Research on Engineering Structures and Materials

151-160

Authors: Liang Ji, Xinzhi Liu, Houlei Zhang

Furfural residue is a detrimental waste generated in furfural production processes. Combustion is an efficient way to dispose furfural residue and drying is a necessary unit operation prior to combustion. In this paper, the properties of furfural residue, including particle size distribution, proximate analysis and pyrolysis process curves were presented. The flow and drying characteristics of furfural residue in a lab-scale single-shaft paddle heat exchanger were documented. The measurements show that the furfural residue contains high moisture (54.26%) and its as received basis lower heating value is 7301 kJ/kg. The high moisture content in furfural residue makes ignition and efficient combustion very difficult. It is feasible to use single-shaft paddle heat exchanger to dry furfural residue to moisture content of 15.94% which is advantageous for further combustion due to low moisture content. No agglutination and blockage were found. This preliminary experimental research provides reference for furfural residue drying unit design.

169-187

Authors: Daniel Helbig, Marcelo Langhinrichs Cunha, Caio Cesar Cardoso da Silva, Elizaldo Domingues dos Santos, Ignácio Iturrioz, Mauro de Vasconcellos Real, Liércio André Isoldi, Luiz Alberto Oliveira Rocha

There are several areas of engineering that use thin plates as structural elements, among them, we can highlight their application in the construction of offshore structures, bridges, ship hulls, and aircraft fuselage. In some design situations, the plates may be subjected to compression stresses and, consequently, they may be under the effect of elastic and/or elasto-plastic buckling. The analysis of the buckling phenomenon presents significant differences between one-dimensional elements, such as beams and columns, and two-dimensional elements, such as plates. The buckling phenomenon is directly related to dimensional, constructive and/or operational aspects. In this sense, the presence of perforations in plates causes a redistribution of their stresses, affecting not only their resistance but also their buckling characteristics. In order to solve the problem of elasto-plastic buckling in thin steel plates with perforations, we used computational models developed in Ansys(R) software, which is based on the Finite Element Method (FEM). For the analysis, it was considered perforated plates with constant thickness h for the relationships H/L = 1.0 and H/L = 0.5, where H is the plate width and L is the plate length. For the volume fraction Ф, i.e., the ratio between the volume of the perforation and the volume of the plate, the following values were considered: 0.08; 0.10; 0.15; 0.20 and 0.25. In addition, the plates were considered to have centralized perforations with the following geometric forms: longitudinal oblong, transverse oblong, elliptic, rectangular, diamond, longitudinal hexagonal, and transverse hexagonal. The shape variation of each perforation type occurs through the ratio H0/L0, being H0 and L0 the characteristics dimensions of perforation. The Constructal Design method was employed to define the range of possible geometries for the perforated plates, allowing an adequately comparison about the von Mises stress distribution among the studied cases. The results show that the geometric shape variation, for all analyzed perforation types, leads to an optimum geometry.

219-230

Authors: Anunciação Jr.N. C, Anflor C.T.M, Goulart J.N.V

This paper focused on developing a methodology based on coupling the Genetic Algorithm (GA) and the Boundary Element Method (BEM) for predicting the mechanical properties of a soil if a previous displacement x frequency curve is known. The NSGA-II (Elitist Non-Dominated Sorting Genetic Algorithm) was chosen for optimizing a dynamic poroelastic problem. The revisited problem introduced by Cheng is the benchmark used to verify the numerical routine and to apply the proposed optimization procedure. The present methodology was shown to be able to predict the mechanical properties of the underground soil if a displacement x frequency curve is previously known.