This is a study of time base errors in video tape packs. The tape is viscoelastic. If a wound pack is stored at a constant temperature or subjected to environmental temperature cycles, the stresses relax and the tape creeps. Consequently, inelastic strains in the tape during playback cause distortion in the pictures. Time base error is a measure of inelastic longitudinal strain in the tape at playback. In this paper a mathematical model is developed to predict the effect of storage time, winding pattern, and pack size on time base error. Both the tape and hub are assumed elastic under hydrostatic loading and viscoelastic in shear. A four element fluid model is used for the tape and a Maxwell fluid model is used for the hub. Some comparison with experiments shows reasonable correlation.

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