Flexural and shear behaviour of layered sandwich beams

A new type of composite beam, referred to as Layered Sandwich Beam (LSB) is introduced in this study. The sandwich system consists of Glass Fiber Reinforced Polymer (GFRP) skins and Phenolic cores, and several layers of sandwich panels are bonded together with epoxy polymer matrix for manufacturing beams. To explore the suitability of this novel concept for structural applications, the flexural and shear behaviour of LSB have been investigated. Eight LSB, with four having layers horizontally oriented and the other four vertically oriented, have been tested under four-point bending and asymmetrical beam shear. A three-dimensional finite element model was developed using Strand7 to further understand the fundamental behaviour of the LSB. The results showed that the LSB has an increased sectional stability by preventing wrinkling and buckling of the composite skins and indentation failure. This improved the bending and shear strengths of the vertical LSB by 25% and 100%, respectively, compared with single sandwich beams in same orientation. While horizontal LSB provided a higher bending stiffness, the vertical beams exhibited higher shear strength due to the orientation of the skins. The finite element model can reliably predict the fundamental behaviour of the LSB in different orientations and loading configurations, within −10% to +14%.