Examinando por Materia "Finite element method"
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Ítem A Fixed Grid method for hyperelastic models in large strain analysis using the level set method(Universidad EAFIT, 2014) Ramírez Benítez, William Alberto; García Ruíz, Manuel JulioA Fixed Grid Finite Element Method (FGFEM) in addition to a Mooney-Rivlin hyperelastic model is introduced. This method uses the mixed finite element formulation to treat the elements, but classifying these in a fixed cartesian grid that is superimposed over the model geometry -- In order to do this, the boundary tracking is achieved by solving the level set equation -- A numerical extrapolation of the displacement field from the solid domain to the entire fixed grid domain is done -- The system of equations are solved by the use of an incremental Newton-Raphson scheme -- Finally, some numerical examples are implemented and good convergence results are obtained for the displacement field, showing that FGFEM for the hyperelastic model is suitable for mechanical problems undergoing large strains and large displacementsÍtem Accelerated Thermal Simulation for Three-Dimensional Interactive Optimization of Computer Numeric Control Sheet Metal Laser Cutting(American Society of Mechanical Engineers (ASME), 2018-03-01) Mejia D.; Moreno A.; Arbelaiz A.; Posada J.; Ruiz-Salguero O.; Chopitea R.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEIn the context of computer numeric control (CNC)-based sheet metal laser cutting, the problem of heat transfer simulation is relevant for the optimization of CNC programs. Current physically based simulation tools use numeric or analytic algorithms which provide accurate but slow solutions due to the underlying mathematical description of the model. This paper presents: (1) an analytic solution to the laser heating problem of rectangular sheet metal for curved laser trajectories and convective cooling, (2) a graphics processing unit (GPU) implementation of the analytic solution for fast simulation of the problem, and (3) an integration within an interactive environment for the simulation of sheet metal CNC laser cutting. This analytic approach sacrifices the material removal effect of the laser cut in the favor of an approximated real-time temperature map on the sheet metal. The articulation of thermal, geometric, and graphic feedback in virtual manufacturing environments enables interactive redefinition of the CNC programs for better product quality, lower safety risks, material waste, and energy usage among others. The error with respect to finite element analysis (FEA) in temperature prediction descends as low as 3.5%. Copyright © 2018 by ASME.Ítem Algunas consideraciones del modelo bidominio basado en el método de volúmenes finitos(Universidad EAFIT, 2014) González Galeano, Andrei Alain; Gil Gómez, Javier Hernán; Villegas Gutiérrez, Jairo AlbertoEn este trabajo se estudia la actividad eléctrica cardíaca por medio del modelo del bidominio, el cual, describe el comportamiento eléctrico del tejido cardíaco, basado en el flujo de corriente, la distribución del potencial eléctrico y la conservación de carga y corriente [7], para esto se utiliza el esquema de volúmenes finitos construido sobre mallas rectangulares, donde se realiza un análisis cualitativo de acuerdo a las simulaciones realizadas -- La discretización se enfocará en los algoritmos existentes para ecuaciones elípticas y parabólicas donde su convergencia estará garantizada por la teoría clásica -- En general el modelo de los volúmenes finitos involucra los siguientes pasos (42): a) Descomposición del dominio en volúmenes de control -- b) Formulación de las integrales sobre cada volumen de control -- c) Aproximación de las integrales por integración numérica -- d) Aproximación de las derivadas por algún esquema numérico como el de Euler -- e) Montaje y solución del sistema algebraico discretoÍtem Análisis de choques en materiales compuestos(Universidad EAFIT, 2007) Gutiérrez Restrepo, Sebastián; López Zapata, Carlos EduardoÍtem Análisis y comparación entre el proceso de centrifugado e inyección para la fabricación de piezas en Zamac(Universidad EAFIT, 2008) Gallego Alzate, Andrés Felipe; Paniagua Villa, Marco AurelioÍtem Analysis of vibrations in a plate using interferometric methods(SPIE-INT SOC OPTICAL ENGINEERING, 2004-01-01) Rueda, E.; Angel, L.; Velasquez, D.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn this work some frequencies and modes of vibration of a thin plate were determined using interferometric methods like: real-time holographic interferometry, time-average holographic interferometry, digital speckle pattern interferometry DSPI. And the results obtained are compared with those obtained with the program of finite elements COSMOS.Ítem Aplicación de una herramienta de ingeniería asistida por computador para el análisis unidimensional de tornillos de extrusión de termoplásticos(Universidad EAFIT, 2005) Bernal Sierra, Luis Felipe; Rodríguez Arroyave, Carlos ArturoÍtem Aplicación del análisis de elementos finitos a la predicción de la geometría final de platos procesados por monococción(Universidad EAFIT, 2005) Arango Londoño, Nolasco; López Rendón, Nelson; Carvajal, Leonardo; Restrepo Ochoa, Jorge LuisÍtem Aplicaciones de la biónica en proyectos de diseño mecánico(Universidad EAFIT, 2010) Ferrer Gómez, Carolina; Otálvaro Guzmán, Viviana; oÍtem Aproximación general al comportamiento del campo de onda sísmico en un medio homogéneo aplicando el método de los elementos finitos(Universidad EAFIT, 2018) Cano Uribe, Leonardo; Mosquera Ampudia, Santhier Stiwar; Villegas Gutiérrez, Jairo Alberto; Castaño Bedoya, Jorge IvánÍtem Aspect ratio- and size-controlled patterned triangulations of parametric surfaces(ACTA PRESS ANAHEIM, 2007-01-01) Ruiz, Oscar E.; Pena, Sebastian; Duque, Juan; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEA method to produce patterned, controlled size triangulation of Boundary Representations is presented. Although the produced patterned triangulations are not immediately suited for fast visualization, they were used in Fixed Grid Finite Element Analysis, and do provide a control on the aspect ratio or shape factor of the triangles produced. The method presented first calculates a triangulation in the parameter space of the faces in which the B-Rep is partitioned and then maps it to 3D space. Special emphasis is set in ensuring that the triangulations of neighboring faces meet in a seamless manner, therefore ensuring that a borderless C2 2-manifold would have as triangulation a C0 borderless 2-manifold. The method works properly under the conditions (i) the parametric form of the face is a 1-1 function, (ii) the parametric pre-image of a parametric face is a connected region, and (iii) the user-requested sampling frequency ( samples per length unit ) is higher than twice the spatial frequency of the features in the B-Rep ( thus respecting the Nyquist principle ). As the conditions (i) and (ii) are possible under face reparameterization or sub-division and the condition (iii) is the minimum that a triangulation should comply with, the method is deemed as generally applicable.Ítem Aspect ratio-and size-controlled patterned triangulations of parametric surfaces(2007-02) Ruíz, Óscar E.; Peña, Sebastián; Duque, Juan; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEA method to produce patterned, controlled size triangulation of Boundary Representations is presented -- Although the produced patterned triangulations are not immediately suited for fast visualization, they were used in Fixed Grid Finite Element Analysis, and do provide a control on the aspect ratio or shape factor of the triangles produced -- The method presented first calculates a triangulation in the parameter space of the faces in which the B-Rep is partitioned and then maps it to 3D space -- Special emphasis is set in ensuring that the triangulations of neighboring faces meet in a seamless manner, therefore ensuring that a borderless C2 2-manifold would have as triangulation a C0 borderless 2-manifold -- The method works properly under the conditions(i) the parametric form of the face is a 1-1 function, (ii) the parametric pre-image of a parametric face is a connected region, and (iii) the user-requested sampling frequency (samples per length unit ) is higher than twice the spatial frequency of the features in the B-Rep ( thus respecting the Nyquist principle ) -- As the conditions (i) and (ii) are possible under face reparameterization or sub-division and the condition (iii) is the minimum that a triangulation should comply with, the method is deemed as generally applicableÍtem Automatic CFD analysis method for shape optimization(Universidad EAFIT, 2007) Giraldo Arias, Santiago; García Ruíz, Manuel JulioThis project presents an Automatic Computational Fluid Dynamics (CFD) analysis method for shape optimization of an aerodynamic profile -- It begins with an overview of basic concepts on shape optimization, geometry parameterization and objective functions -- It continues with an introduction to the current status of CFD simulation software and types of solvers -- Then expands to optimization based on CFD analysis -- Following, a CFD-based method to optimize aerodynamic profiles under certain restrictions and scenarios is proposed -- Finally, the code implemented to automatically modify a profile bound by a set of control points based on CFD analysis is described -- The project was developed entirely at the EAFIT University’s Applied Mechanics Laboratory in Medellin, Colombia and is part of a collaboration effort in companionship with the University of Aberta in Canada and Los Andes University in Bogota, ColombiaÍtem Biomechanics of the canine mandible during bone transport distraction osteogenesis(ASME, 2014-11-01) Zapata, Uriel; Dechow, Paul C.; Watanabe, Ikuya; Elsalanty, Mohammed E.; Opperman, Lynne A.; Zapata, Uriel; Dechow, Paul C.; Watanabe, Ikuya; Elsalanty, Mohammed E.; Opperman, Lynne A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaThis study compared biomechanical patterns between finite element models (FEMs) and a fresh dog mandible tested under molar and incisal physiological loads in order to clarify the effect of the bone transport distraction osteogenesis (BTDO) surgical process. Three FEMs of dog mandibles were built in order to evaluate the effects of BTDO. The first model evaluated the mandibular response under two physiological loads resembling bite processes. In the second model, a 5.0 cm bone defect was bridged with a bone transport reconstruction plate (BTRP). In the third model, new regenerated bony tissue was incorporated within the defect to mimic the surgical process without the presence of the device. Complementarily, a mandible of a male American foxhound dog was mechanically tested in the laboratory both in the presence and absence of a BTRP, and mechanical responses were measured by attaching rosettes to the bone surface of the mandible to validate the FEM predictions. The relationship between real and predicted values indicates that the stress patterns calculated using FEM are a valid predictor of the biomechanics of the BTDO procedures. The present study provides an interesting correlation between the stiffness of the device and the biomechanical response of the mandible affected for bone transport. Copyright © 2014 by ASME.Ítem Biomechanics of the canine mandible during bone transport distraction osteogenesis(ASME, 2014-11-01) Zapata, Uriel; Dechow, Paul C.; Watanabe, Ikuya; Elsalanty, Mohammed E.; Opperman, Lynne A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)This study compared biomechanical patterns between finite element models (FEMs) and a fresh dog mandible tested under molar and incisal physiological loads in order to clarify the effect of the bone transport distraction osteogenesis (BTDO) surgical process. Three FEMs of dog mandibles were built in order to evaluate the effects of BTDO. The first model evaluated the mandibular response under two physiological loads resembling bite processes. In the second model, a 5.0 cm bone defect was bridged with a bone transport reconstruction plate (BTRP). In the third model, new regenerated bony tissue was incorporated within the defect to mimic the surgical process without the presence of the device. Complementarily, a mandible of a male American foxhound dog was mechanically tested in the laboratory both in the presence and absence of a BTRP, and mechanical responses were measured by attaching rosettes to the bone surface of the mandible to validate the FEM predictions. The relationship between real and predicted values indicates that the stress patterns calculated using FEM are a valid predictor of the biomechanics of the BTDO procedures. The present study provides an interesting correlation between the stiffness of the device and the biomechanical response of the mandible affected for bone transport. Copyright © 2014 by ASME.Ítem Boundary Representation of Anatomical Features(2002) Ruíz, Óscar E.; Karangelis, Grigorios; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEIn Simulationen für Bestrahlungstherapieplanung und andere medizinischen und bioingenieur wissenschaftlichen Anwendungen hat man traditionellerweise die anatomischen Eigenschaften mittels volumenbasierten Techniken angezeigt -- Trotzdem, während der Bedarf an Behandlung, Organsimulation und Erzeugung von Prothese präziser wird, reicht es nicht die Menge und die Position von solchen Features zu wissen, sondern auch Detailstufen, die vergleichbar sind zu denjenigen, die man für ingenieurwissenschaftliche Techniken verwendet (finite element analysis, rapid prototyping, Herstellung, usw.) -- Dieser Artikel präsentiert Bemühungen und Ergebnisse in der Anwendung von computerunterstützten geometrischen Algorithmen auf biomedizinischen Applikationen, wobei diese Algorithmen sich ursprünglich auf die Begrenzung von Formen gerichtet haben, die auf Planarmustern von anatomischen Zielregionen basiertenÍtem Closed-form Solution of Timoshenko Frames on Elastic Winkler Foundation Using the Green's Function Stiffness Method(Universidad EAFIT, 2024) Posso Sabogal, Cristian Daniel; Molina Villegas, Juan Camilo; Ballesteros Ortega, Jorge Eliecer; Molina Villegas, Juan CamiloThis paper presents a method to obtain the exact closed-form solution for the static analysis of Timoshenko beams and frames on elastic Winkler foundation, subjected to arbitrary external loads and bending moments. The solution is derived using the Green’s Functions Stiffness Method (GFSM), a novel mesh reduction method that combines the strengths of the Stiffness Method (SM) and Green’s Functions (GFs). By incorporating the core concepts of the SM, the GFSM exhibits similarities to the Finite Element Method (FEM), including the use of shape functions, stiffness matrices, and fixed-end forces. The application of GFs facilitates the derivation of analytical expressions for displacement and internal force fields for arbitrary external loads and bending moments. Three examples are presented: a single-span beam, a two-span beam, and a one-bay, one-story plane frame on elastic Winkler foundations; which demonstrate applicability and efficacy of the method.Ítem Closed-form solution of Timoshenko frames on elastic Winkler foundation using the Green’s function stiffness method(Elsevier, 2024-10-01) Posso, Cristian; Molina-Villegas, Juan Camilo; Ballesteros Ortega, Jorge Eliecer; Universidad EAFIT; University of Central FloridaThis paper presents a method to obtain the exact closed-form solution for the static analysis of Timoshenko beams and frames on elastic Winkler foundation, subjected to arbitrary external loads and bending moments. The solution is derived using the Green’s Functions Stiffness Method (GFSM), a novel mesh reduction method that combines the strengths of the Stiffness Method (SM) and Green’s Functions (GFs). By incorporating the core concepts of the SM, the GFSM exhibits similarities to the Finite Element Method (FEM), including the use of shape functions, stiffness matrices, and fixed-end forces. The application of GFs facilitates the derivation of analytical expressions for displacement and internal force fields for arbitrary external loads and bending moments. Three examples are presented: a single-span beam, a two-span beam, and a one-bay, one-story plane frame on elastic Winkler foundations; which demonstrate applicability and efficacy of the method.Ítem Closed-form solutions for axially non-uniform Timoshenko beams and frames under static loading(Elsevier, 2024-03-23) Molina-Villegas, Juan Camilo; Ballesteros Ortega, Jorge Eliecer; Benítez Soto, Simón; Universidad EAFIT; University of Central FloridaThis paper presents the Green’s Functions Stiffness Method (GFSM) for solving linear elastic static problems in arbitrary axially non-uniform Timoshenko beams and frames subjected to general external loads and bending moments. The GFSM is a mesh reduction method that seamlessly integrates elements from the Stiffness Method (SM), Finite Element Method (FEM), and Green’s Functions (GFs), resulting in a highly versatile methodology for structural analysis. It incorporates fundamental concepts such as stiffness matrices, shape functions, and fixed-end forces, in line with SM and FEM frameworks. Leveraging the capabilities of GFs, the method facilitates the derivation of closed-form solutions, addressing a gap in existing methods for analyzing non-uniform reticular structures which are typically limited to simple cases like single-span beams with specific axial variations and loading scenarios. The effectiveness of the GFSM is demonstrated through three practical examples, showcasing its applicability in analyzing non-uniform beams and plane frames, thereby broadening the scope of closed-form solutions for axially non-uniform Timoshenko structures.Ítem A comparative computational study of blood flow pattern in exemplary textile vascular grafts(Taylor and Francis Ltd., 2018-01-01) R. VALENCIA; M. GARCÍA; J. BUSTAMANTE; R. VALENCIA; M. GARCÍA; J. BUSTAMANTE; Universidad EAFIT. Departamento de Humanidades; Centro de Estudios Urbanos y Ambientales (URBAM)Textile vascular grafts are biomedical devices and play an important role serving as a solution for the partial replacement of damaged arterial vessels. It is believed that the success of a textile vascular graft, in the healing process after implantation, is due to the porous micro-structure of the wall. Although the transport of fluids through textiles is of great technical interest in biomedical applications, little is known about predicting the micro-flow pattern and cellular transport through the wall. The aim of this work is to investigate how the type of fabric, permeability and porosity affect both the local fluid dynamics at several scales and the fluid-particle interaction between platelets in textile grafts, related with the graft occlusion. This study involves both experimental and computational tests. Experimental tests are performed to characterize the permeability and porosity according to the ISO 7198 standard. The numerical process is based on a multi-scale approach where the fluid flow is solved with the Finite Element Method and the discrete particles are solved with the Molecular Dynamic Method. The results have shown that the type of fabric in textile vascular grafts and the degree of porosity and permeability affect both the local fluid dynamics and the level of penetration of platelets through the wall, thus indicating their importance as design parameters. © 2017 Informa UK Limited, trading as Taylor & Francis Group.