Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, 100084 Beijing, P.R. China.
Center for Flexible Electronics Technology, Tsinghua University, 100084 Beijing, P.R. China.
Proc Natl Acad Sci U S A. 2019 Jul 30;116(31):15368-15377. doi: 10.1073/pnas.1907732116. Epub 2019 Jul 17.
Techniques for forming sophisticated, 3D mesostructures in advanced, functional materials are of rapidly growing interest, owing to their potential uses across a broad range of fundamental and applied areas of application. Recently developed approaches to 3D assembly that rely on controlled buckling mechanics serve as versatile routes to 3D mesostructures in a diverse range of high-quality materials and length scales of relevance for 3D microsystems with unusual function and/or enhanced performance. Nonlinear buckling and delamination behaviors in materials that combine both weak and strong interfaces are foundational to the assembly process, but they can be difficult to control, especially for complex geometries. This paper presents theoretical and experimental studies of the fundamental aspects of adhesion and delamination in this context. By quantifying the effects of various essential parameters on these processes, we establish general design diagrams for different material systems, taking into account 4 dominant delamination states (wrinkling, partial delamination of the weak interface, full delamination of the weak interface, and partial delamination of the strong interface). These diagrams provide guidelines for the selection of engineering parameters that avoid interface-related failure, as demonstrated by a series of examples in 3D helical mesostructures and mesostructures that are reconfigurable based on the control of loading-path trajectories. Three-dimensional micromechanical resonators with frequencies that can be selected between 2 distinct values serve as demonstrative examples.
在基础科学和应用科学的众多领域中，具有复杂 3D 介观结构的先进功能材料受到了广泛关注，因此，人们对于能够将这些功能材料制备成具有复杂 3D 介观结构的技术的需求也在日益增长。最近，人们开发出了多种基于控制弯曲力学的 3D 组装方法，这些方法为在各种高质量材料中制备 3D 介观结构提供了一种通用途径，相关材料的长度尺度涵盖了具有特殊功能和/或增强性能的 3D 微系统的范围。在结合了弱界面和强界面的材料中，非线性弯曲和分层行为是组装过程的基础，但这些行为难以控制，尤其是在涉及复杂几何形状的情况下。本文对这一背景下的界面粘附和分层的基本方面进行了理论和实验研究。通过量化各种基本参数对这些过程的影响，我们为不同的材料体系建立了通用的设计图，考虑了 4 种主要的分层状态（褶皱、弱界面的部分分层、弱界面的完全分层和强界面的部分分层）。这些图为避免界面相关失效的工程参数选择提供了指导，通过一系列基于加载路径轨迹控制的 3D 螺旋介观结构和可重构介观结构的实例进行了验证。具有可在两个不同值之间选择的频率的 3D 微机械谐振器就是一个很好的例证。
