Mechanics of Extreme Mechanical Instabilities via Spontaneously Periodic Delamination

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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.