Search results for "Finite Element"
showing 10 items of 892 documents
Multi-physical modelling of Reverse ElectroDialysis
2016
Energy extraction from salinity gradients (salinity gradient power, SGP) represents a novel and valuable renewable energy source. Among the existing SGP technologies, reverse electrodialysis (RED) is the oldest and one of the most promising. RED is a membrane-based electrochemical process that directly converts the salinity gradient energy into electric current. More precisely, in a RED unit two solutions at different concentration flow in two series of alternated channels, which are formed by piling two alternated series of cation and anion exchange membranes (CEMs and AEMs, respectively). The chemical potential difference between the two solutions generates an electric potential differenc…
Experimental and Numerical Analysis of the Distribution of Residual Stresses Induced by Laser Shock Peening in a 2050-T8 Aluminium Alloy
2011
Laser shock peening (LSP) is an innovative surface treatment technique successfully applied to improving fatigue performance of metallic material. The specific characteristic of (LSP) is the generation of a low work-hardening and a deep compressive residual stresses mechanically produced by a laser-induced shock wave propagating in the material. The aim of this study is to analyse the residual stress distribution induced by laser peening in 2050-T8 aluminium alloy experimentally by the X-ray diffraction technique (method sin2Y) and numerically, by a finite element numerical modelling. A specific focus was put on the residual stress distribution along the surface of the impacted material.
Analysis of laser shock waves and resulting surface deformations in an Al-Cu-Li aluminium alloy
2012
Abstract Laser shock processing is now a recognized surface treatment for improving fatigue or corrosion behaviour of metallic materials through the generation of a compressive stress field. In turn, the analysis of shock wave propagation is of primary importance to predict numerically morphological and mechanical surface modifications. Considering experimental and numerical analyses of shock wave propagation, and surface deformations induced by single impacts, a 2050 aluminum alloy having different microstructures was investigated under laser-shock loading. In a first step, the evolution of shock wave attenuation and elastic precursor amplitude was correctly reproduced by finite element si…
Analysis of Stray Flux Spectral Components in Induction Machines under Rotor Bar Breakages at Various Locations
2018
Induction machines under rotor electrical faults have been subjected to intensive research over the years. It is not only the nature of the fault that makes it important to study, but also the differences observed regarding this fault's effect on the motor's conditions. One of these conditions is the rotor bar breakages at non adjacent positions, which has drawn the attention of researchers due to the false negative diagnostic alarms that may be caused. In this paper, a novel approach is presented aiming to reliably detect this type of fault condition. The proposed method is based on the analysis of specific subcomponents of the stray flux over time. The analysis is implemented on an indust…
Gradient with respect to nodes for non-isoparametric finite elements
2006
We consider the problem of controlling the solution of a finite element model using the nodal co-ordinates as control variables. The main emphasis is on the study of the applicability of the domain deformation method for different element types. The results are applied to a simple problem of finite element grid optimization.
Numerical Calibration of a Simplified Model for FRP Confinement of Columns
2018
This paper presents the calibration of a simplified analytical model for concrete columns confined by fiber reinforced polymer (FRP) jackets. The model allows evaluating the increase of strength, ductility and dissipated energy without defining the lateral confinement pressure and it can be easily extended for the assessment of FRP confinement in design applications. This model was obtained by a simplified procedure based on the best fit of experimental data available in the literature and the coefficient of determination (R2) was evaluated in order to estimate the accuracy of the regression analysis. A numerical database resulting from finite element (FE) analyses was compiled and reported…
A three-dimensional back-analysis of the collapse of an underground cavity in soft rocks
2017
Abstract The assessment of stability of man-made underground caves, excavated in the past and later on abandoned, represents a serious challenge for land and urban planning operations, especially for the areas of possible interaction of the caves with overlying structures and infrastructures. Several areas of Southern Italy are characterized by the presence of abandoned underground quarries for the extraction of soft calcarenite rocks, which now threatens the overlying environment due to the risk of collapse and the consequent generation of sinkholes. This work presents a back-analysis of a sinkhole occurred in 2011 in the town of Marsala, caused by the collapse of an underground quarry, as…
A FEM piezoelectric beam model for damping circuit analysis
2013
A finite element, developed for straight generally layered smart beam, is used to investigate vibration damping capability of circuit elements. First, the electric state is analytically condensed to kinematical quantities and the mechanical model is then written for shear deformable Timoshenko’s beam including the effects of electro-elastic couplings stacking sequence. The contributions of the external electric loads on both the equivalent stiffness properties and the equivalent mechanical boundary conditions are also taken into account. The finite element is formulated by using Hermite shape functions, which depend on parameters representative of the staking sequence through the equivalent…
A beam finite element for magneto-electro-elastic multilayered composite structures
2012
Abstract A new finite element based upon an elastic equivalent single-layer model for shear deformable and straight magneto-electro-elastic generally laminated beam is presented. The element has six degrees of freedom represented by the displacement components and the cross-section rotation of its two nodes. The magneto-electric boundary conditions enter the discrete problem as work-equivalent forces and moments while the electro-magnetic state characterization constitutes a post-processing step. The element possesses the superconvergence property for the static problem of beams with uniform cross-section and homogenous material properties along the beam axis direction. Moreover, it is free…
Penalty Function Methods for the Numerical Solution of Nonlinear Obstacle Problems with Finite Elements
2008
A class of penalty function methods for the solution of nonlinear variational inequalities with obstacles ⩽ 0 fur alle v ⩾ ψ in the Sobolev space W1, p (ω) is studied. The (nonlinear) penalty equations are solved by finite element techniques; the order of convergence of this procedure which depends on the regularity of the solution as well as on the finite elements used is investigated. Eine Klasse von Penalty-Methoden zur Losung nichtlinearer Variationsungleichungen mit Hindernisnebenbedingungen ⩽ 0 fur alle v ⩾ ψ im Sobolev Raum W1, p (ω) wird untersucht. Die (nichtlinearen) Penalty-Gleichungen werden mit Hilfe der Finite Elemente Methode gelost; die Konvergenzordnung dieses Verfahrens, w…