Search results for "init"
showing 10 items of 6629 documents
Finite-Element Formulation of a Nonlocal Hereditary Fractional-Order Timoshenko Beam
2017
AbstractA mechanically-based nonlocal Timoshenko beam model, recently proposed by the authors, hinges on the assumption that nonlocal effects can be modeled as elastic long-range volume forces and moments mutually exerted by nonadjacent beam segments, which contribute to the equilibrium of any beam segment along with the classical local stress resultants. Long-range volume forces/moments linearly depend on the product of the volumes of the interacting beam segments, and on pure deformation modes of the beam, through attenuation functions governing the space decay of nonlocal effects. This paper investigates the response of this nonlocal beam model when viscoelastic long-range interactions a…
On the Effect of Slotted Blades on Savonius Wind Generator Performances by CFD Analysis
2012
In this paper a new bucket configuration for Savonius wind generator is proposed. With the aim to increase the effect of the overlap ratio RS on the wind turbine performances and to increase the amount of lift force able to produce torque and power, slotted blades are investigated by means of the Computational Fluid Dynamics analysis. The numerical analyses are performed by Comsol Multiphysics® and the results obtained for a Savonius wind turbine with overlap only are compared to numerical and experimental benchmarks. Parametric analyses are performed, for fixed overlap ratio, by varying the slot angle β and the results show that for low angle β the Savonius rotor exploits improved performa…
Metallurgical Evolutions in Hot Forging of Dual Phase Titanium Alloys: Numerical Simulation and Experiments
2015
Titanium forging has been encountering a growing interest in the scientific and industrial communities because of the distinct advantages it provides with respect to machining, in terms of both mechanical properties of the product and material waste, thus significantly reducing the Buy to Fly ratio. In the paper, a numerical FE model, based on a tri-coupled approach and able to predict the microstructural evolutions of the workpiece during the process, is developed and set up. Calculated results are compared to experiments for a few industrial case studies. The final phases distribution in the forged parts is experimentally measured and compared to the FE model output finding satisfying ove…
Atypical titration curves for GaAl12Keggin-ions explained by a joint experimental and simulation approach
2018
Although they have been widely used as models for oxide surfaces, the deprotonation behaviors of the Keggin-ions (MeAl127+) and typical oxide surfaces are very different. On Keggin-ions, the deprotonation occurs over a very narrow pH range at odds with the broad charging curve of larger oxide surfaces. Depending on the Me concentration, the deprotonation curve levels off sooner (high Me concentration) or later (for low Me concentration). The leveling off shows the onset of aggregation before which the Keggin-ions are present as individual units. We show that the atypical titration data previously observed for some GaAl12 solutions in comparison to the originally reported data can be explain…
Continental weathering and climatic changes inferred from clay mineralogy and paired carbon isotopes across the early to middle Toarcian in the Paris…
2014
Abstract Lower Toarcian strata (Lower Jurassic) have been extensively studied with a view to understanding the oceanographic, climatic and biological processes that drove the Earth's system into an Oceanic Anoxic Event (OAE). For this time period, the evolution of the European marine seaways is now relatively well constrained owing to multiple geochemical studies, but investigations regarding climatic trends in the continental realm remain sparse. In the present study, we test the clay mineralogy as a continental climate-sensitive proxy in the well-documented Sancerre core (southern Paris Basin). We compare variations in the kaolinite content with p CO 2 fluctuations (derived from paired ca…
Development of helium coolant DEMO first wall model for SYCOMORE system code based on HCLL concept
2018
Abstract The conceptual design of the demonstration fusion power reactor, known as DEMO, is ongoing and several reactor configurations have to be investigated by exploring different design parameters. For these reasons, within the European framework, systems codes like SYCOMORE (SYstem COde for MOdelling tokamak REactor) have been developed. SYCOMORE includes several specific modules, one of which is aimed to define a suitable design of the helium breeding blanket. The research activity has been devoted to improve the method to define automatically the First Wall design starting from thermal-hydraulic and thermo-mechanical considerations, using analytical design formulae and, also, taking i…
Intrusion of nonwetting liquid in paper
2007
The saturation curve of a sample of paper board was measured with mercury-intrusion porosimetry, and the three-dimensional structure of its pore space was determined by x-ray tomographic imaging. Ab initio numerical simulation of intrusion on the tomographic reconstruction, based on the lattice-Boltzmann method, was in excellent agreement with the measured saturation curve. A numerical invasion-percolation simulation in the same tomographic reconstruction showed good agreement with the lattice-Boltzmann simulation. The access function of the sample, determined from the saturation curve and the pore-throat distribution determined from the tomographic reconstruction, indicated that the ink-bo…
A genetic algorithm for combined topology and shape optimisations
2003
A method to find optimal topology and shape of structures is presented. With the first the optimal distribution of an assigned mass is found using an approach based on homogenisation theory, that seeks in which elements of a meshed domain it is present mass; with the second the discontinuous boundaries are smoothed. The problem of the optimal topology search has an ON/OFF nature and has suggested the employment of genetic algorithms. Thus in this paper a genetic algorithm has been developed, which uses as design variables, in the topology optimisation, the relative densities (with respect to effective material density) 0 or 1 of each element of the structure and, in the shape one, the coord…
TOPOLOGY OPTIMIZATION OF A CONNECTING ROD FOR AN INTERNAL COMBUSTION ENGINE
2009
The topology optimization of a structure is a process that allows to establish if in a point of an assigned domain there should be some material. No assumption is made with regard to the number and the distribution of the contours and the final topology, that can be very different compared to that one initially hypothesized. In this paper a study related to the topology optimization of a connecting rod for an internal combustion engine is presented. The used technique for the optimization is the density (or distribution of material) method. The developed application, besides giving an innovative solution of the topology of the connecting rod with a lower mass in comparison with the initial …
On the numerical assessment of the thermo-mechanical performances of the DEMO Helium-Cooled Pebble Bed breeding blanket module
2014
Within the framework of the European DEMO Breeder Blanket Programme, a research campaign has been launched by University of Palermo, ENEA-Brasimone and Karlsruhe Institute of Technology to theoretically investigate the thermo-mechanical behavior of the Helium-Cooled Pebble Bed (HCPB) breeding blanket module of the DEMO1 blanket vertical segment, under normal operation and over-pressurization loading scenarios. The research campaign has been carried out following a theoretical-computational approach based on the finite element method (FEM) and adopting a qualified commercial FEM code. A realistic 3D FEM model of the HCPB blanket module central poloidal-radial region has been developed, inclu…