André Jacomel Torii

Reliability Analysis of Water Distribution Networks Using the Adaptive Response Surface Approach

This paper presents the application of the adaptive response surface approach to the reliability analysis of water distribution networks. In this case, the response of the system is approximated by an analytical solution (response surface) and then the reliability problem is solved using first-order reliability methods. This approach is then extended to the analysis of networks that may have to work under several different configurations. This can be a consequence of repairing operations or some other unexpected event, for example. Finally, two numerical examples are presented to discuss the main aspects of the proposed approach.

A local-restart coupled strategy for simultaneous sizing and geometry truss optimization

This paper presents an approach for the global optimization of truss sizing and geometry that is based on a probabilistic restart procedure coupled with a local search algorithm. The resulting algorithm is able to guarantee local optimality and provides a set of local optima which contain, with an increasing probability as the number of restarts increases, the global solution. The optimization problem searches for a truss structure of minimum volume, subject to stress constraints. The design variables are the bars cross-section areas and some nodal coordinates. Several loading conditions are also considered. Finally, four numerical examples are presented and the main aspects of the approach are discussed.

GFEM for modal analysis of 2D wave equation

Purpose – The purpose of this paper is to present an application of the Generalized Finite Element Method (GFEM) for modal analysis of 2D wave equation. Design/methodology/approach – The GFEM can be viewed as an extension of the standard Finite Element Method (FEM) that allows non-polynomial enrichment of the approximation space. In this paper the authors enrich the approximation space with sine e cosine functions, since these functions frequently appear in the analytical solution of the problem under study. The results are compared with the ones obtained with the polynomial FEM using higher order elements. Findings – The results indicate that the proposed approach is able to obtain more accurate results for higher vibration modes than standard polynomial FEM. Originality/value – The examples studied in this paper indicate a strong potential of the GFEM for the approximation of higher vibration modes of structures, analysis of structures subject to high frequency excitations and other problems that concer...

A BACKTRACKING SEARCH ALGORITHM FOR THE SIMULTANEOUS SIZE, SHAPE AND TOPOLOGY OPTIMIZATION OF TRUSSES

THIS PAPER PRESENTS A BACKTRACKING SEARCH OPTIMIZATION ALGORITHM (BSA) TO SIMULTANEOUSLY OPTIMIZE THE SIZE, SHAPE AND TOPOLOGY OF TRUSS STRUCTURES. IT FOCUSES ON THE OPTIMIZATION OF THESE THREE AS-PECTS SINCE IT IS WELL KNOWN THAT THE MOST EFFECTIVE SCHEME OF TRUSS OPTIMIZATION IS ACHIEVED WHEN THEY ARE SIMULTANEOUSLY CONSIDERED. THE MINIMIZATION OF STRUCTURAL WEIGHT IS THE OBJECTIVE FUNCTION, IMPOSING DISPLACEMENT, STRESS, LOCAL BUCKLING AND/OR KINEMATIC STABILITY CONSTRAINTS. THE EFFECTIVENESS OF THE BSA AT SOLVING THIS TYPE OF OPTIMIZATION PROBLEM IS DEMONSTRATED BY SOLVING A SERIES OF BENCHMARK PROBLEMS COMPARING NOT ONLY THE BEST DESIGNS FOUND, BUT ALSO THE STATISTICS OF 100 INDEPENDENT RUNS OF THE ALGORITHM. THE NUMERICAL ANALYSIS SHOWED THAT THE BSA PROVIDED THE BEST DESIGN EVER FOUND FOR MOST OF THE ANALYZED PROBLEMS. MOREOVER, IN SEVERAL CASES, IT WAS ALSO ABLE TO IMPROVE THE STATISTICS OF THE INDE-PENDENT RUNS SUCH AS THE MEAN AND COEFFICIENT OF VARIATION VALUES.

Otimização Topológica Estrutural Baseada em Confiabilidade com Restrição em Tensão Utilizando o Conceito de Derivada Topológica

Em otimizacao estrutural os resultados obtidos devem ser robustos em relacao a incertezas, sejam elas oriundas da natureza probabilistica das variaveis de trabalho ou aquelas inerentes a resistencia dos materiais, por exemplo. Este fato tem levado ao desenvolvimento de diferentes metodologias de otimizacao estrutural baseada em incertezas. Sendo assim, o objetivo deste trabalho e propor uma nova formulacao para o problema de otimizacao topologica estrutural baseada em confiabilidade com restricao em tensao. Buscam-se entao estruturas de volume minimo que atendam simultaneamente aos criterios de resistencia e confiabilidade estruturais.