T1 process

It involves four discrete objects such as bubbles, drops, cells, etc.

The T1 process consists in breaking the contact between A and B and establishing the contact between C and D. When a significant number of rearrangement events such as T1 processes with similar orientations occur inside a foam or a tissue, the material correspondingly undergoes a deformation: it elongates in the direction in which neighbours depart (here, AB) while it contracts in the direction in which new neighbour pairs form (here, CD).

As a result of the existence of the T1 and similar processes, materials made of these objects have a number of similar rheological properties.

For such materials, such irreversible deformations arise from the ability to rearrange their constitutive objects.

Thus, the T1 process is the major mesoscopic ingredient of plasticity for these materials.