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30 results about "Electromechanical impedance" patented technology
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The electromechanical impedance (EMI) technique, which uses piezoelectric ceramic lead zirconate titanate (PZT) sensors, has been successfully applied to structural health monitoring. Conventionally, electromechanical (EM) admittance (the inverse of impedance) is used to diagnose structural damage.
Self-processing integrated damage assessment sensor for structural health monitoring
ActiveUS20050114045A1Easy to useAnalysing solids using sonic/ultrasonic/infrasonic wavesSubsonic/sonic/ultrasonic wave measurementStructural health monitoringSelf processing
A small, lightweight, portable, and inexpensive self-processing integrated damage assessment sensor (SPIDAS) that may be temporarily or permanently attached to a structure for structural health monitoring is provided. The SPIDAS device employs an electromechanical impedance measuring method to directly measure the high-frequency local impedance spectrum of the structure, process the electromechanical impedance data, and issue structural health reports that the device may transmit over a wireless connection.
Owner:SOUTH CAROLINA UNIV OF
Compact multi frequency-range impedance tuner
An automatic multi frequency-range electro-mechanical impedance tuner covers frequencies from a low megahertz to a high gigahertz range, by combining a high frequency with one or two a low frequency tuner modules; the low frequency module is made using either variable phase shifter-capacitor or multi-capacitor-transmission line tuner structures. The high frequency module is a single, double or triple probe slide screw tuner covering up to 1.5 decades in frequency; the low frequency tuner is using cascades of three or more capacitor-coax cable tuning sections or a low frequency phase shifter combined with a variable shunt capacitor; the low frequency tuner can operate as low as a few megahertz whereas the high frequency tuner can operate up to several gigahertz. Depending on the application, low frequency parallel-blade capacitors or high frequency coaxial trimmers are used. Typical cross-over frequencies between low and high frequency modules range from 200 to 800 megahertz, lowest frequencies can reach below 10 megahertz and highest frequencies 26 to 40 gigahertz. Appropriate calibration, control and tuning procedures allow for a fully integrated operation.
Owner:TSIRONIS CHRISTOS
Self-processing integrated damage assessment sensor for structural health monitoring
ActiveUS7174255B2Easy to useAnalysing solids using sonic/ultrasonic/infrasonic wavesSubsonic/sonic/ultrasonic wave measurementStructural health monitoringEngineering
Owner:SOUTH CAROLINA UNIV OF
Wideband low frequency impedance tuner
An electro-mechanical impedance tuner generates wideband and complete Smith chart reflection factor coverage at frequencies as low as 1 MHz. It comprises an in-line adjustable linear phase shifter and a variable capacitor connected in parallel to ground. The transmission line, which serves as an adjustable phase shifter of variable electrical length, is made as a cylindrical rotating spiral wire-over-ground transmission line, on which runs a sliding contact, connected with a variable capacitor; the capacitor can be, depending on the frequency, immersed in a dielectric liquid, such as oil (∈r≈3) or alcohol (∈r≈20) for increased capacitance. The cylindrical structure of the spiral transmission line allows for a compact, 1 meter long apparatus at 1 MHz, whereas the required linear electrical length for this type of impedance tuner would be 150 meters in air, or 100 meters when low cost polyethylene dielectric (∈r≈2.25) is used. Cascading two or more tuners allows pre-matching and harmonic tuning.
Owner:TSIRONIS CHRISTOS
Battery pole piece testing method and die for preparing battery pole piece
ActiveCN108490354ASimple test methodThe test method is accurateElectrode manufacturing processesElectrical testingEngineeringPole piece
The invention provides a battery pole piece testing method and a die for preparing a battery pole piece, and belongs to the field of failure analysis research of lithium ion batteries. A battery is disassembled, pre-treatment is carried out on a double-side battery pole piece, and capacity and impedance testing results of the double-side pole piece after treatment are basically the same with thoseof a single-side pole piece in the disassembled battery. The double-side battery pole piece after disassembling of the battery is sliced directly, rubberizing is carried out after that the pole pieceis processed by the die, single-side treatment is completed for the double-side pole piece, the pole piece is assembled into a button cell form, a charging-discharging curve of a half cell and electromechanical impedance spectra of a full cell and a symmetric cell are measured, and the testing method is simple and accurate.
Owner:INST OF PHYSICS - CHINESE ACAD OF SCI
Ultrasonic guided wave and electromechanical impedance-based mobile damage detection method
ActiveCN104597083AMake up for the shortcoming of small detection rangeOvercoming disadvantages of being vulnerable to environmental changesMaterial impedanceNon destructiveCoupling
The invention discloses an ultrasonic guided wave and electromechanical impedance-based mobile damage detection method. The method comprises the following steps: based on the ultrasonic guided wave and electromechanical impedance technologies, firstly scanning and positioning a structural damage by adopting a wave guiding method, and evaluating the damage status by adopting an electromechanical impedance method. The damage detection method combines an ultrasonic guided wave damage detection method and an electromechanical impedance-based damage detection method so as to give play to the advantages of the two and make up the disadvantages of each other; and the method comprises the following steps: firstly, scanning and positioning a structural damage based on guided wave to determine the non-destructive area and a to-be-detected area E, then respectively moving a probe to the non-destructive area and the to-be-detected area E, so that the details of the damage status can be obtained by dry coupling electromechanical impedance characteristic of a mobile probe, and the detection capability of the damage can be greatly improved.
Owner:DALIAN UNIV OF TECH
Intelligent electromechanical impedance sensor used for structure health status monitoring
InactiveCN102435853AOvercome the shortcomings of being unsuitable for on-site monitoringFast operationTransmission systemsResistance/reactance/impedenceElectrical resistance and conductanceSupply management
The invention provides an intelligent electromechanical impedance sensor used for structure health status monitoring, belonging to the structure health monitoring field, relating to a sensor monitoring a structure health status based on an electromechanical impedance method. The sensor is composed of a power supply management module, a microprocessor module, a wireless communication module, an electromechanical impedance sensing module, a multi-channel change over switch and a piezoelectric patch connection terminal. The sensor can detect mechanical impedance change caused by structure health status change and convert the mechanical impedance change into electrical impedance which is easy to measure. The sensor has the advantages of small volume, wireless communication and convenience of installation on an on-site structure. Through measurement of electromechanical impedance which is coupled of the mechanical impedance and the electrical impedance, necessary information is provided for structure health status monitoring and structure failure prediction based on the electromechanical impedance method.
Owner:BEIJING UNIV OF TECH
Electromechanical impedance monitoring method of bolt pre-tightening force under vibration excitation
InactiveCN110068454AIncreased sensitivityMachine part testingResistance/reactance/impedenceAudio power amplifierSignal amplifier
The invention relates to an electromechanical impedance monitoring method of bolt pre-tightening force under vibration excitation. According to the method, a piezoelectric ceramic PZT is pasted to oneside of a to-be-detected bolt, main deformation directions of the bolt and the PZT are collinear, and an outgoing line of a piezoelectric patch is connected to an impedance analyzer; an exciter is fixed below a to-be-detected structure and is connected with a signal amplifier and a signal generator sequentially; a sweep frequency range of the impedance analyzer is set; meanwhile, the signal generator emits a sine pulse signal with fixed frequency to serve as an input signal of the exciter, and the bolt pre-tightening force is changed so that the bolt is changed step by step from a completely-loosened state to a completely-tightened state; and after the pre-tightening force is changed every time, the signal amplifier is started, and the exciter is made to excite the to-be-detected structure; impedance real-part data under different pre-tightening forces is collected, and the working condition under which the bolt is completely tightened is selected as a standard condition; a sensitivefrequency band is selected from the obtained impedance real-part data; a looseness index RMSD of the sensitive frequency band under the different pre-tightening forces is calculated; and the bolt looseness degree can be measured by use of the looseness index and the standard working condition.
Owner:NORTHWESTERN POLYTECHNICAL UNIV
Acoustic device
InactiveUS20060008099A1High aspect ratioIncrease energy contentPlane diaphragmsDeaf-aid setsAuditory radiationCoupling
A bending wave loudspeaker comprising a panel-form radiator and an electromechanical vibration exciter coupled to the radiator, wherein the bending stiffness of the radiator is in the range 0.001 to 1000 Nm, wherein the coupling between the exciter and the radiator is such that a component of the applied energy results in compression waves in the radiator and wherein the radiator has a break in mid-plane symmetry resulting in acoustic radiation. A method of making a bending wave loudspeaker comprising selecting a panel-form radiator and an electromechanical vibration exciter, coupling the exciter to the radiator to have a relationship between the electromechanical impedance of the vibration exciter and the mechanical impedance of the radiator useful to the operating bandwidth of the radiator, arranging the bending stiffness of the radiator to be in the range 0.001 to 1000 Nm, arranging the coupling between the exciter and the radiator to be such that a component of the applied energy results in compression waves in the radiator and providing the radiator with a break in mid-plane symmetry to cause acoustic radiation.
Owner:NEW TRANSDUCERS LTD
Nondestructive testing method for debonding defects of solid rocket engine interface
InactiveCN110243941AExact decompositionDecomposition and transfer are preciseAnalysing solids using sonic/ultrasonic/infrasonic wavesProcessing detected response signalFiberInsulation layer
The invention relates to a nondestructive testing method for debonding defects of a solid rocket engine interface, and the method combines an electromechanical impedance method and a frequency response function method and is used for testing a solid rocket engine combustion chamber interface. The method comprises the following steps of forming a detection system by using a universal equipment NI multi-channel high-speed data acquisition device, a PCB force hammer, a sensor and the like; knocking the surface of a structure to be detected by using the force hammer to provide a pulse-shaped force; and measuring a time domain waveform of a response signal through a signal acquisition program to obtain a frequency response function curve of an engine heat insulation layer / lining layer / propellant interface so as to judge whether the interface structure is intact. The method is used for the flexible and rapid nondestructive detection of the debonding defects of the interface of the solid rocket engine propellant / lining layer / heat insulation layer of the composite fiber material with the diameter of about 2000 mm, particularly for an integrally assembled product, the detection can be realized on a storage site without decomposition, the method has the characteristics of convenience and high efficiency, and the nondestructive testing method is suitable for the rapid inspection of the debonding defects of the interface of the integrally assembled product.
Owner:XIAN AEROSPACE CHEM PROPULTION PLANT +1
Electromechanical impedance method-based portable hardness detection structure and detection method thereof
InactiveCN104729938AThe contact force is stable and knownStable contact forceInvestigating material hardnessKnoop hardness testMiniaturization
The invention discloses an electromechanical impedance method-based portable hardness detection structure and a detection method thereof. The hardness detection structure disclosed by the invention comprises a hollow barrel, a support block, a limiting pipe, a piezoelectric bimorph beam, a needle tip and a penetrator, wherein deformation of the piezoelectric bimorph beam is a known value through a limiting pipe, so as to obtain stable known contact force. A strain gage or a stain measurement system for a response does not need to be used, and only a simple impedance analysis chip is needed, so that the measurement efficiency is accelerated; the measurement stability is improved; the weakness that an existing method cannot be used for ensuring the unstable contact force caused by interference in contact measurement is solved; the electromechanical impedance method-based portable hardness detection structure is efficient, reliable and easy to operate; and through miniaturization and instrumentation, the electromechanical impedance method-based portable hardness detection structure becomes a portable hardness measurement system, and is likely to apply to hardness test outside or in the industrial fields. Therefore, the electromechanical impedance method-based portable hardness detection structure has a certain market application prospect.
Owner:PEKING UNIV
Method for measuring material surface residual stress and system thereof
InactiveCN105784238AImprove efficiencyEasy to measureApparatus for force/torque/work measurementAcousticsImpedance analyzer
The invention discloses a method for measuring material surface residual stress and a system thereof. The method comprises following steps: a press-in needle tip is contacted with a region to be measured of a sample to be measured, and the sample to be measured is pressed in continuously; a strain gauge measures the changes of load F through strain signals output by a strain foil; an impedance analyzer measures electromechanical impedance frequency response of piezoelectric patches of piezoelectric beams; a projection area S of the contact area of the press-in needle tip and the samples to be measured through the electromechanical impedance frequency response; an F-S curve of the press-in process can be obtained through continuously pressing in and then residual stress is obtained. The measurement method is convenient and efficient; material properties such as plasticity and yield stress, etc. are not needed to be known in advance; the method provided by the invention is an on-site measurement method which is suitable for on-site measurement and engineering field measurement, and can be extended to an automation measurement system. The method only requires a strain measuring module and an impedance chip module and therefore, the method is suitable for large-scale measurement.
Owner:PEKING UNIV
Flange bolt looseness detection method based on electromechanical impedance
ActiveCN111413083AReduce in quantityImplement loose detectionMachine part testingResistance/reactance/impedenceControl theoryStructural rigidity
The invention discloses a flange bolt looseness detection method based on electromechanical impedance. The flange bolt looseness detection method comprises the following steps of patch mounting and connection, detection frequency band searching, damage state calibration, actual damage curve acquisition and data analysis. The bolt looseness state is identified by monitoring the change of the impedance value of the piezoelectric patch due to the facts that the bolt looseness can cause reduction of the structural connection rigidity and the electromechanical impedance value is influenced by the structural rigidity of the area. A novel bolt looseness detection method is provided for the maintenance work of the flange structure.
Owner:DALIAN UNIV OF TECH
Corrosion sensor
ActiveCN108872319ARealize quantitative monitoring of corrosionSimple geometryMaterial resistanceEpoxyFirst Fill
The invention discloses a corrosion sensor which comprises a piezoelectric ceramic piece, an iron sheet, a first filled layer, a second filled layer, an outer shell and a shielded conductor, wherein the bottom surface of the piezoelectric ceramic piece is bonded to the top surface of the iron sheet, the top surface and the lateral side of the piezoelectric ceramic piece are coated by epoxy resin to form protection layers, the piezoelectric ceramic piece which is bonded and protected and the iron sheet are arranged in the outer shell, the first filled layer is arranged between the piezoelectricceramic piece and the outer shell, the second filled layer is arranged between the iron sheet and the outer shell, a plurality of through holes are arranged on the top surface and the bottom surfaceof the outer shell, a wire outlet is arranged on the lateral side of the outer shell, one end of the shielded conductor is connected with the piezoelectric ceramic piece, and the other end of the shielded conductor is guided out of the wire outlet. When the corrosion sensor disclosed by the invention is used for monitoring corrosion of an anchoring system, effects of other factors to electromechanical impedance are eliminated; thus, measurement accuracy is improved.
Owner:HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
Concrete structure full life cycle monitoring system and monitoring method
ActiveCN113899789AEnables continuous monitoringImprove stabilityMaterial analysis using acoustic emission techniquesMaterial resistanceFull life cycleArchitectural engineering
The invention discloses a concrete structure full life cycle monitoring system and monitoring method. The system is composed of a cement-based piezoelectric sensor, a concrete structure early strength development monitoring system and a service concrete structure damage process monitoring system. In the concrete pouring stage, early strength development of the concrete structure is monitored by adopting an electromechanical impedance technology. In the concrete service stage, the damage process of a service concrete structure is monitored by adopting an acoustic emission technology. According to the concrete structure full life cycle monitoring system and the monitoring method provided by the invention, the whole life cycle of the concrete structure can be continuously monitored by using the same cement-based piezoelectric sensor, which is of great significance to health monitoring of the concrete structure.
Owner:WUHAN UNIV
A detection method for flange bolt looseness based on electromechanical impedance
ActiveCN111413083BReduce in quantityImplement loose detectionMachine part testingResistance/reactance/impedenceMechanical resistanceClassical mechanics
The invention discloses a method for detecting flange bolt looseness based on electromechanical impedance, comprising the following steps: patching and connecting, searching for detection frequency bands, calibrating damage states, obtaining actual damage curves, and data analysis. The present invention utilizes that bolt looseness will cause structural connection rigidity to drop, and the electromechanical impedance value is affected by the structural rigidity of this region, so the loosening state of the bolt is identified by monitoring the change of the impedance value of the piezoelectric sheet. A new detection method for bolt looseness is provided for the inspection and maintenance of flange structures.
Owner:DALIAN UNIV OF TECH
Low-temperature composite material storage box damage online identification method based on coupling electromechanical impedance
The invention discloses a low-temperature composite material storage box damage online identification method based on coupling electromechanical impedance. The method comprises the following steps: firstly, acquiring reference electromechanical coupling impedance information of a sensor network, and extracting real part and imaginary part signal characteristics; then, acquiring a current impedancesignal according to a time step and comparing the current impedance signal with a reference signal; if the root-mean-square deviation of the two sets of signals is smaller than a threshold value, stating that no damager appears, and if the deviation is larger than the threshold value, needing to further compare the signal characteristics of the peak value of the real part, the slope of the imaginary part, the frequency response of the real part and the like to determine the damage mode; and if the root-mean-square deviation of the sensors exceeding 30% of the total number in the sensor network is larger than the threshold value, affirming that a large-area damage occurs to the structure. According to the method in the invention, a hierarchical damage judgment-damage identification methodis adopted, so that the smoothness of monitoring is guaranteed, and accurate identification of the damage position, the type and the severity degree is guaranteed.
Owner:DALIAN UNIV OF TECH
Mechanical and electrical impedance type detection method and equipment for bone bridging degree of oral cavity implant
InactiveCN111728731AAccurately reflect the degree of bone healingSimple measurement circuitDiagnostic signal processingDiagnostics using vibrationsElectrical resistance and conductanceShear elastic modulus
The invention discloses a mechanical and electrical impedance type detection method for bone bridging degree of an oral cavity implant. The detection method comprises the following steps of generatinga driving signal according to the circuit characteristics of an impedance detection module, detecting and calculating virtual transfer functions of the impedance detection module and an impedance detection circuit under different loading conditions under the action of the driving signal, calculating the electrical impedance of a mechanical and electrical impedance sensor under free state and close connection state through the virtual transfer functions, and calculating a standard-quantitative implant bone bridging degree index by using the electrical impedance as a middle parameter, so as todecrease the influence of parameter errors of a structure and a circuit on the measuring result. The invention also discloses equipment using the mechanical and electrical impedance type detection method for the bone bridging degree of the oral cavity implant. The equipment comprises a mechanical and electrical impedance sensor, a signal cable and a bone bridging degree detector. Mechanical impedance is changed into electrical impedance, the shear elasticity modulus of the junction surface of the whole implant and an alveolar bone, the bone bridging degree of the oral cavity implant is accurately reflected, the circuit is simple, and operations are convenient.
Owner:陕西工业职业技术学院
Debonding damage detection method, device and electronic equipment
ActiveCN113899786BSure flexibleAccurately determineResistance/reactance/impedenceMaterial impedanceMechanical engineeringMaterials science
The present application provides a debonding damage detection method, device, and electronic equipment, which relate to the technical field of structure detection. The method includes: measuring the electromechanical impedance data of each piezoelectric ceramic sensor in a non-destructive state of the test piece to be tested as a first reference signal; when the test piece is damaged, the electromechanical impedance data of each piezoelectric ceramic sensor is measured as the real damage signal, and the first damage index is obtained based on the first reference signal and the real damage signal; The detection area is divided into multiple pixels, and the distance between each pixel and a piezoelectric ceramic sensor is substituted into the damage distribution function, and the weight factor of each pixel relative to a piezoelectric ceramic sensor is calculated based on the first damage index, so as to calculate The damage probability of each pixel point; and determine the disbonding damage position on the test piece to be tested. The method can solve the problem of low detection sensitivity of debonding damage at present.
Owner:NORTHWESTERN POLYTECHNICAL UNIV
A method and sensor for fast on-line monitoring of solid propellant positive vulcanization point
ActiveCN107490603BAchieving a positive cure pointEasy to operateMaterial impedanceEngineeringMechanical engineering
The present invention relates to a method for rapid on-line monitoring of the optimum cure point of a solid propellant, and a sensor. The method comprises that a piezoelectric sensor is implanted into a monitored propellant sample to make the piezoelectric sensor and the propellant sample form an electromechanical impedance coupling structure; and during online detection of a propellant curing process by the piezoelectric sensor, the impedance change rate detected by the piezoelectric sensor is sequentially increased and decreased along with the increase of the curing time so as to draw an electromechanical impedance change rate-propellant curing time curve; and by analyzing the inflection point of the curve, the optimum cure point of the propellant is determined. According to the present invention, the method can be used for rapidly determining the optimum cure point of the propellant, can further be used for monitoring the curing process of the propellant, has advantages of low cost and convenient operation, cannot cause safety, quality and other negative interference to the monitored object, wherein the optimum cure point determination precision can be precise to the hour.
Owner:内蒙合成化工研究所
A portable hardness detection structure and detection method based on electromechanical impedance method
InactiveCN104729938BStable contact forceImprove measurement efficiencyInvestigating material hardnessContact forceHardness
The invention discloses a portable hardness detection structure and a detection method based on an electromechanical impedance method. The hardness testing structure of the present invention includes: a hollow cylinder, a support block, a limit tube, a piezoelectric twin crystal beam, a needle point and a hardness tester indenter; through the limit tube, the deformation of the piezoelectric twin crystal beam is a known value, and then A stable and known contact force can be obtained. The present invention does not require the use of strain gauges and responsive strain measurement systems, and only needs a simple impedance analysis chip, thus speeding up the measurement efficiency and improving the measurement stability; And the weak point that causes the contact force to be unstable; the present invention is efficient, reliable, and easy to operate. By making it miniaturized and instrumented, it becomes a portable hardness measurement system, which may be applied to hardness testing outdoors or on industrial sites. Therefore, the present invention The invention has a certain market application prospect.
Owner:PEKING UNIV
Method for testing battery pole piece and mold for preparing battery pole piece
ActiveCN108490354BSimple test methodThe test method is accurateElectrode manufacturing processesElectrical testingEngineeringPole piece
Owner:INST OF PHYSICS - CHINESE ACAD OF SCI
Piezoelectric wafer active sensor packaging structure
PendingCN113451499AImprove installation efficiencyIncreased durabilityPiezoelectric/electrostrictive device manufacture/assemblyWaferingFlexible circuits
The invention provides a piezoelectric wafer active sensor packaging structure, and belongs to the technical field of electromechanical impedance. The piezoelectric wafer active sensor packaging structure comprises a flexible circuit board, a piezoelectric wafer active sensor and a radio frequency coaxial adapter; an insulated flexible film is used as a base material, metal layers are formed on the two surfaces of the flexible film in an electroplating or deposition mode, and a printed circuit is manufactured; the piezoelectric wafer active sensor and the radio frequency coaxial adapter are installed on the flexible circuit board, and the three are electrically connected; and the piezoelectric wafer active sensor is packaged, so that the test can be completed without adhering or welding a test signal line on the surface of the piezoelectric wafer active sensor, the direct interconnection of the piezoelectric wafer active sensor and a test instrument is realized, the installation efficiency of the piezoelectric wafer active sensor is accelerated, and due to protection of the flexible film, the durability of the piezoelectric wafer active sensor is improved.
Owner:DALIAN UNIV OF TECH
A rust sensor
ActiveCN108872319BRealize quantitative monitoring of corrosionSimple geometryMaterial resistanceEpoxyEngineering
Owner:HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
Mobile Damage Detection Method Based on Ultrasonic Guided Wave and Electromechanical Impedance
ActiveCN104597083BMake up for the shortcoming of small detection rangeOvercoming disadvantages of being vulnerable to environmental changesMaterial impedanceNon destructiveCoupling
The invention discloses an ultrasonic guided wave and electromechanical impedance-based mobile damage detection method. The method comprises the following steps: based on the ultrasonic guided wave and electromechanical impedance technologies, firstly scanning and positioning a structural damage by adopting a wave guiding method, and evaluating the damage status by adopting an electromechanical impedance method. The damage detection method combines an ultrasonic guided wave damage detection method and an electromechanical impedance-based damage detection method so as to give play to the advantages of the two and make up the disadvantages of each other; and the method comprises the following steps: firstly, scanning and positioning a structural damage based on guided wave to determine the non-destructive area and a to-be-detected area E, then respectively moving a probe to the non-destructive area and the to-be-detected area E, so that the details of the damage status can be obtained by dry coupling electromechanical impedance characteristic of a mobile probe, and the detection capability of the damage can be greatly improved.
Owner:DALIAN UNIV OF TECH
Temperature compensation method for damage monitoring of electromechanical impedance structure
InactiveCN108663411AImpact reduction and avoidanceMaterial impedanceStructural health monitoringCurve fitting
The invention discloses a temperature compensation method for the damage monitoring of an electromechanical impedance structure. The method comprises the following steps: the impedance (admittance) signal of a detected test piece is measured and analyzed to study influence of temperature change on the impedance signal; the real part and the imaginary part of the impedance spectrum of the measuredstructure drift in a certain direction with the change of the temperature; a reference signal is compensated by a temperature compensation algorithm based on minimum RMSD, and the frequency and the amplitude compensation quantity of a reference signal are curve-fitted to obtain a relationship between the temperature and two compensation quantities, that is, a reference signal temperature compensation quantity fitting curve; and using the reference signal temperature compensation quantity fitting curve to compensate different temperature monitoring signals. The effective quantitative temperature compensation algorithm based on the electromechanical impedance technology can compensate the damage impedance (admittance) signal in any experimental temperature range, so the accuracy of damage location and quantification based on the electromechanical impedance technology in structural health monitoring is improved.
Owner:BEIJING UNIV OF TECH
Device and method for measuring nonlinear electromechanical impedance spectroscopy of piezoelectric device
PendingCN114295684AEasy to measureAccurate measurementMaterial resistanceResistive circuitsOvervoltage
The invention discloses a piezoelectric device nonlinear electromechanical impedance spectrum measuring device and a measuring method thereof. A tested piezoelectric device is connected with a sampling resistor in series, a first electromagnetic relay and a second electromagnetic relay respectively control a parallel resistor and a parallel capacitor to be connected to the tested piezoelectric device in parallel, a function generator generates a sinusoidal voltage signal, and the sinusoidal voltage signal is applied to a circuit after being amplified by a voltage amplifier. A first digital multimeter and a second digital multimeter are used for respectively measuring voltages generated by voltage amplifiers which are only connected in series with a sampling resistor circuit, connected in parallel with a parallel resistor circuit and connected in parallel with a parallel capacitor circuit and voltages at two ends of a sampling resistor, and a real part and an imaginary part of admittance of the tested piezoelectric device are calculated; when the applied voltage is small, the device is equivalent to an impedance analyzer, and the linear electromechanical impedance spectrum of the piezoelectric device can be conveniently measured; when the applied voltage is large, the nonlinear electromechanical impedance spectrum of the piezoelectric device can be accurately measured, which cannot be achieved by any other device at present.
Owner:PEKING UNIV
A method and system for measuring residual stress on material surface
InactiveCN105784238BImprove efficiencyEasy to measureApparatus for force/torque/work measurementStrain gaugeImpedance analyzer
The invention discloses a method for measuring material surface residual stress and a system thereof. The method comprises following steps: a press-in needle tip is contacted with a region to be measured of a sample to be measured, and the sample to be measured is pressed in continuously; a strain gauge measures the changes of load F through strain signals output by a strain foil; an impedance analyzer measures electromechanical impedance frequency response of piezoelectric patches of piezoelectric beams; a projection area S of the contact area of the press-in needle tip and the samples to be measured through the electromechanical impedance frequency response; an F-S curve of the press-in process can be obtained through continuously pressing in and then residual stress is obtained. The measurement method is convenient and efficient; material properties such as plasticity and yield stress, etc. are not needed to be known in advance; the method provided by the invention is an on-site measurement method which is suitable for on-site measurement and engineering field measurement, and can be extended to an automation measurement system. The method only requires a strain measuring module and an impedance chip module and therefore, the method is suitable for large-scale measurement.
Owner:PEKING UNIV
Solid engine grain health monitoring and life evaluation method
PendingCN113376216AMaterial impedanceManufacturing computing systemsProcess engineeringImpedance spectrum
A solid engine grain health monitoring and life evaluation method belongs to the field of engine monitoring, and is characterized in that a PZT sensor is used for measuring the impedance spectrum of a charge coupling machine embedded in an interface and analyzing the change of the charge coupling machine along with charge aging so as to analyze the aging characteristic, and by monitoring the change of the impedance RMSD of the grain of the engine along with thermal aging change through using a statistical method, the life of the grain of the engine is preliminarily evaluated. The health monitoring and life evaluation method for the grain of the solid engine is not only lossless but also active, and can be used for conveniently and effectively predicting the health monitoring and life of the engine.
Owner:中国人民解放军火箭军工程大学
Method for rapid on-line monitoring of optimum cure point of solid propellant, and sensor
ActiveCN107490603AAchieving a positive cure pointBring securityMaterial impedanceElectricityCoupling
The present invention relates to a method for rapid on-line monitoring of the optimum cure point of a solid propellant, and a sensor. The method comprises that a piezoelectric sensor is implanted into a monitored propellant sample to make the piezoelectric sensor and the propellant sample form an electromechanical impedance coupling structure; and during online detection of a propellant curing process by the piezoelectric sensor, the impedance change rate detected by the piezoelectric sensor is sequentially increased and decreased along with the increase of the curing time so as to draw an electromechanical impedance change rate-propellant curing time curve; and by analyzing the inflection point of the curve, the optimum cure point of the propellant is determined. According to the present invention, the method can be used for rapidly determining the optimum cure point of the propellant, can further be used for monitoring the curing process of the propellant, has advantages of low cost and convenient operation, cannot cause safety, quality and other negative interference to the monitored object, wherein the optimum cure point determination precision can be precise to the hour.
Owner:内蒙合成化工研究所
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