DAMAGE DETECTION IN FIBER-REINFORCED LAMINATES USING IMPEDANCE TESTING WITH PIEZOELECTRIC ACTIVE FIBER COMPOSITE ELEMENTS

摘要

Active Fiber Composites (AFC) made from piezoelectric fibers show promising potential, both, as actuators for smart composites and as sensors. AFC bonded to model structures (fiber-reinforced polymer-matrix laminate plates) are used for electrical impedance measurements. It is shown that detection of damage growth, e.g., increasing delamination, based on electrical impedance measurements taken at different times is feasible. Approaches for the analysis of the impedance spectra are investigated and potential problems highlighted. Changes in an empirically defined damage index correlate well with increasing size of the defect.