KR100960085B1 - Method and apparatus for generating automatic mesh in a vessel - Google Patents

Abstract

The present invention relates to an automatic hull mesh generation technology, which generates a cross section of a cross section, a vertical cross section and a horizontal cross section in a form in which a structural member inside the hull is placed in a three-dimensional section model generated at the time of designing a ship. Re-divide into a longitudinal section, a horizontal cross-section, and the re-divided intersecting lines in the form of a polygon, characterized in that for generating the polygons composed of a triangle or a square mesh. According to the present invention, it is possible to advance the generation period of a container ship wire analysis model that takes four weeks or more to about one week through a container ship design method using a three-dimensional compartment model, thereby verifying the stability of the structure and designing a ship. The initial supply and demand forecast of city steels can be made more accurately, which can lead to the quickest time to win an order.

Container Ship, Electric Wire Model, 3D Compartment Model, Mesh

Description

METHOD AND APPARATUS FOR GENERATING AUTOMATIC MESH IN A VESSEL}

The present invention relates to a ship design technology, in particular, it is possible to extract information about the internal structural members of the electric wire using a three-dimensional partition model, by automatically generating a finite element model through the recursive mesh generation for polygons A method and apparatus for automatic hull mesh generation suitable for carrying out wire design.

Recently, due to the increase in the amount of marine logistics, the demand for container ships and the demand for large-sized containers have also increased rapidly. In the case of such a large container ship, the wire model is analyzed by the analysis of the wire structure in the initial design stage, and the wire supply prediction and the safety of the structure are verified.

However, unlike oil tankers or bulk cargo ships that structurally analyze the center parallel part, container ships with few central parallel parts and large hatch openings can be used to verify that the entire ship can withstand various loads, including torsional moments. A wire structure analysis modeling is performed, which is a time-consuming major factor in the analysis.

As such, it is very important for the container ship to evaluate the strength of the upper deck against the torsional moment. As the size of the ship grows, the upper deck and the hatch coaming top will reach 100mm in thickness, and at the beginning of the contract, how much thickness will be needed in the early stages and whether such steel can be delivered in a timely manner. It is very important to do.

These demands have led to simple calculations for evaluating torsional strength, but torsional strength, unlike bending moments, is limited in performing accurate evaluation with simple voids. This is because it is difficult to accurately consider the warping deformation due to the shear force due to the large opening between the top plates.

Finite element analysis, on the other hand, is a method to accurately evaluate hull strength regardless of load. Therefore, we have relied heavily on the method of evaluating the initial strength by manually constructing the wire finite element model.

In constructing the wire model using finite element analysis among the initial design methods of the container ship according to the prior art operating as described above, it takes at least about 2 months and requires information about the whole wire. There is a problem that it is quite difficult to make a wire model using a short time and limited drawing information.

Accordingly, the present invention provides an automatic hull mesh generating method and apparatus capable of performing an initial design of a container ship using a three-dimensional partition model in order to reduce the time required for structural analysis of the container ship.

In addition, the present invention, using the three-dimensional partition model to extract the information about the internal structural members, automatically generated finite element model to generate the hull automatic mesh that can perform the wire design through the recursive mesh generation for the polygon It provides a method and apparatus.

According to an exemplary embodiment of the present invention, a process of generating an intersection line of a cross section, a longitudinal section, and a horizontal section in a form in which a structural member inside the hull is placed in a three-dimensional partition model generated when designing a ship, and a cross section of the generated intersection line And a process of re-dividing the cross-section into a horizontal section, a process of constructing the re-divided intersection line into a polygonal form, and generating the constructed polygons into a triangle or a square mesh.

One embodiment of the present invention, the cross-section generating unit for generating the intersection of the cross section, longitudinal section, horizontal cross-section in the form of the inner structural member in the three-dimensional partition model generated when the ship design, and the intersection line generating unit A line segment collection unit for subdividing the intersection line generated from the cross section into a cross section, a longitudinal section, and a horizontal cross section, a polygon forming unit configured to form the subdivided intersection line in a polygonal form, and polygons formed from the polygon forming unit into a triangle or a square mesh. It includes a recursive mesh generator to generate.

In the present invention, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

According to the present invention, it is possible to advance the generation period of a container ship wire analysis model that takes more than four weeks to about one week through a container ship design method using a three-dimensional partition model, thereby verifying the safety of the structure and designing a ship. It is possible to more accurately predict the initial supply and demand of steel, which has the effect of speeding up the order time of ships.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be made based on the contents throughout the specification.

The present invention extracts information about internal structural members by using 3D compartment model to shorten the time required for structural analysis of container ships, and generates finite element model automatically to generate finite element analysis through recursive mesh generation of polygons. Is to carry out the wire design.

As such, a 3D compartment model generated from NAPA, which is a 3D shape model used to support initial and basic design of the ship, is used. The three-dimensional compartment model is intended to define the hull shell and cargo hold compartments to calculate longitudinal stability, including ship stability, cargo volume, and static load. Since this compartment model is generated at the early stage of design, it is advantageous to make the analysis results much earlier when the model for wire analysis is used.

However, since the three-dimensional partition model does not contain any information on the structural members required for structural modeling, in the present invention, it is possible to extract information on the internal structural members from the three-dimensional partition model, and to automatically generate the finite element model. I will present a way to generate it. This shortens the model creation period for container ship wire analysis, which takes at least four weeks, to about one week.

Hereinafter will be described in detail through the following examples.

1 is a block diagram showing the structure of an automatic hull mesh generation system using a three-dimensional partition model according to a preferred embodiment of the present invention.

Referring to FIG. 1, the hull automatic mesh generation system includes a 3D partition model divider 100 and a mesh generator 150, where the 3D partition model divider 100 is an intersection line generator 102. ) And the line segment collection unit 104, and the mesh generating unit 150 includes a polygon forming unit 152 and a recursive mesh generating unit 154.

First, the three-dimensional partition model dividing unit 100 divides the three-dimensional partition model into line segments, and uses the following global coordinate system.

-X axis: Ship length direction, bow direction is (+) direction

-Y axis: ship width direction, port side is (+) direction

-Z axis: ship vertical direction, upward direction (+)

Cross section: YZ plane

Longitudinal section: XZ plane

-Horizontal section: XY plane

As shown in Figs. 3A to 3B, the three-dimensional partition model includes a hull shell 300, a bulkhead of the cargo hold or partition information 302, and the like. However, since the 3D partition model does not include an internal structural member, additional work of extracting such structural member information is required. In other words, the three-dimensional shape model is cut into a cross section (YZ), a longitudinal section (XZ), and a horizontal section (XY) where the structural members are placed to create an intersection line between the hull shell plate and the hull inner plate, and the space between them is regarded as a part filled with structural members. It is. This concept is particularly well suited for ships that do not include inclined members in cargo hold bulkheads, since the internal structure for carrying a container of cuboids, such as container ships, is all formed in the vertical or horizontal plane only.

In the intersection line generating unit 102 in the three-dimensional partition model dividing unit 100 generates a cross line between the cross section (YZ), the longitudinal section (XZ), the horizontal section (XY) and the three-dimensional model on which the structural members are placed, The line segment collection unit 104 converts the generated intersection line into the same cross section, longitudinal section, and horizontal section again to convert the line segment set.

Subsequently, the information converted into the line segment set is transferred to the polygon forming unit 152 of the mesh generating unit 150, and the polygon forming unit 152 reconstructs the converted line segment set, that is, the divided line segments into the polygon set. In addition, the recursive mesh generator 154 generates a wire analysis model by performing recursive mesh generation on the reconstructed polygon.

This will be described in detail step-by-step procedure in the three-dimensional partition model divider 100 and the mesh generator 150 in the hull automatic mesh generation system using a three-dimensional partition model.

2 is a flowchart illustrating an automatic mesh generation procedure of an automatic hull mesh generation system using a three-dimensional partition model according to a preferred embodiment of the present invention.

Referring to FIG. 2, in step 200, the intersection line generating unit 102 is a basic information for extracting the shape of a structural member from a three-dimensional partition shape model, and includes a cross section (YZ plane) and a longitudinal section (XZ plane) on which the structural member is placed. ), The position information of the horizontal section (XY plane) is input. That is, the longitudinal (X) coordinate value of the plane on which the transverse girders or transverse bulkheads are placed, the transverse (Y) coordinate value of the plane on which the longitudinal girders or longitudinal bulkheads are placed, and the horizontal girders or the bottom of the ship bottom, the bottom plating and the deck. Enter the value of the vertical (Z) coordinate.

Thereafter, the intersection line generator 102 generates the intersection lines by cutting the 3D partition shape model into planes perpendicular to three axes defined by the coordinate values defined above. At this time, the area between the two crossing lines where the hull shell and inner plate meet is set on the assumption that it is filled with structural members. As an example of the intersecting line, FIG. 4 shows the intersecting lines 400 generated by cutting a three-dimensional partition shape model into a plane on which a structural member is placed, according to a preferred embodiment of the present invention, and FIG. 5 is a cross section 500, a longitudinal section ( 502, the intersection line of the horizontal cross section 504 is shown.

In step 202, the line segment collecting unit 104 further cuts the intersection line generated in step 200 into respective planes, and divides the intersection line into smaller pieces. This is a set of line segments generated by cutting the intersection lines generated as shown in FIG. 6 back to the plane on which the structural members are placed. The cross section 600, the longitudinal section 602, and the horizontal cross section 604 are line segments and points. It is composed. In this way, the cross-sections decomposed through the step 202 are very similar to the finite element model. By breaking up the disassembled small segments, you can easily create a triangular or square shell element. In operation 202, the user may predict an expected element shape and may modify line segments for better mesh quality.

In this way, the three-dimensional partition model may be decomposed into many pieces through steps 200 through 202. In a later step, a method of generating a shell element having a triangular shape or a quadrangular shape by connecting the line segments is performed. In step 204, a closed polygon is formed from a line segment divided by the polygon forming unit 152, and a recursive mesh is generated in step 206. In section 154, a shell element is generated from the configured polygons.

The intermediate model composed of the line segments generated by the line segment collection unit 104 in step 202 does not have information about the relationship between the line segments. In step 204, line segments are first formed to form a polygon and store line segment and node information constituting the polygon.

A detailed procedure for constructing the polygon will be described with reference to FIG. 7.

7 is a flowchart illustrating a polygon construction procedure according to a preferred embodiment of the present invention.

Referring to FIG. 7, in step 700, one group including a set of line segments and nodes is selected in step 700, and a node shared by only two line segments is selected in step 702. Thereafter, in step 704, the polygon is searched by following the line segment having the smallest connection angle, and in step 706, the polygon is searched by chasing the line segment having the largest connection angle, thereby finding two polygons.

In step 708, the polygon satisfying the preset condition is deleted, and only the polygon that does not correspond to the condition is selected. The preset condition is a polygon composed of only free edges without a shared edge, and refers to a polygon in which only one polygon is shared. In addition, when the polygons are twisted in the middle, that is, when there are three or more line segments that share the nodes among the nodes constituting one polygon, polygons having an area of 0 are deleted.

In step 710, the selected polygon is registered in the polygon forming unit 152, and the formed free edges of the polygons are removed from the group, and in step 712, nodes in the middle of the removed free edges are removed from the group. By doing so, some edges of the formed polygons are removed from the group, and if the polygons are formed for all the segments in the group in step 714 and all the segments are removed, that is, all the segments in the group are not removed, in step 702. Returning to, the polygon forming procedure is performed again.

As described above, the polygon search and free edge removal scheme described through the flowchart of FIG. 7 will be described in detail with reference to FIGS. 8A to 8B.

8A to 8B illustrate a polygon search and free edge elimination scheme according to a preferred embodiment of the present invention. Referring to FIG. 8A, a polygon having a long circumference is formed by connecting line segments connected at the largest angle. Short polygons are formed by connecting the segments connected at the largest angle. Of the two polygons found, the long polygon is one large hole and is removed because it was formed only with free edges. That is, the short polygon is registered as the right polygon 800 and the long polygon is removed as the wrong polygon 802.

8B, when one polygon is formed, free edges of edges forming the polygon are removed from the original model. Then we start the polygon search process (1, 2, 3, 4) at the node shared by the two free edges and repeat until all the segments of the model are removed from the group.

9 is a flowchart illustrating a mesh generation procedure from a polygon according to a preferred embodiment of the present invention.

Referring to FIG. 9, when the polygons registered in the polygon forming unit 152 are received by the recursive mesh generating unit 154, the recursive mesh generating unit 154 selects a polygon having the largest number of nodes in step 900. In step 902, the polygon selected in the step S2 is partitioned according to a predetermined division pattern for each priority.

In step 904, after updating the entire polygon set, in step 906, if all polygons consist of triangles or rectangles, and if there are more than pentagonal polygons, the process returns to step 900 to perform the polygon division process again, and all polygons are triangles. Or, if it is made of a rectangle, the process proceeds to step 908 to make the divided triangle or rectangle into a shell element for generating a finite element model.

As described above, in FIG. 9, the formed polygon is converted into a mesh. For example, a polygon having five or more nodes has three or four nodes that can be immediately converted into a triangular or quadrangular shell element. It's an implementation that keeps dividing until it turns into a polygon. At this time, the preset partitioning method and priority for polygonal partitioning are generally defined as the partitioning pattern as shown in FIG.

10 is a diagram illustrating priorities of division patterns of a polygonal shape according to an exemplary embodiment of the present invention.

Referring to FIG. 10, the basic concept of priority is to divide using a partition pattern of a self-explanatory shape that can easily make a square-shaped shell element in order to maximize the use of the square element.

Looking at the polygon shape and division scheme for each priority, priority 1 is divided into two squares by connecting two nodes, and priority 2 is a square corner with one node. For example, one node can be connected to the corresponding line segment to be square or rectangular. Priority 3 is a corner of type L, and each edge node is connected to the corner of type L. At priority 4, a square corner without nodes is square or rectangular at regular intervals. Connect the line segments.

Priority 5 is a triangle corner with two opposing nodes, which connect these nodes together to form a triangle, and priority 6 divides the pentagon into triangles and squares by connecting two opposite nodes in a pentagon with vertical symmetry. Finally, priority 7 connects the common pentagonal nodes together so that they can be separated into triangles and squares.

As such, each polygonal shape may be divided into triangles or rectangles by priority division patterns, and the divided triangles or rectangles are made into shell elements.

FIG. 11 illustrates an example in which a mesh is generated for the cross section 1100, the longitudinal section 1102, and the horizontal section 1104 using the method described with reference to FIG. 9. In the cross section 1100, the polygons in the dotted rectangle are five or more polygons, and are divided into triangular or rectangular elements according to the division pattern method shown in FIG. 10.

As described above, the present invention extracts information about the internal structural members using a three-dimensional partition model, and automatically generates a finite element model to generate a recursive mesh for polygons in order to reduce the time required for structural analysis of the container ship Conduct the wire structure analysis through

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

1 is a block diagram showing the structure of an automatic hull mesh generation system using a three-dimensional partition model according to an embodiment of the present invention,

2 is a flowchart illustrating an automatic mesh generation procedure of an automatic hull mesh generation system using a three-dimensional partition model according to a preferred embodiment of the present invention;

3a to 3b is a view showing the ship shell and cargo hold compartment information according to a preferred embodiment of the present invention,

4 is a view showing an intersection line generated by cutting a three-dimensional partition shape model according to a preferred embodiment of the present invention into a plane on which a structural member is placed;

5 is a cross-sectional view showing a three-dimensional partition shape model according to a preferred embodiment of the present invention as a cross section of a cross section, a longitudinal section, and a horizontal section in which a structural member is placed;

6 is a view showing a set of line segments generated after cutting intersection lines into a plane on which structural members are placed, according to a preferred embodiment of the present invention;

7 is a flowchart illustrating a polygon construction procedure according to a preferred embodiment of the present invention;

8a to 8b illustrate a polygon search and free edge removal according to a preferred embodiment of the present invention;

9 is a flowchart illustrating a mesh generation procedure from a polygon according to a preferred embodiment of the present invention;

10 is a view showing priorities for each divided pattern of polygonal shapes according to a preferred embodiment of the present invention;

11 is a view showing an example of mesh generation in accordance with a preferred embodiment of the present invention.

<Explanation of Signs of Major Parts of Drawings>

100: three-dimensional partition model division unit 102: intersection line generation unit

104: line segment collecting unit # 150: mesh generating unit

152: polygon forming unit 154: recursive mesh generating unit

Claims (15)

The process of creating the intersection of the cross section, longitudinal section and horizontal section in the form of the structural member inside the hull in the three-dimensional partition model created during ship design, Subdividing the generated intersection line into a cross section, a longitudinal section, and a horizontal section; Configuring the subdivided intersection lines in a polygonal form; Process of generating the constructed polygons as a triangle or a square mesh Hull automatic mesh generation method comprising a. The method of claim 1, The process of generating the intersection line, Inputting the position information of the longitudinal direction, the width direction, the vertical direction, and the cross section, the longitudinal section, and the horizontal section of the vessel on the vessel automatic mesh generation system; Cutting the three-dimensional partition model for each cross section and generating an intersection line between the hull shell and inner plates; Setting a region between the two crossing lines where the hull outer shell and the inner shell meet to fill the structural member Hull automatic mesh generation method comprising a. The method of claim 1, The process of repartitioning, Cutting the generated intersection line into the planes again to generate fragmented line segments; Grouping the generated fragmented line segments for each plane Hull automatic mesh generation method comprising a. The method of claim 1, The process of configuring in the polygonal form, Select a node that is shared only by two segments of the subdivided intersecting line segments, and search for the two polygons by searching for the largest angle segment and the smallest segment segment until they return to the origin. Finding process, Process of configuring only polygons that do not meet the preset conditions Hull automatic mesh generation method comprising a. The method of claim 4, wherein The preset condition is, Method for automatically generating a hull mesh, characterized in that the polygon that is shared only one polygon without a shared edge, or the polygon is twisted in the middle, and a polygon with an area of zero, to remove the incorrectly formed polygon through such conditions. The method of claim 1, The process of generating the mesh of the triangle or square, Selecting the polygons having the highest number of nodes in the polygonal form and dividing them according to a predetermined division pattern for each priority; If all polygons are split to be triangles or rectangles, the process of changing the divided triangles or rectangles into shell elements Hull automatic mesh generation method comprising a. The method of claim 6, The preset priority division pattern is A pattern having a priority set so as to induce the generation of a square shell element as much as possible, wherein the automatic hull mesh generation method comprising dividing a polygon into a predetermined pattern. A recording medium on which a computer program for executing the automatic mesh generating method of the hull according to any one of claims 1 to 7 is recorded. An intersecting line generating unit generating an intersecting line of a cross section, a longitudinal section, and a horizontal section in a form in which a hull internal structural member is placed in a three-dimensional partition model generated during ship design; A line segment collection unit for subdividing an intersection line generated from the intersection line generating unit into a cross section, a longitudinal section, and a horizontal section; A polygon forming unit constituting the subdivided intersection line segment in a polygonal form; Recursive mesh generating unit for generating polygons constructed from the polygon forming unit into a triangle or a square mesh Hull automatic mesh generating device comprising a. The method of claim 9, The intersection line generator, Setting the position information of the longitudinal direction, the width direction, the vertical direction, and the cross section, longitudinal section, horizontal section of the ship, After cutting the three-dimensional partition model for each cross section, and generates an intersection line between the hull shell plate and the inner plate, And an area between the two crossing lines where the hull outer plate and the inner plate meet is set as the structural member is filled. The method of claim 9, The line segment collecting unit, And cutting the generated intersection line back into the planes to generate fragmented line segments, and grouping the fragmented line segments into planes. The method of claim 9, The polygon forming unit, Select a node that is shared only by two segments of the subdivided intersecting line segments, and search for the two polygons by searching for the largest angle segment and the smallest segment segment until they return to the origin. Looking Up, An automatic hull mesh generating device comprising a polygon that does not satisfy a preset condition as a polygon. The method of claim 12, The preset condition is, A polygonal hull automatic mesh generation device, characterized in that polygons that share only one polygon without shared edges, polygons twisted in the middle, and polygons having an area of zero, and which have incorrectly formed polygons through such conditions. The method of claim 9, The recursive mesh generation unit, When the polygons are divided into polygons according to a predetermined priority in order of the highest number of nodes in the polygonal form, and all the polygons are divided into triangles or rectangles, the divided triangles or rectangles are changed into shell elements. Hull automatic mesh generating device. 15. The method of claim 14, The preset priority division pattern is A pattern having a priority set to induce generation of a shell element having a square shape as much as possible, wherein the automatic hull mesh generating device comprises dividing a polygon into a predetermined pattern.

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