Sandwich plates with ‘through-the-thickness’ and ‘fully potted’ inserts: evaluation of differences in structural performance

Abstract

A high-order sandwich plate theory, which includes the transverse flexibility of the core, is introduced. The theory includes separate descriptions of the face sheets and the core material, and general specification of loading and boundary conditions. The theory has been adapted especially for the analysis of sandwich plates with hard points in the form of inserts, and special attention is focused on the problem of sandwich plates with inserts of the ‘through-the-thickness’ and ‘fully potted’ types. The governing equations are formulated as a set of coupled first-order differential equations, which are solved numerically using the ‘multi segment method’ of integration. Numerical results obtained for sandwich plates with ‘through-the-thickness’ and ‘fully potted’ inserts subjected to out-of-plane loading are presented. Special emphasis is focused on describing the active load transfer mechanisms, and it is demonstrated that insert/potting and potting/honeycomb interaction effects play an important role in the build-up of local stress concentrations. A detailed comparison of the results obtained for ‘through-the-thickness’ and ‘fully potted’ inserts is presented, and it is shown that the mechanical response for the latter insert type generally exhibits much more severe stress concentrations than is the case for the first insert type. The paper is concluded with a discussion of design aspects including a few guidelines for design.