CAREER: Measurements of Local Viscoelastic Properties by Nanointendation

这个职业项目将开发和验证一种使用纳米压痕技术来确定时间相关材料的线性和非线性粘弹性性质的方法。在规定的位移或加载历史下，将使用纳米压头来确定作为时间函数的粘弹性材料的载荷或位移。将对材料响应进行分析和数值模拟，以开发一种分析方法来提取表面局部松弛或蠕变函数。该方法将允许测量极少量材料的粘弹性函数，如微电子中使用的衬底上沉积的薄膜、微电子机械系统(MEMS)等非常小的结构、材料特性在空间上变化的梯度材料以及人骨等非均质材料。这种方法将能够测量亚微米尺度的粘弹性性质，而不是通过传统的材料测试系统来确定。计划开展的教育活动旨在实现以下目标：(1)让更多的本科生参与研究活动，使他们能够体验科学研究和发现的兴奋，以及结合和使用他们在不同课程中学到的知识。(2)在课程中引入现代力学实验技术，包括利用纳米压痕在亚微米尺度上测量材料性能。(3)将计算机辅助工程方法融入机械设计与航天结构课程，并在课程中引入实验内容和制造经验。(4)开发研究生水平的课程，为俄克拉荷马州立大学的行业/大学合作研究中心的网络处理研究中心的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.