1、 界面位错论文：基于界面位错理论的界面断裂分析【中文摘要】随着社会科学技术的不断发展,在工程制造中对材料结构的质量要求也越来越高,而界面广泛存在于这些材料结构中,就材料破坏研究而言,由于材料本身的差异性使得断裂力学的应用在合理性方面出现问题,具体表现为界面裂纹尖端附近出现应力振荡与裂纹表面材料互相嵌入现象,这不符合物理事实。为了克服这一不足,并获得对界面断裂现象的合理描述与解释,本论文利用积分交换方法获得界面位错的应力场解,并通过与断裂力学以往的研究结论相比较,进而用正态分布函数取代 Dirac 的函数,使得断裂力学基本解在用于界面分析时在位错解层次上避免了应力振荡奇异性。这样就保留了可做为奇
2、异性的 Cauchy 核解结构特征,并结合了引起振荡项的点力项的物理意义,用分布函数来取代相应的 Dirac 函数就获得了稳定的断裂参量表示。之后,基于界面位错基本解建立了界面断裂模型,把断裂力学变值问题归结为第一类奇异积分方程,避免了应力震荡奇异性,获得了稳定的点力分布区域尺寸,并应用该尺寸处理界面断裂问题,结果表明断裂混合度的变化特征符合实验结论。所作得的主要工作如下:运用积分交换方法求得界面位错的应力场解,根据界面位错与裂纹开裂物理图象的一致性,在位错基本解基础上赋予 Dirac 函数表征的单位点力以数学解释与物理解释,使得断裂力学基本解在用于界面分析时在位错解层次可以避免了应力振荡奇异
3、性。在界面位错塞积模拟界面裂纹开展时,是通过用数值计算模拟来获得稳定的正态分布参数 与裂纹长的对应关系,结果为裂纹长的千分之七左右。采用正态分布参数 解决界面断裂问题,可以获得稳定的断裂混合度,数值结果会表明该模型可用于处理界面断裂问题,这样既可以避免使用第二类奇异积分方程,也可以避免在以往界面模型中过多地使用物理假设带来的复杂性。【英文摘要】With the social development of science and technology, manufacturing in engineering materials to the quality requirements of th
4、e structure more and more is also high,interfaces are widely existing in all kinds of research objects. It is contrary to the fact that applications of fracture mechanics will present some problems which are stress oscillating and tumbling in crack surface material as material destruction in the res
5、earch for the difference of materials. In order to overcome this shortcoming, to get the reasonable description and explanation for the interface fracture, in this paper, the stress field of interface dislocation is obtained by integral transformation, the singularity of stress oscillating is avoid
6、by comparing with conclusions we have of fracture mechanics, replacing Dirac function with normal distribution function when the basic solution of fracture mechanics is applied in interface analysis. The character of Cauchy kernel solution are retained, combining physical significance of the oscilla
7、ting term, so stable fracture parameters is got by replacing Dirac function with normal distribution function. Then the fracture mechanics boundary value problems are changed into the first singular integral formula based on the basic solution of interface dislocation. Avoiding the singularity of st
8、ress oscillating, and getting the stable domain of point force, the results show that the variation of fracture parameter is agreement with the experiment data by the domain to solute the interface fracture problems. The main contributions are as follows:The stress field of interface dislocations is
9、 obtained by using integral exchange method .According to the consistent of interface dislocation and physical picture of crack, in the basic solution the point force using Dirac function is given to the physical interpretation and mathematical explanation, which makes the fundamental solution of fr
10、acture mechanics analysis be used for the interface level of the dislocation solution, avoid the stress oscillatory singularity.Dislocation pileup with a simulation of the interface crack initiation behavior, is obtained by numerical simulation the relations of stable normal parametersand the crack
11、length,which is seven thousandths of the Crack length nearby.The problems of interface fracture are soluted by using normal distribution parameter. Fracture mixing degree is obtained. Numerical results show that the model can be used to solve the interfacial fracture problem. And it doesnt only avoi
12、d using the second class of singular integral equations, but also avoid the complexity which is brought by interface model which has been obtained by using excessive physical assumptions.【关键词】界面位错 应力场 奇异性方程 断裂模型 断裂混合度【英文关键词】interface dislocation stress field singularity equation fracture models frac
13、ture mixing degree【目录】基于界面位错理论的界面断裂分析 摘要 4-5 ABSTRACT 5 第 1 章 绪论 8-15 1.1 课题背景 8-9 1.2 本课题研究的目的及意义 9-10 1.3 国内外研究现状 10-14 1.4 本文主要研究内容 14-15 第二章 基于界面位错解的界面断裂模型 15-22 2.1 引言 15 2.2 界面位错的求解 15-19 2.3 界面位错应力场分析 19-21 2.4 本章小结 21-22 第三章 基于修正模型的界面断裂分析 22-35 3.1 引言 22 3.2 界面断裂模型 22-23 3.3 奇异积分方程的解 23-25 3.4 应力强度因子与应变能释放率 25-26 3.5 数值结果与讨论 26-34 3.6 本章小结 34-35 结论 35-36 参考文献 36-40 致谢 40
