Mechanics of Extreme Mechanical Instabilities via Spontaneously Periodic Delamination

该奖项支持基础研究，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模式形成和演变的潜在变形和破坏机制。从人类皮肤起皱到粉刷墙壁上的水泡，在日常生活中，屈曲不稳定性无处不在。它一直被视为设计可拉伸器件的通用手段，以及动态调整各种表面形貌相关的润湿、粘附和光学特性。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，包括极可拉伸的电子设备、多功能智能窗口、可调光学、可调结构颜色变化的伪装、集水、自清洁、光滑表面和抗生物污染的绿色表面。这项工作还将通过天普大学的荣誉项目和女性工程探索项目为代表性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。通过紧密耦合的实验、计算和理论程序，本研究将探索软性衬底上薄膜自发极度屈曲驱动周期性分层的机制。实验上，将极大的预拉伸应变施加到弹性体衬底上，然后在其上沉积金属或半导体薄膜。预应变将被释放，在微尺度和毫米尺度上以连续薄膜和离散带的形式产生大面积、周期性的极分层图案。在极端屈曲过程中，分层屈曲膜和带的潜在开裂破坏将通过实验和开裂模型进行检验。为了揭示变形机理，将发展基于能量的理论建模和基于黏聚区建模的有限元模拟，以理解和预测随应变变化的周期性分层屈曲型材的可调几何形状。将理论模型和数值模拟与实验进行比较，以验证和修正。

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.