The problem of structural stability of two medieval masonry towers is addressed. The geometrical and structural aspects of the towers were analysed and non-destructive tests were performed to assess the evolution of damage phenomena. The damage processes underway in some portions of the masonry were monitored using the Acoustic Emission (AE) technique. This method makes it possible to estimate ...

We report a novel mode of quasi-static oscillatory crack propagation when a cutting tool is driven through a thin polymer film [6,7]. In our experiments, for tools with a large enough width, the crack tip follows a highly periodic path, leaving behind a striking oscillatory pattern. Taking into account the separation of the film's bending and stretching energies and using classical fracture the...