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https://hdl.handle.net/10784/29295

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Bifurcations and Sequences of Elements in Non-Smooth Systems Cycles
(2013-09-01) RUIZ, OSCAR EDUARDO; Arango, Iván Darío; RUIZ, OSCAR EDUARDO; Arango, Iván Darío; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Characteristic Point Sequences in Local and Global Bifurcation Analysis of Filippov Systems
(World Scientific and Engineering Academy and Society (WSEAS) Press, 2008-10-01) Arango, Iván Darío; Arango, Iván Darío; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Continuation of Nonsmooth Bifurcations in Filippov Systems Using Singular Point Tracking
(2007-12-01) Arango, Iván Darío; Arango, Iván Darío; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Corporificación
(Fondo Editorial Universidad EAFIT, 1999-10-01) RODRIGUEZ, ALBERTO; RODRIGUEZ, ALBERTO; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Design and contruction of simulators from out of service planes for parks of diversion
(2005-01-01) Arango, Iván Darío; Arango, Iván Darío; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Design of a statically balanced fully compliant grasper
(Elsevier Ltd, 2015-10-01) Lamers, A.J.; Gallego Sánchez, J.A.; Herder, J.L.; Lamers, A.J.; Gallego Sánchez, J.A.; Herder, J.L.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Monolithic and thus fully compliant surgical graspers are promising when they provide equal or better force feedback than conventional graspers. In this work for the first time a fully compliant grasper is designed to exhibit zero stiffness and zero operation force. The design problem is addressed by taking a building block approach, in which a pre-existing positive stiffness compliant grasper is compensated by a negative stiffness balancer. The design of the balancer is conceived from a 4-bar linkage and explores the rigid-body-replacement method as a design approach towards static balancing. Design variables and sensitivities are determined through the use of a pseudo-rigid-body model. Final dimensions are obtained using rough hand calculations. Justification of the pseudo rigid body model as well as the set of final dimensions is done by non-linear finite element analysis. Experimental validation is done through a titanium prototype of 40 mm size having an unbalanced positive stiffness of 61.2 N/mm showing that a force reduction of 91.75% is achievable over a range of 0.6 mm, with an approximate hysteresis of 1.32%. The behavior can be tuned from monostable to bistable. The rigid-body-replacement method proved successful in the design of a statically balanced fully compliant mechanism, thus, widening the design possibilities for this kind of mechanism. (C) 2015 Elsevier Ltd. All rights reserved.
Design to Achieve Accuracy in Ink-Jet Cylindrical Printing Machines
(MDPI AG, 2019-01-11) Arango, Ivan; Cifuentes, Catherine; Arango, Ivan; Cifuentes, Catherine; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Machines for direct digital inkjet printing on cylindrical containers are a new technology out on the market. The commercialization in the industrial sector has been affected by their high precision. This led to the use of mechanisms with narrow manufacturing tolerances and to the searches for topologies that have the least accumulated error without affecting quality. Machines with topologies that work on flat substrates have printing and productivity problems working on cylindrical substrates. This research paper presents the qualitative design of direct digital inkjet printers working over cylindrical substrates comparing five mechanical topologies; three topologies with radial distribution and two topologies with parallel distribution. The aim of these topologies is to find the precision, quality and efficiency of the printer taking into account the restrictions present in its construction. Each topology has separate constitutive mechanisms, the tolerance ranges between the movements of the print head and the substrate in order to determine precision are analyzed. Out of the five topologies described and analyzed in the phase diagram in section 3, three of them meet the requirements. One of the three topologies that meet the requirements is not being developed due to current technological limitations.
Diseño de punzonadoras CNC para pequeños lotes de producción
(2012-07-01) Arango, Iván Darío; Arango, Iván Darío; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Dislocation density based flow stress model applied to the PFEM simulation of orthogonal cutting processes of Ti-6Al-4V
(MDPI AG, 2020-01-01) Rodríguez, J.M.; Larsson, S.; Carbonell, J.M.; Jonsén, P.; Rodríguez, J.M.; Larsson, S.; Carbonell, J.M.; Jonsén, P.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Machining of metals is an essential operation in the manufacturing industry. Chip formation in metal cutting is associated with large plastic strains, large deformations, high strain rates and high temperatures, mainly located in the primary and in the secondary shear zones. During the last decades, there has been significant progress in numerical methods and constitutive modeling for machining operations. In this work, the Particle Finite Element Method (PFEM) together with a dislocation density (DD) constitutive model are introduced to simulate the machining of Ti-6Al-4V. The work includes a study of two constitutive models for the titanium material, the physically based plasticity DD model and the phenomenology based Johnson-Cook model. Both constitutive models were implemented into an in-house PFEM software and setup to simulate deformation behaviour of titanium Ti6Al4V during an orthogonal cutting process. Validation show that numerical and experimental results are in agreement for different cutting speeds and feeds. The dislocation density model, although it needs more thorough calibration, shows an excellent match with the results. This paper shows that the combination of PFEM together with a dislocation density constitutive model is an excellent candidate for future numerical simulations of mechanical cutting. © 2020 by the authors.
Dynamic analysis of a recirculation system of micro functional fluids for ink-jet applications
(Springer Verlag, 2017-05-01) Arango, I.; Cañas, M.; Arango, I.; Cañas, M.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
The rise of ink-jet printing technology has led to numerous studies about functional fluids, which, in most cases, are made to change and improve the chemical and rheological properties. Besides this, there are several patents about the recirculation fluid system that help to prevent settling particles, and thus improving print quality without consequences in the chemical composition of the fluid. This paper presents a dynamic analysis of a recirculation circuit for ink-jet microsystems applications with fluids that contain a particle size of 40 nm to 10 µ m. This analysis integrates multiple mathematical and experimental models, in regard to variables such as: viscosity change with temperature and solid volume fraction, sedimentation, surface tension and flow behavior. As a result, specific values of vacuum pressure for different drop-on-demand print heads with different ink-jet functional fluids, places of probable sedimentation and minimum pickup velocities to remove settled particles are given. © 2017, Springer-Verlag Berlin Heidelberg.
E-bikes for steep roads: Mid drive and hub drive motor efficiency comparison
(Inderscience Enterprises Ltd., 2018-01-01) Arango, I.; Godoy, A.; Lopez, C.; Arango, I.; Godoy, A.; Lopez, C.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Power input, speed, and efficiency concern people when selecting a transportation means. This study compares multiple e-bikes configurations and presents to the reader scientific criteria to choose the one that fits best for non-trained cyclists, who want to use e-bikes for everyday transportation in cities with steep roads, assuring that the cyclist takes effective part of the power input. Power development, speeds, energy consumption and efficiency result from a mathematical model and experimental data. Configurations vary in motor placement, assistance level, cyclist cadence, wheel type and transmission sets. Results indicate that the motor's placement is the most determining factor in the efficiency of the entire system. Placing the motor in the bottom bracket, allows both the cyclist and the motor to range in the most efficient rpm. As efficiency for the middle drive motor is higher than the hub drive motor, energy consumption in the hub drive motor is 18% higher. Copyright © 2018 Inderscience Enterprises Ltd.
The Effect of Student Work Group Emotional Intelligence on Individual Task Performance in Teams
(SAGE Publications Ltd, 2020-01-01) Román-Calderón J.P.; Aguilar-Barrientos S.; Escalante J.E.; Barbosa J.; Arias Salazar A.; Román-Calderón J.P.; Aguilar-Barrientos S.; Escalante J.E.; Barbosa J.; Arias Salazar A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Background: The development of employability skills is a concern of educational institutions, which must introduce experiential learning scenarios for undergraduate students. Purpose: This study is aimed at testing the relationship between emotional intelligence and individual task performance in teams, during a recruiting activity for an experiential learning program. Methodology/Approach: Self-reported and third rater’s measures were used to assess both variables as part of the selection process of participants on an experiential learning program focused on engineering competitions. Exploratory structural equation modeling was used for data analysis. Findings/Conclusions: Results show partial support of the hypothesis by revealing a significant but apparently counterintuitive relationship. Implications: The study reveals the measurement of employability skills as a challenge and a necessity. For employers, it reinforces that teamwork, socialization, and daily organizational endeavors require the appropriate soft skills to obtain good performance levels. © The Authors 2020.
The Effect of Student Work Group Emotional Intelligence on Individual Task Performance in Teams
(SAGE Publications Ltd, 2020-07-15) Roman, J.; Roman, J.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Erratum to: Dynamic analysis of a recirculation system of micro functional fluids for ink-jet applications (Microsystem Technologies, (2017), 23, 5, (1485-1494), 10.1007/s00542-016-3254-z)
(Springer Verlag, 2017-07-01) Arango, I.; Cañas, M.; Arango, I.; Cañas, M.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
In the original publication of the article, equation (6) and equation (7) were incorrectly published. The correct equations should be as below: (Formula Presented.) (6) (7) In page 7, the second line in the second paragraph should read as follows: This variation is plotted in the range of 20–30 °C; however, the total range of the temperatures is greater as displayed in Eqs. (6) and (7). In page 9, in the Table 7, the words “Head 2” and “Head 3” are repeated. The correct Table 7 is given below: The original article has been updated accordingly. (Table Presented.). © 2017, Springer-Verlag Berlin Heidelberg.
Flow behaviour over a 2D body using the moving particle semi-implicit method with free surface stabilisation
(Springer-Verlag France, 2017-08-01) Perez, C.A.; Garcia, M.J.; Barbosa Perez, Jaime L.; Orrego, Santiago; Quintero, Santiago; Perez, C.A.; Garcia, M.J.; Barbosa Perez, Jaime L.; Orrego, Santiago; Quintero, Santiago; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
The Moving Particle Semi-implicit (MPS) method is a Lagrangian particle method based on the prediction-correction calculation of the velocity field and the Helmhotz-Hodge decomposition. Initially the predicted velocity is calculated with the viscous and external forces terms and then corrected by the gradient of the pressure which is obtained by the solution of the Poisson Pressure's equation. The MPS was developed for non-compressible bodies and it is adequate for free surface problems. However, when used to simulate fluid structure interaction problems, like ship resistance, the original formulation of the method can not accurately compute the pressure distribution over the bodies. This paper proposes a modified MPS method for modelling immerse bodies in an free surface flow. It was found that small variations in the source term of the Poisson Pressure's equation can destabilise simulations. Therefore, a reformulation of the Poisson pressure equation was developed. The results show that the proposed variation produced numerical stabilisation. The free surface particles behave in a good agreement with experimental observations. Also, although pressure fluctuations were still present, satisfactory results were obtained when comparing the drag coefficient with those reported values in the literature.
Full Scale Fatigue Test Performed to the Bolster Beam of a Railway Vehicle
(Springer-Verlag France, 2016-11-01) BARBOSA, JAIME LEONARDO; BARBOSA, JAIME LEONARDO; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Full scale fatigue test performed to the bolster beam of a railway vehicle
(Springer-Verlag France, 2018-02-01) Gutiérrez-Carvajal, R.E.; Betancur, G.R.; Barbosa, J.; Castañeda, L.F.; Zaja¸c, G.; Gutiérrez-Carvajal, R.E.; Betancur, G.R.; Barbosa, J.; Castañeda, L.F.; Zaja¸c, G.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Many structural elements are exposed to conditions of load that are difficult to consider during the design stage, such as environment uncertainties, random impacts, overloads and inherent material idealization amongst others, hence, miss-estimating its life-time cycle. One way to test those designs is to construct a representative full-scale specimen and test it under the most critical load conditions in a controlled laboratory. Herein, we present a case of study of the fatigue test performed over a bolster beam redesigned in Universidad EAFIT belonging to a railway vehicle. The test was composed by three stages, each one testing a different load hypothesis. The bolster beam was instrumented at the most critical locations, following the results of a FEM analysis previously computed. As results, the most critical welds were identified and the total damage computed for an equivalent operation of eighteen-years, and also the behaviour of the specimen in presence of extreme longitudinal loads. © 2016, Springer-Verlag France.
Hydraulic and rotor-dynamic interaction for performance evaluation on a Francis turbine
(Springer-Verlag France, 2017-08-01) Garcia, M.; Laín, S.; Orrego, S.; Barbosa, J.; Quintero, B.; Garcia, M.; Laín, S.; Orrego, S.; Barbosa, J.; Quintero, B.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
This paper proposes a new methodology to evaluate the technical state of a Francis turbine installed in a hydroelectric plant by coupling computational fluid dynamics (CFD) and rotor-dynamic analysis. CFD simulations predicted the hydraulic performance of the turbine. The obtained field forces, due to the fluid-structure interaction over the blades of the runner, were used as boundary condition in the shaft rotor-dynamic numerical model, which accurately predicted the dynamic behavior of the turbine's shaft. Both numerical models were validated with in situ experimental measurements. The CFD model was validated measuring the pressure fluctuations near the rotor-stator interaction area and the torque and radial force in the shaft using strain gages. The rotor-dynamic model was validated using accelerometers installed over the bearings supporting the shaft. Results from both numerical models were in agreement with experimental measurements and provided a full diagnose of the dynamic working condition of the principal systems of the turbine. Implementation of this methodology can be applied to further identify potential failure and improve future designs.
Integration-Free analysis of nonsmooth local dynamics in planar filippov systems
(WORLD SCIENTIFIC PUBL CO PTE LTD, 2009-03-01) Arango, Ivan; Taborda, John Alexander; Arango, Ivan; Taborda, John Alexander; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
In this paper, we present a novel method to analyze the behavior of discontinuous piecewise-smooth autonomous systems (denominated Filippov systems) in the planar neighborhood of the discontinuity boundary (DB). The method uses the evaluation of the vector fields on DB to analyze the nonsmooth local dynamics of the Filippov system without the integration of the ODE sets. The method is useful in the detection of nonsmooth bifurcations in Filippov systems. We propose a classification of the points, events and events combinations on DB. This classification is more complete in comparison with the others previously reported. Additional characteristics as flow direction and sliding stability are included explicitly. The lines and the points are characterized with didactic symbols and the exclusive conditions for their existence are based on geometric criterions. Boolean-valued functions are used to formulate the conditions of existence. Different problems are analyzed with the proposed methodology. © 2009 World Scientific Publishing Company.
Investment strategies in the Latin American agri-business sub-sectors of agricultural commodities, biofuels and meat chains
(Emerald Group Publishing Ltd., 2018-01-01) Saravia-Matus, S.; Saravia Matus, J.; Sotomayor, O.; Rodriguez, A.; Saravia-Matus, S.; Saravia Matus, J.; Sotomayor, O.; Rodriguez, A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de Máquinas
Purpose The purpose of this paper is to review and examine the recent investment trends of firms operating in the food, feed and biofuel production and processing sectors in Latin America. The inter-related nature of these three sub-sectors and the great expansion they have gone through in the last decade showcases a series of socioeconomic and environmental policy challenges thus making it relevant to identify their different business models through a typology. Design/methodology/approach The paper first presents an unprecedented literature review based on field observations and media coverage of agri-business strategies of the food, feed and biofuel production in the region. It then moves to an in-depth analysis of investment operations that serve to classify such firms into a business model typology considering degree of internationalization and integration. The typology is a useful mechanism to enhance public policy analysis and uncover market or government incentives behind business decisions. Findings By focusing on investment strategies, the paper illustrates how both market and government incentives shape and affect the performance and consolidation of different players in the food, feed and biofuel sub-sectors in Latin America. The resulting effects have strong economic as well as social and environmental implications because such economic activities have an impact on global food and energy security. Research limitations/implications Limitations include a reliance on largely qualitative evidence and research methods due to unavailability of consistent numerical data in these specific agri-business sub-sectors. Originality/value This paper is unique in its focus on business models in a particularly relevant set of agri-business sub-sectors in Latin America and its implications to promote investment and innovation in value chain development while considering regional-specific challenges.

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