Microstructure: Dislocations, Creases, and Grains

9805422斯纳纳该奖项支持材料微观结构领域的研究，这些材料是由外部应变排入尖锐边界而产生的。这种现象发生在晶体的晶界、近晶液晶的焦点锥形缺陷、超导体的涡旋线和碎纸的折痕上。PI将专注于三个领域的具体项目：受挫晶体、非线性和色散以及纸张崩塌。第一个阶段着眼于新的阶段。位错线可以缓解外部应变，但也可以在晶体结构受挫时形成。PI将在各向异性手性晶体的自由能中引入一项，目的是预测和表征由此产生的缺陷晶格相。在第二个领域，PI将研究非线性和Disperson对微裂纹之间的连续介质相互作用的微扰效应，并在连续介质能量中观察到一个迄今被忽略的项。这一研究对于实际模拟相互作用位错线具有重要意义，在这种情况下，原子尺度上的相互作用需要与连续介质弹性理论相联系。最后一个领域与微观结构的大尺度动力学有关。PI将研究一个模型，该模型由马氏体相变和纸张碎裂过程中发现的声发射所驱动。这位才华横溢的PI将进行理论研究，旨在更好地了解与材料缺陷相关的小尺度结构的性质和形成。这项研究还将重点放在这种微观结构的动力学上，这种微观结构与纸张如何崩溃和一类结构转变有关。这项拟议的研究还涉及如何在原子水平上包含关于材料的重要信息，以正确地描述中尺度和宏观尺度上的动力学现象。***

9805422SethnaThis award supports research in the area of microstructure of materials that results from expulsion of external strain into sharp boundaries. This occurs at grain boundaries in crystals, at focal conic defects in smectic liquid crystals, at vortex lines in superconductors, and at creases in crumbled paper. The PI will focus on specific projects in three areas: frustrated crystals, nonlinearities and dispersion, and paper crumbling. The first focuses on new phases. Dislocation lines can relieve external strain, but can also form in response to frustration in the crystal structure. The PI will introduce a term in the free energy of anisotropic, chiral crystals and aim to predict and characterize the resulting defect-lattice phases. In the second area, the PI will study the perturbative effects of nonlinearity and disperson on the continuum interactions between microcracks and observe a hitherto ignored term in the continuum energy. This study is important to realistic simulation of interacting dislocation lines where connection between interactions at atomic scales to continuum elastic theory is required. The final area is concerned with the large scale dynamics of microstructure. The PI will study a model motivated by the acoustic emission found during martensitic transformations and during the crumbling of paper. %%%This talented PI will perform theoretical research aimed at a better understanding of the nature and formation of small scale structure that forms in association with defects in materials. The research will also focus on the dynamics of this microstructure that is relevant to how paper crumbles and a class of structural transformations. The proposed research also bears on how to include important information about materials at the atomic level to describe correctly dynamical phenomena at intermediate and macroscopic length scales. ***