Non-Associated Plastic Flow of Ductile Single Crystals

延性单晶的非缔合塑性流动

• 批准号: 9900131
• 负责人: John Bassani
• 金额: --
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9900131&HistoricalAwards=false
• 关键词: Non; Associated; Plastic; Flow; Ductile

The proposed research focuses othe relationship between the atomic configuration of dislocation cores and macroscopic plastic flow. Our principal goals are 1. to develop physically based continuum constitutive relatins that account for complex phenomena arising form non-planar dislocaiton core structures and can be utilized, for example in finite element analyses and in hydrocode simulaitons. We will consider a range of technologically important materials from different crystal classes andunder conditions that arise in both deformation processes and the response of componenets subjected to mechanical loading. Common signatures of core effects are unexpected deformation modes and slip geometerics, stron and unusual dependence of flow stresses on crystal orientation and temperature, and most prevalently, a break-down of 'Schmid's law' due tothe dependence of slip on non-guide componenets of stresses. At the same time, these core effects may critically affect macroscopic flow of polycrystals, for example, significantly influcencing the physically based sontitutive models that incorporate effects of non-glide stresses on multiple-slip deformation is the focus of the proposal. To do that solely based upon experiments is difficult if not impossible, whereas atomistic simulations can directly reveal those characteristics of dislocations that are responsible for complex macroscopic behaviors. These in turn, depend on bothe the crystal structure and bonding characteristics of a given material. Strain localization has been shown to be quite sentitive to multiple-slip hardening and non-glide stress affects. We propose to investigate localized deformatin both because of its inherent importance provides a chalenging test of the new models.

本文的研究重点是位错核的原子构型与宏观塑性流动之间的关系。 我们的主要目标是1。 开发基于物理的连续体本构关系，该关系解释了由非平面位错核结构引起的复杂现象，并且可以用于例如有限元分析和流体代码模拟。 我们将考虑一系列技术上重要的材料，这些材料来自不同的晶体类别，并且在变形过程和受到机械载荷的组件的响应中出现的条件下。 核心效应的共同特征是意想不到的变形模式和滑移几何学，流动应力对晶体取向和温度的强烈和不寻常的依赖性，最重要的是，由于滑移对应力的非导向分量的依赖性，“施密德定律”被打破。 同时，这些核心效应可能会严重影响多晶体的宏观流动，例如，显着影响的物理为基础的sontentive模型，将非滑移应力的影响，多滑移变形是该建议的重点。 仅仅基于实验来做到这一点是困难的，如果不是不可能的话，而原子模拟可以直接揭示那些负责复杂宏观行为的位错特征。 这些又取决于给定材料的晶体结构和键合特性。 应变局部化对多次滑移硬化和非滑移应力的影响十分敏感。 我们建议研究局部变形，因为它的内在重要性提供了一个新的模型的挑战性测试。