Theoretical Investigation And Numerical Simulation On The Adhesion Properties Of Graphene Nanofilm Based On An Approach Of Blister Test

Graphene is a single-atom-thick planar sheet of covalently bonded carbon atoms which are tightly packed in a honeycomb crystal lattice. Due to its excellent mechanical, electric, magnetic, thermal, and optical properties, graphene has very broad application prospects in novel micro/nano electronic devices, nanocomposite oversoul sensors, and many other fields. The adhesion properties of graphene have great influence on the overall performance of micro/nano electronics devices based on graphene and the enhancement effect of graphene reinforced composites. So the studies on graphene adhesion properties are very important, and it is a hot research topic currently. In this dissertation, based on the method of blistering test, the adhesion properties of graphene and the mechanical behavior when it debonding from substrate are studied.Based on the classical theories of plate and membrane, the adhesion energy and mechanical behaviors of graphene nanofilm debonding from the substrate are studied under uniform/concentrate loads. By the comparisons of the force-deformation relationships derived via linear plate, nonlinear plate and membrane theories, the application scopes of the three theories are illustrated and discussed. According to the energy variation principle in equilibrium state, the analytical expressions of interfacial adhesion energy about the critical debonding load and the critical debonding deflection are derived via the nonlinear plate and membrane theories, respectively, when the graphene nanofilms begin to debond from the substrate. The adhesion energy calculated by the analytical expressions show a good agreement with the experimental and atomistic simulation results in the literatures. On this basis, the dependence of the limit load, the critical debonding load and the deflection of graphene bubble on the geometrical dimensions of the graphene nanofilm are further analyzed. In addition, the stress distributions in the graphene nanofilm are analyzed, and the thickness dependence of adhesion energy is also discussed.Furthermore, finite element simulation was used to study the interface mechanical behavior of graphene when it debonding from the substrate. The critical debonding load and debonding deflection are calculated, and their dependence on the geometrical dimensions of the graphene nanofilm is analyzed when the graphene nanofilm begin to debond from the substrate. The results of simulation show a good agreement with the theoretical results as well as the corresponding experiment results. What's more, the influence of adhesion energy and graphene thickness on the debonding behavior of graphene nanofilm is also investigated. Finally, the mechanical behavior of graphene is studied when peeling of graphene takes place from the substrate. The force-displacement curve is obtained and the influence of adhesion energy on the maximum peeling load is also analyzed.