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

9702017米勒的 整体 本项目的目标是 材料加工/材料力学是在材料的加工和其使用性能之间建立有形的联系。 一般来说，该项目的教育和研究部分将采用的方法是使用实验来了解材料行为和微观结构演变的各个方面。 指导 通过 这些观察，模型， 将开发和实施包含处理效果的在职绩效。 本项目的研究部分，金属成形实践对在役循环性能影响的调查，是出于对统一本构关系的需要。 小应变模型框架 循环塑性 它明确地包含了大量的 应变加工引起的效应。 众所周知，平轧在轧制板材的整个厚度上产生强烈的内部结构梯度。 在本项目中，小应变非弹性循环变形对加工诱导初始结构（以晶体学形式）的依赖性 织构和大应变 位错结构）将通过在轧制铝板厚度的不同位置处取单轴和平面双轴试样来研究。 在这些实验中将监测机械响应以及微观结构演变，并确定哪些大应变效应对随后的小应变循环行为具有最深远的影响。 然后，这些信息将被纳入统一的小应变循环模型，明确占以前的大应变金属形成插曲。 虽然两者都涉及非弹性应变，但在金属成形过程中产生的大变形与小变形有很大不同。 应变循环历史是指部件在其使用寿命期间可能遇到的应变循环历史。 这些差异导致模型结构的不连续性。 大应变模型更多地强调由于过程而缓慢演变的材料行为的表征 等 作为晶体织构的演变，而循环塑性模型必须捕捉快速演变的现象，如有关的位错细胞和晶格结构的成核和演变。 尽管在成形过程中产生的内部结构与小应变循环结构不同，但结构的演变在成形/服务界面上是连续的。 正是这种国家演变的连续性， 希望 建立统一的模型框架。 初始模型将 建立在现有的晶体塑性框架，而最终的建模工作提出了一个新的微观力学配方。 教育计划，设计与加工材料，共享的总体目标，桥接处理/在服务 设计 接口和 重点 主要 本科生和研究生课程的发展，以及实验室的发展和实施。 一 在现有的材料加工课程中，将更强调加工对设计的影响。 上 本科 平整， 学生 将 通过实验研究成形和热加工实践对加工材料性能的影响以及加工过程中微观结构的演变。一个新的材料加工实验课程正在开发中，通过调查以下问题，将加工效果更深入地融入设计的总主题，变形诱导效应 各向异性， 速率和温度 依赖性、不稳定性和超塑性。 教学的发展 的实验室 服务于 的 材料加工课程在机械工程在康奈尔大学一致的建议课程的变化也提出了建议。

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.