Three-point bending and in-plane compression properties of carbon-fiber/aluminum-honeycomb sandwich panels with short-Kevlar-fiber toughening

The short-Kevlar-fiber toughening method for carbon-fiber/aluminum-honeycomb sandwich panels was introduced. Three-point bending tests and in-plane compression tests were conducted. The load-displacement curves and failure modes were compared for toughened specimens and non-toughened specimens, which indicated that interface debonding followed by local failures occurred on the non-toughened specimens, whereas the toughened specimens behaved global failure with structural integrity. The results demonstrate that the bending property, compressive property and energy absorption of the carbon fiber/aluminum honeycomb sandwich panels are respectively increased by more than 14%, 55% and 61% by the short Kevlar fiber toughening. The observations of the damaged interface by SEM reveal that the toughened interface is kept bonded, while the face-core separation of the toughened specimen is caused by the fracture of honeycomb core. The FEM modeling was conducted to numerically analyze the three-point bending and in-plane compression performance of carbon fiber/aluminum honeycomb sandwich structures with and without short Kevlar fiber toughening. The FEM results provide general guidance for the designing of such sandwich structures.