A test device and method for explosive response under mechanical and thermal composite stimulation

Abstract

The present invention discloses a test device and method for explosive response under combined mechanical and thermal stimulation. The device can be used for recovery in flat plate impact experiments, preventing the influence of secondary damage to the sample on the study of its impact damage characteristics. The device comprises a sample impact system, a testing system, and a recovery system. The sample impact system consists of a flying piece, a sample, and a coated PMMA window. The testing system consists of a PZT probe, a VISAR system, and a PMMA through-hole. The recovery system consists of a steel front end cover, a recovery sleeve, a rear end cover, a limit steel ring, and a pressure spring. The device is used to perform measurement and burnout tests. The measurement test involves driving the flying piece impact test device under a certain vacuum. The PZT probe measures the moment when the shock wave reaches the sample interface. The VISAR system measures the particle velocity history at the interface between the sample and the coated PMMA window, and calculates the sample's sound velocity. The burnout test utilizes a temperature-controlled box to control a heater to heat the entire recovery sleeve, and a temperature-measuring thermocouple to measure the ambient temperature when the mechanically damaged sample responds.

Description

Technical Field

[0001] The invention relates to the technical field of flat plate impact experiments, and in particular to a test device and method for explosive response under mechanical and thermal composite stimulation. Background Art

[0002] With the development of modern military technology, higher requirements are being placed on the safety and explosive damage capability of ammunition. Plate impact testing is one experimental method for obtaining thermodynamic parameters of explosives and verifying their impact damage safety. Cook-off testing is also an important method for examining and evaluating the thermal vulnerability of explosives. The mechanical damage and ignition mechanisms of energetic materials under combined thermal and mechanical stimulation have become key research areas in the field of explosion mechanics.

[0003] Dai Kaida et al. conducted thermal damage experiments on PBX explosives using two thermal loading methods: an oven and an electric heating jacket. The damage was then examined using CT scans. Subsequently, a slow cook-off experiment was conducted to test the thermal sensitivity of explosives with different damage. The temperature, time, and degree of reaction of the damaged explosives were measured, and the effect of thermal damage on the thermal sensitivity of PBX explosives was analyzed. Gallic et al. studied the response of TATB-based PBX explosives to combined thermal and mechanical stimulation. The explosives were first heated at a specific heating rate and then impact-loaded with a flat plate. However, neither of these methods considered the effect of mechanical stimulation on the thermal sensitivity of the explosives.

[0004] Zhou Dong et al. conducted a flat-plate impact experiment on PBX explosives using a first-stage light gas gun. By recovering damaged specimens and performing SEM analysis, they investigated the damage patterns and physical mechanisms of damage evolution. However, they only used high-quality cotton yarn for soft recovery of the explosive samples, failing to effectively address the issue of secondary damage to the samples after impact.

[0005] Existing plate impact tests lack a subsequent recovery device for explosives, failing to effectively prevent secondary damage to explosives after a primary impact. Existing cook-off tests only consider the effect of thermal damage on the explosive's cook-off characteristics. Furthermore, existing plate impact tests only consider the effect of thermal stimulation on mechanical stimulation, ignoring the effect of mechanical stimulation on the explosive's cook-off characteristics.

[0006] Therefore, there is currently a lack of a recovery device that can be used for flat-plate impact experiments. On the one hand, the impact of secondary damage to the sample on its impact damage characteristics should be avoided, and at the same time, a burn test should be carried out directly on it after recovery. Summary of the Invention

[0007] In view of this, the present invention provides a test device and method for the response of explosives under mechanical and thermal composite stimulation, which can be suitable for the recovery of flat plate impact experiments, avoiding the influence of secondary damage to the sample on the study of its impact damage characteristics. At the same time, the device facilitates direct baking test research after recovery.

[0008] To achieve the above-mentioned purpose, the technical solution of the present invention is: a test device considering mechanical and thermal composite stimulation, including a sample impact system, a test system and a recovery system.

[0009] The sample impact system consists of a flyer, samples of different thicknesses and a coated PMMA window.

[0010] The test system consists of a PZT probe, a VISAR system, and a PMMA through-hole.

[0011] The recovery system consists of a steel front end cover, a recovery sleeve, a rear end cover, a limiting steel ring and a pressure spring.

[0012] The front end cover is arranged on a horizontal reference platform, and the sample is fixed at the center of the front end cover; a thermocouple keyway is arranged at the front end cover, in which a thermocouple is fixed, and the thermocouple is glued to the side of the sample.

[0013] The coated end face of the PMMA window is bonded to the sample.

[0014] A PZT probe is fixed beside the sample, and the position of the PZT probe is close to the center of the recovery sleeve.

[0015] A plurality of limiting steel rings are arranged on the inner side of the rear end cover, and a pressure spring is installed between the limiting steel rings and the coated PMMA window.

[0016] The recovery sleeve is fixed between the front end cover and the rear end cover by rotating the thread.

[0017] The entire test device was placed on the flange of the light gas gun target chamber; the VISAR system was arranged so that the laser beam was reflected at the center of the coating on the PMMA window.

[0018] Furthermore, the cooking system is composed of a heater, a temperature control box, a thermal insulation layer, a temperature control thermocouple and a temperature measuring thermocouple.

[0019] The heater is arranged around the recovery sleeve, and the heater is used for heating the recovery sleeve.

[0020] A temperature-control thermocouple is arranged on the heater to control the temperature rise rate of the heater.

[0021] The temperature control box is equipped with a power module, which sets the desired temperature and heating rate, and the power module turns on the heater.

[0022] The temperature measuring thermocouple is fixed on the outer wall of the sample and is used to measure the ambient temperature when the sample responds.

[0023] The insulation layer surrounds the entire test device.

[0024] Preferably, the number of the pressure springs is four.

[0025] Another embodiment of the present invention further provides a test method considering mechanical and thermal composite stimulation, and a test device considering mechanical and thermal composite stimulation to perform measurement tests and cook-off tests;

[0026] The measurement test involves the following steps: When the vacuum level in the test apparatus reaches a certain standard (<200 Pa), a light gas cannon is used to drive a flying disc into the test apparatus. A PZT probe measures the moment when the shock wave reaches the interface of the sample (2-1). A VISAR system measures the particle velocity history at the interface between the sample and the coated PMMA window. The time difference between the signal at the sample interface measured by the PZT probe and the signal recorded by the VISAR system at the sample-coated PMMA window interface can be used to calculate the sample's acoustic velocity.

[0027] The baking test process includes the following steps: setting the expected temperature and heating rate in the temperature control box power module, connecting the circuit, heating the entire recovery sleeve through the heater, and controlling the temperature rise rate of the heater (5-4) using a temperature-controlled thermocouple; and measuring the ambient temperature when the sample responds using a temperature-measuring thermocouple fixed on the outer wall of the sample.

[0028] Beneficial effects:

[0029] 1. The present invention provides a test device for explosive response under mechanical and thermal combined stimulation, and designs a recovery device suitable for flat plate impact experiments to avoid the influence of secondary damage to the sample on the study of its impact damage characteristics. At the same time, the device facilitates direct burn-off test research after recovery.

[0030] 2. The present invention provides a test device for the response of explosives under mechanical and thermal combined stimulation, which can be used to study the response characteristics of explosives under mechanical and thermal combined stimulation. Based on the flat plate impact experiment, the present invention designs a recovery device that is convenient for thermal stimulation. At the same time, the hydraulic spring recovery device designed can effectively avoid the impact of secondary damage caused by the collision between the PBX explosive sample and the rear end cover after it detaches from the front end.

[0031] 3. The present invention provides a test method for the response of explosives under mechanical and thermal combined stimulation. Existing studies mainly consider the shock wave sensitivity of PBX explosives at high temperatures and the influence of thermal damage on the cooking characteristics of explosives. This application adopts a test method of first performing mechanical stimulation and then thermal stimulation, which is of great significance for studying the influence of the mechanical deformation-damage response of explosives after impact on their cooking characteristics response. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of the flat plate impact system of the present invention;

[0033] Figure 2 This is a schematic structural diagram of the cook-off system of the present invention;

[0034] Among them: 1-1 front and rear end covers, 1-2 recovery sleeve, 2-1 sample, 2-2 coated PMMA window, 2-3 thermocouple slot key, 2-4 PZT probe, 3-1 flying piece, 3-2 pressure spring, 3-3 limit steel ring, 4-1 VISAR system, 4-2 PMMA through hole, 5-1 temperature control box, 5-2 temperature control thermocouple, 5-3 insulation layer, 5-4 heater, 5-5 temperature measuring thermocouple. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0036] The present invention provides a test device that takes into account mechanical and thermal composite stimulation, such as Figure 1 and 2 As shown, it includes a flat plate impact test system and a cooking system. The flat plate impact test system mainly includes a sample impact system, a testing system and a recovery system.

[0037] The sample impact system includes a flyer, samples of different thicknesses or other properties, and a coated PMMA window; the flyer is loaded by a light gas gun to impact the steel front end cover; the coated PMMA window is bonded to the back of the sample to form the laser emission surface.

[0038] The test system includes a PZT probe and a laser interferometry VISAR system; the PZT probe is used to measure the time it takes for the shock wave to reach the sample interface; the VISAR system is used to measure the particle velocity history at the interface between the sample and the PMMA window.

[0039] The recovery system includes steel front and rear end covers, a recovery sleeve, a limiting steel ring and a pressure spring; the front and rear end covers are internally processed with internal threads, which is conducive to fixing the recovery sleeve. At the same time, the front and rear end covers are processed into a stepped frustum shape, which is conducive to fixing in the gun chamber and providing a force point for the limiting device; the limiting steel ring is used to prevent the pressure spring from "slipping" due to direct contact with the PMMA window and the rear end cover; the pressure spring is used to unload pressure, absorb energy, and prevent secondary damage to the sample.

[0040] The cook-off system consists of a heater, a temperature control box, an insulation layer, temperature-controlling thermocouples, and temperature-measuring thermocouples. The insulation layer primarily provides insulation to prevent heat dissipation; the temperature control box primarily controls temperature, using the heater to set the temperature-rise rate of the cook-off unit; the temperature-controlling thermocouples control the heater temperature and thus the temperature-rise rate; and the temperature-measuring thermocouples measure temperature. Due to the small size of the sample, they are placed on the outer wall of the specimen and connected to the temperature control system to monitor the actual ambient temperature of the specimen over time.

[0041] like Figure 1 As shown, the sample impact system consists of a flying piece 3-1, samples 2-1 of different thicknesses and a coated PMMA window 2-2; the test system consists of a PZT probe 2-4, a VISAR system 4-1 and a PMMA through-hole 4-2; the recovery system consists of a steel front end cover 1-1, a recovery sleeve 1-2, a rear end cover 1-3, a limit steel ring 3-3 and a pressure spring 3-2; the front end cover 1-1 is set on a horizontal reference platform, and the sample 2-1 is fixed at the center of the front end cover 1-1; a thermocouple keyway 2-3 is set at the front end cover 1-1, in which a thermocouple is fixed, and the thermocouple is glued to the side of the sample 2-1; the coated end face of the coated PMMA window 2-2 is glued to the sample 2-1; P is fixed on the side of the sample 2-1 The ZT probe 2-4 and the PZT probe 2-4 are positioned close to the center of the recovery sleeve 1-2; a plurality of limiting steel rings 3-3 are arranged on the inner side of the rear end cover 1-3, and a pressure spring 3-2 is installed between the limiting steel ring 3-3 and the coated PMMA window 2-2. In the embodiment of the present invention, four pressure springs 3-2 are arranged. In actual implementation, the number of springs can be set according to the actual pressure size, and the multiple springs can be arranged symmetrically around the central axis as much as possible; the recovery sleeve 1-2 is fixed between the front end cover 1-1 and the rear end cover 1-3 by screw thread rotation; the entire test device is placed on the flange of the light gas gun target chamber; the VISAR system 4-1 is arranged so that the laser beam is reflected at the center of the coating of the coated PMMA window 2-2.

[0042] like Figure 2 As shown, the baking system consists of a heater 5-4, a temperature control box 5-1, an insulation layer 5-3, a temperature control thermocouple 5-2 and a temperature measuring thermocouple 5-5; the heater 5-4 is arranged around the recovery sleeve 1-2, and the heater 5-4 is used to heat the recovery sleeve 1-2; the temperature control thermocouple 5-2 is arranged on the heater 5-4, and is used to control the temperature rise rate of the heater 5-4; the temperature control box 5-1 is equipped with a power module, which sets the expected temperature and heating rate, and the power module is connected to the heater 5-4; the temperature measuring thermocouple 5-5 is fixed on the outer wall of the sample, and is used to measure the ambient temperature when the sample responds; the insulation layer 5-3 surrounds the entire periphery of the test device.

[0043] Another embodiment of the present invention further provides a test method considering mechanical and thermal combined stimulation, using the above-mentioned test device considering mechanical and thermal combined stimulation to perform measurement tests and cook-off tests;

[0044] The measurement test includes the following steps:

[0045] When the vacuum degree of the environment in which the test device is located reaches a certain standard <200Pa, the light gas cannon is used to drive the flying piece 3-1 to impact the test device.

[0046] The PZT probe 2-4 measures the moment when the shock wave reaches the interface of the sample 2-1.

[0047] The VISAR system 4-1 measures the particle velocity history at the interface between the sample and the coated PMMA window. The time difference between the signal of the shock wave reaching the sample interface measured by the PZT probe 2-4 and the signal of the shock wave reaching the interface between the sample and the coated PMMA window recorded by the VISAR system 4-1 can be used to calculate the sound velocity of the sample 2-1.

[0048] The baking test process includes the following steps: setting the expected temperature and heating rate in the power module of the temperature control box 5-1, connecting the circuit, heating the entire recovery sleeve through the heater 5-4, and controlling the temperature rise rate of the heater 5-4 using the temperature control thermocouple 5-2; using the temperature measuring thermocouple 5-5 fixed on the outer wall of the sample to measure the ambient temperature when the sample responds.

[0049] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A test device considering mechanical and thermal combined stimulation, characterized in that: Including sample impact system, testing system and recovery system; The sample impact system consists of a flying sheet (3-1), samples of different thicknesses (2-1) and a coated PMMA window (2-2); The test system consists of a PZT probe (2-4), a VISAR system (4-1) and a PMMA through-hole (4-2); The recovery system is composed of a steel front end cover (1-1), a recovery sleeve (1-2), a rear end cover (1-3), a limiting steel ring (3-3) and a pressure spring (3-2); The front end cover (1-1) is arranged on a horizontal reference platform, and the sample (2-1) is fixed at the center of the front end cover (1-1); a thermocouple keyway (2-3) is provided at the front end cover (1-1), in which a thermocouple is fixed, and the thermocouple is adhered to the side of the sample (2-1); The coated end surface of the coated PMMA window (2-2) is bonded to the sample (2-1); A PZT probe (2-4) is fixed beside the sample (2-1), and the position of the PZT probe (2-4) is close to the center of the recovery sleeve (1-2); A plurality of limiting steel rings (3-3) are provided on the inner side of the rear end cover (1-3), and a pressure spring (3-2) is installed between the limiting steel rings (3-3) and the coated PMMA window (2-2); The recovery sleeve (1-2) is fixed between the front end cover (1-1) and the rear end cover (1-3) by rotating the threads; The entire test device is placed on the flange of the light gas gun target chamber; the VISAR system (4-1) is arranged so that the laser beam is reflected at the center of the coating on the PMMA window (2-2); The device also includes a cook-off system, which is composed of a heater (5-4), a temperature control box (5-1), a heat insulation layer (5-3), a temperature control thermocouple (5-2) and a temperature measuring thermocouple (5-5); The heater (5-4) is arranged around the recovery sleeve (1-2), and the heater (5-4) is used to heat the recovery sleeve (1-2); The temperature-controlling thermocouple (5-2) is arranged on the heater (5-4) and is used to control the temperature rise rate of the heater (5-4); The temperature control box (5-1) is provided with a power supply module, the expected temperature and the heating rate are set, and the power supply module is connected to the heater (5-4); The temperature measuring thermocouple (5-5) is fixed on the outer wall of the sample and is used to measure the ambient temperature when the sample responds; The thermal insulation layer (5-3) surrounds the entire periphery of the test device; The test device is used to perform measurement tests and cook-off tests; The measurement test includes the following steps: When the vacuum degree of the environment in which the test device is located reaches a certain standard <200Pa, a light gas cannon is used to drive the flying piece (3-1) to impact the test device; The PZT probe (2-4) measures the moment when the shock wave reaches the interface of the sample (2-1); The VISAR system (4-1) measures the particle velocity history at the interface between the sample and the coated PMMA window; The acoustic velocity of the sample (2-1) can be calculated by measuring the time difference between the signal of the shock wave reaching the sample interface measured by the PZT probe (2-4) and the signal of the shock wave reaching the interface between the sample and the coated PMMA window recorded by the VISAR system (4-1); The cooking test process includes the following steps: setting the expected temperature and heating rate in the power module of the temperature control box (5-1), connecting the circuit, heating the entire recovery sleeve through the heater (5-4), controlling the temperature rise rate of the heater (5-4) using the temperature control thermocouple (5-2); and measuring the ambient temperature when the sample responds using the temperature measuring thermocouple (5-5) fixed on the outer wall of the sample.

2. A test device considering mechanical and thermal combined stimulation as claimed in claim 1, characterized in that: The number of the pressure springs (3-2) is 4.

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