Investigation of progressive failure in the composite sandwich panels with elastomeric foam core under concentrated loading

Failure and damage of crushable materials employed as core for the sandwich structures reduces serviceability and energy absorption capacity of the components especially under bending load so that many beneficial properties seem to be achieved by application of noncrushable lightweight materials instead of crushable foams as core for the sandwich structures. In this paper, an elastomeric foam is employed as core for two aspect ratios of the composite sandwich panels and the enhancement of the load-carrying capacity in the elastomeric foam-cored sandwich panels is investigated in comparison to which is measured about the individual composite panels applied as skins. Both experimental and finite element simulation programs are included in the research. The load-carrying performance of the elastomeric foam-cored sandwich panels is considered dependent on two main features of the constituent materials as hyperelastic behavior of the foam core and progressive damage of the composite skins which are simulated in the finite element models in order to describe the failure mechanism in the panels. Collapse of the elastomeric foam-cored sandwich panels is considered due to connection of some failure lines in the composite skins; however, the foam core remains undamaged. The elastomeric foam core can transfer the load from the top composite skin to the bottom one so that a great energy absorption capacity is provided for these panels. The elastomeric foam after failure of the composite skins can mobilize the residual strength of the laminates to endure against large deformations prior to final collapse. By application of the composite laminates in sandwich form with elastomeric foam core, the maximum load carrying and energy absorption capacity of the composite laminates increased about 60 and 110%, respectively. The results show more favorite failure behavior for the elastomeric foam-cored sandwich panels in comparison to which is expected usually for the crushable foam-cored sandwich panels which may be concerned in many industrial applications.