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Laboratory of Structures and Smart Materials

Scientific Director: Professor Francesco dell’Isola

The Laboratory of Structures and Smart Materials is a research and development hub of the University of Rome “La Sapienza”, located in Cisterna di Latina. This laboratory is actively engaged in the study and prototyping of smart structures in collaboration with the Dipartimento di Ingegneria Strutturale e Geotecnica, Ingegneria Elettronica, Ingegneria Meccanica e Areospaziale and Ingegneria per le Scienze di Base e Applicate and the International Research Center for the Mathematics and Mechanics of Complex Systems of University of L’Aquila.

Since 1997 the research group has addressed the issue of vibration damping of mechanical structures using coupled piezoelectric transducers with electronic systems. In this context, research is oriented to the linear and nonlinear control of structural dynamics.

Lightweight structures such as panels and beams are coupled with a system of piezoelectric transducers interconnected via electronic circuits. Piezoelectric transducers allow bidirectional conversion between mechanical and electrical energy, thus fulfilling the dual and simultaneous role of sensors and actuators. The electronic circuitry permits the regulation and manages the transfer of energy. In order to perform this task it acquires signals from the sensors, processes them and provides power for control actions.

For example a typical application is in the design of soundproofing systems for the passenger compartment of an aircraft or a helicopter. In this case, it is necessary to filter the frequencies of the acoustic band transmitted by the panels, which are subjected to both the pressure associated with the aerodynamic flow and the vibrations due to the engine or to the rotor of the device.

Furthermore, the flutter on panels of the wing or the blades of a rotor is characterized by the instability conditions that occur when the flow speed reaches a critical value. This value can be increased by changing the stiffness of the structure, e.g. by varying the applied voltage to piezoelectric elements bonded on these structural elements.

Another issue of practical interest is the identification of structural damage and the design of smart systems able to self-monitor the evolution of its constitutive parameters.

During 2009 LSMI set as its objective the study of control systems applied to structures characterized by uncertain parameters.

It was used as an opportunity to approach the study of new problems even where the investigation of the structural uncertainties was ignored by the literature and on which it was possible to work in order to study traditional methods and possibly suggest new ones.

Issues that are addressed to this end were as follows:

1. Uncertainty modeling in inhomogeneous structures with unknown inhomogeneity and stimulated by piezoelectric actuators;

2. Analysis of metals subjected to the action of external loads and induced structural changes, such as anisotropy and strength of the material.

TThe first step was an important opportunity for interaction with other universities on fundamental founding principles of the Laboratory, providing the opportunity to:

a) acquire experience with the use of non-deterministic modeling techniques;

b) develop innovative topics and issues of interest where modeling uncertainty have received little attention.

The second step is the natural extension and evolution of six years work that this Laboratory has carried out with international recognition.