CAREER: Measurements of Local Viscoelastic Properties by Nanointendation

这个CAREER项目将开发并验证一种方法，利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特性。纳米压头将用于确定载荷或位移作为粘弹性材料的规定位移或加载历史的时间函数。对材料响应进行分析和数值模拟，以开发一种提取表面局部松弛或蠕变函数的分析方法。该方法将允许测量非常少量的材料的粘弹性函数，如沉积在微电子用衬底上的薄膜，非常小的结构，如微机电系统（MEMS），材料性质在空间上变化的梯度材料，以及非均质材料，如人骨。该方法将能够测量亚微米尺度的粘弹性，而传统的材料测试系统是为散装材料样品设计的，无法确定这一点。计划的教育活动是为了实现以下目标：(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，并将他们在不同课程中获得的知识结合起来使用。(2)向课程介绍现代力学实验技术，包括利用纳米压痕在亚微米尺度上测量材料性能。(3)将计算机辅助工程的方法融入机械设计和航天结构课程，在课程中引入实验内容和制造经验。(4)在俄克拉荷马州立大学的产学研合作研究中心——网络处理研究中心，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.