Abstract:Mode coupling theory and energy feed in theory are both regarded as important generation mechanisms of friction induced squeal, but there have been no investigations into relationship between them so far. A two degree of freedom vibration model was established to describe the dynamics of a kind of typical frictional system with friction pairs of a lumped parameter mass and a rigid mass. The conditions of mode coupling instability were derived, as well as the relationship between mode coupling and energy feed in, when conditions of mode coupling were met, not met, or met just critical. The analysis results show that energy feed in is dependent on mode coupling theory and cannot be regarded as generation mechanism of friction squeal.