Theoretical and Experimental Studies of Buckling Mechanics of 3D Thin Film/Shape Memory Polymer Systems

3D 薄膜/形状记忆聚合物系统屈曲力学的理论与实验研究

• 批准号: 1405355
• 负责人: Jianliang Xiao
• 金额: $ 31.55万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1405355&HistoricalAwards=false
• 关键词: Theoretical; Experimental; Studies; Buckling; Mechanics

Buckling and wrinkling of stiff thin films on soft substrates results in ordered, wavy patterns on the surface. This phenomenon has been shown to have many potential applications, such as in novel sensors and actuators, stretchable electronics, precision metrology, optical gratings, and energy harvesting devices. Shape memory polymers, as a class of smart materials, can memorize distinct shapes, and can recover from the deformed shape to the original shape by external stimuli such as heating. These salient features of shape memory polymers, when combined with thin film buckling, can provide a unique opportunity for creating controllable surface patterns on planar as well as on complex 3D structures. This award supports research on the fundamental mechanics of thin film buckling on shape memory polymers, and will develop strategies for analysis and fabrication surface patterns in 3D hybrid material systems consisting of shape memory polymers and metallic thin films. The results from this work will benefit surface engineering, micro/nanoelectromechanical systems, and stretchable electronics with applications in biomedical devices, robotics, smart electronics, and deployable systems. Under the award the PI will provide multidisciplinary training to graduate and undergraduate students, and will actively seek participation from underrepresented groups and K-12 students. Buckling mechanics of thin films on soft substrates has been of interest to the mechanics community in the recent past, however, current theoretical models assume that the mechanical properties of the substrates do not change significantly during buckling and wrinkling formation. This assumption does not hold for shape memory polymers, which undergo dramatic property changes during a thermomechanical shape memory cycle. For example, the modulus typically changes by two to three orders of magnitude; viscosity can change by ten to fifteen orders of magnitude. The objective is to combine theoretical and experimental approaches to develop a new theory for the mechanics of buckling and wrinkling of thin films under consideration of large property changes during the and associated with the instability processes. This will allow one to consider buckling processes of thin films on shape memory polymers, with effects of time, temperature and changes of mechanical properties accounted for. Buckling of thin film ribbons on both 2D and 3D shape memory polymers will be studied The time evolution of buckling patterns coupled with the evolution of 3D shape memory polymer structures will be investigated, which will deliver 4D buckling systems of relevant to programmable devices. In addition, this research could provide practical strategies for fabricating complex 3D hybrid material systems.

硬质薄膜在软衬底上的弯曲和起皱会在表面形成有序的波纹。这一现象已被证明具有许多潜在的应用，如在新型传感器和执行器、可伸缩电子学、精密计量、光学光栅和能量采集设备中。形状记忆聚合物作为一类智能材料，可以记忆不同的形状，并能在加热等外界刺激下从变形的形状恢复到原来的形状。形状记忆聚合物的这些显著特征与薄膜屈曲相结合，可以为在平面和复杂的3D结构上创建可控的表面图案提供独特的机会。该奖项支持形状记忆聚合物薄膜屈曲的基本机制的研究，并将开发由形状记忆聚合物和金属薄膜组成的3D混合材料系统中的表面图案分析和制造策略。这项工作的结果将有利于表面工程、微/纳米机电系统和可拉伸电子设备在生物医学设备、机器人、智能电子和可展开系统中的应用。根据该奖项，PI将为研究生和本科生提供多学科培训，并将积极寻求代表不足的群体和K-12学生的参与。近年来，软衬底上薄膜的屈曲力学问题引起了力学学界的关注，然而，现有的理论模型假定衬底的力学性质在屈曲和起皱形成过程中没有明显的变化。这一假设不适用于形状记忆聚合物，它在热机械形状记忆周期中经历了戏剧性的性质变化。例如，模数通常变化两到三个数量级；粘度可能变化十到十五个数量级。其目的是结合理论和实验方法，在考虑薄膜在失稳过程中的大的性质变化的情况下，发展一种新的薄膜屈曲和起皱的力学理论。这将使人们能够考虑薄膜在形状记忆聚合物上的屈曲过程，并考虑时间、温度和机械性能变化的影响。我们将研究二维和三维形状记忆聚合物上薄膜薄带的屈曲，研究屈曲模式的时间演化和三维形状记忆聚合物结构的演化，从而提供与可编程器件相关的四维屈曲系统。此外，本研究还可以为复杂三维杂化材料体系的制备提供实用的策略。