Método dos elementos finitos e design construtal aplicados à flambagem elasto-plástica biaxial de placas retangulares com perfuração elíptica

Abstract

Plate structures are mechanical elements with great application in engineering, because they are used in the most diverse branches of the industry, such as in the naval, aerospace, oil and gas sector, automobile industry, among others. Because they are elements that are much smaller in thickness than their other dimensions, they are called slender elemen ts, so when theyoccur with axial loads, they are subject to the phenomenon of unwanted structural instability called buckling. However, as is known, the plate structures are differentiated when subjected to buckling, as they do not collapse by elastic buckling. When entering into elastic buckling mode, the reorganization of stresses occurs in to this element, so that a plate still undergoes an increase in load until collapse, this phenomenon is called elasto-plastic buckling. Even for the most diverse reasons, these plates may contain perforations, such as passage of pipes, access for maintenance, weight reducing, among others. In this situation, an analysis of the influence of these perforations is necessary. Based on this, this work examines the influence of elliptical perforations in thin steel plates, subjected to biaxial elasto-plastic buckling. The adopted plate has a ratio b/a = 0,5, between its width b and its length a. Regarding elliptical perforations, plates with the following volumetric fractions φ = 0.10; 0.15; 0.20; will be analyzed, where φ is the relationship between the volume of the plate without perforation and the volume of the hole. To determine the ultimate elasto-plastic buckling load, the commercial software ANSYS® will be used, with the element SHELL281, associated with the Constructal Design Method and the Exhaustive Search Technique, in search of geometric optimization of the plate. The computational model used was verified and validated for its accuracy and satisfactory results were presented for the problem problems. The results of this work which improved the understanding of the elasto-plastic behavior of the plates under biaxial compression. It was noticed that more elongated perforations geometries in the Y axis, provided the best results and that, in the analyzed plate configurations, the loading capacity decreased with the increase of the degree of freedom b0/a0. It was also possible to verify that the increase in the size of the perforation causes a reduction in the capacity of the biaxial load plate.