An improved method for regulating the dynamic characteristics of multi-axis sections of water-lubricated bearings based on carbon fiber layup

Abstract

The present invention belongs to the technical field of water-lubricated bearings, and discloses an improved method for regulating the dynamic characteristics of multi-axis segments of water-lubricated bearings based on carbon fiber layup. A mathematical model of the equivalent support stiffness of the water-lubricated bearing is constructed based on the multi-field coupling theory, which covers the parallel coupling mechanism of the fluid water film stiffness and the bearing micro-convex body contact stiffness. Based on the equivalent support stiffness model, the distribution of the load spectrum of the multi-axis segments of the water-lubricated bearing is determined by the multi-field coupling pressure field integration algorithm, and the mapping relationship between the distribution of the load spectrum of the multi-axis segments of the water-lubricated bearing and the dynamic characteristics of the multi-axis segments is analyzed. Furthermore, with the target stiffness of the multi-axis segments as the constraint condition, based on the meso-mechanical constitutive equation of the carbon fiber and matrix composite water-lubricated bearing material, the volume fraction, layup direction and layup sequence of the carbon fiber in the composite water-lubricated bearing material are optimized to achieve the gradient regulation of the dynamic performance and the stability optimization of the water-lubricated bearing system.

Description

Technical Field

[0001] The present invention belongs to the technical field of water-lubricated bearings, and particularly relates to an improved method for precisely adjusting the dynamic characteristics of multi-axis segments of a water-lubricated bearing through the ply design of a carbon fiber composite material. Background Art

[0002] Water-lubricated bearings are bearings that use water as the lubricating medium. Due to their characteristics such as low friction, environmental friendliness, resource conservation, and ease of maintenance, they are widely used in ship propulsion systems, power generation equipment, and ocean engineering. However, with the in-depth development of the green concept, their lubrication, vibration reduction, and wear resistance performance face higher requirements and challenges. The key to achieving low friction characteristics of water-lubricated bearings lies in the formation and stability of the lubricating water film, and the dynamic performance of water-lubricated bearings is the core factor to ensure the high strength and high stability of the lubricating water film. Currently, the mainstream methods for improving the dynamic characteristics of water-lubricated bearings include the development and design of high-performance water-lubricated bearing materials, the optimization of bearing structure parameters, and surface micro-texture design. Among them, carbon fiber and its reinforced composites are applied to the cross-research field of green lubrication technology and high-performance composite material applications due to their excellent properties such as light weight and high strength.

[0003] When designing the requirements for the dynamic characteristics of water-lubricated bearings, simulation calculations are usually used to determine the equivalent support stiffness parameters of the overall structure of the water-lubricated bearing. Existing simulation calculations are usually based on assumptions such as unidirectional tilt or vertical deflection of the journal, and deterministic models such as hydrodynamic lubrication models, elastohydrodynamic lubrication models, and mixed lubrication models are selected. The finite element method, difference method, and perturbation pressure method are used to solve the equivalent support stiffness of the overall structure of the bearing, and then the dynamic performance of the overall structure of the bearing is evaluated.

[0004] However, as an important support component for water surface ships and underwater vehicles to carry propellers and tail shafts, water-lubricated bearings are often in low-speed and heavy-load working conditions, resulting in a mixed lubrication state where the bearing lubrication interface coexists with dry friction, boundary lubrication, and fluid lubrication. As a result, when analyzing the dynamics of water-lubricated bearings, they are affected by the coupled effects of multiple factors such as the viscoelastic deformation of the bearing bush, micro-convex contact, the cantilever effect of the propeller, and the deformation of the hull. Furthermore, the spatial form of the shaft is not simply equivalent to unidirectional tilt or bending, but a complex and uncertain spatial form. Due to the complex spatial form, the forces on different shaft segments of the bearing are significantly different, forming a zoned lubrication state. As a result, the requirements for the take-off speed and dynamic performance of different shaft segments also vary, making it difficult for the equivalent support stiffness parameters solved based on the overall structure to meet the dynamic performance requirements for forming a lubricating water film in multiple shaft segments, and affecting the low friction characteristics and vibration reduction performance of water-lubricated bearings.

[0005] In view of this, how to use carbon fiber ply design to adjust the dynamic characteristics of the multi-axis section of a water-lubricated bearing to meet the dynamic characteristic requirements for the formation of a lubricating water film has become a key issue that urgently needs to be solved in the research field of water-lubricated bearings. This not only requires accurately analyzing the force conditions and lubrication states of the multi-axis section of the water-lubricated bearing, but also establishing a characteristic model between the elastic modulus of the material and the equivalent support stiffness of the water-lubricated bearing. Furthermore, by reasonably designing the carbon fiber direction and ply scheme, the precise control of the dynamic characteristics of the water-lubricated bearing can be achieved to meet the urgent industrial requirements for vibration reduction and wear resistance of water-lubricated bearings. Summary of the Invention

[0006] To solve the above problems existing in the prior art, the present invention proposes to realize the dynamic characteristics of the multi-axis section of a water-lubricated bearing adapted to the actual working conditions by reasonably designing the carbon fiber ply scheme based on the dynamic performance requirements of the multi-axis section of the water-lubricated bearing under actual working conditions.

[0007] The technical solution of the present invention is as follows:

[0008] An improved method for regulating the dynamic characteristics of the multi-axis section of a water-lubricated bearing based on carbon fiber ply. A mathematical model of the equivalent support stiffness of the water-lubricated bearing is constructed based on the multi-field coupling theory, which covers the parallel coupling mechanism of the fluid water film stiffness and the bearing micro-convex body contact stiffness. Based on the equivalent support stiffness model, the distribution of the load spectrum of the multi-axis section of the water-lubricated bearing is determined through the multi-field coupling pressure field integration algorithm, and the mapping relationship between the load spectrum distribution of the multi-axis section of the water-lubricated bearing and the dynamic characteristics of the multi-axis section is analyzed. Furthermore, with the target stiffness of the multi-axis section as the constraint condition, based on the meso-mechanical constitutive equation of the carbon fiber and matrix composite water-lubricated bearing material, the carbon fiber volume fraction, ply direction, and ply sequence in the composite water-lubricated bearing material are optimized to achieve the gradient regulation of the dynamic performance of the water-lubricated bearing system and the optimization of stability.

[0009] The steps are as follows:

[0010] Step 1: Analyze the multi-field coupling working conditions of the water-lubricated bearing, including rotational speed, load, and the viscosity-temperature characteristics of the lubricating medium, determine the distribution characteristics of the dynamic load spectrum of the bearing-rotating shaft friction pair, and identify the boundary lubrication, mixed lubrication, and fluid lubrication three-state thresholds through the Stribeck curve characteristic parameters, and construct the kinetic characteristic constraint mechanism between the critical water film stability maintenance threshold and the water film dynamic characteristics during the phase change process of the water film hydrodynamic support.

[0011] Step 2: To determine the pressure field distribution characteristics of the lubrication interface of the multi-axis section of the water-lubricated bearing under multi-field coupling working conditions, use the modified average Reynolds equation considering the rheological characteristics of the lubricating medium to solve the average water film pressure of the macroscopic water film hydrodynamic field ; Synchronously use the micro-convex body contact equation based on the fractal theory to solve the micro-convex body contact pressure ;

[0012] Solving the average water film pressure of a water-lubricated bearing by modifying the average Reynolds equation :

[0013]

[0014] Wherein, x is the horizontal direction of the bearing cross-section; y is the vertical direction of the bearing cross-section; is the pressure flow factor in the radial direction of the bearing; is the pressure flow factor in the axial direction of the bearing; is the shear flow factor; is the contact factor; is the average water film pressure; is the axial velocity component of the journal surface; is the axial velocity component of the bearing surface; is the combined root mean square roughness of the journal and bearing surfaces; is the roughness of the journal surface; is the roughness of the bearing surface; h is the water film thickness; μ is the hydrodynamic viscosity; t is the time;

[0015] Solving the asperity contact pressure by the asperity contact equation :

[0016]

[0017]

[0018]

[0019] Wherein, is the elastic modulus of the journal material; is the elastic modulus of the bearing material; is the density of the asperities; is the radius of the asperities; is the film thickness ratio (the ratio of the water film thickness to the combined root mean square roughness); is the standard contact area; p asp is the asperity contact pressure; A asp is the actual contact area of the asperities; is the Poisson's ratio of the journal; is the Poisson's ratio of the bearing; and are statistical functions related to the film thickness ratio.

[0020] Step 3. Using the three-dimensional surface integral algorithm for the average water film pressure Contact pressure with asperities Perform multi-dimensional spatial integration to solve the comprehensive vertical bearing capacity and the comprehensive shear force , establish a multi-field coupling pressure model for the mixed lubrication interface of a water-lubricated bearing, and realize the quantitative characteristic analysis of the multi-axis segment dynamic load spectrum of the water-lubricated bearing;

[0021] Based on the mixed lubrication model of the water-lubricated bearing, integrate the average water film pressure on the bearing surface of the water-lubricated bearing to obtain the water film bearing capacity; based on the asperity contact equation, integrate the asperity contact pressure to obtain the asperity bearing capacity; use the load decomposition theorem based on the circumferential angle , where, in the cross-section of the water-lubricated bearing, a polar coordinate system is established with the geometric center of the water-lubricated bearing as the origin, and the load action direction of the water-lubricated bearing is defined as the reference axis, characterized as the angle between the action direction of the lubrication interface pressure field and the reference axis; project the water film bearing capacity and the asperity bearing capacity onto the x-direction and y-direction of the cross-section of the water-lubricated bearing respectively to obtain the water film vertical bearing capacity and the water film shear force, the asperity vertical bearing capacity and the asperity shear force, and couple the water film vertical bearing capacity and the asperity vertical bearing capacity to obtain the comprehensive vertical bearing capacity expression, and add the water film shear force and the asperity shear force to obtain the comprehensive shear force :

[0022]

[0023] Among them, is the water film vertical bearing capacity; is the asperity vertical bearing capacity; is the water film shear force; is the asperity shear force of the bearing; is the circumferential angle; is the offset angle, which is the angle between the line connecting the journal center and the bearing center and the external load action direction; is the inner diameter of the bearing; is the angular microelement in the circumferential direction of the bearing; is the length microelement in the axial direction; L is the axial length of the bearing.

[0024] Step 4. Determine the non-linear constitutive equation between the comprehensive vertical bearing capacity and the equivalent support stiffness ; based on the stiffness superposition principle, establish a parallel coupling model of the equivalent support stiffness , define its relationship with the water film stiffness and the bearing body stiffness The quantitative relationship between them, and based on this parallel coupling model, establish the equivalent support stiffness of the water-lubricated bearing The mapping relationship with the elastic modulus of the bearing material, and clarify the regulation mechanism of the elastic modulus of the bearing material on the dynamic characteristics of the water-lubricated bearing;

[0025] Based on mechanics of materials, obtain the calculation formulas for the water film stiffness and the bearing body stiffness of the water-lubricated bearing:

[0026]

[0027] Among them, is the stiffness; is the applied force; is the deformation.

[0028] It can be seen from formulas (2) and (3) that the average water film pressure of the water-lubricated bearing and the microconvex body contact pressure , combined with the stiffness calculation formula of formula (6), calculate the water film stiffness and the bearing body stiffness :

[0029]

[0030] Among them, is the water film stiffness; is the bearing body stiffness.

[0031] Based on the non-linear coupling mechanism of the water film stiffness and the bearing body stiffness, define the equivalent support stiffness as the non-linear superposition function of multi-source stiffness, and then determine the calculation formula of the equivalent stiffness of the water-lubricated bearing, realize the cross-scale mapping between the elastic modulus of the water-lubricated bearing material and the equivalent stiffness of the water-lubricated bearing, and complete the establishment of the equivalent stiffness model of the water-lubricated bearing

[0032]

[0033] Among them, is the equivalent support stiffness; is the geometric material shape related parameter of the journal-bush contact surface.

[0034] Step 5: According to the above theory, with the transverse and longitudinal elastic moduli and shear modulus of the carbon fiber and matrix composite water-lubricated bearing material meeting the actual working conditions as the optimization goal, determine the percentage of the carbon fiber volume in the total volume of the carbon fiber and matrix, which is the carbon fiber volume fraction; based on the carbon fiber volume fraction and the wall thickness of the bearing bush of the water-lubricated bearing, determine the total thickness of the carbon fiber ply through the mixture law model; and take the difference in the dynamic stiffness requirements of different shaft sections of the water-lubricated bearing as the objective function to optimize the carbon fiber ply direction and ply sequence of different shaft sections of the water-lubricated bearing, where the carbon fiber laying direction includes and ; after determining the carbon fiber ply direction, determine the ply sequence based on the minimum angle gradient principle and the symmetric ply criterion; among them, the symmetric ply criterion takes the middle plane of the bearing bush wall thickness as the symmetry reference, and the upper and lower plies are symmetrically arranged;

[0035] Step 6: Complete the design and implementation of the carbon fiber ply of the water-lubricated bearing according to the optimization results.

[0036] Advantages of the present invention:

[0037] 1. The present invention combines the modified average Reynolds equation and the microconvex body contact equation, systematically establishes the coupling relationship between the water film pressure, the microconvex body contact force and the equivalent support stiffness of the bearing theoretically, and deeply analyzes the influence of the material elastic modulus on the water-lubricated equivalent support stiffness in combination with material mechanics, providing a new path for theoretical innovation and technical guidance for the development of water-lubricated bearing materials;

[0038] 2. Through the carbon fiber ply design method, the present invention realizes the differentiated dynamic characteristic requirements of different shaft sections of the water-lubricated bearing, ensures the high strength and stability of the lubricating water film under the low-speed heavy-load working conditions of different shaft sections of the water-lubricated bearing, greatly improves the shock absorption performance and anti-wear performance of the water-lubricated bearing, and solves the problem that the single stiffness calculation in the prior art field is difficult to meet the actual working condition requirements;

[0039] 3. Based on the excellent unidirectional mechanical properties of carbon fiber, the present invention not only significantly improves the dynamic characteristics at both the head and tail ends of the bearing, but also enhances the tensile, bending and shear moduli of the material, enabling the bearing head and tail ends with severe compression and shear to have stronger bearing capacity and wear resistance, so the carbon fiber ply technology effectively improves the service life of the water-lubricated bearing from both the static and dynamic characteristics of the bearing material. Description of the drawings

[0040] Figure 1 is the flow chart of the design method for regulating the dynamic characteristics of different shaft sections of the water-lubricated bearing based on carbon fiber ply in the embodiment of the present invention;

[0041] Figure 2 is the structural diagram of the water-lubricated bearing and the coordinate system in the embodiment of the present invention;

[0042] Figure 3 For the spatial shape of the shaft and the force condition on the abnormal wear cross-section of the water-lubricated bearing under actual working conditions;

[0043] Figure 4 For the lubrication state and the force condition at the middle position of the water-lubricated bearing;

[0044] Figure 5 For the lubrication state and the force condition at both the head and tail ends of the water-lubricated bearing;

[0045] Figure 6 For the carbon fiber laying scheme at both the head and tail ends of the water-lubricated bearing;

[0046] Figure 7 For the different carbon fiber ply design schemes of the multi-axis section of the water-lubricated bearing. Specific implementation manners

[0047] The following further describes the specific implementation manners of the present invention in conjunction with the accompanying drawings and technical solutions.

[0048] According to Figure 1 The flowchart designed according to the carbon fiber laying direction shown, including the steps:

[0049] (1) Since the actual force on the water-lubricated bearing under low-speed heavy-load working conditions is affected by multi-field coupling and the situation is relatively complex, we select the shape that the shaft bends downward on both sides of the bearing and arches upward in the middle as determined by Ouyang Wu of Wuhan University of Technology in "Distributed Dynamic Characteristics of Water-Lubricated Stern Bearings under Eccentric Load" in 2019 based on the analysis of water film pressure, shaft center trajectory, and misalignment angle measurement data; and based on the spatial shape of the rotating shaft, further determine the lubrication situation and force state of different shaft sections of the bearing. As can be seen from Figure 3 , there is a water film between the bearing and the shaft in the middle shaft section, belonging to the hydrodynamic lubrication state, and the force condition is as shown in Figure 4 : subject to the water film pressure and the fluid shear force generated by the fluid viscosity; while at both the head and tail ends of the bearing, there is partial boundary lubrication between the bearing and the shaft, belonging to the mixed lubrication state, and the force condition is as shown in Figure 5 : subject to the resultant force of the water film pressure and the micro-convex body contact force and the resultant force of the fluid shear force and the micro-convex body contact shear force.

[0050] Based on the lubrication situation and force state, the dynamic characteristic requirements of the water-lubricated bearing for different shaft sections can be known:

[0051] 1. For the shaft section at the middle position: Under the low-speed and heavy-load working conditions, a complete lubricating water film can be formed at the bearing contact interface to maintain the hydrodynamic lubrication state. At this time, the shaft center restoring force generated by the equivalent support stiffness of the bearing at the middle position matches the external load disturbance under this working condition, which can ensure the stability and load-bearing capacity of the system, and further ensure the integrity and stability of the lubricating water film. There is no need to increase the equivalent support stiffness of the shaft section at the middle position;

[0052] 2. For the shaft sections at the head and tail ends of the bearing: Under the low-speed and heavy-load working conditions, the journal parts at the head and tail ends of the bearing have come into contact with the bearing bush, which proves that the ability of the equivalent support stiffness of the bearing to resist shaft center displacement is less than the external disturbance at this time. Therefore, it is necessary to increase the equivalent support stiffness, improve the support load and anti-disturbance ability, reduce the contact surface in the boundary lubrication area, and ensure the integrity and stability of the lubricating water film. Therefore, for the carbon fiber laying method at the head and tail ends of the bearing, it is necessary to increase the equivalent support stiffness at the head and tail positions.

[0053] The force analysis of the head and tail ends of the water-lubricated bearing shows that due to the downward bending of the rotating shaft on both sides, the bearing is not only subjected to a large pressure on both sides, but also a large frictional force. Therefore, while using carbon fiber laminates to improve the dynamic characteristics of the bearing, the transverse and longitudinal elastic moduli and shear modulus of the material should also be enhanced;

[0054] (2) It can be seen from equations (1)-(5) that based on the modified average Reynolds equation, the microconvex body contact model, and the equivalent support stiffness, a mathematical relationship between the material elastic modulus and the comprehensive vertical bearing capacity is established, and then a positive correlation mathematical relationship between the material elastic modulus and the equivalent support stiffness is determined. Therefore, in the face of the objective function of increasing the equivalent support stiffness at the head and tail ends of the bearing, determine the carbon fiber laying direction and volume fraction;

[0055] (3) Considering the requirements of the static and dynamic mechanical characteristics of the bearing comprehensively, it is necessary to not only increase the equivalent support stiffness at the head and tail ends, but also enhance the elastic modulus and shear modulus at the head and tail ends to meet the bearing's resistance requirements for the downward bending and friction and wear of the rotating shaft. Therefore, it is determined that the fiber laying direction needs to be combined with and .

[0056] Based on the theory of elastic mechanics method, analyze the influence of the carbon fiber laminate direction and sequence on the transverse, longitudinal, and shear moduli of the material:

[0057] 1. Longitudinal elastic modulus:

[0058]

[0059] 2. Transverse elastic modulus:

[0060]

[0061] 3. Shear modulus of elasticity:

[0062]

[0063] 4. Poisson's ratio:

[0064]

[0065] Among them, is the longitudinal modulus of elasticity, , is the transverse modulus of elasticity; , , is the shear modulus of a single ply; , , is Poisson's ratio; is the modulus of elasticity of carbon fiber; is the modulus of elasticity of PEEK;

[0066] is the volume of carbon fiber; is the volume of PEEK; is the fiber shear modulus; is the shear modulus of PEEK; is the Poisson's ratio of carbon fiber; is the Poisson's ratio of PEEK; , , k’ is a coefficient.

[0067] When designing the volume fraction of the bearing material and the carbon fiber in the laying material, the volume fraction of the polymer material of the bearing is selected to be 55% - 95%, and the carbon fiber material laid is 5% - 45%; then, according to the specific actual working conditions of the water-lubricated bearing, the volume fractions of the bearing material and the carbon fiber material are optimized. Taking the low-speed heavy-load working condition of the water-lubricated bearing as an example, based on the influence of the change in the carbon fiber volume fraction on the transverse and longitudinal moduli of elasticity and the shear modulus of elasticity of the material, on the basis of ensuring that the moduli of elasticity and the shear modulus of the material meet the requirements of the actual working conditions, the carbon fiber volume , the volume of the PEEK bearing polymer material , and based on the above formula, the transverse and longitudinal moduli of elasticity and the shear modulus of this carbon fiber composite material are calculated. The calculation results are as follows: longitudinal fiber modulus: 82.775 GPa; transverse fiber modulus: 7.575 GPa; shear modulus: 2.869 GPa. From the calculation results, it can be seen that by reasonably controlling the carbon fiber volume fraction, the transverse, longitudinal, and shear moduli of the PEEK material are significantly enhanced, providing a basis for optimizing the design of the carbon fiber ply orientation sequence;

[0068] After determining the carbon fiber laying direction, the optimal ply design of the carbon fiber is further determined. Based on the fiber ply laying principle: 1. The axial angle between layers should be as small as possible to reduce internal stress concentration and enhance structural stability; 2. The laying angles of adjacent layers should be as different as possible to balance the isotropic mechanical properties of the fibers and improve the overall performance adaptability; 3. Functional layering. To ensure good mechanical properties, carbon fibers are arranged on the surface layer to enhance the longitudinal elastic modulus (parallel to the friction direction, resist friction and wear, and ensure the bonding force between the fiber reinforcement and the matrix; the second layer is carbon fibers, used to improve the dynamic characteristics such as the stiffness of the material. The carbon fibers are superior to and carbon fibers in terms of improving the elastic modulus of the material and maintaining the stiffness of the structural member; the third layer is carbon fibers, used to meet the fiber ply laying principle, enhance the transverse elastic modulus, and improve the balance of the transverse stiffness; the fourth layer is carbon fibers, the fifth layer is carbon fibers... (According to the above principles, the carbon fiber laying directions are arranged in a cycle in the order of 、 、 、and in turn, so as to form a balanced mechanical property distribution in the longitudinal, transverse, and shear directions. The final ply scheme is as Figure 6 shown, which can significantly improve the equivalent support stiffness at both the head and tail ends of the bearing, and at the same time enhance its wear resistance and dynamic stability.)

[0069] Since the actual working conditions do not have strict requirements for the dynamic and static characteristics of the middle shaft section of the water-lubricated bearing, only carbon fibers need to be laid, that is, there is no need to design a ply laying scheme.

[0070] To sum up, the carbon fiber laying scheme with excellent dynamic characteristics of the multi-shaft section of the water-lubricated bearing under the low-speed and heavy-load working conditions and the spatial form with the two ends of the rotating shaft bent downwards and the middle protruding is finally obtained, as Figure 7 shown.

[0071] As mentioned above, for those of ordinary skill in the art, various corresponding changes and deformations can be made according to the technical solutions and technical concepts of the present invention, and all these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. An improved method for regulating the multi-segment dynamic characteristics of a water-lubricated bearing based on carbon fiber layup, characterized in that: Here are the steps: Step 1: Analyze the multi-field coupling working conditions of the water-lubricated bearing, including the speed, load and viscosity-temperature characteristics of the lubricating medium, and determine the dynamic load spectrum distribution characteristics of the bearing-shaft friction pair; identify the three-state thresholds of boundary lubrication, mixed lubrication and fluid lubrication through the characteristic parameters of the Stribeck curve, and construct a dynamic characteristic constraint mechanism between the critical water film stability maintenance threshold and the dynamic characteristics of the water film during the phase change of the water film dynamic pressure support; Step 2: To determine the pressure field distribution characteristics of the multi-segment lubrication interface of the water-lubricated bearing under multi-field coupling conditions, the modified average Reynolds equation considering the rheological characteristics of the lubricating medium is used to solve the average water film pressure of the macroscopic water film dynamic pressure field. ; The contact pressure of the asperity is solved by using the asperity contact equation based on fractal theory. ; Step 3: Calculate the average water film pressure using a three-dimensional surface integral algorithm Contact pressure with asperities Perform multi-dimensional spatial integration to solve the comprehensive vertical bearing capacity and comprehensive shear force , establish a multi-field coupled pressure model of the mixed lubrication interface of water-lubricated bearings, and realize the quantitative characteristic analysis of the multi-axis dynamic load spectrum of water-lubricated bearings; Step 4: Determine the comprehensive vertical bearing capacity based on material mechanics Equivalent support stiffness The nonlinear constitutive equation between the two is established; based on the stiffness superposition principle, the equivalent support stiffness is established The parallel coupling model of , bearing body stiffness The quantitative relationship between them is established, and based on the parallel coupling model, the equivalent support stiffness of the water-lubricated bearing is established. The mapping relationship between the elastic modulus of the bearing material and the elastic modulus of the bearing material is clarified to clarify the regulation mechanism of the elastic modulus of the bearing material on the dynamic characteristics of the water-lubricated bearing; Step 5. According to the above theory, the transverse and longitudinal elastic modulus and shear modulus of the carbon fiber and matrix composite water-lubricated bearing material are optimized to meet the actual working conditions, and the percentage of the carbon fiber volume to the total volume of the carbon fiber and the matrix is ​​determined as the carbon fiber volume fraction; based on the carbon fiber volume fraction and the bearing wall thickness of the water-lubricated bearing, the overall thickness of the carbon fiber ply is determined by the mixed law model; and the difference in dynamic stiffness requirements of multiple shaft sections of the water-lubricated bearing is used as the objective function to optimize the carbon fiber ply direction and ply sequence of different shaft sections of the water-lubricated bearing, where the carbon fiber laying direction includes as well as After determining the carbon fiber ply direction, the ply order is determined based on the minimum angle gradient principle and the symmetrical ply criterion. The symmetrical ply criterion is to use the middle surface of the bearing wall thickness as the symmetry reference, and the upper and lower plies are arranged symmetrically. Step 6: Complete the design and implementation of the carbon fiber layup for the water-lubricated bearing according to the optimization results.

2. The improved method for regulating the multi-segment dynamic characteristics of a water-lubricated bearing based on carbon fiber layup according to claim 1 is characterized in that: The specific implementation process of step 2 is as follows: Solving the average water film pressure of water-lubricated bearings by modified average Reynolds equation : Wherein, x is the horizontal direction of the bearing cross section; y is the vertical direction of the bearing cross section; is the pressure flow factor in the radial direction of the bearing; is the pressure flow factor in the axial direction of the bearing; is the shear flow factor; is the contact factor; is the average water film pressure; is the axial velocity component of the journal surface; is the axial velocity component of the bearing surface; is the combined RMS roughness of the journal and bearing surfaces; is the journal surface roughness; is the bearing surface roughness; h is the water film thickness; μ is the fluid dynamic viscosity; t is the time; Solving the asperity contact pressure by using the asperity contact equation : in, is the elastic modulus of the journal material; is the elastic modulus of the bearing material; is the density of the asperity; is the radius of the asperity; is the film thickness ratio, the ratio of the water film thickness to the integrated RMS roughness; is the standard contact area; p asp is the asperity contact pressure; A asp is the actual contact area of ​​the micro-asperity; is the Poisson's ratio of the journal; is the Poisson’s ratio of the bearing; and is a statistical function related to the film thickness ratio.

3. The improved method for regulating the multi-segment dynamic characteristics of a water-lubricated bearing based on carbon fiber layup according to claim 1 is characterized in that: The specific implementation process of step 3 is as follows: Based on the mixed lubrication model of water-lubricated bearings, the average water film pressure on the bearing surface of the water-lubricated bearing is calculated. The water film bearing capacity is obtained by integration; Based on the asperity contact equation, the asperity contact pressure The bearing capacity of the micro-convex body is obtained by integration; the rotation angle is used The load decomposition theorem is as follows: In the cross section of the water-lubricated bearing, a polar coordinate system is established with the geometric center of the water-lubricated bearing as the origin. The direction of the water-lubricated bearing load is defined as the reference axis. It is characterized by the angle between the direction of the pressure field of the lubrication interface and the reference axis; the water film bearing capacity and the micro-asperity bearing capacity are projected to the x-direction and y-direction of the cross section of the water-lubricated bearing, respectively, to obtain the vertical bearing capacity and shear force of the water film, the vertical bearing capacity and shear force of the micro-asperity, respectively; the vertical bearing capacity of the water film and the vertical bearing capacity of the micro-asperity are coupled to obtain the comprehensive vertical bearing capacity The comprehensive shear force is obtained by adding the water film shear force and the micro-convex shear force ; in, is the vertical bearing capacity of the water film; is the vertical bearing capacity of the micro-convex body; is the water film shear force; is the shear force of the bearing micro-convex body; is the turnover angle; is the offset angle, which is the angle between the line connecting the journal center and the bearing center and the direction of the external load; is the inner diameter of the bearing; is the angle element in the circumferential direction of the bearing; is the infinitesimal length in the axial direction; L is the axial length of the bearing.

4. The improved method for regulating the multi-segment dynamic characteristics of a water-lubricated bearing based on carbon fiber layup according to claim 1 is characterized in that: The specific implementation process of step 4 is as follows: Based on material mechanics, the calculation formulas for the water film stiffness and bearing body stiffness of water-lubricated bearings are obtained: in, is stiffness; To apply force; is the shape variable; From formulas (2) and (3), we know that the average water film pressure of water-lubricated bearings is Contact pressure with asperities , combined with the stiffness calculation formula of formula (6), the water film stiffness is calculated And the bearing body stiffness : in, is the water film stiffness; is the bearing body stiffness; Based on the nonlinear coupling mechanism of water film stiffness and bearing body stiffness, the equivalent support stiffness is defined It is a nonlinear superposition function of multi-source stiffness, and then the equivalent stiffness calculation formula of water-lubricated bearing is determined, the cross-scale mapping between the elastic modulus of water-lubricated bearing material and the equivalent stiffness of water-lubricated bearing is realized, and the equivalent stiffness model of water-lubricated bearing is established: in, is the equivalent support stiffness; It is a parameter related to the geometric material shape of the journal-bearing contact surface.

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