Search results for "sgbem"

Impiego dei sottodomini via SBEM nell’analisi delle murature

2008

Il metodo degli spostamenti nella formulazione simmetrica degli elementi di contorno

2000

Il metodo degli elementi di contorno nella sua versione simmetrica (SGBEM) sta assumendo un ruolo sempre più incisivo per la soluzione di vari problemi di ingegneria. Recentemente ci si è occupati di impiegare tale metodo a corpi bidimensionali piani costituiti da materiale aventi differenti proprietà fisiche attraverso una suddivisione in sottodomini denominati macroelementi.

Internal spring distribution for quasi brittle fracture via Symmetric Boundary Element Method

2009

Abstract In this paper the symmetric boundary element formulation is applied to the fracture mechanics problems for quasi brittle materials . The basic aim of the present work is the development and implementation of two discrete cohesive zone models using Symmetric Galerkin multi-zone Boundary Elements Method . The non-linearity at the process zone of the crack will be simulated through a discrete distribution of nodal springs whose generalized (or weighted) stiffnesses are obtainable by the cohesive forces and relative displacements modelling. This goal is reached coherently with the constitutive relation σ − Δ u that describes the interaction between mechanical and kinematical quantities…

A SGBEM approach for static shakedown analysis as CQO problem

2011

In this paper the shakedown static approach was rephrased by using the Symmetric Galerkin Boundary Element Method (SGBEM) for multidomain type problems. The present formulation utilizes the self-equilibrium stress equation, connecting the stresses at the Gauss points of each substructure (bem-e) to plastic strains, through a stiffness matrix (self-stress matrix), involving all the bem-elements of the discretized system. The optimization problem was solved by Conic Quadratic Optimization (CQO) and implemented using the Karnak.sGbem code coupled with MatLab. In order to prove the efficency of the proposed strategy, some numerical tests, in which the shakedown multiplier was checked by SGBEM e…

Tecniche di trasformazione di integrali di dominio in integrali di contorno nell'ambito del SBEM

2008

Characteristic matrix in the bending plate analysis by SBEM

2008

This paper deals with the thin bending plate analysis by using the symmetric approach of Boundary Element Method (SBEM). A formulation is used in which the plate boundary is discretized into boundary elements and is subjected to appropriate distributions of shear forces and couples, as well as of vertical displacement and rotations. These distributions are the causes and are modelled through appropriate shape functions, whereas the generalized effects are obtained, according to the Galerkin approach, as weighting of the displacements and the rotations, as well as of the shear forces and moments. In the equations system the algebraic operator is a symmetric matrix whose coefficients are defi…

Lower bound limit analysis by bem: Convex optimization problem and incremental approach

2013

Abstract The lower bound limit approach of the classical plasticity theory is rephrased using the Multidomain Symmetric Galerkin Boundary Element Method, under conditions of plane and initial strains, ideal plasticity and associated flow rule. The new formulation couples a multidomain procedure with nonlinear programming techniques and defines the self-equilibrium stress field by an equation involving all the substructures (bem-elements) of the discretized system. The analysis is performed in a canonical form as a convex optimization problem with quadratic constraints, in terms of discrete variables, and implemented using the Karnak.sGbem code coupled with the optimization toolbox by MatLab…

Strain energy evaluation in structures having zone-wise physical-mechanical quantities

2013

Active macro-zone approach for incremental elastoplastic-contact analysis

2013

The symmetric boundary element method, based on the Galerkin hypotheses, has found an application in the nonlinear analysis of plasticity and in contact-detachment problems, but both dealt with separately. In this paper, we want to treat these complex phenomena together as a linear complementarity problem. A mixed variable multidomain approach is utilized in which the substructures are distinguished into macroelements, where elastic behavior is assumed, and bem-elements, where it is possible that plastic strains may occur. Elasticity equations are written for all the substructures, and regularity conditions in weighted (weak) form on the boundary sides and in the nodes (strong) between cont…

Incremental elastoplastic analysis for active macro-zones

2012

In this paper a strategy to perform incremental elastoplastic analysis using the symmetric Galerkin boundary element method for multidomain type problems is shown. The discretization of the body is performed through substructures, distinguishing the bem-elements characterizing the so-called active macro-zones, where the plastic consistency condition may be violated, and the macro-elements having elastic behaviour only. Incremental analysis uses the well-known concept of self-equilibrium stress field here shown in a discrete form through the introduction of the influence matrix (self-stress matrix). The nonlinear analysis does not use updating of the elastic response inside each plastic loop…