A method and system for designing a keel beam of a segmented hydroelastic test model

Abstract

The application discloses a kind of keel beam design method and system of segmented hydroelasticity test model, belong to ship test technical field, wherein, the method includes: simulating the mass characteristics in each segment of the preset test segmented ship model using ordered discrete mass points;According to the ship model, the rectangular hollow section size of the continuous variable cross-section keel beam that simultaneously satisfies the similar vertical bending and horizontal bending inertia moment is determined;Using mass points and section size to establish the finite element connection model of keel beam and mass points;By opening several rectangular openings on the upper surface of keel beam to adjust the torsional stiffness of the whole ship model, then according to the modal analysis results of the finite element connection model, adjust the structure form of the upper surface of keel beam and the wall thickness of keel beam, to obtain the final keel beam size. The method standardizes the design of continuous variable cross-section keel beam that simultaneously satisfies the similar conditions of vertical bending, horizontal bending and torsion, so that the three-dimensional stiffness similar segmented hydroelasticity test model can be accurately and efficiently established based on the keel beam.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship test, in particular to a keel beam design method and system of a segmented hydroelastic test model which meets vertical bending similarity, horizontal bending similarity and torsional similarity at the same time. BACKGROUND

[0002] With the rapid development of shipping industry, modern ships gradually develop towards large scale, high speed and large outboard. In high sea state, slamming phenomenon caused by large amplitude ship wave relative motion is prone to occur, and the high frequency flutter response caused thereby increases the amplitude of nonlinear wave load and total cycle number suffered by the ship body, which threatens the structural strength of the large outboard ship, and has attracted great attention in the maritime industry.

[0003] At present, there are relatively mature test and numerical prediction methods for the vertical vibration problem of ship body slamming under head-on wave state, which can effectively cover most of the flutter response problems. However, recent research shows that under the combined influence of ship longitudinal motion and transverse motion, the slamming load under some oblique waves can reach or even exceed that under head-on wave. At this time, the slamming has obvious asymmetric characteristics, which not only causes strong vertical vibration of the ship body, but also causes torsional vibration of the ship beam.

[0004] From the current international published hydroelastic model test research, the hydroelastic test based on segmented model is the mainstream test research means. The main idea is to cut the test ship body shell into several segments (generally more than 4 segments) along the longitudinal direction, and the adjacent shell segments of the test ship body are connected by flexible members. The bending stiffness of the flexible member is equivalent to the bending stiffness of the actual ship at this position, so as to simulate the overall bending deformation of the ship body when subjected to external force through the deformation of the flexible structure. The use of continuous equivalent stiffness beam to connect each test ship model segment can achieve considerable advantage in the overall arrangement of the test ship model, which is conducive to the division of more segments of the test ship model, and is a mainstream means for the segmented hydroelastic test model at present. The design of equivalent stiffness keel beam for the segmented hydroelastic test model based on this method is the most important link, and the design of the keel beam will directly determine the simulation effect of the ship wave load response in the hydroelastic test.

[0005] For the torsional flutter response research of the ship body under oblique waves, it is required that the test ship model can simulate the vertical bending, horizontal bending and torsional characteristics of the actual ship at the same time. This poses a new challenge to the design of the keel beam, and a keel beam which can meet the vertical bending, horizontal bending and torsional similarity conditions at the same time is needed. However, research on this kind of problem has not yet formed a standardized segmented ship model multi-directional stiffness similarity keel beam design method. SUMMARY

[0006] The present application aims to solve at least one of the technical problems in the related art.

[0007] To this end, one object of the present application is to provide a keel beam design method for a segmented hydroelasticity test model, which can standardize the design of a continuously variable cross-section keel beam that meets the similar conditions of vertical bending, horizontal bending and torsion.

[0008] Another object of the present application is to provide a keel beam design system for a segmented hydroelasticity test model.

[0009] Still another object of the present application is to provide a computer device.

[0010] Still another object of the present application is to provide a non-transitory computer readable storage medium.

[0011] To achieve the above objects, one embodiment of the present application provides a keel beam design method for a segmented hydroelasticity test model, comprising the following steps: step S1, simulating the mass characteristics in each segment of a preset test segmented ship model by using ordered discrete mass points; step S2, determining the rectangular hollow cross-section size of a continuously variable cross-section keel beam that meets the similar conditions of vertical bending inertia moment and horizontal bending inertia moment according to the preset test segmented ship model; step S3, establishing a finite element connection model of the keel beam and the mass points by using the mass points and the rectangular hollow cross-section size; and step S4, adjusting the structure form of the upper surface of the keel beam and the wall thickness of the keel beam according to the finite element connection model of the keel beam and the mass points to obtain the final keel beam size.

[0012] The keel beam design method for a segmented hydroelasticity test model according to the embodiment of the present application serves the segmented hydroelasticity model test research under oblique waves, and can simulate the elastic deformation corresponding to three modes of vertical bending, horizontal bending and torsion for the equivalent stiffness keel beam design of a segmented hydroelasticity test ship model of a general ship type; based on the mass distribution characteristics of an actual ship body, a method is provided for accurately characterizing the mass characteristics of each segment by using a small number of discrete mass points; according to the positions of the keel beam and the discrete mass points, a connection method is provided for rigidly connecting the keel beam and the mass points, and the influence of the connection construction on the overall model mass is minimized; and according to the expected natural frequencies corresponding to the three modes, a keel beam design method is provided for adjusting the structure form and the specific size of the keel beam, so that the finally designed keel beam can meet the established requirements.

[0013] In addition, the keel beam design method for a segmented hydroelasticity test model according to the above embodiment of the present application can also have the following additional technical features:

[0014] Further, in one embodiment of the present application, the step S1 specifically comprises: a step S101 of determining the number and position of the segments of the preset test segmented ship model, and converting the mass characteristics of each ship model segment according to the similarity relationship, wherein the mass characteristics include mass, center of mass position and moment of inertia; a step S102 of using eight mass points with the same mass for each ship model segment, and setting the eight mass points with the same mass at eight vertices of a cuboid respectively, so that the center point coordinates of the cuboid are consistent with the center of mass position of each ship model segment; and a step S103 of adjusting the length, width and height of the cuboid so that the moment of inertia of the center point of the cuboid is equal to the moment of inertia of each ship model segment.

[0015] Further, in one embodiment of the present application, the step S2 specifically comprises: a step S201 of determining the vertical bending stiffness and horizontal bending stiffness at the cutout position of each ship model segment according to the vertical bending stiffness distribution and horizontal bending stiffness distribution of the preset test segmented ship model; a step S202 of converting the expected vertical bending inertia moment and expected horizontal bending inertia moment of the preset keel beam material at each cutout position according to the Young's modulus of the preset keel beam material; and a step S203 of ensuring that the inner wall size of the rectangular hollow cross section at the cutout position of each ship model segment remains consistent and unchanged, and adjusting the upper and lower wall thickness and the left and right wall thickness of each rectangular hollow cross section respectively, so that each rectangular hollow cross section simultaneously satisfies the expected vertical bending inertia moment and the expected horizontal bending inertia moment.

[0016] Further, in one embodiment of the present application, the step S3 specifically comprises: a step S301 of obtaining the coordinate information of the mass points of each ship model segment, placing the mass points in the structural finite element analysis software according to the coordinate information, and determining the relative position relationship between the preset test segmented ship model and the continuously variable cross-section keel beam; a step S302 of establishing a continuously rigid equivalent variable cross-section keel beam finite element model in the structural finite element analysis software according to the relative position relationship, in combination with the rectangular hollow cross section size at the cutout position of each ship model segment; and a step S303 of extending a plate unit from the outer surface of the continuously rigid equivalent variable cross-section keel beam finite element model at the midpoint position of each ship model segment, and connecting the plate unit with the mass points, to obtain a finite element connection model of the keel beam and the mass points.

[0017] Further, in one embodiment of the present application, in the step S3, the cross-sectional size of the keel beam in the length range between the centers of two adjacent ship model segments is consistent, and is consistent with the rectangular hollow cross section size at the cutout position shared by the two adjacent segments.

[0018] Further, in one embodiment of the present application, the step S4 specifically comprises: step S401, determining the first-order vertical natural frequency of vertical bending, the first-order horizontal natural frequency of horizontal bending and the first-order torsional natural frequency of torsion by modal analysis on the finite element connection model of the keel beam and the mass point through a structural finite element software; step S402, based on the finite element connection model of the keel beam and the mass point, according to the first-order torsional natural frequency, symmetrically opening a plurality of rectangular openings along the center longitudinal section of the keel beam on the upper surface of the keel beam, and increasing the thickness of the left and right walls and the upper and lower walls of the keel beam, to obtain an open keel beam connection model; step S403, performing modal analysis on the open keel beam connection model to obtain a new first-order vertical natural frequency of vertical bending, a new first-order horizontal natural frequency of horizontal bending and a new first-order torsional natural frequency of torsion, and determining whether they meet the expected target value, if not, adjusting the thickness of the keel beam or the size of the opening on the upper surface and iteratively executing the steps S401-S403 until the final keel beam size is obtained.

[0019] Further, in one embodiment of the present application, in the step S403, if the new first-order vertical natural frequency of vertical bending is greater than the expected target value, the thickness of the upper and lower walls of the keel beam is reduced, if the new first-order vertical natural frequency of vertical bending is less than the expected target value, the thickness of the upper and lower walls of the keel beam is increased, and the steps S401-S403 are iteratively executed until the final keel beam size is obtained; if the new first-order horizontal natural frequency of horizontal bending is greater than the expected target value, the thickness of the left and right walls of the keel beam is reduced, if the new first-order horizontal natural frequency of horizontal bending is less than the expected target value, the thickness of the left and right walls of the keel beam is increased, and the steps S401-S403 are iteratively executed until the final keel beam size is obtained; if the new first-order torsional natural frequency of torsion is greater than the expected target value, the width or length of the rectangular opening on the upper surface of the keel beam is increased, if the new first-order torsional natural frequency of torsion is less than the expected target value, the width or length of the rectangular opening on the upper surface of the keel beam is reduced, and the steps S401-S403 are iteratively executed until the final keel beam size is obtained.

[0020] To achieve the above object, another aspect of the present application provides a keel beam design system for a segmented hydroelasticity test model, comprising: a simulation mass characteristic module, configured to simulate mass characteristics in each segment of a preset test segmented ship model by using ordered discrete mass points; a determination rectangular hollow section size module, configured to determine rectangular hollow section sizes of a continuously variable cross-section keel beam that satisfy similar vertical bending inertia moment and horizontal bending inertia moment according to the preset test segmented ship model; a construction finite element connection module, configured to establish a finite element connection model of the keel beam and the mass points by using the mass points and the rectangular hollow section sizes; and a size adjustment module, configured to adjust a structure form of an upper surface of the keel beam and a wall thickness of the keel beam according to the finite element connection model of the keel beam and the mass points to obtain a final keel beam size.

[0021] The keel beam design system for the segmented hydroelasticity test model of the embodiment of the present application serves segmented hydroelasticity model test research under oblique waves, and can simulate elastic deformations corresponding to three modes of vertical bending, horizontal bending and torsion simultaneously for equivalent stiffness keel beam design of a segmented hydroelasticity test ship model of a general ship type. Based on mass distribution characteristics of an actual ship body, the embodiment provides a method that can accurately represent mass characteristics of each segment by using a small number of discrete mass points. According to positions of the keel beam and the discrete mass points, the embodiment provides a connection method that can rigidly connect the keel beam and the mass points and minimizes influences of connection construction on the overall model mass. According to expected natural frequencies corresponding to the three modes, the embodiment provides a keel beam design method that adjusts a structure form of the keel beam and specific sizes of the keel beam, so that the finally designed keel beam can meet the established requirements.

[0022] Still another aspect of the present application provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the keel beam design method for the segmented hydroelasticity test model as described in the above embodiments.

[0023] Still another aspect of the present application provides a non-transitory computer readable storage medium, having a computer program stored thereon, wherein the computer program is executable by a processor to implement the keel beam design method for the segmented hydroelasticity test model as described in the above embodiments.

[0024] Additional aspects and advantages of the present application will be made apparent by the following description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1is a flow chart of a keel beam design method of a segmented hydroelasticity test model according to an embodiment of the present application;

[0027] Figure 2 is a specific execution schematic diagram of a segmented hydroelasticity test model keel beam design method according to an embodiment of the present application;

[0028] Figure 3 is a segmented hull mass model feature accurate characterization by limited discrete points schematic diagram according to an embodiment of the present application;

[0029] Figure 4 is a rectangular hollow cross section equivalent corresponding hull cutout place section vertical and horizontal bending stiffness schematic diagram according to an embodiment of the present application;

[0030] Figure 5 is a rectangular hollow variable cross section keel beam and discrete mass point connection model schematic diagram according to an embodiment of the present application;

[0031] Figure 6 is a rectangular hollow variable cross section keel beam upper surface opening schematic diagram according to an embodiment of the present application;

[0032] Figure 7 is a rectangular hollow variable cross section keel beam and discrete mass point connection model modal analysis schematic diagram according to an embodiment of the present application;

[0033] Figure 8 is a segmented hydroelasticity test model first order modal shape simulation schematic diagram according to an embodiment of the present application;

[0034] Figure 9 is a segmented hydroelasticity test model keel beam design system structure schematic diagram according to an embodiment of the present application. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals are used throughout the drawings to refer to the same or like elements or elements having the same or similar functionality. The embodiments described below are exemplary and are intended to be illustrative of the present application and are not to be used to limit the present application.

[0036] The keel beam design method of a segmented hydroelasticity test model according to an embodiment of the present application and the system thereof will be described below with reference to the accompanying drawings. First, the keel beam design method of a segmented hydroelasticity test model according to an embodiment of the present application will be described with reference to the accompanying drawings.

[0037] Figure 1 is a flow chart of a keel beam design method of a segmented hydroelasticity test model according to an embodiment of the present application;

[0038] As Figure 1and 2 As shown, the keel beam design method of the segmented hydroelastic test model includes the following steps:

[0039] In step S1, ordered discrete mass points are used to simulate the mass characteristics of each segment of the preset test segmented ship model.

[0040] Furthermore, in one embodiment of the present invention, step S1 specifically includes:

[0041] Step S101, determining the number and position of the segments of the preset test segmented ship model, and converting the mass characteristics of each ship model segment according to the similarity relationship, wherein the mass characteristics include mass, center of mass position and moment of inertia;

[0042] Step S102: using eight mass points of the same mass for each ship model segment, and setting the eight mass points of the same mass to be located at eight vertices of a cuboid, so that the coordinates of the center point of the cuboid are consistent with the center of mass position of each ship model segment;

[0043] Step S103, adjusting the length, width and height of the cuboid so that the moment of inertia of the center point of the cuboid is equal to the moment of inertia of each ship model segment.

[0044] Specifically, based on the number and position of the segments of the segmented model determined in advance, the mass characteristics of the corresponding segmented ship model are converted through the similarity relationship for each ship model segment. According to the mass M of the segment, the mass m of 8 equivalent mass points with equal mass is obtained, which is calculated by the formula m = M / 8;

[0045] Then, for each ship model segment, eight mass points with the same mass are used to accurately characterize the mass characteristics of each ship model segment. The mass of each mass point is one-eighth of the segment mass. The eight mass points are located at the eight vertices of a rectangular parallelepiped, with the center of the rectangular parallelepiped aligned with the segment's center of mass. By adjusting the length, width, and height of the rectangular parallelepiped, the moment of inertia of the eight mass points about the center point is equal to that of the segment, thus achieving accurate characterization of the mass characteristics of each ship model segment.

[0046] For example, Figure 3 As shown, assuming that 8 mass points are located at the 8 vertices of a cuboid, the center of gravity of the 8 mass points is the coordinate of the midpoint of the cuboid, and the coordinate of the center of the cuboid is kept consistent with the center of gravity of the segment;

[0047] According to the moment of inertia of the segment itself I M xx, I M yy and I Mzz, calculate the length (2a), width (2b), and height (2c) of the cuboid so that the moment of inertia of the eight discrete mass points combined about the center of the cuboid is equal to the moment of inertia of the segment itself. The calculation formula is as follows:

[0048] I M xx=8·(b 2 +c 2 )·m

[0049] I M yy=8·(a 2 +c 2 )·m

[0050] I M zz=8·(a 2 +b 2 )·m

[0051] Steps S101 to S103 are performed on each ship model segment, thereby obtaining a simplified discrete mass point model of each segment.

[0052] In step S2, the rectangular hollow section size of the continuously variable cross-section keel beam that satisfies similar vertical bending inertia moments and horizontal bending inertia moments is determined according to a preset test segmented ship model.

[0053] Furthermore, in one embodiment of the present invention, step S2 specifically includes:

[0054] Step S201, determining the vertical bending stiffness and horizontal bending stiffness at the cutout position of each ship model segment according to the vertical bending stiffness distribution and horizontal bending stiffness distribution of the preset test segmented ship model;

[0055] Step S202, converting the expected vertical bending moment of inertia and the expected horizontal bending moment of inertia of the preset keel beam material at each incision position according to the Young's modulus of the preset keel beam material;

[0056] Step S203, based on the rectangular hollow section, ensure that the inner wall size of the rectangular hollow section at the cutout position of each ship model segment remains consistent and unchanged, and adjust the upper and lower wall thicknesses and left and right wall thicknesses of each rectangular hollow section respectively, so that each rectangular hollow section can simultaneously meet the expected vertical bending moment of inertia and the expected horizontal bending moment of inertia.

[0057] Specifically, if Figure 4 As shown in the figure, according to the vertical bending and horizontal bending stiffness distribution of the preset test segmented ship model, the specific vertical bending stiffness Stif at the segment cut position is determined. y and horizontal bending stiffness Stif z , among which Stif yStif z is the vertical bending stiffness of the cross section at the cutout location of the test ship model.

[0058] For each cutout location, the expected vertical bending moment of inertia I C and the expected horizontal bending moment of inertia I Cyy of the keel beam section at the cutout location are calculated according to the Young's modulus E Czz of the material of the keel beam of the test ship model.

[0059] Stif y = E C I Cyy

[0060] Stif z = E C I Czz

[0061] where λ is the scale ratio of the test ship model.

[0062] According to the determined expected vertical bending moment of inertia I Cyy and the expected horizontal bending moment of inertia I Czz of the keel beam section at the cutout location, the dimensions of the inner walls of the rectangular hollow section at all cutout locations are kept constant and unchanged, and the thicknesses of the upper, lower, left and right walls of the hollow section are adjusted so that the vertical bending moment of inertia and the horizontal bending moment of inertia of the section are within an acceptable error range of the expected values, based on a rectangular hollow section. The calculation formula of the rectangular hollow section moment of inertia is as follows:

[0063]

[0064]

[0065] where b is the width of the internal hollow rectangle, h is the height of the internal hollow rectangle, B is the width of the external rectangle of the section, and H is the height of the external rectangle of the section. The wall thickness of the rectangular hollow section can be calculated by the following formula (assuming that the left and right wall thicknesses are the same and the upper and lower wall thicknesses are the same):

[0066]

[0067]

[0068] where t v is the thickness of the left and right walls, and t h is the thickness of the upper and lower walls.

[0069] Step S2 is performed on all the segment cutouts to determine the specific cross-sectional size of the rectangular hollow cross-section keel beam at each cutout position. The keel beam thus designed can satisfy the similar conditions of vertical bending and horizontal bending stiffness.

[0070] In step S3, a finite element connection model of the keel beam and the mass points is established using the mass points and the rectangular hollow cross-sectional size.

[0071] Further, in an embodiment of the present application, step S3 specifically comprises:

[0072] Step S301, obtaining coordinate information of mass points of each ship model segment, placing the mass points in the structural finite element analysis software according to the coordinate information, and determining the relative position relationship between the pre-set test segment ship model and the continuous variable cross-section keel beam;

[0073] Step S302, according to the relative position relationship, and in combination with the rectangular hollow cross-sectional size at the cutout position of each ship model segment, a continuous stiffness equivalent variable cross-section keel beam finite element model is established in the structural finite element analysis software;

[0074] Step S303, at the midpoint position of each ship model segment, a plate element is extended from the outer surface of the continuous stiffness equivalent variable cross-section keel beam finite element model, and is connected with the mass points to obtain a finite element connection model of the keel beam and the mass points.

[0075] Specifically, according to the coordinate information of the discrete mass points obtained in step S1 for describing the mass characteristics of each segment, the mass points are placed at the specified coordinate positions in the structural finite element analysis software, and a concentrated mass is assigned to each mass point;

[0076] According to the relative position relationship between the pre-set test segment ship model and the continuous variable cross-section keel beam, in combination with the specific rectangular hollow cross-sectional size at each segment cutout position obtained in step S2, a continuous stiffness equivalent variable cross-section keel beam finite element model is established in the structural finite element analysis software. The cross-sectional size of the keel beam in the length range between the centers of two adjacent ship model segments is consistent, and is consistent with the rectangular hollow cross-sectional size at the cutout shared by the two adjacent segments;

[0077] All the cutouts of the pre-set test segment ship model can divide the keel beam into a plurality of beam segments in the longitudinal direction, and the number of the beam segments is consistent with the number of the ship model segments. For example, Figure 5As shown, in the structural finite element software, each keel beam segment corresponds to 8 discrete mass points describing the mass characteristics of the ship model segment. At the center of each segment, plate elements are extended from the outer surface of the keel beam to connect with the mass points, obtaining a finite element connection model of the keel beam and the mass points. Among them, the extended plate element mass is set to be extremely small and the stiffness is set to be extremely large, so as to ensure that it realizes the rigid connection of the keel beam and the mass points, and its existence will not affect the mass of the whole connection model.

[0078] In step S4, the structure form of the upper surface of the keel beam and the wall thickness of the keel beam are adjusted according to the finite element connection model of the keel beam and the mass points, to obtain the final keel beam size.

[0079] Further, in an embodiment of the present application, step S4 specifically includes:

[0080] Step S401, modal analysis is performed on the finite element connection model of the keel beam and the mass points by the structural finite element software, to determine the first-order vertical natural frequency of vertical bending, the first-order horizontal natural frequency of horizontal bending and the first-order torsional natural frequency of torsion;

[0081] Step S402, based on the finite element connection model of the keel beam and the mass points, according to the first-order torsional natural frequency, a plurality of rectangular openings are symmetrically opened on the upper surface of the keel beam along the center longitudinal section of the keel beam, and the wall thickness of the left and right and upper and lower walls of the keel beam is increased, to obtain an opening keel beam connection model;

[0082] Step S403, modal analysis is performed on the opening keel beam connection model, to obtain a new first-order vertical natural frequency of vertical bending, a new first-order horizontal natural frequency of horizontal bending and a new first-order torsional natural frequency of torsion, and it is judged whether it meets the expected target value, if not, the wall thickness of the keel beam or the opening size of the upper surface is adjusted and the steps S401-S403 are iteratively executed until the final keel beam size is obtained.

[0083] Specifically, according to the finite element model of the connection of the keel beam and the discrete mass points established in step S3, modal analysis is performed on it by the structural finite element software, to determine the first-order natural frequencies corresponding to the three modalities of vertical bending, horizontal bending and torsion, i.e. the first-order vertical natural frequency, the first-order horizontal natural frequency and the first-order torsional natural frequency. Since the vertical and horizontal stiffness distribution of the keel beam meets the similar relationship as the actual ship, the vertical and horizontal first-order natural frequencies obtained by modal analysis are very close to the expected results, but the torsional natural frequency of the keel beam also needs to be further adjusted to meet the similar relationship;

[0084] For the ship hull section with complex structure form, because of the existence of support connection structure (such as ribbed plate, transverse bulkhead, deck, etc.) or the existence of opening structure, the expected torsional stiffness of the section converted by the similarity relationship is less than the section torsional stiffness of the rectangular hollow section in step S2. Therefore, as shown in Figure 6 , it is also necessary to open several rectangular openings on the upper surface of the keel beam along the centerplane of the rectangular keel beam to reduce the overall torsional stiffness of the keel beam, while slightly increasing the wall thickness of the left and right walls and the upper and lower walls of the keel beam to compensate for the reduction in the overall vertical stiffness and horizontal stiffness of the keel beam caused by the openings on the upper surface, to obtain an opening keel beam connection model.

[0085] As shown in Figure 7 and 8 , on the basis of the opening keel beam connection model, the modal analysis is performed again on the connection model to calculate the vertical, horizontal and torsional first-order natural frequencies obtained after modifying the structure of the keel beam. Compared with the expected target value, the modes with large differences in natural frequency need to be adjusted again to adjust the wall thickness of the keel beam or the size of the openings on the upper surface and to perform modal analysis to check the first-order natural frequency of the mode. Until the vertical bending, horizontal bending and torsional corresponding first-order natural frequencies of the connection model of the keel beam and the mass point are within the acceptable error range of the expected value, the final size of the keel beam is determined. The specific keel beam size adjustment method is:

[0086] If the new vertical bending first-order vertical natural frequency is greater than the expected target value, slightly reduce the thickness of the upper and lower walls of the keel beam, and if the new vertical bending first-order vertical natural frequency is less than the expected target value, slightly increase the thickness of the upper and lower walls of the keel beam.

[0087] If the new horizontal bending first-order horizontal natural frequency is greater than the expected target value, slightly reduce the thickness of the left and right walls of the keel beam, and if the new horizontal bending first-order horizontal natural frequency is less than the expected target value, slightly increase the thickness of the left and right walls of the keel beam.

[0088] If the new torsional first-order torsional natural frequency is greater than the expected target value, slightly increase the width or length of the rectangular openings on the upper surface of the keel beam, and if the new torsional first-order torsional natural frequency is less than the expected target value, slightly reduce the width or length of the rectangular openings on the upper surface of the keel beam.

[0089] The keel beam design method for the segmented hydroelastic test model according to the embodiment of the present application serves the segmented hydroelastic test research under oblique waves, and can simulate the elastic deformation corresponding to three modes of vertical bending, horizontal bending and torsion simultaneously, and provides a method for accurately characterizing the mass characteristics of each segment through a few discrete mass points based on the mass distribution characteristics of the actual ship body, and provides a connecting method for rigidly connecting the keel beam and the mass points according to the positions of the keel beam and the discrete mass points, and maximally reduces the influence of the connecting structure on the overall model mass, and provides a keel beam design method for adjusting the structure form and the specific size of the keel beam according to the expected natural frequencies corresponding to the three modes, so that the finally designed keel beam can meet the predetermined requirements.

[0090] Secondly, the keel beam design system for the segmented hydroelastic test model according to the embodiment of the present application is described with reference to the accompanying drawings.

[0091] Figure 9 is a structural schematic diagram of the keel beam design system for the segmented hydroelastic test model according to an embodiment of the present application.

[0092] As shown in Figure 9 , the device 10 comprises a simulation mass characteristic module 100, a determination rectangular hollow cross-section size module 200, a construction finite element connection module 300 and a size adjustment module 400.

[0093] The simulation mass characteristic module 100 is used for simulating the mass characteristics in each segment of the preset test segmented ship model by using the ordered discrete mass points. The determination rectangular hollow cross-section size module 200 is used for determining the rectangular hollow cross-section size of the continuous variable cross-section keel beam which can simultaneously satisfy the similar vertical bending inertia moment and horizontal bending inertia moment according to the preset test segmented ship model. The construction finite element connection module 300 is used for establishing the finite element connection model of the keel beam and the mass points by using the mass points and the rectangular hollow cross-section size. The size adjustment module 400 is used for adjusting the structure form of the upper surface of the keel beam and the wall thickness of the keel beam according to the finite element connection model of the keel beam and the mass points, so as to obtain the final keel beam size.

[0094] It should be noted that the above explanation and description of the embodiment of the keel beam design method for the segmented hydroelastic test model also applies to the device of this embodiment, which will not be described here again.

[0095] The keel beam design system of the segmented hydroelastic test model provided by the embodiment of the present application serves the segmented hydroelastic model test research under oblique waves, and can simulate the elastic deformation corresponding to three modes of vertical bending, horizontal bending and torsion simultaneously, provides a method capable of accurately characterizing the mass characteristics of each segment through a few discrete mass points based on the mass distribution characteristics of an actual ship body, provides a connecting method capable of rigidly connecting the keel beam and the mass points according to the positions of the keel beam and the discrete mass points, and maximally reduces the influence of the connecting structure on the mass of the overall model, and provides a keel beam design method of adjusting the structure form and specific size of the keel beam according to the expected natural frequencies corresponding to the three modes, so that the finally designed keel beam can meet the predetermined requirements.

[0096] In order to realize the above-mentioned embodiments, the present application further provides a computer device, comprising a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor implements the keel beam design method of the segmented hydroelastic test model as described in the above-mentioned embodiments when executing the computer program.

[0097] In order to realize the above-mentioned embodiments, the present application further provides a non-temporary computer readable storage medium, which stores a computer program, wherein the computer program is executed by a processor to implement the keel beam design method of the segmented hydroelastic test model as described in the above-mentioned embodiments.

[0098] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above-mentioned terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, the different embodiments or examples described in the present application and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0099] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "N" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0100] Any processes or methods described in the flowcharts or otherwise described herein can be understood as representing a module, segment, or portion of code that includes one or more executable instructions for implementing the specified logical function(s) or process(es). The scope of a preferred embodiment of this application includes embodiments that can carry out a function in a different order, or use different arrangements of steps, or combine certain steps, or a different sequence of steps, or use different steps, or use different functions without departing from the essence of the embodiments disclosed herein. The description of a process or method should be understood as representing executable instructions that can be employed to cause a system, device, or other implement to carry out the associated functions.

[0101] Logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be embodied in computer-readable media, in which a process or method can be executed, using an instruction execution system, apparatus, or device, such as a computer-based system, processor, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For purposes of this specification, a "computer-readable medium" can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable medium can be a computer- readable storage medium. A "computer-readable storage medium" can include any medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable storage medium can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), and floppy disks where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. Additionally, the various memory devices described herein can serve as computer-readable media.

[0102] It should be understood that aspects of the application can be implemented in hardware, software, firmware, or combinations thereof. In the embodiments described above, the steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. As well, if implemented in hardware, as in another embodiment, the hardware can include any or a combination of the following technologies, which are all well known in the art: a discrete logic circuit(s) having logic gates for implementing logic functions upon an application of data signals; an application specific integrated circuit(s) having appropriate combinational logic gates; a programmable gate array(s) (PGA), a field programmable gate array(s) (FPGA), etc.

[0103] Those skilled in the art of the present technology can understand that all or part of the steps carried out by the above-mentioned embodiment method can be completed by programs instructing related hardware, and the programs can be stored in a computer readable storage medium. When the program is executed, it includes one of the steps of the method embodiment or a combination thereof.

[0104] In addition, each functional unit in each embodiment of the present application can be integrated into one processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The integrated module can be realized in the form of hardware or in the form of a software functional module. When the integrated module is realized in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer readable storage medium.

[0105] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

Claims

1. A method for designing a keel beam of a segmented hydroelastic test model, characterized in that: The following steps are involved: Step S1, using ordered discrete mass points to simulate the mass characteristics of each segment of a preset test segmented ship model; Step S2, determining the size of a rectangular hollow section of a continuously variable cross-section keel beam that simultaneously satisfies similar vertical bending moments of inertia and horizontal bending moments of inertia based on the preset test segmented ship model; Step S3, establishing a finite element connection model of the keel beam and the mass points using the mass points and the dimensions of the rectangular hollow section; Step S4, adjusting the structural form of the upper surface of the keel beam and the wall thickness of the keel beam according to the finite element connection model of the keel beam and the mass point to obtain the final keel beam size; The step S1 specifically includes: Step S101, determining the number and position of the segments of the preset test segmented ship model, and converting the mass characteristics of each ship model segment according to the similarity relationship, wherein the mass characteristics include mass, center of mass position and moment of inertia; Step S102: using eight mass points of the same mass for each ship model segment, and setting the eight mass points of the same mass to be located at eight vertices of a cuboid, such that the coordinates of the center point of the cuboid are consistent with the center of mass position of each ship model segment; Step S103: adjusting the length, width and height of the cuboid so that the moment of inertia of the center point of the cuboid is equal to the moment of inertia of each ship model segment.

2. The method for designing a keel beam of a segmented hydroelastic test model according to claim 1, characterized in that: The step S2 specifically includes: Step S201, determining the vertical bending stiffness and the horizontal bending stiffness at the cutout position of each ship model segment according to the vertical bending stiffness distribution and the horizontal bending stiffness distribution of the preset test segmented ship model; Step S202, converting the expected vertical bending moment of inertia and the expected horizontal bending moment of inertia of the preset keel beam material at each incision position according to the Young's modulus of the preset keel beam material; Step S203, based on the rectangular hollow section, ensure that the inner wall size of the rectangular hollow section at the cutout position of each ship model segment remains consistent and unchanged, and adjust the upper and lower wall thicknesses and left and right wall thicknesses of each rectangular hollow section respectively, so that each rectangular hollow section simultaneously meets the expected vertical bending moment of inertia and the expected horizontal bending moment of inertia.

3. The method for designing a keel beam of a segmented hydroelastic test model according to claim 1, characterized in that: The step S3 specifically includes: Step S301, obtaining coordinate information of mass points of each ship model segment, placing the mass points according to the coordinate information in the structural finite element analysis software, and determining the relative position relationship between the preset test segmented ship model and the continuously variable cross-section keel beam; Step S302: Based on the relative position relationship and in combination with the size of the rectangular hollow section at the cutout position of each ship model segment, a continuous stiffness equivalent variable cross-section keel beam finite element model is established in a structural finite element analysis software; Step S303: At the midpoint of each ship model segment, a plate unit is extended from the outer surface of the keel beam of the continuous stiffness equivalent variable-section keel beam finite element model, and connected to the mass point to obtain a finite element connection model of the keel beam and the mass point.

4. The method for designing a keel beam of a segmented hydroelastic test model according to claim 3, characterized in that: In step S3, the cross-sectional dimensions of the keel beam within the length range between the centers of two adjacent ship model segments are consistent, and are consistent with the rectangular hollow cross-sectional dimensions at the cutout position shared by the two adjacent segments.

5. The method for designing a keel beam of a segmented hydroelastic test model according to claim 1, characterized in that: The step S4 specifically includes: Step S401, performing modal analysis on the finite element connection model of the keel beam and the mass point using structural finite element software to determine the first-order vertical natural frequency of vertical bending, the first-order horizontal natural frequency of horizontal bending, and the first-order torsional natural frequency of torsion; Step S402: Based on the finite element connection model of the keel beam and the mass point, a plurality of rectangular openings are symmetrically opened on the upper surface of the keel beam along the mid-longitudinal section of the keel beam according to the first-order torsional natural frequency, and the wall thickness of the left and right walls and the upper and lower walls of the keel beam are increased to obtain an open keel beam connection model. Step S403: Perform modal analysis on the open keel beam connection model to obtain the first-order vertical natural frequency of the new vertical bending, the first-order horizontal natural frequency of the new horizontal bending, and the first-order torsional natural frequency of the new torsion, and determine whether they meet the expected target values. If not, adjust the wall thickness of the keel beam or the opening size of the upper surface and iterate steps S401-S403 until the final keel beam size is obtained.

6. The method for designing a keel beam of a segmented hydroelastic test model according to claim 5, characterized in that: In step S403, If the first-order vertical natural frequency of the new vertical bending is greater than the expected target value, the thickness of the upper and lower walls of the keel beam is reduced; if the first-order vertical natural frequency of the new vertical bending is less than the expected target value, the thickness of the upper and lower walls of the keel beam is increased, and steps S401-S403 are iteratively performed until the final keel beam size is obtained; If the first-order horizontal natural frequency of the new horizontal bending is greater than the expected target value, the thickness of the left and right walls of the keel beam is reduced; if the first-order horizontal natural frequency of the new horizontal bending is less than the expected target value, the thickness of the left and right walls of the keel beam is increased, and steps S401-S403 are iteratively performed until the final keel beam size is obtained; If the first-order torsional natural frequency of the new torsion is greater than the expected target value, the width or length of the rectangular opening on the upper surface of the keel beam is increased; if the first-order torsional natural frequency of the new torsion is less than the expected target value, the width or length of the rectangular opening on the upper surface of the keel beam is reduced, and steps S401-S403 are iteratively performed until the final keel beam size is obtained.

7. A system used in the keel beam design method for a segmented hydroelastic test model according to claim 1, characterized in that: include: The mass characteristics simulation module is used to simulate the mass characteristics of each section of the preset test section ship model using ordered discrete mass points; A rectangular hollow section size determination module is used to determine the rectangular hollow section size of a continuously variable cross-section keel beam that satisfies similar vertical bending inertia moments and horizontal bending inertia moments according to the preset test segmented ship model; Constructing a finite element connection module for establishing a finite element connection model between the keel beam and the mass point using the mass point and the size of the rectangular hollow section; The size adjustment module is used to adjust the structural form of the upper surface of the keel beam and the wall thickness of the keel beam according to the finite element connection model of the keel beam and the mass point to obtain the final keel beam size.

8. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for designing a keel beam of a segmented hydroelastic test model as claimed in any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for designing a keel beam of a segmented hydroelastic test model as claimed in any one of claims 1 to 6 is implemented.

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