Standard approaches to the health monitoring of structures are discussed in some detail; these techniques are mainly based on indirect measures of the structural response to external loads, are less effective than the direct investigations but reveal to be extremely advantageous from a practical point of view. An advanced technique, accounting for the peculiar aspects of damage detection problems and based on measures of the structural eigenfrequencies, is presented. In some specific problems this technique can however manifest a low sensitivity to small local damages. To this end, a novel technique is also introduced and discussed: it is based on purely electric measures of the state variables of an auxiliary electric system coupled to the main structure through a distributed set of piezoelectric patches. The topology of this auxiliary circuit and its constitutive parameters are optimized to increase the sensitivity of global measures, as eigenfrequencies, with respect to local variations of structural mechanical properties. Also due to the high experimental sensitivity of electric measures, the proposed method allows for accurate results in the identification and localization of damages.
展开▼
