THEORETICAL AND EXPERIMENTALRESEARCH ON DYNAMIC BEHAVIOR OF GUYED MASTS UNDER WIND LOAD

I. INTRODUCTION Wind-induced vibration is the critical factor for the safety of guyed masts. Many dynamic modelshave been proposed in the literature[1 , 2]. However, there are obvious de?ciencies in many of theseprevious works owing to the poor cabl…     

Weakly R-KKM mappings——intersection theorems and minimax inequalities in topological spaces

In this paper, we introduce the concepts of weakly R-KKM mappings, R-convex and ,R-β-quasiconvex in general topological spaces without any convex structure. Relating to these, we obtain an extension to general topological spaces of Fan's matching theorem, namely that Lemma 1.2 in this paper. On this basis, two intersection theorems are proved in topological spaces. By using intersection theorems, some minimax inequalities of Ky Fan type are also proved in topological spaces. Our results generalize and improve the corresponding results in the literature.     

PATH INTEGRAL SOLUTION OF NONLINEAR DYNAMIC BEHAVIOR OF STRUCTURE UNDER WIND EXCITATION

IntroductionThe dynamic behavior of the nonlinear structure under wind excitation has beenobserved very complicated.Taking guyed masts as an example,only a few collapsingaccidents occurred under extreme atmospheric conditions[1],many took place under mild…     

纤维树脂界面剪切强度及纤维强度分布参数的实验测定

界面剪切强度及纤维强度分布参数是复合材料设计及应用研究中的重要参数，本文采用单纤维段埋入法测定了上述两个参数。通过实验研究说明了单纤维段埋入法是一种测定界面剪切强度及纤维强度分布参数的有效的实验方法；同时证实了基体的力学性能对界面剪切强度有着重要的影响。全部实验在自制的实验系统上完成     

压电材料椭圆切口的力学分析

在线性压电本构方程框架下，用复势函数方法对椭圆切口模型进行了精确的数值计算。完整地考虑了各向异性力电耦合效应以及切口内不同电介质的介电性质。给出了切口内部不同介电性质对压电材料内部应力的影响。指出了Sosa文章里的一些计算错误。由于现在文献中很少有关于电导通边界条件下理论解的数值结果，所以本文同时提供了不同电边界条件下理论解的数值结果，所以本文同时提供了不同电边界条件下的理论解的数值结果。最后通过最小势能原理建立了8结点有限元模型，对椭圆切口问题进行了计算并与理论解进行了仔细比较。     

遥感技术用于固体力学实验研究的新成果

在岩石、混凝土和钢材加载直到破坏的过程中用红外和微波遥感技术进行了观测研究．发现这些材料在加载过程中其红外和微波辐射温度、红外辐射波谱及红外热像均随应力的变化而变化．材料破坏前这些变化表现出某些前兆性特征．研究表明遥感技术可作为固体力学研究的一种新手段，并可望在工程上得到应用     

EXACT LINEARIZATION BASED MULTIPLE-SUBSPACE ITERATIVE RESOLUTION TO AFFINE NONLINEAR CONTROL SYSTEM

To the optimal control problem of affine nonlinear system, based on differential geometry theory, feedback precise linearization was used. Then starting from the simulative relationship between computational structural mechanics and optimal control, multiple-substructure method was inducted to solve the optimal control problem which was linearized. And finally the solution to the original nonlinear system was found. Compared with the classical linearizational method of Taylor expansion, this one diminishes the abuse of error expansion with the enlargement of used region.     

单轴条件下砂岩三维破裂过程的CT观测

岩石破裂过程研究一直是岩石力学专家关注的重要问题。本文采用特制的三轴压力仪与医用西门子SOMATOM -plusCT扫描仪结合 ,对砂岩进行了室内单轴压缩试验。通过对砂岩的CT图像和密度损伤增量与应力关系曲线分析 ,结果显示 ,砂岩的破裂演化过程可分为初始损伤的压密、裂纹出现—扩展、裂纹归并—分岔、裂纹重分岔—扩展以及裂纹惯通—宏观破坏等五个阶段。在初始损伤的压密阶段 ,砂岩的密度损伤增量为正值 ,速率也为正 ;在裂纹出现—扩展阶段 ,砂岩出现局部密度损伤增量减小 ,并随应力增加而由正值转为负值 ,速率也由正变负 ;在裂纹归并—分岔阶段 ,砂岩的密度损伤增量全为负值 ,速率也变快 ;在裂纹重分岔—扩展阶段 ,砂岩的密度损伤增量继续变负 ,但速率变慢 ;在裂纹惯通—宏观破坏阶段 ,砂岩的密度损伤增量继续变负 ,速率变的更快。     

Mixed-mode I/II fields around a crack with a cohesive zone ahead of the crack tip

Considering a cohesive zone ahead of the crack tip, the linear elastic crack problem under Mode I, Mode II or mixed-mode conditions is formulated in an elliptic coordinate system, so that the cohesive surfaces are conveniently represented by straight line segments. It is shown that the displacement and stress fields around the crack tip and the cohesive zone, expressed in terms of elliptic coordinates, have a simple mathematical form, which does not contain a stress singularity at the crack tip due to the existence of the cohesive zone.     

EXPONENTIAL STABILITY OF INTERVAL DYNAMICAL SYSTEM WITH MULTIDELAY

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｔａｂｉｌｉｔｙｏｆｔｈｅｉｎｔｅｒｖａｌｍａｔｒｉｘａｎｄｕｎｃｅｒｔａｉｎｓｙｓｔｅｍｗｉｔｈｔｉｍｅｄｅｌａｙｈａｖｅｂｅｅｎｃｏｎｓｉｄｅｒｅｄｂｙｒｅｓｅａｒｃｈｅｒｓｉｎｔｈｅｐａｐｅｒｓ [1 -1 3 ] .Ｔｈｅｓｔａｂｉｌｉｔｙａｎｄαｅｘｐｏｎｅｎｔｉａｌｓｔａｂｉｌｉｔｙｏｆｔｈｅｆｏｌｌｏｗｉｎｇｉｎｔｅｒｖａｌｄｙｎａｍｉｃａｌｓｙｓｔｅｍｗｉｔｈｓｉｎｇｌｅｔｉｍｅｄｅｌａｙ ｘ(ｔ) =Ｎ[Ｐ ,Ｑ]ｘ(ｔ) +Ｎ[Ｃ ,Ｄ]ｘ(ｔ-τ)ｈａｖｅｂｅｅｎｃｏｎｓｉ…