Collaborative Oscillatory Fracture (PRL)

We report a new oscillatory propagation of cracks in thin films where three cracks interact mediated by two delamination fronts. Experimental observations indicate that delamination fronts joining the middle crack to the lateral crack tips swap contact periodically with the crack tip of the middle crack. A model based on a variational approach analytically predicts the condition of propagation and geometrical features of three parallel cracks. The stability conditions and oscillating propagation are found numerically and the predictions are in favorable agreement with experiments. We found that the physical mechanism selecting the wavelength structure is a relaxation process in which the middle crack produces a regular oscillatory path.

Collaborative Oscillatory Fracture
Juan-Francisco Fuentealba, Joel Marthelot, Benoît Roman, and Francisco Melo
Phys. Rev. Lett. 124, 174102 (2020) – Published 30 April 2020