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5 August 2003 Multifunctional piezoelectric stiffness/energy for monitoring the health of structures
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A new mechanical multifunctional dual-stiffness sensor for in-situ real-time stiffness and energy density measurements was developed at the University of Maryland. This sensor is composed of 2 sub-sensors - a stiff and compliant subsensor. The sensor has the ability to predict the elastic field of a given host structure based on the strain state of the two sub-sensors integrated into the structure. This study showed the possibility of using the sensor to deduce the local instantaneous host stiffness and the strain energy density. Because the sensors can be embedded in a structure that is subjected to a complex stress state, Eshelbys equivalent inclusion method was used to derive the elastic properties of the host. An analytical derivation and a sensitivity analysis is given in a paper by Majeed and Dasgupta. Majeed and Dasgupta showed how the stiffness sensor is used to estimate the hosts stiffness. The present study evaluates the use of a dual stiffness sensor using piezoelectric sub-sensors to diagnose damage and to determine the remaining life of structures. The objective of this research is to develop an in-situ health monitoring active sensor for a real structure under its actual lifecycle loading condition. The detection of the onset of any damage, the subsequent monitoring of its growth and the help in predicting the remaining life of the structure constitute the important goals of the system. A numerical verification using finite element analysis (FEA) is presented and the results indicate that the sensor can be used for diagnostics of structures. A distributed array of sensors is used to determine the location of damage. Experimental results are presented for uniaxial experimental tests under monotonic quasistatic loading conditions and indicate that the concept can easily be implemented.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kelah Wakha, Majeed A. Majed, Abhijit Dasgupta, and Darryll J. Pines "Multifunctional piezoelectric stiffness/energy for monitoring the health of structures", Proc. SPIE 5056, Smart Structures and Materials 2003: Smart Structures and Integrated Systems, (5 August 2003);

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