Initiation of a secondary crack across a frictional interface

• We study the process of an interface crossing by a tensile crack.
• A special testing scheme was suggested.
• A scenario of step-wise crack path was realized.
• The path includes a shear zone at the interface.
• Estimates of the loading and geometry parameters were obtained.

The propagating crack interacts with an inclined frictional interface. The experiments focus on how a crack reaching the interface would further form a secondary crack on the opposite side after traveling down some distance along the interface. This distance increases with the inclination angle of the interface. This effect is related to an influence of shear along the contact plane caused by the initial crack approaching the contact plane. A simplified model explains the secondary crack development as a result of slip zone propagation along the contact plane, which induces stress concentration at the end of the slip zone.