Mechanics of Extreme Mechanical Instabilities via Spontaneously Periodic Delamination

该奖项支持基础性研究，探索在施加机械应变的情况下，控制极端屈曲驱动的周期性分层图案的形成和演化的潜在变形和破坏机制。屈曲不稳定性在日常生活中普遍存在，从人的皮肤起皱到油漆墙壁上的水泡。它已被用作设计可伸展器件以及动态调整与润湿、附着力和光学性能相关的各种表面形貌的一种通用手段。通过该项目开发的知识可以实现和推进多种表面性质控制的技术，包括极可伸展的电子学、多功能智能窗户、可调光学元件、用于伪装的可调结构颜色变化、集水、自清洁、光滑表面和用于抗生物污染的绿色表面。这项工作还将通过坦普尔大学的荣誉项目和女性工程探索项目为代表不足的群体提供丰富的研究机会，扩大K-12学生的参与范围。通过将实验、计算和理论紧密结合的项目，这项研究将探索软基上薄膜自发极端屈曲驱动的周期性分层的机理。在实验上，对弹性体基板施加极大的预拉伸应变，然后在其上沉积金属或半导体薄膜。预应变将被释放，以产生微米级和毫米级的连续薄膜和离散条带形式的大面积、周期性的极分层图案。将通过实验和裂纹模型来检验脱层屈曲薄膜和带材在极端屈曲过程中的潜在开裂失效。为了揭示变形机理，基于能量的理论模型和基于粘聚区模型的有限元模拟将被用来理解和预测周期性分层应变屈曲轮廓的可调几何形状。理论建模和数值模拟都将与实验进行比较，以进行验证和修改。

This award supports fundamental research exploring the underlying deformation and failure mechanism governing the formation and evolution of extremely buckling driven periodic delaminated patterns with the applied mechanical strain. Buckling instability is ubiquitous in daily lives from human skin wrinkling to blisters on painted walls. It has been pursued as a versatile means to design stretchable devices, as well as dynamically tuning a variety of surface topography related properties in wetting, adhesion, and optics. The knowledge developed through this project could enable and advance multiple surface properties governed technologies, including extremely stretchable electronics, multifunctional smart windows, tunable optics, tunable structural color change for camouflage, water harvesting, self-cleaning, slippery surface, and green surfaces for anti-biofouling. This work will also provide rich research opportunities for underrepresented groups through the honor program at Temple University and the Women Engineering Exploration program broadening participation for K-12 students.Through combining a tightly coupled experimental, computational, and theoretical program, this research will explore the mechanics of spontaneously extremely buckling driven periodic delamination of thin film on soft substrates. Experimentally, extremely large pre-stretched strain will be applied to an elastomer substrate, followed by the deposition of metal or semiconductor thin films on it. The pre-strain will be released to generate large-area, periodic extremely delaminated patterns in the form of continuous thin film and discrete ribbons on both microscale and millimeter-scale. The potential cracking failure in the delaminated buckled film and ribbons during the extreme buckling will be examined through experiments and cracking models. To reveal the deformation mechanism, energy-based theoretical modeling, together with cohesive zone modeling based finite element simulation, will be developed to understand and predict the tunable geometry of periodic delaminated buckled profiles with strains. Both the theoretical modeling and numerical simulations will be compared with experiments for validation and modifications.