Perforated steel thin plates are commonly used in structural engineering. Due to their geometric characteristics, these panels can suffer the undesired buckling phenomenon. In this context, the present work associates the computational modeling and the constructal design method to evaluate the influence of the geometric configuration in the plate buckling behavior, using the exhaustive search method to determine which geometries conduct to superior mechanical behavior. To do so, numerical models are employed to solve elastic and elasto-plastic buckling of plates having a centered perforation. Different hole types (longitudinal oblong, transversal oblong, elliptical, rectangular, diamond, longitudinal hexagonal, or transversal hexagonal) with different shapes (variation of characteristics dimensions of each hole type) are analyzed. Limit curves to avoid buckling were obtained, as well as the definition of the geometries that can improve up to 107% the plate performance.

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Thin steel plates-with or without cutouts-are structural components largely used in several engineering applications as buildings, bridges, ships, airplanes and automobiles. However, if an axial compressive load is imposed to these panels an undesired instability phenomenon can occur: buckling. At a certain load magnitude the limit stress is reached and the plate suffers lateral displacements (out of plane) indicating the buckling occurrence. In plates an elastic buckling or an elastoplastic buckling can occur, depending on dimensional, constructive or operational aspects. Therefore, in the present work, the Constructal Design method was adopted to investigate the influence of the type and shape of the cutout in the plate buckling. To do so, by means the Finite Element Method (FEM), computational models were developed to simulate the elastic (linear) and elasto-plastic (nonlinear) plate buckling. Square and rectangular thin steel plates, simply supported in its four edges, with a centered cutout, were analyzed, being the objective function to maximize the buckling limit stress, avoiding the plate buckling occurrence. The square and rectangular plates have a ratio H/L (ratio between height and length of the plate) of 0.5 and 1.0, respectively. A value of 0.2 for the cutout volume fraction (ratio between the cutout volume and the total plate volume) was adopted for different types of cutout: diamond, longitudinal hexagonal, transversal hexagonal, elliptical, and rectangular. The cutout shape variations were produced by the H0/L0 degree of freedom (which relates the characteristic dimensions of the cutout). The results showed that the cutout shape variation has a fundamental influence in the plate buckling behavior, determining if the buckling is elastic or elasto-plastic, allowing the definition of a buckling stress limit curve for each studied cutout type. In addition, it was observed that the Constructal Design method conduct to the definition of optimal geometries, reaching buckling stress limit improvements around 100%.

Slenderness is a remarkable geometrical characteristic of thin steel plates. When a slender plate is subjected to an axial compression loading, a mechanical behavior called buckling can occur, causing an out-of-plane displacement. This instability phenomenon can be divided into elastic buckling (linear) and elasto-plastic buckling (nonlinear), depending on dimensional, constructive, or operational aspects. Moreover, in several practical situations, it is necessary to provide holes on thin steel plates, causing stress redistribution and changes in its buckling behavior. The present work purposes a buckling study in square and rectangular plates, simply supported, with two different centered perforations types: longitudinal hexagonal and transverse hexagonal. Numerical simulation, using the ANSYS ® software, was employed to determine the critical buckling load and the ultimate buckling load of the plates. The constructal design method was applied, allowing evaluating the variation effect of the degree of freedom H 0 /L 0 (being H 0 the width and L 0 the length of the perforation) on the plate's mechanical buckling behavior. The hole volume fraction (ϕ) was another considered parameter, corresponding to cutouts of 10%, 15%, 20%, and 25% of the total plate volume. The results showed the direct influence of the H 0 /L 0 ratio on the buckling type, allowing the definition of a buckling stress limit curve for each cutout type and hole volume fraction. Besides, the constructal design method, associated with the exhaustive search technique, enabled to define the optimized geometric configuration for each hole type that conducted the plate to a maximized mechanical performance.

O afogamento é causado por muitos fatores, um problema de saúde pública universal que não recebeu a atenção necessária e impacta desproporcionalmente as crianças. Diversos fatores podem causar afogamento, por isso, existe a necessidade de se preveni-lo com o uso de conteúdos, não apenas procedimental, mas também atitudinal e conceitual. O objetivo deste estudo foi identificar o nível de conhecimento preventivo de afogamento em crianças e adolescentes em idade escolar. A metodologia foi de estudo transversal com estudantes com idade entre 9 e 13 anos do Ensino Fundamental da rede pública Estadual do Rio de Janeiro, RJ, Brasil. O total de alunos foram 281, sendo 57 do 5° ano, 112 do 6º ano e 112 do 7º ano. Os dados foram coletados por meio de questionário autorrespondido com supervisão de quatro avaliadores previamente treinados e a classificação da categoria de conhecimento preventivo foi a proposta por Vasconcellos, 2022a. Os resultados deste estudo mostraram que 90% conseguiram fazer a correlação certa a respeito da bandeira amarela, 91% em relação a verde e 93% em relação vermelha. Em relação a saber o significado das figuras que constam nas placas  de prevenção, o resultado mostrou que quase a totalidade dos alunos conhecem os significados das placas, por exemplo, 99,1% acertaram o significado das placas nº 2 e 3 que se referem ao telefone de emergência e proibido empurrar respectivamente. Já em relação aos comportamentos ligados às aulas de natação, verificou-se que mais de 90% dos alunos responderam que devem brincar sem empurrar na borda ou dentro d’água os outros alunos, no entanto, em relação ao buraco que aspira a água da piscina, notou-se que os mais novos do 5º ano são os que menos conhecem (77,2%) sobre os riscos de colocar a mão no sistema de drenagem. Pode-se concluir que os alunos do grupo investigado têm o nível de conhecimento preventivo bom sobre afogamento. No entanto, um excelente desempenho no teste de conhecimento preventivo não representa que o aluno está a salvo do afogamento, pois podem lhe faltar aquacidade e atitudes que o salvarão ou que impedirão de se afogar. Assim, é necessário que o conhecimento preventivo seja trabalhado nas aulas de natação de forma associada as habilidades aquáticas e atitudes corretas diante de uma situação de risco.