Force-thermal coupling test device and test method for friction sensitivity of energetic material

Abstract

The invention discloses a force-heat coupling test device and a test method for friction sensitivity of an energetic material, and belongs to the field of safety evaluation and test of energetic materials. The device comprises a friction sensitivity tester, a thermal coupling system and a pressure control system, a sample loading assembly comprises a sliding column sleeve and a protective sleeve, and the protective sleeve is arranged on the outer side of the sliding column sleeve in a sleeving mode. An upper sliding column and a lower sliding column which are located over the punch are arranged in an inner cavity of the sliding column sleeve, and a charging cavity is reserved between the upper sliding column and the lower sliding column. The upper sliding column and the lower sliding column are detachably arranged in an inner cavity of the sliding column sleeve in a penetrating mode. The friction mechanism comprises a pendulum bob and a pendulum bob support, and an angle is engraved on the pendulum bob support and used for fixing the swing angle of the pendulum bob. The striking rod is fixed to the side end of the upper sliding column in the pressurized state. The thermal coupling system comprises a heating device and a heating coil. An accurate temperature field is applied to the energetic material, stable loading pressure is provided by adjusting the hydraulic pump, the upper sliding column is impacted by the striking rod, so that the lower surface of the upper sliding column rubs with the energetic material, and the friction sensitivity test is carried out.

Description

Technical Field

[0001] This invention belongs to the field of energetic material safety assessment and testing technology, and relates to a force-thermal coupling test device and test method for the friction sensitivity of energetic materials. Background Technology

[0002] Energetic materials (such as explosives, propellants, and propellants) are exposed to extremely complex environments during production, processing, transportation, storage, and combat use. Traditional friction sensitivity testing standards (such as GJB772A-97) are usually conducted at room temperature and pressure, which only characterizes the mechanical sensitivity of materials under standard laboratory conditions.

[0003] However, in practical applications, energetic materials often face the challenge of high-temperature environments. Examples include aerodynamic heating during high-speed missile flight, heat conduction during engine operation, long-term storage of munitions in hot regions, and the high-temperature environment inside weapon launch tubes. Furthermore, energetic materials also experience internal heat accumulation and temperature increases when subjected to continuous mechanical forces. Research shows that temperature is a key factor affecting the chemical reaction rate and activation energy of energetic materials. As temperature increases, the lattice stability of energetic materials decreases, their reactivity increases, and their sensitivity to mechanical stimuli (such as friction) changes significantly (usually increasing sensitivity, i.e., becoming more dangerous).

[0004] Existing friction sensitivity testing devices cannot achieve precise temperature control of drug samples, making it difficult to simulate the true response characteristics of energetic materials under "force-heat" coupled environments. If the safety under high-temperature conditions is assessed solely based on friction sensitivity data at room temperature, the assessment results may be biased towards unsafe conditions, thus creating serious safety hazards.

[0005] Therefore, based on the above background, there is an urgent need to develop a force-thermal coupling test device and method for the friction sensitivity of energetic materials, which can perform friction sensitivity testing while applying a specific temperature field, obtain the friction sensitivity threshold of energetic materials under different temperature conditions, explore the influence of temperature and friction coupling on the ignition mechanism of energetic materials, and provide more accurate and scientific data support for the full life cycle safety assessment of weapons and equipment in complex thermal environments. Summary of the Invention

[0006] To obtain the friction sensitivity of energetic materials under different temperature conditions, the present invention aims to provide a force-thermal coupling test device and test method for the friction sensitivity of energetic materials. A precise temperature field is applied to the energetic material, a stable loading pressure is provided by adjusting the hydraulic pump, and an impact rod is used to impact the upper sliding column to make its lower surface rub against the energetic material, thereby conducting a friction sensitivity test and obtaining the friction sensitivity data of the energetic material at a predetermined test temperature.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A force-thermal coupling testing apparatus for the friction sensitivity of energetic materials includes a friction sensitivity tester, which comprises a sample loading assembly and a friction mechanism. It also includes a thermal coupling system and a pressure control system.

[0009] The sample loading assembly includes a sliding column sleeve and a protective sleeve. The protective sleeve is fitted over the outside of the sliding column sleeve for easy operation and heat insulation. The inner cavity of the sliding column sleeve has an upper sliding column and a lower sliding column located directly above the punch, and a loading cavity is provided between the upper sliding column and the lower sliding column. Both the upper sliding column and the lower sliding column are detachably inserted into the inner cavity of the sliding column sleeve.

[0010] The friction mechanism includes a pendulum and a pendulum support. An angle is engraved on the pendulum support to fix the pendulum's swing angle. A striking rod is fixed to the side end of the upper sliding column under pressure. A punch is located directly below the lower sliding column.

[0011] The thermal coupling system includes a heating device and a heating coil. The heating coil is wound around the outer wall of the sliding sleeve and is encased inside a sheath. The heating device is used to control the temperature of the heating coil. The pressure control system includes a pressure control panel and a regulating hydraulic pump. The regulating hydraulic pump is connected to the loading head of the friction mechanism, and the loading pressure value is set and displayed through the pressure control panel.

[0012] Furthermore, the sheath is made of heat-insulating material, and its inner wall shape matches the sliding sleeve after the coil is wound. The presence of the sheath allows the heated sliding sleeve assembly to be safely removed or replaced, avoiding burns to operators and reducing heat loss to the surrounding environment.

[0013] Furthermore, the heating device is a separate, independent control box, equipped with a temperature display and adjustment knob, and connected to the heating coil located inside the sheath via wires.

[0014] Furthermore, the adjustable hydraulic pump replaces traditional weight loading or manual hydraulic loading, providing higher precision and a larger range of vertical pressure, and achieving digital display and control through a pressure control panel.

[0015] The force-thermal coupling test method for the friction sensitivity of energetic materials disclosed in this invention is based on the aforementioned force-thermal coupling test device for the friction sensitivity of energetic materials. The force-thermal coupling test method for the friction sensitivity of energetic materials includes the following steps:

[0016] Step S1: Weigh the energetic material according to the selected mass and set aside.

[0017] Step S2: The heating coil is pre-wound around the outside of the sliding sleeve and then inserted into the sheath as a whole. This forms the heating assembly.

[0018] Step S3: Install the sliding column into the lower part of the sliding column sleeve. Add the energetic material weighed in step S1 into the sliding column sleeve, so that the energetic material is placed on the upper surface of the sliding column.

[0019] Step S4: Install the upper sliding column on the upper part of the sliding column sleeve so that its lower surface is in contact with the energetic material in the charging chamber.

[0020] Step S5: Connect the heating device, set the target test temperature, heat the sample loading assembly and keep it at that temperature for a certain period of time to ensure that the sample reaches the predetermined temperature.

[0021] Step S6: Turn on the ventilation, place the assembled sample assembly into the friction mechanism, and ensure that the sliding column is directly above the punch.

[0022] Step S7: Set the loading pressure via the pressure control panel, and start the regulating hydraulic pump to apply vertical pressure to the upper slide column. Adjust the loading pressure to the selected value and adjust the pendulum to the selected swing angle.

[0023] Step S8: Release the pendulum impact rod to cause the lower surface of the upper sliding column to rub against the energetic material. Perform a friction sensitivity test and record the results. If the test result indicates an explosion, proceed to step S9. If the test result indicates no explosion, proceed to step S10.

[0024] Step S9: Execute steps S1 to S7, keeping the temperature constant, and lower the loading pressure so that the difference between the pressure of the adjusting hydraulic pump and the previous test pressure is the step pressure. Use a pendulum to impact the striking rod, which in turn impacts the upper sliding column, causing its lower surface to rub against the energetic material. Perform a friction sensitivity test and record the results. If the test result indicates an explosion, proceed to step S11. If the test result indicates no explosion, proceed to step S12.

[0025] Step S10: Execute steps S1 to S7, keeping the temperature constant, and increase the loading pressure so that the difference between the pressure of the adjusting hydraulic pump and the previous test pressure is the step pressure. Use a pendulum to impact the striking rod, which in turn impacts the upper sliding column, causing its lower surface to rub against the energetic material. Perform a friction sensitivity test and record the results. If the test result indicates an explosion, proceed to step S11. If the test result indicates no explosion, proceed to step S12.

[0026] Step S11: Calculate the number of friction sensitivity tests. If the number of friction sensitivity tests is less than N, proceed to step S9. If the number of friction sensitivity tests is equal to N, proceed to step S13.

[0027] Step S12: Calculate the number of friction sensitivity tests. If the number of friction sensitivity tests is less than N, proceed to step S10. If the number of friction sensitivity tests is equal to N, proceed to step S13.

[0028] Step S13: Based on the results of N friction sensitivity tests, use a statistical method for pyrotechnic sensitivity (such as the rise and fall method) to obtain the friction sensitivity threshold (50% ignition critical pressure) at this specific temperature.

[0029] In step S8, the selected loading pressure, selected swing angle, and selected initial temperature can be combined in the following two ways:

[0030] Pair 1: With a fixed loading pressure and adjusted swing angle, measure different 50% ignition critical pressures. Observe the change in explosive friction sensitivity under a fixed loading pressure and the effect of force-thermal coupling.

[0031] Option 2: With a fixed swing angle and adjusted loading pressure, measure different 50% ignition critical pressures. Observe the changes in explosive friction sensitivity under a fixed swing angle and loading pressure under the effect of force-thermal coupling.

[0032] In step S13, based on the results of N friction sensitivity tests, the 50% ignition critical pressure is obtained using the rise and fall method in the statistical method of pyrotechnic sensitivity, as follows:

[0033] When the number of explosions in N friction sensitivity tests is less than or equal to the number of no explosions, the 50% critical ignition pressure is... It is calculated using the following formula (I);

[0034] (I)

[0035] In the formula, The 50% critical ignition pressure is expressed in MPa. d represents the initial pressure, in MPa; d represents the step pressure, in MPa. is the first calculation factor, calculated using formula (II); n is the number of explosions.

[0036] (II)

[0037] In the formula, i is the stimulus index, and the value of i is 0, ±1, ±2, ±3, ...; where the stimulus index 0 is related to the initial pressure. Correspondingly; compared to the initial pressure Large, and related to the initial pressure The difference between id and i corresponds to the test pressure; compared to the initial pressure Small, and with the initial pressure The difference is the test pressure of id, which corresponds to -i; The number of trials in which an explosion occurs when the input pressure is the test pressure of stimulus sequence number i.

[0038] When the number of explosions in N impact sensitivity tests is greater than the number of non-explosions, the 50% ignition pressure is calculated using the following formula (III);

[0039] (III)

[0040] In the formula, The 50% critical ignition pressure is expressed in MPa. d represents the initial pressure, in MPa; d represents the step pressure, in MPa. The second calculation factor is obtained through formula (IV); m is the number of times no explosion occurs;

[0041] (IV)

[0042] In the formula, j is the stimulus index, and the value of j is 0, ±1, ±2, ±3, ...; where the stimulus index 0 is related to the initial pressure. Correspondingly; compared to the initial pressure Large, and related to the initial pressure The difference between j and j corresponds to the test pressure of j; compared to the initial pressure Small, and with the initial pressure The difference is the test pressure of jd, which corresponds to -j; The number of tests in which an explosion does not occur when the input pressure is the test pressure of stimulus sequence number j.

[0043] Beneficial effects:

[0044] 1. The present invention discloses a force-thermal coupling test device and test method for the friction sensitivity of energetic materials. It utilizes a thermal coupling system including a heating coil and a temperature control device to construct a closed temperature control loop, and uses an adjustable hydraulic pump to apply pressure to apply a precise temperature field to the energetic material. The adjustable hydraulic pump provides a stable loading pressure, and the upper sliding column is impacted by an impact rod to cause its lower surface to rub against the energetic material, thereby conducting a friction sensitivity test and obtaining the friction sensitivity data of the energetic material at a predetermined test temperature.

[0045] 2. The force-thermal coupling test device and method for the tribological sensitivity of energetic materials disclosed in this invention employs a high-temperature resistant heat-insulating sleeve whose inner wall shape matches the shape of the sliding cylinder sleeve after the coil is wound, completely encapsulating the heating component. Utilizing the physical isolation and heat insulation properties of the sleeve, and its unique high-temperature resistant heat-insulating sleeve design, modular packaging of the heating component is achieved. The technical advantages are: In test environments up to 290℃, operators can change samples by holding the sleeve without waiting for the device to completely cool down, significantly improving the cycle efficiency of batch testing, while simultaneously protecting the internal heating coil from mechanical impact damage.

[0046] 3. The force-thermal coupling test device and test method for the friction sensitivity of energetic materials disclosed in this invention utilizes an adjustable hydraulic pump with a pressure control panel to replace traditional weights or manual mechanical loading components. By utilizing the pressure holding and fine-tuning functions of the hydraulic system, compared with mechanical thread loading, the adjustable hydraulic pump combined with PID control can effectively compensate for stress changes in energetic materials and metal components during high-temperature expansion or reagent softening. The technical effect is that it ensures the constancy of the vertical normal pressure throughout the friction process and eliminates the interference of thermal expansion on the accuracy of mechanical loading. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the overall structure of the present invention (including the pressure control system);

[0048] Figure 2 yes Figure 1 A schematic diagram of the structure of the sample assembly under loading conditions;

[0049] Figure 3 This is a cross-sectional structural diagram of the sample loading assembly (showing the relationship between the sliding sleeve, coil, and sheath).

[0050] Figure 4 This is a schematic diagram of the sheath;

[0051] Figure 5 Three-dimensional surface plot of the mechanothermal coupling properties of DNAN-based energetic materials;

[0052] In the figure, 1-sample loading assembly, 11-sliding column sleeve, 12-upper sliding column, 13-lower sliding column, 14-charge chamber, 15-sheath, 16-sheath handle, 17-sliding column sleeve placement position, 18-heating wire, 2-friction mechanism, 21-pendulum, 22-pendulum support, 23-strike rod, 24-punch, 3-thermal coupling system, 31-heating device, 32-heating coil, 4-pressure control system, 41-pressure control panel, 42-adjusting hydraulic pump. Detailed Implementation

[0053] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0054] Example 1:

[0055] like Figure 1 As shown, the force-thermal coupling test device for the friction sensitivity of energetic materials disclosed in this embodiment includes a friction sensitivity tester, a thermal coupling system 3, and a pressure control system 4.

[0056] like Figure 2 , Figure 4 As shown, the sample loading assembly 1 includes a sliding sleeve 11. The inner cavity of the sliding sleeve 11 is provided with an upper sliding column 12 and a lower sliding column 13 located on the punch 24, forming a loading cavity 14 between them. Both the upper sliding column 12 and the lower sliding column 13 are made of thermally conductive materials. The core improvement of this embodiment lies in the fact that a heating coil 32 is wound around the outer wall of the sliding sleeve 11, and a protective sleeve 15 is provided on the outer side of the sliding sleeve 11.

[0057] like Figure 4 As shown, 15 is a protective sleeve, designed to enclose the sliding sleeve 11 and heating coil 32 inside. This structural design has two important functions: first, heat insulation, ensuring that heat is mainly transferred to the internal energetic material, rather than being lost to the air or conducted to the friction instrument body; second, easy removal. Since the test is conducted at high temperatures, the sliding sleeve 11 remains very hot after the test. By holding the heat-insulating protective sleeve 15, the operator can easily and safely remove the entire assembly from the instrument for cleaning or to replace the sample for the next test. This addresses a practical operational problem that has not been solved in existing technologies.

[0058] The friction mechanism 2 includes a pendulum 21 and a pendulum support 22. An angle is engraved on the pendulum support 22 to fix the swing angle of the pendulum 21. A striking rod 23 is fixed to the side end of the upper sliding column 12 under pressure. A punch 24 is located directly below the lower sliding column 13.

[0059] The thermal coupling system 3 includes a heating device 31 (shown as an external control box in the figure). The heating device 31 is not a power source, but a dedicated temperature-controlled heating source. It is connected to the heating coil 32 through wires and can precisely control the heating temperature.

[0060] The pressure control system 4 is the power source of this device, including the pressure control panel 41 and adjustable...

[0061] Hydraulic pump 42. Pressure control panel 41 is set on the operating table, and the hydraulic pump 42 is adjusted to provide pressure oil circuit. In the experiment, the user no longer needs to manually move heavy objects or operate a manual jack. He only needs to set the value on the pressure control panel 41 and adjust the hydraulic pump 42 to output a precise vertical load acting on the upper sliding column 12. This is particularly important for studying the force-thermal coupling effect, because hydraulic loading can better maintain the pressure stability after the material softens at high temperature.

[0062] In this embodiment, when assembling the sample assembly 1, the heating coil 32 is evenly and tightly wound around the outer wall of the sliding sleeve 11, and the entire sliding sleeve 11 with the coil wound is embedded into the inner cavity of the sheath 15. The heat transfer efficiency is ensured by the tight fit between the inner wall of the sheath 15 and the coil and the outer wall of the sleeve. The lead wire of the heating coil 32 is led out through the reserved opening in the sheath 15, ready to be connected to the heating device 31.

[0063] Install the lower slide column 13 at the lower part of the slide column sleeve 11; add the weighed energetic material into the pre-reserved charging cavity 14 inside the slide column sleeve 11, so that it contacts the upper surface of the lower slide column 13; install the upper slide column 12 at the upper part of the slide column sleeve 11, so that its lower surface contacts the energetic material in the charging cavity 14. At this time, the slide column sleeve 11, the heating coil 32, the sheath 15 and the upper and lower slide columns constitute a complete heating assembly.

[0064] By designing the structure and selecting materials for the sheath 15 (such as high-temperature resistant insulation materials), thermal isolation between the sliding sleeve 11 and the external operating environment at high temperatures can be achieved, as well as protection of the fragile internal heating coil 32 from direct collision. This allows the entire device to form a stable temperature control circuit consisting of the thermal coupling system 3, the sliding sleeve 11, and the energetic material after heating, thus avoiding high-temperature burns and heat loss.

[0065] Pressure is provided by the regulating hydraulic pump 42 in the pressure control system 4, and the pressure control panel 41 monitors and adjusts it in real time, enabling precise control and maintenance of pressure during the transition from an unloaded state to a loaded state. During this process, the sliding column 13 and the upper sliding column 12 clamp the energetic material under hydraulic pressure. After heating is complete, the presence of the protective sleeve 15 allows operators to easily replace and clean the sample. Without the protective sleeve 15, the sample may not be removed in time due to overheating after the test, or improper operation may damage the heating coil, leading to heating failure.

[0066] During the experiment, the pendulum angle is set by the pendulum support 22, and the pressure control system 4 is activated to adjust to the selected loading pressure. Then, the thermal coupling system 3 applies a preset temperature field around the upper sliding column 12 and the lower sliding column 13, so that the energetic material is subjected to both friction and preset temperature. The pendulum 21 is released to impact the striking rod 23, which in turn impacts the upper sliding column 12, causing the upper sliding column to move in the direction of the force and generate friction with the energetic material in the charge chamber 14. This achieves the force-thermal coupling measurement of this device.

[0067] This embodiment takes into account the operating environment of the test apparatus, featuring a simple structure and small size, allowing for connection with the sample loading assembly. Furthermore, the heating coil 32 can be connected to the heating device 31 to form a closed temperature control loop, effectively adjusting different temperature values. In this test apparatus, the length and power of the heating coil 32 are appropriate, and the sheath 15 is cleverly designed for easy removal. The heating device 31 is a heating controller with PID temperature control function, and its maximum output temperature is 290℃, ensuring the normal operation and safety of the test apparatus. Therefore, this test apparatus can effectively adjust the temperature value experienced by the sample without affecting the friction sensitivity test, while meeting the above conditions.

[0068] The force-thermal coupling test method for the friction sensitivity of energetic materials disclosed in this embodiment is implemented based on the aforementioned force-thermal coupling test device for the friction sensitivity of energetic materials. The specific implementation steps of the force-thermal coupling test method for the friction sensitivity of energetic materials are as follows:

[0069] Step S1: Weigh the energetic material according to the selected mass and set aside;

[0070] Step S2: Tightly wind the heating coil 32 around the outer wall of the sliding sleeve 11, and put it together with the sliding sleeve 11 into the sheath 15. Lead the heating coil 32 through the sheath 15 to ensure the connection of the thermal coupling system.

[0071] Step S3: Install the sliding column 13 at the lower part of the sliding column sleeve 11. When placing the sliding column 13, ensure that its bottom surface is compatible with the bottom surface of the sliding column sleeve 11. Connect the heating coil 32 to the output end of the heating device 31. When placing the sliding column 13, ensure that its position is accurate. In this way, in the following step S4, the energetic material can be evenly spread on the upper surface of the sliding column 13, so that the energetic material sample can be evenly subjected to the combined action of friction and heat.

[0072] Step S4: Add the energetic material weighed in step S1 to the sliding sleeve 11, so that the energetic material is placed on the upper surface of the sliding column 13;

[0073] Step S5: Install the upper sliding column 12 on the upper part of the sliding column sleeve 11, so that its lower surface is in contact with the energetic material in the charging cavity 14;

[0074] Step S6: Turn on the ventilation, place the assembled sample assembly 1 into the friction mechanism 2, and ensure that the sliding column 13 is directly above the punch 24; turn on the heating device 31, set the target test temperature, and wait for the sliding column sleeve 11 and the energetic material to reach the predetermined temperature and keep it warm.

[0075] Through the above steps S1 to S6, the preparation of energetic material loading and heating can be realized, so that a stable thermal conduction environment can be formed between the thermal coupling system 3, the sliding sleeve 11, and the energetic material.

[0076] Step S7: Start the friction mechanism 2 and adjust the pendulum 21 to the selected swing angle; start the pressure control system 4, set the loading pressure through the pressure control panel 41, and operate the regulating hydraulic pump 42 to adjust the pressure to the selected initial pressure; use the pendulum 21 to impact the striking rod 23, and the striking rod 23 impacts the upper sliding column 12 to make its lower surface rub against the energetic material, perform a friction sensitivity test, and record the results; if the test result is an explosion, proceed to step S8; if the test result is no explosion, proceed to step S9.

[0077] An explosion is determined when any of the following phenomena are observed: an explosion sound, light emission, smoke, sample discoloration, or traces of gaseous products on the lower surface of the upper sliding column 12 or the upper surface of the lower sliding column 13 in contact with the energetic material sample. Otherwise, it is considered a non-explosion.

[0078] Step S8: Execute steps S1 to S6, keeping the temperature constant, and lower the loading pressure of the hydraulic pump 42 so that the difference between the loading pressure and the previous test pressure is the step pressure. Use the pendulum 21 to impact the striking rod 23, and the striking rod 23 impacts the upper sliding column 12 to cause its lower surface to rub against the energetic material. Perform a friction sensitivity test and record the results. If the test result is an explosion, proceed to step S10; if the test result is no explosion, proceed to step S11.

[0079] The pressure control system (4) is a hydraulic system with continuously adjustable output pressure, and its maximum output pressure is 5MPa; the initial pressure is 1.5MPa; and the step pressure is 0.1MPa.

[0080] By selecting the loading device as the regulating hydraulic pump (42) and the pressure control panel (41), the pressure of this test method can be set to multiple different preset pressures, and it is easy to adjust.

[0081] Step S9: Execute steps S1 to S6, keeping the temperature constant, and increase the loading pressure of the hydraulic pump 42 so that the difference between the loading pressure and the previous test pressure is the step pressure. Use the pendulum 21 to impact the striking rod 23, and the striking rod 23 impacts the upper sliding column 12 to cause its lower surface to rub against the energetic material. Perform a friction sensitivity test and record the results. If the test result is an explosion, proceed to step S10; if the test result is no explosion, proceed to step S11.

[0082] Step S10: Calculate the number of friction sensitivity tests. If the number of friction sensitivity tests is less than N, proceed to step S8; if the number of friction sensitivity tests is equal to N, proceed to step S12.

[0083] Step S11: Calculate the number of friction sensitivity tests. If the number of friction sensitivity tests is less than N, proceed to step S9; if the number of friction sensitivity tests is equal to N, proceed to step S12.

[0084] Step S12: Based on the results of N friction sensitivity tests, the 50% ignition critical pressure is obtained using the rise and fall method in the statistical method of pyrotechnic sensitivity, as follows:

[0085] When the number of explosions in N friction sensitivity tests is less than or equal to the number of no explosions, the 50% critical ignition pressure is... It is calculated using the following formula (I);

[0086] (I)

[0087] In the formula, The 50% critical ignition pressure is expressed in MPa. d represents the initial pressure, in MPa; d represents the step pressure, in MPa. is the first calculation factor, calculated using formula (II); n is the number of explosions.

[0088] (II)

[0089] In the formula, i is the stimulus index, and the value of i is 0, ±1, ±2, ±3, ...; where the stimulus index 0 is related to the initial pressure. Correspondingly; compared to the initial pressure Large, and related to the initial pressure The difference between id and i corresponds to the test pressure; compared to the initial pressure Small, and with the initial pressure The difference is the test pressure of id, which corresponds to -i; The number of trials in which an explosion occurs when the input pressure is the test pressure of stimulus sequence number i.

[0090] When the number of explosions in N impact sensitivity tests is greater than the number of non-explosions, the 50% ignition pressure is calculated using the following formula (III);

[0091] (III)

[0092] In the formula, The 50% critical ignition pressure is expressed in MPa. d represents the initial pressure, in MPa; d represents the step pressure, in MPa. The second calculation factor is obtained through formula (IV); m is the number of times no explosion occurs;

[0093] (IV)

[0094] In the formula, j is the stimulus index, and the value of j is 0, ±1, ±2, ±3, ...; where the stimulus index 0 is related to the initial pressure. Correspondingly; compared to the initial pressure Large, and related to the initial pressure The difference between j and j corresponds to the test pressure of j; compared to the initial pressure Small, and with the initial pressure The difference is the test pressure of jd, which corresponds to -j; The number of tests in which an explosion does not occur when the input pressure is the test pressure of stimulus sequence number j.

[0095] Example 2:

[0096] The main technical solution in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0097] In step S8, the selected loading pressure, selected swing angle, and selected initial temperature can be combined in the following two ways:

[0098] Pair 1: With a fixed test temperature and an adjusted swing angle, measure different 50% ignition critical pressures; observe the changes in explosive friction sensitivity under the effect of force-thermal coupling at a fixed test temperature as the swing angle changes.

[0099] Using the proportions of energetic materials and the test temperature as quantitative parameters, and the swing angle as a variable, the friction sensitivity test is conducted by selecting an initial swing angle. This allows the determination of the 50% ignition critical pressure of the energetic material at a certain swing angle. By conducting multiple tests at different swing angles with a fixed step size, the 50% ignition critical pressure at different swing angles can be obtained. By comparing the 50% ignition critical pressure at different swing angles, the influence of changes in horizontal force on the friction sensitivity of energetic materials under force-thermal coupling conditions can be obtained, thereby assessing the safety of energetic materials under force-thermal coupling conditions.

[0100] Option 2: With a fixed swing angle and adjusted test temperature, measure different 50% ignition critical pressures; observe the changes in explosive friction sensitivity under the effect of force-thermal coupling, with the test temperature changing as the test temperature changes.

[0101] Using the proportions and swing angle of energetic materials as quantitative parameters and the test temperature as a variable, friction sensitivity testing at the initial test temperature can yield the 50% ignition critical pressure of energetic materials at a certain test temperature. By conducting multiple tests at different test temperatures with a fixed step size, the 50% ignition critical pressure at different test temperatures can be obtained. By comparing the 50% ignition critical pressure at different test temperatures, the influence of changes in the thermal environment on friction sensitivity under force-thermal coupling conditions can be obtained, thereby assessing the safety of energetic materials under force-thermal coupling conditions.

[0102] Example 3:

[0103] The study on the friction sensitivity and phase transition temperature rise characteristics of DNAN-based energetic materials under mechanical-thermal coupling was conducted based on the mechanical-thermal coupling test device and its operation method described in Example 1. Mechanical-thermal coupling tests were performed on the low-melting-point energetic material DNAN (2,4-dinitroanisole) at a predetermined temperature.

[0104] This embodiment establishes a system that includes mechanical load (pressure). The solid and molten temperature rise model of the term quantifies the influence of pressure on heat conduction and phase change processes, and intuitively characterizes the role of the "mechanical-thermal coupling" mechanism in the thermal accumulation effect of energetic materials.

[0105] Experimental materials and pre-set conditions:

[0106] Experimental sample: DNAN (2,4-dinitroanisole), a typical low-melting-point carrier explosive.

[0107] Phase transition characteristics: 94.5°C is set as the critical point for solid-liquid phase transition (melting initiation point).

[0108] Coupling environment: A constant preload static pressure is applied via a pressure control system (4). (simulating the pressure state of the charge), while being heated in a controlled manner through a thermal coupling system (3).

[0109] Mechano-thermal coupling temperature rise model in the solid stage ( )

[0110] At temperatures below 94.5°C, DNAN exists in a solid granular or compacted state. The innovation here lies in the fact that mechanical pressure alters the contact thermal resistance between particles and the tightness of contact between the drug and the sliding sleeve, thereby changing the rate of temperature rise.

[0111] Construct the following pressure-corrected nonlinear temperature rise formula:

[0112]

[0113] in:

[0114] Under constant pressure Sample temperature under action (°C).

[0115] Initial ambient temperature (typically 25°C).

[0116] : Static loading pressure (MPa) applied by the hydraulic pump — a key coupling term.

[0117] : Mechanothermal coupling conductivity ( This coefficient is an innovative parameter measured in this experiment, characterizing the gain effect of pressure on thermal conductivity (the greater the pressure, the smaller the contact thermal resistance, and the faster the temperature rises).

[0118] Pressure sensitivity index (typically 0.5 < m < 1) reflects the nonlinearity of the material compaction process.

[0119] Maximum temperature rise potential parameter.

[0120] Time constant.

[0121] Traditional heating curves are only The formula in this embodiment This indicates that in the force-thermal coupling device, the force field directly participates in the construction of the thermal field, which can more realistically simulate the rapid heat accumulation process of weapon systems under high overload (high pressure) environment.

[0122] Mechanothermal coupling temperature rise model in the melting and liquid stages ( )

[0123] When the temperature reaches and exceeds 94.5°C, DNAN undergoes a phase transition to a liquid state. At this point, under mechanical pressure... Under the constraint of pressure, the thickness of the liquid drug film becomes thinner, and the pressure inhibits the generation of microbubbles, resulting in a change in the thermal convection pattern.

[0124] For this stage, a rheology-thermal coupling temperature rise formula is constructed:

[0125]

[0126] Formula parameter explanation and innovation analysis:

[0127] : The set phase transition reference temperature (°C).

[0128] The time required to reach the phase transition point.

[0129] The heating rate term under pressure control. In the liquid state, high pressure makes the liquid film thinner, shortens the heat conduction path, and causes the temperature rise to exhibit a logarithmic growth characteristic with respect to pressure.

[0130] Liquid thermal diffusion time factor.

[0131] : Viscous dissipation coupling term. This is a highly innovative correction term, taking into account high pressure. Under these conditions, the slight pre-compression creep of the friction mechanism (before the pendulum impact) may generate additional internal viscous heat, which, although small, cannot be ignored in precise mechanical-thermal coupling analysis.

[0132] Analysis of the formula shows that, in the molten state, mechanical pressure is no longer merely a physical constraint, but directly intervenes in the thermodynamic process by changing the medium's morphology (liquid film thickness) and rheological properties. This "direct intervention in the thermodynamic process by changing the medium's morphology (liquid film thickness) and rheological properties" is a phenomenon that cannot be captured by conventional "heating-friction" separation experiments.

[0133] The force-thermal coupling test method for the friction sensitivity of energetic materials disclosed in this embodiment is based on the force-thermal coupling test device for the friction sensitivity of energetic materials described in Embodiment 1. The specific implementation steps of the force-thermal coupling test method for the friction sensitivity of energetic materials are as follows:

[0134] Step S1: Weigh out the DNAN energetic material according to the selected mass and set aside.

[0135] Step S2: The heating coil 32 is wound around the outer wall of the sliding sleeve 11, and the sliding sleeve 11 is installed into the sheath 15 to form a heating assembly.

[0136] Step S3: Install the sliding column 13 onto the lower part of the sliding column sleeve 11; add the DNAN material weighed in step S1 to the sliding column sleeve 11 so that the material is placed on the upper surface of the sliding column 13.

[0137] Step S4: Install the upper sliding column 12 on the upper part of the sliding column sleeve 11, so that its lower surface is in contact with the DNAN in the drug loading cavity 14.

[0138] Step S5: Connect the heating coil 32 to the heating device 31. In this step, turning on the heating device is not simply setting a fixed temperature, but rather based on a preset loading pressure. Based on the aforementioned The model calculates the target heating power curve. The system needs to be monitored in real time, and when the temperature approaches 94.5°C, the change in the heating rate should be recorded to verify the coupling coefficient. .

[0139] Step S6: Turn on the ventilation, place the assembled sample assembly 1 into the friction mechanism 2, and ensure that the sliding column 13 is directly above the punch 24.

[0140] Step S7: Start the pressure control system 4, operate the pressure control panel 41 to control and adjust the hydraulic pump 42, and adjust the loading pressure to the selected initial value. (For example, 3.0 MPa). At this point, the pressure term in the temperature rise formula... It takes effect and enters the force-thermal coupling heating stage.

[0141] Step S8: Select the testing time based on the temperature rise curve:

[0142] Operating condition A (solid-state coupling): In At that time, the friction sensitivity test was conducted by using a pendulum (21) to impact the rod (23).

[0143] Condition B (Melting Coupling): When the monitored temperature exceeds 94.5℃ and meets the requirements... When formula features are used, in At a specific moment (e.g., 105℃), an impact test is performed. Record the results: if the test result is an explosion, proceed to step S9; if it is not an explosion, proceed to step S10.

[0144] Step S9: Execute steps S1 to S7, keeping the target coupling state (solid or liquid temperature point) unchanged, and reduce the loading pressure (step pressure) to perform the test. If an explosion occurs, execute S11; otherwise, execute S12.

[0145] Step S10: Execute steps S1 to S7, keeping the target coupling state unchanged, increase the loading pressure (step pressure), and perform the test. If an explosion occurs, execute S11; otherwise, execute S12.

[0146] Step S11: Calculate the number of friction sensitivity tests. If the number is less than N, proceed to S9; if the number is equal to N, proceed to S13.

[0147] Step S12: Calculate the number of friction sensitivity tests. If the number is less than N, proceed to S10; if the number is equal to N, proceed to S13.

[0148] Step S13: Based on the results of N tests, the friction sensitivity threshold under a specific force-thermal coupling state (e.g., 3MPa, 105℃) is statistically obtained using the rise-fall method, and combined with... and Formulas are used to plot three-dimensional coupled surfaces, such as... Figure 5 .

[0149] By introducing this embodiment and its proprietary mechano-thermal coupling temperature rise formula, this device can not only determine the sensitivity threshold but also quantitatively analyze the corrective effect of mechanical pressure on the thermal response characteristics of energetic materials. Experimental results show that, under the same heating power, the DNAN sample subjected to 5 MPa pressure reaches its melting point in approximately 15% less time than the unpressurized sample, and the risk of thermal runaway after melting (temperature rise rate) increases exponentially with pressure; indicating that "mechano-thermal coupling" is not a simple superposition of operating conditions but rather exhibits a significant mutual reinforcement effect, which is helpful for the safety assessment of this invention in complex environments.

[0150] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is 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 force-thermal coupling test apparatus for the friction sensitivity of energetic materials, comprising a friction sensitivity tester, wherein the friction sensitivity tester comprises a sample loading assembly (1) and a friction mechanism (2); characterized in that: It also includes a thermal coupling system (3) and a pressure control system (4); The sample loading assembly (1) includes a sliding column sleeve (11) and a protective sleeve (15), the protective sleeve (15) being fitted onto the outside of the sliding column sleeve (11); the inner cavity of the sliding column sleeve (11) is provided with an upper sliding column (12) and a lower sliding column (13) located directly above the punch (24), and a loading cavity (14) is provided between the upper sliding column (12) and the lower sliding column (13); the upper sliding column (12) and the lower sliding column (13) are both easily detached and inserted into the inner cavity of the sliding column sleeve (11); The friction mechanism (2) includes a pendulum (21) and a pendulum support (22); the pendulum support (22) is engraved with an angle for fixing the swing angle of the pendulum (21); a striking rod (23) is fixed to the side end of the upper sliding column (12) under pressure; and a punch (24) is located directly below the lower sliding column (13). The thermal coupling system (3) includes a heating device (31) and a heating coil (32); the heating coil (32) is wound around the outer wall of the sliding sleeve (11) and is located between the sliding sleeve (11) and the sheath (15); the heating coil (32) is electrically connected to the heating device (31); The pressure control system (4) includes a pressure control panel (41) and an adjustable hydraulic pump (42). The adjustable hydraulic pump (42) is connected to the loading component of the friction mechanism (2) and controls the loading pressure through the pressure control panel (41).

2. The force-thermal coupling test device for the tribological sensitivity of energetic materials according to claim 1, characterized in that: The sheath (15) is made of high temperature resistant heat insulation material. The inner diameter of the sheath (15) is adapted to the outer diameter of the sliding sleeve (11) on which the heating coil (32) is wound, so that the sliding sleeve (11) together with the heating coil (32) can be inserted into or removed from the sheath (15) as a whole.

3. The force-thermal coupling test device for the tribological sensitivity of energetic materials according to claim 1, characterized in that: The heating device (31) is a heating controller with PID temperature control function, which can set and keep the output temperature constant, and its maximum output temperature is 290°C. A temperature sensor is connected to the heating device (31), and the temperature sensor probe extends to the surface of the sliding sleeve (11) or near the loading chamber (14).

4. The force-thermal coupling test device for the tribological sensitivity of energetic materials according to claim 1, characterized in that: The regulating hydraulic pump (42) provides continuous and adjustable static pressure, and the pressure control panel (41) displays the current loaded pressure value in real time and has pressure holding and pressure fine-tuning functions.

5. The force-thermal coupling test device for the tribological sensitivity of energetic materials according to claim 1, characterized in that: The sliding sleeve (11) is made of a metal material with good thermal conductivity to ensure that the heat from the heating coil (32) can be quickly transferred to the charging chamber (14).

6. A force-thermal coupling test method for the friction sensitivity of energetic materials, implemented based on the force-thermal coupling test apparatus for the friction sensitivity of energetic materials as described in claims 1, 2, 3, 4, or 5; characterized in that: Includes the following steps: Step S1: Weigh the energetic material according to the selected mass and set aside; Step S2: Wind the heating coil (32) around the outer wall of the sliding sleeve (11) and insert the sliding sleeve (11) into the sheath (15) to form a heating assembly; Step S3: Install the sliding column (13) on the lower part of the sliding column sleeve (11); add the energetic material weighed in step S1 to the sliding column sleeve (11) so that the energetic material is placed on the upper surface of the sliding column (13); Step S4: Install the upper sliding column (12) on the upper part of the sliding column sleeve (11) so that its lower surface is in contact with the energetic material in the charging cavity (14); Step S5: Connect the heating coil (32) to the heating device (31), turn on the heating device (31) and set the target test temperature, wait for the sliding sleeve (11) and the energetic material to reach the predetermined temperature and keep it warm; Step S6: Turn on the ventilation and place the assembled sample assembly (1) into the friction mechanism (2), ensuring that the sliding column (13) is directly above the punch (24); Step S7: Start the pressure control system (4), operate the pressure control panel (41) to control the regulating hydraulic pump (42), and adjust the loading pressure to the selected value; Step S8: Adjust the pendulum (21) to the selected swing angle, use the pendulum (21) to impact the striking rod (23), the striking rod (23) impacts the upper sliding column (12) to make its lower surface rub against the energetic material, perform a friction sensitivity test at a specific temperature, and record the results; if the test result is an explosion, proceed to step S9; if the test result is no explosion, proceed to step S10; Step S9: Execute steps S1 to S7, keep the temperature constant, lower the loading pressure so that the difference between the pressure of the hydraulic pump (42) and the previous test pressure is the step pressure, use the pendulum (21) to impact the striking rod (23), the striking rod (23) impacts the upper sliding column (12) so that its lower surface rubs against the energetic material, perform a friction sensitivity test, and record the results; if the test result is an explosion, then execute step S11; if the test result is no explosion, then execute step S12; Step S10: Execute steps S1 to S7, keep the temperature constant, increase the loading pressure so that the difference between the pressure of the hydraulic pump (42) and the previous test pressure is the step pressure, use the pendulum (21) to impact the striking rod (23), the striking rod (23) impacts the upper sliding column (12) so that its lower surface rubs against the energetic material, perform a friction sensitivity test, and record the results; if the test result is an explosion, then execute step S11; if the test result is no explosion, then execute step S12; Step S11: Calculate the number of friction sensitivity tests. If the number of friction sensitivity tests is less than N, proceed to step S9; if the number of friction sensitivity tests is equal to N, proceed to step S13. Step S12: Calculate the number of friction sensitivity tests. If the number of friction sensitivity tests is less than N, proceed to step S10; if the number of friction sensitivity tests is equal to N, proceed to step S13. Step S13: Based on the results of N friction sensitivity tests, the friction sensitivity threshold at the test temperature is obtained using the statistical method of pyrotechnic sensitivity, thus realizing the force-thermal coupling test of the friction sensitivity of energetic materials.

7. In the force-thermal coupling test method for the tribological sensitivity of energetic materials according to claim 6, in step S8, the selected loading pressure, selected swing angle, and selected initial temperature can be combined in the following two ways: Pair 1: With a fixed loading pressure and an adjusted swing angle, measure different 50% ignition critical pressures; observe the changes in explosive friction sensitivity under a fixed loading pressure and the effect of force-thermal coupling. Option 2: With a fixed swing angle and adjusted loading pressure, measure different 50% ignition critical pressures; observe the changes in explosive friction sensitivity under a fixed swing angle and loading pressure under the effect of force-thermal coupling.

8. The method for testing the friction sensitivity of energetic materials by force-thermal coupling according to claim 7, in step S13, based on the results of N friction sensitivity tests, the 50% ignition critical pressure is obtained using the rise and fall method in the statistical method of pyrotechnic sensitivity, as follows: When the number of explosions in N friction sensitivity tests is less than or equal to the number of no explosions, the 50% critical ignition pressure is... It is calculated using the following formula (I); (I) In the formula, The 50% critical ignition pressure is expressed in MPa. d represents the initial pressure, in MPa; d represents the step pressure, in MPa. is the first calculation factor, calculated using formula (II); n is the number of explosions. (II) In the formula, i is the stimulus index, and the value of i is 0, ±1, ±2, ±3, ...; where, Stimulus number 0 and initial pressure Correspondingly; compared to the initial pressure Large, and related to the initial pressure The difference between id and i corresponds to the test pressure; compared to the initial pressure Small, and with respect to the initial pressure The difference is the test pressure of id, which corresponds to -i; The number of trials in which an explosion occurs when the input pressure is the test pressure of stimulus sequence number i. When the number of explosions in N impact sensitivity tests is greater than the number of non-explosions, the 50% ignition pressure is calculated using the following formula (III); (III) In the formula, The 50% critical ignition pressure is expressed in MPa. d represents the initial pressure, in MPa; d represents the step pressure, in MPa. The second calculation factor is obtained through formula (IV); m is the number of times no explosion occurs; (IV) In the formula, j is the stimulus index, and the value of j is 0, ±1, ±2, ±3, ...; where the stimulus index 0 is related to the initial pressure. Correspondingly; compared to the initial pressure Large, and related to the initial pressure The difference between j and j corresponds to the test pressure of j; compared to the initial pressure Small, and with respect to the initial pressure The difference is the test pressure of jd, which corresponds to -j; The number of tests in which an explosion does not occur when the input pressure is the test pressure of stimulus sequence number j.

Images