Experimental study on failure detection of sandwich panels with different cores under bending,vibration and cyclic impact loading,use of piezoelectric technology

The main objective of this work is to characterise sandwich panels with carbon/epoxy composite skins and cores of different materials (Expanded polystyrene foam, polyurethane foam injection and polyurethane foam sample) under three-point bending tests in free/free vibration and under repeated impact. The analysis of the behavior of the different sandwich panels under bending and vibration aims to determine the flexibility or stiffness of these panels. However, the analysis under repeated impact aims to determine the failure modes and the strength of the three sandwich panels. Indeed, the damage analysis was carried out using piezoelectric sensors connected to an acquisition chain using an advanced signal processing technique, which allows precise detection and quantification of damage. Using piezoelectric technology, this detection system ensures structures’ safety and reliability by allowing early and accurate detection of potential damage. Indeed, relying on piezoelectric sensors bonded to sandwich panels to capture vibration responses can improve its safety, thus reducing maintenance costs and ensuring an extension of its service life. The results of the various tests showed that carbon fibre resin matrix composite skin offers good protection to the different types of cores used in the sandwich panels. In addition, the composite sandwich panel with an expanded polystyrene core responded better than the other panels in bending and vibration tests. In repeated impact tests, the composite sandwich panel with foam core and the composite sandwich panel with injected polyurethane foam core proved effective in absorbing initial impacts. On the other hand, the sandwich panel with an expanded polystyrene core showed its ability to absorb repeated impacts while ensuring more extended degradation than the other two sandwich panels.