Constant-pressure expansion type stern bearing based on negative Poisson's ratio topological lining structure

Abstract

The invention belongs to the technical field of ship propulsion system bearing structure design and vibration control, and discloses an isobaric expansion type stern bearing based on a negative Poisson's ratio topological lining structure, and a negative Poisson's ratio topological layer is composed of geometric topological units and generates tangential expansion deformation under the action of radial load. Through the negative Poisson's ratio effect, the radial compression load of the shaft system is converted into circumferential expansion response, isobaric expansion of a shaft-lining contact area is achieved, the effective bearing area is increased, and contact pressure distribution is homogenized. The topology lining is divided into a head end topology area, a transition area, a middle topology area, a transition area and a stern end topology area in the axial direction, and all the areas are matched with non-uniform distribution of shaft system bending, unbalance loading and lubricating states under the low-speed and heavy-load working conditions by regulating and controlling topological unit geometric parameters, equivalent Poisson ratios and negative Poisson ratio topological layer thicknesses. According to the invention, edge high pressure and local wear can be obviously reduced, water film stability is improved, bearing capacity and vibration and noise reduction performance of the stern bearing are improved, and service life is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of bearing structure design and vibration control technology for ship propulsion systems, and relates to an isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure. Background Technology

[0002] Traditional water-lubricated stern bearing liners are mostly made of homogeneous elastomer materials such as rubber and polymers. Under shaft load and water film pressure, these liners mainly exhibit radial compressive deformation, while there is a lack of effective linkage between tangential deformation and radial force. This singular compression response mechanism makes it difficult to adapt to shaft off-center loads and pressure gradient changes, easily leading to localized concentration of contact pressure. This, in turn, causes problems such as uneven water film thickness distribution, localized water film rupture, and accelerated wear in high-pressure areas, becoming a significant factor restricting the bearing's load-bearing capacity and service life.

[0003] Existing research mainly focuses on improving the liner structure by addressing material properties, such as reducing the elastic modulus to enhance compliance, using partitioned or gradient materials to alleviate off-center loading, or designing microporous groove structures to optimize water film formation. While these methods can reduce peak contact pressure and improve lubrication, they still fall under the category of passive softening or localized adjustments and cannot fundamentally change the stress-deformation mechanism of the liner. In particular, when subjected to radial pressure, these homogeneous / quasi-homogeneous liners lack a controllable tangential deformation response, making it difficult to achieve coordinated control of radial load, tangential deformation, and contact pressure.

[0004] The negative Poisson's ratio structure, with its unique geometric and topological properties, can induce lateral expansion deformation orthogonal to the loading direction under pressure, providing a novel solution for the radial-tangential cooperative response mechanism. When used as a bearing liner material, the negative Poisson's ratio effect of this structure can precisely convert radial pressure into controllable circumferential expansion, actively reconstructing the morphology of the shaft-bearing liner contact interface, effectively optimizing contact stress distribution and improving water film uniformity. This characteristic gives it significant advantages in alleviating local stress concentration, suppressing edge contact effects, and reducing friction and wear.

[0005] However, existing research on negative Poisson's ratio structures mainly focuses on honeycomb materials, lattice systems, and periodic metamaterials, emphasizing performance optimization such as equivalent elasticity control, energy absorption, and impact protection. Most studies are conducted under free boundary or uniform load conditions, and have not fully considered the unique fluid lubrication environment, off-center loading conditions, constrained deformation boundaries, and shaft-bearing liner contact coupling effects of ship stern bearings. In particular, a systematic design method for liner geometric constraints and service conditions is lacking. Summary of the Invention

[0006] This invention aims to propose a liner structure method based on negative Poisson's ratio topology design. Through geometric topology design, it realizes tangential expansion behavior under radial compression, so that the liner automatically homogenizes the pressure distribution and expands the contact area when the bearing is under load. Combined with the water film, it forms an "isobaric expansion" effect, thereby reducing edge high pressure and local film thickness collapse, and improving the steady-state load-bearing and noise reduction performance of the bearing.

[0007] The technical solution of this invention: An isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure comprises, from the outside to the inside, a bearing housing, a negative Poisson's ratio topological layer, and a liner matrix; The bearing housing is used to support and fix the inner liner structure formed by the inner liner matrix and the negative Poisson's ratio topology layer, and is connected to the inner liner structure by mechanical fitting or bonding; the bearing housing is made of metal material.

[0008] The negative Poisson's ratio topological layer is composed of periodic geometric topological units and is disposed between the inner liner substrate and the bearing housing. It is connected to the inner liner substrate by co-casting or flexible adhesive. The negative Poisson's ratio topological layer is made of polyetheretherketone composite material or polyamide composite material.

[0009] The inner liner substrate forms a lubrication interface with the shaft; the inner liner substrate is made of rubber or polyurethane composite material.

[0010] Furthermore, the periodic geometric topological unit has the following structural forms: reentry honeycomb structure, star-shaped lattice structure, rotatable regular polygonal unit structure, or a quasi-negative Poisson's ratio structure formed by staggered slots. When the inner lining structure is radially compressed, it generates tangential expansion. The equivalent Poisson's ratio is controlled by adjusting parameters such as the unit reentry angle and the unit rib length ratio of the geometric topological unit. The stiffness and expansion effect of the inner lining structure are controlled by adjusting the thickness of the negative Poisson's ratio topological layer and the equivalent Poisson's ratio.

[0011] Furthermore, the negative Poisson's ratio topological layer is sequentially divided into five regions along the axial direction: the head topological region, the transition region between the head topological region and the middle topological region, the middle topological region, the transition region between the middle topological region and the stern topological region, and the stern topological region. Among them, the head topological region and the stern topological region have the same structural form and geometric parameters, the transition region between the head topological region and the middle topological region and the transition region between the middle topological region and the stern topological region have the same geometric parameters, and their structural form is symmetrical about the middle topological region.

[0012] Furthermore, the proximal and stern topological regions correspond to the two ends of the bearing, and their equivalent Poisson's ratios are -0.4 to -0.6; the thickness of the proximal and stern topological regions is 45% to 60% of the total thickness of the inner lining structure; the reentry angle θ of the geometric topological unit is 45° to 55°; and the rib length ratio t / l of the geometric topological unit is 0.10 to 0.14.

[0013] Furthermore, the central topological region corresponds to the middle section of the bearing, and its equivalent Poisson's ratio is -0.15 to -0.25; the thickness of the central topological region is 30% to 40% of the total thickness of the inner lining structure, the unit reentry angle θ of the geometric topological unit is 30° to 40°, and the unit rib length ratio t / l of the geometric topological unit is 0.15 to 0.20.

[0014] Furthermore, the transition regions between the front and middle topological regions and between the middle and stern topological regions are collectively referred to as transition regions. The transition regions achieve a smooth transition of geometric parameters by adjusting the re-entry angle θ of the geometric topological elements, the rib length ratio t / l of the geometric topological elements, and the thickness of the transition regions. The values ​​of the re-entry angle θ, the rib length ratio t / l, and the thickness of the geometric topological elements in the transition regions are within the numerical range formed by the values ​​of the re-entry angle θ, the rib length ratio t / l, and the thickness of the geometric topological elements in the front and middle topological regions.

[0015] During the load-bearing process of the isobaric extended stern bearing based on the negative Poisson's ratio topology liner structure, the negative Poisson's ratio topology layer undergoes rotation, bending or unfolding deformation under radial contact pressure, which causes the equivalent contact width of the contact area between the shaft and the liner matrix to increase adaptively with the increase of load, thereby reducing the contact pressure gradient and realizing isobaric extension and uniform distribution of contact pressure. The negative Poisson's ratio topological layer does not achieve softening by reducing the intrinsic elastic modulus of the material. Instead, it acts as a deformation control layer, actively reconstructing the contact interface morphology through a radial-tangential deformation coupling mechanism while maintaining the necessary load-bearing stiffness.

[0016] During the operation of the isobaric extended stern bearing based on the negative Poisson's ratio topological liner structure, the tangential extension of the negative Poisson's ratio topological layer changes the geometry of the contact area from a local concentrated load-bearing state to an extended load-bearing state, thereby reducing the standard deviation of the contact pressure and the local pressure peak, and reducing the formation of high-pressure areas at the edges. At the same time, the extension of the contact area morphology is conducive to the formation of a more stable lubrication wedge zone, reducing the water film pressure gradient and suppressing local film thickness collapse.

[0017] Through the above structural design, the isobaric extended stern bearing based on the negative Poisson's ratio topological liner structure of the present invention achieves adaptive homogenization of contact pressure and improvement of lubrication stability under low-speed heavy-load conditions without relying on active control or complex lubrication systems.

[0018] The beneficial effects of this invention are: (1) The present invention introduces a negative Poisson's ratio topology layer in the stern bearing design. Through the radial-tangential deformation coupling induced by the negative Poisson's ratio topology, the isobaric expansion of the contact area between the shaft and the bearing liner substrate is achieved, which effectively suppresses local high pressure and edge wear. (2) Under the premise of maintaining the necessary bearing stiffness, the present invention actively reconstructs the contact interface morphology, which significantly improves the stability and bearing capacity of the water film; (3) The negative Poisson's ratio topology layer of the present invention can be realized by additive manufacturing or compression molding, and is suitable for different shaft diameters, loads and off-center load conditions, and has good engineering adaptability and manufacturability; (4) The present invention relates to the element geometric parameters of negative Poisson ratio topological layers, which can be quantitatively controlled by geometric design and have a functional correspondence with the equivalent mechanical response. A database can be established for parameter optimization design. Attached Figure Description

[0019] Figure 1 This is a structural diagram of an isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure; Figure 2 This is a schematic diagram of a reentry-type cellular structure unit; Figure 3 A schematic diagram of the axially divided regions of an isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure.

[0020] In the diagram: 1-Bearing housing; 2-Negative Poisson's ratio topological layer; 3-Inner liner substrate; 4-Forehead topological region; 5-Transition region between the forehead and middle topological regions; 6-Middle topological region; 7-Transition region between the middle and stern topological regions; 8-Stern topological region; 9-Transition zone one; 10-Transition zone two; 11-Transition zone three. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0022] Example This paper designs a water-lubricated stern bearing for a ship's propulsion system operating under low-speed, heavy-load conditions. Under these conditions, the stern shaft rotates at low speeds and experiences large radial loads. The shafting is affected by propeller cantilever loads and hull deformation, exhibiting a spatial shape with downward bending at both ends and an arched shape in the middle. This results in significant differences in the stress and lubrication states of the bearing at different axial positions. Specifically, the bearing located in the middle shaft section has a water film between it and the shaft, exhibiting hydrodynamic lubrication; while the bearings located at the bow and stern ends partially exhibit boundary lubrication between them and the shaft, exhibiting mixed lubrication, which is prone to contact stress concentration, water film rupture, and edge wear.

[0023] Based on the above differences, an isobaric extended stern bearing with a negative Poisson's ratio topological liner structure is proposed to achieve adaptive homogenization of contact pressure in different shaft segments.

[0024] like Figure 1 As shown, an isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure comprises, from the outside to the inside: a bearing housing 1, made of carbon steel, used to bear the overall load of the bearing and fixedly connected to the hull structure; a negative Poisson's ratio topological layer 2, made of polyetheretherketone composite material; and a liner matrix 3, made of rubber material; the negative Poisson's ratio topological layer 2 and the liner matrix 3 form the liner structure. The negative Poisson's ratio topology layer is composed of periodic geometric topological units. The specific structure and parameter design of the geometric topological units are as follows: Figure 2 As shown, the geometric topological unit of the negative Poisson's ratio topological layer 2 is a reentry-type honeycomb structure. The geometric parameters of this geometric topological unit include: the horizontal element side length h, the oblique element side length l, the element reentry angle θ, and the rib thickness t. To ensure that the geometric topological unit can stably rotate and unfold under radial compression without local buckling or instability, its geometric parameters satisfy the following stability constraint: (t / l)sinθ≥0.06, where t / l is the element rib length ratio of the geometric topological unit.

[0025] Axial partitioning design of negative Poisson's ratio topology layer: combining the spatial morphological characteristics of shaft system under low-speed heavy-load conditions, such as... Figure 3 As shown, the negative Poisson's ratio topological layer 2 is sequentially divided into five regions along the axial direction: the head topological region 4, the transition region 5 between the head topological region and the middle topological region, the middle topological region 6, the transition region 7 between the middle topological region and the stern topological region, and the stern topological region 8. Among them, the transition region 5 between the head topological region and the middle topological region is divided into transition partition 1 9, transition partition 2 10, and transition partition 3 11 from near the head topological region 4 to the middle topological region 6. The head topological region 4 and the stern topological region 8 have the same structural form and geometric parameters. The transition region 5 between the head topological region and the middle topological region has the same geometric parameters as the transition region 7 between the middle topological region and the stern topological region, and its structural form is symmetrical about the middle topological region 6. (1) The middle topological region 6 is the middle section of the isobaric extended stern bearing, which adopts a weak negative Poisson's ratio topology. The horizontal element side length of the geometric topological unit is h1=3.2 mm, the oblique element side length of the geometric topological unit is l1=4.0 mm, the rib thickness of the geometric topological unit is t1=0.72 mm, the rib length ratio of the geometric topological unit is t1 / l1=0.18, the element reentry angle of the geometric topological unit is θ1=35°, and the thickness of the middle topological region 6 is h t1It accounts for 35% of the total thickness of the inner lining structure, and its equivalent Poisson's ratio is taken as -0.20 to ensure load-bearing stiffness and prevent excessive deformation; (2) The bow topology region 4 and the stern topology region 8 correspond to the two shaft sections of the isobaric extended stern bearing; under low-speed heavy load conditions, the shaft of the bow topology region 4 and the stern topology region 8 has obvious local contact with the inner liner substrate 3; the topology adopts a negative Poisson's ratio effect reinforced topology structure, the horizontal element side length h2=3.2 mm, the oblique element side length l2=4.0 mm, the rib thickness t2=0.48 mm, the rib length ratio t2 / l2=0.12, the element reentry angle θ2=50°, and the thickness h of the bow topology region 4 and the stern topology region 8 are... t2 It accounts for 55% of the total thickness of the inner lining structure, and its equivalent Poisson's ratio is taken as -0.52; (3) The transition zone 5 between the head topology region and the middle topology region, through the geometric topological elements of transition partition 1 (9), transition partition 2 (10), and transition partition 3 (11), has the element re-entry angle θ, the rib length ratio t / l of the geometric topological elements, and the thickness h of the transition zone 5 between the head topology region and the middle topology region. t The changes achieve a smooth transition of topological parameters between the initial topological region 4 and the middle topological region 6. The percentage of the thickness of transition zones 1 (9), 2 (10), and 3 (11) to the total thickness of the inner lining structure linearly decreases from 55% to 35%. The geometric parameters of the geometric topological units in transition zone 1 (9) are: horizontal unit side length h = 3.2 mm, oblique unit side length l = 4.0 mm, rib thickness t = 0.56 mm, rib length ratio t / l = 0.14, unit reentry angle θ = 45°, and equivalent Poisson's ratio -0.40. The geometric parameters of the geometric topological units in transition zone 2 (10) are: horizontal unit side length h = 3.2 mm, oblique unit side length l = 4.0 mm, and rib thickness t = 0.64 mm. mm, the rib length ratio t / l=0.16 of the geometric topology element, the element reentry angle θ=40° of the geometric topology element, and the equivalent Poisson's ratio -0.30; the geometric parameters of the geometric topology element in transition partition 31 are: horizontal element side length h=3.2 mm, oblique element side length l=4.0 mm, rib thickness t=0.68 mm, rib length ratio t / l=0.17, element reentry angle θ=37° of the geometric topology element, and the equivalent Poisson's ratio -0.25.

[0026] Isobaric expansion mechanism: During the load-bearing process of the isobaric expansion stern bearing, the shaft applies radial contact pressure to the bearing liner. Unlike traditional homogeneous bearing liners that only undergo radial compression, the negative Poisson's ratio topological layer in this embodiment exhibits significant tangential expansion deformation under radial pressure, causing the equivalent contact width of the shaft-liner contact area to adaptively increase with increasing load. This tangential expansion behavior brings the following effects: the contact pressure changes from localized concentrated load to expanded load, reducing the pressure peak; the contact pressure is more uniformly distributed circumferentially, reducing the pressure standard deviation; and the expansion of the contact area geometry facilitates the formation of a more stable lubrication wedge region, suppressing local film thickness collapse. This achieves isobaric expansion load-bearing under low-speed, heavy-load conditions.

Claims

1. An isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure, characterized in that, The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure comprises, from the outside to the inside, a bearing housing, a negative Poisson's ratio topological layer, and a liner matrix. The bearing housing is used to support and fix the inner liner structure formed by the inner liner matrix and the negative Poisson's ratio topology layer, and is connected to the inner liner structure by mechanical fitting or bonding. The negative Poisson's ratio topological layer is composed of periodic geometric topological units and is disposed between the inner lining matrix and the bearing housing. It is connected to the inner lining matrix by co-casting or flexible adhesive. The inner liner substrate forms a lubrication interface with the shaft.

2. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 1, characterized in that, The bearing housing is made of metal.

3. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 1, characterized in that, The inner lining matrix is ​​made of rubber or polyurethane composite material.

4. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 1, characterized in that, The negative Poisson's ratio topological layer is made of polyetheretherketone composite material or polyamide composite material.

5. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 1, characterized in that, The periodic geometric topological unit has the following structural forms: reentry honeycomb structure, star-shaped lattice structure, rotatable regular polygonal unit structure, or a quasi-negative Poisson's ratio structure formed by staggered slots. When the inner lining structure is radially compressed, it generates tangential expansion. The equivalent Poisson's ratio is controlled by adjusting parameters such as the unit reentry angle and the unit rib length ratio of the geometric topological unit. The stiffness and expansion effect of the inner lining structure are controlled by adjusting the thickness of the negative Poisson's ratio topological layer and the equivalent Poisson's ratio.

6. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 1, characterized in that, The negative Poisson's ratio topological layer is divided into five regions along the axial direction: the fore-end topological region, the transition region between the fore-end and middle topological regions, the middle topological region, the transition region between the middle and stern topological regions, and the stern topological region. The fore-end and stern topological regions have the same structure and geometric parameters. The transition regions between the fore-end and middle topological regions and the transition regions between the middle and stern topological regions have the same geometric parameters, and their structure is symmetrical about the middle topological region.

7. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 6, characterized in that, The proximal and stern topological regions correspond to the shaft segments at both ends of the bearing, and their equivalent Poisson's ratios are -0.4 to -0.

6. The thickness of the proximal and stern topological regions is 45% to 60% of the total thickness of the inner lining structure. The reentry angle θ of the geometric topological unit is 45° to 55°, and the rib length ratio t / l of the geometric topological unit is 0.10 to 0.

14.

8. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 6, characterized in that, The central topological region corresponds to the middle section of the bearing, and its equivalent Poisson's ratio is -0.15 to -0.25; the thickness of the central topological region is 30% to 40% of the total thickness of the inner lining structure, the element reentry angle θ of the geometric topological element is 30° to 40°, and the element rib length ratio t / l of the geometric topological element is 0.15 to 0.

20.

9. The isobaric extended stern bearing based on a negative Poisson's ratio topological liner structure according to claim 6, characterized in that, The transition region is defined by adjusting the element reentry angle θ of the geometric topology element, the element rib length ratio t / l of the geometric topology element, and the thickness h of the negative Poisson's ratio topology layer. t To achieve a smooth transition of geometric parameters; the element reentry angle θ, element rib length ratio t / l, and thickness h of the negative Poisson's ratio topology layer of the transition region. t The value of is between the element reentry angle θ of the geometric topological element in the head topological region and the middle topological region, the element rib length ratio t / l of the geometric topological element, and the thickness h of the negative Poisson's ratio topological layer. t The range of values ​​formed by the values ​​of .

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