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An artificial Neural Network (ANN) system has been developed that can analyse aircraft flight data to provide a reconstruction of the aerodynamic loads experienced by the aircraft during flight, including manoeuvre, buffet and distributed loading. For this research data was taken from the International Follow-On Structural Test Project (IFOSTP) F/A-18 fatigue test conducted by the Royal Australian Air Force and Canadian Forces. This fatigue test involved the simultaneous application of both manouevre and buffet loads using airbag actuators and shakers. The applied loads were representative of the actual loads experienced by an FA/18 during flight tests. Following an evaluation of different ANN types an Ellman network with three linear layers was selected. The Elman back-propagation network was tested with various parameters and structures. The network was trained using the MATLAB 'traingdx' function with is a gradient descent with momentum and adaptive learning rate back-propagation algorithm. The ANN was able to provide a good approximation of the actual manoeuvre or buffet loads at the location where the training loads data were recorded even for input values which differ from the training input values. In further tests the ability to estimate distributed loading at locations not included in the training data was also demonstrated. The ANN was then modified to incorporate various methods for the calculation and prediction of output error and reliability Used in combination and in appropriate circumstances, the addition of these capabilities significantly increase the reliability, accuracy and therefore usefulness of the ANN system's ability to estimate aircraft loading.To demonstrate the ANN system's usefulness as a fatigue monitoring tool it was combined with a formulae for crack growth analysis. Results inficate the ANN system may be a useful fatigue monitoring tool enabling real time monitoring of aircraft critical components using existing strain gauge sensors.

<p>External stores mounted on aircraft generate loads which need to be estimated before first takeoff. These loads can be measured in a wind tunnel but since the possible store configurations are basically endless, testing them all is neither economically feasible nor time efficient. Thus, scaling based on geometrical similarity is used. This can, however, be a crude method. Stores with similar geometrical properties can still behave in different ways due to aerodynamic interference caused by adjacent surfaces.</p><p>To improve the scaling performance, this work focuses on investigating two CFD codes, ADAPDT and Edge. The CFD simulations are used to derive the difference in aerodynamic coefficients, or the Δ-effect, between a reference store and the new untested store. The Δ-effect is then applied to an existing wind tunnel measurement of the reference store, yielding an estimation of the aerodynamic properties for the new store.</p><p>The results show that ADAPDT, using a coarse geometry representation, has large difficulties predicting the new store properties, even for a very simple store configuration on the aircraft. Therefore it is not suited to use as a scaling tool in its present condition. Edge on the other hand uses a more precise geometry representation and proves to deliver good estimations of the new store load behavior. Results are well balanced and mainly conservative. Some further work is needed to verify the performance but Edge is the recommended tool for scaling.</p><p> </p>

External stores mounted on aircraft generate loads which need to be estimated before first takeoff. These loads can be measured in a wind tunnel but since the possible store configurations are basically endless, testing them all is neither economically feasible nor time efficient. Thus, scaling based on geometrical similarity is used. This can, however, be a crude method. Stores with similar geometrical properties can still behave in different ways due to aerodynamic interference caused by adjacent surfaces. To improve the scaling performance, this work focuses on investigating two CFD codes, ADAPDT and Edge. The CFD simulations are used to derive the difference in aerodynamic coefficients, or the Δ-effect, between a reference store and the new untested store. The Δ-effect is then applied to an existing wind tunnel measurement of the reference store, yielding an estimation of the aerodynamic properties for the new store. The results show that ADAPDT, using a coarse geometry representation, has large difficulties predicting the new store properties, even for a very simple store configuration on the aircraft. Therefore it is not suited to use as a scaling tool in its present condition. Edge on the other hand uses a more precise geometry representation and proves to deliver good estimations of the new store load behavior. Results are well balanced and mainly conservative. Some further work is needed to verify the performance but Edge is the recommended tool for scaling.

This master thesis focuses on designing of an external six-component balance. This universal concept would provide access of results from different models of wings, aircraft and automobiles with relatively small scales. This work also includes theoretical background needed in aerodynamic testing, analysis of 1D beam element model of scale and explanation of components used in scale. Lastly methods of calibration and measurement in aerodynamic tunnel are described, which can be adopted for this design to achieve the adequate level of accuracy.

Loads determination for external stores on fighter aircraft is an important task for manufacturers in ensuring the safe operation of their aircraft. Due to the large number of possible store combinations, wind tunnel tests – the primary approach to obtaining loads data – cannot be performed for all configurations. Instead, supplementary techniques to estimating loads are necessary. One approach is to use information from another store and adapt it, using so-called scaling methods, to the non-tested store. In this thesis, a scaling method combining the results of computational fluid dynamics (CFD) simulations, for both a non-tested and a reference store, with existing wind tunnel data for the reference store, is thoroughly examined for a number of different stores, angles of attack, sideslip angles and Mach numbers. The performance of the proposed scaling method is assessed in relation to currently used scaling methods, using non-parametric and multivariate statistics. The results show no definitive improvement in performance for the proposed scaling method over the current methods. Although the proposed method is slightly more conservative, considerable variability in the estimates and an increased time consumption for scaling leads the author to advise against using the proposed method for scaling aerodynamic loads on external stores. / Lastbestämning för yttre utrustning på stridsflygplan är en viktig uppgift för att tillverkarna ska kunna garantera säkerheten för sina flygplan. Då antalet möjliga utrustningskombinationer är mycket stort, kan inte vindtunneltester – normalt den främsta metoden för att erhålla lastdata – utföras för alla konfigurationer. Således behövs kompletterande metoder för att skatta laster. Ett alternativ är att använda data från en annan utrustning och anpassa den, med hjälp av så kallade skalningsmetoder, till den icke-testade utrustningen. I detta examensarbete behandlas en skalningsmetod som kombinerar resultaten från numeriska strömningsberäkningar – så kallade CFD-simuleringar – för både en testad och en icke-testad utrustning med befintliga vindtunneldata för den testade utrustningen. Metoden undersöks grundligt för ett antal olika utrustningar, anfallsvinklar, sidanblåsningsvinklar och Machtal. Prestandan hos den föreslagna skalningsmetoden utvärderas i relation till nu använda skalningsmetoder, baserat på icke-parametrisk och multivariat statistik. Resultaten visar inga definitiva förbättringar av prestanda för den föreslagna skalningsmetoden jämfört med de nuvarande metoderna. Även om den föreslagna metoden är något mer konservativ, så föranleder betydande variationer i skattningar och en ökad tidsåtgång för skalning författaren att avråda från att använda den föreslagna metoden för skalning av luftlaster på yttre utrustning.

Made available in DSpace on 2014-12-17T14:58:12Z (GMT). No. of bitstreams: 1 ElsonANM.pdf: 918866 bytes, checksum: 54ffb16de332a5a9c76c3afd577bcea1 (MD5) Previous issue date: 2005-09-16 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The study of aerodynamic loading variations has many engineering applications, including helicopter rotor blades, wind turbines and turbo machinery. This work uses a Vortex Method to make a lagrangian description of the a twodimensional airfoil/ incident wake vortex interaction. The flow is incompressible, newtonian, homogeneus and the Reynolds Number is 5x105 .The airfoil is a NACA 0018 placed a angle of attack of the 0? and 5?simulates with the Painel Method with a constant density vorticity panels and a generation poit is near the painel. The protector layer is created does not permit vortex inside the body. The vortex Lamb convection is realized with the Euler Method (first order) and Adans-Bashforth (second order). The Random Walk Method is used to simulate the diffusion. The circular wake has 366 vortex all over positive or negative vorticity located at different heights with respect to the airfoil chord. The Lift was calculated based in the algorithm created by Ricci (2002). This simulation uses a ready algorithm vatidated with single body does not have a incident wake. The results are compared with a experimental work The comparasion concludes that the experimental results has a good agrement with this papper / Este estudo simula numericamente, atrav?s do M?todo de V?rtices, a intera??o entre uma nuvem de circula??o incidente e um aerof?lio NACA 0018 posicionado com ?ngulos de ataque de 0? e 5?. O n?mero de Reynolds utilizado ? de 5x105 e o escoamento ? considerado incompress?vel. Devido a complexidade do fen?meno de geometria tridimensional, apenas uma se??o do aerof?lio ? simulada transformando o trabalho em bidimensional. Utiliza-se o M?todo dos Pain?is com vorticidades distribu?das para simular o corpo e o ponto de gera??o de vorticidade ? deslocado da superf?cie do painel. Uma camada protetora ? criada para evitar a entrada de v?rtices no corpo. A convec??o dos v?rtices de Lamb presentes ? realizada atrav?s dos esquemas de Euler (1?ordem) e de Adams-Bashforth (2?ordem). A difus?o utiliza o M?todo do Avan?o Rand?mico. As cargas de sustenta??o s?o calculadas atrav?s de um algoritmo desenvolvido por Ricci (2002). A nuvem utilizada tem 366 v?rtices com circula??o de +0.001375692 ou -0.001375692 formando um c?rculo de raio 0,2. A simula??o utilizou um algoritmo existente que foi modificado para o problema em quest?o. Validado atrav?s da simula??o do perfil sem a presen?a da nuvem. Os resultados encontrados mostram uma boa concord?ncia com os encontrados em trabalhos experimentais