Jose Claudio F. Telles

Federal University of Rio de Janeiro | UFRJ · Instituto Alberto Luiz Coimbra de Pós-Graduação e Pesquisa de Engenharia (COPPE)

Reinforced concrete (RC) structures are widely used in engineering due to their physical, chemical and mechanical characteristics that guarantee good durability. However, one of the main mechanisms of degradation of these structures is associated with the corrosion of the reinforcement, which often occurs due to carbonation of the concrete and/or t...

The design of cement sheaths in offshore oil wells is usually performed following a deterministic approach, which doesn’t consider explicitly the variability and uncertainties in material properties and loads. Cement properties can vary, for instance, due to the intrinsic nature of the cementation process. Load uncertainties are attributed to the r...

Understanding cement shrinkage behavior in offshore well cement sheaths is crucial for assessing integrity and preventing potential issues. This study investigates the correlation between early strength development and shrinkage to assist in cement paste design. In this research, one cement paste was formulated with water-to-cement ratio of 0.36 an...

The present paper focuses on the development of an efficient and simple formulation based on Method of Fundamental Solutions (MFS) for simulation of steady potential problems in heterogeneous media. In this formulation, proper Green's functions are used to deal with the heterogeneity of the problems. These functions are here modified by the image-s...

This paper presents a generalized formulation to describe nonuniform torsion in composite bars with variable cross section including higher-order warping modes. In that, the boundary-element subregion-by-subregion (BE SBS) technique is applied to determine the warping modes for cross sections constituted of any number of different materials. The di...

This paper presents a simple formulation based on Method of Fundamental Solutions (MFS) for the numerical solution of non-homogeneous potential problems. This formulation makes use of Green's functions for dealing with the non-homogeneity of the problems. These Green's functions are here modified by the method of images, aiming limiting the number...

A frequency-domain formulation based on Method of Fundamental Solutions (MFS) is here addressed for the modeling of sound-absorbing barriers on an infinite plane ground in the presence of a point source. In this formulation, the full discretization of both ground and barrier is avoided by using Green’s functions obtained by the method of images. I...

The present paper deals with the development of a Galerkin Boundary Element Method (Galerkin-BEM) approach applied to the numerical simulation of plane and half-plane quasi-static viscoelastic problems. This approach makes use of a half-plane viscoelastic fundamental solution, thus avoiding the full discretization of the half-plane and consequently...

In this paper a parallel implementation strategy is presented, for meshless methods, using principles of functional programming and memory polymorphism. The meta-programming presented technique has been developed to guarantee portability of performance in different execution spaces and simplified representation of the mathematical physics model thr...

This paper will present Finite Element models to study the thermo-chemo-mechanical behaviour of concrete structures taking into account both aging and damage. The analysis is composed of two separated models, namely: thermo-chemical and thermo-mechanical with damage. First, the thermo-chemical model will be briefly presented. Then, the thermo-mecha...

The required current to efficiently protect external bottom of aboveground storage tanks by means of impressed current cathodic protection was evaluated and optimised for anode number and positioning. The study introduced a numerical polarization curve obtained by inverse analysis, using a genetic algorithm, based on potential values measured in a...

This work presents a numerical modeling procedure to simulate the refractory concrete lining in fluid catalytic cracking units of oil refineries. The model includes the simulation of the anchors that reinforce the contact between the refractory concrete and the steel casing. For this purpose, the constitutive relations of an interface finite elemen...

In this paper, the Method of Fundamental Solutions (MFS) and the Meshless Local Petrov-Galerkin (MLPG) method are applied to the numerical simulation of Cathodic Protection (CP) systems. The problem of CP systems is governed by the Laplace equation. In this problem, the boundary conditions are characterized by a nonlinear relationship between the e...

In this paper, the Local Radial Point Interpolation Method (LRPIM) is applied to analyse the problem of plates according to the Reissner’s theory. An efficient interpolation scheme is employed to improve the computational performance of the proposed method. To validate the numerical implementation of the LRPIM, the results are compared with those p...

Mathematical formulations for the electrochemical potential problem are proposed, considering the following methods: The Boundary Element Method (BEM), the Method of Fundamental Solutions (MFS) and the Meshless Local Petrov-Galerkin (MLPG-2) procedure. Furthermore, in order to deal with the strongly nonlinear polarization, a boundary element method...

Over the last decades, several computer codes have been developed aiming at the full 3D simulation of cathodic protection (CP) systems. CP is a technique applied to prevent corrosive processes and the main goal of the sim- ulation has been to predict the degree of corrosion control achieved. Many pioneering works allowed for the successful applicat...

This paper presents a numerical analysis of bending plates considering Reissner’s hypothesis. A truly meshless method designated Meshless Local Petrov-Galerkin (MLPG) method is used to obtain a linear system of equation. A simplified Radial Point Interpolation Method (RPIM) approximation scheme, by centering both quadrature and local interpolation...

The purpose of this work is to efficiently evaluate the design of cathodic protection (CP) systems of tank bottoms using concentric ring or linear anodes. As customary in current CP systems, the outer surface of the tank bottom is usually in electrical contact with a slender homogeneous layer of conductive concrete (or something similar) which in t...

Neste trabalho, o Método sem Malha Local Petrov-Galerkin (MLPG – sigla em inglês) é aplicado para resolver o problema de proteção catódica (CP). Esse método faz uso da função delta de Dirac como função de ponderação. O problema de potencial eletroquímico é governado pela equação de Laplace. Nesse problema, as condições de contorno são dadas por uma...

The purpose of this work is to efficiently evaluate the design of cathodic protection (CP) systems of tank bottoms using concentric ring or linear anodes. As customary in current CP systems, the outer surface of the tank bottom is usually in electrical contact with a slender homogeneous layer of conductive concrete (or something similar) which in t...

The computational implementation of moving least squares (MLS) shape functions is an important step to consider in some versions of the meshless local Petrov–Galerkin (MLPG) method for a variety of two-dimensional engineering problems. Here, the usage of conventional Gaussian quadrature in the MLPG may require an excessive number integration points...

The purpose of this work is to numerically find the optimum location of constant potential anodes to ensure complete structure surface protection using a cathodic protection technique. The existence of sacrificial anodes is originally introduced through the boundary conditions of the corresponding boundary value problem (BVP). However, if constant...

The boundary element method has been applied with success to linear elastic fracture mechanic problems, involving static and dynamic cases. In order to solve body force problems (e.g., gravitational forces and transient problems with velocities and accelerations), Nardini and Brebbia presented, in 1982, the dual reciprocity formulation. Originally...

This paper presents a coupled FEM-BEM strategy for the numerical analysis of elastodynamic problems where infinite-domain models and complex heterogeneous media are involved, rendering a configuration in which neither the Finite Element Method (FEM) nor the Boundary Element Method (BEM) is most appropriate for the numerical analysis. In this case,...

The present paper aims at developing a method to accommodate multi-surface concrete plasticity from the point of view of a consistency concept applied to general tangent operators. The idea is based on a Taylor series expansion of the actual effective stress at the stress point corresponding to the previous accumulated true stresses plus the curren...

A truly meshless iterative coupling is presented to solve linear elastic fracture mechanic (LEFM) problems. The global domain of the problem is decomposed into sub-domains, where each one is addressed using an appropriate meshless method. The sub-domain which has embedded cracks is modeled by the method of fundamental solutions (MFS) with the help...

The method of fundamental solutions (MFS) is used for the solution of Laplace’s equation, with nonlinear boundary conditions, aiming at analyzing cathodic protection systems. In the MFS procedure, it is necessary to determine the intensities and the distribution of the virtual sources so that the boundary conditions of the problem are satisfied. Th...

An iterative coupling procedure using different meshless methods is presented to solve linear elastic fracture mechanic (LEFM) problems. The domain of the problem is decomposed into two sub-domains, where each one is addressed using an appropriate meshless method. The method of fundamental solutions (MFS) based on the numerical Green's function (NG...

This paper presents a simple and effective method to model the wetting and drying of coastal areas by the tide. The approach considers an equivalent "rough-porous layer" (RPL), wetting and drying method. The method can be easily implemented in finite elements, which makes it useful in numerical modeling of natural water bodies with intricate topogr...

The method of fundamental solutions (MFS) is used for the solution of Laplace’s equation, with nonlinear boundary conditions, aiming at analyzing cathodic protection systems of external problems within infinite regions (e.g. seawater). In the MFS procedure, it is necessary to determine the intensities and the distribution of the virtual sources so...

The method of fundamental solutions (MFS) is used for the solution of Laplace׳s equation, with nonlinear boundary conditions, aiming at analyzing cathodic protection systems. In the MFS procedure, it is necessary to determine the intensities and the distribution of the virtual sources so that the boundary conditions of the problem are satisfied. Th...

This work presents a methodology to simulate the interface behavior between steel and refractory concrete, two materials used in Fluid Catalytic Cracking (FCC) units and commonly bonded by anchor systems. A special interface element that considers the interaction of the steel anchorages and the concrete lining was developed using a finite element m...

In this paper the inverse problem of electrical impedance tomography (EIT) in a three dimensional environment is considered. In this technique, electrodes are placed on the external boundary of the body and electrical current is injected by sequentially activating pairs of them while the corresponding potentials are measured. Usually such measures...

The method of fundamental solutions (MFS) is used for the solution of Laplace's equation, with nonlinear boundary conditions, aiming at analyzing cathodic protection systems. In the MFS procedure it is necessary to determine the intensities and the distribution of the virtual sources so that the boundary conditions of the problem are satisfied. The...

Tidal wetlands are among the most important natural ecosystems and they play a variety of ecological functions. They are generally maintained by a flooding and drying tidal related cycle. Such cycles play an essential role in exchanging material over the estuarine and mangrove swamp complex. Therefore, the capacity to forecast the hydrodynamic proc...

The method of fundamental solutions (MFS) is applied to solve linear elastic fracture mechanics (LEFM) problems. The approximate solution is obtained by means of a linear combination of fundamental solutions containing the same crack geometry as the actual problem. In this way, the fundamental solution is the very same one applied in the numerical...

The aim of this paper is to present numerical simulations of Cathodic Protection (CP) Systems using a Genetic Algorithm (GA) and the Method of Fundamental Solutions (MFS). MFS is used to obtain the solution of the associated homogeneous equation with the non-homogeneous equation subject to nonlinear boundary conditions defined as polarization curve...

The aim of this paper is to present numerical simulations of Cathodic Protection (CP) Systems using a Genetic Algorithm (GA) and the Method of Fundamental Solutions (MFS). MFS is used to obtain the solution of the associated homogeneous equation with the non-homogeneous equation subject to nonlinear boundary conditions defined as polarization curve...

Over the last few years the Boundary Element Method (BEM) has been successfully applied to linear elastic fracture mechanics problems (LEFM), involving static and dynamic cases. An approach to solve LEFM problems is presented in this work. The Numerical Green's Function is used at the fundamental solution together with the Operational Quadrature Me...

This paper presents a simple and effective method to model wetting and drying processes in natural water bodies. The proposed method has been nicknamed \“rough-porous layer”, or RPL. It bears similarities with the so called marsh porosity method, but is simpler to implement, mass conserving and does not affect wave celerity in wet areas. The method...

The Hilbert-Huang Transform (HHT) is extended to the time series analysis of wave orbital velocities resulting from the superposition of waves propagating in different directions. On a theoretical basis, it is shown that an apparently chaotic velocity signal may result from the interaction of three or more waves, each one with its own period and di...

After years dominating high performance computing, expensive vector computers were gradually replaced by more affordable solutions and the use of vectorization techniques once applied to many scientific codes also faded. This paper addresses the vectorization of engineering codes using Streaming SIMD Extensions (SSE) also known as multimedia instru...

In this work the boundary element method is applied to solve 2D elastoplastic problems. In elastoplastic boundary element analysis, domain integrals have to be calculated to introduce the contribution of yielded zones. Traditionally, the use of internal integration cells have been adopted to evaluate such domain integrals. The present work, however...

This work aims at extending the concept of the Numerical Green's Function (NGF), known from boundary element applications to potential and fracture mechanics problems, to the Local Boundary Integral Equation (LBIE) context. As a "companion" solution, the NGF is used to remove the integrals of the main discontinuities over the crack boundary and is...

The present work introduces a boundary element formulation adopting an alternative procedure to remove domain cell discretization commonly used to simulate velocity correcting fields needed to account for potential problems in heterogeneous media via homogeneous fundamental solutions. To this end, an orthogonal moving least square (OMLS), borrowed...

BEM (boundary element method) was employed to protect the Angra dos Reis Waterway Terminal (TEBIG). The boundary element method (BEM) is an adequate technique to analyze CP systems. This method is based on integral equations and shows advantages for this kind of application. The work consists of numerically determining the range of effectiveness of...

A known feature of any mixed interpolation boundary integral equations (BIE)-based methods is that equilibrium is not generally guaranteed in the numerical solution. Here, a complete meshless technique, based on the boundary element-free method (BEFM) with complete equilibrium satisfaction for 2D elastostatic analysis is proposed. The BEFM adopted...

After years dominating high performance computing, expensive vector computers were gradually replaced by more affordable solutions and the use of vectorization techniques once applied to many scientific codes also faded. This paper addresses the vectorization of engineering codes using Streaming SIMD Extensions (SSE) also known as multimedia instru...

The Hilbert-Huang Transform (HHT) is extended to the time series analysis of wave orbital velocities resulting from the superposition of waves propagating in different directions. On a theoretical basis, it is shown that an apparently chaotic velocity signal may result from the interaction of three or more waves, each one with its own period and di...

The Numerical Green’s Function (NGF) technique, previously proposed by the present authors, is here extended to fracture mechanics problems involving Reissner’s plate theory. The technique numerically produces a plate bending fundamental Green’s function that automatically includes embedded cracks to be used in the classical boundary element method...

The application of the method of fundamental solutions (MFS), a mesh-free technique, to solve cracked Reissner's plates is discussed in this work. Here, the numerical Green's function (NGF) previously developed by the authors is used as the fundamental solution required by the method. Stress intensity factors or the related force intensity factors...

The present paper presents a self-equilibrated boundary element formulation for elastostatic analysis of Reissner’s plate bending problems. In this formulation, rigid body movements are introduced to the generalized displacement fundamental solution, resulting in modified boundary element matrices with inherent equilibrium satisfaction. The procedu...

Over decades, since the invention of the first computers, hardware and software have been created or modified to follow the increasing complexity of scientific and engineering problems. However, since there is always a limit to the performance of a workstation, server or even a local parallel machine, programs can bypass these limitations by using...

In this work, a complete meshless technique, based on the Boundary Element-Free Method (BEFM) for 2-D elastostatic analysis applied to Functionally Graded Materials (FGMs) is proposed. FGMs are non-homogenous materials in which some properties (e.g. density, Young modulus, Poisson rate, etc.) vary as a function of spatial coordinates. BEFM is a mes...

A meshless procedure, based on boundary integral equations, is proposed to analyze elastoplastic problems. To cope with non-linear problems, the usual boundary element method introduces domain discretization cells, often considered a ‘drawback’ of the method. Here, to get rid of the standard element and cell, i.e. boundary and domain discretization...

Nowadays processor architectures include Streaming SIMD Extensions (SSE) originally developed for multimedia applications, not so well explored for scientific computing. This fact has called the attention of the present authors and this paper introduces the application of SSE, also known as multimedia instructions, to boundary element codes. Since...

The present work discusses a solution procedure for heterogeneous media three-dimensional potential problems, involving nonlinear boundary conditions. The problem is represented mathematically by the Laplace equation and the adopted numerical technique is the boundary element method (BEM), here using velocity correcting fields to simulate the condu...

Over the last few years the Boundary Element Method (BEM) has been successfully applied to linear elastic fracture mechanics problems (LEFM), involving static and dynamic cases. An approach to solve LEFM problems is presented in this work. The Numerical Green’s Function is used at the fundamental solution together with the Operational Quadrature Me...

The shape optimization problem consists in looking for the geometry that minimizes an objective function, like mass or compliance, subject to mechanical constraints. The boundary element method (BEM) is used for the structural analysis. For linear elasticity problems, it needs only a mesh on the boundary of the structure. This characteristic makes...

Originally developed by the consortium Sony-Toshiba-IBM for the Playstation 3 game console, the Cell Broadband Engine proces- sor has been increasingly used in a much wider range of applications like HDTV sets and multimedia devices. Conforming the new Cell Broad- band Engine Architecture that extends the PowerPC architecture, this processor can de...

This work aims at introducing the concept of the numerical Green's function (NGF) idea for elastostatic fracture mechanics using the boundary element-free method (BEFM). Unlike the local boundary integral equation method (LBIE), the BEFM only requires boundary interpolation. This method derives from the coupling of the boundary integral equation me...

Boundary element formulations incorporating consistent transient potential theory, satisfying exact energy balance, and dynamic equilibrium satisfaction with respect to the co-ordinate axis directions and moments, including inertial forces, elastoplastic deformations and thermal loadings, are presented. The procedures are quite general and can be i...

The present paper discusses the author’s experience and contributions to the implementation and development of the boundary element method (BEM). The main motivation for this descriptive text is to pay homage to Professor Frank Rizzo’s well known career, dedicated to boundary integral techniques, whose recent retirement certainly deserves recog...

The numerical Green’s function (NGF) technique, previously proposed by the present authors, is here extended to fracture mechanics problems involving Reissner’s plate theory. The technique numerically produces a plate bending fundamental Green’s function that automatically includes embedded cracks to be used in the classical boundary element method...

This paper applies the numerical Green’s function (NGF) boundary element formulation (BEM) first in standard form to solve the Laplace equation and then, coupled to the operational quadrature method (OQM), to solve time domain problems (TD-BEM). Both involve the analysis of potential discontinuities in the respective scalar model simulation. The im...

In the past two decades, considerable improvements concerning integration algorithms and solvers involved in boundary-element formulations have been obtained. First, a great deal of efficient techniques for evaluating singular and quasi-singular boundary-element integrals have been, definitely, established, and second, iterative Krylov solvers have...

Efficient integration algorithms and solvers specially devised for boundary-element procedures have been established over the last two decades. A good deal of quadrature techniques for singular and quasi-singular boundary-element integrals have been developed and reliable Krylov solvers have proven to be advantageous when compared to direct ones, a...

This work aims at extending the concept of the Numerical Green's Function (NGF), well known from boundary element applications to fracture mechanics, to the Local Boundary Integral Equation (LBIE) context. As a "companion" solution, the NGF is used to remove the integrals over the crack boundary and is introduced only for source points whose suppor...

A Simplified numerical evaluation of cathodic protection (CP) systems on a steel catenary riser (SCR) connecting a floating offshore platform and a wet Christms tree, is discussed. The complete system analysis was made by numerical simulation, using the boundary element method. The potential distribution along the riser was obtained under two coati...

This paper presents an original time-domain boundary element formulation for the dynamic analysis of porous media. Integral equations for displacements, stresses and pore-pressures, based on non-transient fundamental solutions are considered. Elastoplastic models are also dealt with by the present methodology, extending the applicability of boundar...

This paper presents a boundary element (BE) formulation with complete dynamic equilibrium satisfaction with respect to the co-ordinate axis directions and moments, including inertial forces. The new procedure is quite general and very easy to implement into BE existing codes. All the required expressions for both static and dynamic formulations are...

High performance coatings provide excellent protection to pipelines in service conditions. Such coatings have been applied to replace aged coatings, which have lost efficiency due to transport, installation, operation or even due to aging processes. There is growing concern regarding cathodic protection systems when segments of high performance coa...

Simultaneous Analysis and Design technique (SAND) for structural optimization considers the state variables as unknowns of the optimization problem and includes the equilibrium equations as equality constraints. In this way, equilibrium is only obtained at the end of the optimization process. Therefore, it is not necessary to solve the equilibrium...

This paper presents a crack growth prediction analysis based on the numerical Green's function (NGF) procedure and on the minimum strain energy density criterion for crack extension, also known as S-criterion. In the NGF procedure, the hypersingular boundary integral equation is used to numerically obtain the Green's function which automatically in...

A computational model based on the numerical Green's function (NGF) and the dual reciprocity boundary element method (DR-BEM) is presented for the study of elastodynamic fracture mechanics problems. The numerical Green's function, corresponding to an embedded crack within the infinite medium, is introduced into a boundary element formulation, as th...

This paper discusses the application of the numerical Green's function boundary element approach coupled with the operational quadrature method for the solution of dynamic crack problems governed by the scalar wave equation. Numerical examples are presented, allowing for the verification of the accuracy of the proposed procedure.

The present paper aims at introducing the concept of Green's function type fundamental solutions (i.e., unit source fundamental solutions satisfying particular boundary conditions) into the context of meshless approaches, particularly dealing with the local boundary integral equation method (LBIE) derived from the classic boundary integral equation...

Most formulations involving the use of the so-called consistent elastoplastic tangent operator procedure, in boundary element analysis, have been presented taking in consideration only a J 2 -type yield criterion, like von Mises. The present paper aims at bringing a general consistency concept to tangent operators obtained without yield criterion p...

This paper presents the parallel implementation of a boundary element code for the solution of 2D elastostatic problems using linear elements. The original code is described in detail in a reference text in the area [Boundary elements techniques: theory and applications in engineering, 1984]. The Fortran code is reviewed and rewritten to run on sha...

The numerical construction of a Green's function for multiple interacting planar cracks in an anisotropic elastic space is considered. The numerical Green's function can be used to obtain a special boundary-integral method for an important class of two-dimensional elastostatic problems involving planar cracks in an anisotropic body.

The present paper introduces the main steps towards the parallelization of existing boundary element codes, using standard and portable libraries for writing shared memory parallel programs, OpenMP and LAPACK. Parallel programming techniques can have a great impact on application performance and OpenMP facilitates these improvements. Since, such pr...

This paper presents the parallel implementation of a computer program for the solution of three-dimensional elastostatic problems using the Boundary Element Method (BEM). The Fortran code is written for shared memory systems using standard and portable libraries: OpenMP and LAPACK. The implementation process provides guidelines to develop highly po...

This article discusses computer simulation and experimental test results of an impressed current internal cathodic protection system for seawater pipelines. A single anode located on the axis of the pipeline was studied, and the current required to keep the minimum potential ∼ -950 mV vs silver/silver chloride (Ag/AgCl) electrode was determined for...

This paper discusses the application of boundary elements, with time independent fundamental solutions, to solve Biot's plane strain consolidation equations for poro-elastic saturated media, assuming incompressible grains and fluid. The time marching scheme divides the analysis in small steps and applies finite differences to integrate the diffusio...

This paper discusses the application of boundary elements, with time independent fundamental solutions, to solve Biot's plane strain consolidation equations for poro-elastic saturated media, assuming incompressible grains and fluid. The time marching scheme divides the analysis in small steps and applies finite differences to integrate the diffusio...

The Serra da Mesa Hydroelectric Power Plant, located in the Tocantins river, 210 km north of Brasilia, Brazil, has been completed and power (1200 MW) has been generated since 1998. This project includes one of the largest underground structures in Brazil, totalling 550,000 m3 of underground excavations in rock for the hydraulic circuit which was ex...

 This work is concerned with the computation of space and time derivatives (scalar wave) and stress and velocity components (elastodynamics) in a time-domain BEM formulation. Two approaches are presented: the first employs standard closed form integral equations related to desired variables, the second is based on a procedure that employs numerical...

The work introduces the main steps towards the parallelization of existing boundary element method (BEM) codes using available standard and portable libraries for writing parallel programs, such as LAPACK and ScaLAPACK. Here, a well-known BEM Fortran implementation is reviewed and rewritten to run on shared and distributed memory systems. This effo...

This work presents our efforts towards single node optimization and parallelization of an existing Boundary Element Method (BEM) code using OpenMP. Basic techniques of High Performance Computing (HPC) are employed to enhance serial code performance and to identify code parts to be parallelized. Numerical experiments on a SGI Origin 2000 on large pr...