Resolución del problema cinemático inverso en un robot SCARA mediante grupos de Assur

XIX Congreso Nacional de Ingeniería Mecánica, CNIM 2012, Castellón (España)Este artículo presenta una nueva formulación para la resolución de la cinemática inversa de un robot SCARA mediante grupos de Assur. Dicha formulación minimiza el tiempo de resolución del problema cinemático y permite definir, de manera inequívoca, el modo de trabajo del robot en cualquier instante de la simulación. También permite identificar posibles configuraciones singulares del problema inverso. Debido a las características comentadas, esta formulación está especialmente indicada para utilizarse en algoritmos automáticos de planificación de trayectorias en entornos cambiantes donde se deban evitar colisione

The current educational atmosphere regarding Graphic Engineering courses in university degrees

[EN] Subjects regarding graphic content are essential in engineering and architectural degrees; however, a significant lack of updated teaching methodologies are still commonplace among them. Although some assumptions can be made relating the possible causes of this mishap, truth is that no clear answer can be stated. Aiming to gather all relevant information that may bring light into real causes that led to such situation, 250 educators have been surveyed to collect first-hand perspectives on the real needs of these type of subjects. Results show that new bespoke teaching platforms to deal with graphic contents are being demanded by lecturers, especially in the case of technical drawings. Furthermore, educators preferred the use of free software that also allows autonomous learning and the implementation of innovative methodologies.This research was funded by funded by Ministry of Universities and co-funded by the Erasmus+ program of the European Union through grant 2021-1-ES01-KA220-VET-000034745Guerrero-Miguel, D.; Pando Cerra, P.; Prendes-Gero, M.; Muñiz-Calvente, M. (2024). The current educational atmosphere regarding Graphic Engineering courses in university degrees. Editorial Universitat Politècnica de València. https://doi.org/10.4995/HEAd24.2024.1724

Study of the Time-Temperature-Dependent behaviour of PVB: application to laminated glass elements

The mechanical behavior of laminated glass elements is governed by material properties of the interlayer, the Polyvinyl Butiral (PVB) being the most used interlayer material in these elements. PVB is a viscoelastic material whose mechanical properties (Young’s modulus, shear modulus, etc.) depend mainly on the load application time and the temperature. Thus an adequate mechanical characterization of the PVB must be performed in order to predict the response of laminated glass elements with a good accuracy In this work, PVB specimens were subjected to static relaxation tests and to dynamic experimental tests (frequency domain) at different temperatures from -〖15〗^o C to 〖50〗^o C using a DMTA equipment. Then the curves at different temperatures were related using the William-Landel-Ferry (WLF) Time-Temperature Superposition (TTS) model to obtain the mastercurve of both the time and frequency domain Young’s moduli of the PVB. Finally, a viscoelastic Prony based model was fitted to the experimental data and used, afterwards, to simulate numerically the static and dynamic behaviour of different laminated glass elements at different temperatures. The numerical simulations were compared with the static and dynamic experimental results achieving a good accuracy in both the static deflections and the natural frequencies. With respect to the damping, the discrepancies are less than 22%

Satisfacción del alumnado en la utilización de sus teléfonos móviles como herramienta de gamificación en un entorno universitario

The use of the mobile phone as a gamification tool to improve attention and interest in a university context has been barely evaluated. The objective of this study is to evaluate it in some subjects of the Medicine and Biology degree. The experiment was carried out in three highly demanding and rote learning subjects of the Degree in Medicine and Biology at the University of Oviedo. After each lesson, the researchers devoted 8 minutes to carry out game-based quizzes through mobile phones. The students\u27 satisfaction with the technique was evaluated at the end of the subject. The statistics used are descriptive together with histograms. The results were encouraging, with more than 90% of the students wanting to use the methodology in the rest of the subjects and more than 90% also having a high degree of overall satisfaction. The results were highly concordant in the three subjects analysed despite their technical diversity.La utilización del teléfono móvil como herramienta de gamificación para mejorar la atención y el interés en un entorno universitario ha sido escasamente evaluado. El objetivo de este estudio es evaluarlo en algunas asignaturas del grado de Medicina y Biología. El experimento se realizó en 3 asignaturas altamente demandantes y de carácter memorístico del Grado de Medicina y Biología de la Universidad de Oviedo. Después de cada clase los investigadores se reservaron 8 minutos para realizar cuestionarios en forma de juego a través de los teléfonos móviles. Al final de la asignatura se evaluó la satisfacción de los alumnos con la técnica. La estadística utilizada es descriptiva acompañada de histogramas. Los resultados fueron alentadores, deseando más del 90% de los alumnos trasladar la metodología al resto de asignaturas y estando también más del 90% con un grado de satisfacción global alto. Los resultados fueron altamente concordantes en las 3 asignaturas analizadas a pesar de su diversidad técnica

A Probabilistic Approach to Assessing and Predicting the Failure of Notched Components

This work presents a probabilistic model to evaluate the strength results obtained from an experimental characterisation program on notched components. The generalised local method (GLM) is applied to the derivation of the primary failure cumulative distribution function (PFCDF) as a material property (i.e., independent of the test type, load conditions and specimen geometry selected for the experimental campaign), which guarantees transferability in component design. To illustrate the applicability of the GLM methodology, an experimental program is performed using specimens of EPOLAM 2025 epoxy resin. Three different samples, each with a specific notch geometry, are tested. As a first scenario, a single assessment of each sample is obtained and the PFCDFs are used to perform cross predictions of failure. Some discrepancies are noticeable among the experimental results and cross-failure predictions, although they are within the expected margins. A possible reason for the disagreement can be assigned to the inherent statistical variability of the results and the limited number of tests per each sample. As a second scenario, a joint assessment of the three samples is performed, from which a unique PFCDF is provided, according to the GLM. In the latter case, a more reliable assessment of the experimental results from the geometry conditions is achieved, the suitability of the selected driving force is verified, and the transferability of the present material characterisation is confirmed

A novel tool for finite element post-processing

International Conference on Mechanics and Materials in Design (7th, 2017, Albufeira

Gamificación en la impartición de Cálculo de Estructura

Resumen de los autoresGrado en Ingeniería Civil (Universidad de Oviedo)Las nuevas tecnologías entre las que se encuentran los dispositivos móviles no son ajenas al mundo de la docencia en ingeniería. En la mayoría de los casos, los dispositivos móviles, teléfonos fundamentalmente, son percibidos por el docente como un problema en el aula más que una herramienta de trabajo. En este trabajo se propone una metodología de introducción positiva de los dispositivos móviles durante las clases de Cálculo de Estructuras a través de cuestionarios de tipo “Quizz”. Con ello se busca una propuesta de gamificación para los alumnos a la vez que se obtiene por parte del docente una información relevante sobre el grado de aprendizaje de los conceptos y materia impartida. El desarrollo de esta propuesta ha sido aceptada y seguida por los alumnos con interés siendo el grado de satisfacción de la misma muy positivo.ES

Fatigue Assessment of Selective Laser Melted Ti-6Al-4V: Influence of Speed Manufacturing and Porosity

Additive Manufacturing represents a promising technology as an alternative to the conventional manufacturing process, with rapid and economic product development, as well as a significant weight reduction and a freeform design. Although the mechanical properties of additively manufactured metals, such as the Ti-6Al-4V alloy, are well-established, a complete understanding of the fatigue performance is still a pending aspiration due to its inherent stochastic complexity and the influence of several manufacturing factors. This paper presents a study of the influence of speed manufacturing and porosity in the fatigue behaviour of a Ti-6Al-4V alloy. To this aim, a numerical simulation of the expected porosity at different laser velocities is performed, together with a simulation of the residual stresses. These numerical results are compared with experimental measurements of residual stresses and a qualitative analysis of the porosities. Then, fatigue strength is experimentally obtained for two different laser speeds and fitted by a probabilistic model. As a result, the probabilistic S–N fields for different laser velocities are found to be similar, with scatter bands nearly coincident, drawing the conclusion that this effect is negligible in comparison with other concurrent ones, such as roughness or surface defects from manufacturing conditions, promoting crack initiation and premature fatigue failure

Análisis probabilístico de elementos de vidrio recocido mediante una distribución triparamétrica Weibull

El vidrio y la cerámica presentan un comportamiento frágil, lo que implica una gran dispersión en los resultados de ensayos. Esta dispersión se debe principalmente a la inevitable presencia de microfisuras superficiales, defectos de borde o defectos internos, que deben tenerse en cuenta mediante criterios de fallo apropiados no deterministas, sino probabilistas. Entre las distribuciones de probabilidad existentes, generalmente se utiliza la distribución de Weibull bi o triparamétrica en el ajuste de resultados de resistencia de materiales. En primer lugar se realiza un amplio programa experimental utilizando probetas planas de vidrio recocido de distintas dimensiones bajo flexión a 4 puntos y flexión con anillos concéntricos dobles. Seguidamente se presentan los modelos de elementos finitos realizados para cada tipo de ensayo, así como el ajuste de los parámetros de la función de distribución (fdd) triparamétrica de Weibull (λ: localización; β: forma; δ: escala) para un criterio de fallo determinado y el cálculo de las áreas efectivas a partir de la fdd determinada. Con todo ello, el trabajo pretende generalizar la utilización de la fdd triparamétrica de Weibull en elementos de vidrio estructural con distribuciones de carga no descritas analíticamente, permitiendo aplicar el modelo probabilista propuesto a distribuciones generales de solicitación