A three-dimensional parameterized modeling method based on two-dimensional midship section

Abstract

The application provides a three-dimensional parameterized modeling method based on a two-dimensional midship section of a midship cargo hold, and the method comprises the following steps: S1, obtaining midship cargo hold parameters according to a midship section drawing of the midship cargo hold; S2, arranging the obtained midship cargo hold parameters into an external data file which can be read by three-dimensional modeling software; S3, reading the external data file and performing secondary development to obtain contour node coordinate information of a longitudinal plate of the midship cargo hold and installation node coordinate information of a longitudinal frame of the midship cargo hold; S4, performing parameterized geometric modeling on the longitudinal plate of the midship cargo hold and the longitudinal frame of the midship cargo hold to obtain two-dimensional geometric models of the longitudinal plate of the midship cargo hold and the longitudinal frame of the midship cargo hold; and S5, uniformly performing longitudinal stretching on the two-dimensional geometric models of the longitudinal plate of the midship cargo hold and the longitudinal frame of the midship cargo hold to obtain a three-dimensional model of the midship cargo hold. The method uses three-dimensional modeling platform secondary development technology to quickly generate the three-dimensional model of the midship cargo hold, provides a basis for quick conversion of a finite element model of the midship cargo hold, and greatly shortens the construction time and construction difficulty of the finite element model of the midship cargo hold.

Description

Technical Field

[0001] This invention belongs to the field of container ship construction technology, specifically relating to a three-dimensional parametric modeling method based on a two-dimensional midsection of the cargo hold. Background Technology

[0002] During the design and classification society review stages of ultra-large container ships, it is necessary to first review and approve typical mid-section drawings, and then conduct finite element structural strength assessments of the mid-cargo hold based on these drawings to determine the dimensions of each component, thereby further improving the structural safety performance of the hull and ensuring operational safety and the stable development of shipping logistics.

[0003] Because the International Maritime Organization (IMO) and IACS, as well as classification societies, mandate finite element analysis of mid-section cargo holds based on mid-section drawings, rapid finite element modeling is crucial. Currently, full lifecycle design based on 3D modeling platforms is increasingly being applied in ship design, enabling rapid conversion between CAD and CAE models. However, current CAD geometric models require manual creation at each node of the mid-section, a time-consuming process that delays the R&D and design cycle and places stringent demands on different operators. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a three-dimensional parametric modeling method based on the two-dimensional mid-section of the cargo hold, which can quickly generate a three-dimensional model of the cargo hold, provide a basis for the rapid conversion of the finite element model of the cargo hold, and greatly shorten the modeling time and reduce the modeling difficulty of the finite element model of the cargo hold.

[0005] To achieve the above and other related objectives, this invention provides a three-dimensional parametric modeling method based on a two-dimensional midsection of the cargo hold, the method comprising:

[0006] S1. Obtain the mid-cargo hold parameters based on the mid-section drawing of the mid-cargo hold; the mid-cargo hold parameters include: molded depth D, molded width B, hatch coaming height Dh, double bottom structure height Hdb, double hull width Bs, distance from the beam arch to the midships Ba, height from the beam arch to the main deck Ha, spacing between the side bottom girder Bc, container height Hc, spacing between the mid bottom girder and the side bottom girder Bp, total number of transverse containers Rcn, total number of vertical containers Tcm between the first platform and the third platform, spacing between the longitudinal girders of the top deck H1, spacing between the longitudinal girders of the first main deck B1, spacing between the longitudinal girders of the second main deck B2, length of the hatch coaming top plate Bw1, and height of the hatch coaming fold plate Bw2.

[0007] S2. Organize the acquired cargo hold parameters into an external data file that can be read by 3D modeling software;

[0008] S3. Use 3D modeling software to read external data files and perform secondary development to obtain the outline node coordinate information of the longitudinal plate of the middle cargo hold and the installation node coordinate information of the longitudinal skeleton of the middle cargo hold.

[0009] S4. Use the modeling function of the 3D modeling software to perform parametric geometric modeling of the longitudinal plate and longitudinal frame of the middle cargo hold, and obtain the two-dimensional geometric model of the longitudinal plate and the two-dimensional geometric model of the longitudinal frame of the middle cargo hold, thus completing the two-dimensional geometric modeling of the middle cargo hold.

[0010] S5. Based on the length of the middle cargo hold, the two-dimensional geometric models of the longitudinal plates and longitudinal ribs of the middle cargo hold are uniformly stretched longitudinally to obtain the three-dimensional model of the middle cargo hold.

[0011] Preferably, when performing two-dimensional geometric modeling of the mid-cargo hold, the two-dimensional geometric modeling of the mid-cargo hold is divided into two-dimensional geometric modeling of the double-bottom structure and two-dimensional geometric modeling of the side structure; the two-dimensional geometric modeling of the double-bottom structure includes two-dimensional geometric modeling of the double-bottom longitudinal plate and the double-bottom longitudinal ribs, and the two-dimensional geometric modeling of the side structure includes two-dimensional geometric modeling of the side longitudinal plate and the side longitudinal ribs; the two-dimensional geometric model of the mid-cargo hold longitudinal plate is obtained by completing the two-dimensional geometric modeling of the double-bottom longitudinal plate and the side longitudinal plate; the two-dimensional geometric model of the mid-cargo hold longitudinal ribs is obtained by completing the two-dimensional geometric modeling of the double-bottom longitudinal ribs and the side longitudinal ribs; the two-dimensional geometric modeling of the double-bottom longitudinal plate is prioritized over the two-dimensional geometric modeling of the side longitudinal plate to improve the modeling speed.

[0012] Preferably, the two-dimensional geometric modeling of the double bottom longitudinal plate includes the two-dimensional geometric modeling of the bottom plate, the inner bottom plate, and the inner bottom girder; the two-dimensional geometric modeling of the double bottom longitudinal girder includes the two-dimensional geometric modeling of the bottom longitudinal girder, the inner bottom longitudinal girder, and the inner bottom girder longitudinal girder; the inner bottom girder includes one center bottom girder and multiple side bottom girder, the number of which is determined by the total number of transverse containers Rcn; the two-dimensional geometric modeling of the side longitudinal plate includes the two-dimensional geometric modeling of the platform, the outer shell, the inner shell, the main deck, the hatch coaming, the inner bottom side plate, and the bilge; the two-dimensional geometric modeling of the side longitudinal girder includes the two-dimensional geometric modeling of the platform longitudinal girder, the outer shell longitudinal girder, the inner shell longitudinal girder, the main deck longitudinal girder, the bilge longitudinal girder, and the inner bottom side plate longitudinal girder.

[0013] Preferably, the data file is a CSV file.

[0014] As described above, the three-dimensional parametric modeling method based on the two-dimensional mid-section of the cargo hold of the present invention has the following beneficial effects:

[0015] (1) It can quickly realize the parametric geometric modeling of the cross section of the middle cargo hold, obtain the two-dimensional geometric model of the cross section of the middle cargo hold, and perform longitudinal stretching on the basis of the two-dimensional geometric model to obtain the three-dimensional model of the middle cargo hold, which provides a basis for the conversion and analysis of the finite element model in the later stage, greatly shortens the design cycle and design difficulty, and is easy to promote and use.

[0016] (2) Based on the arrangement direction of the containers, classify and model them to facilitate the rapid implementation of the parametric program and improve modeling efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the mid-section of the cargo hold in a container.

[0018] Figure 2 This is a schematic diagram showing the parameters of the middle cargo hold on a cross-section of the middle cargo hold.

[0019] Figure 3 This is a schematic diagram of the two-dimensional geometric model of the middle cargo hold.

[0020] Figure 4 This is a schematic diagram of the three-dimensional model of the middle cargo hold.

[0021] Explanation of reference numerals in the attached figures

[0022] Double bottom structure 1, side structure 2, container 3. Detailed Implementation

[0023] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0024] Please see Figures 1 to 4 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0025] The three-dimensional parametric modeling software of the present invention can be implemented based on any three-dimensional modeling software that can be further developed. This embodiment takes CATIA three-dimensional modeling software as an example for specific explanation.

[0026] This invention provides a three-dimensional parametric modeling method based on a two-dimensional midsection of the cargo hold, the method comprising:

[0027] S1, such as Figures 1 to 2 As shown, the parameters of the mid-cargo hold are obtained based on the mid-section drawing of the mid-cargo hold. These parameters include: molded depth D, molded width B, hatch coaming height Dh, double bottom structure height Hdb, double hull width Bs, distance from the arch to the midships Ba, height from the arch to the main deck Ha, spacing between the side girder girders Bc, container height Hc, spacing between the mid-bottom girder and the side girder girders Bp, total number of transverse containers Rcn, total number of vertical containers Tcm between the first and third platforms, spacing between the longitudinal girders of the top deck H1, spacing between the longitudinal girders of the first and second main decks B1, length of the hatch coaming top plate Bw1, and height of the hatch coaming fold plate Bw2. The container width is equal to the side girder spacing Bc.

[0028] S2. Organize the acquired cargo hold parameters into an external data file that can be read by CATIA software;

[0029] Specifically, the data file can be any external data file that can be recognized by modeling software such as CATIA, such as an Excel file, CSV file, XML file, or TXT file. There is no limitation on this, but in this embodiment, a CSV file is preferred.

[0030] It is understandable that the parameters of the cargo hold can be compiled into a data file using manual or software processing methods, and there are no restrictions on this.

[0031] S3. Use CATIA software to read external data files and obtain the outline node coordinate information of the longitudinal plate of the middle cargo hold and the installation node coordinate information of the longitudinal skeleton of the middle cargo hold through secondary development programming.

[0032] It is understandable that the mid-cargo hold longitudinal plating includes the bottom plating, inner bottom plating, inner bottom girder, outer shell, inner shell, first platform, second platform, third platform, main deck, hatch coaming, inner bottom side plating, and bilge; the mid-cargo hold longitudinal girders include the bottom longitudinal girders, inner bottom longitudinal girders, inner bottom girder longitudinal girders, platform longitudinal girders, main deck longitudinal girders, inner bottom side plating longitudinal girders, and bilge longitudinal girders.

[0033] Specifically, as in question 2 and Figure 3As shown, firstly, the coordinate information of the outline nodes A and C of the bottom plate, the coordinate information of the outline nodes A' and C' of the double bottom plate, and the number of inner bottom girders are determined by the double bottom structure height Hdb, the side bottom girder spacing Bc, the spacing Bp between the middle bottom girder and the side bottom girder, and the total number of transverse containers Rcn. Then, the coordinate information of the outline node B' of each inner bottom girder on the inner bottom plate and the coordinate information of the outline node B on the bottom plate are determined. Next, the distance between two adjacent outline nodes on the inner bottom plate is divided into three equal parts to obtain the installation node coordinate information of the longitudinal girders of the inner bottom plate. The distance between two adjacent outline nodes on the bottom plate is divided into three equal parts to obtain the installation node coordinates of the longitudinal girders of the bottom plate. The distance between two outline nodes on each inner bottom girder is divided into three equal parts to obtain the installation node coordinates of the longitudinal girders of the inner bottom girder.

[0034] Next, using the container height Hc, double-bottom structure height Hdb, width B, double-shell width Bs, and the coordinate information of contour node C, the coordinate information of three contour nodes D, D', and D” on the first platform is determined. Then, the distance between two adjacent contour nodes on the first platform is trisected to obtain the installation node coordinates of the longitudinal ribs of the first platform. Using the coordinate information of contour node D, contour node D', container height Hc, and the total number of vertical containers Tcm between the first and third platforms, the coordinate information of two contour nodes E and E' on the second platform and two contour nodes F and F' on the third platform are determined. Then, the distance between two contour nodes on the second platform is trisected to obtain the installation node coordinates of the longitudinal ribs of the second platform, and the distance between two contour nodes on the third platform is trisected to obtain the installation node coordinates of the longitudinal ribs of the third platform. Using the depth D, width B, and other coordinate information, the coordinate information of the longitudinal ribs of the first platform is determined. Determine the coordinate information of contour node G. Based on the coordinate information of contour node G, beam B, distance from the midships to the beam arch Ba, and height from the beam arch to the main deck Ha, determine the coordinate information of virtual node G”. Based on the coordinate information of contour node G, virtual node G”, contour node D’, and contour node F’, determine the coordinate information of contour node G’. Divide the distance between the two contour nodes G and G’ according to the spacing between the first main deck longitudinals B1 and the spacing between the second main deck longitudinals B2 to obtain the installation node coordinate information of the main deck longitudinals. Divide the distance between the two contour nodes D and G according to the spacing between the top plate longitudinals H1 (i.e., Hc / 2) and the spacing between the outer plate longitudinals (i.e., Hc / 3) to obtain the installation node coordinate information of the outer shell longitudinals. Divide the distance between the two contour nodes D’ and G’ according to the spacing between the top plate longitudinals H1 and the spacing between the outer plate longitudinals to obtain the installation node coordinate information of the inner shell longitudinals.

[0035] Next, based on the hatch coaming height Dh and the coordinate information of the profile node D', the coordinate information of the profile node P1 is obtained. Then, based on the hatch coaming top plate length Bw1, the hatch coaming upper fold plate height Bw2, and the coordinate information of the profile nodes D' and G', the coordinate information of the profile nodes P2 and P3 is obtained.

[0036] Finally, according to the maximum number of transverse containers, the distance between contour nodes C and D is divided equally to obtain the installation node coordinate information of the bilge longitudinal rib; the distance between contour nodes C' and D” is divided equally to obtain the installation node coordinate information of the inner side plate longitudinal rib.

[0037] S4. By calling CATIA's own modeling function through CAA+, parametric geometric modeling of the longitudinal plate and longitudinal frame of the middle cargo hold is performed to obtain the two-dimensional geometric model of the longitudinal plate and the two-dimensional geometric model of the longitudinal frame of the middle cargo hold, thus completing the two-dimensional geometric modeling of the middle cargo hold.

[0038] When performing 2D geometric modeling of the mid-cargo hold, the 2D geometric modeling of the mid-cargo hold is divided into 2D geometric modeling of the double-bottom structure and 2D geometric modeling of the side structure. The 2D geometric modeling of the double-bottom structure includes 2D geometric modeling of the double-bottom longitudinal plate and the double-bottom longitudinal ribs. The 2D geometric modeling of the side structure includes 2D geometric modeling of the side longitudinal plate and the side longitudinal ribs. The 2D geometric model of the mid-cargo hold longitudinal plate is obtained by completing the 2D geometric modeling of the double-bottom longitudinal plate and the side longitudinal plate. The 2D geometric model of the mid-cargo hold longitudinal ribs is obtained by completing the 2D geometric modeling of the double-bottom longitudinal ribs and the side longitudinal ribs.

[0039] To facilitate rapid implementation of the program algorithm, the specific steps for 2D geometric modeling of the cargo hold are as follows:

[0040] (1) The outline nodes of the longitudinal plate of the cargo hold are divided into Class I outline nodes (i.e., nodes in the transverse direction of container arrangement) and Class II outline nodes (i.e., nodes in the vertical direction of container arrangement) according to the arrangement direction of the containers. The Class I outline nodes are outline nodes of the double bottom structure, and the Class II outline nodes are outline nodes of the side structure. The outline nodes of the double bottom structure include outline nodes A, A', B, B', C, C', and the outline nodes of the side structure include outline nodes D, D', D”, E, E', F, F', G, G', P1, P2, P3.

[0041] Specifically, with A as the center of the coordinate circle, a coordinate system with Y and Z axes is established. The Y-coordinates of contour nodes A and A' are 0, the Z-coordinates of contour nodes A, B, and C are 0, and the Z-coordinates of contour nodes A', B', and C' are Hdb. The procedure for determining the Y-coordinates of contour nodes B, B', C, and C' in the double-bottom structure is as follows:

[0042] Do j = 1, Rcn - 1;

[0043] Y: Bp+(j-1)*Bc;

[0044] End do

[0045] In the side structure, the Y-coordinate of contour nodes D, E, F, and G is the beam B; the Y-coordinate of contour nodes D', E', F', G', and P1 is B-Bs; the Y-coordinate of contour node D” is Bp+(Rcn-2)*Bc; the vertical coordinates of contour nodes D, D', and D” are Hdb+Hc; the vertical coordinates of contour nodes F and F' are Hdb+(Tcm+1)*Hc; and the vertical coordinates of contour nodes E and E' are Hd. b+(Tcm / 2+1)*Hc; The vertical coordinate of contour node G is D, then the vertical coordinate of contour node G' is: D+Bs*Ha / (B-Ba); The vertical coordinates of contour nodes P1 and P2 are both: Dh, the Y-coordinate of contour node P1 is: Bp+(Rcn-2)*Bc, the Y-coordinates of contour nodes P2 and P3 are: Bp+(Rcn-2)*Bc+Bw1; the Y-coordinate of contour node P3 is: Dh-Bw2.

[0046] After determining the outline nodes of all longitudinal plates, determine the installation node positions of each longitudinal rib.

[0047] (2) Connect contour nodes A and C to obtain the two-dimensional geometric model of the bottom plate AC, and connect contour nodes A' and C' to obtain the two-dimensional geometric model of the inner bottom plate A'C'; connect contour nodes A and A' to obtain the two-dimensional geometric model of the middle bottom girder AA', connect contour nodes C and C' to obtain the two-dimensional geometric model of the outermost side bottom girder CC', and connect contour node B and the corresponding contour node B' to obtain the two-dimensional geometric model of the remaining side bottom girder BB', thus finally obtaining the two-dimensional geometric model of each longitudinal plate on the double bottom structure (i.e., the two-dimensional geometric model of the double bottom longitudinal plate); then, assign ribs to the installation nodes of the inner bottom plate, bottom plate, and inner bottom girder to obtain the two-dimensional geometric model of each longitudinal rib on the double bottom structure (i.e., the two-dimensional geometric model of the double bottom longitudinal rib); thus, the two-dimensional geometric model of the entire double bottom structure is obtained.

[0048] (3) Connect contour nodes D, D' and contour nodes D', D” to obtain the two-dimensional geometric model of the first platform DD”, and then assign skeletons to the mounting nodes of the first platform to obtain the two-dimensional geometric model of the longitudinal skeleton of the first platform; connect contour nodes E, E' to obtain the two-dimensional geometric model of the second platform EE’, connect contour nodes F, F' to obtain the two-dimensional geometric model of the third platform, and then assign skeletons to the mounting nodes of the second and third platforms to obtain the two-dimensional geometric models of the longitudinal skeletons of the second and third platforms; connect contour nodes D, G to obtain the two-dimensional geometric model of the outer shell, connect contour nodes D', G' to obtain the two-dimensional geometric model of the inner shell, and then assign skeletons to the mounting nodes of the inner and outer shells to obtain the two-dimensional geometric models of the longitudinal skeletons of the inner and outer shells; connect contour nodes G, G' to obtain the main armor The two-dimensional geometric model of the main deck is obtained by assigning ribs to the installation nodes of the main deck. The two-dimensional geometric model of the hatch coaming is obtained by connecting the contour nodes G' and P1, P1 and P2, and P2 and P3. The two-dimensional geometric model of the bilge is obtained by connecting the contour nodes D and C using spline curves, and ribs are assigned to the installation nodes of the bilge to obtain the two-dimensional geometric model of the bilge longitudinals. The two-dimensional geometric model of the inner bottom plate is obtained by connecting the contour nodes C' and D'', and ribs are assigned to the installation nodes of the inner bottom plate to obtain the two-dimensional geometric model of the inner bottom plate longitudinals. Thus, the two-dimensional geometric model of the entire side structure (including the two-dimensional geometric models of the side longitudinal plates and the side longitudinals) is obtained. The two-dimensional geometric model of the mid-cargo hold is completed.

[0049] S5, such as Figure 3 and Figure 4 As shown, based on the length of the middle cargo hold, the two-dimensional geometric model of the longitudinal plate of the middle cargo hold (i.e., the two-dimensional geometric model of the double bottom longitudinal plate + the two-dimensional geometric model of the side longitudinal plate) and the two-dimensional geometric model of the longitudinal skeleton of the middle cargo hold (i.e., the two-dimensional geometric model of the double bottom longitudinal skeleton + the two-dimensional geometric model of the side longitudinal skeleton) are uniformly stretched longitudinally to obtain the three-dimensional model of the middle cargo hold.

[0050] Finally, using CATIA's CAD-CAE conversion function, the 3D model of the middle cargo hold was converted into a 3D finite element model of the middle cargo hold.

[0051] In summary, this invention automatically generates the node coordinates of the cargo hold through secondary development technology and quickly constructs a three-dimensional model of the cargo hold using parametric modeling technology. This provides a foundation for the subsequent conversion and analysis of the finite element model, greatly shortens the design cycle and reduces the design difficulty, effectively meets the adaptive construction requirements of the finite element model of the cargo hold in containers of different sizes, and is easy to promote and use.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A three-dimensional parametric modeling method based on a two-dimensional midsection of the cargo hold, characterized in that, The method includes: S1. Obtain the mid-cargo hold parameters based on the mid-section drawing of the mid-cargo hold; the mid-cargo hold parameters include: molded depth D, molded width B, hatch coaming height Dh, double bottom structure height Hdb, double hull width Bs, distance from the beam arch to the midships Ba, height from the beam arch to the main deck Ha, spacing between the side bottom girder Bc, container height Hc, spacing between the mid bottom girder and the side bottom girder Bp, total number of transverse containers Rcn, total number of vertical containers Tcm between the first platform and the third platform, spacing between the longitudinal girders of the top deck H1, spacing between the longitudinal girders of the first main deck B1, spacing between the longitudinal girders of the second main deck B2, length of the hatch coaming top plate Bw1, and height of the hatch coaming fold plate Bw2. S2. Organize the acquired cargo hold parameters into an external data file that can be read by 3D modeling software; S3. Use 3D modeling software to read external data files and perform secondary development to obtain the outline node coordinate information of the longitudinal plate of the middle cargo hold and the installation node coordinate information of the longitudinal skeleton of the middle cargo hold. S4. Utilize the modeling function of the 3D modeling software to perform parametric geometric modeling of the longitudinal plate and longitudinal frame of the middle cargo hold, thereby obtaining a two-dimensional geometric model of the longitudinal plate and longitudinal frame of the middle cargo hold, completing the two-dimensional geometric modeling of the middle cargo hold; wherein, the inner bottom girder includes one central bottom girder and multiple side bottom girders, the number of which is determined by the total number of transverse containers Rcn, and the container width is equal to the side bottom girder spacing Bc; the vertical distance between the first platform and the third platform is dynamically determined by the total number of vertical containers Tcm; The two-dimensional geometric modeling process for the middle cargo hold includes the following: The outline nodes are divided into Class I outline nodes and Class II outline nodes according to the arrangement direction of the containers. The Class I outline nodes are the nodes in the lateral arrangement direction of the containers, corresponding to the double bottom structure, including outline nodes A, A', B, B', C, C'. The Class II outline nodes are the nodes in the vertical arrangement direction of the containers, corresponding to the side structure, including outline nodes D, D', D”, E, E', F, F', G, G', P1, P2, P3. Establish a coordinate system and determine the coordinates of various contour nodes: The Y-coordinates of contour nodes A and A' are 0, the Z-coordinates of contour nodes A, B, and C are 0, and the Z-coordinates of contour nodes A', B', and C' are Hdb. In the double-bottom structure, the Y-coordinates of the contour nodes B, B', C, and C' are determined by Bp+(j-1)×Bc, where j is the sequence number of the side bottom truss, and the value of j is an integer from 1 to Rcn-1. In the side structure, the Y-coordinate of the contour nodes D, E, F, and G is the beam B, and the Y-coordinate of the contour nodes D', E', F', G', and P1 is B-Bs, where B is the beam. The Y-coordinate of the contour node D” is Bp+(Rcn-2)×Bc. The vertical coordinates of contour nodes D, D', and D” in the side structure are: Hdb+Hc; the vertical coordinates of contour nodes F and F' are: Hdb+(Tcm+1)×Hc; the vertical coordinates of contour nodes E and E' are: Hdb+(Tcm / 2+1)×Hc; the vertical coordinate of contour node G is D, where D is the molded depth; the vertical coordinate of contour node G' is: D+Bs×Ha / (B-Ba), where B is the molded width and D is the molded depth; the vertical coordinates of contour nodes P1 and P2 are both: Dh; the Y-coordinate of contour node P1 is: Bp+(Rcn-2)×Bc; the Y-coordinates of contour nodes P2 and P3 are: Bp+(Rcn-2)×Bc+Bw1; the Y-coordinate of contour node P3 is: Dh-Bw2. After determining the outline nodes of all longitudinal plates, determine the installation node positions of each longitudinal rib. S5. Based on the length of the middle cargo hold, the two-dimensional geometric models of the longitudinal plates and longitudinal ribs of the middle cargo hold are uniformly stretched longitudinally to obtain the three-dimensional model of the middle cargo hold.

2. The three-dimensional parametric modeling method based on the two-dimensional midsection of the cargo hold according to claim 1, characterized in that, When performing two-dimensional geometric modeling of the middle cargo hold, the two-dimensional geometric modeling of the middle cargo hold is divided into two-dimensional geometric modeling of the double bottom structure and two-dimensional geometric modeling of the side structure. The two-dimensional geometric modeling of the double bottom structure includes the two-dimensional geometric modeling of the double bottom longitudinal plate and the two-dimensional geometric modeling of the double bottom longitudinal rib; the two-dimensional geometric modeling of the side structure includes the two-dimensional geometric modeling of the side longitudinal plate and the two-dimensional geometric modeling of the side longitudinal rib. The two-dimensional geometric model of the mid-cargo hold longitudinal plate is obtained by completing the two-dimensional geometric model of the double bottom longitudinal plate and the two-dimensional geometric model of the side longitudinal plate; the two-dimensional geometric model of the mid-cargo hold longitudinal bone is obtained by completing the two-dimensional geometric model of the double bottom longitudinal bone and the two-dimensional geometric model of the side longitudinal bone; the two-dimensional geometric model of the double bottom longitudinal plate is taken precedence over the two-dimensional geometric model of the side longitudinal plate.

3. The three-dimensional parametric modeling method based on the two-dimensional midsection of the cargo hold according to claim 2, characterized in that, The two-dimensional geometric modeling of the double bottom longitudinal plate includes the two-dimensional geometric modeling of the bottom plate, the inner bottom plate, and the inner bottom girder. Two-dimensional geometric modeling of double bottom longitudinal girders includes two-dimensional geometric modeling of bottom longitudinal girders, inner bottom longitudinal girders, and inner bottom girder longitudinal girders. The two-dimensional geometric modeling of the side longitudinal plates includes the two-dimensional geometric modeling of the platform, the outer shell, the inner shell, the main deck, the hatch coaming, the inner bottom plate, and the bilge. The two-dimensional geometric modeling of the side longitudinals includes the two-dimensional geometric modeling of the platform longitudinals, the outer shell longitudinals, the inner shell longitudinals, the main deck longitudinals, the bilge longitudinals, and the inner bottom plate longitudinals.

4. The three-dimensional parametric modeling method based on the two-dimensional midsection of the cargo hold according to claim 1, characterized in that, The data file is a CSV file.

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