Self-supporting structure deep water transducer based on relaxor ferroelectric single crystal

Abstract

The application discloses a self-supporting structure deep water transducer based on a relaxor ferroelectric single crystal, which comprises a certain number of transducer units, each of which comprises a piezoelectric element, a transition block, a curved shell, a force transmission plate and a radiation panel; the piezoelectric element adopts a relaxor ferroelectric single crystal element; the curved shell adopts a type VII bending-stretching transducer shell form with the long axis and the short axis vibrating in phase, one force transmission plate is added to the outside of the short axis of the shell, a certain number of transducer units are arranged in a certain rule, the radiation panel is connected to the transducer units through the force transmission plates at both ends of the transducer units, the transverse vibration of the single crystal element is amplified in displacement through the curved shell at the short axis of the shell, the vibration is transmitted to the radiation panel through the force transmission plate, the radiation panel is used for reducing the working frequency, unifying the vibration phase of the transducer units, directly facing the fluid to bear the hydrostatic pressure, and isolating the internal space from the external fluid; the static pressure of the external fluid acts on the radiation panel and then acts on the short axis of the shell through the force transmission plate.

Description

Technical Field

[0001] This invention belongs to the field of underwater electronic equipment technology, specifically relating to a self-supporting deep-sea transducer based on a relaxor ferroelectric single crystal. Background Technology

[0002] The pressure-resistant structural forms for underwater acoustic transducers to operate in deep water mainly include self-supporting, compressed gas-filled, oil-filled with compliant tubing, oil-filled, and overflow types. Among these, the self-supporting type has a simple structure but a shallow operating depth, typically not exceeding 300m, and its performance varies greatly with water depth. A representative transducer type is the air-backed tension transducer. Tension transducers are generally classified into seven categories, with Type IV and Type VII being typical low-frequency, high-power transmitting transducers. As hydrostatic pressure increases, the combined stress on the transducer shell causes the prestress of the air-backed Type IV tension transducer to gradually decrease, leading to a decline in transducer performance; the operating depth then depends on the magnitude of the prestress. Conversely, the prestress of the air-backed Type VII tension transducer gradually increases, and its operating depth depends on the structural mechanical strength.

[0003] An effective technical approach to improving the transmission power of underwater acoustic transducers is to use high-performance active materials. Relaxor ferroelectric single crystals possess superior piezoelectric and dielectric properties compared to piezoelectric ceramics. Due to the anisotropic nature of relaxor ferroelectric single crystal materials, they exhibit different characteristics and applications along different polarization directions.

[011] c Directional polarization relaxor ferroelectric single crystal materials d 32 Compared to isotropic piezoelectric ceramics d 31 Several times higher, exhibiting superior piezoelectric properties in its lateral length direction, effectively improving the transducer's emission performance. According to the above

[011] ... c The properties of directionally polarized relaxor ferroelectric single crystal materials can be integrated with air-backed VII-type bending transducer structures to achieve greater water depth and higher power transmission.

[0004] In the 2010s, the U.S. Naval Research Laboratory publicly reported on a lightweight, thin, broadband planar transducer for shallow-water UUV operations, utilizing

[001] . c Radial polarization of relaxed ferroelectric single-crystal wafers d 31 In the vibration mode, a convex cymbal-shaped bending transducer was fabricated, and a planar emission transducer was developed by using 25 cymbal-shaped transducer units arranged in 5 rows and 5 columns and bolts to fix the units to the radiation panels on both sides.

[0005] Self-supporting transducers lack sufficient water depth resistance, and their working depth is limited by the strength of the mechanical structure and the magnitude of the prestress. For air-backed Type IV bending transducers, as the hydrostatic pressure increases, the overall stress on the transducer shell gradually reduces the prestress, leading to a decline in transducer performance. Transducer performance is also affected by the active material. Piezoelectric materials are commonly used active materials in underwater acoustic transducers; a higher piezoelectric coefficient is beneficial for improving transducer performance. New relaxor ferroelectric single-crystal materials have piezoelectric coefficients several times higher than those of traditional piezoelectric ceramics. Summary of the Invention

[0006] To address the deficiencies and shortcomings of the prior art, the present invention provides a method combining

[011] c The properties of directionally polarized relaxor ferroelectric single crystal materials are integrated with an air-backed VII-type bending transducer structure to achieve transducer transmission at greater depths and with higher power. Compared with piezoelectric ceramic elements, the piezoelectric coefficient is higher, and the transducer can achieve a higher transmission response. Compared with using a convex bending shell, it can apply prestress to the piezoelectric element and improve the transducer's resistance to hydrostatic pressure. This is a self-supporting deep-water transducer based on relaxor ferroelectric single crystals.

[0007] The objective of this invention is achieved through the following technical solution: a self-supporting deep-sea transducer based on a relaxor ferroelectric single crystal, comprising a certain number of transducer units, each transducer unit including a piezoelectric element, a transition block, a bending shell, a force transmission plate, and a radiation panel; the piezoelectric element adopts an

[011] ... c The device employs a directionally polarized relaxor ferroelectric single-crystal element. The curved housing adopts a VII-type bending transducer housing form with co-phase vibration of the long and short axes. A force transmission plate is added to the outer side of the short axis of the housing. A certain number of transducer units are arranged according to a specific rule. A radiating panel is connected to both ends of the transducer units via the force transmission plates. The lateral vibration of the single-crystal element is amplified through the curved housing along the short axis. The force transmission plates transmit the vibration to the radiating panel. The radiating panel is used to reduce the operating frequency and unify the vibration phase of the transducer units. Simultaneously, it directly faces the fluid and bears the hydrostatic pressure, isolating the internal space from the external fluid. The hydrostatic pressure of the external fluid acts on the radiating panel, and then acts on the short axis of the housing via the force transmission plates. The contraction of the short axis causes the long axis to contract simultaneously. The pressure along the long axis of the housing acts on the piezoelectric element through a transition block. As the hydrostatic pressure increases, the pressure on the element, i.e., the prestress, increases. This increases the working depth of the transducer while ensuring the mechanical strength of the piezoelectric element and the passive structure.

[0008] Preferably, the piezoelectric element has a cuboid structure, with the length and width of the cuboid being much greater than its thickness; the piezoelectric element is made of a novel relaxor ferroelectric single crystal material, and the single crystal element is along

[011] cDirectional polarization; piezoelectric constant corresponding to polarization along the width direction d 32 It is a negative value, the piezoelectric constant corresponding to polarization along the length direction. d 31 It is a positive value, and d 32 Absolute value greater than d 31 .

[0009] Preferably, the curved shell is a concave tensile body composed of three structural parts: an end block structure, a beveled edge structure, and a platform structure; the shell thickness along the long axis is greater than the shell thickness along the short axis.

[0010] Preferably, the end block structure is a cuboid in shape and is connected to the transition block and the inclined side structure. The length of the end block structure is the same as the length of the piezoelectric element, the width is equal to the sum of the thickness of the piezoelectric element, the height of the inner cavity of the curved shell, and the height of the inclined side structure, and the thickness is greater than the thickness of the platform structure. The inclined side structure is a parallelogram-shaped stretched body with the same length as the piezoelectric element, inclined from the edge of the end block structure towards the element, and the thickness is the same as the thickness of the platform structure. The platform structure is a cuboid with the same length as the piezoelectric element, a width less than the length of the piezoelectric element, and a thickness the same as the inclined side structure and less than the thickness of the end block structure.

[0011] Preferably, the force transmission plate is a cuboid structure with the same length as the piezoelectric element, a width greater than that of the end block structure, and a thickness less than that of the platform structure.

[0012] Preferably, all transducer units are arranged at equal intervals along the length and width directions of the transducer; the spacing between units along the length direction is equal to the sum of the transducer unit length and the gap, and the spacing between units along the width direction is equal to the sum of the transducer unit width and the gap; the gap along the length direction of the transducer units is equal to the gap along the width direction of the transducer units.

[0013] Preferably, there are two radiating panels, located on both sides of the transducer unit. The length of the radiating panel is greater than the length of all the transducer units arranged at equal intervals, the width of the radiating panel is greater than the width of all the transducer units arranged at equal intervals, and the thickness of the radiating panel is much smaller than its length and width.

[0014] Preferably, the piezoelectric element has a length, width, and thickness of 20mm*17mm*2mm.

[0015] Preferably, the transition block is made of aluminum alloy, and the bending shell, force transmission plate, and radiation panel are made of TC4 titanium alloy.

[0016] Preferably, the length of the force transmission plate is equal to the tensile length of the bending shell.

[0017] The beneficial effects of this invention are:

[0018] Compared with piezoelectric ceramic elements, the present invention has a higher piezoelectric coefficient, and the transducer can achieve a higher emission response. Compared with convex curved shells, the present invention can apply prestress to the piezoelectric elements and improve the transducer's resistance to hydrostatic pressure. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of a bent structure transducer unit using a relaxor ferroelectric single crystal cuboid element in one embodiment of the present invention.

[0020] Figure 2 This is a front view of a bent structure transducer unit using a relaxor ferroelectric single-crystal cuboid element in one embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the arrangement of 25 transducer units in one embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of a transducer with an added radiating panel in one embodiment of the present invention;

[0023] Figure 5 This is a front view of a transducer unit with a radiating panel in one embodiment of the present invention;

[0024] Figure 6 This is a front view of the displacement change of the radiating panel of the transducer unit under a normal force in one embodiment of the present invention;

[0025] Figure 7 This is a finite element simulation curve of the transducer's emission voltage response in water in three directions in one embodiment of the present invention;

[0026] Figure 8 This is a finite element simulation curve of the directional properties of three planes in the water of the transducer in one embodiment of the present invention;

[0027] 1-Piezoelectric element, 2-Transition block, 3-Force transmission plate, 4-Bending shell, 5-Radiation panel, A-End block structure, B-Hydraulic edge structure, C-Platform structure. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0029] The embodiments provided in this invention include a self-supporting deep-water transducer based on a relaxor ferroelectric single crystal, such as... Figure 4 As shown, the transducer includes two radiating panels and 25 transducer units. Each transducer unit includes one piezoelectric element, two transition blocks, one bending shell, and two force transmission plates.

[0030] In this embodiment, the transducer's length, width, and height dimensions are 162mm*105mm*17.8mm, and the transducer's length, width, and height directions are the same as the piezoelectric element's width, length, and thickness directions.

[0031] like Figure 1 and 2 As shown, the piezoelectric single-crystal element in this embodiment is a cuboid, with its length and width much greater than its thickness, measuring 20mm*17mm*2mm respectively; the piezoelectric element is fabricated using a novel relaxor ferroelectric single-crystal material PIN-46%PMN-30%PT, and the single-crystal element is along

[011] c Directional polarization; the two planes of the piezoelectric element's length and width serve as the positive and negative electrode planes, respectively; the piezoelectric element's... d 32 The direction is the same as the width direction of the piezoelectric element, and the piezoelectric element's d 31 The direction is the same as the length direction of the piezoelectric element, and the piezoelectric element's d 33 The direction is the same as the thickness direction of the piezoelectric element; the piezoelectric element's d 32 -1693pC / N d 31 It is 675pC / N. d 33 It is 1068 pC / N.

[0032] In this embodiment, the transition block is a cuboid made of aluminum alloy. The length of the transition block is the same as the length of the piezoelectric element, the thickness is the same as the thickness of the piezoelectric element, and the width is much smaller than the length. The length, width and thickness are 20mm*4mm*2mm respectively.

[0033] In this embodiment, the curved shell and force transmission plate are integrally formed using a machining method, and the material is TC4 titanium alloy; the curved shell is a stretched body, and the stretched length is the same as the length of the piezoelectric element; Figure 2The main view shows that the curved shell consists of three structures: end block structure A, inclined side structure B, and platform structure C. The end block structure is a cuboid with dimensions of 20mm x 12.8mm x 3.2mm. It connects to the transition block and the inclined side structure. The length of the end block structure is the same as the length of the piezoelectric element, and its width is equal to the sum of the thickness of the piezoelectric element, the height of the inner cavity of the shell, and the height of the inclined side structure. Its thickness is greater than that of the platform structure. The inclined side structure is a parallelogram-shaped stretched body with the same length as the piezoelectric element. It slopes from the edge of the end block structure towards the element, and its thickness is the same as that of the platform structure. The platform structure is a cuboid with dimensions of 20mm x 5mm x 2.4mm. Its length is the same as the length of the piezoelectric element, its width is less than the length of the piezoelectric element, and its thickness is the same as that of the inclined side structure and less than that of the end block structure.

[0034] In this embodiment, the force transmission plate is a cuboid with a length, width, and thickness of 20mm*4.5mm*2mm. Its length is the same as that of the piezoelectric element, its width is greater than that of the end block structure, and its thickness is less than that of the platform structure.

[0035] Figure 3 This is a schematic diagram of the arrangement of 25 identical transducer units in this embodiment. All transducer units are arranged in 5 rows and 5 columns with equal spacing along the length and width directions; the spacing between units along the length direction is equal to the sum of the transducer unit length and the gap, and the spacing between units along the width direction is equal to the sum of the transducer unit width and the gap; the gap along the length direction of the transducer units is equal to the gap along the width direction of the transducer units; wherein the gap is 2mm.

[0036] Figure 4 This is a schematic diagram of the transducer with added radiating panels in this embodiment. The transducer includes two radiating panels, which are identical in structure, size, and material, and are located on both sides of the 25 transducer units. The radiating panels are cuboids with dimensions of 162mm*105mm*2.4mm (length*width*th thickness), and are made of TC4 titanium alloy. The length of the radiating panels is greater than the length of all the transducer units arranged at equal intervals, the width of the radiating panels is greater than the width of all the transducer units arranged at equal intervals, and the thickness of the radiating panels is much smaller than their length and width.

[0037] In this embodiment, the lateral vibration of the single crystal element is amplified by the displacement on the short axis through the bending shell. The force transmission plate transmits the vibration to the radiation panel. The addition of the radiation panel can reduce the operating frequency, unify the vibration phase of the transducer unit, and directly face the fluid to bear the hydrostatic pressure, thus isolating the internal space from the external fluid.

[0038] Figure 5This is a front view of a transducer unit with a radiating panel in this embodiment. Fixed constraints are applied to one side of the radiating panel, and a normal planar load is applied to the outer surface of the other side of the radiating panel to simulate hydrostatic pressure. Figure 6 The resulting displacement change causes the transducer housing to contract along both the short and long axes, generating lateral pressure on the piezoelectric element through the transition block. As the hydrostatic pressure increases, the pressure on the element, i.e., the prestress, increases. Under the premise of ensuring the mechanical strength of the piezoelectric element and the passive structure, the working depth of the transducer can be increased.

[0039] Figure 7 These are the finite element simulation curves of the transducer's emission voltage response in water in three directions in this embodiment. The resonant frequency is 3kHz, the maximum emission voltage response is 117dB, the -3dB bandwidth is approximately 1.3kHz, and the Q value is 2.3.

[0040] Figure 8 These are the finite element simulation curves of the transducer's three planes in the water in this embodiment, showing that the transducer is non-directional.

[0041] In summary, the self-supporting deep-water transducer based on a relaxor ferroelectric single crystal provided by this invention has a higher piezoelectric coefficient and can achieve a higher transmission response compared to transducers using piezoelectric ceramic elements. Compared to using a convex curved shell, this embodiment can apply prestress to the piezoelectric element and improve the transducer's resistance to hydrostatic pressure. This has significant military application value for enhancing the detection capabilities of active sonar.

[0042] This invention cites relevant papers by James F. Tressler, such as A comparison of the underwater acoustic performance of single crystal versus piezoelectric ceramic-based “cymbal” projectors. J. Acoustic. Soc, Am. 119(2), 2006:879-889.

[0043] Explanation of relevant technical terms in this invention: Ternary relaxor ferroelectric single crystal PIN-PMN-PT (PIMNT, Pb(In) 1 / 2 Nb 1 / 2 O3-Pb(Mg) 1 / 3 Nb 2 / 3 (O3-PbTiO3) is a solid solution of lead indium niobate, lead magnesium niobate, and lead titanate.

[0044] Self-supporting transducer is a type of pressure-resistant structure that relies on its own structural strength to resist the effects of hydrostatic pressure on the transducer. Air-backed transducers typically use this type of pressure-resistant transducer. The advantage of this method is its simple structure, but the disadvantages are its shallow working depth and large variations in transducer performance.

[0045] The Type IV bending transducer is composed of multiple short elliptical tubes. An active material stack is inserted into each elliptical shell along its major axis. When the active material stack undergoes expansion and contraction vibrations, it excites the elliptical tubes to undergo bending vibrations. To achieve broadband emission, the coupling of multiple vibration modes is often utilized. Its drawback is that as the water depth increases, the prestress on the active material stack decreases, reducing its radiation performance.

[0046] The Type VII bending transducer is structurally similar to the Type IV bending transducer, with the shell being obtained by stretching a bending plane. The Type VII has a cross-section that is large at both ends and small in the middle, resembling a bone; therefore, the Type VII bending transducer is also known as a "dog bone" transducer. As water depth increases, the prestress of the air-backed Type VII bending transducer gradually decreases, and the working depth depends on the structural mechanical strength.

[0047] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A self-supporting structure deep water transducer based on a relaxor ferroelectric single crystal, characterized in that: The application relates to a transducer unit, which comprises a plurality of transducer units, each of which comprises a piezoelectric element, a transition block, a curved shell, a force transmission plate and a radiation panel; the piezoelectric element adopts a relaxor ferroelectric single crystal element polarized along the [011] c direction; the curved shell adopts a type VII bending-stretching transducer shell in which the long axis and the short axis vibrate in phase, one force transmission plate is added to the outside of the short axis of the shell, a plurality of transducer units are regularly arranged, radiation panels are connected to the two ends of the transducer units through the force transmission plates, the transverse vibration of the single crystal element is amplified in displacement through the curved shell at the short axis of the shell, the vibration is transmitted to the radiation panels through the force transmission plates, the radiation panels are used for reducing the working frequency, unifying the vibration phase of the transducer units, directly facing the fluid to bear the hydrostatic pressure, and isolating the internal space from the external fluid. The static pressure of the external fluid acts on the radiating panel, and then on the short axis of the shell through the force transmission plate. The contraction of the short axis of the shell causes the long axis to contract simultaneously. The pressure along the long axis of the shell acts on the piezoelectric element through the transition block. As the hydrostatic pressure increases, the pressure on the piezoelectric element, i.e., the prestress, increases. While ensuring the mechanical strength of the piezoelectric element and the passive structure, the working depth of the transducer is increased.

2. The self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 1, characterized in that: The piezoelectric element is a cuboid structure, the length and width of the cuboid are much greater than the thickness; the piezoelectric element is prepared from a new type of relaxor ferroelectric single crystal material, the single crystal element is polarized along [011] c direction; the piezoelectric constant corresponding to the polarization along the width direction d 32 is a negative value, the piezoelectric constant corresponding to the polarization along the length direction d 31 is a positive value, and d 32 the absolute value is greater than d 31 .

3. A self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 2, characterized in that: The curved shell is a concave tensile body composed of three structural parts: an end block structure, a beveled edge structure, and a platform structure; the shell thickness along the long axis is greater than the shell thickness along the short axis.

4. The self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 3, characterized in that: The end block structure is a cuboid in shape and is connected to the transition block and the inclined side structure. The length of the end block structure is the same as the length of the piezoelectric element, the width is equal to the sum of the thickness of the piezoelectric element, the height of the inner cavity of the curved shell, and the height of the inclined side structure, and the thickness is greater than the thickness of the platform structure. The inclined side structure is a parallelogram-shaped stretched body with the same length as the piezoelectric element, inclined from the edge of the end block structure towards the element, and the thickness is the same as the thickness of the platform structure. The platform structure is a cuboid with the same length as the piezoelectric element, a width less than the length of the piezoelectric element, and a thickness the same as the inclined side structure and less than the thickness of the end block structure.

5. A self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 3, characterized in that: The force transmission plate is a cuboid structure with the same length as the piezoelectric element, a width greater than the end block structure, and a thickness less than the platform structure width.

6. A self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 3, characterized in that: All transducer units are arranged at equal intervals along the length and width directions of the transducer; the spacing between units along the length direction is equal to the sum of the transducer unit length and the gap, and the spacing between units along the width direction is equal to the sum of the transducer unit width and the gap; the gaps along the length direction and the gaps along the width direction of the transducer units are equal.

7. A self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 3, characterized in that: There are two radiating panels, located on both sides of the transducer unit. The length of the radiating panel is greater than the length of all the transducer units arranged at equal intervals, the width of the radiating panel is greater than the width of all the transducer units arranged at equal intervals, and the thickness of the radiating panel is much smaller than its length and width.

8. A self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 2, characterized in that: The piezoelectric element has dimensions of 20mm*17mm*2mm (length*width*th thickness).

9. A self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 1, characterized in that: The transition block is made of aluminum alloy, and the bending shell, force transmission plate, and radiation panel are made of TC4 titanium alloy.

10. A self-supporting deep-water transducer based on a relaxor ferroelectric single crystal according to claim 5, characterized in that: The length of the force transmission plate is equal to the tensile length of the bending shell.

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