A series of ballistic experiments were performed to investigate the damage behavior of high velocity reactive material projectiles(RMPs) impacting liquid-filled tanks,and the corresponding hydrodynamic ram(HRAM) was s...
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A series of ballistic experiments were performed to investigate the damage behavior of high velocity reactive material projectiles(RMPs) impacting liquid-filled tanks,and the corresponding hydrodynamic ram(HRAM) was studied in ***/Al/W RMPs with steel-like and aluminum-like densities were prepared by a pressing/sintering *** projectiles impacted a liquid-filled steel tank with front aluminum panel at approximately 1250 m/*** corresponding cavity evolution characteristics and HRAM pressure were recorded by high-speed camera and pressure acquisition system,and further compared to those of steel and aluminum *** different from the conical cavity formed by the inert metal projectile,the cavity formed by the RMP appeared as an ellipsoid with a conical *** RMPs were demonstrated to enhance the radial growth velocity of cavity,the global HRAM pressure amplitude and the front panel damage,indicating the enhanced HRAM and structural damage ***,combining the impact-induced fragmentation and deflagration characteristics,the cavity evolution of RMPs under the combined effect of kinetic energy impact and chemical energy release was *** mechanism of enhanced HRAM pressure induced by the RMPs was further revealed based on the theoretical model of the initial impact wave and the impulse ***,the linear correlation between the deformation-thickness ratio and the non-dimensional impulse for the front panel was obtained and *** was determined that the enhanced near-field impulse induced by the RMPs was the dominant reason for the enhanced structural damage behavior.
Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex *** study first implements multiple objective topology optimizatio...
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Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex *** study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is *** two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic *** experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic ***,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic *** explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.
2,6-bis(picrylamino)-3,5-dinitropyridine(PYX)has excellent thermostability,which makes its thermal decomposition mechanism receive much *** this paper,the mechanism of PYX thermal decomposition was investigated thorou...
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2,6-bis(picrylamino)-3,5-dinitropyridine(PYX)has excellent thermostability,which makes its thermal decomposition mechanism receive much *** this paper,the mechanism of PYX thermal decomposition was investigated thoroughly by the ReaxFF-lg force field combined with DFT-B3LYP(6-311++G)*** detailed decomposition mechanism,small-molecule product evolution,and cluster evolution of PYX were mainly *** the initial stage of decomposition,the intramolecular hydrogen transfer reaction and the formation of dimerized clusters are earlier than the denitration *** the progress of the reaction,one side of the bitter amino group is removed from the pyridine ring,and then the pyridine ring is *** final products produced in the thermal decomposition process are CO_(2),H_(2)O,N_(2),and H_(2).Among them,H_(2)O has the earliest generation time,and the reaction rate constant(k_(3))is the *** clusters are formed during the decomposition of PYX,and the formation,aggregation,and decomposition of these clusters are strongly affected by *** low temperatures(2500 K-2750 K),many clusters are *** high temperatures(2750 K-3250 K),the clusters aggregate to form larger *** 3500 K,the large clusters decompose and become *** the late stage of the reaction,H and N in the clusters escaped almost entirely,but more O was trapped in the clusters,which affected the auto-oxidation process of ***'s initial decomposition activation energy(E_(a))was calculated to be 126.58 kJ/*** work contributes to a theoretical understanding of PYX's entire thermal decomposition process.
Afterburning behind the detonation front of an aluminized explosive releases energy on the millisecond timescale,which prolong the release of detonation energy and the energy release at different stages also shows sig...
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Afterburning behind the detonation front of an aluminized explosive releases energy on the millisecond timescale,which prolong the release of detonation energy and the energy release at different stages also shows significant ***,at present,there are few effective methods for evaluating the energy release characteristics of the middle reaction stage of such explosives,which can have a duration of tens to hundreds of *** present work demonstrates an approach to assessing the midstage of an aluminized explosive detonation based on a water push test employing a high degree of *** this method,the explosive is contained in a steel cylinder having one end closed that is installed at the bottom of a transparent water *** detonation,the gaseous products expand in one direction while forcing water ahead of *** resulting underwater shock wave and the interface between the gas phase products and the water are tracked using an ultra-high-speed framing and streak *** shock wave velocity in water and the expansion work performed by the gaseous detonation products were calculated to assess the energy release characteristics of aluminized explosives such as CL-20 and RDX in the middle stage of the detonation *** the middle stage of the detonation process of these aluminized explosives,the aluminum reaction reduced the attenuation of shock waves and increased the work performed by gas phase products.A higher aluminum content increased the energy output while the presence of oxidants slowed the energy release *** work demonstrates an effective means of evaluating the performance of aluminized explosives.
In order to study the blast damage effects of aviation kerosene storage tanks,the out-field explosion experiments of 8 m3fixed-roof tanks were carried *** fragments,shock wave and fireball thermal radiation of the tan...
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In order to study the blast damage effects of aviation kerosene storage tanks,the out-field explosion experiments of 8 m3fixed-roof tanks were carried *** fragments,shock wave and fireball thermal radiation of the tank in the presence of bottom oil,half oil and full oil,as well as empty tank,were investigated under internal explosion by various TNT charge contents(1.8 kg,3.5 kg and 6.2 kg).The results showed that the tank roof was the only fragment produced,and the damage forms could be divided into three *** increase of TNT charge content and oil volume enlarged the deformation of the tank,while the hole ratio presented a trend of increase first and then *** H_r,maxand V_(max)values positively increased as increasing the TNT charge content and oil volume(from empty to half oil),but decreased in full *** Pmaxvalues had a progressive increase with the increment of TNT charge content,but not the case with the increase in oil *** development of fireball was divided into three stages:tank roof‘towed'flame,jet flow flame tumbling and rising,and jet flow flame *** Dmaxand Hf,maxvalues both increased as increasing TNT charge content and oil *** oscillation phenomenon of fireball temperature was observed in the cooling *** average temperature of fireball surface was positively correlated with TNT charge content,and negatively correlated with oil volumes.
Porous materials are widely used in the field of protection because of their excellent energy absorption *** this work,a series of polyurethane microscopic models are established and the effect of porosity on the shoc...
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Porous materials are widely used in the field of protection because of their excellent energy absorption *** this work,a series of polyurethane microscopic models are established and the effect of porosity on the shock waves is studied with classical molecular dynamics ***,shock Hugoniot relations for different porosities are obtained,which compare well with the experimental *** pores collapse and form local stress wave,which results in the complex multi-wave structure of the shock *** microstructure analysis shows that the local stress increases and the local velocity decreases gradually during the process of pore collapse to complete ***,it leads to stress relaxation and velocity *** shock stress peaks can be fitted with two exponential functions,and the amplitude of attenuation coefficient decreases with the increase of ***,the pore collapse under shock or non-shock are discussed by the entropy increase rate of the *** energy is dissipated mainly through the multiple interactions of the waves under *** energy is dissipated mainly by the friction between atoms under non-shock.
Titanium hydride(TiH_(2)), a promising high-energy additive, is doped into PTFE/Al to optimize the energy output structure of the reactive jet and strive for better aftereffect damage ability to the target. Six types ...
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Titanium hydride(TiH_(2)), a promising high-energy additive, is doped into PTFE/Al to optimize the energy output structure of the reactive jet and strive for better aftereffect damage ability to the target. Six types of PTFE/Al/TiH_(2) reactive liners with different TiH_(2) content are prepared by the molding and sintering method. The energy release characteristics of PTFE/Al/TiH_(2) reactive jet are tested by the transient explosion energy test, and are characterized from pressure and temperature. The reaction delay time,pressure history, and temperature history of the energy release process are obtained, then the actual value of released energy and reaction efficiency of the reactive jet are calculated. The results show that the peak pressure and temperature of the PTFE/Al/TiH_(2) jet initially increase and then decrease with increasing TiH_(2) content. When the TiH_(2) content is 10%, the actual value of released energy and reaction efficiency increased by 24% and 6.4%, respectively, compared to the PTFE/Al jet. The reaction duration of the reactive material is significantly prolonged as the TiH_(2) content increased from 0% to 30%. Finally,combined with the energy release behaviors of PAT material and the dynamic deformation process of liner, the enhancement mechanism of TiH_(2) on energy release of the reactive jet is expounded.
Spent galvanizing acid solution contains high concentrations of zinc salts, ferrous salts, and residual acids,exhibiting extremely high value-added recovery potential. However, achieving the efficient extraction and s...
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Spent galvanizing acid solution contains high concentrations of zinc salts, ferrous salts, and residual acids,exhibiting extremely high value-added recovery potential. However, achieving the efficient extraction and separation of Zn over Fe becomes particularly challenging under elevated Zn ion concentration. Here, the key extraction parameters, such as modifier ratio, Cyanex 923 concentration and ratio of organic phase to aqueous phase(O/A), are investigated. The stripping and regeneration of extractant, extraction mechanism, as well as high-value recovery of Zn and Fe resources are also comprehensively expounded. After the two-stage extraction,the extraction efficiency of Zn and Fe is 98.92 % and 2.09 %, respectively. Moreover, the stripping efficiency of Zn reaches 92.3 % with O/A ratio of 1 : 2, using oxalic acid as stripping agent. The predominant extracted species is confirmed to be ZnCl-3, resulting in the formation of HZnCl3· R3PO complex. More importantly, the regenerated extractant can be recycled back into the extraction process, and the reproduced HCl, high-value recovered ZnO and Fe2O3can be used for different industrial fields. These findings lay a solid foundation for the efficient separation and comprehensive recovery of high-concentration spent galvanizing acid solution.
In this paper, the high-efficiency thermal insulation composites were prepared and investigated, which are formed by the addition of hollow SiO2 microspheres, hollow glass microspheres, and hollow phenolic microsphere...
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Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway ***,the safety performance and mec...
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Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway ***,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be *** work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration *** penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also *** results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway *** difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the *** controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.
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