Preface to the Sixth Edition of Aircraft Structures

Megson, T.H.G.

doi:10.1016/b978-0-08-100914-7.09991-6

Cited by 7 publications

(10 citation statements)

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“…In some texts, 1 the symbol J is reserved for the polar second moment of area which is not implied here. Furthermore, in some texts on thin shell theory, 11 where the product of the shell thickness and the second moment of length is used extensively, the symbol I is employed and the implied meaning must be discerned from the context. A similar result is obtained for the position of the centroid in the y-direction, where cosθ is replaced by sinθ in the integral to yield,…”

Section: Centroid Of a Surface Of Revolutionmentioning

confidence: 99%

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Extensions to the theorems of Pappus to determine the centroids of solids and surfaces of revolution

Cloete

2023

International Journal of Mechanical Engineering Education

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Extensions to the first and second theorems of Pappus are presented, whereby the centroid of a surface or solid of revolution can be determined using only the geometric properties of the generating plane curve or figure and the arc of revolution. The derivations are well suited to first-year-level courses in mathematics and engineering. From a didactic perspective, the resulting formulas are simple to apply, especially since the required geometric properties are typically available in standard tables of plane sections or relatively routine to derive. Furthermore, the formulas provide a general scaffold for students to attempt problems involving axisymmetric bodies while also reinforcing and embedding their knowledge of the properties of the generating plane shapes. A selection of illustrative problems is discussed that are generally regarded to be challenging for introductory mechanics courses but for which the formulas derived in this article provide straightforward solutions.

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Section: Centroid Of a Surface Of Revolutionmentioning

confidence: 99%

“…where the second integral is recognized as the product second moment of length of the generating plane figure relative to the r-and z-axes, J rz , 11 giving the final result,…”

Section: Centroid Of a Surface Of Revolutionmentioning

confidence: 99%

Extensions to the theorems of Pappus to determine the centroids of solids and surfaces of revolution

Cloete

2023

International Journal of Mechanical Engineering Education

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“…a principal função da asa é para reduzir o arrasto induzido na ponta da asa trapezoidal mas com uma estrutura mais resistente, onde da raiz começa retangular e perto da ponta começa a ficar trapezoidal, sendo assim mais eficiente e de melhor fabrico e baixo custo de produção [15] . Certamente foi realizado testes específicos após a nova modificação, e foi detectado que a ponta da nova asa entrava em ressonância harmônica quando o avião se encontrava em determinada condição de alto fator de carga n [7] e com uma velocidade específica (flutter).…”

Section: Flutterunclassified

Mitigação de vibrações de longarinas de asas aeronáuticas em situação de flutter

Silva¹,

Santos²

2023

Braz. J. Develop.

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O presente projeto de pesquisa tem como objetivo estudar a mitigação de vibrações de longarinas de asas aeronáuticas em casos de flutter. Para estes casos será estudado juntamente, aero elasticidade, que é definida como a ciência que está interessada na interação mútua entre as forças elásticas, aerodinâmicas e inerciais em um corpo sobre escoamento aerodinâmico. Entre os fenômenos aero elásticos, o flutter pode ser definido como a interação auto excitada de dois ou mais modos de vibração de um sistema devidamente alterado. Este é realimentado pelo escoamento de um fluído, podendo, a certas velocidades (velocidade de flutter), resultar em uma falha trágica. Isso ocorre por conta do desenvolvimento de oscilações de amplitudes crescentes, prejudicando o desempenho e segurança da aeronave, podendo levar a uma falha da estrutura da mesma [6] . Isto se constitui em um problema crítico enfrentado pelos projetistas de aeronaves, principalmente no desenho daquelas onde é necessário um grande desempenho. Neste caso é necessário reduzir o peso e controlar as cargas aerodinâmicas. Assim, foi desenvolvido um método analítico através da equação do movimento para uma seção típica com dois graus de liberdade: torção e flexão. A obtenção da velocidade de flutter para o problema da aeronave estudada, foi realizada através da análise das matrizes de rigidez e de massa, obtendo-se um diagrama V-f além dos valores de amortecimento em função da velocidade V. Por fim, foi adicionado um grau de liberdade ao sistema, correspondente a um TMD (Tunned Mass Damper), que teve por objetivo aumentar a velocidade de flutter para que a aeronave pudesse ter um range maior de velocidades para operação. Sugestões para trabalhos futuros, também foram apresentadas.

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“…A complex structure can be idealized into simpler models that behave in a similar manner as the real structure. Megson (2007) proposes in ideal mechanical model based on a skinboom combination. The conservative assumptions behind this model are that stringers and spars can be substituted by area concentrations, which will carry all direct stresses, while the skins will carry only shear stresses.…”

Section: Composite Materials Mechanics In Aircraft Structuresmentioning

confidence: 99%

“…Finally, the shear loads acting on the skin panels and the boom's normal loads are evaluated. More details on the calculation process can be consulted in Ricci (2019) and Megson (2007). The model also provides longitudinal and angular displacements at the wingtip position.…”

Section: Design Proceduresmentioning

confidence: 99%

Multiobjective optimization of the LASER aircraft wing’s composite structural design

Ricco

Coimbra

Gomes

2021

AEAT

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Purpose Aircraft wings, one of the most important parts of an aircraft, have seen changes in its topological and design arrangement of both the internal structures and external shape during the past decades. This study, a numerical, aims to minimize the weight of multilaminate composite aerospace structures using multiobjective optimization. Design/methodology/approach The methodology started with the determination of the requirements, both imposed by the certifying authority and those inherent to the light, aerobatic, simple, economic and robust (LASER) project. After defining the requirements, the loads that the aircraft would be subjected to during its operation were defined from the flight envelope considering finite element analysis. The design vector consists of material choice for each laminate of the structure (20 in total), ply number and lay-up sequence (respecting the manufacturing rules) and main spar position to obtain a lightweight and cheap structure, respecting the restrictions of stress, margins of safety, displacements and buckling. Findings The results obtained indicated a predominance of the use of carbon fiber. The predominant orientation found on the main spar flange was 0° with its location at 28% of the local chord, in the secondary and main web were ±45°, the skins also had the main orientation at ±45°. Originality/value The key innovations in this paper include the evaluation, development and optimization of a laminated composite structure applied to a LASER aircraft wings considering both structural performance and manufacturing costs in multiobjetive optimization. This paper is one of the most advanced investigations performed to composite LASER aircraft.

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Preface to the Sixth Edition of Aircraft Structures

Cited by 7 publications

References 0 publications

Extensions to the theorems of Pappus to determine the centroids of solids and surfaces of revolution

Extensions to the theorems of Pappus to determine the centroids of solids and surfaces of revolution

Mitigação de vibrações de longarinas de asas aeronáuticas em situação de flutter

Multiobjective optimization of the LASER aircraft wing’s composite structural design

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