复合材料高压气瓶的碳纤维缠绕设计和ANSYS分析技术

为了获得复合材料气瓶合理的有限元分析模型,并能够有效地掌握气瓶固有的变化规律,以不锈钢316L为内衬、碳纤维(T1000GB)/环氧树脂(BA202)为复合层的高压气瓶作为研究对象,介绍了一种采用螺旋缠绕与环向缠绕组合线型的缠绕设计方法.利用该方法确定复合层厚度、缠绕角、缠绕层数等参数,运用ANSYS程序,采用薄壁壳单元shell91建立了复合层多层结构模型,得出了气瓶应力、应变分布规律,并给出了气瓶疲劳破坏点和起裂点处失效参数的变化历程,最后,将ANSYS计算结果与试验实测结果作了比对分析,为定量化研究复合材料气瓶提供准确的数据支持.研究结果表明:ANSYS数值仿真结果与试验结果吻合良好,采用壳单元shell91可以比较正确地模拟复合层的多层结构;柱形复合材料气瓶破坏薄弱点位于简体(靠封头)部位,气瓶受环向膨胀力影响较大,易使其沿纵向撕裂;随瓶内压力升高,薄壁内衬发生完全塑性变形,复合层仅发生弹性变形.     

冲压发动机C/SiC喷管沉积特性研究

为了探索冲压发动机C/SiC复合材料喷管的沉积特性,从C/SiC喷管不同的型面结构、不同试验状态以及不同的燃烧室状态等方面进行了研究。研究表明:C/SiC复合材料喷管的型面结构对喷管固体颗粒的沉积影响较小,可以忽略;试验状态和燃烧室状态对C/SiC复合材料喷管固体颗粒的沉积影响较大,喷管不容易产生沉积;在高空状态、复合材料燃烧室状态下,喷管扩张段容易产生沉积,且当扩张段欠膨胀时,加剧沉积。      

导热增强型相变材料温控试验

为满足高超声速飞行器舱内温度要求,提出了在舵轴热短路区域使用相变材料进行热耗散的方案.通过开展导热增强型相变材料温控试验,获得了不同试验方案对舵轴及周围金属壳体的降温效果.结果表明,导热增强型相变材料由于良好的导热性能,能够很好地发挥相变吸热能力,对降低舵轴热短路区域的局部高温具有显著效果;金属壳体内、外同时使用低温和中温相变装置,能够将舵轴周围金属壳体温度控制在允许工作温度范围内(150℃).本研究可为飞行器舵轴温控设计提供指导.     

Ma4-6级别临近空间飞行器材料体系研究

介绍了Ma4～6级别临近空间飞行器飞机表面瞬态温度的计算方法及表面温度分布;阐述了热防护系统的分类及其特点;重点讨论了高马赫数临近空间飞行器对材料的使用要求,以及满足Ma4～6级别临近空间飞行器热防护要求的材料体系方案;提出高马赫数临近空间飞行器的热防护材料发展建议。     

Microstructure and mechanical properties of hybrid fabricated 1Cr12Ni2WMoVNb steel by laser melting deposition

 Laser melting deposition was carried out to deposit a 1Cr12Ni2WMoVNb steel bar on a wrought bar of same material. Room-temperature tensile properties of the hybrid fabricated 1Cr12Ni2WMoVNb steel sample were evaluated, and microstructure, fracture surface morphology, and hardness profile were analyzed by an optical microscope (OM), a scanning electron microscope (SEM), and a hardness tester. Results show that the hybrid fabricated 1Cr12Ni2WMoVNb steel sample consists of laser deposited zone, wrought substrate zone, and heat affected zone (HAZ) of the wrought substrate. The laser deposited zone has coarse columnar prior austenite grains and fine well-aligned dendritic structure, while the HAZ of the wrought substrate has equiaxed prior austenite grains which are notably finer than those in the wrought substrate zone. Besides, austenitic transformation mechanism of the HAZ of the wrought substrate is different from that of the laser deposited zone during the reheating period of the laser deposition, which determines the different prior austenite grain morphologies of the two zones. Microhardness values of both the laser deposited zone and the HAZ of the wrought substrate are higher than that of the wrought substrate zone. Tensile properties of the hybrid fabricated 1Cr12Ni2WMoVNb steel sample are comparable to those of the wrought bar, and fracture occurs in the wrought substrate zone during the tensile test.     

气体传感器的研究及发展方向

介绍了气体传感器的特性；根据气体传感器使用的气敏材料以及气敏材料与气体相互作用的效应不同，对气体传感器进行了分类；介绍了目前气敏元件的加工技术；论述了气体传感器的发展方向。     

Status and Perspectives in Protective Design

Starting with an introduction into the field of hypervelocity impacts, an overview over current research in the area of protection against space debris is given. Trends and strategies to further develop know-how in protection technology are then discussed. One purpose is to demonstrate that improvements in shield efficiency can be expected. To achieve this aim, a strategy is outlined which tries to avoid the adjustment of numerical and material parameters by fits to penetration experiments. Instead, it is suggested to determine material parameters from carefully selected laboratory tests, covering a broad range of strains, strain rates and stress states. Knowledge of the dynamic material behaviour can then be used for the development of new shield concepts by means of numerical simulation.     

固体发动机复合材料壳体的电子束固化

叙述了电子束固化技术在固体火箭发动机复合材料壳体工艺中的应用，讨论了该技术的优点和局限性，介绍了在航空航天其它领域内的推广情况。     

GMR硬盘磁头抛光的超声波作用机理

在硬盘磁头抛光中加入超声波,可以提高材料去除率、降低表面粗糙度值、减小极尖沉降。     

固定阴极电化学切割规律研究

在研究固定阴极扩孔、切割等加工的成型规律时，通常将极间电场简化为平行平面场。然而当阴极宽度不能远远大于极间间隙时，采用这种处理方式将产生很大的误差。根据电磁场理论，文中提出了一种研究固定阴极电化学切割规律的更为严密的处理方法，并且基于这一思路分析了用该加工方式在阳极被加工面上某处电场强度、电流密度、加工速度等在加工过程中的变化规律，建立了基本能反映加工实际过程的一般数学模型。根据所建的数学模型对一