Examinando por Materia "Structural optimization"
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Ítem Análisis de viabilidad para introducir al mercado antioqueño una cama canapé abatible(Universidad EAFIT, 2010) Berrío Gómez, Juan David; Gómez Salazar, Elkin ArcesioÍtem Design of structural parts for a racing solar car(SPRINGER-VERLAG BERLIN, 2017-01-01) Betancur, Esteban; Mejia-Gutierrez, Ricardo; Osorio-Gomez, Gilberto; Arbelaez, Alejandro; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)The racing solar cars are characterized by the constant pursuit of energy efficiency. The tight balance between energy inputs and consumption is the main reason to seek optimization in different areas. The vehicle weight is directly related to the energy consumption via rolling resistance of the tires. The relation between weight and energy consumption is quantified. The structural optimization techniques are studied and a series of rules is obtained to iteratively improve the shape of structural parts reducing its weight. The implementation is done in a practical case and satisfactory results are achieved. © Springer International Publishing AG 2017.Ítem Engineering design using evolutionary structural optimisation based on iso-stress-driven smooth geometry removal(2001) García, M.J.; Ruíz, O.E.; Steven, G.P.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThe main goal of Evolutionary Structural Optimisation (ESO) research has been to provide an easily applicable optimisation method for the engineering industry which assists the design process for product improvement -- Originally O was based on the concept of fully stressed structures and it is obtained by slowly removing, from a Finite Element mesh these elements that present the lowest stress value -- Following this heuristically-driven removal criteria, the initial topology evolves towards the optimum one -- Since its introduction in 1992, ESO has been developed and extended to several types of structural problems -- Initial weaknesses of ESO were (i) typically long solution times and (ii) topologies with jagged surfaces as a result of removing whole elements in the optimisation process -- These characteristics hindered its application to computer aided design and analysis -- In this investigation, these weaknesses have been addressed for 2D situations by (i) basing the stress computation on the Fixed Grid (FG) finite element method and (ii) removing material with the lowest values along iso-stress contours instead of removing whole elements -- A boundary representation (B-rep) of the structure is maintained at each iteration of the optimisation process -- Modification to the workpiece is made by identifying the stress contour lines and incorporating them into the evolving geometry -- The topological consistency of the B-rep is maintained via normalized 2D boolean operationsÍtem FEA Structural Optimization Based on Metagraphs(Springer Verlag, 2019-01-01) Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Sanchez-Londono D.; Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Sanchez-Londono D.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)Evolutionary Structural Optimization (ESO) seeks to mimic the form in which nature designs shapes. This paper focuses on shape carving triggered by environmental stimuli. In this realm, existing algorithms delete under - stressed parts of a basic shape, until a reasonably efficient (under some criterion) shape emerges. In the present article, we state a generalization of such approaches in two forms: (1) We use a formalism that enables stimuli from different sources, in addition to stress ones (e.g. kinematic constraints, friction, abrasion). (2) We use metagraphs built on the Finite Element constraint graphs to eliminate the dependency of the evolution on the particular neighborhood chosen to be deleted in a given iteration. The proposed methodology emulates 2D landmark cases of ESO. Future work addresses the implementation of such stimuli type, the integration of our algorithm with evolutionary based techniques and the extension of the method to 3D shapes. © 2019, Springer International Publishing AG, part of Springer Nature.Ítem FEA Structural Optimization Based on Metagraphs(Springer Verlag, 2019-01-01) Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Sanchez-Londono D.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de ProcesosEvolutionary Structural Optimization (ESO) seeks to mimic the form in which nature designs shapes. This paper focuses on shape carving triggered by environmental stimuli. In this realm, existing algorithms delete under - stressed parts of a basic shape, until a reasonably efficient (under some criterion) shape emerges. In the present article, we state a generalization of such approaches in two forms: (1) We use a formalism that enables stimuli from different sources, in addition to stress ones (e.g. kinematic constraints, friction, abrasion). (2) We use metagraphs built on the Finite Element constraint graphs to eliminate the dependency of the evolution on the particular neighborhood chosen to be deleted in a given iteration. The proposed methodology emulates 2D landmark cases of ESO. Future work addresses the implementation of such stimuli type, the integration of our algorithm with evolutionary based techniques and the extension of the method to 3D shapes. © 2019, Springer International Publishing AG, part of Springer Nature.Ítem FEA Structural Optimization Based on Metagraphs(Springer Verlag, 2019-01-01) Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Sanchez-Londono D.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEEvolutionary Structural Optimization (ESO) seeks to mimic the form in which nature designs shapes. This paper focuses on shape carving triggered by environmental stimuli. In this realm, existing algorithms delete under - stressed parts of a basic shape, until a reasonably efficient (under some criterion) shape emerges. In the present article, we state a generalization of such approaches in two forms: (1) We use a formalism that enables stimuli from different sources, in addition to stress ones (e.g. kinematic constraints, friction, abrasion). (2) We use metagraphs built on the Finite Element constraint graphs to eliminate the dependency of the evolution on the particular neighborhood chosen to be deleted in a given iteration. The proposed methodology emulates 2D landmark cases of ESO. Future work addresses the implementation of such stimuli type, the integration of our algorithm with evolutionary based techniques and the extension of the method to 3D shapes. © 2019, Springer International Publishing AG, part of Springer Nature.Ítem Fixed grid finite element analysis for 3D structural problems(World Scientific Publishing Co., 2005) García, Manuel J.; Henao, Miguel A.; Ruíz, Óscar E.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEFixed Grid (FG) methodology was first introduced by García and Steven as an engine for numerical estimation of two-dimensional elasticity problems -- The advantages of using FG are simplicity and speed at a permissible level of accuracy -- Two dimensional FG has been proved effective in approximating the strain and stress field with low requirements of time and computational resources -- Moreover, FG has been used as the analytical kernel for different structural optimisation methods as Evolutionary Structural Optimisation, Genetic Algorithms (GA), and Evolutionary Strategies -- FG consists of dividing the bounding box of the topology of an object into a set of equally sized cubic elements -- Elements are assessed to be inside (I), outside (O) or neither inside nor outside (NIO) of the object -- Different material properties assigned to the inside and outside medium transform the problem into a multi-material elasticity problem -- As a result of the subdivision NIO elements have non-continuous properties -- They can be approximated in different ways which range from simple setting of NIO elements as O to complex noncontinuous domain integration -- If homogeneously averaged material properties are used to approximate the NIO element, the element stiffness matrix can be computed as a factor of a standard stiffness matrix thus reducing the computational cost of creating the global stiffness matrix. An additional advantage of FG is found when accomplishing re-analysis, since there is no need to recompute the whole stiffness matrix when the geometry changes -- This article presents CAD to FG conversion and the stiffness matrix computation based on non-continuous elements -- In addition inclusion/exclusion of O elements in the global stiffness matrix is studied -- Preliminary results shown that non-continuous NIO elements improve the accuracy of the results with considerable savings in time -- Numerical examples are presented to illustrate the possibilities of the methodÍtem A General Meta-graph Strategy for Shape Evolution under Mechanical Stress(Taylor and Francis Inc., 2019-01-01) Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Posada J.; Sanchez-Londono D.; Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Posada J.; Sanchez-Londono D.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)The challenges that a shape or design stands are central in its evolution. In the particular domain of stress/strain challenges, existing approaches eliminate under-demanded neighborhoods from the shape, thus producing the evolution. This strategy alone incorrectly (a) conserves disconnected parts of the shape and (b) eliminates neighborhoods which are essential to maintain the boundary conditions (supports, loads). The existing analyses preventing (a) and (b) are conducted in an ad-hoc manner, by using graph connectivity. This manuscript presents the implementation of a meta-graph methodology, which systematically lumps together finite element subsets of the current shape. By considering this meta-graph connectivity, the method impedes situations (a) and (b), while maintaining the pruning of under-demanded neighborhoods. Research opportunities are open in the application of this methodology with other types of demand on the shape (e.g., friction, temperature, drag, and abrasion). © 2019, © 2019 Taylor & Francis Group, LLC.Ítem A General Meta-graph Strategy for Shape Evolution under Mechanical Stress(Taylor and Francis Inc., 2019-01-01) Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Posada J.; Sanchez-Londono D.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThe challenges that a shape or design stands are central in its evolution. In the particular domain of stress/strain challenges, existing approaches eliminate under-demanded neighborhoods from the shape, thus producing the evolution. This strategy alone incorrectly (a) conserves disconnected parts of the shape and (b) eliminates neighborhoods which are essential to maintain the boundary conditions (supports, loads). The existing analyses preventing (a) and (b) are conducted in an ad-hoc manner, by using graph connectivity. This manuscript presents the implementation of a meta-graph methodology, which systematically lumps together finite element subsets of the current shape. By considering this meta-graph connectivity, the method impedes situations (a) and (b), while maintaining the pruning of under-demanded neighborhoods. Research opportunities are open in the application of this methodology with other types of demand on the shape (e.g., friction, temperature, drag, and abrasion). © 2019, © 2019 Taylor & Francis Group, LLC.Ítem A General Meta-graph Strategy for Shape Evolution under Mechanical Stress(Taylor and Francis Inc., 2019-01-01) Montoya-Zapata D.; Acosta D.A.; Ruiz-Salguero O.; Posada J.; Sanchez-Londono D.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de ProcesosThe challenges that a shape or design stands are central in its evolution. In the particular domain of stress/strain challenges, existing approaches eliminate under-demanded neighborhoods from the shape, thus producing the evolution. This strategy alone incorrectly (a) conserves disconnected parts of the shape and (b) eliminates neighborhoods which are essential to maintain the boundary conditions (supports, loads). The existing analyses preventing (a) and (b) are conducted in an ad-hoc manner, by using graph connectivity. This manuscript presents the implementation of a meta-graph methodology, which systematically lumps together finite element subsets of the current shape. By considering this meta-graph connectivity, the method impedes situations (a) and (b), while maintaining the pruning of under-demanded neighborhoods. Research opportunities are open in the application of this methodology with other types of demand on the shape (e.g., friction, temperature, drag, and abrasion). © 2019, © 2019 Taylor & Francis Group, LLC.Ítem Optimización estructural con mallas fijas y análisis de sensibilidad utilizando varias aproximaciones a los elementos de frontera(Universidad EAFIT, 2010) Ramírez Benítez, William Alberto; García Ruíz, Manuel JulioEste artículo presenta un método de optimización basado en aproximación por mallas fijas utilizando diferentes métodos para obtener la matriz de rigidez de los elementos de la frontera e implementando Optimización Estructural Evolutiva (ESO) -- En ESO, un valor de umbral de esfuerzo es calculado y los elementos que se encuentran por debajo de este son removidos -- Desafortunadamente se producen patrones de tablero de ajedrez y fronteras dentadas -- En el método de mallas fijas la representación de fronteras (B-Rep) se mantiene como una aproximación lineal a trozos -- El método IsoESO utiliza el método de mallas fijas y el material es removido cortando el material sobre la isosuperficie del valor de umbral -- Como la superficie resultante es suave, esta no contiene fronteras dentadas o patrones de tablero de ajedrez, evitando la concentración de esfuerzos -- El algoritmo resultante converge en un número reducido de iteraciones cuando se compara con ESO -- La presente aproximación computa una función implícita basada en análisis de sensibilidad -- La B-Rep es asociada con esta función implícita y el valor de umbral -- La superficie final se obtiene moviendo la frontera a la posición de la iso-curva del valor de umbral de la función de sensibilidad -- Resultados preliminares muestran las ventajas en tiempo y calidad de superficie resultante del presente métodoÍtem Shape optimisation of continuum structures via evolution strategies and fixed grid finite element analysis(SPRINGER, 2004-01-01) Garcia, MJ; Gonzalez, CA; Mecánica AplicadaEvolution strategies (ES) are very robust and general techniques for finding global optima in optimisation problems. As with all evolutionary algorithms, ES apply evolutionary operators and select the most fit from a set of possible solutions. Unlike genetic algorithms, ES do not use binary coding of individuals, working instead with real variables. Many recent studies have applied evolutionary algorithms to structural problems, particularly the optimisation of trusses. This paper focuses on shape optimisation of continuum structures via ES. Stress analysis is accomplished by using the fixed grid finite element method, which reduces the computing time while keeping track of the boundary representation of the structure. This boundary is represented by b-spline functions, circles, and polylines, whose control points constitute the parameters that govern the shape of the structure. Evolutionary operations are applied to each set of variables until a global optimum is reached. Several numerical examples are presented to illustrate the performance of the method. Finally, structures with multiple load cases are considered along with examples illustrating the results obtained.Ítem Simulation and parameterization by the finite element method of a C Shape Delectromagnet for application in the characterization of magnetic properties of materials(World Academy of Science, Engineering and Technology, 2012-11-22) Velásquez Torres, Álvaro Andrés; Baena Rodríguez, Juliana; Universidad EAFIT. Departamento de Ciencias Básicas; avelas26@eafit.edu.co; Electromagnetismo Aplicado (Gema)This article presents the simulation, parameterization and optimization of an electromagnet with the C–shaped configuration, intended for the study of magnetic properties of materials -- The electromagnet studied consists of a C-shaped yoke, which provides self–shielding for minimizing losses of magnetic flux density, two poles of high magnetic permeability and power coils wound on the poles -- The main physical variable studied was the static magnetic flux density in a column within the gap between the poles, with 4cm2 of square cross section and a length of 5cm, seeking a suitable set of parameters that allow us to achieve a uniform magnetic flux density of 1x104 Gaussor values above this in the column, when the system operates at room temperature and with a current consumption not exceeding 5A -- By means of a magnetostatic analysis by the finite element method, the magnetic flux density and the distribution of the magnetic field lines were visualized and quantified -- From the results obtained by simulating an initial configuration of electromagnet, a structural optimization of the geometry of the adjustable caps for the ends of the poles was performed -- The magnetic permeability effect of the soft magnetic materials used in the poles system, such as low–carbon steel (0.08% C), Permalloy (45% Ni, 54.7% Fe) and Mumetal (21.2% Fe, 78.5% Ni), was also evaluated -- The intensity and uniformity of the magnetic field in the gap showed a high dependence with the factors described above -- The magnetic field achieved in the column was uniform and its magnitude ranged between 1.5x104 Gauss and 1.9x104 Gauss according to the material of the pole used, with the possibility of increasing the magnetic field by choosing a suitable geometry of the cap, introducing a cooling system for the coils and adjusting the spacing between the poles -- This makes the device a versatile and scalable tool to generate the magnetic field necessary to perform magnetic characterization of materials by techniques such as vibrating sample magnetometry (VSM), Hall-effect, Kerr-effect magnetometry, among others -- Additionally, a CAD design of the modules of the electromagnet is presented in order to facilitate the construction and scaling of the physical deviceÍtem Structural characterization of the (methanol)4 potential energy surface(AMER CHEMICAL SOC, 2009-09-24) David, Jorge; Guerra, Doris; Restrepo, Albeiro; Universidad EAFIT. Departamento de Ciencias Básicas; Electromagnetismo Aplicado (Gema)In this paper, we report the geometries and properties of the structural isomers obtained from a random walk of the potential energy surface (PES) of the methanol tetramer. Thirty-three structures were obtained after B3LYP/6-31+g* optimization of 94 candidate structures generated from a stochastic search of the PM3 conformational space. The random search was carried out using a recently proposed modified Metropolis acceptance test in the simulated annealing (SA) procedure. Corrections for the basis set superposition error (BSSE) show improvements on the binding energies of the clusters in an average of approximately 2.0 kcal/mol, while geometries are predicted to be less sensitive to BSSE corrections. MP2/aug-cc-pvdz calculations on representative structures did not change the geometries but predicted better binding energies. Highly correlated CCSD(T) energies were calculated on the B3LYP and MP2 stationary points and used to establish relative stabilities. We report several new conformations and group the structures into six distinct geometrical motifs. Only the cyclic tetramers with four primary hydrogen bonds in the same plane are predicted to have significant populations. Secondary hydrogen bonds, those for which the donated proton comes from an alkyl group, lead to a rich conformational space.