CAREER: Linking Processing Practice to the Performance of Materials in Design

职业：将加工实践与设计中材料的性能联系起来

• 批准号: 9702017
• 负责人: Matthew Miller
• 金额: $ 30万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-07-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9702017&HistoricalAwards=false
• 关键词: CAREER; Linking; Processing; Practice; Performance

9702017 Miller The overall objective of this project in materials processing / mechanics of materials is to establish tangible links between the processing of a material and its in- service performance. In general, the method which will be employed in both the educational and research components of the project is to use experiments to understand various aspects of material behavior and microstructural evolution. Guided by these observations, models for in-service performance which incorporate processing effects will be developed and implemented. The research component of this project, An Investigation of the Effects of Metal Forming Practice on In-Service Cyclic Performance, is motivated by the need for a unifying constitutive model framework for small strain cyclic plasticity which explicitly incorporates large strain processing-induced effects. It is well known that flat rolling produces strong internal structure gradients through the thickness of rolled plate material. In this project, the dependence of small strain inelastic cyclic deformation on processing induced initial structure (in the form of crystallographic texture and large strain dislocation structures) will be investigated by taking uniaxial and planar biaxial test specimens at various locations through the thickness of rolled aluminum plate. Both the mechanical response as well as the microstructural evolution will be monitored in these experiments and a determination made as to which of the large strain effects have the most profound influence on the subsequent small strain cyclic behavior. This information will then be incorporated into unifying small strain cyclic models which explicitly account for prior large strain metal forming episodes. While both involve inelastic strains, the large deformations incurred during a metal forming episode differ sharply from the small strain cyclic history which a component may encounter during its service life. These differences produce a discontinuity with respect to model structure. Large strain models place more of an emphasis on the characterization of slowly evolving material behavior due to processes such as crystallographic texture evolution while models for cyclic plasticity must capture quickly evolving phenomena such as that related to the nucleation and evolution of dislocation cells and lattice structures. Even though the internal structure produced during forming is distinct from small strain cyclic structure, the evolution of structure is continuous across the forming/service interface. It is this continuity of state evolution which offers hope for developing a unifying model framework. The initial model will build on a currently-existing crystal plasticity framework while the final modeling effort proposes an new micromechanical formulation. The educational plan, Designing with processed materials, shares the overall goal of bridging the processing / in- service design interface and focuses primarily on undergraduate and graduate curriculum development as well as laboratory development and implementation. A stronger emphasis on the effects of processing on design will be interjected into existing materials processing courses. On the undergraduate level, students will investigate experimentally what effects forming and thermal processing practice have on the properties of the processed material and how the microstructure evolves during processing On the graduate level, a new experimental course in materials processing is being developed taking the general theme of incorporating processing effects into design to a greater depth by investigating issues such as effects of deformation- induced anisotropy, rate and temperature dependence, instabiliti es, and superplasticity. Development of the instructional laboratory which serves the materials processing curriculum in Mechanical Engineering at Cornell consistent with the proposed curriculum changes is also proposed.

9702017米勒，该项目在材料处理 /材料机制方面的总体目标是在材料的处理及其服务性能之间建立切实的联系。 通常，将在项目的教育和研究组成部分中采用的方法是使用实​​验来了解材料行为和微观结构进化的各个方面。 在这些观察结果的指导下，将开发和实施纳入处理效果的在职绩效的模型。 该项目的研究组成部分是对金属形成实践对循环性能的影响的研究，这是由于需要对小应变环形可塑性进行统一的本构模型框架的启发，该模型明确结合了大型应变诱导的效果。 众所周知，扁平滚动会通过滚动板材料的厚度产生强大的内部结构梯度。 在该项目中，将通过在各种位置通过在各种位置通过滚动铝的厚度在各种位置进行单轴和平面双轴测试样品来研究小应变非弹性循环变形对加工引起的初始结构（以晶体学纹理和较大的应变脱位结构的形式）的依赖性。盘子。 在这些实验中，将监测机械响应以及微结构演化，并确定哪些大应变效应对随后的小菌株循环行为具有最深远的影响。 然后将这些信息纳入统一的小应变循环模型中，这些模型明确说明了先前的大型应变金属发作。 尽管两者都涉及非弹性应变，但在金属形成发作中产生的大变形与组件在使用寿命期间可能遇到的小菌株循环历史截然不同。 这些差异在模型结构方面产生了不连续性。 大型应变模型更多地强调了由于过程（例如晶体纹理演化）而引起的缓慢发展的材料行为的表征，而环状可塑性的模型必须捕获迅速发展的现象，例如与位错细胞和晶格结构的成核和演变相关的现象。 即使在形成过程中产生的内部结构与小应变循环结构不同，但结构的演变在整个形成/服务界面之间是连续的。 国家进化的连续性为开发一个统一的模型框架提供了希望。 最初的模型将建立在当前存在的晶体可塑性框架上，而最终建模工作则提出了一种新的微机械配方。 使用加工材料设计的教育计划共享了桥接加工 /内部设计界面的总体目标，并主要关注本科和研究生课程发展以及实验室开发和实施。 对加工对设计的影响的更加强调将插入现有的材料处理课程中。 在本科层面上，学生将在实验上研究形成和热处理实践对处理材料的特性以及微观结构在研究生水平上的处理过程中如何发展的效果，这是一项新的材料处理中的新实验课程，以一般为主题开发通过研究诸如变形诱导的各向异性，速率和温度依赖性，Intabiliti es和质超塑性等问题，将加工效应纳入设计中。 还提出了与拟议的课程更改一致的机械工程中材料处理课程的教学实验室的开发。