A method for TNT equivalent assessment based on implosion quasi-static pressure

Abstract

This invention discloses a TNT equivalent evaluation method based on implosion quasi-static pressure. It proposes a design method for an implosion test chamber, in which an implosion test is performed on the explosive under test. The TNT equivalent of the explosive is then evaluated based on the measured peak quasi-static pressure, ensuring that the measured quasi-static pressure is approximately equal to the total energy released by the explosion of the explosive. The TNT equivalent obtained from this evaluation is scientifically reasonable, with high testing accuracy and good result stability. Furthermore, the test chamber contains sufficient oxygen to ensure the complete reaction of non-ideal explosives that require oxygen for the reaction. Therefore, this invention is not only applicable to the testing of ideal explosives but also to the testing of non-ideal explosives such as aluminum-containing explosives, thermobaric explosives, and thermobaric charges that require oxygen for the reaction.

Description

Technical Field

[0001] This invention belongs to the field of TNT equivalent assessment technology for explosives, specifically relating to a TNT equivalent assessment method based on implosion quasi-static pressure. Background Technology

[0002] The concept of TNT equivalent originated from nuclear explosions, used to visually reflect the power of nuclear weapons, representing the energy released by the total energy produced by a nuclear weapon explosion equivalent to the energy released by the explosion of a certain mass (in ten thousand tons) of TNT explosive. Subsequently, TNT equivalent was used to assess the power of conventional weapons, forming a widely recognized and accepted definition of explosive TNT equivalent. Existing widely used methods for testing TNT equivalent ratios are mainly divided into direct testing methods and indirect testing methods: the direct testing method calculates the TNT equivalent ratio by measuring the heat of explosion of the tested explosive; this method is the heat-explosive bomb test method. The indirect testing method is based on the explosion similarity law, considering the mass of TNT explosive at which the shock wave parameters produced by the tested explosive are consistent with those of standard TNT explosive as the TNT equivalent of the tested explosive. Commonly used shock wave parameters include peak overpressure and specific impulse.

[0003] The direct testing method has a drawback: the tested explosive must be tested in an oxygen-free environment. While this method is relatively accurate for determining the heat of explosion of ideal explosives based on the exothermic decomposition reaction, it is unsuitable for non-ideal explosives that require oxygen in the air for the reaction (such as aluminum-containing explosives, thermobaric charges, and thermobaric explosives). Oxygen-free conditions can lead to incomplete reactions, resulting in a lower measured heat of explosion than the true value. Therefore, this method is not applicable to non-ideal explosives that require oxygen in the air for the reaction. The indirect testing method requires that the energy output structure of the tested explosive is the same as that of TNT, meaning the shock wave energy is approximately equal to the total energy released in the explosion. The energy released by an explosive detonation in air mainly consists of two parts: first, the large amount of high-temperature gaseous products generated by the explosive detonation pushes the air to form a shock wave, the energy contained in the shock wave is called shock wave energy; second, the diffusion of high-temperature detonation products, with different components reacting with each other and with oxygen in the air, continuously releasing heat, the energy generated is called detonation product energy. Non-ideal explosives, such as aluminum-containing explosives, exhibit an afterburning effect. A significant portion of the explosive's energy is released through subsequent reactions of the detonation products, resulting in a high proportion of energy derived from these products. Consequently, the shock wave energy is no longer approximately equal to the total energy. Therefore, shock wave energy equivalent obtained using shock wave parameter evaluation methods is lower than the total energy equivalent for non-ideal explosives. Furthermore, because shock waves are high-frequency signals, the accuracy and stability of shock wave parameter testing in free fields are poor. Near-field shock wave testing is frequently affected by high temperatures and strong light, leading to data distortion. The TNT equivalent ratio of the explosive calculated using shock wave parameters varies significantly with the proportional distance, resulting in a non-unique TNT equivalent ratio and making it difficult to guarantee the accuracy of the evaluation. Summary of the Invention

[0004] In view of this, the present invention provides a TNT equivalent evaluation method based on implosion quasi-static pressure, which evaluates the TNT equivalent by testing the peak value of the quasi-static pressure generated by the explosion of the explosive under test in a confined environment.

[0005] This invention provides a TNT equivalent assessment method based on implosion quasi-static pressure, comprising the following steps:

[0006] Step 1: Determine the structure, initial internal side length, and initial wall thickness of the implosion test chamber based on the theoretical TNT equivalent of the explosive being tested and the range of the selected pressure sensor. The implosion test chamber is a cube with six walls: a top surface, a bottom surface, and four side walls. A through hole is provided on the top surface as a pressure relief port, and sensor interfaces for connecting low-frequency piezoresistive pressure sensors are provided on the side walls for testing quasi-static pressure. All walls are made of steel of equal thickness, and the walls are connected by welding.

[0007] Step 2: Determine the minimum air volume based on the amount of oxygen required for the complete detonation reaction of the explosive being tested. If the test chamber volume obtained from the initial internal side length is less than the minimum air volume, then the internal side length when the minimum air volume is the test chamber volume shall be used as the final internal side length; otherwise, the initial internal side length shall be used as the final internal side length.

[0008] Step 3: Based on the final internal side length and the initial wall thickness, use the plastic dynamics analysis method to calculate the critical pressure that causes plastic deformation of the wall when the TNT equivalent and detonation distance of the explosive under test are given. Calculate the peak value of the shock wave pressure and the peak value of the quasi-static pressure of the explosive under test. If both the peak value of the shock wave pressure and the peak value of the quasi-static pressure are less than the critical pressure, then use the current initial wall thickness as the final wall thickness and proceed to Step 4; otherwise, increase the initial wall thickness and proceed to Step 3.

[0009] Step 4: Construct an implosion test chamber based on the aforementioned structure, final internal side length, and final wall thickness. Under set operating conditions, conduct implosion tests on standard TNT explosives of different masses within the implosion test chamber. Obtain the quasi-static pressure peak value from the quasi-static pressure-time curve acquired by the pressure sensor. Substitute the obtained quasi-static pressure peak value and the corresponding mass m into the quasi-static pressure peak value p. qs Relationship between TNT equivalent and volume ratio The least squares method is then used to fit the undetermined coefficients a and b, where V is the volume of the implosion test chamber;

[0010] Step 5: Under the set operating conditions, conduct an implosion test on the explosive of mass W, and substitute the quasi-static pressure peak value obtained by the pressure sensor into the quasi-static pressure peak value p determined in step 4. qsThe TNT equivalent m of the tested explosive can be calculated from the TNT equivalent-volume ratio formula, and thus the TNT equivalent ratio of the tested explosive can be obtained.

[0011] Furthermore, the steel material used for the wall surface is Q235 steel.

[0012] Furthermore, the pressure relief port is located at the geometric center of the top surface.

[0013] Furthermore, sensor interfaces are provided on all four side walls, and the sensor interfaces are located at the geometric center of each side wall; the response frequency of the low-frequency piezoresistive pressure sensor is on the order of kilohertz.

[0014] Furthermore, step 3 also includes a secondary verification of the final wall thickness using numerical simulation.

[0015] Furthermore, in step 4, the method of obtaining the quasi-static pressure peak value based on the quasi-static pressure-time curve obtained from the pressure sensor is as follows: the quasi-static pressure peak value is obtained based on the quasi-static pressure-time curves obtained from the four pressure sensors, and after removing unreasonable data, the arithmetic mean of the valid data is taken as the final quasi-static pressure peak value.

[0016] Furthermore, in step 4, when conducting implosion tests on standard TNT explosives of different masses in the implosion test chamber under set working conditions, a detonation sequence is provided for the standard TNT explosives.

[0017] Beneficial effects:

[0018] This invention proposes a design method for an implosion test chamber for measuring the quasi-static pressure generated by explosives exploding in a confined space. The implosion test of the explosive under test is performed within the constructed chamber. The TNT equivalent of the explosive is then evaluated based on the measured peak value of the quasi-static pressure. Quasi-static pressure is a low-amplitude, low-frequency signal with high testing accuracy and good result stability. Therefore, the TNT equivalent ratio of the explosive obtained using this invention is less affected by test conditions, ensuring that the measured quasi-static pressure is approximately equal to the total energy released by the explosion of the explosive under test. The TNT equivalent ratio evaluated accordingly is scientifically reasonable. Furthermore, the test chamber contains sufficient oxygen to ensure the complete reaction of non-ideal explosives that require oxygen for the reaction. Therefore, this invention is applicable not only to ideal explosives but also to non-ideal explosives such as aluminum-containing explosives, thermobaric explosives, and thermobaric charges that require oxygen in the air for the reaction. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating a TNT equivalent assessment method based on implosion quasi-static pressure provided by the present invention.

[0020] Figure 2A schematic diagram of an implosion test chamber for a TNT equivalent evaluation method based on implosion quasi-static pressure provided by the present invention.

[0021] Figure 3 The diagram shows the structure of an implosion test chamber for a TNT equivalent assessment method based on implosion quasi-static pressure provided by this invention.

[0022] Figure 4 This is a schematic diagram of an implosion test chamber and a quarter-scale model of the explosive to be tested, established using a TNT equivalent evaluation method based on implosion quasi-static pressure provided by the present invention.

[0023] Figure 5 The displacement-time curve is obtained by using the TNT equivalent evaluation method based on implosion quasi-static pressure provided by this invention.

[0024] Figure 6 This is a typical quasi-static pressure curve obtained using the TNT equivalent assessment method based on implosion quasi-static pressure provided by the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] This invention provides a TNT equivalent assessment method based on implosion quasi-static pressure, the process of which is as follows: Figure 1 As shown, the specific steps include:

[0027] Step 1: Determine the structure, initial internal side length, and initial wall thickness of the implosion test chamber based on the theoretical TNT equivalent of the explosive to be tested and the range of the selected pressure sensor.

[0028] To suit the characteristics of the test, the implosion test chamber is designed as a cube structure, comprising six walls: a top surface, a bottom surface, and four side walls. Figure 2 As shown, a through hole is opened on the top surface as a pressure relief port and for loading explosives. Sensor interfaces for connecting low-frequency piezoresistive pressure sensors are set on the four side walls for testing quasi-static pressure. All six sides of the implosion test chamber are made of steel of equal thickness and are connected by welding. The ratio of the area of ​​the pressure relief port to the second power of three of the volume of the implosion test chamber is less than 0.0215.

[0029] To further improve welding performance, this invention uses Q235 steel as the material for the six sides of the implosion test chamber. The pressure relief port is located at the geometric center of the top surface, and the sensor interface is located at the geometric center of each side wall. The response frequency of the low-frequency piezoresistive pressure sensor is on the order of kilohertz.

[0030] The range of the measured quasi-static pressure peak value is estimated based on the range of the selected pressure sensor. Then, based on the range of the measured quasi-static pressure peak value and the theoretical TNT equivalent of the explosive being tested, the range of the sealed space volume of the implosion test chamber is calculated using the quasi-static pressure peak value calculation formula. Within the range of the sealed space volume, the internal dimensions of the implosion test chamber are initially selected as the initial internal side length.

[0031] The formula for calculating the quasi-static peak pressure that can be used is as follows:

[0032]

[0033] Where, p qs The quasi-static pressure peak value is expressed in MPa; m is the TNT equivalent of the explosive in kg; and V is the volume of the confined space in m³. 3 .

[0034] For example, if the range of the selected low-frequency piezoresistive pressure sensor is 0MPa to 1MPa, the linearity of the sensor is usually better when the measured pressure peak is 20% to 80% of the upper limit of the range. Therefore, let p in equation (1) qs The range of values ​​for is (0.2MPa, 0.8MPa), therefore the range of values ​​for V is (1.64m). 3 11.87m 3 Meanwhile, according to the applicable range of equation (1), m / V<1, that is, V>m, we can obtain V>1m. 3 In summary, the range of values ​​for the volume V of the enclosed space is (1.64m). 3 11.87m 3 Since the implosion test chamber is a cube, the range of values ​​for the internal side length of the implosion test chamber is (1.18m, 2.28m). Based on this range, the initial internal side length of the implosion test chamber can be preliminarily selected as 1.5m×1.5m×1.5m.

[0035] The energy released by the explosion of explosives within the implosion test chamber is converted into outwardly radiated light and heat energy, as well as the energy contained in the deformation energy of the chamber structure and the pressure load. The light and heat energy typically constitute a small, negligible portion. To ensure that the energy contained in the pressure load is as close as possible to the total energy released by the explosive explosion, the structure and walls of the implosion test chamber must not be damaged or undergo plastic deformation under the implosion load. Since the internal dimensions and materials of the chamber are already determined, the wall thickness is the main factor affecting the deformation of the chamber structure and walls. Therefore, by selecting an appropriate thickness, the chamber can undergo only elastic deformation under the implosion load of the tested explosive. Thus, the wall thickness can be initially selected as the initial wall thickness based on the TNT equivalent of the tested explosive and engineering experience.

[0036] Step 2: Determine the minimum air volume based on the amount of oxygen required for the complete detonation reaction of the explosive being tested. Use the minimum air volume to check the initial internal side length of the implosion test chamber set in Step 1. If the test chamber volume obtained from the initial internal side length determined in Step 1 is less than the minimum air volume, then the minimum air volume is used as the final internal side length of the implosion test chamber set for the test chamber volume; otherwise, the initial internal side length is used as the final internal side length.

[0037] The internal space of the implosion test chamber needs to be large enough to provide sufficient oxygen to ensure the complete detonation reaction of aluminum-containing explosives that require oxygen from the air to participate in the reaction. Therefore, for the reliability of the test, this invention first verifies the internal oxygen content of the implosion test chamber. Specifically, the amount of oxygen required for complete reaction is calculated based on the mass and composition of the explosive being tested. Then, based on the fact that the oxygen content in the air is 21%, the air volume required to provide the corresponding oxygen can be calculated. The internal volume of the implosion test chamber should not be less than this air volume, and the dimensions of the test chamber can be verified accordingly.

[0038] Step 3: Based on the final internal side length and the initial wall thickness, use the plastic dynamics analysis method to calculate the critical pressure that causes plastic deformation of the wall of the implosion test chamber under the given TNT equivalent and detonation distance of the explosive under test. Calculate the peak value of the shock wave pressure and the peak value of the quasi-static pressure of the given explosive under test. If both the peak value of the shock wave pressure and the peak value of the quasi-static pressure are less than the critical pressure, then use the current initial wall thickness as the final wall thickness and proceed to Step 4; otherwise, increase the initial wall thickness and proceed to Step 3.

[0039] Based on the final internal side length and initial wall thickness, assuming each wall of the implosion test chamber is a fixed square plate, the critical pressure that causes plastic deformation of the chamber wall with the initial wall thickness under given TNT equivalent and detonation distance can be theoretically calculated using the plastic dynamics analysis method (Zhu Xi, Ship Structure Damage Mechanics [M], National Defense Industry Press, 2013). The explosion of the explosive (bare charge) in a confined space mainly generates two pressure loads: shock wave and quasi-static pressure. The peak value of the shock wave pressure and the peak value of the quasi-static pressure on the chamber wall can be calculated using theoretical formulas. If both the peak value of the shock wave pressure and the peak value of the quasi-static pressure are less than the critical pressure that causes plastic deformation of the chamber wall, then the implosion test chamber does not undergo plastic deformation, indicating that the dimensions and wall thickness of the implosion test chamber meet the requirements. If the peak value of the shock wave pressure or the peak value of the quasi-static pressure is greater than or equal to the critical pressure, the chamber wall thickness should be increased and the calculation repeated until the peak pressure of the implosion pressure load is lower than the critical pressure. This determines the minimum value of the chamber wall thickness. In addition, since the assumptions in the theoretical calculations are too ideal, it is recommended to use numerical simulation to perform a secondary verification of the strength of the test chamber.

[0040] Since the explosive detonates at the geometric center inside the implosion test chamber, the detonation distance is half the side length inside the test chamber.

[0041] Step 4: Construct the implosion test chamber according to its structure, final internal side length, and final wall thickness. Under the set working conditions, conduct implosion tests on standard TNT explosives of different masses in the implosion test chamber. Obtain the quasi-static pressure-time curve based on the pressure sensor to obtain the quasi-static pressure peak value. Substitute the obtained quasi-static pressure peak value and the corresponding mass into formula (2), and then use the least squares method to fit and obtain the undetermined coefficients a and b, thereby determining the quasi-static pressure peak value p. qs The relationship between TNT equivalent and volume ratio (m / V).

[0042] Wherein, formula (2) is the quasi-static pressure peak value p qs Formula for calculating the relationship between TNT equivalent-volume ratio (m / V):

[0043]

[0044] Where a and b are undetermined coefficients.

[0045] Implosion tests were conducted in a test chamber using at least two different masses of standard TNT explosives. For example, the explosives were spherical or cylindrical with a length-to-diameter ratio of 1:1 and a density of not less than 1.57 g / cm³. 3 To ensure the test chamber meets the aforementioned strength requirements, the maximum mass of the standard TNT explosive shall not exceed the theoretical TNT equivalent of the explosive being tested. The explosive is lowered into the geometric center of the test chamber through the pressure relief vent at the top. Figure 3 As shown, to ensure reliable detonation of explosives, a suitable detonation sequence can be provided, typically by setting a detonator or a detonator and an initiating charge. Quasi-static pressure-time curves are obtained using pressure sensors positioned at the centers of the four side walls of the implosion test chamber. The highest point of the curve is the maximum value, i.e., the quasi-static pressure peak value. Furthermore, for the same operating condition, unreasonable data can be removed, and the arithmetic mean of the valid data can be taken as the final test result.

[0046] Based on the ideal gas law and numerous implosion test results, this invention constructs the quasi-static pressure peak value p as shown in formula (2). qs The relationship with the TNT equivalent-volume ratio (m / V) can be obtained by substituting the quasi-static pressure peak value measured by the implosion test of standard TNT explosives of different masses into formula (2), and then fitting it with the least squares method to obtain the undetermined coefficients a and b.

[0047] Step 5: In the implosion test chamber constructed in Step 4, an implosion test is conducted on the explosive of mass W under the same set conditions. The quasi-static pressure peak value obtained by the pressure sensor is substituted into the quasi-static pressure peak value p determined in Step 4. qs The TNT equivalent m of the tested explosive is calculated from the relationship between TNT equivalent and volume ratio (m / V). The result of dividing m by W is the TNT equivalent ratio of the tested explosive.

[0048] Implosion tests of the explosive under test were conducted in the same implosion test chamber, and the test methods and conditions were exactly the same as those for the aforementioned standard TNT implosion test. For the quasi-static pressure peak values ​​recorded at four measuring points for each test, unreasonable data were removed and the arithmetic mean of the valid data was taken as the final test result.

[0049] The quasi-static pressure peak obtained from the implosion test of the explosive under test is substituted into formula (2) with the coefficients a and b already fitted, and the TNT equivalent m of the explosive under test can be calculated. The actual mass of the explosive under test is W, and the TNT equivalent ratio of the explosive under test can be obtained by dividing m by W.

[0050] Example:

[0051] In this embodiment, a TNT equivalent evaluation method based on implosion quasi-static pressure provided by the present invention is used to evaluate the TNT equivalent of two explosives (explosive 1 is RDX explosive, and explosive 2 is aluminum-containing RDX explosive). The composition, mass, and detonation parameters of the two explosives (calculated using Explo 5 software) are shown in Table 1.

[0052] Table 1. Cases of the two tested explosives

[0053]

[0054] S1, Implosion Test Chamber Design

[0055] The heat of explosion of standard TNT is 4186 J / g. According to Table 1, the theoretical TNT equivalent ratios of explosive 1 and explosive 2 can be calculated to be 1.30 and 1.75, respectively. The TNT equivalents of 40g of the two tested explosives are 52g and 70g, respectively. Therefore, the maximum theoretical TNT equivalent of the tested explosives is 70g.

[0056] The selected pressure sensor is a CY-YZ-010 piezoresistive sensor manufactured by Jiangsu Lianeng Electronic Technology Co., Ltd., with a range of 0–2 MPa, an output voltage of 0–5 V, and a response frequency of 2 kHz. Based on the sensor's range, the internal side length of the test chamber should be greater than 0.49 m and less than 0.94 m. An internal dimension of 0.6 m was selected, and a wall thickness of 16 mm was chosen based on engineering experience. The diameter of the pressure relief port at the top of the test chamber was selected as 70 mm. The ratio of the pressure relief port area to the square root of the test chamber volume was calculated to be 0.011, which is less than 0.0215, thus meeting the requirements.

[0057] S2, Test Chamber Calibration

[0058] S2.1 Internal oxygen content verification

[0059] Explosive 1 is an ideal explosive, exhibiting self-exhaustive energy decomposition and requiring no oxygen from the air for its reaction. Explosive 2 is an aluminum-containing explosive, requiring oxygen from the air for its reaction; therefore, only the oxygen consumption of explosive 2 needs to be calculated. According to calculations, the theoretical oxygen consumption for 40g of explosive 2 is 0.034kg. Assuming an oxygen content of 21% in the air, the required air volume is calculated to be 0.136m³. 3 The test chamber, with internal dimensions of 0.6m square, has a volume of 0.216m³. 3 The volume of oxygen is greater than the required air volume, thus meeting the oxygen demand of the explosive being tested.

[0060] S2.2 Test Chamber Strength Verification

[0061] When the internal side length of the test chamber is 0.6m, the wall thickness is 16mm, and the material is Q235 steel, the critical pressure of the shock wave load that causes plastic deformation of the chamber wall is calculated to be 515.95MPa and the critical pressure of the quasi-static pressure load is 3.74MPa using the plastic dynamics analysis method. For the test explosive with a TNT equivalent of 70g detonated in the test chamber, the maximum shock wave load at the chamber wall is calculated to be 2.07MPa according to the Brode formula for the peak overpressure of the reflected shock wave, which is less than the critical pressure; the peak value of the quasi-static pressure is calculated to be 1.00MPa according to formula (1), which is also less than the critical pressure.

[0062] The strength of the test chamber was further verified using the commercial impact dynamics simulation software AUTODYN. Considering symmetry, a quarter-scale model of the test chamber and the explosive under test was established. Figure 4 As shown in the figure. Observation points were set on the inner surface of the test chamber. Observation points 1 and 2 are located at the geometric center of the outer surface of the wall, 3 and 4 are located at the geometric center of the inner surface of the wall, observation point 5 is located at the two-sided corner, and observation point 6 is located at the three-sided corner. According to the simulation results, the pressure on the chamber is the greatest at the three-sided corner. The displacement-time curve at observation point 6 is extracted as shown in the figure. Figure 5As shown, the maximum displacement is 1.4e-4mm. The strain generated at the location of the maximum displacement is calculated to be 9.33e-8, which is much smaller than the limit strain of elastic deformation of Q235 steel (0.00205). This means that the test chamber did not undergo plastic deformation under the implosion pressure load.

[0063] In summary, both theoretical calculations and numerical simulations show that the strength of the test chamber meets the requirements, and the manufacturing of the implosion test chamber is complete.

[0064] S3. Conduct tests on standard TNT explosives and fit the undetermined coefficients.

[0065] Implosion tests were conducted in a test chamber using standard TNT explosives (cylinders of similar height with an aspect ratio close to 1:1) weighing 30g and 50g, with three explosions for each weight. For each weight, the arithmetic mean of 12 measured quasi-static pressure peaks was taken as the final test result. The tests showed that the quasi-static pressure peaks generated by the explosion of 30g and 50g standard TNT explosives in the test chamber were 0.588MPa and 0.832MPa, respectively.

[0066] Substituting the peak static pressure of the implosion of each mass of standard TNT explosive into equation (2), the undetermined coefficients a and b were obtained by least squares fitting, which were 2.25 and 0.68, respectively.

[0067] S4. Conduct an implosion test on the explosive being tested and calculate its TNT equivalent ratio.

[0068] Implosion tests of explosives 1 and 2 were conducted in the same test chamber. Three charge fragments of each explosive were prepared, and a total of six implosion tests were performed. The typical quasi-static pressure curves of explosives 1 and aluminum-containing explosive 2 were obtained as follows: Figure 6 As shown. For the data measured in the experiment, the method of deleting unreasonable data and taking the average of the valid data was used to statistically analyze the data. The quasi-static pressure peak values ​​of explosive 1 and explosive 2 were found to be 0.83 MPa and 1.01 MPa, respectively. These were then substituted into the formula (2) with known undetermined coefficients as input: p qs = 2.25 (m / V) 0.68 The TNT equivalent m of the two explosives were calculated to be 53.6g and 70.8g respectively. The TNT equivalent m of each explosive was divided by the actual mass W (W is 40g) to obtain the TNT equivalent ratio of explosive 1 and explosive 2 as 1.34 and 1.77 respectively.

[0069] The theoretical TNT equivalent ratio of explosive 1 and explosive 2, the TNT equivalent ratio obtained from quasi-static pressure, and their relative deviation are shown in Table 2. As can be seen from Table 2, the method proposed in this invention for evaluating TNT equivalent through quasi-static pressure peak value can accurately assess the TNT equivalent ratio of explosives, whether for ideal explosives or aluminum-containing explosives.

[0070] Table 2. TNT equivalent ratio of explosive 1 and explosive 2

[0071]

[0072] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the equivalent TNT based on implosion quasi-static pressure, characterized in that, Includes the following steps: Step 1: Determine the structure, initial internal side length, and initial wall thickness of the implosion test chamber based on the theoretical TNT equivalent of the explosive being tested and the range of the selected pressure sensor. The implosion test chamber is a cube with six walls: a top surface, a bottom surface, and four side walls. A through hole is provided on the top surface as a pressure relief port, and sensor interfaces for connecting low-frequency piezoresistive pressure sensors are provided on the side walls for testing quasi-static pressure. All walls are made of steel of equal thickness, and the walls are connected by welding. Step 2: Determine the minimum air volume based on the amount of oxygen required for the complete detonation reaction of the explosive being tested. If the test chamber volume obtained from the initial internal side length is less than the minimum air volume, then the internal side length when the minimum air volume is the test chamber volume shall be used as the final internal side length; otherwise, the initial internal side length shall be used as the final internal side length. Step 3: Based on the final internal side length and the initial wall thickness, use the plastic dynamics analysis method to calculate the critical pressure that causes plastic deformation of the wall when the TNT equivalent and detonation distance of the explosive under test are given. Calculate the peak value of the shock wave pressure and the peak value of the quasi-static pressure of the explosive under test. If both the peak value of the shock wave pressure and the peak value of the quasi-static pressure are less than the critical pressure, then use the current initial wall thickness as the final wall thickness and proceed to Step 4; otherwise, increase the initial wall thickness and proceed to Step 3. Step 4: Construct an implosion test chamber based on the aforementioned structure, final internal side length, and final wall thickness. Under set operating conditions, conduct implosion tests on standard TNT explosives of different masses within the implosion test chamber. Obtain the quasi-static pressure peak value from the quasi-static pressure-time curve acquired by the pressure sensor. Substitute the obtained quasi-static pressure peak value and the corresponding mass m into the quasi-static pressure peak value p. qs Relationship between TNT equivalent and volume ratio The least squares method is then used to fit the undetermined coefficients a and b, where V is the volume of the implosion test chamber; Step 5: Under the set operating conditions, conduct an implosion test on the explosive of mass W, and substitute the quasi-static pressure peak value obtained by the pressure sensor into the quasi-static pressure peak value p determined in step 4. qs The TNT equivalent m of the tested explosive can be calculated from the TNT equivalent-volume ratio formula, and thus the TNT equivalent ratio of the tested explosive can be obtained.

2. The TNT equivalent assessment method according to claim 1, characterized in that, The wall surface is made of Q235 steel.

3. The TNT equivalent assessment method according to claim 1, characterized in that, The pressure relief port is located at the geometric center of the top surface.

4. The TNT equivalent assessment method according to claim 1, characterized in that, Sensor interfaces are provided on all four side walls, and the sensor interfaces are located at the geometric center of each side wall; the response frequency of the low-frequency piezoresistive pressure sensor is on the order of kilohertz.

5. The TNT equivalent assessment method according to claim 1, characterized in that, Step 3 also includes using numerical simulation to perform a secondary verification of the final wall thickness.

6. The TNT equivalent assessment method according to claim 4, characterized in that, The method for obtaining the quasi-static pressure peak value based on the quasi-static pressure-time curve obtained from the pressure sensor in step 4 is as follows: the quasi-static pressure peak value is obtained based on the quasi-static pressure-time curves obtained from the four pressure sensors, and after removing unreasonable data, the arithmetic mean of the valid data is taken as the final quasi-static pressure peak value.

7. The TNT equivalent assessment method according to claim 1, characterized in that, In step 4, when conducting implosion tests on standard TNT explosives of different masses in the implosion test chamber under set working conditions, a detonation sequence is provided for the standard TNT explosives.

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