Structural enhancements for increased energy absorption in composite sandwich structures

Facesheet debonding and buckling failure modes are often the cause of low energy absorption in composite sandwich panels under edgewise compression loading. To control the failure mode and initial failure location, the use of structural enhancements coupled with crush initiators were investigated. Three types of structural enhancements (end bevels, stitching, and core webbing) were incorporated into four composite sandwich configurations consisting of woven or random mat carbon/epoxy facesheets with foam or balsa wood cores. The effectiveness of these structural enhancements, combined with the use of crush initiators, was evaluated using dynamic edgewise compression testing. Results show that structural enhancements coupled with crush initiators may be used to increase the energy absorption capabilities of composite sandwich structures. However, the effectiveness of the structural enhancements investigated is highly dependant upon the stiffness and strength properties of the facesheets and core as well as the strength of the facesheet/core interfaces. These findings suggest that composite sandwich structures may be designed for enhanced energy absorption through the proper design of the sandwich configuration and the incorporation of a suitable structural enhancement.