Examinando por Materia "Temperature"
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Ítem Evaluation of mixing conditions and its influence over free residual(Universidad EAFIT, 2012-06-15) Montoya, C C; Cruz, H; Torres, P; Laín, Santiago; Escobar, J C; Universidad del ValleÍtem Fast analytic simulation for multi-laser heating of sheet metal in GPU(MDPI AG, 2018-11-01) Mejia-Parra D.; Montoya-Zapata D.; Arbelaiz A.; Moreno A.; Posada J.; Ruiz-Salguero O.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEInteractive multi-beam laser machining simulation is crucial in the context of tool path planning and optimization of laser machining parameters. Current simulation approaches for heat transfer analysis (1) rely on numerical Finite Element methods (or any of its variants), non-suitable for interactive applications; and (2) require the multiple laser beams to be completely synchronized in trajectories, parameters and time frames. To overcome this limitation, this manuscript presents an algorithm for interactive simulation of the transient temperature field on the sheet metal. Contrary to standard numerical methods, our algorithm is based on an analytic solution in the frequency domain, allowing arbitrary time/space discretizations without loss of precision and non-monotonic retrieval of the temperature history. In addition, the method allows complete asynchronous laser beams with independent trajectories, parameters and time frames. Our implementation in a GPU device allows simulations at interactive rates even for a large amount of simultaneous laser beams. The presented method is already integrated into an interactive simulation environment for sheet cutting. Ongoing work addresses thermal stress coupling and laser ablation. © 2018 by the authors.Ítem Frequency-domain analytic method for efficient thermal simulation under curved trajectories laser heating(Elsevier BV, 2019-01-01) Mejia-Parra D.; Moreno A.; Posada J.; Ruiz-Salguero O.; Barandiaran I.; Poza J.C.; Chopitea R.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEIn the context of Computer Simulation, the problem of heat transfer analysis of thin plate laser heating is relevant for downstream simulations of machining processes. Alternatives to address the problem include (i) numerical methods, which require unaffordable time and storage computing resources even for very small domains, (ii) analytical methods, which are less expensive but are limited to simple geometries, straight trajectories and do not account for material non-linearities or convective cooling. This manuscript presents a parallel efficient analytic method to determine, in a thin plate under convective cooling, the transient temperature field resulting from application of a laser spot following a curved trajectory. Convergence of both FEA (Finite Element Analysis) and the analytic approaches for a small planar plate is presented, estimating a maximum relative error for the analytic approach below 3.5% at the laser spot. Measured computing times evidence superior efficiency of the analytic approach w.r.t. FEA. A study case, with the analytic solution, for a large spatial and time domain (1m×1m and 12s history, respectively) is presented. This case is not tractable with FEA, where domains larger than 0.05m×0.05m and 2s require high amounts of computing time and storage. © 2019 International Association for Mathematics and Computers in Simulation (IMACS)Ítem Predictions of fluidities of amines by molecular simulations: TraPPE-EH vs. OPLS-AA(Elsevier B.V., 2018-05-25) Rendón-Calle A.; Orozco G.A.; Builes S.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de ProcesosAmines have several important industrial properties and commercial applications, such as gas sweetening and carbon capture; and the synthesis of: tranquilizers, decongestants, and azo dyes. For the design of many engineering applications, it is important to calculate the density and viscosity of the substances in order to determine how the fluids should be handled, stored, and discarded. In this work, the accuracy of two common force fields for amines, TraPPE-EH and OPLS-AA, was evaluated with respect to their predictions of liquid densities and fluidities for a large set of amine molecules including primary, secondary and tertiary. We propose the use of the reciprocal of viscosity, the fluidity, as a more accurate assessment of the predictions of viscosity at different temperatures. The fluidity was calculated using molecular dynamics in the isothermal-isobaric ensemble (NPT) along with the Green Kubo formalism. The simulation results were compared to available experimental information in order to provide a quantitative study of the force fields accuracy as well as their transferability to amines and thermodynamic conditions different to the ones used in their original parametrization. Overall, liquid densities and fluidities are well reproduced by the TraPPE-EH force field with absolute average deviations of 1.5% and 12%, respectively. However, important deviations were found for the OPLS-AA force field corresponding to 3.6% and 28% for density and fluidity respectively. In order to obtain better estimations of the fluidity, a temperature correction that accounts for the error in the liquid density predictions was proposed. Once the temperature correction was included the average deviation of the fluidity decreased to 10% for TraPPE-EH and to 18% for OPLS-AA. © 2018 Elsevier B.V.Ítem Two-Step Processing Method for Blending High-Performance Polymers with Notable Thermal and Rheological Differences: PEI and PBT(Taylor and Francis Inc., 2018-09-22) Vásquez-Rendón, M.; Sánchez-Arrieta, N.; Álvarez-Láinez, M.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Blends between high-performance polymers (HPP) are barely studied, especially those produced by melting processing. In this work, it is proposed a novel methodology to prepare blends between polymers with notable processing temperature differences: poly(ether imide) (PEI) and poly(butylene terephthalate) (PBT). Processing parameters are settled after thermal and rheological evaluation of pure materials, those results suggest these blends need to be produced by steps. It is found a synergistic effect such as lowering PEI processing temperature and reducing PBT hydrolysis at high temperatures. Propose methodology allows to produce blends between HPP in the whole composition range with the same processing conditions. © 2017, © 2017 Taylor & Francis.