Search results for "sgbem"
showing 10 items of 23 documents
Analisi strutturale condotta con il BEM simmetrico in analogia al FEM
2009
Nell’articolo si presenta l’approccio agli spostamenti del Metodo Simmetrico degli Elementi di Contorno attraverso una suddivisione del corpo continuo in macroelementi denominati ebem. Attraverso questo approccio, caratterizzato da una forte condensazione delle variabili, si determina per ogni e-bem una matrice capostipite a partire dalla quale viene generata la relazione costitutiva del singolo e-bem. Quest’ultima relaziona soltanto variabili all’interfaccia tra i macroelementi, e precisamente il vettore delle trazioni pesate con il vettore degli spostamenti nodali e con il vettore delle azioni esterne. Una tale strategia è molto simile a quella seguita dal Metodo degli Elementi Finiti, ma…
SHAKEDOWN ANALYSIS BY BEM
2000
In the ambit of the symmetric Galerkin boundary element formulation the statical shakedown load multiplier and the limit analysis are reformulated making use of macrozone modelling. The subdivision of the domain into macroelements makes it possible to deal with piecewise homogeneous materials of the body. For each macroelement a discretization of the boundary and a subdivision of the domain into portions called cells are performed in order to introduce the unknowns (i.e. traction and displacement discontinuities) on the boundary and material plastic laws appropriately interpolated. The weighed regularity imposed between adjacent macroelements produces algebraic operators which are symmetric…
Elastoplastic analysis by active macro-zones with linear kinematic hardening and von Mises materials.
2014
In this paper a strategy to perform elastoplastic analysis with linear kinematic hardening for von Mises materials under plane strain conditions is shown. The proposed approach works with the Symmetric Galerkin Boundary Element Method applied to multidomain problems using a mixed variables approach, to obtain a more stringent solution. The elastoplastic analysis is carried out as the response to the loads and the plastic strains, the latter evaluated through the self-equilibrium stress matrix. This matrix is used both, in the predictor phase, for trial stress evaluation and, in the corrector phase, for solving a nonlinear global system which provides the elastoplastic solution of the active…
Multidomain Symmetric Galerkin BEM for non-linear analysis of masonries in-plane loaded
2014
The preservation of the historical and monumental buildings, but also of the considerable heritage of old constructions made by traditional techniques, is one of the actual problems of the structural mechanics. The level of knowledge of their structural behavior in presence of external actions is made through calculus methods and simple procedures in order to allow a reading of the material suffering degree and as a consequence of the related safety. In this paper an elastic analysis of walls, also in presence of geometrical nonlinearity consisting in the contact/detachment phenomenon among stone blocks. The wall having any shape and zone-wise variable physical characteristics is loaded in …
Frctionless contact: step by step analysis and mathematical programming technique
2011
The object of the paper concerns a consistent formulation of the classical Signorini's theory regarding the frictionless unilateral contact problem between two elastic bodies in the hypothesis of small displacements and strains. A variational approach employed in conjunction with the Symmetric Boundary Element Method (SBEM) leads to an algebraic formulation based on generalized quantities [1]. The contact problem is decomposed into two sub-problems: one is purely elastic, the other pertains to the unilateral contact conditions alone [2,3]. Following this methodology, the contact problem, by symmetric BEM, is characterized by symmetry and sign definiteness of the coefficient matrix, thus adm…
Symmetric Galerkin Boundary Element Metod for 3D analysis
1999
The mixed boundary value problem is dealt with by Galerkin approach in 3D linear elasticity via a system of boundary integral equations. This paper presents a method for computing a solving system coefficient made up of double surface integrals with hypersingular kernel. This method employs the Schwartz distribution theory in order to obtain the closed form of the first surface integration which represents the traction. The successive surface integration of the weighed traction having a kernel with logarithmic singularity uses known numerical techniques. This formulation requires C° continuity of shape functions modelling the source represented by the displacement discontinuity.
Frictionless contact formulation by mathematical programming technique
2011
The object of the paper concerns a consistent formulation of the classical Signorini's theory regarding the frictionless unilateral contact problem between two elastic bodies in the hypothesis of small displacements and strains. A variational approach, employed within the symmetric Boundary Element Method, leads to an algebraic formulation based on nodal quantities. The contact problem is decomposed into two sub-problems: one is purely elastic, and the other pertains to the unilateral contact condition alone. Following this methodology, the contact problem, faced with symmetric BEM, is characterized by symmetry and sign definiteness of the coefficient matrix, thus admitting a unique solutio…
Energetic criterion of the error evaluation in the analysis via SGBEM
2006
The Symmetric Galerkin Boundary Element Method (sGbem) is assuming more and more an effective role in the solving problems of mechanics in different fields of engineering [1]. The presence of symmetric and defined in sign algebraic operators make such Method more competitive in comparison to the formulation for collocation. The present work has as objective the improvement of the response in the process of analysis of the system where a first discretizazion has been operated, by using a strategy that allows to operate a estimate of the error. On the base of such estimate it is possible to operate a new discretizazion of the boundary through adaptive procedures.
La propagazione della frattura fragile nell'ambito della formulazione simmetrica del BEM
2009
A combined approach of SGBEM and conic quadratic optimization for limit analysis
2011
The static approach to evaluate the limit multiplier directly was rephrased using the Symmetric Galerkin Boundary Element Method (SGBEM) for multidomain type problems [1,2]. The present formulation couples SGBEM multidomain procedure with nonlinear optimization techniques, making use of the self-equilibrium stress equation [3-5]. This equation connects the stresses at the Gauss points of each substructure (bem-e) to plastic strains through a self-stress matrix computed in all the bem-elements of the discretized system. The analysis was performed by means of a conic quadratic optimization problem, in terms of discrete variables, and implemented using Karnak.sGbem code [6] coupled with MathLa…