Floating production storage and offloading (FPSO) upper module lower supporting point simulation method considering local rigidity influence

Abstract

The invention relates to the technical field of structural rod piece vibration analysis, in particular to an FPSO upper module lower supporting point simulation method considering local rigidity influence, which comprises the following steps: S1, establishing an upper module structure frame overall model according to design drawing requirements; s2, refining the model at the supporting point of the upper module; s3, simulating a ship body local model at a supporting point; s4, applying reasonable constraint conditions to the local model of the ship body at the supporting points; s5, applying a load to the upper modular structure frame according to the working condition; s6, finite element numerical solution analysis is carried out, and a structural response result with local rigidity influence being taken into account is obtained; a model at a supporting point is refined through a simulation method, and the local rigidity of a ship body is considered, so that the mechanical behavior of an actual structure is reflected more truly, the precision of an analysis result is improved, potential problems can be identified and optimized in a design stage, and the safety and reliability of an FPSO upper module are improved; and the bearing capacity of the structure is improved by improving the local rigidity of the supporting point area.

Description

Technical Field

[0001] This invention relates to the field of structural member vibration analysis technology, and in particular to a simulation method for the lower support point of the FPSO upper module that takes into account the influence of local stiffness. Background Technology

[0002] FPSO (Floating Production Storage and Offloading) units are key facilities in offshore oil and gas development. Their topside modules typically include heavy structures such as production equipment and living quarters, which are connected to the hull via support points. Under marine environmental loads (such as wind, waves, and inertial forces), the loads of the topside modules are transferred to the hull structure through the support points. Therefore, the design of the support points directly affects the safety and fatigue life of the overall structure.

[0003] In existing technologies, the simulation of the support points of the FPSO upper module often uses simplified models that ignore the influence of local stiffness, leading to discrepancies between the analysis results and actual working conditions. For example, simplified models cannot accurately reflect stress concentration, deformation compatibility issues, and the dynamic response of connection nodes at the support points, which may underestimate the risk of local fatigue damage or excessive deformation.

[0004] Therefore, the technical problem that this application actually aims to solve is: how to provide a simulation method for the lower support point of the FPSO upper module that can accurately take into account the influence of local stiffness, so as to improve the model accuracy and the reliability of structural response prediction. Summary of the Invention

[0005] The main objective of this invention is to provide a simulation method for the lower support point of the FPSO upper module that takes into account the influence of local stiffness, so as to solve the problems raised in related technologies.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for simulating the lower support point of an FPSO upper module considering the influence of local stiffness is provided, comprising the following steps: S1. Establish an overall model of the upper module structure framework according to the design drawings; S2. Refine the model at the support points of the upper module; S3. Simulate a partial model of the hull at the support point; S4. Apply reasonable constraints to the local model of the hull at the support point; S5. Apply loads to the upper module structural frame according to the working conditions; S6. Conduct finite element numerical analysis to obtain the structural response results that take into account the influence of local stiffness.

[0007] Furthermore, it includes an upper module structure frame, which is fixedly mounted on the hull. The upper module structure frame includes at least a number of platform frames distributed in the vertical direction. The platform frames are formed by interlacing and welding of several H-beams, and several connecting rods are welded between two adjacent platform frames.

[0008] Furthermore, several upper module support points are fixedly installed at the bottom of the platform frame at the lowest point, and the upper module support points include at least the columns welded to the bottom edge of the platform frame.

[0009] Furthermore, the lower end sidewall of the column is symmetrically welded with length direction stiffening plates, and the lower end sidewall of the column is also symmetrically welded with beam direction stiffening plates, which are arranged perpendicularly to the beam direction stiffening plates.

[0010] Furthermore, the lower end of the column is provided with several grooves in a circular array, and one side of the length direction stiffener and the width direction stiffener are inserted into the grooves and welded to them.

[0011] Furthermore, inclined braces are symmetrically arranged between two adjacent columns, and the lower end of the inclined braces is fixedly connected to the longitudinal stiffening plate of the ship.

[0012] Furthermore, the lower ends of the diagonal brace and the column have symmetrical oblique cuts.

[0013] Furthermore, the length direction stiffeners are arc-shaped on both sides of the lower end of the diagonal brace, and the width direction stiffeners are triangular.

[0014] Furthermore, the length direction stiffener and the width direction stiffener are welded perpendicularly to the upper surface of the hull.

[0015] Furthermore, the bottom of the hull is welded with several hull stiffening ribs to enhance the structural strength of the hull.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In this simulation method for the lower support point of the FPSO upper module that takes into account the influence of local stiffness, by setting up reinforcing structures such as columns, stiffening plates and diagonal braces at the support point of the upper module and optimizing their connection method, the local stiffness of the support point area is effectively improved, thereby transferring the load more accurately, reducing stress concentration, and improving the load-bearing capacity and fatigue life of the structure.

[0017] 2. In this simulation method for the lower support point of the FPSO upper module that takes into account the influence of local stiffness, the model at the support point is refined by simulation method and the local stiffness of the hull is considered. This can more realistically reflect the mechanical behavior of the actual structure, improve the accuracy of the analysis results, help identify and optimize potential problems in the design stage, and improve the safety and reliability of the FPSO upper module. Attached image description: Figure 1 This is a schematic diagram of the overall structure of the lower support point of the FPSO upper module in Embodiment 1 of the present invention, taking into account the influence of local stiffness. Figure 2 This is a schematic diagram of the overall structure of the upper module support point in Embodiment 1 of the present invention; Figure 3 This is a cross-sectional view along the length of the ship of the upper module support point in Embodiment 1 of the present invention; Figure 4 This is a cross-sectional view of the upper module support point along the width of the ship in Embodiment 1 of the present invention.

[0018] Illustration: 1. Upper module structural frame; 11. Platform frame; 12. Connecting rod; 2. Upper module support points; 21. Length direction stiffeners; 22. Beam direction stiffeners; 23. Diagonal braces; 24. Columns; 3. Hull; 31. Hull stiffening ribs. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] The purpose of this embodiment is to provide a simulation method for the lower support point of the FPSO upper module that takes into account the influence of local stiffness, including the following steps: S1. Weld several H-beams vertically and interlaced according to the design drawings to form several platform frames 11. Weld several connecting rods 12 between two adjacent platform frames 11 to form a complete upper module structure frame 1. S2. Refine the model at support point 2 of the upper module, accurately simulating the structure of each component according to the drawings; weld several columns 24 to the bottom of the platform frame 11 at the bottom, and weld mutually perpendicular longitudinal stiffeners 21 and beam stiffeners 22 to the lower end of the columns 24, and weld diagonal braces 23 between two adjacent columns 24, so that the lower end of the diagonal braces 23 is welded to the longitudinal stiffeners 21; use a specific mesh generation technique to densify the area near support point 2 of the upper module to improve the accuracy of the model.

[0021] S3. Simulate the local model of the hull 3 at the support point, weld the longitudinal stiffening plate 21 and the beam stiffening plate 22 to the upper surface of the hull 3, and weld several hull stiffening ribs 31 at the bottom of the hull 3. Taking into account factors such as material nonlinearity, geometric configuration, weld connection characteristics and contact behavior between components, the influence mechanism of the support structure on the local stiffness of the hull 3 is fully reflected. S4. Based on the actual working conditions and boundary conditions, apply reasonable constraints to the local model of hull 3 at the support point; based on the overall deformation of hull 3 and the connection constraints between hull 3 and the upper module structure frame 1, set constraints on the displacement, rotation and other degrees of freedom of the local model of hull 3 at the support point to ensure that the local model can truly reflect the global response. S5. Based on the actual load environment that the FPSO may encounter during operation, apply multiple load combinations to the upper module structure frame 1, including but not limited to wind load, wave inertial force, equipment operation dynamic load, self-weight and operation additional mass, to simulate the stress state under various typical working conditions (such as full load, no load, extreme sea state, etc.). S6. Conduct finite element numerical analysis to obtain structural response results that take into account the influence of local stiffness; by solving the structural mechanics control equations, output data such as stress distribution cloud map, displacement-deformation curve, strain energy density distribution and force transmission path of support points in key parts; the analysis results cover, but are not limited to: stress concentration level, deformation compatibility, connection node safety and dynamic response characteristics of the entire upper module structural frame 1 at support point 2 of the upper module.

[0022] like Figure 1 As shown, the FPSO upper module lower support point, which takes into account the influence of local stiffness, includes an upper module structural frame 1. The upper module structural frame 1 is fixedly installed on the hull 3. The upper module structural frame 1 includes at least a number of platform frames 11 distributed in the vertical direction. The platform frames 11 are formed by welding several H-beams together to form a grid-like load-bearing structure. This grid-like load-bearing structure has high strength and stiffness and can effectively bear the weight of the upper module and various loads. Several connecting rods 12 are welded between two adjacent platform frames 11. The connecting rods 12 are channel steels and are used to connect adjacent platform frames 11 to improve the spatial stiffness and stability of the overall structure. The selection of channel steel must take into account factors such as its cross-sectional shape, size and material to ensure that it can meet the requirements of connection and reinforcement.

[0023] like Figure 1As shown, several upper module support points 2 are fixedly installed at the bottom of the platform frame 11 at the lowest point. The upper module support points 2 include at least one column 24 welded to the bottom edge of the platform frame 11. The position and number of the columns 24 need to be reasonably determined according to the stress of the upper module and the load-bearing capacity of the hull 3 to ensure that the support points can effectively transfer the load of the upper module to the hull 3.

[0024] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the lower sidewall of the column 24 is symmetrically welded with a longitudinal stiffening plate 21, and the lower sidewall of the column 24 is also symmetrically welded with a beam stiffening plate 22. The longitudinal stiffening plate 21 and the beam stiffening plate 22 are arranged perpendicularly to each other, forming an orthogonal reinforcement structure, which effectively improves the load-bearing capacity of the support point area in the longitudinal and transverse directions. The orthogonal reinforcement structure can disperse the load, reduce local stress concentration, and improve the stability and reliability of the structure.

[0025] like Figure 2 As shown, the lower end of the column 24 has several grooves arranged in a ring array. The length direction stiffener 21 and the width direction stiffener 22 are inserted into the grooves on one side and are firmly welded by fillet welds, thereby enhancing the node connection strength and improving the stress transmission path.

[0026] like Figure 1 and Figure 2 As shown, inclined braces 23 are symmetrically arranged between two adjacent columns 24. The lower end of the inclined brace 23 is fixedly connected to the longitudinal stiffener 21 of the ship to form a stable triangular support system, which significantly improves the lateral displacement and bending resistance of the support structure. The triangular support system has high stability and can effectively resist the action of lateral forces and bending moments, thereby improving the overall stiffness and stability of the support structure.

[0027] like Figure 2 As shown, the lower ends of the diagonal brace 23 and the column 24 are symmetrically cut, which facilitates matching and welding with other components and reduces stress concentration caused by geometric abrupt changes. The design of the cut surface can make the welded joint smoother, reduce stress concentration, and improve welding quality and service life.

[0028] like Figure 2 As shown, the length direction stiffener 21 is arc-shaped on both sides of the lower end of the diagonal brace 23, and the width direction stiffener 22 is triangular. This optimized shape helps to disperse local stress and improve fatigue life. This shape design can make the stress more evenly distributed, reduce local stress peaks, and improve the fatigue performance and service life of the structure.

[0029] like Figure 3 and Figure 4 As shown, the longitudinal stiffener 21 and the transverse stiffener 22 are vertically welded to the upper surface of the hull 3 to ensure efficient load transfer to the hull 3 structure; the vertical welding arrangement can ensure the straightness of load transfer, reduce energy loss, and improve load transfer efficiency.

[0030] like Figure 3 and Figure 4 As shown, several hull stiffening ribs 31 are welded to the bottom of the hull 3 to enhance the local structural rigidity of the hull 3 and prevent buckling or excessive deformation due to concentrated loads. The arrangement of the hull stiffening ribs 31 should be reasonable according to the stress conditions and local rigidity requirements of the hull to ensure that the hull can maintain stable structural performance under various working conditions.

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A simulation method for the lower support point of an FPSO upper module considering the influence of local stiffness, characterized in that, Includes the following steps: S1. Establish the upper module structure framework (1) overall model according to the design drawings; S2. Refine the model at the upper module support point (2); S3, Simulate the local model of the hull (3) at the support point; S4. Apply reasonable constraints to the local model of the hull (3) at the support point; S5. Apply loads to the upper module structural frame (1) according to the working conditions; S6. Conduct finite element numerical analysis to obtain the structural response results that take into account the influence of local stiffness.

2. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness as described in claim 1, characterized in that, The system includes an upper module structure frame (1), which is fixedly mounted on the hull (3). The upper module structure frame (1) includes at least a number of platform frames (11) distributed in the vertical direction. The platform frames (11) are made of several H-beams welded together in an interlaced manner, and several connecting rods (12) are welded between two adjacent platform frames (11).

3. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness as described in claim 2, characterized in that, The bottom of the platform frame (11) at the bottom is fixedly provided with several upper module support points (2), and the upper module support points (2) include at least the columns (24) welded to the bottom edge of the platform frame (11).

4. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness as described in claim 3, characterized in that, The lower side wall of the column (24) is symmetrically welded with a length direction stiffening plate (21), and the lower side wall of the column (24) is also symmetrically welded with a width direction stiffening plate (22). The length direction stiffening plate (21) and the width direction stiffening plate (22) are arranged perpendicularly.

5. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness as described in claim 4, characterized in that, The lower end of the column (24) is provided with several grooves in a circular array. The length direction stiffener (21) and the width direction stiffener (22) are inserted into the grooves and welded to them.

6. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness according to claim 4, characterized in that, The two adjacent columns (24) are symmetrically provided with inclined braces (23), and the lower end of the inclined braces (23) is fixedly connected to the ship's longitudinal stiffener (21).

7. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness as described in claim 6, characterized in that, The lower ends of the diagonal brace (23) and the column (24) are symmetrically cut.

8. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness as described in claim 6, characterized in that, The length direction stiffener (21) is arc-shaped on both sides of the lower end of the diagonal brace (23), and the width direction stiffener (22) is triangular.

9. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness according to claim 4, characterized in that, The length direction stiffener (21) and the width direction stiffener (22) are welded perpendicularly to the upper surface of the hull (3).

10. The simulation method for the lower support point of the FPSO upper module taking into account the influence of local stiffness according to claim 1, characterized in that, The bottom of the hull (3) is welded with several hull stiffening ribs (31) to enhance the structural strength of the hull (3).

Images