Orthotropic Parameters of PU Foam Used in Sandwich Panels

Abstract

Polyurethane foam used as a core material in sandwich panels is considered in the paper. In this class of structures foam-filled material is treated as an isotropic, elastic material very often. Then, only two independent material parameters are needed to describe this material. Usually, they are chosen from the Young’s modulus E, the shear modulus G or the Poisson’s ratio $\nu$. In fact, when the material under consideration is a porous structure like a polyurethane foam, the identification of the mechanical properties of this material (even for the isotropic model) is an intricate task. Additionally, as will be shown in the paper, the foam stress-strain response is a function of the applied load. Therefore, the orthotropic behavior of the PU foam is analyzed. To determine mechanical parameters standard tests and a Digital Image Correlation (DIC) technique (named Aramis) are applied. The experimental results are discussed in detail.