Three-Dimensional Dynamic Contact Problem for an Elliptic Crack Interacting with a Normally Incident Harmonic Compression–Expansion Wave

The paper deals with the three-dimensional dynamic problem for an elliptic crack interacting with a normally incident harmonic compression–expansion wave, considering the contact interaction of the crack faces. An asymmetric solution is obtained using an iteration algorithm developed earlier. Numerical results are presented     

裂尖超钝化:实验、理论与数值模拟

本文报道了在改性聚丙烯裂尖平面应变段发生超钝化的实验发现。利用环向冷拉模型,可说明裂尖超钝化的形成取决于冷拉传播速率与加载率之比。裂尖超钝化可使材料韧性,尤其是冲击韧性的改善,达到一个新的水平。本文在超弹性-粘塑性各向异性损伤的有限变形本构模型下进行了详尽的数值计算。模拟结果成功地再现了裂尖超钝化的基本特征。     

复合型表面裂纹疲劳门槛应力的估算

表面裂纹是工程构件常见的缺陷，由于实验数据的缺乏及其他困难，断裂力学应用于表面裂纹的疲劳扩展，其经验和成果还十分有限。本文利用复合型断裂准则，对圆棒试样表面小裂纹的门槛应力进行分析和估算，得到了较满意的结果。     

试验确定自增强圆筒的表面裂纹K1因子和疲劳扩展规律

本文提供了一种可以进行自增强处理的圆筒试样,通过实验用柔度法确定了该试样的表面裂纹的应力强度因子,介绍了含表面裂纹试样的柔度测试技术,导出了柔度与表面裂纹尖端前缘各点的应力强度因子的关系式,该式可作为各种含表面裂纹试样柔度法测表面裂纹 K_1因子的参考,本文还测定了不同自增强程度下,自增强圆筒的表面裂纹疲劳扩展规律。     

压电材料平面应力状态的直线裂纹问题一般解

研究了含直线裂纹系的压电材料平面应力问题单个裂纹和双裂纹问题的封闭解答表明，在裂纹尖端，应力、电场强度和电位移有１／２阶的奇异性并与前人结果比较了产生电场奇异性的物理因素     

停歇对疲劳裂纹扩展超载迟滞效应影响的研究

本文用 16 Mn和 A 537 两种普通低合金钢试件,较系统地研究了停歇对疲劳超载迟滞效应的影响。研究表明,疲劳载荷中的停歇对超载迟滞效应有明显影响,其影响的程度大小与停歇时的载荷 P_H,停歇时间 t_H 等因素密切相关;不但可能使试件的疲劳寿命减少,也可能使试件的疲劳寿命增加。在工程结构疲劳设计、分析及应用超载迟滞效应时应予以注意。     

刚性元方法和块状岩体稳定性分析

本文提出的刚性元方法是一种数值分析方法,它将变形体离散为一些刚性块体(剐性元)和块体之间的可变形薄层(节理元)的组合体,在各种载荷条件下求出块体的运动以及薄层的变形和应力分布。本文联合岩石系统的失稳准则来使用刚性元方法,成功地研究了块状岩体的稳定性问题。计算实例表明,本文提出的方法可以正确地反映块状岩体的失稳机制,是一种合理和可行的岩体稳定性分析手段。     

疲劳裂纹扩展门槛值的研究进展

Ⅰ.引言 大量的研究和疲劳裂纹扩展的试验表明,对于存在一定尺寸裂纹及缺陷的材料或构件,只有当裂纹尖端的应力强度因子达到或超过某一值时,裂纹才会在交变应力的作用下扩展。当裂纹尖端的应力强度因子小于这一值时,裂纹在交变应力作用下不发生扩展。这个应力强度因子值,就是界限应力强度因予幅值△K_(th),在疲劳研究中称为裂纹扩展的门槛值。 门槛值△K_(th)和疲劳裂纹扩展速率da/dN一样,是反映带裂纹或缺陷构件抗疲劳性能的     

Scaled-boundary method in electroelasticity of thin plates

The paper discusses the scaled-boundary method as applied to electroelastic problems. As an example, the stress-intensity factor is calculated for a thin rectangular piezoelectric plate with an edge crack __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 7, pp. 124–134, July 2006.     

Analysis of energy release rate for composite delaminated cylindrical shells subjected to axial compression

In this paper, the postbuckling governing equations and the analytical expression of the energy release rates associated with delamination growth in a compression-loaded cylindrical shell are derived by using the variational principle of moving boundary and the Griffith fracture criterion. The finite difference method is used to generate the postbuckling solutions of the delaminated cylindrical shells, and with these solutions, the values of the energy release rates are determined. In simulational examples, the effects of a wide range of parameters, such as delamination sizes and depths, boundary conditions, geometrical parameters, material properties and laminate stacking sequences on the energy release rates of axisymmetrical laminated cylindrical shells are intensively discussed.The English text was polished by Yunming Chen.