Damage Analysis in Sandwich Beams with Cellular Core using Micromechanics Coupled to a Statistical Approach

Abstract

This paper deals with the analysis of damage and mechanical properties of sandwich beams. The face sheets consist of glass mat-reinforced polyester (GMRP) perfectly bonded to core material. The latter is a regular array of thermoplastic tubular cells called Tubulam®. Mechanical behaviour of sandwich beams is analysed and simulated under three and four-point bending and correlated to experimental results. Sandwich beam modelling was performed according to two steps. First, skins behaviour is modelled by a micromechanical approach based upon the generalised Mori and Tanaka theory. Moreover, in the second step, an analytical model based on the laminate theory predicts the overall properties of core material. In this work, damage mechanisms are introduced in the modelling using probabilistic concepts applied at the microscopic scale of face sheets (fibres, matrix, interface between fibres and matrix) as well as at the mesoscopic scale namely tubular core and bond layer between core and skins. Finally, the developed model is validated by experimental tests: three and four-point bending. Experimentally measured global responses of the sandwich beams are compared to those numerically simulated and discussed in terms of damage chronology and evolution. The main point of the developed analysis is that the mechanical behaviour may be predicted on the basis of the structural parameters. Hence, it may provide an important analytical tool for aided design to optimise sandwich structures with respect to applied loading and micromechanical parameters.