Propagation of Boundary Disturbances in an Axially Moving Strip in Contact With Rigid and Flexible Constraints

The exact expression describing the contact force between an axially moving flexible strip and a one-sided constraint is derived using the Green’s function formulation. Discontinuity of the initial velocity at a boundary of the strip due to a disturbance, causes discontinuity in the contact force history at any constraint that is not modeled by a single spring element. The discontinuities in the contact force occur at the instants when those propagating wavefronts in the strip with nonvanishing slope interact with the constraint. A model of a magnetic tape-recording head system is analyzed. Tape-head contact loss is predicted, depending on the amplitude and frequency of a disturbance, the head location, and the preload of the tape against the head.