Fernando D. Goncalves

Instituto Federal de Educação, Ciência e Tecnologia do Pará

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Co-Authors

Mehdi Ahmadian

Virginia Tech

J. D. Carlson

RELX Group (United States)

Jeong‐Hoi Koo

Korea Electric Power Corporation (South Korea)

Corina Sandu

Virginia Tech

André Barros

Universidade Estadual de Campinas (UNICAMP)

Rafael Hideo Lopes Kikuchi

Instituto Federal de Educação, Ciência e Tecnologia do Pará

Baolin Hou

Hunan University of Science and Technology

Hong Zhang

Griffith University

Daniel J. Moutinho

Universidade do Porto

Richard B. Wilder

The University of Texas at Arlington

Cooperative Institutions

Universidade Federal do Pará

Instituto Federal de Educação, Ciência e Tecnologia do Pará

Virginia Tech

Universidade Estadual de Campinas (UNICAMP)

Federal Ministry of Science & Technology

Lord Corporation (United States)

Advanced Dynamics (United States)

Vehicle Control Technologies (United States)

Arizona State University

Federal Center for Technological Education of Minas Gerais

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Research Field

Investigating the magnetorheological effect at high flow velocities

Smart Materials and Structures (2005)

Fernando D. Goncalves Mehdi Ahmadian J. D. Carlson

The objective of this work is to investigate the magnetorheological (MR) effect at high flow velocities. A slit-flow rheometer has been built which allows for high speed testing of MR fluid under varying field strengths. The gap size of the rheometer was chosen to achieve high fluid velocity and high shear rates. With a 1 mm gap size, fluid velocities range from 1 to 37 m s−1 with resulting shear rates ranging from 0.07 × 105 to 2.5 × 105 s−1. In order to evaluate the performance of the fluid, the force required to drive the fluid through the flow channel is measured and force–velocity characteristics are generated. From the force–velocity curves, the apparent viscosity is found. The apparent viscosity is used to calculate the yield stress for several magnetic field strengths. Two MR valve lengths are considered (25.4 and 6.35 mm). At each velocity the yield stress is found using the closed form solution for the non-dimensional yield stress. Fluid dwell time is introduced as the amount of time the fluid spends in the presence of a magnetic field. For the range of velocities considered, fluid dwell times range from 12.4 to 0.18 ms. A reduction in apparent yield stress is observed as dwell time decreases. Results indicate that the MR fluid can achieve 63.2% of the expected yield stress for dwell times greater than 0.6 ms.

Apparent viscosity

Dwell time

Herschel–Bulkley fluid

10.1088/0964-1726/15/1/036

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Citations (80)

INVESTIGATING THE TIME DEPENDENCE OF THE MR EFFECT

International Journal of Modern Physics B (2007)

Fernando D. Goncalves J. D. Carlson

Magnetorheological fluids are known to respond in a matter of milliseconds to the application of a magnetic field. To date, however, very little work has been done to study the time dependence of the MR response. The purpose of this study is to investigate the response time of the fluid. Experiments were conducted on a high shear rate rheometer capable of fluid speeds in excess of 35 m/s. With an MR valve length of 6.35 mm, the resulting dwell times were as low as 0.18 ms. For each of three magnetic field strengths, a reduction in yield stress is observed as dwell time decreases. A model is proposed to represent the time response of the fluid to the application of the magnetic field. The experimental data and the proposed model are used to identify the response time of the fluid for each field strength. Results indicate that as the magnetic field increases, the response time of the MR fluid decreases. For the range of magnetic field strengths considered in this study the response time of the fluid ranged from 0.24 ms to 0.19 ms.

Response time

Dwell time

10.1142/s0217979207045736

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Citations (32)

Investigation of the response time of magnetorheological fluid dampers

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2004)

Jeong‐Hoi Koo Fernando D. Goncalves Mehdi Ahmadian

The primary purpose of this paper is to investigate the response time of magnetorheological (MR) dampers and the effect of operating parameters. Rapid response time is desired for all real-time control applications. In this experimental study, a commercially available MR damper was tested and the response time was found for various operating conditions. The parameters considered include operating current, piston velocity, and system compliance. The authors define the response time as the time required to transition from the initial state to 63.2% of the final state, or one time constant. Using a triangle wave to maintain constant velocity across the damper, various operating currents ranging from 0.5 Amps to 2 Amps were applied and the resulting force was recorded. The results show that, for a given velocity, the response time remains constant as the operating current varies, indicating that the response time is not a function of the applied current. To evaluate the effect of piston velocity on response time, velocities ranging from 0.1 in/s to 3 in/s were tested. The results show that the response time decreases exponentially as the velocity increases, converging on some final value. Further analysis revealed that this result is an artifact of the compliance in the system. To confirm this, a series of tests were conducted in which the compliance of the system was artificially altered. The results of the compliance study indicate that compliance has a significant effect on the response time of the damper.

Response time

Time constant

Piston (optics)

Shock absorber

Rise time

Response analysis

Piston rod

Constant (computer programming)

Magnetorheological damper

10.1117/12.539643

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Citations (39)

In Search of a Suitable Control Policy for Intelligent Vehicle Suspensions

Dynamic Systems and Control (2002)

Fernando D. Goncalves Mehdi Ahmadian

Many control policies, such as skyhook and groundhook control, are now being considered for intelligent vehicle suspensions. Past studies have shown the performance limitations of these policies, as well as others that have been considered for vehicle applications. The performance of three semi-active control policies were studied experimentally under steady-state and transient inputs. Experimental results were obtained using a quarter-car rig and a magneto-rheological damper. The commonly considered skyhook and groundhook control policies were employed and evaluated under a steady-state, or pure tone, input and a transient, or step input. An alternative control technique called “hybrid control,” which attempts to merge the performance benefits of skyhook and groundhook control was also considered. Peak-to-peak displacement and peak-to-peak acceleration were used to evaluate performance. The results indicate that while skyhook and groundhook can offer benefits to either the sprung or unsprung masses, hybrid control can offer benefits to both masses. The compromise inherent in both skyhook and groundhook is eliminated with the use of hybrid control. Both the steady-state and transient dynamics of the sprung and unsprung masses can be reduced below those of passive using hybrid control with an α of 0.5. This corresponds to equal contributions from skyhook control and groundhook control.

Skyhook

Transient (computer programming)

10.1115/imece2002-33462

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Citations (2)

<title>A study on MR fluids subjected to high shear rates and high velocities</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2005)

Fernando D. Goncalves Mehdi Ahmadian

This study intends to identify the behavior of MR fluid subject to high rates of shear and high flow velocities. A high shear rheometer is built which allows for the high velocity testing of MR fluids. The rheometer is capable of fluid velocities ranging from 1 m/s to 37 m/s, with corresponding shear rates ranging from 0.14x10⁵ s^-1 to 2.5x10⁵ s^-1. Fluid behavior is characterized in both the off-state and the on-state. In the off-state, the MR fluid was shown to exhibit nearly Newtonian post-yield behavior. A slight thickening was observed for growing shear rates. This slight thickening can be attributed to the behavior of the carrier fluid. The purpose of the on-state testing was to characterize the MR effect at high flow velocities. MR fluid was run through the rheometer at various flow velocities and a number of magnetic field strengths. The term "dwell time" is introduced and defined as the amount of time the fluid spends in the presence of a magnetic field. Two active valve lengths were considered, which when coupled to the fluid velocities, generated dwell times ranging from 12 ms to 0.18 ms. The yield stress was found from the experimental measurements and the results indicate that the magnitude of the yield stress is sensitive to fluid dwell time. The results from the on-state testing imply that high velocity applications may be subject to diminished controllability for falling dwell times.

10.1117/12.598530

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Citations (5)

YIELD ENRICHMENT IN MR FLUID VALVES

Electrorheological Fluids and Magnetorheological Suspensions (2011)

Fernando D. Goncalves DAVID R. DOBBS

10.1142/9789814340236_0081

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Citations (0)

Caracterização de revestimento de titânia aplicado por aspersão térmica a plasma em liga Ti-6A1-4V para aplicação em implantes

Fernando D. Goncalves

A necessidade de melhorar as características superficiais da liga Ti-4Al-6V usada em implantes ortopédicos, levou à pesquisas no sentido de estudar a modificação da superfície dos implantes através da deposição de revestimentos cerâmicos resistentes à corrosão, ao desgaste e biocompatíveis, por vários métodos: eletroquímica, física a vapor, eletroforética, por sol-gel, biomimética e por aspersão térmica a plasma, entre outras.A aspersão térmica a plasma é o processo mais utilizado comercialmente, pois é rápido e reprodutível.As biocerâmicas mais utilizadas para revestimento, com sucesso, são as de fosfato de cálcio (hidroxiapatita-HA, betafosfato tricálcico [• -TCP] e uma mistura dessas duas fases).A adesão dessas biocerâmicas ao tecido ósseo possuí bom desempenho é bastante discutida na literatura.A comunidade médica tem algumas restrições ao uso desses implantes metálicos revestidos por cerâmicas, com relação à interface metal-cerâmica, cuja adesão é considerada baixa.Neste trabalho foi estudado a adesão metal/cerâmica em implantes revestidos por aspersão térmica à plasma (ATP) com cerâmica, mais especificamente liga de titânio (Ti-6Al-4V) revestida com titânia (TiO 2 ) sem e com tratamento térmico a vácuo, com o intuito de verificar uma possível melhoria nessa adesão.A cerâmica utilizada neste trabalho foi a titânia, uma vez que é uma cerâmica biocompatível e osseointegrável, que é bastante utilizada para revestir implantes.Para a execução do trabalho foram confeccionados diversos corpos de prova, os quais foram revestidos por titânia por aspersão térmica à plasma,

10.47749/t/unicamp.2012.855964

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Citations (0)

HIGH-SHEAR-RATE, VALVE-MODE RHEOMETER FOR MR FLUIDS

Electrorheological Fluids and Magnetorheological Suspensions (2011)

Fernando D. Goncalves J. D. Carlson Richard B. Wilder

Mode (computer interface)

10.1142/9789814340236_0082

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Citations (0)

Experimental Investigation of the Energy Dissipated in a Magneto-Rheological Damper for Semi-Active Vehicle Suspensions

Fernando D. Goncalves Mehdi Ahmadian

Magneto-rheological (MR) fluid dampers are often characterized by their field-dependent yield stress. This fielddependent yield stress and their fast response time make MR fluid dampers attractive alternatives to conventional viscous dampers. In comparing passive dampers with MR dampers, an equivalent viscous damping coefficient is often found from the energy dissipated by the MR damper. This study considers the energy dissipated by the MR damper under semi-active control. A hybrid control policy for semi-active vehicle suspensions is considered. A quarter car rig was used to evaluate the dynamics of the hybrid suspension using an MR damper. The steady-state performance of hybrid control is investigated with regard to the RMS displacements and accelerations of the sprung and unsprung masses. A frequency domain analysis is also presented. The transmissibilities of the sprung and unsprung masses are found using a range specific chirp signal. Results indicate that hybrid control with equal contributions from skyhook and groundhook can offer benefits to both the sprung and unsprung masses. With the performance of the hybrid semi-active suspension known, the study then considers the energy dissipated by the MR damper under hybrid control. An investigation into the possible correlation between performance and the energy dissipated by the MR damper is presented. Force-displacement curves are generated and an energy ratio is introduced. The energy ratio is the energy metric used to evaluate the energy dissipation of the MR damper. The energy ratio is defined as the ratio of the energy dissipated by the MR damper and the energy input into the system. The results indicate that the MR damper under hybrid control can dissipate nearly 70% of the energy input to the system.

Suspension

Skyhook

Damping torque

10.1115/imece2003-55087

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Citations (1)

An alternate operation mode for MR fluids—magnetic gradient pinch

Journal of Physics Conference Series (2009)

Fernando D. Goncalves J. D. Carlson

MR fluids have been employed in a wide variety of applications, providing viable solutions to many engineering challenges. Controllability in MR fluid devices is achieved through one of three commonly recognized operating modes—valve mode, direct-shear mode, and squeeze mode. This paper presents evidence of an alternative valve configuration for controlling MR fluids. This valve design represents a considerable departure from the commonly recognized modes. Specifically, this novel valve design replaces the conventional narrow gap with a relatively large circular orifice, and it changes the way in which the magnetic field interacts with the fluid. With these changes, we present evidence that this novel valve design may offer functionality not currently available in conventional MR fluid valves.

Mode (computer interface)

10.1088/1742-6596/149/1/012050

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Citations (66)