从复合材料的粘结层合板到机翼表面的积冰现象，固体粘附接触界面在工程应用和日常生活中广泛存在，其力学性能往往关乎系统的安全性和可靠性。如何对粘附界面的力学性能进行合理的表征和调控，成为机械、材料和力学等领域十分关注的科学问题。尽管目前人们对粘附界面的力学行为进行了不少探索，但对于实验中如何客观、全面地表征界面的粘附力学性能还未有清晰的认识，同时对于复杂界面载荷情况下的粘附界面接触行为还存在一定的争议和矛盾。鉴于此，本文以测量、分析和调控粘附界面的理论方法和实验表征为核心，开展了以下研究工作。首先，针对粘附界面强度的表征问题，本文建立了法向拔离实验（刚性平压头与有限厚度弹性基底）的粘附接触模型，理论推导得到了两种界面脱粘模式的理论解，并提出了一个重要的无量纲系统参数用于描述界面在裂纹扩展式脱粘和均匀式脱粘两种极限模式之间的转变。结合有限元计算，给出了描述脱粘行为的转变过程的拟合公式，并提出了一套系统的实验方法来合理地表征界面的粘附强度参数。该实验方法和理论模型得到了弹性薄膜粘附界面的法向拔离实验的证明。其次，针对界面剪切力存在下的粘附接触行为，本文理论分析了系统的能量释放率和平衡条件，推导了界面存在均匀剪应力时的粘附接触理论解。该理论模型明确了当界面剪切变形能可逆时，剪应力会对界面的粘附行为产生削弱作用；同时，相关模型还首次揭示了剪切对粘附的削弱作用将取决于系统的Maugis无量纲粘附参数。最后本文通过滑动粘附实验，证明了界面粘附的削弱作用确实同时与系统的Maugis粘附参数和可逆剪切指数相关，并首次提取了一般接触构型下的可逆滑动系数。最后，基于法向拔离脱粘模式转变的理论基础，本文设计了大幅可控和循环可逆的复合多聚物粘附界面，当复合结构中的合金发生固液转换时，界面粘附行为在裂纹扩展式和均匀脱粘两种模式之间进行可逆转变，临界脱粘力的调控范围高达约100倍。该方法被拓展应用于复合阵列结构的粘附调控，实现了表面局部粘附的编程化控制，并用于器件的选择性转印，也验证了网格化和像素级粘附界面调控的可能性。
Solid adhesive contact interfaces widely exist in engineering and in daily life, ranging from composite laminates to ice-accumulated airplane wings. Mechanical properties of these adhesive interfaces are often critical to the safety and reliability of the corresponding systems. Although great efforts have been dedicated to explore the mechanical behavior of adhesive interfaces, there is still lacking of a clear understanding on how to rationally characterize the mechanical properties of adhesive interfaces in experiments. In the meantime, there are still some controversies in theoretical prediction on the behavior of adhesive contact under complex load, especially with interface shear. Therefore, the thesis work focuses on experimental characterization and theoretical modeling of solid adhesive contacts, based on which new insights on adhesion regulation will also be offered and discussed.Firstly, the decohesion behavior of a rigid flat punch from an elastic film of finite thickness supported on a rigid substrate is studied. The solutions for two limiting decohesion modes, i.e. the JKR-like behavior when the interface breaks in a fashion of crack propagation and the DMT-like behavior when the interface breaks more uniformly, are obtained analytically. Then, an important dimensionless system parameter is proposed to describe the transition between the two limiting decohesion modes. Combined with finite element calculations, an approximate solution is obtained through fitting to describe the transition process of decohesion behaviors. Based on the approximate solution, a rational procedure to properly quantify the intrinsic interfacial strength from pull-off tests is proposed and validated by experiments.Secondly, for adhesive contact behavior in the presence of interface shear, analytical solutions have been derived by assuming a uniform shear stress along the interface based on an energy framework and the Maugis-Dugdale cohesive model. The theoretical predictions suggest that adhesion will be weakened by the interfacial shear stress as long as the reversible shear strain energy is positive even when generic contact configurations are considered. Moreover, this model also reveals, for the first time, that the adhesion weakening effect of interfacial shear stress would depend on the Maugis parameter of the system. Furthermore, adhesion experiments with pre-sliding prove that the adhesion weakening effect is indeed determined both by the reversible shear index and the Maugis parameter. By fitting the experimental data, the reversible slip factors for the generic contact configurations are obtained.Thirdly, based on the idea that decohesion mode can be affected by sub-surface stiffness, composite structures made of PDMS polymer and embedded alloy blocks have been designed to yield surfaces with switchable and reversible adhesion. More specifically, when the embedded alloy is in solid state, detachment from the surface occurs uniformly thereby exhibiting high pull-off force. In contrast, when the alloy is in the liquid state, detachment occurs in a crack-like fashion resulting in a much lower pull-off force. By changing the depth of the embedded alloy blocks, the tuning ratio of the critical pull-off force can be achieved up to 100 times. Such tuning mechanism has been further exploited to design meta-surfaces with programmable inhomogeneous adhesion and pixel-level control capability.
