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Introduction/purpose: The dynamic analysis of a seismic response of a concrete vault dam is a complex problem in which the representation of the behavior of the material requires some form of a nonlinear model, especially if the concrete is subjected to a significant stress load of the ground. In the case of large movements of the latter, large cracks may form in some areas of the dam, especially at the base of the dam and near sudden changes in geometry. Methods: This analysis was based on a numerical simulation of the dynamic effect. This work was carried out using the finite element method with the ANSYS 12.1 program. The dam was modelled in two dimensions. Four types of analysis were performed: static analysis, modal analysis, seismic analysis under excitation of two accelerograms (Asnam 1980 and Boumerdes 2003), and spectral analysis. Results: This analysis showed the vulnerability of the Brezina dam to the Boumerdes earthquake with high stresses at the base of the structure. Conclusions: Based on this study, it was concluded that if the Brezina dam suffers an earthquake of a greater intensity than that of Boumerdes, this will cause structural damage and cracks that will compromise the dam’s watertightness as well as its durability. [ABSTRACT FROM AUTHOR]

Introduction/purpose: This paper presents a numerical study of the forced dynamic behavior of a functionally graded beam subjected to a harmonically varying transversely concentrated moving force using a higher-order shear deformation theory. Methods: The governing equations are derived using Hamilton's principle. These equations are then transformed into the weak form using the Galerkin method. The problem is solved using the finite element method by developing a three-node finite element with four degrees of freedom per node. The Newmark beta method is chosen for the time integration and the Gauss method for the spatial integration. Results: The effects of several parameters were investigated, including the slenderness ratio, the material index, foundation stiffness, velocity and the frequency of the moving load. Good agreement was observed with the results obtained from the literature. Conclusion: This study illustrates the importance of using a higher order theory in the case of short beams and clearly shows the change in the behavior of the FGM beam as a function of different parameters. [ABSTRACT FROM AUTHOR]

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This research focuses on assessing the mechanical strength feasibility of utilizing composite materials in the design of slotted flaps as a replacement for isotropic materials. Modern computational capabilities and software tools enable the analysis of both anisotropic and isotropic materials. However, it is imperative to consider several factors to ensure that the computational model accurately mirrors real-world scenarios. In the context of composite materials, this necessitates the comprehensive integration of anisotropic properties such as Young's modulus in different orientations, Poisson's coefficients, fiber orientation, and ply stacking. Additionally, precise delineation of each boundary condition and exploration of various simulation conditions are vital to prevent biases. To validate the developed models, they are rigorously compared with laboratory tests, establishing a robust basis for the obtained results. [ABSTRACT FROM AUTHOR]

El presente trabajo propone el uso de diseño generativo para el modelado de un pedal de freno de un automóvil, generando una propuesta de diseño funcional, segura y ligera; reduciendo lo más posible la cantidad de material, pero manteniendo una buena resistencia mecánica. Para esta investigación, se hizo uso del módulo de diseño generativo del software CAD Autodesk Fusion 360®. Este software emplea una serie de algoritmos y los parámetros definidos por el usuario, y en base a ello, generar una serie de propuestas de diseño del pedal. Como resultados de la investigación, se obtuvieron dos propuestas del pedal de frenado. El análisis por elementos finitos (FEM) mostro esfuerzos mecánicos de hasta un 86.07% por debajo del esfuerzo último del material de fabricación (aluminio 6061-T4). Adicionalmente, se obtuvo un factor de seguridad de hasta 4.8, con una reducción de la masa del pedal de hasta 16.67%. Los resultados mostraron que diseño generativo es una buena herramienta para explorar nuevas ideas y conceptos que fomentan la innovación en el diseño automotriz, logrando diseños funcionales, resistentes y con bajo consumo de material.

Lamb waves are extensively used in non-destructive tests (NDT) to detect corrosion and another defects in thin plates. Several NDT methods require to compute the phase velocity of the Lamb wave, which depends on the frequency. In this work we show the potential of the combination of the phase velocity method (PVM) with the finite element method (FEM) for computing the phase velocity dispersion curve of an ultrasonic pulse traveling in a transversally annular isotropic thin plate. The FEM-PVM is based on the numerical solution of the wave propagation equations for several selected frequencies. To solve these equations, a second order difference scheme is used to discretize the temporal variable, while spatial variables are discretized with FEM. The open software FreeFem++ is used with quadratic triangular elements to compute the displacements. The phase velocity for a given frequency is obtained from the computed displacements at few points on the top of the plate. Repeating the procedure for several frequencies we compute a sample of points that are fitted to obtain an approximation of the phase velocity dispersion curve. A deeper understanding on the behavior of the phase velocity dispersion curve with respect to the plate curvature is obtained as result of an extensive experimentation with annular isotropic plates of two materials. [ABSTRACT FROM AUTHOR]

Introducción: El método elementos finitos ha ganado en popularidad para determinar los parámetros de mecánica de la fractura, pero este tipo de análisis numérico arriba a resultados precisos o no, en dependencia de la calidad del modelo y el procedimiento de implementación de los métodos establecidos. Objetivo: Implementar y validar el cálculo del factor de intensidad de tensiones y la integral J a través de los métodos de extrapolación de desplazamientos, integral de dominio y de integral de interacción, mediante la modelación por elementos finitos de problemas de piezas fisuradas en 2D y 3D. Materiales y Métodos: Se calcularon el factor de intensidad de tensiones y la integral J, en una probeta compacta fisurada y una placa con grieta semicircunferencial superficial, mediante modelos de elementos finitos en 2D y 3D y estos resultados se comprobaron respecto a los obtenidos mediante expresiones analíticas publicadas. Resultados y Discusión: El error de los resultados que brindan los modelos de elementos finitos no supera el 3 % para los modelos bidimensionales y el 7 % para los tridimensionales, lo que demuestra su calidad y precisión. Conclusiones: Se considera validada la implementación del cálculo de los parámetros de mecánica de la fractura, lo que posibilita extender en el futuro su empleo a construcciones y equipos que presenten agrietamiento en servicio.

In this document we will study and solve the nonlinear partial differential equation, with initial conditions for vehicle entry that serves to model the dynamics of traffic flow. To find a numerical solution to the dynamics that govern the behavior of traffic flow, the Finite Element Method in a spatial dimension was used. In accordance with the temporal dynamics, simulations were developed to know the flow in terms of time. The numerical solution is interesting for predicting the number of vehicles at the entrance to a high-flow road. Some theorems are enunciated that guarantee the existence of the solution and the uniqueness is given by the boundary conditions. [ABSTRACT FROM AUTHOR]

In this study, porous carbon has been prepared through potassium hydroxide (KOH) activation of coconut fiber (CF) and subsequent carbonization in the presence of an inert gas. The activated carbons (AC) were prepared via carbonization of the precursor at different temperatures. Subsequently, their electromagnetic wave absorption (EMWA) performance was investigated at X-band frequency. The phase crystallinity, porous features, and degree of graphitization of the activated carbons were studied using XRD, nitrogen adsorption/desorption isotherm, and Raman spectroscopy, respectively. Using the BET method, the activated carbon prepared at 750 °C displayed a high specific surface area of 602.9 m2 g−1 and an average pore size of 6 nm, which confirms the extant of mesopores. The EMWA was studied using COMSOL Multiphysics software based on the finite element method. Results show that the activated carbon prepared at 750 °C attained an optimal reflection loss of −45.6 dB at 10.96 GHz with a corresponding effective bandwidth of 3.5 GHz at a thickness of 3.0 mm. In conclusion, this study interestingly shows that porous carbon obtained from coconut fiber has great potential for attenuating electromagnetic waves. Resumen: En este estudio, el carbono poroso se ha preparado mediante la activación con hidróxido de potasio (KOH) de la fibra de coco (CF) y la posterior carbonización en presencia de un gas inerte. Los carbones activados (AC) se prepararon mediante carbonización del precursor a diferentes temperaturas. Posteriormente, se investigó su rendimiento de absorción de ondas electromagnéticas (EMWA) en la frecuencia de banda X. La cristalinidad de fase, las características porosas y el grado de grafitización de los carbones activados se estudiaron utilizando XRD, isoterma de adsorción/desorción de nitrógeno y espectroscopia Raman, respectivamente. Empleando el método BET, el carbón activado preparado a 750 °C mostró una alta superficie específica de 602,9 m2 g−1 y un tamaño de poro medio de 6 nm, lo que confirma la existencia de mesoporos. La EMWA se estudió utilizando el software COMSOL Multiphysics basado en el método de elementos finitos. Los resultados muestran que el carbón activado preparado a 750 °C alcanzó una pérdida de reflexión óptima de −45,6 dB a 10,96 GHz con un ancho de banda efectivo correspondiente de 3,5 GHz con un grosor de 3,0 mm. En conclusión, este estudio muestra de manera interesante que el carbono poroso obtenido de la fibra de coco tiene un gran potencial para atenuar las ondas electromagnéticas.

Introduction: The finite element method has become popular to determine fracture mechanics parameters, but this type of numerical analysis may or not lead to accurate results, depending on the model quality and the implementation of the established methods. Objective: Implement and validate the calculation of the stress intensity factor and the J integral through the displacement extrapolation, domain integral and interaction integral methods, through finite element modeling of cracked part problems in 2D and 3D. Materials and methods: The stress intensity factor and the integral J were calculated in a compact cracked specimen and a plate with a semi-circumferential surface crack, by means of 2D and 3D finite element models, and these results were verified with those obtained by means of published analytical expressions. Results and Discussion: The error of the results provided by the finite element models does not exceed 3% for the two-dimensional models and 7% for the three-dimensional ones, which demonstrates their quality and precision. Conclusions: The implementation of the calculation of the fracture mechanics parameters is considered validated, which makes it possible to extend its use in the future for constructions and equipment that present cracking in service. [ABSTRACT FROM AUTHOR]

Current research deals with simulation of the shielding and grounding systems in a distributed power station, because of failures have occurred in it, causing damage to protection equipment, even, it has considered a future expansion. Therefore, soil resistivity and grounding resistance measurements were made using Std. IEEE 81, obtaining values up to 40.4 O-m and 986 O respectively along land and common ground points. Later, systems were modeled in ETAP; under current conditions ground resistivity value of 23.57 Om, determining a resistance of 0.588 O, and a touch voltage of 854.4 V, which exceeds tolerable values of regulations, as well as in accordance to modeling of rolling spheres for current shielding system made up of a dipole type lightning rod; It was determined that 3 generators are outside the protection zone and at doing expansion, this set of protections would not provide the necessary guarantees for proper functioning of plant. Improvements to the system were proposed; they were verified by simulation; obtaining grounding values of 0.414 O and touch voltage of 589 V which are within permissible limits, in addition to designing expansion. [ABSTRACT FROM AUTHOR]

Copyright of Técnica Industrial: Revista Cuatrimestral de Ingeniería, Industria e Innovación is the property of Fundacion Tecnica Industrial and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Técnica Energía is the property of Centro Nacional de Control de Energia CENACE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Support vessels for platforms in the oil industry have operation versatility and capacity for structural modification. This article presents a proposal for the installation of a crawler crane on the main deck of a platform support vessel, which will carry out offshore maintenance operations. This proposal includes the results of the structural analysis of the main deck, considering its reinforcement with two NVA36 beams. This structural analysis incorporates the integrity of the main deck, taking into account the crane and loads through finite element method (FEM) models. The obtained results show that the main deck requires the proposed reinforcement to decrease the maximum stresses of von Mises up to 218.71 MPa for the structure of the main deck and 201.67 MPa for the reinforcement beams. These maximum stresses do not exceed the allowable and yield stresses of the main deck material. The reinforcement of the main deck that supports crawler crane allows safe operation of the offshore support vessel. [ABSTRACT FROM AUTHOR]

En el presente artículo se presentan los resultados de las simulaciones del campo electromagnético en la Línea de Transmisión de 500 kV San Rafael – El Inga mediante el Método de los elementos finitos en el programa FEMM. Los resultados obtenidos son contrastados con las mediciones realizadas con instrumentos de medición en el campo. Con ayuda de AutoCAD se levantaron los diseños de las estructuras a escala 1:1, mismos que fueron exportados al programa FEMM para realizar las simulaciones correspondientes del campo electromagnético emitido por las líneas de transmisión de extra alto voltaje. Se consideraron las estructuras ubicadas en diferentes altitudes sobre el nivel del mar y se simularon diferentes alternativas de la geometría de las torres de la línea de transmisión para determinar los valores del campo eléctrico y magnético hasta obtener una configuración adecuada que presente valores bajos del campo electromagnético. Finalmente, mediante las simulaciones realizadas en el programa FEMM se muestra el diseño adecuado resultante para una línea de transmisión de extra alto voltaje.

Los buques de apoyo para plataformas de la industria petrolera tienen versatilidad de operación y capacidad de modificación estructural. Este artículo presenta una propuesta de instalación de una grúa sobre orugas sobre la cubierta principal de un buque de apoyo a plataformas petroleras, el cual realizará operaciones de mantenimiento en mar adentro. Esta propuesta incluye los resultados del análisis estructural de la cubierta principal, donde se considera el refuerzo con dos vigas NVA36. Este análisis estructural incorpora la integridad de la cubierta principal considerando la grúa y las cargas mediante modelos del método de elementos finitos (MEF). Los resultados obtenidos muestran que la cubierta principal requiere el refuerzo propuesto para disminuir las tensiones máximas de Von Mises hasta 218,71 MPa para la estructura de la cubierta principal y 201,67 MPa en las vigas de refuerzo. Estas tensiones máximas no superan las tensiones admisibles y de fluencia del material de la cubierta principal. El refuerzo de la cubierta principal que soporta la grúa sobre orugas permite la operación segura del buque de apoyo mar adentro.

The methods of modelling and simulation of casting processes are carried out by means of software. This allows a reduction of time and costs in technological tests. As fundamental part of any casting mould is the feeding system, a component of the design on which the correct filling and solidification of the part depends. The aim of this work was to evaluate the feeding system of a permanent metal mould by gravity casting to obtain an aluminum alloy piston for an internal combustion engine, using CAD/CAE software for its modelling and simulation by finite elements. A modification was evaluated, simulated and proposed to provide a viable and economical solution, obtaining a satisfactory filling and solidification cycle that minimizes the current rejects of the original mould. The simulation of the proposal is in correspondence with the experiments carried out physically. [ABSTRACT FROM AUTHOR]

A methodology based on digital rock physics is proposed for a group of tomographic images taken from a core of sandstone extracted from an oil well, considering an anisotropic model of the material during the segmentation process. The rock sample, provided by the Colombian Petroleum Institute, is composed mainly of minerals such as quartz and calcite. First, a three-dimensional model is generated from the tomographic images. Then, a finite element mesh is created considering a material model that relates density and elastic modulus with the Hounsfield scale. Finally, a parametric study of the numerical model is performed and the results are compared with the reference values. Three different tests are proposed for the evaluation of elastic properties, where the minerals are studied individually (quartz and calcite) and as a composite (sandstone). The results of these tests are compared with reference values, showing difference percentages between 3 - 10% for the elastic modulus and between 0.7 - 2.1% for the Poisson's ratio. [ABSTRACT FROM AUTHOR]

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En los últimos años se han desarrollado nuevas técnicas para el estudio de materiales, entre las cuales se destaca la técnica de indentación. Los datos experimentales logrados por esta técnica permiten la evaluación del comportamiento mecánico del material a distintos niveles microestructurales. Recientemente, los avances informáticos han permitido la evolución de herramientas que permiten evaluar y predecir el comportamiento de distintos fenómenos físicos con el desarrollo de los métodos matemáticos, entre los cuales se encuentran los llamados métodos numéricos. El presente trabajo estudia el modelado numérico por elementos finitos de la técnica de indentación para su aplicación en la estimación de la curva carga vs desplazamiento; se revisan los fundamentos de la técnica con el objeto de establecer condiciones de borde a las cuales deberá estar sujeto el modelo numérico propuesto, donde un modelo computacional representativo a la técnica de indentación esférica cumple la finalidad de validar al modelo geométrico propuesto a partir de las ecuaciones analíticas de Hertz.

Se propone una metodología basada en la física de roca digital para un grupo de imágenes tomográficas tomadas de un núcleo de arenisca extraído de un pozo de petróleo, considerando un modelo anisotrópico del material durante el proceso de segmentación. La muestra de roca, proporcionada por el Instituto Colombiano del Petróleo, está compuesta principalmente por minerales como el cuarzo y la calcita. Primero, se genera un modelo tridimensional a partir de las imágenes tomográficas. Luego, se crea una malla de elementos finitos considerando un modelo de material que relaciona la densidad y el módulo elástico con la escala Hounsfield. Finalmente, se realiza un estudio paramétrico del modelo numérico y los resultados se comparan con los valores de referencia. Se proponen tres ensayos diferentes para la evaluación de 2 propiedades elásticas, donde los minerales se estudian individualmente (cuarzo y calcita) y como compuesto (arenisca). Los resultados de estas pruebas se comparan con valores de referencia, mostrando porcentajes de diferencia entre 3 - 10% para el módulo de elasticidad y entre 0,7 - 2,1% para el coeficiente de Poisson.

Hoy en día, la fabricación aditiva (AM) hace posible la producción de piezas metálicas complejas, y el uso de la aleación de titanio conocida como Ti6Al4V con AM se ha convertido en una aplicación común en la industria. Uno de los diseños más prometedores para AM es el uso de estructuras de celosía que ofrecen piezas livianas con propiedades de alta resistencia y amortiguación. Debido a estas características, su importancia está aumentando día a día en sectores que requieren alta tecnología como el aeroespacial. En este estudio, dos especímenes de estructura de celosía 2D diferentes que tienen la misma densidad de celosía, pero uno con espesor de pared, el otro sin espesor de pared, se han producido con el método de fusión por haz de electrones y se ha experimentado su resistencia a la tracción. Comparando la deformación de ambas muestras, el espesor de la pared afecta en gran medida los valores de deformación. De acuerdo con las pruebas FEM y de tracción, las muestras con espesor de pared demostraron un comportamiento mejorado de la resistencia a la tracción. La producción se llevó a cabo con los mismos valores de los parámetros de producción. Las superficies de las fracturas se escanean con el microscopio electrónico de barrido (SEM).

The present study aims to create a patient-specific hand model to simulate the passive rehabilitation on the index finger, quantifying the flexor digitorum profundus (FDP) tendon excursion and the stress experienced during simulated flexion. The computational model used in this analysis was created from an unknown patient dataset available in the Embodi3d online library. The segmentation, three-dimensional reconstruction, and modeling of the structures involved were performed using Materialise Mimics and Rhino3D. The FDP tendon excursion and stress values present in the model were calculated in the ANSYS environment. Based on the finite-element simulation, the FDP tendon presents an excursion of 10.1 mm during passive postoperative flexion. The highest-stress values were observed between the pulleys-FDP tendon contact surfaces. In particular, the pulley A1 exhibited the maximum principal stress of the model with a 58.7 MPa. The pulley A3 showed the same stress distribution pattern that A1 Pulley, but with the lowest values. The FDP Tendon excursion obtained is consistent with the results reported in the literature, which vary from 8 to 11 mm. The stress values found in the model explain the importance of the pulley mechanism keeping the FDP tendon attached to the finger bone during the range of motion experienced. The silico model proposed may potentially be used in the assessment of new medical device proposals in the field of hand reconstructive surgery. [ABSTRACT FROM AUTHOR]

A comprehensive analysis of the elasto-plastic behavior of ARMCO iron sheets undergoing severe plastic deformation (SPD) by constrained groove pressing (CGP) was carried out via the finite element method (FEM). Parameters such as die geometry and coefficient of friction were considered to study its effects on the elasto-plastic response of the material. For this ANSYS workbench was used for FEM simulations. The results showed that the parameters studied influence in different ways not only the strain achieved but also the strain distribution through the sheet. [ABSTRACT FROM AUTHOR]

This paper presents the design of a tuned mass damper (TMD) for vibration control of a simply supported metal beam. Considering the mechanical properties of commercial springs and magnetic dampers, and applying the finite element method, the feasibility of couple a TMD that allow to reduce vibrations in the beam was evaluated. This paper describes the beam mechanical properties, as well as the characteristics of the tuned mass damper. These results can be used in construction of dynamic models that promote the experimental study of structures. The equations proposed by Deng Hartog were used to identify adequate stiffness and damping. Finally, it was evaluated the performance of the TMD in vibration control under impact excitation conditions. With the implementation of this device, were obtained reductions of more than 90%. [ABSTRACT FROM AUTHOR]

Un análisis estructural por medio del método de elementos finitos es realizado a una embarcación tipo CPV (Coastal Patrol Vessel) que es sometida a una carga de slamming. Se realizó el diseño estructural siguiendo el Reglamento High Speed Craft de Germanicher Lloyd (GL), así mismo las cargas de slamming fueron aplicadas de acuerdo a lo que contempla este reglamento a lo largo de la longitud de la embarcación. El modelamiento de la geometría fue hecho utilizando un software CAD, posteriormente mediante el uso de un paquete de simulación comercial de elementos finitos (ANSYS) se realizó el análisis respectivo, para ello se define previamente una condición de frontera apropiada, se obtiene las distribuciones de esfuerzos y deformaciones en toda la estructura. Finalmente se comparó estos resultados con los criterios de aceptación de la Casa Clasificadora GL. Palabras clave: Slamming, método de elementos finitos, esfuerzos, deformaciones, criterio de aceptación, CPV, análisis

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Los mini implantes dentales son tornillo que se insertan temporalmente en el maxilar de un paciente como anclaje para generar una fuerza y mover una pieza dental. Este artículo presenta el diseño de un dispositivo para la determinación del torque de inserción de mini implantes dentales autoperforantes en una probeta de hueso porcino. El mecanismo propuesto no requiere de accionamiento eléctrico. La entrada de potencia se da mediante el torque resultante del efecto del peso actuando sobre una polea a través de una cuerda. El dispositivo está compuesto por tres transmisiones para la transformación de movimiento: transmisión por polea, engranajes cónicos de dientes rectos, y un mecanismo piñón-cremallera. Este último permite el avance longitudinal al tiempo que se da la rotación de la herramienta, haciendo posible el rompimiento del hueso e inserción del mini implante. A partir de la fuerza de inserción y de la velocidad recomendada para la transmisión piñón-cremallera, y teniendo en cuenta la eficiencia de cada estación de transmisión, se estableció la potencia de accionamiento del dispositivo. Para el caso de estudio se diseñó un portaherramientas adecuado para mini implante marca HUBIT Co x 1.4mm. Se consideraron tanto el diseño por fatiga como el diseño estático para el dimensionamiento de los ejes. El análisis de movimiento realizado permitió verificar que no existe interferencia entre ninguna de las piezas en contacto, permitiendo el avance del tornillo mediante la inclusión de un cuñero deslizante.

Actualmente, a nivel mundial las energías alternativas han tomado gran importancia en las diversas aplicaciones relacionadas con el desarrollo del sector energético, entre las cuales podemos mencionar la energía solar, eólica, hidráulica, geotérmica y mareomotriz. Una nueva tecnología que aprovecha la energía cinética de la corriente de agua en canales naturales y/o artificiales e inclusive de las corrientes marinas son las turbinas hidrocinéticas. En este trabajo, se presenta un estudio de los diferentes métodos numéricos que pueden ser de utilidad para diseñar, analizar y optimizar sistemas de generación energética a partir de turbinas hidrocinéticas.

Finite element (FEM) based software is frequently used in practice for tunnel design, alongside the traditional analytical and empirical solutions. Design is not the only challenge in this kind of projects, there are other important factors such as considering what is necessary to develop an efficient construction plan under a schedule and foreseeing possible changes that modify the original design. The use of two-dimensional (2D) FEM is one of the main tools used in the industry. However, 2D results yield not an entirely accurate analysis, since the behaviour of the infrastructure is considered as threedimensional (3D). This paper presents nomographs and a 3D and 2D relationship, to rapidly estimate values of elastic 3D and 2D displacements produced in the periphery of a deep circular tunnel, inside soils of different rigidities. Graphics given correspond to five different radii and for a 100 m excavation length. Nomographs were obtained from RS3© and RS2© FEM simulations and according to the elastic theory. Geotechnical parameters correspond to a constant friction angle, cohesion and soil specific weight. FEM analysis was made using the Mohr-Coulomb model, considering isotropic conditions. [ABSTRACT FROM AUTHOR]

Mini dental implants are screws that are temporarily inserted into a patient's jaw as an anchor to generate force and move a tooth. The design of a device for the determination of the insertion torque of mini self-drilling dental implants in a porcine bone specimen is presented. The proposed mechanism does not require electric drive. The input power is given by the torque resulting from the effect of weight acting on a pulley through a rope. The device consists of three transmissions for motion transformation: transmission by pulley, bevel gear with straight teeth, and a rack-and-pinion mechanism. The latter allows the longitudinal advance while the rotation of the tool occurs, making possible the bone breaking and the insertion of the mini implant. The insertion force and the recommended speed for rack-and-pinion transmission, in addition to the efficiency of each transmission station were considered for calculating the input drive power of the device. For the case study, a tool holder suitable for mini implant brand HUBIT Co x 1.4mm was designed. Both cumulative fatigue and static designs were considered. A motion analysis for the in-contact moving parts allowed verifying that no interference is present in the proposed design. Linear motion of the screw is achieved by a sliding cotter. [ABSTRACT FROM AUTHOR]

In this study, a novel technique for multiple damage detection of structures using modal characterization to evaluate the dynamic response of the structure given a damage model is investigated. The damage identification problem is seen as an optimization problem to be solved using a firefly optimization algorithm. The objective function is based on a numerical damage model that considers the modal response of the structures. We show some implementation details and discuss the obtained results for a benchmark problem used to assess the performance of the method and its advantages for structural health monitoring. [ABSTRACT FROM AUTHOR]

Nowadays, the alternative energies have reached a great worldwide importance in the different applications related to the development of the energy sector, among which the solar energy, wind energy, hydraulic energy, geothermal energy and seawater energy can be named. A new technology that uses the kinetic energy from the water currents in natural and/or artificial channels and even from sea currents are the so-called hydrokinetic turbines. In this study, a review of the state-of-the-art referring to several numerical methods that can be useful when implemented to design, analyze, and optimize energy generation systems from hydrokinetic turbines is presented. [ABSTRACT FROM AUTHOR]

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Un modelo de elementos finitos no hidrostático integrado en la profundidad para la propagación y transformación del oleaje en zonas costeras fue desarrollado con suceso a partir del modelo hidrostático SisBahia®. El modelo utiliza elementos finitos cuadrilaterales cuadráticos para la aproximación de las velocidades horizontales y elementos finitos cuadrilaterales lineales para la aproximación de las elevaciones de la superficie del agua y las presiones no hidrostáticas. El modelo es verificado con una solución analítica y validado usando datos experimentales. Al no requerir del uso de mallas intercaladas el presente modelo puede ser usado en mallas no estructuradas de elementos finitos.

El presente artículo describe la metodología utilizada en la evaluación de tensiones equivalentes en recipientes a presión mediante el método de elementos finitos. Con base en las consideraciones resultantes, se diseñó una escotilla de inspeccióny se realizaron comprobaciones analíticas por medio de técnicas de simulación por computador. Esto generó puntos de comparación y un estudio sistemático con el fin de comprobar el comportamiento de las fuerzas resultantes en función de las modificaciones geométricas. También se definió un modelo a partir de tres propuestas de Manhole. Las configuraciones de escotilla de inspección responden a los formatos circular, elíptico-longitudinal y elíptico-transversal. Así, fue comprobado el trazado de tensiones sobre el objeto de estudio y se definió un procedimiento más incluyente en comparación con el método convencional, el cual se basa en expresiones de cálculo simplificadas.

En este trabajo se presentan los resultados de un análisis numérico llevado a cabo para la determinación del Factor de Intensidad de Tensiones en Modo Mixto, KI y KII, correspondiente al caso típico de una presa de hormigón fisurada sometida a una acción sísmica. El modelo numérico se ha implementado en el código comercial de elementos finitos Abaqus/Standard. La geometría adoptada se corresponde a la presa de Koyna, con la salvedad de que se ha incorporado una fisura paralela al plano horizontal. Con la finalidad de evaluar la importancia de garantizar un buen sellado de la fisura, mediante la inyección de resinas epoxis, se ha realizado un segundo estudio paramétrico en el que se ha considerado el sellado parcial de la fisura. Los resultados del estudio permiten establecer cuáles son las fisuras que más comprometen la integridad estructural de la presa frente a acciones sísmicas.

In this paper, the three-dimensional simulation of the indirect cold extrusion of aluminum is made, in which the structural static module of the ANSYS program is used. The behavior of a circular cross-section bar subjected to indirect extrusion with a square punch is studied to evaluate the characteristics of the process, varying the roundness of the punch and the coefficient of friction. To carry out the study, investigations were made about the process of forming the indirect extrusion with which the object described above was raised, which was developed using the finite element method showing as results that the indirect extrusion load is greater as the punch travels. In addition, it is concluded that the behavior of the equivalent effort of Von Mies in the work billet remains constant around the head of the punch as it penetrates the billet. [ABSTRACT FROM AUTHOR]

The electronic states of a GaAs elliptic quantum ring embedded in AlxGa1-xAs matrix are investigated by mean of effective mass approximation. The quantum ring is built with rectangular cross section (radial direction). The Schrödinger equation is solved by using finite element method. In angular direction, the amplitude of altitude is modulated, it lets to model quantum dots in the quantum ring. The electron energies are reported as a function of size ring, for both the lengths of the ellipses in the x y plane and their height (z-axis). [ABSTRACT FROM AUTHOR]

In this paper, the results of a numerical analysis to obtain the stress intensity factor in mixed mode, KI and KII, in a cracked concrete dam submitted to seismic loads are presented. The numerical model was implemented in the commercial finite element code Abaqus/Standard. Koyna dam geometry was used, including a crack parallel to the horizontal plane. In order to evaluate the importance of guaranteeing an adequate crack sealing using epoxy resin, a second parametric study was done considering partial crack sealing. The study results allow determining the cracks that endangered the dam structural integrity under seismic loads. [ABSTRACT FROM AUTHOR]

En este artículo se emplea la corriente y la impedancia de secuencia negativa como indicadores de fallas de cortocircuito entre espiras de un motor de inducción tipo jaula de ardilla. También se analiza el efecto que tienen los desequilibrios de tensión y los diferentes niveles de carga en dichos parámetros de diagnóstico, los cuales se calcularon a partir de datos obtenidos de simulaciones por medio del Método de Elementos Finitos (MEF) y experimentos de laboratorio.