【作者】 张超；

【导师】 孙胜；

【作者基本信息】 山东大学 ， 材料加工工程， 2005， 硕士

【摘要】 随着各种先进的电子仪器的发展,以及力学在金属学中的更为广泛的应用,科学家可以对金属微观结构进行越来越深入的研究。 目前对于金属塑性行为的研究更多的是从宏观方面去研究。而对于微观状态下金属发生塑性变形的机理的研究还不够完善。金属的塑性变形行为与材料的细观结构是密切相关的,而如何利用这些材料的细观信息为材料成形领域所服务就成为了一个新的热点研究领域。晶体塑性变形理论正是解决这一问题的基础。晶体塑性变形理论构建了材料的宏观变形和微观变形的桥梁,为我们更细致的分析,研究材料的宏观变形提供了理论依据。 晶体塑性成形理论涉及到多方面的问题。其中最基本,最基础的就是微观状态下晶体的位相分布情况。本文首先阐述了晶体的初始分布情况,涉及了晶粒的大小,形状和位相情况。对于晶体的位相分布情况进行模拟有多种数学模型,本文采用了Voronoi图数值模拟方法。文章简要阐述了利用Voronoi图的数学和几何性质,并提出了voronoi图的算法。 针对目前大部分的学者还都是应用Taylor模型进行本构关系的研究,但是对于Taylor模型中的滑移机制在国内外的科技文献中还没有比较详尽展开讨论与介绍的问题,本文着重对晶体塑性变形的几何学和运动学理论作了详细的阐述。其中重点以Taylor模型阐述了晶体的滑移机理与运动机制。首先阐述了判断哪些滑移系先发生滑移的Schmid定律和最小塑性功原理。其次阐述了最基本的单晶体单滑移系滑移机制,单晶体的多滑移系滑移机制,最后阐述了多晶体滑移系滑移机制。 本文在总结和研究前面晶体滑移运动几何学理论的基础上,建立了晶体滑移运动几何学的模型。并采用Fortran PowerStation 4.0为开发工具,在Windows 2000环境下以晶体滑移运动几何学模型为基础,对该模型的运动几何学进行数值模拟分析。以滑移剪应变,拉伸轴方向向量,晶体的边界条件作为已知量,利用晶体滑移几何学的理论知识计算出晶体变形后的新的边界坐标以及整个拉伸轴的伸长量。本文可以同时输出所涉及到的各个中间变量。本模型有利于更好的理解晶体滑移变形理论,也可以作为后续程序开发的基础。更多还原

【Abstract】 With the development of all kinds of electronic instruments and the mechanics widely used in metallography ,scientists can study further the microstructure of metals deeply.Nowdays more attition about metallic plastic deformation is paid to the study of the macrostructure of metals. The behaviour of metal plastic deformation is correlative with its microstructure intimately. But how to utilize these information of metallic microstructure to help to study the mechanism in metal forming is becoming a hot spot. The theory of crystal plastic deformation is the key for the door of resolving this problem. As a bridge between macroscopical deformation and microcosmic deformation ,it provides us with theoretical foundation for further research.The theory of crystal plastic deformation involves several facets.First of all ,this paper discusses initial distribution ,size and shape of crystal ;it introduces the application of Voronoi body-create method to simulate crystal initial distribution. At the same time ,it puts forward Voronoi graph arithmetic.At present, a majority of scholars make use of Taylor model to study constitutive laws,but there is no detailed introduction about slip mechanism based on Taylor model in domestic and foreign literature up to now.This paper mainly introduces geometry and kinetics of crystal plastic deformation.The most important content is slip mechanism and kinetics mechanism.These comtents include several parts:the Schmid law and the least plastic energy law judging which silp system will slip first;the mechanicsm about one slip system of single crystal; the mechanicsm about several slip systems of single crystal; the mechanicsm about several slip systems of polycrystal.This paper establishes a crystal-slip kinetics and geometry model based on the theory of crystal-slip kinetics and geometry.The develop-tools software is Fortran PowerStation and the develop platform is Windows 2000.In this model , the slip-shearing strain,the extension axis orientation-vector, boundary condition comprises the knownquantity.We get new boundary condition and new extension of the extension axis by the theory of crystal-slip kinetics and geometry.At the sametime ,some secondary data is also available if we need.This model is helpful for us to understand the theory of crystal-slip kinetics and geometry;we can regard this model as the basis of further developing program.In this paper,we put forward Voronoi graph arithmetic to simulate crystal initial distribution and analyze the slip mechanism based on Taylor model.There will be usefull significance for the study of mechanism of metal plastic deformation.更多还原