Browsing by Author "Cruchaga, Marcela A."

Now showing 1 - 8 of 8
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    Analysis of Flow Past Oscillatory Cylinders Using a Finite Element Fixed Mesh Formulation
    (2017) González, Felipe A.; Cruchaga, Marcela A.; Celentano, Diego J.
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    Bending and pressurisation test of the human aortic arch: experiments, modelling and simulation of a patient-specific case
    (2013) Garcia-Herrera, Claudio M.; Celentano, Diego J.; Cruchaga, Marcela A.
    This work presents experiments, modelling and simulation aimed at describing the mechanical behaviour of the human aortic arch during the bending and pressurisation test. The main motivation is to describe the material response of this artery when it is subjected to large quasi-static deformations in three different stages: bending, axial stretching and internal pressurisation. The sample corresponds to a young artery without cardiovascular pathologies. The pressure levels are within the normal and hypertension physiological ranges. The two principal findings of this work are firstly, the material characterisation performed via tensile test measurements that serve to derive the material parameters of a hyperelastic isotropic constitutive model and, secondly, the assessment of these material parameters in the simulation of the bending and pressurisation test. Overall, the reported material characterisation was found to provide a realistic description of the mechanical behaviour of the aortic arch under severe complex loading conditions considered in the bending and pressurisation test.
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    Bilinear damage evolution in AA2011 wire drawing processes
    (2022) Gonzalez, Alvaro A.; Cruchaga, Marcela A.; Celentano, Diego J.
    This paper presents an experimental and numerical analysis of damage evolution in AA2011 aluminum alloy wires drawn under different scenarios. To this end, load-unload tensile tests were firstly carried out in order to characterize the degradation of the mechanical response in every cycle where the experimental results show a bilinear damage relationship in terms of the effective plastic strain. Therefore, a modification of the classical Lemaitre model is proposed in this work in order to reproduce bilinear paths of damage with the addition of only two parameters that can be directly obtained from the material characterization. Then, the damage predictive capability of this new experimental-based model is assessed in numerical simulations of the drawing process in one and two passes (considering for this last case the sequential and tandem configurations) where the computed predictions are compared with the corresponding experimental data showing a good agreement between them.
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    Mechanical characterisation of the human thoracic descending aorta: experiments and modelling
    (TAYLOR & FRANCIS LTD, 2012) Garcia Herrera, Claudio M.; Celentano, Diego J.; Cruchaga, Marcela A.; Rojo, Francisco J.; Atienza, Jose Miguel; Guinea, Gustavo V.; Goicolea, Jose M.
    This work presents experiments and modelling aimed at characterising the passive mechanical behaviour of the human thoracic descending aorta. To this end, uniaxial tension and pressurisation tests on healthy samples corresponding to newborn, young and adult arteries are performed. Then, the tensile measurements are used to calibrate the material parameters of the Holzapfel constitutive model. This model is found to adequately adjust the material behaviour in a wide deformation range; in particular, it captures the progressive stiffness increase and the anisotropy due to the stretching of the collagen fibres. Finally, the assessment of these material parameters in the modelling of the pressurisation test is addressed. The implication of this study is the possibility to predict the mechanical response of the human thoracic descending aorta under generalised loading states like those that can occur in physiological conditions and/or in medical device applications.
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    Numerical simulation and experimental validation of the microindentation test applied to bulk elastoplastic materials
    (2012) Celentano, Diego J.; Guelorget, Bruno; Francois, Manuel; Cruchaga, Marcela A.; Slimane, Amara
    The main objective of this work is to compare numerically simulated load-indentation depth curves together with deformation and stress fields underneath a sharp indenter for a set of mystical materials. Firstly, a numerical simulation and experimental validation of the microindentation test applied to three different bulk elastoplastic materials (copper, stainless steel and pure aluminium) using two indenters (Berkovich and spherical) are presented. The simulation of these microindentation tests is carried out using the finite element large strain elastoplastic and contact models. The corresponding results are particularly aimed at addressing the following aspects: the influence of the indenter geometry on both the load-indentation depth curve and range of plastic strains involved in the test, the comparison of the 3D results for the sharp indenter with those of the 2D approximation, the capabilities of the modelling through experimental validation of the numerical predictions and, in addition, an assessment of the indentation size effect. Secondly, the numerical results of Berkovich indentation applied to a set of mystical materials are exhaustively discussed. Although it is effectively shown that these mystical materials exhibit indistinguishable load-penetration depth curves during the loading phase, an important aspect that has not been previously addressed is that some clear differences in their responses are obtained for the unloading stage. Finally, the deformation and stress contours at the maximum indentation force and after unloading are particularly analysed.
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    Simulation and experimental validation of multiple-step wire drawing processes
    (ELSEVIER, 2009) Celentanoa, Diego J.; Palacios, Mauricio A.; Rojas, Ennio L.; Cruchaga, Marcela A.; Artigas, Alfredo A.; Monsalve, Alberto E.
    This paper presents an experimental analysis and a numerical simulation of the mechanical behaviour experienced by a steel rod during multiple-step wire cold-drawing processes. To this end, a set of tensile experiments is firstly carried out in order to characterise the material hardening evolution for different consecutive wire reductions. The experimental procedure also encompasses the measurement of drawing forces in a multiple-step process conducted at a laboratory scale under different drawing velocities. Then, this problem is simulated via a finite element formulation that accounts for both large viscoplastic strains and friction effects. The results obtained with the simulation are experimentally validated. Finally, the influence of specific operating conditions, such as the decrease of the number of wire reductions and the presence of back tension, on the material response during the whole process is numerically assessed. (C) 2008 Elsevier B. V. All rights reserved.
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    Simulation and experimental validation of the motion of immersed rigid bodies in viscous flows
    (ELSEVIER SCIENCE SA, 2008) Cruchaga, Marcela A.; Munoz, Christian M.; Celentano, Diego J.
    In this work we present the numerical analysis of the motion of a rigid body immersed in a viscous fluid. The fluid flow induced by the gravity-driven motion of a rigid body is particularly analysed using cylinders and spheres. The Navier-Stokes equations coupled with the interface motion are solved in the framework of a finite element formulation. The interface of the rigid body is represented using a moving Lagrangian interface technique (MLIT). The proposed formulation is applied to describe the two-dimensional motion of a cylinder between parallel walls as well as the axisymmetric representation of a sphere assessing in both cases the effects of the walls distance on the velocity developed by such bodies. The numerical predictions are verified using different models for the analysis of the problem, and are validated by comparison with theoretical-empirical correlations. Moreover, the computed body velocities are compared with experimental data reported in the literature as well as measurements obtained from experiments carried out in the framework of the present work. (C) 2008 Elsevier B.V. All rights reserved.
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    Solving steady-state lid-driven square cavity flows at high Reynolds numbers via a coupled improved element-free Galerkin-reduced integration penalty method
    (2021) Alvarez Hostos, Juan C.; Salazar Bove, Joselynne C.; Cruchaga, Marcela A.; Fachinotti, Victor D.; Mujica Agelvis, Rafael A.
    Steady-state two-dimensional lid-driven square cavity flows at high Reynolds numbers are solved in this communication using a velocity-based formulation developed in the context of the improved element-free Galerkin-reduced integration penalty method (IEFG-RIPM). The analyses based on the IEFG-RIPM are performed under a standard Galerkin weak-formulation, i.e. without the need of introducing streamline-upwind or pressure stabilizing terms in order to suppress the appearance of non-physical oscillations. Solutions in a wide range of high Reynolds numbers are successfully achieved, and the results obtained have exhibited an excellent agreement with mesh-based solutions reported in the literature. The numerical performance of the proposed IEFG-RIPM in the solution of such benchmark problem has been analysed in terms of velocity distribution, streamline patterns, vorticity and pressure contours, and also in terms of the properties of primary and secondary vortices. The outcomes of this study demonstrate the potential of the IEFG-RIPM as a feasible and reliable numerical technique for the analysis of lid-driven square cavity flows at high Reynolds numbers, allowing the fulfilment of accuracy and stability numerical requirements demanded in the solution of this benchmark problem in a remarkably simple manner.