48 research outputs found
Design and analysis of a low cost, deployable unmanned aerial vehicle for environmental surveillance
Capstone Project submitted to the Department of Engineering, Ashesi University in partial fulfillment of the requirements for the award of Bachelor of Science degree in Mechanical Engineering, May 2021Surveillance aircraft require long flight endurance and range to perform their task fully. An
aircraft's flight endurance can be increased by lowering the aircraft's weight and increasing
the UAV's wingspan. However, the challenges that arise with a long wingspan are increased
weight and costs due to the addition of materials to the wing. Most importantly, it results in
large volumes that take much storage space resulting in difficulties in storing and deploying
multiple UAVs. This project discusses the design and analysis of a low-cost micro-UAV with
collapsible wings made from lightweight, flexible fabric. The UAV designed in this paper
weighs less than 300g and flies at an altitude of 200m and a flight endurance of approximately
45 minutes. Size optimisation was done in guidance with the mission and design requirements.
Flight endurance baseline was established by deriving a mathematical endurance model
together with power sizing. The shape of the UAV was defined using configuration selection. This was followed by 3D modelling of parts and were assembled using SolidWorks software.
To wrap the design, an XFLR5 software was used to analyse and select aerofoils and analyse
the UAV's aerodynamic performance, Cl, Cd and Cl/Cd. The coefficient of lift of the aircraft
when cruising is 0.455. Results from XFLR5 were compared with the analytically predicted
values. Lastly, structural analysis (Finite Element Analysis (FEA)) was performed numerically
(using SolidWorks) to determine the structural performance of the wing hinge to avoid failures
due to static and fatigue torsional stresses. The critical point on the hinge had 0.74% damage
and a safety factor of 2.258, showing that the hinge is unlikely to fail.
Keywords: UAV Design, Aerofoil, XFLR5, Flight EnduranceAshesi Universit
Inflatable structure for aerospace application: Historical perspective and future outlook
No Abstract
Design for additive manufacturing: Trends, opportunities, considerations, and constraints
The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future challenges, and identifies promising directions for research and the exploitation of AM's full potential in industry
Design for additive manufacturing: trends, opportunities, considerations, and constraints
© 2016 CIRP. The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future challenges, and identifies promising directions for research and the exploitation of AM's full potential in industry
Design in Engineering: An Evaluation of Civilian and Military Unmanned Aerial Vehicle Platforms, Considering Smart Sensing with Ethical Design to Embody Mitigation Against Asymmetric Hostile Actor Exploitation
This report is written in part-fulfilment of personal output criteria for the Visiting Research Fellowship (Sir Richard Grenville Fellowship) at the Changing Character of War Centre, Pembroke College, Oxford, and the Centre for Sea Power and Strategy, Britannia Royal Naval College, Plymouth University at BRNC, Dartmouth. In this report I undertook an extensive analysis of the maritime UAV platform systems sector of a wide range of upstream manufacturing industry and downstream end user stakeholders. I consulted a global range of military and civilian users, to inform discussions around civilian UAV platforms which could be modified by hostile non-state actors, with emphasis on the littoral maritime region. This has strategic relevance to the United Kingdom, being an island-state with over 10,000 miles of coastline, c. 600 ports, and nearly 300 off-shore oil and gas platforms. In addition the UK has 14 dependencies together with a combined EEZ of 2.5 million square miles, the fifth largest in the world
Investigação e otimização topológica de nervuras obtidas através de fabrico aditivo
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
12th EASN International Conference on "Innovation in Aviation & Space for opening New Horizons"
Epoxy resins show a combination of thermal stability, good mechanical performance, and durability, which make these materials suitable for many applications in the Aerospace industry. Different types of curing agents can be utilized for curing epoxy systems. The use of aliphatic amines as curing agent is preferable over the toxic aromatic ones, though their incorporation increases the flammability of the resin. Recently, we have developed different hybrid strategies, where the sol-gel technique has been exploited in combination with two DOPO-based flame retardants and other synergists or the use of humic acid and ammonium polyphosphate to achieve non-dripping V-0 classification in UL 94 vertical flame spread tests, with low phosphorous loadings (e.g., 1-2 wt%). These strategies improved the flame retardancy of the epoxy matrix, without any detrimental impact on the mechanical and thermal properties of the composites. Finally, the formation of a hybrid silica-epoxy network accounted for the establishment of tailored interphases, due to a better dispersion of more polar additives in the hydrophobic resin