Examinando por Autor "Díaz-Garrido, Francisco Alberto"
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Ítem Applied computer vision for composite material manufacturing by optimizing the impregnation velocity: An experimental approach(Elsevier, 2021-11-30) Almazán-Lázaro, Juan Antonio; López-Alba, Elías; Díaz-Garrido, Francisco AlbertoThe application of the cutting edge industrial solutions in composite manufacturing are optimizing the processes, quality control and resources usage. Computer vision is currently used in many quality control stages, although its potential advantages have not been applied in the process control. In this paper, computer vision is used to control the impregnation velocity in VARI (Vacuum Assisted Resin Infusion) process. As it is known, there is a relationship between the impregnation velocity and the final mechanical properties in LCM (Liquid Composite Manufacturing) processes. Constant and optimum flow front velocity mean optimum mechanical properties, although the nature of the process makes it difficult to keep these conditions. Then, a methodology has been proposed to identify and use the optimum velocity during the manufacturing process. Firstly, the flow front recognition algorithm was calibrated to be used in different reinforcement and fluid systems. Then, tensile and impact specimens have been manufactured and tested at different controlled and uncontrolled velocities. As a result, the tensile modulus has been increased up to 12.6%, as the tensile strength has increased up to 8.7%. Similarly, the maximum reaction force during the impact test has been increased up to 6.5%, as the damaged area has been reduced by 8.8%. For stitched laminates, force results increase up to 3.2%, as the damaged area has been reduced up to 31% when the optimum velocity is used. The experimental results have demonstrated the advantage of using mechanisms to control the impregnation process to achieve improved mechanical properties of composite materials.Ítem Enhanced Low-Velocity Impact Properties for Resin Film Infusion-Manufactured Composites by Flow-Control Approach(Multidisciplinary Digital Publishing Institute, 2021-10-06) Almazán-Lázaro, Juan Antonio; López-Alba, Elías; Schmeer, Sebastian; Díaz-Garrido, Francisco AlbertoThe optimization of the mechanical properties of composite materials has been a challenge since these materials were first used, especially in aeronautics. Reduced energy consumption, safety and reliability are mandatory to achieve a sustainable use of composite materials. The mechanical properties of composites are closely related to the amount of defects in the materials. Voids are known as one of the most important defect sources in resin film infusion (RFI)-manufactured composites. Minimizing the defect content leads to maximized mechanical properties and lightweight design. In this paper, a novel methodology based on computer vision is applied to control the impregnation velocity, reduce the void content and enhance the impact properties. Optimized drop-impact properties were found once the impregnation velocity was analyzed and optimized. Its application in bot conventional and stitching-reinforced composites concludes with an improvement in the damage threshold load, peak force and damaged area. Although stitching tends to generate additional voids and reduces in-plane properties, the reduction in the damaged area means a positive balance in the mechanical properties. At the same time, the novel methodology provides the RFI process with a noticeable level of automation and control. Consequently, the industrial interest and the range of applications of this process are enhanced.Ítem Human femur fracture by mechanical compression: Towards the repeatability of bone fracture acquisition(ELSEVIER, 2023-09) Pérez-Cano, Francisco Daniel; Jiménez-Pérez, Juan Roberto; Molina-Viedma, Ángel Jesús; López-Alba, Elías; Luque-Luque, Adrián; Delgado-Martínez, Alberto Damián; Díaz-Garrido, Francisco Alberto; Jiménez-Delgado, Juan JoséThe increase in life expectancy combined with greater bone fragility over the years is causing a rise in the bone fracture cases. Femur fractures are the most important due to their high mortality rate. This multidisciplinary work is carried out in this context and focuses on the experimental reproduction of human femur fractures by compression. We describe a sequence of steps supervised by orthopaedic surgeons for the correct arrangement of specimens on the system set up to perform the experiment. The device applies force by compression until the human bone is fractured. All tests performed have been monitored and evaluated from different knowledge perspectives. The results obtained have demonstrated the repeatability of the fracture type in a controlled environment as well as identifying the main features involved in this process. In addition, the fractured bones have been digitized to analyze the fracture zone to recreate and evaluate future simulations.Ítem Improving composite tensile properties during resin infusion based on a computer vision flow-control approach(Multidisciplinary Digital Publishing Institute, 2018-12-05) Almazán-Lázaro, Juan Antonio; López-Alba, Elías; Díaz-Garrido, Francisco AlbertoLiquid composite manufacturing techniques, mainly applied in the transport industry, have been studied and optimized for decades while defect analysis and its minimization have been a goal to increase reliability and mechanical performance. Researchers have found that many process parameters have a strong influence on the mechanical behavior of composite structures where the flow front velocity, closely related to voids, plays a considerable role. In this work, the optimal flow front velocity was evaluated and controlled using a computer vision system for different laminates improving the mechanical tensile properties and void content. Enhanced mechanical tensile properties were found using a feedback flow-controller vision system which was able to keep the optimal flow front velocity constant to reduce the air traps among tows and fibers. Tensile strength was enhanced up to 18% for fiber orientation at 0◦ and 3.3% at 90◦, whereas tensile modulus was increased up to 18.4% for fibers at 0◦ and 8.7% at 90◦. A novel methodology is presented through this work, aiming to improve the robustness of resin film infusion (RFI) processes while ensuring the quality of the composite material.Ítem Indentation Measurement in Thin Plates under Bending Using 3D Digital Image Correlation(Multidisciplinary Digital Publishing Institute, 2021-03-17) Almazán-Lázaro, Juan Antonio; López-Alba, Elías; Rubio, Luis; Díaz-Garrido, Francisco AlbertoIn the current paper, a novel experimental methodology to characterize the contact behavior on thin plates under bending is presented. The method is based on the experimental measurement of the indentation observed during contact experiments. Tests were conducted using aluminum thin plates and a steel sphere to evaluate the effect of thickness and bending during contact. For this purpose, a non-contact optical technique, 3D Digital Image Correlation (3D-DIC), has been employed to measure the out-of-plane displacements experienced at the rear face of the specimens (opposite where the contact is occurring). An indirect measurement of the experimental contact law is obtained for different plate thicknesses (2 mm, 3 mm, 4 mm, 5 mm and 6 mm) as the contact load increases. An energy balance performed during contact experiments made it possible to evaluate and quantify the applied energy to generate bending and contact deformation. When the specimen thickness increases from 2 mm to 6 mm, contact deformation reaches higher values from the total applied energy. In addition, it is also possible to evaluate the portion of the elastically recovered energy for contact and bending deformation during the unloading. It has been observed that thicker specimens show a lower elastic energy recovery due to bending and a higher elastic energy recovery due to contact. Results clearly show how the ratio between absorbed and applied energy changes as the specimen thickness increases, highlighting the relevance of the proposed method for the characterization of contact behavior in thin plates.Ítem Numerical analysis of compliance and fatigue life of the CCC specimen(Elservier, 2023-01-23) Neto, Diogo Mariano; Antunes, Fernando Ventura; Sérgio, Edmundo; Branco, Ricardo; Camacho-Reyes, Alonso; Díaz-Garrido, Francisco Alberto; Gómez-Gonzales, Giancarlo Luis; Vasco, José ManuelThis study presents the numerical evaluation of the compliance in the CCC specimen aiming to assess the crack length inside the specimen. The numerical model considered the elastoplastic behaviour of the specimen, which is modelled using axisymmetric finite elements. The results shown that the propagation of the crack yields a nonlinear increase of the compliance. Nevertheless, variation of the compliance is very small for small values of crack radius. Considering a loading sequence composed by four load blocks of constant amplitude, the fatigue crack growth was predicted both using the Paris law and the numerical model. Both predictions agree but only the numerical simulation is able to capture the crack retardation between load blocksÍtem Optimización del proceso de infusión de resina mediante el control de la velocidad del frente de flujos en materiales compuestos reforzados con fibra(Jaén : Universidad de Jaén, 2020-12-18) Almazán-Lázaro, Juan Antonio; Díaz-Garrido, Francisco Alberto; López-Alba, Elías; Universidad de Jaén. Departamento de INGENIERÍA MECÁNICA Y MINERASe presenta una metodología basada en el control y análisis de la velocidad de impregnación aplicada a procesos de fabricación de materiales compuestos por infusión de resina. Se fundamenta en la relación entre la velocidad de impregnación y la generación de atrapamientos de aire. Mediante un sistema de control específicamente desarrollado, se realiza el proceso a velocidad óptima, tanto en laminados convencionales como reforzados tridimensionalmente por stitching. Mediante su aplicación, las propiedades a tracción e impacto han mostrado aumentos significativos. Por su parte, el stitching ha aportado ventajas relevantes al proceso de infusión al aumentar la capacidad de éste. Así, supone un avance significativo en el proceso de fabricación mediante el que se obtendrán materiales con mayores prestaciones, fiabilidad, optimización de peso y uso más eficiente de los recursos utilizados. Asimismo, el sistema aporta cierto grado de automatización al proceso caracterizado por su elevada labor manual.Ítem The mechanical effect of monitoring and controlling the impregnation in the resin infusion process(Wiley, 2022-01-25) Almazán-Lázaro, Juan Antonio; López-Alba, Elías; Díaz-Garrido, Francisco AlbertoNowadays, most of industries are optimizing their processes to make their products more competitive. In the composites manufacturing industry, there is a big gap between the almost fully automated processes and those which require an intensive labor-work. Although it has many advantages, the resin infusion process is characterized for its lack of automation. As a consequence, the results are strongly dependent on the process boundaries, the operator skills and expertise, and the result is usually far away from the optimum. In this work, the application of a novel methodology and its capability to maximize the mechanical properties of infusion-manufactured composite materials is presented. After manufacturing stitched and unstitched materials at different impregnation velocities, an optimum value was assessed. The application of this value during the manufacture has increased the tensile and impact properties.