微型计算机在复合材料强度准则研究中的应用

文中论述了运用微型计算机(IBM-PC)进行复合材料强度准则研究的方法,包括强度包络线绘制、双向加载数据采集及实验数据处理等,同时还研究了如何确定双向试验中的破坏载荷值,并在分析实例中提供了较详细的数据。     

穿甲子弹偏心入射陶瓷/钢复合靶板试验

设计并进行了7.62mm穿甲子弹侵彻陶瓷/低碳钢复合靶板的弹道试验,得到了极限速度及陶瓷锥底部半径等数据。分析了锥底半径与入射速度、面板及背板厚度的关系,着重分析了偏心入射时靶板的抗弹机理。结果表明:陶瓷锥可分为破碎区和粉碎区,粉碎区半径约为面板厚度与弹丸半径之和;当弹着点距离陶瓷面板边缘大于5mm时,靶板的抗弹性能变化不大,而弹着点位于距陶瓷面板边缘小于5mm的板边区时,抗弹性能明显降低,靶板的有效防护面积应扣除板边区。     

寻找无向图中全部生成树的复合支路和网络撕裂技术

将复合支路和网络撕裂技术用于寻找无向图中全部生成树的算法.给出复合支路的概念、表示方法和运算规则,以及由各个子图的全部生成树得到原图的全部生成树的方法.在图的分解和找树过程中,可以采用并行算法,从而降低了找树算法的复杂性.     

脆性材料中的裂纹对组合梁剪切件滑移的影响

组合梁的承载能力受多种因素的影响,工程中通常采用强度条件进行设计,这种方法的实质是假定剪切联接件具有无限大的滑移能力。实际上,剪切联接件的超量滑移会引起梁的破坏。假设组合梁由脆性材料和韧性材料组合而成,在考虑脆性材料产生拉伸裂纹的情况下,用等效刚度法计算了剪切件的滑移量,进而得出组合梁的极限弯矩。     

重力分离SHS陶瓷内衬复合管后期处理组织研究

研究了重力分离SHS法制备的陶瓷内衬复合管,在还原气氛下进行高温处理过程前后,复合管中陶瓷与钢管间的过渡层组织形态、组织分布的变化和过渡层中的裂纹的变化情况。指出:随着加热温度的升高、保温时间的延长,原子扩散能力加强,在过渡层界面上,以及陶瓷和钢管中出现新的化合相,能增强复合管的结合强度和力学性能,降低陶瓷的脆性。后期高温处理中,加热温度过高、保温时间过长,会造成组织粗化等缺陷,导致复合管性能变差。     

磁控溅射工艺对CrN基复合涂层微观结构及摩擦学性能的影响

采用闭合场非平衡磁控溅射技术在不锈钢基体上制备了不同质量分数Mo的CrMoN复合涂层。采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、能谱仪（EDX）和光电子能谱仪（XPS）,系统分析了CrMoN复合涂层的相结构、表面形貌、成分、原子化合价价态等,结果表明：添加Mo后,CrMoN涂层的择优取向由CrN涂层的（220）转变为（200）,CrMoN涂层中的Mo原子取代了CrN晶格中的Cr原子,形成（Cr,Mo）N置换固溶体。采用Nano Test 600硬度测试仪测定了CrMoN复合涂层的纳米硬度,结果表明：由于CrN相和MoN两种硬相的协同作用,使得CrMoN复合涂层的纳米硬度值增大。采用多功能摩擦磨损试验机测定了CrN涂层及CrMoN复合涂层的摩擦因数,结果表明：CrMoN复合涂层的摩擦因数低于CrN涂层,磨损过程中由于摩擦热反应生成大量MoO3,使得复合膜的摩擦因数降低,起到了一定的润滑效果,降低了磨损量。     

Fabrication and analysis of TIG welding-brazing butt joints of in-situ TiB2/7050 composite and TA2

Lightweight hybrid structures of Al MMCs and titanium alloy dissimilar materials have great prospect in the defence industry application. So, it is necessary to join Al MMCs with Ti metal to achieve this structural design. In this work, in-situ TiB2/7050 composite and TA2 were firstly attempted to join by TIG welding-brazing technique. The result was that the intact welding-brazing butt joint was successfully fabricated. The joint presents dual characteristics, being a brazing on TA2 side and a welding on TiB2/7050 side. At brazing joint side, ER4043 filler metal effectively wets on TA2 under TIG heating condition, and a continuous interfacial reaction layer with 1—3μm is formed at welded metal/TA2 interface. The whole interfacial reaction layers are composed of Ti(AlSi)3 intermetallic compounds (IMCs), but their morphologies at the different regions present obvious distinguishes. The microhardness of the reaction layers is as much as 141—190 HV. At welding joints side, the fusion zone appears the equixaed crystal structure, and the grain sizes are much smaller than those of welded metal, which is attributed to the effect of TiB2 particulates from the melted TiB2/7050 on acceleration formation and inhibiting growth for the new crystal nucleus. The tensile test results show that average tensile strength of the optimal welding-brazing joint is able to achieve 138 MPa. The failure of the tensile joint occurs by quasi-cleavage pattern, and the cracks initiate from the IMCs layer at the groove surface of TA2 and propagate into the welded metal.     

Influence of thickness and projectile shape on penetration resistance of the compliant composite

The present study deals with development of conceptual proof for jute rubber basedflexible composite block to completely arrest the projectile impacting the target at high velocity impact of 400 m/s through numerical simulation approach using finite element (FE) method. The proposed flexible composite blocks of repeating jute/rubber/jute (JRJ) units are modelled with varying thickness from 30 mm to 120 mm in increments of 30 mm and impacted by flat (F), ogival (O) and hemispherical (HS) shaped projectiles. All the considered projectiles are impacted with proposed flexible composite blocks of different thicknesses and the penetration behaviour of the projectile in each case is studied. The penetration depth of the projectile in case of partially penetrated cases are considered and the effect of thickness and projectile shape on percentage of penetration depth is statistically analyzed using Tagu-chi's design of experiments (DOE). Results reveal that the though proposedflexible composite block with thickness of 90 mm is just sufficient to arrest the complete penetration of the projectile, considering the safety issues, it is recommended to use theflexible composite with thickness of 120 mm. The nature of damage caused by the projectile in the flexible composite is also studied. Statistical studies show that thickness of the block plays a prominent role in determining the damage resistance of the flexible composite.     

Efficient budget allocation strategies for elementary effects method in stochastic simulation

This paper focuses on extending the Morris' elementary effects method (MM) for sensitivity analysis/factor screening originated in the context of deterministic computer experiments to the stochastic simulation setting. Given a fixed simulation budget to expend, the main objective is to provide efficient and accurate estimates of main and interaction (or nonlinear) effects coined by the standard MM for characterizing the importance of each factor, despite the impact of simulation errors. Taking into account both the factor/input sampling uncertainty rooted in MM and the random errors inherent in a stochastic simulation, we develop efficient budget allocation strategies for implementing MM in this new context. Under each strategy proposed, we derive its corresponding optimal budget partition and optimal budget allocation rules. Numerical results corroborate the practical effectiveness of the proposed budget allocation strategies.     

卫星中心承力筒结构优化设计研究

利用有限元软件ANSYS建立复合材料中心承力筒式卫星平台结构的参数化有限元分析模型,计算了整星结构振动模态,在此基础上对复合材料蜂窝夹层中心承力筒结构分析模型进行简化,在满足结构的强度、变形、振动和屈曲约束条件下,对承力筒结构进行优化设计,并对多种方案进行比较,提出的方法和思路为今后同类结构设计提供了参考。