Structural Health Monitoring of CFRP Propellers by Piezoelectric Line Sensors

Abstract

Recently, marine propellers made of carbon fiber reinforced plastics (CFRP) have been put into practical use for merchant ships. CFRP have advantages of high specific stiffness/strength and vibration damping property, and these can reduce the weight and noise of propellers to increase the efficiency and comfort in operation. However, they are more susceptible to impact or cavitation that cause critical damage than conventional propellers made of a copper alloy. Therefore, it can improve the reliability of CFRP propellers to assess the structural integrity based on structural health monitoring (SHM). In this study, piezoelectric line sensors were embedded into intact and damaged blades, respectively, in CFRP propellers with which a leisure boat was equipped. We could successfully detect vibration deformation of the propellers during the boat was moving, and we found that the amplitudes of the measured signals in the damaged blades were larger than those in the intact ones. Consequently, we can say that the applicability of the embedded piezoelectric sensors to SHMsystem for marine propellers is shown and it will increase the reliability not only of the propellers but also of the ship operation in the sea.