Mechanical Model and FEM Simulations for Efforts on Biceps and Triceps Muscles under Vertical Load: Mathematical Formulation of Results

[ES]Aunque las contracciones isométricas en los músculos humanos se han analizado varias veces, no existen modelos de elementos finitos que nos permitan utilizar la misma articulación modelada (el codo en nuestro caso) en diferentes condiciones. La mayoría de las articulaciones del codo utilizan elementos 3D para el mallado. Representar los músculos de la articulación es bastante útil cuando el estudio se centra en el propio músculo, para conocer la distribución de tensiones en el músculo y comprobar en detalle las lesiones musculares (inserción tendón-músculo, por ejemplo). Sin embargo, esta técnica no es útil para estudiar el comportamiento del músculo en diferentes posiciones de la articulación. Este estudio, basado en el modelo mecánico de la articulación del codo, propone una metodología para modelar los músculos a estudiar en diferentes posiciones modelándolos con elementos 1D. Además, la metodología permite calcular las tensiones del bíceps y tríceps bajo carga para diferentes ángulos de apertura de la articulación del codo. Los resultados de la simulación se han modelado matemáticamente para obtener formulaciones generales de estas tensiones en función de la carga y del ángulo de apertura.[EN]Although isometric contractions in human muscles have been analyzed several times, there are no FEA models that allow us to use the same modeled joint (the elbow under our case) in different conditions. Most elbow joints use 3D elements for meshing. Representing the muscles in the joint is quite useful when the study is focused on the muscle itself, knowing stress distribution on muscle, and checking damage in muscle in a detailed manner (tendon–muscle insertion, for example). However, this technique is not useful for studying muscle behavior at different positions of the joint. This study, based on the mechanical model of the elbow joint, proposes a methodology for modelling muscles that will be studied in different positions by meshing them with 1D elements. Furthermore, the methodology allows us to calculate biceps and triceps efforts under load for different angles of elbow joint aperture. The simulation results have been mathematically modelled to obtain general formulations for these efforts, depending on the load and the aperture angle

Methodologies for Designing and Developing New Concepts in Vertical Transportation

Escalator and moving walkway are multibody systems with a design of more than a century. Developed methodology allows studying and improving any subsystem of both systems. In addition, new concepts can be developed and tested without the necessity and cost of a real construction. CITEF (Railway Technologies Research Centre) has been modelling escalators for more than four years. Several complex and innovative models has been developed to characterize static, kinematic and dynamic escalator behaviour. The high number of mechanical elements that are part of escalators complicate modelling task. In this way, methodologies and tools have been developed in order to automate these task and saving computational and time costs. Developed methodologies have been validated with the results of comparing real measurements and simulated outputs from a dynamic model

Rheological behaviour of submicron mullite-carbon nanofiber suspensions for Atmospheric Plasma Spraying coatings

Mullite is widely used as a structural material for applications like thermal and environmental barriers coatings. For some of these applications, thermal spray is a suitable technique due to its fast production time and versatility. This makes mullite a very interesting coating material for thermal spray industry. In the present work, the viability to produce coatings by thermal spray using mullite-CNFs agglomerated powders is analyzed. The stability of aqueous mullite and mullite-CNFs suspensions was studied in terms of zeta potential and rheological behaviour of concentrated slurries. Slurries were optimized in terms of dispersant concentration and solid content. The optimized suspensions were used for the granules preparation by spray drying technology. The obtained granules were characterized through the determination of particle size distribution and shape factor by field emission scanning electron microscopy and laser scattering. These granules were used to form the coatings by Atmospheric Plasma Spraying which were characterized by evaluating the composition, structure, shape, and thickness

Methodology for Flexible Modeling of Escalator Multibody Systems

This paper presents some particular escalator modelling features and methodologies developed to dramatically reduce time cost regarding two aspects: computation and implementation. CITEF (Railway Technologies Research Centre) has been modelling escalators for three years. During this time, several static, kinematic and dynamic escalator models have been developed and improved. In parallel, automation tools mainly intended for saving time cost have been described in a piecemeal fashion. These tools are based on the repetitiveness of the bodies, and a definition of the joints, forces and loops, and on the cyclic movement of most of the bodies involved. In addition, noise signals have been programmed from MATLAB to simulate them in SIMPACK software in order to apply robust design methods for studying and optimizing certain parameters

Simulación y modelización de las escaleras mecánicas como vía para la mejora del confort de los pasajeros y la disminución de costes

La escalera mecánica lleva más de un siglo entre nosotros, sin apenas variar su diseño de forma notoria. La simulación mecánica de este sistema multicuerpo, asignatura pendiente en la actualidad, ahorrará tiempo y dinero frente a los experimentos tradicionales. En esta línea, CITEF está desarrollando una serie herramientas de mejora del diseño basadas en modelos estáticos, cinemáticos y dinámicos para la simulación del comportamiento de la escalera mecánica convencional así como para el desarrollo y análisis de nuevos diseños. Estas herramientas permitirán el estudio de variables como son la velocidad y la aceleración del peldaño, así como los valores de tensión de la cadena y de reacción de los rodillos. Con los resultados obtenidos se podrán inferir mejoras que supongan una disminución del coste del conjunto de la escalera y del coste de mantenimiento, así como un aumento del confort del usuario

Flow disposicional en salvamento deportivo : una aproximación desde la teoría de la autodeterminación

This study analyzed the relationships between perceived motivational climates, psychological mediators, selfdetermined motivation and dispositional flow in lifesaving sport. The study variables also examined differences according to gender, age and daily practice time. A total of 283 athletes with a mean age of 17.27 years (SD = 3.36) who completed the Perceived Motivational Climate in Sport Questionnaire-2 (PMCSQ-2), the Motivational Mediators in Sport Scale (EMMD), the Sport Motivational Scale (SMS) and the Dispositional Flow Scale (DFS) participated in the study. The results revealed that perceived task and ego-involving motivational climates, perceived competence and autonomy, and selfdetermined motivation positively predicted dispositional flow with 50% of the variance explained. Men reported higher scores in autonomy, competence and dispositional flow than women did. Older athletes displayed a higher level of perceived autonomy than younger ones. The results are discussed in connection with the motivational factors important to improving dispositional flow

Metodi per migliorare le scale mobili = Methods for improving escalators

This paper presents several methods to search for improvements in escalator design. Escalators were invented more than a century ago. During this time several features have been developed although most of them have not shown any clear advantage over the conventional device. This mechanism is becoming a ¿commodity¿ product. CITEF is using tools to simulate and to analyze the static, kinematic and dynamic behaviour of this multibody system. We have used MATLAB, CATIA and SIMPACK software. In addition, a life prediction model based on dynamic results has been developed

Methoden zur Verbesserung von Fahrtreppen

This paper presents several methods to search for improvements in escalator design. Escalators were invented more than a century ago. During this time several features have been developed although most of them have not shown any clear advantage over the conventional device. This mechanism is becoming a ¿commodity¿ product. CITEF is using tools to simulate and to analyze the static, kinematic and dynamic behaviour of this multibody system. We have used MATLAB, CATIA and SIMPACK software. In addition, a life prediction model based on dynamic results has been developed

Methods for Improving Escalators

This paper presents several methods to search for improvements in escalator design. Escalators were invented more than a century ago. During this time several features have been developed although most of them have not show nany clear advantage over the conventional device. This mechanism is becoming a "commodity" product.C1TEF is using tools to simulate and to analyze the static, kinematic and dynamic behavior of this multibody system. We have used MATLAB, CATIA and SIMPACK software. In addition, a life prediction model based on dynamic results has been developed

Mejora de un diseño de más de 100 años. Nuevos conceptos en escaleras mecánicas

El presente trabajo persigue la mejora e innovación en el diseño de las escaleras mecánicas, cuya arquitectura básica lleva más de un siglo funcionando con tecnologías electromecánicas alcanzables por todos los fabricantes. Durante este tiempo, se han ido haciendo mejoras continuas en los diversos aspectos de las escaleras móviles aunque ningún sistema patentado posteriormente presenta ventajas claras frente al inicial, Cien años con una arquitectura funcionando sin cambios novedosos hace que este producto se esté convirtiendo en un “commodity”. El CITEF empleará herramientas que permitan simular y analizar el comportamiento estático, cinemático y dinámico de un sistema multicuerpo de este tipo. Se emplearán herramientas tales como MATLAB, CATIA y SIMPACK. Adicionalmente, se desarrollará un modelo de predicción de vida basado en los resultados dinámicos