QQ客服 官方微博 反馈留言

题名	微裂纹细观损伤理论
学位类别	博士
答辩日期	1999
授予单位	中国科学院研究生院
授予地点	北京
导师	王自强
关键词	细观损伤理论 微裂纹 相互作用 有效模量 损伤演化过程 micromechanical damage theory microcracks interaction effective moduli damage evolution process
学位专业	固体力学
中文摘要	材料的宏细观破坏理论是当前固体力学和材料科学研究的一个重要课题。本文在对连续损伤理论和细观损伤理论进行评述的基础上，着重研究了脆性材料中微裂纹细观损伤问题。本文建立了一套完整的细观损伤理论来分析二维多裂纹体问题。该理论的基本方法是基本解叠加法，此方法直接考虑了微裂纹之间的相互作用以及有限边界的影响。通过叠加原理，使在裂纹面和外边界满足边界条件，用边界配置法化控制方程组为线性方程组，进行数值求解。本文以裂纹密度为参量，针对微裂纹随机分布和平行分布两种情况，计算了无限大体中代表性体元（VRVE）和多裂纹有限体的有效弹性模量。数值计算结果表明，本文所用方法具有统一与直能的优点，采用此法所得模量与试验结果吻合，在处理多裂纹体问题时计算效率高、精度好，对求解多裂纹问题非常有效。此外，通过建立微裂纹晶内扩展准则和穿晶扩展准则，分析了微裂纹扩展连接直至裂纹形成、扩展这一全过程的细观力学行为，对微裂纹的损伤演化过程进行了直接模拟，计算了含微裂纹矩形板的宏观应国变关系曲线。本文进一步提出了三维微裂纹相互作用的数学分析方法 — 扁球坐标和位移函数法，并采用边界配置法或裂纹面面力平均化方法进行求解。数值结果表明，扁球坐标和位移函数法分析三维微裂纹的相互作用问题是有效可行的。最后，本文提出了埋入基体的镶嵌体胞模型，建立了计算非均质体有效弹性模量的解析表达式。该式从理论上讲是严格的，且具有形式简单、内涵丰富及有效弹性模量能显式表达等优点。针对球体含球形夹杂、裂纹及旋转扁球体含球形夹杂、裂纹等不同体胞结构计算了其有效弹性模量，并与其他细观力学方法所得结果进行了比较。本文还将埋入基体的镶嵌体胞模型进行了发展，研究了二相颗粒复合材料的弹塑性本构关系（基体为弹性而颗粒为塑性材料），计算了球体含球形颗粒用旋转扁球体含扁球状颗粒两种体胞结构的宏观应力 - 应变曲线。
索取号	29875
英文摘要	The macro- and micro-failure theory of materials is a very important research subject of solid mechanics and material science. In this thesis, both phenomenological and micromechanical damage models are reviewed. Attention is focused on the microcracks micro-damage of brittle materials. A rather complete micromechanical damage theory is established for solving the plane elasticity problem of finite solids with multiple microcracks. Analysis is based on a superposition of the basic solutions. The method directly accounts for the interactions between different microcracks and the effect of outer boundary of a finite plate. By using the traction free conditions on each crack surface and resultant force relations along outer boundary, a set of governing equations is formulated. The governing equations are solved numerically on the basis of a boundary collocation procedure. The effective Young's moduli for randomly oriented cracks and parallel cracks are evaluated for the representative volume element (RVE) with microcracks in infinite media and rectangular plates with microcracks. The numerical results are compared with those from various micromechanics models and experimental data. These results show that the present method provides a direct and efficient approach to deal with finite solids containing multiple microcracks. In addition, the microcracks evolution process is simulated through the use of the criterions of intergranular growth and transgranular growth. The stress-strain relations are obtained from the micromechanics analysis. A method called oblate spheroidal coordinates and displacement functions is presented which can be used to analyze the interactions among three-dimensional microcracks. The boundary collocation procedure and the average method of crack-line tractions are used for solving the governing equations. The numerical results show the present method provides a direct and efficient approach to deal with three-dimensional solids containing multiple microcracks. In this thesis, an embedded cell model is presented to obtain the effective elastic moduli for three-dimensional two-phase composites which is an exact analytic formula without any simplified approximation and can be expressed in an explicit form. For the different cells including spherical particle and crack in sphere and oblate spheroid matrix, the effective elastic moduli are evaluated and the results are compared with those from various micromechanics models. Further, the embedded cell model is developed to obtain the elastic-plastic stress-strain relations of two-phase particulate composites. In this paper, the matrix is elastic and the particle is plastic. The elastic-plastic stress-strain relations are obtained for spherical cells and oblate spheroid cells.
语种	中文
学科主题	固体力学
公开日期	2009-04-13 ; 2009-08-25
出处	[博士论文].北京.中国科学院力学研究所,1999
内容类型	学位论文
源URL	[http://dspace.imech.ac.cn/handle/311007/24258]
专题	力学研究所_力学所知识产出(1956-2008)
推荐引用方式 GB/T 7714	. 微裂纹细观损伤理论[D]. 北京. 中国科学院研究生院. 1999.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。