Influence of the Foam Core Material on the Indentation Behavior of Sandwich Composite Panels

Foam core sandwich composite materials have been used more and more frequently in various engineering applications in recent decades. Due to the increased usage of these materials, the concern about their strength and reliability has gained momentum. One of the basic disadvantages of the sandwich structures is their sensitivity to failure by the application of localized lateral loads. The main aim of this work is to investigate the influence of the foam core material on the indentation response of flat sandwich panels. For this purpose, quasi-static indentation test are conducted on sandwich panel specimens that are manufactured with glass fiber reinforced plastic (GFRP) face sheets and three types of Divinycell foam core material (H60, H100 and HCP100). The load is applied through a steel spherical indentor with diameter of 25 mm. The load-displacement diagram for both loading and unloading steps is obtained from the experiments. A numerical modeling of the elastic-plastic indentation response of sandwich structures is performed using the ABAQUS finite element program. In order to predict the residual dent magnitude, both indentation and unloading phases are analyzed. The finite element results demonstrate good agreement with the experimental data. It is found that the load (at a given indentation) is the highest for sandwich panels with the HCP100 foam core, and is the lowest for sandwich panels with the H60 foam core. The load (at the same indentation) for panels with the H100 foam core has intermediate magnitude.