浅埋的圆柱形孔洞对SH波的散射与地震动

研究了浅埋的圆柱形孔洞对以任意方向入射的平面SH波的散射与地震动问题。利用复变函数和多极坐标方法构造了问题的位移解。当入射波的波长与圆孔的半径相比较小时,地震动将受到较大的影响。影响地震动有三个主要参数:(1)SH波的入射角0;(2)入射波波数,即圆柱形孔洞的半径与入射波半波长之比;(3)h/R,即圆柱形孔洞至表面的距离与圆孔半径之比。当较大时,地震动幅值变化激烈,位移幅值可出现跳动和放大的现象。当h/R增大至10～12时,位移幅值变化恢复至半空间的情况,表明圆柱形孔洞的影响可被忽略。     

复杂三维结构物的光弹性实验研究

应用光弹性原理和方法，根据有关相似原理，对研究对象的几何尺寸进行缩比、模型设计及加工成型．然后将模型在危险载荷作用下，进行应力冻结、切片及应力分析．确定了模型不同截面上的应力及其变化规律，为优化设计和调整数值计算方法提供了有价值的依据．     

ANALYSIS ON ACOUSTICAL SCATTERING BY A CRACKED ELASTIC STRUCTURE

The acoustical scattering by a cracked elastic structure is studied. The mixed method of boundary element and fractal finite element is adopted to solve the cracked structure-acoustic coupling problem. The fractal two-level finite element method is employed for the cracked structure, which can reduce the degree of freedoms (DOFs) greatly, and the boundary element method is used for the exterior acoustic field which can automatically satisfy Sommerfeld‘s radiation condition. Numerical examples show that the resonance frequency is lower with the crack‘s depth increase, and that the effect on the acoustical field by the crack is particularly pronounced in the vicinity of the crack tip. This mixed method of boundary element and finite element is effective in solving the scattering problem by a cracked structure.     

用拉梅-麦克斯韦尔方程解平面楔及半平面受集中力问题

借助拉梅-麦克斯韦尔方程用解析法求解半无限平面楔顶受集中力的问题. 在这 一问题中的主应力坐标系和极坐标系是等价的，据此求得半无限平面楔问题的解. 把受集中 力作用的半无限平面问题视为上述问题的特例, 也给出了它的解. 该求解方法直接而简 单，逻辑严密.     

动力学逆问题的提法和解法

本文介绍动力学逆问题的研究现状,并提出逆问题的几个未来发展方向.     

各向异性两相材料尖劈奇性场的非协调元分析

提出了一个基于位移的、分析柱状各向异性两相材料尖劈端部邻域的奇性位移场和应力场问题的非协调元特征分析法. 该方法从柱状扇区的散度定理出发，将柱状扇区控制方程的弱式化为一个与虚功原理相同形式的方程，采用一种新的非协调元技术把所导出的``虚功原理'转化为标准一阶特征方程的求解问题. 非协调元法中，尖劈端部邻域的位移场假定没有采用奇异变换技术，有限元的单元形式是一维的. 将柱状各向异性两相材料尖劈视为``广义平面应变'问题，位移场与坐标z无关，只关注界面端的幂奇异性而不考虑对数奇异性. 运用该方法给出了柱状各向异性两相材料尖劈端部奇性应力指数、奇性位移角分布和应力角分布的算例. 所有的计算结果表明，该方法使用的单元少而且精度较高.     

弹性地基梁振动特性的近似分析方法

文中介绍了用模态摄动法分析复杂情况下弹性地基梁动力特性的近似方法。这一方法中可考虑纵向钢筋以及变地基弹性系数对弹性地基梁振动特性的影响，通过算例说明了这一方法的有效性。     

ANALYSIS OF AN INCOMPRESSIBLE RUBBER WEDGE CONTACTING WITH A RIGID NOTCH

I. INTRODUCTION It is well known that rubber materials are much more important in modern society. It is, therefore,not surprising that a sizable number of investigations have been concerned with the rubber materials.Considerable attention has been paid …     

大型沉井结构施工力学模型的研究

大型沉井结构是当今应用较广的基础工程，由于沉井结构的规模大，工区土层复杂，存在有许多不确定性因素。使得施工过程的力学模型比较难确定。迄今尚缺乏可供借鉴的理论研究。由于施工的关键是保证沉井的均匀下沉，控制终沉和防止突沉，为此，建立合适的施工力学模型以预测下沉量和开挖量之间的关系就十分必要，考虑到混凝土沉井在土体中下沉时，其本身的变形很小，可以忽略其影响，本文从多自由度刚体运动的角度，建立沉井下沉过程的动态力学模型。为验证所建模型的正确性，本文对一实际工程进行了数值仿真计算。并将计算结果与实测结果进行了对比。结果表明，所建立的力学模型能较好地反映沉井下沉的工程实际，因而可以应用该模型对沉井下沉进行预测分析。从而有助于指导沉井的实际施工。     

A PREDICTIVE APPROACH TO THE IN-PLANE MECHANICAL PROPERTIES OF STITCHED COMPOSITE LAMINATES

This contribution attempts to model the alteration of the in-plane elastic properties in laminates caused by stitching,and to predict the in-plane effective tensile strength of the stitched composite laminates.The distortion of in-plane fibers is considered to be the main cause that affects the in-plane mechanical properties.A fiber distortion model is proposed to characterize the fiber misalignment and the fiber content concentration due to stitching.The undistorted region,the fiber distortion region,the resin-rich pocket and the through-thickness reinforcement section are taken into account.The fiber misalignment and inhomogeneous fiber content due to stitching have been formulated by introducing two parameters,the distortion width and maximum misalignment.It has been found that the ply stress concentration in stitched laminates is influenced by the two concurrent factors,the stitch hole and inhomogeneous fiber content.The stitch hole brings about the stress concentration whereas the higher fiber content at the local region induced by stitching restrains the local deformation of the composite.The model is used to predict the tensile strength of the [0/45/0/-45/90/45/0/-45]_(2s) T300/QY9512 composite laminate stitched by Kevlar 29 yarn with different stitching configurations,showing an acceptable agreement with experimental data.