Numerical modelling of sub-surface stress in magnetic data tape heads due to the dynamic contact with a tape

The stress field at the subsurface of the ceramic used as a tape-bearing surface (TBS) in magnetic head construction is calculated by means of numerical methods taking into account roughness and friction forces at the head to tape interface (HTI). A two-dimensional model confirms the purely elastic character of the contact. However, only a three-dimensional model allows a quantitative interpretation, and thus to estimate the real area to apparent area of contact ratio-in agreement with a previous formal calculation-as well as the depth of the maximum von Mises stress-i.e. the depth at which a crack is more likely to form and extend-near 30 nm, comparable to the pullout depth observed at the surface of the ceramic used in actual heads. (C) 2002 Elsevier Science Ltd. All rights reserved.