SGER: Weibull Failure Criterion for MEMS Component with Stress Singularity

0411844 PI- Okwaro-Osire，德克萨斯理工大学项目总结SGER：应力奇异性MEMS元件的Weibull失效准则动机和目标本提案涉及微机电系统（MEMS）的概率分析和设计，特别是将Weibull失效准则应用于应力奇异性或高应力梯度元件。拟议的研究解决了MEMS可靠性的一个关键方面。这是一个重要的问题，因为MEMS在可靠性至关重要的关键领域得到了广泛的应用：医疗领域和国土安全。MEMS材料表现出脆性和尺寸效应，因此选择了基于脆性材料尺寸效应的威布尔理论。此外，蚀刻工艺和MEMS材料的性质通常会在制造的部件中产生尖锐的凹口。 此外，许多MEMS部件由多层组成。尖锐的缺口和多层界面都产生应力奇异性，从而产生奇异性问题。单独地，这些力学问题中的每一个都被广泛地研究，但是在威布尔理论和奇异性的组合问题上进行了稀疏的工作。事实上，人们已经注意到，在高应力梯度的情况下应用传统的威布尔理论可能会低估部件中的临界缺陷尺寸（因此强度）。 因此，所提出的研究的动机是需要一个可用的（工程师）的方法锚定在威布尔理论，以解决奇异性，发生在整个类的工程问题。因此，拟议的工作有两个目标：也就是说，发展初步理论成果（这将是一个强大的威布尔失效准则的MEMS元件的应力奇异性的基础），并提出了一种新的测试装置的初步设计（用于在以后的研究阶段验证理论结果）智力优点拟议的研究将通过开发一个强大的威布尔理论来描述由于材料界面和尖锐缺口的应力奇异性的脆性部件的故障概率，从而提高知识。在拟议的研究中获得的结果将是一个基本上未经测试的想法的初步工作。这使得拟议的工作成为SGER赠款的理想候选人。此外，PI打算使用从SGER补助金获得的结果作为催化剂的一个更广泛的项目，这将涉及验证开发的理论，使用一种新的测试仪器对MEMS materials.Broader ImpactsThe拟议的研究充分整合到工程概率方面的本科生和研究生的教学研究活动。该计划规定本科生和研究生（特别是来自代表性不足群体的学生）在研究活动的各个阶段和层次积极参与研究。鼓励学生在专业会议上展示他们的成果。PI引入并创造了与大学工程教学有关的教学方法“泛指导”。他将继续开发和采用有效的教学技术来教授工程。 这项研究计划规定，加强与学生和/或教师谁是代表性不足的群体在得克萨斯理工大学的成员合作。此外，还开始与Prairie View A M大学（历史上的黑人学院大学之一）和德克萨斯大学圣安东尼奥（西班牙裔服务机构之一）的教师进行接触。在与政府的合作方面，美国宇航局格伦研究中心，特别是寿命预测分支，对拟议的研究活动非常感兴趣。拟议的研究活动的结果将不仅限于MEMS应用，而且可以扩展到陶瓷-金属结合、薄膜涂层和陶瓷涡轮机热负荷的应用。

0411844PI - Okwaro-Osire, Texas Tech UniversityPROJECT SUMMARYSGER: Weibull Failure Criterion for MEMS Component with Stress SingularityMotivation and ObjectivesThis proposal is concerned with the probabilistic analysis and design of microelectromechanical systems (MEMS), specifically with the application of the Weibull failure criterion to components with stress singularities or high stress gradients. The proposed research addresses a critical aspect of MEMS reliability. This is an important issue since MEMS are finding extensive use in the critical areas where reliability is paramount: the medical field and homeland security. MEMS materials have been shown to behave in a brittle manner and to exhibit the size effect , thus the choice of the Weibull theory, which is based on the size effect of brittle materials. Additionally, the etching process and the nature of MEMS materials often result in sharp notches in the manufactured components. Furthermore, many MEMS components consist of multi-layers. Both the sharp notches and multi-layer interfaces create stress singularities thus the singularity problem. Separately, each of these Mechanics problems has been researched extensively, but sparse work has been conducted on the combined problem of Weibull theory and singularity. In fact, it has been noted that applying the traditional Weibull theory in situations of high stress gradients can underestimate the critical flaw size (consequently the strength) in the component. Thus, the motivation of the proposed research is the need for a useable (for an engineer) approach anchored in the Weibull theory to address singularity that occurs in a whole class of engineering problems. Thus the objective of the proposed work is twofold; namely, develop preliminary theoretical results (that will be a basis for a robust Weibull failure criterion for MEMS component with stress singularity) and to present a preliminary design of a novel testing apparatus (to be used in verifying the theoretical results at a later phase of research).Intellectual MeritThe proposed research will advance knowledge by developing a robust Weibull theory to describe the probability of failure of brittle components with stress singularities due to material interfaces and sharp notches. The results obtained in the proposed research will be preliminary work in a largely untested idea. This makes the proposed work an ideal candidate for an SGER grant. Furthermore, the PI intends to use the results obtained from the SGER grant as a catalyst for a more extensive project, which will involve verifying the developed theory using a novel testing instrumentation on MEMS materials.Broader ImpactsThe proposed research fully integrates research activities into the teaching of probabilistic aspects of engineering to undergraduate and graduate students. The plan provides for the active research participation of both undergraduate and graduate students (particularly those from underrepresented groups) at the various stages and the level of the research activities. The students will be encouraged to present their results at professional meetings. The PI introduced and coined the pedagogic approach "Pan-mentoring" which relates to engineering instruction at college level. He will continue developing and adopting effective pedagogic techniques for teaching engineering. This research plan provides for the strengthening of collaboration with students and/or faculty who are members of underrepresented groups at Texas Tech University. Furthermore, contacts have been initiated with faculty at Prairie View A&M University (one of Historically Black Colleges & Universities) and at the University of Texas at San Antonio (one of Hispanic Serving Institutions). In regard to collaboration with the government, the proposed research activity is of immense interest to NASA Glenn Research Center, specifically the Life Prediction Branch.The results of the proposed research activity will not be limited to MEMS applications, but could extend toapplications in ceramic-to-metal bonds, thin-film coatings, and thermal loading of ceramic turbines.