Compression, flexure and shear properties of a sandwich composite containing defects

The mechanical properties of a sandwich composite containing interfacial cr acks or impact damage are compared when loaded in edgewise compression, fle xure or shear. The composite is made from glass fibre reinforced polymer (G FRP) laminate skins over a core of foamed poly vinyl chloride (PVC), and th is sandwich material is used in some naval minehunting ships. The propertie s are reduced with increasing interfacial crack or impact damage length, bu t only when the defects cause a change in the failure mode, which is depend ent on the load state. The principal failure modes under the different load states are compared. The properties are also dependent on the severity of impact damage, with low energy damage to the skin having a smaller effect o n stiffness and strength than high energy impacts which damage both the ski n and foam core. The implications of these findings on the structural integ rity of a minehunting ship made from GFRP/PVC foam sandwich composite is di scussed. (C) 1999 Elsevier Science Ltd. All rights reserved.