A vibration measurement and control device and method for a semi-cylindrical shell structure

Abstract

The present invention discloses a vibration measurement and control device and method for a semi-cylindrical shell structure, comprising a three-layer truss structure, a vibration detection assembly, and a control assembly. The three-layer truss structure comprises three spaced-apart flat plates connected by support slots and the semi-cylindrical shell, with the thickness of the lower semi-cylindrical shell greater than that of the upper semi-cylindrical shell. The vibration detection assembly comprises a piezoelectric film and a fiber laser vibrometer. Two piezoelectric films are attached to the outer wall of each semi-cylindrical shell to measure the vibration state of the semi-cylindrical shell structure. The laser direction of the fiber laser vibrometer points along the radius of the semi-cylindrical shell toward the center of the shell. The control assembly analyzes the vibration information from the piezoelectric film and the fiber laser vibrometer to determine the deformation status and modal frequency of the semi-cylindrical shell. This invention can quickly and accurately control and detect the vibration of a semi-cylindrical thin-walled shell structure.

Description

Technical Field

[0001] The present invention relates to the field of detection and control, and in particular to a vibration measurement and control device and method for a semi-cylindrical shell structure. Background Art

[0002] Thin-walled shell structures, as indispensable basic components, such as the outer shells of guided missiles, the drums of aircraft engines, and the tubes of high-speed centrifugal separators, are often used in the fields of machinery, aerospace, and submarines due to their simple manufacturing, large load-bearing capacity, and high rigidity-to-weight ratio. Thin-shell structures are subjected to complex loads and different boundary conditions during operation, which may affect the performance and life of these structures. Cavity noise caused by fluids is also widely present in thin-shell structures, affecting the operating accuracy of the mechanism and the user experience. Thin-shell structures have high specific strength and specific stiffness, and are therefore widely used in the aerospace field. In addition, semi-cylindrical shell structures have stronger bending resistance than flat plate structures of the same volume, and are expected to replace flat plate pillars as supporting structures.

[0003] With the development of computer technology and smart materials, the use of smart materials combined with testing technology and automatic control technology to measure and suppress vibration has become mature. The main idea is to integrate smart materials as sensors or actuators into flexible structures, detect the vibration of the flexible structure through sensors, and transmit it to the computer for corresponding processing.

[0004] In the prior art, the most commonly used sensor for detecting vibration is a piezoelectric ceramic piece. The piezoelectric ceramic piece has a fast response, a wide frequency bandwidth, and low power consumption, but it is not bendable and cannot be attached to the curved surface of a spherical thin shell. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, an object of the present invention is to provide a vibration measurement and control device and method for a semi-cylindrical shell structure.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A vibration measurement and control device of a semi-cylindrical shell structure, comprising a three-layer truss structure, a vibration detection component and a control component;

[0008] The three-layer truss structure includes three flat plates arranged at a distance from each other, and adjacent flat plates are connected by support slots and semi-cylindrical shells, and the thickness of the semi-cylindrical shell located in the lower layer is greater than that of the semi-cylindrical shell located in the upper layer;

[0009] The vibration detection assembly includes a piezoelectric film and a fiber laser vibrometer. Two piezoelectric films are attached to the outer wall of each semi-cylindrical shell to obtain the vibration state of the semi-cylindrical shell structure. The laser direction of the fiber laser vibrometer is directed along the radius of the semi-cylindrical shell to the center point of the shell.

[0010] The control component analyzes the vibration information of the piezoelectric film and the fiber laser vibrometer to obtain the deformation condition and the modal frequency of the semi-cylindrical shell.

[0011] Furthermore, the control component includes a computer, a charge amplifier and an A / D acquisition card. The laser emitted by the semi-cylindrical shell of the fiber laser vibrometer structure generates interference and transmits vibration information to the computer. The piezoelectric film detects the strain information of the semi-cylindrical shell, which is amplified by the piezoelectric amplifier and then collected by the first channel of the A / D acquisition card and transmitted to the computer.

[0012] Furthermore, the fiber laser vibrometer includes a fiber head, a bracket and a fiber laser control box. The bracket is provided with a spherical connecting part. The fiber head is arranged on the bracket. The fiber laser control box is connected to the fiber head and connected to the control component.

[0013] Furthermore, the outer diameter of the semi-cylindrical shell is 40 mm, the thickness is 3 mm or 2 mm, and the height is 200 mm.

[0014] Furthermore, support slots are provided at both ends of the semi-cylindrical shell.

[0015] Furthermore, the piezoelectric film has a size of 40 mm×15 mm×1 mm and is attached to the center of the semi-cylindrical shell.

[0016] Furthermore, the control component is also connected to a vibration control component, which is used to adjust the power of the vibration excitation device, simulate different working states of the semi-cylindrical shell under different conditions, and control the generated vibration.

[0017] Furthermore, the concave surfaces of the two layers of semi-cylindrical shells are placed with a 90-degree difference in orientation.

[0018] A method of the vibration measurement and control device, comprising:

[0019] Step 1: Turn on and initialize all parts of the device, and manually apply excitation to generate forced vibration of the semi-cylindrical shell;

[0020] Step 2: The piezoelectric film detects the strain information of the semi-cylindrical shell, which is amplified by the charge amplifier and then collected by the first channel of the A / D acquisition card and transmitted to the computer;

[0021] Step 3: Four fiber laser vibrometers receive the laser emitted by the semi-cylindrical shell to generate interference, and transmit the vibration information to the computer through the fiber laser control box;

[0022] Step 4: By changing the excitation and control parameters, conduct repeated experiments, obtain multiple experimental results, and compare them to find the optimal control parameters.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) The present invention proposes a complete vibration detection scheme for a truss structure supported by a semi-cylindrical shell, providing a reliable data acquisition method for modal vibration analysis of such structures.

[0025] (2) The present invention detects the multi-order modes of a semi-cylindrical shell by measuring multiple positions. Compared with the existing technology, its advantages are: it is a non-contact measurement and does not affect the dynamic performance of the object being measured; the system structure is simple and easy to operate; it can detect at multiple points, reduce experimental errors, and improve measurement accuracy.

[0026] (3) The present invention uses a method combining piezoelectric thin film detection and fiber laser vibrometer detection to detect and compare the vibration of the semi-cylindrical shell, which is beneficial to improving the detection accuracy.

[0027] (4) Fiber laser vibrometer can accurately measure the position, displacement and other changes of semi-cylindrical shells without contact, and can perform high-precision and short-distance measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a structural schematic diagram of a vibration measurement and control device with a semi-cylindrical shell structure according to the present invention;

[0029] Figure 2 yes Figure 1 The main view;

[0030] Figure 3 yes Figure 1 A top view of

[0031] Figure 4 yes Figure 1 Left view of;

[0032] Figure 5 yes Figure 1 Schematic diagram of the middle semi-cylindrical shell (thickness 2mm) with slots;

[0033] Figure 6 yes Figure 1 Schematic diagram of the middle semi-cylindrical shell (3mm thickness) with slots;

[0034] Figure 7 It is a workflow diagram of the present invention.

[0035] The figure shows: 1 - semi-cylindrical shell, 2 - support slot, 3 - flat plate, 4 - test bench, 5 - vibrometer support, 6 - fiber laser vibrometer, 7 - piezoelectric film, 8 - charge amplifier, 9 - A / D acquisition card, 10 - fiber laser control box, 11 - computer. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0037] like Figures 1-6 As shown, a vibration measurement and control device with a semi-cylindrical shell structure includes a three-layer truss structure, a vibration detection component and a control component.

[0038] The three-layer truss structure comprises three flat plates 3, with adjacent plates connected by support slots and semi-cylindrical shells. The semi-cylindrical shells 1 serve as supports, and adjacent flat plates 3 are connected by support slots 2 and the semi-cylindrical shells. The thickness of the semi-cylindrical shells in the lower layer is greater than that in the upper layer.

[0039] Specifically: three layers of flat plates, one layer of flat plates is located on the test bench 4, the first and second layers are connected to the semi-cylindrical shell 1 through support slots 2, the two support slots are located at both ends of the semi-cylindrical shell, the second and third layers are connected to the semi-cylindrical shell through support slots, and the three layers have the same structure.

[0040] The plate 3 is 400mm long, 300mm wide, and 10mm thick. The total height of the support slot is 50mm. The base is 70mm long x 70mm wide x 10mm high. The support slot is 60mm long x 60mm wide x 40mm high. The support slot has a depth of 20mm and is shaped to match the semi-cylindrical support. The semi-cylindrical shell 1 serves as a structural member, providing support and connection. Its specifications are: outer diameter 40mm, thickness 3mm or 2mm, and height 200mm. The lower layer uses a 3mm thick semi-cylindrical shell as the structural support, while the upper layer uses a 2mm thick semi-cylindrical shell as the structural support.

[0041] The material used for the semi-cylindrical shell is carbon structural steel. Carbon structural steel is primarily used in railways, bridges, and various construction projects to manufacture various metal components that withstand static loads. It is inexpensive, suitable for various support structures, and possesses high strength and flexibility. The structural features of the three-layer truss structure supported by a 3mm-thick semi-cylindrical shell are as follows: the first-layer flat plate structure is connected to four slot supports via screws, and the four semi-cylindrical shell structures are fixed to specific positions on the flat plate through the slots. The upper portion of the semi-cylindrical shell connects to another plate that already has four slot supports installed, thus supporting the second plate. Similarly, using this method, four 2mm-thick semi-cylindrical shell structures are again used, with the semi-cylindrical shell structures perpendicular to the first layer, to construct the third layer of the three-layer truss structure. Furthermore, this application allows for varying the installation orientation of the slot supports and semi-cylindrical shell structures to construct different types of three-layer structures to verify which installation method provides the best vibration resistance, stability, and suitability as a support structure. Thus, a three-layer truss structure supported by the semi-cylindrical shell is formed. The three-layer truss structure supported by the semi-cylindrical shell is then fixed on the test bench.

[0042] The vibration detection component includes a piezoelectric film and a fiber laser vibrometer. The vibration information of the semi-cylindrical shell detected by the piezoelectric film is input into the computer 11 through the charge amplifier 8 and the A / D acquisition card 9; the fiber laser controller is set on the test bench 4, and is used to detect the vibration information of the lower semi-cylindrical shell, input it into the fiber laser control box, and then input it into the computer 11.

[0043] Specifically, a piezoelectric film 7 is arranged at the center position of the outer wall of the upper and lower semi-cylindrical shells, and two piezoelectric films 7 are arranged in each semi-cylindrical shell. The piezoelectric films are arranged in the same layer of the upper and lower semi-cylindrical shells and are arranged symmetrically. The range for detection includes the entire semi-cylindrical shell structure to obtain the vibration state of the semi-cylindrical shell structure.

[0044] The fiber laser vibrometer includes a fiber head, a bracket with a spherical connector, and a fiber laser control box 10. The fiber head is mounted on the bracket, and the fiber laser control box is connected to the fiber head and to the control assembly. The fiber head of the fiber laser vibrometer is used to transmit laser light and receive laser light reflected from the outer wall of a shallow spherical shell.

[0045] Specifically, the fiber laser vibrometer is set on the test bench through the vibrometer support 5, and is set in front of the lower semi-cylindrical shell. There are four in total. The laser direction of each fiber laser vibrometer points to the center of the corresponding thin shell along the radius of the cylindrical thin shell, and is 50 to 100 mm away from the shell.

[0046] In the existing technology, piezoelectric ceramic sheets are often used as detection components. Piezoelectric ceramic sheets have fast response, wide bandwidth, and low power consumption, but they are not bendable and cannot be pasted on the curved surface of a semi-cylindrical shell. Piezoelectric films, which have a similar detection principle, have lower sensitivity but are easy to bend and can fit well with the curved surface. They can accurately reflect the vibration of the thin shell at the measuring point, and can amplify the detection signal through stacking to improve relative sensitivity.

[0047] The commonly used laser measuring instrument has no mass loading effect and high accuracy in non-contact measurement, but the laser may be scattered by the thin shell, resulting in interference errors. The present invention adopts two detection methods to avoid the defects of the laser measuring instrument.

[0048] The control assembly is connected to a vibration control mechanism, a piezoelectric film, and a fiber laser vibrometer. The vibration control mechanism is used to adjust the power of the vibration excitation device. By adjusting the input excitation voltage or current, the power input to the outer wall of the semi-cylindrical shell is adjusted to simulate different operating conditions of the semi-cylindrical shell under different conditions and obtain relevant experimental test data of the semi-cylindrical shell operating under different conditions.

[0049] In addition, the computer is connected to the fiber laser vibrometer, piezoelectric amplifier, and charge amplifier through an A / D acquisition card, and is connected to the vibration control mechanism through a D / A conversion card and an amplifier in turn. The piezoelectric amplifier is connected to the piezoelectric film. The present invention can quickly and accurately control the vibration of a semi-enclosed thin-walled shell structure.

[0050] In this embodiment, the piezoelectric film 7 is made of a high molecular multifunctional material polyvinylidene fluoride (PVDF). The piezoelectric film 7 can detect the vibration signal of the semi-cylindrical shell 1, has low production cost, is easy to form, is soft and flexible, can fit well with any position of the curved surface of the semi-cylindrical shell 1, and can adopt a stacking method to amplify the strain; in this embodiment, sixteen piezoelectric films 7 are provided, of which eight piezoelectric films 7 are pasted on the outer wall of the semi-cylindrical shell between the first and second layers of plates, and each two piezoelectric films form a group, that is, four groups of piezoelectric films 7 are pasted on the outer wall of each semi-cylindrical shell, and another eight piezoelectric films 7 are pasted on the outer wall of the semi-cylindrical shell between the second and third layers of trusses, and each two piezoelectric films form a group, and each semi-cylindrical shell is pasted in one group, that is, four groups of piezoelectric films 7 are pasted on the outer walls of the four semi-cylindrical shells, and each piezoelectric film 7 is connected in series. After detecting the vibration information, the piezoelectric film 7 transmits it to the control component.

[0051] The two piezoelectric films are symmetrically positioned to ensure that the piezoelectric force is directed in the same direction when symmetrically positioned, thus minimizing the excitation of higher-order modes. In this structure, the ends of the semi-cylindrical support column connect to a rigid body (stainless steel plate). If the piezoelectric films were attached near the base (close to the rigid body), the piezoelectric effect on the flexible body would be limited. Therefore, the two piezoelectric films were attached side by side in the center.

[0052] In this embodiment, the piezoelectric film 7 is cut from a high molecular multifunctional material polyvinylidene fluoride film, with a piezoelectric strain constant of 23×10-12C / N, a Young's modulus of 2.5Gpa, a density of 1780Kg / m3, an operating temperature of -40℃~80℃, and conductive silver glue is used to bond the wires. The cutting size of each piezoelectric film 9 is 40mm×15mm×1mm; the fiber laser vibrometer uses Sunny Optical's LV-S01-SF, with a frequency of DC~1MHz.

[0053] like Figure 7 As shown, this embodiment provides a vibration detection method for a three-layer truss structure supported by a semi-cylindrical shell. The method is implemented based on the above-mentioned device and includes the following steps:

[0054] Step 1: Turn on and initialize each device, and manually apply excitation to cause the semi-cylindrical shell 1 to generate forced vibration.

[0055] Step 2: The piezoelectric film 7 detects the strain information of the semi-cylindrical shell 1 , which is amplified by the charge amplifier 8 and then collected by the first channel of the A / D acquisition card 9 and transmitted to the computer 11 .

[0056] Step 3: The four fiber laser vibrometers 6 receive the laser light emitted by the semi-cylindrical shell 1 to generate interference, and transmit the vibration information to the computer 11 through the fiber laser control box 10 .

[0057] Step 4: By changing the excitation and control parameters, conduct repeated experiments, obtain multiple experimental results, and compare them to find the optimal control parameters.

[0058] Figure 1 The dotted lines in the middle indicate the connection relationships between the various devices.

[0059] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A vibration measurement and control device with a semi-cylindrical shell structure, characterized in that: It includes a three-layer truss structure, a vibration detection component and a control component; The three-layer truss structure includes three flat plates arranged at intervals, and adjacent flat plates are connected by support slots and semi-cylindrical shells, and the thickness of the semi-cylindrical shell located in the lower layer is greater than that of the semi-cylindrical shell located in the upper layer; The vibration detection component includes a piezoelectric film and a fiber laser vibrometer; Two piezoelectric films are attached to the outer wall of each semi-cylindrical shell to obtain the vibration state of the semi-cylindrical shell structure; The vibration detection component is provided with sixteen piezoelectric films, eight of which are pasted on the outer wall of the semi-cylindrical shell between the first and second layers of plates, and each two piezoelectric films form a group, that is, four groups of piezoelectric films are pasted on the outer walls of the four semi-cylindrical shells, and the other eight piezoelectric films are pasted on the outer wall of the semi-cylindrical shell between the second and third layers of trusses, and each two piezoelectric films form a group, and each semi-cylindrical shell is pasted with a group, that is, four groups of piezoelectric films are pasted on the outer walls of the four semi-cylindrical shells, and the piezoelectric films are connected in series. After the piezoelectric films detect vibration information, they are transmitted to the control component. The two piezoelectric films in each group are pasted side by side at the center of the semi-cylindrical shell; The laser direction of the fiber laser vibrometer is directed along the radius of the semi-cylindrical shell toward the center of the shell. Specifically, the fiber laser vibrometer is mounted on the test bench via a vibrometer support, in front of the lower semi-cylindrical shell. There are four fiber laser vibrometers in total, and the laser direction of each fiber laser vibrometer is directed along the radius of the cylindrical shell toward the center of the corresponding shell. The control component analyzes the vibration information of the piezoelectric film and the fiber laser vibrometer to obtain the deformation situation and the modal frequency of the semi-cylindrical shell.

2. The vibration measurement and control device according to claim 1, characterized in that: The control component includes a computer, a charge amplifier and an A / D acquisition card. The fiber laser vibrometer receives the laser reflected by the semi-cylindrical shell to generate interference and transmits the vibration information to the computer. The piezoelectric film detects the strain information of the semi-cylindrical shell, which is amplified by the charge amplifier and then collected by the first channel of the A / D acquisition card and transmitted to the computer.

3. The vibration measurement and control device according to claim 1, characterized in that: The fiber laser vibrometer includes a fiber head, a bracket and a fiber laser control box. The bracket is provided with a spherical connecting part. The fiber head is arranged on the bracket. The fiber laser control box is connected to the fiber head and connected to the control component.

4. The vibration measurement and control device according to claim 1, characterized in that: The outer diameter of the semi-cylindrical shell is 40 mm, the thickness of the lower semi-cylindrical shell is 3 mm, the thickness of the upper semi-cylindrical shell is 2 mm, and the height is 200 mm.

5. The vibration measurement and control device according to claim 1, characterized in that: Support slots are provided at both ends of the semi-cylindrical shell.

6. The vibration measurement and control device according to claim 1, characterized in that: The piezoelectric film has a size of 40 mm×15 mm×1 mm.

7. The vibration measurement and control device according to any one of claims 1 to 6, characterized in that: The control component is also connected to the vibration control component, which is used to adjust the power of the vibration excitation device, simulate different working states of the semi-cylindrical shell under different conditions, and control the generated vibration.

8. The vibration measurement and control device according to claim 1, characterized in that: The concave surfaces of the two layers of semi-cylindrical shells are placed 90 degrees apart.

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