Pilot-frequency transmitting-receiving type ultrasonic array transducer and working method thereof

Abstract

The invention discloses a pilot frequency transmitting-receiving type ultrasonic array transducer and a working method thereof, and belongs to the technical field of ultrasonic nondestructive testing. Comprising a high-frequency transmitting unit and a plurality of low-frequency receiving units surrounding the high-frequency transmitting unit, the high-frequency transmitting unit transmits high-frequency ultrasonic waves consistent with the center frequency of the high-frequency transmitting unit, and the low-frequency receiving units receive quasi-static components formed by the non-linear effect of the high-frequency ultrasonic waves in a to-be-tested material and convert the quasi-static components into electric signals. Core elements are high-frequency and low-frequency piezoelectric elements and work in a thickness stretching vibration mode, the thickness is the half wavelength of the corresponding frequency, the diameter meets the specific requirement, piezoelectric ceramics and the like can be selected as materials, and wedge-shaped backing layers are stacked on the upper surfaces of the core elements. And the high-frequency transmitting unit and the four low-frequency receiving units form a cross array. The working method comprises the steps of applying electric signals to the high-frequency transmitting unit to excite high-frequency ultrasonic waves, and receiving quasi-static component signals by the low-frequency receiving unit. The non-linear ultrasonic non-destructive testing device is used for non-linear ultrasonic non-destructive testing of high-attenuation materials and has the advantages in the aspects of thickness detection, resolution ratio detection and signal-to-noise ratio detection.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic nondestructive testing, and particularly to a heterodyne transceiver ultrasonic array transducer and its working method. Background Art

[0002] In the field of ultrasonic nondestructive testing, high attenuation materials pose many challenges to the testing work due to their strong absorption and scattering effects on ultrasonic waves. High-frequency ultrasonic waves are difficult to penetrate a certain thickness of high attenuation materials, resulting in insufficient signal penetration depth; while low-frequency ultrasonic waves have certain advantages in penetration, but their pulse widths are difficult to control and cannot meet the detection resolution requirements. Traditional single-frequency transceiver transducers perform poorly in terms of detection thickness, resolution, and signal-to-noise ratio when detecting high attenuation materials due to the above problems. To solve these problems, a heterodyne transceiver ultrasonic array transducer has emerged. Through the heterodyne design of high-frequency transmission and low-frequency reception, combined with the array structure, it effectively makes up for the deficiencies of traditional technologies and provides a new solution for ultrasonic nondestructive testing of high attenuation materials. Summary of the Invention

[0003] The purpose of the present invention is to provide a heterodyne transceiver ultrasonic array transducer and its working method, which can realize ultrasonic measurement of high attenuation materials in a heterodyne transceiver mode, with a large detection range, high detection resolution, and high signal-to-noise ratio.

[0004] To achieve the above purpose, the present invention provides a heterodyne transceiver ultrasonic array transducer, including:

[0005] A high-frequency transmitting unit configured to emit high-frequency ultrasonic waves to the material to be measured, and the frequency of the high-frequency ultrasonic waves is consistent with the center frequency of the high-frequency transmitting unit;

[0006] A plurality of low-frequency receiving units arranged around the high-frequency transmitting unit, configured to receive the quasi-static component generated after the high-frequency ultrasonic waves propagate and reflect in the material to be measured, and the quasi-static component is a low-frequency signal formed by the non-linear action of the high-frequency ultrasonic waves in the material to be measured;

[0007] Moreover, the core components of the high-frequency transmitting unit and the low-frequency receiving units are high-frequency piezoelectric elements and low-frequency piezoelectric elements respectively, and electrodes are installed on both the upper and lower sides of the high-frequency piezoelectric elements and the low-frequency piezoelectric elements.

[0008] Preferably, the electric field directions of the high-frequency piezoelectric element and the low-frequency piezoelectric element are parallel to the ultrasonic wave propagation direction, and they operate in the thickness expansion and contraction vibration mode.

[0009] Preferably, the thicknesses of the high-frequency piezoelectric element and the low-frequency piezoelectric element are each half of the wavelength corresponding to their respective operating frequencies.

[0010] Preferably, the diameter of the high-frequency piezoelectric element is less than 10 times its thickness, and the diameter of the low-frequency piezoelectric element is less than its thickness.

[0011] Preferably, the materials of the high-frequency piezoelectric element and the low-frequency piezoelectric element include piezoelectric ceramics and piezoelectric composite materials, but are not limited to the two.

[0012] Preferably, the high-frequency piezoelectric element is a high-frequency longitudinal wave piezoelectric ceramic column, and the low-frequency piezoelectric element is a low-frequency longitudinal wave piezoelectric ceramic column.

[0013] Preferably, a backing layer is laminated on the upper surfaces of the high-frequency piezoelectric element and the low-frequency piezoelectric element, and the backing layers are both wedge-shaped.

[0014] Preferably, one high-frequency transmitting unit and four low-frequency receiving units form an ultrasonic transceiver array, and the ultrasonic transceiver array is a cross array.

[0015] Preferably, the operating frequency range of the low-frequency receiving unit is 1 / 10 to 1 / 20 of the center frequency of the high-frequency transmitting unit.

[0016] The present invention also provides a working method for an ultrasonic array transducer with different frequency transmitting and receiving, including the following steps:

[0017] S1. Apply a single-frequency electrical signal to the high-frequency transmitting unit to excite high-frequency ultrasonic waves;

[0018] S2. Receive the quasi-static component signal generated by the high-frequency ultrasonic waves in the material to be measured through the low-frequency receiving unit, and convert it into an electrical signal for output.

[0019] The application of the working method provided by the present invention is used for non-destructive testing of nonlinear ultrasonic waves of high-attenuation materials. By analyzing the time-domain and frequency-domain characteristics of the quasi-static components, quantitative evaluation of the material thickness, defects, and nonlinear parameters can be achieved.

[0020] Therefore, the present invention adopts an ultrasonic array transducer with different frequency transmitting and receiving having the above structure and its working method, and has the following beneficial effects:

[0021] (1) Compared with the traditional single-frequency transmitting and receiving transducer, the present invention shows advantages in the detection thickness, detection resolution, and signal-to-noise ratio of high-attenuation materials, and can realize ultrasonic detection of large-thickness high-attenuation materials.

[0022] (2) The present invention uses the signal superposition technology of pulse inversion to suppress the direct interference wave, further improves the signal-to-noise ratio of the quasi-static component echo signal, and improves the detection range and resolution.

[0023] (3) In the present invention, the receiving array with a cross array structure enhances the ability to receive weak quasi-static components; the design of the backing layer optimizes the acoustic wave emission and reception performance of the transducer; the material selection and size design of the high-frequency and low-frequency piezoelectric elements (the thickness is half of the wavelength corresponding to the frequency and the diameter meets the requirements) ensure the efficient operation of the transducer.

[0024] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of an ultrasonic array transducer with different-frequency transmitting and receiving and its working method according to the present invention;

[0026] Figure 2 It is a schematic structural diagram of an ultrasonic transmitting and receiving array of an ultrasonic array transducer with different-frequency transmitting and receiving and its working method according to the present invention;

[0027] Figure 3 It is a schematic diagram of an excitation signal of an ultrasonic array transducer with different-frequency transmitting and receiving and its working method according to the present invention;

[0028] Figure 4 It is a time-domain comparison diagram of the received echo signals of the quasi-static components of a 100-mm silicone rubber different-frequency transmitting and receiving dual-element transducer and an ultrasonic array transducer with different-frequency transmitting and receiving according to the present invention; (a) is the time-domain diagram of the received signal of the different-frequency transmitting and receiving dual-element transducer, and (b) is the time-domain diagram of the received signal of the ultrasonic array transducer with different-frequency transmitting and receiving;

[0029] Figure 5 It is a frequency-domain comparison diagram of the received echo signals of the quasi-static components of a 100-mm silicone rubber different-frequency transmitting and receiving dual-element transducer and an ultrasonic array transducer with different-frequency transmitting and receiving according to the present invention; (a) is the frequency-domain diagram of the received signal of the different-frequency transmitting and receiving dual-element transducer, and (b) is the frequency-domain diagram of the received signal of the ultrasonic array transducer with different-frequency transmitting and receiving;

[0030] Figure 6 It is a time-domain diagram of the received echo signal of the quasi-static component of a 100-mm silicone rubber ultrasonic array transducer with different-frequency transmitting and receiving after being processed by the signal superposition technology of pulse inversion according to the present invention;

[0031] Figure 7 It is a frequency-domain diagram of the received echo signal of the quasi-static component of a 100-mm silicone rubber ultrasonic array transducer with different-frequency transmitting and receiving after being processed by the signal superposition technology of pulse inversion according to the present invention;

[0032] Figure 8Schematic diagram of the high-frequency transmitting unit and the low-frequency receiving unit of a heterodyne transceiver ultrasonic array transducer and its working method according to the present invention;

[0033] Reference numerals

[0034] 1. High-frequency transmitting unit, 2. Low-frequency receiving unit, 3. Outer shell package, 4. High-frequency piezoelectric element, 5. Electrode, 6. Low-frequency piezoelectric element, 7. Backing layer. Detailed implementation manner

[0035] The technical solution of the present invention will be further described below with reference to the drawings and embodiments.

[0036] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those of ordinary skill in the field to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right" are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0037] Embodiment

[0038] As Figure 1-8 shown, the present invention provides a heterodyne transceiver ultrasonic array transducer, including:

[0039] A high-frequency transmitting unit 1 that emits high-frequency ultrasonic waves into the material to be measured, and the frequency of the high-frequency ultrasonic waves is consistent with the center frequency of the high-frequency transmitting unit.

[0040] A low-frequency receiving unit 2 that is arranged around the high-frequency transmitting unit. The low-frequency receiving unit receives the quasi-static component reflected from the bottom surface of the sample to be measured. The quasi-static component is the component that can be detected by the low-frequency receiving unit generated by the propagation of high-frequency ultrasonic waves in the sample to be measured.

[0041] The core components of both the high-frequency transmitting unit 1 and the low-frequency receiving unit 2 are cylindrical piezoelectric elements with thickness expansion and contraction in which the electric field is parallel to the wave propagation direction.

[0042] The thicknesses of the high-frequency piezoelectric element 4 and the low-frequency piezoelectric element 6 are each half of the wavelength corresponding to their respective frequencies.

[0043] The diameter of the high-frequency piezoelectric element 4 is less than 10 times the thickness of the high-frequency piezoelectric element 4, and the diameter of the low-frequency piezoelectric element 6 is less than the thickness of the low-frequency piezoelectric element 6.

[0044] The materials of the high-frequency piezoelectric element 4 and the low-frequency piezoelectric element 6 include piezoelectric ceramics and piezoelectric composite materials, but are not limited to the two.

[0045] The high-frequency piezoelectric element 4 is a high-frequency longitudinal wave piezoelectric ceramic column, and the low-frequency piezoelectric element 6 is a low-frequency longitudinal wave piezoelectric ceramic column.

[0046] The upper surfaces of the high-frequency piezoelectric element 4 and the low-frequency piezoelectric element 6 are both laminated with a backing layer 7, and the backing layers 7 are both wedge-shaped.

[0047] An ultrasonic transceiver array is composed of one high-frequency transmitting unit 1 and four low-frequency receiving units 2, and the ultrasonic transceiver array is a cross array.

[0048] In one embodiment, a heterodyne transceiver ultrasonic array transducer includes: a high-frequency transmitting unit 1, a low-frequency receiving unit 2, and a housing package 3. The high-frequency transmitting unit 1 is composed of a high-frequency piezoelectric element 4, an electrode 5, and a backing layer 7. The low-frequency receiving unit 2 is composed of a low-frequency piezoelectric element 6, an electrode 5, and a backing layer 7. The high-frequency transmitting unit 1 and the low-frequency receiving unit 2 are in contact with the sample through a liquid couplant.

[0049] In one embodiment, the high-frequency transmitting unit 1 is excited by a single-frequency electrical signal to emit high-frequency ultrasonic waves. The high-frequency ultrasonic waves propagate in the sample to be measured and generate a quasi-static component, which can be detected by the low-frequency receiving unit 2.

[0050] Refer to Figure 1 、 Figure 2 、 Figure 8 , a heterodyne transceiver ultrasonic array transducer includes a high-frequency transmitting unit 1, a low-frequency receiving unit 2, and a housing package 3. The high-frequency transmitting unit 1 is composed of a high-frequency piezoelectric element 4, an electrode 5, and a backing layer 7. The low-frequency receiving unit 2 is composed of a low-frequency piezoelectric element 6, an electrode 5, and a backing layer 7; wherein the high-frequency piezoelectric element 4 is a PZT82 piezoelectric ceramic cylinder with a diameter of 20 mm, a thickness of 2 mm, and a center frequency of 1 MHz, and the low-frequency piezoelectric element 6 is a PZT5 piezoelectric ceramic cylinder with a diameter of 13.5 mm, a thickness of 15 mm, and a center frequency of 80 kHz. During the measurement, the high-frequency transmitting unit 1 and the low-frequency receiving unit 2 are in contact with the sample through a liquid couplant.

[0051] Based on the heterodyne transceiver ultrasonic array transducer of the above embodiment, the industrial control computer controls the USB-UT350 system to excite a rectangular window modulated sine wave signal with a center frequency of 1 MHz, as Figure 3As shown, the excitation signal generates ultrasonic longitudinal waves by being loaded into the high-frequency transmitting unit. During the propagation in the sample, due to material nonlinearity, a quasi-static component is generated. After being reflected by the bottom surface, it is received by the low-frequency receiving unit. Through testing, when the number of half-cycles of the transmitted signal is 14, the response of the low-frequency receiving unit is the best. In the subsequent embodiments, the transmitted signal is defaulted to have 14 half-cycles.

[0052] Based on the above embodiments, a silicone rubber with a thickness of 100 mm is used for measurement. The time-domain and frequency-spectrum diagrams of the echo receiving signals of the quasi-static components of the heterodyne transceiver (1 MHz transmitting / 80 kHz receiving) ultrasonic array transducer and the heterodyne transceiver (1 MHz transmitting / 80 kHz receiving) dual-element transducer are as Figure 4 (a), Figure 4 (b), Figure 5 (a) and Figure 5 (b) shown. The array transducer can produce a good response to the echo signal of the quasi-static component, and can realize ultrasonic detection of large-thickness and high-attenuation materials; for 100-mm-thick silicone rubber, the time-domain and frequency-spectrum diagrams of the echo of the quasi-static component of the heterodyne transceiver ultrasonic array transducer processed by the signal superposition technology of pulse inversion are as Figure 6 and Figure 7 shown. It can be seen that the signal superposition technology of pulse inversion can suppress the direct interference wave, and further improve the signal-to-noise ratio of the echo signal of the quasi-static component to improve the detection range and resolution.

[0053] Based on the above heterodyne transceiver ultrasonic array transducer, the present invention also provides a method for ultrasonic non-linear detection of quasi-static components. The method includes:

[0054] The high-frequency transmitting unit 1 is excited by a single-frequency electrical signal to transmit high-frequency ultrasonic waves;

[0055] The high-frequency ultrasonic waves propagate in the sample to be measured to generate a quasi-static component, and the quasi-static component can be detected by the low-frequency receiving unit 2.

[0056] In one embodiment, the working method of the integrated dual-frequency ultrasonic transducer includes the following steps.

[0057] A rectangular window modulated sine wave signal with a center frequency of 1 MHz and 14 half-cycles generates high-frequency ultrasonic longitudinal waves by being loaded into the high-frequency transmitting unit 1;

[0058] When the high-frequency ultrasonic longitudinal waves propagate in the sample, a quasi-static component is generated. After being reflected by the bottom surface, the ultrasonic static component is received by the low-frequency receiving unit 2 and converted into an electrical signal, which is displayed and collected on the industrial control computer control software interface.

[0059] According to the application of the working method, the working method is used to realize heterodyne transceiver non-linear ultrasonic detection.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An ultrasonic array transducer with different frequency transmitting and receiving, characterized in that: Including: A high-frequency transmitting unit configured to transmit high-frequency ultrasonic waves to a material to be measured, and the frequency of the high-frequency ultrasonic waves is consistent with the center frequency of the high-frequency transmitting unit; A plurality of low-frequency receiving units arranged around the high-frequency transmitting unit, configured to receive the quasi-static component generated after the high-frequency ultrasonic waves propagate and reflect in the material to be measured, and the quasi-static component is a low-frequency signal formed by the non-linear action of the high-frequency ultrasonic waves in the material to be measured; Moreover, the core components of the high-frequency transmitting unit and the low-frequency receiving units are a high-frequency piezoelectric element and low-frequency piezoelectric elements respectively, and electrodes are installed on both the upper and lower sides of the high-frequency piezoelectric element and the low-frequency piezoelectric elements.

2. The heterodyne transceiver type ultrasonic array transducer according to claim 1, wherein: The electric field directions of the high-frequency piezoelectric element and the low-frequency piezoelectric elements are parallel to the ultrasonic wave propagation direction, and they operate in the thickness expansion and contraction vibration mode.

3. The heterodyne transceiver type ultrasonic array transducer according to claim 1, wherein: The thicknesses of the high-frequency piezoelectric element and the low-frequency piezoelectric elements are half of the wavelengths corresponding to their respective operating frequencies.

4. The heterodyne transceiver type ultrasonic array transducer according to claim 1, characterized in that: The diameter of the high-frequency piezoelectric element is less than 10 times its thickness, and the diameter of the low-frequency piezoelectric element is less than its thickness.

5. The heterodyne transceiver type ultrasonic array transducer according to claim 1, wherein: The materials of the high-frequency piezoelectric element and the low-frequency piezoelectric elements are selected from piezoelectric ceramics, piezoelectric composites or combinations thereof.

6. The heterodyne transceiver type ultrasonic array transducer according to claim 1, characterized in that: The high-frequency piezoelectric element is a high-frequency longitudinal wave piezoelectric ceramic column, and the low-frequency piezoelectric element is a low-frequency longitudinal wave piezoelectric ceramic column.

7. The heterodyne transceiver type ultrasonic array transducer according to claim 1, wherein: Backing layers are laminated on the upper surfaces of the high-frequency piezoelectric element and the low-frequency piezoelectric elements, and the backing layers are both wedge-shaped.

8. The heterodyne transceiver type ultrasonic array transducer according to claim 1, wherein: One high-frequency transmitting unit and four low-frequency receiving units form an ultrasonic transceiver array, and the ultrasonic transceiver array is a cross array.

9. A working method of the heterodyne transceiver ultrasonic array transducer according to any one of claims 1-8, characterized in that: Including the following steps: S1. Apply a single-frequency electrical signal to the high-frequency transmitting unit to excite high-frequency ultrasonic waves; S2. Receive the quasi-static component signal generated by the high-frequency ultrasonic waves in the material to be measured through the low-frequency receiving unit, and convert it into an electrical signal for output.

10. An application of the working method according to claim 9, characterized in that, It is used for non-destructive testing of non-linear ultrasonic waves of high-attenuation materials. By analyzing the time-domain and frequency-domain characteristics of the quasi-static component, quantitative evaluation of the material thickness, defects and non-linear parameters is achieved.

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