  The phenomenon of arrest of an unstably-growing crack due to a curved weak
interface is investigated. The weak interface can produce the deviation of the
crack path, trapping the crack at the interface, leading to stable crack growth
for certain interface geometries. This idea could be used as a technical
solution for a new type of crack arrester, with a negligible impact on the
global stiffness, strength and weight of the structure. In order to exploit
this concept, an experimental campaign based on photo-elasticity and digital
image correlation is carried out, showing the capability of curved weak
interfaces to arrest cracks. The experiment is repeated for several geometrical
configurations through the modification of the interface curvature radii. The
phenomenon of crack deviation and subsequent arrest at the interface is also
investigated with the assistance of a computational model based on the finite
element method. The computational predictions provide the rationale for the
interpretation of the experimental observations, and distinguish between the
different behaviour of concave and convex interfaces. Consequently, as is shown
in the present study, the curved interface concept fosters new routes for the
attainment of structures with enhanced fracture resistance capacities, which
are of paramount importance for materials and components used in extreme
conditions.
