单试样法测金属材料JR曲线及其条件起裂值

在单试样卸载柔度法及三曲线法基础上,提出了一种更简便的测定金属材料JR曲线及其条件起裂值的单试样三点柔度法,并用该方法测定了1Cr1/2Mo钢、16MnR钢和WCF62钢的JR曲线及其条件起裂值,与标准的多试样法相比,误差均在工程许可范围内。     

单试样法测金属材料J_R曲线及其条件起裂值

在单试样卸载柔度法及三曲线法基础上 ,提出了一种更简便的测定金属材料 JR曲线及其条件起裂值的单试样三点柔度法 ,并用该方法测定了 1 Cr1 / 2 Mo钢、1 6Mn R钢和 WCF62钢的 JR曲线及其条件起裂值 ,与标准的多试样法相比 ,误差均在工程许可范围内     

边界变换法求边界近傍的应力

本文介绍的边界变换法,可以避免边界层效应,解决边界近傍的应力(或位移)的准确计算问题.     

单试样三曲线法测定J积分阻力曲线及条件起裂值

用单试样三曲线法测定了16MnR 钢和某一焊缝金属的 J 积分阻力曲线及其条件起裂值,与标准的多试样测定结果基本吻合.实验表明,单试样三曲线的关联分析反映了带裂纹的三点弯曲试样的宏观断裂物理过程,裂纹的延性扩展符合幂函数规律.     

Computational model for short-fiber composites with eigenstrain formulation of boundary integral equations

A computational model is proposed for short-fiber reinforced materials with the eigenstrain formulation of the boundary integral equations （BIE） and solved with the newly developed boundary point method （BPM）. The model is closely derived from the concept of the equivalent inclusion Of Eshelby tensors. Eigenstrains are iteratively determined for each short-fiber embedded in the matrix with various properties via the Eshelby tensors, which can be readily obtained beforehand either through analytical or numerical means. As unknown variables appear only on the boundary of the solution domain, the solution scale of the inhomogeneity problem with the model is greatly reduced. This feature is considered significant because such a traditionally time-consuming problem with inhomogeneity can be solved most cost-effectively compared with existing numerical models of the FEM or the BEM. The numerical examples are presented to compute the overall elastic properties for various short-fiber reinforced composites over a representative volume element （RVE）, showing the validity and the effectiveness of the proposed computational modal and the solution procedure.     

Two-dimensional polynomial eigenstrain formulation of boundary integral equation with numerical verification

The low-order polynomial-distributed eigenstrain formulation of the boundary integral equation (BIE) and the corresponding definition of the Eshelby tensors are proposed for the elliptical inhomogeneities in two-dimensional elastic media. Taking the results of the traditional subdomain boundary element method (BEM) as the control, the effectiveness of the present algorithm is verified for the elastic media with a single elliptical inhomogeneity. With the present computational model and algorithm, significant improvements are achieved in terms of the efficiency as compared with the traditional BEM and the accuracy as compared with the constant eigenstrain formulation of the BIE.     

二维多项式本征应变边界积分方程及其数值验证

针对弹性介质中的椭圆形异质体,给出了低阶多项式分布的二维本征应变边界积分方程和相应的Eshelby张量的定义．以边界元分域法为参照,利用含有单个异质体的弹性介质对提出的计算模型和算法进行了数值验证．结果表明该算法取得较大的改进,其计算效率高于传统的边界元法,计算精度则高于采用常数本征应变的计算模型．     

短纤维复合材料的本征应变边界积分方程计算模型

提出了短纤维复合材料的本征应变边界积分方程计算模型,并采用新发展的边界点法进行了求解.模型依据Eshelby等效夹杂物的概念并借助Eshelby张量,采用迭代方法来计算基体中各种性能短纤维的本征应变,其中所需的Eshelby张量不难通过解析或数值方法获得.由于未知量只出现在边界上,与已有的有限元和边界元模型相比,提出的计算模型可极大地减小异质体问题的求解规模,提高计算效率.通过数值算例计算了代表性体积单元上各种短纤维复合材料的整体弹性性能,验证了计算模型和求解方法的正确性和有效性.     

边界元初应变法弹塑性分析的预测—校正迭代法

本文提出预测—校正迭代方法,使边界元初应变法的弹塑性分析可以适用于包括非强化材料在内的各种塑性流变特性的材料。其原理为利用结构因子,即内部单元对其初应变的弹性响应来校正每步增量载荷作用下预测的塑性应变增量,使塑性区的等效应力逐步返回到屈服面上,在中型计算机上对均匀拉伸的双V缺口平板按理想弹塑性材料进行了弹塑性分析,计算结果与有限元法的结果十分一致。但计算时间大为缩短。     

COD阻力曲线的单试样三曲线分析法

在三曲线分析的基础上,提出了一种新的单试样测定 COD 阻力曲线的方法和步骤,编制了计算机应用程序。用三曲线法测定了 C—Mn 钢,Cr-Mo 钢和一种焊缝金属的 COD 阻力曲线,与标准的多试样法实验结果符合较好。该方法使用方便经济。有推广使用的价值。