Method for evaluating explosive detonation performance under trace conditions

Abstract

The application discloses a method for evaluating explosive detonation performance under trace conditions, which comprises the following steps: S1, laser ablation ignition is performed on sample explosive, and a schlieren photography technique is used to observe the propagation process of an air shock wave generated by the sample explosive reaction under different ablation laser energy conditions, so that a correlation between the ablation laser energy and the initial impact velocity is given; S2, a S curve model is established to analyze the variation trend of the initial impact velocity with the ablation laser energy, and optimal ablation laser energy information is obtained; and S3, experiments are performed by taking the optimal ablation laser energy as an initial condition, the initial impact velocity is correlated with known explosive detonation performance, and explosive detonation performance evaluation capability is realized. The application has the advantages of explosive detonation performance evaluation capability under milligram conditions.

Description

Technical Field

[0001] This invention relates to the field of explosive detonation performance evaluation technology, and in particular to a method for evaluating explosive detonation performance under micro-scale conditions. Background Technology

[0002] Explosives have wide applications in both defense and civilian fields. With a deeper understanding of explosive reaction mechanisms and the development of explosive synthesis technology, many new explosive materials, such as MOF (Metal-Organic Frameworks) explosives and all-nitrogen anionic materials, as well as novel explosive formulations based on these materials, have been developed. Although the testing methods for explosive detonation performance are now quite sophisticated, two major challenges remain in evaluating the detonation performance of new explosives and newly formulated explosives:

[0003] First, the amount of new explosives synthesized is generally very small (milligrams to grams), which cannot meet the requirements of traditional detonation performance testing experiments (tens of grams to hundreds of grams).

[0004] Secondly, before the new explosive formula is finalized, the proportions of various materials such as explosives and binders will be continuously adjusted. Using traditional evaluation techniques, multiple rounds of detonation performance tests are required, which is not efficient, economical, or environmentally friendly.

[0005] Currently, the LASEM (Laser-induced air shock from energetic materials) method has been developed. In the LASEM method, explosive materials are ablated by nanosecond pulsed lasers, resulting in a high-temperature chemical reaction. This reaction generates a laser-induced shock wave that propagates into the air above the sample. Schlieren photography is used to observe the propagation process of the shock wave in the air. The laser-induced shock velocity of the probe can be obtained through polynomial fitting. By correlating the laser-induced shock velocity of various traditional explosive materials with known detonation pressure, detonation velocity, detonation heat, and detonation energy, an evaluation curve can be obtained, which can then be used to evaluate the detonation performance of explosives with unknown parameters. However, this method also has some limitations. During the laser ablation of explosives, in addition to the work done on the air by the laser ignition reaction, the ionization effect of the focused laser on the air also does work. Therefore, the shock wave formed in reality is the result of the combined effect of these two factors. Thus, in the above method, because the mass of the explosive used is very small, the influence of the laser used to ignite the explosive on the work done on the air cannot be ignored. However, existing studies all use arbitrary single laser energy to ablate explosives without considering the influence of ablation laser energy on the air impact process, which reduces the accuracy of explosive detonation performance evaluation.

[0006] Furthermore, a safe, efficient, and economical pre-evaluation method is needed for testing the detonation performance of stored aging explosives. Therefore, it is essential to develop a method for evaluating the detonation performance of explosives under micro-scale (milligram level) conditions, which has broad application needs in explosive formulation design, development of new explosive materials, and evaluation of the detonation performance of stored aging explosives. Summary of the Invention

[0007] The purpose of this invention is to provide a method for evaluating the detonation performance of explosives under micro-scale conditions, which has the advantage of being able to evaluate the detonation performance of explosives at the milligram level.

[0008] To achieve the above objectives, this invention provides a method for evaluating the detonation performance of explosives under micro-scale conditions, assessing the detonation pressure and detonation velocity of sample explosives. The method includes: Step S1, laser ablation ignition of the sample explosive, observing the propagation process of the shock wave generated by the work done by the explosive reaction under different ablation laser energy conditions using schlieren photography, and providing the correlation between ablation laser energy and initial impact velocity; Step S2, establishing an S-curve model to analyze the trend of initial impact velocity with ablation laser energy, obtaining optimal ablation laser energy information; Step S3, conducting experiments using this optimal ablation laser energy as initial conditions, correlating the initial impact velocity with known explosive detonation performance, and realizing the ability to evaluate explosive detonation performance.

[0009] Preferably, step S1 includes: step S11, setting multiple different ablation laser energies, and ablating and igniting the sample explosive one by one, causing the sample explosive to react and do work on the air to form a shock wave; step S12, using schlieren photography to detect the propagation process of the shock wave in the air and obtain the propagation image of the shock wave front over time; step S13, correlating the position of the shock wave front with time to obtain the displacement-time relationship curve, and using a fifth-order polynomial to fit this curve to obtain the initial shock wave velocity; step S14, correlating different ablation laser energies with the initial shock velocity to obtain the change curve of ablation laser energy with the initial shock velocity.

[0010] Preferably, step S1 includes: the particle size distribution of the sample explosive is 10 micrometers to 40 micrometers.

[0011] Preferably, step S11 further includes: the energy range of the ablation laser energy is 0.6 J - 2.0 J, and the energy interval is 0.2 J.

[0012] Preferably, step S11 further includes: setting a lens with a focal length of 20 cm, and after the laser passes through the lens with a focal length of 20 cm, it ablates and ignites the sample explosive. The ablation laser energy is adjusted by polarization beam splitting. The sample explosive is placed 1.5 cm above the focal point of the lens to avoid the influence of air ionization.

[0013] Preferably, step S12 further includes: setting an external light source and a photographic device, wherein the light emitted by the external light source is focused on a single point as a point light source; and a first off-axis parabolic mirror and a conjugate off-axis parabolic mirror are positioned opposite each other above the sample stage, wherein the light emitted by the point light source is collimated by the first off-axis parabolic mirror to become parallel light as illumination light for schlieren photography, wherein the illumination light illuminates the area above the sample explosive in space; and then the light is focused by the conjugate off-axis parabolic mirror onto the photographic device, and the photographic device images the shock wave generated by the work done by the sample explosive.

[0014] Preferably, step S12 further includes: the photographic device is placed 15 cm away from the focal point of the conjugate off-axis parabolic mirror, and a zoom lens is set for fine adjustment to make the image clear; the frame rate of the photographic device is set to 100,000 frames and the shutter speed is set to 100 nanoseconds.

[0015] Preferably, in step S2, in order to quantitatively determine the optimal ablation laser energy, the experimental data are fitted using an S-curve model:

[0016]

[0017] in, The initial impact velocity, To ablation laser energy, As the baseline for velocity, The relative magnitude of the speed increase. The maximum rate of ascent of the initial impact velocity. This represents the energy of the ablation laser at its maximum rise rate.

[0018] Preferably, step S3 includes: step S31, using the optimal ablation laser energy as the initial condition, obtaining the initial impact velocity of different types of sample explosives under this condition; step S32, correlating the initial impact velocity of different types of sample explosives under this condition with the known detonation pressure and detonation velocity parameters of the corresponding explosives to obtain the curves of detonation pressure and detonation velocity changing with the initial impact velocity; fitting the curves of detonation pressure and detonation velocity changing with the initial impact velocity using a linear relationship to obtain the detonation performance evaluation curve; step S33, obtaining the initial impact velocity of sample explosives with unknown detonation performance under the optimal ablation energy condition, and substituting this as the independent variable into the detonation performance evaluation curve to obtain the detonation pressure and detonation velocity information of the sample explosives with unknown detonation performance.

[0019] In summary, compared with the prior art, the method for evaluating the detonation performance of explosives under micro-scale conditions provided by the present invention has the following beneficial effects:

[0020] First, the present invention proposes a method for evaluating the detonation performance of explosives under micro-conditions. The explosives are ignited using an energy-resolved method, and the influence of ablation laser energy is analyzed using a mathematical model to find the optimal ablation laser energy under specific conditions.

[0021] Second, the present invention proposes an evaluation method for the detonation performance of explosives under micro-conditions. By analyzing the linearity of the relationship between the initial impact velocity and the known detonation pressure and velocity of typical explosives under different ablation laser energy conditions, it is confirmed that the experimental and data analysis methods of the present invention significantly increase the reliability of the detonation performance evaluation. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a method for evaluating the detonation performance of explosives under micro-scale conditions proposed in this invention.

[0023] Figure 2 This is a flowchart of a method for evaluating the detonation performance of explosives under micro-scale conditions proposed in this invention.

[0024] Figure 3 This is a schematic diagram of an apparatus for implementing a method for evaluating the detonation performance of explosives under micro-scale conditions, as proposed in this invention.

[0025] Figure 4 This is a schlieren photograph of the shock wave propagating in the air, as shown in an embodiment of the present invention.

[0026] Figure 5 The average impact velocity varies with time in this embodiment of the invention.

[0027] Figure 6The initial impact velocity varies with the ablation laser energy in this embodiment of the invention.

[0028] Figure 7 These are fitting parameters for the trend of initial impact velocity changing with ablation laser energy in embodiments of the present invention.

[0029] Figure 8 This is the explosive detonation pressure and detonation velocity evaluation curve of an embodiment of the present invention. Detailed Implementation

[0030] The following will be combined with the appendix in the embodiments of the present invention. Figure 1 ~Appendix Figure 8 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0031] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0032] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0033] like Figure 1 and Figure 2 As shown, a method for evaluating the detonation performance of explosives under trace conditions is used to evaluate sample explosives. The method includes:

[0034] Step S1: Laser ablation ignition is performed on the sample explosive. Schlieren photography is used to observe the propagation process of the shock wave generated by the reaction work of the sample explosive under different ablation laser energy conditions, and the correlation between ablation laser energy and initial impact velocity is given.

[0035] Schlieren photography is an optical measurement technique that uses the refraction of light to visualize density changes in transparent media. It is widely used in fluid mechanics, aerodynamics, and combustion science, and is particularly adept at capturing flow fields that are difficult to observe directly with the naked eye. When light passes through a transparent medium with uneven density (such as differences in air density caused by temperature gradients or pressure changes), it is deflected due to changes in the medium's refractive index. Schlieren systems capture this deflection using special optical devices (such as knife edges, prisms, and gratings) and convert it into an image with contrasting light and dark areas, thus visually representing the density distribution of the medium.

[0036] Step S2: Establish an S-curve model to analyze the trend of the initial impact velocity with the ablation laser energy and obtain the optimal ablation laser energy information.

[0037] Step S3: Using this optimal ablation laser energy as the initial condition, conduct experiments to correlate the initial impact velocity with the known detonation performance of explosives, thereby achieving the ability to evaluate the detonation performance of explosives.

[0038] In a specific embodiment, step S1 includes:

[0039] Step S11: Set multiple different ablation laser energies and ablate and ignite the sample explosives one by one, so that the sample explosives react and do work on the air to form a shock wave.

[0040] In a preferred embodiment, the ablation laser energy ranges from 0.6 J to 2.0 J, with an energy interval of 0.2 J, totaling eight single pulses. Additionally, a lens with a focal length of 20 cm can be used; after passing through the 20 cm lens, the laser ablates and ignites the sample explosive.

[0041] The ablation laser energy was adjusted using polarization beam splitting, and the sample explosive was placed 1.5 cm above the laser focal point to avoid the influence of air ionization. The focal spot size was approximately 1 mm, determined by the scar left by the laser ablation of the aluminum film.

[0042] Step S12: Use schlieren photography to detect the propagation process of the shock wave in the air and obtain the propagation image of the shock wave over time.

[0043] In a preferred embodiment, the photographic device is positioned 15 cm above the focal point of the lens and fine-tuned using a zoom lens to ensure sharp imaging. The frame rate of the photographic device is set to 100,000 frames per second, and the shutter speed is set to 100 nanoseconds.

[0044] Furthermore, step S12 also includes: setting up an external light source and a photographic device, wherein the light emitted by the external light source is focused on a single point as a point light source (using a slit and zoom lens as described in later embodiments, which will not be elaborated here); and a first off-axis parabolic mirror (passing through an off-axis parabolic mirror as described in later embodiments, which will not be elaborated here) and a conjugate off-axis parabolic mirror are positioned opposite each other above the sample stage, wherein the light emitted by the point light source is collimated by the first off-axis parabolic mirror to become parallel light as illumination light for schlieren photography, and the illumination light illuminates the area above the sample explosive in space; then it is focused by the conjugate off-axis parabolic mirror to the photographic device, and the photographic device images the shock wave formed by the work done by the explosive (passing through a conjugate off-axis parabolic mirror as described in later embodiments, which will not be elaborated here).

[0045] Step S13: Correlate the position before the shock wave with time to obtain the displacement-time curve, and use a fifth-order polynomial to fit this curve to obtain the initial shock wave velocity.

[0046] Step S14: Correlate different ablation laser energies with the initial impact velocity to obtain the curve of ablation laser energy changing with the initial impact velocity.

[0047] In step S2, to quantitatively determine the optimal ablation laser energy, the experimental data are fitted using an S-curve model:

[0048]

[0049] in, The initial impact velocity, To ablation laser energy, As the baseline for velocity, The relative magnitude of the speed increase. The maximum rate of ascent of the initial impact velocity. This represents the energy of the ablation laser at its maximum rise rate.

[0050] In a specific embodiment, step S3 includes:

[0051] Step S31: Using the optimal ablation laser energy as the initial condition, obtain the initial impact velocity of different types of sample explosives under this condition; wherein, this step can be carried out in accordance with the idea of ​​steps S11 to S14.

[0052] Step S32: Correlate the initial impact velocity of different types of sample explosives under this condition with the known detonation pressure and detonation velocity parameters of the corresponding explosives to obtain the curves of detonation pressure and detonation velocity as a function of initial impact velocity; use the linear relationship to fit the curves of detonation pressure and detonation velocity as a function of initial impact velocity to obtain the detonation performance evaluation curve.

[0053] Step S33: Obtain the initial impact velocity of the sample explosive with unknown detonation performance under the optimal ablation energy condition. Substitute this velocity into the detonation performance evaluation curve (step S32) to obtain the detonation pressure and detonation velocity information of the sample explosive with unknown detonation performance.

[0054] like Figure 3 As shown, a brief description of the apparatus for carrying out the present invention is given here.

[0055] Samples typically consist of single-element explosives such as RDX (RDX), HMX (Octogen), TATB (Triaminotrinitrobenzene), LLM105 (2,6-diamino-3,5-dinitropyrazine-1-oxide), and CL20 (hexanitrohexaazaisowulzane). The powder is adhered to a carrier plate using double-sided adhesive and then compacted with a pressure plate. This invention utilizes laser ablation technology to ignite the explosives. The laser beam emitted from the laser is polarized and its energy adjusted by a beam splitter. The adjusted laser beam is then focused onto the sample surface through a mirror and lens. The laser ablation effect induces a reaction in the explosive, and the entire reaction process performs work on the air, generating a shock wave.

[0056] This invention uses schlieren photography to detect the work done on air by an explosive reaction. Illumination light emitted from an arc lamp is collimated by components within the arc lamp and an off-axis parabolic mirror, forming parallel light that passes above the ablation zone of the explosive as illumination. A high-speed camera images the area above the ablation zone, so that the shock wave generated by the work done on air by the explosive reaction is imaged on the camera's photosensitive surface. A digital delay generator synchronizes the laser emission and camera opening processes, adjusting the delay to ensure the camera opens at the appropriate time.

[0057] This device is a proposed apparatus for implementing the method of the present invention. In specific embodiments, it can be adjusted and modified according to existing technology. For example, it can be composed of five parts: an optical path module, a laser, an arc lamp, a high-speed camera, and a fiber optic spectrometer. The optical path module includes a sample stage that can move in two dimensions and a pair of off-axis parabolic mirrors. The laser is connected to the optical path module via a light guide and focused onto the sample stage by a lens integrated with the light guide, providing energy for ignition of the explosive. The arc lamp is connected to the optical path module via a flange and collimated by the pair of parabolic mirrors, serving as illumination light for schlieren photography. The high-speed camera is connected to the optical path module via a flange, serving as a detection device for schlieren photography, used for video imaging of shock waves in the air. The fiber optic spectrometer is connected to the optical path module via a fiber optic interface, used to monitor the reaction of the explosive.

[0058] The following are specific examples.

[0059] The first step is device verification.

[0060] In practical applications, a laser pulse is emitted from a laser, transmitted via a light guide, and focused onto the sample by a lens at the end of the light guide. The sample is placed on a platform so that the focal length can be adjusted vertically and the ablation position horizontally. White light emitted from the arc lamp is collimated by a first off-axis parabolic mirror and passes over the sample as illumination. The propagation of the shock wave generated by the work done on the air by the explosive reaction is observed using a high-speed camera.

[0061] The second step is sample preparation.

[0062] Five energetic materials—RDX, HMX, TATB, LLM-105, and CL-20—were used in the preparation of the target (sample). These energetic material powders were all prepared by solvent evaporation, with a purity exceeding 99% and a particle size distribution ranging from 10 to 40 micrometers. During target preparation, double-sided tape was applied to a glass substrate consisting of a support sheet. Approximately 15 milligrams of the energetic material powder were then placed on top and compacted with a pressure plate. Excess powder was removed from the support sheet by gentle tapping.

[0063] The third step is the experimental procedure.

[0064] For ignition, laser ablation is used to detonate the energetic material on the target; for detection, schlieren photography is used to detect the propagation process of the shock wave generated by the work done on the air by the explosion of the energetic material. Specific details are as follows... Figure 1 As shown, the laser emitted from the laser (1064 nm, 10 ns) is focused onto the target through a lens with a focal length of 20 cm to detonate the energetic material on it. The single-pulse energy of the laser is adjusted by polarization beam splitting. In the experiment, the single-pulse energy range was set to 0.6 J-2.0 J, with an energy interval of 0.2 J, for a total of 8 single-pulse energies. The target was placed 1.5 cm above the laser focal point to avoid the influence of air ionization. The focal spot size was approximately 1 mm, determined by the scar left by the laser ablation of the aluminum film.

[0065] Regarding the external light, the light emitted from the arc lamp equipped with a mercury-argon bulb (maximum power: 500 W, set power: 300 W) is approximately focused onto a single point as a point light source through the slit of the mercury-argon bulb and the zoom lens. This light is then collimated into parallel light by a first off-axis parabolic mirror (aperture: 50.8 cm, focal length: 15 cm) to serve as illumination for schlieren photography. This illumination light spatially illuminates the area above the target and is focused by another conjugate off-axis parabolic mirror (aperture: 50.8 cm, focal length: 15 cm). A high-speed camera is positioned 15 cm from the focal point of the conjugate off-axis parabolic mirror and fine-tuned using a zoom lens to ensure sharp imaging. The camera frame rate is set to 100,000 frames per second, the shutter speed to 100 nanoseconds, and the effective pixel count to 120 × 1152.

[0066] The excitation and detection actions are synchronized electrically, using the Q-conversion signal of the laser to trigger the high-speed camera. During this process, the time interval between the camera's first frame acquisition and the trigger time is affected by the camera's de-shake time, response time, acquisition period, and latency. In the experiment, the camera's de-shake time was set to 1 microsecond, the response time to approximately 30 nanoseconds, and the acquisition period to 10 microseconds. Therefore, based on these parameters, it can be seen that the camera will acquire its first frame approximately 10.18 microseconds after triggering.

[0067] The fourth step is data processing.

[0068] I. Initial Impact Velocity

[0069] In the experiment, laser ablation detonates the energetic material on the target, and the explosion of the energetic material creates a shock wave by doing work on the air. The average velocity of the shock wave at each moment can be derived from its propagation path. For the five energetic materials used in the experiment, the trend of the shock velocity changing with time is similar. Here, the results of CL-20 are used to illustrate the general trend of the shock velocity changing with time.

[0070] like Figure 4 As shown, under each ablation laser energy loading condition, the trend of impact velocity change with time is similar for CL-20, all of which decay with time, and the decay rate becomes smaller over time.

[0071] like Figure 5 As shown, the trend of impact velocity versus time under each ablation laser energy condition is fitted using a fifth-order nonlinearity, and the intercept of the fitted curve with the velocity axis is defined as the initial impact velocity.

[0072] II. Optimal Ablation Laser Energy

[0073] For different ablation laser energy loading conditions, the impact velocity increases with the increase of ablation laser energy. In order to clarify the relationship between impact velocity and ablation laser energy, the initial impact velocity and ablation laser energy are correlated to explore the influence of ablation laser energy on the shock wave propagation process.

[0074] like Figure 6 As shown, the initial impact velocity exhibits an overall S-shaped trend with increasing ablation laser energy. The initial impact velocity is primarily influenced by two factors: the work done by the laser breaking down the air and the work done by the reaction of the energetic material. In the energy range of 0.6 J – 1.0 J, the increase in initial impact velocity is relatively gradual, indicating that under these conditions, the ablation laser energy is too low to cause all the energetic material in the ablation region to react. In this case, the work done by the laser breaking down the air dominates the increase in laser-induced impact velocity.

[0075] In the energy range of 1.0 J - 1.6 J, the initial impact velocity increases rapidly, indicating that under this condition the energy is sufficient to cause all the energetic materials in the ablation zone to react. Furthermore, as the energy increases, the ablation zone also expands. At this point, the work done by the reaction of the energetic materials dominates the increase in the initial impact velocity.

[0076] In the energy range of 1.6 J - 2.0 J, the increase in initial impact velocity becomes relatively gradual, indicating that as the energy density continues to increase, the ablation pulse can break down the air and ionize it before the focal point, making the work done by the laser breaking down the air the dominant factor again.

[0077] Comparing the above processes, only when the ablation laser pulse energy is in the range of 1.0 J - 1.6 J does the work done by the energetic material reaction dominate the increase in initial impact velocity. Therefore, when using initial impact velocity to evaluate the detonation performance of energetic materials, the ablation laser pulse energy should be set within this energy range.

[0078] To quantitatively determine the optimal ablation laser energy, the experimental data were fitted using an S-curve.

[0079]

[0080] in, The initial impact velocity, To ablation laser energy, As the baseline for velocity, The relative magnitude of the speed increase. The maximum rate of ascent of the initial impact velocity. This represents the energy of the ablation laser at its maximum rise rate.

[0081] For five energetic materials, the fitting parameters for the initial impact velocity as a function of ablation laser energy are listed in... Figure 7 The fitting results show that the maximum rise rate of the initial impact velocity varies slightly for these five energetic materials, primarily due to the material's sensitivity. The average maximum rise rate of the laser-induced impact velocity for each energetic material is 5.83 m / s·J. At the maximum rise rate, the ablation laser energy for each material is relatively close, with an average of 1.33 J. Therefore, under our experimental conditions, setting the ablation laser pulse energy to around 1.33 J is most suitable for evaluating the detonation performance of energetic materials using the initial impact velocity.

[0082] III. Evaluation Curve

[0083] The initial impact velocity is correlated with the detonation pressure and detonation velocity to form an evaluation curve for the detonation performance of energetic materials. For example... Figure 8 As shown, the initial impact velocity exhibits a monotonic relationship with both the detonation pressure and detonation velocity of the energetic material. Linear fitting was used to analyze these two monotonic relationships. The fitting results indicate that when the laser energy is 1.4 J, the closer the correction parameter value is to 1, the better the fit similarity.

[0084] The laser energy of 1.4 J is closest to the 1.33 J obtained from the fitting analysis of the relationship between laser energy, initial impact velocity, and ablation laser energy, thus proving the rationality of this analysis process. Furthermore, it demonstrates that before evaluating the detonation performance of energetic materials using laser ablation, it is essential to analyze the influence of ablation laser energy on the initial impact velocity to find the optimal ablation laser energy.

[0085] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for evaluating the detonation performance of explosives under trace conditions, wherein a sample explosive is evaluated, characterized in that, The method includes: Step S1: Laser ablation ignition is performed on the sample explosive. Schlieren photography is used to observe the propagation process of the shock wave generated by the work done by the explosive reaction under different ablation laser energy conditions, and the correlation between ablation laser energy and initial impact velocity is given. Step S2: Establish an S-curve model to analyze the trend of the initial impact velocity with the ablation laser energy and obtain the optimal ablation laser energy information. Step S3: Using this optimal ablation laser energy as the initial condition, conduct an experiment to correlate the initial impact velocity with the known detonation performance of explosives, thereby achieving the ability to evaluate the detonation performance of explosives. Step S1 includes: Step S11: Set multiple different ablation laser energies and perform laser ablation ignition on the sample explosives one by one, so that the sample explosives react and do work on the air to form a shock wave. Step S12: Use schlieren photography to detect the propagation process of the shock wave in the air and obtain the propagation image of the shock wave over time. Step S13: Correlate the position before the shock wave with time to obtain the displacement-time curve, and use a fifth-order polynomial to fit this curve to obtain the initial shock wave velocity. Step S14: Correlate different ablation laser energies with the initial impact velocity to obtain the curve of ablation laser energy as a function of the initial impact velocity; In step S2, to quantitatively determine the optimal ablation laser energy, the experimental data are fitted using an S-curve model: ， in, The initial impact velocity, To ablation laser energy, As the baseline for velocity, The relative magnitude of the speed increase. The maximum rate of ascent of the initial impact velocity. This represents the energy of the ablation laser at its maximum rise rate.

2. The method for evaluating the detonation performance of explosives under trace conditions according to claim 1, characterized in that, Step S1 includes: the particle size distribution of the sample explosive is 10 micrometers to 40 micrometers.

3. The method for evaluating the detonation performance of explosives under micro-scale conditions according to claim 2, characterized in that, Step S11 further includes: the energy range of the ablation laser energy is 0.6 J - 2.0 J, and the energy interval is 0.2 J.

4. The method for evaluating the detonation performance of explosives under trace conditions according to claim 3, characterized in that, Step S11 further includes: setting a lens with a focal length of 20 cm, and after the laser passes through the lens with a focal length of 20 cm, it ablates and ignites the sample explosive. The ablation laser energy is adjusted by polarization beam splitting. The sample explosive is placed 1.5 cm above the focal point of the lens to avoid the influence of air ionization.

5. The method for evaluating the detonation performance of explosives under micro-scale conditions according to claim 4 is characterized in that, Step S12 further includes: setting an external light source and a photographic device, wherein the light emitted by the external light source is focused on a single point as a point light source; and a first off-axis parabolic mirror and a conjugate off-axis parabolic mirror are positioned opposite each other above the sample stage, wherein the light emitted by the point light source is collimated by the first off-axis parabolic mirror to become parallel light as illumination light for schlieren photography, wherein the illumination light illuminates the area above the sample explosive in space; and then the light is focused by the conjugate off-axis parabolic mirror onto the photographic device, and the photographic device images the shock wave formed by the work done by the sample explosive.

6. The method for evaluating the detonation performance of explosives under trace conditions according to claim 5, characterized in that, Step S12 further includes: the photographic device is placed 15 cm away from the focal point of the conjugate off-axis parabolic mirror, and a zoom lens is set for fine adjustment to make the image clear. The frame rate of the photographic device is set to 100,000 frames and the shutter speed is set to 100 nanoseconds.

7. The method for evaluating the detonation performance of explosives under trace conditions according to claim 6, characterized in that, Step S3 includes: Step S31: Using the optimal ablation laser energy as the initial condition, the initial impact velocity of different types of sample explosives under this condition is obtained. Step S32: Correlate the initial impact velocity of different types of sample explosives under this condition with the known detonation pressure and detonation velocity parameters of the corresponding explosives to obtain the curves of detonation pressure and detonation velocity as a function of initial impact velocity; use the linear relationship to fit the curves of detonation pressure and detonation velocity as a function of initial impact velocity to obtain the detonation performance evaluation curve. Step S33: Obtain the initial impact velocity of the sample explosive with unknown detonation performance under the optimal ablation energy condition. Substitute this velocity into the detonation performance evaluation curve to obtain the detonation pressure and detonation velocity information of the explosive with unknown detonation performance.

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