New Insights into Current Issues in Nanoindentation from Finite Element/Atomistic Multiscale Modeling

9971429金衬底的Brenner纳米压痕将使用有限元/原子多尺度模型进行模拟。这项模拟采用了研究裂纹扩展的方法所采用的技术，将用原子模型处理压痕周围的区域。该区域将嵌入到用有限元模拟的连续体中。然后，纳米压痕的动力学可以被解析到原子尺度，而不需要过多的原子来模拟远程应力。将进行三系列模拟，每一系列模拟都是由北卡罗来纳州立大学和桑迪亚国家实验室正在进行的实验合作的结果驱动的，在该实验中将研究金衬底的压痕。在每一次模拟中，原子衬底区域将使用公共的Sandia-Livermore程序用嵌入原子势来建模。处理衬底连续区域的代码将作为EAM代码的一组子例程来开发。在这个项目结束时，这些程序将通过PI的网站提供给其他研究人员。金衬底的纳米压痕将使用有限元/原子多尺度建模进行模拟。当一种硬度更高的材料(通常以尖头的形式)撞击到另一种材料的表面时，就会产生纳米压痕。衬底的响应是相对硬度的量度。对这种纳米压痕进行建模涉及原子级和连续型长度尺度的耦合。这笔赠款支持北卡罗来纳州立大学和桑迪亚国家实验室正在进行的试图模拟纳米压痕实验的理论研究。

9971429BrennerNanoindentation of gold substrates will be simulated using finite-element/atomistic multiscale modeling. The simulation, using techniques adapted from methods developed to study crack propagation, will treat the region around the indentation with an atomistic model. This region will be embedded in a continuum modeled with finite elements. The dynamics of nanoindentation may then be resolved to the atomic scale without the need for an excessively large number of atoms to model long-range stresses.Three series of simulations will be carried out, each of which are motivated by the results of an ongoing experimental collaboration at North Carolina State University and Sandia National Laboratory in which the indentation of gold substrates will be studied. In each of the simulations, the atomistic substrate region will be modeled with embedded-atom potentials using the public Sandia-Livermore code. Code to treat the continuum region of the substrate will be developed as a set of subroutines to the EAM code. At the end of this project, these routines will be made available to other researchers through the PI's web site.Nanoindentation of gold substrates will be simulated using finite-element/atomistic multiscale modeling. Nanoindentation occurs when a material of greater hardness, usually in the form of a pointed probe, impinges on the surface of another. The response of the substrate is a measure of the relative hardness. Modeling this nanoindentation involves coupling of atomistic and continuum length-scales. This grant supports theoretical research which attempts to model nanoindentation experiments being conducted at North Carolina State University and Sandia National Laboratory.