Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 18 of 18 results
  • Detection of Failure Mechanisms of Tool Steels by means of Acoustic Emission Technique

     Martinez González, Eva
    Defense's date: 2014-01-30
    Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract  Share Reference managers Reference managers Open in new window

    Aquesta tesi es centra en calibrar la tècnica d'emissió acústica (EA) per detectar i identificar mecanismes de dany en acersper eines. El procediment de mesura de l¿EA s'ha desenvolupat i calibrat per a dos assajos mecànics: assaig de flexió iassaig d¿indentació esfèrica.A l¿assaig de flexió es generen esquerdes a la superfície de la proveta degudes a la tensió de tracció màxima. El danys'inicia amb la nucleació d'esquerdes (trencament de carburs i deformació plàstica local) i després, les esquerdes espropaguen a través de la matriu metàl¿lica seguint els carburs trencats. La monitorització de l¿assaig amb EA, permetdetectar i identificar cada etapa de la fractura: el trencament de carburs i plastificació (nucleació), creixement de l¿esquerda através de la matriu d¿acer i la fallada catastròfica final de la mostra.L¿assaig d' indentació esfèrica permeten la creació d'una distribució de tensions en la part afectada de la mostra méscomplexa. Amb l¿ aplicació de càrregues baixes, es genera un camp de tensions en el rang elàstic sota l¿indentador esfèric.Durant els assajos, es va detectar activitat d'EA en aquest rang elàstic, i aquests senyals es relacionen amb la ruptura decarburs situats a la zona d'esforç tallant màxim. Una característica important d'aquest assaig és que la ruptura de carburs esporta a terme sense deformació plàstica, i per tant els senyals de dany es van identificar clarament amb el trencament decarburs.En ambdós assajos, el trencament dels carburs va ser confirmat per mitjà de la EA com causa de la nucleació d'esquerdesen acers per a eines. L¿EA va fer possible identificar el trencament de carburs i la propagació d'esquerdes a través de lamatriu metàl¿lica i predir la fractura final de la mostra en els assajos de flexió. Aquesta tesi proposa una nova configuracióde filtratge en assajos de fractura per eliminar senyals espúries a causa del dany provocat pel contacte entre la mostra i elssuports de la màquina, així com una metodologia per a l¿identificació de mecanismes de dany en mostres de mida petitasobre la base de certes característiques de la forma d'ona dels senyals d¿EA. Des del punt de vista de la recerca dematerials, l'acoblament d¿EA amb la configuració que es proposa en cada assaig millora significativament els resultatsobtinguts dels assajos, ja que permet identificar l'evolució del dany durant el cicle de càrrega. Els resultats experimentalsobtinguts avalen el possible ús de l¿EA en el manteniment preventiu d¿eines de conformat a la indústria

  • Filtering of acoustic emission signals for the accurate identification of fracture mechanisms in bending tests

     Martinez González, Eva; Picas Anfruns, Ingrid; Romeu Garbi, Jordi; Casellas, Daniel
    Materials transactions
    Date of publication: 2013
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    In this manuscript, acoustic emission (AE) analysis is used to identify the fracture mechanisms that take place during a three-point bending test of steel specimens. However, an important source of AE was detected and related to the deformation of the supports and the surface of the steel specimen in contact. This source creates AE signals that are very high in number and amplitude, and prevent determining accurately the onset stress for fracture mechanisms in specimens. A signal filtering is proposed based on the properties of the initial part of the recorded AE waveform, combined with a linear localization. The filtering successfully allows the AE signals to be classified according to their source as background noise, damage due to contact of the specimen surface to the supports and fracture mechanisms occurring in the specimen microstructure as a result of the bending test. The aforementioned filter has been successfully applied in case of a cold work tool steel DIN 1.2379 to determine accurately the stress level at which the first damaging mechanisms start to occur in the microstructure in situ during the three-point bending test. Filtered AE signal results indicating damage in the microstructure have been corroborated by inspection of the specimen's surface in a Confocal Microscope. In default of using the proposed filter, unfiltered signals have been estimated to lead to an overestimation of critical stresses of about 20%, what is undesirable for most applications. © 2013 The Japan Institute of Metals and Materials.

  • Análisis del accidente de "el péndulo" en el parque de atracciones Tibidabo de Barcelona

     Carretero Alfaro, David; Sanchez Molina, David; Martinez González, Eva; Velazquez Ameijide, Juan; Arregui Dalmases, Carlos
    Dyna
    Date of publication: 2013-06-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    An analysis of the possible causes of the collapse of an attraction (El Péndulo) located in the amusement park of Tibidabo (Barcelona) has been performed. This analysis corroborates some hypotheses asserted by Professional association of Industrial Engineers of Catalonia (COEIC) by numerical computations. The accident caused a fatality and additional injured people. This attraction was opened in August of 2006, that indeed, it lasted for 4 years. In the analysis carried out, it is analyzed in detail the most probable hypothesis that could have happened focusing the causes of the collapse on the preloaded screws provided to the lower base of el Péndulo and the presence of corrosion on the screws. Publicly known data have been used for an accurate reconstruction of the geometry of el Péndulo. This is used for kinematical and dynamical computations in detail. These suggest to discard some possible failure causes, and they point to corrosion and tightening torque as factors involved in the collapse.

  • Micro-mechanical damage in tool steels analyzed by acoustic emission technique

     Picas, Ingrid; Martinez González, Eva; Casellas, Daniel; Romeu Garbi, Jordi
    Journal of acoustic emission
    Date of publication: 2012-12-30
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The carbides in tool steels act as hard particles and dictate the wear resistance. The origin of failure of these steels is mostly related with the carbide cracking, as a nucleation site of final cracks. This paper shows the acoustic emission (AE) signals related with the nucleation (carbide cracking) and the crack growth (in the metallic matrix) during a monotonic bending test of a tool steel obtained by ingot metallurgy routes (DIN 1.2379). The paper presents a relationship between the frequency spectrum of AE signals obtained and the microscopic images during the test.

  • Estudio micro-mecánico de daño en aceros para herramientas mediante la técnica de la emisión acústica

     Martinez González, Eva; Picas, Ingrid; Casellas, Daniel; Romeu Garbi, Jordi
    Revista de la Asociación Española de Ensayos No Destructivos
    Date of publication: 2012-09-01
    Journal article

     Share Reference managers Reference managers Open in new window

  • Analysis of fracture resistance of tool steels by means of acoustic emission

     Martinez González, Eva; Picas Anfruns, Ingrid; Casellas Padro, Daniel; Romeu Garbi, Jordi
    The e-journal and exhibition of non-destructive testing
    Date of publication: 2012-02-01
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Implementación de un proyecto horizontal integrador en la asignatura de Tecnología Mecánica

     Travieso Rodríguez, José Antonio; Martinez González, Eva
    Congreso Universitario de Innovación Educativa en las Enseñanzas Técnicas
    Presentation's date: 2011-10-06
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Application of acoustic emission technique (EA) for diagnostics of different types of materials and structures  Open access

     Martinez González, Eva; Gallego Molina, Antolino; Infantes Vázquez, Cristobal; Benavent Climent, Amadeo; Morillas Romero, Leandro; Martínez Jequier, José; Juanes, Javier; Valea Pérez, Ángel
    Congreso Español de Ensayos No Destructivos
    Presentation's date: 2011-06-15
    Presentation of work at congresses

    Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

  • Aplicación de la Emisión Acústica (EA) al estudio del comportamiento micro-mecánico de los AHSS

     Martinez González, Eva; Romeu Garbi, Jordi; Picas Anfruns, Ingrid; Casellas Padro, Daniel
    Congreso Nacional de Ingeniería Mecánica
    Presentation's date: 2010-11-04
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Analysis of fracture resistance of tool steels by means of acoustic emission.  Open access

     Martinez González, Eva; Picas Anfruns, Ingrid; Casellas Padro, Daniel; Romeu Garbi, Jordi
    European Conference on Acoustic Emission
    Presentation's date: 2010-09-09
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The usage of advanced high strength steels (AHSS) in structural automotive components has been broadened in the past few years to satisfy the strict specifications of the automotive industry. Besides showing excellent strength to weight rations, AHSS have several limitations due to the high loads required in cold forming and cutting tools, which decrease considerably the tooling performances. Therefore, these important forces of impact provoke unforeseen breakage of the dies. The aim of this research is to study the micromechanical behaviour and fracture mechanisms (nucleation and crack propagation) during fracture of tool steels using the acoustic emission (EA) technique. To do that, bending testing specimens of different tool steels were monitored in order to establish a relationship between AE signals and their mechanical behavior (carbide breakage, cracks emanating from them and crack propagation through the metallic matrix).

  • Analysis of fracture resistance of tool steels by means of acoustic emission

     Martinez González, Eva; Picas Anfruns, Ingrid; Casellas Padro, Daniel; Romeu Garbi, Jordi
    Journal of acoustic emission
    Date of publication: 2010-12-10
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The automotive manufacturers currently use advanced high-strength steels (AHSS) to produce lightweight vehicles with increased safety performance. While showing excellent strengthto-weight ratios, AHSS have several limitations due to the high loads required in cold forming and cutting processes, which lead to accelerated wear and premature fracture of tools. Thus, new tool materials with improved mechanical behavior ought to be developed with regard to the tool failure mechanisms. The aim of this work is to shed light on the fracture mechanisms acting in tools (i.e. crack nucleation and propagation) applying the acoustic emission (AE) technique. Bending tests using two different tool steels were monitored in order to establish a relationship between AE signals and fracture events.

  • Pla de consolidació

     Balastegui Manso, Andreu; Arcos Villamarin, Robert; Martinez González, Eva; Jimenez Diaz, Santiago; Pamies Gomez, Teresa; Romeu Garbi, Jordi
    Participation in a competitive project

     Share

  • Comportamiento mecánico de una correa plana de transmisión de potencia considerando los efectos inerciales ( aceleración radial y tangencial).

     Martinez González, Eva; Genesca Francitorra, Meritxell; Romeu Garbi, Jordi
    Congreso Iberoamericano de Ingeniería Mecánica
    Presentation's date: 2009-11-18
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • DPI 2007-66688-C02-01. Detección y Diagnóstico de fallos para Mantenimiento Predictivo de sistemas mecatrónicos. Aplicación a actuadores de alta eficiencia para robótica y aeronáutica, y accionamientos auxiliares en el automóvil. DIAGMAIN - MECH-AUTO

     Romeral Martinez, Jose Luis; Ortega Redondo, Juan Antonio; Martinez González, Eva; Cusido Roura, Jordi; Garcia Espinosa, Antonio; Moreno Eguilaz, Juan Manuel; Riba Ruiz, Jordi Roger; Romeu Garbi, Jordi; Rosero Garcia, Javier Alveiro
    Participation in a competitive project

     Share

  • PLANTA PARA LA CARACTERIZACIÓN DINÁMICA AXIAL Y TRANSVERSAL DE MUELLES Y AISLADORES DE VIBRACIONES

     Martinez González, Eva; Romeu Garbi, Jordi; Torres, R J
    Date of request: 2006-06-01
    Invention patent

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Planta para la caracterización dinámica axial y transversal de muelles y aisladores de vibraciones.

    Consiste en una planta de ensayo que permite estudiar el comportamiento axial y transversal de aisladores de vibraciones bajo diferentes situaciones de carga (estática, dinámica y de impacto).

    La planta está constituida básicamente por el aislador a ensayar (4), una masa de bloqueo (3) que queda aislada del entorno mediante aisladores (2), masas calibradas para realizar el ensayo (5) y un elemento excitador de vibraciones (1) que puede actuar tanto vertical como horizontalmente. Se trata de un sistema doble masa-muelle, en el que las frecuencias propias de los dos sistemas son suficientemente diferentes, de tal forma que permite la caracterización del muelle ensayado a bajas frecuencias (incluso inferiores a 20 Hz).

  • Análisis, diseño y construcción de un chasis autoportante de material composite

     Velazquez Ameijide, Juan; Llumà Fuentes, Jordi; Sánchez, C; Martinez González, Eva; Ruiz, Carlos
    Congreso Universitario de Innovación Educativa en las Enseñanzas Técnicas
    Presentation's date: 2004-02-22
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Ingeniería inversa de bajo perfil: Motor 32 cm3

     Christophe, Alonso; Xavier, Ribas; Ortiz Moron, Pedro; Ruiz Moya, Carlos; Martinez González, Eva
    Congreso Universitario de Innovación Educativa en las Enseñanzas Técnicas
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window