钨铜粉末药型罩射孔弹对钢靶侵彻的数值模拟

利用Ansys/Ls-Dyna软件对钨铜粉末药型罩射孔弹侵彻钢靶过程进行了数值模拟。运用混合物的叠加原理对钨铜混合材料的状态方程参数进行了计算,得到钨铜(20W80Cu)粉末药型罩的参数。采用多物质ALE算法,模拟了钨铜药型罩射流的形成及侵彻钢靶的过程,模拟89型号射孔弹作用45#钢靶,穿深为153mm,孔径为9.6mm,并与实际情况对比,数值模拟结果与实验结果差别在5%以内。     

活性金属药型罩射孔弹破甲试验研究*

为增大射孔弹的穿孔孔径,设计了一种活性金属药型罩,该种药型罩中包含在外界作用下可产生放热反应的铝/镍金属体系,同时选用3种活性金属材料配方开展相应试验,并与铜钨金属粉末药型罩的作用效能进行对比。试验结果表明,添加一定比例反应性金属能够提高药型罩射流的后效作用能力、增大穿孔孔径,其中,铜粉质量分数为10％时对增加射流穿深几乎没有形成帮助,而当铜粉质量分数为70％时,射流的穿深显著增大。     

矩形射孔弹射流形成机理的微元法数值分析研究

对矩形射孔弹射流的形成过程及其侵彻靶板的过程进行数值仿真研究,并采用将药型罩进行微元划分的方法,研究药型罩微元的运动规律以及射流的有效结构,获得了射流的头部速度、纵向速度分布、射流的临界侵彻速度等一系列评估射流威力特性的重要参数。结果表明:对于45号钢质靶板,在射流对靶板进行侵彻的过程中,张角为60°的药型罩产生的有效射流为速度超过550 m/s以上的药型罩微元所形成的射流段;有效射流的高速段(v≥1300 m/s)由药型罩顶部材料组成,有效射流的中速段(1000 m/s≤v1300 m/s)由药型罩的中部及中上部材料组成,沿药型罩母线方向靠近底部约0.2倍母线长度的材料不形成有效射流。     

钨铜聚能粒子流的侵彻特性研究

为研究钨铜聚能粒子流的侵彻特性,对钨铜多孔药型罩和紫铜板药型罩的侵彻性能进行了试验研究,测试了钨铜聚能粒子流侵彻铝板的穿深与时间关系曲线。试验结果表明:在1倍装药口径炸高下,钨铜聚能粒子流侵彻铝靶的穿深比紫铜板射流侵彻铝靶的穿深要提高31%。利用最小二乘法对穿深与时间关系曲线进行拟合,拟合结果表明穿深与时间的关系呈乘幂形式。结合侵彻试验结果,确定了钨铜聚能粒子流的最后侵彻速度为1657.8m/s。这为多孔药型罩聚能装药的设计提供一定的指导意义。     

基于SPH方法对不同药型罩线性聚能射流形成及后效侵彻过程的模拟

为了解决传统基于网格的数值方法在模拟线性聚能射流问题时因大变形而导致网格畸变使计算难以进行的问题,本文通过自编程实现的光滑粒子法（SPH）对不同药型罩线性聚能装药射流形成及其侵彻金属靶板的过程开展了数值模拟研究,所实现的算法可以为线性聚能射流数值模拟研究提供新途径。本文所开展的研究首先基于已有的线性聚能射流试验模型进行模拟分析,采用SPH方法有效实现了线性聚能射流的形成过程,数值模拟获得的射流头部速度与试验比对误差在10%以内。然后建立了装药质量、药型罩质量和装药横截面宽度相同的前提下不同药型罩线性聚能射流模型,数值模拟获得不同药型罩形成的射流特征以及侵彻金属靶板的开口宽度和侵彻深度随时间的变化规律。研究得到的不同药型罩线性聚能射流形成及后效侵彻规律可为线性聚能射流的设计提供参考。     

前舱干扰下锥弧药型罩射流成型及侵彻性能研究

为了有效地降低前舱对聚能射流的干扰作用,提高聚能战斗部侵彻混凝土靶的威力,设计了一种锥弧药型罩。利用动力学仿真软件AUTODYN 2D对两种小锥段不同壁厚的锥弧药型罩和相同装药结构下的传统药型罩在前舱干扰情况下形成射流的过程进行数值模拟研究,分析这3种药型罩形成射流的性能,最后通过静破甲试验验证锥弧药型罩的侵彻性能。结果表明:与传统结构药型罩相比,在爆轰压力作用下,锥弧药型罩的锥形部分形成头部高速射流,减少在前舱的射流消耗,增加侵彻深度;弧形部分形成的射流质量利用率高,可形成粗大射流,提高侵彻能力;小锥段1.6 mm和2.5 mm壁厚锥弧药型罩形成的射流都能够侵彻1 200 mm厚的混凝土靶板,且小锥段1.6 mm壁厚锥弧药型罩形成的射流侵彻性能更好。     

辅助药型罩尺寸大小对半球形药型罩射流成型影响的数值模拟

为研究辅助药型罩尺寸对半球形药型罩射流成型的影响，采用数值模拟的方法对加装辅助药型罩结构的半球形药型罩射流形成性能进行了研究。结果表明：加装辅助药型罩后半球形药型罩所形成的射流质量相较于单一半球形药型罩具有明显提高，辅助药型罩直径d=0.6D,厚度h=0.1D时所形成的射流综合性能与其他方案相比较好，采用该方案与单一半球形药型罩进行半无限钢靶的侵彻对比，侵彻深度提高了76.8%。     

平顶药型罩聚能射流形成过程研究

ANSYS/LS-DYNA对平顶药型罩的射流形成过程进行数值模拟,结果表明,在顶点起爆条件下,平顶药型罩的平顶中心首先下凹并拉动药型罩边壁向内汇聚,使得存在夹角的平顶与边壁整体构成环形线性聚能罩,此聚能罩在炸药爆轰作用下产生一级射流,一级射流彼此作用继而产生更高速度的二级射流。分析认为其机理是二级药型罩成型假说,尝试探索研究多级射流领域,并为提高射流速度提供一种新思路。     

柱-锥结合线型药型罩射流特性的数值模拟

为了提升线型聚能装药的切割能力,在锥形线型药型罩的基础上设计了一种新型柱-锥结合线型药型罩,并采用数值模拟软件ANSYS/ls-dyna对柱-锥结合线型药型罩、圆弧顶线型药型罩、锥形线型药型罩射流的形成及切割45号钢板的过程进行了数值模拟,通过对比3种结构药型罩形成射流的头尾部速度、拉伸断裂时间、对45号钢板的切割能力来确定设计方案的可行性。研究表明:柱-锥结合线型药型罩形成射流的头部速度最高,相对锥形线型药型罩提高了约12.6%,相对圆弧顶线型药型罩提高了约5.4%;而且柱-锥结合线型药型罩形成的射流拉伸性能较好,能量更高,对45号钢板的切割能力最强,相对圆弧顶线型药型罩提升了约26.7%,相对锥形线型药型罩提升了约58.8%。     

平顶药型罩聚能射流形成过程研究

ANSYS/LS-DYNA对平顶药型罩的射流形成过程进行数值模拟,结果表明,在顶点起爆条件下,平顶药型罩的平顶中心首先下凹并拉动药型罩边壁向内汇聚,使得存在夹角的平顶与边壁整体构成环形线性聚能罩,此聚能罩在炸药爆轰作用下产生一级射流,一级射流彼此作用继而产生更高速度的二级射流。分析认为其机理是二级药型罩成型假说,尝试探索研究多级射流领域,并为提高射流速度提供一种新思路。     

Experimental and analytical study of early time material processing, in a collapsing shaped - charge liner, using “softly - recovered” partially - collapsed copper liners

It is not yet clear what detailed deformation mechanisms enable copper shaped charge jets to exhibit the extraordinarily high ductility, which characterizes their dynamic behavior. The study described in this paper seeks to find some of these answers, by stopping the liner collapse process at various intermediate stages, and examining the grain structures in the partially collapsed liners.

Well characterized OFE copper shaped-charge liners, assembled into a cylindrical polycarbonate case, of constant length and volume, were partially collapsed, with reduced-weight cylindrical explosive charges. A series of increasing explosive charge weights were used to obtain progressively greater partial deformations on individual copper liners. The shock waves from the varying length explosive charges were coupled to the copper liners through intermediate water fill, which was in direct contact with the rear of the liners.

The series of partially collapsed copper liner was captured by “soft recovery” in low density polystyrene. Flash radiography prior to liner recovery, confirmed that the unexpected shapes of the recovered partially collapsed liners, actually existed prior to their entering the recovery medium and were not the result of the recovery process itself. This was an early concern when the unusual shapes of the recovered liners were first seen.

These shapes were also independently confirmed by a series of computations at Los Alamos National Laboratory, using MESA 2D.

A comparison of the photomicrographs of undeformed virgin copper liners andd the series of partially collapsed liners, shows regions on the inner apex near the liner axis where plastic flow has occured, with very substantial modifications (refinement and elongation in grain structure even for the small deformations which barely change the overall liner shape.

Time dependent strain and strain rate computations, using LaGrangean tracer markers, indicate very large strain rates, between 3×10⁷/sec. and 4.7×10⁷/sec. in those regions with plastic flow where grain refinement and elongation are seen, even with very small overall deformation.

It is believed likely that this early time material processing and grain refinement, arising from the localized plastic deformation of the liner, plays a key role in preparing the liner material structure, so that it can exhibit the high dynamic ductility, characteristic of copper shaped-charge jets.     

The penetration resistance of a titanium alloy against jets from tantalum shaped charge liners

Titanium alloys, notably Ti-6AL-4V, are known to provide high mass effectiveness against kinetic energy penetrators. However, the penetration effectiveness of titanium against shaped charge jets has not been investigated in detail. An experimental study was conducted with Ti-6Al-4V billets impacted by shaped charge jets formed from 100-mm, 42-degree conical shaped charge liners fabricated from tantalum. This work represents the first study of hypervelocity, high-density jet penetration into titanium alloys.     

Creation and simulation of very fast jets

We propose a concept in order to produce very fast metallic jets (which speed could exceed 20 km/s). It uses the detonation wave of an explosive cylinder to initiate a high compression on the rear face of a metallic target ; the jet is created on the front surface, in a cylindrical cavity. Many experiments were performed, in which we tested different metals and various geometries of cavity. Numerical calculations with PLEXUS (finite element 2D or 3D code) and CEL (finite difference 2D code) were used to understand the phenomenology of the creation and propagation of these jets ; the correlation with the experimental results (about the shape of the jets and their speed) is good.     

铜粉末药型罩试验研究

研究粉末罩的力学性能,对聚能装药的设计和应用具有重要意义。本文对两种不同孔隙度的铜粉末药型罩进行了试验研究,并与紫铜药型罩进行了比较。试验结果表明,在给定的试验条件下,粉末药型罩的穿深随孔隙度的增加而增加;两者分别在0.7～3.0和1.1～2.2倍口径的炸高范围内,粉末药型罩穿深要比紫铜射流的深;孔隙度为9.3%的粉末射流在14μs内侵彻速度与紫铜射流几乎没有差别,14μs后很快降低。     

铜粉末药型罩试验研究

研究粉末罩的力学性能,对聚能装药的设计和应用具有重要意义。本文对两种不同孔隙度的铜粉末药型罩进行了试验研究,并与紫铜药型罩进行了比较。试验结果表明,在给定的试验条件下,粉末药型罩的穿深随孔隙度的增加而增加;两者分别在0.7～3.0和1.1～2.2倍口径的炸高范围内,粉末药型罩穿深要比紫铜射流的深;孔隙度为9.3%的粉末射流在14μs内侵彻速度与紫铜射流几乎没有差别,14μs后很快降低。     

冷锻紫铜药型罩材料的织构研究

运用X射线衍射仪对两种铜药型罩材料进行了织构测量和分析,研究不同的加工工艺对铜药型罩材料的显微组织及织构的影响,结果表明,冷锻罩晶粒细小,具有均匀弱织构,各向同性好,而挤压罩织构较强,呈现明显的各向异性,两罩沿母线方向的各向异性程度均大于沿周向的,且罩底各向异性程度最大,罩底的织构沿周向挤压罩的差别大,冷锻罩的差别小;两罩罩体上下部分织构差别依次减弱,即挤压罩差别较大,冷锻罩底和罩顶织构相差最小。靶试结果表明,冷锻罩具有高的破甲性能。     

Bubbly Jet Impingement in Different Liquids

The impingement of bubbly jets in distilled water and ethanol has been experimentally studied on ground. An experimental apparatus for the study of jet impingement on ground and in microgravity has been designed. The opposed-jet configuration with changeable orientation is used in order to study which is the better disposition to achieve an efficient mixing process. The impact angle between jets that can be changed from 0° (frontal collision) up to 90° (perpendicular collision). The impinging jets are introduced into a test tank full of liquid by means of two bubble injectors. The bubble generation method, insensitive to gravity level for low Bond numbers, is based on the creation of a slug flow inside a T-junction of capillary tubes of 0.7 mm of diameter. Bubble velocities at the injector outlet and generation frequencies can be controlled by changing gas and liquid flow rates. Individual bubble properties and coalescence events, as well as the whole jet structure are analyzed from the images recorded by a high speed camera. Bubble velocities are compared with the velocity field of a single-phase jet. Rate of coalescence between bubbles is found higher in ethanol than in water, creating a higher dispersion in bubble sizes.     

Research Progress of Key Technology of High-Speed and High Precision Motorized Spindles

High speed machining and high precision machining are two tendencies of the manufacturing technology worldwide. The motorized spindle is the core component of the machine tools for achieving the high speed and high precise machining, which affects the general development level of the machine tools to a great extent. Progress of the key techniques is reviewed in this paper, in which the high speed and high precision spindle bearings, the dynamical and thermal characteristics of spindles, the design technique of the high frequency motors and the drivers, the anti-electromagnetic damage technique of the motors, and the machining and assembling technique are involved. Finally, tha development tendencies of the motorized spindles are presented.     

Modelling of the break up mechanism in gas atomization of liquid metals Part II. The gas flow model

An analytical model for the gas flow produced by a close coupled atomization assembly is described. The algorithm is based on physical arguments and it fully accounts for the expansion of compressible gas from cylindrical gas jets and the convergence/divergence of the subsequent turbulent flow. A critical input parameter of the model, the radius of the convergence area of the individual jet flows, established elsewhere [G. Antipas, PhD Thesis, University of Surrey, UK, 1995] to be 3 mm by high speed photography, is in tight agreement with the predictions of the model. Pitot tube gas velocity measurements compared well with model predictions.     

Design of CNG tank made of aluminium and reinforced plastic

A compressed natural gas storage tank suitable for gas operated vehicles can be made of thin-walled aluminium liners with a glass/epoxy reinforcement overwind. The hybrid construction allows the higher tensile strength of the glass reinforcement to be utilized, whilst giving a structure which weeps before burst and self-health. The advantages of the chosen construction can only be maximized for the optimal wall thickness and optimal stiffness of the composite shell after optimal prestressing of the tank. The purpose of the design task is to optimize the construction. This paper gives the methodology involved in achieving this using analytical techniques. The reliability of the design method together with the advantages of the chosen structural solution are proved by the manufacture and testing of prototype tanks.