Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Çelik lifli betonarme kirişte akustik emisyon aktivitelerinin Ib değeri analizi ile değerlendirilmesi(Gazi Üniversitesi, 2019) Alver, Ninel; Tayfur, Sena; Saatçi, SelçukThere are numerous nondestructive testing methods that are used to determine damages within structures. Acoustic Emission (AE), being one of these methods makes it possible to obtain significant pieces of information such as origin time, location and type of damage formed in a material during loading by analyzing AE data using various algorithms. Ib value analysis is one of these algorithms which is based on AE signal and this analysis enables to have information on formation of new cracks or propagation of existing cracks by scaling the magnitude of AE activities. In this study, in order to investigate effect of the steel fiber in concrete matrix on Ib value, two reinforced concrete beams were tested under simple bending while one of them was the reference. Afterwards, AE parameters obtained were analyzed, Ib value analyses were applied to amplitude values and these parameters were associated to each other. Furthermore, effect of steel fiber existence on behavior of the beam and distribution of AD value were examined.Conference Object Citation - WoS: 11Citation - Scopus: 14Quantitative Detection of Low Energy Impact Damage in a Sandwich Composite Wing(SAGE Publications Inc., 2010) Seaver, Mark; Aktaş, Engin; Trickey, Stephen T.This work describes damage detection in a foam core composite wing (1320 mm × 152.4 mm × 13.4 mm) following a series of low energy impacts. Thirteen impacts (6-8 J deposited energy) were applied at adjacent locations approximately 1/4 of the way out from the wing center. Following every one or two impacts, the wing was tested using static tip deflection and dynamic vibrational excitation. Static and dynamic strains were measured using eight fiber Bragg grating sensors. Dynamic acceleration was also monitored using three conventional accelerometers. The estimated bicoherence was used to detect the presence of damage-induced non-linearity in time-series data recorded from each sensor. Receiver operating characteristic (ROC) curves were constructed for each sensor based on 15 or more dynamic measurements made for each damage case. The ROC curves provide a quantitative, statistical approach to evaluating the damage detection capabilities of the various sensors.Article Citation - WoS: 2Citation - Scopus: 5The Influence of Low Energy Impacts on the Static and Dynamic Response of a Foam Core Composite Wing(SAGE Publications Inc., 2009) Aktaş, Engin; Seaver, Mark; Nichols, Jonathan M.; Trickey, Stephen T.; Davis, W. R.This work describes damage detection efforts on a composite wing subject to a series of low-energy (ĝ̂1/47 J) impacts. Two airfoils with fundamentally different damage scenarios were considered. The first damage scenario produced no visible signs of damage on the wing surface following eight impacts. A duplicate wing, subjected to a similar series of impacts, was investigated using flash thermography and subsequently autopsied. The flash thermography showed small, localized damage in the skin, but gave no information about core damage. The autopsy showed core/skin disbonding at both interfaces that varied with the number of impacts, core crushing, and a through the core shear crack. No clear changes to the static or dynamic wing response were observed for this scenario. The second damage scenario involved cracking of the wing skin. While damage quantification was not undertaken for this scenario, both static and dynamic changes in wing response were observed. An analytical model of the wing is presented which helps explain the observed behaviors of the two damage scenarios.