Mechanics of Extreme Mechanical Instabilities via Spontaneously Periodic Delamination

该奖项支持基础研究探索潜在的变形和失效机制，这些机制控制着极端屈曲驱动的周期性分层模式的形成和演变以及施加的机械应变。屈曲不稳定性在日常生活中无处不在，从人类皮肤起皱到油漆墙壁上的水泡。它已被追求作为一种通用的手段来设计可拉伸设备，以及动态调整各种表面形貌相关的润湿，粘附和光学性能。通过该项目开发的知识可以实现和推进多种表面特性控制技术，包括极度可拉伸的电子器件，多功能智能窗户，可调光学器件，用于伪装的可调结构颜色变化，水收集，自清洁，光滑表面和用于抗生物污染的绿色表面。 这项工作也将提供丰富的研究机会，为代表性不足的群体通过荣誉计划在坦普尔大学和妇女工程探索计划扩大参与K-12 students.Through紧密耦合的实验，计算和理论相结合的程序，本研究将探讨自发极端屈曲驱动的软基板上的薄膜周期性分层的力学。在实验中，将极大的预拉伸应变施加到弹性体基底上，然后在其上沉积金属或半导体薄膜，释放预拉伸应变，在微米和毫米尺度上产生大面积、周期性的连续薄膜和离散条带形式的极端分层图案。在脱层屈曲膜和带在极端屈曲过程中潜在的开裂失效将通过实验和开裂模型进行检查。为了揭示变形机制，将开发基于能量的理论建模，以及基于内聚区建模的有限元模拟，以理解和预测周期性脱层屈曲轮廓与应变的可调几何形状。理论建模和数值模拟将与实验进行比较，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.