Finite element analysis of broken fiber effects on the performance of active fiber composites

The finite element method was used to study the effect of fiber damage on the performance of active fiber composite (AFC) with piezoelectric fibers. The finite element model was developed for the simulation of PZT fiber-epoxy matrix composite with an interdigitated electrode pattern containing gaps in the fibers. The simulations were performed for the actuation and sensing functions of the composites with broken fibers and with undamaged fibers. Additionally, models in which the gaps in the fibers were accompanied by the depolarized regions in the adjacent parts of fibers were studied. The results demonstrate that a gap in the fiber leads to the loss of the contribution from the whole fiber segment between two electrodes into the actuation as the electric field is concentrating in the gap. The loss of up to 10% of the actuation and sensing performance was observed in the models with broken fibers compared to the composite with undamaged fibers. The results indicate that the decrease in the effective stiffness, resulting from the fiber damage, can produce the degradation of the AFC actuation performance as significant as the loss of the piezoelectric effect in the broken segments of fibers. Crown Copyright (c) 2008 Published by Elsevier Ltd. All rights reserved.