Gallardo Llopis, Carles
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Gallardo Llopis
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Carles
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- PublicationComparative Study of Coupling Techniques in Lamb Wave Testing of Metallic and Cementitious Plates(MDPI AG, 2019-09-20) Vazquez-Martinez, Santiago; Gosálbez Castillo, Jorge; Bosch Roig, Ignacio; Carrión García, Alicia; Gallardo Llopis, Carles; Paya Bernabeu, Jorge Juan; Dpto. de Física Aplicada; Escuela Técnica Superior de Ingeniería de Telecomunicación; Dpto. de Ingeniería de la Construcción y de Proyectos de Ingeniería Civil; Dpto. de Comunicaciones; Escuela Técnica Superior de Arquitectura; Instituto Universitario de Telecomunicación y Aplicaciones Multimedia; Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos; Instituto de Investigación para la Gestión Integrada de Zonas Costeras; Instituto de Instrumentación para Imagen Molecular; Instituto Universitario de Investigación de Ciencia y Tecnología del Hormigón; Agencia Estatal de Investigación; Ministerio de Economía y Empresa[Otros] Lamb waves have emerged as a valuable tool to examine long plate-like structures in a faster way compared to conventional bulk wave techniques, which make them attractive in non-destructive testing. However, they present a multimodal and dispersive nature, which hinders signal identification. Oblique incidence is one of the most known methods to generate and receive Lamb waves and it is applied in different experimental arrangements with different types of sensors. In this work, several setups were conducted and compared to determine the optimal ones to launch and detect ultrasonic Lamb waves, especially in non-homogeneous specimens. The chosen arrangements were contact with angle beam transducers, immersion in a water tank, localised water coupling using conical containers and air coupling. Plates of two different materials were used, stainless steel and Portland cement mortar. Theoretical and experimental dispersion curves were compared to verify the existence of Lamb modes and good correspondence was achieved.
- PublicationAirborne ultrasounds for damaged cementitious characterization(Acoustical Society of America, 2019-09-06) Gosálbez Castillo, Jorge; Carrión García, Alicia; Gallardo Llopis, Carles; Vázquez, S.; Genovés, V.; Paya Bernabeu, Jorge Juan; Dpto. de Física Aplicada; Escuela Técnica Superior de Ingeniería de Telecomunicación; Dpto. de Ingeniería de la Construcción y de Proyectos de Ingeniería Civil; Dpto. de Comunicaciones; Escuela Técnica Superior de Arquitectura; Instituto Universitario de Telecomunicación y Aplicaciones Multimedia; Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos; Instituto de Investigación para la Gestión Integrada de Zonas Costeras; Instituto de Instrumentación para Imagen Molecular; Instituto Universitario de Investigación de Ciencia y Tecnología del Hormigón; AGENCIA ESTATAL DE INVESTIGACION[EN] The scope of this paper is to demonstrate the capability of airborne non-contact ultrasound (ANC-US) to assess thermal damage on normalized Portland cement mortar specimens. For this purpose, contact ultrasound (C-US) and ANC-US are compared. A normalized dosage mortar was carried out to obtain standardized mortar specimens of 4 x 4 x 16 cm. Then, they were measured by ANC-US and C-US. Afterwards, they were thermal damaged (400º C) and measured again. Ultrasound velocity and frequency attenuation were estimated. As expected, damaged samples show lower velocities and higher attenuations than sound samples. It is remarkable how the attenuation keeps constant for frequencies below 100 kHz and increases due to the sensitivity of higher frequencies to the size of thermal microcracking. Although ANC-US does not require any coupling media as C-US does, it requires additional calibration to compensate propagation through the air and material boundaries. Considering these terms, both techniques offer consistent results and the capability of ANC-US technique for damage characterization in cementitious systems is proved.