DSpace Angular :: Browsing by Author "Celentano, Diego"

Browsing by Author "Celentano, Diego"

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A formulation for fluid-structure interaction problems with immersed flexible solids: Application to splitters subjected to flow past cylinders with different cross-sections
(2024) Cruchaga, Marcela; Ancamil, Pablo; Celentano, Diego
In the finite element method framework, a fluid-structure formulation is developed by coupling an Eulerian fixed-mesh fluid approach with a Lagrangian deforming-mesh description for a flexible solid. The coupled formulation is solved using a staggered scheme during time. For the fluid solution stage, the solid walls are considered as a time-variable internal boundary. The velocity and pressure fields are obtained by solving the weak form of the fluid dynamic equations in which the solid velocity is imposed on the internal boundary via a penalization term. For the solid solution stage, the displacement field is obtained by solving the discrete solid dynamic equations which consider traction forces computed by integrating pressures and viscous stresses on the nodes belonging to the solid walls. This novel technique is firstly applied to analyze a flexible splitter under the shedding of a flow past square cylinder due to this problem is considered as a benchmark in the literature. The present solutions agree with those computed using body-fitted techniques, thus validating the proposal. Secondly, flexible splitter motions under the shedding of flow past cylinders with different cross-sections and splitter lengths are comprehensively studied. Overall, the computed results confirmed that the hydrodynamic coefficients on the cylinders were reduced because of the presence of the splitter.
Characterization of the Elastoplastic Response of Low Zn-Cu-Ti Alloy Sheets Using the CPB-06 Criterion
(2019) Alister, Francisco; Celentano, Diego; Signorelli, Javier; Bouchard, Pierre-Olivier; Pino, Daniel; Cruchaga, Marcela
Unlike other HCP metals such as titanium and magnesium, the behavior of zinc alloys has only been modeled in the literature. For the low Zn-Cu-Ti alloy sheet studied in this work, the anisotropy is clearly seen on the stress-strain curves and Lankford coefficients. These features impose a rigorous characterization and an adequate selection of the constitutive model to obtain an accurate representation of the material behavior in metal forming simulations. To describe the elastoplastic behavior of the alloy, this paper focuses on the material characterization through the application of the advanced Cazacu-Plunket-Barlat 2006 (CPB-06 for short) yield function combined with the well-known Hollomon hardening law. To this end, a two-stage methodology is proposed. Firstly, the material characterization is performed via tensile test measurements on sheet samples cut along the rolling, diagonal and transverse directions in order to fit the parameters involved in the associate CPB-06/Hollomon constitutive model. Secondly, these material parameters are assessed and validated in the simulation of the bulge test using different dies. The results obtained with the CPB-06/Hollomon model show a good agreement with the experimental data reported in the literature. Therefore, it is concluded that this model represents a consistent approach to estimate the behavior of Zn-Cu-Ti sheets under different forming conditions.
Computational Shape Design Optimization of Femoral Implants: Towards Efficient Forging Manufacturing
(2024) Tuninetti, Victor; Fuentes, Geovanni; Onate, Angelo; Narayan, Sunny; Celentano, Diego; Garcia-Herrera, Claudio; Menacer, Brahim; Pincheira, Gonzalo; Garrido, Cesar; Valle, Rodrigo
Total hip replacement is one of the most successful orthopedic operations in modern times. Osteolysis of the femur bone results in implant loosening and failure due to improper loading. To reduce induced stress, enhance load transfer, and minimize stress, the use of Ti-6Al-4V alloy in bone implants was investigated. The objective of this study was to perform a three-dimensional finite element analysis (FEA) of the femoral stem to optimize its shape and analyze the developed deformations and stresses under operational loads. In addition, the challenges associated with the manufacturing optimization of the femoral stem using large strain-based finite element modeling were addressed. The numerical findings showed that the optimized femoral stem using Ti-6Al-4V alloy under the normal daily activities of a person presented a strains distribution that promote uniform load transfer from the proximal to the distal area, and provided a mass reduction of 26%. The stress distribution was found to range from 700 to 0.2 MPa in the critical neck area of the implant. The developed computational tool allows for improved customized designs that lower the risk of prosthesis loss due to stress shielding.
Damage Prediction in the Wire Drawing Process
(2024) Gonzalez, Alvaro; Cruchaga, Marcela; Celentano, Diego; Ponthot, Jean-Philippe
In this study, the prediction of damage in the wire drawing process of 2011 aluminum alloy was investigated through both experimental and numerical methods. A comprehensive experimental setup was designed involving 20 cases of wire drawing with varying die angles (10 degrees, 15 degrees, 21 degrees, 27 degrees, and 34 degrees) and reductions (21%, 29%, 31%, and 38%). Each case was tested three times, and the drawing forces, as well as occurrences of wire breakage, were recorded. The mechanical behavior of the material was firstly characterized using uniaxial tensile tests, whose results were used to determine the material parameters of both the hardening Voce law and those of uncoupled and coupled damage models. Then, the numerical simulations of the wire drawing process were performed using a finite element model, accounting for axisymmetric conditions and mesh convergence analysis to ensure accuracy. The previously characterized damage models were applied to evaluate their fracture prediction capabilities. A novel presentation method using three-dimensional graphs was employed to indicate the level of damage for each angle and reduction, providing greater sensitivity and insight into the damage values. Good agreement between the experimental and numerical data was demonstrated for the bilinear coupled damage model, validating its effectiveness. This study contributes to a better understanding of damage prediction in the wire drawing process, with implications for improving industrial practices and material performance evaluations.
Elastoplastic Characterization of Zn-Cu-Ti Alloy Sheets: Experiments, Modeling, and Simulation
(2021) Alister, Francisco ; Celentano, Diego ; Nicoletti, Emanuel ; Signorelli, Javier ; Bouchard, Pierre-Olivier ; Pino, Daniel ; Pradille, Christophe ; Cruchaga, Marcela
In this work, the elastoplastic behavior of Zn20 alloy sheets is characterized via a methodology that encompasses experiments, modeling, and numerical simulations. The experimental campaign includes tensile, compression, shear, and bulge tests. The modeling is based on the Cazacu-Plunket-Barlat 2006 yield criterion and the Swift hardening law, adjusted only from experimental data from the tensile and compression tests. The corresponding material parameters are obtained with a calibration procedure that accounts for the tensile stress-strain curves and Lankford coefficients, along with five directions regarding the sheet's rolling direction. Besides, compression tests were performed to search for evidence of asymmetric behavior. The numerical simulation, carried out with the finite element method (FEM), is used to validate the previous characterization with the shear and bulge tests models. The experimental force-displacement curve and the shear strain contours are the comparison basis for the shear test. For the bulge test, considering different mask geometries (minor to major axis length ratios), plots of the major-minor strain paths and thickness reduction in terms of the dome height are also used to assess the model's predictive capabilities. In general, the obtained numerical results show a good description of the material behavior in the shear and bulge tests. The evolution of the strain field in the bulge test is well represented by the model regardless of the sample orientation and mask configuration. It is finally concluded that the proposed methodology provides a robust model to describe the elastoplastic response of Zn-Cu-Ti (Zn20) alloy sheets subject to different proportional loading conditions.
Erosion under turbulent slurry flow: Effect of particle size in determining impact velocity and wear correlation by inverse analysis
(2021) Molina, Nicolas; Walczak, Magdalena; Kalbarczyk, Marek; Celentano, Diego
Surface topography after slurry erosion contains meaningful information concerning the process of erosive wear. This paper describes a procedure of inverse analysis to determine particle impact velocity from collective erosive features through image processing and further modeling. Slurry pot is used to produce wear damage on copper in exposure to a highly turbulent flow of dilute slurry of glass beads. Topography data for image processing is acquired by non-contact 3D profilometry. The analysis is carried out using two empirical models (Oka and Huang) and one analytical model (Cheng). The results reveal that the back-calculated velocity depends significantly on the model used. Whereas Huang's and Cheng's models produce values representative of the nominal flow conditions, the Oka's model results in unrealistic values. Finally, monotonic correlations between experimental variables associated with individual erosive features are discussed in the context of collective erosion models.
Experimental and Numerical Analysis of Low Output Power Laser Bending of Thin Steel Sheets
(ASME, 2012) Stevens, Vicente; Celentano, Diego; Ramos Grez, Jorge; Walczak, Magdalena
This work presents an experimental and numerical analysis of a low output power single-pass laser forming process applied to thin stainless steel sheets. To this end, the proposed methodology consists in four stages respectively devoted to material characterization via tensile testing, estimation of thermal boundary conditions present in laser forming, realization of laser bending tests for two sets of operating variables, and finally, numerical simulation of this process carried out with a coupled thermomechanical finite element formulation accounting for large plastic strains, temperature-dependent material properties and convection-radiation phenomena. The numerical analysis, focused on the description of the evolution of the thermomechanical material response, is found to provide a satisfactory experimental validation of the final bending angle for two laser forming cases with different operating variables. In both cases, the predicted high temperature gradients occurring across the sample thickness show that the deformation process is mainly governed by the thermal gradient mechanism. [DOI: 10.1115/1.4005807]
Hybrid numerical-experimental strategy for damage characterization of SAE 1045 steel
(2023) Aranda, Pedro Miguel; Garcia-Herrera, Claudio; Celentano, Diego; Tuninetti, Victor; Toro, Sebastian Andres; Landeros, Felipe
In this work, the elastoplastic behavior with continuous mechanical damage in a SAE 1045 steel is characterized using mainly torsional tests and simulations. A numerical-experimental inverse analysis procedure is proposed to fit a von Mises-type elastoplastic model and a Lemaitre-type continuous damage model to the material's mechanical response obtained in torsional tests. A FEM simulation campaign is carried out to calibrate the damage model, considering a two-step linear evolution of the damage variable in terms of the degradation of the elastic torsional stiffness measured in cyclic torsional tests. The procedure is validated with a numerical- experimental comparison in tensile tests to demonstrate the validity of the solution in other loading paths. The numerical model obtained is used to analyze the local effects of the damage and its distribution in torsional and tensile tests.
Numerical heat transfer in annular fins of curved profile formed with the intersection of two equal circles
(2021) Celentano, Diego; Campo, Antonio
Purpose The purpose of this paper is to investigate the heat transfer attributes of annular fins with quarter circle profile in terms of the Biot number Bi and the radius ratio r(r). The latter corresponds to the internal radius of the tube divided by the length of the fin in question. Design/methodology/approach To this end, the governing two-dimensional (2-D) heat conduction equation in cylindrical coordinates is numerically solved via finite element analysis for different Bi (i.e., 0.1, 1 and 5) and r(r) (i.e., 0.5, 1 and 2). Findings The obtained results for the mid-plane and surface temperatures show that these profiles, which exhibit nearly r(r)-independent responses, only present one-dimensional (1-D) radially linear distributions for the case Bi = 1. For Bi = 0.1, the temperature profiles also possess a 1-D character but with a clearly defined concave pattern. Finally, for Bi = 5, a 2-D temperature field in a wide zone from the fin base is achieved with a convex pattern for the mid-plane and surface temperatures. Originality/value Exhaustive assessment of the heat transfer in annular fins with quarter circle profile in terms of different Biot numbers and radius ratios
Numerical simulation of natural convection and phase-change in a horizontal Bridgman apparatus
(2011) Celentano, Diego; Cruchaga, Marcela; Romero, Jorge; El Ganaoui, Mohammed
Purpose - The purpose of this paper is to present a 2D numerical simulation of natural convection and phase-change of succinonitrile in a horizontal Bridgman apparatus. Three different heat transfer mechanisms are specifically studied: no growth, solidification and melting.
On the validation and applicability of multiphysics models for hydrogen SOFC
(2024) Diaz, Brayn; Celentano, Diego; Molina, Paulo; Sancy, Mamie; Troncoso, Loreto; Walczak, Magdalena
Solid oxide fuel cells (SOFC) are a viable alternative for environmentally-friendly conversion of hydrogen into energy and multiphysics simulation can be used to diminish the experimental effort to improve their efficiency. However, an appropriate model of the involved processes and their parameters must be chosen. This paper studies the effects of choice between Maxwell-Stefan and Fick's law models, and uncertainty of electrode ionic conductivity sigma(ion) ion and anodic reference exchange current density i(0,ref,f), on cell performance as implemented in the COMSOL Multiphysics (R) software. In the case of Maxwell-Stefan, peak average power output increased by 21.9% as sigma(ion) varies from 10(-3) to 10(-1) S/cm, while the model based on Fick's law shows an increase of 55.2%. The Maxwell-Stefan model exhibits an increase in peak power of 6% as i(0,ref,f) ranges from 0.4 to 0.8 A/cm(2), and the Fick's law model an increase of 8.2%. The dependence of the Maxwell-Stefan model on sigma(ion) is characterized as logarithmic in the studied range. The Maxwell-Stefan model is deemed preferable because its lower sensitivity to the studied parameters helps mitigate uncertainty. It is concluded that despite its limitations, multiphysics modeling is a useful tool for directing research on SOFC materials owing to its descriptive potential.
Prediction of the temperature-time history in ordinary bodies induced by surface heat flux utilizing the enhanced method of discretization in time and the finite difference method
(2023) Campo, Antonio; Celentano, Diego; Masip, Yunesky
PurposeThe purpose of this paper is to address unsteady heat conduction in two subsets of ordinary bodies. One subset consists of a large plane wall, a long cylinder and a sphere in one dimension. The other subset consists of a short cylinder and a large rectangular bar in two dimensions. The prevalent assumptions in the two subsets are: constant initial temperature, uniform surface heat flux and thermo-physical properties invariant with temperature. The engineering applications of the unsteady heat conduction deal with the determination of temperature-time histories in the two subsets using electric resistance heating, radiative heating and fire pool heating. Design/methodology/approachTo this end, a novel numerical procedure named the enhanced method of discretization in time (EMDT) transforms the linear one-dimensional unsteady, heat conduction equations with non-homogeneous boundary conditions into equivalent nonlinear "quasi-steady" heat conduction equations having the time variable embedded as a time parameter. The equivalent nonlinear "quasi-steady" heat conduction equations are solved with a finite difference method. FindingsBased on the numerical computations, it is demonstrated that the approximate temperature-time histories in the simple subset of ordinary bodies (large plane wall, long cylinder and sphere) exhibit a perfect matching over the entire time domain 0 < t < infinity when compared against the rigorous exact temperature-time histories expressed by classical infinite series. Furthermore, using the method of superposition of solutions in the convoluted subset (short cylinder and large rectangular crossbar), the same level of agreement in the approximate temperature-time histories in the simple subset of ordinary bodies is evident. Originality/valueThe performance of the proposed EMDT coupled with a finite difference method is exhaustively assessed in the solution of the unsteady, one-dimensional heat conduction equations with prescribed surface heat flux for: a subset of one-dimensional bodies (plane wall, long cylinder and spheres) and a subset of two-dimensional bodies (short cylinder and large rectangular bar).
Structural Evaluation by the Finite-Element Method of Hollow Microneedle Geometries for Drug Delivery
(2022) Henriquez, Francisco; Morales-Ferreiro, Jorge Osvaldo; Celentano, Diego
Herein, the structural comparison, using the finite-element method (FEM), of different designs of individual hollow microneedles (MNs) is exposed, that is, conical, pyramidal, traditional, and sting type, for use as a transdermal drug delivery system (TDDS). These configurations attract interest in fields such as pharmaceutics and medicine due to their efficiency, easy administration of drugs, and significant reduction in pain compared to the traditional use of hypodermic needles. For the structural analysis and comparison of the proposed designs, ANSYS FEM-based software is used to simulate the insertion of an MN in the skin. The study and comparison are carried out under simulations of structural resistance, buckling analysis, and behavior in the MN-skin contact. The application forces are set according to the fracture resistance of the outside layer of the skin. A force of 0.16N for a conical MN is finally obtained as a critical application load to avoid a structural failure in the insertion of the MN in the human skin. Moreover, the use of poly(lactic-co-glycolic) acid (PLGA) is also assessed as a second biocompatible alternative due to both its easy handling for manufacture process and the resistance it presents in indentation simulations in which the applied force reaches 0.19N.
Surface laser treatment on ferritic ductile iron: effect of linear energy on microstructure, chemical composition, and hardness
(2021) Catalán Salas, Néstor Andrés; Ramos Moore, Esteban; Boccardo, Adrián; Celentano, Diego; Alam, Nazmul; Walczak, Magdalena; Gunasegaram, Dayalan
The Triaxiality Effect on Damage Evolution in Al-2024 Tensile Samples
(2024) Gonzalez, Alvaro; Celentano, Diego; Cruchaga, Marcela; Ponthot, Jean-Philippe
The effect of triaxiality on the evolution of damage in Al-2024 aluminum cylindrical specimens is studied in this work. Uncoupled and coupled damage models, all of them explicitly dependent on triaxiality, are assessed and compared. These models are characterized by tensile tests on cylindrical specimens without notches, to obtain the material parameters for each model. The capability of each model to predict fracture when different positive triaxial conditions evolve is then evaluated through tensile tests on notched cylindrical specimens. In particular, the damage index, evaluated at the fracture strain level, is compared with the experimental results validating the models. Moreover, the triaxiality evolution in the different specimens is studied in order to assess its effect on damage, demonstrating that the fracture strain decreases at greater triaxiality values. Observations through scanning electron microscopy confirm this pattern; i.e., an increase in triaxiality reveals a shift in the fracture mechanism from a more ductile condition in the original specimens to a more brittle one as the notch radius decreases. In addition, bilinear damage evolution is proposed to describe the physical behavior of the material when the Lemaitre coupled model is considered. In such a case, special attention must be devoted to the material characterization since coupling between hardening material parameters and damage affects the results.
Tuning the Electronic Bandgap of Penta-Graphene from Insulator to Metal Through Functionalization: A First-Principles Calculation
(2024) Morales-Ferreiro, J. O.; Silva-Oelker, Gerardo; Kumar, Chandra; Zambra, Carlos; Liu, Zeyu; Diaz-Droguett, Donovan E.; Celentano, Diego
We performed first-principles density functional theory (DFT) calculations to numerically investigate the electronic band structures of penta-graphene (PG), a novel two-dimensional carbon material with a pentagonal lattice structure, and its chemically functionalized forms. Specifically, we studied hydrogenated PG (h-PG), fluorinated PG (f-PG), and chlorinated PG (Cl-PG). We used the generalized gradient approximation (GGA) and the hybrid Heyd-Scuseria-Ernzerhof (HSE06) exchange-correlation functional in the DFT-based software VASP to capture electronic properties accurately. Our results indicate that hydrogenation and fluorination increased the indirect bandgap of PG from 3.05 eV to 4.97 eV and 4.81 eV, respectively, thereby effectively transforming PG from a semiconductor to an insulator. In contrast, we found that chlorination closed the bandgap, thus indicating the metallic behavior of Cl-PG. These results highlight the feasibility of tuning the electronic properties of PG through functionalization, offering insight into designing new materials for nanoelectronic applications.
Viscoplastic and Temperature Behavior of Zn-Cu-Ti Alloy Sheets: Experiments, Characterization, and Modeling
(2021) Alister, Francisco ; Celentano, Diego ; Signorelli, Javier ; Bouchard, Pierre-Olivier ; Pino Muñoz, Daniel ; Cruchaga, Marcela
It has been experimentally observed that the Zn-Cu-Ti zinc alloy shows a strong influence of strain rate and temperature on its plastic behavior. A significant change in the material response is seen with relatively small strain rate variations or temperature. In this work, these effects are addressed through the Cazacu-Plunket-Barlat 2006 (CPB-2006) yield criterion and the Johnson-Cook hardening law. The tests were carried out over the three main directions: rolling, diagonal, and transversal. Three strain rate conditions (0.002, 0.02, and 0.2 s(-1)) and three temperatures (20, 60, and 80 degrees C) were tested. Although the experi-mental results exhibit a significant influence of the strain rate and temperature on stress-strain curves for all tested directions, such two variables do not practically affect the Lankford coefficients. The proposed model calibration procedure is found to describe the material responses properly under the studied conditions. (C) 2021 The Author(s). Published by Elsevier B.V.

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