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Unlike metal structure, composite structures don’t give any clue till the fatal final collapse. The problem is more complicated when applied load on the structure is aeroelastic in nature. Under such loading, composite laminate experiences stresses. The first layer failure happens when stresses in the weakest ply exceed the allowable strength of the laminate. This initial layer-based failure changes overall material characteristics. It is important now to degrade the composite laminate characteristics for the subsequent failure prediction. The constitutive relations are required to be updated by the reduction in stiffness. The rest of the undamaged laminates continue to take the load till the updated strength is reached. In the present work, layer wise progressive failure analysis under aeroelastic loading has been performed by the inclusion of different failure criteria which allow for the identification of the location of the failure. ANSYS APDL environment has been used to model geometry of helicopter rotor. Under the loading conditions, stresses are calculated in the blade. Using stress tensor and failure criteria, failure location and modes have been predicted. It has been found that failure starts at higher speeds and failure starts from the root chord and tend towards the tip chord.

Formerly clandestine, abandoned and legacy nuclear facilities, whether associated with civil or military applications, represent a significant decommissioning challenge owing to the lack of knowledge surrounding the existence, location and types of radioactive material(s) that may be present. Consequently, mobile and highly deployable systems that are able to identify, spatially locate and compositionally assay contamination ahead of remedial actions are of vital importance. Deployment imposes constraints to dimensions resulting from small diameter access ports or pipes. Herein, we describe a prototype low-cost, miniaturised and rapidly deployable ‘cell characterisation’ gamma-ray scanning system to allow for the examination of enclosed (internal) or outdoor (external) spaces for radioactive ‘hot-spots’. The readout from the miniaturised and lead-collimated gamma-ray spectrometer, that is progressively rastered through a stepped snake motion, is combined with distance measurements derived from a single-point laser range-finder to obtain an array of measurements in order to yield a 3-dimensional point-cloud, based on a polar coordinate system—scaled for radiation intensity. Existing as a smaller and more cost-effective platform than presently available, we are able to produce a millimetre-accurate 3D volumetric rendering of a space—whether internal or external, onto which fully spectroscopic radiation intensity data can be overlain to pinpoint the exact positions at which (even low abundance) gamma-emitting materials exist.

Titania nanotubes (TNTs) are attractive for a variety of applications. In this study, amorphous TNTs have been synthesized by anodization. Annealing of anodized TNTs has been performed to get the anatase phase. Amorphous and annealed TNTs have been electrochemically reduced using 1 M KOH solution. For characterization of amorphous, annealed, electrochemically reduced amorphous and annealed TNTs, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energydispersive spectroscopy (EDS) techniques were used. The presence of C, F and K is detected from the full scan of X-ray photoelectron spectroscopy (XPS) analysis. The effect of electrochemical reduction on optical properties of TNTs under ambient conditions is studied using photoluminescence (PL) spectroscopy. The electrochemical reduction does not cause any appreciable morphological changes (evident from SEM images). However, XRD results show that this treatment produces strain in the anatase phase as a result of the increase in 'd' spacing between ( 101) and ( 202) planes. Photoluminescence spectroscopy of TNTs indicates that the defect states lie in the visible region for all the samples. These defects states have been found at 2.93 eV, 2.67 eV, 2.53 eV and 2.35 eV energies for amorphous TNTs. For annealed TNTs, these states have been observed at 2.67 eV and 2.35 eV. PL signal for amorphous TNTs is higher than the annealed TNTs. The electrochemical reduction treatment of the amorphous TNTs efficiently removes defects like F, K and C in addition to creating oxygen vacancies as compared to annealed TNTs. As these electrochemically reduced amorphous TNTs are exposed to ambient air for 7 days, the oxygen vacancies are filled. Moreover, in addition to removal of oxygen vacancies, these exposed and electrochemically reduced amorphous TNTs are devoid of other defects like F, K and C. This results in the significant reduction in PL intensity for such amorphous TNTs samples 7 days after electrochemical reduction. Due to the oxygen scavenging ability of electrochemically reduced TNTs, they could be used for vacuum improvement in various devices. This type of electrochemical reduction/recovery cycle makes these TNTs useful for the solar cell application under special (reduced/ absence of oxygen) conditions.

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