CAREER: Measurements of Local Viscoelastic Properties by Nanointendation

这个CAREER项目将开发和验证一种方法来确定线性和非线性粘弹性随时间变化的材料使用纳米压痕技术。纳米压头将用于确定粘弹性材料在规定位移或加载历史下的载荷或位移随时间的变化。将进行材料响应的分析和数值模拟，以开发用于提取表面局部松弛或蠕变函数的分析方法。该方法将允许非常少量的材料，如薄膜沉积在微电子，非常小的结构，如微电子机械系统（MEMS），梯度材料与材料特性变化的空间，和异质材料，如人的骨骼基板上的粘弹性功能的测量。这种方法将能够测量亚微米尺度上的粘弹性，而这些粘弹性是无法从为散装材料样品设计的传统材料测试系统中确定的。（1）让更多的本科生参与科研活动，让他们体验科学研究和发现的兴奋，以及结合和运用他们在不同课程中获得的知识。(2)介绍力学的现代实验技术，包括使用纳米压痕测量亚微米尺度的材料性能。(3)将计算机辅助工程的方法融入机械设计和航空航天结构课程，并在课程中引入实验内容和制造经验。(4)在俄克拉荷马州州立大学的一个工业/大学合作研究中心，开发研究生水平的课程，为研究生提供力学知识。

This CAREER project will develop and validate a method to determine linearly and nonlinearly viscoelastic properties of time-dependent materials using nanoindentation technology. A nanoindenter will be used to determine the load or displacement as a function of time of a viscoelastic material for prescribed displacement or loading history. Analysis and numerical simulation of the material response will be performed to develop a method of analysis for extracting the surface local relaxation or creep functions. The method will allow the measurements of viscoelastic functions for very small amounts of materials such as thin films deposited on substrates used in microelectronics, very small structures such as Micro-Electrical-Mechanical-Systems (MEMS), gradient materials with material properties varying spatially, and heterogeneous materials such as human bones. This method will enable the measurements of viscoelastic properties on the sub-micron scale that cannot be determined from conventional material testing systems that are designed for bulk material samples The educational activities are planned to fulfill the following objectives: (1) Involving more undergraduate students in research activities that allow them to experience the excitement in scientific research and discovery, as well as combining and using the knowledge they have acquired in different courses. (2) Introduce to the curriculum modern experimental techniques in mechanics, including the measurements of material properties on the sub-micron scale using nanoindentation. (3) Integrate the approach of Computer Aided Engineering into the Mechanical Design and Aerospace Structures courses, and introduce experimental content and manufacturing experience in the curriculum. (4) Develop graduate level courses that provide knowledge of mechanics to graduate students in the Web Handling Research Center, an Industry/University Cooperative Research Center at Oklahoma State University.