CAREER: Determine the Roles of Material Heterogeneity and Thickness Variability on the Stability of Thin Membranes

该学院早期职业发展计划（Career）奖将支持综合研究和教育工作，以产生关于薄的、生物相容性材料和生物组织的材料和厚度不均匀性（也称为非均质性）如何在各种变形条件下影响其机械行为的新知识。这种材料的例子包括超薄可穿戴生物传感器、耳膜和心脏瓣膜。该奖项支持基础研究，这些研究将使目前不可用的非破坏性材料表征协议能够获得材料属性图，这将使这些材料的变形和稳定性得到更好的理解。该项目的创新方法有望促进新力学知识的科学进步，这对广泛的医疗保健和生物医学应用具有重要意义，从而影响国民健康和经济。该项目将为培养力学、材料科学和生物医学设备等重要跨学科领域的研究生和本科生提供机会。教育推广活动旨在让幼儿和代表性不足的少数民族参与STEM教育，目标是扩大国家的STEM人才库。许多重要的天然和合成非均质薄膜在非常小的载荷下起皱。薄结构的稳定性一直是力学界的一个经典问题。然而，迄今为止，理论和实验之间在屈曲载荷上的巨大差异仍然通常由经验修正来解释。在预测非均质薄膜的屈曲载荷方面存在明显的滞后。本CAREER项目的目标是验证一个假设，即薄膜中较高程度的非均质性可以降低临界屈曲载荷。研究方法是通过实验测量和比较不同非均质程度（从高度非均质到均匀）的薄膜的屈曲载荷。荧光立体显微镜和逆向有限元分析相结合，提取材料的性能分布和厚度变化，然后建立一个理论指导的数值模型，以确定定量的非均质程度，并阐明它与减少屈曲载荷的关系。该项目由民用、机械和制造创新计划（CMMI）和刺激竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development Program (CAREER) award will support integrated research and educational efforts to generate new knowledge of how material and thickness non-uniformity (also referred to as heterogeneity) in thin, bio-compatible materials and bio-tissues affect their mechanical behaviors under various deformation conditions. Examples of such materials include ultra-thin wearable bio-sensors, the eardrum membrane, and the heart valves. The award supports fundamental research that will enable a currently unavailable, non-destructive material characterization protocol for obtaining the material property maps, which will allow the deformation and stability of these materials to be better understood. The innovative approach in this project is expected to promote scientific advancement in new mechanics knowledge that is important for a wide range of healthcare and biomedical applications, thereby impacting the national health and economy. The project will provide opportunities to train graduate and undergraduate students in the important interdisciplinary areas of mechanics, materials science, and biomedical devices. The educational outreach activities are designed to engage young children and under-represented minorities in STEM education, with the goal of enlarging the STEM talent pool for the nation.Many important natural and synthesized heterogeneous thin membranes wrinkle under very small loads. Stability of thin structures has long been a canonical problem in the mechanics community. Yet to date, huge discrepancies in buckling loads between theories and experiments are still usually accounted for by empirical corrections. There is a clear lag in understanding for predicting the buckling loads of thin heterogeneous membranes. The objective of this CAREER project is to test the hypothesis that a higher degree of heterogeneity in thin membranes reduces the critical buckling loads. The research approach is to experimentally measure and compare the buckling loads of a set of thin membranes of various degrees of heterogeneity ranging from highly heterogeneous to homogeneous. Fluorescence stereo microscopy and inverse finite element analysis will be combined to extract the material property distributions and thickness variability, and then a theory-guided numerical model will be developed to identify a quantitative degree of heterogeneity and elucidate how it is related to reduced buckling loads.This project is jointly funded by the Civil, Mechanical, and Manufacturing Innovation program (CMMI), and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.