In this work, three different types of laminates, each one realized with thirteen layers of fabric in epoxy matrix, have been inspected. In the first one, only aramid fiber (Twaron®) are used, the second one is a hybrid laminate reinforced by basalt and aramid fibers with an intercalated structure, while the last one is again reinforced by basalt and aramid fibers but disposed in a sandwich-like structure. The low velocity impact energy has been set at 12.5 J. In a first stage, the samples have been inspected after the impacts but before being subjected to ageing in an environmental chamber (ACS Angelantoni), by using different NDT methods, such as infrared thermography (IRT), near-infrared reflectography (NIRR) and transmittography (NIRT) and the ultraviolet (UV) imaging. In a second stage, i.e., after the treatment previously described, the impacted composite samples were again inspected by IRT. In particular, a comparison between the Fast Fourier Transform (FFT) and the Wavelet Transform (WT) techniques applied to the IRT data is reported. A discussion about the optimal choice of the scales related to the complex Morlet wavelet is also added. The discussion attempts to fill a gap that currently is present in the literature inherent the IRT method. The results obtained, if combined together, can be considered as innovative for the scientific community involved in this research field.

Studying the Effect of Enviromental Ageing on Impacted Composite Materials: An Innovative Perspective Through the Use of Non-Destructive Testing (NDT) Techniques

S. Sfarra;PAOLETTI, ALFONSO;PAOLETTI, Domenica
2014-01-01

Abstract

In this work, three different types of laminates, each one realized with thirteen layers of fabric in epoxy matrix, have been inspected. In the first one, only aramid fiber (Twaron®) are used, the second one is a hybrid laminate reinforced by basalt and aramid fibers with an intercalated structure, while the last one is again reinforced by basalt and aramid fibers but disposed in a sandwich-like structure. The low velocity impact energy has been set at 12.5 J. In a first stage, the samples have been inspected after the impacts but before being subjected to ageing in an environmental chamber (ACS Angelantoni), by using different NDT methods, such as infrared thermography (IRT), near-infrared reflectography (NIRR) and transmittography (NIRT) and the ultraviolet (UV) imaging. In a second stage, i.e., after the treatment previously described, the impacted composite samples were again inspected by IRT. In particular, a comparison between the Fast Fourier Transform (FFT) and the Wavelet Transform (WT) techniques applied to the IRT data is reported. A discussion about the optimal choice of the scales related to the complex Morlet wavelet is also added. The discussion attempts to fill a gap that currently is present in the literature inherent the IRT method. The results obtained, if combined together, can be considered as innovative for the scientific community involved in this research field.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/43473
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