Mismatch Plasticity Via Pressure Cycling

通过压力循环实现塑性失配

• 批准号: 9705558
• 负责人: Glenn Daehn
• 金额: $ 65万
• 依托单位: Ohio State University Research Foundation -DO NOT USE
• 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: 1997-08-15 至 2000-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9705558&HistoricalAwards=false
• 关键词: Mismatch; Plasticity; Via; Pressure; Cycling

9705558 Daehn This integrated program of experimentation, simulation, and analysis is aimed at a fundamental understanding of powder consolidation by pressure cycling. The FRG investigates mismatch plasticity in heterogeneous powder systems induced by cyclic pressure application which induces an equivalent effect via Eshelby mismatch, albeit at rates suitable for mass production. Recent experiments demonstrate the dramatic impact of cyclic pressure on consolidation densities and the even greater impact on green compact strengths. The former allows processing of powders with high reinforcement fractions while the latter introduces the possibility of secondary processing of highly reinforced green compacts, both of which are very challenging with traditional processing. A series of 2-D and 3-D experiments using real and idealized powders are compared with analysis and finite element modeling (FEM). A robust contact algorithm for large-strain FEM is developed for application to a wide range of micro-mechanical simulation. For each combination of experiment and simulation, compact densities and strengths are compared as functions of cyclic pressure application. An improved understanding of mismatch plasticity via pressure cycling and a robust numerical method for simulating micromechanical problems involving real contact properties should be developed. These advances eliminate the need for questionable assumptions inherent in today's theories and simulations. %%% The impact to the FRG is in several technological areas. Results from the project will demonstrate methods for producing powder-processed parts with greater consistency and shape accuracy, with or without secondary processing. New techniques for processing reinforced metal matrix composites via powder metallurgical routes will be identified. ***

小行星9705558 这个实验，模拟和分析的综合方案的目的是通过压力循环粉末固结的基本理解。 联邦德国研究不匹配塑性在非均匀粉末系统引起的循环压力的应用，通过Eshelby不匹配引起的等效效果，虽然在适合大规模生产的速度。 最近的实验证明了循环压力对固结密度的显著影响，并且对绿色压坯强度的影响更大。 前者允许加工具有高增强分数的粉末，而后者引入了高度增强的绿色压坯的二次加工的可能性，这两者对于传统加工都是非常具有挑战性的。 使用真实的和理想化粉末的一系列2-D和3-D实验与分析和有限元建模（FEM）进行比较。 本文提出了一种适用于大应变有限元分析的稳健接触算法。 对于实验和模拟的每一个组合，压实密度和强度作为循环压力应用的函数进行比较。 通过压力循环和一个强大的数值方法来模拟微观力学问题，涉及真实的接触性能的失配塑性的更好的理解，应开发。 这些进步消除了对当今理论和模拟中固有的可疑假设的需要。 对联邦德国的影响体现在多个技术领域。 该项目的结果将展示生产具有更高一致性和形状精度的粉末加工零件的方法，无论是否进行二次加工。 将确定通过粉末冶金途径加工增强金属基复合材料的新技术。 ***