| 講演要旨： |
To Characterize the interface strength of coating materials, critical interfaicial stresses corresponding to the critical scratch load are essential. From the analysis results of scratch tests under different stress conditions, it is found that the shear strength of the interface dramatically depends on the normal pressure. The larger the pressure is, the stronger the shear strength becomes. An empirical debonding criterion is proposed based on experimental and numerical results. Interestingly, such a criterion is similar to the well known Columb and Mohr's criterion for brittle materials under compression. However, it cannot be extended to normal tensile cases, under which an elliptical debonding criterion is developed by MD analysis. Thereby, to describe the strength behaviors of the interface in coating materials, three material properties are necessary.
Static failure and fatigue propagation properities of interface cracks in coating materials are also examined by experiments and numerical analysis in this study. It is found that the mode ratio has a strong effect on static failure, but almost no effect on its fatigue propagation.
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