1,720,967 research outputs found
Nondestructive detection of damage in carbon fibre composites by SQUID magnetometry
No full textMonitoring of structural integrity is an essential issue in enhancing the affordability as well the safety of modern aircraft and spacecraft structures. Increasingly, metallic parts of aircrafts are being replaced by carbon fibre composite components due to their high strength and stiffness combined with low density. This paper reviews of the use of superconducting quantum interference devices (SQUIDs) in the detection of different types of damage in carbon fibre panels. The results presented here on impact damage on carbon fibre reinforced polymer and cracks induced by tensile loads on carbon fibre reinforced carbon matrix show that this method is sensitive not only to the presence but also the severity of damage. Indeed, it enables one to distinguish between the different failure mechanisms as the damage process evolves. SQUIDs response to artificial delaminations, flaws and deep-lying defects are also presented. The application of a neural network system for the detection of impact damage in a noisy environment is discussed. Experimental results demonstrate that nondestructive evaluation using SQUID magnetometers is a suitable technique to investigate composites to improve their mechanical properties
MAGNETIC RESPONSE OF DAMAGED CARBON FIBER REINFORCED PLASTICS MEASURED BY HTS-SQUID MAGNETOMETER
No full textMagnetic response of damaged carbon fibre reinforced plastics measured by a HTS-SQUID magnetometer
No full textControlled states of damage were imparted to carbon fibre reinforced plastic panels, simply supporting them on a circular ring and applying a quasi-statically increasing transverse load at the centre. The damage state was controlled by interrupting the loading stage at predetermined values of the deflection. After mechanical tests, the panels were non-destructively inspected by a highly sensitive superconductive magnetometer (HTS SQUID), from which the maps of the parallel component of the magnetic field above the sample surface were obtained. A destructive analysis of the specimens was also carried out by optical microscopy, to assess damage features. The existence of a defect in the material was clearly signalled by a distortion in the magnetic field, even when an elastic behaviour could be guessed from the load-displacement curve. Until the loading conditions only resulted in failures in the matrix, the slope of the SQUID response along a line-scan was linearly dependent on the maximum energy applied to the specimen during the mechanical tests. The dependence of the slope on the energy was strongly altered when fibre failures were induced in the laminate. The magnetometer response was also influenced by the coil excitation frequency. The results obtained at different frequencies indicate that the optimum frequency can vary, depending on the scope of the non-destructive inspection under concern
Analysis of low-velocity impact damages in reinforced carbon fiber composites by HTS-SQUID magnetometers
No full textExperimental results in eddy current nondestructive testing based on superconductive and conventional electromagnetic probes.
No full textHigh Tc SQUIDs and Eddy-current NDE: a Comprhensive Investigation from Real Data to modelling
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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