An overview of tritium retention in dust particles from the JET-ILW divertor

Tritium (T) retention characteristics in dust collected from the divertor in JET with ITER-like wall (JET-ILW) after the third campaign in 2015-2016 (ILW-3) have been examined in individual dust particles by combining radiography (tritium imaging plate technique) and electron probe micro-analysis. The results are summarized and compared with the data obtained after the first campaign in 2011-2012 (ILW-1). The dominant component in ILW-1 dust was carbon (C) originating from tungsten-coated carbon fibre composite (CFC) tiles in JET-ILW divertor and/or legacy of C dust after the JET operation with carbon wall. Around 85 % of the total tritium retention in ILW-1 dust was attributede to the C dust. The retention in tungsten (W) and beryllium (Be) dominated particles was 100 times smaller than the highest T retention in carbon-based particles. After ILW-3 the main component contributing to the T retention was W. The number of small W particles with T increased, in comparison to ILW-1, most probably by the exfoliation and fragmentation of W coatings on CFC tiles though T retention in individual W particles was smaller than in C particles. The detection of only very few Be-dominated dust particles found after ILW-1 and ILW-3 could imply stable Be deposits on the divertor tiles.

Precision Fibre Angle Inspection for Carbon Fibre Composite Structures Using Polarisation Vision

This paper evaluates the precision of polarisation imaging technology for the inspection of carbon fibre composite components. Specifically, it assesses the feasibility of the technology for fibre orientation measurements based on the premise that light is polarised by reflection from such anisotropically conductive surfaces. A recently commercialised Sony IMX250MZR sensor is used for data capture by using various lighting conditions. The paper shows that it is possible to obtain sub-degree accuracy for cured and dry woven and unidirectional materials in ideal conditions, which comprised dark field illumination. Indeed, in ideal conditions, the average relative angles can be measured to an accuracy of 0.1–0.2°. The results also demonstrate a precision of the order 1° for more general illumination, such as dome illumination and ambient lighting, for certain material type/lens combinations. However, it is also shown that the precision varies considerably depending on illumination, lens choice and material type, with some results having errors above 2°. Finally, a feasibility study into the inspection of three-dimensional components suggests that only limited application is possible for non-planar regions without further research. Nevertheless, the observed phenomena for such components are, at least, qualitatively understood based on physics theory.

Novel Carbon Fibre Composite Centrifugal Impeller Design, Numerical Analysis, Manufacturing and Experimental Evaluations

This paper presents an experimental investigation on using high strength-to-weight composite materials to reduce the mass of a centrifugal compressor impeller by 600%. By reducing the blades number from 17 to 7 and by doubling their thickness, the compression ratio and efficiency were maintained close to the reference metallic impeller. Using autoclave technology, seven composite blades were manufactured individually and assembled to form the impeller. After manufacturing, small deviations were found at the blade’s tip. As these deviations were found to be symmetrical, impeller balancing was successfully performed removing a total of 45 g of mass, followed by an experimental test on a dedicated test bench. Experimental testing identified the resonant frequencies of the composite centrifugal impeller at 13.43 Hz 805 rot/min and at 77 Hz with a 0.1 mm/s amplitude at 4400 rot/min, highlighting feasibility and the advantage of a composite compressor impeller design with application in centrifugal compressors and rotating machine assemblies and sub-assemblies. As there are numerous numerical investigations performed on the strength analysis and on the lay-up orientations mechanical behaviour for polymer composite materials with respect to the design of centrifugal impellers, no experimental evaluations in relevant working conditions have been performed to date. As the paper contains relevant experimental data on the subject, the outcome of the paper may aid the oil and gas or aviation industries.

Development of an assistive device for adaptive cycling

Background Biomechanics literature has widely recognised the importance of creating modifying conditions for Sports for Persons with Disabilities, such as assistive devices. In this context, it is key that the motor function capacity and physical limitations of each person be taken into due account, leading to highly personalised equipment. This project optimised an assistive device for an adaptive cyclist that rides only with the right leg due to a transtibial amputation on the left leg, which remains supported by the assistive device, classifying him as C2 category for competitions, according to Union Cycliste Internationale (UCI). The purpose was to improve the comfort, ergonomics, and safety of the cyclist. Methods Reverse engineering, 3D modelling and manufacturing were the methodology applied to design the device with a crank-arm, a quick step-in pedal type clamp system, a carbon fibre composite shell, adapting the pedal position to support the cyclist stump, and an aluminium alloy 7075-T6 component to anchor to the seat post, providing stability to his body. Results The device which provided stability to the athlete's body was submitted to static and dynamic laboratory tests and real-life (in-track) try-outs. The developed clump system guarantees the athlete’s comfort and safety by automatically detaching him from the bicycle in case of fall. Conclusions The assistive device proved to be determinant for the athlete’s performance due the improvement of the comfort, ergonomics, and safety provided to the cyclist. Thus, qualifying him for the Tokyo 2021 Paralympic Games.

Numerical Fluid-Structure Interaction Analysis for a Flexible Marine Propeller Using Co-Simulation Method

Carbon fibre composite has exceptionally high strength, low density and corrosion resistance in the marine environment compared to conventional materials. These characteristics make it a favourable alternative material to be considered for manufacturing marine screw propellers. Despite these advantages, the flexibility of the material leads to a significant change in blade geometry due to loads acting on blades which alter hydrodynamic performance. A two-way coupled fluid-structure interaction analysis is required to accurately capture its hydrodynamic performance due to the reduced stiffness and material anisotropy. The present study focuses on numerical investigation for the hydro-elastic based performance analysis of a composite marine propeller in open water condition. The procedure involves the coupling of Reynolds-Averaged Navier-Stokes Equation based computational fluid dynamics solver with the finite element method solver using co-simulation technique. The open water characteristics, including thrust coefficient, torque coefficient and open water efficiency, are discussed as a function of advance ratio. This paper presents a comparison of the hydrodynamic performance and structural responses between a carbon fibre composite propeller and a conventional steel propeller which are geometrically identical. The results for the composite propeller show a significant improvement in hydrodynamic performance compared to the metallic propeller while remaining structurally safe throughout the tested range.