有阻尼体系的时域边界元法

针对时域边界元方法的特点，提出了一种新的阻尼模型（称为比例时耗阻尼），并成功地应用于时域边界元方法中．这是在时域边界元方法中首次考虑阻尼这一影响结构动力响应的重要因素，为时域边界元在实际工程中的应用解决了一个难题．通过对简单问题的分析和计算，验证了本文模型的正确性．     

三维非规则非均匀边界元网格的简便的高精度算法

对三维直接边界元中一阶奇异积分、一阶近奇异积分以及非奇异积分进行统一处理，给出了一种提高积分计算精度的简便有效的方法，对非规则非均匀边界元网格可获得比一般方法高得多的计算精度，非常适合边界形状比较复杂的三维实际问题的边界元分析．     

三维非规划非均匀边界元网格的简便的高精度算法

对三维直接边界元中一阶奇异积分，一阶近奇异积分以及非奇异积分进行统一处理，给出了一种提高积分计算精度的简便有效的方法，对非规则非均匀边界元网格可获得比一般方法高得多的计算精度，非常适合边界形状比较复杂的三维实际问题的边界元分析。     

边界积分方程——非连续边界元度散方法及其应用

利用非连续元离散边界积分方程,有效地解决了“角点效应”问题,对影响非连续元精度和分析效率的几个问题从数值计算的角度进行了讨论,将非连续边界元用于自适应边界元分析,给出了自适应边界元误差指示确定的一种方法,通过对具体实例分析表明了给所方法的可行性,。》     

非连续边界元——有限元耦合方法分析

对边界元－有限元耦合方法进行了分析，采用非连续元离散边界积分方程，解决了耦合分析中自由度约束问题，给出了非连续边界元同有限元耦合的具体实施步骤，通过对二维弹性力学和流＝固耦合问题分析，表明了该文方法的有效性。     

二维边界元奇异积分和多域缩聚法分析

基于基本解的一种新的表达式，对二维边界元分析中奇异积分的精确求解进行了讨论，从几何方面对基本解的奇异性进行了分析，给出了超参非连续元离散位势和弹性力学问题边界积分方程时奇异积分计算的精确式，从而为判断各种近似方法的优劣和间接方法的精度提供了依据，也为精确地分析了大规模问题提供了一条有效的途径。     

各向异性介质波动问题的时域边界元法及实验验证

对前已建立的各向异性介质波动问题的时域边界元计算模型进行了实验验证．用单向纤维增强光弹性复合材料模拟正交异性介质，用冲击加载，加载方向与纤维方向分别成0°，90°及45°角度，进行了正交异性动态光弹性实验及动态应变测量，并同时对该模型进行了时城边界元计算．将时域边界元方法计算出的应力分量代入正交异性动态光弹性的动态应力-光性定律，得到双折射条纹级数随时间的变化曲线，将其与动态光弹性实验的结果进行比较；此外，由动态电测获得的应变响应曲线推算出应力时程；与时城边界元计算出的应为响应曲线也进行了比较．两种情况下，时域边界元的计算成果均与实验成果吻合较好，从而证明该各向异性介质波动问题的时域边界元计算模型具有较好的精度及稳定性，可用于各向异性介质的动态问题特别是波传播问题的分析研究．     

一种新的三角极坐标变换

本文提出了一种新的三角极坐标变换，它将积分域中的三角形区域映射到另一三角形区域，而坐标变换所引入的雅可比矩阵可消除积分核的Ｏ（１／ｒ）奇异性，从而对于三角形单元，在进行边界元积分计算时，非奇异积分和Ｏ（１／ｒ）型奇异积分可采用同一种计算格式，简化了三角形边界元的编程和运用，并可提高计算效率。     

齿轮边界元强度计算的单元自动生成

本文提出一种专用于齿轮边界元强度计算的单元自动生成办法，只需输入端截面内一半数据，便可自动生成空间四边形8节点等参元的全部数据，也适合于其它螺旋体的边界元计算．     

三维弹性力学边界元多域缩聚法分析

采用超参非连续元离散三维弹性力学问题边界积分方程，借助三角极坐标变换方法处理奇异积分。将超参非连续元用于多域边界元分析，解决了自由度约束问题。提出了二次缩聚的概念，提高了多域缩聚边界元法的求解效率。通过数值算例表明了本文方法的可行性和有效性。     

Elastodynamic Green’s function for reinforced concrete beams

A semi-analytical solution procedure for three dimensional wave propagation in reinforced concrete (RC) beams has been presented in this paper. Elastodynamic Green’s function has been derived by employing the compatibility conditions and utilizing the symmetry conditions at the loaded cross section. Numerical procedure developed for the Green’s function has been validated using results available in the literature for an infinite laminated composite plate. Three-dimensional wave propagation analysis has been performed for reinforced concrete beam sections of T and L shapes which are common forms of structural elements. Steel reinforcement has been modeled in the finite element mesh. Effect of corrosion has also been included in the finite element model. Green’s function for reinforced concrete sections affected by corrosion of steel unit normalized frequency has been evaluated for illustration. Accuracy of the solution technique has been evaluated in terms of the percentage error in energy balance between the input energy of the applied unit load and the output energy carried by the propagating wave modes. The percentage error has been found to be negligible in all the cases considered here. A simple and accurate numerical method has been presented here as a tool to evaluate Green’s function for RC beams and can be used to detect corrosion.     

Rotary motion of the parametric and planar pendulum under stochastic wave excitation

In this paper a rotary motion of a pendulum subjected to a parametric and planar excitation of its pivot mimicking random nature of sea waves has been studied. The vertical motion of the sea surface has been modelled and simulated as a stochastic process, based on the Shinozuka approach and using the spectral representation of the sea state proposed by Pierson–Moskowitz model. It has been investigated how the number of wave frequency components used in the simulation can be reduced without the loss of accuracy and how the model relates to the real data. The generated stochastic wave has been used as an excitation to the pendulum system in numerical and experimental studies. For the first time, the rotary response of a pendulum under stochastic wave excitation has been studied. The rotational number has been used for statistical analysis of the results in the numerical and experimental studies. It has been demonstrated how the forcing arrangement affects the probability of rotation of the parametric pendulum.     

Experimental Study on Oscillatory Natural Convection in a Hele-Shaw Cell due to Unstably Heated Side

The oscillatory motion of natural convection in a porous medium has been investigated experimentally using a Hele-Shaw cell technique. The cell has been heated on the lower half and cooled on the upper half along the same vertical sidewall. Flows have been visualized using the pH indicator method. Photographs of natural convection patterns as well as average Nusselt number data have been presented for different Rayleigh numbers. Oscillatory motion of natural convection has been observed for large enough Rayleigh numbers and the critical Rayleigh number has been estimated to be between 120 and 450. Scaling analysis has been conducted to understand the heat transfer and the oscillating mechanism. According to the scaling analysis, it has been found that the average Nusselt number is proportional to the square root of the Rayleigh number, and that the oscillation frequency is proportional to the Rayleigh number. Obtained experimental data support the scaling analysis.     

Exact slip-buckling analysis of two-layer composite columns

A mathematical model for slip-buckling has been proposed and its analytical solution has been found for the analysis of layered and geometrically perfect composite columns with inter-layer slip between the layers. The analytical study has been carried out to evaluate exact critical forces and to compare them to those in the literature. Particular emphasis has been placed on the influence of interface compliance on decreasing the bifurcation loads. For this purpose, a preliminary parametric study has been performed by which the influence of various material and geometric parameters on buckling forces have been investigated.     

VIBRATIONS OF CIRCULAR CYLINDRICAL SHELLS WITH NONUNIFORM CONSTRAINTS,ELASTIC BED AND ADDED MASS. PART III: STEADY VISCOUS EFFECTS ON SHELLS CONVEYING FLUID

The effect of steady viscous forces on vibrations of shells with internal and annular flow has been considered by using the time-mean Navier–Stokes equations. The model developed in Part I of the present study, capable of simulating shells with nonuniform boundary conditions, added masses and partial elastic bed, has been extended to include nonuniform prestress. The effect of steady viscous forces has been added to the inviscid flow formulation considered in Part II of the present study. A computer code, DIVA, has been constructed by using the model developed in this series of papers. It has been validated by comparison with available results for shells with uniform constraints and has been used to study shells with nonuniform constraints and added lumped masses.     

Analysis of stress singularities in thin coatings bonded to a semi-infinite elastic substrate

The interfacial stress arising between thin structures bonded to a 2D elastic substrate has been investigated in the present work. Chebyshev polynomials have been adopted to approximate the shear stress occurring across the contact region. Perfect adhesion has been assumed among the coating structures and the underlying substrate, leading to a singular integral equation which has been reduced to an algebraic system. Thin bonded structures having several geometric configurations under different load conditions have been considered. In particular, the stress concentration in the neighborhood of the coating edges and around the points of load application has been evaluated in detail.     

Numerical investigation of structural geometric nonlinearity effect in high-aspect-ratio wing using CFD/CSD coupled approach

An efficient and robust fluid–structure coupled methodology has been developed to investigate the linear and non-linear static aeroelastic behavior of flexible high-aspect-ratio wing. A three-dimensional open source finite element solver has been loosely coupled with an in-house Reynolds-averaged Navier–Stokes solver, designed for hybrid-unstructured meshes, to perform aero-structural coupled simulations. For volume mesh deformation and two-way data interpolation over non-matching grids interface, a radial basis function methodology combined with a data reduction algorithm has been used. This technique is efficient in handling large deflections and provides high-quality deformed meshes. Structural geometric nonlinearity has been considered to predict the deformations in the vertical and torsional directions caused by gravitational and aerodynamic loading. A multi-material finite element model has been generated to match the experimental configuration. Computational aeroelastic simulations were performed on an experimental high-aspect-ratio aeroelastic wing model with a slender body at the tip to get non-linear static deflections, twist and structure natural frequencies. The effect of the geometric nonlinearity is significant for large deformation analysis and has been highlighted in the predicted maximum tip deflection and twist. Good qualitative and quantitative agreement has been achieved between the predicted results and the available experimental data.     

Transient and statistical measurement techniques for two-phase flows: A critical review

Much work has been expended in the study of two-phase, gas-liquid flows. While it has been recognized superficially that such flows are not homogeneous in general, little attention has been paid to the inherent discreteness of the two-phase systems. It has been a relatively recent development that fluctuating characteristics of two-phase flows have been studied in detail. As a result, new experimental devices and techniques have been developed for use in obtaining measurements of quantities previously ignored. This paper reviews and summarizes these methods in an effort to emphasize the importance of the fluctuating nature of these flows and as a guide to further research in this field.     

钢丝绳捻制成形的空间几何模型与有限元分析

根据钢丝绳捻制成形原理，在考虑钢丝绳空间几何形状的基础上，建立了引入自扭转系数时钢丝绳的几何结构计算模型和钢丝绳捻制成形有限元计算边界条件模型。进而编制了相应的有限元建模程序，生成可被ANSYS直接调用的数据文件。分析了钢丝绳一次捻制和二次捻制的加工应力应变变化情况，并讨论了自扭转系数对加工应力应变的影响。     

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根据实验结果,将泥石流的流变关系分为稀性和粘性泥石流两类情况进行了分析,并由流变模型绘出明渠中泥石流的垂向速度分布．