Elastic–plastic response of structural foams subjected to localized static loads

Structural foams are increasingly used in engineering applications where high strength and low weight are important. They are used also as energy absorbers. Sandwich structures are a typical area for application of structural foams (as core materials). In a sandwich structure, the core transfers the transverse forces as shear stresses and supports the face sheets against buckling and wrinkling. The structural foams are notoriously sensitive to failure by the application of localized surface loads. Thus, the proper design requires an understanding of the mechanical response of the foam materials to localized external loads.In this paper, the elastic–plastic behavior of closed-cell cellular foams subjected to point and line loads is investigated both experimentally and numerically. Two types of Divinicell foam (H60 and H100) are studied. A finite element modeling procedure is developed using the ABAQUS package. Both plane and axisymmetric formulations for local indentations by rigid bodies are considered. The plastic behavior is described using the *CRUSHABLE FOAM HARDENING material model. This model is calibrated using experimental curves from uniaxial compression tests. Geometrical non-linearity is also taken into account. Both indentation and unloading phases are modeled. Static indentation tests of foam panels and beams are performed using spherical and cylindrical indentors, respectively. A comparison of indentation response obtained from the numerical analysis and from the tests is carried out. A good agreement between the modeling and the experimental data is achieved. In perspective view, the present investigation can contribute towards the development of a damage tolerance methodology for rigid foams.