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Projecte llegit

Títol: Estudio de viabilidad de una técnica innovadora de NDT para detección de grietas superficiales en materiales no ferromagnéticos

Estudiants que han llegit aquest projecte:

Director/a: ROJAS GREGORIO, JOSEP IGNASI

Departament: FIS

Títol: Estudio de viabilidad de una técnica innovadora de NDT para detección de grietas superficiales en materiales no ferromagnéticos

Data inici oferta: 23-03-2012     Data finalització oferta: 23-11-2012


Estudis d'assignació del projecte:
    Tipus: Individual
     
    Lloc de realització: EETAC
     
    Paraules clau:
    surface crack, magnetic particle, ferrofluid, aluminium alloy, composite, non-ferromagnetic material, NDT, NDE
     
    Descripció del contingut i pla d'activitats:
    This TFC is part of a research project about an innovative idea for developing a Non-Destructive Testing (NDT) technique to detect surface defects. The proposed technique is aimed at meeting the requirements of NDT end-users in the form of a significant reduction of inspection costs, as compared with the most commonly used techniques at present day. This goal is to be achieved specifically through the reduction of equipment costs and through the reduction of inspection time.

    In addition, the proposed NDT technique would feature suitability to wide range of aerospace NDT applications, which is an important asset. The method studied in this work would be applicable to any type of material except ferromagnetic materials. Namely, the technique would be valid to inspect components made of aluminum and composite materials like CFRP or GFRP.

    El plan de actividades del TFC consta de las siguientes etapas:

    1. Búsqueda de bibliografía y documentación relevante
    2. Realización de ensayos experimentales de la nueva técnica NDT
    3. Comparación de resultados teóricos y experimentales
    4. Discusión de los resultados y viabilidad de la técnica NDT
    5. Elaboración de la memoria
     
    Overview (resum en anglès):

    To improve safety and minimize the risk of accidents in the aviation industry, it is very important to know the status of the cracks and defects of the components of the structure of aircraft, such as the wing or the fuselage.

    In this work we studied a new Non-Destructive Testing (NDT) technique to detect surface cracks in non-ferromagnetic materials, based on the local magnetic field disturbance caused by the deposition and accumulation of a ferrofluid (liquid with a suspension of magnetic particles) on the surface crack. The aim of the study is to determine the feasibility and benefits of this new technique. In particular, it is intended to quantify the deviation of the magnetic field measured when the ferrofluid is introduced in the surface defect.

    For this purpose, we performed two different experiments, first with DC feeding a coil to excite the magnetic field of the ferrofluid and, after, with AC. In DC, the detection of the magnetic field of the ferrofluid has been studied in three different cases: 1) the ferrofluid has not been magnetized yet, 2) the ferrofluid is being magnetized and 3) the ferrofluid has already been magnetized. Then, we compared these three different versions, determining the advantages and disadvantages of each one, and comparing the variations produced by the ferrofluid when it is introduced in the surface crack. We concluded that the most interesting version of the technique (i.e. the version which produces the major deviation on the magnetic field when the ferrofluid is introduced in the crack) is the one in which the ferrofluid is being magnetized at the same time that the surface is being inspected.

    In AC, detection of the surface defects was studied based on the measurement of the magnetic field as a function of frequency for the cases with and without ferrofluid. Fitting the experimental results to the equation that describes the behaviour of a forced oscillator, we determined the optimum parameter of this equation to be used to detect surface cracks: the position of the resonance peak of the magnetic field response in frequency.

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