RUI: The Origins of Statistical Variation of Strength in Micropatterned Adhesive Contacts

RUI：微图案粘合剂接触强度统计变化的起源

• 批准号: 2211761
• 负责人: Jamie Booth
• 金额: $ 30.21万
• 依托单位: The University Corporation, Northridge
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2211761&HistoricalAwards=false
• 关键词: RUI; Origins; Statistical; Variation; Strength

This grant investigates the relationship between the properties of roughness on real-world surfaces and the resulting performance of novel controllable and reusable adhesive surfaces. Based upon patterning surfaces with arrays of microscale structures, taking inspiration from the toepads of insects and lizards, these adhesives can transition between strong attachment and easy detachment over many repeat cycles. This may enable new capabilities in gripping of delicate objects in extreme environments (e.g. in vacuum and underwater) or in the creation of multifunctional interfaces (e.g. in biomedical diagnostics and therapeutics). Differences in interfacial defects at each micropatterned sub-contact results in variation in local adhesive performance, with the statistical properties influencing the global strength and stability of the adhesive patch. This work will establish relationships which enable prediction of the emerging statistical behavior and resulting adhesive performance, based upon characteristic properties of the contacting surfaces. This grant will also strengthen research-based educational activities for the Mechanical Engineering student body at California State University Northridge, of whom 65.6 percent are from traditionally underserved minorities. The reach will be extended through a course-based undergraduate project, allowing a large volume of students to contribute meaningful data toward achieving the research objectives. Additionally, participating students will serve as undergraduate mentors and run high school outreach workshops themed around the topic.Several key gaps in understanding will be addressed in this study. The adhesive strength of sub-contacts has only been characterized for idealized defects, and a comprehensive range of defect size, shape, and position will be considered. Cohesive zone finite element simulations of microstructural detachment will provide the strength as defect properties are varied. Defect formation on rough surfaces is not understood, and must be examined to relate the surface characteristics to the statistical distribution of adhesive strength. Molecular dynamics simulations will yield contact maps as spectral properties of the roughness and the elastic properties of the bodies are varied. Experimental characterization of micropatterned adhesives will be performed on surfaces with manufactured defects and random roughness to validate relationships obtained through modeling and simulation. Lastly, understanding of the influence of statistical variation in sub-contact adhesive strength on performance at length and time scales approximating temporary bonding applications must be expanded. A semi-analytical mechanical model of adhesive patch behavior will integrate this local variation and examine the combined effects of substrate curvature, loading rate, and patch size on the global adhesive performance.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.

该拨款研究了现实世界表面的粗糙度特性与新型可控和可重复使用的粘合表面的最终性能之间的关系。这些粘合剂基于具有微尺度结构阵列的图案化表面，并从昆虫和蜥蜴的趾垫中汲取灵感，可以在多次重复循环中在牢固附着和轻松分离之间转变。这可能会带来在极端环境（例如真空和水下）中抓取精致物体或创建多功能接口（例如在生物医学诊断和治疗中）的新能力。每个微图案子接触处的界面缺陷的差异会导致局部粘合性能的变化，而统计特性会影响粘合贴片的整体强度和稳定性。这项工作将建立关系，根据接触表面的特性，能够预测新出现的统计行为和由此产生的粘合性能。这笔赠款还将加强加州州立大学北岭分校机械工程学生群体的研究型教育活动，其中 65.6% 来自传统上服务不足的少数族裔。该范围将通过基于课程的本科项目扩大，允许大量学生为实现研究目标贡献有意义的数据。 此外，参与的学生将担任本科生导师，并围绕该主题举办高中外展研讨会。本研究将解决几个关键的理解差距。子接触的粘合强度仅针对理想化缺陷进行了表征，并且将考虑全面的缺陷尺寸、形状和位置。微观结构分离的内聚区有限元模拟将提供缺陷特性变化时的强度。粗糙表面上的缺陷形成尚不清楚，必须进行检查以将表面特性与粘合强度的统计分布联系起来。随着物体粗糙度的光谱特性和弹性特性的变化，分子动力学模拟将产生接触图。将在具有制造缺陷和随机粗糙度的表面上进行微图案粘合剂的实验表征，以验证通过建模和模拟获得的关系。最后，必须扩大对子接触粘合强度统计变化对近似临时粘合应用的长度和时间尺度性能影响的理解。 粘合剂贴片行为的半分析力学模型将整合这种局部变化，并检查基材曲率、加载速率和贴片尺寸对整体粘合剂性能的综合影响。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。