CAREER: Cyclic Plasticity and Fatigue Life of Small-Scale Metal Structures

职业：小型金属结构的循环塑性和疲劳寿命

• 批准号: 9876261
• 负责人: Richard Vinci
• 金额: $ 30.43万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9876261&HistoricalAwards=false
• 关键词: CAREER; Cyclic; Plasticity; Fatigue; Life

9876261VinciTwo objectives of this program on small-scale metallic structures are to understand plastic behavior related to cyclic loading and to identify mechanisms that determine fatigue lifetimes for low-and high-cycle regimes. Both cyclic plasticity and fatigue are evaluated in terms of sample state, particularly thickness and microstructure. The effects of testing conditions, including strain rate, ambient atmosphere and temperature, are evaluated. Emphasis is placed on identifying the key parameters that differentiate the behavior of freestanding metal thin films from that of bulk metals and that of thin metal films adhered to substrates. Unique apparatus under development fits into the specimen chamber of an Environmental Scanning Electron Microscope equipped with an Orientation Imaging Microscopy unit. This arrangement allows in-situ monitoring of surface morphology and microstructure during testing. Uniaxial tensile samples are used for simplicity of testing and analysis. Metal specimens are patterned at the Stanford Nanofabrication Facility using fabrication techniques developed in a preliminary study. Materials systems include aluminum (a FCC low melting point metal), iridium (a high melting point FCC metal), and molybdenum (a high melting point BCC metal). Improved understanding of thin film mechanical behavior will be transmitted to students through three paths: training of graduate and undergraduate research assistants, development of a specialized graduate mechanical behavior course, and integration of thin film mechanical behavior into the undergraduate curriculum.%%%Physics-based mechanical behavior models will allow dynamic modeling of device behavior and reliability for performance optimization. Technologies that will benefit include MEMS products such as high frequency RF switches and resonators for precision electronics. Relevant mesoscale applications include devices such as miniature aircraft and gas turbines for power generation. The target audience for this work includes university researchers, developers of design software, small-scale device manufacturers, and endusers of this technology.***

9876261Vinci小尺度金属结构的这一计划的两个目标是了解与循环载荷有关的塑性行为，并确定确定低周和高周疲劳寿命的机制。 循环塑性和疲劳都是根据试样状态，特别是厚度和微观结构来评价的。 测试条件的影响，包括应变速率，环境气氛和温度，进行了评估。 重点放在确定的关键参数，区分独立的金属薄膜的行为，从散装金属和薄金属膜粘附到基板。 正在开发的独特设备适合环境扫描电子显微镜的样品室，配备了定向成像显微镜单元。 这种布置允许在测试期间原位监测表面形态和微观结构。 单轴拉伸样品用于简化测试和分析。 金属标本图案化在斯坦福大学纳米工厂使用制造技术开发的初步研究。 材料系统包括铝（FCC低熔点金属）、铱（高熔点FCC金属）和钼（高熔点BCC金属）。 提高对薄膜力学行为的理解将通过三条途径传递给学生：培养研究生和本科生研究助理，开发专门的研究生力学行为课程，以及将薄膜力学行为整合到本科课程中。基于物理的机械行为模型将允许对设备行为和可靠性进行动态建模，以实现性能优化。 受益的技术包括MEMS产品，如用于精密电子产品的高频RF开关和谐振器。 相关的中尺度应用包括诸如微型飞机和用于发电的燃气轮机等装置。 这项工作的目标受众包括大学研究人员、设计软件开发人员、小规模设备制造商和这项技术的最终用户。