PVDF sensor and its applications in delamination response detection

Abstract

Questions are frequently raised from industries concerning removable and reusable sensors for composite products damage detection and health monitoring. A major requirement is that the tested product should not be altered during the process of bonding and removing the sensor. In this paper, a method using thin PVDF sensors and double-sided tapes to detect delaminations and other damages in composite structures with emphasis on composite beams is presented. Sensor equations are derived for thin PVDF materials. Delamination detection examples, by using the nonlinear characteristics of the delaminated structures and PVDF sensor sensing properties, are also presented. though actuation applications can also be found in literature.'8'91 Campbell et a/.' used PVDF films in conditioning and strain measurement in composite materials. Lee and Moon'3' used flexibility and easy user-tailed properties of the PVDF films and designed modal sensor for given structures. Hanagud et a/.'7' used PVDF films to carry out experimental modal analysis. In this paper, we present the applications of using PVDF sensors in composite structure delamination detections and nonlinear vibration monitoring. Analysis of the thin PVDF films indicates that the sensor output is proportional to the structural local curvature; therefore it is more sensitive to the structural abnormality than those setups using displacement or accelerometer sensors.