João Paulo Silva Lima

SIMULAÇÃO NUMÉRICA E MÉTODO DESIGN CONSTRUTAL APLICADOS AO ESTUDO DE FLAMBAGEM EM PLACAS DE AÇO COM PERFURAÇÃO HEXAGONAL

RESUMO Placas finas de aco sao componentes muito utilizados em estruturas navais e oceânicas. Por se tratarem de elementos esbeltos, essas placas sao propensas a sofrerem o fenomeno da flambagem, quando submetidas a um carregamento de compressao axial. A realizacao de perfuracoes nestes componentes pode ser necessaria, o que gera uma redistribuicao de tensoes, causando mudancas no desempenho mecânico. Este trabalho propoe um estudo do fenomeno de flambagem em placas quadradas ou retangulares, simplesmente apoiadas e com perfuracao hexagonal longitudinal. A simulacao numerica foi utilizada para determinar a carga critica de flambagem e a carga de colapso da placa. O metodo Design Construtal foi aplicado, permitindo avaliar a influencia do grau de liberdade H 0 / L 0 (sendo H 0 a altura e L 0 o comprimento da perfuracao hexagonal), no comportamento mecânico das placas. A fracao de volume da perfuracao na placa ( ϕ ) tambem foi considerada, correspondendo a 10%, 15%, 20% e 25% do volume total da placa. Os resultados mostraram a direta influencia da relacao H 0 /L 0 na ocorrencia da flambagem, para cada valor de fracao de volume estudada. Alem disso, o metodo Design Construtal, associado ao mecanismo de busca exaustiva, permitiu definir a geometrias otima para a perfuracao hexagonal nas placas. Palavras-chave: Placas de aco; Flambagem; Simulacao numerica; Design Construtal.

APLICAÇÃO DO MÉTODO DESIGN CONSTRUTAL NA ANÁLISE DE TUBOS PERFURADOS SOB FLAMBAGEM

RESUMO Os tubos metalicos sao componentes empregados nas obras de engenharia devido a sua vida util e facilidade de utilizacao. Quando esbeltos, os tubos podem sofrer o fenomeno de flambagem. Submetidos a presenca de perfuracoes, apenas analises experimentais ou numericas podem ser empregadas para obter o valor da carga critica de flambagem elastica. Assim, desenvolveu-se um modelo computacional no software ANSYS, baseando no Metodo dos Elementos Finitos (MEF) para a analise da influencia de perfuracoes no seu comportamento mecânico. Alem disso, empregou-se o Metodo Design Construtal para determinar geometrias que possam avaliar a presenca de perfuracoes no tubo, alem da influencia da variacao geometrica dos furos, retangulares, circulares e hexagonais, na carga critica de flambagem. Sendo assim, o trabalho objetiva determinar a geometria otima para as perfuracoes nos tubos, considerando o parâmetro ϕ dado como o volume removido e o volume total da coluna igual a 0,05; 0,10; 0,15 e 0,20, com um grau de liberdade variando a forma geometrica do furo. Por fim, o estudo mostrou que a relacao de volume retirado e a carga critica de flambagem sao inversamente proporcionais, obtendo uma geometria otima para todos os valores de ϕ, prevalecendo a geometria retangular em todas as variacoes volumetricas. Palavras-chave: Flambagem; Tubos estruturais; Metodo dos Elementos Finitos; Design Construtal.

A PROBABILISTIC ANALISYS OF THE FORCES IN THE PILES OF A CONTAINER TERMINAL WHARF UNDER SHIP BERTHING ACTIONS

ABSTRACT In this work a probabilistic structural analysis of a container terminal wharf is presented. Through the application of the Monte Carlo Simulations in a finite element structural model, the statistics of the axial forces at the pile heads were evaluated. Considering only ship berthing conditions, but varying equipment type, number and positions, ten external load combinations were analyzed and compared. Both finite element model and probabilistic analysis were performed in ANSYS software, v.16, on its APDL Mechanical and Probabilistic Design System packages respectively. The random input parameters considered were the concrete structure, pavement and rear landfill self-weight, live loads and ship sizes, for which statistical parameters were attributed based on bibliography or data collection. PIANC’s berthing energy method for fender systems design was applied for the evaluation of ship berthing forces acting on the structure. Considering the axial forces as the main parameters in the design of partially embedded piles, the random output parameters obtained were the minimum and maximum axial forces on each simulation. That approach, applied due to the possibility of ANSYS to be programmed through its Parametric Design Language (APDL), proved to be a powerful tool for probabilistic analysis of complex structural systems. The results present a comparison between the statistical parameters and probability density curves for the ten cases analyzed, by which the worst combinations from a probabilistic point of view could be defined. Keywords: Container terminal berth; Probabilistic Analisys; Monte Carlo Method; Finite Element Method; ANSYS.

NUMERICAL SIMULATION ANDCONSTRUCTAL DESIGN APPLIED TO THE STUDY OF ELASTIC BUCKLING IN THIN STEEL PLATES WITH OBLONG PERFORATIONS

ABSTRACT Buckling is an instability phenomenon that can happen when a slender plate is subjected to axial compression loads. In addition, perforated plates are often necessary in the engineering field. Throughout this article, the Constructal Design Method, which is based on the Constructal Theory, has been used to evaluate the influence of the hole on thin steel plates under elastic buckling. For that, the different types of holes analyzed were both transversal and longitudinal oblong. They were all placed in the center of the plate. The geometry of the hole varied according to the degree of freedom H 0 /L 0 , which relates the dimensions of each type of different hole. The size of the perforation are varied by means the hole volume fraction (f) parameter, that represents the relation between the volume of the hole and the total volume of the plate (without hole). The main goal is to achieve the greatest critical load for the perforated plates. To do so, the ANSYS software, based on the Finite Element Method (FEM), has been used to numerically analyze the elastic buckling in each case. It has been observed the importance of the geometry when seeking superior performances: through a simple fluctuation of the geometry of the hole, once the volume fraction was kept constant, it was possible to achieve a significant increase on the critical loads. Key words: Buckling; Computational Modeling; Critical Load; Constructal Design.