线型聚能装药射流形成及侵彻钢板的数值模拟

利用LS-DYNA对线型聚能装药射流的形成和侵彻钢板的过程进行了数值模拟,通过其结果与现有实验结果进行对比表明LS-DYNA程序可用于线型聚能装药的优化设计。     

不同材料模型的药型罩对仿真结果的影响

应用ANSYS/LS-DYNA的聚能装药侵彻仿真时,药型罩材料模型的选择有多种,对仿真结果之间的差别进行了比较.在炸药、药型罩结构等条件相同的情况下,选择Johnson-Cook与Steinberg两种材料模型,利用ANSYS/LS-DYNA软件对聚能射流侵彻靶板进行仿真.对比仿真结果,得出两种模型都能很好地模拟射流的形成及侵彻过程,且各时刻射流头部最高速度差值很小.     

不同材料模型药型罩数值仿真结果对比

应用ANSYS/LS-DYNA的聚能装药侵彻仿真时,药型罩材料模型的选择有多种,对仿真结果之间的差别进行了比较。在炸药、药型罩结构等条件相同的情况下,选择Johnson-Cook与Steinberg两种材料模型,利用ANSYS/LS-DYNA软件对聚能射流侵彻靶板进行仿真。对比仿真结果,得出两种模型都能很好地模拟射流的形成及侵彻过程,且各时刻射流头部最高速度差值很小。     

药型罩对聚能射流速度影响的数值模拟分析

为了研究药型罩对聚能射流破甲威力的影响,利用LS-DYNA动力有限元计算程序对聚能射流形成过程进行了数值模拟.在此基础上着重应用数值模拟方法分析了药型罩锥角、药型罩壁厚、药型罩形状对聚能射流速度的影响,得到了射流速度与药型罩的关系,射流速度随药型罩锥角的减小而增加,随药型罩壁厚的增加而降低,喇叭形罩比圆锥罩速度大.从而为聚能射流药型罩的设计提供参考.     

基于LS-DYNA 3D的聚能装药数值模拟规律验证与检验

针对当前广泛应用的商用数值模拟软件LS-DYNA 3D,开展了聚能装药射流成型与侵彻数值模拟结果可信度研究,对美国BRL-82基准弹进行数值模拟规律验证.结果表明：对轴对称聚能装药结构,药型罩壁厚网格数δ=4,对应装药、射流成型及侵彻通道的关键区域网格单元划分0.25 mm;射流成型采用多物质全Euler算法,侵彻采用多物质流固耦合算法,计算结果可信度较高.此外,铜药型罩材料本构模型选为Steinberg或Johnson-Cook时,对射流成型及侵彻计算结果可信度影响较小.设计了直径为56 mm的聚能装药,基于上述验证规律对其射流成型及侵彻进行数值模拟,通过脉冲X光和静破甲实验对该结果可信度进行了检验.     

基于FEM/SPH算法的管壁效应对聚能射流影响的数值模拟

基于LS-DYNA 3D软件,应用SPH/FEM算法对聚能射流侵彻不同内径管状装甲的过程进行数值模拟。研究发现金属射流穿过装甲管时,部分射流粒子从主体逃逸;逃逸粒子飞溅至管壁后在管壁效应作用下,粒子向心反弹或沿管壁做向心运动,对后续射流产生持续干扰,使其失稳和断裂降低侵彻能力。对比同等厚度及间隙的双层靶板,发现管状装甲对射流的干扰明显优于间隙靶板。对比不同管径情况下逃逸粒子的飞散现象,射流的剩余动能及对后效靶的剩余穿深。结果表明:当管径在10~20 mm范围内时,装甲管对聚能射流的干扰能力逐渐增强;在20~30 mm范围内时,装甲管对聚能射流的干扰能力逐渐减弱,管径为20 mm时装甲管对聚能射流的干扰能力最强。得出的规律可以为管状装甲的优化和设计提供一定的参考。     

铝-金属玻璃-铝复合板的抗破甲性能研究

利用爆炸焊接技术成功制备出铝-金属玻璃-铝三层复合板, 并对其抗破甲性能进行了试验及数值分析。针对复合板的尺寸较小的特点, 建立了适用于小试件( 特征尺寸小于 50 mm) 的破甲实验方案;基于动力学软件ANSYS/ LS-DYNA 提出了一套对破甲过程进行数值模拟的计算方案。研究结果表明, 破甲试验装置产生的聚能射流直径较小、稳定性良好, 铝-金属玻璃-铝三层复合板在聚能射流作用下其上表面呈大范围的花瓣形破坏, 中间层的金属玻璃材料呈粉末状破碎, 对后续的射流过程起到了干扰的作用; 计算方案可有效地模拟聚能射流的形成及其对铝-金属玻璃-铝三层复合板的侵彻; 数值模拟得到的破甲深度、稳定阶段侵彻通道的直径、材料的破坏模式与实验结果相符。     

线型聚能装药射流形成过程的数值模拟

聚能射流形式过程的研究对于正确认识射流侵彻理论具有重要的意义。根据线型聚能药的结构特点,利用DYNA3D显式有限元程序对线型聚能射流的形成过程进行了数值模拟。模型探讨了线型聚能装药爆炸的诸多重要物理特性,如药型罩的压垮、射流形成和拉伸以及体杵体的“体缩”现象。还分析了线型聚能射流形成过程中速度、密度、温度等参数的分布特性,得出了射流有逆向速度梯度和杵体存在“体缩”现象听结论,其结果与现有的理论分成果基本一致。     

命中位置对引爆重型爆炸反应装甲影响数值模拟

主要针对聚能战斗部引爆重型爆炸反应装甲问题开展研究,采用前处理软件TrueGrid建立了聚能射流引爆重型反应装甲数值计算模型,并采用非线性动力学软件LS-DYNA对该问题进行了数值模拟研究,使用后处理软件LS-prepost获得了不同命中位置对爆炸反应装甲引爆特性和飞散特性的影响特性.结果表明,命中位置对反应装甲引爆和飞散行为影响显著.命中位置越靠近反应装甲边缘,夹层装药起爆后的爆轰波峰值压力越低;飞板越晚开始飞散运动,加速时间越短;飞板飞散速度越小,对射流的干扰持续时间越长.      

新型环形聚能射流形成机理研究

为了解决环形聚能射流稳定性差、速度低等缺点,提出了一种新型环形聚能装药结构,基于正交优化方法,采用Autodyn软件对新型环形聚能装药结构进行了优化设计,给出了药型罩壁厚、药型罩曲率半径、聚焦装置锥角、喷孔直径及壳体厚度对射流头部轴向及径向速度的影响,优化出了径向偏转速度低的新型环形聚能射流,并进行了实验验证,实验结果与数值模拟结果基本一致.数值模拟及实验结果均表明,文中提出的新型环形聚能装药结构能够形成环形破孔,在钢靶上破孔直径107 mm,深度28 mm.      

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that