With the rapid development of hypervelocity weapons, analyzing the penetration effectiveness of hypervelocity weapon warheads on concrete shields is significant for the design of newly-built protective structures and the safety evaluation of as-built protective structures. Focusing on the penetration performance of AGM-183A hypervelocity weapon warhead against three typical shields: normal strength concrete (NSC), ultra-high performance concrete (UHPC), and corundum rubble concrete (CRC), firstly, the reliability of the numerical algorithms, mesh size, and material model parameters used in the finite element analysis method was fully validated by comparing the experimental and simulation results of three types of target subjected to penetration of steel/tungsten alloy projectiles. Subsequently, a numerical analysis method for the prototype scenario was established based on a mesh transition strategy equivalent to penetration depth and recovered projectile length. Finally, a series of simulations were conducted for the AGM-183A hypervelocity weapon warhead penetrating the aforementioned three shields at Ma ranging from 3 to 8. The results indicate that: (1) the AGM-183A hypervelocity weapon warhead reaches maximum penetration depth when NSC, UHPC, and CRC shields subjected to penetration at Ma=4, Ma=4, and Ma=3, respectively, with depths of 4.26, 3.74, and 1.00 m. Due to instability phenomena of projectiles, such as fractures at the junction between the head and body caused by local stress concentration, further increases in penetration velocity lead to a decrease in penetration effectiveness; (2) compared with the combined penetration and explosion damage depths of conventional sound speed penetrating warheads SDB, WDU-43/B, and BLU-109/B, the penetration depths induced by AGM-183A into NSC, UHPC, and CRC shields are 3.2, 1.6, and 1.8 times, 4.7, 2.1, and 2.2 times, and 3.4, 1.3, and 1.5 times higher, respectively; (3) the recommended design thicknesses of the three shields against the AGM-183A hypervelocity weapon warhead are 8.01, 7.03, and 1.88 m, respectively. The UHPC shield shows no significant improvement subjected to hypervelocity penetration compared with the NSC shield. Comparatively, the CRC shield is recommended for shield design, which can be effectively subjected to both conventional subsonic and hypervelocity impacts.
In physics, a “source” denotes the origin of matter or energy, while a “sink” refers to the terminal point of matter or energy. By analogizing with the energy source problem in underground explosions, this study proposes an energy sink problem for ideal fluid cavity annihilation. A detailed analysis is conducted on the energy balance and adjustment mechanisms in the ideal fluid cavity annihilation problem, establishing the relationships among fluid pressure work, energy convergence, transmission and transformation. A characteristic energy factor is introduced to describe the “centripetal convergence” behavior of energy sinks. The characteristic energy factor for energy sinks incorporates the information on converged energy, geometric dimensions of cavities and physical properties of fluids, effectively characterizing the “convergence” behavior of energy sink problems and laying a theoretical foundation for the subsequent research on “energy sink” problems in solids. The physical mechanisms and mathematical foundations of the characteristic energy factor are analyzed, and its characteristics and advantages are expounded. Specifically, the introduction of the characteristic energy factor circumvents the need for complex stress-strain relationships, boundary conditions, and unknown internal material structures in traditional continuum mechanics, significantly simplifying the complexity of the problem. The characteristic energy factor is primarily applicable to the predictions of engineering disasters with large scales or well-defined failure zones (e.g., underground explosions, large-scale surrounding rock deformation, zonal disintegration or pendulum waves, and shear-slip rock bursts in ore pillars), whereas its applicability to highly localized engineering disasters with unknown failure zones (e.g., strain-type rock bursts) requires further investigation.
Regarding the displacement response of clamped circular plates under multiple far-field blast loads, we proposes a novel theoretical modeling approach based on membrane theory energy equations, by simplifying multiple blast loads into linearly decaying pulse sequences, a theoretical displacement response model for clamped circular plates is established for the first time, considering both strain rate strengthening effects and cumulative hardening effects. The linear displacement field approximation is adopted for the initial loading phase, while a quadratic function displacement field assumption is introduced for subsequent loading phases, deriving recursive formulas for midpoint displacements under multiple blasts. Numerical validations were conducted using LS-DYNA for both double and triple blast scenarios. For double blast cases, theoretical predictions exhibited errors of 20%–30% compared to simulation results, while errors reduced to below 20% for triple blast conditions. The ASTM A415 steel circular plate model was used for the simulations, and the strain rate strengthening effect was described by the Cowper-Symonds model. Finite element models with quadrilateral shell elements demonstrated strong agreement with experimental data (errors<10%), confirming model reliability. The assumption of quadratic function displacement field for subsequent loading phases was verified by numerical displacement curves of the middle profiles of the plates. Further parametric analysis proved that the theoretical model is effective for different tangent modulus, which represents the strength of the strain strengthening effect. The model reveals that midpoint displacement can be characterized as a weighted square root function combining the final explosion’s individual displacement and prior cumulative displacement, with displacement increments from subsequent explosions decreasing as prior cumulative displacement increases.
Iridium alloys have been extensively utilized as structural materials in specific high-temperature applications, attributed to their superior strength and ductility at elevated temperatures. To enhance the understanding of high-speed impacts at elevated temperatures, it is imperative to characterize the mechanical properties of iridium alloys, including their failure response under high strain rates and elevated temperatures. In this study, the conventional split Hopkinson tension bar technique was modified to evaluate the tensile behavior of an iridium alloy at high strain rates and elevated temperatures. A dynamic high-temperature tensile testing technique for thin and flat specimens was established based on the high current heating method. A fixture with a slot was employed, enabling the specimen shoulder to bear the load and transmit it to the gauge section of the specimen. An integrated high current heater equipped with a self-controlled system was utilized to heat the iridium alloy specimen and maintain the desired high-temperature conditions. To prevent unintended heating of the bars, a pair of hollow water-cooled pillow blocks were installed. Moreover, to mitigate rapid cooling of the specimen, the cold contact time was meticulously controlled to be less than 1 ms. To elucidate the dynamic high-temperature properties of the iridium alloy, tensile tests were conducted using this technique at a strain rate of 103 s−1 and at temperatures of room temperature, 600, 900, and 1100 ℃. Experimental results revealed that as the temperature increased from room temperature to 900 ℃, the tensile strength of the iridium alloy decreased by 12%, while its ductility doubled. However, when the temperature was further elevated to 1100 ℃, the tensile strength decreased by 43%, and the ductility increased by a factor of 7.3. Macroscopic and microscopic analyses of the fracture morphologies were conducted to reveal the deformation mechanisms of the iridium alloy. It was found that with increasing temperature, the failure mode of the iridium alloy transitioned from predominantly intergranular fracture to plastic deformation and granular fracture. The dynamic fracture behavior of iridium alloy at high temperatures is governed by the competition between grain-boundary failure and granular softening.
Polypropylene (PP) is widely utilized in industrial production, yet PP dust generated during its production and transportation can form explosive dust clouds, leading to severe dust explosion accidents that threaten personnel and equipment safety. To address this issue, a novel explosion suppressant, NiP@Fe-SBA-15, was synthesized to inhibit the propagation of PP dust combustion flames. The synthesis involved modifying SBA-15 mesoporous silica with Fe ions and subsequently loading NiP, resulting in a composite powder with uniformly dispersed active components and a well-preserved mesoporous structure. Characterization via SEM-Mapping and N2 adsorption-desorption experiments revealed that NiP@Fe-SBA-15 maintains a high specific surface area, exhibits a regulated pore structure, and shows no significant particle agglomeration. The Hartman tube explosive testing system was employed to evaluate the effect of NiP@Fe-SBA-15 on PP dust deflagration. Results indicated that as the NiP@Fe-SBA-15 additive increased, the flame propagation speed, brightness, and flame length of PP deflagration decreased significantly, with flame propagation almost completely inhibited by a suppressant dosage with the mass fraction of 70 %. The dual explosion suppression mechanism of NiP@Fe-SBA-15 was analyzed. Physically, NiP@Fe-SBA-15 occupies reaction space, reducing oxygen and combustible volatile concentrations, while the SBA-15 molecular sieve, exposed by thermal decomposition of the suppressant, absorbs heat and forms a physical barrier, thereby reducing combustion intensity. Chemically, NiP decomposition releases Ni· and P· radicals that consume key free radicals (H·, O·, OH·) in combustion reactions, interrupting explosion chain reactions. Meanwhile, Fe-based species rapidly oxidize to Fe3O4, reducing oxygen availability and further weakening combustion intensity. In summary, NiP@Fe-SBA-15 was proven to be an effective explosion suppressant for PP dust explosions, reducing combustion intensity through combined physicochemical synergies. This research provides a new approach to enhancing polypropylene industry safety. Future work will focus on optimizing the industrial application of NiP@Fe-SBA-15 explosion suppressants while addressing cost, environmental sustainability, and stability issues to further advance dust explosion prevention technology.
In the present study, numerical analyses were conducted to enhance the strength of the magnetic field. While electromagnetic coils and permanent magnets have conventionally been used for this purpose, the study explores the utilization of superconducting magnets, known for their significantly stronger magnetic fields. Through analytical tests on a thruster powered by a 5-kW source at 400 V, and 12.5 A current, computer simulations are conducted using an open-source HallThruster.jl developed using Julia language which gave 1D simulation of plasma properties of Hall effect thruster (HET), along a thrust of 0.687 N was achieved representing a three times greater increase, and specific impulse increasing to 3097 s which is 1.7 times more compared to conventional results, accompanied by improved plasma parameters. Furthermore, to study the particle behavior the Particle In cell (PIC) approach was utilized, from which particle motion due to the magnetic field was achieved. By enhancing the magnetic field, we can significantly boost thrust, unlocking new possibilities for exploring distant planets and conducting long-duration space missions. Utilizing superconducting materials ensures continuous, efficient operation with increased thrust and fewer operating payloads, ultimately enhancing overall spacecraft functionality. This advancement paves the way for future innovations in space exploration and applications.
The defective cracks were prefabricated on the wall of the notch holes by using polymethyl methacrylate (PMMA) material, which were parallel or vertical to the notch, and the distance from the defective cracks to the hole center was 2, 3, and 4 mm. The influence of notch hole wall defects on the crack propagation of notch blasting was investigated by using a digital dynamic caustic experimental system with numerical simulation. At the same time, triacetone triperoxide (TATP) explosives were employed as a charge, which served to mitigate the effect of gun smoke on the dynamic caustic experimental system and to improve the experimental design. The results demonstrate that the reflection of the stress wave at parallel defects results in a downward shift in the direction of crack initiation at the notch, but the refraction of the stress wave at vertical defects has no effect on the direction of crack initiation. The presence of wall defects in the hole impedes the impact of stress waves and blast gases on the cracks at the notch, resulting in a reduction in the length, expansion rate, and strength factor values of the cracks, and the degree of inhibition is contingent upon the distance of the defects from the centre of the borehole. As the distance between the parallel defects and the centre of the borehole increases, the inhibition effect of the parallel defects on both sides of the notch cracks gradually decreases. The inhibition effect of vertical defects on the far side of the notch cracks gradually decreases, while the inhibition effect on the proximal side of the notch cracks gradually enhances. The left and right notch cracks of vertical defects are more significantly affected by the boundary reflected stress wave than those of parallel defects. The notch cracks on the left side do not exhibit a clear pattern, owing to the pre-existing reflected stress wave at the defects. In contrast, the notch cracks on the right side are substantially diminished by the boundary-reflected stress wave as the vertical defects move away from the centers of the notch holes.
Theoretical and observational approaches to settling the important questions surrounding the progenitor systems and the explosion mechanism of normal Type Ia supernovae have thus far failed. With its unique capability to obtain continuous spectra through the near- and mid-infrared, JWST now offers completely new insights into Type Ia supernovae. In particular, observing them in the nebular phase allows us to directly see the central ejecta and thereby constrain the explosion mechanism. We aim to understand and quantify differences in the structure and composition of the central ejecta of various Type Ia supernova explosion models. We examined the currently most popular explosion scenarios using self-consistent multidimensional explosion simulations of delayed-detonation and pulsationally assisted, gravitationally confined delayed detonation Chandrasekhar-mass models and double-detonation sub-Chandrasekhar-mass and violent merger models. We find that the distribution of radioactive and stable nickel in the final ejecta, both observable in nebular spectra, are significantly different between different explosion scenarios. Therefore, comparing synthetic nebular spectra with JWST observations should allow us to distinguish between explosion models. We show that the explosion ejecta are inherently multidimensional for all models, and the Chandrasekhar-mass explosions simulated in spherical symmetry in particular lead to a fundamentally unphysical ejecta structure. Moreover, we show that radioactive and stable nickel cover a significant range of densities at a fixed velocity of the homologously expanding ejecta. Any radiation transfer postprocessing has to take these variations into account to obtain faithful synthetic observables; this will likely require multidimensional radiation transport simulations.
Samuel S. Taylor, Kálmán Varga, Károly Mogyorósi
et al.
Fragmentation dynamics in the Coulomb explosion of hydrocarbons, specifically methane, ethane, propane, and butane, are investigated using time dependent density functional theory (TDDFT) simulations. The goal of this work is to elucidate the distribution of fragments generated under laser-driven Coulomb explosion conditions. Detailed analysis reveals the types of fragments formed, their respective charge states, and the optimal laser intensities required for achieving various fragmentations. Our results indicate distinct fragmentation patterns for each hydrocarbon, correlating with the molecular structure and ionization potential. Additionally, we identify the laser parameters that maximize fragmentation efficiency, providing valuable insights for experimental setups. This research advances our understanding of Coulomb explosion mechanisms and offers a foundation for further studies in controlled molecular fragmentation.
Reaction networks have been widely used as generic models in diverse areas of applied science, such as biology, chemistry, ecology, epidemiology, and computer science. Reaction networks incorporating noisy effect are modelled as continuous time Markov chains (CTMC), and are called stochastic reaction systems. Non-explosivity is a concept that characterizes regularity of CTMCs. In this paper, we study non-explosivity of stochastic reaction systems, in the sense of their underlying CTMCs. By constructing a simple linear Lyapunov function, we obtain non-explosivity for a class of endotactic stochastic reaction systems containing second-order endotactic stochastic mass-action systems as a subset. As a consequence, we prove that every bimolecular weakly reversible stochastic mass-action system is non-explosive. We apply our results to diverse models in biochemistry, epidemiology, ecology, and synthetic biology in the literature.
4,4′-azobis(1,2,4-triazole) (Atrz) is an excellent thermally stable explosive that is widely used to synthesize high-energy nitrogen-rich compounds. However, current methods for synthesizing this compound are low-yield and exothermic. In order to overcome these limitations, in this study, a continuous method based on the use of continuous stirred tank reactor (CSTR) was used to prepare Atrz for the first time, and the optimal experimental conditions were obtained by single factor experimental method and orthogonal experimental method. The yield of Atrz increased from 20%-30% to 71.84%, and the purity reached 98.54%. The use of CSTR enables materials to be mixed efficiently, making the reaction process efficient and environmentally friendly. At the same time, this method has the advantages of simple reaction process, easy large-scale continuous production, and high yield.
Sathiskumar PS, Alok Kumar Patel, Vinay Paliwal
et al.
This work details the study conducted on composite solid propellants with activated copper chromite (ACR) as burn catalyst for its burn rate change with time due to the interaction of ammonium perchlorate (AP) with ACR. One of the hypotheses cited for burn rate reduction is the conversion of chromite in ACR to chromate by an electrolytic reaction with moisture in the presence of ammonium perchlorate. This hypothesis was studied by a design of experiments which includes blending ammonium perchlorate and ACR, Aluminum and ACR, stand alone ACR in raw material stage and the blends storage with time. The effect of moisture in AP is addressed by comparing undried and dried AP in the blends. The blended raw materials were characterized by Thermo-gravimetric analysis, Particle Size Distribution, surface area measurement, Scanning Electron Microscopy and chromium estimation. Results show that the conversion of chromium from chromite to chromate is very minimum in the presence of AP. Propellant samples are prepared with these blends at different time intervals to understand viscosity, mechanical properties and burn rate behavior with raw material storage. Experimental results show burn rate shows an opposite trend of increase with blend storage of 6 months. A plausible explanation for this observation is presented in the paper correlating the experimental conditions.
Ivan Gospodinov, Kostiantyn V. Domasevitch, Cornelia C. Unger
et al.
3,3‘,5,5‘-Tetranitro-4,4‘-bipyrazole monohydrate (TNBPz, 1⋅H2O) is an excellent precursor for the synthesis of new energetic materials (2–12). Several nitrogen-rich salts (e.g. guanidinium, aminoguanidinium, hydrazinium, ammonium and hydroxylammonium) were prepared from 1⋅H2O by neutralization reactions. In addition, the N-methylation and N-amination of compound TNBPz was investigated and is reported. All new synthesized energetic materials were fully characterized by NMR (1H, 13C, 14N, and 15N) spectroscopy, infrared spectroscopy, differential thermal analysis (DTA) and elemental analysis. Compounds 2, 4–8 and 10 were characterized with single crystal X-ray diffraction. The heats of formation for compounds 2, 4–6, 8, 11 and 12 were calculated using the atomization method based on CBS-4 M enthalpies. Several detonation parameters, such as detonation pressure, velocity and energy, were calculated by using the X-ray densities and the calculated standard molar enthalpies of formation. The sensitivities of all energetic materials toward external stimuli were tested according to the BAM standards. In addition, the toxicity toward vibrio fischeri bacteria of few energetic salts (3 and 4) is reported.
Mohammed Jouini, Amir Abdelaziz, Djalal Trache
et al.
This study conducted a detailed examination of the characteristics of hydroxyl‑terminated polybutadiene (HTPB) doped with potato starch nitrate (NPS) as a high-energy-density binder. The investigation specifically focused on evaluating the impact of NPS doping on the chemical structure, energetic attributes, and thermokinetic behavior of HTPB-NC binder systems. The findings demonstrated advantageous features, including favorable chemical compatibility, improved material density accompanied by remarkable thermal stability, substantial energy release, and high chemical reactivity. These findings contribute to the understanding of HTPB-NPS composite and offer evidence for its remarkable features, indicating promising prospects for its utilization in the development of advanced formulations for high-energy-density propellants in future applications.
The rheological properties and isothermal curing kinetics of the GAP/AN/HMX propellant slurries were investigated by steady rheological measurements and isothermal rheological measurements, and subsequently, the rheological model and the curing kinetics equation of the slurries were constructed, respectively. The results indicate that the GAP/AN/HMX propellant slurries are Carreau–Yasuda fluids, and the apparent viscosity of the slurries gradually decreases with the increase in shear rate and temperature. The storage modulus and loss modulus of the slurries show an ''S'' growth with the curing reaction, and the higher temperature causes a significant reduction in the time required for complete curing of the slurries. The pot-lifes of the slurries at 55 °C, 60 °C and 65 °C are 52590 s, 19820 s, 18150 s, respectively, with a noticible decrease with increasing temperature. Furthermore, the curing reaction of the slurries is viewed as an autocatalytic reaction, and the corresponding curing degrees (αmax) at the maximum curing rate are 0.3481 (55 °C), 0.3536 (60 °C), and 0.4420 (65 °C), respectively.
SNe Ia play a key role in the fields of astrophysics and cosmology. It is widely accepted that SNe Ia arise from thermonuclear explosions of WDs in binaries. However, there is no consensus on the fundamental aspects of the nature of SN Ia progenitors and their explosion mechanism. This fundamentally flaws our understanding of these important astrophysical objects. We outline the diversity of SNe Ia and the proposed progenitor models and explosion mechanisms. We discuss the recent theoretical and observational progress in addressing the SN Ia progenitor and explosion mechanism in terms of the observables at various stages of the explosion, including rates and delay times, pre-explosion companion stars, ejecta-companion interaction, early excess emission, early radio/X-ray emission from CSM interaction, surviving companions, late-time spectra and photometry, polarization signals, and SNR properties, etc. Despite the efforts from both the theoretical and observational side, the questions of how the WDs reach an explosive state and what progenitor systems are more likely to produce SNe Ia remain open. No single published model is able to consistently explain all observational features and the full diversity of SNe Ia. This may indicate that either a new progenitor paradigm or the improvement of current models is needed if all SNe Ia arise from the same origin. An alternative scenario is that different progenitor channels and explosion mechanisms contribute to SNe Ia. In the next decade, the ongoing campaigns with the JWST, Gaia and the ZTF, and upcoming extensive projects with the LSST and the SKA will allow us to conduct not only studies of individual SNe Ia in unprecedented detail but also systematic investigations for different subclasses of SNe Ia. This will advance theory and observations of SNe Ia sufficiently far to gain a deeper understanding of their origin and explosion mechanism.
ABSTRACT: The first attempt to use genetic function approximation (GFA) for prediction of aquatic toxicity of soluble energetic materials is reported in this paper. The prediction is based on the estimation of the luminescent bacteria Aliivibrio fischeri inhibition in water according to the recently reported experimental results. Thus, two quantitative structure-activity relationship (QSAR) models for 15 min and 30 min exposure were obtained, which include five and six essential descriptors, respectively. Most of them are so-called “fast descriptors” assuming there is no need for quantum-chemical calculations. The rest descriptors are obtained in terms of semi-empirical approach allowing the prediction to be rapidly complete. The developed QSAR models provide relatively high correlation coefficients, namely, R2 = 0.81 and 0.82 for 15 min and 30 min datasets, respectively. The experimental datasets included a number of values, which were presented ambiguously (< or > than certain values). Thus, these have not been included (13 for 15 min and 10 for 30 min datasets) in the training sets and used them as the corresponding test sets. As a result, the developed models accurately indicate what exactly the higher and lower values should be applied instead of ones presented with ambiguity. Thus, the results may be useful for predicting the aquatic toxicity of new nitrogen-rich energetic materials, both molecular and ionic, bearing nitro, nitramino, azido groups and other commonly used explosophores.
There are 4 general approaches for imparting or improving thermal stability of explosives ‘Salt Formation’, ‘Introduction of Amino Group/s’, ‘Introduction of Conjugation’ & ‘Condensation with Triazole Ring/s’ as proposed by Agrawal which were supported by some typical examples. We have recently reported a large number of explosives which validate ‘Salt Formation’ & ‘Introduction of Amino Group/s’ approaches. In this review paper, we report additional examples of explosives scattered over in the literature to validate the ‘Introduction of Conjugation’ & ‘Condensation with Triazole Ring/s’ approaches for imparting/improving thermal stability of explosives. Wherever, data on thermal stability is not available in the literature, the same has been calculated using Energetic Materials Designing Bench (EMDB), Version 1.0. The data generated on a large number of explosives clearly brings out validation of ‘Introduction of Conjugation’ & ‘Condensation with Triazole Ring/s’ approaches for imparting/improving thermal stability of explosives. Further, as the number of triazole ring/s increases, thermal stability also increases. In addition, density, impact sensitivity & velocity of detonation data of promising explosives which are also essential from their application point of view, have been reported. This study also reveals that explosives (i) DAHNS (Explosive 3), PATO (Explosive 15), BTATNB (Explosive 17), TTTATNB (Explosive 19), DANTNP (Explosive 31) and TTATNB (Explosive 35) appear to be better substitutes of HNS and (ii) BDATTz (Explosive 36) and BTDAONAB (Explosive 39) appear to be better substitutes of TATB, a benchmark thermally stable explosive at present.
Adamantane is an important and versatile skeleton for synthesis of a large number of cage-like energetic compounds since its high intrinsic density, symmetry, stability, and derivability. Herein, a novel cage-like energetic compound, 4,4,8,8-tetranitro-2-oxaadamantane was synthesized in an overall yield of 21.1% from easily accessible compounds through six steps. Thermogravimetry (TG) and differential scanning calorimetry (DSC) tests indicate that it has excellent thermal stability since its decomposition temperature was found to be 288 °C, and the theoretical detonation velocity is calculated to be 6955 m/s. These results imply that the as-prepared compound has the potential to be applied as heat-resistant explosive.