A model for the mechanical stresses induced by head-disk contact

Abstract

A model is developed for the mechanical stresses resulting from contact between a flying head and a thin-film “rigid” disk of a magnetic storage system. The complexity of the configuration leads to a number of simplifying assumptions so as to render the problem tractable. In particular, the disk is treated as being comprised of homogeneous, isotropic. elastic layers; the normal loading is considered to be quasi-static provided dynamic enhancement is included; the tangential loads are simply taken to be the normal loading times a coefficient of friction; and the surface roughness is modelled as being sinusoidal in two dimensions. Even so, the problem is three-dimensional and geometrically nonlinear. Analysis proceeds on substructuring the model into a global problem for contact over the lowermost head planform and a local problem for asperity contact within this planform, with attention being focused on the latter. For the local problem, solutions for the contact stresses are obtained via an adaptation of the recent paper by Johnsonet al. (1985,Int. J. Mech. Sci.^]p27, 383), while solutions for the interior stresses are derived in closed form using Papkovich Neuber potentials. Some typical results are presented. In a full treatment of a system, these would have to be combined with thein situ and thermal stresses involved. Thus the present analysis simply provides a means for determining the mechanical contribution to the complete stress fields.