Micro-computed tomography analysis of damage in notched composite laminates under multi-axial fatigue
COMPOSITES PART B-ENGINEERING
Authors: Qiao, Yao; Salviato, Marco
The broad application of polymer composites in engineering demands the deep understanding of the main damage mechanisms under realistic loading conditions and the development of proper physics-based models. Towards this goal, this study presents a comprehensive characterization of the main damage mechanisms in a selection of notched composite structures under multiaxial fatigue loading. Thanks to a synergistic combination of X-ray micro-computed tomography (mu-CT) and Digital Image Correlation (DIC), the main failure modes are identified while the crack volume associated to each mechanism is characterized. This study provides unprecedented quantitative data for the development and validation of computational models to capture the fatigue behavior of polymer composite structures.
Search for giant pulses of radio pulsars at frequency 111 MHz with LPA radio telescope
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
Authors: Kazantsev, Andrey Nikolaevich; Potapov, Vladimir Alexeevich
We have used the unique low frequency sensitivity of the Large Phased Array (LPA) radio telescope of Pushchino Radio Astronomy Observatory to collect a dataset consisting of single pulse observations of second period pulsars in the Northern Hemisphere. During observation sessions in 20112017, we collected data on 71 pulsars at a frequency of 111 MHz using a digital pulsar receiver. We have discovered Giant Radio Pulses (GRPs) from pulsars B0301+09 and B1237+25, and confirmed earlier reported generation of anomalously strong (probable giant) pulses from B1133+16 in a statistically significant dataset. Data for these pulsars and from B0950+08 and B1112+50, earlier reported as pulsars generating GRPs, were analyzed to evaluate their behavior over long time intervals. It was found that the statistical criterion (power-law spectrum of GRP distribution of energy and peak flux density) seems not to be strict for pulsars with a low magnetic field at their light cylinder. Moreover, spectra of some of these pulsars demonstrate unstable behavior with time and have a complex multicomponent shape. In the dataset for B0950+08, we have detected the strongest GRP from a pulsar with a low magnetic field at its light cylinder ever reported, having a peak flux density as strong as 16.8 kJy.