ON THE SUFFICIENT CONDITION FOR A CONVEX DOMAIN TO CONTAIN ANOTHER IN R_(2n)

1IntroductionandSomeLemmasInplalle,tileclassicalresultsontilesufficielltcollditiolll'oradonlailltocontaillallotherareobtainedinH.Hadwiger's['t,]first.Renobtaillstileeqllivalentformwhichisllloresilllplein[1],i.e.,TheoremLetDoandDIbethedomainsboulldedbythes…     

A micromechanics approach to homogenizing elasto-viscoplastic heterogeneous materials

The variational asymptotic method for unit cell homogenization (VAMUCH) has emerged as a general-purpose micromechanics code capable of predicting the effective properties of heterogeneous materials and recovering the local fields. The objective of this paper is to propose a micromechanics approach enabling VAMUCH to homogenize elasto-viscoplastic heterogeneous materials. An affine formulation of the constitutive relations for an elasto-viscoplastic constituent, which exhibits viscoplastic anisotropy and combined isotropic–kinematic hardening, is derived. The weak form of the problem is derived using an asymptotic method, discretized using finite elements, and implemented into VAMUCH. The new features of VAMUCH are validated with examples such as homogenizing binary, fiber-reinforced, and particle-reinforced composites. VAMUCH is found to be capable of handling various microstructure, complex material models, complex loading conditions, and complex loading paths. More sophisticated material models can be implemented into it.     

SINS／GPS动态观测数据的最优滤波算法

—面向大地测量应用，本文建立了ＳＩＮＳ／ＧＰＳ数据滤波的模型方程；研究了相应算法的实现方法；给出一种数值稳定性高，快速高效的滤波方法。     

Micromorphic continuum. Part III: Small deformation plasticity coupled with damage

Properties of the micromorphic theory proposed in Part II are discussed for the case of small deformations. Model responses for beam specimens under bending loading and plates with circular holes under tension loading are calculated by employing the finite element method. The results reported are concerned with the capabilities of the theory to predict size effects.     

Refined geometrically nonlinear formulation of a thin-shell triangular finite element

A refined geometrically nonlinear formulation of a thin-shell finite element based on the Kirchhoff-Love hypotheses is considered. Strain relations, which adequately describe the deformation of the element with finite bending of its middle surface, are obtained by integrating the differential equation of a planar curve. For a triangular element with 15 degrees of freedom, a cost-effective algorithm is developed for calculating the coefficients of the first and second variations of the strain energy, which are used to formulate the conditions of equilibrium and stability of the discrete model of the shell. Accuracy and convergence of the finite-element solutions are studied using test problems of nonlinear deformation of elastic plates and shells. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 160–172, September–October, 2007.     

叠加型A-F类随动强化模型塑性应变的数值计算法

以Chaboche随动强化模型为例,在M isses屈服准则及正交流动准则的前提下,推导了叠加型A rm-strong-F rederick(A-F)类随动强化模型塑性应变的数值计算法,联合利用四阶龙格-库塔法与径向返回法实现数值计算中的内部平衡迭代。同时推导了统一切向矩阵以便确定每一平衡迭代后的试算应变。利用AN SY S提供的U PF s将算法嵌入到AN SY S有限元程序,实现了叠加型A-F类随动强化模型塑性应变的数值计算,并利用四边形单元模拟了单轴循环加载时的棘轮应变,计算结果能够很好地与实验值吻合。     

单桩横向非线性运动地震响应简化分析

采用退化的Bouc-Wen模型和动力Winkler地基梁模型,建立了一个单桩横向非线性运动地震响应的简化分析模型,将自由场位移,作为沿桩轴均匀分布的非线性弹簧和频率相关的粘壶的支撑运动,利用运动响应因子的概念以及相应的计算方法,计算并讨论了地震运动过程中,单桩横向非线性运动地震响应问题。计算结果表明,对于单桩横向非线性运动地震响应问题的简化分析,所提出的模型在物理上是合理的。     

A new kinematic model for the closure equations of the generalized Stewart platform mechanism

The paper deals with the direct position analysis of the six degrees of freedom parallel manipulator known as generalized Stewart Platform Mechanism. When a set of actuator displacements is given the mechanism becomes a statically determined structure and the analysis solves for the closure of the structure. The governing equations are non-linear and many solutions are possible. Kinematic models reported in the literature relate to systems of six equations in six unknowns, which are solved numerically because of their complexity. Based on a novel approach, a new kinematic model of the structure is presented in this paper. It leads to a system of three equations in three unknowns that greatly reduces the computational burden. Finally, a case study has been reported.Paper presented at 2nd Int. Workshop on Advanced Robot Kinematics, Linz, Austria, 10–12 September, 1990.     

Circular welding problems with a crack

In this paper,the problem of an infinite plane with acircular hole welded by a nearly circular plate with a crackof different material is considered.The problem is tran-sformed into solving a certain boundary value problem ofanalytic functions and then reduced to solving a singularintegral equation along the crack.The formulas and somenumerical results of the factors of stress intensityfor the cases Mode Ⅰ and Mode Ⅱ are obtained at the endof this paper.     

Workspace and Optimal Design of a Pure Translation Parallel Manipulator

This paper presents a study of a pure translation three degrees of freedom fully-parallel manipulator, known as the Tsai manipulator. Based on the static analysis and on the determination of the singularity loci of the manipulator, criteria for the optimal geometric design of the manipulator for a given workspace free from singularities are proposed.