FRICTIONLESS CONTACT OF LAYERED METAL-MATRIX AND POLYMER-MATRIX COMPOSITE HALF-PLANES

This paper examines the differences and similarities in the response of metal-matrix and polymer-matrix composite half planes indented by a rigid, parabolic punch. The quantities of interest are the load versus contact length and the normal stress distribution in the contact region. In particular, the effect of material properties and off-axis ply orientation on these quantities is investigated for homogeneous and layered configurations. Layered configurations include [0-degrees/+/-45] layer sequences bonded to 90-degrees half planes, as well as to a half plane with significantly lower elastic stiffness moduli. The analysis is conducted using a recently developed solution method for frictionless contact problems of arbitrarily layered half planes consisting of isotropic, orthotropic, or monoclinic layers. The results indicate that homogeneous metal-matrix composite half planes exhibit a substantially stiffer load versus contact length response than homogeneous polymeric matrix half planes owing to their higher transverse material parameters, in particular the transverse Young's modulus, E33. In situations where local bending is present, which occurs in sandwich-type configurations with a substantially softer substrate, the ratio of the longitudinal to transverse Young's moduli plays a significant role for the considered laminate configurations. In this case, the normalized contact stress profiles of certain metal-matrix and polymer-matrix composites exhibit substantial departures from elliptical that appear similar in shape despite differences in the actual magnitudes of the material parameters.