Harbin Institute of Technology

Weijia Shi

Jiubin Tan

Bo Zhao

Jiaxin Li

Bingquan Wang

Xuyang Yu

Xue Qi

An ultrasonic measurement method for plane stress on the basis of a multi-wafer air-coupled transducer relates to the technical field of ultrasonic testing. The method solves problems that a traditional measurement method for plane stress generally computes the plane stress by changing at least 3 different measurement directions and obtaining information such as an acoustic time difference in the 3 measurement directions by using a pair of contact ultrasonic transducers, which is too complicated in operation, and a coupling agent can influence measurement accuracy of the plane stress. The method includes: emitting, by an excitation signal transmission end, an ultrasonic wave passing a wafer of the multi-wafer air-coupled transducer to a member to be measured; receiving, by an excitation signal reception end, an echo returned from the member to be measured through a corresponding wafer of the multi-wafer air-coupled transducer; obtaining an acoustic time difference of lamb waves through data processing according to the ultrasonic wave and the echo; and obtaining first principal stress, second principal stress and an included angle between the first principal stress and a fiber direction of an orthotropic composite material according to the acoustic time difference of the lamb waves. The method is suitable for the field of plane stress testing.

Ultrasonic measurement method for plane stress on the basis of multi-wafer air-coupled transducer

An air-coupled ultrasonic plane stress detection method for a composite material based on dual-modal sound-time ratios of a Lamb wave includes: S1: assembling a detection device; S2: based on the detection device and the dual-modal sound-time ratios of the Lamb wave in S1, using unidirectionally loaded stress to obtain different stress coefficient relations; S3: based on the stress coefficient relations in S2, solving stress coefficients; S4: based on the stress coefficients in S3, acquiring three sound-time ratios; S5: based on the sound-time ratios in S4, describing a stress state of a detection point; and S6: repeating S4 and S5 till completing detection and scanning. The method improves the accuracy of stress coefficient calibration and air-coupled ultrasonic stress representation of a composite material panel greatly.

Air-coupled ultrasonic plane stress detection method for composite material based on dual-modal sound-time ratios of lamb wave

The disclosure provides a method, system, device and medium for online monitoring of a plane stress field without baseline data based on a piezoelectric transducer array. Since Lamb waves have complex multi-mode characteristics, a suitable excitation frequency needs to be selected according to geometric dimensions of the structure to be measured, and then, only low-order mode Lamb waves are excited inside the measured structure to avoid serious waveform aliasing. For isotropic measured objects, anisotropic characteristics will be generated under the action of pre-stresses, that is, the propagation velocities of ultrasonic waves in all directions are different, but there is a linear relationship between velocity changes in different propagation directions and stresses. Therefore, there is still a linear relationship between the difference of velocity changes in different propagation directions and the stress. According to this characteristic, a characterization method of an absolute stress field without baseline data can be implemented. The method of the disclosure can make full use of the low attenuation characteristics of the Lamb waves to realize online monitoring of the plane stress field with a large coverage area.

Method, system, device and medium for online monitoring of plane stress field without baseline data based on piezoelectric transducer array

A method, system, device, and medium for online stress monitoring without baseline data based on single-mode multi-frequency signal fusion are provided. The method includes: establishing a dispersion curve according to geometric dimensions and material parameters of a measured object; then solving an approximate linear relationship between propagation time of S0 modes with different frequencies and stress at a fixed propagation distance by using a relationship between stress and group velocity, the obtained linear relationship being an acousto-elastic equation required for final measurement; then performing Hilbert transformation on an obtained signal, extracting a signal envelope, and determining arrival time of two excitation frequency signals by means of a peak extraction algorithm and a time domain width of an excitation signal; and calculating a propagation time ratio and substituting the propagation time ratio into a pre-calibrated acousto-elastic equation to solve a stress value of an object to be measured. The disclosure is advantageous in that the multi-frequency data is fused by using dispersion characteristics of a single-mode Lamb wave and an acousto-elastic effect, thereby achieving online stress monitoring without baseline data.

Method, system, device, and medium for online stress monitoring without baseline data based on single-mode multi-frequency signal fusion

The present disclosure proposes a non-baseline on-line stress monitoring system and monitoring method based on multi-mode Lamb wave data fusion. A Lamb wave dispersion curve is established according to geometric dimensions and material parameters of a measured object, a cut-off frequency of a first-order Lamb wave mode is obtained, an excitation frequency of a Lamb wave signal is determined, and then pure Lamb waves in S0 and A0 modes obtained inside the measured object are obtained; an acoustoelastic equation is established, an elastodynamic equation of the measured object under a prestress condition is solved, and linear relationships between a group velocity and a stress of the Lamb waves in the S0 and A0 modes under the excitation frequency are obtained; data is processed through the on-line monitoring system; a stress gradient in a depth direction is calculated, and finally, a stress state of the measured object is represented. The present disclosure does not require data under a zero stress state as baseline data, does not require designing a wedge block capable of generating a critical refraction longitudinal wave, and combines acoustoelastic effects of Lamb waves in different modes to realize online stress monitoring without the baseline data.

Non-baseline on-line stress monitoring system and monitoring method based on multi-mode lamb wave data fusion

The disclosure discloses a stress gradient high-efficiency non-destructive detection system based on frequency domain calculation of broadband swept frequency signals, and a detection method thereof. The detection method includes: step 1: calibrating an LCR wave velocity of an object to be measured; step 2: calculating a starting frequency and a cut-off frequency of broadband swept frequency signals based on the LCR wave velocity of the object to be measured in the step 1 and a stress gradient measuring range in a depth direction of the object to be measured; step 3: converting phase delay to time delay information based on the phase delay of the starting frequency and the cut-off frequency in the step 2; and step 4: determining stresses of depths corresponding to different frequency components based on the time delay information in the step 3 to finally realize layer-by-layer scanning of stresses at different depths of the measured object. The disclosure is used to solve the problem of low stress gradient measuring accuracy, and realize the high-efficiency characterization of the stress gradient in the depth direction.

Stress gradient high-efficiency non-destructive detection system based on frequency domain calculation of broadband swept frequency signals, and detection method thereof

Disclosed are a linkage device, a transceiver module and a plane stress field measuring device and method capable of achieving synchronous adjustment of distance and angle, and relates to the field of ultrasonic non-destructive testing. The existing technical means for measuring plane stress in the field of ultrasonic testing has the shortcomings that the same testing is only applicable for single materials and the deflection angles of transmitting and receiving transducers are inconsistent. In the application, the linkage device designed by comprising a distance adjusting screw, an angle adjusting screw, a left connecting rod, a right connecting rod, a shaft column and a column lock is adopted, and based on the linkage device, the transceiver module designed by comprising a receiving end wedge, a receiving probe, a transmitting end wedge and a transmitting probe is additionally arranged; based on the transceiver module, the measuring device designed by comprising a pulse transmitting device, an amplifying device and a data acquisition device is additionally arranged, and the stress measuring method applicable for the stress measuring device is provided; and the distance and deflection angle between the receiving probe and the transmitting probe of the detection are adjusted according to a tested part. The application applies to stress measurement in the manufacturing process of mechanical components.

Linkage device, transceiver module and plane stress field measuring device and method capable of achieving synchronous adjustment of distance and angle

The disclosure provides a linearization identification method for a hysteresis model of piezoceramics based on Koopman operators, and belongs to the field of precision positioning. In order to solve the problem of hysteresis of a piezoelectric actuator in practical application, the disclosure further provides the linearization identification method for the hysteresis model of the piezoceramics based on Koopman operators. The method of the disclosure includes: Step I, building a structure of the hysteresis model of the piezoceramics; Step II, determining parameters of the hysteresis model of the piezoceramics; Step III, obtaining a great amount of simulation data by using simulation software; Step IV, performing deep learning training based on Koopman operators; and Step V, determining a linearization model for the hysteresis model of the piezoceramics based on Koopman operators. The disclosure is applicable to piezoelectric actuator control and precision positioning.

Linearization identification method for hysteresis model of piezoceramics based on Koopman operators

The disclosure relates to a control method of a probe with ultrasonic phased array transducers in a hinge array, and belongs to the technical field of ultrasonic detecting. The control method includes the steps: firstly, fixing a part under test, making a central piezoelectric array element of piezoelectric array elements for the ultrasonic phased array transducers in the hinge array make contact with a surface of the part under test, and then fixing a fixed support; before detection is started, driving the hinge array through voice coil motors to make the piezoelectric array elements completely fit the surface of the part under test, wherein the number of the piezoelectric array elements is 2N+1 (N=1, 2, 3, 4 and 5), and different values of N are selected according to a size of the part under test; with the value of pressure of the central piezoelectric array element as a standard and difference values between values of pressures of other piezoelectric array elements and the value of pressure of the central piezoelectric array element as control signals of respective corresponding voice coil motor coils, controlling output rods to drive the hinge array; keeping the values of pressures of all the piezoelectric array elements consistent by means of an incremental digital PID control method; and then realizing deflecting and focusing of ultrasonic waves by means of a time delay rule for ultrasonic detecting, thereby detecting parts under test with planar or curved surfaces.

Control method of probe with ultrasonic phased array transducers in hinge array

An ultrasonic phased array transducer device with a two-dimensional hinge array structure belongs to equipment in the technical field of ultrasonic detection. A connecting rod is fixedly connected to a fixed support and a two-dimensional hinge array respectively. Voice coil motors are symmetrically arranged in a shape of the British 'Union Jack' with the connecting rod as a center, and are fixedly connected to the fixed support. Force output rods are respectively connected to voice coil motor coils and the upper surfaces of array units. Piezoelectric array elements are fixedly connected to the lower surfaces of all the array units. The numbers of the voice coil motors and the force output rods are 2N (N=4, 8, 12, 16, 20), the number of the piezoelectric array elements is 2N+1, and different N values are selected according to the sizes of workpieces to be detected. In the disclosure, by adjusting the current of each voice coil motor coil, the corresponding force output rod generates displacement to drive the two-dimensional hinge array unit to generate displacement, so as to push out and retract the hinge array unit and the piezoelectric array element fixedly connected below and drive the two-dimensional hinge array to generate deformation, so that the piezoelectric array elements fully fit with the surface of the workpiece to be detected. The disclosure can be applied to detection of the workpieces to be detected with flat surfaces, curved surfaces or spherical surfaces.

Ultrasonic phased array transducer device with two-dimensional hinge array structure

A zero-voltage zero-current soft switching type driving method for an ultrasonic motor is provided, relating to the technical field of driving of a two-phase actuator. The disclosure solves the problems of high loss, high heat amount and the like in a traditional ultrasonic motor driving circuit. The method provided realizes resonance between series inductors and buffer capacitors by means of an optimal design of the inductance of matching inductors, the capacitance of buffer capacitors, a dead time value and a delay time value, thereby causing a power tube to realize zero-voltage and zero-current switching. Two signal input ends of a two-phase pseudo full bridge inverter are connected to a power grid, and two signal output ends of the two-phase pseudo full bridge inverter are respectively connected to two signal input ends of a matching circuit; and the output ends of the matching circuit are respectively connected to a two-phase ultrasonic motor.

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Harbin, China

Weijia Shi