Simulação numérica e design construtal aplicados à flambagem elástica biaxial de placas retangulares com perfurações retangulares

Abstract

Thin plates are structural elements widely used in several areas of engineering, being of great importance in aeronautical and naval engineering, emerging as the main element in the construction of vessel hulls and offshore structures. However, because they are a slender structural element, they are subject to the occurrence of elastic buckling, which is a phenomenon of unwanted structural instability in engineering projects. In addition, the insertion of perforations in plates is a technique commonly used, whether to enable access to facilities, either to reduce weight or even for aesthetic reasons. However, the inclusion of perforations in plates causes a redistribution of internal stresses of the element, affecting its mechanical strength and its buckling characteristics. Therefore, in this work, the influence of the insertion of rectangular and centralized perforations on the mechanical behavior of thin steel plates, simply supported and submitted to biaxial compression, will be analyzed. The analysis was performed for plates with rectangular geometry (b/a = 0,5), where b and a represent the width and length of the plate, respectively. Regarding drilling, rectangular holes were inserted into the plate, which varied in geometry based on their volumetric fraction. The following volumetric fractions were considered: : ;, being the fraction that relates the volume of the perforation and the volume of the plate. To determine the critical buckling load, the SHELL281 element was used through the commercial software ANSYS®, which uses the Finite Element Method (MEF). The Constructive Design Method (DC) associated with the Exhaustive Search technique was used to determine the search space and the optimum geometries for all the studied volumetric fractions where it was possible to obtain optimized geometries for the perforations, seeking the best mechanical performance of the structure. It is worth to mention that the perforation insertion, or the volume fraction increasing, resulted in a reduction of critical buckling load. Also, the geometric variation of the perforation can increase in 78,8% the critical buckling load of the plate.