ECCM15 - 15 TH EUROPEAN CONFERENCE ON COMPOSITE MATERIALS, Venice, Italy, 24-28 June 2012 POLYMERIC FOAMS MODELLING BASED ON MICROSCOPIC CELL GEOMETRY FOR LIGHT SANDWICH STRUCTURE APPLICATION TO HELICOPTER BLADE IMPACT J. Aubry 1* , S. Marguet 1 , J.-F. Ferrero 1 , P. Navarro 1 1 Institut Clément Ader, Composite Materials and Structures, 10 ave. Edouard Belin 31400 TOULOUSE, France *julien.aubry@isae.fr Keywords: Polymeric foams, micro to macro model, numerical modeling, experimental characterization Abstract In this paper, a strategy for the modelling of the mechanical behaviour of polymeric foams is developped at the scale of the microstructure. The basic idea relies on the idealization of the microstructure by a network of perturbed truncated octahedron cells. Each cell is modelled with beams elements in agreement with micrograph observations. Moreover, an elastoplastic mechanical behaviour is applied to the beams to deal with buckling of the edges. The strategy is evaluated on examples of compressive and shearing tests. 1 Introduction As presented in figure 1, an helicopter blade is basically a box beam made of a metal leading edge for protection, a unidirectional glass fibers/epoxy resin roving dealing with the centrifugal loads, carbon fibers/epoxy resin woven fabric skins for aerodynamic shape, carbon fibers/epoxy resin woven fabric stiffeners for torsion and a polymeric foam core for skins stabilization. Figure 1. Scheme of a helicopter blade section During their whole life, helicopter blades can be subjected to various kind of impacts characterized by: • the relative velocity of impact, up to 150 m.s -1 (rotation of the rotor) • the angle: frontal (0°) or oblique (up to 90°) impact • the nature of the impactor: ice, wreckage... 1 Foam Glass / epoxy UD Composite skin