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Svalstedt, Mats, and Sofia Swedberg. "Commercial Aircraft Wing Structure : - Design of a Carbon Fiber Composite Structure." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276702.
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This project explores the classical wing structure of an commercial aircraft for an all carbon fiber reinforced polymer unmanned aerial vehicle(UAV). It is part of a collaborative work consisting of several groups researching different parts of the aircraft. The objective of this report is to present the design of the inner wing structure for a greener, more efficient scaled 2:1 version of the Skywalker X8. In order to make the aircraft as efficient as possible, the structure needs to be lightweight. The loads were first approximated using XFLR5 and a first design made. The design was then tested using finite element analysis (FEA) in the programme Ansys Static Structural. The material that was tested was carbon fiber/epoxy prepreg. The final design of the wing weighs 3.815 kg, and consists of one spar and a skin thickness of 1 mm. The weight of the whole aircraft, including the propulsion system and a sharklet at both wingtips researched by other groups, is 20.262 kg. The lift-to-drag ratio was also calculated, and the most efficient angle of attack was concluded to be around 2-3°.Detta projekt utforskar den klassiska vingstrukturen av ett kommersiellt flygplan för en obemannad luftfarkost gjord helt i kolfiberarmerad polymer. Det är en del av ett samarbete som består av flera projektgrupper som forskar på olika delar av flygplanet. Målet med projektet är att designa den inre vingstrukturen för en miljövänligare, mer effektiv uppskalad 2:1 version av drönaren Skywalker X8. För att göra flygplanet så effektiv som möjligt så behöver den vara lättviktig. Lasterna var först uppskattade via XFLR5 och en första design gjordes. Designen testades sedan med finita elementmetoden (FEM) i programmet Ansys Static Structural. Materialet som testades var kolfiber/epoxi prepreg. Den slutgiltiga vingdesignen väger 3.815 kg, och består av en bom och en tjocklek på 1 mm av vingskalet. Totala vikten av flygplanet, inklusive framdrivningssystemet samt virveldämpare på båda vingspetsarna som är framtagna av andra grupper, är 20.262 kg. Glidtalet beräknades även, och är som mest effektiv runt 2-3°.
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Eustace, Paul Alan. "Structural mass of innovative concept aircraft." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/7361.
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Bingham, Christopher Malcolm. "Application of variable structure control methods to actuator nonlinearities in aerospace systems." Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358823.
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Spurgeon, S. K. "An assessment of robustness of flight control systems based on variable structure techniques." Thesis, University of York, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383881.
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Dalton, Roger Patrick. "Propagation of LAMB waves in metallic aircraft fuselage structure." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392345.
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Faddy, James Malcolm Pullin Dale Ian. "Flow structure in a model of aircraft trailing vortices /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05272005-163801.
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Reytier, Thomas. "Modelling fatigue spectra of aircraft structure under gust loads." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1614/.
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Cette thèse est consacrée à l'analyse de fatigue et de tolérance aux dommages des structures d'avions soumis aux rafales de vent. L'analyse de fatigue et de tolérance aux dommages est un enjeu essentiel dans la conception des structures d'avions. Elle permet de définir un programme d'inspection de la structure afin d'assurer sa sécurité tout au long de la vie de l'avion. La première partie passe en revue l'état de l'art dans les différents domaines impliqués dans le processus global d'analyse de fatigue des structures d'avions soumis aux rafales de vent: la modélisation de la turbulence atmosphérique, le calcul des charges et des contraintes à l'aide d'analyses par éléments finis, la construction du spectre de fatigue et enfin, l'analyse de fatigue et de tolérance aux dommages. La deuxième partie présente le processus complet actuellement implémenté au sein d'Airbus. Les points forts et les points faibles de ce processus sont d'identifiés et permettent de dégager des axes d'amélioration. A partir du modèle de turbulence continue basé sur la densité spectrale de puissance (DSP) de Von Karman, les contraintes calculées sont insérées selon des statistiques établies par des mesures envol dans le spectre de fatigue pour former une séquence de cycles de contraintes. Les données d'entrée pour l'analyse de fatigue et tolérance aux dommages sont obtenues à partir de la définition des différents profils de mission, des valeurs de contraintes unitaires, de la réponse dynamique de la structure et des statistiques de turbulence. Dans la troisième partie, une nouvelle méthodologie est présentée afin d'obtenir des séquences temporelles des contraintes dues à la turbulence de manière précise et efficace. Cette méthode s'appuie sur de nouveaux résultats permettant de générer des signaux temporels corrélés à partir des DSP. Tout d'abord, les DSP des différentes composantes des contraintes sont directement obtenues à l'aide d'une analyse par éléments finis à partir de la DSP de Von Karman. Puis, les séquences temporelles corrélées de ces contraintes sont générées et sont ensuite distribuées dans le spectre de fatigue selon la loi statistique de l'intensité de la turbulence atmosphérique. Ce nouveau processus permet d'améliorer le calcul des contraintes et la génération du spectre de fatigue. Il remplace les statistiques de turbulence par des statistiques de franchissement de niveaux de contraintes raisonnablement conservatives définies par une formule analytique. De plus, le temps de livraison des données d'entrée pour l'analyse de fatigue et tolérance aux dommages est significativement réduit. Les résultats présentés, issus de l'analyse de fatigue et de tolérance aux dommages, permettent de souligner la qualité des améliorations apportées à la fois en termes de précision et de durée du processusThis thesis is dedicated to the fatigue and damage tolerance analysis of the aircraft structures under gust loads. The fatigue and damage tolerance analysis is a significant issue in the aircraft structure design. It aims at defining the inspection program of the aircraft structure in order to ensure its safety through its entire life. The first part reviews the state-of-the-art in the various involved topics for the global process for fatigue analysis of aircraft structure under gust loads: the atmospheric turbulence modelling, the load and stress computation by a finite element analysis, the generation of the fatigue spectrum and at the end, the fatigue and damage tolerance analysis. The second part presents the whole process currently implemented at Airbus. The main strengths and weaknesses are pointed out and this en-ables the identification of several improvement axes. From the continuous turbulence model based on the Von Karman Power Spectral Density(PSD), the computed stresses are included according to statistics established from in-flight measurements in the fatigue spectrum in order to build a stress cycle sequence. The input data for the fatigue and damage tolerance analysis are obtained from the definition of the various fatigue mission profiles, the unitary stress values, the dynamic response of the structure and the turbulence statistics. In the third part,a new methodology is presented in order to obtaine efficiently and accurately the temporal stress sequences due to the atmospheric turbulence. This method relies on new results enabling the generation of correlated time signals from the PSD functions. First, the PSD of the various stress components are directly obtained from the Von Karman PSD via a finite element analysis. Then, the correlated temporal stress sequences are generated and distributed in the fatigue spectrum according to the turbulence intensity statistical law. This new process enables the improvement of the stress computation and the fatigue spectrum generation. It replaces the turbulence statistics by stress exceedance statistics which are defined by an analytical formula in a reasonably conservative way. In addition, the lead time to build the input data for the fatigue and damage tolerance analysis is significantly reduced. Results from the fatigue and damage tolerance analysis are presented in order to highlight the quality of the improved processes both in terms of accuracy and lead time
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Sonelius, Ulrika. "FISST - Fully Integrated Shell Structure : OPTIMIZATION OF AN AIRCRAFT FUSELAGE." Thesis, KTH, Lättkonstruktioner, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-164286.
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In order to reduce the costs of aircraft, the weight of the fuselage has to be reduced. This master thesis, collaboration between the Royal Institute of Technology and Airbus Group, aims to optimize a new aircraft fuselage under development. This new fuselage design, called FISST, consists of a sandwich panel to stiffen the structure instead of the stringers used in baseline fuselage. Apart from the goal of reducing the weight, the new design also has advantages during maintenance and repairing. During this project the FISST-concept has been optimized, by modeling using the Finite Element Method, in order to fulfill given requirements. The design has been evaluated for buckling, strains and displacements. Furthermore modeling methods have been validated in order to ensure that the results are accurate enough. This report shows that the FISST-concept fulfills the given requirements better than the baseline.
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Goksel, Lorens Sarim. "Fatigue and damage tolerance assessment of aircraft structure under uncertainty." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49124.
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This thesis presents a new modeling framework and application methodology for
the study of aircraft structures. The framework provides a ‘cradle-to-grave’ approach to
structural analysis of a component, where structural integrity encompasses all phases of
its lifespan.
The methodology examines the holistic structural design of aircraft components
by integrating fatigue and damage tolerance methodologies. It accomplishes this by
marrying the load inputs from a fatigue analysis for new design, into a risk analysis for an
existing design. The risk analysis incorporates the variability found from literature,
including recorded defects, loadings, and material strength properties.
The methodology is verified via formal conceptualization of the structures, which
are demonstrated on an actual hydraulic accumulator and an engine nacelle inlet. The
hydraulic accumulator is examined for structural integrity utilizing different base
materials undergoing variable amplitude loading. Integrity is accomplished through a
risk analysis by means of fault tree analysis. The engine nacelle inlet uses the damage
tolerance philosophy for a sonic fatigue condition undergoing both constant amplitude
loading and a theoretical flight design case. Residual strength changes are examined
throughout crack growth, where structural integrity is accomplished through a risk
analysis of component strength versus probability of failure.
Both methodologies can be applied to nearly any structural application, not
necessarily limited to aerospace.
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Bigand, Audrey. "Damage assessment on aircraft composite structure due to lightning constraints." Thesis, Toulouse, ISAE, 2020. http://www.theses.fr/2020ESAE0027.
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L’utilisation des matériaux composites dans l’industrie aéronautique s’étant largement étendue, ledimensionnement de ces structures et de leur protection vis-à-vis de la foudre est devenu un enjeu majeur. Ilest important de pouvoir développer des outils prédictifs permettant d’obtenir une conception de structurerépondant aux critères de certification avec des temps et coûts de conception maitrisés. L’interaction de lafoudre avec une structure composite est un phénomène multiphysique complexe, avec une difficulté ajoutéepar la présence d’une protection métallique en surface et d’une couche de peinture. Dans ce contexte, cetteétude a visé à développer la compréhension par rapport aux forces générées par la foudre et d’en évaluer sesconséquences quant à l’endommagement du composite. Dans cet objectif, le phénomène a d’abord étédécomposé pour en étudier ses différentes parties et définir l’impact des interactions. Dans un premier temps,l’arc libre a été comparé au pied d’arc en interaction avec différents substrats permettant de définir un modèlede vaporisation de la protection foudre. Dans un second temps, la surpression générée par l’explosion de laprotection en surface lors de la vaporisation a été évaluée pour définir des profils de pression spatio-temporels.Dans un troisième temps, une caractérisation mécanique de la peinture a été développée afin de quantifier soneffet de confinement sur l’explosion de surface. A chaque étape, une théorie a été développée et analysée viades modèles numériques et des essais. Enfin, ces trois différentes briques ont été rassemblées dans un modèlemécanique simulant l’impact foudre sur une structure composite afin d’en prédire l’endommagement. De plus,une loi utilisateur a été développée pour appliquer ce chargement complexe ainsi qu’une loid’endommagement. Ces modèles sont comparés aux résultats d’essai foudre en laboratoire afin d’endéterminer les limites de validité et leur capacité à prédire l'endommagementAs composite materials are now widely used in the aeronautical industry, the sizing of these structures andtheir protection against lightning has become a major issue. It is important to develop predictive tools to obtaina structure concept that meets certification requirements with a controlled time and cost during the designphase. The interaction of lightning with a composite structure is a complex multi-physics phenomenon, with afurther difficulty due to the presence of a metallic protection on the surface and a layer of paint. In this context,this study aimed to develop an understanding of the forces generated by lightning and to assess itsconsequences in terms of damage to the composite. To this end, the phenomenon was first broken down tostudy its different components and define the impact of their interactions. In a first step, the free arc wascompared to the arc root in interaction with different substrates to define a vaporisation model of the lightningprotection. In a second step, the overpressure generated by the explosion of the surface protection duringvaporisation was evaluated to define spatio-temporal pressure profiles. In a third step, a mechanicalcharacterization of the paint was developed in order to quantify its confinement effect on the surface explosion.At each stage, a theory was developed and analysed via numerical models and tests. Finally, these threedifferent bricks are brought together in a mechanical model simulating the lightning impact on a compositestructure in order to predict the damage. In addition, a user subroutine has been developed to apply thiscomplex loading as well as a damage law. These models are compared with lightning laboratory test results todetermine their validity limits and their ability to predict the damage
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Mahdi, Stephane. "The performance of bonded repairs to composite structures." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/7815.
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Mills, Austin Shelley. "The Structural Suitability of Tensegrity Aircraft Wings." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1590172090108379.
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Huang, Haidong. "Optimal design of a flying-wing aircraft inner wing structure configuration." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7439.
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Flying-wing aircraft are considered to have great advantages and potentials in
aerodynamic performance and weight saving. However, they also have many
challenges in design. One of the biggest challenges is the structural design of
the inner wing (fuselage). Unlike the conventional fuselage of a tube
configuration, the flying-wing aircraft inner wing cross section is limited to a
noncircular shape, which is not structurally efficient to resist the internal
pressure load. In order to solve this problem, a number of configurations have
been proposed by other designers such as Multi Bubble Fuselage (MBF),
Vaulted Ribbed Shell (VLRS), Flat Ribbed Shell (FRS), Vaulted Shell
Honeycomb Core (VLHC), Flat Sandwich Shell Honeycomb Core (FLHC), Y
Braced Box Fuselage and the modified fuselage designed with Y brace
replaced by vaulted shell configurations. However all these configurations still
inevitably have structural weight penalty compared with optimal tube fuselage
layout. This current study intends to focus on finding an optimal configuration
with minimum structural weight penalty for a flying-wing concept in a preliminary
design stage.
A new possible inner wing configuration, in terms of aerodynamic shape and
structural layout, was proposed by the author, and it might be referred as
‘Wave-Section Configuration’. The methodologies of how to obtain a structurally
efficient curvature of the shape, as well as how to conduct the initial sizing were
incorporated.
A theoretical analysis of load transmission indicated that the Wave-Section
Configuration is feasible, and this was further proved as being practical by FE
analysis. Moreover, initial FE analysis and comparison of the Wave-Section
Configuration with two other typical configurations, Multi Bubble Fuselage and
Conventional Wing, suggested that the Wave-Section Configuration is an
optimal design in terms of weight saving. However, due to limitations of the
author’s research area, influences on aerodynamic performances have not yet
been taken into account.
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Mosinyi, Bao Rasebolai Awerbuch Jonathan Lau Alan C. W. Tan Tein-Min. "Fatigue damage assessment of high-usage in-service aircraft fuselage structure /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/2762.
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Satterwhite, Matthew Ryan. "Development and Validation of Fluid-Structure Interaction in Aircraft Crashworthiness Studies." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51559.
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Current Federal Aviation Regulations require costly and time consuming crashworthiness testing to certify aircraft. These tests are only capable of a limited assessment of progressive damage and all crash configurations and scenarios cannot be physically evaluated. Advancements in technology have led to accurate and effective developments in numerical modeling that have the possibility of replacing these rigorous physical experiments. Through finite element analysis, an in-depth investigation of an aircraft equipped with a fabricated composite undercarriage was evaluated during water ditching. The severe impact of aircraft ditching is dynamic and nonlinear in nature; the goal of this work to develop a methodology that not only captures the structural response of the aircraft, but also the fluidic behavior of the water. Fundamental studies were first conducted on a well-researched fluid-solid interaction problem, the water entry of a wedge. Typical modeling strategies did not capture the desired detail of the event. An advanced meshing scheme combining meshed and meshless Lagrangian techniques was developed and multiple wedge angles were tested and compared to analytic and qualitative results. The meshing technique proved valid, as the difficult to model phenomena of splashing was captured and the maximum impact force was within five percent of analytical calculations for the 20° and 30° deadrise wedge. Physical small scale aircraft ditching experiments were then performed with an innovative testing platform capable of producing varied aircraft approach configurations. The model was outfitted with an instrumented composite undercarriage to record data throughout the impact while a high-speed camera recorded the event. Numerical simulations of the model aircraft were then compared to experimental results with a strong correlation. This methodology was then ultimately tested on a deformable model of a fuselage section of a full-size aircraft.Master of Science
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Knöös, Franzén Ludvig, and Erik Magnusson. "Weight Penalty Methods for Conceptual Aircraft Design." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-175012.
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This report addresses a project conducted at Saab Aeronautics during the spring of 2018. The goal of the project was to investigate aircraft weight estimations in the conceptual design phase. The work was divided into two major parts: finding new weight estimation techniques and implementing an existing technique called the Berry Weight Estimation in to the Pacelab APD software. Several weight estimation techniques were found during an extensive literature review but in the end, only one was chosen for further investigation. The chosen technique was the NASA Wing Weight Build-Up which proposed calculations for wing weights based on aircraft statistics. It contained material data tables for determining so called K-factors that were used to essentially scale the individual wing weight formulas. The data tables did not include K-factors up to a load factor of 9 which was a requirement from Saab. Extrapolations of the material data tables were done to approximate the missing values. The NASA wing weight build-up showed promising results with little deviation from the actual wing weight for a few chosen aircraft. This weight estimation technique was consequently chosen as a worthy candidate for a future implementation in the Pacelab APD software. The task of implementing the Berry Weight Estimation in Pacelab APD was divided into a fuselage- and a wing part. This was done to ease the implementation since it would resemble the original description of the method. The wing and fuselage weights were both calculated in two steps. The first step was to calculate a gross shell weight. This is the weight of an idealized structure without cut-outs or imperfections. The second step was to add so called weight penalties for various components within the wing or fuselage. Typical aircraft components had associating weight penalty functions described in the Berry Weight Estimation. Most of the implemented calculations used Pacelab APD to get involved parameters automatically. However, some of the needed parameters had to be user specified for the implemented Berry Weight Estimation to work. Once the implementation task was finished, several sensitivity studies were made to establish a perception about the involved parameters impact on the Berry Weight Estimation results. The new implementation gave benefits compared with the Berry Weight Estimation in Bex. One of these was the ability to perform extensive trade- and sensitivity studies. The sensitivity studies gave verdicts on the most influencing parameters of the implemented code and guide lines on future improvements of the calculations. These sensitivity studies show, among other things, that is recommended to increase the number of wing and fuselage stations significantly in order to get a converged result for the Berry Weight Estimation.
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Foister, Steven A. M. "The interaction of ultrasound with the material structure of titanium alloys." Thesis, University of Surrey, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301330.
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Bail, Justin L. "Non-desctructive investigation & FEA correlation on an aircraft sandwich composite structure." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1196702586.
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Thesis (M.S.)--University of Akron, Dept. of Civil Engineering, 2007."December, 2007." Title from electronic thesis title page (viewed 02/25/2008) Advisor, Wieslaw Binienda; Faculty readers, Craig Menzemer, Robert Goldbert; Department Chair, Wieslaw Binienda; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Bail, Justin. "Non-Destructive Investigation & FEA Correlation on an Aircraft Sandwich Composite STructure." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1196702586.
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Farao, Javon. "Toward a full aircraft model platform for fuel slosh-structure interaction simulations." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24315.
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The purpose of this study was to initiate the development of a full aircraft model (FAM) for the purpose of non-linear loads calculation of an aircraft. The FAM is employed during the design process of an aircraft and comprises of various reduced-order models (ROMs). These are mainly structural, slosh and aerodynamic loads. This study focused on the structural and slosh aspects using Ele- mental(TM) software as the base. First, a structural ROM was developed such that it is compatible with Airbus data and processes. The developed code reads in MSC Nastran data, from which Hermitian finite element discretisation is performed followed by transient calculations. To this end, the structure was represented by Timoshenko beam theory. The structural ROM was validated and verified against the widely used MSC Nastran commercial software. Simulated dynamic responses were within 5% while eigenvalue predictions were within 2% of each other. Secondly, a strongly-coupled partitioned fluid-structure interaction (FSI) scheme was deployed to incorporate the high-fidelity sloshing fluid onto the structure. Lastly, the developed FSI technology was verified and validated against challenging analytical as well as real-world benchmark test cases. It was demonstrated to be accurate and robust in all cases.
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Liu, Hongfen. "A structural design comparison of metallic and composite aircraft pressure retaining doors." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7308.
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The pressure retaining door is obviously a sensible part of an aircraft, and the design criteria is much more critical than for the fuselage, so a problem caused by this critical criteria is the heavy weight of the door structure because it should be strong enough to withstand loads and stiff enough to meet the sealing requirements.
In spite of the pressure retaining door being so important, it is difficult to find design references. So, in this thesis, the pressure retaining door is investigated first, and then a typical structure of a type A door is selected as the study case using both metallic and composite material, in order to generate a standard method for door structure design, and to identify the key factors which can affect the structure weight.
The study indicates that the structure weight of a type A door can be kept in a range for different combinations of beams and stringers, and the composite door structure can be 20% lighter than the metallic door while the stiffness of the two doors remains similar. It is found that the skin contributes much more weight to the door structure than other components and the skin thickness is affected by the short edge of the skin panel divided by beams and stringers.
The results also found that it is much more serious when the end stop fails than when the middle stops fail.
Therefore, it appears that the composite door is a good material as an alternative to aluminium. Also the method of door structure design is reasonable for the composite door, although it would be better to consider the stiffness of beams while in the theory design period.
Besides IRP, the Group Design Project (GDP) is another important part of the MSc study; it lasts nearly half a year and we complete the Fly-wing concept design. The main contribution of the author to the GDP is the arrangement of doors, and also includes the family issues, cabin layout arrangement and a 3D model construct, which can be seen in APPENDIX B. According to the GDP work, I will have broadened my professional knowledge and will have an overall view of aircraft design.
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Yalcin, Mehmet Efruz. "Design And Analysis Of An Equipment Rack Structure Of A Medium Transport Aircraft." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611123/index.pdf.
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In this study, equipment rack structure for a medium transport aircraft was designed and finite element analysis of this design was performed. The equipment rack structure, which was designed for a modernization project, was positioned and dimensions were determined by regarding the geometry of primary structures of the aircraft. The structure was designed such that it satisfies the pre-defined margin of safety values. Design of the structure was prepared in Unigraphics, and the finite element modeling and analysis phases were carried out using MSC.Patran and MSC.Nastran programs. For the fastener analysis, which is usually carried out by hand calculations, two analysis tools were prepared by using FORTRAN and Microsoft Office Excel programs. These tools were found to greatly facilitate the analysis and save time. As these tools can be used in other finite element analyses, in which MSC.Patran and MSC.Nastran programs are used, user manuals were prepared.
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Ma, Leong. "Crack link up and residual strength of aircraft structure containing multiple site damage /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/7039.
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Crump, Duncan Andrew. "Performance analysis of a reduced cost manufacturing process for composite aircraft secondary structure." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/142803/.
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In the current, environmentally-aware, climate aircraft designers are under increasing pressure to produce fuel efficient vehicles. Weight reduction is an important method for increasing fuel efficiency. Fibre reinforced polymer (FRP) composites are known to offer weight savings over traditional metallic components, due to their excellent stiffness and strength to weight ratios. However, the major limiting factor for the use of aerospace quality composites is the manufacturing cost. The costs incurred in the conventional process of prepreg cured in an autoclave are well documented. The research in this thesis is concerned with reducing the cost of manufacturing aircraft standard carbon fibre composite sandwich panels, whilst maintaining mechanical performance. The overall aim of the EngD is to provide a unified approach for assessing the performance of carbon fibre sandwich secondary structure that are manufactured using several different techniques. Cost and performance criteria are defined so that an optimal panel can be produced. The work has been motivated by the industrial sponsor, GE Aviation Systems. Five combinations of raw material and processing techniques, manufacturing options (MOs) were considered in incremental steps from the baseline of unidirectional prepreg cured in an autoclave to the noncrimp fabric (NCF) infiltrated using resin film infusion (RFI) and cured in a conventional oven. For cost and performance analysis a generic panel has been designed that is representative of secondary wing structure on commercial passenger aircraft. The cost was estimated by monitoring the manufacture of generic panels using each MO, whilst the performance was measured by both mechanical characterisation tests and by full scale tests on a custom designed rig. The rig applies a pressure load using a water cushion and allows optical access to the surface of the panel enabling the use of optical techniques, i.e. thermoelastic stress analysis (TSA) and digital image correlation (DIC). Feasibility tests on TSA and DIC demonstrated their use on the materials considered in this thesis, and were used to validate finite element (FE) models. The RFI out-of-autoclave process was found to reduce generic panel manufacture time by almost 30%, and the material cost was reduced by almost 40%. The mechanical characterisation tests suggested the ‘new’ process could produce laminates with a similar fibre volume fraction to that of the original process and similar in and out-of-plane mechanical properties. The in-plane stiffness was slightly reduced by 7 %, but the strength showed an increase of 12%. Full scale tests on the generic panels using point out-of-plane deflection measurements and full field TSA demonstrated the panel produced using the ‘new’ process has adequate performance. Moreover the full-field tests indicated an improvement in performance. Further work is required to optimise the design of the panel for weight, in particular the weight of the raw material, and investigating methods for modelling the NCF for certification.
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Dove-Jay, Ashley. "Development, integration and testing of a 0-v honeycomb structure for aircraft morphing." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690034.
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This thesis lays out the development, analysis, integration and testing of a camber morphing concept for control surfaces dealing with fluidic dynamics, with specific focus on replacing the outboard aileron of fixed-wing aircraft in an effort to increase associated fuel efficiency. Core to the development of the morphing concept was a zero Poisson's ratio (O-v) honeycomb. The state-of-the-art was studied, modified for compatibility with the application intended, was subjected to topological optimization to improve relevant performance charactelistics, and was validated through experimental studies. Mass was reduced by 20% and energy for morphing by 42-55% without affecting load-carrying capability; but fatigue life was reduced by 18%. A near-term performance study was conducted. The outboard aileron of a state-of-the-art A320 wing was replaced with the morphing equivalent, demonstrating higher efficiency and increasing aircraft range by 0.8-0.9% depending on weather conditions in a medium fidelity flight simulation (Heathrow to Amsterdam). A first-iteration long-term study, unrestricted by current design constraints, indicated a significant increase in aerodynamic efficiency; towards 50% for high control surface deflections. Coupled to a pre-stressed hyper-elastic surface skin and an an-ay of micro-linear actuators for morphing, the O-u honeycomb was integrated into a 1.05m span wing for wind-tunnel testing. The generated morphed shapes successfully met the overarching geometric objectives; significant reduction in chordwise and spanwise geometric discontinuities and pressure gradients. Comparison between FE and hammer-testing showed modal frequencies agreed with an average en-or of 8%. Comparison between CFD and wind-tunnel studies showed CL agreement with an average error of 0.07 CL. A methodology for whole wing conformal shape optimisation, based on modified Class Shape Transformations and Bemstein Polynomials, enabled by integration of the O-u honeycomb structure generated coupled to cellular micro-linear actuators, was developed and proposed as a logical step forward to explore the full potential of the morphing system proposed.
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Masango, Thubalakhe Patrick. "Condition monitoring of a wing structure for an unmanned aerial vehicle (UAV)." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2384.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2015.Currently non-destructive testing techniques for composite aircraft structures are disadvantaged when compared to online Structural Health Monitoring (SHM) systems that monitor the structure while in-service and give real time data. The present research work looks at developing a protocol for online structural health monitoring of a UAV wing structure using PVDF film sensors, especially including the monitoring of structural changes caused by defects. Different types of SHM techniques were studied in relation to carbon fibre composites. Laminate composite make-up and manufacturing process was investigated and vacuum infusion process was used to manufacture the samples that resemble the Guardian II wing structure, then the three-point bending test was used to determine the material properties. Digital Shearography was employed as a stationery non-destructive technique to determine the sensor to structure attachment, type and position of defects that affect the state of performance. Finite Element Analysis (FEA) was done using ANSYS Workbench which served as a modelling tool using a drawing imported from Solid-works. Experimental investigation was done using PVDF sensor embedded on the surface of the sample in a cantilever setup and a vertical Vernier scale to measure the deflection due to impact and vibration loading. A Fluke-View oscilloscope was used as a data logger when the measurement of the output voltage and the natural frequency were recorded. The techniques of using FEA and experimental investigation were then compared. The findings of this study showed that the PVDF sensor is suitable for condition monitoring of a UAV wing structure.
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Sorenson, Daren S. "Preparing for the long war : transformation of UAVs in future force structure planning for close air support operations /." Norfolk, Va. : Joint Forces Staff College, Joint Advanced Warfighting School, 2006. http://handle.dtic.mil/100.2/ADA451217.
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Thesis (M.S. in Joint Campaign Planning and Strategy)--Joint Forces Staff College, Joint Advanced Warfighting School, 2006.Vita. "National Defense Univ Norfolk VA"--DTIC cover. "14 April 2006." Includes bibliographical references (p. 58-61). Also available via the Internet.
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Backhouse, R. "Multiaxial non-crimp fabrics : characterisation of manufacturing capability for composite aircraft primary structure applications." Thesis, Cranfield University, 1998. http://dspace.lib.cranfield.ac.uk/handle/1826/1929.
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Carbon composite reinforcement fabrics aimed at flight critical aircraft structure application were designed and the capability of the process used to manufacture them examined. Studies of the LIBA multiaxial non-crimp fabric manufacturing process focused on the effect of changes to four manufacturing parameters using an experimental design process to design the fabrics and analyse the results. The composite properties measured included microstructural features of the fibre tows and resin distribution, and mechanical performance both in-plane and their damage resistance and tolerance characteristics. Nine pairs of Toray T300 carbon based LIBA multiaxial non-crimp fabrics were manufactured and converted to composite laminates. Processing was accomplished using the interleaved Resin Film Infusion processing route with commercial Fiberdux 914 matrix resin. All the fabrics were of the same reinforcement type, consisting of 816 g/m2 of fibre; 376 g/m2 oriented along the fabric length (0°) and 220 g/m2 oriented in each of the ±45° directions. Differences between the nine pairs of fabrics were restricted to the settings of four manufacturing parameters; stitch course (needle penetrations/cm); stitch tension, 00 tension and 0° coverage (amount of constraint on the 0° material provided by the stitch). Three settings were used for each of the parameters; each representing the upper and lower limits, and standard setting. Microstructural characterisation of the laminates indicated large differences in both resin distribution and levels of 0° fibre crimp caused by the changes in manufacturing parameter settings. In-plane and damage resistance and tolerance tests on their composites allowed relationships between manufacturing settings, microstructure and engineering properties to be deduced. It was found that selected in-plane properties could be increased by as much as 17% relative to standard production materials, although a wide range of influence was observed. For damage resistance and tolerance characteristics, reductions in impact damage area (C-scan) of between 13-50% are expected across a range of energies. Manufacturing settings to maximise the impact force for delamination initiation were found to minimise the impact damage areas. Similarly the same settings maximised both the Mode I propagation strain energy release rate and the Compression After Impact strength of the materials. It was found that polyester knitting yarn was largely responsible for the control of the damage resistance and tolerance characteristics together with the mean size of the resin areas and layers within the composite. The manufacturing/microstructure/property relationships identified provide those wishing to exploit these materials with design guidelines to tailor fabric structure and performance characteristics for the intended application. Above all else the results highlight the need for precision in specifying and controlling the manufacturing process in order to repeatably produce the desired performance. Further work on the same materials could be used to provide a link to processing characteristics such as permeability for liquid resin moulding processes and ability to conform to complex curved surfaces.
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Doucet, Jeremy. "Fatigue life enhancement of aircraft structures through bonded crack retarders (BCR)." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/11279.
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The trend in aircraft design is to produce greener airplanes through lighter structures and/or structures with extended life and reduced maintenance. Bonded crack retarders (BCR) are one of the solutions towards that objective. BCR are reinforcing straps bonded to the structure in order to improve the fatigue and damage tolerance properties of the assembly. The aim of this study was to demonstrate that the BCR hybrid technology – beneficial for upper wing cover – could also be applied to lower wing covers. The project also focused on evaluating BCR most important parameters. The fatigue life improvement obtained from BCR was evaluated through a series of coupons and skin-stringer assemblies tested under constant and variable amplitude loading. While the coupon tests demonstrated a life improvement of only 17% under constant amplitude loading, the variable amplitude load tests performed on the skin-stringer assembly demonstrated increased fatigue lives with a factor of 5 and reduced crack growth rates with a factor of 5 to 6. A finite element calculation tool was developed in order to conduct a parametric analysis of BCR geometry through the evaluation of the substrate stress intensity factor in the case of fatigue loading. The main difficulty was to include the interacting mechanism of the substrate lead crack and the disbond of the adhesive layer. The novelty of the approach was to incorporate the fatigue delamination calculation in order to evaluate the fatigue disbond propagation with crack growth. This was embedded in a 3D finite element design tool ReSLIC (Reinforced Structures Life Improvement Calculation). A necessary step to the development of ReSLIC was the analysis of fatigue properties of the adhesive system in order to provide input data for fatigue delamination calculations. To that end, a series of fatigue tests were performed in pure Mode I, pure Mode II and mixed mode with ratios of 25%, 50% and 75% of mode II ... [cont.].
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Che, Yunxiang, and S3145469@student rmit edu au. "Aging structure life prediction and reliability assessment." RMIT University. SAMME, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091113.114541.
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Confront with the serious aging problem in aircraft structure field, the profession was tasked to unveil the mysterious in the mechanism of aging. In decades, many endeavours were put into different subjects such as, fatigue and crack calculation, corrosion analysis, reliability evaluation, life prediction, structure monitor and protection, structure repair, etc. In an effort of developing a reasonable model for life prediction and reliability evaluation, a wide range of topics in the field of aging structure reliability are reviewed. Many existing methods and tools are carefully studied to distinguish the advantages, disadvantages and the special application. With consideration of corrosion fatigue life, and based on the data obtained through investigating service status of the aging aircraft, a fuzzy reliability approach is proposed and presented. Initially, the thesis presents the literature review in the field, introducing the well-established theories and analysis tools of reliability and points out how such these methods can be used to assess the life and reliability of aging structure. Meanwhile, some characteristic parameters and distributions, as well as some crucial calculation formulations, procedures for aging aircraft reliability/risk analysis are given. Secondly, mathematical models are established to evaluate the initial crack size and to assess both randomness and fuzziness of the variables, which also successfully work out the probability of survival of existing structures over a time period and predict the operation time under specific reliability requirement. As a practical approach to the reliability of aging aircraft structure, example is presented and evaluated. While conduct the calculation, a few programs based on FORTRAN code are developed to solve the none-linear equation, to work out the multi dimension integration and to simulate the survival probability. The crack life prediction software AFGROW is selected for comparison of the calculation results, which also shows the appropriate accuracy of the established model. As conclusion, the effects of some variables including fuzzy factors on reliability and life of aging aircraft structure are finally discussed. It is apparent that the confines of the model are existing as fact because of the huge assumption of the parameters input and model uncertainties. Suggestions on further prospective research are proposed respectively.
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Rosenwasser, Jon Jason. "Governance structure and weapon innovation : the case of unmanned aerial vehicles /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2004.
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Thesis (Ph.D.)--Tufts University, 2004.Adviser: Robert L. Pfaltzgraff, Jr. Submitted to the Fletcher School of Law and Diplomacy. Includes bibliographical references (leaves 421-445). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Xu, Rongxin. "Optimal design of a composite wing structure for a flying-wing aircraft subject to multi-constraint." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7290.
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This thesis presents a research project and results of design and optimization of a composite wing structure for a large aircraft in flying wing configuration. The design process started from conceptual design and preliminary design, which includes initial sizing and stressing followed by numerical modelling and analysis of the wing structure. The research was then focused on the minimum weight optimization of the /composite wing structure /subject to multiple design /constraints. The modelling, analysis and optimization process has been performed by using the NASTRAN code. The methodology and technique not only make the modelling in high accuracy, but also keep the whole process within one commercial package for practical application.
The example aircraft, called FW-11, is a 250-seat commercial airliner of flying wing configuration designed through our MSc students Group Design Project (GDP) in Cranfield University. Started from conceptual design in the GDP, a high-aspect-ratio and large sweepback angle flying wing configuration has been adopted. During the GDP, the author was responsible for the structural layout design and material selection. Composite material has been chosen as the preferable material for both the inner and outer wing components. Based on the derivation of structural design data in the conceptual phase, the author continued with the preliminary design of the outer wing airframe and then focused on the optimization of the composite wing structure. Cont/d.
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Grun, Eli (Eli Paul). "An application of design structure matrix methods to explore process improvements in aircraft fight line operations." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106246.
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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, School of Engineering, System Design and Management Program, Engineering and Management Program, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 45-47).
The complexities around building, testing, and flying aircraft span many different domains. Some of these domains include processes, people, and tools, of which affect the way work is performed on aircraft. In this thesis, communication tools and the organizations involved in troubleshooting and readying aircraft for flight at an aircraft manufacturer's flight line was analyzed using Design Structure Matrix (DSM) methods. Mapping the two DSMs together into a larger multi-domain matrix (MDM) provided insight to the ways information is transferred, and clarified ways to streamline available information to the various stakeholders, while reducing effort and increasing information quality. One recommendation to streamline flows was to design a system that leverages existing responsibilities of Manufacturing, Quality and Engineering and applying them in an electronic format by utilizing computers (a tool found at every level of employee) to capture live data in an organic fashion. The proposed solution would provide valuable information to other stakeholders at a reduced effort, translating to savings. Savings in the form of interaction reductions could range from 235 to 117, at a 50% reduction in interactions across all organizations. It would also provide a method by which to share information at faster speeds, ensuring all stakeholders are engaged with the latest information. Information quality and speed would further help reduce the risk of flight delays, and improve the customer experience. Overall, reductions in efforts from all organizations and an improved customer experience through rapid and accurate information dissemination, will ultimately reduce cost and promote business and growth.
by Eli Grun.
S.M. in Engineering and Management
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Coleman, Robert Mark 1962. "The effects of design, manufacturing processes and operations management on the assembly of aircraft composite structure." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/42495.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991 and Thesis (M.S.)--Sloan School of Management, 1991.Includes bibliographical references (leaf 104).
by Robert Mark Coleman.
M.S.
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Houglan, Gary D. "The impact of matrix structure and self-managed teams at the Naval Air Warfare Center, Aircraft Division, Indianapolis." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA276937.
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Thesis (M.S. in Management) Naval Postgraduate School, December 1993.Thesis advisor(s): Susan P. Hocevar ; Gail Fann Thomas ; Frank J. Barrett. "December 1993." Bibliography: p. 122-125. Also available online.
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Ančík, Zdeněk. "Mechatronic Design and Verification of Autonomic Thermoelectric Energy Source for Aircraft Application." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-234600.
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Předložená disertační práce řeší komplexní mechatronický návrh autonomního termoelektrického zdroje energie pro letecké aplikace. Na základě dostupných zdrojů a literatury práce popisuje současný stav problematiky. V práci jsou prezentovány simulační modely MEMS termoelektrických článků, které jsou ověřeny experimentálním testováním a hodnotami dostupnými od výrobce. Na základě metodiky model-besed design byly navrženy a vyrobeny tři demonstrátory. Jejich vlastnosti byly testovány v reálných podmínkách na letecké pohonné jednotce.
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Marengo, Giovanni. "The use of unidirectional carbon fibre rods in high loaded joints for a composite large civil aircraft wing structure." Thesis, Cranfield University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393700.
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Rahn, David. "Forcing and structure of the 22-25 June 2006 coastally trapped wind reversal using aircraft observations and numerical simulations." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1799961831&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Muller, Yannick. "Coupled thermomechanical fluid-structure interaction in the secondary air system of aircraft engines : contribution to an integrated design method." Valenciennes, 2009. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/94032a6b-3a17-4aaf-b07a-ce560f117b33.
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Dans un turboréacteur, le système d'air secondaire remplit de multiples fonctions. Les flux d'air secondaire contrôlent les températures des matériaux et l'expansion thermale des parties moteurs, en particulier les écartements des joints d'étanchéité. Pour s'assurer de la réalisation des diverses fonctions dès la phase de développement, les différentes propriétés du gaz doivent être correctement prédîtes. Actuellement, les calculs aérodynamiques, livrant les flux les températures et les pressions d'air, sont séparés des calculs thermiques, livrant les températures matériaux. Les interactions dont le traitement nécessite de nombreuses itérations sont ignorées. En effet, un changement de température matériau modifie l'expansion relative des parties moteurs, redéfinissant ainsi l'écartement des joints qui a son tour contrôle les débits d'air. La définition de l'écartement de joint influant de manière importante sur les pertes de charges, un fort effet de couplage est attendu. Le but de l'étude est de prendre en compte ces interactions au sein d'un nouvel outil combinant analyse du système d'air secondaire et calculs thermique et mécaniques. Une série de modules intégrés permet de considérer ces effets dans les cas stationnaires. Un réseau constitue de nodes représentant les chambres connectées par des éléments assimiles a des pertes de charges constitue la base du concept. Utilisant une formulation compatible avec la topologie Elément Finis, le réseau est imbrique dans le modèle Eléments Finis thermomécanique au sein d'un modèle unique et résolu grâce au logiciel CalculiX. Températures, pressions et débits sont calculés basé sur les températures et déformations matériau de l'itération précédente et servent de conditions limites au calcul thermomécanique dans l'itération suivanteIn jet engines, the secondary air system, or SAS, takes care of a variety of important functions. In particular, secondary air flows control material temperatures and thermal expansion of engine parts, especially seal clearances. To check the fulfilment of these functions in the engine design phase, gas properties, temperatures, pressures and mass flow rates, must be accurately predicted. Up to now, the aerodynamic calculations leading to mass-flow rates, fluid pressures and temperatures and the thermal calculations yielding material temperatures are performed separately. A lot of interactions are neglected, the treatment of which would require numerous time consuming iterations. Indeed, material temperature changes lead to a modification of the expansion of the interacting parts yielding significant modifications in the gaps which control mass-flow rates. Since gap width has an important influence on the pressure losses, the interaction between aerodynamic, thermal and solid mechanics solution to the problem is expected to be important. The present investigation aims at taking this interaction into account in a robust analysis tool, combining SAS, thermal and mechanical analysis. An integrated program suite has been created, which allows to calculate these effects steady state. The basic concept is a network consisting of nodes representing the chambers and connected by pressure loss elements. Using a finite-element-compatible formulation, the network is embedded in a thermo-mechanical finite element model of the engine within an unique model and solved using the free software finite element CalculiX. This is done in the form of a module in which the gas pressure temperature and mass-flow are calculated based on the structural temperature and deformation of the previous iteration and serve as boundary conditions to the thermo-mechanical model for the next iteration
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D'Ermilio, Jessica. "Laser shock peening treatment to control and moderate fatigue crack growth in aircraft structure based on residual stress engineering approach." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6865/.
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Laser Shock Peening (LSP) is a surface enhancement treatment which induces a significant layer of beneficial compressive residual stresses of up to several mm underneath the surface of metal components in order to improve the detrimental effects of the crack growth behavior rate in it.
The aim of this thesis is to predict the crack growth behavior in metallic specimens with one or more stripes which define the compressive residual stress area induced by the Laser Shock Peening treatment. The process was applied as crack retardation stripes perpendicular to the crack propagation direction with the object of slowing down the crack when approaching the peened stripes.
The finite element method has been applied to simulate the redistribution of stresses in a cracked model when it is subjected to a tension load and to a compressive residual stress field, and to evaluate the Stress Intensity Factor (SIF) in this condition.
Finally, the Afgrow software is used to predict the crack growth behavior of the component following the Laser Shock Peening treatment and to detect the improvement in the fatigue life comparing it to the baseline specimen.
An educational internship at the “Research & Technologies Germany – Hamburg” department of AIRBUS helped to achieve knowledge and experience to write this thesis. The main tasks of the thesis are the following:
•To up to date Literature Survey related to “Laser Shock Peening in Metallic Structures”
•To validate the FE model developed against experimental measurements at coupon level
•To develop design of crack growth slowdown in Centered Cracked Tension specimens based on residual stress engineering approach using laser peened strip transversal to the crack path
•To evaluate the Stress Intensity Factor values for Centered Cracked Tension specimens after the Laser Shock Peening treatment via Finite Element Analysis
•To predict the crack growth behavior in Centered Cracked Tension specimens using as input the SIF values evaluated with the FE simulations
•To validate the results by means of experimental tests
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Lemmens, Yves Claude Jean. "Modelling and analysis of engineering changes in complex systems." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/5071.
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Complex products are comprised of a large number of tightly integrated components, assemblies and systems resulting in extensive logical and physical interdependences between the constituent parts. Thus a change to one item of a system is highly likely to lead to a change to another item, which in turn can propagate further. The aim of this research therefore is to investigate dependency models that can be used to identify the impact and trace thepropagation of changes in different information domains, such as requirements, physical product architecture or organisation. Cont/d.
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Syamsudin, Hendri. "Development of an approach and tool to improve the conceptual design process of the wing box structure of low-subsonic transport aircraft." Thesis, Cranfield University, 2009. http://hdl.handle.net/1826/4418.
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To produce a better airframe design, it is imperative to investigate the problems of design and manufacturing integration early on at the conceptual design stage. A new design approach and support tool is required which will aid the designer in future product development. This is a particular necessity in the current context of increasing complexity and challenging economic situations.
The present work focuses on the development of a design approach and design aids for designing metallic wingbox structures of low-subsonic transport aircraft with small wing sweepback angles. Its aims are two-fold: to assist in producing alternative structural concepts, and to capture the effects of new materials and manufacturing processes on weight and cost. It will form the basis for selecting the structural concept at the early stage of the design process. The target users of this design approach and tools are relatively inexperienced structural designers and students.
The developed process and tools are quite general in their application as they use stand-alone modules which can be employed separately or jointly with existing techniques and tools used by industry, research centres and academia.
A comparison of the result from the developed analytical tools against a detailed study undertaken by an aircraft company on the original configuration was made. It showed stress analysis and sizing results that were within a 10% margin.
A case study was performed to investigate the reduction of Direct Operating Cost (DOC) of a turboprop transport aircraft by redesigning the wingbox structure. Weight reductions of wing box structure of 16% were achieved using new configurations and advanced metallic materials. The purchase price of the aircraft could also be reduced through use of cheaper labour and new manufacturing processes. These cost savings, if converted into DOC reductions, are only 0.36% of DOC due to fuel saving and 0.25% of DOC due to manufacturing cost reduction for the wingbox structure only.
It is obvious that the overall DOC reduction is the result of the total impact of relative DOC effects due to fuel cost saving, material prices, labour rates, and manufacturing process improvements. Within the range of the
calculated parameter values, the overall DOC reductions could be as much as 0.61% relative DOC. It appears that fuel prices, material cost and labour rates give greater impacts on DOC than high speed machining processes.
Due to the use of advanced aluminium, maintenance cost is also predicted to be less. It has better fatigue life and fracture toughness than the standard aluminium and therefore will increase the aircraft maintenance periods for inspection and repair due to slower crack damage growth. This cost saving will contribute in reducing the life cycle cost of the aircraft. In addition, the number of crack stoppers could be reduced, therefore minimising weight and manufacturing cost. These benefits however have not been analysed.
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Cilliers, M. E. "Investigation of an aeroelastic model for a generic wing structure." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80317.
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Thesis (MScEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Computational Aeroelasticity is a complex research field which combines structural and aerodynamic analyses to describe a vehicle in flight. This thesis investigates the feasibility of including such an analysis in the development of control systems for unmanned aerial vehicles within the Electronic Systems Laboratory at the Department of Electrical and Electronic Engineering at Stellenbosch University. This is done through the development of a structural analysis algorithm using the Finite Element Method, an aerodynamic algorithm for Prandtl’s Lifting Line Theory and experimental work. The experimental work was conducted at the Low-Speed Wind Tunnel at the Department of Mechanical and Mechatronic Engineering. The structural algorithm was applied to 20-noded hexahedral elements in a winglike structure. The wing was modelled as a cantilever beam, with a fixed and a free end. Natural frequencies and deflections were verified with the experimental model and commercial software. The aerodynamic algorithm was applied to a Clark-Y airfoil with a chord of 0:1m and a half-span of 0:5m. This profile was also used on the experimental model. Experimental data was captured using single axis accelerometers. All postprocessing of data is also discussed in this thesis. Results show good correlation between the structural algorithm and experimental data.
AFRIKAANSE OPSOMMING: Numeriese Aeroelastisiteit is ’n komplekse navorsingsveld waar ’n vlieënde voertuig deur ’n strukturele en ’n aerodinamiese analise beskryf word. Hierdie tesis ondersoek die toepaslikheid van hierdie tipe analise in die ontwerp van beheerstelsels vir onbemande voertuie binne die ESL groep van die Departement Elektriese en Elektroniese Ingenieurswese by Stellenbosch Universiteit. Die ondersoek bevat die ontwikkeling van ’n strukturele algoritme met die gebruik van die Eindige Element Methode, ’n aerodinamiese algoritme vir Prandtl se Heflynteorie en eksperimentele werk. Die eksperimentele werk is by die Department Meganiese en Megatroniese Ingensierswese toegepas in die Lae-Spoed Windtonnel. Die strukturele algoritme maak gebruik van ’n 20-nodus heksahedrale element om ’n vlerk-tipe struktuur op te bou. Die vlerk is vereenvouding na ’n kantelbalk met ’n vasgeklemde en ’n vrye ent. Natuurlike frekwensies en defleksies is met die eksperimentele werk en kommersiële sagteware geverifieer. Die aerodinamiese algoritme is op ’n Clark-Y profiel met 0:1m koord lengte en ’n halwe vlerk length van 0:5m geïmplementeer. Die profiel is ook in die eksperimentele model gebruik. Die eksperimentele data is met eendimensionele versnellingsmeters opgeneem. Al die verdere berekeninge wat op ekperimentele data gedoen is, word in die tesis beskryf. Resultate toon goeie korrelasie tussen die strukturele algoritme en die eksperimentele data.
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Blanc, Maximin. "Optimisation d’une structure de conversion DC/DC réversible pour application aéronautique de forte puissance." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT115.
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Le véhicule aérien a connu de nombreuses révolutions durant les dernières décennies afin d’être plus économe en énergie et plus respectueux de l’environnement. Dans cet objectif, l’électricité est apparue comme le vecteur énergétique le plus adapté associé aux sources conventionnelles d’énergie. C’est dans ce contexte que nos recherches se sont portées sur ce mode de transport qui va voir des bouleversements structurels importants et de plus en plus d’équipements électriques installés à bord. Ce travail de recherche s’intéresse à une brique de conversion DC/DC nécessaire au transfert d’énergie entre les bus HVDC et LVDC présents sur les avions actuels, pour cela nous avons étudié la structure et le contrôle de la topologie Dual Active Bridge qui apparaît comme le meilleur candidat pour atteindre les objectifs techniques, de rendement et compacité. Un dimensionnement ainsi que des résultats expérimentaux sont présentés pour valider nos choix avec un démonstrateur de 3,75kW. Des pistes de réflexions sont enfin proposées pour poursuivre et étendre certaine assertions vers une structure tri-ports pour l’interfaçage de multiples réseaux et moyen de stockage. L’originalité de ses travaux réside dans la volonté de concevoir un produit industrialisable dans le domaine de l’aéronautique en favorisant plusieurs ruptures technologiques jusqu’alors rédhibitoire chez les avionneursAvionics is intended to become more and more efficient in terms of energy saving thanks to increased efficiency of embedded system. Today, electricity is presented as the best energy vector compared to hydraulic or pneumatic. This is why current researches aim to focus on power electronic converters in order to meet the future electrical power demand in aircraft networks. This research project presents a DC/DC dual active bridge converter which is expected as the best candidate to meet the complex requirements of an aircraft environment, especially the high voltage dynamics. This persuaded us to study the structure and modulations which are explained and brought face to face with a 3,75kW demonstrator in order to validate the theoretical assumptions. Some food for thought is proposed to extend this work toward a three-port converter to interface multiple network as well as storage systems. The originality of this work is to build a new kind of active conversion system promoting break through technologies to prove it suits to aircraft specifications
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Horner, Michael S. "Determining the fine structure of the entrainment zone in cloud-topped boundary layers." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FHorner.pdf.
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Carlsson, Martin. "Design and Testing of Flexible Aircraft Structures." Doctoral thesis, KTH, Aeronautical and Vehicle Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3761.
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Methods for structural design, control, and testing offlexible aircraft structures are considered. Focus is onnonconventional aircraft con- figurations and control concepts.The interaction between analysis and testing is a central topicand all studies include validation testing and comparisonbetween computational and experimental results.
The first part of the thesis is concerned with the designand testing of an aeroelastic wind-tunnel model representing aBlended Wing Body (BWB) aircraft. The investigations show thata somewhat simplified wind-tunnel model design concept isuseful and efficient for the type of investigations considered.Also, the studies indicate that well established numericaltools are capable of predicting the aeroelastic behavior of theBWB aircraft with reasonable accuracy. Accurate prediction ofthe control surface aerodynamics is however found to bedifficult.
A new aerodynamic boundary element method for aeroelastictimedomain simulations and its experimental validation arepresented. The properties of the method are compared totraditional methods as well as to experimental results. Thestudy indicates that the method is capable of efficient andaccurate aeroelastic simulations.
Next, a method for tailoring a structure with respect to itsaeroelastic behavior is presented. The method is based onnumerical optimization techniques and developed for efficientdesign of aeroelastic wind-tunnel models with prescribed staticand dynamic aeroelastic properties. Experimental validationshows that the design method is useful in practice and that itprovides a more efficient handling of the dynamic aeroelasticproperties compared to previous methods.
Finally, the use of multiple control surfaces andaeroelastic effects for efficient roll maneuvering isconsidered. The idea is to design a controller that takesadvantage of the elasticity of the structure for performancebenefits. By use of optimization methods in combination with afairly simple control system, good maneuvering performance isobtained with minimal control effort. Validation testing usinga flexible wind-tunnel model and a real-time control systemshows that the control strategy is successful in practice.Keywords: aeroelasticity, active aeroelastic structures,aeroelastic tailoring, control, structural optimization,wind-tunnel testing.
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Fortunet, Charles. "Une méthode d'optimisation multicritère pour le Design For Manufacturing : application aux portes d'avion." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC048.
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Actuellement, le marché aéronautique est en constante augmentation. Pour faire face à cela, les avionneurs doivent se restructurer et revoir les processus de fabrication des pièces. En effet, il est nécessaire d’augmenter les cadences et réduire les prix tout en conservant les performances des pièces (poids et résistance mécanique). Cependant, ces trois objectifs sont contradictoires et un compromis est difficile à trouver. Ces travaux de thèse abordent cette problématique dans le cadre du CORAC. Ils proposent une manière originale d’optimiser une pièce de structure aéronautique qui vise à développer une nouvelle approche de la conception de pièces et de processus de fabrication pour tendre vers des solutions de compromis performantes. Pour ce faire, une méthodologie multicritère en trois étapes est proposée. D’abord, l’expertise industrielle est formalisée afin de formuler le problème mathématiquement. Ensuite, un algorithme génétique est utilisé afin de déterminer une population de solutions dont les performances sont placées sur un front de Pareto.Enfin, une étape de choix parmi la population finale prenant en compte le contexte industriel est mise en place. Cette méthodologie est appliquée à une porte d’avion moyen-courrier fabriquée par matriçage puis usinage. Dans ce cas, elle permet de choisir la solution la plus adaptée au contexte industriel parmi mille solutions de compromisNowadays, the aeronautical market grows constantly. To face this, aircraft industry has to restructure and the manufacturing processes must be revised. Indeed, production rate must increase and manufacturing cost decrease while keeping the performances of the parts (weight and mechanical resistance). These objectives are contradictory and compromises must be found. This thesis broaches this problematic in relation to the CORAC. A novel method to optimize an aeronautical structural part and its manufacturing process is developed to tend toward performing compromise solutions. To do so, a three steps multi-criteria method is proposed. First, the industrial expertise is formalized to mathematically express the problem. Then, a genetic algorithm is used to determine a population in which every solution is located on a single Pareto front. At least, a decision step is set up to find the best solution in the population considering the industrial environment of the part. This methodology is applied to an aircraft door manufactured by forging and machining. In this case, it allows choosing the solution that fit the most the industrial environment within a one thousand solutions’ population
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Freeman, Michael James. "The Integration of Iterative Convergent Photogrammetric Models and UAV View and Path Planning Algorithms into the Aerial Inspection Practices in Areas with Aerial Hazards." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8738.
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Small unmanned aerial vehicles (sUAV) can produce valuable data for inspections, topography, mapping, and 3D modeling of structures. Used by multiple industries, sUAV can help inspect and study geographic and structural sites. Typically, the sUAV and camera specifications require optimal conditions with known geography and fly pre-determined flight paths. However, if the environment changes, new undetectable aerial hazards may intersect new flight paths. This makes it difficult to construct autonomous flight path missions that are safe in post-hazard areas where the flight paths are based on previously built models or previously known terrain details. The goal of this research is to make it possible for an unskilled pilot to obtain high quality images at key angles which will facilitate the inspections of dangerous environments affected by natural disasters through the construction of accurate 3D models. An iterative process with converging variables can circumvent the current deficit in flying UAVs autonomously and make it possible for an unskilled pilot to gather high quality data for the construction of photogrammetric models. This can be achieved by gaining preliminary photogrammetric data, then creating new flight paths which consider new developments contained in the generated dense clouds. Initial flight paths are used to develop a coarse representation of the target area by aligning key tie points of the initial set of images. With each iteration, a 3D mesh is used to compute a new optimized view and flight path used for the data collection of a better-known location. These data are collected, the model updated, and a new flight path is computed until the model resolution meets the required heights or ground sample distances (GSD). This research uses basic UAVs and camera sensors to lower costs and reduce the need for specialized sensors or data analysis. The four basic stages followed in the study include: determination of required height reductions for comparison and convergent limitation, construction of real-time reconnaissance models, optimized view and flight paths with vertical and horizontal buffers constructed from previous models, and develop an autonomous process that combines the previous stages iteratively. This study advances the use of autonomous sUAV inspections by developing an iterative process of flying a sUAV to potentially detect and avoid buildings, trees, wires, and other hazards in an iterative manner with minimal pilot experience or human intervention; while optimally collecting the required images to generate geometric models of predetermined quality.
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Škatula, Václav. "Hangár." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265485.
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The final thesis is focused on a project of a load bearing structure of a aircraft maintenance hangar that has a rectangular ground plan 60,0x120,0 m and includes suspended mobile hoist of loading capacity 5,0t. The object is situated in the airport area of Ostrava Mošnov. The task provides two versions of design. The first version consists of eleven traverse joining beams witch are distanced twelve meters from each other. The second version consists of thirteen traverse joining beams witch are distanced ten meters from each other. The thesis focuses on the load pressure of the steel construction, the main emphasis being placed on the single structural components and assembling components. The calculation meet the standards of ČSN EN.
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Liu, Wei Lin. "Integrated and flexible ultrasonic transducers for structural health monitoring on aircraft structures." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97155.
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Fatigue crack initiating from fastener holes in aluminum plates is a typical damagefrequently found on modern aircraft structures. Requirements for life extension of agingaircraft fleets and reduced maintenance costs have been accelerating the developments ofstructural health monitoring (SHM) technologies. This thesis considers the active sensingapproach of SHM that involves the integrated ultrasonic transducer (IUT) and the flexibleultrasonic transducer (FUT). The main component of IUT and FUT was piezoelectriclead-zirconate-titanate composite films which were fabricated using the sol-gel spraytechnique. The crack growth monitoring capability of the IUT and FUT was successfullydemonstrated on aluminum plates with fatigue cracks. The artificial damages on analuminum test article representing aircraft structural complexity were also detected by theFUT array bonded on both planar and curved surfaces. Finally, the design and fabricationof miniature angle beam wedges having low spurious noise are presented. The fatiguecrack on an aluminum thin plate was detected using the FUT bonded onto such anglebeam wedges.Les fissures dues à la fatigue du métal initiées aux trous de fixation dans lesplaques d'aluminium sont des problèmes communs dans les avions modernes. De plus,l'utilisation d'avions de plus en plus âgés et le besoin de réduire leurs coûts d'entretien àaccélérer le développement de la technologie de la surveillance de la santé structurelle(SSS) de ces derniers. Ce mémoire considère l'approche active de la SSS en incorporantla capacité des capteurs intégrés ultrasonores (CIU) et des capteurs flexibles ultrasonores(CFU). L'ingrédient principal des CIU et CFU est des films à base de plomb-zirconatetitanatequi sont fabriqués à partir de la technique sol-gel. La capacité des CIU et CFU àsurveiller la croissance des fissures sur des plaques d'aluminium fissurées par fatigue futdémontrée avec succès. Les défauts artificiels mis dans des échantillons de plaquesd'aluminium représentant la complexité structurelle furent également détectés par unematrice de CFU collée sur des surfaces plane et courbe. Finalement, la conception et lafabrication de coins d'angles miniatures ayant comme caractéristiques de faibles bruitsparasites sont présentées. Les fissures par fatigue sur de minces plaques d'aluminiumfurent détectées en utilisant les CFU collés sur de tels coins.