Experimental study of sandwich panel strength with hourglass and square cell core under buckling load

In this paper, the strength analysis of composite sandwich structures under buckling load as well as composite polyurethane foam core in composite sandwich structures has been studied experimentally. For better performance of the shell and core in the sandwich structure as well as to increase their strength against buckling compressive load, a reinforcer with new geometry of hourglass and square with foam and without foam has been used. Having a negative Poisson's ratio and greater flexural stiffness as well as maximum load bearing capacity is the reason for using hourglass geometry. The new VARTM method has been used to create better and more uniform quality samples. The results of this study show that corrugated sandwich structures with hourglass filled with polyurethane foam withstand more load against buckling load and also have good efficiency in energy absorption. In a foamless composite sandwich structure, the core is distorted (separation of the shell from the core), and local buckling occurs due to the empty core. While in the sandwich structure with foam, due to the presence of foam in the core, the distortion of the structure is prevented. Also, despite its light weight, foam is able to withstand the compressive load due to local buckling. As a result, the structure has only suffered general buckling.