Skip to main content

S. Sherrit

Followers

29

Following

6

Co-authors

7

Public Views

Interests

Uploads

Papers by S. Sherrit

Temperature Dependence of Dielectric, Elastic and Piezoelectric Properties of Pb(Zr x Ti 1 - x )O 3 Ceramics Near the Morphotropic Phase Boundary

by Binu Mukherjee and S. Sherrit

Japanese Journal of Applied Physics, 1997

Smart structures based on piezoelectric materials are now finding applications in a wide variety ... more Smart structures based on piezoelectric materials are now finding applications in a wide variety of environmental conditions. We have used the impedance resonance technique to measure the impedance spectra of lead zirconate titanate ceramic specimens over temperatures ranging between 0ºC and 100ºC. The analysis of the radial, thickness, thickness shear and length extensional modes of resonance have allowed us to determine the temperature dependence of the complete reduced matrix of material constants, [s E , ε T , d], and our results are presented. We have also studied the effect of multiple heating cycles on the material and have observed the occurrence of thermal hysteresis. The causes and the significance of this hysteresis are analysed.

<title>Wireless piezoelectric acoustic-electric power feedthru</title>

by Zensheu Chang, Yoseph Bar-Cohen, and S. Sherrit

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2007, 2007

ABSTRACT

Electrode systems and heat transfer in thermoelectric generator design

The design parameters of a free-standing convection-cooled thermoelectric generator based on sodi... more The design parameters of a free-standing convection-cooled thermoelectric generator based on sodium beta-double-prime alumina are defined. The device uses a heat pipe structure for sodium recirculation. The theoretical conversion efficiency is up to 12 percent for a source temperature of 550 C. The experimental efficiency is less than 2 percent, with the principal limitation in performance resulting from effects associated with sodium and electron flow in the electrodes.

Frequency dispersion and field dependence in the material constants of PVDF-TrFE copolymers in the thickness mode

ISAF '96. Proceedings of the Tenth IEEE International Symposium on Applications of Ferroelectrics, 1996

<title>Emission of multiple types of radiation using a miniature ferroelectric-based single source</title>

Sensor Systems and Networks: Phenomena, Technology, and Applications for NDE and Health Monitoring 2007, 2007

ABSTRACT NASA exploration missions are increasingly seeking to determine existence of past or pre... more ABSTRACT NASA exploration missions are increasingly seeking to determine existence of past or present life, detect water and examine the mineralogy of various planets in the solar system. Determination of the surface and bulk properties of selected samples currently requires multiple analytical instruments, each with an independent type of radiation source. Using multitude of instruments requires high power, mass and volume resulting in high cost and complexity. Recently, the authors developed a ferroelectric based radiation source, which they named Ferrosource, that was demonstrated to emit five radiation types enabling a new generation of compact, low power, low mass multifunctional NDE analytical instruments. The emitted radiation types include visible light, ultraviolet, X-ray, as well as electron and ion beams. These radiation types are already in use in a multitude of instruments for detecting water, performing mineralogical/chemical analysis and for identifying biological markers. This ferroelectric-based source consists of a disk having a continuous ground electrode on one side and a grid-shaped cathode on the other side. This source is placed in a vacuum tube and is used to generate plasma by switching high voltage pulses and the plasma is harnessed to generate the radiation. To make the source more practical and applicable for NASA missions it was miniaturized by about 50 times the original chamber volume and efforts were made to increase its efficiency to compensate for the size reduction. A series of experiments were performed to demonstrate the capability of the developed miniature source. The source, the experiments, and the test results will be described and discussed in this paper.

<title>Frequency dispersion and field dependence in the thickness mode material constants of PVDF-TRFE copolymers made by AMP Sensors Ltd.</title>

1996 Symposium on Smart Materials, Structures, and MEMS, 1998

ABSTRACT A set of thickness resonators of PVDF-TrFE copolymer have been characterized as a functi... more ABSTRACT A set of thickness resonators of PVDF-TrFE copolymer have been characterized as a function of the frequency and DC bias. The first six resonance peaks in the impedance spectra were analyzed to determine the degree of frequency dispersion in the complex elastic, piezoelectric, and dielectric constants. Modeling the dispersion in the material constants as a polynomial in the frequency f produced an excellent fit to the data over the 1 - 30 MHz frequency range. The samples were then tested for non- linearity by analyzing the fundamental resonance as a function of a DC bias field. The field dependence of the PVDF-TrFE samples was much smaller than for comparable samples of a soft PZT.

Microstructural, dielectric, piezoelectric and pyroelectric properties of chemically derived modified lead titanate

ISAF '92: Proceedings of the Eighth IEEE International Symposium on Applications of Ferroelectrics, 1992

Chemical coprecipitation and gel processing techniques have been used to synthesize precursor pow... more Chemical coprecipitation and gel processing techniques have been used to synthesize precursor powders of a modified lead titanate composition. The effects of powder processing parameters and sintering conditions on the microstructure and dielectric, piezoelectric, and pyroelectric properties of the products are discussed. Powders and products produced by the conventional attrition milling process are compared to those produced by chemical processing

The effect of electrode materials on measured piezoelectric properties of ceramics and ceramic-polymer composites

[Proceedings] 1990 IEEE 7th International Symposium on Applications of Ferroelectrics, 1991

<title>High temperature monitoring the height of condensed water in steam pipes</title>

Health Monitoring of Structural and Biological Systems 2011, 2011

An in-service health monitoring system is needed for steam pipes to track through their wall the ... more An in-service health monitoring system is needed for steam pipes to track through their wall the condensation of water. The system is required to measure the height of the condensed water inside the pipe while operating at temperatures that are as high as 250 o C. The system needs to be able to make real time measurements while accounting for the effects of cavitation and wavy water surface. For this purpose, ultrasonic wave in pulse-echo configuration was used and reflected signals were acquired and auto-correlated to remove noise from the data and determine the water height. Transmitting and receiving the waves is done by piezoelectric transducers having Curie temperature that is significantly higher than 250 o C. Measurements were made at temperatures as high as 250 o C and have shown the feasibility of the test method. This manuscript reports the results of this feasibility study.

<title>Complete matrix of the piezoelectric, dielectric, and elastic material constants of 1-3 piezoelectric ceramic/polymer composites</title>

Smart Materials, Structures, and Integrated Systems, 1997

ABSTRACT The results of our analysis of a set of lead zirconate titanate (PZT-5H)/hard polyuretha... more ABSTRACT The results of our analysis of a set of lead zirconate titanate (PZT-5H)/hard polyurethane 1 - 3 piezoelectric composites produced by injection molding are presented. Two groups of samples with 15 and 30 volume percent PZT were analyzed using impedance resonance techniques. Results from the thickness, radial, length thickness, thickness shear, and the length extensional modes allow the determination of the effective material constants. The complete effective (sE, d, (epsilon) T) matrix is presented for the two compositions. The limitations of using resonance techniques to determine composite material properties are discussed.

The dielectric, piezoelectric and hydrostatic properties of PLZT based rainbow ceramics

Proceedings of 1994 IEEE International Symposium on Applications of Ferroelectrics, 1994

Incremental "model-build-test" validation exercise for a 1-D biomedical ultrasonic imaging array

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 1997

Quantitative validation is critical to the comprehensive design and analysis tools to facilitate ... more Quantitative validation is critical to the comprehensive design and analysis tools to facilitate the effective utilization of large-scale modeling in advanced design, development and subsequent optimization of biomedical ultrasonic imaging applications. This work future ultrasonic imaging systems. describes an incremental "model-build-test" validation Over the past couple of years, the computational power exercise centered around a nonproprietary, 5MHz, 1D offered by desktop computer systems has increased linear array design. The step-by-step sequence reported dramatically. Furthermore, the cost of RAM has fallen to here includes piezoceramic slivers, slivers with matching the point where it is not uncommon to find desktop and slivers with both backing and matching. Furthermore, computer systems equipped with more than 1GByte of prior to the fabrication process, all the active and passive RAM. By employing a computationally efficient finitematerial components are accurately characterized. PZFlex, element code such as PZFlex[1], it now becomes possible an explicit time-domain finite element modeling package, to model the entire ultrasonic array assembly, and not be is used to predict the performance of the incremental array confined to simpler "unit-cell" types of analysis. However, components at each stage of the validation exercise.

ChemInform Abstract: Plasma-Sprayed Lead Zirconate Titanate-Glass Composites

ChemInform, 1994

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The use of complex material constants to model the dynamic response of piezoelectric materials

1998 IEEE Ultrasonics Symposium. Proceedings (Cat. No. 98CH36102), 1998

Accurate equivalent circuits for unloaded piezoelectric resonators

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 1997

Equivalent circuit models for unloaded piezoelectric vibrators are presented. The new circuit mod... more Equivalent circuit models for unloaded piezoelectric vibrators are presented. The new circuit model includes terms which take into account the dielectric and piezoelectric loss as well as the mechanical loss found in the standard Van Dyke's model. The new model contains two branches , the motional branch and the static branch, like the Van Dyke's model, however there is no resistance element in the motional branch and the losses (mechanical, dielectric, piezoelectric) associated with the vibrator are represented as imaginary components of the remaining circuit elements (C 0 , C 1 , L 1 ). The model produced impedance curves that very closely matched the impedance calculated by using the equation derived from vibration theory and data from lead zirconate titanate and PVDF copolymer samples. The calculation of the circuit parameters C 0 , C 1 , and L 1 from the complex elastic, dielectric and piezoelectric material constants is straightforward and the model accurately represents the impedance spectra about the fundamental resonance even when the mechanical Q of the resonator is as low as 2. Conversely, If the circuit parameters are known, the material constants including losses can be derived by straightforward calculations without the loss of any information.

The physical acoustics of energy harvesting

2008 IEEE Ultrasonics Symposium, 2008

Energy harvesting systems based on the transformation of acoustic vibrations into electrical ener... more Energy harvesting systems based on the transformation of acoustic vibrations into electrical energy are increasingly being used for niche applications due to the reduction in power consumption of modern day electronic systems. Typically these applications involve extracting energy at remote or isolated locations where local long term power is unavailable or inside sealed or rotating systems where cabling and electrical commutation are problematic. The available acoustic power spectra can be in the form of longitudinal, transverse, bending, hydrostatic or shear waves of frequencies ranging from less than a Hz to 10's of kHz.

Wireline deep drill for exploration of Mars, Europa, and Enceladus

2013 IEEE Aerospace Conference, 2013

ABSTRACT One of the most pressing current questions in space science is whether life has ever ari... more ABSTRACT One of the most pressing current questions in space science is whether life has ever arisen anywhere else in the universe. Water is a critical prerequisite for all life-as-we-know-it, thus the possible exploration targets for extraterrestrial life are bodies that have or had copious liquid: Mars, Europa, and Enceladus. Due to the oxidizing nature of Mars&#39; surface, as well as subsurface liquid water reservoirs present on Europa and Enceladus, the search for evidence of existing life must likely focus on subsurface locations, at depths sufficient to support liquid water or retain biologic signatures. To address these questions, an Auto-Gopher sampler has been developed that is a wireline type drill. This drill is suspended on a tether and its motors and mechanisms are built into a tube that ends with a coring bit. The tether provides the mechanical connection to a rover/lander on a surface as well as power and data communication. Upon penetrating to a target depth, the drill is retracted from the borehole, the core is deposited into a sample transfer system, and the drill is lowered back into the hole. Wireline operation sidesteps one of the major drawbacks of traditional continuous drill string systems by obviating the need for multiple drill sections, which add significantly to the mass and the complexity of the system. The Auto-gopher has been successfully tested in a laboratory environment in rock to a depth of 2 m. Field testing of the drill took place in November, 2012 at the US Gypsum quarry outside Borrego Springs, CA. The drill successfully penetrated to over 3 m depth with an average penetration rate of 1 m/hr.

Composite curved linear array for sonar imaging: construction, testing, and comparison to FEM simulations

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 1997

The design, construction, performance, and comparison to FEM simulation of a broadband 375 kHz, 1... more The design, construction, performance, and comparison to FEM simulation of a broadband 375 kHz, 100 element, composite based, 115 mm radius curved receive array is described. This array was designed for use in a forward-looking, mine-hunting application with 60, 1.5° beams scanning a 900 sector. A 150° sector can be scanned with beamwidths widening beyond the center 90°. The bandwidth was desired to be 250 kHz, centered at 375 kHz. This array was demonstrated using an imaging system constructed by UDI-Fugro as part of a TTCP collaboration. The array was designed by Ultrex Corporation supported by FEM modeling at Weidlinger Associates and the University of Strathclyde. The array was constructed by Materials Systems Inc. (MSI) using their proprietary injection-molded composite technology and was tested by UDI-Fugro. Materials characterization was conducted at the Royal Military College of Canada. The details of the final array design are described including the final composite microstructure, choice of composite filler, matching layer material and dicing pattern, and kerf filler. Array parameters achieved include 330 kHz center frequency, 245 kHz bandwidth, element acceptance angle from 62° at 250 kHz to 48° at 500 kHz, and sensitivity of -193 dB re 1V/uPa. FEM simulations showed excellent correspondence in predicting element electrical impedance

<title>Compact sensitive piezoelectric mass balance for measurement of unconsolidated materials in space</title>

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 2010

ABSTRACT In many in-situ instruments information about the mass of the sample could aid in the in... more ABSTRACT In many in-situ instruments information about the mass of the sample could aid in the interpretation of the data and portioning instruments might require an accurate sizing of the sample mass before dispensing the sample. In addition, on potential sample return missions a method to directly assess the captured sample size would be required to determine if the sampler could return or needs to continue attempting to acquire sample. In an effort to meet these requirements piezoelectric balances were developed using flextensional actuators which are capable of monitoring the mass using two methods. A piezoelectric balance could be used to measure mass directly by monitoring the voltage developed across the piezoelectric which is linear with force, or it could be used in resonance to produce a frequency change proportional to the mass change. In the case of the latter, the piezoelectric actuator/balance would be swept in frequency through its fundamental resonance. If a mass is added to the balance the resonance frequency would shift down proportionally to the mass. By monitoring the frequency shift the mass could be determined. This design would allow for two independent measurements of the mass. In microgravity environments spacecraft thrusters could be used to provide acceleration in order to produce the required force for the first technique or to bring the mass into contact with the balance in the second approach. In addition, the measuring actuators, if driven at higher voltages, could be used to fluidize the powder to aid sample movement. In this paper, we outline some of our design considerations and present the results of a few prototype balances that we have developed.

<title>Smart material/actuator needs in extreme environments in space</title>

Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, 2005

Future missions to the planets and moons in our Solar System may require new technology. Missions... more Future missions to the planets and moons in our Solar System may require new technology. Missions with surface or atmospheric mobility or sample acquisition requirements will need advanced actuation technology to operate in the extreme environments found in the Solar System. Depending on the specific mission this technology may be required to withstand 10's of Kelvin environments or temperatures exceeding that of Venus (460 o C). In addition the technology may have to withstand high radiation and corrosive environments and pressures ranging from high vacuum to 100's of MPa. These challenging mission requirements push the limit in performance even under terrestrial conditions. Motors for mobility platforms, deployment devices or actuators for sampling tools are required that can operate reliably and deliver substantial torque and power. These devices must be lightweight, compact and operate effectively under extreme conditions. This paper will focus on a range of actuators based on electromechanical materials used for the applications discussed above and will present some of the challenges of developing these systems for space applications.

Temperature Dependence of Dielectric, Elastic and Piezoelectric Properties of Pb(Zr x Ti 1 - x )O 3 Ceramics Near the Morphotropic Phase Boundary

by Binu Mukherjee and S. Sherrit

Japanese Journal of Applied Physics, 1997

Smart structures based on piezoelectric materials are now finding applications in a wide variety ... more Smart structures based on piezoelectric materials are now finding applications in a wide variety of environmental conditions. We have used the impedance resonance technique to measure the impedance spectra of lead zirconate titanate ceramic specimens over temperatures ranging between 0ºC and 100ºC. The analysis of the radial, thickness, thickness shear and length extensional modes of resonance have allowed us to determine the temperature dependence of the complete reduced matrix of material constants, [s E , ε T , d], and our results are presented. We have also studied the effect of multiple heating cycles on the material and have observed the occurrence of thermal hysteresis. The causes and the significance of this hysteresis are analysed.

<title>Wireless piezoelectric acoustic-electric power feedthru</title>

by Zensheu Chang, Yoseph Bar-Cohen, and S. Sherrit

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2007, 2007

ABSTRACT

Electrode systems and heat transfer in thermoelectric generator design

The design parameters of a free-standing convection-cooled thermoelectric generator based on sodi... more The design parameters of a free-standing convection-cooled thermoelectric generator based on sodium beta-double-prime alumina are defined. The device uses a heat pipe structure for sodium recirculation. The theoretical conversion efficiency is up to 12 percent for a source temperature of 550 C. The experimental efficiency is less than 2 percent, with the principal limitation in performance resulting from effects associated with sodium and electron flow in the electrodes.

Frequency dispersion and field dependence in the material constants of PVDF-TrFE copolymers in the thickness mode

ISAF '96. Proceedings of the Tenth IEEE International Symposium on Applications of Ferroelectrics, 1996

<title>Emission of multiple types of radiation using a miniature ferroelectric-based single source</title>

Sensor Systems and Networks: Phenomena, Technology, and Applications for NDE and Health Monitoring 2007, 2007

ABSTRACT NASA exploration missions are increasingly seeking to determine existence of past or pre... more ABSTRACT NASA exploration missions are increasingly seeking to determine existence of past or present life, detect water and examine the mineralogy of various planets in the solar system. Determination of the surface and bulk properties of selected samples currently requires multiple analytical instruments, each with an independent type of radiation source. Using multitude of instruments requires high power, mass and volume resulting in high cost and complexity. Recently, the authors developed a ferroelectric based radiation source, which they named Ferrosource, that was demonstrated to emit five radiation types enabling a new generation of compact, low power, low mass multifunctional NDE analytical instruments. The emitted radiation types include visible light, ultraviolet, X-ray, as well as electron and ion beams. These radiation types are already in use in a multitude of instruments for detecting water, performing mineralogical/chemical analysis and for identifying biological markers. This ferroelectric-based source consists of a disk having a continuous ground electrode on one side and a grid-shaped cathode on the other side. This source is placed in a vacuum tube and is used to generate plasma by switching high voltage pulses and the plasma is harnessed to generate the radiation. To make the source more practical and applicable for NASA missions it was miniaturized by about 50 times the original chamber volume and efforts were made to increase its efficiency to compensate for the size reduction. A series of experiments were performed to demonstrate the capability of the developed miniature source. The source, the experiments, and the test results will be described and discussed in this paper.

<title>Frequency dispersion and field dependence in the thickness mode material constants of PVDF-TRFE copolymers made by AMP Sensors Ltd.</title>

1996 Symposium on Smart Materials, Structures, and MEMS, 1998

ABSTRACT A set of thickness resonators of PVDF-TrFE copolymer have been characterized as a functi... more ABSTRACT A set of thickness resonators of PVDF-TrFE copolymer have been characterized as a function of the frequency and DC bias. The first six resonance peaks in the impedance spectra were analyzed to determine the degree of frequency dispersion in the complex elastic, piezoelectric, and dielectric constants. Modeling the dispersion in the material constants as a polynomial in the frequency f produced an excellent fit to the data over the 1 - 30 MHz frequency range. The samples were then tested for non- linearity by analyzing the fundamental resonance as a function of a DC bias field. The field dependence of the PVDF-TrFE samples was much smaller than for comparable samples of a soft PZT.

Microstructural, dielectric, piezoelectric and pyroelectric properties of chemically derived modified lead titanate

ISAF '92: Proceedings of the Eighth IEEE International Symposium on Applications of Ferroelectrics, 1992

Chemical coprecipitation and gel processing techniques have been used to synthesize precursor pow... more Chemical coprecipitation and gel processing techniques have been used to synthesize precursor powders of a modified lead titanate composition. The effects of powder processing parameters and sintering conditions on the microstructure and dielectric, piezoelectric, and pyroelectric properties of the products are discussed. Powders and products produced by the conventional attrition milling process are compared to those produced by chemical processing

The effect of electrode materials on measured piezoelectric properties of ceramics and ceramic-polymer composites

[Proceedings] 1990 IEEE 7th International Symposium on Applications of Ferroelectrics, 1991

<title>High temperature monitoring the height of condensed water in steam pipes</title>

Health Monitoring of Structural and Biological Systems 2011, 2011

An in-service health monitoring system is needed for steam pipes to track through their wall the ... more An in-service health monitoring system is needed for steam pipes to track through their wall the condensation of water. The system is required to measure the height of the condensed water inside the pipe while operating at temperatures that are as high as 250 o C. The system needs to be able to make real time measurements while accounting for the effects of cavitation and wavy water surface. For this purpose, ultrasonic wave in pulse-echo configuration was used and reflected signals were acquired and auto-correlated to remove noise from the data and determine the water height. Transmitting and receiving the waves is done by piezoelectric transducers having Curie temperature that is significantly higher than 250 o C. Measurements were made at temperatures as high as 250 o C and have shown the feasibility of the test method. This manuscript reports the results of this feasibility study.

<title>Complete matrix of the piezoelectric, dielectric, and elastic material constants of 1-3 piezoelectric ceramic/polymer composites</title>

Smart Materials, Structures, and Integrated Systems, 1997

ABSTRACT The results of our analysis of a set of lead zirconate titanate (PZT-5H)/hard polyuretha... more ABSTRACT The results of our analysis of a set of lead zirconate titanate (PZT-5H)/hard polyurethane 1 - 3 piezoelectric composites produced by injection molding are presented. Two groups of samples with 15 and 30 volume percent PZT were analyzed using impedance resonance techniques. Results from the thickness, radial, length thickness, thickness shear, and the length extensional modes allow the determination of the effective material constants. The complete effective (sE, d, (epsilon) T) matrix is presented for the two compositions. The limitations of using resonance techniques to determine composite material properties are discussed.

The dielectric, piezoelectric and hydrostatic properties of PLZT based rainbow ceramics

Proceedings of 1994 IEEE International Symposium on Applications of Ferroelectrics, 1994

Incremental "model-build-test" validation exercise for a 1-D biomedical ultrasonic imaging array

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 1997

Quantitative validation is critical to the comprehensive design and analysis tools to facilitate ... more Quantitative validation is critical to the comprehensive design and analysis tools to facilitate the effective utilization of large-scale modeling in advanced design, development and subsequent optimization of biomedical ultrasonic imaging applications. This work future ultrasonic imaging systems. describes an incremental "model-build-test" validation Over the past couple of years, the computational power exercise centered around a nonproprietary, 5MHz, 1D offered by desktop computer systems has increased linear array design. The step-by-step sequence reported dramatically. Furthermore, the cost of RAM has fallen to here includes piezoceramic slivers, slivers with matching the point where it is not uncommon to find desktop and slivers with both backing and matching. Furthermore, computer systems equipped with more than 1GByte of prior to the fabrication process, all the active and passive RAM. By employing a computationally efficient finitematerial components are accurately characterized. PZFlex, element code such as PZFlex[1], it now becomes possible an explicit time-domain finite element modeling package, to model the entire ultrasonic array assembly, and not be is used to predict the performance of the incremental array confined to simpler "unit-cell" types of analysis. However, components at each stage of the validation exercise.

ChemInform Abstract: Plasma-Sprayed Lead Zirconate Titanate-Glass Composites

ChemInform, 1994

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The use of complex material constants to model the dynamic response of piezoelectric materials

1998 IEEE Ultrasonics Symposium. Proceedings (Cat. No. 98CH36102), 1998

Accurate equivalent circuits for unloaded piezoelectric resonators

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 1997

Equivalent circuit models for unloaded piezoelectric vibrators are presented. The new circuit mod... more Equivalent circuit models for unloaded piezoelectric vibrators are presented. The new circuit model includes terms which take into account the dielectric and piezoelectric loss as well as the mechanical loss found in the standard Van Dyke's model. The new model contains two branches , the motional branch and the static branch, like the Van Dyke's model, however there is no resistance element in the motional branch and the losses (mechanical, dielectric, piezoelectric) associated with the vibrator are represented as imaginary components of the remaining circuit elements (C 0 , C 1 , L 1 ). The model produced impedance curves that very closely matched the impedance calculated by using the equation derived from vibration theory and data from lead zirconate titanate and PVDF copolymer samples. The calculation of the circuit parameters C 0 , C 1 , and L 1 from the complex elastic, dielectric and piezoelectric material constants is straightforward and the model accurately represents the impedance spectra about the fundamental resonance even when the mechanical Q of the resonator is as low as 2. Conversely, If the circuit parameters are known, the material constants including losses can be derived by straightforward calculations without the loss of any information.

The physical acoustics of energy harvesting

2008 IEEE Ultrasonics Symposium, 2008

Energy harvesting systems based on the transformation of acoustic vibrations into electrical ener... more Energy harvesting systems based on the transformation of acoustic vibrations into electrical energy are increasingly being used for niche applications due to the reduction in power consumption of modern day electronic systems. Typically these applications involve extracting energy at remote or isolated locations where local long term power is unavailable or inside sealed or rotating systems where cabling and electrical commutation are problematic. The available acoustic power spectra can be in the form of longitudinal, transverse, bending, hydrostatic or shear waves of frequencies ranging from less than a Hz to 10's of kHz.

Wireline deep drill for exploration of Mars, Europa, and Enceladus

2013 IEEE Aerospace Conference, 2013

ABSTRACT One of the most pressing current questions in space science is whether life has ever ari... more ABSTRACT One of the most pressing current questions in space science is whether life has ever arisen anywhere else in the universe. Water is a critical prerequisite for all life-as-we-know-it, thus the possible exploration targets for extraterrestrial life are bodies that have or had copious liquid: Mars, Europa, and Enceladus. Due to the oxidizing nature of Mars&#39; surface, as well as subsurface liquid water reservoirs present on Europa and Enceladus, the search for evidence of existing life must likely focus on subsurface locations, at depths sufficient to support liquid water or retain biologic signatures. To address these questions, an Auto-Gopher sampler has been developed that is a wireline type drill. This drill is suspended on a tether and its motors and mechanisms are built into a tube that ends with a coring bit. The tether provides the mechanical connection to a rover/lander on a surface as well as power and data communication. Upon penetrating to a target depth, the drill is retracted from the borehole, the core is deposited into a sample transfer system, and the drill is lowered back into the hole. Wireline operation sidesteps one of the major drawbacks of traditional continuous drill string systems by obviating the need for multiple drill sections, which add significantly to the mass and the complexity of the system. The Auto-gopher has been successfully tested in a laboratory environment in rock to a depth of 2 m. Field testing of the drill took place in November, 2012 at the US Gypsum quarry outside Borrego Springs, CA. The drill successfully penetrated to over 3 m depth with an average penetration rate of 1 m/hr.

Composite curved linear array for sonar imaging: construction, testing, and comparison to FEM simulations

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 1997

The design, construction, performance, and comparison to FEM simulation of a broadband 375 kHz, 1... more The design, construction, performance, and comparison to FEM simulation of a broadband 375 kHz, 100 element, composite based, 115 mm radius curved receive array is described. This array was designed for use in a forward-looking, mine-hunting application with 60, 1.5° beams scanning a 900 sector. A 150° sector can be scanned with beamwidths widening beyond the center 90°. The bandwidth was desired to be 250 kHz, centered at 375 kHz. This array was demonstrated using an imaging system constructed by UDI-Fugro as part of a TTCP collaboration. The array was designed by Ultrex Corporation supported by FEM modeling at Weidlinger Associates and the University of Strathclyde. The array was constructed by Materials Systems Inc. (MSI) using their proprietary injection-molded composite technology and was tested by UDI-Fugro. Materials characterization was conducted at the Royal Military College of Canada. The details of the final array design are described including the final composite microstructure, choice of composite filler, matching layer material and dicing pattern, and kerf filler. Array parameters achieved include 330 kHz center frequency, 245 kHz bandwidth, element acceptance angle from 62° at 250 kHz to 48° at 500 kHz, and sensitivity of -193 dB re 1V/uPa. FEM simulations showed excellent correspondence in predicting element electrical impedance

<title>Compact sensitive piezoelectric mass balance for measurement of unconsolidated materials in space</title>

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 2010

ABSTRACT In many in-situ instruments information about the mass of the sample could aid in the in... more ABSTRACT In many in-situ instruments information about the mass of the sample could aid in the interpretation of the data and portioning instruments might require an accurate sizing of the sample mass before dispensing the sample. In addition, on potential sample return missions a method to directly assess the captured sample size would be required to determine if the sampler could return or needs to continue attempting to acquire sample. In an effort to meet these requirements piezoelectric balances were developed using flextensional actuators which are capable of monitoring the mass using two methods. A piezoelectric balance could be used to measure mass directly by monitoring the voltage developed across the piezoelectric which is linear with force, or it could be used in resonance to produce a frequency change proportional to the mass change. In the case of the latter, the piezoelectric actuator/balance would be swept in frequency through its fundamental resonance. If a mass is added to the balance the resonance frequency would shift down proportionally to the mass. By monitoring the frequency shift the mass could be determined. This design would allow for two independent measurements of the mass. In microgravity environments spacecraft thrusters could be used to provide acceleration in order to produce the required force for the first technique or to bring the mass into contact with the balance in the second approach. In addition, the measuring actuators, if driven at higher voltages, could be used to fluidize the powder to aid sample movement. In this paper, we outline some of our design considerations and present the results of a few prototype balances that we have developed.

<title>Smart material/actuator needs in extreme environments in space</title>

Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, 2005

Future missions to the planets and moons in our Solar System may require new technology. Missions... more Future missions to the planets and moons in our Solar System may require new technology. Missions with surface or atmospheric mobility or sample acquisition requirements will need advanced actuation technology to operate in the extreme environments found in the Solar System. Depending on the specific mission this technology may be required to withstand 10's of Kelvin environments or temperatures exceeding that of Venus (460 o C). In addition the technology may have to withstand high radiation and corrosive environments and pressures ranging from high vacuum to 100's of MPa. These challenging mission requirements push the limit in performance even under terrestrial conditions. Motors for mobility platforms, deployment devices or actuators for sampling tools are required that can operate reliably and deliver substantial torque and power. These devices must be lightweight, compact and operate effectively under extreme conditions. This paper will focus on a range of actuators based on electromechanical materials used for the applications discussed above and will present some of the challenges of developing these systems for space applications.