SHEAR PROPERTIES OF A SANDWICH COMPOSITE CONTAINING DEFECTS

This paper investigates the effects of interfacial crack size and impa ct damage size on the shear properties and failure mechanisms of a typ ical marine sandwich composite made from glass reinforced polymer (GRP ) skins and a poly(vinyl chloride) (PVC) foam core. An abrupt decrease in the static shear strength and fatigue resistance occurred when the interfacial crack length between the skin and core exceeded similar t o 20-30 mm due to the failure mechanism changing from wrinkling of the GRP skin to shear cracking of the foam core. The static shear failure loads of the composite containing interfacial cracks between 20 and 9 0 mm in length were used to test the accuracy of two models for predic ting the strengths of defected sandwich composites. The shear properti es were also reduced when the impact damage area was increased, althou gh the magnitude of the reduction was determined by the impact energy. (C) 1998 Elsevier Science Ltd. All rights reserved.