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

在摩擦接触下连接两种材料的界面破裂控制了它们的宏观滑动。界面破裂动力学显着取决于约束摩擦界面的散装材料的机械性能。当材料相似时，最新的实验和理论研究表明，线性弹性断裂力学（LEFM）描述的剪切裂纹定量描述了摩擦界面的破裂。当两种材料的弹性特性不同时，双材料耦合会产生许多新的效果：界面处的法向应力与局部滑移率弹性力学耦合。在低破裂速度下，双材料耦合不是很明显，并且界面破裂由LEFM很好描述的“双材料裂纹”控制。 $C_{Ť}$。当破裂方向与软材料中施加的剪切方向相反时，我们表明 $C_{Ť}$是亚音速极限速度。当破裂在较软的材料中沿施加的剪切方向传播时，我们证明 $C_{Ť}$ 提供了有关如何以及何时生成滑动脉冲（以空间局部滑动为特征的新破裂模式）的说明。