Examinando por Autor "Molina-Viedma, Ángel"
Mostrando 1 - 2 de 2
- Resultados por página
- Opciones de ordenación
Ítem Comparative of conventional and alternative Digital Image Correlation techniques for 3D modal characterisation(Elsevier, 2020-02-01) Molina-Viedma, Ángel; Felipe-Sese, Luis; Lopez-Alba, Elias; Díaz, Francisco A.The integration of Fringe Projection and 2D-DIC is a low-cost optical technique which employs a single camera for full-field 3D displacement measurements using RGB colour encoding to filter coexisting fringe and speckle patterns out from a single image. In this work, this technique was explored together with conventional 3D-DIC for challenging modal analysis on a large aeronautical panel under random excitation. Modal identification was performed using the Least-Squares Complex Exponential approach. Multiple degree-of-freedom methods have been avoided in previous works or just employed in one direction due to high memory requirements to process 3D full-field data. In this work, the 3D modal characterisation was addressed with especial mention to mode shapes. Hardware limitations makes FP + DIC less sensitive than 3D-DIC and hence more suitable for lower frequencies. Nevertheless, the obtained modal parameters showed high agreement and hence FP + DIC demonstrated to be a cost-effective alternative for 3D modal analyses.Ítem 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, FranciscoIn 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.