Unstable cracks trigger asymptotic rupture modes in bimaterial friction

The rupture of the interface joining two materials under frictional contact controls their macroscopic sliding. Interface dynamics depend markedly on mechanical properties bulk that bound interface. When are similar, recent experimental and theoretical work has shown shear cracks described by Linear Elastic Fracture Mechanics (LEFM) quantitatively describe interfaces. elastic dissimilar, many new effects take place result from bimaterial coupling: normal stress at is elastodynamically coupled to local slip rates. At low velocities, coupling not very significant governed `bimaterial cracks' well LEFM. As velocities increase, we experimentally theoretically show how become unstable a subsonic critical velocity, $c_T$. direction opposes applied in softer material, $c_T$ limiting velocity. ruptures propagate demonstrate provides an explanation for when pulses (new modes characterized spatially localized slip) generated. This completes fundamental physical description interfaces takes place.