Method for determining grid size for composite curing deformation simulation and application

Abstract

The application discloses a composite material curing deformation simulation grid size determination method and application, through minimum envelope size related grid division objects, adopting a "curved surface-plane" double-reference grid division strategy based on curvature characteristics and envelope size, a dynamic evaluation method of grid size and simulation result convergence is established, the problem that a real composite part surface structure feature and grid division need to be processed for a long time in the early stage is avoided, simple structure is extracted to replace the structure feature of the real part, only the global grid size needs to be changed in the simulation iteration updating process, a large amount of time can be saved, the simulation result precision can be well ensured, and effective balance between simulation precision and efficiency is realized.

Description

Technical Field

[0001] This invention belongs to the field of computer simulation technology, specifically relating to a method for determining the mesh size in a composite material curing deformation simulation and its application. Background Technology

[0002] Currently, determining mesh size in composite material curing deformation simulation mainly relies on engineer experience or a globally uniform meshing method. Mesh sizes based on engineer experience can lead to discrepancies in simulation results among different engineers; while globally uniform meshing methods suffer from insufficient simulation accuracy in regions with large curvature variations due to overly sparse meshes, and wasteful computational resources in flat regions due to overly dense meshes. Furthermore, processing the structural features of the actual part surface and performing mesh generation requires significant manual operation and processing time, especially in the simulation of complex curved surface parts in the aerospace field. Existing technologies lack scientific quantitative standards to determine the optimal mesh size, making it difficult to balance the reliability of simulation results with computational efficiency. Traditional methods typically require multiple trial calculations and adjustments, or complex evaluation processes and preparation time for final determination. Existing meshing methods for two-dimensional triangular meshes suffer from poor applicability, and the mesh types are not suitable for composite material curing deformation simulation. Summary of the Invention

[0003] The purpose of this invention is to provide a method and application for determining the mesh size in the simulation of composite curing deformation, so as to solve the problem that the determination of mesh size in the simulation of composite part curing deformation depends on subjective experience, resulting in insufficient simulation accuracy or large amount of calculation, and difficulty in balancing the credibility of the simulation structure and the calculation efficiency.

[0004] This invention is achieved through the following technical solution: The method for determining the mesh size in composite material curing deformation simulation includes the following steps: Extract the film surface of the composite part to be simulated, calculate the minimum volume envelope size of the film surface of the composite part, obtain the curvature curve at the position of maximum curvature of the film surface, and stretch it along the normal of the cross-sectional curve to generate a surface A with a uniform cross-section. Plane B is generated with the length and width of the minimum volume envelope size of the film surface as the boundary; Based on surface A and plane B, generate solids AA and BB along the thickness direction, respectively. In the simulation software, the solids AA and BB are meshed according to the default global mesh size. Following the composite curing deformation simulation process, a curing deformation simulation model is established, and the corresponding curing deformation is calculated to obtain the maximum deformation. By gradually adjusting the mesh size and repeatedly performing deformation simulation calculations, the maximum deformation of solids AA and BB can be obtained. Plot a curve with 1 / mesh size as the x-axis and maximum deformation as the y-axis. When the rate of change of the maximum deformation between two consecutive intervals meets the set conditions, terminate the iterative analysis and record the current corresponding mesh size. Compare the mesh sizes and take the smaller value as the simulation mesh size for the curing deformation of the composite part under test.

[0005] In some embodiments, before performing solidification deformation simulation analysis on solid AA and solid BB, information on the simulated composite parts to be tested is obtained, including material grade, layup sequence and coordinate system, part thickness, process curve, etc.

[0006] In some embodiments, the step of obtaining the curvature curve at the location of maximum curvature on the film surface includes: analyzing the curvature of the film surface using a curvature analysis tool, finding the location of maximum curvature on the film surface, and forming a curvature curve.

[0007] In some embodiments, the step of obtaining the curvature curve at the position of maximum curvature of the film surface includes: taking the width and height plane of the minimum envelope volume as a reference, making a number of parallel planes in the length direction of the film surface, then constructing the intersection lines between the parallel planes and the film surface respectively, calculating the ratio of the curve length to the length of the straight line connecting the beginning and end on each intersection line, and taking the curve with the largest ratio as the curvature curve.

[0008] In some embodiments, when performing solidification deformation simulation iterative analysis on entities AA and BB, only the network size is changed, while other settings remain unchanged.

[0009] In some embodiments, during iterative analysis, the mesh size is adjusted gradually upwards or downwards based on the iterative simulation results.

[0010] On the other hand, the present invention also provides an application of a method for determining the grid size of composite material curing deformation simulation in the curing deformation simulation of fully laminated parts and missing-layer parts.

[0011] Compared with the prior art, the present invention has the following advantages and beneficial effects: The method of this invention associates meshing objects with minimum envelope size and adopts a dual-reference meshing strategy of "surface-plane" based on curvature features and envelope size. It establishes a dynamic evaluation method for the convergence of mesh size and simulation results, avoiding the problem of having to spend a long time processing the surface structural features and meshing of real composite parts in the early stage. It extracts a simplified structure to replace the structural features of real parts. During the simulation iteration update process, only the global mesh size needs to be changed, which can save a lot of time and can well ensure the accuracy of simulation results, achieving an effective balance between simulation accuracy and efficiency. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This refers to the minimum envelope volume of the film-coated surface of the simulated composite part in this embodiment of the invention.

[0014] Figure 2 This is a schematic diagram illustrating the determination of the curvature curve on the film surface using a curvature analysis tool in an embodiment of the present invention.

[0015] Figure 3 This is a schematic diagram illustrating the method of determining the curvature curve by comparing ratios in an embodiment of the present invention.

[0016] Figure 4 This is a schematic diagram of surface A obtained from the curvature curve in an embodiment of the present invention.

[0017] Figure 5 This is a schematic diagram of plane B obtained from the minimum envelope volume in an embodiment of the present invention.

[0018] Figure 6 This is a graph plotted in an embodiment of the present invention with 1 / grid size as the horizontal axis and maximum deformation as the vertical axis. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining this application and not for limiting it. It should also be noted that, for ease of description, only the parts relevant to this application are shown in the drawings, not all of them. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0020] This invention addresses the structural characteristics of composite materials by systematically considering the differences between curvature and flat regions. By establishing quantitative standards to determine the mesh size, it effectively balances computational accuracy and efficiency, making it well-suited for the curing deformation simulation analysis of fully laminated parts and delaminated parts.

[0021] In some embodiments of the present invention, the method for determining the grid size includes the following steps: Determine the basic information of the composite part to be simulated, including material grade, layup and thickness, and prepare the subroutines required for simulation analysis.

[0022] Extract the film surface of the composite part to be simulated, calculate the minimum volume envelope size (length L × width W × height H) of the film surface of the composite part, obtain the cross-sectional curve at the position of maximum curvature of the film surface, and stretch along the normal of the cross-sectional curve to generate a surface A with uniform cross-section.

[0023] Plane B is generated with the length L and width W of the minimum volume envelope size of the film surface as the boundary.

[0024] Based on surface A and plane B, generate solids AA and BB along the thickness direction, respectively.

[0025] Entities AA and BB are meshed in the simulation software according to the default global mesh size. Following the composite material curing deformation simulation process, a curing deformation simulation model is established, and the corresponding curing deformation is calculated to obtain the maximum deformation amounts U1-A and U1-B.

[0026] By gradually reducing the mesh size and repeating the deformation simulation calculations, the maximum deformation amounts (U2-A, U2-B), (U3-A, U3-B)...(U...) of solids AA and BB are obtained. n -A, U n -B).

[0027] Plot a curve with 1 / grid size as the x-axis and maximum deformation as the y-axis. When the rate of change of the maximum deformation between two consecutive times (|U) n -U n-1 | / U n-1 When the percentage of positive meshes is ≤5%, terminate the iterative analysis and record the current corresponding mesh size d. n-1 -A、d n-1 -B.

[0028] Compare d n-1 -A、d n-1 -B, take the smaller of the two values ​​as the determined grid size.

[0029] The process of determining the grid size using the method of the present invention will be described in detail below with reference to specific embodiments.

[0030] S1. By consulting the theoretical digital model of the composite part to be simulated, confirm the structural characteristics, material grade, layup sequence and coordinate system, part thickness, etc. of the composite part, and prepare the subroutines required for deformation simulation.

[0031] S2. Extract the coating surface of the composite part to be simulated, and calculate the minimum envelope volume size (length L × width W × height H) of the coating surface through geometric analysis, such as... Figure 1 As shown.

[0032] S3. Using curvature analysis tools, analyze the curvature of the molding surface, identify the location of maximum curvature on the molding surface, and generate a curvature curve, such as... Figure 2 As shown.

[0033] Alternatively, using the WH plane of the minimum envelope volume as a reference, construct several parallel planes along the length of the molding surface, then construct the intersection lines between the parallel planes and the molding surface, calculate the ratio of the curve length to the length of the straight line connecting the beginning and end on each intersection line, and compare the curve with the largest ratio as the curvature curve, such as... Figure 3 As shown.

[0034] S4. Stretch the curvature curve along the normal direction to generate a uniform cross-section surface A of length L, such as... Figure 4 As shown; A plane B is generated with the length L and width W of the minimum envelope volume as its boundaries, such as... Figure 5 As shown.

[0035] S5. Based on surface A and plane B, generate solid AA and solid BB along the thickness direction respectively.

[0036] For parts with missing layers, a missing layer entity can be generated according to the actual missing layer structure, or an equivalent entity with the same thickness can be generated according to the ratio of the part volume to the film surface area.

[0037] S6. Import solids AA and BB into the simulation software respectively. Based on the actual layup information of the parts and the composite curing deformation simulation process, establish a simulation model and use the default initial global mesh size to divide the model mesh.

[0038] S7. Perform solidification deformation simulation analysis on models AA and BB respectively, and record the mesh size used and the maximum deformation U1-A and U1-B obtained from the simulation.

[0039] S8. Gradually adjust the mesh size, keeping all other settings unchanged, repeat the solidification deformation simulation, and record the mesh size used and the maximum deformation obtained from the simulation (U2-A, U2-B), (U3-A, U3-B)...(U n -A, U n -B).

[0040] The mesh size can be adjusted upwards or downwards based on the actual situation and the results of iterative simulation, or it can be adjusted by referring to the trend of the curve drawn in step S9.

[0041] S9. Plot a curve with 1 / grid size as the x-axis and the maximum deformation as the y-axis, such as... Figure 6 As shown; When the rate of change of two consecutive maximum deformations (|U) n -U n-1 | / U n-1 When the percentage of positive values ​​is ≤5%, terminate the iteration and record the corresponding mesh size d. n-1 -A、d n-1 -B, see Table 1.

[0042] Table 1

[0043] S10. Compare the mesh sizes used by model AA and model BB when they terminate the iteration, and take the smaller value of the two as the final mesh size D. This size D can be used as the mesh size for the simulation analysis of the solidification deformation of the composite part under test.

[0044] The mesh size determined by this method can well balance the accuracy and efficiency of the simulation of curing deformation of composite parts.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for determining the mesh size in a composite material curing deformation simulation, characterized in that, Includes the following steps: Extract the film surface of the composite part to be simulated, calculate the minimum volume envelope size of the film surface of the composite part, obtain the curvature curve at the position of maximum curvature of the film surface, and stretch it along the normal of the cross-sectional curve to generate a surface A with a uniform cross-section. Plane B is generated with the length and width of the minimum volume envelope size of the film surface as the boundary; Based on surface A and plane B, generate solids AA and BB along the thickness direction, respectively. In the simulation software, the solids AA and BB are meshed according to the default global mesh size. Following the composite curing deformation simulation process, a curing deformation simulation model is established, and the corresponding curing deformation is calculated to obtain the maximum deformation. By gradually adjusting the mesh size and repeatedly performing deformation simulation calculations, the maximum deformation of solids AA and BB can be obtained. Plot a curve with 1 / mesh size as the x-axis and maximum deformation as the y-axis. When the rate of change of the maximum deformation between two consecutive intervals meets the set conditions, terminate the iterative analysis and record the current corresponding mesh size. Compare the mesh sizes and take the smaller value as the simulation mesh size for the curing deformation of the composite part under test.

2. The method for determining the mesh size for composite material curing deformation simulation according to claim 1, characterized in that, Before performing solidification deformation simulation analysis on solid AA and solid BB, information on the composite parts to be simulated is obtained, including material grade, layup sequence and coordinate system, part thickness, and process curve.

3. The method for determining the mesh size for composite material curing deformation simulation according to claim 1, characterized in that, The steps to obtain the curvature curve at the location of maximum curvature on the film surface include: analyzing the curvature of the film surface using a curvature analysis tool, finding the location of maximum curvature on the film surface, and forming a curvature curve.

4. The method for determining the mesh size for composite material curing deformation simulation according to claim 1, characterized in that, The steps to obtain the curvature curve at the position of maximum curvature of the film surface include: taking the width and height plane of the minimum envelope volume as the reference, making several parallel planes along the length direction of the film surface, then constructing the intersection lines between the parallel planes and the film surface, calculating the ratio of the curve length to the length of the straight line connecting the beginning and end on each intersection line, and taking the curve with the largest ratio as the curvature curve.

5. The method for determining the mesh size for composite material curing deformation simulation according to claim 1, characterized in that, When performing iterative simulation analysis on solidification deformation of entities AA and BB, only the network size is changed, while other settings remain unchanged.

6. The method for determining the mesh size for composite material curing deformation simulation according to claim 1, characterized in that, During iterative analysis, the mesh size is adjusted upwards or downwards gradually based on the iterative simulation results.

7. The method for determining the grid size for composite curing deformation simulation according to any one of claims 1-6 is applied to the curing deformation simulation of fully laminated parts and parts with missing layers.

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