用奇异有限元法计算正交各向异性复合材料平面断裂的应力强度因子

将复合材料平板视为正交各向异性平板，把正交各向异性平板裂纹顶点附近的位移展开式迭加在一般的等参数单元上，建立了用于复合材料平板应力强度因子计算的奇异元。并以所做出的公式，对正交各向异性板含单边裂纹和双边裂纹问题进行了计算分析，取得了较好的效果。     

高变形率低密度碳／碳复合材料的研究

介绍了一种平均压缩率达到１０％，平均压缩回弹率达到１３％的低密度碳／碳材料及其独特的制造技术，对改善碳／碳材料的韧性提供了一种行之有效的方法。其主要工艺途径为，在水中以表面活性剂分散、包覆原材料、混合抽滤、烘干固化、炭化等工序。     

复合材料平板复杂应力试验的试样研究

用解析法、有限单元法对在双向载荷下平板试样的均匀应力区范围进行了计算分析,并用光弹实验进行了检验.利用双向加载试验机对单向复合材料板式试样施加不同比例的双向载荷,进行了应变分布测试,结果表明,130mm×130mm的板样在各种载荷比下,其均匀应力区范围不小于30mm×30mm.在此基础上设计了用于双向拉伸的平板试样.     

Analytical solution methods for eigenbuckling of symmetric cross-ply composite laminates

Based on the first-order shear deformation theory, this paper explores the analytical methods for eigenbuckling of symmetric cross-ply rectangular composite laminates with a pair of parallel edges simply supported and the remaining two edges arbitrarily constrained. The main con-tribution of present paper lies in two aspects: one is to present a simple and effective analytical method, namely, the separation-of-variables method, which can generate the closed-form buckling solutions without any computational difficulty;the other is to incorporate the accurate computation method of exponential matrix into the state space technique to avoid the inevitable numerically ill-conditioned problems reported in several literatures. The results obtained via both analytical meth-ods are identical, and a good agreement with their counterparts in literature is observed. The separation-of-variables method can generate exact solutions within 1 s, which is impossible if the state space method is employed. Besides, the combination of the accurate computation method of exponential matrix and the state space method greatly improves the computational efficiency and gives correct results compared with the straightforward use of state space method.     

Static strength analysis of dragonfly inspired wings for biomimetic micro aerial vehicles

This article examines the suitability of fabricating artificial, dragonfly-like, wing frames from materials that are commonly used in unmanned aircraft(balsa wood, black graphite carbon fiber and red prepreg fiberglass). Wing frames made with Type 321 stainless steel are also examined for comparison. The purpose of these wings is for future use in biomimetic micro aerial vehicles(BMAV). BMAV are a new class of unmanned micro-sized aerial vehicles that mimic flying biological organisms(like flying insects). Insects, such as dragonflies, possess corrugated and complex vein structures that are difficult to mimic. Simplified dragonfly-like wing frames were fabricated from these materials and then a nano-composite film was adhered to them, which mimics the membrane of an actual dragonfly. Finite element analysis simulations were also performed and compared to experimental results. The results showed good agreement(less than 10% difference for all cases).Analysis of these results shows that stainless steel is a poor choice for this wing configuration, primarily because of the aggressive oxidation observed. Steel, as well as balsa wood, also lacks flexibility. In comparison, black graphite carbon fiber and red prepreg fiberglass offer some structural advantages, making them more suitable for consideration in future BMAV applications.     

落儿岭-土地岭断裂几何结构及晚第四纪活动特征初探

落儿岭-土地岭断裂是东大别地区重要的发震构造,然而限于自然地理条件等因素,前人对其的研究并不充分。本文以发生多次中强地震的落儿岭-土地岭断裂为研究对象,在高精度卫星影像解译的基础上,通过详细的野外地质地貌调查,尤其是对典型断层剖面进行分析,研究落儿岭-土地岭断裂的断错地质地貌特征、几何结构及活动特征。通过野外调查并结合其他资料分析认为落儿岭-土地岭断裂为发育于大别造山带内部的一条走向NE、向NW陡倾的断裂带。依据地质地貌特征及地震活动性,断裂可以划分为杨树沟-黑石渡段和黑石渡-横塘岗乡段两个几何段落。断裂最新活动时代为中更新世晚期—晚更新世早期,断裂最新活动继承了中生代以来的运动方式,以兼具右旋走滑的拉张正断为主。     

某型飞机典型结构应力腐蚀开裂原因分析

针对某型飞机典型结构应力腐蚀开裂问题,从材料选用、结构加工、装配工艺、服役环境等角度,结合有限元模拟细节应力分析技术,分析了发生应力腐蚀开裂的原因。基于分析结果,为新飞机制造和现役飞机维修提供相应的建议,为制造厂和维修厂提高飞机结构的应力腐蚀抗性以及结构完整性和航空安全性提供参考。     

高效图像资源管理器的设计与实现

针对数据存储量大引起的访问广域网服务器速度慢、不能对访问的客户进行细粒度的权限控制问题,研究了B/S模式下基于.NET平台的图像资源管理器的设计和实现技术。系统综合采用权限管理模型、动态加载、文档对象模型（DOM）等技术以及非点击无刷新伸缩控制方法,实现了图像资源管理器的分权限控制、高速访问以及无刷新高效联动等操作。实验验证了方法的可行性。     

NOVEL HIGH-SPEED FPGA-BASED FFT PROCESSOR

A novel architecture for computing the fast Fourier transform ( FFT ) on programmable devices is presented.To improve the system operation speed , a hybrid parallel FFT algorithm is used.Results indicate that the use of an 8×8parallel structure for realizing the 64-point FFT leads to a 8times higher processing speed compared with its counterparts employing other series of techniques.     

Effects of sector structure of the interplanetary magnetic field on the upper mesosphere–lower thermosphere dynamics

In this paper we study the influence of the interplanetary magnetic field (IMF) polarity changes caused by the Earth passing through the IMF sector boundary on the dynamic processes taking place in neutral atmosphere within the altitude interval of the upper mesosphere–lower thermosphere (83–101 km). The analysis has revealed the influence of the IMF sector structure on dynamics of the upper mesosphere–lower thermosphere. There has been a significant seasonal variation of the wind reaction to the IMF polarity changes observed. The influence of the IMF polarity changes on neutral atmosphere dynamics within the altitude range of 83–101 km is most pronounced in the zonal component of neural wind when the IMF polarity changes from negative to positive in all the seasons except for spring and when IMF polarity changes from positive to negative – in spring only.