Indentation Analysis of In-Plane Prestressed Composite Sandwich Plates: An Improved Contact Law

摘要

In this article a closed form solution is derived for the deformation response of a composite sandwich plate subjected to static indentation of a flat-ended cylindrical indenter. The facesheet deflection is several times the laminate thickness so that bending moments may be neglected and only membrane forces are considered in the facesheet. In contrast to the existing analytical model for the indentation of composite sandwich plates, in the present model, the stacking sequence of the facesheets can be completely arbitrary, so that the shear-extension coupling terms, i.e. A_(16) and A_(26), can also be included in the analysis. Furthermore, in the present model the effects of the initial in-plane normal and shear stresses on the edges of the sandwich plate are also considered. An improved contact law is derived based on the minimum total potential energy principle. The elastic strain energy, the plastic work dissipated in crushing the core and the external work are calculated using an appropriate shape function for the facesheet deflection. The relations between the indentation load and the deflection and length of deformation are obtained by minimization of the total potential energy. Analytical predictions of the load-indentation response compare well with experimental results. The effects of stacking sequence, ply thickness, number of layers and initial in-plane forces on the load-indentation response are studied and discussed.