Integrated dual-frequency ultrasonic transducer, working method and application

Abstract

The present invention discloses an integrated dual-frequency ultrasonic transducer, a working method and an application. In the integrated dual-frequency ultrasonic transducer, a high-frequency piezoelectric layer emits high-frequency ultrasonic waves and receives ultrasonic fundamental frequency components reflected back by a sample to be tested, wherein the ultrasonic fundamental frequency components are high-frequency ultrasonic signals with the same frequency as the high-frequency ultrasonic waves. An intermediate layer is stacked on the upper surface of the high-frequency piezoelectric layer, a low-frequency piezoelectric layer is stacked on the upper surface of the intermediate layer, and the low-frequency piezoelectric layer receives ultrasonic static components reflected back by the sample to be tested, wherein the ultrasonic static components are signals induced by the high-frequency ultrasonic waves and whose carrier frequency is 0.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic nondestructive testing, and in particular to an integrated dual-frequency ultrasonic transducer, a working method and an application thereof. Background Art

[0002] The ultrasonic static component is induced by nonlinear sources such as materials and microcracks during the propagation of ultrasonic waves in the sample. Its carrier frequency is 0. Compared with traditional fundamental frequency components and high-order harmonic components, it has the characteristics of longer propagation distance and smaller sound attenuation.

[0003] In traditional nondestructive testing, the ultrasonic static component is measured by the penetration method, which often makes it difficult to keep the transmitting and receiving transducers on the same axis, or the measurement results are easily affected by the coupling agent, which may cause large errors in the measurement results. For the existing integrated dual-frequency ultrasonic transducer, the low-frequency piezoelectric layer is used as the transmitting source, and the high-frequency piezoelectric layer is used as the receiver for harmonic imaging, etc. The existing technology cannot achieve self-transmitting and self-receiving measurement and the error is large.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes an integrated dual-frequency ultrasonic transducer, a working method and an application, which can realize the measurement of ultrasonic fundamental frequency components and static components in a self-generated and self-received manner with high strategic accuracy.

[0006] The object of the present invention is achieved through the following technical solutions: an integrated dual-frequency ultrasonic transducer comprises:

[0007] A high-frequency piezoelectric layer, which emits high-frequency ultrasonic waves and receives ultrasonic fundamental frequency components reflected back by the sample to be tested, wherein the ultrasonic fundamental frequency components are high-frequency ultrasonic signals having the same frequency as the high-frequency ultrasonic waves;

[0008] An intermediate layer, which is stacked on the upper surface of the high-frequency piezoelectric layer;

[0009] A low-frequency piezoelectric layer is stacked on the upper surface of the intermediate layer, and the low-frequency piezoelectric layer receives the ultrasonic static component reflected back by the sample to be measured, wherein the ultrasonic static component is a signal induced by the high-frequency ultrasonic wave and having a carrier frequency of 0.

[0010] In the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer and the low-frequency piezoelectric layer are both thickness-expandable piezoelectric layers in which the electric field is parallel to the wave propagation direction.

[0011] In the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer and the low-frequency piezoelectric layer have the same length and width, and the thickness of the high-frequency piezoelectric layer and the low-frequency piezoelectric layer is half the wavelength of their respective corresponding frequencies.

[0012] In the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer and the low-frequency piezoelectric layer have the same length and width, and both the length and width are more than 5 times the thickness of the high-frequency piezoelectric layer.

[0013] In the integrated dual-frequency ultrasonic transducer, the material of the high-frequency piezoelectric layer and the low-frequency piezoelectric layer includes piezoelectric ceramics.

[0014] In the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer is a high-frequency longitudinal wave piezoelectric chip, and the low-frequency piezoelectric layer is a low-frequency longitudinal wave piezoelectric chip.

[0015] In the integrated dual-frequency ultrasonic transducer, a backing layer is stacked on the upper surface of the low-frequency piezoelectric layer.

[0016] In the integrated dual-frequency ultrasonic transducer, the integrated dual-frequency ultrasonic transducer includes a signal generator that sends a high-frequency transmission signal to the high-frequency piezoelectric layer.

[0017] The working method of the integrated dual-frequency ultrasonic transducer comprises the following steps:

[0018] The signal generator generates a single high-frequency transmission signal;

[0019] The transmitting signal excites the high-frequency piezoelectric layer to generate high-frequency ultrasonic waves;

[0020] The high-frequency ultrasonic wave generates a static component when propagating in the sample. After being reflected by the sample, the high-frequency piezoelectric layer receives the ultrasonic base frequency component through the duplexer, and the low-frequency piezoelectric layer receives the ultrasonic static component and converts it into an electrical signal.

[0021] The working method is applied to realize self-generated and self-received nonlinear ultrasonic detection and thickness measurement.

[0022] Compared with the prior art, the present invention has the following advantages: the present invention can realize the measurement of ultrasonic fundamental frequency component and static component in a self-generated and self-received manner, and can ensure a smaller error. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0024] In the attached picture:

[0025] Figure 1 is a schematic diagram of a dual-frequency ultrasonic transducer of the present invention;

[0026] Explanation of symbols: 1-high frequency piezoelectric layer, 2-intermediate layer, 3-low frequency piezoelectric layer, 4-backing layer;

[0027] Figure 2 Schematic diagram of echo signals of fundamental frequency components and static components in a measurement material (PPS is used in this embodiment, and its ultrasonic fundamental frequency component is not completely attenuated) according to an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of echo signals of fundamental frequency components and static components in a measurement material (silicone rubber is used in this embodiment, and its ultrasonic fundamental frequency component has been completely attenuated) of an embodiment of the present invention;

[0029] Figure 4 is the time domain waveform of the transmitted signal;

[0030] Figure 5 is the spectrum of the transmitted signal;

[0031] Figure 6 It is the received fundamental frequency component and static component time domain waveform (PPS thickness is 50mm);

[0032] Figure 7 It is the received fundamental frequency component and static component spectrum (PPS thickness is 50mm);

[0033] Figure 8 is the time domain waveform of the received fundamental frequency component (the thickness of the silicone rubber is 30.15 mm);

[0034] Fig. 9 is the received static component time domain waveform (silicone rubber thickness is 30.15mm);

[0035] Fig.10 is the received static component spectrum (silicone rubber thickness is 30.15mm).

[0036] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0037] The following will refer to the attached Figures 1 to 10 Specific embodiments of the present invention are described in more detail. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0038] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0039] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0040] For a better understanding, Figures 1 to 10 As shown, in an integrated dual-frequency ultrasonic transducer,

[0041] The high-frequency piezoelectric layer 1 emits high-frequency ultrasonic waves and receives ultrasonic fundamental frequency components reflected back by the sample to be tested. The ultrasonic fundamental frequency components are high-frequency ultrasonic signals with the same frequency as the high-frequency ultrasonic waves.

[0042] The intermediate layer 2 is stacked on the upper surface of the high-frequency piezoelectric layer 1.

[0043] The low-frequency piezoelectric layer 3 is stacked on the upper surface of the intermediate layer 2. The low-frequency piezoelectric layer 3 receives the ultrasonic static component reflected back by the sample to be tested. The ultrasonic static component is a signal induced by the high-frequency ultrasonic wave and having a carrier frequency of 0.

[0044] In a preferred embodiment of the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 are both thickness-expandable piezoelectric layers in which the electric field is parallel to the wave propagation direction.

[0045] In a preferred embodiment of the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 have the same length and width, and the thickness of the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 is half the wavelength of their respective corresponding frequencies.

[0046] In a preferred embodiment of the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 have the same length and width, and both the length and width are more than 5 times the thickness of the high-frequency piezoelectric layer 1 .

[0047] In a preferred embodiment of the integrated dual-frequency ultrasonic transducer, the material of the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 includes piezoelectric ceramics.

[0048] In a preferred embodiment of the integrated dual-frequency ultrasonic transducer, the high-frequency piezoelectric layer 1 is a high-frequency longitudinal wave piezoelectric chip, and the low-frequency piezoelectric layer 3 is a low-frequency longitudinal wave piezoelectric chip.

[0049] In a preferred embodiment of the integrated dual-frequency ultrasonic transducer, a backing layer 4 is stacked on the upper surface of the low-frequency piezoelectric layer 3 .

[0050] In a preferred embodiment of the integrated dual-frequency ultrasonic transducer, the integrated dual-frequency ultrasonic transducer includes a signal generator that sends a high-frequency transmission signal to the high-frequency piezoelectric layer 1 .

[0051] In one embodiment, an integrated dual-frequency ultrasonic transducer includes: a high-frequency piezoelectric layer 1, an intermediate layer 2, a low-frequency piezoelectric layer 3, and a backing layer 4. The high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 have the same lateral dimensions, and the thickness is half the wavelength of the corresponding frequency. The high-frequency piezoelectric layer 1 is in contact with the sample through a liquid coupling agent.

[0052] In one embodiment, the integrated dual-frequency ultrasonic transducer is provided with a high-frequency piezoelectric layer 1, an intermediate layer 2, a low-frequency piezoelectric layer 3, and a backing layer 4 in sequence from bottom to top, which realizes the measurement of the ultrasonic fundamental frequency component and the static component in a self-generated and self-received manner.

[0053] In one embodiment, the high-frequency piezoelectric layer 1 is used to transmit high-frequency ultrasonic waves and receive ultrasonic fundamental frequency components reflected back by the sample; the low-frequency piezoelectric layer 3 is used to receive ultrasonic static components induced by nonlinearities such as the sample's material and microcracks and reflected back.

[0054] In one embodiment, the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 are both thickness-expanding piezoelectric layers in which the electric field is parallel to the wave propagation direction, and the two piezoelectric layers operate at different center frequencies. The materials of the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 include but are not limited to piezoelectric ceramics, piezoelectric composite materials, etc.

[0055] In one embodiment, the high-frequency piezoelectric layer 1 is a high-frequency longitudinal wave piezoelectric chip, and the low-frequency piezoelectric layer 3 is a low-frequency longitudinal wave piezoelectric chip. The lateral dimensions of the high-frequency piezoelectric layer 1 and the low-frequency piezoelectric layer 3 are consistent in length and width and are greater than 5 times the thickness, and the thickness is half the wavelength of the corresponding frequency.

[0056] In one embodiment, the thickness of the intermediate layer 2 is equal to or less than a quarter wavelength corresponding to the high-frequency ultrasonic frequency, and the material is generally epoxy resin, AB glue or similar materials.

[0057] In one embodiment, the fundamental frequency component is a high-frequency ultrasonic signal having the same frequency as the excitation signal, and the static component is a signal induced by the excited high-frequency ultrasonic signal and having a carrier frequency of 0.

[0058] Reference Figure 1 The integrated dual-frequency ultrasonic transducer includes a high-frequency piezoelectric layer 1, an intermediate layer 2, a low-frequency piezoelectric layer 3, and a backing layer 4; wherein the high-frequency piezoelectric layer 1 is a PZT piezoelectric ceramic rectangular sheet with a length of 26 mm, a width of 20 mm, a thickness of 0.4 mm and a center frequency of 5 MHz, the intermediate layer is an external clamped ultrasonic sensor coupling agent, and the low-frequency piezoelectric layer 3 and the backing layer 4 as a whole adopt a broadband piezoelectric transducer with a size of 0.5″×1.0″ and a center frequency of 0.5 MHz. During the measurement process, the high-frequency piezoelectric layer 1 is in contact with the sample through a liquid coupling agent.

[0059] Based on the integrated dual-frequency ultrasonic transducer of the above embodiment, Figure 2 and Figure 3 As shown in the figure, the computer controls the RAM-5000SNAP system to stimulate a sine pulse signal with a center frequency of 5MHz and a frequency of 15, which is modulated by a Hanning window. Figure 4 As shown, its spectrum is as follows Figure 5 As shown, the excitation signal is loaded into the high-frequency piezoelectric chip through a 2.25MHz high-pass filter to generate ultrasonic longitudinal waves. During the propagation of the sample, the nonlinearity of the material induces the generation of ultrasonic static components. After reflection from the bottom surface, the high-frequency piezoelectric chip is connected to the duplexer to receive the baseband echo signal, and the low-frequency piezoelectric transducer receives the static component echo signal. For materials where the baseband component echo signal is not completely attenuated, the static component echo signal needs to pass through a 1MHz low-pass filter; while for materials where the baseband component echo signal is completely attenuated, the static component echo signal does not need to be converted into an electrical signal by a low-pass filter and is received by the RAM-5000SNAP system and displayed by the oscilloscope.

[0060] Based on the above embodiment, a PPS with a thickness of 50 mm and a silicone rubber with a thickness of 30.15 mm are used for measurement. The time domain and spectrum diagrams of the ultrasonic fundamental frequency component and static component echo receiving signal of the 50 mm thick PPS are as follows: Figure 6 and Figure 7As shown in FIG. 1 , the ultrasonic static component echo signal and the fundamental frequency component echo signal can be used to realize the self-transmitting and self-receiving nonlinear ultrasonic detection and thickness measurement of materials; for a silicone rubber with a thickness of 30.15 mm, the received ultrasonic fundamental frequency component echo time domain signal is as follows: Figure 8 As shown in the figure, it can be seen that the ultrasonic fundamental frequency component has been completely attenuated, and the static component echo receiving time domain signal and spectrum are shown in Fig. 9 and Fig.10 As shown, it can be seen that the static component is not completely attenuated. Because the pulse carrier frequency of the static component is 0, the attenuation is small, and the propagation distance is farther than the fundamental frequency component. The product of the flight time and wave velocity of the two echoes of the ultrasonic static component can be used to realize the self-generated and self-received material thickness measurement.

[0061] Based on the above-mentioned integrated dual-frequency ultrasonic transducer, the present invention also provides a self-generated and self-received measurement method of ultrasonic fundamental frequency component and static component, the method comprising:

[0062] The signal generator generates a single high frequency transmission signal;

[0063] The transmitting signal excites the high-frequency piezoelectric layer 1 of the dual-frequency ultrasonic transducer to generate a high-frequency ultrasonic signal;

[0064] When the high-frequency ultrasonic signal propagates in the sample, it is accompanied by a static component generated by nonlinear sources such as materials and microcracks. After being reflected by the bottom surface, the high-frequency piezoelectric layer 1 of the dual-frequency ultrasonic transducer receives the baseband echo signal through the duplexer, and the low-frequency piezoelectric layer 3 receives the static component echo signal, and the echo signal is converted into an electrical signal.

[0065] In one embodiment, the working method of the integrated dual-frequency ultrasonic transducer comprises the following steps:

[0066] The signal generator generates a single high-frequency transmission signal;

[0067] The transmitting signal excites the high-frequency piezoelectric layer 1 to generate high-frequency ultrasonic waves;

[0068] The high-frequency ultrasonic wave generates a static component when propagating in the sample. After being reflected by the sample, the high-frequency piezoelectric layer 1 receives the ultrasonic fundamental frequency component through the duplexer, and the low-frequency piezoelectric layer 3 receives the ultrasonic static component and converts it into an electrical signal.

[0069] According to the application of the working method, the working method is utilized to realize self-generating and self-receiving nonlinear ultrasonic detection and thickness measurement.

[0070] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. An integrated dual-frequency ultrasonic transducer, characterized in that: These include, A high-frequency piezoelectric layer, which emits high-frequency ultrasonic waves and receives ultrasonic fundamental frequency components reflected back by the sample to be tested, wherein the ultrasonic fundamental frequency components are high-frequency ultrasonic signals having the same frequency as the high-frequency ultrasonic waves; An intermediate layer, which is stacked on the upper surface of the high-frequency piezoelectric layer; A low-frequency piezoelectric layer is stacked on the upper surface of the intermediate layer, the low-frequency piezoelectric layer receives the ultrasonic static component reflected back by the sample to be measured, the ultrasonic static component is a signal induced by the high-frequency ultrasonic wave and having a carrier frequency of 0, the high-frequency piezoelectric layer and the low-frequency piezoelectric layer are both thickness-expanding piezoelectric layers in which the electric field is parallel to the wave propagation direction, the high-frequency piezoelectric layer and the low-frequency piezoelectric layer operate at different center frequencies, the materials of the high-frequency piezoelectric layer and the low-frequency piezoelectric layer include piezoelectric ceramics or piezoelectric composite materials, the high-frequency piezoelectric layer is in contact with the sample through a liquid coupling agent, the high-frequency piezoelectric layer and the low-frequency piezoelectric layer have the same length and width, the thickness of the high-frequency piezoelectric layer and the low-frequency piezoelectric layer is half the wavelength of the corresponding frequency, the high-frequency piezoelectric layer and the low-frequency piezoelectric layer have the same length and width, the length and width are both more than 5 times the thickness of the high-frequency piezoelectric layer, the thickness of the intermediate layer is equal to or less than a quarter wavelength of the corresponding high-frequency ultrasonic frequency, and the self-generated and self-collected material thickness measurement is achieved by utilizing the product of the flight time and wave velocity of two echoes of the ultrasonic static component.

2. The integrated dual-frequency ultrasonic transducer according to claim 1, wherein: The materials of the high-frequency piezoelectric layer and the low-frequency piezoelectric layer include piezoelectric ceramics.

3. The integrated dual-frequency ultrasonic transducer according to claim 1, wherein: The high-frequency piezoelectric layer is a high-frequency longitudinal wave piezoelectric chip, and the low-frequency piezoelectric layer is a low-frequency longitudinal wave piezoelectric chip.

4. The integrated dual-frequency ultrasonic transducer according to claim 1, wherein: A backing layer is stacked on the upper surface of the low-frequency piezoelectric layer.

5. The integrated dual-frequency ultrasonic transducer according to claim 1, wherein: The integrated dual-frequency ultrasonic transducer includes a signal generator that sends a high-frequency transmission signal toward the high-frequency piezoelectric layer.

6. The working method of the integrated dual-frequency ultrasonic transducer according to any one of claims 1 to 5, characterized in that: It includes the following steps, The signal generator generates a single high-frequency transmission signal; The transmitting signal excites the high-frequency piezoelectric layer to generate high-frequency ultrasonic waves; The high-frequency ultrasonic wave generates a static component when propagating in the sample. After being reflected by the sample, the high-frequency piezoelectric layer receives the ultrasonic base frequency component through the duplexer, and the low-frequency piezoelectric layer receives the ultrasonic static component and converts it into an electrical signal.

7. An application of the working method according to claim 6, characterized in that: The working method is used to realize self-generated and self-received nonlinear ultrasonic detection and thickness measurement.

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