A fatigue analysis method and system for an upper module of an FPSO based on coupling effect

Abstract

This invention discloses a fatigue analysis method and system for the top module of an FPSO based on coupling effects. The fatigue analysis method for the top module of an FPSO based on coupling effects includes the following steps: S1: wave environment data reconstruction; S2: wave-hull deformation data coupling; S3: coupling analysis model construction; S4: fatigue response analysis; S5: engineering application guidance. The fatigue analysis method for the top module of an FPSO based on coupling effects provided by this invention avoids the existing method's approach of considering wave loads or hull deformation separately in fatigue analysis, thus improving the accuracy and reliability of the calculation and analysis results.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering structural safety technology, and particularly relates to a fatigue analysis method and system for the top module of an FPSO based on coupling effects. Background Technology

[0002] The FPSO top module is subjected to marine environmental loads for a long time. The six-degree-of-freedom motion of the hull caused by wave motion has a significant coupling effect with the hull arching and sagging deformation, which directly affects the stress distribution and fatigue damage of the key components of the top module.

[0003] Traditional fatigue analysis methods for FPSO topside modules often decouple wave motion from hull deformation, considering only the effects of wave loads or hull deformation. This leads to significant deviations in fatigue life assessment results, making it impossible to accurately identify fatigue failure risks and consequently affecting the safe operation and service life of the FPSO structure.

[0004] In the existing technology, most studies on FPSO fatigue analysis focus on single load factors and lack a systematic consideration of the wave-hull deformation coupling effect; some coupling analysis methods only involve local degrees of freedom motion, failing to achieve full-dimensional coupling between six degrees of freedom motion and structural deformation, and are not practical enough for engineering applications, making it difficult to meet the needs of field applications.

[0005] Therefore, it is urgent to design a fatigue analysis method for the upper module of an FPSO based on the coupling effect to solve the problems mentioned above. Summary of the Invention

[0006] The purpose of this invention is to provide a fatigue analysis method for the top module of an FPSO based on the coupling effect, which aims to solve the problems of existing fatigue analysis methods for the top module of FPSO based on the coupling effect neglecting the coupling effect between wave motion and hull deformation, having low evaluation accuracy, and poor engineering practicality.

[0007] To achieve the above objectives, the specific technical solution of the fatigue analysis method for the FPSO upper module based on coupling effect of the present invention is as follows: A fatigue analysis method for the upper module of an FPSO based on coupling effects mainly includes the following steps: S1. Based on the wave direction analysis results of FPSO, key wave parameters in the operating sea area are selected, the original marine environmental monitoring data are reconstructed, and a wave load input dataset is generated. S2. Establish a correlation model between the wave propagation direction and the hull arch and sag deformation, couple the wave load data with the hull structure deformation data, and output the coupled load-deformation dataset. S3. Construct a coupled analysis model that includes the six-degree-of-freedom motion response of the hull. Input the coupled dataset from S2 into the model to generate stress data of key components of the upper module under coupled conditions. S4. Extract the stress amplitude of key components based on the hot spot stress calculation method, and calculate the cumulative fatigue damage value of key components by combining Miner's fatigue damage accumulation theory to obtain the fatigue response results of the upper module. S5. Based on the fatigue response results, identify high-risk fatigue nodes in the upper module and guide node design optimization.

[0008] Furthermore, in S1, the wave direction analysis results are based on on-site measured or numerically simulated sea conditions, simulating the distribution patterns of ships and wave directions under different incoming wave directions.

[0009] Furthermore, key wave parameters include wave height, period, and propagation direction.

[0010] Furthermore, in S2, the data on the hull arch and sag deformations are calculated using the finite element model of the hull structure, and the coupling process uses linear interpolation to achieve a quantitative correlation between wave loads and hull deformation.

[0011] Furthermore, in S3, the coupled analysis model integrates the wave calculation module and the finite element structural analysis module to achieve real-time interaction between the hull motion parameters and the deformation data of the superstructure.

[0012] Furthermore, in S4, the hot spot stress calculation is determined by linear extrapolation; the cumulative fatigue damage calculation is introduced into the SN curve correction factor, which is adjusted according to the component material properties and marine environmental corrosion conditions.

[0013] A fatigue analysis system for an FPSO upper module includes: The data reconstruction module is used for filtering and reconstructing wave environment data; The coupling processing module is used to couple wave loads with hull deformation data; The model calculation module is used to construct a six-degree-of-freedom motion response coupling analysis model and output stress time history data; The fatigue analysis module is used to calculate hot spot stress and cumulative fatigue damage. The results output module is used to generate fatigue response reports and guide node design optimization.

[0014] The fatigue analysis method for the FPSO upper module based on coupling effect of the present invention has the following advantages: (1) This invention realizes the full-dimensional correlation between wave motion and hull deformation by reconstructing wave environment data and coupling wave-deformation data, breaking through the limitation of traditional analysis that ignores the coupling effect and greatly improving the accuracy of fatigue life assessment of FPSO upper module.

[0015] (2) The coupled analysis model constructed in this invention takes into account both the six-degree-of-freedom motion response and structural deformation, accurately characterizes the dynamic coupling mechanism, and combines hot spot stress calculation and fatigue damage accumulation theory to form an integrated analysis technology that has both accuracy and engineering applicability.

[0016] (3) This invention can effectively identify high-risk fatigue nodes in the upper module, guide node design optimization, provide reliable technical support for safe operation and maintenance and life extension of FPSO structure, and has significant engineering application value. Attached Figure Description

[0017] Figure 1 This is a diagram of the coupling analysis model architecture of the present invention; Figure 2 This is a flowchart illustrating the technical process of the fatigue analysis method for the upper module of an FPSO based on coupling effect according to the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0020] The following is a reference to the appendix. Figure 1 To be continued Figure 2 This invention describes a fatigue analysis method for the upper module of an FPSO based on coupling effects.

[0021] The fatigue analysis method for the FPSO upper module based on coupling effect in this invention mainly includes the following steps: S1. Based on the wave direction analysis results of FPSO, key wave parameters in the operating sea area are selected, the original marine environmental monitoring data are reconstructed, and a wave load input dataset is generated. In S1, the wave direction analysis results are based on on-site measured or numerically simulated sea conditions, simulating the distribution patterns of ships and wave directions under different incoming wave directions; key wave parameters include wave height, period, and propagation direction. The wave environment data reconstruction mentioned refers to the process of reconstructing the original marine environmental monitoring data based on the wave direction analysis results of FPSO, selecting key wave parameters (wave height, period, and propagation direction) in the operating sea area, and generating a wave load input dataset that matches the actual sea area.

[0022] S2. Establish a correlation model between the wave propagation direction and the hull arch and sag deformation, couple the wave load data with the hull structure deformation data, and output the coupled load-deformation dataset. In S2, the hull arch and sag deformation data are calculated through the hull structure finite element model. The coupling process uses linear interpolation to achieve a quantitative correlation between wave load and hull deformation. The wave-hull deformation data coupling mentioned refers to establishing a correlation model between the wave propagation direction and the hull arching and sagging deformation. Based on the correspondence between wave direction and hull deformation, wave load data is coupled with hull structural deformation data to output the coupled load-deformation dataset.

[0023] S3. Construct a coupled analysis model that includes the six-degree-of-freedom motion response of the hull. Input the coupled dataset from S2 into the model to generate stress data of key components of the upper module under coupled conditions. In S3, the coupled analysis model integrates the wave calculation module and the finite element structural analysis module to achieve real-time interaction between the hull motion parameters and the deformation data of the superstructure. The aforementioned coupled analysis model refers to the construction of a coupled analysis model that includes the six-degree-of-freedom motion response of the hull. The coupled dataset from step S2 is input into the model to simulate the dynamic correlation between the hull motion and the deformation of the superstructure under wave loads, and to generate stress time history data of key components of the superstructure under coupled conditions.

[0024] S4. Extract the stress amplitude of key components based on the hot spot stress calculation method, and calculate the cumulative fatigue damage value of key components by combining Miner's fatigue damage accumulation theory to obtain the fatigue response results of the upper module. In S4, hot spot stress calculation is determined by linear extrapolation; fatigue damage accumulation calculation is introduced into the SN curve correction factor, which is adjusted according to the component material properties and marine environmental corrosion conditions. The fatigue response analysis mentioned refers to extracting the stress amplitude of key components based on the hot spot stress calculation method, and calculating the cumulative fatigue damage value of key components by combining Miner's fatigue damage accumulation theory, so as to obtain the fatigue response results of the upper module.

[0025] S5. Based on the fatigue response results, identify high-risk fatigue nodes in the upper module and guide node design optimization; The engineering application guidance mentioned refers to identifying high-risk fatigue nodes of the upper module based on fatigue response results, guiding node design optimization, and improving the fatigue life of the FPSO upper module structure.

[0026] As a preferred embodiment: When reconstructing wave environment data: collect marine environmental monitoring data for one year in the FPSO operation area. Based on the wave direction distribution results, the angle between the wave and the bow is mainly within the range of ±30°. The wave load input dataset is then reconstructed. When coupling wave-deformation data: establish a correlation model between northeast-oriented waves and hull mid-sag deformation, calculate the hull mid-sag deformation as 12mm through finite element method, and use linear interpolation to couple wave load data with deformation data to output coupled dataset; When constructing the coupled analysis model: Construct a coupled analysis model that includes the six degrees of freedom motion of the hull. After inputting the coupled dataset, simulate the stress time history data of the manifold support node of the upper module. The stress amplitude range is 120-180 MPa. During fatigue response analysis: the hot spot stress of the manifold support node was calculated using the linear extrapolation method. Combined with the SN curve (material is Q345 steel, SN curve parameters m=3, C=1.0×1012), the cumulative fatigue damage value was calculated to be 0.28 based on Miner's theory. When guiding engineering applications: Based on the fatigue response results, the node is identified as a high-risk fatigue area. The node structure is optimized (by adding rounded transitions and increasing the radius from 10mm to 20mm). After optimization, the stress amplitude of the node is reduced to 100-150MPa, the cumulative fatigue damage value is reduced to 0.15, and the fatigue life is increased by 18%.

[0027] This application discloses a fatigue analysis system for the upper module of an FPSO, comprising: The data reconstruction module is used for filtering and reconstructing wave environment data; The coupling processing module is used to couple wave loads with hull deformation data; The model calculation module is used to construct a six-degree-of-freedom motion response coupling analysis model and output stress time history data; The fatigue analysis module is used to calculate hot spot stress and cumulative fatigue damage. The results output module is used to generate fatigue response reports and guide node design optimization.

[0028] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A fatigue analysis method for the upper module of an FPSO based on coupling effects, characterized in that, The main steps include: S1. Based on the wave direction analysis results of FPSO, key wave parameters in the operating sea area are selected, the original marine environmental monitoring data are reconstructed, and a wave load input dataset is generated. S2. Establish a correlation model between the wave propagation direction and the hull arch and sag deformation, couple the wave load data with the hull structure deformation data, and output the coupled load-deformation dataset. S3. Construct a coupled analysis model that includes the six-degree-of-freedom motion response of the hull. Input the coupled dataset from S2 into the model to generate stress data of key components of the upper module under coupled conditions. S4. Extract the stress amplitude of key components based on the hot spot stress calculation method, and calculate the cumulative fatigue damage value of key components by combining Miner's fatigue damage accumulation theory to obtain the fatigue response results of the upper module. S5. Based on the fatigue response results, identify high-risk fatigue nodes in the upper module and guide node design optimization.

2. The fatigue analysis method for FPSO upper module based on coupling effect according to claim 1, characterized in that, In S1, the wave direction analysis results are based on on-site measurements or numerical simulations of sea conditions, simulating the distribution patterns of ships and wave directions under different incoming wave directions.

3. The fatigue analysis method for FPSO upper module based on coupling effect according to claim 2, characterized in that, in, Key wave parameters include wave height, period, and propagation direction.

4. The fatigue analysis method for FPSO upper module based on coupling effect according to claim 1, characterized in that, In S2, the data on the hull arch and sag deformation are obtained by calculating the hull structure finite element model. The coupling process uses linear interpolation to achieve a quantitative correlation between wave load and hull deformation.

5. The fatigue analysis method for FPSO upper module based on coupling effect according to claim 1, characterized in that, In S3, the coupled analysis model integrates the wave calculation module and the finite element structural analysis module to achieve real-time interaction between the hull motion parameters and the deformation data of the superstructure.

6. The fatigue analysis method for FPSO upper module based on coupling effect according to claim 1, characterized in that, In S4, hot spot stress calculation is determined by linear extrapolation; fatigue damage accumulation calculation is introduced into the SN curve correction factor, which is adjusted according to the component material properties and marine environmental corrosion conditions.

7. A fatigue analysis system for FPSO upper modules based on coupling effects, comprising the fatigue analysis method for FPSO upper modules based on coupling effects as described in any one of claims 1-6, characterized in that, include: The data reconstruction module is used for filtering and reconstructing wave environment data; The coupling processing module is used to couple wave loads with hull deformation data; The model calculation module is used to construct a six-degree-of-freedom motion response coupling analysis model and output stress time history data; The fatigue analysis module is used to calculate hot spot stress and cumulative fatigue damage. The results output module is used to generate fatigue response reports and guide node design optimization.

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