A Pressurized Blister Test Model For The Interface Adhesion Of Dissimilar Elastic-plastic Materials

With the increasing application of surface coatings and thin-film systems, coating failure due to the mismatch of mechanical and thermal properties between coating and substrate is of great importance. Previous studies have demonstrated that the most important intrinsic factor affecting the life of coating materials is the quality of interface adhesion. Therefore, characterizing of the interface adhesion quality is the key in practical application. In this master thesis, a concept of the interface adhesion energy,Γ0 , has been proposed to characterize the quality of interface adhesion of the elastic-plastic materials system. The ultimately purpose of this work is to gain an empirical equation to evaluate theΓ0 . So a series of jobs are conducted for this purpose here.Three main parts are contained in this master thesis. In the first part, the interface adhesion energy,Γ0 , has been proposed to characterize the quality of interface adhesion of the elastic-plastic materials system. A theory frame was established to extract the interface adhesion energy of elastic-plastic thin film/elastic-plastic substrate system with blister test. In the second part, a geometrically nonlinear finite element analysis of a blister test has been conducted. The blister test of elastic thin film/elastic substrate material system and elastic-plastic thin film/elastic substrate are both modeled. The results verified the validity of our finite element model and the theory frame we created in the first part. Thus, they have shown that our finite element model can well predict the solution for an elastic-plastic film bonded to an elastic-plastic substrate. In the third part, effects on the critical pressure of various influencing parameters are studied with this finite element model. On this basis, primary dimensionless relation between critical pressure with the interface fracture energy was obtained.At the beginning of this thesis, related research background and research status were introduced, the existed parameters characterizing interface adhesion and experiments methods to measure it were interpreted detailedly. A theory frame was established to extract the interface adhesion energy of elastic-plastic thin film/elastic-plastic substrate system with blister test. It includes three steps: first, dimensional analysis was applied to derive the relationship between blister test and interface adhesion energy. Then the blister test was simulated by finite element method. At last, the interface adhesion energy was extracted by a combination of nondimensional equation and true experiment data. The second important work is the geometrically nonlinear finite element analysis of the blister tests of an elastic film bonded to an elastic substrate and an elastic-plastic film bonded to an elastic substrate. The results verified the validity of our finite element model and the theory frame we created in the first part. Finally, a geometrically nonlinear finite element analysis of a blister test of an elastic-plastic film bonded to an elastic-plastic substrate was conducted. The primary dimensionless relation between critical pressure with the interface fracture energy was obtained.