Non-linear elastic damping unit-based low-vibration floating platform mooring design method and ocean energy platform mooring

Abstract

The invention provides a low-vibration floating platform mooring design method based on a nonlinear elastic damping unit. The nonlinear elastic damping unit is arranged in a mooring chain between a floating platform and an anchoring point in series; the nonlinear elastic damping unit is composed of a multi-stage gradual stiffness spring and a speed-sensitive hydraulic damping system, the stiffness function of the multi-stage gradual stiffness spring is k (x), the multi-stage gradual stiffness spring shows the flexible characteristic during small tensile displacement, the stiffness is gradually enhanced during large tensile displacement, and nonlinear elastic response is achieved; a variable throttling channel is arranged in the speed-sensitive hydraulic damping system, the damping function is cp (), the requirement that damping force is increased along with the increase of the movement speed is met, and the speed-sensitive damping characteristic is achieved. The overall mechanical response of the nonlinear elastic damping unit is described by a function F (x). The large-amplitude vibration of the floating platform can be effectively restrained, the mooring fatigue load of the ocean energy platform is reduced, and the steady-state performance and safety of the platform are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of offshore engineering equipment, and particularly relates to a mooring design method for a low-vibration floating platform based on a nonlinear elastic damping unit and a mooring for an ocean energy platform. Background Art

[0002] In recent years, the application of floating platforms in ocean energy development and offshore engineering has been increasing continuously, and the stability of the platform and the safety of the mooring system have become key issues. The traditional mooring chain design has limited effects in suppressing platform vibration and coping with large-amplitude wave disturbances, which easily leads to excessive platform displacement or fatigue failure of the mooring chain. Therefore, a new mooring design method needs to be developed to better suppress platform vibration and ensure its safety and stability under complex sea conditions. Summary of the Invention

[0003] The object of the present invention is to provide a mooring design method for a low-vibration floating platform based on a nonlinear elastic damping unit to improve platform stability and reduce mooring chain fatigue. The obtained mooring for an ocean energy platform can effectively suppress vibration, remain compliant under small-amplitude waves, and provide strong restoring force and energy dissipation under large-amplitude impacts.

[0004] The present invention provides a mooring design method for a low-vibration floating platform based on a nonlinear elastic damping unit, in which a nonlinear elastic damping unit is arranged in series in the mooring chain between the floating platform and the anchoring point; The nonlinear elastic damping unit is composed of a multi-stage progressive stiffness spring and a velocity-sensitive hydraulic damping system. The stiffness function of the multi-stage progressive stiffness spring is k(x), which satisfies the flexible characteristic at small tensile displacements and the stiffness gradually increases at large tensile displacements to achieve a nonlinear elastic response; a variable throttle channel is provided in the velocity-sensitive hydraulic damping system, and the damping function is c p ( ), which satisfies that the damping force increases with the increase of the motion speed to achieve the velocity-sensitive damping characteristic; the overall mechanical response of the nonlinear elastic damping unit is described by the function F(x), and the specific expression is as follows: ; where x represents the tensile amount of the mooring chain; represents the motion speed of the platform.

[0005] Further, the specific expression of the stiffness function k(x) of the multi-stage progressive stiffness spring is as follows: ; where x represents the tensile amount of the mooring chain, x1 represents the starting displacement of the progressive stiffness, x2 represents the saturation displacement of the progressive stiffness, and there is x1 < x2, k0 represents the initial stiffness of the mooring chain, k maxThis indicates the maximum stiffness of the mooring chain.

[0006] Furthermore, the damping function C of the speed-sensitive hydraulic damping system p ( The specific expression for ) is as follows: ; In the formula, c min c is the minimum damping coefficient at low speed. max This represents the maximum damping coefficient at high speeds. v0 represents the speed at which the damping coefficient begins to increase rapidly, and a represents the steepness of the transition near the control threshold, which determines the smoothness of the increase in the damping coefficient.

[0007] The present invention also provides a marine energy platform mooring, including a mooring chain, which is obtained according to the aforementioned low-vibration floating platform mooring design method based on nonlinear elastic damping units.

[0008] By employing the aforementioned scheme, a low-vibration floating platform mooring design method based on nonlinear elastic damping units is adopted. This method utilizes a multi-stage progressive stiffness spring structure to achieve a progressively increasing stiffness response as displacement increases, and a velocity-sensitive hydraulic damping system to achieve damping adjustment that varies with motion speed. This allows the platform to remain compliant under small-amplitude wave action and provide strong restoring force and energy dissipation under large-amplitude impacts. The design, centered on the nonlinear mechanical function F(x), achieves joint control of stiffness and damping, giving the marine energy platform mooring adaptive variable stiffness and variable damping characteristics. The marine energy platform mooring obtained through this design method can effectively suppress large-amplitude vibrations of the floating platform, reduce fatigue loads, and improve the platform's steady-state performance and safety.

[0009] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the application of a mooring chain obtained by a low-vibration floating platform mooring design method based on a nonlinear elastic damping unit according to an embodiment of the present invention to the mooring of an ocean energy platform. Figure 2 This is a schematic diagram of the stiffness function k(x) of a multi-stage progressive stiffness spring according to an embodiment of the present invention; Figure 3 The damping function Cp of the speed-sensitive hydraulic damping system according to an embodiment of the present invention is... (Diagram)

[0011] Reference numerals: 1 - Floating platform; 2 - Anchoring point; 3 - Mooring chain; 4 - Nonlinear elastic damping unit; 5 - Multi - stage progressive stiffness spring; 6 - Velocity - sensitive hydraulic damping system. Specific embodiments

[0012] The following combines the drawings and embodiments to further describe the specific embodiments of the present invention in detail. The following embodiments are used to illustrate the present invention, but do not limit the scope of the present invention.

[0013] Refer Figures 1 to 3 As shown, this embodiment provides a mooring design method for a low - vibration floating platform and a mooring for an ocean energy platform based on a nonlinear elastic damping unit.

[0014] The mooring of the ocean energy platform applying the nonlinear elastic damping unit includes a floating platform 1, an anchoring point 2, and a mooring chain 3 connecting the floating platform 1 and the anchoring point 2. A nonlinear elastic damping unit 4 is connected in series in the mooring chain 3. The nonlinear elastic damping unit includes a multi - stage progressive stiffness spring 5 and a velocity - sensitive hydraulic damping system 6.

[0015] The stiffness function of the multi - stage progressive stiffness spring 5 is k(x), which satisfies the flexible characteristic at small tensile displacements and the stiffness gradually increases at large tensile displacements to achieve a nonlinear elastic response. A variable throttle channel is provided in the velocity - sensitive hydraulic damping system 6, and the damping function is c p ( ) which satisfies that the damping force increases with the increase of the motion speed to achieve the velocity - sensitive damping characteristic. The overall mechanical response of the nonlinear elastic damping unit 4 is described by the function F(x), and the specific expression is as follows: .

[0016] In some embodiments, the specific expression of the stiffness function k(x) of the multi - stage progressive stiffness spring is as follows: ; where x represents the elongation of the mooring chain, x1 represents the starting displacement of the progressive stiffness, x2 represents the saturation displacement of the progressive stiffness, and x1 < x2. k0 represents the initial stiffness of the mooring chain, and k max represents the maximum stiffness of the mooring chain. The starting and ending displacement intervals of the spring stiffness change can be controlled by adjusting x1 and x2, thereby adjusting the sensitive range of the nonlinear response; the initial stiffness in the small - displacement stage can be controlled by adjusting k0, thereby adjusting the compliance of the system; by adjusting k max control the maximum stiffness in the large - displacement stage, thereby adjusting the bearing capacity and vibration - resistance performance of the system under large deformations.

[0017] In some embodiments, the damping function C of the velocity - sensitive hydraulic damping system p( The specific expression for ) is as follows: .

[0018] In the formula, c min c is the minimum damping coefficient at low speed. max This represents the maximum damping coefficient at high speeds. This represents the platform's motion speed; v0 represents the speed threshold at which the damping coefficient begins to increase rapidly; and 'a' represents the steepness of the transition near the control threshold, determining the smoothness of the damping coefficient increase. This can be achieved by adjusting c. min c max By controlling the minimum and maximum values ​​of the damping coefficient, the range of damping force is determined; by adjusting v0, the inflection point of damping change with speed is set, thereby adjusting the speed sensitivity characteristics; by adjusting a, the degree of nonlinearity of damping force growth with speed is controlled, thereby adjusting the system's energy dissipation capacity and response smoothness.

[0019] This invention proposes a low-vibration floating platform mooring design method and marine energy platform mooring based on nonlinear elastic damping units. This method achieves the following when the platform is subjected to environmental loads: during small displacement stages, flexible springs provide compliance, while during large displacement stages, the stiffness gradually increases to prevent excessive stretching. Simultaneously, the damping units provide low damping during low-speed motion and automatically increase damping force during high-speed motion. Through the synergistic effect of this nonlinear elasticity and velocity-sensitive damping, adaptive vibration reduction of the mooring chain is achieved, significantly reducing the platform's vibration response.

[0020] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-vibration floating platform mooring design method based on nonlinear elastic damping units, characterized in that, Nonlinear elastic damping elements are arranged in series in the mooring chain between the floating platform and the anchor point; The nonlinear elastic damping unit consists of a multi-stage progressive stiffness spring and a velocity-sensitive hydraulic damping system. The stiffness function of the multi-stage progressive stiffness spring is k(x), which exhibits flexible characteristics at small tensile displacements and gradually increases stiffness at large tensile displacements, achieving a nonlinear elastic response. The velocity-sensitive hydraulic damping system has a variable throttling channel, and the damping function is c. p ( The damping force increases with increasing velocity, achieving velocity-sensitive damping characteristics. The overall mechanical response of the nonlinear elastic damping unit is described by the function F(x), with the specific expression as follows: ； In the formula, x represents the amount of stretching of the mooring chain; This indicates the platform's movement speed.

2. The low-vibration floating platform mooring design method based on nonlinear elastic damping units according to claim 1, characterized in that, The specific expression for the stiffness function k(x) of the multi-stage progressive stiffness spring is as follows: ； Where x represents the elongation of the mooring chain, x1 represents the starting displacement of the progressive stiffness, x2 represents the saturation displacement of the progressive stiffness, and x1 < x2, k0 represents the initial stiffness of the mooring chain, and k max represents the maximum stiffness of the mooring chain.

3. The low-vibration floating platform mooring design method based on nonlinear elastic damping units according to claim 1, characterized in that, The damping function C of the velocity-sensitive hydraulic damping system p ( The specific expression for ) is as follows: ； In the formula, c min c is the minimum damping coefficient at low speed. max This represents the maximum damping coefficient at high speeds. v0 represents the speed at which the damping coefficient begins to increase rapidly, and a represents the steepness of the transition near the control threshold, which determines the smoothness of the increase in the damping coefficient.

4. A mooring system for an ocean energy platform, characterized in that, The mooring chain is obtained by the low-vibration floating platform mooring design method based on nonlinear elastic damping unit according to any one of claims 1-3.

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