“…One of the earliest approaches was the use of specific Green's functions that intrinsically account for the presence of the crack in the domain and avoid the discretisation the crack itself [6,7,8]; however such a technique is based on the knowledge of different Green's functions for different crack geometries, which in many cases are difficult, if not impossible, to evaluate. Another powerful and versatile approach for modelling cracked domains using the BEM is the multi-region technique, which is based on a subdivision of the domain into subregions whose boundaries contain the crack [9,10,11]. Then, to retrieve the behaviour of the original domain, continuity/equilibrium interface conditions are enforced on the newly introduced boundaries, whereas traction-free boundary conditions are enforced over the crack surfaces.…”