DYNAMIC INSTABILITIES IN THE SLIDING OF 2 LAYERED ELASTIC HALF-SPACES

Two flat layered elastic half-spaces, of different material properties , are pressed together and slide against each other with a constant co efficient of friction. Although a nominally steady-state solution exis ts, an analysis of the dynamic motion yields complex eigenvalues with positive real parts, i.e., a flutter instability. These results demons trate that self-excited (unstable) motion occurs for a wide range of m aterial combinations. The physical mechanism responsible for this inst ability is that of slip-wave destabilization. The influence of the pro perties of the layers on the destabilization of sliding motion is inve stigated These dynamic instabilities lead either to regions of stick-s lip or to areas of loss-of-contact. Finally the dynamic stresses at th e interfaces between the layers and the semi-infinite bodies are deter mined and compared to the nominally steady-state stresses. These dynam ic stresses are expected to play an important role in delamination.