Viscoelastic fractures in stratified composite materials: "lenticular   trumpet"
  We consider fractures in a stratified composite material with solid layers separated by thin slices of extremely soft matter. Viscoelastic effects associated with the soft layers are taken into account via the simplest model for weakly cross-linked polymers. We find that certain small cracks running along layers take a new "trumpet" shape quite different from previously known shapes. 
Ko Okumura