36 results about "Electromechanical impedance" patented technology

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The invention relates to the technical field of concrete detection, in particular to a concrete protective layer void detection method and system based on a detachable piezoelectric ceramic sensor and an electromechanical impedance resonance technology. The detection method comprises the following steps: temporarily fixing a detachable piezoelectric ceramic sensor on a detection point on the surface of a concrete structure; applying an alternating-current sweep-frequency voltage to excite the piezoelectric ceramic sensor, and obtaining an electromechanical impedance signal frequency spectrum; the electromechanical impedance signal frequency spectrum is analyzed, the frequency of a local defect formant is obtained, and according to the frequency of the local defect formant, geometric parameters of a void area are estimated through a defect size and frequency relation model; and moving the sensor and repeatedly detecting other detection points. The detection method has high efficiency and flexibility, and detection can be realized in any environment; the single-point detection speed is high, the efficiency is high, baseline data is not needed for detection, the anti-interference performance is high, and rapid positioning and quantitative evaluation of void damage can be achieved.

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.

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.

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.

The invention discloses a wind power tower monitoring and safety assessment method based on acoustic emission and electromechanical impedance. The method comprises the following steps: arranging piezoelectric patches for acquiring response signals and piezoelectric patches in a reference state on the outer surface of a wind power tower; the method comprises the following steps: setting a triggering threshold value for monitoring an acoustic emission signal and the size of a data buffer area, preprocessing the collected original signal, constructing a time-frequency characteristic matrix, calculating a damage factor and judging cracks; when crack signals are detected, preprocessing of the signals under acoustic emission monitoring is stopped, and broadband excitation signals are applied to the piezoelectric patches; and acquiring response signals of the piezoelectric patches, extracting low-frequency components of the signals, comparing the currently measured impedance spectrum with a reference state, selecting an RMSD index to perform damage evaluation on the wind power tower, identifying the change degree of the structural performance, and quantifying the influence of damage on the structural safety of the wind power tower. According to the invention, high-precision identification of the crack signal is realized, and the monitoring accuracy and the detection efficiency are effectively improved.

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.

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.

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.

The invention discloses a structural health monitoring method and system based on an electromechanical impedance technology. The method comprises the following steps: receiving an impedance curve of each test and storing the impedance curve as a historical impedance curve; meanwhile, starting from receiving the impedance curve of the kth test, executing the following steps on the impedance curve received each time: S100, performing sub-segment division on the impedance curve according to frequency bands, and constructing an RMSD value sequence of the impedance curve according to RMSD values of sub-segments; s200, whether the RMSD value of each sub-segment exceeds a first threshold value or not is judged, and if the RMSD value of each sub-segment does not exceed the first threshold value, the structure is healthy at present; if the sub-segments exceed, marking the exceeded sub-segments as abnormal sub-segments, and executing the step S300 on the abnormal sub-segments one by one; s300, correcting the RMSD value of the abnormal sub-segment; and S400, updating the RMSD value sequence of the impedance curve in the step S100 by adopting the correction value of the RMSD value of the abnormal sub-segment, and judging whether the structure is healthy or damaged according to the corrected RMSD value sequence. The method is suitable for a strong vibration environment, and is successfully applied to damage monitoring of a carbon fiber plate and an aluminum alloy cantilever beam at present.

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.

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.

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.

The invention provides an electromechanical impedance uniform corrosion assessment method for a grounding conductor of a power transmission tower. The corrosion degree of the grounding conductor is assessed by taking the radius variation delta r of the grounding conductor as a corrosion parameter. Solving a model parameter km by using a finite element simulation technology and a least square method based on a model of a system electromechanical impedance real part resonance original frequency fm and a corrosion parameter delta r; and substituting the actually measured fm into the model to predict the delta r so as to evaluate the corrosion degree of the grounding conductor.

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.

The present invention discloses a classification method for electromechanical impedance damage monitoring based on environmental matching, comprising: obtaining the conductance signal of a structure; decomposing the conductance signal into real and imaginary part signals and storing them in a baseline data set, and storing the conductance signals after damage at different temperatures in corresponding test data groups; calculating the correlation coefficients of the baseline data set and the test data groups; obtaining the real part signals corresponding to the test data groups; importing the cross-correlation function to calculate the damage diagnosis index of the structure; and finding two sets of baseline data closest to each set of test data in the baseline data set; taking the maximum value of the cross-correlation function of the real part signal of one set of baseline data as the damage diagnosis index, and taking the maximum value of the cross-correlation function of the real part signals of the two sets of baseline data as the judgment threshold for damage, so as to classify the damage of the structure. The present invention can perform non-destructive damage monitoring on composite material structural parts under temperature change conditions, and reduce false alarms caused by temperature changes.

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.