基于钽球缺药型罩的多模式毁伤元成型规律

为研究钽球缺药型罩毁伤元成型规律,通过爆轰波碰撞理论和马赫高度计算模型分析了起爆半径对毁伤元成型的马赫超压和马赫高度的影响;利用LS-DYNA有限元程序研究了钽球缺药型罩结构参数(内曲率半径、外曲率半径、罩壁厚)对毁伤元成型的影响。结果表明,中心单点起爆可以形成EFP,环起爆半径为0.8倍装药半径可形成杆式EFP;毁伤元速度和密实度与药型罩内曲率半径呈正相关,与药型罩外曲率半径和药型罩壁厚呈负相关,毁伤元长径比与药型罩内外曲率半径以及壁厚呈负相关;在药型罩内曲率半径R1和外曲率半径R2关系为1.04相似文献   

环形EFP的形成和侵彻效应

设计了两种可形成环形弹丸的装药结构--环锥形和环球形EFP.通过数值模拟和破甲试验,对环形弹丸的形成和侵彻靶板的特点进行了研究.结果表明,通过使药型罩由中心向外翻转,两种方案都可在0.5～2.0倍炸高范围内形成环形弹丸,侵彻孔径可达1倍装药口径,穿深可达0.3倍装药口径.相对于环锥形EFP,环球形EFP产生的环形弹丸更完整,稳定时间更长,侵彻靶板的效果更好.与普通EFP和环形射流相比,虽然环形EFP的穿深小,但开孔孔径很大,这为串联战斗部的前级装药设计提供了一种新的技术途径.     

变壁厚双层药型罩壁厚匹配的数值计算与实验验证

参考变壁厚药型罩和双层药型罩的结构优点,根据能量利用的观点提出了一种新型变壁厚双层药型罩,采用正交实验及AUTODYN有限元软件对药型罩的结构参数进行优化并通过试验进行了验证。数值计算结果表明,在同等装药量下,由变壁厚双层药型罩形成的侵彻体的性能要优于由变壁厚药型罩或双层药型罩形成的侵彻体的性能。与常用的等壁厚单层药型罩相比,射流头部速度增大559m/s,射流质量基本不变,铜的利用率提高了19.1%。由变壁厚双层药型罩形成的侵彻体可以提高战斗部的侵彻能力,同时也有利于节约昂贵的金属材料。     

药型罩参数对周向MEFP成型的影响

采用ANSYS/LSDYNA有限元软件数值模拟研究了药型罩参数对周向MEFP成型的影响.通过对成型后的集群EFP性能统计分析,得到药型罩曲率半径、壁厚和口径对周向MEFP成型性能的影响规律和参数之间的合理匹配关系.结果表明,在爆炸载荷作用下,周向MEFP装药形成的中间层EFP速度明显大于边缘上下层EFP速度;而且当药型...     

基于爆炸成型弹丸(EFP)的大锥角喇叭罩成型规律

为了进一步拓展适用于爆炸成型弹丸(EFP)的药型罩结构,基于弧锥结合罩结构,提出了一种可形成密实EFP的大锥角喇叭罩。根据药型罩结构特点,分析了大锥角喇叭罩与传统弧锥结合罩和球缺罩在压垮过程中的区别和特点;运用LS-DYNA数值模拟软件,计算得到了大锥角喇叭罩的结构参数(虚拟罩高、喇叭曲率半径、圆弧曲率半径和罩厚)对EFP侵彻体速度、长度、密实度等成型参数的影响规律。结果表明,大锥角喇叭罩罩厚对侵彻体的影响主要体现在头部速度,虚拟罩高和圆弧曲率半径则决定了侵彻体长度及密实度,而喇叭曲率半径则主要影响侵彻体头部的成型状态;与传统弧锥结合罩和球缺罩形成的EFP相比,相同质量的大锥角喇叭罩形成的EFP在头部速度、长度、长径比及密实度等方面均具有一定优势,可将侵彻体密实度提高1～3.5倍,具有应用于EFP战斗部的潜力;其适用于较佳EFP成型时各结构参数的取值范围为:虚拟罩高0.14～0.16倍装药直径,喇叭曲率半径1.5倍装药直径以上,圆弧曲率半径0.4～0.8倍装药直径,罩厚0.04～0.045倍装药直径。     

变壁厚石油射孔弹聚能射流形成的影响因素分析

为研究药型罩锥角、壁厚等对石油射孔弹聚能装药引爆形成的聚能射流影响,利用有限元分析软件ANSYS/LS-DYNA,采用ALE方法对变壁厚石油射孔弹聚能射流的形成过程进行了模拟分析,得出型罩结构与射流头部速度的关系。研究结果表明,药型罩锥角越大,射流速度越小,形成的杵体长度相比于射流的长度也越小;同锥角药型罩壁厚越小,聚能射流的形态发育得越好,药型罩壁厚越大,射流速度越低。     

爆炸成型PELE形成影响因素的数值模拟研究

为研究爆炸成型横向效应增强型侵彻体(爆炸成型PELE)的形成规律,基于一种中心点起爆的包覆式复合药型罩战斗部结构,采用AUTODYN数值模拟软件计算爆炸成型PELE形成过程;运用图像处理技术,提取侵彻体形成后的边界并计算出密实度作为衡量侵彻体形成优劣的评价依据,获得了药型罩材料、结构以及装药长径比对爆炸成型PELE形成性能的影响规律。结果表明,在中心点起爆条件下,采用变壁厚结构铁外罩、等壁厚结构铝内罩组合方式,内外罩顶厚度比为2∶3、装药长径比为0.5时,可获得密实度较高的爆炸成型PELE,其结构参数为:外罩内、外曲率半径分别为1.00D和1.15D,外罩顶厚度为0.06D,内罩内、外曲率半径均为0.42D,内罩顶厚度为0.04D。     

线形EFP药型罩设计

为提高多EFP战斗部单位面积上的弹丸个数,提出了一种新型EFP--线形EFP,并探索了新型EFP药型罩的设计方法和毁伤效应.参考常规EFP药型罩设计方法,设计了不同形状和不同材料的线形EFP药型罩,并通过数值仿真和试验比较了线形EFP药型罩顶点厚度、形状和材料以及相邻两条预控刻槽间的圆心角对线形EFP成行性和穿甲能力的影响.结果表明,将线形EFP药型罩用于多EFP战斗部可使防空反导型战斗部对钢板的侵彻能力提高到25mm.     

串联侵彻战斗部前级装药设计及试验研究

为了提高前级聚能装药对钢筋混凝土目标的侵彻威力,增加预损伤的穿孔孔径大小和深度,满足后级弹丸侵入目标内部爆炸的需求,提出了3种前级装药杆式聚能侵彻体设计方案.采用三维程序ANSYS/LS-DYNA3D 计算了3种药型罩形状、铜和铝两种罩材料、装药不同起爆方式等条件变化对前级聚能侵彻体形成的影响,选出了变壁厚球缺罩和K型...     

环形EFP成型及侵彻过程的数值模拟

在分析环形射流形成机理的基础上,利用LS-DYNA软件对环形EFP的成型与侵彻过程进行了数值模拟.通过对环形药型罩及其聚能装药结构参数的合理匹配,解决了环形药型罩成型翻转过程中的偏斜飞散问题,探索了实用环形EFP工程设计的技术途径.计算结果表明,在0.26倍装药长径比和4倍装药口径的炸高条件下,环形EFP对45号钢的侵彻孔径可达到0.96倍装药口径.     

10号钢和紫铜EFP侵彻性能的数值模拟及实验研究

对10号钢和紫铜材料EFP侵彻对50mm厚603均质装甲靶板的性能进行了研究。应用ANSYS/LS-DYNA软件对两种EFP的成型和侵彻靶板过程进行了数值模拟,分析了两种EFP侵彻性能差异存在的内在原因。结果表明,10号钢EFP的穿深能力小于紫铜EFP,而扩孔能力较为显著,其靶板入口尺寸约为紫铜EFP的1.5倍。认为侵彻性能的差别由材料特性、EFP形状和速度分布引起,而靶板入口大小由尾翼大小决定。     

Research on Feasibility of Several High Density Materials for EFP Liner and Material Selection Criteria

In order to find new kinds of EFP liner materials with high density, W alloys, Ni, Mo, U, and U alloy were selected to be tested. Both liner test and flyer plate test were carried out in experiment, with existing EFP liner materials being testified as reference. It turned out that among the selected materials only Ni was suitable for EFP liner material, other potential candidates fractured to different extent in experiment. The potential reasons of materials’ fracturing under explosive loading were analyzed through different scales in fracture mechanics. Characteristics of a feasible candidate material for EFP liner were discussed through fracture toughness K _IC, impact toughness α _k, damage tolerance d _y, and microstructure mechanics analysis. Finally material selection criteria of EFP liner were presented. The research results are significant in the material selection of EFP liner especially within high density materials, and it can be important guidelines for the researchers to avoid the blindness in research investments and waste in experiments in EFP research field.     

Mach Wave Control in Explosively Formed Projectile Warhead

A Mach wave emerges at the top of the liner when a wave shaper is embedded in charge, and thus seriously breaks the explosively formed projectile (EFP) nose. Thus, to avoid breakage at the EFP nose, the pressure behind the Mach wave should be controlled. An analytical model for calculating Mach wave parameters is presented based on three‐shock theory. The parameters of Mach waves, such as their growth angles and radii, their velocity along the plane of symmetry, and the pressure behind them, can be determined. Calculation results show that when the diameter of the wave shaper is reduced or the distance between the wave shaper and liner increases, the incident angle of the detonation wave at the top of the liner increases and thereby lowers the pressure behind the Mach wave. Avoiding the occurrence of Mach waves by reducing the incident angle fails to avoid breakage at the nose of the EFP, but lowering the pressure behind the Mach wave by increasing the incident angle avoids breakage at the nose of the EFP. Calculation and simulation results are validated through X‐ray imaging experimentation.     

新型多线形爆炸成型弹丸战斗部的弹丸成型及毁伤研究

为了简化工艺并提高线形爆炸成型弹丸(LEFP)的成型质量和毁伤威力,设计了一种中心起爆的新型多线形爆炸成型弹丸(MLEFP)战斗部,药型罩具有弧顶厚度小于边缘厚度的特点.通过数值模拟方法计算了弹丸的成型及飞散效应,并对药型罩进行了优化.设计了后翻转形成密实弹丸的战斗部原理样机并进行了静爆实验.模拟结果表明,在中心起爆方式下,药型罩弧顶厚度大于边缘厚度时,药型罩易前翻转形成弹丸;药型罩弧顶厚度小于边缘厚度时,药型罩易后翻转形成密实弹丸.铁材料药型罩的成型效果优于铜材料.静爆试验结果表明,MLEFP战斗部形成的弹丸可贯穿离爆炸中心2.5m处的30mm厚的45号钢板.     

Design,manufacture, and test of lightweight composite sandwich helmets

Abstract

This paper summarises work undertaken on the design, manufacturing development, and impact testing of a lightweight composite aircrew helmet. Full details are given on the double diaphragm forming process, developed at DERA, which has been extensively used to manufacture the complex, doubly curved layers that form the final helmet assembly. Manufacturing options for the development of a ‘form fitting’ foam liner are also included, as are developments in the foam liner press moulding processes.

Results from an extensive impact test programme conducted on fully assembled shell samples are provided, illustrating good energy management during test. Some redundant material was apparent from the results, hence further mass reduction is possible. Modification of the layer deformation sequence is also required. However the sandwich shells met all impact test requirements. Correlation of the impact test data and helmet damage cross- sections has allowed recommendations to be made regarding improved design and manufacture of the layered construction. Predictions based on these improvements show the final helmet mass should be ～750 g, excluding breathing systems and communications.     

Preparation of Mono-Dispersed Polyurea-Urea Formaldehyde Double Layered Microcapsules

A new method to prepare a kind of double layered microcapsules was developed. Polyurea (PU) microcapsules were firstly fabricated by interfacial polymerization as inner layer, on which urea-formaldehyde (UF) resin was coated to form a protective outer layer by in-situ polymerization. Environmental scanning electron microscope, optical image analyzer, Fourier transform infrared spectrophotometer and thermo gravimetric analysis were employed to investigate their characteristics for the morphologies, particle size, materials structures and thermal properties. The prepared double layered PU-UF microcapsules are mono-dispersed with ultra-thick capsule wall and improved thermal stability.