Method and device for testing three-dimensional acoustic elastic model with mechanical vibration isolation system

Abstract

The invention relates to a three-dimensional acoustic elasticity model test method and device with a mechanical vibration isolation system, and relates to the technical field of ship vibration isolation system vibration and underwater three-dimensional acoustic elasticity calculation and test. By specifically considering and simulating excitation of different devices, replacement and test of different types of vibration isolators are realized, test points are arranged to completely obtain a vibration transmission path from the excitation of the devices to sound radiation, and scientific tests are carried out on the model in the air and underwater. According to the three-dimensional acoustic elasticity model test device with the mechanical vibration isolation system, a corresponding air and open water area test technology is constructed, and development, popularization and application of a calculation method are powerfully supported.

Description

Technical Field

[0001] The invention relates to the field of vibration of ship vibration isolation system and underwater three-dimensional acoustic elasticity calculation and testing technology, in particular to a three-dimensional acoustic elastic model test method and device with a mechanical vibration isolation system. Background Art

[0002] Mechanical noise is the main source of noise when the ship is stationary or cruising at low speed. How to effectively reduce the vibration and sound radiation of the mechanical system is crucial to ship noise reduction. Among the current methods of mechanical noise reduction, the use of raft vibration isolation system is the most suitable and effective vibration isolation method for large ship units, which is mainly composed of base, vibration isolator, raft and other structures. In the raft vibration isolation system, the vibration transmission path contains multiple levels of structure, and the calculation of the generated radiation noise is very complicated. Extensive research has been conducted at home and abroad on the calculation and testing of hull acoustic vibration with raft vibration isolation system. Recently, the academic community has developed a linear and nonlinear three-dimensional acoustic elastic theory and calculation method for ships with mechanical vibration isolation system, which can realize the full process of equipment excitation-raft vibration-isolator transmission-base vibration-hull vibration and sound radiation. The calculation method has been established, and the corresponding calculation software module has been developed to realize the trial of the project.

[0003] Model tests with a complete set of vibration isolation systems are an important means of verifying the correctness of calculation methods and software. For the mechanical vibration isolation system of the ship, the test model needs to specifically consider how to simulate the excitation of different equipment, how to achieve the replacement and testing of different types of vibration isolators, how to arrange the measurement points to fully obtain the vibration transmission path from equipment excitation to sound radiation, and how to conduct scientific tests on the model in the air and underwater. Designing a three-dimensional acoustic elastic model test device with a mechanical vibration isolation system and building corresponding air and open water test technologies can strongly support the development and promotion of calculation methods. Summary of the invention

[0004] In order to solve the above problems, the applicant provides a three-dimensional acoustic elastic model test method and device with a reasonable structure and a mechanical vibration isolation system.

[0005] The technical solution adopted by the present invention is as follows: A three-dimensional acoustic elastic model with a mechanical vibration isolation system comprises a shell, end plates are arranged at both ends of the shell, and a vibration isolation system is arranged inside the shell. The vibration isolation system comprises: The base is connected to the curved inner wall of the shell. The vibration isolator is set on the mounting plane formed by the top of the base. The floating raft is installed on the vibration isolator; an excitation signal output device is arranged on the floating raft, and the excitation signal output device has an excitation rod. The position of the concentrated excitation point of the vibration isolation system is adjustable.

[0006] As a further improvement of the above technical solution: It is suitable for vibration isolation tests in air and water environments. During water environment tests, the end plate and the shell form a closed test space.

[0007] A test method for a three-dimensional acoustic elastic model using a mechanical vibration isolation system, using a vibrator and a vibration motor to provide an excitation signal, and the excitation method of the model includes: The first type: the vibration machine is turned on, the vibration rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned on. The second type: the vibration machine is turned on, the vibration rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned off. The third type: the vibration machine is turned on, the vibration rod is connected to the shell at the bottom of the column shell, the concentrated excitation point acts on the shell, and the vibration motor on the raft is turned off.

[0008] As a further improvement of the above technical solution: When the model is tested in an air environment, it is divided into the stage of testing the natural frequency and vibration mode of the model and the stage of testing vibration isolation transmission. The excitation mode of the test model's natural frequency and vibration mode stage is as follows: the excitation machine is turned on, the excitation rod is connected to the bottom shell of the column shell, the concentrated excitation point acts on the bottom shell of the column shell, and the vibration motor on the floating raft is turned off. Arrange acceleration sensors and force sensors, and hang the model in the air for testing; The excitation method of the vibration isolation transmission stage of the test is as follows: the excitation machine is turned on, the excitation rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned on. Arrange acceleration sensors and force sensors, and hang the model in the air for testing.

[0009] The arrangement of the test points used in the air environment test is as follows: The accelerometers are evenly distributed in the annular section inside the shell. An acceleration sensor is arranged on the panel of the base corresponding to the vibration isolator. The vibration exciter and vibration motor of the floating raft are equipped with acceleration sensors at diagonal positions. A force sensor is arranged at the end of the exciting rod.

[0010] When the model is used in underwater environment testing, the natural frequency and vibration mode of the wet model, the vibration transmission test of the underwater mechanical vibration isolation system and the model sound radiation test are carried out. The test steps are as follows: The excitation method is as follows: the vibration machine is turned on, the excitation rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, the vibration motor on the raft is turned off, and after the acceleration sensor and force sensor are arranged, the two ends of the shell are closed. Real-time monitoring equipment is installed in the model device for watertight packaging. The model is lowered to the expected depth in the water; hydrophones are arranged in the water area to detect background noise. Before the formal test, remove the hydrophone and record the vibration acceleration and hydroacoustic data at each measuring point. After one test is completed, the model is hoisted and the excitation mode is changed as follows: the exciter is turned on, the excitation rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned on; Adjust the installation position of the vibration machine, fix the vibration rod and force sensor, ensure that the two devices excite the raft at the same time, and test again.

[0011] The measurement point arrangement for underwater testing is as follows: The acceleration sensors are evenly distributed in the circumferential section of the shell. Arrange the acceleration sensor at the vibration isolator installation position of the base panel. Arrange the acceleration sensor at the place where the floating raft is connected to the vibration isolator. An acceleration sensor is arranged diagonally opposite to the excitation signal output device on the floating raft. The accelerometer is arranged at the convex position of the floating raft. A force sensor is arranged at the end of the exciting rod.

[0012] The verification process is: first conduct a vibration test on a linear vibration isolator, then replace it with a nonlinear vibration isolator and test it again, to obtain the vibration transfer characteristics of the mechanical vibration isolation system under different vibration isolators, and compare and verify to guide the design of the nonlinear vibration isolator. In the time domain and frequency domain acoustic vibration verification methods, different signal excitations are carried out. In the time domain acoustic vibration test, under the second excitation mode, the exciter emits a short-term transient excitation signal of 1s; in the frequency domain acoustic vibration test, under the second excitation mode, the exciter emits a wide-band steady-state excitation, and the excitation signal is adjusted in real time according to the test purpose.

[0013] The beneficial effects of the present invention are as follows: The present invention provides a model test scheme with low cost and strong operability for verifying the linear and nonlinear three-dimensional acoustic elastic calculation method of ships with mechanical vibration isolation systems.

[0014] According to the method provided by the present invention, the design of the ring-ribbed cylindrical shell test model with a mechanical vibration isolation system, the selection of excitation equipment, the vibration test of the dry model in the air and the arrangement of measuring points, the acoustic vibration test of the underwater model and the arrangement of internal and external measuring points can be easily realized, thus forming a systematic and directly instructive three-dimensional acoustic elastic model test method and device for ships with a mechanical vibration isolation system as a whole.

[0015] The present invention serves the development of the three-dimensional acoustic elasticity theory and application technology of ships, provides a model test scheme and a professional test device for the assessment and verification of the corresponding calculation methods and calculation software, and plays a good supporting role in its further development and promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the closed state of the shell of the present invention.

[0017] Figure 2 It is a three-dimensional diagram of the shell structure of the present invention.

[0018] Figure 3 Built-in Figure 2 Schematic diagram of the raft structure in the shell.

[0019] Figure 4 This is the front view of the shell and raft assembly of the present invention, and the red dots in the figure are the positions of different excitation points.

[0020] Figure 5 It is a radial cross-sectional view of the shell and raft assembly of the present invention.

[0021] Figure 6 Schematic diagram of the arrangement of acceleration sensor measurement points for the model device in air.

[0022] Figure 7 Schematic diagram of the experimental state of the vibration test of the model device in air.

[0023] Figure 8 This is a schematic diagram of the cable extraction in the model, and the red lines are cables.

[0024] Fig. 9 This is a schematic diagram of the acceleration sensor measurement points on the shell when the model is underwater.

[0025] Fig.10 Schematic diagram of the acceleration sensor measurement points on the base and the raft when the model is underwater.

[0026] Fig.11 This is a schematic diagram of the underwater hydrophone measurement points and test status when the model is subjected to acoustic vibration testing underwater.

[0027] Fig.12This is a schematic diagram of the arrangement of circumferential measuring points on the floating platform when the model is subjected to underwater acoustic vibration testing.

[0028] Fig.13 It is a flowchart of the present invention.

[0029] Among them: 1. Shell; 2. End plate; 3. Base; 4. Vibration isolator; 5. Floating raft; 6. Exciter; 7. Vibration motor; 8. Exciter rod; 9. Boss; 10. Groove; 11. Pagoda head; 12. Cable; 13. Hose; 14. Gantry; 15. Floating platform. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1-Figure 13 , describing the specific implementation modes of the present invention.

[0031] A three-dimensional acoustic elastic model with a mechanical vibration isolation system comprises a shell, end plates are arranged at both ends of the shell, and a vibration isolation system is arranged inside the shell. The vibration isolation system comprises: The base is connected to the curved inner wall of the shell. The vibration isolator is set on the mounting plane formed by the top of the base. The floating raft is installed on the vibration isolator; an excitation signal output device is arranged on the floating raft, and the excitation signal output device has an excitation rod. The position of the concentrated excitation point of the vibration isolation system is adjustable.

[0032] As a further improvement of the above technical solution: It is suitable for vibration isolation tests in air and water environments. During water environment tests, the end plate and the shell form a closed test space.

[0033] A test method for a three-dimensional acoustic elastic model using a mechanical vibration isolation system, using a vibrator and a vibration motor to provide an excitation signal, and the excitation method of the model includes: The first type: the vibration machine is turned on, the vibration rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned on. The second type: the vibration machine is turned on, the vibration rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned off. The third type: the vibration machine is turned on, the vibration rod is connected to the shell at the bottom of the column shell, the concentrated excitation point acts on the shell, and the vibration motor on the raft is turned off.

[0034] As a further improvement of the above technical solution: When the model is tested in an air environment, it is divided into the stage of testing the natural frequency and vibration mode of the model and the stage of testing vibration isolation transmission. The excitation mode of the test model's natural frequency and vibration mode stage is as follows: the excitation machine is turned on, the excitation rod is connected to the bottom shell 1 of the column shell, the concentrated excitation point acts on the bottom shell 1 of the column shell, and the vibration motor on the floating raft is turned off. Arrange acceleration sensors and force sensors, and hang the model in the air for testing; The excitation method of the vibration isolation transmission stage of the test is as follows: the excitation machine is turned on, the excitation rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned on. Arrange acceleration sensors and force sensors, and hang the model in the air for testing.

[0035] The arrangement of the test points used in the air environment test is as follows: The accelerometers are evenly distributed in the annular section inside the shell. An acceleration sensor is arranged on the panel of the base corresponding to the vibration isolator. The vibration exciter and vibration motor of the floating raft are equipped with acceleration sensors at diagonal positions. A force sensor is arranged at the end of the exciting rod.

[0036] When the model is used in underwater environment testing, the natural frequency and vibration mode of the wet model, the vibration transmission test of the underwater mechanical vibration isolation system and the model sound radiation test are carried out. The test steps are as follows: The excitation method is as follows: the vibration machine is turned on, the excitation rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, the vibration motor on the raft is turned off, and after the acceleration sensor and force sensor are arranged, the two ends of the shell are closed. Real-time monitoring equipment is installed in the model device for watertight packaging. The model is lowered to the expected depth in the water; hydrophones are arranged in the water area to detect background noise. Before the formal test, remove the hydrophone and record the vibration acceleration and hydroacoustic data at each measuring point. After one test is completed, the model is hoisted and the excitation mode is changed as follows: the exciter is turned on, the excitation rod is connected to the raft boss, the concentrated excitation point acts on the middle of the boss, and the vibration motor on the raft is turned on; Adjust the installation position of the vibration machine, fix the vibration rod and force sensor, ensure that the two devices excite the raft at the same time, and test again.

[0037] The measurement point arrangement for underwater testing is as follows: The acceleration sensors are evenly distributed in the circumferential section of the shell. Arrange the acceleration sensor at the vibration isolator installation position of the base panel. Arrange the acceleration sensor at the place where the floating raft is connected to the vibration isolator. An acceleration sensor is arranged diagonally opposite to the excitation signal output device on the floating raft. The accelerometer is arranged at the convex position of the floating raft. A force sensor is arranged at the end of the exciting rod.

[0038] The verification process is: first conduct a vibration test on a linear vibration isolator, then replace it with a nonlinear vibration isolator and test it again, to obtain the vibration transfer characteristics of the mechanical vibration isolation system under different vibration isolators, and compare and verify to guide the design of the nonlinear vibration isolator. In the time domain and frequency domain acoustic vibration verification methods, different signal excitations are carried out. In the time domain acoustic vibration test, under the second excitation mode, the exciter emits a short-term transient excitation signal of 1s; in the frequency domain acoustic vibration test, under the second excitation mode, the exciter emits a wide-band steady-state excitation, and the excitation signal is adjusted in real time according to the test purpose.

[0039] The specific structure and working principle of the present invention are as follows: like Figure 1 , Figure 2 As shown, the present invention provides a ring-stiffened cylindrical shell model with a built-in mechanical vibration isolation system as a test device. Figure 4 and Figure 5 As shown, the axis of the ring-ribbed cylindrical shell model is placed horizontally, and the inner wall of the shell 1 has a circular array of T-shaped ribs. End plates 2 are sealed and installed at both ends of the shell 1. A base 3 is installed inside the shell 1. The base 3 is two coplanar platforms parallel to the axis of the shell 1. A raft 5 is connected to the base 3 through a vibration isolator 4, and an excitation device is installed on the panel of the raft 5. The excitation device includes an exciter 6 and a vibration motor 7. The exciter 6 can provide a broadband excitation signal, and the vibration motor 7 can emit a low-frequency typical line spectrum to ensure a high signal-to-noise ratio of the model, and can simulate various vibration excitations of real ship equipment.

[0040] The vibration exciter 6 is installed in a flexible manner, for example, on a spring or a buffer layer, which has an ideal high-frequency filtering effect at the installation position, and can better isolate the dynamic force transmitted to the structure by the vibration exciter 6 through the installation position, so that the excitation force is only transmitted to the structure through the vibration rod 8. The vibration motor 7 is rigidly connected with bolts to transmit the vibration directly to the floating raft 5.

[0041] The device of the present invention can be used for tests in air and underwater. When a dry model vibration test is performed in air, the end plate 2 does not need to be installed. When a model device is tested for underwater acoustic vibration, the model is installed with the end plate 2 for installing seals and counterweights. The end plates 2 on both sides are connected to the cylindrical shell flange by bolts. A sealing groove is provided on the cylindrical shell flange for arranging a rubber sealing ring to ensure watertightness.

[0042] When conducting model tests in air or underwater, the excitation methods can be summarized into the following three types: The first type: the vibration machine 6 is turned on, the vibration rod 8 is connected to the boss 9 of the floating raft 5, the concentrated excitation point acts on the middle of the boss 9, and the vibration motor 7 on the floating raft 5 is turned on. The second type: the vibration machine 6 is turned on, the vibration rod 8 is connected to the boss 9 of the floating raft 5, the concentrated excitation point acts on the middle of the boss 9, and the vibration motor 7 on the floating raft 5 is turned off. The third type: the vibration machine 6 is turned on, the vibration rod 8 is connected to the bottom end of the cylindrical shell 1, the concentrated excitation point acts on the shell 1, and the vibration motor 7 on the floating raft 5 is turned off.

[0043] The following provides a verification method for the above structure in the test of linear and nonlinear three-dimensional acoustic elastic calculation of ships.

[0044] In order to realize the acoustic vibration time domain and frequency domain verification method of linear and nonlinear vibration isolation system, the vibration isolator 4 on the base 3 first selects the linear BE rubber vibration isolator 4, and takes the installation height, load-bearing, dynamic and static stiffness, etc. of the rubber vibration isolator 4 as the design basis to design a high-static and low-dynamic quasi-zero stiffness vibration isolator 4 with strong nonlinearity.

[0045] The bottom of the floating raft 5 and the panel of the base 3 are provided with round holes matching the BE rubber isolator 4 and the nonlinear isolator 4, which serve as bolt interfaces and can connect the two isolators 4.

[0046] During the test, the vibration test of the BE rubber vibration isolator 4 is first carried out, then the bolts are removed, and the nonlinear vibration isolator 4 is replaced, and then the test is carried out. This not only provides a test installation platform for different vibration isolators 4, but also can obtain the vibration transfer characteristics of the mechanical vibration isolation system under different vibration isolators 4, and can also guide the design of nonlinear vibration isolators 4 by comparing and verifying with each other.

[0047] In the time domain and frequency domain acoustic vibration verification methods, different signal excitations are required. The time domain acoustic vibration test needs to be carried out in the second excitation mode, that is, the exciter 6 is turned on, the concentrated excitation point acts on the middle of the boss 9, and the vibration motor 7 on the floating raft 5 is turned off. The exciter 6 sends a short-term transient excitation signal of 1s; The frequency domain acoustic vibration test requires that the vibration machine 6 emits a wide-frequency steady-state excitation in the second excitation mode, and the excitation signal is adjusted in real time according to the test purpose.

[0048] Several specific test plans are described below.

[0049] Test 1: Test plan for dry model vibration test in air. Figure 6 , Figure 7 The arrangement of measuring points.

[0050] The steps for the dry model vibration test in air are: 1. Test the natural frequency and vibration mode of the model using the third excitation method, that is, the vibration machine 6 is turned on, the concentrated excitation point acts on the bottom shell 1 of the column shell, and the vibration motor 7 on the raft 5 is turned off, ensuring that only one excitation force excites the bottom shell 1, and then arrange the acceleration sensor and force sensor according to the expected measurement point requirements.

[0051] A hook is welded on the top of the model device, and the model is slowly lifted up using a crane and suspended in the air for testing.

[0052] 2. When testing the vibration transmission of the model vibration isolation system, the first excitation method is adopted, that is, the exciter 6 is turned on, the concentrated excitation point acts on the middle of the boss 9, and the vibration motor 7 is turned on. The two excitation devices simultaneously turn on the excitation raft 5, and then the acceleration sensor and force sensor are arranged according to the expected measurement point requirements. The model is slowly lifted by a crane and suspended in the air for testing.

[0053] The measurement point arrangement of the dry model vibration test in air is as follows: Figure 5 As shown, 12 acceleration sensors are evenly arranged in the middle annular section of the model device and are numbered #1 to #12 in sequence. These acceleration sensors are used to test the natural frequency and typical mode vibration shape, as well as the vibration response on the shell 1.

[0054] Near the installation positions of the four vibration isolators 4 on the panel of the base 3, four acceleration sensors are arranged, numbered #13 to #16, and these four acceleration sensors are used to obtain the vibration response transmitted by the vibration isolators 4 to the base 3; The vibration motor 7 is installed on the floating raft 5, that is, the floating raft 5 is Figure 5 The diagonal positions of the vibration motor 7 shown in the figure, for example, two acceleration sensors are arranged at the left front and right rear of the vibration motor 7, numbered #17 and #18, respectively, to obtain the vibration response at the foot of the vibration motor 7, which is regarded as the vibration input of the vibration motor 7; Two acceleration sensors, numbered #19 and #20, are also arranged at diagonal positions near the installation position of the vibration machine 6 on the floating raft 5 to obtain the vibration response at the installation position of the vibration machine 6 and detect the effectiveness of the flexible installation vibration isolation; A force sensor, numbered #21, is arranged at the connection of the end of the excitation rod 8 to obtain the excitation force provided by the exciter 6. The force sensor is determined according to the excitation position. For example, if the excitation rod 8 excites the boss 9 of the floating raft 5, the force sensor is connected to the excitation rod 8 and the boss 9; if the excitation rod 8 excites the shell 1, the force sensor is connected to the excitation rod 8 and the shell 1.

[0055] If the test is to be conducted in open water, the end plates 2 at both ends of the shell 1 need to be installed in a sealed manner. At this time, it is necessary to design how to lead out the cables 12 of the equipment in the model device.

[0056] During the open water test, a closed structure is formed inside the shell 1. Considering the opening control of the excitation device and the data transmission of the acceleration sensor, it is necessary to design the lead-out of the device cable 12.

[0057] like Figure 8 As shown, in order to ensure that the model has an outlet, a convex groove 10 is specially opened on one side of the end plate 2 for all cables 12 to pass through after being knotted. A round hole is opened at the top of the convex groove 10 to weld a pagoda head 11, which avoids the large-angle bending of the sleeve hose 13 and can be connected to the water surface more smoothly; the length of the hose 13 must exceed the diving depth of the model by at least 5m. The vertical upward pulling force on the model when it is suspended underwater is only provided by the traction rope on the lifting lug, ensuring that the hose 13 and the sleeve joint are not subjected to pulling force.

[0058] The height of the pagoda head 11 is not less than 10 cm, which can increase the length of the hose 13 sleeve and ensure the firmness of the sleeve. After the hose 13 is sleeved, a clamp and waterproof tape are used to double fix it at the sleeve to ensure that the pagoda head 11 sleeves the hose 13 with reliable water tightness, so that the cable 12 passes through the end cover convex groove 10, passes through the pagoda head 11 and can be smoothly connected to the water surface through the hose 13.

[0059] Test 2: When the model is tested for vibration and acoustic radiation underwater, the main tests are the natural frequency and vibration mode of the wet model, the vibration transmission test of the underwater mechanical vibration isolation system, and the acoustic radiation test of the model. Fig. 9 and Fig.10 .

[0060] Specifically, the second excitation method is adopted: the exciter 6 is turned on, the excitation rod 8 is connected to the boss 9 of the floating raft 5, the concentrated excitation point acts on the middle of the boss 9, and the vibration motor 7 on the floating raft 5 is turned off to ensure that only one excitation force excites the bottom shell 1 of the column shell, and then the acceleration sensor and force sensor are arranged according to the measurement point requirements. After the exciter 6 and the acceleration sensor are installed and checked to be normal, the sealing covers at both ends of the fixed model are installed.

[0061] Install cameras inside the model for real-time monitoring, and monitor the internal situation on board in real time to check if there is any water leak in the model.

[0062] After arranging and tying the cables 12 of the equipment in the model, pass them through the pagoda head 11 on the end cover, use clamps and waterproof tape to make the model watertight, wait for the water to completely solidify, and check the watertightness.

[0063] Use a rope to pass through the model's lifting ear and connect it to the lifting ring. Mark the rope at the appropriate position according to the depth of the water. Use a lifting device to lift the lifting ring and slowly lower the model into the water. When the mark is close to the water surface, stop lowering.

[0064] Hydrophones were placed in the water area to test the background noise.

[0065] The equipment is turned on, the test is carried out, and the hydrophone array is moved. The vibration acceleration and hydroacoustic data of each measuring point are recorded.

[0066] After the first working condition test is completed, the model is slowly lifted from the water and placed on the supporting stand. The end cover on the side where the pagoda head 11 is not installed is opened, and the first excitation method is adopted: the exciter 6 is turned on, the excitation rod 8 is connected to the boss 9 of the raft 5, and the concentrated excitation point acts on the middle of the boss 9. At the same time, the vibration motor 7 on the raft 5 is turned on; the installation position of the exciter 6 is adjusted, the excitation rod 8 and the force sensor are fixed to ensure that the two devices excite the raft 5 at the same time. After the installation is completed and checked to be normal, the sealing covers at both ends of the model are installed and fixed.

[0067] Repeat the above steps of putting the model into water, testing background noise, and obtaining point vibration acceleration and hydroacoustic data until all tests are completed.

[0068] During the test, the test waters, environment selection and test feasibility principles must also be considered. In the selection of the test waters, it is necessary to consider that the waters are at least 30m deep, try to avoid being close to the shore, the waters are open, the bottom of the water is relatively flat, and the surrounding environment of the waters is quiet. In the choice of test time, try to choose to carry out at night, and stagger the working hours of the surrounding environment such as dams, power plants, shipyards, and docks. In addition, summer and winter seasons should be staggered as much as possible to avoid strong winds, heavy rains, etc. causing underwater undercurrents, and avoid low temperatures causing equipment failures, hose 13 cracking, and ice on the water surface. During the test, avoid the passage of ships in the test waters, and ensure that the background noise can meet the test requirements. After the equipment is turned on, the signal-to-noise ratio is required to be greater than 6dB to ensure that the test data is reliable and not interfered with.

[0069] The internal vibration measurement points of the model underwater acoustic vibration test are arranged as follows, combined with the reference Fig.11 The arrangement of measuring points.

[0070] When performing acoustic vibration testing on the model device underwater, since there are many measuring points, they are divided into measuring points on the shell 1 and measuring points on the base 3 raft 5.

[0071] like Figure 7 As shown, 12 acceleration sensors are evenly arranged in the middle annular section of the model, numbered #1 to #12, for testing the natural frequency and modal vibration shape of the wet model, as well as the vibration response on the shell 1.

[0072] like Figure 7 As shown, four acceleration sensors, numbered #13 to #16, are arranged near the installation positions of the four vibration isolators 4 on the panel of the base 3 to obtain the vibration response transmitted to the base 3 through the vibration isolators 4, that is, the vibration response after the vibration of the vibration isolators 4 is transmitted; Four acceleration sensors, numbered #17 to #20, are arranged near the position where the lower panel of the floating raft 5 is connected to the vibration isolator 4, for obtaining the vibration response of the panel of the floating raft 5, that is, the vibration response before the vibration of the vibration isolator 4 is transmitted; Two acceleration sensors, numbered #21 and #22, are arranged near the diagonal vertices of the vibration motor 7 on the floating raft 5 to obtain the vibration response at the foot of the vibration motor 7, which is regarded as the vibration input of the vibration motor 7; Two acceleration sensors, numbered #23 and #24, are arranged near the diagonal vertices of the vibration exciter 6 on the floating raft 5 to obtain the vibration response at the installation position of the vibration exciter 6 and detect the effectiveness of the flexible installation vibration isolation; An acceleration sensor, numbered #25, is arranged near the excitation point of the boss 9 to obtain the vibration response of the excitation point of the excitation rod 8; A force sensor, numbered #26, is arranged at the connection of the end of the excitation rod 8 to obtain the excitation force provided by the exciter 6. The force sensor is determined according to the excitation position. For example, if the excitation rod 8 excites the boss 9 of the floating raft 5, the force sensor is connected to the excitation rod 8 and the boss 9; if the excitation rod 8 excites the shell 1, the force sensor is connected to the excitation rod 8 and the shell 1.

[0073] The specific arrangement of external hydrophone measurement points for the model underwater acoustic vibration test is as follows: refer to Fig.12 The open water test requires a special floating platform 15, which consists of platforms on the left and right sides and a gantry 14 between the platforms. A lifting device is installed on the gantry 14. After the model is launched into the water, a ten-element vertical acoustic array is used for testing. The acoustic array consists of 10 hydrophones connected in series with an interval of 1m.

[0074] During the test, the model device was lowered to 15m underwater, and the top hydrophone of the acoustic array was 5m away from the water surface. Fig.11 Mobile measurement is performed on the outer contour of the floating platform 15. Eight measurement points are arranged on both sides of the left and right platforms, and the distance between adjacent measurement points is 5m. Four measurement points are arranged at the head and tail ends, for a total of 24 mobile points. Fig.12 As shown. Through mobile measurement, an underwater envelope area can be formed, and the average sound pressure of the area surface can be calculated for comparison with the calculation result. The specific calculation process is not within the protection scope of the present invention. The present invention only provides a test model and a test method, so the calculation process is not described in detail.

[0075] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. A three-dimensional acoustic elastic model with a mechanical vibration isolation system, characterized in that: The invention comprises a shell (1), wherein both ends of the shell (1) are provided with end plates (2), and a vibration isolation system is provided inside the shell (1). The vibration isolation system comprises: The base (3) is connected to the arc-surface inner wall of the shell (1). The vibration isolator (4) is arranged on a mounting plane formed on the top of the base (3). The floating raft (5) is mounted on the vibration isolator (4); an excitation signal output device is arranged on the floating raft (5), and the excitation signal output device has an excitation rod (8). The position of the concentrated excitation point of the vibration isolation system is adjustable.

2. The three-dimensional acoustic elastic model with a mechanical vibration isolation system according to claim 1, characterized in that: It is suitable for vibration isolation testing in air environments and water environments. During water environment testing, the end plate (2) and the shell (1) form a closed testing space.

3. A method for testing a three-dimensional acoustic elastic model of a mechanical vibration isolation system according to claim 1, characterized in that: The excitation signal is provided by a vibration machine (6) and a vibration motor (7). The excitation mode of the model includes: The first method: the vibration machine (6) is turned on, the vibration rod (8) is connected to the boss (9) of the floating raft (5), the concentrated excitation point acts on the middle of the boss (9), and the vibration motor (7) on the floating raft (5) is turned on at the same time. The second method: the vibration machine (6) is turned on, the vibration rod (8) is connected to the boss (9) of the floating raft (5), the concentrated excitation point acts on the middle of the boss (9), and the vibration motor (7) on the floating raft (5) is turned off. The third type: the vibration machine (6) is turned on, the vibration rod (8) is connected to the shell (1) at the bottom end of the column shell, the concentrated excitation point acts on the shell (1), and the vibration motor (7) on the floating raft (5) is turned off.

4. The testing method according to claim 3, characterized in that: When the model is tested in an air environment, it is divided into the stage of testing the natural frequency and vibration mode of the model and the stage of testing vibration isolation transmission. The excitation method for the test model's natural frequency and vibration mode stage is as follows: the vibration machine (6) is turned on, the vibration rod (8) is connected to the column shell bottom end shell (1), the concentrated excitation point acts on the column shell bottom end shell (1), and the vibration motor (7) on the floating raft (5) is turned off. Arrange acceleration sensors and force sensors, and hang the model in the air for testing; The excitation method of the vibration isolation transmission stage of the test is as follows: the vibration machine (6) is turned on, the excitation rod (8) is connected to the boss (9) of the floating raft (5), the concentrated excitation point acts on the middle of the boss (9), and the vibration motor (7) on the floating raft (5) is turned on. Arrange acceleration sensors and force sensors, and hang the model in the air for testing.

5. The testing method according to claim 4, characterized in that The arrangement of the test points used in the air environment test is as follows: The accelerometers are evenly distributed in the annular cross section of the housing (1). An acceleration sensor is arranged on the panel of the base (3) at a position corresponding to the vibration isolator (4). The vibration exciter (6) and the vibration motor (7) of the floating raft (5) are respectively provided with acceleration sensors at diagonal positions. A force sensor is arranged at the end of the exciting rod (8).

6. The testing method according to claim 3, characterized in that: When the model is used in underwater environment testing, the natural frequency and vibration mode of the wet model, the vibration transmission test of the underwater mechanical vibration isolation system and the model sound radiation test are carried out. The test steps are as follows: The excitation method is as follows: the vibration machine (6) is turned on, the excitation rod (8) is connected to the boss (9) of the floating raft (5), the concentrated excitation point acts on the middle of the boss (9), the vibration motor (7) on the floating raft (5) is turned off, and after the acceleration sensor and the force sensor are arranged, the two ends of the shell (1) are closed. Real-time monitoring equipment is installed in the model device for watertight packaging. The model is lowered to the expected depth in the water; hydrophones are arranged in the water area to detect background noise. Before the formal test, remove the hydrophone and record the vibration acceleration and hydroacoustic data at each measuring point. After one test is completed, the model is hoisted and the excitation mode is changed as follows: the vibration machine (6) is turned on, the excitation rod (8) is connected to the boss (9) of the floating raft (5), the concentrated excitation point acts on the middle of the boss (9), and the vibration motor (7) on the floating raft (5) is turned on at the same time; The installation position of the vibration machine (6) is adjusted, the vibration rod (8) and the force sensor are fixed, and the two devices are ensured to simultaneously excite the floating raft (5), and the test is repeated.

7. The testing method according to claim 6, characterized in that: The measurement point arrangement for underwater testing is as follows: Acceleration sensors are uniformly distributed in the annular cross section of the housing (1). An acceleration sensor is arranged at the mounting position of the vibration isolator (4) on the panel of the base (3). An acceleration sensor is arranged at the place where the floating raft (5) is connected to the vibration isolator (4). An acceleration sensor is arranged at a diagonal position of the excitation signal output device on the floating raft (5). An acceleration sensor is arranged at the boss (9) of the floating raft (5). A force sensor is arranged at the end of the exciting rod (8).

8. The testing method according to claim 3, characterized in that: The verification process is as follows: firstly, a vibration test of the linear vibration isolator (4) is carried out, and then a nonlinear vibration isolator (4) is installed for further testing, so as to obtain the vibration transfer characteristics of the mechanical vibration isolation system under different vibration isolators (4), and the comparison and verification guide the design of the nonlinear vibration isolator (4). In the time domain and frequency domain acoustic vibration verification methods, different signal excitations are performed. In the time domain acoustic vibration test, under the second excitation mode, the exciter (6) emits a short-term transient excitation signal of 1 s; in the frequency domain acoustic vibration test, under the second excitation mode, the exciter (6) emits a wide-band steady-state excitation, and the excitation signal is adjusted in real time according to the test purpose.

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