Fracture toughness of a rigid polyurethane foam: experimental and numerical investigation by varying the specimen sizes

In the present paper, the fracture toughness of a polyurethane (PUR) foam (manufactured by Necumer GmbH, Germany, under the commercial designation Necuron 651) is experimentally and numerically investigated in order to examine its dependence on the specimen sizes. As a matter fact, to the best knowledge of the present authors, such an analysis is still missing in the technical literature. To perform the experimental campaign, notched PUR foam beams, with different geometrical sizes, are tested under three-point bending loading, and the Modified Two-Parameter Model (recently proposed by some of the present authors) is employed to measure the fracture toughness. Subsequently, such an experimental campaign is numerically simulated by applying a micromechanical model, implemented in a non-linear finite element homemade code. Finally, the results obtained are compared with some experimental data available in the literature, related to the same PUR foam.