Packaging of active fiber composites for improved sensor performance

Abstract

Active fiber composites (AFC) composed of lead zirconate titanate (PZT) fibers embeddedin an epoxy matrix and sandwiched between two interdigitated electrodes provide a thinand flexible smart material device which can act as a sensor or actuator. The thin profilesof AFC make them ideal for integration in glass or carbon fiber composite laminates.However, due to the low tensile limit of the PZT fibers, AFC can fail at strains below thetensile limit of many composites. This makes their use as a component in an activelaminate design somewhat undesirable. In the current work, tensile testing of smartlaminates composed of AFC integrated in glass fiber laminates was conducted to assess theeffectiveness of different packaging strategies for improving AFC sensor performanceat high strains relative to the tensile limit of the AFC. AFC were encased incarbon fiber, silicon, and pre-stressed carbon fiber to improve the tensile limitof the AFC when integrated in glass fiber laminates. By laminating AFC withpre-stressed carbon fiber, the tensile limit and strain sensor ability of the AFC weresignificantly improved. Acoustic emission monitoring was used and the results showthat PZT fiber breakage was reduced due to the pre-stressed packaging process.