Influence of micro-voids on toughness of interfaces

In order to take into account the microstructure or the thickness of interfaces, the matched asymptotic expansions method can be an option to structural computations by finite elements based on refined meshes in the regions under consideration. It gives a description of the solution by means of two expansions, the outer one is meaningful at a distance of the interface under consideration whereas the inner one is valid in the vicinity of the interface. This approach allows to express the influence of a porous interface, which microstructure is made of microvoids regularly distributed, on the stiffness and toughness of an assembly. Moreover, it is proved that even if the macroscopic crack growth along this interface is stable, it is made of spontaneous microscopic crack increments.