# Paulo M PimentaUniversity of São Paulo | USP · School of Engineering (POLI)

Paulo M Pimenta

Prof. Dr.-Ing.

## About

115

Publications

29,937

Reads

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1,325

Citations

Introduction

Paulo got his Civil Engineer degree at the Polytechnic School at the University of São Paulo (EPUSP) and his PhD in Aerospace Engineering at the University of Stuttgart. In 1989 he was appointed as full professor at EPUSP. He was visiting professor at the University of Stuttgart, Hanover, Lisbon and Stanford. In 2006 he got from DFG a Mercator Chair in Hanover. He is researcher class 1A (CNPq), IACM Fellow and recipient of the Georg Forster Research Award from Alexander von Humboldt Foundation.

Additional affiliations

December 1989 - present

**Polytechnic School at University of Sao Paulo**

Position

- Professor (Full)

July 1987 - November 1989

**Polytechnic School at University of Sao Paulo**

Position

- Professor (Associate)

August 1986 - December 1989

**ENGESA**

Position

- Consultant

Education

October 1978 - September 1982

April 1978 - September 1978

March 1977 - February 1978

**Polytechnic School at University of São Paulo**

Field of study

- Structural Engineering

## Publications

Publications (115)

This work addresses simultaneous use of geometrically exact shear-rigid rod and shell finite elements and describes both models within the same framework. Parameterization of the rotation field is performed by Rodrigues rotation vector, which makes the incremental updating of the rotational variables remarkably simple. For the rod element, cubic He...

This work presents a computational method for the solution of problems involving flowing fluid media laden with solid particles. The idea is based on previous works by the authors on (though then separately considered) fluid–structure interaction and particle dynamics. The fluid problem is treated through an Eulerian finite element approach, with t...

This work develops a simple finite element for the geometrically exact analysis of Bernoulli–Euler rods. Transversal shear deformation is not accounted for. Energetically conjugated cross-sectional stresses and strains are defined. A straight reference configuration is assumed for the rod. The cross-section undergoes a rigid body motion. A rotation...

This work presents a geometrically exact Bernoulli–Euler rod model. In contrast to Pimenta (1993b), Pimenta and Yojo (1993), Pimenta (1996), Pimenta and Campello (2001), where the hypothesis considered was Timoshenko’s, this approach is based on the Bernoulli–Euler theory for rods, so that transversal shear deformation is not accounted for. Energet...

This book presents new ideas in the framework of novel, finite element discretization schemes for solids and structure, focusing on the mechanical as well as the mathematical background. It also explores the implementation and automation aspects of these technologies. Furthermore, the authors highlight recent developments in mixed finite element fo...

The current paper implementates a simple fully non-linear Kirchhoff-lovel shell penalty based finite element. The 6 nodes and 21 DoF triangular element developed in this work has a quadratic displacement field associated to it and the C1 continuity required by Kirchhoff-Love Hyphotesis is approximated by an internal penalty. The biggest novelty in...

The paper presents a novel approach for rate‐independent single crystal plasticity based on the Infeasible Primal‐Dual Interior Point Method in a small strain framework. Therein, the principle of maximum dissipation together with the yield functions on the slip systems in the crystal are considered as the constrained optimization problem. The const...

Single crystal plasticity plays a major role in the analysis of material anisotropy and texture evolution, treats each crystalline grain individually. The polycrystalline material response is obtained upon considering a structure consisting of various individual grains, often also considering interface effects at the grain boundaries. On the indivi...

It is not new that Model Order Reduction (MOR) methods are employed in almost all fields of Engineering in order to reduce the processing time of complex computational simulations. At the same time, Interior Point Methods (IPM), a method to deal with inequality constraint problems ‐ which is little explored in engineering ‐ can be applied in many f...

This special issue contains selected papers first presented in a short format at the Congress CILAMCE 2018 (39th Ibero-Latin American Congress on Computational Methods in Engineering) held in Paris and in Compiègne, France, from 11 to 14 November 2018.

In this work, a geometrically exact, fully nonlinear Euler‐Bernoulli beam formulation is presented. Herewith a special case of Timoshenko rod models, discussed in various publications such as [2] or [4], is considered. Following the basic assumptions of transversal shear rigidity and plane cross sections, the formulation is based on displacements,...

his work considers the use of a type of "sliding cable" element that includes the effect of friction to represent the behavior of tendons in prestressed structures. The sliding cable element can potentially model the prestressing tendons in connection to a broader class of structural elements. In order to test its performance in prestressing applic...

This paper presents the initial activities of an ongoing research on the analysis of orthotropic membranes, considering geometrical nonlinearity. The subject is relevant for t he consistent description of the materials used in the production of the current structural membranes and for the proper consideration of wrinkling in such type of structures...

This work presents a mathematical model to establish the weak form and tangent operator contributions due to contact between spherical surfaces and general surfaces. Normal and friction components are included, such as dissipative actions. The main concern herein is the proper consideration of the kinematics of the spherical surface and its influen...

This work presents a simple finite element implementation of a geometrically exact and fully nonlinear Kirchhoff–Love shell model. Thus, the kinematics are based on a deformation gradient written in terms of the first- and second-order derivatives of the displacements. The resulting finite element formulation provides C1
-continuity using a penalty...

Slender structures are commonly represented using beam models. When addressing the contact between them, usually one has to adopt specific formulations, wherein the beam is represented by a 3D curve. Aiming at increasing the geometric details of such formulations, in this work we present a master-surface to master-surface contact formulation, which...

This work presents a derivation of equivalent loads, coming from the integration of hydrostatic pressure fields on the internal and external walls of a curved pipe, which is modeled as a Euler-Bernoulli beam. To achieve that, the divergence theorem is applied to an infinitesimal-length pipe element. The Frenet coordinate system is used, leading to...

Recent studies analyze the behavior of advanced shell structures, like foldable, multistable or morphing shell structures. Simulating a thin foldable curved structure is not a trivial task: the structure may go through many snapping transitions from a stable configuration to another. Then, one could claim arc-length methods or use a dynamic approac...

Model Order Reduction (MOR) methods are employed in many fields of Engineering in order to reduce the processing time of complex computational simulations. A usual approach to achieve this is the application of Galerkin projection to generate representative subspaces (reduced spaces). However, when strong nonlinearities in a dynamical system are pr...

Meshless methods provide a highly continuous approximation field, convenient for thin structures like shells. Nevertheless, the lack of Kronecker Delta property makes the formulation of essential boundary conditions not straightforward, as the trial and test fields cannot be tailored to boundary values. Similar problem arise when different approxim...

Nesta Tese é estudado o comportamento das estruturas de aço a altas temperaturas. São apresentadas curvas temperatura-tempo dos gases quentes que envolvem as chamas e deduzidas as expressões para a determinação da ação térmica e seu efeito, a temperatura, nas peças estruturais. É analisada a influência da ventilação, da carga de incêndio e da geome...

In this paper a surface to surface frictionless contact formulation is presented, which is appropriate to the analysis of beam to beam contact. Parameterized surfaces are assumed to represent the boundaries of the bodies that are candidate to contact. The material points of each surface are described using convective coordinates. No master-slave di...

Model Order Reduction (MOR) methods are extremely useful to reduce processing time, even nowadays, when parallel processing is possible in any personal computer. This work describes a method that combines POD (Proper Orthogonal Decomposition) and Ritz vectors to achieve an efficient Galerkin projection which changes during nonlinear solving (online...

The finite element implementation of a geometrically exact thin shell model is reported in the present paper. The shell kinematics is based on the Kirchhoff–Love assumption and is characterized by the deformation gradient, which yielded the generalized cross-section strain measures — stretches and curvatures, written in terms of first- and second-o...

Die Verlegung von Kabel auf dem Meeresgrund kann nur durch Balkenmodelle erfasst werden, die es erlauben endliche Verschiebungen und Rotationen abzubilden. Dies führt auf nichtlineare Formulierungen, die nur noch mittels diskretisierender Verfahren, wie der Methode der finiten Elemente gelöst werden können. Hinzu kommen Zwangsbedingungen infolge de...

Laying of offshore cables on ocean ground can be described by beam models which allow for finite displacements and rotations. These models lead to nonlinear formulations that can only be solved by using approaches like the finite element method. Additional to the nonlinearities stemming from the cable unilateral constraints occur due to contact of...

Catenary risers have an interaction zone with the seabed, usually referenced as flowline. Movements in this region can be induced by sea currents and large offsets in floating unit, leading to touchdown position changes and affecting internal loads along riser length. In this work the contact flowline-seabed is modeled including sliding and rolling...

This work addresses some issues in the embedded interface method for the conjoined interface between fluid and structure domains in two-dimensional Fluid-Structure Interaction (FSI) coupled problems. Our approach uses Lagrange multipliers to enforce the kinematic condition along the interface between the non-matching overlapping meshes of the struc...

Many engineering scenarios involve contact between beam structures or, eventually, self-contact. Specifically when dealing with a beam submitted to large torsion loads and considering large displacements and rotations, it is possible to occur self-contact. Beams with low bending stiffness loaded with large torsion can present a loop, followed by se...

In the present paper, a meshless generalized multiple fixed least squares implementation of the geometrically exact Kirchhoff–Love shell theory is described. The material time derivative of the deformation gradient and the first Piola–Kirchhoff stress tensor are considered as basic conjugate quantities to evaluate the internal power. The shell's in...

The present paper addresses the problem of establishing the boundary conditions of a geometrically nonlinear thin shell model, especially the kinematic ones. Our model is consistently derived from general 3D continuum mechanics statements. Generalized cross-sectional strains and stresses are based on the deformation gradient and the first Piola–Kir...

This work presents a new approach to model the contact between a circular cross section beam and a flat surface. In a finite element environment, when working with beam elements in contact with surfaces, it is common to consider node or line to surface approaches for describing contact. An offset can be included in normal gap function due to beam c...

The current work discusses an application of the TUBA finite elements, initially developed for thin plates problems, to geometrically exact thin shell analysis. The proposed geometrically exact shell model is derived from complete 3D continuum mechanics by means of certain kinematic and static assumptions. The theory is derived independently from t...

In offshore applications there are elements that can be modeled as long beams, such as umbilical cables, flexible and rigid pipes and hoses, immersed in the sea water, suspended from the floating unit to the seabed. The suspended part of these elements is named “riser” and is subjected to the ocean environment loads, such as waves and sea current....

Keywords: self-contact, beam, loop, instability When a beam-like structure initially straight is subjected to compression and torsion, it can turn into a loop shape. This is related to a classical instability problem, addressed by many authors (see [1]). The loop formation instability can be found in many applications, from DNA molecules to offshor...

Loop formation may occur in cables, ropes, and also risers — flexible pipes or umbilical cables — used for offshore exploitation. The phenomenon occurs when there is enough torsion moment in the line and also a low tension condition or, even in the cases of cable slack (almost zero tension) with some torsion moment. Many references discuss about th...

The CFD analysis of the National Stadium of Brasilia, which was built for World Cup 2014, is presented.

This work develops a kinematically linear shell model departing from a consistent nonlinear theory. The initial geometry is mapped from a flat reference configuration by a stress-free finite deformation, after which, the actual shell motion takes place. The model maintains the features of a complete stress-resultant theory with Reissner-Mindlin kin...

This work addresses the treatment of lower density regions of structures undergoing large deformations during the design process by the topology optimization method (TOM) based on the finite element method. During the design process the nonlinear elastic behavior of the structure is based on exact kinematics. The material model applied in the TOM i...

Most of the Brazilian bridges of federal road network are made of reinforced concrete and are more than 30 years old, with little information about the mechanical properties of their constitutive materials. Along the service life of these bridges much modification occurred on vehicles load and geometry and in design standard. Many of them show sign...

This paper addresses the development of a hybrid-mixed finite element formulation for the quasi-static geometrically exact
analysis of three-dimensional framed structures with linear elastic behavior. The formulation is based on a modified principle
of stationary total complementary energy, involving, as independent variables, the generalized vecto...

A unified formulation is presented in this work for the nonlinear dynamics analysis of rods and shells undergoing arbitrarily
large deformations and rigid body motions. Based on our previous works, we develop a special notation and describe both rod
and shell kinematics with the same set of expressions. Differences are observed only at the constitu...

This paper addresses the development of some alternative hybrid and mixed variational formulations for the geometrically-exact three-dimensional first-order-shear shell boundary value problem. In the framework of the complementary-energy-based formulations, a Legendre transformation is used to introduce the complementary energy density in the varia...

This work consists of a low level analysis, considering assembly instructions, registers, Floating Point Unit and RAM (Random-Access Memory) details, of programming codes used by direct methods of solving linear systems, such as Crout, Cholesky and others, written in high level language, as well as discussing mechanisms that can be used to optimize...

This paper addresses the development of several alternative novel hybrid/multi-field variational formulations of the geometrically exact three-dimensional elastostatic beam boundary-value problem. In the framework of the complementary energy-based formulations, a Legendre transformation is used to introduce the complementary energy density in the v...

This work proposes a study on the XFEM method used to treat the conjoined interface between fluid and structure domains in two dimensional coupled Fluid-Structure Interaction (FSI) problems. The idea is based on [1], in which the FSI problem is solved adopting two non-matching overlapping meshes for the structural and fluid fields in an alternative...

This work presents a fully nonlinear Kirchhoff-Love shell model. In contrast with shear flexible models, our approach is based on the Kirchhoff-Love theory for thin shells, so that transversal shear deformation is not accounted for.
We define energetically conjugated cross-sectional generalized stresses and strains. The fact that both the first Pi...

A plate theory as a mean to compute precise 3D-solutions including edge effects and related (O. Allix and C. Dupleix-Courdec) A fully nonlinear thin shell model of Kirchhoff-Love type (P.M. Pimenta, E.S. Almeida Neto and E.M.B. Campello) A beam finite element for nonlinear analysis of shape memory alloy devices (E. Artioli, F. Auricchio and R.L. Ta...

An alternative approach for the analysis of arbitrarily curved shells is developed in this paper based on the idea of initial deformations. By ‘alternative’ we mean that neither differential geometry nor the concept of degeneration is invoked here to describe the shell surface. We begin with a flat reference configuration for the shell mid-surface,...

In this work, the non-penetration condition and the interface models for contact, taking into account the surface microstructure, are investigated in detail. It is done using a homogenization procedures presented by Bandeira, Wriggers and Pimenta (2001a), to obtain by numerical simulation the interface behavior for the normal and tangential contact...

A fully nonlinear geometrically-exact multi-parameter rod model is presented in this work for the analysis of beam structures undergoing arbitrarily large 3-D deformations. Our approach accounts for in-plane distortions of the cross-sections as well as for out-of-plane cross-sectional warping by means of cross-sectional degrees-of-freedom within th...

This paper discusses the natural force density method (NFDM), an extension of the force density method for the shape finding of continuous membrane structures, which preserves the linearity of the original method. Furthermore, if applied iteratively, the NFDM
may converge to a minimal surface through a succession of viable configurations. This is a...

A fully conserving algorithm is developed in this paper for the integration of the equations of motion in nonlinear rod dynamics.
The starting point is a re-parameterization of the rotation field in terms of the so-called Rodrigues rotation vector, which
results in an extremely simple update of the rotational variables. The weak form is constructed...

This work presents, with the aid of the natural approach, an extension of the force density method for the initial shape finding of cable and membrane structures, which leads to the solution of a system of linear equations. This method, here called the natural force density method, preserves the linearity which characterizes the original force dens...

In the present contribution a geometrically exact thin shells formulation is presented. An analysis pro-cedure based on a meshfree approximation is outlined. As no restrictions are imposed on the rotational fields, the present formulation falls on the category of the geometrically exact structural theories. The derivation is made by imposing the ki...

In this work a homogenization method presented by Bandeira et al [2,3,4] is enhanced to obtain by numerical simulation interface laws for the normal contact pressure based on statistical surface models. For this purpose elastoplastic behaviour of the asperities is introduced. Statistical evaluations of numerical simulations lead to a constitutive l...

The applicability of a meshfree approximation method, namely the EFG method, on fully geometrically exact analysis of plates is investigated. Based on a unified nonlinear theory of plates, which allows for arbitrarily large rotations and displacements, a Galerkin approximation via MLS functions is settled. A hybrid method of analysis is proposed, w...

Following the approach developed for rods in Part 1 of this paper (Pimenta etal. in Comput. Mech. 42:715–732, 2008), this work presents a fully conserving algorithm for the integration of the equations of motion in nonlinear shell dynamics.
We begin with a re-parameterization of the rotation field in terms of the so-called Rodrigues rotation vector...