Effects of nano-sized aluminum on detonation characteristics and metal acceleration for RDX-based aluminized explosive

Nano-sized aluminum(Nano-Al)powders hold promise in enhancing the total energy of explosives and the metal acceleration ability at the same time.However,the near-detonation zone effects of reaction between Nano-Al with detonation products remain unclear.In this study,the overall reaction process of 170 nm Al with RDX explosive and its effect on detonation characteristics,detonation reaction zone,and the metal acceleration ability were comprehensively investigated through a variety of experiments such as the detonation velocity test,detonation pressure test,explosive/window interface velocity test and confined plate push test using high-resolution laser interferometry.Lithium fluoride(LiF),which has an inert behavior during the explosion,was used as a control to compare the contribution of the reaction of aluminum.A thermochemical approach that took into account the reactivity of aluminum and ensuing detonation products was adopted to calculate the additional energy release by afterburn.Combining the numerical simulations based on the calculated afterburn energy and experimental results,the param-eters in the detonation equation of state describing the Nano-Al reaction characteristics were calibrated.This study found that when the 170 nm Al content is from 0％to 15％,every 5％increase of aluminum resulted in about a 1.3％decrease in detonation velocity.Manganin pressure gauge measurement showed no significant enhancement in detonation pressure.The detonation reaction time and reaction zone length of RDX/Al/wax/80/15/5 explosive is 64 ns and 0.47 mm,which is respectively 14％and 8％higher than that of RDX/wax/95/5 explosive(57 ns and 0.39 mm).Explosive/window interface velocity curves show that 170 nm Al mainly reacted with the RDX detonation products after the detonation front.For the recording time of about 10 μs throughout the plate push test duration,the maximum plate velocity and plate acceleration time accelerated by RDX/Al/wax/80/15/5 explosive is 12％and 2.9 μs higher than that of RDX/LiF/wax/80/15/5,respectively,indicating that the aluminum reaction energy significantly increased the metal acceleration time and ability of the explosive.Numerical simulations with JWLM explosive equation of state show that when the detonation products expanded to 2 times the initial volume,over 80％of the aluminum had reacted,implying very high reactivity.These results are significant in attaining a clear understanding of the reaction mechanism of Nano-Al in the development of aluminized explosives.     

Gas metal arc welding of high nitrogen stainless steel with Ar-N2-O2 ternary shielding gas

High nitrogen stainless steel with nitrogen content of 0.75％was welded by gas metal arc welding with Ar—N2-O2 ternary shielding gas. The effect of the ternary shielding gas on the retention and improvement of nitrogen content in the weld was identified. Surfacing test was conducted first to compare the ability of O2 and CO2 in prompting nitrogen dissolution. The nitrogen content of the surfacing metal with O2 is slightly higher than CO2. And then Ar—N2-O2 shielding gas was applied to weld high nitrogen stainless steel. After using N2-containing shielding gas, the nitrogen content of the weld was improved by 0.1 wt％. As N2 continued to increase, the increment of nitrogen content was not obvious, but the ferrite decreased from the top to the bottom. When the proportion of N2 reached 20％, a full austenitic weld was obtained and the tensile strength was improved by 8.7％. Combined with the results of surfacing test and welding test, it is concluded that the main effect of N2 is to inhibit the escape of nitrogen and suppress the ni-trogen diffusion from bottom to the top in the molten pool.     

Mechanical behavior and failure mechanism of polyurea nanocomposites under quasi-static and dynamic compressive loading

Polyurea is an elastomeric material that can be applied to enhance the protection ability of structures under blast and impact loading.In order to study the compressive mechanical properties of SiC/polyurea nanocomposites under quasi-static and dynamic loading,a universal testing machine and split Hop-kinson pressure bar(SHPB)apparatus were used respectively.The stress-strain curves were obtained on polyurea and its composites at strain rates of 0.001-8000 s-1.The results of the experiment suggested that increase in the strain rates led to the rise of the flow stress,compressive strength,strain rate sensitivity and strain energy.This indicates that all of the presented materials were dependent on strain rate.Moreover,these mechanical characters were enhanced by incorporating a small amount of SiC into polyurea matrix.The relation between yield stress and strain rates were established using the power law functions.Finally,in order to investigate the fracture surfaces and inside information of failed specimens,scanning electron microscopy(SEM)and micro X-ray computed tomography(micro-CT)were used respectively.Multiple voids,crazes,micro-cracks and cracking were observed in fracture surfaces.On the other hand,the cracking propagation was found in the micro-CT slice images.It is essential to understand the deformation and failure mechanisms in all the polyurea materials.     

A method to determine the shell layout scheme for equipment battlefield damage tests under artillery fire

In this paper,a new method for determining the shell layout scheme is proposed,which can make the equipment damage data by the battlefield damage test resemble as close as possible the actual combat data.This method is based on the analysis of the impact point distribution and effective damage area of equipment.In order to obtain the position of the impact points,an impact point distribution model under artillery fire was established.Similarly,in order to obtain the effective damage area of equipment,the concepts of generalized damage area and task-based equipment functional damage probability were demonstrated,and the corresponding calculation model was established.Through case analysis,the shell layout scheme was effectively obtained,verifying the correctness of the proposed method.     

唐生智与1937年南京保卫战

1937年12月爆发的南京保卫战,是抗战初期的重要战役之一。国民政府蒋介石任命唐生智为南京卫戍司令长官,具体负保卫南京之责。他将10余万卫戍军部署在外围阵地及复廓阵地上,以抗击来犯的约8个师团的日本侵略军。保卫战于12月5日正式打响,经过近10天的殊死战斗,消灭敌人大批有生力量,但以种种原因,国民政府首都南京于12月13日陷于敌手。凶残成性的日本侵略者制造了骇人听闻的南京大屠杀,我被杀害的军民同胞达30万人,为世界所罕见。中国军民在战斗中表现出来的高度爱国主义精神,令人钦敬;保卫战的经验教训及其历史地位,永远载入中国抗战史册。     

孙吴益州战略论析

益州战略是孙吴建国初期即定下的图取天下的基本战略。赤壁之战后,孙吴着手实施益州战略,由于复杂的三国政治、军事、外交以及地理形势等因素的作用,刘备集团占据益州,孙吴最终无法实现益州战略。基于现实,孙吴修正了益州战略,以略取、经营益州为主变为防御、联合益州为主,从而与蜀汉形成矛盾统一的关系。益州战略贯穿孙吴历史,深刻影响三国政局。     

西方传统武德文化中的德性之维

西方文明虽有崇尚战争、赞美胜利的倾向,但这并不影响其传统武德文化放射注重战争正义和军人德性的光芒。西方传统武德文化的“正义必胜”战略思想、以“爱国主义”为核心的道德规范体系、“注重自然法和重视精神力量作用”的传统在当代军人武德建设中仍有积极意义。     

古代军人利益观述评

本文对古代中外一些国家不同时代的军人利益观进行了梳理,并作了简要的评论,指出了这些军队的军人利益观之阶级特点、民族特征,且与我军军人利益观作了粗浅的比较。希冀此文能起到抛砖引玉的作用,引发对军人利益观问题的深入研究。     

一种新型直流电网短路限流装置的设计与分析

针对直流电网短路故障时迅速产生的短路电流,利用IGBT器件为核心,设计出一种新型的直流短路电网限流装置并阐述了其工作原理.在分析了该装置的各种工作状态后,给出了对应的数学解析模型,为直流电网短路限流装置各参数的设计提供了理论依据.研制出小功率实验样机,并经过实验验证了解析模型的正确性和所设计的限流装置工作的快速有效性.