We present recent results of fracture experiments in poly-acrylamide gels. Polyacrylamide gels are soft polymers in which the characteristic sound speeds are on the order of a few meters/sec – thereby slowing down fracture dynamics by 3 orders of magnitude. We first demonstrate the universality of rapid fracture dynamics, comparing dynamics observed in gels with those seen in “classic” materials such as glass. Among these are the appearance of branching instabilities, localized waves confined to the crack front, and close correlations between the dynamics of the crack front and characteristic attributes of the resulting fracture surface. We will then demonstrate a number wholly new aspects of the fracture process, whose study is only made possible by utilizing the “slow motion” inherent in the fracture of these materials.
The Racah Institute of Physics, The Hebrew University of Jerusalem