考虑毛细作用微梁剥离的实验和力学模型

毛细力诱发的粘附现象在自然界和工农业生产中广泛存在,例如微机电系统、微纳米自组装、油气驱替等.本文系统研究了两根微梁的毛细粘附行为,包括梁剥离过程中液桥的形貌以及剥离力-位移变化规律.试验发现,微梁在毛细力作用下的剥离部分经历了液膜粘附和液滴粘附两个阶段.考虑两个阶段的液桥形状特征,分别建立系统的能量泛函,采用变分原理推导了考虑毛细力的微梁剥离的非线性微分方程和边界条件.基于Matlab编程求解方程,得到了剥离力-位移曲线,理论计算与试验结果具有很好的一致性.另外,参数研究表明,接触角和表面张力系数对液膜粘附的微梁剥离影响显著,而对液滴粘附的剥离影响较小;微梁刚度对两个阶段的剥离都有明显影响.本文的试验结果和理论分析对于实际工程中微结构的定量设计具有一定参考价值.

Experimental Test and Mechanical Modeling of Microbeam Peeling Considering Capillary Action

Capillary-induced adhesion phenomena exist widely in nature and industrial and artificial production, such as micro-electromechanical systems, micro-nano self-assembly, and oil and gas displacement. In this paper we study the capillary adhesion behavior of two microbeams, including the morphology of the liquid bridge and the change of the force-displacement relation during the peeling. The experiment results indicate that the microbeam peeling process under the capillary force experiences two stages, i.e., the liquid film-adhesion and the droplet-adhesion. The energy functionals of the system are established considering the liquid-bridge-shape characteristics for the two stages. The nonlinear differential equation and the boundary conditions of the microbeam peeling considering the capillary force are derived using the variational principle. The equation is solved using Matlab, and the peeling force-displacement curve is obtained. The theoretical calculations are in good agreement with the experimental results. Besides, parametric studies show that the contact angle and the surface tension coefficient have significant effects on the microbeam peeling in the liquid film-adhesion stage, but have minor effects in the droplet-adhesion stage. This work provides valuable references for the quantitative design of microstructures in practical engineering.