CN111859559A - Dynamic characteristic analysis method of soft steel arm single-point mooring system - Google Patents

Dynamic characteristic analysis method of soft steel arm single-point mooring system Download PDF

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CN111859559A
CN111859559A CN202010623008.9A CN202010623008A CN111859559A CN 111859559 A CN111859559 A CN 111859559A CN 202010623008 A CN202010623008 A CN 202010623008A CN 111859559 A CN111859559 A CN 111859559A
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point
steel arm
mooring system
point mooring
arm single
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李开宇
吴国东
彭柳
曹光明
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Wuhan No 2 Ship Design Institute No 719 Research Institute of China Shipbuilding Industry Corp
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Wuhan No 2 Ship Design Institute No 719 Research Institute of China Shipbuilding Industry Corp
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M10/00—Hydrodynamic testing; Arrangements in or on ship-testing tanks or water tunnels
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F18/00—Pattern recognition
    • G06F18/20—Analysing
    • G06F18/23—Clustering techniques
    • G06F18/232—Non-hierarchical techniques
    • G06F18/2321—Non-hierarchical techniques using statistics or function optimisation, e.g. modelling of probability density functions
    • G06F18/23213—Non-hierarchical techniques using statistics or function optimisation, e.g. modelling of probability density functions with fixed number of clusters, e.g. K-means clustering
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/27—Design optimisation, verification or simulation using machine learning, e.g. artificial intelligence, neural networks, support vector machines [SVM] or training a model
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/04—Constraint-based CAD
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

Abstract

The application relates to a dynamic characteristic analysis method of a soft steel arm single-point mooring system, which relates to the technical field of marine nuclear power platform positioning, wherein the soft steel arm single-point mooring system is used for positioning a marine nuclear power platform, and the dynamic characteristic analysis method comprises the following steps: establishing a multi-body dynamic model of the soft steel arm single-point mooring system by using the design parameters of the soft steel arm single-point mooring system, and carrying out mechanical analysis to obtain a dynamic equation of the multi-body dynamic model; screening out sea condition parameters of a specific sea condition to be faced by the marine nuclear power platform by using ship FPSO historical monitoring data of a target sea area where the marine nuclear power platform is arranged; and taking the sea condition parameters as the external force conditions of the dynamic equation to obtain the dynamic characteristics of the soft steel arm single-point mooring system under the specific sea condition. The dynamic characteristic analysis method of the soft steel arm single-point mooring system can truly describe the dynamic characteristic of the soft steel arm mooring system in the service process.

Description

Dynamic characteristic analysis method of soft steel arm single-point mooring system
Technical Field
The application relates to the technical field of marine nuclear power platform positioning, in particular to a dynamic characteristic analysis method of a soft steel arm single-point mooring system.
Background
At present, the fault rate of a positioning system in the domestic maritime work field is high, and related safety guarantee measures are lacked. The marine nuclear power platform belongs to a nuclear-involved platform, and the operation stability and the safety of the marine nuclear power platform are particularly important, which puts high requirements on the safety performance of a positioning system of the marine nuclear power platform.
In the related art, a conventional marine nuclear power platform positioning system is a multi-hinged marine engineering structure and is a typical multi-body system; specifically, the marine nuclear power platform positioning system adopts a soft rigid arm single-point mooring system. For multi-body dynamic analysis of a soft rigid arm single-point mooring system, a hydrodynamic simulation method and a pool model test method are generally adopted.
However, due to the complexity of marine load in time and space and the nonlinear multi-hinge connection of the soft rigid arm mooring structure, the dynamic characteristics of the soft rigid arm mooring system in the service process cannot be truly described by using hydrodynamic simulation and pool model experiments.
Disclosure of Invention
The embodiment of the application provides a dynamic characteristic analysis method of a soft steel arm single-point mooring system, which can truly describe the dynamic characteristic of the soft steel arm mooring system in the service process.
The invention provides a dynamic characteristic analysis method of a soft steel arm single-point mooring system, which comprises the following steps:
establishing a multi-body dynamic model of the soft steel arm single-point mooring system by using the design parameters of the soft steel arm single-point mooring system, and carrying out mechanical analysis to obtain a dynamic equation of the multi-body dynamic model;
screening out sea condition parameters of a specific sea condition to be faced by the marine nuclear power platform by using ship FPSO historical monitoring data of a target sea area where the marine nuclear power platform is arranged; and taking the sea condition parameters as the external force conditions of the dynamic equation to obtain the dynamic characteristics of the soft steel arm single-point mooring system under the specific sea condition.
In some embodiments, the mild steel arm single point mooring system comprises a plurality of single bodies, and the method for establishing the multi-body dynamic model comprises the following steps:
marking the single bodies and the hinge points among the single bodies, and converting the single-point mooring system of the mild steel arm into a topological structure diagram according to the connection relation of the single bodies;
and selecting a hinge point in the topological structure diagram for cutting off, and converting the topological structure diagram of the closed-loop multi-body system into a derivative tree system consisting of the single bodies and the hinge point.
In some embodiments, the method of deriving the pivot vectors for each hinge point comprises the steps of:
according to the derived tree system, combining the sea condition parameters, defining generalized coordinate vectors of all hinge points of the derived tree system and a satellite coordinate system of each monomer;
obtaining the coordinates of the mass center of each monomer in the derivative tree system in a satellite coordinate system by taking a single-point turret in the mild steel arm mooring system as a base point; and calculating the rotating shaft vector of each hinge point according to the generalized coordinate vector of each hinge point and the coordinate of the mass center of each monomer in the satellite coordinate system.
In some embodiments, the method of calculating the dynamic equation of the mild steel arm single point mooring system comprises the steps of:
calculating a position vector of each single mass center based on the single-point turret according to the derived tree system;
according to the position vector of each monomer mass center, combining the zero slip freedom degree of the cut-off hinge point, and listing a relative displacement constraint equation matrix expression of the soft steel arm single-point mooring system;
and converting the relative displacement constraint equation matrix expression into a constraint equation Jacobian matrix expression, and combining the rotating shaft vector, the design parameters and the virtual power principle to obtain a dynamic equation of the soft steel arm single-point mooring system.
In some embodiments, the topological structure diagram comprises 5 monomers, each being a single-point turret O0Soft rigid arm O1Left mooring leg O2Right mooring leg O3And mooring support O4Said O is1Are hinged to O respectively0、O2And O3Said O is3Are hinged to O respectively1And O4Said O is2Are hinged to O respectively1And O4(ii) a The soft rigid arm is also denoted as YOKE, and the soft rigid arm single-point mooring system also comprises 5 hinge points which are O respectively0And O1Hinge point H1YOKE and O2Hinge point H2、O1And O3Hinge point H3、O4And O3Hinge point H4、O4And O2Hinge point H5。
In some embodiments, the method of calculating the pivot vectors of the respective hinge points comprises the steps of:
selecting H5Cutting off the hinge point to generate a derivative tree system consisting of the monomers and the hinge point;
according to the derived tree system, by combining with sea condition parameters, defining the generalized coordinate vector Q of each hinge point of the derived tree system and the satellite coordinates of the mass center of each monomer in a satellite coordinate system:
Q＝[q11,q12,q13,q21,q22,q31,q32,q41,q42,q43]
wherein (q)11,q12,q13) Is a hinge point H1Rotation angle in three degrees of freedom, (q)21,q22)，(q31,q32) Are respectively a hinge H2、H3Rotation angle in two degrees of freedom, (q)41,q42,q43) Is H4Angle of rotation in three degrees of freedom；
The satellite coordinates of the mass center of each monomer in the satellite coordinate system are respectively H 1The coordinates are
Figure BDA0002563695860000031
H2Has the coordinates of
Figure BDA0002563695860000032
H3Has the coordinates of
Figure BDA0002563695860000033
H4Has the coordinates of
Figure BDA0002563695860000034
Calculating rotating shaft vectors P1, P2, P3 and P4 of each hinge point by combining the satellite coordinates and Q of the mass center of each monomer in the satellite coordinate system;
Figure BDA0002563695860000035
Figure BDA0002563695860000036
Figure BDA0002563695860000041
Figure BDA0002563695860000042
wherein s and c are sine and cosine symbols, (g)1、g2、g3) Is a base vector of a geodetic coordinate system in a random coordinate system.
In some embodiments, the method of calculating a single turret-referenced position vector for each cell centroid comprises the steps of:
let r be1、r2、r3And r4Are respectively H1、H2、H3、H4Quality of (1)The vector of the position of the heart is,
r1＝-C10
r2＝r1+C12-C21
r3＝r1+C13-C31
r4＝r3+C34-C43
wherein, CijI is more than or equal to 1 and less than or equal to 4, and j is more than or equal to 1 and less than or equal to 4.
In some embodiments, calculating the expression of the jacobian matrix of the constraint equations comprises the steps of:
is provided with h5＝r4+C42-r2-C24For cutting off the relative displacement of the hinge point, the relative displacement constraint equation matrix expression is
Figure BDA0002563695860000043
The expression of converting the constraint equation into a constraint equation Jacobian matrix is
Figure BDA0002563695860000044
Wherein phi5To constrain the Jacobian matrix, t5Is the acceleration caused by the generalized velocity,
Figure BDA0002563695860000045
is the result of Q two derivatives over time, which represents the rotational acceleration of the respective hinge point.
In some embodiments, the dynamic equation of the mild steel arm single-point mooring system is
Figure BDA0002563695860000046
Where M is the mass M of each monomer in accordance with the design parameters iThe generalized mass matrix of the soft steel arm single-point mooring system is obtained through conversion; λ is a coefficient of measure which passes through the rotation axis vectors P1, P2, P3,P4、r1、r2、r3、r4、C10、C12、C21、C13、C31、C34And C43Obtaining the product through conversion;
f is a generalized mass matrix of the single-point mooring system with the mild steel arm,
Figure BDA0002563695860000051
Fi αfor the inertial force of each monomer, Mi αFor the moment of inertia of the individual units, JiG is the acceleration of gravity, which is the tensor of moment of inertia of each cell.
In some embodiments, the step of cluster analyzing comprises:
a large amount of historical monitoring data of the FPSO comprises a plurality of data objects, and K data objects are selected as initial clustering centers; k is more than or equal to 2;
dividing each data object into nearest cluster centers according to Euclidean distance between each data object and each cluster center and a nearest principle to form K clusters; assigning each data object to a respective cluster;
and updating the clustering center according to the mean values corresponding to all the data objects in the current cluster, judging whether the clustering center is changed or not, if not, outputting the result, and if so, updating the clustering center according to the nearest principle.
The beneficial effect that technical scheme that this application provided brought includes:
the embodiment of the application provides a dynamic characteristic analysis method of a soft steel arm single-point mooring system, which comprises the steps of establishing a multi-body dynamic model of the soft steel arm single-point mooring system by using design parameters of the soft steel arm single-point mooring system, and calculating to obtain a dynamic equation; screening out sea condition parameters of a specific sea condition faced by an ocean nuclear power platform by using historical monitoring data of an FPSO (Floating Production, Storage and Offloading Unit, offshore Floating Production, Storage and Offloading Unit) of a target sea area; inputting the sea condition parameters into a dynamic equation to obtain the stress condition of each hinge point of the soft steel arm single-point mooring system under a specific sea condition; compared with the traditional hydrodynamic simulation and pool model experiment method, the dynamic characteristic analysis method based on the sea condition parameters can more truly describe the dynamic characteristic of the soft rigid arm single-point mooring system in the service process, and provides powerful support for the design and safe operation strategy of the marine nuclear power platform positioning system.
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In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a flowchart of a method for analyzing dynamic characteristics according to an embodiment of the present disclosure.
Fig. 2 is a topological structure diagram of a mild steel arm single-point mooring system provided in the embodiment of the present application.
Fig. 3 is a centroid position and a body axis vector diagram of the mild steel arm single-point mooring system provided in the embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
As shown in fig. 1, according to an embodiment of the present application, a method for analyzing a dynamic characteristic of a mild steel arm single-point mooring system, where the mild steel arm single-point mooring system is used for positioning an offshore nuclear power platform, includes the following steps:
and establishing a multi-body dynamic model by using the design parameters of the soft steel arm single-point mooring system which is already designed but not built, and carrying out mechanical analysis to obtain a dynamic equation of the multi-body dynamic model.
Screening out sea condition parameters of a specific sea condition to be faced by the marine nuclear power platform by using FPSO historical monitoring data of a ship in a target sea area where the marine nuclear power platform is arranged; the sea condition parameters are substituted into the dynamic equation as the external force conditions of the dynamic equation to obtain the dynamic characteristics of the soft steel arm single-point mooring system under the specific sea condition, and reference is provided for the design and safe operation of the soft steel arm single-point mooring system.
In particular, the single point mooring system with the mild steel arm is a multi-hinged ocean engineering structure and is a typical multi-body system.
Further, the mild steel arm single-point mooring system comprises a plurality of single bodies, and the method for establishing the multi-body dynamic model comprises the following steps: marking the single bodies and the hinge points among the single bodies respectively, and converting the single-point mooring system with the mild steel arm into a topological structure diagram according to the connection relation of the single bodies; and then selecting a hinge point from the topological structure chart as a cutting hinge point to cut off, and converting the topological structure chart of the closed-loop multi-body system into a derivative tree system consisting of the single body and the hinge point. The derivative tree system can be used as a multi-body dynamic model of the single-point mooring system with the soft steel arm.
In one embodiment of the present application, the method of deriving the pivot vectors for the respective hinge points comprises the steps of:
according to the derived tree system, the generalized coordinate vectors of all hinge points of the derived tree system and the satellite coordinate systems of all the monomers are defined by combining sea condition parameters.
Obtaining the coordinates of the mass center of each monomer in the derivative tree system in a coordinate system with the monomer brick tower in the mild steel arm mooring system as a base point; and calculating the rotating shaft vector of each hinge point according to the generalized coordinate vector of each hinge point and the coordinate of the mass center of each monomer in the satellite coordinate system.
Preferably, the sea state parameters include a maximum wind speed, a maximum roll angle of each cell, a maximum pitch distance of each cell, and the like.
Further, the method for calculating the dynamic equation of the single-point mooring system with the mild steel arm comprises the following steps:
calculating the position vector of each monomer mass center by taking the monomer brick tower as a reference according to a derivative tree system;
according to the position vector of each monomer mass center, combining that the slip freedom degree of a cut-off hinge point is zero, and listing a relative displacement constraint equation matrix expression of the soft steel arm single-point mooring system;
and converting the relative displacement constraint equation matrix expression into a constraint equation Jacobian matrix expression, and combining the rotating shaft vector, the design parameters and the virtual power principle to obtain a dynamic equation of the soft steel arm single-point mooring system.
As shown in FIG. 2, in one embodiment of the present application, the topological structure diagram comprises 5 single units, each being a single-point turret O0Soft rigid arm O1Left mooring leg O2Right mooring leg O3And mooring support O4，O1Are hinged to O respectively0、O2And O3，O3Are hinged to O respectively1And O4，O2Are hinged to O respectively1And O4(ii) a The soft rigid arm is also denoted as YOKE, and the soft rigid arm single-point mooring system also comprises 5 hinge points which are O respectively0And O1Hinge point H1YOKE and O2Hinge point H2、O1And O3Hinge point H3、O4And O3Hinge point H4、O4And O2Hinge point H5。
In one embodiment of the present application, as shown in FIG. 3, H is selected5In order to cut off the hinge points, the method for calculating the rotating shaft vector of each hinge point comprises the following steps:
and converting the topological structure chart of the closed-loop multi-body system into an open-loop spanning tree system.
According to the derived tree system, combining with sea condition parameters, defining the generalized coordinate vector Q of each hinge point of the derived tree system and the satellite coordinates of the mass center of each monomer in a satellite coordinate system:
Q＝[q11,q12,q13,q21,q22,q31,q32,q41,q42,q43]
wherein (q)11,q12,q13) Is a hinge point H1Rotation angle in three degrees of freedom, (q)21,q22)，(q31,q32) Are respectively a hinge H2、H3Rotation angle in two degrees of freedom, (q)41,q42,q43) Is H4Rotation angles in three degrees of freedom.
The satellite coordinates of the mass center of each monomer in the satellite coordinate system are respectively H 1The coordinates are
Figure BDA0002563695860000081
H2Has the coordinates of
Figure BDA0002563695860000082
H3Has the coordinates of
Figure BDA0002563695860000083
H4Has the coordinates of
Figure BDA0002563695860000084
In FIG. 3, H1、H2、H3、H4The upper corner marks of the coordinates are all abbreviated, YOKE is abbreviated as Y, LLEG is abbreviated as L, RLEG is abbreviated as R, and FPSO is abbreviated as F.
Calculating rotating shaft vectors P1, P2, P3 and P4 of each hinge point by combining the satellite coordinates and Q of the mass center of each monomer in the satellite coordinate system;
Figure BDA0002563695860000091
Figure BDA0002563695860000092
Figure BDA0002563695860000093
Figure BDA0002563695860000094
wherein s and c are sine and cosine symbols, (g)1、g2、g3) Is a base vector of a geodetic coordinate system in a random coordinate system.
In one embodiment of the present application, a method of calculating a location vector referenced to each monolithic centroid monolithic brick tower comprises the steps of:
let r be1、r2、r3And r4Are respectively H1、H2、H3、H4The vector of the position of the center of mass of,
r1＝-C10
r2＝r1+C12-C21
r3＝r1+C13-C31
r4＝r3+C34-C43
wherein, CijI is more than or equal to 1 and less than or equal to 4, and j is more than or equal to 1 and less than or equal to 4. Specifically, C10Represents O1To its center of mass and O0The body hinge vector of the joint, C12Represents O1To its center of mass and O2The body hinge vector of the joint, C21Represents O2To its center of mass and O1The body hinge vector of the joint, C13Represents O1To its center of mass and O3The body hinge vector of the joint, C31Represents O3To its center of mass and O1The body hinge vector of the joint, C34Represents O3To its center of mass and O4The body hinge vector of the joint, C 43Represents O4To its center of mass and O3The body hinge vector of the joint.
Further, the calculation of the expression of the jacobian matrix of the constraint equation comprises the following steps:
is provided with h5＝r4+C42-r2-C24For the relative displacement of the cut-off hinge point, the cut-off hinge point can only rotate but cannot move, and the relative displacement constraint equation matrix expression of the cut-off hinge point is
Figure BDA0002563695860000101
The expression of converting the constraint equation into a constraint equation Jacobian matrix is
Figure BDA0002563695860000102
Wherein phi5To constrain the Jacobian matrix, t5Is the acceleration caused by the generalized velocity,
Figure BDA0002563695860000103
is the result of Q two derivatives over time, which represents the rotational acceleration of the respective hinge point.
In particular,. phi5Is calculated by the formula
Figure BDA0002563695860000104
Figure BDA0002563695860000105
The matrix of the Jacobian is obtained,
Figure BDA0002563695860000106
which is equal to the beam Jacobian matrix phi5The meaning of the representation differs.
Wherein, t5Is calculated by the formula
Figure BDA0002563695860000107
Figure BDA0002563695860000108
Wherein the content of the first and second substances,
Figure BDA0002563695860000109
Figure BDA00025636958600001010
represents h5A first derivative of (a) is obtained,
Figure BDA00025636958600001011
represents H5Relative displacement with respect to O0The slip speed of (d);
wherein alpha is1、α2、α3And alpha4Each represents O1、O2、O3、O4Speed of movement of beta2And beta4Each represents O2、O4The rotational angular velocity of (a); sigma2And σ4Each represents O2、O4The acceleration of motion of; w is a2And w4By alpha1、α2、α3、α4And
Figure BDA00025636958600001012
is converted out ofiRepresenting the mass center acceleration of each monomer when the change rate of the generalized speed of the system is 0; alpha is alphai、βi、σiAnd wiThrough rotating shaft vectors P1, P2, P3, P4 and r 1、r2、r3、r4、C10、C12、C21、C13、C31、C34And C43Obtaining the product through conversion; omegaiIndicating the angular speed of rotation of each cell.
Further, the dynamic equation of the single point mooring system with the mild steel arm is
Figure BDA0002563695860000111
Where M is the mass M of each monomer in accordance with the design parametersiThe generalized mass matrix of the soft steel arm single-point mooring system is obtained through conversion; λ is a metering coefficient passing through the rotation axis vectors P1, P2, P3, P4, r1、r2、r3、r4、C10、C12、C21、C13、C31、C34And C43And (4) obtaining the compound through conversion.
F is a generalized mass matrix of the single-point mooring system with the mild steel arm,
Figure BDA0002563695860000112
Fi αfor the inertial force of each monomer, Mi αFor the moment of inertia of the individual units, JiG is the acceleration of gravity, which is the tensor of moment of inertia of each cell.
In one embodiment, the cluster analysis comprises the steps of:
a large amount of historical monitoring data of the FPSO comprises a plurality of data objects, and K data objects are selected as initial clustering centers; k is more than or equal to 2;
dividing each data object into nearest cluster centers according to Euclidean distance between each data object and each cluster center and a nearest principle to form K clusters; assigning each data object to a respective cluster;
updating the clustering center according to the mean values corresponding to all the data objects in the current cluster, judging whether the clustering center is changed or not, if not, outputting the result to form K data sets, and if so, updating the clustering center according to the nearest principle until all the data are completely distributed to form K data sets. Each data set represents a sea state, and the K data sets respectively represent a plurality of typical sea states, wherein the typical sea states comprise a stationary sea state, a high wind sea state, a storm sea state and the like.
The implementation background of the method for analyzing the dynamic characteristics of the soft steel arm single-point mooring system provided by the embodiment of the application is that the marine nuclear power platform is not built yet but designed, and the marine nuclear power platform cannot obtain the dynamic equation of the dynamic characteristic model of the marine nuclear power platform positioning system according to the self-measured sea state data.
The embodiment of the application utilizes historical monitoring data of similar water displacement FPSO of the same target sea area as input conditions; due to the fact that the FPSO is long in service time, the historical monitoring data volume is large, the water displacement of the FPSO is close to that of the ocean nuclear power platform, and the historical monitoring data of the FPSO can be used for researching the ocean nuclear power platform. According to the method, a multi-body dynamic model of the soft steel arm single-point mooring system is established by using design parameters of the soft steel arm single-point mooring system, and a dynamic equation is calculated; screening out sea condition parameters of a specific sea condition to be faced by the marine nuclear power platform by using FPSO historical monitoring data of a target sea area; inputting the sea condition parameters into a dynamic equation to obtain the stress condition of each hinge point of the soft steel arm single-point mooring system under a specific sea condition; compared with the traditional hydrodynamic simulation and pool model experiment method, the dynamic characteristic analysis method based on the sea condition parameters can more truly describe the dynamic characteristic of the soft rigid arm single-point mooring system in the service process, and provides powerful support for the design and safe operation strategy of the marine nuclear power platform positioning system.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A dynamic characteristic analysis method of a mild steel arm single-point mooring system, wherein the mild steel arm single-point mooring system is used for positioning an ocean nuclear power platform, and the dynamic characteristic analysis method comprises the following steps:
establishing a multi-body dynamic model of the soft steel arm single-point mooring system by using the design parameters of the soft steel arm single-point mooring system, and carrying out mechanical analysis to obtain a dynamic equation of the multi-body dynamic model;
screening out sea condition parameters of a specific sea condition to be faced by the marine nuclear power platform by using ship FPSO historical monitoring data of a target sea area where the marine nuclear power platform is arranged; and taking the sea condition parameters as the external force conditions of the dynamic equation to obtain the dynamic characteristics of the soft steel arm single-point mooring system under the specific sea condition.
2. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 1, wherein the mild steel arm single-point mooring system comprises a plurality of single bodies, and the method for establishing the multi-body dynamic model comprises the following steps:
marking the single bodies and the hinge points among the single bodies, and converting the single-point mooring system of the mild steel arm into a topological structure diagram according to the connection relation of the single bodies;
and selecting a hinge point in the topological structure diagram for cutting off, and converting the topological structure diagram of the closed-loop multi-body system into a derivative tree system consisting of the single bodies and the hinge point.
3. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 2, wherein the method for obtaining the rotation axis vector of each hinge point comprises the following steps:
according to the derived tree system, combining the sea condition parameters, defining generalized coordinate vectors of all hinge points of the derived tree system and a satellite coordinate system of each monomer;
obtaining the coordinates of the mass center of each monomer in the derivative tree system in a satellite coordinate system by taking a single-point turret in the mild steel arm mooring system as a base point; and calculating the rotating shaft vector of each hinge point according to the generalized coordinate vector of each hinge point and the coordinate of the mass center of each monomer in the satellite coordinate system.
4. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 3, wherein the method for calculating the dynamic equation of the mild steel arm single-point mooring system comprises the following steps:
calculating a position vector of each single mass center based on the single-point turret according to the derived tree system;
according to the position vector of each monomer mass center, combining the zero slip freedom degree of the cut-off hinge point, and listing a relative displacement constraint equation matrix expression of the soft steel arm single-point mooring system;
and converting the relative displacement constraint equation matrix expression into a constraint equation Jacobian matrix expression, and combining the rotating shaft vector, the design parameters and the virtual power principle to obtain a dynamic equation of the soft steel arm single-point mooring system.
5. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 4, wherein the method comprises the following steps: the topological structure chart comprises 5 monomers which are respectively a single-point turret O0Soft rigid arm O1Left mooring leg O2Right mooring leg O3And mooring support O4Said O is1Are hinged to O respectively0、O2And O3Said O is3Are hinged to O respectively1And O4Said O is2Are hinged to O respectively1And O4(ii) a The soft rigid arm is also denoted as YOKE, and the soft rigid arm single-point mooring system also comprises 5 hinge points which are O respectively 0And O1Hinge point H1YOKE and O2Hinge point H2、O1And O3Hinge point H3、O4And O3Hinge point H4、O4And O2Hinge point H5。
6. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 5, wherein the method for calculating the rotation axis vector of each hinge point comprises the following steps:
selecting H5Cutting off the hinge point to generate a derivative tree system consisting of the monomers and the hinge point;
according to the derived tree system, by combining with sea condition parameters, defining the generalized coordinate vector Q of each hinge point of the derived tree system and the satellite coordinates of the mass center of each monomer in a satellite coordinate system:
Q＝[q11,q12,q13,q21,q22,q31,q32,q41,q42,q43]
wherein (q)11,q12,q13) Is a hinge point H1Rotation angle in three degrees of freedom, (q)21,q22)，(q31,q32) Are respectively a hinge H2、H3Rotation angle in two degrees of freedom, (q)41,q42,q43) Is H4Rotation angles in three degrees of freedom;
the satellite coordinates of the mass center of each monomer in the satellite coordinate system are respectively H1The coordinates are
Figure FDA0002563695850000031
H2Has the coordinates of
Figure FDA0002563695850000032
H3Has the coordinates of
Figure FDA0002563695850000033
H4Has the coordinates of
Figure FDA0002563695850000034
Calculating rotating shaft vectors P1, P2, P3 and P4 of each hinge point by combining the satellite coordinates and Q of the mass center of each monomer in the satellite coordinate system;
Figure FDA0002563695850000035
Figure FDA0002563695850000036
Figure FDA0002563695850000037
Figure FDA0002563695850000038
wherein s and c are sine and cosine symbols, (g)1、g2、g3) Is a base vector of a geodetic coordinate system in a random coordinate system.
7. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 6, wherein the method for calculating the position vector of each single mass center based on the single-point turret comprises the following steps:
let r be1、r2、r3And r4Are respectively H1、H2、H3、H4The vector of the position of the center of mass of,
r1＝-C10
r2＝r1+C12-C21
r3＝r1+C13-C31
r4＝r3+C34-C43
wherein, CijI is more than or equal to 1 and less than or equal to 4, and j is more than or equal to 1 and less than or equal to 4.
8. The method of claim 7, wherein the step of calculating the expression of the jacobian matrix of the constraint equation comprises the steps of:
is provided with h5＝r4+C42-r2-C24For cutting off the relative displacement of the hinge point, the relative displacement constraint equation matrix expression is
Figure FDA0002563695850000041
The expression of converting the constraint equation into a constraint equation Jacobian matrix is
Figure FDA0002563695850000042
Wherein phi5To constrain the Jacobian matrix, t5Is the acceleration caused by the generalized velocity,
Figure FDA0002563695850000043
is the result of Q two derivatives over time, which represents the rotational acceleration of the respective hinge point.
9. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 8, wherein the dynamic equation of the mild steel arm single-point mooring system is
Figure FDA0002563695850000044
Where M is the mass M of each monomer in accordance with the design parameters iThe generalized mass matrix of the soft steel arm single-point mooring system is obtained through conversion; λ is a metering coefficient passing through the rotation axis vectors P1, P2, P3, P4, r1、r2、r3、r4、C10、C12、C21、C13、C31、C34And C43Obtaining the product through conversion;
f is a generalized mass matrix of the single-point mooring system with the mild steel arm,
Figure FDA0002563695850000045
Fi αfor the inertial force of each monomer, Mi αFor the moment of inertia of the individual units, JiG is the acceleration of gravity, which is the tensor of moment of inertia of each cell.
10. The method for analyzing the dynamic characteristics of the mild steel arm single-point mooring system according to claim 1, wherein a clustering analysis method is adopted to screen out the sea state parameters of the specific sea state faced by the marine nuclear power platform, and the clustering analysis step comprises:
a large amount of historical monitoring data of the FPSO comprises a plurality of data objects, and K data objects are selected as initial clustering centers; k is more than or equal to 2;
dividing each data object into nearest cluster centers according to Euclidean distance between each data object and each cluster center and a nearest principle to form K clusters; assigning each data object to a respective cluster;
and updating the clustering center according to the mean values corresponding to all the data objects in the current cluster, judging whether the clustering center is changed or not, if not, outputting the result, and if so, updating the clustering center according to the nearest principle.
CN202010623008.9A 2020-06-30 2020-06-30 Dynamic characteristic analysis method of soft steel arm single-point mooring system Pending CN111859559A (en)

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