Through mechanical deformation of crystalline metals with hard molds, superplastic nanomolding provides a simple and high-throughput method to directly form nanostructures in the metal surface. The releasing of the molded nanostructures generally involves in chemical etching away the mold, in which metal nanostructures could also be chemically attacked. Therefore, mechanical demoulding is very promising not only for solving the above problem, but also for drastically reducing the cost by recycling molds. As a result, the mechanics underlying the mechanical demoulding is very important and highly desired since it can tell what kind of nanofeatures can be released without damaging the molds. In this paper, we develop a theory for the peeling mechanics of elastic film with its surface nanostructures deeply embedded in a substrate. Specifically, by analyzing the obtained micromechanical behavior in the interface and combining it into the mechanical framework of the macro-bending behavior of the film, we successfully derive a nonlinear governing equation for demoulding. By non-dimensionalizing the governing equation and further numerically solving it, we find out a simple expression for the apparent adhesion work. Our theory demonstrates that the apparent adhesion work is mainly contributed by the interface shear stress rather than the interface energy as revealed by the peeling of elastic film from flat or wavy interfaces, and the fillet radius at the edge of the cavity is found to be a crucial factor to determine the success or failure of demoulding. Finally, by recording the real-time peeling force of an actual peeling process, we observe that the theoretical prediction is in good agreement with the experimental results. This work not only provides theoretical guidance for mechanical demoulding of molded micro-/nanostructures, but also establishes a mechanical framework for studying the peeling mechanics of real material interface.

中文翻译：

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界面中相互嵌入纳米结构的薄膜-基底系统的剥离力学


通过硬模具对晶体金属进行机械变形，超塑性纳米成型提供了一种简单且高通量的方法，可以直接在金属表面形成纳米结构。模制纳米结构的脱模通常涉及化学蚀刻掉模具，其中金属纳米结构也可能受到化学攻击。因此，机械脱模不仅可以解决上述问题，而且可以通过回收模具来大幅降低成本。因此，机械脱模的力学非常重要并且非常需要，因为它可以告诉我们可以在不损坏模具的情况下释放什么样的纳米特征。在本文中，我们开发了一种表面纳米结构深深嵌入基材中的弹性薄膜的剥离力学理论。具体来说，通过分析获得的界面中的微观力学行为并将其结合到薄膜宏观弯曲行为的力学框架中，我们成功地推导了脱模的非线性控制方程。通过对控制方程进行无量纲化并进一步对其进行数值求解，我们找到了表观粘附功的简单表达式。我们的理论表明，表观粘附功主要由界面剪切应力而不是弹性薄膜从平坦或波状界面剥离所揭示的界面能贡献，并且发现空腔边缘的圆角半径为决定脱模成败的关键因素。最后，通过记录实际剥离过程的实时剥离力，我们观察到理论预测与实验结果非常吻合。 该工作不仅为模压微纳米结构的机械脱模提供了理论指导，而且为研究真实材料界面的剥离力学建立了力学框架。