Mojtaba Ghodsi - Academia.edu (original) (raw)

Papers by Mojtaba Ghodsi

International Journal of the Physical Sciences, 2011

In this research, galfenol (iron-gallium alloy) is exploited to make a miniature actuator. The re... more In this research, galfenol (iron-gallium alloy) is exploited to make a miniature actuator. The relationship between displacement and the applied current is measured. Furthermore, the dynamic behaviors of the actuator in wide range of temperature from cryogenic environment (77 K) to room temperature (RT) are investigated numerically and experimentally. Although, the length of galfenol bar is 10 mm and the maximum strain of annealed galfenol bar is 200 ppm, the large displacements of 37 and 25 μm are achievable at RT and 77 K, respectively when the coil is energized by ±1 A. The natural frequency of this actuator at RT and 77K is 1015 and 1075 Hz, respectively. Furthermore, modal analysis predicts the natural frequency of the actuator by maximum 9% error. Low hysteresis behavior makes this actuator suitable for positioning at both, RT and 77 K. It is also found that the low quality factor of actuator at RT is related to Joule heat dissipation.

Advances in Nanocomposite Research, Aug 6, 2014

Http Dx Doi Org 10 1080 10426914 2014 921710, Jul 7, 2014

Physica C, 2006

In this paper we propose a new experimental method to investigate the principle of 'Mixed-μ' levi... more In this paper we propose a new experimental method to investigate the principle of 'Mixed-μ' levitation systems. To confirm our claim, we measured the attractive force and the variation of flux passing through both, the HTS sample and the face surface of iron yoke, when the yoke is approached/retreated to the surface of field-cooled HTS sample. It is revealed that when the diameter of the yoke is less than the diameter of the HTS, in the small gap by reducing the gap, the flux which passes through the face surface of the yoke and consequently the attractive force will decrease. Therefore, stable levitation is achievable. However, when the diameter of yoke is equal to the diameter of the HTS, the magnetic flux will not decrease for a reducing gap and stable levitation is unfeasible. Briefly, stable levitation is achievable when the yoke diameter is less than the HTS's diameter. Additionally, as the yoke is approached to the HTS the flux variation of the HTS in 77 K is negligible compare to the flux variation of the HTS in the room temperature. Therefore, in superconductivity state the pinned fluxes in the HTS samples remain approximately constant and the HTS acts as a 'magnetic isolator'. This specification can be used to simulate the behavior of field-cooled HTS by the FEM software.

Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, and Civil Infrastructure 2016, 2016

Transparent ferroelectric thin films based on solid solutions of Lead Zirconate Titanate _Pb(Zr 0... more Transparent ferroelectric thin films based on solid solutions of Lead Zirconate Titanate _Pb(Zr 0.52 ,Ti 0.48 )O 3 -(PZT)_ and Bismuth Titanate _Bi 4 Ti 3 O 12 -(BiT)_ perovskite structures, were prepared by Photochemical Metal Organic Decomposition (PMOD) spin-coating technique as electromechanical transducers used in optoelectronic devices like piezo-touch screens. Both solutions were deposited on flat and convex amorphous glass (SiO 2 ) substrates by repetitive successive multi-step coating to poke-charge the device or detect the touch point coordinate. After optimized coating process, films with satisfied properties were dense, crack free and optically transparent. X-ray diffraction and FESEM analyses confirmed the phase formation and grain morphology, respectively. The effects of UV exposure, precursor type and annealing temperature (600-800°C) were investigated on microstructural and electrical properties of deposited thin films. Piezoelectric dispersive and capacitive sensing approaches were discussed as well as optical properties of both films were analyzed as a function of thickness ranging from 30 to 300 nm. P-E loop was measured at 1 kHz as well as relatively low remnant polarization (Pr=8.6 µC cm -2 and 5.1 µC cm -2 ), and coercive field (E c = 115 and 90 kV cm -1 ) were obtained for PZT and BiT respectively.

The International Journal of Advanced Manufacturing Technology, 2014

In this paper, a new voltage induction synchronous electrostatic motor (VISE motor) is introduced... more In this paper, a new voltage induction synchronous electrostatic motor (VISE motor) is introduced, and its performance is analyzed using analytical modeling. In the proposed motor, compared to similar size electrostatic motors, the power is significantly improved by using active electrodes on both rotor and stator. Besides, the rotor's electrodes are charged indirectly (via induction electrodes supplied on both the rotor and stator) to eliminate the undesirable wiring system. This leads to the remarkable features of the new design, including the simplicity, compactness, and light weight despite the feasibility of providing contactless rotor. In order to investigate the performance, the approach of the capacitance coefficient matrix has been used in which the coefficients are numerically calculated using the finite element method. In addition, the induced voltages and torque equation of motor are analytically derived and verified using the fabricated prototype and experimental setup. Kinetics, design, and fabrication process of a prototype are presented, and some performance parameters of motor such as ripple, maximum speed, and synchronousness are experimentally examined. To improve the performance and smoothness of motor rotation, the skew design for rotor electrodes is used and evaluated by both modeling and experiments. There is an excellent agreement between the experimental observations and analytical results, both indicating the considerable improvement in the motor power.

Journal of Magnetism and Magnetic Materials, 2015

Structural health monitoring of stationary and moving structures has been considered based on ele... more Structural health monitoring of stationary and moving structures has been considered based on electromechanical impedance/admittance (EMI/EMA) spectrum of deposited piezoelectric thick films as wafer active transducers. This method is one of the effective approaches to predict the probable damages in a variety of sensitive structures like turbofans, compressors, and specifically titanium or super alloy blades in aerospace industries. In this study, thick piezoelectric films of a) PbZr0.52Ti0.48O3- PZT, b) Bi4Ti3O12-BiT, c) PZT-PZT composite, and d) PZT-BiT composite, were deposited on the convex surfaces of nickel-based super alloy blades Ruston-TA 1750 (IN738) and Pratt&Whitney JT8D (IN718) for structural health monitoring with different thicknesses and properties using photochemical metal-organic deposition and hybrid sol-gel techniques. ...

This research presents a novel "zero-power" actuator for cryogenic conditions by combining a magn... more This research presents a novel "zero-power" actuator for cryogenic conditions by combining a magnetostrictive bimetal with a bulk high temperature superconductor (HTS) sample. This actuator is based on two phenomena; "pinning effect", and "magnetostrictive bimetal". The relationship between displacement of actuator and applied current was measured when the thickness of the HTS samples was 1, 2, and 3 mm. It was found that because of pinning effect part of the magnetic flux (energy), generated by the coil can be trapped (stored) in the HTS samples. Consequently, the actuator can be held in the desired position when its power is switched off. "Holding range" of actuator is directly proportional to the thickness of the HTS samples. The holding range of 4.5 m for 1 mm thickness of the HTS increases to 12 m for 3 mm thickness. The controllability of the actuator over its holding range was also demonstrated.

Electrostatic motors are presented special advantages compare to electromagnetic motors such as l... more Electrostatic motors are presented special advantages compare to electromagnetic motors such as light-weight, compactness and simple to fabricating. Due to these capabilities, recently, many researchers are working on electrostatic motors to make them applicable in industries. Accordingly, in this paper a new design idea for these motors is investigated theoretically and experimentally. This motor has driving electrodes on both rotor and stator, however, no wire is attached to rotor and signals are transferred to rotor using the induction electrodes. Modeling is implemented to study the effective parameters on performance. Then, using the modeling results, the design parameters are optimized using numerical method to improve the torque and minimize the ripple. Optimization findings are identified an optimum value for ratio of width to gap for driving electrodes and an optimum value for ratio of induction electrodes surface to total surface. Finally, the motor performance is evaluate...

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, 2015

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, 2015

Journal of Magnetism and Magnetic Materials, 2015

In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and eff... more In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and effects of magnetic field frequency, peak of magnetic flux density and diameter of Terfenol-D on the eddy currents losses are investigated. To provide reliable data for the purpose of the paper, an experimental laboratory is fabricated and used to obtain major and minor hysteresis loops of Terfenol-D at different frequencies.

Smart Materials Research, 2014

This paper presents a brief experimental comparative study on electrical and dielectric propertie... more This paper presents a brief experimental comparative study on electrical and dielectric properties of two sets of porous and nonporous MRNCs, each including five samples of film-shaped magnetorheological nanocomposites (MRNCs) based on room temperature vulcanized (RTV) silicone rubber and nanosized carbonyl iron particles (CIPs). The electrical and dielectric properties of porous and nonporous MRNCs were measured at five different filler concentrations. Several experiments were performed to measure the volume resistivity, dielectric constant, and dielectric loss. The MRNCs dielectric properties were analysed with respect to the parameters like frequency and CIPs loadings. The electrical conductivity was studied in terms of volume resistivity. The comparative investigation suggests the porous MRNCs for smart and light-weighted structures those benefits from a lower electrical property, dielectric losses, and dielectric constants.

IEEE Transactions on Magnetics, 2015

International Journal of the Physical Sciences, 2011

In this research, galfenol (iron-gallium alloy) is exploited to make a miniature actuator. The re... more In this research, galfenol (iron-gallium alloy) is exploited to make a miniature actuator. The relationship between displacement and the applied current is measured. Furthermore, the dynamic behaviors of the actuator in wide range of temperature from cryogenic environment (77 K) to room temperature (RT) are investigated numerically and experimentally. Although, the length of galfenol bar is 10 mm and the maximum strain of annealed galfenol bar is 200 ppm, the large displacements of 37 and 25 μm are achievable at RT and 77 K, respectively when the coil is energized by ±1 A. The natural frequency of this actuator at RT and 77K is 1015 and 1075 Hz, respectively. Furthermore, modal analysis predicts the natural frequency of the actuator by maximum 9% error. Low hysteresis behavior makes this actuator suitable for positioning at both, RT and 77 K. It is also found that the low quality factor of actuator at RT is related to Joule heat dissipation.

Advances in Nanocomposite Research, Aug 6, 2014

Http Dx Doi Org 10 1080 10426914 2014 921710, Jul 7, 2014

Physica C, 2006

In this paper we propose a new experimental method to investigate the principle of 'Mixed-μ' levi... more In this paper we propose a new experimental method to investigate the principle of 'Mixed-μ' levitation systems. To confirm our claim, we measured the attractive force and the variation of flux passing through both, the HTS sample and the face surface of iron yoke, when the yoke is approached/retreated to the surface of field-cooled HTS sample. It is revealed that when the diameter of the yoke is less than the diameter of the HTS, in the small gap by reducing the gap, the flux which passes through the face surface of the yoke and consequently the attractive force will decrease. Therefore, stable levitation is achievable. However, when the diameter of yoke is equal to the diameter of the HTS, the magnetic flux will not decrease for a reducing gap and stable levitation is unfeasible. Briefly, stable levitation is achievable when the yoke diameter is less than the HTS's diameter. Additionally, as the yoke is approached to the HTS the flux variation of the HTS in 77 K is negligible compare to the flux variation of the HTS in the room temperature. Therefore, in superconductivity state the pinned fluxes in the HTS samples remain approximately constant and the HTS acts as a 'magnetic isolator'. This specification can be used to simulate the behavior of field-cooled HTS by the FEM software.

Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, and Civil Infrastructure 2016, 2016

Transparent ferroelectric thin films based on solid solutions of Lead Zirconate Titanate _Pb(Zr 0... more Transparent ferroelectric thin films based on solid solutions of Lead Zirconate Titanate _Pb(Zr 0.52 ,Ti 0.48 )O 3 -(PZT)_ and Bismuth Titanate _Bi 4 Ti 3 O 12 -(BiT)_ perovskite structures, were prepared by Photochemical Metal Organic Decomposition (PMOD) spin-coating technique as electromechanical transducers used in optoelectronic devices like piezo-touch screens. Both solutions were deposited on flat and convex amorphous glass (SiO 2 ) substrates by repetitive successive multi-step coating to poke-charge the device or detect the touch point coordinate. After optimized coating process, films with satisfied properties were dense, crack free and optically transparent. X-ray diffraction and FESEM analyses confirmed the phase formation and grain morphology, respectively. The effects of UV exposure, precursor type and annealing temperature (600-800°C) were investigated on microstructural and electrical properties of deposited thin films. Piezoelectric dispersive and capacitive sensing approaches were discussed as well as optical properties of both films were analyzed as a function of thickness ranging from 30 to 300 nm. P-E loop was measured at 1 kHz as well as relatively low remnant polarization (Pr=8.6 µC cm -2 and 5.1 µC cm -2 ), and coercive field (E c = 115 and 90 kV cm -1 ) were obtained for PZT and BiT respectively.

The International Journal of Advanced Manufacturing Technology, 2014

In this paper, a new voltage induction synchronous electrostatic motor (VISE motor) is introduced... more In this paper, a new voltage induction synchronous electrostatic motor (VISE motor) is introduced, and its performance is analyzed using analytical modeling. In the proposed motor, compared to similar size electrostatic motors, the power is significantly improved by using active electrodes on both rotor and stator. Besides, the rotor's electrodes are charged indirectly (via induction electrodes supplied on both the rotor and stator) to eliminate the undesirable wiring system. This leads to the remarkable features of the new design, including the simplicity, compactness, and light weight despite the feasibility of providing contactless rotor. In order to investigate the performance, the approach of the capacitance coefficient matrix has been used in which the coefficients are numerically calculated using the finite element method. In addition, the induced voltages and torque equation of motor are analytically derived and verified using the fabricated prototype and experimental setup. Kinetics, design, and fabrication process of a prototype are presented, and some performance parameters of motor such as ripple, maximum speed, and synchronousness are experimentally examined. To improve the performance and smoothness of motor rotation, the skew design for rotor electrodes is used and evaluated by both modeling and experiments. There is an excellent agreement between the experimental observations and analytical results, both indicating the considerable improvement in the motor power.

Journal of Magnetism and Magnetic Materials, 2015

Structural health monitoring of stationary and moving structures has been considered based on ele... more Structural health monitoring of stationary and moving structures has been considered based on electromechanical impedance/admittance (EMI/EMA) spectrum of deposited piezoelectric thick films as wafer active transducers. This method is one of the effective approaches to predict the probable damages in a variety of sensitive structures like turbofans, compressors, and specifically titanium or super alloy blades in aerospace industries. In this study, thick piezoelectric films of a) PbZr0.52Ti0.48O3- PZT, b) Bi4Ti3O12-BiT, c) PZT-PZT composite, and d) PZT-BiT composite, were deposited on the convex surfaces of nickel-based super alloy blades Ruston-TA 1750 (IN738) and Pratt&Whitney JT8D (IN718) for structural health monitoring with different thicknesses and properties using photochemical metal-organic deposition and hybrid sol-gel techniques. ...

This research presents a novel "zero-power" actuator for cryogenic conditions by combining a magn... more This research presents a novel "zero-power" actuator for cryogenic conditions by combining a magnetostrictive bimetal with a bulk high temperature superconductor (HTS) sample. This actuator is based on two phenomena; "pinning effect", and "magnetostrictive bimetal". The relationship between displacement of actuator and applied current was measured when the thickness of the HTS samples was 1, 2, and 3 mm. It was found that because of pinning effect part of the magnetic flux (energy), generated by the coil can be trapped (stored) in the HTS samples. Consequently, the actuator can be held in the desired position when its power is switched off. "Holding range" of actuator is directly proportional to the thickness of the HTS samples. The holding range of 4.5 m for 1 mm thickness of the HTS increases to 12 m for 3 mm thickness. The controllability of the actuator over its holding range was also demonstrated.

Electrostatic motors are presented special advantages compare to electromagnetic motors such as l... more Electrostatic motors are presented special advantages compare to electromagnetic motors such as light-weight, compactness and simple to fabricating. Due to these capabilities, recently, many researchers are working on electrostatic motors to make them applicable in industries. Accordingly, in this paper a new design idea for these motors is investigated theoretically and experimentally. This motor has driving electrodes on both rotor and stator, however, no wire is attached to rotor and signals are transferred to rotor using the induction electrodes. Modeling is implemented to study the effective parameters on performance. Then, using the modeling results, the design parameters are optimized using numerical method to improve the torque and minimize the ripple. Optimization findings are identified an optimum value for ratio of width to gap for driving electrodes and an optimum value for ratio of induction electrodes surface to total surface. Finally, the motor performance is evaluate...

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, 2015

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, 2015

Journal of Magnetism and Magnetic Materials, 2015

In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and eff... more In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and effects of magnetic field frequency, peak of magnetic flux density and diameter of Terfenol-D on the eddy currents losses are investigated. To provide reliable data for the purpose of the paper, an experimental laboratory is fabricated and used to obtain major and minor hysteresis loops of Terfenol-D at different frequencies.

Smart Materials Research, 2014

This paper presents a brief experimental comparative study on electrical and dielectric propertie... more This paper presents a brief experimental comparative study on electrical and dielectric properties of two sets of porous and nonporous MRNCs, each including five samples of film-shaped magnetorheological nanocomposites (MRNCs) based on room temperature vulcanized (RTV) silicone rubber and nanosized carbonyl iron particles (CIPs). The electrical and dielectric properties of porous and nonporous MRNCs were measured at five different filler concentrations. Several experiments were performed to measure the volume resistivity, dielectric constant, and dielectric loss. The MRNCs dielectric properties were analysed with respect to the parameters like frequency and CIPs loadings. The electrical conductivity was studied in terms of volume resistivity. The comparative investigation suggests the porous MRNCs for smart and light-weighted structures those benefits from a lower electrical property, dielectric losses, and dielectric constants.

IEEE Transactions on Magnetics, 2015