Papers by Author: Arcangelo Messina

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Authors: Andrea Antonio Rizzo, Nicola Ivan Giannoccaro, Arcangelo Messina
Abstract: Operational modal identification techniques, also known as Ambient modal or Output Only modal, have been in recent years object of growing interest within several applications typical of civil, mechanical and aerospace engineering. In this paper, two of them, known as EFDD and SSI, are fully implemented by means of in-house codes and applied on a finite element beam model dynamic response time data, in order to evaluate their accuracy, focusing on the lowest system’s natural frequencies. Assessments of the techniques’ robustness to a disturbance in the random excitation, reliability when implementing on a small number of measurement channels and in localization and quantification of a given damage in multiple sites are also performed and presented.
Authors: Edward J. Williams, Arcangelo Messina
Authors: Vito Dattoma, N.I. Giannoccaro, Arcangelo Messina, Riccardo Nobile
Abstract: Aluminium foam represents a new class of materials characterized by a large variability due to its porous structure. A simple and easy-to-use indicator of foam inhomogeneities is represented by apparent density, but this parameter does not give indications about differences existing in structural stiffness. To overcome this limit, the variability of natural frequency has been considered in this work in the case of commercial closed-cell aluminium foam. Moreover, fatigue and fracture properties of aluminium foam are not well studied. In this work standard three-point bend specimens SE(B) have been used to determine critical Crack-Tip Opening Displacement. The pre-crack phase, consisting in the application of appropriate fatigue load, has been monitored through modal analysis. Experimental results confirm the possibility of using this technique also in the initial step of fatigue failure process to quantify the amount of fatigue damage induced by repeated loads.
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