Localized bending effects in sandwich panels: photoelastic investigation versus high-order sandwich theory results

Abstract

The problem of local bending in sandwich panels with a ‘soft’ core often encountered in laterally loaded sandwich panels is investigated by conducting a series of photoelastic experiments. The experimental results are compared with analytical results obtained using the high-order sandwich panel theory (HSAPT). The experimental set-up consists of a symmetrically supported sandwich beam in three-point bending. The skins and the core of the sandwich specimens are made from optically active i.e. temporary double refractive, epoxy resin and polyurethane rubber, respectively, giving a elastic modular ratio of about 1260. The investigation includes two specimens differing from each other only by the thickness of their skins. The results of the analytical and experimental studies reveal that severe local stress concentrations are induced in the near vicinity of the support points and the point of external load application. The comparison between the analytical and the experimental results is presented in the form of contour line maps through the entire length and depth of the core material, and at the upper and lower fibres of the skins. The comparative study demonstrated a very good agreement between the photoelastic measurements and the predictions based on the HSAPT.