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Most modern structural system designs rely on a damage tolerance philosophy, which means that a structure can withstand some damage without failure. The residual strength of a structure, i.e. the load that a damaged structure can still carry without failure, can be significantly affected by the presence of a crack or a damaged area and is usually substantially lower than the strength of the undamaged structure [1] . In the study presented in this paper MSC.Nastran sol700 explicit solver has been used to simulate different impact conditions on a stiffened composite panel [2] . This has allowed estimating and analysing the damage effects on the matrix and fibers of the composite panel. The virtual damaged panel has been loaded in a non-linear implicit simulation using MSC.Nastran sol400 solution to predict the residual strength [3–6] . The simulation results were in good agreement with experimental tests.

2009 - 2010 The here considered SHM procedure concerns innovative techniques for a structural monitoring of aeronautical components, all of them based upon the use of a Scanning Laser Doppler Vibrometer. The vibrometer is used to detect the dynamic response of the component under test, in wave propagation regime. The signal so recorded consists of space and time maps of vibration velocity offplane. The purpose of the study lies in the analysis of such maps, using filtering techniques that separate reflected waves from the incident ones, so that they can enable to identify defects. The innovative application of a novel technique (introduced by Ruzzene) for the first time to stringerized composite specimens, allowed the generation of baseline information directly from the measured dataset. The effectiveness of these methods has been demonstrated through their application to detection of a delamination in a composite stiffened plate and detection of defect/wrinkling in a T-shaped skin to stringer component. The most significant technological innovations achieved through these theses are: • The option key to excite the surface of a complex structure (in this case, the skins of a composite stingerized panel) and to derive the velocity profile on surfaces orthogonal to the excited one (in our case the web of the stringer) has been checked. This is crucial, as it would allow to install the piezo elements on the stringers, to excite them and to read velocities of points over the entire surface of the skin, without disassembly. Up to now, only cases of standard solicitation have been analyzed in literature, or cases where the velocities were acquired on the same surfaces excited. Today, therefore, there is no published study on the analysis conducted in such a manner. • The damage index was also applied to stiffened and greatly complex geometries. Up to now, in literature only analysis applied to simple flat panels can be found. • The FEM simulation was carried out on stiffened panels. In literature there are only simulations carried out on simple structural elements like flat panels without any stiffener. [edited by author] IX n.s.

Different multi-walled carbon nanotube (MWCNT) concentrations were incorporated in an epoxy resin and both the epoxy precursor and the composite were cured at 110 degrees C with a tertiary amine. Infrared spectroscopy was used to follow the curing progress by determining the decrease of the band due to the epoxy group. It was shown that the presence of MWCNTs accelerates the process, halving the time for the disappearance of the epoxy band. Atomic force microscopy demonstrated that the carbon nanotubes are well embedded in the epoxy matrix and singularly dispersed or in bundles, depending on their concentration. As a consequence of the good dispersion and interpenetration of the carbon nanotubes in the epoxy matrix, the glass transition temperature increased with increasing MWCNT concentration. Dynamic-mechanical analysis indicated a higher elastic modulus, particularly at high temperatures. The study of the transport properties, sorption and diffusion of water vapour at different activities, showed improved barrier properties on increasing the CNT concentration. (C) 2009 Elsevier Ltd. All rights reserved.