Slow-Fast Crack Propagation in Ferroelectric Single Crystals

Dear Prof. Xu,

Thank you for your comment. I have added below a snapshot of the video which shows the distribution of electric displacement magnitude. Ferroelectric domain orientations (tetragonal phases) are indicated with arrows, which are bold white for the twins ahead of the crack. The smeared crack is highlighted by the blue region in the middle of the specimen. The crack finally splits the model into two parts. Domain walls are also highlighted by low values of the electric displacement (green and blue regions) around the crack. The interaction between the crack and domains can be explained as follows. Since the crystal’s unit cell is longer along the domain direction (arrows), compressive stresses in the vertical direction are induced by the vertical twins ahead of the crack (bold white arrows), leading to a strong toughening effect. In the video it is obvious that as the crack cuts a set of twins, it can propagate easily until it feels the compressive stresses of the next set of twins ahead of the tip, and is arrested. These stages reflect the  sequence of abrupt crack propagation events, subsequent crack arrest and slow crack propagation periods (Slow-Fast crack propagation).

I hope that this short explanation helps to better understand the video.

By the way, I will say your hello to Prof. Arias as soon as I meet her.

Best regards,

Amir