step S2: Obtain the shell breakage energy, shell kinetic energy, and air shock wave overpressure based on the energy method; and obtain the corresponding reactivity based on the shell breakage energy, shell kinetic energy, and air shock wave overpressure, respectively.

[0063] Step S3: Obtain the final state reactivity based on the shell breakage energy, shell kinetic energy, and the reactivity corresponding to the air shock wave overpressure, or obtain the final state reactivity based on the reactivity corresponding to the air shock wave overpressure and the IM accident total energy estimation method; obtain the maximum reaction rate based on the final state reactivity and reaction time; substitute the final state reactivity and maximum reaction rate into the reaction intensity expression to obtain the reaction intensity of the confined charge; substitute the reaction intensity of the confined charge into the reaction intensity normalization function of the confined charge to obtain the normalized value of the reaction intensity of the confined charge;

[0064] Step S4: Based on the normalized value of the reaction intensity of the restrained charge, the probability factor of the environmental accidental stimulus, and the explosive weight factor, obtain the hazard score of the restrained charge under different IM accidental stimuli, and then obtain the total hazard score of the restrained charge.

[0065] Specifically, in step S1, the expression for the reaction intensity of the constrained charge is:

[0066]

[0067] Among them, F new Here, E represents the reaction intensity, and E represents the total final energy of the non-detonation (IM accident) munition charge reaction. E represents the maximum power of the non-detonation (IM accident) munition charge reaction. det This represents the total energy at the final state of the detonation.

[0068] Specifically, the ammunition is typically a cylindrical charge structure, and the detonation is initiated from one end. Assuming the explosive density is ρ... 0e The detonation velocity is D, the charge length is L, the charge radius is R, and the heat of explosion is Q. det The volume of the charge is: V 0e =πLR 2 The detonation energy of the ammunition is: E det =ρ 0e V 0e Q det The detonation power is: Assume the heat of reaction (usually the heat of combustion) of the accident reaction is Q. f The final-state reactivity of an IM accident is λ, and the maximum reaction rate of an IM accident is... The reaction energy of the IM accident ammunition is: E = λρ 0e V 0e Q f The energy release rate of the IM accident munition reaction is: According to the above formula, we can obtain:

[0069]

[0070] Substituting equation (2) into equation (1) yields:

[0071]

[0072] Since L / D actually represents the time t required for the ammunition detonation to complete its reaction. det Due to the maximum reaction rate of the ammunition detonation Then equation (3) can be further simplified to:

[0073]

[0074] Furthermore, based on the reaction intensity distribution and function curve characteristics, the reaction intensity is normalized to the [0,100] interval, and the reaction intensity normalization function of the confined charge is finally expressed by the following equation (5) or (6):

[0075]

[0076] F NEW =100+10log(F) new (6)

[0077] Among them, F NEW This represents the normalized value of the reaction intensity of the restrained charge.

[0078] It should be noted that equation (5) or (6) can increase the reaction intensity [F]. NEW Normalized to the [0, 100] interval, after normalization, the detonation time [F]D ] = 100, non-flammable and non-explosive [F NR ] = 0. The coefficients in equation (5) or (6) can also be changed as needed to adjust the reaction intensity [F]. NEW Normalize to other intervals, such as [0,10]. Furthermore, experimental data on the combustion, deflagration, and explosion reaction levels of different ammunition can be obtained through numerous experiments. The reaction intensity corresponding to each experiment can be calculated using the above formula, thereby determining the reaction intensity [F] for the combustion, deflagration, and explosion reaction levels. BUR ]、[F DEF ]、[F BL The range of values ​​that can be taken.

[0079] Specifically, the reaction intensity is calculated in segments according to different accidents:

[0080] (1) For the unresponsive state: λ, If F is equal to 0 or its value is so small as to be negligible, then F new =0.

[0081] (2) For combustion reaction: the average combustion rate under constant pressure (1 atmosphere) in an atmospheric environment can be used as a reference. Calculations, such as measuring the complete combustion time of the ammunition as t. max If λ = 1 at this time, then

[0082]

[0083] (3) For deflagration, explosion, and detonation reactions: These typically generate strong air shock waves, cause a certain degree of shell fragmentation, and result in high shell expansion velocities and fragment velocities. These quantities can usually be measured relatively accurately. The total energy E of the accident charge reaction is converted into energy for external work, including the shell fragmentation energy E0. c kinetic energy of the shell E v Air shock wave energy E s If other forms of energy dissipation are ignored, then

[0084] E = E c +E v +E s ,

[0085]

[0086] The shell breakage energy, kinetic energy, and air shock wave energy can all be characterized by the total energy of the charge reaction and the degree of reactivity.

[0087] Specifically, in step S2, obtaining the shell breakage energy, shell kinetic energy, and air shock wave overpressure based on the energy method, and obtaining the corresponding reactivity based on the shell breakage energy, shell kinetic energy, and air shock wave overpressure respectively includes: obtaining the shell breakage energy through the total breakage energy estimation method or breakage energy comparison method, and obtaining the reactivity corresponding to the shell breakage energy; obtaining the shell kinetic energy through the total kinetic energy measurement estimation method, specific kinetic energy comparison method, or Grenfell's energy method, and obtaining the reactivity corresponding to the shell kinetic energy; obtaining the air shock wave overpressure through the TNT equivalent method, direct overpressure assessment method, or shock wave velocity method, and obtaining the reactivity corresponding to the air shock wave overpressure.

[0088] Specifically, based on different known conditions and test data, the shell breakage energy E is obtained. c There are two methods: total crushing energy estimation method and crushing energy comparison method.

[0089] (1) Total crushing energy estimation method:

[0090] Shell breakage energy E c The crushing energy E can be estimated based on the degree of shell fragmentation, that is, based on the number and size of the shell fragments (the recovered fragments). c .

[0091] Specifically, in the non-detonation reaction process, due to the limited reaction rate, the acceleration on the shell is also limited. Therefore, the shell fragmentation mainly occurs under the action of internal pressure, which is close to hydrostatic pressure, resulting in the deformation of the shell into several large projectile fragments. The shell deformation typically occurs in two stages: the first stage is uniform expansion under internal pressure, and the second stage is the formation of cracks due to localized necking deformation, which then propagate and produce fragments of a certain size. Assuming the shell is a cylindrical structure, the deformation mainly occurs in the circumferential tensile deformation due to acceleration in the diametrical direction perpendicular to the axial direction, leading to fracture and fragmentation. For the non-detonation-driven fracturing process, because the number of fragments is small, i.e., the fracture area S is small, the fracturing energy consumed is relatively small.

[0092] Specifically, to calculate the sum of the fracture surface areas S of the fragments, we first need to obtain the fragment size. Assume the number of recovered fragments is N, and their average width is... Average length is Assuming that the mathematical characteristic values ​​(i.e., width and length) of the recovered fragments can represent the mathematical characteristic values ​​of all fragments, the sum of the fracture surface areas of all fragments can be approximated by the following expression:

[0093]

[0094] in, W i This represents the width of the i-th fragment. Li R represents the length of the i-th fragment, R0 represents the initial radius of the shell, L represents the initial length of the shell, and h represents the average thickness of the shell.

[0095] Furthermore, in the absence of fragment size distribution, based on the simple concept that the shell deformation causes necking, the unloading sound waves propagate laterally from the necking point, and no new cracks are generated where the sound waves reach, the average fragment width can be estimated using the following formula:

[0096]

[0097] Where c0 is the sound velocity of the shell material, u p ε is the final velocity obtained by the shell material. fracture ε k These represent the strain at fracture and the strain at the onset of necking, respectively.

[0098] Specifically, in a low-intensity reaction, the fragment length can be approximately equal to the length of the projectile charge, based on which the sum of the fracture surface areas of all fragments can be calculated:

[0099]

[0100] Then, the total energy of shell fracture, E, is calculated based on the surface fracture energy of the shell material. c :

[0101] E c =Sγ s (10)

[0102] Where, γ s This represents the surface fracture energy of the shell material.

[0103] It should be noted that different shell materials have different surface fracture energies; for example, the surface fracture energy of steel is 5 × 10⁻⁶. 4 J / m 2 .

[0104] Furthermore, based on the shell crushing energy E c =λ c ρ 0e V 0e Q f The reactivity λ corresponding to the shell breakage energy is obtained. c for:

[0105]

[0106] It should be noted that, compared to other forms of energy, the energy of shell fragmentation during combustion and deflagration is relatively small (close to 0) and can usually be ignored.

[0107] (2) Fracture energy comparison method:

[0108] Research results indicate that the fragmentation energy of the ammunition casing during detonation accounts for approximately 3% of the total energy of the explosive detonation, i.e.:

[0109] E cdet =0.03E det ,or,

[0110] λ det =0.03. (12)

[0111] Specifically, using the shell fragmentation energy during detonation as a reference, the shell fragmentation energy of a typical IM accident response satisfies:

[0112]

[0113] When the average width of the casing fragments in the IM accident reaction is known and average length and the average width of fragments during munition detonation and average length At that time, S is obtained using equation (7) to obtain the shell crushing energy:

[0114]

[0115] If the shell fragments from the IM accident are not recovered, the average width of the fragments is estimated using equation (8), and the shell breakage energy is obtained using equation (9):

[0116]

[0117] in, The average width of the shell fragments in the detonation state. The average length of the shell fragments in the detonation state. and It can be obtained through static explosion tests or theoretical calculations.

[0118] Furthermore, based on formula (12), the degree of reactivity corresponding to the shell breakage energy is obtained as follows:

[0119]

[0120] Furthermore, based on different known conditions and test data, the shell kinetic energy E is obtained. v There are three methods: total kinetic energy measurement estimation method, specific kinetic energy comparison method, and Grenfell energy method.

[0121] (1) Total kinetic energy measurement estimation method:

[0122] kinetic energy of the shell E v It can be calculated based on the shell expansion rate at multiple shell locations. For example... Figure 2As shown, based on the actual geometry of the ammunition casing, several PDV velocity probes are arranged along the axial direction of the ammunition casing using PDV velocity measurement technology to obtain the velocity variation distribution of the ammunition casing along its axial direction, thereby providing a basis for calculating the kinetic energy of the ammunition casing under accidents such as deflagration and explosion.

[0123] Specifically, assuming the average warhead casing thickness h, warhead radius R, warhead length L (length of the propellant portion), and casing material density ρ are known, the PDV probe is used to measure the casing expansion velocity at a typical location on the cylindrical section of the ammunition casing. Assume the casing thicknesses corresponding to the n PDV probes are h1, h2, h3…h n h = (h1 + h2 + h) 3+… +h n ) / n, the pressure p inside the shell is the same everywhere, ignore the motion of the shell before it breaks, the shell starts to accelerate when it breaks, the acceleration at each point is only related to the thickness of the shell, and the acceleration time is the same at each point.

[0124] The acceleration at the position of the i-th PDV probe is: a i =p / ρh i ,

[0125] The velocity at the position of the i-th PDV probe is: v i =a i t = pt / ρh i ,

[0126] Based on the position of the PDV probe, the cylindrical section of the ammunition casing is divided into n segments along the axial direction, with an average thickness of h for each segment. i The length of each segment is L i And L=ΣL i Then the volume of each shell segment is:

[0127] V i =2π(R-0.5h)L i h i ,

[0128] Kinetic energy E of the cylindrical section of the ammunition casing vz for:

[0129]

[0130] Assume the velocity of the tail cap of the ammunition casing when it flies out is v. L The end cap radius is R L The end cap thickness is h L The end cap material has a density of ρ L Then the end cap kinetic energy E vL for:

[0131]

[0132] Considering the kinetic energy of the shell's head, the kinetic energy of the shell (i.e., the total kinetic energy of the shell) E v for:

[0133]

[0134] Wherein, γ is the kinetic energy ratio coefficient of the shell head.

[0135] It should be noted that γ is related to the shape of the shell head and is generally 0.05-0.15.

[0136] Furthermore, based on the shell kinetic energy, the degree of reactivity corresponding to the shell kinetic energy is obtained as follows:

[0137]

[0138] Where E is the total energy of the explosive. (17)

[0139] (2) Kinetic energy comparison method:

[0140] Given the known expansion velocity U of the ammunition casing under detonation conditions m Alternatively, assuming an initial velocity of V0 for the ammunition casing fragments, the ratio of the kinetic energy of the ammunition casing or fragments through an IM accident and detonation is e. v / e vdet Determine the kinetic energy E of the IM accident. v .

[0141] It should be noted that the warhead of the ammunition is usually cylindrical. The fragmentation velocity of the cylindrical section of the ammunition casing caused by the explosion represents the maximum power of the ammunition. During the IM test, the expansion velocity of the ammunition casing should also be measured to determine the fragmentation velocity of the cylindrical section of the ammunition casing.

[0142] Assuming the velocity distribution of the ammunition casing during an IM accident is similar to the corresponding velocity distribution during detonation, i.e.

[0143]

[0144] x i For the location of the ammunition casing, U m (x i (x) represents the ammunition casing during an IM incident. i The velocity at that point, U mdet (x i (x) represents the ammunition casing during detonation. i The velocity at point k is a constant, then

[0145]

[0146] Furthermore, if the maximum velocity of the ammunition casing during an IM accident is U m The maximum velocity of the ammunition casing during detonation is U.mdet The specific kinetic energy of the ammunition casing can then be obtained using the following formula:

[0147] The specific kinetic energy of the ammunition casing during detonation is:

[0148] The specific kinetic energy of the ammunition casing during an IM accident is: The kinetic energy of the shell is then obtained by comparing the specific kinetic energy:

[0149]

[0150] Furthermore, based on the shell kinetic energy, the corresponding reactivity is obtained as follows:

[0151]

[0152] It should be noted that the closer an IM accident is to a detonation state, and the higher the reaction intensity, the greater the similarity between the velocity distribution of the ammunition casing and the corresponding velocity distribution during detonation, and the more reliable the method. For deflagration events with relatively low reaction intensity, the lower the intensity, the fewer fragments produced by the ammunition casing, the lower the velocity, and the less kinetic energy accounts for the total released energy in the IM accident; in this case, the error in estimating the casing kinetic energy has a smaller impact on the quantitative calculation results of the IM accident reaction intensity. Therefore, the specific kinetic energy comparison method can meet the accuracy requirements of kinetic energy calculation for IM accidents, and this method has more reasonable requirements for IM experimental measurements, the experimental conditions are easier to meet, and its practicality is higher.

[0153] (3) Grenenen method:

[0154] During IM test evaluation, some munitions cannot undergo static detonation tests, making it impossible to obtain the casing velocity under detonation conditions. In such cases, the empirical Grenfell energy formula for cased charges can be used to calculate the Grenfell energy E. G Then calculate the initial velocity V of the ammunition casing fragments. 0det .

[0155] Specifically, based on the energy conservation principle of the detonation of a cased explosive, the energy balance at the time of ammunition casing rupture leads to the following conclusions:

[0156] E0 = E G +E int (ρ),

[0157] Where E0 is the specific internal energy of the undetonated explosive (i.e., the total energy output by detonation), E G E is the Grenfell energy (i.e., the energy converted into the kinetic energy of the gas and the shell). int (ρ) represents the internal energy per unit mass of the detonation products with density ρ at the instant the ammunition casing expands. This method neglects the energy absorbed by the casing material in the form of strain / heat, as well as the kinetic energy E that the casing expansion imparts to the surrounding atmosphere before the casing ruptures. ε .

[0158] Specifically, assuming the detonation products undergo adiabatic expansion under Chapman-Jouguet pressure and are perfect gases with a constant polynomial coefficient γ, we can obtain:

[0159]

[0160] Where p represents pressure.

[0161] According to the detonation theory, we can conclude that:

[0162] D 2 =2(γ) 2 -1)E0

[0163]

[0164] Where D is burst speed, p CJ ρ CJ Let ρp be the pressure and density of the Chapman-Jouguet state detonation products, respectively, and ρ0 be the density of the unexploded ordnance. Assuming the detonation products are adiabatic, we can obtain:

[0165]

[0166] It should be noted that the Grenfell energy depends on the degree of expansion of the gaseous products. Once the shell ruptures, the gaseous products expand through the fragments, and the fragmentation acceleration process quickly stops. The Grenfell energy also depends on the tensile properties of the shell material, as this will determine the value of ρ / ρ0 at the time of rupture.

[0167] According to Grenen E G The initial velocity V of the ammunition casing fragments during detonation can be calculated using the following formula. 0det .

[0168]

[0169] Where C is the mass of the explosive per unit length, and M is the mass of the cylindrical shell per unit length;

[0170] The kinetic energy of the shell during detonation is E vdet for:

[0171]

[0172] Furthermore, based on the kinetic energy of the shell during detonation, the degree of reactivity corresponding to the kinetic energy of the shell during detonation is obtained as follows:

[0173]

[0174] Among them, Q det The heat of the explosion.

[0175] Similarly, for an IM accident, after measuring the initial velocity V0 of the shell fragments, the expression for the shell's kinetic energy is obtained as follows:

[0176]

[0177] The degree of reactivity corresponding to the shell kinetic energy is:

[0178]

[0179] It should be noted that the initial velocity of the shell fragments is equivalent to the maximum expansion velocity U of the shell. m Therefore, the maximum expansion velocity of the shell can also be obtained, thus yielding the expression for the shell's kinetic energy as follows:

[0180]

[0181] The degree of reactivity corresponding to the shell kinetic energy is:

[0182]

[0183] Furthermore, based on different known conditions and test data, there are three methods to obtain the overpressure of air shock waves: the TNT equivalent method, the direct overpressure assessment method, and the shock wave velocity method.

[0184] (1) TNT equivalent method:

[0185] Specifically, for explosions and deflagrations, the first step is to determine the peak overpressure ΔP of the air shock wave at a distance r from the explosion center. m Calculate the equivalent explosive weight ω of the explosion products after a typical cased explosive explosion. be The pressure of a free-field air shock wave is calculated by the following formula:

[0186]

[0187] Wherein, ΔP m ω represents the overpressure of the air shock wave, r represents the distance from the explosion center, and ω represents the distance from the explosion center. be It indicates the equivalent weight of explosives left as reaction products after the charge explodes or deflagrates (unit: kg), and atm indicates the standard atmospheric pressure.

[0188] Furthermore, based on the shock wave TNT equivalent coefficient β of the ammunition charge formulation, the reaction charge mass C is calculated. R =ω be / β, then the reactivity of the shock wave energy of an IM accident relative to the total energy of the explosive is: λ s =C R / C, where C is the total mass of the charge.

[0189] (2) Direct overpressure assessment method:

[0190] If the propagation law of the air shock wave corresponding to the explosion of the main charge of the ammunition is known as shown in the following formula:

[0191]

[0192] Where A1, A2, and A3 are all coefficients, and w represents the mass of the ammunition charge used to generate the shock wave.

[0193] It should be noted that A1, A2, and A3 can be determined based on the overpressure distribution data of the air shock wave during the airborne static explosion test of the unloaded explosive. In this case, the overpressure peak value ΔP at the IM accident measuring point is used as the reference. m The charge mass C, representing the proportion of air shock wave energy in an IM accident, can be obtained. R Then λ s =C R / C.

[0194] (3) Shock wave velocity method:

[0195] If the peak overpressure of the air shock wave in an IM accident cannot be measured, but the spatiotemporal evolution data of the air shock front (i.e., the relationship between location and time) can be obtained through high-speed photography techniques such as background schlieren high-speed photography, the air shock wave velocity value D(r) at each location in the flow field can be obtained through processing, given the local ambient temperature T and the speed of sound C. a The air shock wave overpressure ΔP m for:

[0196]

[0197] For air, k is usually taken as 1.4, therefore

[0198]

[0199] Where P0 is the initial pressure of the low-pressure section, typically P0 = 0.101325 MPa, M is the Mach number of the shock wave, and C... a The initial speed of sound (m / s) in the low-pressure range, C a =331.6+0.54T, where T is the ambient temperature (°C) and D represents the air shock wave velocity.

[0200] It should be noted that after obtaining the peak overpressure value ΔP of the air shock wave, the TNT equivalent ω of the explosive charge in the accident response can be calculated using the TNT equivalent method. be The reactivity corresponding to the overpressure of the air shock wave.

[0201] Specifically, in step S3, the final reactivity λ and the maximum reaction rate for:

[0202]

[0203]

[0204] Where, λ c λ represents the reactivity corresponding to the shell breakage energy. v λ represents the degree of reactivity corresponding to the shell's kinetic energy. s w represents the reactivity corresponding to the overpressure of the air shock wave. e E represents the amount of explosive charge reacting in response to an air shock wave. c E represents the shell fracture energy. v Q represents the kinetic energy of the shell. f ρ represents the heat of reaction in an IM accident. 0e V represents the initial density of the charge. 0e t represents the initial volume of the charge. m Indicates reaction time.

[0205] Furthermore, if the shell fracture energy and shell kinetic energy cannot be successfully obtained in the IM accident test, and only shock wave overpressure data are available, the following method can be used to approximately estimate the total energy and final-state reactivity of the IM accident response:

[0206] Based on the shock wave overpressure data under the different conditions described above, the TNT equivalent method, the direct overpressure assessment method, or the shock wave velocity method can be selected to determine the TNT equivalent ω of the accident air shock wave energy portion. be For a cylindrical, encased explosive charge, the explosive equivalent of the air shock wave energy from the exploding casing is:

[0207]

[0208] Where ω is the total reaction amount of the charge (kg); ω be α represents the explosive equivalent of the air shock wave (kg); α is the product loading factor, γ = 3; for a steel casing, the radius at which the fragments reach maximum velocity is r. m =1.5r0. Therefore, the final state reaction degree of the IM accident is λ = ω / C, where C is the amount of ammunition.

[0209] In addition, in practical engineering applications, the shock wave overpressure data from the static explosion test of the charged explosive device is typically used to calibrate and obtain the propagation law of the air shock wave of the product:

[0210]

[0211] Among them, coefficients B1, B2, and B3 can be determined based on the overpressure distribution data of the shock wave in an aerial static explosion test with a casing, and w is the total reaction volume of the charge (kg). At this point, based on the overpressure peak value ΔP of the IM accident... m From this, we can obtain the total reaction amount w of the charge in the IM accident. Then, the final state reaction degree of the IM accident is: λ = w / C.

[0212] It should be noted that the above method for calculating reactivity is only applicable to explosive reaction intensity and relatively violent deflagration reaction intensity.

[0213] Furthermore, substituting the final state reactivity and maximum reaction rate into the reaction intensity expression yields the reaction intensity of the constrained charge. Substituting the reaction intensity of the constrained charge into the reaction intensity normalization function yields the normalized value of the reaction intensity of the constrained charge.

[0214] Specifically, in step S4, the insensitivity assessment specifications for ammunition categorize unexpected stimuli encountered by the ammunition into six types: rapid burn (FCO), slow burn (SCO), bullet impact (BI), fragment impact (FI), sympathetic detonation (SD), and jet impact (SCJ). The insensitivity performance of the ammunition is assessed through these six IM (Instantaneous Motion) tests. The reaction intensity of the ammunition represents the degree of harm to the surrounding environment caused by the ammunition's reaction. Through the aforementioned IM tests, normalized values ​​of the reaction intensity of the ammunition under different IM unexpected stimuli are obtained. These values ​​are then combined with the environmental unexpected stimulus probability factor and the explosive weight factor to obtain the corresponding hazard score for the confined charge under different IM unexpected stimuli, thus yielding the overall hazard score for the confined charge.

[0215] Furthermore, the expression for the total hazard score of the constrained charge is:

[0216]

[0217] Among them, F NEWi L represents the normalized response intensity value corresponding to the i-th IM assessment test, where i∈[1,6], L Ei NEW represents the probability factor of unexpected environmental stimuli corresponding to the i-th IM assessment test. w This indicates the weight factor of the explosive.

[0218] Specifically, the types and probabilities of unexpected stimuli faced by ammunition vary under different environments. Therefore, when assessing the hazards of ammunition, the environment in which it is located must be considered, i.e., the types and probabilities of unexpected stimuli faced by the ammunition under typical conditions. In a storage environment, ammunition may encounter fire accidents, causing it to explode or causing adjacent ammunition to detonate. Therefore, the unexpected stimuli faced by ammunition are mainly rapid heating (fire), slow heating (high temperature), and detonation. In a combat environment, ammunition may suffer destructive impacts, facing unexpected stimuli such as bullet impact, fragment impact, and jet streams. It may also generate fire and high-temperature environments, causing the ammunition to explode or causing adjacent ammunition to detonate. The probability factor of environmental unexpected stimuli should be determined based on the characteristics of the confined charge itself and the specific environment.

[0219] For example, the probability factor L of unexpected environmental stimuli corresponding to the shipboard environment.E The reference values ​​are shown in Table 1 below:

[0220] Table 1. Probability Factor L of Unexpected Environmental Stimuli Corresponding to the Shipboard Environment E Reference value

[0221]

[0222] As shown in the table above, the shipboard environment is most likely to experience rapid heating and has a relatively high probability of secondary explosions, while the probability of facing slow heating and jet streams is the lowest.

[0223] Specifically, due to different propellant charges, the degree of harm to the surrounding environment in the event of an IM accident varies. Small-charge munitions pose less of a threat, while large-charge munitions pose a greater threat. The reference values ​​for the explosive weight factor are shown in Table 2 below:

[0224] Table 2 Reference values ​​for explosive weight factors

[0225] [NEWw] 1 5 10 25 100

[0226] It should be noted that the above method can be used to obtain the overall hazard score of various typical confined charges, determine the degree of harm of ammunition accident response to the surrounding platform and environment, and rank the various typical confined charges according to the overall hazard score.

[0227] Compared with existing technologies, the beneficial effects of the ammunition hazard assessment method provided by this invention are as follows:

[0228] 1. This invention obtains the reaction intensity of a restrained charge by establishing a reaction intensity expression, and obtains the corresponding hazard score and the total hazard score of the restrained charge under different IM unexpected stimuli based on the reaction intensity. This solves the problem of lacking a method for quantitatively assessing the hazard of ammunition under unexpected stimuli, and also solves the problem of ranking the hazard of different types of ammunition, providing a basis for the selection of insensitive ammunition.

[0229] 2. This invention establishes a reaction intensity expression for constrained charges, obtains the shell breakage energy, shell kinetic energy, air shock wave overpressure and their corresponding reactivity based on the energy method, and obtains the final state reactivity and maximum reaction rate, thereby obtaining the reaction intensity of constrained charges, and proposes a new reaction intensity expression.

[0230] 3. The reaction intensity normalization function established in this invention normalizes the reaction intensity value to the range of [0, 100], which facilitates the subsequent quantitative evaluation of the reaction intensity level of ammunition.

[0231] 4. Based on different known conditions and test data, this invention provides a variety of methods and expressions for obtaining shell breakage energy, shell kinetic energy, and air shock wave overpressure, which have wider adaptability and practicality.

[0232] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0233] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for assessing the hazard of ammunition, characterized in that, The method includes the following steps: Construct a reaction intensity expression for a constrained charge, and obtain a reaction intensity normalization function for the constrained charge based on this expression; The shell breakage energy, shell kinetic energy, and air shock wave overpressure are obtained based on the energy method, and the corresponding reactivity is obtained based on the shell breakage energy, shell kinetic energy, and air shock wave overpressure, respectively. The final state reactivity is obtained based on the reactivity corresponding to the shell breakage energy, shell kinetic energy, and air shock wave overpressure, or based on the reactivity corresponding to the air shock wave overpressure and the IM accident total energy estimation method; the maximum reaction rate is obtained based on the final state reactivity and reaction time; the final state reactivity and maximum reaction rate are substituted into the reaction intensity expression to obtain the reaction intensity of the restrained charge; the reaction intensity of the restrained charge is substituted into the reaction intensity normalization function of the restrained charge to obtain the normalized value of the reaction intensity of the restrained charge; Based on the normalized value of the reaction intensity of the restrained charge, the probability factor of the environmental accidental stimulus, and the explosive weight factor, the risk score of the restrained charge under different IM accidental stimuli is obtained, and then the total risk score of the restrained charge is obtained. The expression for the reaction intensity is: ， in, Indicates the reaction intensity of the restraint charge. λ Indicates the final state responsiveness to an IM incident. max This indicates the maximum response rate to an IM incident. det This indicates the maximum reaction rate of the ammunition detonation. Q det It indicates extreme heat. Q f The heat of reaction represents the reaction response to an accident.

2. The ammunition hazard assessment method according to claim 1, characterized in that, The normalized function for the reaction intensity of a constrained charge is: ， Or: ， in, Indicates the reaction intensity of the restraint charge. This represents the normalized value of the reaction intensity of the restrained charge.

3. The method for assessing the hazard of ammunition according to claim 1, characterized in that, Final reactivity λ and maximum reaction rate max for: ， ， in, This indicates the degree of reactivity corresponding to the shell breakage energy. This indicates the degree of responsiveness corresponding to the shell's kinetic energy. λ s This indicates the reactivity corresponding to the overpressure of the air shock wave. This indicates the amount of explosive charge reacting in response to the air shock wave. Indicates the energy of shell breakage. Indicates the kinetic energy of the shell. Indicates the heat of reaction in an IM accident. Indicates the initial density of the charge. Indicates the initial volume of the explosive charge. Indicates reaction time.

4. The ammunition hazard assessment method according to claim 1, characterized in that, If only shock wave overpressure data is obtained without acquiring shell breakage energy and shell kinetic energy, then the appropriate TNT equivalent ω corresponding to the air shock wave overpressure during the IM accident response should be determined based on the shock wave overpressure data, using either the TNT equivalent method, the direct overpressure assessment method, or the shock wave velocity method. be Based on ω be Obtain the total reaction amount of the charge ω The final reactivity λ can be obtained using the following formula: λ= ω / C , in, C This refers to the amount of propellant in the ammunition casing.

5. The method for assessing the hazard of ammunition according to claim 1, characterized in that, The expression for the overall hazard score of the constrained charge is: ， in, This represents the normalized value of the reaction intensity corresponding to the i-th IM assessment test. , This represents the probability factor of unexpected environmental stimuli corresponding to the i-th IM assessment test. This indicates the weight factor of the explosive.

6. The method for assessing the hazard of ammunition according to claim 1, characterized in that, The process of obtaining shell breakage energy, shell kinetic energy, and air shock wave overpressure based on the energy method, and obtaining the corresponding reactivity based on shell breakage energy, shell kinetic energy, and air shock wave overpressure respectively, includes: obtaining shell breakage energy through the total breakage energy estimation method or breakage energy comparison method, and obtaining the reactivity corresponding to shell breakage energy based on shell breakage energy. The shell kinetic energy is obtained by total kinetic energy measurement estimation, specific kinetic energy comparison, or Grenfell's energy method, and the corresponding reactivity is obtained based on the shell kinetic energy. The air shock wave overpressure is obtained by the TNT equivalent method, the direct overpressure assessment method, or the shock wave velocity method, and the corresponding reactivity is obtained based on the air shock wave overpressure.

7. The ammunition hazard assessment method according to claim 6, characterized in that, The expression for the shell breakage energy obtained through the total breakage energy estimation method is as follows: ， in, Indicates the energy of shell breakage. This represents the sum of the fracture surface areas of all the fragments. This represents the surface fracture energy of the shell material; The degree of reactivity corresponding to the shell breakage energy is: ， in, This indicates the degree of reactivity corresponding to the shell breakage energy. Indicates the density of the explosive. Indicates the volume of the propellant. This indicates the heat of reaction in an IM accident.

8. The method for assessing the hazard of ammunition according to claim 6, characterized in that, The expression for the shell's kinetic energy, obtained through the total kinetic energy measurement estimation method, is as follows: ， in, Indicates the kinetic energy of the shell. This is the coefficient representing the proportion of kinetic energy at the head of the shell. Indicates the density of the shell material. Indicates the radius of the warhead. This indicates the average thickness of the shell. Indicates the length of the i-th segment of the warhead. This represents the average thickness of the i-th segment of the shell. This represents the shell expansion velocity at the i-th test location. Indicates the end cap radius. Indicates the end cap thickness. This indicates the speed at which the tail cap flies out.

9. The method for assessing the hazard of ammunition according to claim 6, characterized in that, The expression for the overpressure of the air shock wave obtained through the TNT equivalent method is as follows: (atm) , in, Indicates air shock wave overpressure. Indicates the distance from the epicenter. It indicates the equivalent weight of explosives left as reaction products after the explosive charge explodes or deflagrates; atm indicates the pressure based on standard atmospheres. The reactivity corresponding to the overpressure of the air shock wave is: λ s = C R / C， in, λ s This indicates the degree of reactivity corresponding to the overpressure of the air shock wave; C R Indicates the mass of the reactants used in the reaction. C R =ω be / β , β This indicates the TNT equivalent coefficient of the blast wave in the ammunition charge formulation; C This indicates the total mass of the explosive charge.

10. The method for assessing the hazard of ammunition according to claim 9, characterized in that, The expression for the overpressure of an air shock wave obtained through the shock wave velocity method is as follows: ， in, P 0 represents the initial pressure in the low-pressure section. M The Mach number represents the shock wave. C a The initial speed of sound in the low-pressure section during calibration is represented by , and D represents the air shock wave velocity.

Images