Integrated three-frequency ultrasonic transducer oriented to body wave homodromous frequency mixing, working method and application
By designing an integrated three-frequency ultrasonic transducer, coaxial and co-directional excitation and co-side reception of the fundamental frequency signal were achieved, solving the problem of mechanical interference in the co-directional mixing of body waves, improving the mixing effect and ultrasonic energy transmission efficiency, and realizing the effective detection of local damage.
Patent Information
- Application Number
- CN202510915110.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-10-28
AI Technical Summary
In bulk wave coaxial mixing measurement, the mechanical interference of multiple transducers makes it difficult for the fundamental frequency wave to achieve coaxiality and collinearity, resulting in a weak mixing effect and difficulty in receiving the resonant difference frequency signal. This makes it difficult to achieve effective measurement, especially when it is impossible to contact the other side of the workpiece.
Design an integrated tri-frequency ultrasonic transducer comprising high-frequency, low-frequency, and mid-frequency piezoelectric layers. Through specific frequency matching and positional relationships, the fundamental frequency signal is coaxially and in the same direction to be excited. The resonant difference frequency signal propagating in the opposite direction is received through the low-frequency piezoelectric layer. Nonlinear parameters are extracted by combining phase reversal and Hanning window signal processing methods.
It achieves coaxial and co-directional excitation and co-side reception of fundamental frequency signals, improves the mixing effect, can effectively locate and detect local damage, reduces acoustic impedance differences and crosstalk between piezoelectric layers, and enhances ultrasonic energy transmission efficiency.
Smart Images
Figure CN120838673A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultrasonic nondestructive testing technology, and in particular to an integrated three-frequency ultrasonic transducer for body wave in-direction mixing, its working method, and its application. Background Technology
[0002] When a finite amplitude wave propagates within the material under test, it interacts with the nonlinear features of the structure to generate a nonlinear ultrasonic signal. By analyzing this signal, information about the nonlinear characteristics of the structure can be obtained, thereby enabling the detection of microscopic defects within the material. Commonly used nonlinear ultrasonic testing techniques mainly include the nonlinear ultrasonic second harmonic method and the nonlinear ultrasonic mixing method. Compared with the second harmonic method, the nonlinear ultrasonic mixing method has significant advantages such as spatial selection, waveform conversion, frequency selectivity, and direction controllability.
[0003] Nonlinear ultrasonic methods are classified into collinear mixing and non-collinear mixing based on whether the fundamental frequency waves are collinear. Collinear mixing is further divided into in-direction mixing and counter-direction mixing. Due to the characteristic of its resonant waves propagating in the opposite direction, in-direction mixing of volume waves can effectively measure the local nonlinear characteristics of the material under test and achieve scanning in situations where space is limited or the other side of the workpiece cannot be reached (such as pipes, pressure vessels, etc.).
[0004] The difficulty of body wave in-phase mixing lies in the mechanical interference of multiple transducers in actual measurements, which makes it difficult to achieve coaxial and collinearity of the fundamental frequency wave, resulting in a weak mixing effect and difficulty in receiving the resonant difference frequency signal. Summary of the Invention
[0005] The purpose of this invention is to provide an integrated three-frequency ultrasonic transducer, working method and application for realizing same-side excitation and same-side reception of body waves in the same direction mixing and local damage localization and detection.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] An integrated three-frequency ultrasonic transducer for body wave in-direction mixing is characterized by comprising a matching layer, a high-frequency piezoelectric layer, a low-frequency piezoelectric layer, a mid-frequency piezoelectric layer, and a backing layer. The matching layer and the backing layer are respectively disposed below and around the high-frequency piezoelectric layer, the low-frequency piezoelectric layer, and the mid-frequency piezoelectric layer. The high-frequency piezoelectric layer is nested outside the low-frequency piezoelectric layer and the mid-frequency piezoelectric layer and is used to emit high-frequency ultrasonic waves. The frequency of the high-frequency ultrasonic waves is the fundamental frequency component one of the body wave in-direction mixing. The mid-frequency piezoelectric layer is used to emit mid-frequency ultrasonic waves. The frequency of the mid-frequency ultrasonic waves is the fundamental frequency component two of the body wave in-direction mixing. The low-frequency piezoelectric layer is used to emit low-frequency ultrasonic waves. The frequency of the low-frequency ultrasonic waves is the difference between the fundamental frequency component one and the fundamental frequency component two of the body wave in-direction mixing.
[0008] Furthermore, the high-frequency piezoelectric layer is a longitudinally polarized piezoelectric layer based on the d33 mode.
[0009] Both the low-frequency piezoelectric layer and the mid-frequency piezoelectric layer are laterally polarized piezoelectric layers based on the d31 mode.
[0010] Furthermore, the high-frequency piezoelectric layer is a ring-shaped high-frequency longitudinal wave piezoelectric sheet used to emit high-frequency longitudinal waves.
[0011] The low-frequency piezoelectric layer is a semi-circular low-frequency transverse wave piezoelectric sheet used to emit low-frequency transverse waves;
[0012] The intermediate frequency piezoelectric layer is a semi-circular intermediate frequency transverse wave piezoelectric sheet used to emit intermediate frequency transverse waves.
[0013] Furthermore, the positional relationship between the high-frequency piezoelectric layer, the low-frequency piezoelectric layer, and the medium-frequency piezoelectric layer also satisfies:
[0014] The semi-circular shapes of the low-frequency piezoelectric layer and the medium-frequency piezoelectric layer together form a circular shape;
[0015] The annular shape of the high-frequency piezoelectric layer is coaxial and concentric with the circular shape.
[0016] Furthermore, the center frequency ω of the high-frequency piezoelectric layer L With the center frequency ω of the intermediate frequency piezoelectric layer T The following conditions for body wave in-direction mixing resonance are met:
[0017]
[0018] In the formula, C L Let C be the velocity of longitudinal wave propagation in the sample to be tested. T The velocity of the transverse wave propagation in the sample under test is denoted as .
[0019] Furthermore, it also includes a transducer housing located around the outside of the backing layer.
[0020] Furthermore, the working principle of the three-frequency ultrasonic transducer to achieve co-directional mixing of body waves includes:
[0021] For a homogeneous solid, the displacement wave equation described by Lagrange is constructed as follows:
[0022]
[0023] in:
[0024]
[0025] u i =u i (x,t)
[0026] In the formula, L i [u] represents the component u acting on the displacement. iThe Lagrange operator of the wave equation, C L Let u be the velocity of the longitudinal wave propagating in the sample to be tested. i For x i The displacement x from its initial position at any time t. i Let x be the spatial coordinate scalar of the spatial position vector x in the x-direction. j Let x be the spatial coordinate scalar of the spatial position vector x in the y direction, κ be the ratio of the longitudinal wave speed to the transverse wave speed, and u be the spatial position vector x in the y direction. j Let F be the component of the displacement vector u in the y-direction, and let x be the spatial position vector. i [u] is a homogeneous quadratic function of the displacement vector u = [u1, u2, u3], C T The velocity of the transverse wave propagation in the sample to be tested;
[0027] By retaining terms of up to second order, the solution to equation (1) is:
[0028] u i =u i (0) +u i (1) (2)
[0029] Among them, |u i (0) |>>|u i (1) |,u i (0) For the zero-order displacement solution, u i (1) For displacement u i The first-order correction term, L i [u 0 ] = 0, L i [ω 0 [This is the zeroth order Lagrange equation;]
[0030] Construct the following equation:
[0031] L i [u 1 ] = f i [U 0 ]
[0032] Wherein: F i [u 1 ] << F i [u 0 ]
[0033] In the formula, L i [u 1 ] is a first-order Lagrange equation, F i [u 0 [This refers to] zero-order driving force;
[0034] Suppose two waves propagate along the x1 direction in the x1ox2 plane, that is:
[0035] u1=u1(x1,t), u2=u2(x1,t), u3=0 (4)
[0036] The right side of equation (1) is transformed into:
[0037]
[0038] in:
[0039] β L =3+η L
[0040] β T =κ 2 +η T
[0041]
[0042] In the formula, F1[u] is the component of the driving force in the x-direction, F2[u] is the component of the driving force in the y-direction, and β L Let u1 be the displacement in the x direction, u2 be the displacement in the y direction, u3 be the displacement in the z direction, x1 be the spatial coordinate in the x direction, λ and μ be the Lamé constants of the material, and l, m and n be the Murnaghan third elastic constants of the material.
[0043] Consider the mixing of two simple harmonic waves in the x1ox2 plane, we have:
[0044]
[0045] In the formula, U1 and U2 are amplitudes, and d (m) p (m) m = 1, 2, representing four vectors. ω1 and ω2 are the corresponding values of the vectors, representing the displacement vector and wave vector of the two simple harmonic waves, respectively. ω1 and ω2 are the frequencies, and k1 and k2 are the wave numbers.
[0046] Substituting equation (6) into equation (5), we get:
[0047]
[0048] in:
[0049] ω ± =ω1±ω2
[0050]
[0051] In the formula, b ±ω is a known function of the material and frequency. ± For the frequency and the frequency difference, For wavenumber sum and wavenumber difference;
[0052] Considering the co-directional mixing of longitudinal and transverse waves, let:
[0053]
[0054] Assume the solution to equation (3) is:
[0055]
[0056] Where, The displacement solutions are the sum-frequency signal and the difference-frequency signal.
[0057] Substituting equation (8) into equation (1), we get:
[0058] A ± a ± =U1U2b ± (10)
[0059] in:
[0060]
[0061] Only when Det(A) + )*Det(A - )≠0, and Rank(A) ± |b ± )≠Rank(A ± This generates a resonant wave that propagates in the opposite direction. At this point, the following conditions must be met:
[0062]
[0063] Furthermore, the high-frequency piezoelectric layer, low-frequency piezoelectric layer, and medium-frequency piezoelectric layer are all composite materials made of piezoelectric ceramics and polymers.
[0064] The present invention also provides a method for operating an integrated three-frequency ultrasonic transducer based on the above-described body wave in-direction mixing, comprising the following steps:
[0065] The signal generator produces two fundamental frequency signals that satisfy the bulk wave in-direction mixing resonance condition, namely fundamental frequency signal one and fundamental frequency signal two;
[0066] The fundamental frequency signal excites the high-frequency piezoelectric layer to generate a high-frequency longitudinal wave;
[0067] The fundamental frequency signal excites the intermediate frequency piezoelectric layer to generate an intermediate frequency transverse wave;
[0068] The high-frequency longitudinal wave and the mid-frequency transverse wave propagate in the same direction in the sample under test, generating a resonant difference frequency signal that propagates in opposite directions at a specific location, which is received by the low-frequency piezoelectric layer and converted into an electrical signal.
[0069] The electrical signal is processed by phase inversion and Hanning windowing to extract nonlinear parameters from the resonant difference frequency signal.
[0070] The present invention also provides an application of the working method of the integrated three-frequency ultrasonic transducer based on the above-described body wave co-directional mixing method, which enables co-directional mixing of body waves excited and received on the same side and local damage location and detection.
[0071] Compared with the prior art, the present invention has the following beneficial effects:
[0072] (1) The present invention can realize coaxial and co-directional excitation of the fundamental frequency signal and receive the difference frequency mixing signal, and can realize the same-side excitation and same-side reception of the body wave co-directional mixing and the localization and detection of local damage.
[0073] (2) The present invention provides a matching layer to reduce the acoustic impedance difference between the piezoelectric layer and the sample to be tested, thereby improving the transmission efficiency of ultrasonic energy. It also provides a backing layer to absorb ultrasonic vibrations from the piezoelectric layer, reduce residual vibrations, and reduce crosstalk between different piezoelectric layers. Finally, it provides a transducer housing to provide mechanical protection and electromagnetic shielding for the piezoelectric layer. Attached Figure Description
[0074] Figure 1 This is a schematic diagram of the three-frequency ultrasonic transducer structure of the present invention;
[0075] Figure 2 This is a schematic diagram of an architecture of the nonlinear ultrasonic volume wave mixing experimental device of the present invention.
[0076] Figure 3 The following are the time-domain and frequency-domain plots of the fundamental frequency component signal of this invention;
[0077] Figure 4 The frequency domain diagram and frequency domain diagram of the frequency component two signal of the present invention are shown below;
[0078] Figure 5 This is the original time-domain diagram of the resonant difference frequency signal received by the present invention;
[0079] Figure 6 The time-domain diagram of the received resonant difference frequency signal of the present invention after phase inversion and Hanning windowing;
[0080] Figure 7 The frequency domain diagram of the received resonant difference frequency signal of the present invention after phase inversion and Hanning windowing;
[0081] Figure 8 This is a schematic diagram of the bulk wave in-direction mixing measurement of local adhesive damage according to the present invention;
[0082] Figure 9 This is a diagram showing the volume wave in-direction mixing measurement results of localized adhesive damage according to the present invention.
[0083] Among them, 1-matching layer, 2-high frequency piezoelectric layer, 3-low frequency piezoelectric layer, 4-medium frequency piezoelectric layer, 5-backing layer, 6-transducer housing. Detailed Implementation
[0084] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0085] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.
[0086] This embodiment provides an integrated three-frequency ultrasonic transducer for body wave in-direction mixing, such as... Figure 1 As shown, the transducer includes a matching layer 1, a high-frequency piezoelectric layer 2, a medium-frequency piezoelectric layer 4, a low-frequency piezoelectric layer 3, a backing layer 5, and a transducer housing 6.
[0087] Matching layer 1: It is placed below the piezoelectric layer to reduce the acoustic impedance difference between the piezoelectric layer and the sample under test, thereby improving the transmission efficiency of ultrasonic energy.
[0088] Backing layer 5: As an internal interlayer, it is placed around (above) the piezoelectric layer and inside the transducer housing 6. Its purpose is to absorb ultrasonic vibrations from the piezoelectric layer, reduce residual vibrations, and reduce crosstalk between different piezoelectric layers.
[0089] Transducer housing 6: It is placed outside the backing layer 5 to provide mechanical protection and electromagnetic shielding for the piezoelectric layer;
[0090] High-frequency piezoelectric layer 2: It emits high-frequency ultrasonic waves, the frequency of which is the fundamental frequency component of the bulk wave in the same direction mixing.
[0091] Intermediate frequency piezoelectric layer 4: It emits intermediate frequency ultrasonic waves, the frequency of which is the fundamental frequency component of the bulk wave in the same direction mixing.
[0092] Low-frequency piezoelectric layer 3: It receives low-frequency ultrasonic waves propagating in the reverse direction from the sample under test. The frequency of the low-frequency ultrasonic waves is the difference between the fundamental frequency component one and the fundamental frequency component two of the body wave mixing in the same direction.
[0093] As a preferred embodiment, such as Figure 2 As shown, both fundamental frequency component one and fundamental frequency component two are generated by a signal generator and amplified by a power amplifier (PA). The resonant mixing signal received by the low-frequency piezoelectric layer 3 is transmitted back to the oscilloscope.
[0094] In a preferred embodiment, a computer-controlled signal generator excites a sinusoidal pulse fundamental frequency signal with a center frequency of 10MHz and a period of 10, the time-domain and frequency-domain diagrams of which are shown below. Figure 3 As shown, the signal is transmitted to the high-frequency piezoelectric layer 2 via a power amplifier.
[0095] As a preferred embodiment, such as Figure 2 As shown, a computer-controlled signal generator produces a sinusoidal pulse fundamental frequency signal with a center frequency of 7.5MHz and a period of 10. Its time-domain and frequency-domain plots are as follows. Figure 4 As shown, the signal is transmitted to the intermediate frequency piezoelectric layer 4 via a power amplifier.
[0096] like Figure 3 and Figure 4 As shown, the excitation times of the two fundamental frequency components are different, with the aim of making the two fundamental frequency components meet in a specific mixing region.
[0097] The original time-domain signal received by the low-frequency piezoelectric layer 3 is as follows Figure 5 As shown, the time-domain signal obtained by processing the signal through methods such as phase inversion and adding a Hanning window is as follows: Figure 6 As shown, the frequency domain signal is as follows Figure 7 As shown, the signal is a resonant difference frequency signal generated by the interaction of two fundamental frequency components.
[0098] In a preferred embodiment, a special coupling agent is used to couple the transducer to the sample under test.
[0099] In a preferred embodiment, the high-frequency piezoelectric layer 2 is a longitudinally polarized piezoelectric layer based on the d33 mode, while the mid-frequency piezoelectric layer 4 and the low-frequency piezoelectric layer 3 are both transversely polarized piezoelectric layers based on the d31 mode. The high-frequency piezoelectric layer 2 is a ring-shaped high-frequency longitudinal wave piezoelectric sheet, the mid-frequency piezoelectric layer 4 is a semi-circular mid-frequency transverse wave piezoelectric sheet, and the low-frequency piezoelectric layer 3 is a semi-circular low-frequency transverse wave piezoelectric sheet. The positional relationship between the high-frequency piezoelectric layer 2, the mid-frequency piezoelectric layer 4, and the low-frequency piezoelectric layer 3 should satisfy the following:
[0100] The high-frequency piezoelectric layer 2 is nested outside the mid-frequency piezoelectric layer 4 and the low-frequency piezoelectric layer 3, and the annular shape of the high-frequency piezoelectric layer 2 and the circle formed by the mid-frequency and low-frequency piezoelectric layers 3 should remain coaxial and concentric. The center frequency ω of the high-frequency piezoelectric layer 2 is... L With the center frequency ω of the intermediate frequency piezoelectric layer 4 T Specific body wave in-direction mixing resonance conditions must be met, specifically:
[0101]
[0102] Where C L Let C be the velocity of longitudinal wave propagation in the sample to be tested. T The velocity of the transverse wave propagation in the sample under test is denoted as .
[0103] In a preferred embodiment, the center frequency of the high-frequency piezoelectric layer 2 is 10MHz, the center frequency of the mid-frequency piezoelectric layer 4 is 5MHz, and the center frequency of the low-frequency piezoelectric layer 3 is 2.5MHz.
[0104] In a preferred embodiment, the high-frequency piezoelectric layer 2, the medium-frequency piezoelectric layer 4, and the low-frequency piezoelectric layer 3 are all made of composite materials of piezoelectric ceramics and polymers.
[0105] In a preferred embodiment, the material of the matching layer 1 is a multilayer impedance-gradient composite material.
[0106] In a preferred embodiment, the backing layer 5 is made of a mixture of tungsten powder and epoxy resin.
[0107] In a preferred embodiment, the transducer housing 6 is made of metallic copper.
[0108] The working principle of volume wave in-phase mixing is characterized by:
[0109] For a homogeneous solid, the Lagrangian equation for displacement wave is:
[0110]
[0111] Among them, L i [u] represents the component u acting on the displacement. i The Lagrange operator of the wave equation, C Lu is the velocity of longitudinal waves (i.e., the high-frequency ultrasound mentioned above) propagating in the sample under test. i For x i The displacement x from its initial position at any time t. i Let x be the spatial coordinate scalar of the spatial position vector x in the x-direction. j Let x be the spatial coordinate scalar of the spatial position vector x in the y direction. u is the ratio of the sound speed of longitudinal waves to that of transverse waves. i =u i (x,t) is x i The displacement F from its initial position at any time t. i [u] is a homogeneous quadratic function of the displacement vector u = [u1, u2, u3].
[0112] C T The velocity of the transverse wave propagation in the sample under test is denoted as .
[0113] Asymptotically, by retaining terms up to second order, the solution to equation (1) can be written as:
[0114] u i =u i (0) +u i (1) (2)
[0115] Among them, |u i (0) |>>|u i (1) |,u i (0) The zero-order displacement solution describes the dominant linear wave behavior of the medium, u i (1) For displacement u i The first-order correction term describes the first-order perturbation caused by nonlinear effects, and it is much smaller than the zero-order displacement term u. i (0) L i [u 0 ] = 0, L i [u 0 ] is the zeroth-order Lagrange equation, which describes the linear wave equation in the absence of weak nonlinearity.
[0116] L i [u 1 ] = F i [u 0 (3)
[0117] The derivation of equation (3) takes into account F i [u 1 ] << F i [u 0 ], Li [u 1 [ ] is a first-order Lagrange equation, operator L i For the correction term u i (1) The mechanism of action is the same as that of the zeroth order, with the linear part dominating and the nonlinear part retained up to the second order, F. i [u 0 [This is the zero-order driving force.]
[0118] Assume two waves propagate along the x1 direction in the x1ox2 plane, that is:
[0119] u1=u1(x1,t),u2=u2(x1,t),u3=0 (4)
[0120] The right side of equation (1) becomes:
[0121]
[0122] where β L =3+η L ,β T =κ 2 +η T , λ and μ are the Lamé constants of the material, and l, m, and n are the Murnaghan third-order elastic constants of the material.
[0123] Consider the mixing of two simple harmonic waves in the x1ox2 plane:
[0124]
[0125] in, U1 and U2 represent the displacement vector and wave vector of two simple harmonic waves, respectively. U1 and U2 are the amplitudes, ω1 and ω2 are the frequencies, and k1 and k2 are the wave numbers.
[0126] Substituting equation (6) into equation (5), we get:
[0127]
[0128] Where, ω ± =ω1±ω2 represents the sum and difference of frequencies. Let b be the sum and difference of wavenumbers. ± It is a known function of the material and frequency.
[0129] Consider the co-directional mixing of longitudinal waves (high-frequency ultrasound as mentioned above) and transverse waves (mid-frequency ultrasound as mentioned above).
[0130]
[0131] Assume the solution to equation (3) is:
[0132]
[0133] in, The displacement solutions are the sum-frequency signal and the difference-frequency signal.
[0134] Substituting into equation (1), we get:
[0135] A ± a ± =U1U2b ± (10)
[0136] in:
[0137]
[0138] Only when Det(A) + )*Det(A - )≠0 and Rank(A) ± |b ± )≠Rank(A ± When ), a resonant wave propagating in the reverse direction will be generated.
[0139] At this point, the following conditions need to be met:
[0140]
[0141] That is, the resonance conditions specified above.
[0142] Based on the aforementioned integrated three-frequency ultrasonic transducer, this invention also provides a self-transmitting and self-receiving measurement method for co-directional mixing signals, the method comprising:
[0143] The signal generator produces two fundamental frequency signals that meet the frequency conditions;
[0144] The base frequency signal excites the high-frequency piezoelectric layer to generate a high-frequency longitudinal wave;
[0145] The fundamental frequency signal excites the intermediate frequency piezoelectric layer to generate an intermediate frequency transverse wave;
[0146] The high-frequency longitudinal wave and the mid-frequency transverse wave propagate in the same direction in the sample. In a specific mixing region, due to the presence of nonlinear sources such as materials and microcracks in the region, a resonant difference frequency signal propagates in the opposite direction. The resonant difference frequency signal is received by the low-frequency piezoelectric layer 3 and converted into an electrical signal.
[0147] The low-frequency piezoelectric layer 3 received signal is processed by a signal processing method involving phase reversal and adding a Hanning window, and nonlinear parameters in the resonant difference frequency signal are extracted.
[0148] In one embodiment, the operation method of the integrated tri-frequency ultrasonic transducer includes the following steps:
[0149] The signal generator produces two fundamental frequency signals that meet the frequency conditions;
[0150] The base frequency signal excites the high-frequency piezoelectric layer to generate a high-frequency longitudinal wave;
[0151] The fundamental frequency signal excites the intermediate frequency piezoelectric layer to generate an intermediate frequency transverse wave;
[0152] The high-frequency longitudinal wave and the mid-frequency transverse wave propagate in the same direction in the sample. In a specific mixing region, due to the presence of nonlinear sources such as materials and microcracks in the region, a resonant difference frequency signal propagates in the opposite direction. The resonant difference frequency signal is received by the low-frequency piezoelectric layer 3 and converted into an electrical signal.
[0153] The low-frequency piezoelectric layer 3 received signal is processed by a signal processing method involving phase reversal and adding a Hanning window, and nonlinear parameters in the resonant difference frequency signal are extracted.
[0154] Based on the application of the above working method, the measurement of body wave homogeneous mixing and local nonlinear ultrasound (local damage location and detection) by homogeneous excitation and homogeneous reception can be achieved.
[0155] like Figure 8 As shown, it consists of two 100*100*25mm... 3 The aluminum blocks were bonded with epoxy resin, but area 2 was made of Teflon and was 20*30mm thick. 2 The adhesive damage areas were measured in areas 1, 2, and 3 using the methods described above.
[0156] like Figure 9 As shown, the amplitude of the mixed-frequency wave in the well-bonded area and the bonded damaged area is significantly different, thus locating the bonded damaged area of the test specimen.
[0157] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0158] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. An integrated three-frequency ultrasonic transducer for body wave in-direction mixing, characterized in that, The system includes a matching layer (1), a high-frequency piezoelectric layer (2), a low-frequency piezoelectric layer (3), a mid-frequency piezoelectric layer (4), and a backing layer (5). The matching layer (1) and the backing layer (5) are respectively disposed below and around the high-frequency piezoelectric layer (2), the low-frequency piezoelectric layer (3), and the mid-frequency piezoelectric layer (4). The high-frequency piezoelectric layer (2) is nested outside the low-frequency piezoelectric layer (3) and the mid-frequency piezoelectric layer (4) and is used to emit high-frequency ultrasonic waves. The frequency of the high-frequency ultrasonic waves is the fundamental frequency component one of the body wave in the same direction mixing. The mid-frequency piezoelectric layer (4) is used to emit mid-frequency ultrasonic waves. The frequency of the mid-frequency ultrasonic waves is the fundamental frequency component two of the body wave in the same direction mixing. The low-frequency piezoelectric layer (3) is used to emit low-frequency ultrasonic waves. The frequency of the low-frequency ultrasonic waves is the difference between the fundamental frequency component one and the fundamental frequency component two of the body wave in the same direction mixing.
2. The integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 1, characterized in that, The high-frequency piezoelectric layer (2) is a longitudinally polarized piezoelectric layer based on the d33 mode. The low-frequency piezoelectric layer (3) and the mid-frequency piezoelectric layer (4) are both transversely polarized piezoelectric layers based on the d31 mode.
3. The integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 1, characterized in that, The high-frequency piezoelectric layer (2) is a ring-shaped high-frequency longitudinal wave piezoelectric sheet used to emit high-frequency longitudinal waves. The low-frequency piezoelectric layer (3) is a semi-circular low-frequency transverse wave piezoelectric sheet used to emit low-frequency transverse waves; The intermediate frequency piezoelectric layer (4) is a semi-circular intermediate frequency transverse wave piezoelectric sheet used to emit intermediate frequency transverse waves.
4. The integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 3, characterized in that, The positional relationship between the high-frequency piezoelectric layer (2), the low-frequency piezoelectric layer (3), and the medium-frequency piezoelectric layer (4) also satisfies: The semi-circular shapes of the low-frequency piezoelectric layer (3) and the medium-frequency piezoelectric layer (4) form a circular shape; The annular shape of the high-frequency piezoelectric layer (2) is coaxial and concentric with the circular shape.
5. An integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 1, characterized in that, The center frequency ω of the high-frequency piezoelectric layer (2) L With the center frequency ω of the intermediate frequency piezoelectric layer (4) T The following conditions for body wave in-direction mixing resonance are met: In the formula, C L Let C be the velocity of longitudinal wave propagation in the sample to be tested. T The velocity of the transverse wave propagation in the sample under test is denoted as .
6. The integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 1, characterized in that, It also includes a transducer housing (6) located around the outside of the backing layer (5).
7. The integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 1, characterized in that, The working principle of the three-frequency ultrasonic transducer to achieve co-directional mixing of body waves includes: For a homogeneous solid, the displacement wave equation described by Lagrange is constructed as follows: in: u i =u i (x,t) Where, L i [y] represents the force acting on the displacement component u. i The Lagrange operator of the wave equation, C L Let u be the velocity of the longitudinal wave propagating in the sample to be tested. i For x i The displacement x from its initial position at any time t. i Let x be the spatial coordinate scalar of the spatial position vector x in the x-direction. j Let x be the spatial coordinate scalar of the spatial position vector x in the y direction, κ be the ratio of the longitudinal wave speed to the transverse wave speed, and y be the spatial coordinate scalar of the spatial position vector x in the y direction. j Let F be the component of the displacement vector u in the y-direction, and let x be the spatial position vector. i [y] is a homogeneous quadratic function of the displacement vector u = [u1, u2, u3], C T The velocity of the transverse wave propagation in the sample to be tested; By retaining terms of up to second order, the solution to equation (1) is: in i =in i (0) +in i (1) (2) Among them, |u i (0) |>>|u i (1) |,u i (0) For the zero-order displacement solution, u i (1) For displacement u i The first-order correction term, L i [u 0 ] = 0, L i [u 0 [This is the zeroth order Lagrange equation;] Construct the following equation: L i [and 1 ]=F i [and 0 ] Among them: F i [u 1 ]<<F i [u 0 ] Where, L i [u 1 ] is a first-order Lagrange equation, F i [u 0 [This refers to] zero-order driving force; Suppose two waves propagate along the x1 direction in the x1ox2 plane, that is: u1=u1(x1,t), u2=u2(x1,t), u3=0 (4) The right side of equation (1) is transformed into: in: b L =3+n L b T =k 2 +n T In the formula, F1[u] is the component of the driving force in the x-direction, F2[u] is the component of the driving force in the y-direction, and β L Let u1 be the displacement in the x direction, u2 be the displacement in the y direction, u3 be the displacement in the z direction, x1 be the spatial coordinate in the x direction, λ and μ be the Lamé constants of the material, and l, m and n be the Murnaghan third elastic constants of the material. Consider the mixing of two simple harmonic waves in the x1ox2 plane, we have: u3 (0) ＝0 (6) In the formula, U1 and U2 are amplitudes, and d (m) p (m) m = 1, 2, representing four vectors. ω1 and ω2 are the corresponding values of the vectors, representing the displacement vector and wave vector of the two simple harmonic waves, respectively. ω1 and ω2 are the frequencies, and k1 and k2 are the wave numbers. Substituting equation (6) into equation (5), we get: in: oh ± =ω1±ω2 In the formula, b ± ω is a known function of the material and frequency. ± For the frequency and the frequency difference, The sum and difference of wavenumbers; Considering the co-directional mixing of longitudinal and transverse waves, let: Assume the solution to equation (3) is: In the formula, The displacement solutions are the sum-frequency signal and the difference-frequency signal. Substituting equation (8) into equation (1), we get: in: Only when Det(A) + )*Det(A - )≠0, and Rank(A) ± |b ± )≠Rank(A ± This generates a resonant wave that propagates in the opposite direction. At this point, the following conditions must be met:
8. An integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 1, characterized in that, The high-frequency piezoelectric layer (2), low-frequency piezoelectric layer (3), and medium-frequency piezoelectric layer (4) are all composite materials of piezoelectric ceramics and polymers.
9. A method for operating an integrated three-frequency ultrasonic transducer with body wave in-direction mixing according to any one of claims 1-8, characterized in that, Includes the following steps: The signal generator produces two fundamental frequency signals that satisfy the bulk wave in-direction mixing resonance condition, namely fundamental frequency signal one and fundamental frequency signal two; The fundamental frequency signal excites the high-frequency piezoelectric layer (2) to generate a high-frequency longitudinal wave; The fundamental frequency signal excites the intermediate frequency piezoelectric layer (4) to generate an intermediate frequency transverse wave; The high-frequency longitudinal wave and the mid-frequency transverse wave propagate in the same direction in the sample under test, generating a resonant difference frequency signal that propagates in opposite directions at a specific location, which is received by the low-frequency piezoelectric layer (3) and converted into an electrical signal. The electrical signal is processed by phase inversion and Hanning windowing to extract nonlinear parameters from the resonant difference frequency signal.
10. An application of the working method of the integrated three-frequency ultrasonic transducer for body wave in-direction mixing according to claim 9, characterized in that, Using the aforementioned working method, it is possible to achieve same-side excitation and same-side reception of body waves in the same direction for mixing and localization and detection of local damage.