A device for observing the evolution of laser ignition reactions in energetic materials.

Abstract

This invention relates to an observation device for the evolution of laser ignition reactions in energetic materials. The device comprises an upper metal cylinder, a lower metal cylinder, a first camera, a second camera, a first reflector, a second reflector, a laser igniter, and a hydraulic press. The upper metal cylinder has a first observation window and a first laser illumination window on its surface. The first reflector is located inside the first observation window, and the first camera is located outside the first observation window. A first transparent window is located at the bottom of the upper metal cylinder. The lower metal cylinder is identical to the upper metal cylinder. An experimental sample is placed between the first and second transparent windows. A hydraulic press is located below the lower metal cylinder. The laser igniter ignites the experimental sample outside the first and second laser illumination windows. This invention offers a simple experimental process, can acquire a large amount of ignition process data, and fully utilizes multi-factor coupling analysis to understand the hotspot propagation mechanism.

Description

Technical Field

[0001] This invention relates to the field of observation device design for the evolution of photoignition reaction, and in particular to an observation device for the evolution of laser ignition reaction in energetic materials. Background Technology

[0002] In the analysis of the safety of energetic materials, people generally only focus on whether they "explode" or "do not explode," but ignore the process of hotspot generation and propagation. This inertia of thinking hinders our exploration and research on the safety mechanism.

[0003] The currently accepted theory for the ignition process is the transport theory: external stimuli, including impacts, sparks, friction, boundary heat, or shocks, raise the temperature of the local or overall explosive material to a critical point, thereby generating gaseous products and developing into a self-sustaining reaction. The process leading to the self-sustaining reaction is usually called the pre-ignition stage, while the state after the self-sustaining reaction is called the post-ignition stage. Different types and proportions of energetic materials respond differently to stimuli. Similarly, due to their own material properties and the influence of external structural factors, the "ability" of hotspot propagation also varies. Therefore, these two stages should be studied separately.

[0004] Energetic materials, as core components of warhead explosives, can ignite under unexpected stimuli. After ignition, the explosive undergoes conductive combustion, which can even further develop into convective combustion. A review of relevant domestic and international research indicates that crack propagation, matrix fracture, and fragmentation are key mechanisms leading to further escalation of the reaction intensity. However, they can also be significant factors inhibiting reaction propagation or even causing failure. Therefore, studying the mechanisms influencing crack propagation is crucial for understanding the after-effects of ignition.

[0005] Current research on the reaction growth of energetic materials after ignition mainly relies on experiments. Previous researchers have designed many experimental devices and continuously improved experimental methods to explore the evolution mechanism of combustion reaction after ignition.

[0006] Dickson et al. designed a visual constrained combustion experiment to observe the evolution of the combustion reaction after ignition inside a dense explosive. They discovered the relationship between the combustion reaction and crack damage in the explosive using a high-speed camera and proposed that crack damage provides a pathway for the combustion reaction, thereby promoting the reaction to extend to the entire sample.

[0007] Shang Hailin and colleagues at the China Academy of Engineering Physics designed a gap pressurization experiment for convective combustion. They installed two long, thin strips of explosive within a confined enclosure, creating a gap of a certain length and width between the two strips. One end of the gap was closed, while the other end communicated with the ignition chamber. A transparent window was placed at one end of the gap, allowing real-time observation of the combustion reaction within the gap. A pressure sensor was installed on the other side of the gap to record the pressure during the combustion process.

[0008] Wang Shuo, Lu Fangyun, and others from the National University of Defense Technology designed an experiment on the evolution of the intensity of the central ignition reaction of explosives. This experiment uses a sealed space formed by upper and lower end caps, a tempered glass base, a window, gaskets, and a metal ring to confine the explosive fragments. A DC power supply is used to heat a heating wire, thereby igniting the explosive near the heating wire. The experiment uses three different confinement rings to set variables.

[0009] Current experimental setups for observing the aftereffects of hotspot formation in energetic materials suffer from several drawbacks. These setups are complex to operate and provide insufficient quantitative data on the ignition process. They rely primarily on subjective observation of the aftereffects using high-speed cameras, lacking quantitative data to validate conclusions. Furthermore, these setups lack a standardized system; researchers design or improve them only for their specific research areas, resulting in limited overall improvement plans and a limited number of controllable variables for each device. Consequently, they fail to adequately analyze the mechanisms of hotspot propagation through multi-factor coupling. Summary of the Invention

[0010] The purpose of this invention is to provide an observation device for the evolution of laser ignition reaction in energetic materials. The experimental process is simple to operate, and it can acquire a large amount of quantitative data on the ignition process, enabling full multi-factor coupling analysis of the hotspot propagation mechanism.

[0011] To achieve the above objectives, the present invention provides the following solution:

[0012] An observation device for the evolution effect of laser ignition reaction in energetic materials includes an upper metal cylinder, a lower metal cylinder, a first camera, a second camera, a first reflector, a second reflector, a laser igniter, and a hydraulic press.

[0013] The upper metal cylinder has a first observation window and a first laser illumination window on its surface. The first reflector is located inside the first observation window, and the first camera is located outside the first observation window. The lower bottom of the upper metal cylinder has a first transparent window.

[0014] The lower metal cylinder has a second observation window and a second laser irradiation window on its surface. The second reflector is located inside the second observation window, and the second camera is located outside the second observation window. The lower metal cylinder has a second transparent window on its top.

[0015] An experimental sample is placed between the first transparent window and the second transparent window;

[0016] A hydraulic press is located below the lower metal cylinder;

[0017] The laser igniter ignites the experimental sample outside the first laser irradiation window and the second laser irradiation window.

[0018] Optionally, a supplementary light illumination window and a screw hole are respectively opened on both sides of the surface of the upper metal cylinder. The supplementary light illumination window is used to illuminate the surface of the experimental sample, and the screw hole is used to fix the supplementary light inside the upper metal cylinder. A supplementary light illumination window and a screw hole are respectively opened on both sides of the surface of the lower metal cylinder. The supplementary light illumination window is used to illuminate the surface of the experimental sample, and the screw hole is used to fix the supplementary light inside the upper metal cylinder.

[0019] Optionally, the hydraulic press is a remotely controllable quasi-static hydraulic press, and the maximum output pressure of the quasi-static hydraulic press is 20MPa.

[0020] Optionally, a piezoelectric pressure sensor is provided at the hydraulic port of the hydraulic press, which is used to measure the dynamic pressure pulse transmitted to the hydraulic press by the explosion reaction; a piezoresistive pressure sensor is provided at the hydraulic port of the hydraulic press, which is used to measure the quasi-static pressure load applied by the hydraulic press to the sample, and records the preloaded stress-strain state of the experimental sample in conjunction with a displacement sensor.

[0021] Optionally, the maximum output power of the laser igniter is 3000W, and the maximum pulse length is 10ms.

[0022] Optionally, when using the laser igniter, the laser ignition head of the laser igniter is aligned with the graphite pre-embedded in the experimental sample, and the igniter is remotely activated to complete the ignition.

[0023] Optionally, both the first transparent window and the second transparent window are made of sapphire glass.

[0024] Optionally, it also includes an upper metal end cap and a lower metal end cap;

[0025] The upper metal end cap is located at the bottom of the upper metal cylinder, and a first groove is opened on the top of the upper metal end cap to place the sapphire glass in the first groove;

[0026] The lower metal end cap is located on top of the lower metal cylinder, and a second groove is formed at the bottom of the lower metal end cap to place the sapphire glass in the second groove.

[0027] Optionally, it also includes a fixed frame, which includes an upper top frame, a lower bottom frame, and side frames.

[0028] Optionally, it also includes a base disposed below the fixed frame.

[0029] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0030] This invention relates to an observation device for the reaction evolution effect of laser ignition in energetic materials. It designs an experimental apparatus for the aftereffects of energetic material reactions generated by laser-induced hotspots. Employing various testing techniques, it can acquire diverse data volumes and high-speed images. Combining these experimental results facilitates the analysis of the reaction hotspot propagation mechanism. Furthermore, this invention can apply axially controllable quasi-static preloads and set different constraint conditions to control multiple variables, allowing for the study of factors influencing the reaction growth process from multiple perspectives. The laser ignition method is convenient and quick to operate, simplifying the experimental process, while remote control of the ignition ensures the safety of experimental personnel. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 Schematic diagram of the observation device for the evolution of laser ignition reaction in energetic materials. Figure 1 ;

[0033] Figure 2 Schematic diagram of the observation device for the evolution of laser ignition reaction in energetic materials. Figure 2 ;

[0034] Figure 3 Schematic diagram of a metal cylindrical shell part;

[0035] Figure 4 This is a schematic diagram of a ring-shaped fill light;

[0036] Figure 5 Drawings of long bolts and nuts;

[0037] Figure 6 This is a drawing of the end cap part. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The purpose of this invention is to provide an observation device for the evolution of laser ignition reaction in energetic materials. The experimental process is simple to operate, and it can acquire a large amount of quantitative data on the ignition process, enabling full multi-factor coupling analysis of the hotspot propagation mechanism.

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Figure 1 Schematic diagram of the observation device for the evolution of laser ignition reaction in energetic materials. Figure 1 ,

[0042] Figure 2 Schematic diagram of the observation device for the evolution of laser ignition reaction in energetic materials. Figure 2 , Figure 3 This is a schematic diagram of a cylindrical metal shell part. Figure 1-3 As shown, an observation device for the evolution effect of laser ignition reaction of energetic materials includes an upper metal cylinder 1, a lower metal cylinder 2, a first camera 3, a second camera 4, a first reflector 5, a second reflector 6, a laser igniter 7, and a hydraulic press 8.

[0043] The upper metal cylinder 1 has a first observation window 9 and a first laser illumination window 10 on its surface. The first reflector 5 is located inside the first observation window 9, and the first camera 3 is located outside the first observation window 9. The lower bottom of the upper metal cylinder 1 has a first transparent window 10. The lower metal cylinder 2 has a second observation window and a second laser illumination window 17 on its surface. The second reflector 6 is located inside the second observation window, and the second camera 4 is located outside the second observation window. The top of the lower metal cylinder 2 has a second transparent window.

[0044] Experimental sample 13 is placed between the first transparent window and the second transparent window.

[0045] A hydraulic press 8 is located below the lower metal cylinder 2.

[0046] The laser igniter 7 ignites the experimental sample outside the first laser irradiation window and the second laser irradiation window.

[0047] Both the first camera 3 and the second camera 4 are high-speed cameras, which can clearly capture the burning and crack propagation process on the surface of the test sample.

[0048] The upper metal cylinder 1 has a supplementary light illumination window 11 and a screw hole 12 on both sides of its surface. The supplementary light illumination window 11 is used to illuminate the surface of the experimental sample, and the screw hole 12 is used to fix the supplementary light inside the upper metal cylinder to ensure sufficient brightness on the sample surface. The lower metal cylinder 2 also has a supplementary light illumination window and a screw hole on both sides of its surface. The supplementary light illumination window is used to illuminate the surface of the experimental sample, and the screw hole is used to fix the supplementary light inside the upper metal cylinder to ensure sufficient brightness on the sample surface. This facilitates clearer images and easier processing of experimental results. A schematic diagram of the ring-shaped supplementary light is shown below. Figure 4 As shown.

[0049] The hydraulic press 8 is a remotely controllable quasi-static hydraulic press with a maximum output pressure of 20 MPa. A piezoelectric pressure sensor 16 is installed at the hydraulic port of the hydraulic press 8 to measure the dynamic pressure pulse transmitted to the hydraulic press 8 by the explosion reaction. A piezoresistive pressure sensor is also installed at the hydraulic port of the hydraulic press 8 to measure the quasi-static pressure load applied to the sample by the hydraulic press 8. Combined with a displacement sensor 15, the pre-loaded stress-strain state of the experimental sample is recorded. The displacement sensor 15 is mainly used to record the stress-strain curve of the energetic material, facilitating the establishment of a constitutive model of the experimental sample.

[0050] This invention utilizes the characteristic of graphite readily absorbing laser energy to simulate the generation process of hot spots under non-impact conditions using laser ignition. The laser igniter 7 has a maximum output power of 3000W and a maximum pulse length of 10ms. In use, the laser igniter 7 is aligned with the graphite pre-embedded in the experimental sample, and the igniter is remotely activated to complete the ignition. Using laser ignition has two main advantages: First, the laser provides quantifiable and repeatable energy within a controllable timeframe, thereby controlling the size and temperature of the hot spot. Second, the heat from the laser can be transferred to the experimental sample through sapphire glass, thus avoiding the limitations of contact ignition sources like heating wires, which cannot meet the fully constrained conditions required during the experiment.

[0051] Both the first transparent window and the second transparent window are made of sapphire glass.

[0052] The observation device applied to the laser ignition reaction evolution effect of energetic materials also includes a fixed frame 14, which comprises an upper frame, a lower frame, and side frames. To ensure the stability of the main body, it is fixed using eight long bolts and nuts, with the long bolts penetrating the entire upper and lower frames. The penetrating portions are threaded to improve the reliability of the device during testing. The long bolts and nuts are as follows: Figure 5 As shown. The observation device for the evolution of laser ignition reaction in energetic materials also includes a base 15, which is disposed below the fixed frame.

[0053] Figure 6 The diagram shows the end cap component. The observation device applied to the laser ignition reaction evolution effect of energetic materials further includes an upper metal end cap and a lower metal end cap; the upper metal end cap is located at the bottom of the upper metal cylinder 1, and a first groove is formed at the top of the upper metal end cap, in which sapphire glass is placed; the lower metal end cap is located at the top of the lower metal cylinder 2, and a second groove is formed at the bottom of the lower metal end cap, in which sapphire glass is placed.

[0054] The observation device applied to the laser ignition reaction evolution effect of energetic materials can also add a reflector in the radial direction of the experimental sample to observe the surface changes of the sample from all angles. This device also supports the use of DIC (Digital Image Correlation) to record strain curves during crack propagation on the sample surface. The experimental sample is cylindrical. From one angle, only about 180 degrees of the cylindrical side surface can be observed. By adding concave and convex reflectors to the side of the experimental sample, 360 degrees of change on the side of the experimental sample can be observed.

[0055] This invention relates to an observation device for the reaction evolution effect of laser ignition in energetic materials. It designs an experimental apparatus for the aftereffects of energetic material reactions generated by laser-induced hotspots. Employing various testing techniques, it can acquire diverse data volumes and high-speed images. Combining these experimental results facilitates the analysis of the reaction hotspot propagation mechanism. Furthermore, this invention can apply axially controllable quasi-static preloads and set different constraint conditions to control multiple variables, allowing for the study of factors influencing the reaction growth process from multiple perspectives. The laser ignition method is convenient and quick to operate, simplifying the experimental process, while remote control of the ignition ensures the safety of experimental personnel.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0057] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A device for observing the evolution of laser ignition reactions in energetic materials, characterized in that, It includes an upper metal cylinder, a lower metal cylinder, a first camera, a second camera, a first reflector, a second reflector, a laser igniter, and a hydraulic press; The upper metal cylinder has a first observation window and a first laser illumination window on its surface. The first reflector is located inside the first observation window, and the first camera is located outside the first observation window. The lower bottom of the upper metal cylinder has a first transparent window. The lower metal cylinder has a second observation window and a second laser irradiation window on its surface. The second reflector is located inside the second observation window, and the second camera is located outside the second observation window. The lower metal cylinder has a second transparent window on its top. An experimental sample is placed between the first transparent window and the second transparent window; A hydraulic press is located below the lower metal cylinder; The laser igniter ignites the experimental sample outside the first laser irradiation window and the second laser irradiation window; The upper metal cylinder has a supplementary light illumination window and a screw hole on each side of its surface. The supplementary light illumination window is used to illuminate the surface of the experimental sample, and the screw hole is used to fix the supplementary light inside the upper metal cylinder. The lower metal cylinder has a supplementary light illumination window and a screw hole on each side of its surface. The supplementary light illumination window is used to illuminate the surface of the experimental sample, and the screw hole is used to fix the supplementary light inside the upper metal cylinder. The hydraulic press is a remotely controllable quasi-static hydraulic press, and the maximum output pressure of the quasi-static hydraulic press is 20MPa; The hydraulic press is equipped with a piezoelectric pressure sensor at its hydraulic port, which is used to measure the dynamic pressure pulse transmitted to the hydraulic press by the explosion reaction; the hydraulic press is also equipped with a piezoresistive pressure sensor at its hydraulic port, which is used to measure the quasi-static pressure load applied by the hydraulic press to the sample, and, in conjunction with a displacement sensor, to record the preloaded stress-strain state of the experimental sample. The maximum output power of the laser igniter is 3000W, and the maximum pulse length is 10ms. When using the laser igniter, the laser ignition head of the laser igniter is aligned with the graphite pre-embedded in the experimental sample, and the igniter is remotely started to complete the ignition.

2. The observation device for the evolution effect of laser ignition reaction in energetic materials according to claim 1, characterized in that, Both the first transparent window and the second transparent window are made of sapphire glass.

3. The observation device for the evolution effect of laser ignition reaction in energetic materials according to claim 2, characterized in that, It also includes an upper metal end cap and a lower metal end cap; The upper metal end cap is located at the bottom of the upper metal cylinder, and a first groove is opened on the top of the upper metal end cap to place the sapphire glass in the first groove; The lower metal end cap is located on top of the lower metal cylinder, and a second groove is formed at the bottom of the lower metal end cap to place the sapphire glass in the second groove.

4. The observation device for the evolution effect of laser ignition reaction in energetic materials according to claim 1, characterized in that, It also includes a fixed frame, which comprises an upper top frame, a lower bottom frame, and side frames.

5. The observation device for the evolution effect of laser ignition reaction in energetic materials according to claim 4, characterized in that, It also includes a base, which is disposed below the fixed frame.

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