| The Van Der Waals forces are always present, so that they play a role in a host different phenomenon. In this thesis, we choose the adhesion between the gecko-inspired array and surfaces and film buckling induced by the Van der Waals forces as examples to explore their mechanical behavior.The gecko-inspired adhesion array has a broad application prospects in the fields of medical devices and wearable devices as a new kind of material. People find that the pre-load and aspect ratio affect the array's pull-off force a lot in the experiment. We give the expression of pull-off force using the basic theory of beam, and find that as the pre-load increasing, the pull-off force increases and then tend to a definite value when the array interact with rough surfaces.at the same time, we show that as surfaces become rougher and the aspect ratio of the pillars become smaller, the pull-off force decreases.The soft thin elastic film already has a widely application in bio-engineering, microelectronic components and other fields. We know the influence of the Van der Waals forces to the buckling of soft elastic films can't be ignored. On the one hand, the film becomes no longer smooth causing the failure; On the other hand, the buckling of thin film can form useful patterns under the influence of the Van der Waals force. We established the equations using the nonlinear continuum mechanics and give the expression of the external load when buckling. We study how the Van Der Waals forces affect film buckling in two cases through linear stability analysis. One is the Van Der Waals forces between the film and the substrate; another is between the film and the contactor. We find in both two cases, equi-biaxial stretching lower the possibility of buckling. And repulsion between the film and the substrate has the same impact. The larger relative thickness to the distance between the film and the contactor is, the more possibility the film will buckle. |
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