Search results for "Structural Engineering"
showing 10 items of 1998 documents
Effects of external energetic factors on tritium release from the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles
2009
Abstract Tritium release from samples of 9–13 mg of the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles under the separate and simultaneous action of temperature 490–770 K, 5 MeV fast-electron radiation 14 MGy h−1 for 3 h and magnetic field (MF) of 1.7 T was investigated. The pebbles were found to be very dissimilar with respect to their total tritium content—2.5–9 MBq g−1. The batch contained also some coarse agglomerates of the pebbles containing 10–19 MBq g−1 of tritium having also a high tritium release. For the pebbles having the total tritium 2.5–5.3 MBq g−1, the electron radiation for 3 h caused the fractional tritium release 17–26% (B = 0) and 21–29% (B = 1.7 T), the temperature …
Radiation effects on stress evolution and dimensional stability of large fusion energy structures
2021
Abstract We assess the effects of neutron irradiation on the deformation and stress evolution of large-scale fusion energy structures. This is accomplished through non-linear finite element structural analysis of the coupled thermal and mechanical fields at the Beginning-Of-Life (BOL), at 45 dpa, and at 90 dpa. Radiation effects include volumetric swelling and the influence of radiation on the mechanical properties. The system studied here is a large section of a full inboard module of an integrated structure comprising the First Wall and Blanket (FW/B) of a Dual Cooled Lithium-Lead (DCLL) energy conversion unit in the Fusion Nuclear Science Facility (FNSF). The structural material is the f…
Fatigue Crack Growth Rate under Different Bending to Torsion Ratios in 10HNAP Steel
2011
The paper contains the fatigue test results of rectangular cross-section specimens made of 10HNAP steel. The specimen height to width ratio was 1.5. Bending with torsion tests were carried out for the following ratios of bending to torsional moments MaB / MaT = 0.47, 0.94, 1.87 and the loading frequency 26.5 Hz. The tests were performed in a high cycle fatigue regime for the stress ratio R = - 1 and phase shift between bending and torsion loading equal to = 0.
Laboratory and in-situ tests for estimating improvements in asphalt concrete with the addition of an LDPE and EVA polymeric compound
2019
Abstract Pavement deformation is a critical issue in the design of pavement structures and the related mixture. Asphalt concretes may be very sensitive to this problem, in compliance with the viscoelastic behaviour of the adopted bitumen. To improve the material performance, many attempts have been made to introduce in the mixture other materials as “modifiers” or “additives” for increasing the permanent deformation resistance and the elastic modulus of the material. Among the different possible materials, polymers determined significant improvements in the road pavement performance. In this paper, the authors tested the adoption of a specifically engineered polymeric compound, in order to …
The effect of introduction of montmorillonite clay (MMT) on the elastic properties of polycarbonate (PC) composition with acrylonitrile-butadiene sty…
2015
Abstract Polycarbonate (PC)/acrylonitrile–butadiene–styrene terpolymer (ABS)/montmorillonite (MMT) nanocomposites have been obtained by melt compounding in a twin-screw extruder. Structural and elastic properties have been characterized. The theoretical analysis of the elastic properties of PC/ABS/MMT composite with a widely varied number of elementary layers in clay filler particles has been performed in order to estimate the influence of the degree of exfoliation of particles on the effect of reinforcement of the material. Results of the theoretical analysis have been compared with the experimental data about the effects of unmodified and two types of organically modified montmorillonite …
Parameters influencing the stiffness of composites reinforced by carbon nanotubes – A numerical–analytical approach
2014
Abstract Due to their high stiffness and strength, as well as their electrical conductivity, carbon nanotubes are under intense investigation as fillers in polymer matrix composites. The nature of the carbon nanotube/polymer bonding and the curvature of the carbon nanotubes may strongly reduce the reinforcing effect of the carbon nanotubes when added to a matrix to create composites. Here the effects of carbon nanotube waviness and the interaction with the matrix on the stiffness of the composite are investigated. Using a mixed numerical–analytical model, a parametric study of the waviness and volume fraction influence of CNTs on the elastic behavior of the nanocomposite is presented. The m…
Elasticity and long-term behavior of recycled polyethylene terephthalate (rPET)/montmorillonite (MMT) composites
2014
Abstract Recycled polyethylene terephthalate (rPET) nanocomposites with various amounts of montmorillonite clay (MMT) have been manufactured by using twin screw extrusion. By rising MMT weight content Wf up to 1 wt.% it is possible to increase yield strength and ultimate strength of the composite by 17% and 27% respectively in comparison to neat rPET. Introduction of MMT in the rPET leads also to considerable increase of the modulus of elasticity E. Relationship E(Wf), however, is non-linear and is characterized by slow-down in E growth along with increasing MMT content. At low nanofiller content experimental results are sufficiently well described by using the method of Mori–Tanaka and the…
On the thermal-hydraulic performances of the DEMO divertor cassette body cooling circuit equipped with a liner
2020
Abstract In the framework of the Work Package DIV 1 - “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by University of Palermo and ENEA to investigate the steady-state thermal-hydraulic performances of the DEMO divertor cassette cooling system. The research activity has been focussed onto the most recent design of the Cassette Body (CB) cooling circuit, consistent with the DEMO baseline 2017 and equipped with a liner, whose main function is to protect the underlying vacuum pump CB opening from plasma radiation. The research campaign has been carried out following a theoretical-computational approach based on the finite vo…
Thermal-hydraulic study of the DEMO divertor cassette body cooling circuit equipped with a liner and two reflector plates
2021
Abstract In the framework of the Work Package DIV 1 – “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by University of Palermo and ENEA to investigate the steady-state thermal-hydraulic performances of the DEMO divertor cassette cooling system. The research activity has been focussed onto the most recent design of the Cassette Body (CB) cooling circuit, consistent with the DEMO baseline 2017 and equipped with a liner and two Reflector Plates (RPs), whose main functions are to protect the underlying vacuum pump hole from the radiation arising from plasma and shield the PFCs inlet distributors, respectively. The research ca…
Thermal optimization of the Helium-Cooled Lithium Lead breeding zone layout design regarding TBR enhancement
2017
Abstract Within the framework of EUROfusion R&D activities, CEA-Saclay has carried out an investigation of the thermal and mechanical performances of alternative designs intended to enhance the Tritium Breeding Ratio (TBR) of the Helium-Cooled Lithium Lead (HCLL) Breeding Blanket (BB) for DEMO. Neutronic calculations performed on the 2014 DEMO HCLL baseline predicted a value of TBR equal to 1.07, lower than the required value of 1.1, necessary to ensure the tritium self-sufficiency of the breeding blanket taking into account uncertainties. In order to reach the TBR target, the strategy of the steel amount reduction inside the HCLL module breeding zone (BZ) has been followed by suppressing s…