Failure mode investigation of sandwich beams with functionally graded core

A failure mode criterion for piece-wise functionally graded sandwich composites is proposed and compared against experimental data. The average peak load for low and high density core configurations at upper region is 138% and 192% higher than the reference group. The proposed failure mode model predicts with accuracy the failure mechanisms. The best performance was obtained by the beam configuration where the core layer with highest density is located right below the upper face-sheet. This case not only leads to the highest value of normal wrinkling stress but it also prevents the core plastic collapse occurrence. However, the core failure by yielding will occur regardless of the core layer stacking sequence.