A method and device for identifying a panel of a three-dimensional finite element model

Abstract

The application discloses a panel identification method and device of a three-dimensional finite element model. The method comprises the following steps: obtaining a three-dimensional finite element model; traversing the element edges of shell elements, identifying the panel boundary in the element edges according to a panel boundary judgment condition, and determining the shell elements constituting the panel; determining the nodes corresponding to the panel according to the corresponding relationship between the shell elements and the nodes and the corresponding relationship between the shell elements and the panel; determining the type of the panel according to the nodes corresponding to the panel, identifying the contour nodes of different types of panels, and the type of the panel comprises a planar panel and a curved panel; traversing the contour nodes, grouping the contour nodes according to a node grouping condition, and making each group of contour nodes correspond to the same panel edge of the panel. The application determines the contour nodes of the panel and the type of the panel by identifying the shell elements and the nodes included in the panel, and can identify all types of panels included in the three-dimensional finite element model.

Description

Technical Field

[0001] This invention relates to the field of model recognition technology, and in particular to a method and apparatus for plate recognition of a three-dimensional finite element model. Background Technology

[0002] In the design and review of ship and marine engineering structures, the finite element method (FEM) is required to analyze and verify the structural strength. According to industry standards, structural strength verification mainly includes static strength analysis, buckling analysis, and fatigue strength analysis. Buckling analysis differs from general finite element eigenvalue buckling analysis; it uses individual plates as the analysis object. Especially for ship structures, which are composed of plates and a frame, the plates are divided into numerous plates by the frame. Therefore, before conducting structural buckling analysis, it is necessary to identify all plates (including regular plates, irregular plates, curved plates, and open web plates) based on the structural finite element model, determine the shell elements and beam elements constituting each plate, and calculate the plate parameters required for buckling verification assessment.

[0003] The number of elements in a three-section hull model or a marine flat structure finite element model ranges from tens of thousands to hundreds of thousands, resulting in a massive number of plate grids. Currently, there is a lack of standalone plate grid identification methods. Relying on existing finite element analysis software for secondary development can easily lead to problems such as a limited number of identification elements, the inability to identify certain types of plate grids, or low identification accuracy, thus affecting the effectiveness of plate grid identification. Summary of the Invention

[0004] To address at least one technical problem existing in the prior art, embodiments of the present invention provide a method and apparatus for plate identification in a three-dimensional finite element model. The technical solution is as follows:

[0005] Firstly, a method for plate identification in a three-dimensional finite element model is provided, including:

[0006] A three-dimensional finite element model is obtained, the model including: a plate grid, the plate grid being divided into at least one shell element, the shell element including: nodes and element edges;

[0007] Traverse the edges of the shell units, identify the grid boundaries in the edges of the units according to the grid boundary determination conditions, and determine the shell units that make up the grid.

[0008] Based on the correspondence between the shell unit and the node, and the correspondence between the shell unit and the plate grid, determine the node corresponding to the plate grid;

[0009] The type of the plate is determined based on the nodes corresponding to the plate, and the contour nodes of different types of plate are identified. The types of plate include: planar plate and curved plate.

[0010] Traverse the contour nodes and group them according to the node grouping conditions, so that each group of contour nodes corresponds to the same edge of the grid.

[0011] Further, the step of traversing the cell edges of the shell cell, identifying the grid boundaries in the cell edges according to the grid boundary determination condition, and determining the elements constituting the grid includes:

[0012] Traverse all the edges of any shell element in the model, identify the common edge elements of the currently traversed edge elements, and generate the common edge element information of the edge elements;

[0013] The boundary of the grid is identified by comparing the information of the common edge units of the current unit with the grid boundary determination conditions.

[0014] If the current unit edge is not determined as the grid boundary, then identify the common edge unit of the unit edge, repeatedly traverse all the unit edges of the common edge unit, identify the grid boundary in the common edge unit, until the common edge unit of the currently traversed unit edge is only the shell unit to which the current unit edge belongs.

[0015] Further, the step of comparing the common edge information of the current unit edge with the grid boundary determination condition to identify the grid boundary includes:

[0016] If the shared edge information of the unit edge meets any of the following criteria, then the unit edge is identified as the grid boundary:

[0017] There are beam elements on the edge of the current element;

[0018] Currently, there is only one shared edge unit among the current unit edges;

[0019] The currently described unit has at least three shared edge units;

[0020] The current unit edge has two shared edge units, and the angle between the normal vectors of the two shared edge units is less than a preset normal vector angle threshold.

[0021] Further, determining the type of the grid based on the nodes corresponding to the grid, and identifying the contour nodes of different types of grids, includes:

[0022] The type of the grid is determined based on the node corresponding to the grid.

[0023] A first local coordinate system is established based on the type of the grid to identify the contour nodes, and the coordinates of the nodes in the grid in the first local coordinate system are determined.

[0024] Based on the coordinates of the node in the first local coordinate system, the contour nodes of the grid are identified using a planar point cloud contour recognition method.

[0025] Further, determining the type of the grid based on the node corresponding to the grid includes:

[0026] Obtain the number of nodes corresponding to the grid;

[0027] Identify the grid with three nodes as a planar grid;

[0028] For a grid with more than three nodes, a plane is determined using any three non-collinear nodes, and the normal vector of the plane is calculated. Vectors are established between any node in the plane and the remaining nodes of the grid. The angle between the established vector and the normal vector is calculated. If any angle satisfies an angle threshold, the grid is identified as a curved grid.

[0029] Further, the step of establishing a first local coordinate system for identifying the contour nodes based on the type of the grid, and determining the coordinates of the nodes in the grid within the first local coordinate system, includes:

[0030] For the planar plate grid, a spatial rectangular coordinate system is established based on the node in any shell unit of the planar plate grid, and the coordinates of the node in the first local coordinate system are determined.

[0031] For the curved panel grid, select any two shell elements that share an edge but are not coplanar within the grid. Based on the two nodes on the common edge of the two shell elements and the nodes on the non-common edge within any one of the shell elements, determine the plane and calculate the normal vector of the plane. Based on any vector and the normal vector within the plane and using the right-hand rule, establish the first local spatial coordinate system of the grid. Project the node coordinates in the first local spatial coordinate system onto the planar coordinate system to determine the coordinates of the node in the first local coordinate system.

[0032] Further, the step of identifying the contour nodes of the grid using a planar point cloud contour recognition method based on the coordinates of the nodes in the first local coordinate system includes:

[0033] Identify the features of the grid, which include: convex hull features and concave features;

[0034] Gamham scanning is used to identify the contour nodes of a grid with convex hull features.

[0035] Alpha shapes are used to process the grid with concave features and to identify the contour nodes of the grid.

[0036] Further, the step of traversing the contour nodes and grouping them according to node grouping conditions, so that each group of contour nodes is associated with the same edge of the grid, includes:

[0037] Traverse the contour nodes corresponding to the grid, establish two vectors using three adjacent contour nodes, and determine the included angle between the two adjacent vectors;

[0038] Determine whether the included angle between two adjacent vectors satisfies the same-side angle threshold. If it does, identify the three contour nodes corresponding to the same grid edge. If it does not, identify the three contour nodes corresponding to two different grid edges.

[0039] Furthermore, the method also includes:

[0040] Determine the first coordinate system node, the second coordinate system node, and the third coordinate system node on the plate grid, and establish a second local coordinate system for stress transformation;

[0041] The centroids of each shell element in the plate grid are transformed from the global coordinate system to the second local coordinate system using a coordinate system transformation matrix;

[0042] By utilizing the stress coordinate transformation relationship, the stress in the global coordinate system is transformed into the second local coordinate system, and the equivalent stress of the plate grid is calculated.

[0043] Further, the step of determining the first coordinate system nodes, the second coordinate system nodes, and the third coordinate system nodes on the plate grid, and establishing a second local coordinate system for stress transformation, includes:

[0044] For the planar grid, based on the number of grid edges corresponding to the grid, identify whether the grid is a regular grid or an irregular grid, and determine the first coordinate system node, the second coordinate system node and the third coordinate system node according to the coordinate system node determination rules for regular or irregular grids;

[0045] For the curved panel grid, the length of each panel edge determines whether the panel edge is a straight edge or a curved edge. The panel edges are arranged in the order of curved edge-straight edge-curved edge-straight edge. The first coordinate system node, the second coordinate system node, and the third coordinate system node are determined according to the rules for determining the coordinate system nodes of the curved panel grid.

[0046] The first coordinate system node is determined as the origin of the second local coordinate system. The vector constructed from the origin of the second local coordinate system to the second coordinate system node is taken as the X-axis. The normal vector of the plane determined by the first coordinate system node, the second coordinate system node, and the third coordinate system node is taken as the Z-axis. The cross product vector of the X-axis and the Z-axis is taken as the Y-axis.

[0047] Furthermore, the method also includes:

[0048] Calculate the dimensions of each edge of the grid:

[0049] For the planar grid, the long side dimension and short side dimension of the planar grid are calculated based on the dimensions of each grid edge;

[0050] For the curved panel grid, the dimensions of each panel edge are used to determine whether the panel edge is straight or curved. The radius and length of the arc of the curved edge, as well as the short side dimension of the curved panel grid, are calculated.

[0051] Furthermore, the step of utilizing stress coordinate transformation relationships to transform the stress in the input global coordinate system to the second local coordinate system of the plate grid, and calculating the equivalent stress of the plate grid, includes:

[0052] The stress coordinate transformation relationship is used to transform the plate stress in the global coordinate system to the second local coordinate system. Based on the plate type, the equivalent stress of the plate is calculated using an interpolation algorithm. The stress coordinate transformation relationship includes:

[0053]

[0054] in Let be the stress tensor of the plate grid in the second local coordinate system. Let be the stress tensor of the lattice in the global coordinate system. Let be the cosine of the angle between the coordinate axes of the global coordinate system and the second local coordinate system.

[0055] Secondly, a plate grid recognition device for a three-dimensional finite element model is provided, comprising:

[0056] The model acquisition module is used to acquire a three-dimensional finite element model, the model including: a plate grid, the plate grid being divided into at least one shell element, the shell element including: nodes and element edges;

[0057] The unit determination module is used to traverse the unit edges of the shell unit, identify the grid boundaries in the unit edges according to the grid boundary determination conditions, and determine the shell units that make up the grid.

[0058] The node determination module is used to determine the node corresponding to the plate grid based on the correspondence between the shell unit and the node and the correspondence between the shell unit and the plate grid.

[0059] The contour node recognition module is used to determine the type of the board grid based on the nodes corresponding to the board grid, and to identify the contour nodes of different types of board grids. The types of board grids include: planar board grids and curved board grids.

[0060] The grouping module is used to traverse the contour nodes and group the contour nodes according to the node grouping conditions, so that each group of contour nodes corresponds to the same edge of the grid.

[0061] Furthermore, the unit determination module includes:

[0062] The common edge unit information generation module is used to traverse all element edges of any shell element in the model, identify the common edge units of the currently traversed element edge, and generate the common edge unit information of the element edge.

[0063] The boundary recognition module is used to compare the common edge information of the current unit edge with the plate boundary determination conditions to identify the plate boundary. If the current unit edge is not determined as the plate boundary, the common edge of the unit edge is identified, and all unit edges of the common edge are repeatedly traversed to identify the plate boundary in the common edge, until the common edge of the currently traversed unit edge is only the shell unit to which the current unit edge belongs.

[0064] Furthermore, the criteria for determining the grid boundary include:

[0065] If the information of the common edge elements of an element meets any of the following criteria, then the element edge is identified as a grid boundary:

[0066] There are beam elements on the edge of the current element;

[0067] The current cell has only one cell sharing an edge;

[0068] The current cell has at least three shared edges;

[0069] The current cell has two cells sharing the same edge, and the angle between the normal vectors of the two cells sharing the same edge is less than a preset threshold for the angle between normal vectors.

[0070] Furthermore, the contour node recognition module includes:

[0071] The first type determination module is used to determine the type of the grid based on the nodes corresponding to the grid.

[0072] The first local coordinate system establishment module is used to establish a first local coordinate system for identifying contour nodes based on the type of the grid, and to determine the coordinates of the nodes in the grid in the first local coordinate system.

[0073] The contour recognition module is used to identify the contour nodes of the grid based on the coordinates of the nodes in the first local coordinate system using the planar point cloud contour recognition method.

[0074] Furthermore, the first type determination module is specifically used for:

[0075] Identify a grid with three nodes as a planar grid;

[0076] For a grid with more than three nodes, a plane is determined using any three non-collinear nodes. The normal vector of the plane is calculated. Vectors are established between any node in the plane and the remaining nodes in the grid. The angle between the established vector and the normal vector is calculated. If any angle is less than the angle threshold, the grid is identified as a curved grid.

[0077] Furthermore, the first local coordinate system establishment module is specifically used for:

[0078] For a planar plate grid, a spatial rectangular coordinate system is established based on the nodes within any shell element of the planar plate grid, and the coordinates of the nodes in the first local coordinate system are determined.

[0079] For a curved panel grid, select any two shell elements that share an edge but are not coplanar within the grid. Based on two nodes on the common edge of the two shell elements and nodes on the non-common edge of any one of the two shell elements, determine the plane and calculate the normal vector of the plane. Based on any vector and normal vector in the plane and using the right-hand rule, establish the first local spatial coordinate system of the grid. Project the node coordinates in the first local spatial coordinate system onto the planar coordinate system to determine the coordinates of the nodes in the first local coordinate system.

[0080] Furthermore, the contour recognition module includes:

[0081] The feature recognition module is used to identify the features of the grid, which include convex hull features and concave features.

[0082] The Gamham scanning module is used to scan lattices with convex hull features using Gamham scanning to identify the contour nodes of the lattice.

[0083] The Alpha shapes processing module is used to process grids with concave features using Alpha shapes and to identify the outline nodes of the grids.

[0084] Furthermore, the grouping module includes:

[0085] The angle determination module is used to traverse the contour nodes corresponding to the grid, establish two vectors using three adjacent contour nodes, and determine the angle between the two adjacent vectors.

[0086] The judgment module is used to determine whether the included angle between two adjacent vectors meets the same side angle threshold. If it does, the three contour nodes are identified as corresponding to the same grid edge. If they do not meet the threshold, the three contour nodes are identified as corresponding to two different grid edges.

[0087] Furthermore, the grid identification device disclosed in this embodiment of the invention also includes:

[0088] The second local coordinate system establishment module is used to determine the first coordinate system nodes, the second coordinate system nodes, and the third coordinate system nodes on the plate grid, and to establish a second local coordinate system for stress transformation.

[0089] The coordinate transformation module is used to transform the centroid of each shell element in the plate grid from the global coordinate system to the second local coordinate system using the coordinate system transformation matrix.

[0090] The equivalent stress calculation module is used to transform the stress in the global coordinate system to the second local coordinate system using the stress coordinate transformation relationship, and to calculate the equivalent stress of the plate.

[0091] Furthermore, the second local coordinate system establishment module includes:

[0092] The coordinate system node determination module is used for:

[0093] For a planar grid, the grid is identified as either a regular grid or an irregular grid based on the number of grid edges. The first coordinate system node, the second coordinate system node, and the third coordinate system node are determined according to the coordinate system node determination rules for regular or irregular grids.

[0094] For curved grid panels, the length of each grid edge determines whether it is a straight edge or a curved edge. The grid edges are arranged in the order of curved edge-straight edge-curved edge-straight edge. The first coordinate system node, the second coordinate system node, and the third coordinate system node are determined according to the rules for determining the coordinate system nodes of the curved grid panels.

[0095] The coordinate system establishment module is used to determine the first coordinate system node as the origin of the second local coordinate system. The vector constructed from the origin of the second local coordinate system to the second coordinate system node is used as the X-axis. The normal vector of the plane determined by the first coordinate system node, the second coordinate system node, and the third coordinate system node is used as the Z-axis. The cross product vector of the X-axis and the Z-axis is used as the Y-axis.

[0096] Furthermore, the grid identification device disclosed in this embodiment of the invention also includes:

[0097] The board edge dimension calculation module is used for:

[0098] For a planar grid, calculate the long and short side dimensions of the planar grid based on the dimensions of each grid edge;

[0099] For curved panel grids, determine whether the grid edge is straight or curved based on the dimensions of each grid edge, calculate the radius and length of the curved edge, as well as the short side dimension of the curved panel grid.

[0100] Furthermore, the equivalent stress calculation module is specifically used for:

[0101] The stress in the lattice under global coordinates is transformed to a second local coordinate system using stress coordinate transformation relationships. The equivalent stress of the lattice is calculated using an interpolation algorithm based on the lattice type. The stress coordinate transformation relationships include:

[0102]

[0103] in Let be the stress tensor of the plate lattice in the second local coordinate system. Let be the stress tensor of the plate lattice in the global coordinate system. Let be the cosine of the angle between the coordinate axes of the global coordinate system and the second local coordinate system.

[0104] Thirdly, an electronic device is provided, comprising:

[0105] One or more processors; and

[0106] A memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the method as described in any of the first aspects.

[0107] Fourthly, a computer-readable medium is provided having a computer program stored thereon, wherein the program, when executed by a processor, implements the method as described in any of the first aspects.

[0108] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0109] 1. The plate grid recognition technology disclosed in this embodiment of the invention identifies the shell elements and nodes included in the plate grid, determines the outline nodes and type of the plate grid, and can identify all types of plate grids included in the three-dimensional finite element model.

[0110] 2. The grid recognition technology disclosed in this embodiment of the invention adopts a traversal loop algorithm and sets an algorithm termination condition, without setting an upper limit on the number of grids to be recognized, and comprehensively and completely recognizes the grids included in the model.

[0111] 3. The plate recognition technology solution disclosed in the embodiments of the present invention does not require secondary development based on existing finite element analysis software and can run independently.

[0112] 4. The plate grid recognition technology disclosed in the embodiments of the present invention can calculate the equivalent stress of the plate grid by establishing a local coordinate system of the plate grid.

[0113] 5. The grid recognition technology disclosed in this embodiment of the invention can calculate the dimensions of the grid edges, as well as the long and short side dimensions of the planar grid, which helps users to further understand the grid information. Attached Figure Description

[0114] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0115] Figure 1 This is a flowchart of the grid recognition method provided in the embodiments of the present invention;

[0116] Figure 2 This is a schematic diagram of a model including a planar grid provided in an embodiment of the present invention;

[0117] Figure 3 This is a schematic diagram of the planar grid boundary recognition process provided in an embodiment of the present invention;

[0118] Figure 4 This is a schematic diagram of a model including a curved panel grid provided in an embodiment of the present invention;

[0119] Figure 5 This is a schematic diagram of the curved panel grid boundary recognition process provided in an embodiment of the present invention;

[0120] Figure 6 This is a schematic diagram of planar grid outline node recognition provided in an embodiment of the present invention;

[0121] Figure 7 This is a schematic diagram of curved panel grid contour node recognition provided in an embodiment of the present invention;

[0122] Figure 8 This is a schematic diagram of the structure of the grid recognition device provided in an embodiment of the present invention;

[0123] Figure 9 This is a schematic diagram of the electronic device structure provided in an embodiment of the present invention. Detailed Implementation

[0124] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0125] This invention discloses a method and apparatus for identifying plate grids in a three-dimensional finite element model. The specific technical solution is as follows:

[0126] like Figure 1 As shown, a method for plate identification in a three-dimensional finite element model includes:

[0127] S1. Obtain a three-dimensional finite element model. The model includes a plate grid, which is divided into at least one shell element. The shell element includes nodes and element edges.

[0128] The aforementioned 3D finite element model is generated from user-imported 3D finite element model data. The finite element model is divided into numerous plate grids, each of which is further divided into multiple shell elements. The finite element model data includes element topology information, which includes the correspondence between various types of elements and plate grids in the 3D finite element model. The correspondence between nodes and shell elements is then supplemented based on the model data. Shell elements are one of the element types used in the 3D finite element model for finite element analysis. Besides shell elements, the 3D finite element model also includes plate elements, beam elements, and rod elements. Shell elements consider forces in both the vertical plane and in-plane directions, plate elements only consider forces in the vertical plane, beam elements primarily bear bending moments, and rod elements primarily bear axial forces.

[0129] S2. Traverse the element edges of the shell element, identify the grid boundaries in the element edges according to the grid boundary determination conditions, and determine the shell elements that make up the grid.

[0130] As mentioned above, the element edge refers to the boundary of the shell element, and the grid boundary refers to the grid edge or a part of the grid edge. The embodiments disclosed in this invention first identify the grid boundary, determine the shell elements located at the boundary position in the grid, and then determine the shell elements that make up the same grid based on the shared edge relationship between the shell elements.

[0131] In one embodiment, step S2 includes:

[0132] S21. Traverse all element edges of any shell element in the model, identify the common edge elements of the currently traversed element edge, and generate the common edge element information of the element edge.

[0133] S22. Compare the information of the common edge units of the current unit edge with the grid boundary determination conditions to identify the grid boundary.

[0134] S23. If the current element edge is not identified as a grid boundary, identify the common element of the element edge, repeatedly traverse all element edges of the common element, identify the grid boundary in the common element, until the common element of the currently traversed element edge is only the shell element to which the current element edge belongs.

[0135] As mentioned above, any element edge has at least one shared element, which is the shell element to which it belongs. If two shell elements have a common edge, then both shell elements have two shared elements.

[0136] The above-mentioned conditions for determining the grid boundary include:

[0137] If the information of the common edge elements of an element meets any of the following criteria, then the element edge is identified as a grid boundary:

[0138] (1) There is a beam element on the edge of the current element;

[0139] (2) The current cell has only one cell sharing an edge;

[0140] (3) The current cell has at least three cells sharing the same edge;

[0141] (4) The current unit has two units sharing the same edge, and the angle between the normal vectors of the two units sharing the same edge is less than the preset threshold for the angle between the normal vectors.

[0142] The specific implementation of steps S21-S23 above is illustrated with an example:

[0143] (1) Define an element set EA and put all shell elements of the finite element model into this set;

[0144] (2) Define a grid set PA to store the grid currently being traversed;

[0145] (3) Define an empty set of cells EP, and then define an empty set of cells ED. Take any shell cell from set EA and put it into set EP;

[0146] (4) Take any shell element ei from the set EP, traverse each element edge of shell element ei, and determine whether the currently traversed element edge satisfies the plate boundary determination condition. If it does not satisfy the condition, and the shell element ec that shares an edge with this element edge does not exist in the sets ED and EP, then put the element ec that shares an edge into the set EP. If it satisfies the condition, then do not process it.

[0147] (5) After each side is completed, remove the unit ei from the set EP and put ei into the set ED;

[0148] (6) If the number of units in set EP is greater than 0, repeat step (4). If the number of units in set EP is equal to 0, it means that all the shell units associated with the current grid have been determined. Put all the shell units in set ED into grid set PA as a grid, and then remove all the shell units in ED from EA.

[0149] (7) If the number of shell elements in set EA is greater than 0, repeat step (3); if the number of shell elements in set EA is equal to 0, it means that each shell element of the finite element model has been processed and the plate identification process ends.

[0150] For example, Figure 2 The diagram shown is a partial schematic of a three-dimensional finite element model containing planar plates. The model includes: longitudinal ribs (beam elements) a, double-layer bottom longitudinal girder b, ribs c, and the outer bottom of the ship d. Figure 2 The black box in the middle represents the grid to be identified. The ★ in the figure indicates the starting unit of the traversal. Figure 3 The process of identifying the grid boundaries of a planar grid is illustrated exemplarily: Figure 3 (a) The element edges identified in the currently traversed shell elements that have beam elements, element edges that have three or more shared edge elements, and element edges that have only one shared edge element (themselves). Figure 3 (b)- Figure 3 (e) represents the element edges of beam elements identified during the loop traversal, element edges with three or more shared edge elements, and element edges with only one shared edge element (itself). This indicates an element edge identified as having a beam element. This indicates a cell edge identified as having three or more shared edge elements. This indicates a cell edge that shares only one edge with itself. Figure 4 The diagram shown is a partial schematic of a three-dimensional finite element model containing curved panel grids. The model includes: longitudinal skeleton (beam element) a, rib plate c, and bilge e. Figure 5 The process of identifying the grid boundaries of a curved panel is illustrated exemplarily: Figure 5 (a) The element edges identified in the currently traversed shell elements that have beam elements, element edges that have three or more shared edge elements, and element edges that have only one shared edge element (themselves). Figure 5 (b)- Figure 5 (e) represents the element edges of beam elements identified during the loop traversal, element edges with three or more shared edge elements, and element edges with only one shared edge element (itself). This indicates an element edge identified as having a beam element. This indicates a cell edge identified as having three or more shared edge elements. This indicates a cell edge that shares only one edge with itself.

[0151] S3. Based on the correspondence between shell elements and nodes, and the correspondence between shell elements and plate grids, determine the nodes corresponding to the plate grids.

[0152] As described above, the nodes included in each shell element are determined according to the correspondence between shell elements and nodes, and the shell elements included in each plate grid are determined according to the correspondence between shell elements and plate grids. Thus, the nodes included in each plate grid in the three-dimensional finite element model can be determined.

[0153] S4. Determine the type of plate grid based on the nodes corresponding to the plate grid, and identify the contour nodes of different types of plate grids. The types of plate grids include: planar plate grids and curved plate grids.

[0154] As described above, a planar grid is a grid in which all contour nodes are on the same plane, while a curved grid is a grid in which some contour nodes are not on the same plane. Contour nodes mainly refer to nodes located on the edges of the grid.

[0155] In one embodiment, step S4 includes:

[0156] S41. Determine the type of grid based on the nodes corresponding to the grid.

[0157] S42. Establish a first local coordinate system for identifying contour nodes based on the type of grid, and determine the coordinates of the nodes in the grid in the first local coordinate system.

[0158] S43. Based on the coordinates of the nodes in the first local coordinate system, the contour nodes of the grid are identified using the planar point cloud contour recognition method.

[0159] In the embodiments of the present invention, a planar point cloud contour recognition method is used to identify contour nodes. This method requires identifying the features of the grid, which are represented by the coordinates of the nodes; therefore, a local coordinate system needs to be established. For planar grids, the first local coordinate system is a spatial rectangular coordinate system; for curved grids, the first local coordinate system is a curved surface coordinate system.

[0160] In one embodiment, step S41 includes:

[0161] S411. Identify a grid with three nodes as a planar grid.

[0162] S412. For a grid with more than three nodes, use any three non-collinear nodes to determine a plane, calculate the normal vector of the plane, establish vectors between any node in the plane and the remaining nodes in the grid, calculate the angle between the established vector and the normal vector, and if any angle is less than the angle threshold, then the grid is identified as a curved grid.

[0163] In the above embodiments of the invention, the grid type is determined by the number of nodes included in the grid. For a planar grid, three points define a plane; therefore, a grid with only three nodes is necessarily a planar grid. For a curved grid, a plane is first defined, then the normal vector of that plane is determined. If the angle between the normal vector and the normal vector satisfies an angle threshold, then the grid is a curved grid. Generally, the angle threshold is less than... , A very small angle value determined for the user.

[0164] For example, step S41 specifically includes:

[0165] (1) If the number of grid nodes is 3, it means that the current grid has only one triangular element, and therefore it must be a planar grid;

[0166] (2) If the number of grid nodes is greater than 3, first use three non-collinear nodes N1, N2 and N3 to determine a plane, and calculate the plane normal. For the remaining nodes of the lattice, the vector is calculated by iterating through each node Ni. and plane normal vector The included angle, as long as one of the included angle values ​​is less than the angle threshold ( , If point Ni is not on the plane (e.g., a very small angle value determined by the user), then the current grid is marked as a curved grid; otherwise, it is marked as a planar grid.

[0167] In one embodiment, step S42 includes:

[0168] For a planar plate grid, a spatial rectangular coordinate system is established based on the nodes within any shell element of the planar plate grid, and the coordinates of the nodes in the first local coordinate system are determined.

[0169] For a curved panel grid, select any two shell elements that share an edge but are not coplanar within the grid. Based on two nodes on the common edge of the two shell elements and nodes on the non-common edge of any one of the two shell elements, determine the plane and calculate the normal vector of the plane. Based on any vector and normal vector in the plane and using the right-hand rule, establish the first local spatial coordinate system of the grid. Project the node coordinates in the first local spatial coordinate system onto the planar coordinate system to determine the coordinates of the nodes in the first local coordinate system.

[0170] As described above, the embodiments of the present invention determine the first local coordinate system of the grid for identifying the boundary contour points of the grid, and calculate the coordinates of all nodes of the grid in the first local coordinate system through spatial coordinate transformation. The curved grid also needs to project all nodes onto the XOY plane of the first local coordinate system.

[0171] For example, step S42 specifically includes:

[0172] (1) The steps for determining the first local coordinate system of the curved panel grid include:

[0173] Let N1 be the first node of the first unit in the grid association, N2 be the first node of the first unit, and N3 be the first node of the first unit. Then, the local coordinate system has node N1 as its origin and vector N3 as its coordinate system. The X-axis is the vector. and The plane formed is normal to the Z-axis, and the local coordinate system Y-axis is determined based on the X-axis and Z-axis using the right-hand rule.

[0174] (2) The steps for determining the first local coordinate system and projecting nodes of the curved panel grid include:

[0175] From all the elements in the grid, select an element eo with adjacent elements ea that share an edge but do not share a plane, and the nodes on the common edge are Ni and Nj respectively;

[0176] Let N2 be a node of element ea that does not belong to eo, and let N1 be the node of nodes Ni and Nj that is closer to node N2, and N3 be the other node.

[0177] Determine the local coordinate system of the projection, with node N1 as the origin and vector... The X-axis is the vector. and The plane formed is normal to the Z-axis. The local coordinate system Y-axis is determined by the right-hand rule based on the X-axis and Z-axis.

[0178] The coordinates of all nodes of the curved panel grid in the projected coordinate system are calculated using the coordinate transformation method, and the Z value of all nodes is set to 0 to complete the projection of the nodes onto the local coordinate system XOY plane.

[0179] In one embodiment, step S43 includes:

[0180] S431. Identify the features of the grid, which include: convex hull features and concave features.

[0181] S432. Use Gamham scanning to identify the contour nodes of the grid with convex hull features.

[0182] S433. Use Alpha shapes to process the grid with concave features and identify the outline nodes of the grid.

[0183] As mentioned above, Gamham scanning and Alpha shapes are two common planar point cloud contour recognition algorithms. The contour nodes obtained by both algorithms are stored in a counterclockwise order.

[0184] S5. Traverse the contour nodes and group them according to the node grouping conditions, so that each group of contour nodes corresponds to the same edge of the grid.

[0185] The node grouping conditions mentioned above include: determining whether the angle between two adjacent vectors satisfies the same-side angle threshold; if it does, then identifying the three contour nodes corresponding to the same grid edge; if not, then identifying the three contour nodes corresponding to two different grid edges. Generally, the same-side angle threshold is greater than... , A very small angle value determined for the user.

[0186] For example, since the contour nodes are sorted counterclockwise, all nodes associated with the circular grid are assumed to be three consecutive nodes. Where i represents the index of the point, if the vector sum vector If the included angle is greater than the angle threshold (α, a value that can be set by the user and is close to 180°), then the determination point is... If they are on the same side, otherwise consider the point to be on the same side. The second point on the next side, point The last point of the current edge is also the first point of the next edge. By repeating this rule, the number of edges of the grid and the contour nodes on each edge can be determined.

[0187] For example, Figure 6 It consists of contour nodes and node groups identified by the planar grid. The first local coordinate system is established based on the contour nodes of the grid in the figure. Figure 7 This refers to the contour nodes and node groups identified by the curved panel grid. The first local coordinate system is established based on the contour nodes of the grid. × in the figure represents contour nodes.

[0188] Based on the steps S1-S5 above, the method disclosed in this embodiment of the invention determines the contour nodes and type of the plate grid by identifying the shell elements and nodes included in the plate grid, and also identifies the correspondence between the nodes and the plate grid edges. Thus, all types of plate grids included in the three-dimensional finite element model can be identified. This embodiment of the invention employs a traversal loop algorithm and sets an algorithm termination condition, without setting an upper limit on the number of plate grids identified, thus comprehensively and completely identifying the plate grids included in the model.

[0189] In one embodiment, the plate recognition method disclosed in this invention further includes:

[0190] S6. Determine the first coordinate system node, the second coordinate system node, and the third coordinate system node on the plate grid, and establish a second local coordinate system for stress transformation.

[0191] The first coordinate system node, the second coordinate system node, and the third coordinate system node are points used to determine the origin, X-axis, Y-axis, and Z-axis of the second layout coordinate system. The three nodes can be nodes on the grid in the model, or they can be virtual nodes selected according to the grid edge size.

[0192] In one embodiment, step S6 includes:

[0193] S61. For a planar grid, identify whether the grid is a regular grid or an irregular grid based on the number of grid edges corresponding to the grid. Determine the first coordinate system node, the second coordinate system node, and the third coordinate system node according to the coordinate system node determination rules for regular or irregular grids.

[0194] For curved grid panels, the length of each grid edge determines whether it is a straight edge or a curved edge. The grid edges are arranged in the order of curved edge-straight edge-curved edge-straight edge. The first coordinate system node, the second coordinate system node, and the third coordinate system node are determined according to the rules for determining the coordinate system nodes of the curved grid panels.

[0195] S62. Determine the first coordinate system node as the origin of the second local coordinate system. The vector constructed from the origin of the second local coordinate system to the second coordinate system node is taken as the X-axis. The normal vector of the plane determined by the first coordinate system node, the second coordinate system node, and the third coordinate system node is taken as the Z-axis. The cross product vector of the X-axis and the Z-axis is taken as the Y-axis.

[0196] For example, for a planar grid:

[0197] (1) If the number of sides of the grid is equal to 2 (such as the bilge elbow, whose boundary is formed by a straight edge and a circular arc), 3 or greater than 4, then the current grid is determined to be an irregular grid.

[0198] (2) For irregular grids with 2 sides: determine the straight edge by the nodes of each side, and mark the first node of the straight edge as N1, the last node of the straight edge as N2, and any point on the curved edge other than N1 and N2 as N3.

[0199] (3) For irregular grids with 3 sides: calculate the lengths of the three medians of the triangle formed by the three sides of the grid, and denote the vertex with the longest median as N1, the midpoint of the side opposite N1 as N2, and any endpoint of the side opposite N1 as N3.

[0200] (4) For grids with 4 sides: Based on the length of each side of the grid, adjust the order of the four sides to long-short-long-short. There are two cases: Case 1: If the length difference between the two long sides and the two short sides does not exceed 10%, the current grid is still considered a regular grid. Record the first node of the first side N1, the last node of the first side N2, and the first node of the fourth side N3. Take the average length of the first and third sides as the long side length a, and the average length of the second and fourth sides as the short side length b. Case 2: If the length difference between the two long sides and the two short sides exceeds 10%, the current grid is considered an irregular grid. Record the midpoint of one short side as N1, the midpoint of the other short side as N2, and any node on any long side as N3.

[0201] (5) For a grid with 5 sides: Calculate the included angle between every two adjacent sides, for a total of 5 angle values. Select the four nodes closest to 90° as the four corner nodes C1, C2, C3 and C4 (distributed counterclockwise along the grid boundary). Calculate the lengths d1, d2, d3 and d4 of the four sides formed by these four points, and determine the size of d1+d3 and d2+d4. If d1+d3 is larger, then mark the midpoint of C1 and C4 as N1, the midpoint of C2 and C3 as N2, and any point from C1 to C4 as N3. If d2+d4 is larger, then mark the midpoint of C1 and C2 as N1, the midpoint of C3 and C4 as N2, and any point from C1 to C4 as N3.

[0202] (6) For grids with more than 5 sides: Adjust the order of the grid sides, with the side with the longest length as the first, and the other sides are still arranged in counterclockwise order. Calculate the distance between the first node N1 of the first side and the endpoints of the other sides in turn. Record the endpoint with the largest distance as N1 and any other endpoint as N2.

[0203] For example, for curved panel grids:

[0204] (1) Calculate the length of each side of the grid using the nodes of each side of the grid (the number of curved grid boundaries must be equal to 4).

[0205] (2) Determine the curved edge and the straight edge according to the length of each side, and adjust the order of the edges to curved edge-straight edge-curved edge-straight edge.

[0206] (3) Determine the local coordinate system of the curved panel grid, and record the first node N1 of the first side, the last node N2 of the first side, and the first node N3 of the fourth side.

[0207] In the example above, N1 is the first coordinate node, N2 is the second coordinate node, and N3 is the third coordinate node.

[0208] In one embodiment, the method disclosed in this invention further includes:

[0209] S63. Calculate the dimensions of each edge of the grid:

[0210] For a planar grid, calculate the long and short side dimensions of the planar grid based on the dimensions of each grid edge;

[0211] For curved panel grids, determine whether the grid edge is straight or curved based on the dimensions of each grid edge, calculate the radius and length of the curved edge, as well as the short side dimension of the curved panel grid.

[0212] As mentioned above, for planar grids, the boundary dimensions refer to the dimensions of the long side and the short side; for curved grids, the boundary dimensions refer to the radius of the arc, the arc length, and the width of the short side.

[0213] For example, for a planar grid:

[0214] (1) Calculate the dimensions of each edge of the planar grid.

[0215] (2) For irregular grids with 2 sides: the length of the straight side is the long side length a, and the total area A of the grid is divided by the long side length a to get the short side length b.

[0216] (3) For irregular grids with 3 sides: Let the length of the longest centerline be L1, the total area of ​​the grid divided by the length of the longest side be L2, and let the coefficient C be... Then the length of the longer side of the current irregular grid is determined to be... The length of the shorter side is .

[0217] (4) For a grid with 4 sides: the distance between N1 and N2 is the length of the long side of the grid, a, and the total area of ​​the grid A divided by the length of the long side is the length of the short side of the grid, b.

[0218] (5) For a grid with 5 sides: the length a of the long side of the grid is the distance between N1 and N2, and the length b of the short side of the grid is the total area A of the grid divided by the length a of the long side.

[0219] (6) For grids with more than 5 sides: determine the maximum distance as the length of the long side a, and the length of the short side b as the total area A of the grid divided by the length of the long side a.

[0220] For example, for curved panel grids:

[0221] (1) Select any curved edge and select three nodes on the curved edge that are close to the middle of the curved edge. Calculate the radius R and length of the curved edge.

[0222] (2) Select any short side and calculate the width D of the short side of the curved panel grid.

[0223] For example, Figure 6The diagram shows the identification of the long and short sides of a regular planar grid with four grid edges. In the diagram, the grid edge corresponding to the first contour node and the grid edge corresponding to the third set of contour nodes are identified as long sides, while the second set of contour nodes and the fourth set of contour nodes are identified as short sides. Figure 7 The diagram shows the recognition of straight and curved edges of curved panel grids. In the diagram, the grid edges corresponding to the first and fourth sets of contour nodes are recognized as curved edges, while the grid edges corresponding to the second and third sets of contour nodes are recognized as straight edges.

[0224] S7. Use the coordinate transformation matrix to transform the centroid of each shell element in the plate grid from the global coordinate system to the second local coordinate system.

[0225] As mentioned above, the coordinates of the centroids of each shell element in the global coordinate system can be obtained in the three-dimensional finite element model.

[0226] S8. Using the stress coordinate transformation relationship, the stress in the global coordinate system is transformed into the second local coordinate system, and the equivalent stress of the plate is calculated.

[0227] As mentioned above, the stress in the global coordinate system can be obtained in the three-dimensional finite element model.

[0228] In one embodiment, step S9 includes:

[0229] The stress in the lattice under global coordinates is transformed to a second local coordinate system using stress coordinate transformation relationships. The equivalent stress of the lattice is calculated using an interpolation algorithm based on the lattice type. The stress coordinate transformation relationships include:

[0230]

[0231] in Let be the stress tensor of the plate lattice in the second local coordinate system. Let be the stress tensor of the plate lattice in the global coordinate system. Let be the cosine of the angle between the coordinate axes of the global coordinate system and the second local coordinate system.

[0232] like Figure 8 As shown, based on the plate grid recognition method disclosed in the above embodiments of the present invention, the present invention also discloses a three-dimensional finite element model plate grid recognition device, comprising:

[0233] The model acquisition module 801 is used to acquire a three-dimensional finite element model. The model includes a plate grid, which is divided into at least one shell element. The shell element includes nodes and element edges.

[0234] As described above, the 3D finite element model is generated from user-imported 3D finite element model data. The finite element model is divided into a large number of lattices, and each lattice is further divided into multiple shell elements. The finite element model data includes: element topology information, which includes the correspondence between various types of elements and lattices in the 3D finite element model. The correspondence between nodes and shell elements is then supplemented based on the model data.

[0235] The element determination module 802 is used to traverse the element edges of the shell elements, identify the grid boundaries in the element edges according to the grid boundary determination conditions, and determine the shell elements that make up the grid.

[0236] As mentioned above, the element edge refers to the boundary of the shell element, and the grid boundary refers to the grid edge or a part of the grid edge. The embodiments disclosed in this invention first identify the grid boundary, determine the shell elements located at the boundary position in the grid, and then determine the shell elements that make up the same grid based on the shared edge relationship between the shell elements.

[0237] In one embodiment, the unit determining module 802 includes:

[0238] The common edge unit information generation module is used to traverse all element edges of any shell element in the model, identify the common edge units of the currently traversed element edge, and generate the common edge unit information of the element edge.

[0239] The boundary recognition module is used to compare the common edge information of the current unit edge with the plate boundary determination conditions to identify the plate boundary. If the current unit edge is not determined as the plate boundary, the common edge of the unit edge is identified, and all unit edges of the common edge are repeatedly traversed to identify the plate boundary in the common edge, until the common edge of the currently traversed unit edge is only the shell unit to which the current unit edge belongs.

[0240] The above-mentioned conditions for determining the grid boundary include:

[0241] If the information of the common edge elements of an element meets any of the following criteria, then the element edge is identified as a grid boundary:

[0242] (1) There is a beam element on the edge of the current element;

[0243] (2) The current cell has only one cell sharing an edge;

[0244] (3) The current cell has at least three cells sharing the same edge;

[0245] (4) The current unit has two units sharing the same edge, and the angle between the normal vectors of the two units sharing the same edge is less than the preset threshold for the angle between the normal vectors.

[0246] The node determination module 803 is used to determine the nodes corresponding to the plate grid based on the correspondence between shell elements and nodes, and the correspondence between shell elements and plate grids.

[0247] As described above, the nodes included in each shell element are determined according to the correspondence between shell elements and nodes, and the shell elements included in each plate grid are determined according to the correspondence between shell elements and plate grids. Thus, the nodes included in each plate grid in the three-dimensional finite element model can be determined.

[0248] The contour node recognition module 804 is used to determine the type of board grid based on the nodes corresponding to the board grid, and to identify the contour nodes of different types of board grids. The types of board grids include: planar board grids and curved board grids.

[0249] As described above, a planar grid is a grid in which all contour nodes are on the same plane, while a curved grid is a grid in which some contour nodes are not on the same plane. Contour nodes mainly refer to nodes located on the edges of the grid.

[0250] In one embodiment, the contour node recognition module 804 includes:

[0251] The first type determination module is used to determine the type of the grid based on the nodes corresponding to the grid.

[0252] The first local coordinate system establishment module is used to establish a first local coordinate system for identifying contour nodes based on the type of the grid, and to determine the coordinates of the nodes in the grid in the first local coordinate system.

[0253] The contour recognition module is used to identify the contour nodes of the grid based on the coordinates of the nodes in the first local coordinate system using the planar point cloud contour recognition method.

[0254] In one embodiment, the first type determination module is specifically used for:

[0255] Identify a grid with three nodes as a planar grid;

[0256] For a grid with more than three nodes, a plane is determined using any three non-collinear nodes. The normal vector of the plane is calculated. Vectors are established between any node in the plane and the remaining nodes in the grid. The angle between the established vector and the normal vector is calculated. If any angle is less than the angle threshold, the grid is identified as a curved grid.

[0257] In one embodiment, the first local coordinate system establishment module is specifically used for:

[0258] For a planar plate grid, a spatial rectangular coordinate system is established based on the nodes within any shell element of the planar plate grid, and the coordinates of the nodes in the first local coordinate system are determined.

[0259] For a curved panel grid, select any two shell elements that share an edge but are not coplanar within the grid. Based on two nodes on the common edge of the two shell elements and nodes on the non-common edge of any one of the two shell elements, determine the plane and calculate the normal vector of the plane. Based on any vector and normal vector in the plane and using the right-hand rule, establish the first local spatial coordinate system of the grid. Project the node coordinates in the first local spatial coordinate system onto the planar coordinate system to determine the coordinates of the nodes in the first local coordinate system.

[0260] In one embodiment, the contour recognition module includes:

[0261] The feature recognition module is used to identify the features of the grid, which include convex hull features and concave features.

[0262] The Gamham scanning module is used to scan lattices with convex hull features using Gamham scanning to identify the contour nodes of the lattice.

[0263] The Alpha shapes processing module is used to process grids with concave features using Alpha shapes and to identify the outline nodes of the grids.

[0264] Grouping module 805 is used to traverse contour nodes and group contour nodes according to node grouping conditions, so that each group of contour nodes corresponds to the same edge of the grid.

[0265] The node grouping conditions mentioned above include: determining whether the angle between two adjacent vectors satisfies the same-side angle threshold. If it does, then the three contour nodes are identified as corresponding to the same grid edge; if not, then the three contour nodes are identified as corresponding to two different grid edges. Generally, the same-side angle threshold is greater than 180° - θ, where θ is a very small angle value determined by the user.

[0266] In one embodiment, the grouping module 805 includes:

[0267] The angle determination module is used to traverse the contour nodes corresponding to the grid, establish two vectors using three adjacent contour nodes, and determine the angle between the two adjacent vectors.

[0268] The judgment module is used to determine whether the included angle between two adjacent vectors meets the same side angle threshold. If it does, the three contour nodes are identified as corresponding to the same grid edge. If they do not meet the threshold, the three contour nodes are identified as corresponding to two different grid edges.

[0269] In one embodiment, the plate identification device disclosed in this invention further includes:

[0270] The second local coordinate system establishment module is used to determine the first coordinate system nodes, the second coordinate system nodes, and the third coordinate system nodes on the plate grid, and to establish a second local coordinate system for stress transformation.

[0271] The first coordinate system node, the second coordinate system node, and the third coordinate system node are points used to determine the origin, X-axis, Y-axis, and Z-axis of the second layout coordinate system. The three nodes can be nodes on the grid in the model, or they can be virtual nodes selected according to the grid edge size.

[0272] The coordinate transformation module is used to transform the centroid of each shell element in the plate grid from the global coordinate system to the second local coordinate system using the coordinate system transformation matrix.

[0273] The equivalent stress calculation module is used to transform the stress in the global coordinate system to the second local coordinate system using the stress coordinate transformation relationship, and to calculate the equivalent stress of the plate.

[0274] In one embodiment, the second local coordinate system establishment module includes:

[0275] The coordinate system node determination module is used for:

[0276] For a planar grid, the grid is identified as either a regular grid or an irregular grid based on the number of grid edges. The first coordinate system node, the second coordinate system node, and the third coordinate system node are determined according to the coordinate system node determination rules for regular or irregular grids.

[0277] For curved grid panels, the length of each grid edge determines whether it is a straight edge or a curved edge. The grid edges are arranged in the order of curved edge-straight edge-curved edge-straight edge. The first coordinate system node, the second coordinate system node, and the third coordinate system node are determined according to the rules for determining the coordinate system nodes of the curved grid panels.

[0278] The coordinate system establishment module is used to determine the first coordinate system node as the origin of the second local coordinate system. The vector constructed from the origin of the second local coordinate system to the second coordinate system node is used as the X-axis. The normal vector of the plane determined by the first coordinate system node, the second coordinate system node, and the third coordinate system node is used as the Z-axis. The cross product vector of the X-axis and the Z-axis is used as the Y-axis.

[0279] In one embodiment, the equivalent stress calculation module is specifically used for:

[0280] The stress in the lattice under global coordinates is transformed to a second local coordinate system using stress coordinate transformation relationships. The equivalent stress of the lattice is calculated using an interpolation algorithm based on the lattice type. The stress coordinate transformation relationships include:

[0281]

[0282] in Let be the stress tensor of the plate lattice in the second local coordinate system. Let be the stress tensor of the plate lattice in the global coordinate system. Let be the cosine of the angle between the coordinate axes of the global coordinate system and the second local coordinate system.

[0283] In one embodiment, the plate identification device disclosed in this invention further includes:

[0284] The board edge dimension calculation module is used for:

[0285] For a planar grid, calculate the long and short side dimensions of the planar grid based on the dimensions of each grid edge;

[0286] For curved panel grids, determine whether the grid edge is straight or curved based on the dimensions of each grid edge, calculate the radius and length of the curved edge, as well as the short side dimension of the curved panel grid.

[0287] In addition, this invention also provides an electronic device, including:

[0288] One or more processors; and

[0289] A memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the methods disclosed in the above embodiments.

[0290] in, Figure 9 An exemplary system architecture of an electronic device is shown, which may specifically include a processor 910, a video display adapter 911, a disk drive 912, an input / output interface 913, a network interface 914, and a memory 920. The processor 910, video display adapter 911, disk drive 912, input / output interface 913, network interface 914, and memory 920 can communicate with each other via a communication bus 930.

[0291] The processor 910 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to achieve the technical solution provided in this application.

[0292] The memory 920 can be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 920 can store the operating system 921 for controlling the operation of the electronic device, and the basic input / output system (BIOS) for controlling the low-level operations of the electronic device. Additionally, it can store a web browser 923, a data storage management system 924, and a device identification information processing system 925, etc. The aforementioned device identification information processing system 925 can be the application program that specifically implements the aforementioned steps in this embodiment. In summary, when the technical solution provided in this application is implemented through software or firmware, the relevant program code is stored in the memory 920 and is called and executed by the processor 910.

[0293] Input / output interface 913 is used to connect input / output modules to realize information input and output. Input / output modules can be configured as components in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. Input devices may include keyboards, mice, touch screens, microphones, various sensors, etc., and output devices may include displays, speakers, vibrators, indicator lights, etc.

[0294] Network interface 914 is used to connect a communication module (not shown in the figure) to enable communication between this device and other devices. The communication module can communicate via wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0295] Bus 930 includes a pathway for transmitting information between various components of the device, such as processor 910, video display adapter 911, disk drive 912, input / output interface 913, network interface 914, and memory 920.

[0296] In addition, the electronic device can also obtain information on specific claim conditions from the virtual resource object claim condition information database for condition judgment, and so on.

[0297] It should be noted that although the above-described device only shows the processor 910, video display adapter 911, disk drive 912, input / output interface 913, network interface 914, memory 920, bus 930, etc., in specific implementations, the device may also include other components necessary for normal operation. Furthermore, those skilled in the art will understand that the above-described device may only include the components necessary for implementing the solution of this application, and does not necessarily include all the components shown in the figures.

[0298] Specifically, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from a memory, or installed from ROM. When the computer program is executed by a processor, it performs the functions defined above in the methods of embodiments of this application.

[0299] It should be noted that the computer-readable medium in the embodiments of this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In the embodiments of this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In the embodiments of this application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (Radio Frequency), etc., or any suitable combination thereof.

[0300] The aforementioned computer-readable medium may be included in the aforementioned server; or it may exist independently and not assembled into the server. The aforementioned computer-readable medium carries one or more programs that, when executed by the server, cause the server to: in response to detecting that the peripheral mode of the terminal is not activated, acquire the frame rate of the application on the terminal; when the frame rate meets the screen-off condition, determine whether the node is acquiring the screen information of the terminal; and in response to the determination that the node is not acquiring the screen information of the terminal, control the screen to enter an immediate dimming mode.

[0301] Computer program code for performing the operations of the embodiments of this application can be written in one or more programming languages ​​or a combination thereof. Programming languages ​​include object-oriented programming languages—such as Java, Smalltalk, and C++—and conventional procedural programming languages—such as the "C" language or similar programming languages. The program code can be executed entirely on the node computer, partially on the node computer, as a standalone software package, partially on the node computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the node computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0302] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0303] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0304] All the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of the present invention, and will not be described in detail here.

[0305] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for identifying plate grids in a three-dimensional finite element model, characterized in that, include: A three-dimensional finite element model is obtained, the model including: a plate grid, the plate grid being divided into at least one shell element, the shell element including: nodes and element edges; Traverse the edges of the shell units, identify the grid boundaries in the edges of the units according to the grid boundary determination conditions, and determine the shell units that make up the grid. Based on the correspondence between the shell unit and the node, and the correspondence between the shell unit and the plate grid, determine the node corresponding to the plate grid; The type of the plate is determined based on the nodes corresponding to the plate, and the contour nodes of different types of plate are identified. The types of plate include: planar plate and curved plate. Traverse the outline nodes and group them according to the node grouping conditions, so that each group of outline nodes corresponds to the same edge of the grid. The step of determining the type of the grid based on the nodes corresponding to the grid, and identifying the contour nodes of different types of grids, includes: The type of the grid is determined based on the node corresponding to the grid. Based on the type of the grid, a first local coordinate system is established for identifying the contour nodes. The coordinates of the nodes in the grid in the first local coordinate system are determined as follows: For the planar grid, a spatial rectangular coordinate system is established based on the nodes in any shell unit of the planar grid, and the coordinates of the nodes in the first local coordinate system are determined. For the curved grid, any two shell units that share an edge but are not coplanar are selected in the grid. Based on the two nodes on the common edge of the two shell units and the nodes on the non-common edge in any one of the two shell units, a plane is determined and the normal vector of the plane is calculated. Based on any vector and the normal vector in the plane and using the right-hand rule, a first local spatial coordinate system of the grid is established. The coordinates of the nodes in the first local spatial coordinate system are projected onto the planar coordinate system to determine the coordinates of the nodes in the first local coordinate system. Based on the coordinates of the node in the first local coordinate system, the contour nodes of the grid are identified using a planar point cloud contour recognition method: the features of the grid are identified, including convex hull features and concave features; Gamham scanning is used to identify the contour nodes of the grid with convex hull features; Alpha shapes are used to process the grid with concave features to identify the contour nodes of the grid.

2. The method as described in claim 1, characterized in that, The step of traversing the cell edges of the shell cells, identifying the grid boundaries in the cell edges according to the grid boundary determination conditions, and determining the shell cells that make up the grid includes: Traverse all the edges of any shell element in the model, identify the common edge elements of the currently traversed edge elements, and generate the common edge element information of the edge elements; The boundary of the grid is identified by comparing the information of the common edge units of the current unit with the grid boundary determination conditions. If the current unit edge is not determined as the grid boundary, then identify the common edge unit of the unit edge, repeatedly traverse all the unit edges of the common edge unit, identify the grid boundary in the common edge unit, until the common edge unit of the currently traversed unit edge is only the shell unit to which the current unit edge belongs.

3. The method as described in claim 2, characterized in that, The step of comparing the common edge information of the current unit edge with the grid boundary determination condition to identify the grid boundary includes: If the shared edge information of the unit edge meets any of the following criteria, then the unit edge is identified as the grid boundary: There are beam elements on the edge of the current element; Currently, there is only one shared edge unit among the current unit edges; The currently described unit has at least three shared edge units; The current unit edge has two shared edge units, and the angle between the normal vectors of the two shared edge units is less than a preset normal vector angle threshold.

4. The method as described in claim 1, characterized in that, Determining the type of the grid based on the node corresponding to the grid includes: Obtain the number of nodes corresponding to the grid; Identify the grid with three nodes as a planar grid; For a grid with more than three nodes, a plane is determined using any three non-collinear nodes, and the normal vector of the plane is calculated. Vectors are established between any node in the plane and the remaining nodes of the grid. The angle between the established vector and the normal vector is calculated. If any angle satisfies an angle threshold, the grid is identified as a curved grid.

5. The method as described in claim 1, characterized in that, The step of traversing the contour nodes and grouping them according to node grouping conditions, such that each group of contour nodes is associated with the same edge of the grid, includes: Traverse the contour nodes corresponding to the grid, establish two vectors using three adjacent contour nodes, and determine the included angle between the two adjacent vectors; Determine whether the included angle between two adjacent vectors satisfies the same-side angle threshold. If it does, identify the three contour nodes corresponding to the same grid edge. If it does not, identify the three contour nodes corresponding to two different grid edges.

6. The method according to any one of claims 1-5, characterized in that, The method further includes: Determine the first coordinate system node, the second coordinate system node, and the third coordinate system node on the plate grid, and establish a second local coordinate system for stress transformation; The centroids of each shell element in the plate grid are transformed from the global coordinate system to the second local coordinate system using a coordinate system transformation matrix; By utilizing the stress coordinate transformation relationship, the stress in the global coordinate system is transformed into the second local coordinate system, and the equivalent stress of the plate grid is calculated.

7. The method as described in claim 6, characterized in that, The step of determining the first coordinate system nodes, the second coordinate system nodes, and the third coordinate system nodes on the plate grid, and establishing a second local coordinate system for stress transformation, includes: For the planar grid, based on the number of grid edges corresponding to the grid, identify whether the grid is a regular grid or an irregular grid, and determine the first coordinate system node, the second coordinate system node and the third coordinate system node according to the coordinate system node determination rules for regular or irregular grids; For the curved panel grid, the length of each panel edge determines whether the panel edge is a straight edge or a curved edge. The panel edges are arranged in the order of curved edge-straight edge-curved edge-straight edge. The first coordinate system node, the second coordinate system node, and the third coordinate system node are determined according to the rules for determining the coordinate system nodes of the curved panel grid. The first coordinate system node is determined as the origin of the second local coordinate system. The vector constructed from the origin of the second local coordinate system to the second coordinate system node is taken as the X-axis. The normal vector of the plane determined by the first coordinate system node, the second coordinate system node, and the third coordinate system node is taken as the Z-axis. The cross product vector of the X-axis and the Z-axis is taken as the Y-axis.

8. The method as described in claim 7, characterized in that, The method further includes: Calculate the dimensions of each edge of the grid: For the planar grid, the long side dimension and short side dimension of the planar grid are calculated based on the dimensions of each grid edge; For the curved panel grid, the dimensions of each grid edge are used to determine whether the grid edge is straight or curved. The radius and length of the arc of the curved edge are calculated, as well as the short side dimension of the curved panel grid.

9. The method as described in claim 6, characterized in that, The process of transforming the stress in the input global coordinate system to the second local coordinate system of the plate using stress coordinate transformation relationships, and calculating the equivalent stress of the plate, includes: The stress coordinate transformation relationship is used to transform the plate stress in the global coordinate system to the second local coordinate system. Based on the plate type, the equivalent stress of the plate is calculated using an interpolation algorithm. The stress coordinate transformation relationship includes: in Let be the stress tensor of the plate grid in the second local coordinate system. Let be the stress tensor of the lattice in the global coordinate system. Let be the cosine of the angle between the coordinate axes of the global coordinate system and the second local coordinate system.

10. A plate identification device for a three-dimensional finite element model, used in the method described in any one of claims 1-9, characterized in that, include: The model acquisition module is used to acquire a three-dimensional finite element model, the model including: a plate grid, the plate grid being divided into at least one shell element, the shell element including: nodes and element edges; The unit determination module is used to traverse the unit edges of the shell unit, identify the grid boundaries in the unit edges according to the grid boundary determination conditions, and determine the shell units that make up the grid. The node determination module is used to determine the node corresponding to the plate grid based on the correspondence between the shell unit and the node and the correspondence between the shell unit and the plate grid. The contour node recognition module is used to determine the type of the board grid based on the nodes corresponding to the board grid, and to identify the contour nodes of different types of board grids. The types of board grids include: planar board grids and curved board grids. The grouping module is used to traverse the contour nodes and group the contour nodes according to the node grouping conditions, so that each group of contour nodes corresponds to the same edge of the grid.

11. An electronic device, characterized in that, include: One or more processors; as well as A memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the method as described in any one of claims 1 to 9.

12. A computer-readable medium having a computer program stored thereon, wherein, When the program is executed by the processor, it implements the method as described in any one of claims 1 to 9.

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