In situ correlation procedure is developed for electromechanically coupled PZT sensors to output the structural responses in standard engineering format, namely, displacement, strain, acceleration, and so forth. In order to implement this idea, we have used the standard sensing devices such as laser displacement sensor, strain gauge, and accelerometer. Aluminum beams and composite plate are employed in the experiments as specimens. The experimental results have shown that the structural reactions at critical locations can be monitored by a dynamically correlated PZT patch sensor, besides measuring the intensity of load in terms of acceleration. Furthermore, the influence of damage on sensor correlation has been evaluated. It is seen that the presence of damage has significantly modified the interpreted engineering parameters from the PZT patch and if they are appropriately correlated with respect to healthy structure, then the occurrence of damage related information will be ascertained. The developed sensor correlation concept therefore may be useful in load monitoring, health monitoring, and structural control applications. 1. Introduction Piezoelectric materials are a class of smart materials, which can be used as sensors and actuators to build adaptive and health monitoring aerospace structures. Introduction of these multifunctional materials into composites offers a great potential for stiffness tailoring, static shape correction, health monitoring, and vibration control applications [1–6]. Future unmanned aerospace vehicles demand high performance structural systems with self-thinking and adaptive capabilities, where piezoelectric composite materials may be considered as a solution to build adaptive structural concepts [7–9]. A structural system can be made diagnosable, when it is able to communicate its response with respect to various disturbances. In this regard, PZT material in thin film form provides the distributed sensing opportunity for the structural system to read its spatial information. However the data read from the sensors must be interpreted or examined with a proven health monitoring algorithm or procedure for knowing the vital information such as occurrence of damage, intensity of damage, location of damage, and loading intensity. The sensory information may be static or dynamic (vibration) in real time; therefore the electromechanically coupled (PZT) sensor is found suitable for a frequency dependent response monitoring application. Structural health monitoring concepts, involving piezoelectric sensors, have got considerable
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