Campinas, Brazil
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Forti T.L.D.,Simworx Engineering | Farias A.M.,University of Campinas | Devloo P.R.B.,University of Campinas | Gomes S.M.,University of Campinas
Finite Elements in Analysis and Design | Year: 2016

In this work, different finite element formulations for elliptic problems are implemented and compared, in terms of accuracy versus number of required degrees of freedom. The implemented formulations are: (a) the classical H1 weak formulation (continuous); (b) the non-symmetric discontinuous Galerkin formulation by Baumann, Oden and Babuska; (c) a mixed discontinuous Galerkin formulation, known as Local Discontinuous Galerkin (LDG); (d) a mixed H(div)-conforming formulation; (e) a primal hybrid formulation. In order to compare the methods, two 2-dimensional test problems are approximated, one having a smooth solution and the second one presenting a square root singularity in a boundary node. The different formulations are compared in terms of the L2 norm of the approximation errors in the solution and in its gradient (the flux). The tests are performed with h refinement with constant order of approximation p, as well as for a given hp refinement procedure. For the problem with a smooth solution, the results confirm convergence orders predicted by theoretical a priori error estimates. As expected, the application of hp refinement to the singular problem improves considerably the performance of all methods. Furthermore, due to the type of the singularity (square root), the efficiency of continuous and discontinuous Galerkin formulations is further improved by using enriched spaces with quarter-point elements. Regarding continuous, hybrid and mixed formulations, the effect of using static condensation of element equations is also analysed, in order to illustrate the reduction in the global system of equations in each case. A third comparison is given in terms of the conservation of the flux over a curve around a singularity. © 2016 Elsevier B.V. All rights reserved.

Forti N.C.S.,Pontifical Catholic University of Campinas | Requena J.A.V.,University of Campinas | Forti T.L.D.,Simworx Engineering
Journal of Constructional Steel Research | Year: 2015

This paper presents a parametric study of symmetrically loaded multiplanar KK connections in circular hollow steel sections. The connections were designed with gaps between the diagonal braces. Analyses were performed using the commercial finite element program Ansys. A total of 54 KK connections and their corresponding uniplanar K connections were analyzed and compared in terms of the connection resistance. A new objective criterion to assess the two failure modes most often occurring in KK connections is proposed. Failure mode 1 is observed when two neighboring diagonal braces loaded in the same sense act as one brace penetrating the chord together. In failure mode 2, excessive deformation is observed in the chord region between two neighboring braces, folding the chord wall. However, in some cases, the failure mode is not easily identified, or both failure types are present. The proposed criterion is based on the diametric deformation of the chord and objectively assesses the failure mode. By comparing the connection resistance of KK and K connections as determined using numerical analyses, analytical expressions to predict the connection resistance of KK connections were developed. The expressions accurately predict the connection resistance based on geometric parameters and the resistance of the corresponding uniplanar K connection. © 2015 Elsevier Ltd. All rights reserved.

Forti T.L.D.,Simworx Engineering | Longhin G.C.,Simworx Engineering | da Silva Forti N.C.,University of Campinas | Requena J.A.V.,University of Campinas
Revista Escola de Minas | Year: 2014

This article describes the development of an application for structural analysis of tubular trussed girders. Such structural components are widely used on roofs for which long span components are a necessity, e. g., supermarkets, distribution centers, etc. The application supplies hints to the project engineers as to the most economic solutions for a combination of span, loads, and other characteristics. Software development techniques are also explored. Such techniques can be divided into two large groups. In the first one, which is most widely known and used, software development complies with very rigid planning, where processes are more important than skills. This methodology is known as the Rigorous Development System (RDS). The second group, called Agile Development System (ADS), is conceived as an option for those not aligned with the RDS rules. This text describes the experience of an ADS based software development for truss design. In Section 2, the basis of ADS is presented. Section 3 describes the truss design application and civil engineering related concepts. Section 4 brings an example illustrating the application. Conclusions are in Section 5. © 2014, Escola de Minas. All right reserved.

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