A method, apparatus, device, medium and product for drawing a forming limit diagram on a plate

Abstract

The application discloses a kind of on-plate forming limit diagram drawing method, device, equipment, medium and product, it is related to graphics rendering technical field.The method is first together as the main secondary strain value of each grid vertex located on the model outer surface of target sheet metal three-dimensional model is set to corresponding vertex as map coordinates, then for vertex shader, the map coordinates of grid vertex located on corresponding grid patch are transferred to corresponding pixel shader, and the transferred map coordinates are rasterized to obtain pixel map coordinates, then in pixel shader, pixel main secondary strain value is extracted from pixel map coordinates, and pixel color used for drawing forming limit diagram is determined in combination with material parameter, finally pixel color is rendered to model outer surface, whereby color positioning accuracy and FLD demarcation line smoothness can be greatly improved, to improve the perception accuracy of sheet metal rupture risk in turn.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of graphic rendering, and particularly relates to a method and device for drawing a forming limit diagram on a sheet, a computer device, a computer readable storage medium, and a computer program product. BACKGROUND

[0002] A forming limit diagram (FLD) is a graphical representation used to describe the fracture limit of a material under plane stress conditions. It has wide applications in metal forming engineering, aerospace, and automotive manufacturing. By studying the forming limit diagram, engineers can predict the risk of material fracture during the forming process, thereby optimizing process parameters, improving product quality, and reducing production costs. The forming limit diagram mainly includes two parts: the limit strain curve and the fracture point. The limit strain curve represents the maximum plastic strain capacity of the material under plane stress conditions, while the fracture point represents the stress state at which the material begins to fracture.

[0003] Currently, the existing technical solution for drawing a forming limit diagram on the outer surface of a sheet model is as follows: taking a grid facet such as a triangular facet and / or a quadrilateral facet located on the outer surface of the sheet model as the smallest coloring unit, and based on the principal strain value and the secondary strain value of each vertex located on the facet, combining the Keeler formula (which is an existing way for predicting the forming limit diagram of a material) and the material parameters, calculating the area color value of the corresponding facet (for example, using red to represent the fracture area color, yellow to represent the fracture risk area color, green to represent the safe area color, light blue to represent the wrinkling risk area color, pink to represent the wrinkling area color, purple to represent the severe wrinkling area color, gray to represent the effective strain deficiency area color, and so on), and finally obtaining a forming limit diagram on a sheet as shown in Figure 1 .

[0004] However, as shown in Figure 1 , since the smallest coloring unit is a facet rather than a pixel, the above-mentioned existing technical solution will be difficult to meet the requirements of more accurate color positioning and smoother FLD boundary line drawing. SUMMARY

[0005] The purpose of the present application is to provide a method and device for drawing a forming limit diagram on a sheet, a computer device, a computer readable storage medium, and a computer program product, to solve the problem that the existing forming limit diagram drawing scheme on a sheet is difficult to meet the requirements of more accurate color positioning and smoother FLD boundary line drawing.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, a method for drawing a forming limit diagram on a sheet is provided, comprising:

[0008] obtaining the principal strain value and the secondary strain value of each grid vertex located on the model outer surface of the target sheet metal three-dimensional model;

[0009] for each grid vertex, setting the corresponding principal strain value and secondary strain value together as a map coordinate to the corresponding vertex;

[0010] for each grid patch located on the model outer surface, setting a corresponding vertex shader and a pixel shader;

[0011] for the vertex shader, passing the map coordinates of the grid vertices located on the corresponding grid patch to the corresponding pixel shader;

[0012] rasterizing the passed map coordinates to the pixel shader, so that the pixel shader obtains pixel map coordinates calculated by an interpolation algorithm during rasterization;

[0013] in the pixel shader, extracting the pixel principal strain value and the pixel secondary strain value from the pixel map coordinates, and combining the material parameters of the target sheet metal three-dimensional model to determine the pixel color for drawing the forming limit diagram;

[0014] rendering the pixel color to the model outer surface to obtain the completed drawing of the sheet forming limit diagram.

[0015] Based on the above invention content, a new scheme for sheet forming limit diagram drawing with pixels as the minimum coloring unit is provided, that is, the principal and secondary strain values of each grid vertex located on the model outer surface of the target sheet metal three-dimensional model are set together as a map coordinate to the corresponding vertex, then for the vertex shader, the map coordinates of the grid vertices located on the corresponding grid patch are passed to the corresponding pixel shader, and the passed map coordinates are rasterized to obtain pixel map coordinates, then in the pixel shader, the pixel principal and secondary strain values are extracted from the pixel map coordinates, and the material parameters are combined to determine the pixel color for drawing the forming limit diagram, and finally the pixel color is rendered to the model outer surface, which can greatly improve the color positioning accuracy and the FLD boundary smoothness, and thus any color change caused by slight changes in principal and secondary strain values can be reflected in the final display result, which is beneficial to improving the perception accuracy of sheet metal rupture risk and facilitating practical application and promotion.

[0016] In one possible design, the sheet forming limit diagram drawing method is implemented using a graphics drawing system based on Hoops, OpenGL, DirectX or Vulkan.

[0017] In one possible design, when the sheet forming limit diagram drawing method is implemented using the Hoops-based graphics drawing system, for each mesh vertex, a corresponding principal strain value and a secondary strain value are set to the corresponding vertex as a map coordinate, including:

[0018] For each mesh vertex, a corresponding principal strain value and a secondary strain value are set to the corresponding vertex as a map coordinate using a HC_Set_Parameter setting function.

[0019] In one possible design, when the sheet forming limit diagram drawing method is implemented using the Hoops-based graphics drawing system, for each mesh patch on the outer surface of the model, a corresponding vertex shader and a pixel shader are set, including:

[0020] For each mesh patch on the outer surface of the model, a corresponding vertex shader and a pixel shader are set using a HC_Set_Shader setting function.

[0021] In one possible design, the material parameters include a plastic strain ratio value, a principal strain value when the secondary strain is zero, a strain hardening exponent value, a sheet thickness, a safe region value, and / or an allowable thickening interval value.

[0022] In one possible design, a pixel principal strain value and a pixel secondary strain value are extracted from the pixel map coordinate, and in combination with the material parameters of the target sheet metal three-dimensional model, a pixel color for drawing the forming limit diagram is determined, including the following steps S61-S68 executed in sequence:

[0023] S61. A pixel principal strain value y and a pixel secondary strain value x are extracted from the pixel map coordinate;

[0024] S62. It is judged whether the pixel principal strain value y is less than or equal to a first curve function GreenLine(r, x) in the Keeler formula, if yes, it is determined that the pixel color to be assigned is a first color for indicating a wrinkling risk region, wherein the first curve function GreenLine(r, x) is represented as follows:

[0025]

[0026] In the formula, r represents a plastic strain ratio value in the material parameters of the target sheet metal three-dimensional model;

[0027] S63. Determine whether the principal strain value y of the pixel is less than or equal to a second curve function BlueLine(x) in the Keeler formula, if yes, determine the pixel color to be assigned as a second color for indicating being in a wrinkling region, wherein the second curve function BlueLine(x) is represented as follows: BlueLine(x) = -x;

[0028] S64. Determine whether the principal strain value y of the pixel is less than or equal to a third curve function PinkLine(r,x) in the Keeler formula, if yes, determine the pixel color to be assigned as a third color for indicating being in a severe wrinkling region, wherein the third curve function PinkLine(r,x) is represented as follows:

[0029] S65. Determine whether the principal strain value y of the pixel is greater than or equal to a fourth curve function YellowLine(FLD0,x,safe region ) in the Keeler formula, if yes, determine the pixel color to be assigned as a fourth color for indicating being in a risk of rupture region, wherein the fourth curve function YellowLine(FLD0,x,safe region ) is represented as follows:

[0030]

[0031] wherein FLD0 represents a principal strain value in the material parameters and at zero secondary strain, safe region represents a safe region value in the material parameters;

[0032] S66. Determine whether the principal strain value y of the pixel is greater than or equal to a fifth curve function RedLine(FLD0,x) in the Keeler formula, if yes, determine the pixel color to be assigned as a fifth color for indicating being in a rupture region, wherein the fifth curve function RedLine(FLD0,x) is represented as follows:

[0033]

[0034] S67. Determine whether the principal strain value y of the pixel is less than or equal to a sixth curve function DiagonalGreyLine(allowable thickening ,x) in the Keeler formula and the secondary strain value x of the pixel is greater than or equal to a seventh curve function VerticalGreyLine(allowable thickening), if yes, determining the pixel color to be assigned as a sixth color for indicating an effective insufficient strain area, wherein the sixth curve function DiagonalGreyLine(allowable thickening , x) and the seventh curve function VerticalGreyLine(allowable thickening ) are respectively represented as follows:

[0035]

[0036] allowable thickening represents an allowable thickening interval value in material parameters;

[0037] S68. determining a pixel color for drawing a forming limit diagram as the pixel color to be assigned;

[0038] The steps S62-S67 allow to retain any one of them or any combination thereof.

[0039] In a second aspect, a device for drawing a forming limit diagram on a plate is provided, comprising a strain data acquisition module, a map coordinate setting module, a shader setting module, a map coordinate transmission module, a rasterization processing module, a pixel color determination module and a pixel color rendering module;

[0040] The strain data acquisition module is configured to acquire a principal strain value and a secondary strain value of each mesh vertex located on a model outer surface of a target plate model;

[0041] The map coordinate setting module is in communication with the strain data acquisition module and is configured to set, for each mesh vertex, a corresponding principal strain value and a secondary strain value together as a map coordinate to a corresponding vertex;

[0042] The shader setting module is configured to set, for each mesh patch located on the model outer surface, a corresponding vertex shader and a pixel shader;

[0043] The map coordinate transmission module is in communication with the map coordinate setting module and the shader setting module respectively and is configured to transmit, for the vertex shader, a map coordinate of a mesh vertex located on a corresponding mesh patch to a corresponding pixel shader;

[0044] The rasterization processing module is in communication with the map coordinate transmission module and is configured to rasterize the map coordinate transmitted to the pixel shader, so that the pixel shader obtains a pixel map coordinate calculated by an interpolation algorithm in a rasterization process;

[0045] The pixel color determination module is in communication connection with the rasterization processing module, configured to extract a pixel major strain value and a pixel minor strain value from the pixel map coordinates in the pixel shader, and determine a pixel color for drawing the forming limit diagram in combination with material parameters of the target sheet metal three-dimensional model;

[0046] The pixel color rendering module is in communication connection with the pixel color determination module, configured to render the pixel color onto the model outer surface to obtain a completed-drawing sheet forming limit diagram.

[0047] In a third aspect, the present application provides a computer device, comprising a memory, a processor and a transceiver which are in turn in communication connection, wherein the memory is configured to store a computer program, the transceiver is configured to transceive messages, and the processor is configured to read the computer program and execute the sheet forming limit diagram drawing method as described in the first aspect or any possible design in the first aspect.

[0048] In a fourth aspect, the present application provides a computer readable storage medium, wherein instructions are stored on the computer readable storage medium, and when the instructions are executed on a computer, the sheet forming limit diagram drawing method as described in the first aspect or any possible design in the first aspect is executed.

[0049] In a fifth aspect, the present application provides a computer program product, comprising a computer program or instructions, and when the computer program or the instructions are executed by a computer, the sheet forming limit diagram drawing method as described in the first aspect or any possible design in the first aspect is implemented.

[0050] The above-mentioned scheme has the following beneficial effects:

[0051] (1) The present application creatively provides a new scheme of drawing a sheet forming limit diagram by taking a pixel as a minimum coloring unit, that is, the major and minor strain values of each grid vertex located on the model outer surface of a target sheet metal three-dimensional model are set as map coordinates on the corresponding vertex, then the map coordinates of the grid vertices located on the corresponding grid patches are transmitted to the corresponding pixel shader for vertex shader, and the transmitted map coordinates are rasterized to obtain pixel map coordinates, then the pixel major and minor strain values are extracted from the pixel map coordinates in the pixel shader, and the pixel color for drawing the forming limit diagram is determined in combination with the material parameters, and finally the pixel color is rendered onto the model outer surface, so that the color positioning accuracy and the FLD demarcation line smoothness can be greatly improved, and thus any color change caused by slight major and minor strain value changes can be reflected on the final display result, which is beneficial to improving the perception accuracy of sheet metal rupture risk and facilitating actual application and promotion. BRIEF DESCRIPTION OF DRAWINGS

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0053] Figure 1 An example diagram of the forming limit diagram on the board obtained using existing drawing methods, provided for the purposes of the prior art.

[0054] Figure 2 This is a schematic flowchart of the method for drawing a forming limit diagram on a board provided in an embodiment of this application.

[0055] Figure 3 This is an example diagram of rasterizing a triangular facet provided in an embodiment of this application.

[0056] Figure 4 An example diagram showing the positional relationship of multiple forming limit curves in a planar coordinate system provided in the embodiments of this application.

[0057] Figure 5 An example diagram of the forming limit diagram on the board obtained using the solution of this application is provided for an embodiment of this application.

[0058] Figure 6 This is a schematic diagram of the structure of the plate forming limit diagram drawing device provided in the embodiments of this application.

[0059] Figure 7 A schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these embodiments without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0061] It should be understood that although the terms "first" and "second", etc., may be used herein to describe various objects, these objects should not be limited by these terms. These terms are only used to distinguish one object from another. For example, the first object may be referred to as the second object, and similarly, the second object may be referred to as the first object, without departing from the scope of the exemplary embodiments of the invention.

[0062] It should be understood that the term "and / or" that may appear in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, or A and B exist simultaneously. Another example is A, B and / or C, which can mean that any one of A, B, and C or any combination thereof exists. The term " / and" that may appear in this document describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone or A and B exist simultaneously. In addition, the character " / " that may appear in this document generally indicates that the related objects before and after it are in an "or" relationship.

[0063] Example

[0064] like Figures 2 to 5 As shown, the method for drawing the forming limit diagram on the board provided in the first aspect of this embodiment can be executed, but is not limited to, by a computer device with certain computing resources, such as a graphics processing server, cloud server, personal computer (PC, referring to a multi-purpose computer of size, price, and performance suitable for personal use; desktop computers, laptops, mini-laptops, tablets, and ultrabooks are all personal computers), smartphone, personal digital assistant (PDA), or wearable device, etc. Figure 2 As shown, the method for drawing the forming limit diagram on the plate may include, but is not limited to, the following steps S1 to S7.

[0065] S1. Obtain the principal strain and secondary strain values ​​of each mesh vertex on the outer surface of the target sheet 3D model.

[0066] In step S1, the principal strain values ​​and secondary strain values ​​of each mesh vertex form the data basis for drawing the forming limit diagram on the board, which can be conventionally obtained based on existing forming limit diagram drawing schemes on boards. For example, when implementing this embodiment using a graphics rendering system based on Hoops (i.e., HOOPS Visualize, a high-performance 3D graphics rendering engine based on preserved mode, designed for real-time visualization of complex 3D scenes), the following C++ code can be used, but is not limited to:

[0067] #include<HUtility.h>

[0068] #include <vector>

[0069] int point_count; / / vertex number

[0070] std::vector major_strain(point_count); / / vertex major strain value

[0071] std::vector minor_strain(point_count); / / vertex minor strain value

[0072] S2. For each mesh vertex, set the corresponding major strain value and minor strain value together as a map coordinate to the corresponding vertex.

[0073] In step S2, the map coordinate refers to the two-dimensional coordinate of each pixel on the map positioned on the surface of the three-dimensional model, usually represented by two coordinate axes such as U axis and V axis, similar to the X axis and Y axis of the two-dimensional plane. For example, when implementing the present embodiment using the Hoops-based graphics rendering system, for each mesh vertex, the HC_Set_Parameter setting function or other map coordinate setting function can be used to set the corresponding major strain value and minor strain value together as a map coordinate to the corresponding vertex, and the following C++ code can be used for setting and implementation, but is not limited thereto:

[0074]

[0075] S3. For each mesh patch on the outer surface of the model, set the corresponding vertex shader and pixel shader.

[0076] In step S3, the mesh patch can be, but is not limited to, a triangular patch or a quadrilateral patch, etc. Considering the image rendering pipeline (i.e. Rendering Pipeline, which is a processing flow in computer graphics for generating a two-dimensional image to represent a three-dimensional scene. It describes a series of continuous steps, starting from the original three-dimensional model data, through a series of calculations and processing, and finally converting into pixels that can be seen on the screen) in the present embodiment, each mesh vertex needs to be converted by the vertex shader to map the coordinate into the user visualization window, so that the rendering pipeline can rasterize (i.e. Rasterization, which is a process in computer graphics for converting vector geometry data such as triangular patches described by vertices into a screen pixel array) the converted mesh (such as dividing a line into one pixel by one pixel on the screen; taking triangular patch rasterization as an example, such as Figure 3 As shown), each pixel is then processed by a pixel shader (or fragment shader) to calculate its color. Therefore, it is necessary to first set the corresponding vertex shader and pixel shader for each mesh facet. For example, when implementing this embodiment using a Hoops-based graphics rendering system, for each mesh facet located on the outer surface of the model, the corresponding vertex shader and pixel shader can be set using the HC_Set_Shader setting function or other shader setting functions. Taking a triangle facet as an example, it can be set using, but is not limited to, the following C++ code:

[0077] #include<HUtility.h>

[0078] char const*const vertex_shader_string; / / Vertex shader code string

[0079] char const*const pixel_shader_string; / / pixel shader code string

[0080] HC_KEY vertex_shader_key = HC_Define_Shader("vertex_shader", "vertex", vertex_shader_string); / / Define vertex shader handle

[0081] HC_KEY pixel_shader_key = HC_Define_Shader("pixel_shader", "pixel", pixel_shader_string); / / Define pixel shader handle

[0082] HC_Set_Shader("triangles", vertex_shader_key, pixel_shader_key); / / Define the triangle face shader

[0083] S4. For the vertex shader, the texture coordinates of the mesh vertices located on the corresponding mesh facet are passed to the corresponding pixel shader.

[0084] In step S4, for example, when implementing this embodiment using a Hoops-based graphics rendering system, the vertex shader can be implemented using, but is not limited to, the following C++ code:

[0085]

[0086] S5. Rasterize the map coordinates passed to the pixel shader, so that the pixel shader gets pixel map coordinates calculated by interpolation algorithm during rasterization.

[0087] In the step S5, the map coordinates rasterization is also the rasterization of the major strain value and the minor strain value of the mesh vertex, so that the pixel shader gets the interpolated pixel major strain value and the pixel minor strain value (i.e. the pixel map coordinates). The specific rasterization process and the interpolation calculation process can be derived by referring to the conventional graphics rasterization technology, and will not be described here. In addition, when the Hoops-based graphics rendering system is used to implement the embodiment, the entire step S5 can be implemented internally in Hoops.

[0088] S6. In the pixel shader, the pixel major strain value and the pixel minor strain value are extracted from the pixel map coordinates, and the pixel color for drawing the forming limit diagram is determined in combination with the material parameters of the target sheet metal three-dimensional model.

[0089] In the step S6, the material parameters can be obtained by user input, specifically including but not limited to the plastic strain ratio, the major strain value when the minor strain is zero, the strain hardening exponent value, the sheet thickness, the safety region value and / or the allowable thickening interval value, etc. In the process of drawing the forming limit diagram, a plurality of forming limit curves (FLC) are involved for the purpose of differentiated coloring, as shown in the following figure. Figure 4 In order to maximize the reduction of the demand of the pixel shader on computing resources, preferably, the pixel major strain value and the pixel minor strain value are extracted from the pixel map coordinates, and the pixel color for drawing the forming limit diagram is determined in combination with the material parameters of the target sheet metal three-dimensional model, including the following steps S61-S68 executed in sequence.

[0090] S61. The pixel major strain value y and the pixel minor strain value x are extracted from the pixel map coordinates.

[0091] S62. It is judged whether the pixel major strain value y is less than or equal to the first curve function GreenLine(r, x) in the Keeler formula. If yes, it is determined that the pixel color to be assigned is the first color for indicating the wrinkling risk area, wherein the first curve function GreenLine(r, x) is represented as follows:

[0092]

[0093] In the formula, r represents the plastic strain ratio in the material parameters of the target sheet metal three-dimensional model.

[0094] In the step S62, the forming limit curve corresponding to the first curve function GreenLine(r, x) is FLC1 in Figure 4 . In addition, the first color is exemplified but not limited to light blue; and the pixel color to be assigned can be initialized as green so as to be safe by default.

[0095] S63. It is judged whether the pixel principal strain value y is less than or equal to the second curve function BlueLine(x) in the Keeler formula, if yes, it is determined that the pixel color to be assigned is a second color for indicating the wrinkle region, wherein the second curve function BlueLine(x) is represented as follows: BlueLine(x) = -x.

[0096] In the step S63, the forming limit curve corresponding to the second curve function BlueLine(x) is FLC2 in Figure 4 . In addition, the second color is exemplified but not limited to pink.

[0097] S64. It is judged whether the pixel principal strain value y is less than or equal to the third curve function PinkLine(r, x) in the Keeler formula, if yes, it is determined that the pixel color to be assigned is a third color for indicating the severe wrinkle region, wherein the third curve function PinkLine(r, x) is represented as follows:

[0098] In the step S64, the forming limit curve corresponding to the third curve function PinkLine(r, x) is FLC3 in Figure 4 . In addition, the third color is exemplified but not limited to purple.

[0099] S65. It is judged whether the pixel principal strain value y is greater than or equal to the fourth curve function YellowLine(FLD0, x, safe region ) in the Keeler formula, if yes, it is determined that the pixel color to be assigned is a fourth color for indicating the risk of rupture region, wherein the fourth curve function YellowLine(FLD0, x, safe region ) is represented as follows:

[0100]

[0101] In the formula, FLD0 represents the principal strain value in the material parameter and when the secondary strain is zero, safe region represents the safe region value in the material parameter.

[0102] In step S65, the fourth curve function YellowLine(FLD0,x,safe) is used. region The corresponding forming limit curve is Figure 4 FLC4 in the text. If the material parameters do not include FLD0 but include the strain hardening index value and the plate thickness, then FLD0 can be calculated using the following formula:

[0103]

[0104] In the formula, n represents the strain hardening index value, and t represents the plate thickness. Furthermore, the fourth color is, for example but not limited to, yellow, and the safe zone value is... region It can be a user-defined constant, or it can be derived from... Figure 4 The percentage result of the distance from the FLC5 line to the X-axis.

[0105] S66. Determine whether the principal strain value y of the pixel is greater than or equal to the fifth curve function RedLine(FLD0,x) in the Keeler formula. If so, determine that the color of the pixel to be assigned is the fifth color used to indicate the fracture region, wherein the fifth curve function RedLine(FLD0,x) is represented as follows:

[0106]

[0107] In step S66, the forming limit curve corresponding to the fifth curve function RedLine(FLD0,x) is... Figure 4 FLC5 in the example. Furthermore, the fifth color is, for example but not limited to, red.

[0108] S67. Determine whether the principal strain value y of the pixel is less than or equal to the sixth curve function DiagonalGreyLine(allowable) in the Keeler formula. thickening And whether the pixel sub-strain value x is greater than or equal to the seventh curve function VerticalGreyLine(allowable) in the Keeler formula. thickening If so, then the pixel color to be assigned is determined to be the sixth color used to indicate the region of insufficient effective strain, wherein the sixth curve function is DiagonalGreyLine(allowable thickening The seventh curve function VerticalGreyLine(allowable) and x) thickening The following are respectively represented:

[0109]

[0110] allowable thickening represents the allowable thickening interval value in the material parameter.

[0111] In the step S67, the forming limit curve corresponding to the sixth curve function DiagonalGreyLine(allowable thickening ,x) is FLC6 in the following formula: Figure 4 In the step S67, the forming limit curve corresponding to the seventh curve function VerticalGreyLine(allowable thickening ) is FLC7 in the following formula: Figure 5 In addition, the sixth color is exemplified but not limited to grey, and the allowable thickening interval value allowabl thickening e can also be a user-defined constant.

[0112] S68. Determining the pixel color for drawing the forming limit diagram as the pixel color to be assigned.

[0113] Before the step S68, other curve functions (for example, the orange curve FLC8 in the following formula: Figure 1 ) can also be defined for more refined coloring. The above steps S62-S67 are independent of each other, and thus any one or any combination of them can be allowed to be retained, i.e., only step S62, step S63, step S64, step S65, step S66 or step S67, etc. (for example, extracting the pixel principal strain value and the pixel secondary strain value from the pixel texture coordinates, and determining the pixel color for drawing the forming limit diagram in combination with the material parameters of the target sheet metal three-dimensional model, including sequentially performing steps S61, S64 and S68, etc.) can be used, and any combination of steps S62, S63, S64, S65, S66 and S67, etc. (for example, extracting the pixel principal strain value and the pixel secondary strain value from the pixel texture coordinates, and determining the pixel color for drawing the forming limit diagram in combination with the material parameters of the target sheet metal three-dimensional model, including sequentially performing steps S61, S63, S64, S67 and S68, etc.) can also be used.

[0114] In the step S6, when the present embodiment is implemented using the Hoops-based graphic drawing system, the above steps S61-S68 can be but not limited to calculated and implemented using the following C++ code:

[0115]

[0116] S7. Rendering the pixel color to the model outer surface to obtain the completed drawn sheet forming limit diagram. In the step S7, the color rendering can be completed by using the existing rendering technology to obtain, for example, Figure 6 The sheet forming limit diagram shown is compared with Figure 7 The embodiment has obvious improvements in color positioning accuracy and FLD boundary line smoothness, so that any color change caused by slight primary and secondary strain value changes can be reflected in the final display result, which helps to improve the perception accuracy of sheet material rupture risk. In addition, the embodiment can be implemented using a graphics rendering system based on OpenGL, DirectX or Vulkan, and the specific steps of the embodiment can be programmed using programming languages such as C, Java, Python, Matlab or Javascript.

[0117] The sheet forming limit diagram drawing method described based on the foregoing steps S1-S7 provides a new scheme for drawing a sheet forming limit diagram with pixels as the minimum coloring unit, i.e., the primary and secondary strain values of each grid vertex on the model outer surface of the target sheet metal three-dimensional model are set as a texture coordinate on the corresponding vertex, then for the vertex shader, the texture coordinates of the grid vertices on the corresponding grid patch are transmitted to the corresponding pixel shader, and the transmitted texture coordinates are rasterized to obtain pixel texture coordinates, then in the pixel shader, the pixel primary and secondary strain values are extracted from the pixel texture coordinates, and the pixel color for drawing the forming limit diagram is determined in combination with the material parameters, and finally the pixel color is rendered on the model outer surface, which can greatly improve the color positioning accuracy and FLD boundary line smoothness, so that any color change caused by slight primary and secondary strain value changes can be reflected in the final display result, which helps to improve the perception accuracy of sheet material rupture risk and facilitates actual application and promotion.

[0118] As ​ The second aspect of the embodiment provides a virtual device for implementing the sheet forming limit diagram drawing method of the first aspect, which includes a strain data acquisition module, a texture coordinate setting module, a shader setting module, a texture coordinate transmission module, a rasterization processing module, a pixel color determination module, and a pixel color rendering module.

[0119] The strain data acquisition module is configured to acquire the primary and secondary strain values of each grid vertex on the model outer surface of the target sheet metal three-dimensional model.

[0120] The texture coordinate setting module is in communication with the strain data acquisition module and is configured to set the corresponding primary and secondary strain values as texture coordinates on the corresponding vertex for each grid vertex.

[0121] The shader setting module is configured to set the corresponding vertex shader and pixel shader for each grid patch on the model outer surface.

[0122] The map coordinate transmission module is respectively connected in communication with the map coordinate setting module and the shader setting module, and is configured to transmit map coordinates of mesh vertices located on corresponding mesh patches to the corresponding pixel shader for the vertex shader;

[0123] The rasterization processing module is connected in communication with the map coordinate transmission module, and is configured to rasterize the map coordinates transmitted to the pixel shader, so that the pixel shader obtains pixel map coordinates calculated by an interpolation algorithm in a rasterization process;

[0124] The pixel color determination module is connected in communication with the rasterization processing module, and is configured to extract a pixel primary strain value and a pixel secondary strain value from the pixel map coordinates in the pixel shader, and determine a pixel color used for drawing a forming limit diagram in combination with material parameters of the target sheet model;

[0125] The pixel color rendering module is connected in communication with the pixel color determination module, and is configured to render the pixel color onto an outer surface of the model to obtain a completed sheet forming limit diagram.

[0126] The working process, working details and technical effects of the foregoing device provided by the second aspect of the embodiment can be referred to the sheet forming limit diagram drawing method described in the first aspect, and will not be described here again.

[0127] As shown in ​ The third aspect of the embodiment provides a computer device for executing the sheet forming limit diagram drawing method described in the first aspect, which comprises a memory, a processor and a transceiver connected in sequence in communication, wherein the memory is configured to store a computer program, the transceiver is configured to receive and send messages, and the processor is configured to read the computer program and execute the sheet forming limit diagram drawing method described in the first aspect. Specifically, the memory can include, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a flash memory, a first input first output (FIFO) memory and / or a first input last output (FILO) memory, etc.; the processor can be, but is not limited to, a microprocessor with a model number of STM32F105 series. In addition, the computer device can further include, but is not limited to, a power module, a display screen and other necessary components.

[0128] The working process, working details and technical effects of the aforementioned computer device provided by the third aspect of the embodiment can be referred to the plate forming limit diagram drawing method described in the first aspect, and will not be repeated here.

[0129] The fourth aspect of the embodiment provides a computer readable storage medium storing instructions of the plate forming limit diagram drawing method described in the first aspect, that is, the computer readable storage medium stores instructions, and when the instructions are run on a computer, the plate forming limit diagram drawing method described in the first aspect is executed. Wherein, the computer readable storage medium refers to a carrier for storing data, which can include, but is not limited to, floppy disks, optical disks, hard disks, flash memories, USB flash disks and / or Memory Stick and other computer readable storage media, and the computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices.

[0130] The working process, working details and technical effects of the aforementioned computer readable storage medium provided by the fourth aspect of the embodiment can be referred to the plate forming limit diagram drawing method described in the first aspect, and will not be repeated here.

[0131] The fifth aspect of the embodiment provides a computer program product, including a computer program or instructions, which, when executed by a computer, implements the plate forming limit diagram drawing method described in the first aspect. Wherein, the computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices.

[0132] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.< / vector>

Claims

1. A method for drawing a forming limit diagram on a plate, characterized in that, The method for drawing the forming limit diagram on the board is implemented using a graphics rendering system based on Hoops, OpenGL, DirectX, or Vulkan, and includes: Obtain the principal strain and secondary strain values ​​of each mesh vertex located on the outer surface of the target sheet's 3D model; For each mesh vertex, the corresponding principal strain value and secondary strain value are set together as texture coordinates on the corresponding vertex. When the forming limit diagram drawing method on the board is implemented using a Hoops-based graphics drawing system, the specific method includes: for each mesh vertex, using the HC_Set_Parameter setting function to set the corresponding principal strain value and secondary strain value together as texture coordinates on the corresponding vertex. For each mesh patch located on the outer surface of the model, set the corresponding vertex shader and pixel shader; For the vertex shader, the texture coordinates of the mesh vertices located on the corresponding mesh facet are passed to the corresponding pixel shader; The texture coordinates passed to the pixel shader are rasterized, so that the pixel shader obtains the pixel texture coordinates calculated by the interpolation algorithm during the rasterization process; In the pixel shader, the principal strain value and secondary strain value of the pixel are extracted from the pixel map coordinates, and combined with the material parameters of the target sheet 3D model, the pixel color used to draw the forming limit diagram is determined. The pixel color is rendered onto the outer surface of the model to obtain the completed forming limit diagram on the board.

2. The method for drawing the forming limit diagram on a plate according to claim 1, characterized in that, When using a Hoops-based graphics rendering system to implement the method for drawing the forming limit diagram on the board, for each mesh patch located on the outer surface of the model, corresponding vertex shaders and pixel shaders are set, including: For each mesh facet located on the outer surface of the model, the HC_Set_Shader setting function is used to set the corresponding vertex shader and pixel shader.

3. The method for drawing forming limit diagrams on a plate according to claim 1, characterized in that, The material parameters include the plastic strain ratio, the principal strain value when the secondary strain is zero, the strain hardening index, the plate thickness, the safe zone value, and / or the allowable thickening range value.

4. The method for drawing the forming limit diagram on a plate according to claim 1, characterized in that, The pixel principal strain value and pixel secondary strain value are extracted from the pixel texture coordinates, and combined with the material parameters of the target sheet 3D model, the pixel color used to draw the forming limit diagram is determined, including the following steps S61 to S68 executed sequentially: S61. Extract the principal strain value of the pixel from the pixel map coordinates. and pixel strain value ; S62. Determine the principal strain value of the pixel. Is it less than or equal to the first curve function in the Keeler formula? If so, then the pixel color to be assigned is determined to be a first color used to indicate areas at risk of wrinkling, wherein the first curve function It is expressed as follows: In the formula, This represents the plastic strain ratio in the material parameters of the three-dimensional model of the target sheet. S63. Determine the principal strain value of the pixel. Is it less than or equal to the second curve function in the Keeler formula? If so, then the color of the pixel to be assigned is determined to be a second color used to indicate the wrinkled area, wherein the second curve function It is expressed as follows: ; S64. Determine the principal strain value of the pixel. Is it less than or equal to the third curve function in the Keeler formula? If so, then the color of the pixel to be assigned is determined to be a third color used to indicate a severely wrinkled region, wherein the third curve function It is expressed as follows: ; S65. Determine the principal strain value of the pixel. Is it greater than or equal to the fourth curve function in the Keeler formula? If so, then the color of the pixel to be assigned is determined to be a fourth color used to indicate a region at risk of breakage, wherein the fourth curve function It is expressed as follows: In the formula, This represents the principal strain value in the material parameters where the secondary strain is zero. This represents the safe zone value in the material parameters; S66. Determine the principal strain value of the pixel. Is it greater than or equal to the fifth curve function in the Keeler formula? If so, then the color of the pixel to be assigned is determined to be the fifth color used to indicate the broken region, wherein the fifth curve function It is expressed as follows: ； S67. Determine the principal strain value of the pixel. Is it less than or equal to the sixth curve function in the Keeler formula? And the pixel secondary strain value Is it greater than or equal to the seventh curve function in the Keeler formula? If so, then the pixel color to be assigned is determined to be the sixth color used to indicate areas of insufficient effective strain, wherein the sixth curve function and the seventh curve function They are represented as follows: In the formula, This indicates the allowable thickness range in the material parameters; S68. The pixel color used to draw the forming limit diagram is determined as the pixel color to be assigned; The above steps S62 to S67 can be retained in any one of them or any combination thereof.

5. A device for drawing limit diagrams of forming plates, characterized in that, The plate forming limit diagram drawing device is implemented using a graphics drawing system based on Hoops, OpenGL, DirectX or Vulkan, and includes a strain data acquisition module, a texture coordinate setting module, a shader setting module, a texture coordinate transfer module, a rasterization processing module, a pixel color determination module and a pixel color rendering module. The strain data acquisition module is used to acquire the principal strain values ​​and secondary strain values ​​of each mesh vertex located on the outer surface of the three-dimensional model of the target sheet. The texture coordinate setting module is communicatively connected to the strain data acquisition module. It is used to set the corresponding principal strain value and secondary strain value together as texture coordinates to the corresponding vertex for each mesh vertex. When the forming limit diagram drawing device on the board is implemented using a Hoops-based graphics drawing system, it specifically includes: using the HC_Set_Parameter setting function to set the corresponding principal strain value and secondary strain value together as texture coordinates to the corresponding vertex for each mesh vertex. The shader setting module is used to set corresponding vertex shaders and pixel shaders for each mesh facet located on the outer surface of the model. The texture coordinate transfer module is communicatively connected to the texture coordinate setting module and the shader setting module, and is used to transfer the texture coordinates of the mesh vertices located on the corresponding mesh facets to the corresponding pixel shader for the vertex shader. The rasterization processing module is communicatively connected to the texture coordinate transmission module and is used to rasterize the texture coordinates transmitted to the pixel shader, so that the pixel shader obtains the pixel texture coordinates calculated by the interpolation algorithm during the rasterization process. The pixel color determination module is communicatively connected to the rasterization processing module. It is used to extract the pixel principal strain value and pixel secondary strain value from the pixel texture coordinates in the pixel shader, and combine them with the material parameters of the target sheet 3D model to determine the pixel color used to draw the forming limit diagram. The pixel color rendering module is communicatively connected to the pixel color determination module and is used to render the pixel color onto the outer surface of the model to obtain the completed drawing of the plate forming limit diagram.

6. A computer device, characterized in that, The device includes a memory, a processor, and a transceiver that are sequentially and communicatively connected. The memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the plate forming limit diagram drawing method as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that... The computer-readable storage medium stores instructions that, when executed on a computer, perform the plate forming limit diagram drawing method as described in any one of claims 1 to 4.

8. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or the instructions are executed by the computer, they implement the plate forming limit diagram drawing method as described in any one of claims 1 to 4.

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