一种连续索滑移的处理方法

目的是建立一种快速简便的拉索滑移问题的有限元计算方法。采用基于弹性悬链线精确解的两节点悬链线单元模拟索结构中的拉索，利用求解非线性方程组的延拓法，再配以常用的牛顿法，建立了快速的给定索原长情况下的拉索刚度计算方法。此法对于一般的给定初值，能很快逼近真实解，从而扩大了解的收敛范围，更重要的是与牛顿法相比更加高效。进而采用二分法建立了索结构中拉索滑移问题处理的算法，编制了相应的程序段，并通过算例证明了其正确性。本文的拉索滑移处理方法可用于索结构的设计与施工。     

Control of Wind-Induced Nonlinear Oscillations in Suspended Cables

In this paper, the along-wind and across-wind responses of suspended cables are studied. The mean wind direction is assumed to be perpendicular to the plane of the suspended cable. It is shown that the cable gallops in the across-wind direction, when the mean wind speed exceeds a critical wind speed. To control the galloping response, a vertical viscous damper, in the vertical plane of the cable, is introduced at a certain location on the cable to a near fixed platform such as a bridge deck. The efficiency of the vertical viscous damper and its location in controlling the galloping of the suspended cable is investigated.     

碳纤维复合材料拉索的非线性力学性能

采用解析法分析碳纤维复合材料(CFRP)拉索的非线性力学性能,通过与钢拉索对比分析,得出了CFRP拉索的受力特点.由于密度低,CFRP拉索自重应力、垂度约为钢拉索的1/5,承载效率也比钢拉索高许多,其承载极限长度为钢拉索的7倍,且随跨径增大,钢拉索的等效弹性模量下降非常快,而CFRP索仍保持较高值.由于CFRP线胀系数比钢材的线胀系数要小得多,约为其1/14,在温差与约束相同时,无垂度CFRP索温度应力仅为无垂度钢索的1/23.当有垂度时,钢索的温度应力降低,CFRP索的温度应力变化很小.     

Perturbation analyses for the postbuckling of simply supported rectangular plates under uniaxial compression

In this paper, applving perturbation method to von Kármán nonlinear large deflection equations of plates by taking deflection as perturbation parameter, the posibuckling behavior of simply supported rectangular plates under uniaxial compresion is investigated. Two types of in-plane boundary conditions are now considered and the effects of initial imperfections are also studied. It is found that the theoretical results are in good agreement with experiments. The method suggested in this paper which has not been found in previous papers is rather simple and easy for the postbuckling analysis of rectangular plates.     

Acoustic emission monitoring of carbon-fiber-reinforced-polymer bridge stay cables in large-scale testing

This paper presents acoustic emission (AE) monitoring of damage initiation and progression in carbon-fiber-reinforced-polymer (CFRP) stay cables subject to largescale laboratory tests. The research is part of the University of California, San Diego (UCSD), larger project on the design and construction of a new cable-stayed bridge made of advanced composites. No previous use of AE on large-size CFRP stay cables appears in the literature. Three types of cables of potential use in the UCSD composite bridge were tested at lengths ranging from 5500 mm to 5870 mm. The AE events were monitored to detect damage and provide a qualitative correlation with the type of structural failure. The tests allowed a comparative characterization of the failure behavior of the three types of cables under investigation. An additional study was performed to characterize acoustic attenuation and dispersion phenomena that are relevant to AE testing of largescale CFRP cables. It is shown that despite their large size, these cables are excellent acoustic wave guides exhibiting very low attenuation. Finally, this study shows promising results for an effective use of in situ AE for health monitoring of these structural components in service.     

Dynamics of Geometrically Nonlinear Rods: II. Numerical Methods and Computational Examples

The paper selects and develops appropriate numerical solutionmethods for initial boundary value problems of the equations of motionof geometrically nonlinear extensible Euler–Bernoulli-beams. A finiteelement method that uses first-order Hermitian polynomials as interpolationfunctions for the rod axis position vector is used as discretizationtechnique. An averaging method for the calculation of net forces andmoments is developed that achieves a better approximation than thedirect calculation from the strains. Time integration is done usingan energy and momentum conserving algorithm that is proposed in thispaper and Newmark type methods. The derived algorithms are used tosolve problems from space and marine engineering. The obtained simulationresults are compared with results which have been already publishedin the literature or were calculated by different methods.     

斜拉桥拉索-阻尼器系统非线性响应分析

考虑索的抗弯刚度、垂度及几何非线性的影响，得出了索一阻尼器系统的空间非线性振动偏微分方程，用中心差分法将微分方程在空间内离散，导出了系统的非线性振动常微分方程组。结合Newmark法及虚拟力法提出了一种用于求解非线性振动瞬态响应的杂交分析算法。并以典型的斜拉桥拉索为研究对象，给出了数值算例，并与Runge—Kutta直接积分法进行了比较，说明了杂交算法的准确性及有效性。     

水轮机蜗壳和固定导叶内部三维紊流流场数值研究

1引言用数值方法研究蜗壳和固定导叶内部流场是改进和优化蜗壳和固定导叶设计的一个重要手段。早期的数值研究大多基于势流理论[1～2]，随着计算机技术和计算流体动力学的迅速发展，蜗壳和固定导叶内部三维紊流的数值分析已经成为可能t’－’］。本文以三峡水轮机组内部流动的研究为背景，基于N－S方程和标准的k一。紊流模型，采用贴体座标和交错网格系统，用SIMPLEC算法对三峡模型机组蜗壳和固定导叶内部的流动进行数值模拟，提出设计工况时蜗壳和固定导叶内三维素流数值模拟计算结果，为改进蜗壳和固定导叶设计提供了一些有益的参考资…     

Review of conductor development for use in high-temperature superconducting cables

Summary This paper reviews and assesses the progress in conductor development across the world in advancing high-temperature superconducting science and technology towards the fabrication of superconducting transmission cables operating at 77 K. Materials, fabrication routes and the feasibility of high-temperature superconducting cables will be discussed. Paper presented at the ?VII Congresso SATT?, Torino, 4–7 October 1994.     

扩张不变集相对非自治扰动的稳定性

本文研究了自映射的扩张不变集在Ｃ￣０非自治扰动和Ｃ￣１非自治扰动下的稳定性质。