Recursos de colección

Archivo Digital UPM (118.711 recursos)

This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.

Materia = Aeronáutica

Mostrando recursos 1 - 20 de 78

  1. Vibration-based method for damage detection at welded beams and rods

    Garcia-fogeda Nuñez, Pablo; Salgado Sanchez, P.; Lopez Negro, P.
    In this work, a vibration-based method for damage detection at welded beams and rods is presented. The model of the structural element includes the effect of the added inertia due to the welding process. Two methods of solution, analytically and by means of the Finite Element Method (FEM), are presented. From the results obtained it can be asseverated that the method can be a useful tool to detect degradation of welded structures. In contrast to other existing methods for cracks detection, it is shown that several frequencies have to be taken into consideration to determine the wear characteristics of the welded elements,...

  2. Material elastic waves test exploitation in benefit of composite structure health monitoring

    Lozano Martín, Ángel; Marcos García, Rodrigo; García Alonso, Jaime; Fernández López, Antonio; Iglesias, Manuel; Gümes Gordo, Alfredo
    Composite structures suffer from an unsatisfactory behavior to impact damage, which involves conservative designs, high maintenance and repair costs in order to prevent premature failures. These time-consuming operations can be optimized by SHM techniques. In the case study presented, a 48 PZT sensing network has been integrated within two similar composite panels, representative of real aeronautical structures and multi-functional skin concept, approximate size 600mm width and 1650mm length, with substrate made of carbon fiber and thermoset matrix, with two integrated hat stiffeners along the longitudinal direction, and transverse C metallic stiffeners. This sensors network may be used by both active...

  3. Free-edge delamination location and growth montoring with an embedded distributed fiber optic network

    Díaz-Maroto, Patricia; Fernández López, Antonio; Larrañaga, Beatriz; Güemes Gordo, Jesús Alfredo
    Delamination is the most characteristic damage found in composite materials. Low velocity impacts may lead to delamination onset, likely to occur during manufacturing processes or in operating service life.Furthermore, areas near the free-edge of the structures,as well as ply drop off and integrated reinforcements have demonstrate a high vulnerability to impacts. This paper focuses on the delamination detection based on an embedded or fixed fiber optic network in a composite laminate. The sensor network uses the Rayleigh scattering through an Optical Backscatter Reflectometer (OBR)that it obtains a continuous strain monitoring on a bare opical fiber. For this purpose, several optical...

  4. Environmental effect compensation for damage detection in structures using artificial neural networks and chirplet transform

    García Alonso, Jaime; Fernández López, Antonio; González Requena, Ignacio; Gümes Gordo, Alfredo
    One of the open problems to implement Structural Health Monitoring techni ques based on guided waves in real structures is the interference of the environme ntal effects in the damage diagnosis problem. This paper deals with the compensation of one of the envir onmental effects, the temperature. It is well known that the guided wave form is modified by temperature variation and causes errors in damage diagnosis. This happens because the waveform has an influence due to temperature changes of the same order tan he damage presence, which makes difficult to separate both effects in order to avoid false positives....

  5. Numerical study of effect of wall heating conditions on heat transfer performance of internal cooling channel

    Wang, Zhi; Corral Garcia, Roque
    This paper investigates the impacts of wall heating conditions on heat transfer performace for a rotating channel with one side smooth and one side roughened by 45 degree inclined ribs. Previous experimental and numerical studies for only ribbed wall heated case showed that rotation has significantly negative impact on heat transfer performance. In order to investigate this uncommon behaviour, RANS simulations were conducted under three different wall heating conditions in present study: ribbed wall heated, all walls heated and adiabatic conditions. Numerical results show that the uneven wall heating condtions has negligible impact on stationary case, however, it has a...

  6. Effect of uneven wall heating conditions under different buoyancy numbers for a one side rib-roughened rotating channel

    Wang, Zhi; Corral Garcia, Roque
    Abstract This paper investigates the impacts of uneven wall heating conditions under different Buoyancy numbers on flow field and heat transfer performance of a rotating channel with one side smooth and one side roughened by 45 degree inclined ribs. Parametric RANS simulations were conducted under two different wall heating conditions: only ribbed wall heated, as in experiment setup, and all walls heated, under three different Buoyancy numbers. Results are compared, when available, with experimental results. Abstract Numerical results show that uneven wall heating has only a minor impact on non-rotating cases and very low buoyancy rotating cases. However, it has...

  7. The adaptation of sustainable biojet fuels and its effect on aircraft engine maintenance

    Noh, H. Mohd; Alonso Rodrigo, Gustavo; Rahman, N. A. Abdul
    Aviation industries are looking into several resources for renewable and sustainable energy. Among those attention is focused in biojet fuel. This paper engages the issue of biojet fuel emissions that increase the environmental concern in the air transport sector. The paper presents the use of biojet fuel and its effect on aircraft engine maintenance through preliminary data collections, and a review of its development process in operations for time and goal. As conclusion, airlines management needs to adapt and adopt the transition to alternative fuels, especially given the global biofuel trend emerging due to the authority approval.

  8. Mixed CFD-1D wind turbine diffuser design optimization

    Sorribes Palmer, Felix; Sanz Andres, Angel Pedro; Ayuso Moreno, Luis Manuel; Sant Palma, Rodolfo; Franchini Longhi, Sebastian Nicolas
    A method to design a diffuser augmented wind turbine (DAWT) is proposed, using as a guiding point the optimal pressure drop at the turbine. The use of concepts and expressions derived from a 1D analytic model helped to reduce the number of computational fluid dynamics simulations needed to find the optimal configuration. The proposed configuration can extract energy from the flow with the same efficiency as the state-of-the-art shrouded wind turbine (SWT) configurations but generating a significantly smaller wake, which makes this configuration a good candidate for wind farms or tidal applications. Furthermore, as a product of the 1D model,...

  9. Drag-shield drop tower residual acceleration optimisation

    Figueroa, Antonio; Sorribes Palmer, Félix; Fernández de Pierola, M.; Durán, J.
    Among the forces that appear in drop towers for microgravity experiments, aerodynamic drag plays a crucial role in the residual acceleration. Buoyancy can also be critical, especially at the first instances of the drop when the low speed of the experimental platform makes the aerodynamic drag small compared with buoyancy. In this paper the perturbation method is used to formulate an analytical model which has been validated experimentally. The experimental test was conduced by undergraduate students of aerospace engineering at the Institute of Microgravity ‘Ignacio Da Riva’ of the Technical University of Madrid (IDR/UPM) microgravity tower. The test helped students to understand...

  10. Capturing yield surface evolution with a multilinear anisotropic kinematic hardening model

    Zhang, Meijuan; Benítez, José María; Montans Leal, Francisco Javier
    Many authors have observed experimentally that the macroscopic yield surface changes substantially its shape during plastic flow, specially in metals which suffer significant work hardening. The evolution is frequently characterized by a corner effect in the stress direction of loading, and a flatter shape in the opposite direction. In order to incorporate this effect many constitutive models for yield surface evolution have been proposed in the literature. In this work we perform some numerical predictions for experiments similar to the ones performed in the literature using a multilayer kinematic hardening model which employs the associative Prager’s translation rule. Using this...

  11. Light-trapping in photon enhanced thermionic emitters

    Buencuerpo, J.; Llorens, J.M.; Zilio, Pierfrancesco; Raja, Waseem; Cunha, Joao; Alabastri, Alessandro; Zaccaria, Remo Proietti; Martí Vega, Antonio; Versloot, T.
    A series of photonic crystal structures are optimized for a photon enhanced thermionic emitter. With realistic parameter values to describe a p-type GaAs device we find an efficiency above 10%. The light-trapping structures increases the performance by 2% over an optimal bilayer anti-reflective coating. We find a device efficiency very close to the case of a Lambertian absorber, but below its maximum performance. To prevent an efficiency below 10% the vacuum gap must be dimensioned according to the concentration factor of the solar irradiance.

  12. Numerical simulation of pararotor dynamics: Effect of mass displacement from blade plane

    Piechocki, Joaquín; Nadal Mora, Vicente; Sanz Andres, Angel Pedro
    The pararotor is a biology-inspired decelerator device based on the autorotation of a rotary wing, whose main purpose is to guide a load descent into a certain planetary atmosphere. This paper focuses on a practical approach to the general dynamic stability of a pararotor whose center of mass is displaced from the blade plane. The numerical simulation tool developed is based upon the motion equations of pararotor flight, utilizing a number of simplifying hypotheses that allow the most influencing factors on flight behavior to be determined. Several simulated cases are analyzed to study the effect of different parameters associated with...

  13. Characterisation of cross-flow above a railway bridge equipped with solid windbreaks

    Avila Sanchez, Sergio; Lopez Garcia, Oscar; Cuerva Tejero, Alvaro; Meseguer Ruiz, J.
    The flow field above a two dimensional model of a railway bridge equipped with solid windbreaks is analysed in a wind tunnel. Particle image velocimetry (PIV) is used to measure the flow velocity in planes perpendicular to the bridge span. The mean velocity components, the two-component turbulent kinetic energy, the turbulence intensities of the velocity fluctuation components and the Reynolds shear stress above the bridge deck are presented. The flow patterns based on the streamlines of the average flow field are analysed. The inclusion of a windbreak produces a separation bubble, that is locked to the bridge deck due to...

  14. Joule effect self-heating of epoxy composites reinforced with graphitic nanofillers

    Gonzalez Prolongo, Margarita; Del Rosario, G.; Prolongo, S. G.; Moriche, R.; Jimenez-suarez, A.; Urena, A.
    Self-heating of conductive nanofilled resins due to the Joule effect is interesting for numerous applications, including computing, self-reparation, self-post-curing treatment of resins, fabrication of adhesive joints, de-icing coatings and so on. In this work, we study the effect of the nature and amount of graphitic nanofiller on the self-heating of epoxy composites. The addition of graphitic nanofillers induced an increase in the thermal conductivity of the epoxy resins, directly proportional to the nanofiller content. Percolation was not observed because of the heat transport through phonons. In contrast, the electrical conductivity curves present a clear percolation threshold, due to the necessity...

  15. Domain Reduction Strategy for Stability Analysis of a NACA0012 airfoil

    Sanvido, Silvia; Abruzzese, Gennaro; Vicente Buendia, Javier de; Valero Sánchez, Eusebio
    A new reduction domain strategy is applied in the framework of stability analysis for industrial applications. The aim of this work is to investigate if the geometrical approach proposed could be used as alternative or in combination with the numerical techniques that are currently employed for alleviating the prohibitive computational costs associated to the study of the stability of complex aerodynamic ows.Global linear stability analysis has been applied to a NACA0012 airfoil to study the transient bu�et phenomenon. The leading disturbance associated to bu�eting remains located in a inner región of the computational domain, making this problem a perfect test case for...

  16. A revision of the flutter margin method to predict in real-time the limit cycle oscillations onset speed with structural freeplay present in the plunge axis

    Casado Corpas, José; Sanz Lobera, Alfredo; González Requena, Ignacio; Sevilla, L.
    Computational fluid dynamic and order reducing methods have been extensively applied to predict the flutter onset speed of several types of aircrafts. However, the accuracy required by certification standards still ascribes flight testing as the only method available that safely validates the flight envelope of an aircraft. In particular, free-flutter conditions must be demonstrated in the target flight envelope, and several methods have been developed to determine the flutter onset speed in real-time when expanding the envelope during flight testing. Among the methods, the damping versus velocity technique combined with a flutter margin implementation remains the most common technique used for...

  17. Computationally efficient simulation of unsteady aerodynamics using POD on the fly

    Moreno Ramos, Ruben; Vega de Prada, José Manuel; Varas Merida, Fernando
    Modern industrial aircraft design requires a large amount of sufficiently accurate aerodynamic and aeroelastic simulations. Current computational fluid dynamics (CFD) solvers with aeroelastic capabilities, such as the NASA URANS unstructured solver FUN3D, require very large computational resources. Since a very large amount of simulation is necessary, the CFD cost is just unaffordable in an industrial production environment and must be significantly reduced. Thus, a more inexpensive, yet sufficiently precise solver is strongly needed. An opportunity to approach this goal could follow some recent results (Terragni and Vega 2014 SIAM J. Appl. Dyn. Syst. 13 330–65; Rapun et al 2015 Int....

  18. Diseño de almacén para el lanzamiento de un nuevo producto aeronáutico

    Ayerdi Tornero, Ignacio
    El objetivo de este Proyecto es el análisis y la consecuente definición de todos los aspectos de la Gestión de Almacenes necesarios para poner en marcha un nuevo producto en el entorno de una empresa fabricante de productos aeronáuticos en su sede de Madrid. Este nuevo producto engloba una serie de subconjuntos que, posteriormente, se ensamblarán en otro centro productivo para constituir un nuevo modelo de avión comercial. De cara al desarrollo de un nuevo modelo de avión, la empresa maneja una estimación de referencia de 7000 millones de euros, en base a la experiencia adquirida en modelos anteriores. Sin embargo, históricamente se pueden encontrar casos en...

  19. Strain monitoring on a composite aircraft cabin with fiber optic sensors

    Díaz-Maroto, Patricia; Fernández López, Antonio; Fernández, Rosario; Gutierrez, Nicolás; Lasagni, Fernando; Güemes Gordo, Jesús Alfredo
    An integral composite aircraft cabin had been instrumented with two different technologies: distributed fiber optic sensors (DFOSs) and Fiber Bragg Gratings (FBGs). This structural test aims at strain field monitoring in any part of structure when cabin pressurization is applied in order to simulate flight conditions. The Distributed fiber optic network used is based on Rayleigh scatter ing using an Optical Backscatter Reflectometer (OBR). The OBR provides a large number of strain sensor s with high spatial and strain accuracy with a plain optical fiber. DFOSs prove to be the most suitable technology for this test due to their capability...

  20. Finding a causal method for the prediction and assessment of safety performance in an Air Traffic Management Service = Establecimiento de un método causal para la predicción y medición de prestaciones de seguridad operacional de un Servicio de Gestión de Tráfico Aéreo

    Barragán Montes, Ana del Rocío
    El rendimiento de un espacio aéreo en términos de seguridad operacional debería ser medido de manera preventiva tal y como es recomendado por la OACI. La búsqueda de métricas precursoras de prestaciones de seguridad es un campo en pleno auge. Los factores que pueden dar una medida de la seguridad pueden ser varios. Actualmente se tienen en cuenta los eventos de seguridad, entendiendo como tales: §los incidentes o pérdidas de la separación mínima establecida, reportados por los actores que intervienen en la operación: pilotos y controladores del espacio aéreo; §los accidentes. De esta manera, la seguridad se mide en base...

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