Testing platform and testing method for dynamic stiffness and dynamic damping of ship water lubricated bearing

Abstract

The invention relates to the technical field of ship water lubricated shaft testing, in particular to a dynamic stiffness and dynamic damping testing platform and method for a ship large-length-diameter-ratio water lubricated bearing in an unbalance loading operation state. Through cooperation of the rotor-bearing system, the driving system, the loading system, the lubrication system and the test system, different radial specific pressures can be flexibly and conveniently applied to two sides of the water-lubricated bearing so as to simulate various unbalanced motion working conditions of the rotor-bearing system, and the test platform is simple to operate, small in installation error, high in measurement precision and high in reliability. The dynamic characteristics of the water lubricated bearing can be accurately identified; the dynamic equation of the bearing system and the mechanical model of the bearing connecting part are established, the displacement impedance method is combined, the comprehensive rigidity coefficient and the damping coefficient of the liquid film and the structure of the water lubricated bearing can be accurately measured, and the testing method is short in calculation time, high in measurement efficiency and wide in application range.

Description

Technical Field

[0001] The present invention relates to the technical field of ship water-lubricated shaft testing, and in particular to a testing platform and a testing method for dynamic stiffness and dynamic damping of a ship large aspect ratio water-lubricated bearing under an eccentric load operation state. Background Art

[0002] In the ship power system, the propulsion shaft system is mainly used to transmit the main engine power and propeller thrust, and is a key component to ensure the normal operation of the ship. As a key element for transmitting vibration energy between the propeller-shaft system-main engine-hull, the dynamic characteristics of the water-lubricated stern bearing affect the dynamic behavior of the propulsion shaft system and are directly related to the quality of the propulsion system operation. However, for the ship's stern bearing under low-speed and heavy-load conditions, the inclined tail shaft has already had friction contact with one end of the stern bearing, and the microscopic roughness peak contact has been transformed into a macroscopic surface contact. This idea transforms the microscopic roughness mixed lubrication problem into a macroscopic regional mixed lubrication problem. With the increasing demand for rotor dynamics research, the traditional method of testing the dynamic characteristics of bearings can no longer meet the accuracy requirements of complex service environments.

[0003] In order to improve the accuracy of dynamic characteristics identification of ship water-lubricated bearings, a method for identifying the dynamic characteristics coefficients of local contact water-lubricated bearings is proposed. The reason is that the random model is used in the mixed lubrication analysis of bearings, and fewer statistical parameters are used to describe the characteristics of the rough surface. With the development of computer technology and numerical calculation methods, deterministic models have become the main direction of mixed lubrication research and have made great progress. Deterministic models refer to the use of numerical methods to characterize the dynamic performance of bearing systems. Therefore, accurate identification of bearing dynamic characteristics parameters can effectively analyze the stability and reliability of the entire ship shaft system, thereby accurately describing the actual operation of the bearing. In the actual service process of the shaft system, there is always a mixed lubrication of dry friction lubrication, boundary lubrication and film lubrication at the interface of the water-lubricated bearing. At this time, the dynamic characteristics of the water-lubricated bearing are very complex and are affected by factors such as squeezed water film, lining performance and contact conditions. It is difficult for traditional water-lubricated bearing test benches to simulate this mixed lubrication state, resulting in difficulty in accurately identifying the dynamic characteristics test of the bearing system.

[0004] In order to accurately obtain the dynamic stiffness of the bearing, the existing technology generally adopts indirect testing, and the indirect conversion method is closely related to the accuracy of the indirect parameters and the rationality of the conversion method. Therefore, it is key to study the high-precision testing technology of the dynamic stiffness and dynamic damping of the shaft system. In addition, there are interference factors such as processing and installation errors and measurement environment during the test. How to analyze and reduce these errors and improve measurement accuracy is also one of the main considerations during the test. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a test platform and method for the dynamic stiffness and dynamic damping of ship water-lubricated bearings, which can accurately measure the dynamic stiffness and dynamic damping of ship water-lubricated bearings with large aspect ratio under eccentric load operation, and has simple operation and short calculation time. It can simulate various bearing system uncoordinated motion conditions and realize accurate identification of the dynamic characteristics of water-lubricated bearings.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] 1. A test platform for dynamic stiffness and dynamic damping of ship water-lubricated bearings

[0008] The present invention provides a test platform for dynamic stiffness and dynamic damping of a ship water-lubricated bearing, which mainly comprises: a rotor-bearing system, a drive system, a loading system, a lubrication system and a test system;

[0009] The rotor-bearing system comprises a water-lubricated bearing 10 to be tested and a rotating shaft 2, wherein the rotating shaft 2 on both sides of the water-lubricated bearing 10 is supported and mounted on a first support bearing 3 and a second support bearing 18 respectively;

[0010] The drive system comprises a variable frequency motor 1, which is connected to a rotating shaft 2 via an elastic coupling to drive the rotating shaft 2 to rotate;

[0011] The loading system includes a first hydraulic loader 5 and a second hydraulic loader 9 respectively mounted on the first support bearing 3 and the second support bearing 18, the first hydraulic loader 5 and the second hydraulic loader 9 are both connected to the hydraulic cylinder, and the tops are fixedly mounted by a gantry;

[0012] The lubrication system comprises a circulating water tank 7 and a circulating water pump, wherein the circulating water tank 7 is connected to the lubricating medium inlet and the lubricating medium outlet of the water-lubricated bearing 10 through a water inlet pipe 8 and a water return pipe 6 respectively;

[0013] The test system includes a numerical sensing module, a data acquisition module and a data processing module. The numerical sensing module collects physical signals of the rotor-bearing system in real time and converts them into electrical signals and transmits them to the data acquisition module. The data acquisition module synchronously collects data of each electrical signal and transmits them to the data processing module for processing and calculation to identify the dynamic characteristic coefficient of the water-lubricated bearing to be tested.

[0014] Furthermore, the numerical sensing module includes a first force sensor 4, a second force sensor 17, a first eddy current sensor 11, a second eddy current sensor 12, a third eddy current sensor 13, and a fourth eddy current sensor 14; the data acquisition module includes a data acquisition card 15, and the data processing module includes a data analyzer 16.

[0015] Further, the first force sensor 4 is provided at the contact point between the first hydraulic loader 5 and the first support bearing 3, and the second force sensor 17 is provided at the contact point between the second hydraulic loader 9 and the second support bearing 18;

[0016] The first force sensor 4 and the second force sensor 17 are respectively installed at the bottom of the loading ends of the first hydraulic loader 5 and the second hydraulic loader 9 through threaded connection.

[0017] Furthermore, the first eddy current sensor 11 and the second eddy current sensor 12 are installed at the left end of the water-lubricated bearing 10 and are arranged radially at a distance of 90°;

[0018] The third eddy current sensor 13 and the fourth eddy current sensor 14 are installed at the right end of the water-lubricated bearing 10 and are arranged radially at a distance of 90°.

[0019] Furthermore, the first force sensor 4 , the second force sensor 17 , the first eddy current sensor 11 , the second eddy current sensor 12 , the third eddy current sensor 13 , and the fourth eddy current sensor 14 are all connected to the data acquisition card 15 via signal lines, and the data acquisition card 15 is directly connected to the data analyzer 16 .

[0020] Furthermore, the first hydraulic loader 5 and the second hydraulic loader 9 apply a preset radial specific pressure to both sides of the rotating shaft 2 through the first support bearing 3 and the second support bearing 18 respectively, so as to simulate the unbalanced motion condition of the rotor-bearing system.

[0021] 2. A test method for dynamic stiffness and dynamic damping of ship water-lubricated bearings

[0022] Based on the same inventive concept, the present invention also provides a method for testing the dynamic stiffness and dynamic damping of a ship water-lubricated bearing, based on the test platform as described above, specifically comprising the following steps:

[0023] S1, start the lubrication system and set the lubrication medium flow rate, start the drive system and set the motor speed, start the loading system, read the specific pressure of the rotating shafts on both sides of the water-lubricated bearing through the first force sensor and the second force sensor respectively, and wait for the specific pressure value to stabilize;

[0024] S2, establishing a bearing system model, simplifying the bearing system to obtain the dynamic equation of the bearing system;

[0025] S3, establishing a mechanical model of the bearing connection part, and connecting a butterfly spring with a preset stiffness in series between the force sensor and the hydraulic loader in the model to offset the interference effect of the bearing connection part;

[0026] S4, solve the bearing dynamic characteristic coefficient, and obtain the total force on the shaft by superimposing the dynamic forces measured by the force sensors at both ends of the water-lubricated bearing; and measure two vibration signals through eddy current sensors set at both ends of the water-lubricated bearing, and use the displacement impedance method to identify the dynamic characteristic coefficient of the water-lubricated bearing to be tested.

[0027] Furthermore, the dynamic equation of the bearing system is as follows:

[0028]

[0029] Where: F d is the exciting force applied by the loading system; m1 is the mass of the shaft; Y d k is the displacement amplitude of the shaft relative to the water-lubricated bearing; b and c b are the comprehensive stiffness coefficient and damping coefficient of the water-lubricated bearing fluid film and structure respectively; k0 is the connection stiffness of the shaft.

[0030] Furthermore, the mechanical model of the bearing connection part is as follows:

[0031]

[0032] Where m is the mass of the hydraulic loader, support bearing and force sensor, k is y is the hydraulic oil stiffness, k g is the transition stiffness between the hydraulic rod and the rotating shaft.

[0033] Furthermore, solving the bearing dynamic characteristic coefficient specifically includes:

[0034] The two vibration signals measured by the eddy current sensors at both ends of the water-lubricated bearing and After vector synthesis, the shaft displacement amplitude Y at the axial midpoint of the water-lubricated bearing is obtained. d and Phase

[0035]

[0036] Assume that the initial phase angle of the loading force is Then the exciting force F d and displacement amplitude Y d The solution equation is:

[0037]

[0038] The displacement impedance method is used to identify the dynamic characteristic coefficient of the water-lubricated bearing to be tested. The displacement impedance is:

[0039]

[0040] Solve for the dynamic characteristic coefficients of water-lubricated bearings:

[0041]

[0042] In the formula, k b and c b They are the comprehensive stiffness coefficient and damping coefficient of the water-lubricated bearing fluid film and structure respectively.

[0043] Compared with the prior art, the present invention has the following main advantages:

[0044] 1. The present invention builds a test platform for the dynamic stiffness and dynamic damping of water-lubricated bearings under eccentric load operation. By cooperating with the rotor-bearing system, the drive system, the loading system, the lubrication system and the test system, different radial pressure ratios can be flexibly and conveniently applied on both sides of the water-lubricated bearing to simulate various unbalanced motion conditions of the rotor-bearing system. The test platform is simple to operate, has a small installation error and high measurement accuracy, and can realize accurate identification of the dynamic characteristics of the water-lubricated bearing.

[0045] 2. The present invention proposes a test method for the dynamic stiffness and dynamic damping of a water-lubricated bearing with a large aspect ratio. By establishing the dynamic equation of the bearing system and the mechanical model of the bearing connection part, combined with the displacement impedance method, the comprehensive stiffness coefficient and damping coefficient of the water-lubricated bearing fluid film and structure can be accurately measured. The test method has short calculation time, high measurement efficiency, and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of a test platform for dynamic stiffness and dynamic damping of a ship water-lubricated bearing according to an embodiment of the present invention;

[0047] Figure 2 A schematic diagram of a test system in an embodiment of the present invention;

[0048] Figure 3 A simplified mechanical model of a bearing system in an embodiment of the present invention;

[0049] Figure 4 A simplified mechanical model of the connection part of the bearing system in the embodiment of the present invention;

[0050] Figure 5 The figure is a flow chart of a method for testing dynamic stiffness and dynamic damping of a ship water-lubricated bearing in an embodiment of the present invention.

[0051] In the figure: 1-frequency conversion motor; 2-rotating shaft; 3-first support bearing; 4-first force sensor; 5-first hydraulic loader; 6-return pipe; 7-circulating water tank; 8-water inlet pipe; 9-second hydraulic loader; 10-water-lubricated bearing; 11-first eddy current sensor; 12-second eddy current sensor; 13-third eddy current sensor; 14-fourth eddy current sensor; 15-data acquisition card; 16-data analyzer; 17-second force sensor; 18-second support bearing. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0053] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0054] Embodiment 1: This embodiment provides a test platform for dynamic stiffness and dynamic damping of ship water-lubricated bearings. Figures 1-2 As shown, it is mainly composed of a variable frequency motor 1, a rotating shaft 2, a first support bearing 3, a first force sensor 4, a first hydraulic loader 5, a return pipe 6, a circulating water tank 7, a water inlet pipe 8, a second hydraulic loader 9, a water-lubricated bearing 10, a second force sensor 17, a second support bearing 18, etc.

[0055] The first hydraulic loader 5 and the second hydraulic loader 9 cooperate to apply different radial pressure ratios to the rotating shaft 2 to simulate the unbalanced motion of the rotor system. A loading probe is provided below the hydraulic loading device for connecting the support bearing.

[0056] like Figure 2 As shown, the test system consists of a first eddy current sensor 11, a second eddy current sensor 12, a third eddy current sensor 13, a fourth eddy current sensor 14, a data acquisition card 15, and a data analyzer 16. Each sensor converts a physical signal into an electrical signal and transmits it to the data acquisition card 15. The data acquisition card 15 synchronously collects data of each signal, and the data analyzer 16 processes and identifies the dynamic characteristic coefficient of the bearing.

[0057] Among them, the first force sensor 4 is connected to the bottom thread of the first hydraulic loader 5 through the processed thread, the second force sensor 9 is connected to the bottom thread of the second hydraulic loader 9 through the processed thread, the first eddy current sensor 11 and the second eddy current sensor 12 are located at the left end of the water-lubricated bearing 10 and are arranged radially at 90°, the third eddy current sensor 13 and the fourth eddy current sensor 14 are located at the right end of the water-lubricated bearing 10 and are arranged radially at 90°, all signals are connected to the data acquisition card 15, and the data acquisition 15 is directly connected to the data analyzer 16.

[0058] like Figure 3 The figure shows a simplified mechanical model of the shaft system, where Fd is the self-excitation force; m1 is the mass of the rotating shaft 2; Yd is the displacement of the shaft relative to the bearing hole; kb and cb are the combined stiffness and damping coefficient of the bearing fluid film and structure; and k0 is the connection stiffness of the rotating shaft 2.

[0059] like Figure 4 The figure shows a simplified mechanical model of the connection part of the bearing system, where m0 is the parametric mass, including the loading rod, rolling bearing and force sensor, etc.; ky is the hydraulic oil stiffness, and kg is the transition stiffness between the hydraulic rod and the rotating shaft 2.

[0060] Embodiment 2, based on the same inventive concept, this embodiment also provides a method for testing the dynamic stiffness and dynamic damping of a ship water-lubricated bearing. Based on the test platform described above, the dynamic characteristic coefficient is solved by collecting the excitation force and displacement of the shaft system, such as Figure 5 As shown, the specific steps include:

[0061] S1, start the lubrication system and set the flow rate; start the drive system, set the speed and wait for stabilization; start the loading system, read different pressure ratios through the first force sensor 4 and the second force sensor 9, and wait for the pressure ratio value to stabilize.

[0062] S2, establish the bearing system model, simplify the bearing system to obtain the mechanical model as follows Figure 3 , its dynamic equation:

[0063]

[0064] Where: F d is the self-excitation force; m1 is the mass of the shaft; Y d k is the displacement of the shaft relative to the bearing hole; b and c b is the combined stiffness and damping coefficient of the bearing fluid film and structure; k0 is the connection stiffness of the shaft. b In parallel, when k0 is less than 10% of k b , can be ignored.

[0065] S3, establish the mechanical model of the bearing connection part, Figure 4 is the mechanical model of the connection part, where m0 is the parametric mass, including the loading rod, rolling bearing and force sensor, etc.; k y is the hydraulic oil stiffness, k g is the transition stiffness between the hydraulic rod and the shaft. The following relationship can be established:

[0066]

[0067] From the above formula, we can see that by reducing k g To achieve the purpose of reducing k0. By connecting a small stiffness butterfly spring in series between the force sensor and the hydraulic rod to reduce k0, k0Y can be ignored. d Item, and then perform Fourier transform on the simplified formula to get the test equation:

[0068] (k b -m1ω 2 +jωc b )Y d (ω)=F d (ω)

[0069] S4, solve the bearing dynamic characteristic coefficient, and the dynamic forces tested by the force sensors at both ends of the bearing are superimposed to obtain the total force on the shaft; an eddy current sensor is set at each end of the bearing in the vertical direction, and the two vibration signals measured are and After vector synthesis, the displacement amplitude and phase of the shaft at the axial midpoint of the bearing are obtained:

[0070]

[0071] Assume that the initial phase angle of the force is Then the exciting force and displacement are:

[0072]

[0073] The displacement impedance method is used to identify the dynamic characteristic coefficient of the measured system. The displacement impedance is:

[0074]

[0075] Solve for the dynamic coefficients of the bearing system:

[0076]

[0077] It should be pointed out that due to the installation eccentricity of the rotor and the coupling, as well as some weak nonlinear factors, there must be high-order harmonics and subharmonic components in the signal that are not synchronized with the rotor unbalance excitation frequency. However, only the fundamental wave information corresponding to the test equation can be extracted during signal processing. The required dynamic force and displacement can be obtained through fundamental wave detection and tracking.

[0078] Embodiment 3: This embodiment provides a method for testing the dynamic stiffness and dynamic damping of a ship water-lubricated bearing, which mainly includes:

[0079] (1) Separate the excitation source. At the test speed, the hydraulic loading device loads the rotor system through the rolling bearing. The force sensor installed between the hydraulic loading system and the rolling bearing will measure the superposition force of the static force and the dynamic force. The dynamic force separated from it is the rotor self-excitation force.

[0080] (2) Establish a bearing system model and simplify the bearing system to obtain the dynamic equation;

[0081] (3) A mechanical model of the bearing connection part is established, and the interference effect of the bearing connection part is reduced by connecting a small stiffness butterfly spring in series between the force sensor and the hydraulic rod;

[0082] (4) Solve the dynamic characteristic coefficient of the bearing and obtain the total force on the shaft by superimposing the dynamic forces measured by the force sensors at both ends of the bearing. An eddy current sensor is set in the vertical direction at each end of the bearing, and the two vibration signals are measured, and the displacement impedance method is used to identify the dynamic characteristic coefficient of the system under test.

[0083] According to the above scheme, the test parameters include speed and specific pressure. Each specific specific pressure has multiple speeds, and data must be collected after the rotor system runs stably for each working condition.

[0084] According to the above scheme, due to the installation eccentricity of the rotor and the coupling, as well as some weak nonlinear factors, there must be high-order harmonics and sub-harmonic components in the signal that are asynchronous with the rotor unbalance excitation frequency. However, only the fundamental wave information corresponding to the test equation can be extracted during signal processing. The required dynamic force and displacement can be obtained through fundamental wave detection and tracking.

[0085] On the other hand, this example provides a test bench for testing the dynamic stiffness and dynamic damping of a ship's large aspect ratio water-lubricated bearing under an eccentric load operation state, including: a rotor-bearing system, a lubrication system, a drive system, a loading system and a test system.

[0086] Among them, the driving system uses a motor to adjust the rotation speed and drives the entire shaft system to rotate through an elastic coupling; the rotor-bearing system includes a test bearing and a rotating shaft; the hydraulic loading system fixes the hydraulic loading device through a gantry, and adjusts the output loading force by connecting a hydraulic cylinder, so as to apply different radial pressure ratios to the test bearing; the lubrication system includes components such as a water tank, a water pump and pipelines, which provide circulating cooling water for the test bearing to take away heat and provide water as a lubricating medium, and the lubricating water enters from the bottom of the bearing and exits from the top; the test system includes a numerical perception module, a data acquisition module and a data processing module, wherein the data perception module converts physical signals into electrical signals through sensors and transmits them to the data acquisition module, the data acquisition module synchronously collects data of each signal, and the data processing module accurately identifies the dynamic characteristic coefficient of the bearing.

[0087] According to the above scheme, a hydraulic loading device is arranged on each side of the bearing, and the loading force acts on the rotating shaft through the rolling bearing to apply radial specific pressure, and a force sensor is arranged on the top of the loading rod.

[0088] According to the above scheme, the test system includes a force sensor, an eddy current sensor, a data acquisition card and dynamic characteristic identification software. The eddy current sensors are located at both ends of the test bearing and arranged radially at 90°. The data acquisition module is directly connected to the data analysis module.

[0089] According to the above scheme, the hydraulic loading system applies an eccentric load to simulate the unbalanced motion of the rotor by adjusting the pressure ratio on both sides.

[0090] Furthermore, all parts of the present application that are not described in detail are the same as the prior art or are implemented using the prior art.

[0091] In summary:

[0092] 1. The present invention builds a test platform for the dynamic stiffness and dynamic damping of water-lubricated bearings under eccentric load operation. By cooperating with the rotor-bearing system, the drive system, the loading system, the lubrication system and the test system, different radial pressure ratios can be flexibly and conveniently applied on both sides of the water-lubricated bearing to simulate various unbalanced motion conditions of the rotor-bearing system. The test platform is simple to operate, has a small installation error and high measurement accuracy, and can realize accurate identification of the dynamic characteristics of the water-lubricated bearing.

[0093] 2. The present invention proposes a test method for the dynamic stiffness and dynamic damping of a water-lubricated bearing with a large aspect ratio. By establishing the dynamic equation of the bearing system and the mechanical model of the bearing connection part, combined with the displacement impedance method, the comprehensive stiffness coefficient and damping coefficient of the water-lubricated bearing fluid film and structure can be accurately measured. The test method has short calculation time, high measurement efficiency, and a wide range of applications.

[0094] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A test platform for dynamic stiffness and dynamic damping of ship water-lubricated bearings, characterized by: Includes rotor-bearing system, drive system, loading system, lubrication system and testing system; The rotor-bearing system comprises a water-lubricated bearing (10) to be tested and a rotating shaft (2), wherein the rotating shaft (2) on both sides of the water-lubricated bearing (10) is supported and mounted on a first support bearing (3) and a second support bearing (18) respectively; The drive system comprises a variable frequency motor (1), wherein the variable frequency motor (1) is connected to a rotating shaft (2) via an elastic coupling to drive the rotating shaft (2) to rotate; The loading system comprises a first hydraulic loader (5) and a second hydraulic loader (9) respectively mounted on the first support bearing (3) and the second support bearing (18); the first hydraulic loader (5) and the second hydraulic loader (9) are both connected to a hydraulic cylinder and are fixedly mounted on the top via a gantry; The lubrication system comprises a circulating water tank (7) and a circulating water pump, wherein the circulating water tank (7) is connected to a lubrication medium inlet and a lubrication medium outlet of a water-lubricated bearing (10) via a water inlet pipe (8) and a water return pipe (6) respectively; The test system includes a numerical sensing module, a data acquisition module and a data processing module. The numerical sensing module collects physical signals of the rotor-bearing system in real time and converts them into electrical signals and transmits them to the data acquisition module. The data acquisition module synchronously collects data of each electrical signal and transmits them to the data processing module for processing and calculation to identify the dynamic characteristic coefficient of the water-lubricated bearing to be tested.

2. A ship water-lubricated bearing dynamic stiffness and dynamic damping test platform according to claim 1, characterized in that: The numerical sensing module comprises a first force sensor (4), a second force sensor (17), a first eddy current sensor (11), a second eddy current sensor (12), a third eddy current sensor (13), and a fourth eddy current sensor (14); the data acquisition module comprises a data acquisition card (15), and the data processing module comprises a data analyzer (16).

3. A ship water-lubricated bearing dynamic stiffness and dynamic damping test platform according to claim 2, characterized in that: The first force sensor (4) is arranged at a contact point between the first hydraulic loader (5) and the first support bearing (3), and the second force sensor (17) is arranged at a contact point between the second hydraulic loader (9) and the second support bearing (18); The first force sensor (4) and the second force sensor (17) are respectively installed at the bottom of the loading end of the first hydraulic loader (5) and the second hydraulic loader (9) through threaded connection.

4. A ship water-lubricated bearing dynamic stiffness and dynamic damping test platform according to claim 3, characterized in that: The first eddy current sensor (11) and the second eddy current sensor (12) are installed at the left end of the water-lubricated bearing (10) and are arranged radially at a distance of 90°; The third eddy current sensor (13) and the fourth eddy current sensor (14) are installed on the right side end of the water-lubricated bearing (10) and are arranged radially at an angle of 90 degrees.

5. A ship water-lubricated bearing dynamic stiffness and dynamic damping test platform according to claim 4, characterized in that: The first force sensor (4), the second force sensor (17), the first eddy current sensor (11), the second eddy current sensor (12), the third eddy current sensor (13), and the fourth eddy current sensor (14) are all connected to the data acquisition card (15) via signal lines, and the data acquisition card (15) is directly connected to the data analyzer (16).

6. A ship water-lubricated bearing dynamic stiffness and dynamic damping test platform according to claim 1, characterized in that: The first hydraulic loader (5) and the second hydraulic loader (9) apply a preset radial specific pressure to both sides of the rotating shaft (2) through the first support bearing (3) and the second support bearing (18) respectively, so as to simulate the unbalanced motion condition of the rotor-bearing system.

7. A method for testing dynamic stiffness and dynamic damping of a ship water-lubricated bearing, based on the test platform according to any one of claims 1 to 6, characterized in that: The steps include: S1, start the lubrication system and set the lubrication medium flow rate, start the drive system and set the motor speed, start the loading system, read the specific pressure of the rotating shafts on both sides of the water-lubricated bearing through the first force sensor and the second force sensor respectively, and wait for the specific pressure value to stabilize; S2, establishing a bearing system model, simplifying the bearing system to obtain the dynamic equation of the bearing system; S3, establishing a mechanical model of the bearing connection part, and connecting a butterfly spring with a preset stiffness in series between the force sensor and the hydraulic loader in the model to offset the interference effect of the bearing connection part; S4, solve the bearing dynamic characteristic coefficient, and obtain the total force on the shaft by superimposing the dynamic forces measured by the force sensors at both ends of the water-lubricated bearing; and measure two vibration signals through eddy current sensors set at both ends of the water-lubricated bearing, and use the displacement impedance method to identify the dynamic characteristic coefficient of the water-lubricated bearing to be tested.

8. The testing method according to claim 7, characterized in that: The dynamic equation of the bearing system is as follows: Where: F d is the exciting force applied by the loading system; m1 is the mass of the shaft; Y d k is the displacement amplitude of the shaft relative to the water-lubricated bearing; b and c b are the comprehensive stiffness coefficient and damping coefficient of the water-lubricated bearing fluid film and structure respectively; k0 is the connection stiffness of the shaft.

9. The testing method according to claim 8, characterized in that: The mechanical model of the bearing connection part is as follows: Where m is the mass of the hydraulic loader, support bearing and force sensor, k is y is the hydraulic oil stiffness, k g is the transition stiffness between the hydraulic rod and the rotating shaft.

10. The testing method according to claim 9, characterized in that: The solution of the bearing dynamic characteristic coefficient specifically includes: The two vibration signals measured by the eddy current sensors at both ends of the water-lubricated bearing and After vector synthesis, the shaft displacement amplitude Y at the axial midpoint of the water-lubricated bearing is obtained. d and Phase Assume that the initial phase angle of the loading force is Then the exciting force F d and displacement amplitude Y d The solution equation is: The displacement impedance method is used to identify the dynamic characteristic coefficient of the water-lubricated bearing to be tested. The displacement impedance is: Solve for the dynamic characteristic coefficients of water-lubricated bearings: In the formula, k b and c b They are the comprehensive stiffness coefficient and damping coefficient of the water-lubricated bearing fluid film and structure respectively.

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