%0 Journal Article
%T On the Failure and Fracture of Polymer Foam Containing Discontinuities
%A Addis Kidane
%J ISRN Materials Science
%D 2013
%R 10.1155/2013/408596
%X An experimental study is performed to investigate the tensile failure and fracture behavior of polymer foam containing discontinuities. PVC corecell foam, series A800 and A1200 is used for the investigation. Unnotched dog-bone specimen and specimens with center hole and edge cracks are tested under uniaxial tensile loading. Series of experiments are conducted at different defect size to width ratios, and the effect of the defect size on the net-section tensile strength of the foam is investigated. A fracture study is also conducted, and the effect of density and loading rate on the fracture behavior of foam is investigated. A minimal notch-strengthening effect is observed in specimens with center hole, and a notch-weakening effect is observed in specimen with edge notches. Furthermore, the fracture toughness increases with the increase in the foam density and decreases with the increase in loading rate. 1. Introduction Polymer foams are widely used in lightweight structures, such as core material for sandwich structures, due to their superior blast mitigation and impact resisting behavior. Currently, sandwich structures are among the lightweight structures widely used in aerospace, navy, and other related industries. Polymer foams have shown promising results as a core material for sandwich structures due to their high energy absorption capabilities, especially in the case of impact loading [1, 2]. There are well documented studies on the compressive properties and energy absorbing behavior of these materials [3]. It is shown that the structural response of a polymer foam strongly depends on the foam density, cell microstructure, and solid polymer properties [3]. Recent developments in the manufacturing processes of polymer foams contribute to the expansion of these materials in structural applications. Some of the applications involve cutout and holes. It is well understood that, in the case of a structure with a fully dense material, the presence of cracks, notches, and holes results in a stress concentration that leads to fracture. To understand these phenomena, the fracture behavior of polymers has been studied by different researcher including the early work of McIntyre and Anderton [4] and others [5¨C7]. McIntyre and Anderton [4] investigated the fracture toughness of a rigid polyurethane foam over a range of densities and found that the fracture toughness increases with density. The fatigue crack growth in the polyurethane foam has been investigated by Noble and Lilley [8]. The fracture process occurring in rigid, closed-cell polyurethane foam has
%U http://www.hindawi.com/journals/isrn.materials.science/2013/408596/