Examinando por Autor "Felipe-Sesé, Luis"

Mostrando 1 - 12 de 12

An alternative approach for improving DIC by using out-of-plane displacement information
(Elsevier, 2020-05-01) Siegmann, Philip; Felipe-Sesé, Luis; Díaz, Francisco
A new approach to perform 2D Digital Image Correlation (DIC) on objects that are subjected to large out-of-plane displacements is presented. It employs out-of-plane information to distort the speckle images of the reference and the deformed surface, increasing their similarity and therefore their sub-set cross-correlation peaks. The new approach is implemented using the combined Fringe Projection and 2D-DIC technique on two experiments: The buckling of an initial flat plate, and the rotation of the reference surface towards the camera from 0° to 60°. In both cases large speckle distortions are produced due to two issues, the lens magnification and the surface tilting. The first speckle distortion is applied to the deformed image to perform the lens magnification correction, and the second speckle distortion is applied to the reference image. The obtained distorted speckle images become very similar, allowing to successfully compute corresponding pixels between both images in a simple way (i.e. without nonlinear minimization processes). For this propose, an analytical iterative equation is derived to determine pixel displacements due to out-of-plane surface tilting. The resulting displacements are compared with those obtained by the conventional procedure, applying 2D-DIC (using open source Ncorr software) on the non-distorted speckle images and then making the lens magnification correction. The novel procedure proposed makes it possible to successfully find the corresponding pixels at the reference surface for out-of-plane rotations of 55° and 60° for which Ncorr failed. 3D-DIC (using commercial VIC software) is also employed to validate the results.
Comportamiento a fractura de yeso con adición de fibras poliméricas
(2019-04) Suárez-Guerra, Fernando; Felipe-Sesé, Luis; Díaz, Francisco A.; Gálvez-Ruíz, Jaime Carlos; García-Alberti, Marcos
El yeso es un material de construcción ampliamente utilizado como revestimiento interior en edificios por su bajo coste, manejabilidad y propiedades de habitabilidad (aislamiento acústico y térmico, aspecto estético, etc.). La industria del yeso ha ido buscando nuevos usos, fruto de lo cual, entre otros, han surgido los paneles sándwich de yeso laminado o las placas de yeso reforzado con fibras de celulosa, que mejoran considerablemente sus propiedades mecánicas. Por otro lado, el uso de fibras poliméricas ha dado recientemente interesantes resultados en hormigón, proporcionando buenas propiedades dúctiles a las mezclas y dotándolas de una importante capacidad resistente frente a esfuerzos de tracción. En el presente estudio se analiza el comportamiento a fractura de mezclas de yeso con adiciones de distintos tipos de fibras poliméricas, en particular microfibras de polipropileno y macrofibras de poliolefina. Para ello se realizaron ensayos de flexión en tres puntos con probetas prismáticas entalladas. Además, el uso de un sistema de correlación digital de imágenes (DIC) permite medir la evolución de la apertura de la fisura (CMOD) y, lo que es más innovador e importante para evaluar su comportamiento, obtener mapas completos de deformaciones que ayuden a entender cómo contribuyen los distintos tipos de fibras a la disipación de energía durante la propagación del daño.
Estudio de comportamiento vibratorio aplicado al análisis estructural mediante técnicas ópticas de alta resolución temporal y espacial
(2025-01-16) Pastor, Manuel Esteban; Felipe-Sesé, Luis; Universidad de Jaén. Departamento de Ingeniería Mecánica
Las vibraciones en entornos industriales afectan maquinaria y procesos productivos, causando fallos en componentes críticos, aumentando costos de mantenimiento y reduciendo la vida útil de los equipos. Además, estas vibraciones pueden generar condiciones peligrosas para los usuarios. Las variaciones de temperatura también influyen, alterando las propiedades de los materiales y acelerando su desgaste. El análisis modal experimental es esencial para caracterizar las propiedades dinámicas de los sistemas vibratorios. Las técnicas ópticas sin contacto, como la vibrometría láser Doppler (LDV) y la Correlación Digital de Imágenes (DIC), ofrecen mediciones más precisas. Proyección de franjas (FP) combinada con DIC proporciona una solución de bajo costo para obtener mediciones detalladas del comportamiento dinámico. Además, la magnificación de movimiento amplifica vibraciones sutiles, mejorando la visualización de pequeños movimientos difíciles de detectar. Por tanto, este trabajo busca mejorar los métodos de procesamiento de datos para medir vibraciones y analizar su evolución bajo cambios de temperatura.
Estudio de la influencia de la adición de fibras en la rotura en modo II de materiales cuasifrágiles
(UK Zhende Publishing Limited, 2021-08) Suárez Guerra, Fernando; Felipe-Sesé, Luis; Castilla-Gonzalo, Francisco-José; Díaz-Garrido, Francisco
La rotura de materiales cuasifrágiles, tales como el hormigón o el yeso, ha sido objeto de estudio desde hace décadas. Estos estudios han ampliado el conocimiento de los mecanismos de rotura así como de los parámetros que gobiernan este fenómeno y han permitido proponer modelos numéricos que lo reproducen mediante herramientas tales como el método de los elementos finitos. Por otro lado, de los tres posibles Modos de rotura que se diferencian a la hora de analizar problemas de Mecánica de la Fractura, el Modo I es sin duda el mejor conocido, reproducido experimentalmente y empleado como base para los modelos numéricos. No obstante, existen situaciones en las que la rotura es el resultado de un estado de tensiones que moviliza un mecanismo en el que participan los Modos I y II simultáneamente. A este respecto, la rotura en Modo II ha sido estudiada con menos profundidad, en parte porque las roturas en Modo I son más habituales, pero también porque su reproducción experimental y, por tanto, su estudio, resulta más complejo. En este estudio se presentan resultados experimentales de ensayos que movilizan la rotura en Modo II en probetas de yeso adicionadas con fibras de refuerzo. En concreto se emplean el ensayo de cortante definido por la norma japonesa JSCE y el ensayo de push-off. El campo de desplazamientos se obtiene empleando la técnica de correlación digital de imágenes (DIC), lo cual ayuda a entender cómo las fibras modifican los mecanismos de rotura de la matriz cuando ésta se produce en condiciones de Modo II.
Estudio de la influencia de la adición de fibras en la rotura en modo II de matrices cuasifrágiles
(2021-06) Suárez Guerra, Fernando; Felipe-Sesé, Luis; Castilla-Gonzalo, Francisco J.; Díaz, Francisco A.
La rotura de materiales cuasifrágiles, tales como el hormigón o el yeso, ha sido objeto de estudio desde hace décadas. Estos estudios han ampliado el conocimiento de los mecanismos de rotura así como de los parámetros que gobiernan este fenómeno y han permitido proponer modelos numéricos que lo reproducen mediante herramientas tales como el método de los elementos finitos. Por otro lado, de los tres posibles modos de rotura que se diferencian a la hora de analizar problemas de Mecánica de la Fractura, el modo I es sin duda el mejor conocido, reproducido experimentalmente y empleado como base para los modelos numéricos. No obstante, existen situaciones en las que la rotura es el resultado de un estado de tensiones que moviliza un mecanismo en el que participan los modos I y II simultáneamente. A este respecto, la rotura en modo II ha sido estudiada con menos profundidad, en parte porque las roturas en modo I son más habituales, pero también porque su reproducción experimental y, por tanto, su estudio, resulta más complejo.En este estudio se presentan resultados experimentales de ensayos que movilizan la rotura en modo II en probetas de yeso adicionadas con fibras de refuerzo. En concreto se emplean el ensayo de cortante definido por la norma japonesa JSCE y el ensayo de push-off, que en los últimos años está permitiendo estudiar este modo de rotura en el hormigón adicionado con fibras. El campo de desplazamientos se obtiene empleando la técnica de correlación digital de imágenes (DIC), lo cual ayuda a entender cómo las fibras modifican los mecanismos de rotura de la matriz cuando ésta se produce en condiciones de modo II.
Evaluation of modal identification under base motion excitation using vision techniques
(ELSEVIER, 2022-11) Molina-Viedma, Ángel; Felipe-Sesé, Luis; Pastor-Cintas, Manuel; López-Alba, Elías; Díaz, Francisco
In certain situations, employing a movable base acting as the excitation of a mechanical system is the best or even the only way to determine the response model for modal analysis. However, the obtained transmissibility functions must be modified prior to modal identification with a conventional procedure based on frequency response functions. Moreover, when employing vision techniques, the response curves are noisier and even poorly defined as the sensitivity is significantly lower than traditional sensors. Using the right model for curve-fitting is particularly relevant in this case. The current study performs an analysis of the adaptation of transmissibility functions, obtained by a vision technique, to improve the accuracy of the modal data estimation with conventional procedures. Two sets of transmissibility functions were evaluated: the originally obtained in the experiment, and the adapted one. After modal identification, significant differences were found concerning mode shapes and curve synthesis. The adaptation improved the accuracy of the identification in all the measurement points, proved by statistical indicators of the curve-fitting procedure like the correlation coefficient and the error between the synthesised and the experimental curves.
Exploiting phase-based motion magnification for the measurement of subtle 3D deformation maps with FP+ 2D-DIC
(Elsevier, 2022-05-31) Felipe-Sesé, Luis; Molina-Viedma, Ángel J.; Pastor-Cintas, Manuel; López-Alba, Elías; Díaz, Francisco
Phase-Based Motion Magnification (PBMM) is an effective methodology to visualise imperceptible phenomena based on magnifying periodic subtle movements on image sequences. Moreover, the integration of the optical techniques Fringe Projection and 2D Digital Image Correlation (FP + 2D-DIC) make it possible to obtain 3D displacement maps employing a single camera. In this study, the integration of PBMM with FP + 2D-DIC is exploited for the determination of subtle 3D displacements. An initial solid-rigid test validates of the combination of those techniques. A later test, employing a cantilever beam, demonstrates its correct performing in the determining of Operational Deflection Shapes. In both cases, the results are compared with those obtained with 3D-DIC and Scanning Laser Doppler Vibrometer (SLDV) to evaluate the relation between the magnification factor and the result obtained. Finally, the potential of the proposed integration for the determination of complex mode shapes is demonstrated by obtaining the ODSs of an industrial component.
FP+DIC for low-cost 3D full-field experimental modal analysis in industrial components
(ELSEVIER, 2019-04-07) Felipe-Sesé, Luis; Molina-Viedma, Ángel J.; López-Alba, Elías; Díaz, Francisco A.
High Speed 3D Digital Image Correlation has reached notorious popularity in dynamic characterisations because of the full-field non-invasive performance. It is being especially relevant for experimental modal analysis due to the importance of the modal parameters to define the dynamic behaviour. However, the economic cost of a stereoscopic system of two high speed cameras is a main concern regarding traditional instrumentations. In the search for low-cost alternatives, different methodologies have arisen that employ a single camera for 3D measurements. One approach consists in obtaining a stereo-vision in a single image using, for instance, a mirror system. These approaches involve important field of-view restrictions. An interesting approach employs the full resolution by combining Fringe Projection and 2D-DIC for out-of-plane and in-plane displacements, respectively. In this study, this technique is explored to perform experimental modal analysis in a large non-flat aeronautical panel. The validation of the results has been performed using accelerometer measurements during an impact hammer test. The results of the study stand this technique as an attractive low-cost technique for 3D full-field modal characterisations of complex components
Full-field 3D displacement and strain analysis during low energy impact tests employing a single-camera system
(Elsevier, 2020) Felipe-Sesé, Luis; López-Alba, Elías; Díaz, Francisco
Characterising materials behaviour during dynamics events such as impact require several features related to monitoring and instrumentation which find in full-field techniques one of the main responses due to high spatial and, nowadays, also temporal resolution. 3D-Digital Image Correlation has provided an interesting tool to evaluate the material response during impact testing. It contributes with displacement and strain fields at high frame rates, which represents enormous potential for subsequent analysis. However, 3D-DIC also presents some issues which may condition the experimentation. The first of them is the requirement of a stereoscopic optical system, which lead to important economic issues if high speed cameras are required. Secondly, certain impact arrangements have limited space which make complicated to dispose of a proper stereoscopic system observing an area of interest with a suitable angle that makes it possible r a successful processing. In this work, a recent procedure combining Fringe projection and 2D-DIC is presented as an alternative for impact testing analysis. As main characteristic, the optical arrangement is simplified to only one high speed camera and an additional simple LCD projector which makes it easier the experimentation, reducing significantly the setup cost. To demonstrate that capabilities of FP+2D-DIC as a simpler approach with results comparable to those obtained with 3D-DIC, in this work it was analysed 2, 3, 4, and 5 mm thickness aluminium plates under low speed impacts with different energy levels. Impacts were performed employing an impact tower with a hemispherical impactor, connected to a load cell. During the impact, displacement and strain maps were measured at the non-impacted face of the specimen, using a single camera system implementing the combination of FP and 2D-DIC techniques. Permanent displacement and strain maps were validated with those obtained with a 3D-DIC system, supporting the potential of this FP+2D-DIC approach for impact testing.
On the experimental characterisation of crack tip displacement fields on nonplanar elements: Numerical and experimental analysis
(Elsevier, 2023-02-04) Camacho-Reyes, Alonso; Antunes, Fernando Ventura; Vasco, José Manuel; Diaz-Garrido, Francisco Alberto; Felipe-Sesé, Luis
In this work, a numerical and experimental study about crack tip fields characterisation on curve-cracked elements has been performed. This study combines a novel differential geometry approach combined with 3D-DIC and FEA results to determine crack-tip parameters from the displacement field on a curved cracked element. The work aims to validate and compare some aspects that cannot be addressed using 3D-DIC. SIFs for different crack lengths are determined using DIC and FEA data and compared In addition, a comprehensive comparison between experimental and numerical fields is done using an Image Decomposition technique based on Tchebichef polynomials.
On the fracture behaviour of fibre-reinforced gypsum using micro and macro polymer fibres
(Elsevier, 2020-05-30) Suárez Guerra, Fernando; Felipe-Sesé, Luis; Díaz, Francisco; Galvez, Jaime; García-Alberti, Marcos García
Gypsum is the most widely used material as interior lining in buildings due to its low cost and good habitability conditions. The use of fibres as randomly distributed reinforcement of quasibrittle matrices, such as gypsum, remarkably improve the material behaviour under tensile stresses. In this work, the fracture behaviour of gypsum specimens reinforced with several types of polymer fibres was assessed, for one of them three fibre lengths were studied. Three types of polymer fibres were employed, with one of them being of microscopic scale and the other two of macroscopic scale. The mechanical behaviour of each mix was studied by means of three-point bending tests and compression tests that were analysed using a digital image correlation system. To study the influence of the fibre length, pull-out tests were also performed. The size, surface finishing and length of the fibres strongly affect the material properties and the way that the fracture mechanisms are developed.
Thermoelastic effect in modal shapes at high frequencies using infrared thermography
(Elsevier, 2021-02-01) Molina-Viedma, Angel J; Felipe-Sesé, Luis; Lopez-Alba, Elias; Diaz, Francisco A.
Infrared thermography is employed by different methodologies and techniques to perform characterisations and evaluations in solids, typically related to fracture mechanics and damage, based on monitoring heat generation or temperature changes. In this study, the limits of the current technology for Thermoelastic Stress Analysis (TSA), usually employed under low-frequency loads, are explored to characterise temperature fields associated to the first stress invariant in mode shapes. Higher frequencies are especially emphasised in this research. Eleven modes of a plate were analysed, reaching frequencies over 2000 Hz. High correlation coefficients were obtained in comparison with the first stress invariant fields of a finite element model, with a detriment as the mode’s order increases. In those cases, this study highlights the combined influence of the specimen response and mode shape stiffness as well as the progressively shorter integration time.

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Examinando por Autor "Felipe-Sesé, Luis"