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Abstract(s)
O fabrico aditivo, em inglês Aditive Manufacturing (AM), surgiu nos últimos anos como uma
tecnologia chave na fabricação de componentes estruturais de aeronaves. Este permite explorar
topologias estruturais mais complexas e mais eficientes, bem como reduzir o desperdício
de material. O presente trabalho tem como objetivo investigar as características de rigidez e
resistência de várias nervuras com diferentes topologias estruturais prescritas ou optimizadas,
construídas através de AM. Esta dissertação descreve o design, os procedimentos numéricos e
experimentais e a otimização de nervuras fabricadas com ácido polilático (PLA) usando a tecnologia
FDM (Fused Deposition Modeling). As topologias estudadas foram projetadas com base
em algumas configurações tradicionais onde as cargas de flexão e as cargas de corte devem
ser transmitidas ao longo da nervura para a longarina da asa. Estes layouts da nervura incluem
treliças bidimensionais, favo de mel e topologias de lightening-hole, entre outros. As análises
numéricas foram realizadas utilizando o módulo de análise estrutural estática do software Ansys
Workbench para dois carregamento distintos. O primeiro carregamento é uma simplificação em
que a força distribuída ao longo da corda, resultante da força de sustentação, é substituída por
duas cargas concentradas equivalentes junto ao bordo de ataque e ao bordo de fuga. O objetivo
aqui é analisar numericamente uma situação cuja validação experimental é viável. O segundo
carregamento representa uma situação mais realista onde as cargas distribuídas são aplicadas
nas superfícies superior e inferior do perfil aerodinâmico para produzir uma resposta estrutural
melhorada durante o vôo. Uma função de mérito que contém a tensão máxima equivalente de
von-Mises, o deslocamento máximo e a energia de deformação é calculada para avaliar quantitativamente
quais as geometrias da nervura que apresentam o melhor desempenho estrutural.
Além disso, um problema de otimização estrutural é realizado usando Topology Optimization
(TO). Este método matemático, que otimiza o layout do material dentro de um determinado
espaço de design para um determinado conjunto de cargas, condições de fronteira e restrições
com o objetivo de maximizar o desempenho do sistema, é aplicado para minimizar a massa da
nervura da asa sujeita a restrições de resistência e rigidez. Os resultados mostram um bom
acordo geral entre os deslocamentos e tensões calculados numericamente e os resultados obtidos
a partir de testes experimentais. A otimização topológica é útil para produzir nervuras
estruturalmente melhoradas com layouts complexos não triviais que são facilmente obtidos por
técnicas de AM. Algumas fontes de erros experimentais e numéricos são identificadas e alguns
melhoramentos são propostos.
Additive manufacturing (AM) has emerged over the last years has a key technology in aircraft structural components’ manufacturing. It enables more complex and more efficient structural topologies to be explored as well as to reduce material waste. The present work aims at investigating stiffness and strength characteristics of several wing ribs having different prescribed or optimized structural topologies that were built by AM. This paper describes the design, the numerical and experimental procedures and the optimization of wing ribs manufactured with polylactic acid (PLA) using the Fused Deposition Modeling (FDM) technology. The studied wing rib concepts were designed based on some traditional configurations where bending loads and shear loads must be transmitted along the rib to the wing spar. These wing rib layouts include two-dimensional truss, honeycomb and lightening-hole topologies, among others. Numerical analyses were performed using Ansys Workbench’s static structural analysis for two distinct loading cases. The first loading is a simplification in which the chordwise distributed force, resulting from wing lift, is replaced by two equivalent concentrated loads at the leading and trailing edges. The objective here is to numerically analyze a situation whose experimental validation is feasible. The second loading represents a more realistic situation where distributed loads are applied on the upper and on the lower surfaces of the airfoil to produce an improved structural response during flight. A merit function containing maximum equivalent von-Mises stress, maximum displacement and strain energy is computed in order to quantitatively evaluate which wing rib concepts present the best overall structural performance. In addition, a structural optimization problem is performed using Topology Optimization (TO). This mathematical method, which optimizes material layout within a given design space for a given set of loads, boundary conditions and constraints with the goal of maximizing the performance of the system, is applied to minimize the wing rib mass subject to strength and stiffness constraints. The results show a general good agreement between the displacements and stresses numerically calculated and the results obtained from experimental tests. Topology optimization is useful to produce structurally improved wing ribs with complex non-trivial layouts which are easily obtained by AM techniques. Some sources of numerical and experimental errors are identified and some enhancements are proposed.
Additive manufacturing (AM) has emerged over the last years has a key technology in aircraft structural components’ manufacturing. It enables more complex and more efficient structural topologies to be explored as well as to reduce material waste. The present work aims at investigating stiffness and strength characteristics of several wing ribs having different prescribed or optimized structural topologies that were built by AM. This paper describes the design, the numerical and experimental procedures and the optimization of wing ribs manufactured with polylactic acid (PLA) using the Fused Deposition Modeling (FDM) technology. The studied wing rib concepts were designed based on some traditional configurations where bending loads and shear loads must be transmitted along the rib to the wing spar. These wing rib layouts include two-dimensional truss, honeycomb and lightening-hole topologies, among others. Numerical analyses were performed using Ansys Workbench’s static structural analysis for two distinct loading cases. The first loading is a simplification in which the chordwise distributed force, resulting from wing lift, is replaced by two equivalent concentrated loads at the leading and trailing edges. The objective here is to numerically analyze a situation whose experimental validation is feasible. The second loading represents a more realistic situation where distributed loads are applied on the upper and on the lower surfaces of the airfoil to produce an improved structural response during flight. A merit function containing maximum equivalent von-Mises stress, maximum displacement and strain energy is computed in order to quantitatively evaluate which wing rib concepts present the best overall structural performance. In addition, a structural optimization problem is performed using Topology Optimization (TO). This mathematical method, which optimizes material layout within a given design space for a given set of loads, boundary conditions and constraints with the goal of maximizing the performance of the system, is applied to minimize the wing rib mass subject to strength and stiffness constraints. The results show a general good agreement between the displacements and stresses numerically calculated and the results obtained from experimental tests. Topology optimization is useful to produce structurally improved wing ribs with complex non-trivial layouts which are easily obtained by AM techniques. Some sources of numerical and experimental errors are identified and some enhancements are proposed.
Description
Keywords
Fabrico Aditivo Nervura Otimização Topológica