NSF/DMR-BSF: Bridging the gap between atomistic simulations and fracture mechanics

NSF/DMR-BSF：弥合原子模拟和断裂力学之间的差距

• 批准号: 1607670
• 负责人: Ellad Tadmor
• 金额: $ 30万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-12-15 至 2021-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607670&HistoricalAwards=false
• 关键词: NSF; DMR; BSF; Bridging; gap

NONTECHNICAL SUMMARYThe National Science Foundation and the United States -- Israel Binational Science Foundation (BSF) jointly support this collaboration between a US-based researcher and an Israel-based researcher. The NSF Division of Materials Research funds this award, which supports research and education on the fundamental nature of fracture in materials, which is governed by processes that occur at the atomic scale. The project seeks to answer the following question: why do atomistic simulations predict cracks in materials with different characteristics than those predicted by theory and observed in experiments? The PIs postulate that this is because, up until now and due to computational limitations, most atomistic simulations are artificially constrained and study systems that are too small. To go beyond current capabilities, the PIs will extend and apply a novel computational approach that will enable realistic simulations of fracture experiments. The simulations will focus on silicon, and will be validated against unique high-resolution dynamic fracture experiments performed by the Israeli collaborator. Silicon was chosen due its importance in many technologies including microelectronics devices, micro- and nano-electro-mechanical systems, solar cells, and bio-inspired devices. This research has potential for a significant positive impact on industry by elucidating how to prevent catastrophic failure in devices. All computer codes developed in this project will be made freely available to the research community via dedicated web portals (qcmethod.org and openkim.org). The collaborative project will also strengthen research ties between the US and Israel, and engage Israeli graduate students (both Jewish and Arab) with their US counterparts to create a positive example of collaboration in a troubled region.TECHNICAL SUMMARYThe National Science Foundation and the United States -- Israel Binational Science Foundation (BSF) jointly support this collaboration between a US-based researcher and an Israel-based researcher. The NSF Division of Materials Research funds this award, which supports research and education on the fundamental nature of fracture in materials, which is governed by processes that occur at the atomic scale.The ultimate aim of this project is to develop a predictive multiscale framework for simulating fracture phenomena that explicitly account for the effect of a variety of factors including crystallographic orientation, loading rate, temperature, and preexisting defects. This requires a multiscale approach that includes both the correct treatment of the long-range stress field generated by a crack, and the atomic-scale fracture processes that involve bond breaking at the crack tip. Fully-atomistic simulations that focus primarily on the crack tip region exhibit an effect called "lattice trapping" whereby the loading device has to overcome an energy barrier associated with breaking atomic bonds that span the cleavage plane. This overloading causes cracks to begin to move at high initial speed. In contrast, continuum theory does not account for lattice trapping and predicts that a crack can begin to propagate at any speed. Recent high-resolution fracture experiments on silicon crystals performed by the Israeli collaborator agree with continuum theory, and show that the lattice trapping effect is small and that slow initial crack speeds are possible. The PIs posit that lattice trapping is an artifact of the size and 2D constraints imposed on the atomistic simulations. The proposed framework will make it possible to simulate fracture experiments at realistic loading rates for specimens with a large enough atomistic region for curvature effects to occur.This research has potential for a significant positive impact on industry by elucidating how to prevent catastrophic failure in devices. All computer codes developed in this project will be made freely available to the research community via dedicated web portals (qcmethod.org and openkim.org). The collaborative project will also strengthen research ties between the US and Israel, and engage Israeli graduate students (both Jewish and Arab) with their US counterparts to create a positive example of collaboration in a troubled region.

非技术总结国家科学基金会和美国 - 以色列双原则科学基金会（BSF）共同支持美国研究人员与以色列研究人员之间的这一合作。 NSF材料研究部研究资金为该奖项提供了支持，该奖项支持材料中裂缝基本性质的研究和教育，该材料的基本性质受原子规模上发生的过程的约束。该项目试图回答以下问题：为什么原子模拟可以预测具有与理论预测并在实验中观察到的材料不同的材料的裂纹？ PI假设这是因为到目前为止，由于计算局限性，大多数原子模拟都是人为地限制的，并且研​​究系统太小。为了超越当前功能，PI将扩展并应用一种新型的计算方法，该方法将对断裂实验进行现实模拟。这些模拟将集中在硅上，并将根据以色列合作者执行的独特高分辨率动态断裂实验进行验证。选择硅在许多技术中的重要性，包括微电子设备，微电动机械系统，太阳能电池和生物启发的设备。这项研究通过阐明如何预防设备中的灾难性故障来对行业产生重大积极影响。该项目中开发的所有计算机代码均可通过专用Web门户（qcmethod.org和openkim.org）免费提供给研究社区。该协作项目还将加强美国和以色列之间的研究联系，并与他们的美国同行与以色列研究生（犹太人和阿拉伯人）互动，以在陷入困境的地区创建一个积极的协作例子。 NSF材料研究部研究基金该奖项，该奖项支持材料中裂缝基本性质的研究和教育，该过程受原子量表上发生的过程的控制。该项目的最终目的是开发一个预测性的多尺度框架，以模拟分裂现象，以明确地说明各种因素的效果，包括各种因素的效果，包括各种因素的效果，包括结晶的效果，并定制了定型，并构成了定型，并构成了定型，并构成了定型，并构成了定型效果。这需要一种多尺度方法，其中包括对裂纹产生的远程应力场的正确处理，以及涉及在裂纹尖端破裂的原子尺度断裂过程。主要集中在裂纹尖端区域的全部原子模拟表现出一种称为“晶格捕获”的效果，从而加载装置必须克服与破坏跨裂解平面的破坏原子键相关的能屏障。这种超载导致裂缝开始以高初始速度移动。相比之下，连续理论不能解释晶格陷阱，并预测裂缝可以以任何速度开始传播。以色列合作者执行的硅晶体上的最新高分辨率断裂实验同意连续性理论，并表明晶格诱捕效果很小，并且可能会缓慢的初始裂纹速度。 PI认为晶格陷阱是对原子模拟施加的大小和2D约束的工件。所提出的框架将使在具有足够大原子体区域的标本中模拟骨折实验以实现曲率效应。该项目中开发的所有计算机代码均可通过专用Web门户（qcmethod.org和openkim.org）免费提供给研究社区。该协作项目还将加强美国和以色列之间的研究关系，并与美国同行一起与以色列研究生（犹太人和阿拉伯人）互动，以在陷入困境的地区建立一个积极的协作典范。