大装填比弹侵彻钢筋混凝土实验研究

设计了一种薄壁弹体,采用YOUNG方程预估该弹体侵彻混凝土靶板的侵彻深度,采用SAMPLL程序预估轴向过载.运用LS-DYNA软件分析弹体的侵彻过程,对材料力学性能进行实验研究.通过在φ130 mm气炮上的一系列弹体侵彻钢筋混凝土靶实验,考核了弹体的结构强度和侵彻深度.结果表明:弹体在低速侵彻钢筋混凝土靶板时结构不会发生破坏,300 m/s速度下具备侵彻贯穿600 mm钢筋混凝土层的能力.     

钢管收口代替方钢热冲拔弹体毛坯加工工艺研究

重点介绍了炮弹新产品弹体毛坯由钢管收口代替传统的方钢热冲拔加工工艺,弹体一次收口工艺研究过程。确定的弹体生产工艺,工艺过程简单,产品质量得到大幅度提高,改善了工作环境,降低了劳动强度,在同行业处于领先水平,并为新型薄壁弹种的研发奠定了工艺基础。     

某薄壁壳体收带工艺改进

分析了弹体收带工艺产生的变形问题,理论计算弹带收带所需挤压力,确定收带弹体变形产生的原因,通过改进收带工艺和夹爪结构、优化调整收带芯子与弹体内膛配合间隙,减少了薄壁弹体收带变形,降低了收带废品率,保证了薄壁弹体收带质量,节约了生产成本.     

弹体毛坯热冲拔工艺

目的设计弹体毛坯热冲拔成形工艺方案。方法将冲子压入加热后的钢坯,使钢坯在压力作用下充满模腔,压成盂形,然后套在引伸冲子通过一串直径逐渐缩小的模圈,使弹体拉长、直径减小、壁厚减薄,获得合理的弹体毛坯尺寸,生产出合格毛坯。分析弹体毛坯冲拔成形原理、温度控制、工装设计及冲拔过程中的金属流动规律,根据体积不变原理,计算出冲拔毛坯尺寸。结果通过批量试制,根据冲拔过程中常见问题的控制措施,优化了冲拔工艺参数,实现了弹体毛坯热冲拔成形。结论通过冲拔原理分析、毛坯及工装设计,形成了热冲拔设计规范,该弹体毛坯热冲拔工艺可行。     

压模壁厚与压爆事故

在传爆药柱或弹体药柱的压制过程中,由于压模壁太厚而引起爆炸的事故不是偶然的。本文从理论和实际的角度分析了壁厚引起爆炸的原因,继而提出了较合理的压模壁厚度。     

偏转式抗侵彻防护技术研究现状

随着弹体侵彻能力不断提升，传统“阻挡”的防护设计思想指导下的防护结构为达到防御目标，其质量与尺寸必将不断提高。基于弹体非理想侵彻及侵彻非均匀防护结构中的弹体偏转现象而提出的“偏转”防护思想，使得更加轻质高效的防护结构成为可能。本文以弹体侵彻过程中的各种偏转现象为主要研究对象，综述了偏转式抗侵彻防护技术的研究现状，主要内容包括弹体非理想侵彻过程和弹体侵彻非均匀防护结构过程中的偏转现象，非理想侵彻的过程分析以及影响弹体非理想侵彻过程中偏转程度的主要因素，非均质防护结构偏转弹体的机制，介绍了目前实际应用中较为典型的三种偏转式防护结构形式，并分析了其抗侵彻性能和存在的不足，最后针对目前偏转式抗侵彻防护技术研究现状提出了建议，为高效能偏转式防护结构研究提供参考依据与思路。     

半球头长杆弹高速侵彻半无限厚靶临界速度理论模型

高速/超高速侵彻问题一直是武器设计者和防护工程专家关注的焦点问题之一。随着撞击速度的提高,弹体由刚体侵彻转入变形、流体侵彻状态,进而导致侵彻深度不再随速度呈单一上升趋势。为预测大着速范围下弹体的侵彻状态,基于弹体质量守恒、动量守恒及弹体动态强度计算方法,建立了弹体侵彻过程中的动力学平衡方程,进而确定高速侵彻临界速度。在与已有实验结果对比验证的基础上,分析了不同弹靶参数对侵彻临界速度的影响规律。结果表明:随着弹体静态屈服强度增大,弹体的变形长度减小,弹体的临界侵彻速度增大;弹靶塑性波波速等参数对高速侵彻状态临界速度也有显著影响。     

聚合物基熔铸炸药螺旋立式挤注过程的流场仿真研究

针对当前聚合物基熔铸炸药装药工序中的人机面对、手工作业问题，拟采用立式螺压工艺来实现药浆的连续挤注以及弹体的自动装药，故在表征药浆流变特性的基础上对其流场特征参数进行仿真分析。结果表明:液相载体的润滑作用以及剪切过程中固相颗粒的取向排列均会导致药浆表观黏度的下降。提高螺杆转速可以显著增大药浆的流动性及产能，但也会造成剪切速率的线性递增以及压力的阶梯状递增。同时，剧烈的剪切作用也会拓宽药浆的温度分布范围，并将最高温度提高18.6 ℃；需要借助芯部调温来削弱螺杆的剪切升温效应，确保工艺安全性。     

舰员抗冲击地砖动力学分析

抗冲击地砖具有超弹性大孔隙率蜂窝薄壁结构。建立抗冲击地砖的周期性薄壁结构单胞模型，进行冲击响应分析。结果表明，抗冲击地砖在压缩过程中具有明显的应变平台期，能够在一定载荷范围内提供足够的支撑刚度；在载荷强度达到一定值时，该结构能够被迅速压溃，产生瞬态大变形而吸收冲击能量。因此，抗冲击地砖是一种理想的舰员冲击防护手段。     

高强度薄壁筒水压试验分析

高强度薄壁筒水压试验分析柳州市长虹机器制造公司梁兴国通过对１￣＃、２￣＃高强度薄壁筒水压试验爆裂的断口进行金相、扫描电镜和性能检测分析，查明了１￣＃筒产生低应力爆裂的原因；在计算内压引起的应力时，应用了公式σ＝ＰＤ／２ｔ￣［３，４］和第四强度理论：Ｐ...     

弹壳开裂失效分析

对某型H68黄铜弹壳进行检查时发现大量弹壳存在裂纹。通过对弹壳进行宏观和微观观察、能谱分析、金相检验和残余应力测定等,分析了弹壳开裂的原因。结果表明:弹壳的开裂性质为应力腐蚀开裂,其原因是由于收口位置存在一定的残余拉应力,且该位置的晶粒尺寸较大,在外界介质的协同作用下产生了应力腐蚀裂纹。     

Physical and mechanical properties of YBa2Cu3O7-δ superconductors

The physical and mechanical properties of YBa₂Cu₃O_7–° superconductors are examined. These properties are related to powder preparation method, powder characteristics, sintering behaviour and sintered microstructure. The sintering atmosphere and sintering schedules affect the final microstructure very strongly and determine, in conjunction with starting powder characteristics, the sintered density. The mechanical properties such as Young's modulus, bend strength and critical stress intensity factor (fracture toughness) are measured and related to microstructure as determined by electron microscopy. Control of microstructure by careful powder selection and sintering schedule is seen as key to optimizing the physical and mechanical properties of the material. Finally attention is drawn to fabrication techniques and how these must be optimized in order to realize the mechanical properties which are necessary if these are to be useful as engineering materials. Comparisons between fabrication techniques show that uniaxial powder pressing suffers from limitations in terms of specimen complexity and densification whereas the favoured route, termed viscous processing, gives a more homogeneous microstructure, higher strength and allows near theoretical density to be achieved.     

The effect of pore size and heat treatment on the fracture toughness of pressed and sintered Ancoloy SA powdered steel

Ancoloy SA powder, adjusted by addition of carbon to give a composition which was slightly hypo-eutectoid, was tested in a pressed and sintered condition. Porosity was varied by changing the pressing pressure and structure was varied by heat treatment. The effect of pressing pressure, through void content and shape, dominated the toughness change, although heat treatment produced a large increase in yield stress.     

Anisotropy in Powder Compaction: Methods for Analysis and Testing

The issue of anisotropy in plastic flow of compacted metal powders is addressed using a combination of analytical and experimental methods. A yield function, based on the first two stress invariants and associative plastic flow, is modified for anisotropy by introducing coefficients on the stress terms. The test method uses die-compacted cylinders that are pressed into metal sleeves positioned inside a rigid die. When the sleeves and specimens are removed from the die, subsequent axial pressing causes pressure to be transmitted through the powder onto the inner surface of the sleeve. Yield of the sleeve sets the value of radial stress, and punch load sets the value of axial stress, at yield of the powder compact.     

Anisotropy in Powder Compaction: Methods for Analysis and Testing

The issue of anisotropy in plastic flow of compacted metal powders is addressed using a combination of analytical and experimental methods. A yield function, based on the first two stress invariants and associative plastic flow, is modified for anisotropy by introducing coefficients on the stress terms. The test method uses die-compacted cylinders that are pressed into metal sleeves positioned inside a rigid die. When the sleeves and specimens are removed from the die, subsequent axial pressing causes pressure to be transmitted through the powder onto the inner surface of the sleeve. Yield of the sleeve sets the value of radial stress, and punch load sets the value of axial stress, at yield of the powder compact.     

Effect of glass container encapsulation on deformation and densification behavior of metal powders during hot isostatic pressing

Hot isostatic pressing process consolidates metal powders to produce fully dense parts with complex geometries. Deformation behavior of compacts during hot isostatic pressing process typically is anisotropic for powders encapsulated in metal containers. Therefore, post-processing processes are required to fabricate the parts with required shape and dimension. This paper reports the effect of glass container encapsulation on deformation and densification behavior of 316 L stainless steel powder and nickel-based superalloy powder during hot isostatic pressing. Finite element calculations from Abaqus – finite element analysis (FEA) were compared with measured deformed shapes of powder compacts. Finally, samples deformed in glass containers were compared with those in metal containers to study the capabilities of glass containers to form near-net-shape parts. Glass containers transmitted all the pressure applied to the compacts and did not induce the Mises stress to the compacts that leads to homogeneous distribution of relative density over the compacts. Glass containers showed more homogeneous densification and uniform deformation of compacts compared to the conventional metal containers.     

一种新型滑板材料的研制及性能研究

采用粉末冶金／挤压的方法制作了一种新型的Cu-C滑动集电材料，对该材料的机械性能进行了检测，结果证明该材料具有较高的抗拉强度，适中的表面硬度，较低的电阻率，是一种较为优良的电力机车滑板材料。将其性能测试民铁标要求对比，优于铁标的要求。     

Influence of the P/M process on the microstructure and properties of WC reinforced copper matrix composite

The influence of powder metallurgy pressing procedure on 9%WC reinforced copper matrix composite was investigated, and the fracture surfaces of the composite in different states of process were observed by scanning electron microscope. The mechanism of fracture of the composite was analyzed. The results show that the pressing process apparently influences the properties and microstructure of the composite. The properties improved with processing sequence progression and the microstructure in terms of the distribution of WC particles in the composite became more uniform. The pressing process can improve the bonding at the interface between copper and WC particles and increases the critical stress for crack extension.     

NET SHAPE MANUFACTURING - THE UTILITY OF POWDER METALLURGY PROCESSING

Powder metallurgy is a source of new and viable near or net shape manufacturing processes, with compelling economic and technical advantages over conventional ingot metallurgy practice. Selected commercial methods are considered, namely pressing and sintering, injection molding, powder preform working and direct powder consolidation. Particular attention is directed to the prevailing state of stress, temperature and time in each mode, since these dictate densification mechanism(s), and hence microstructure and properties.     

Application of the powder of porous titanium carbide ceramics to a reusable adsorbent for environmental pollutants

The aim of this study is to investigate the utilization of the powder of porous titanium carbide (TiC) ceramics as a novel adsorbent or a material for solid-phase extraction (SPE). The adsorption and elution of inorganic and organic pollutants, Pb(II), 2,4,6-trichlorophenol (TCP), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA), to the material were evaluated. The cartridge packed with TiC ceramics powder was used for the extraction test of pollutants. The solution containing pollutants at 1.0 μg mL(-1) was passed through the TiC cartridge, and the substances were almost quantitatively removed. Furthermore, the pollutants retained in the cartridge were eluted with 3N HCl for Pb(II) and with methanol for organic pollutants. The recoveries of pollutants were over 80%. In addition, we used the TiC cartridge for the solid-phase extraction of water samples (500 mL each of the distilled water and the river water) by adding pollutants at determined concentrations. Every pollutant was adsorbed almost quantitatively, and eluted by 3N HCl or methanol. From these results, we concluded that the powder of porous TiC ceramics is a useful reusable adsorbent for the water cleanup and solid-phase extraction.