孔隙压力作用下圆形巷道围岩的蠕变分析

在原有的岩土流变理论基础上,与渗流力学原理相结合,考虑孔隙压力及孔隙度在岩石蠕变过程中对于岩体变形的影响,在弹性解答的基础上,通过Laplace变换(对应性原理)得出解析解．在一定的假设条件下,利用弹性力学基本方程、蠕变方程及有效应力原理(Terzaghi有效应力方程),采用H-K体模型作为本构方程,将孔隙压力引入到围岩蠕变方程中．给出在孔隙压力作用下的蠕变曲线,并与不考虑孔隙压力和定孔隙压力条件下蠕变曲线相比,其更接近于实际．     

A variational solution of 2-D sound-structure interaction problems

Based on the fluid-structure coupling theory, a localized variational principle for analyzing the sound radiation from elastic structure submerged in water due to harmonic excitations is presented. It will be a powerful tool to formulate various numerical methods for steady response of structural-acoustic systems. By means of this variational principle a hybrid element method, in which an analytical solution valid in most of the surrounding water is incorporated with finite elements distributed in the structure and its neighboring water, is devised. Computational examples are then given to demonstrate its high accuracy and time saving. The project supported by the National Natural Science Foundation of China (10172038) and the Doctoral Program Foundation of Institution of Higher Education of China (20040487013). The English text was polished by Yunming Chen.     

THE OPTIMAL CONTROL VARIATIONAL PRINCIPLE AND FINITEELEMENTS ANALYSIS FOR VISCOPLASTIC DYNAMICS

I.Viscoplastic-DynamicsConstitutiveRelationThestructurematerialwouldarisesimultaneouslytheelasticity,viscosityandplasticityindynamichighstraincondition.Atpresent,theovcrstressmodel,viscoplasticitymodel,quasi-linearconstitutiverelationtheoryandintrinsicvar…     

任意挠曲输液管道瞬时变分原理

给出了弹性系统瞬时势能泛函的一般表达式，得到了其关于任意挠曲输液管道的具体表达式，根据瞬时最小势能原理建立了该结构的有限元动力方程，并首次推导出其离心力载荷公式，讨论了管道结构静平衡位置的发散流速的确定，最后，用简单的实验结果对理论分析作了验证。     

非线性问题严格互补极点－鞍点定理

本文给出两个具有新的非线性型式问题的严格互补极点－鞍点定理，同时论述了建议的二次变分－凸分析方法的一般性和有效性。其一是旋转叶轮问题，通过引进周期性自由面变量，揭示了隐含的一类对偶变分原理，从而给出了可能存在的全部互补原理。其二是带转动变量的非Ｋ－Ｌ壳体，具有超出常规的几何非线性性质，目前只知道使用这里的方法可以建立互补原理。     

Parameter identification for viscoelastic materials

Starting from the general stress-strain relation for a linear Boltzmann-Volterra material, which is in agreement with the principle of inertia, a new identification procedure is proposed. Instead of running one long-range relaxation experiment, following asingle suitably specified deformation history, material characterization is done using the data ofn short relaxation experiments followingn different deformation histories. To interpret these data a direct non-iterative algorithm has been developed. Compared with other methods, for example curve fitting by using Gauss' method, this direct method is numerically stable and allows a simple direct evaluation of the error due to the scattering of experimental data. The method has been applied to the determination of the relaxation times of an unsaturated polyester material.     

非线性粘弹性拟静态问题与非线性弹性静力问题对应原理

本文应用多重单边拉氏变换导出了非线性粘弹性拟静态问题与非线性弹性静力问题的对应关系,从而把过去认为只有线性条件下存在的粘弹性——弹性对应原理拓展到了非线性范畴     

热压电变分原理

热释电介的许多传感器及机敏结构或中的关键材料，本文系统地讨论了在基础理论和数值计算中极具重要地位的各类变分原理，包括准静态变分原理、动态变分原理和关于固有频率的变分原理。最后建立了关于静态压电要板的变分原理，并由此导出了各向异性压电板的控制方程及边界条件。     

Preliminary report on the energy balance for nonlinear oscillations

In this paper, a reliable technique for calculating angular frequencies of nonlinear oscillators is developed. The new algorithm offers a promising approach by constructing a Hamiltonian for the nonlinear oscillator. Some illustrative examples are given.     

The Stress Response of Functionally Graded Isotropic Linearly Elastic Rotating Disks

The purpose of this research is to investigate the effects of material inhomogeneity on the response of linearly elastic isotropic solid circular disks or cylinders, rotating at constant angular velocity about a central axis. The work is motivated by the recent research activity on functionally graded materials (FGMs), i.e., materials with spatially varying properties tailored to satisfy particular engineering applications. The analog of the classic problem for a homogeneous isotropic rotating solid disk or cylinder is considered. The special case of a body with Young"s modulus depending on the radial coordinate only, and with constant Poisson"s ratio, is examined. For the case when the Young"s modulus has a power-law dependence on the radial coordinate, explicit exact solutions are obtained. It is shown that the stress response of the inhomogeneous disk (or cylinder) is significantly different from that of the homogeneous body. For example, the maximum radial and hoop stresses do not, in general, occur at the center as in the case for the homogeneous material. Furthermore, for the case where the Young"s modulus increases with radial distance from the center, it is shown that radially symmetric solutions exist provided the rate of growth of the Young"s modulus is, at most, cubic in the radial variable. It is also shown for the general inhomogeneous isotropic case how the material inhomogeneity may be tailored so that the radial and hoop stress are identical throughout the disk. This revised version was published online in August 2006 with corrections to the Cover Date.