Multi-Scale Experimental Investigation of Sliding Friction

滑动摩擦的多尺度实验研究

• 批准号: 9908218
• 负责人: Steven Glaser
• 金额: $ 23.03万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-10-01 至 2002-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9908218&HistoricalAwards=false
• 关键词: Multi; Scale; Experimental; Investigation; Sliding

***9908218GlaserEngineers have always relied on rate- and state-dependent constitutive models(behavioral criteria). Recent advances by the condensed-matter physicscommunity have resulted in hypothetical theoretical mechanisms responsible forfrictional resistance to sliding. These models explain behaviors from angstromscale to kilometers-long earthquake dislocations, and provide a theoreticalframework for understanding material creep as well as self-healing slip on theSan Andreas fault. Since there has been little direct experimental proof thatthe posited fundamental physical mechanisms indeed are at work, the PIs willleverage their experimental and interpretive ability to image thesemicro-mechanisms. Given that the fundamental kinematics of frictional junctionsresults in production of phonons (vibrational, hence acoustic, energy), thecombination of quantitative acoustic emission and waveform inversion isuniquely able to image these kinematics. Glaser has developed surface andembeddable sensors proven capable by NIST of measuring picometer displacementsfrom 10 kHz to 1 MHz to within 3 dB. Studies show that the dynamic recordtransduced by these sensors match the theoretical kinematic waveformsremarkably well, allowing whole-waveform inversion for source kinematics ratherthan single-point moment tensor inversion. The results of this project will further science and engineering on severallevels. Fundamental understanding of the physical mechanisms behind slidingfriction, leading to improvement of basic understanding of the physical world. This will help refine current empirical understanding of friction and allowgreat improvement in mechanical design from nanomachines to sub-kilometer-scalestructures. In addition, fundamental questions about kilometer-scaleearthquake source mechanisms will be answered, in particular the issuessurrounding the notion of self-healing slip, thereby leading to an improvedunderstanding of the earthquake dislocation mechanism, and ultimately improvedseismic safety.***

* 9908218工程师一直依赖于速率和状态相关的本构模型（行为准则）。凝聚态物理学界的最新进展导致了对滑动摩擦阻力负责的假设理论机制。这些模型解释了从埃尺度到几秒钟长的地震位错的行为，并为理解圣安德烈亚斯断层上的材料蠕变和自愈滑动提供了理论框架。 由于几乎没有直接的实验证据证明假设的基本物理机制确实在工作，PI将利用他们的实验和解释能力来成像这些微观机制。考虑到摩擦连接的基本运动学导致声子（振动，因此声学能量）的产生，定量声发射和波形反演的结合完全能够将这些运动学成像。Glaser开发了表面和可嵌入式传感器，经NIST验证，能够测量皮米位移，范围从10 kHz到1 MHz，误差在3 dB以内。 研究表明，这些传感器转换的动态记录与理论运动学波形匹配得非常好，允许对震源运动学进行全波形反演，而不是单点矩张量反演。该项目的成果将在多个层面上推动科学和工程的发展。对滑动摩擦背后的物理机制的基本理解，从而提高对物理世界的基本理解。这将有助于完善目前对摩擦的经验性理解，并使机械设计从纳米机器到亚公里级结构有很大的改进。 此外，关于更大规模地震震源机制的基本问题将得到回答，特别是围绕自愈滑动概念的问题，从而提高对地震位错机制的理解，并最终提高地震安全性。