A geometric modeling method for 2.5-dimensional braided composite yarn

Abstract

The invention discloses a geometric modeling method for 2.5-dimensional braided composite material yarn, comprising the following steps: 1) establishing a weft projection diagram of a 2.5-dimensional braided composite material with extruded weft yarn; 2) establishing a three-dimensional framework diagram of a 2.5-dimensional braided composite material with extruded weft yarn according to the weft projection diagram; 3) establishing a standard model of the 2.5-dimensional braided composite material according to the three-dimensional framework diagram; 4) extracting the original geometric blocks of the target position of the standard model, separately establishing a weft yarn geometric block considering extrusion, and performing replacement assembly to obtain a new model as a whole; 5) structurally coupling the new model as a whole to form a complete whole with closely connected units. It is helpful to further standardize the finite element analysis process, improve the precision and accuracy of the finite element analysis, and the factors have a wide range of influence restrictions, and have greater universality.

Description

Technical Field

[0001] The invention relates to the field of composite material geometric modeling, and in particular to a geometric modeling method for 2.5-dimensional braided composite material yarn. Background Art

[0002] Since the 1960s, composite materials have been developing rapidly and are widely used in aerospace, shipping, and medical fields. For the study of composite material properties, many scholars use finite element analysis methods, that is, to obtain the various properties of composite materials through the analysis process of model building, meshing, parameter setting, software solving, and experimental verification. In this process, structural analysis before establishing a geometric model is of utmost importance. Whether it is parametric modeling or visual solid modeling using modeling software, we must strive to take into account the various characteristics of the internal structure of the geometric model to avoid missing important influencing factors, otherwise, the accuracy of the calculation results will be greatly affected. Regarding the structural analysis of geometric models, a large number of literatures show that researchers have made various conjectures. The gradual development of non-destructive testing technology has made it easy to obtain the internal structure of composite materials, which further optimizes the assumptions of geometric models. However, for textile composite materials, researchers have made the following assumptions about the cross-section of composite yarns: runway shape, biconvex lens shape, rectangle, hexagon, octagon, etc. The yarn orientation, especially the weft orientation, is simply regarded as a single function type. The relevant research is very insufficient, which will undoubtedly affect the accuracy of solving the mechanical properties of yarns. At the same time, according to the detection of the interior of textile composites by non-destructive testing technology, the surface yarn is most affected by the processing technology. Processes such as mold extrusion, tool cutting and machine shaping have seriously changed the geometric characteristics of the surface yarn. This shows that the structural laws of textile composites cannot be characterized by a single hypothesis or a single function. Summary of the invention

[0003] The purpose of the present invention is to provide a geometric modeling method for 2.5-dimensional braided composite yarn, which helps to further standardize the finite element analysis process, improve the precision and accuracy of finite element analysis, and has a limited range of factors affecting the modeling, and has greater universality.

[0004] To achieve the above object, according to one aspect of the present invention, the present invention provides the following technical solution:

[0005] A geometric modeling method for 2.5-dimensional braided composite yarn comprises the following steps:

[0006] 1) Establish the weft projection diagram of the 2.5D woven composite material with squeezed weft yarns;

[0007] 2) According to the weft projection diagram, a three-dimensional frame diagram of the 2.5-dimensional woven composite material with squeezed weft yarns is established;

[0008] 3) Establish a standard model of 2.5D braided composite materials based on the three-dimensional frame diagram;

[0009] 4) Extract the original geometric block of the target position of the standard model, establish a weft geometric block considering extrusion, and perform replacement assembly to obtain the new model as a whole;

[0010] 5) Structural coupling is performed on the new model as a whole to make it a complete whole with closely connected units.

[0011] The present invention is further configured that the step 1) establishes a weft projection diagram of the 2.5-dimensional woven composite material with compressed weft yarns, specifically,

[0012] 1-1) Scan the 2.5-dimensional woven composite material test piece using non-destructive testing technology, obtain the scanned image and the internal structural characteristics of the test piece, and use software to measure the size of each component on the scanned image;

[0013] 1-2) Establish a weft projection diagram of the composite material considering weft yarn extrusion according to the size of each component.

[0014] The present invention is further configured as follows: the step 2) establishes a three-dimensional framework diagram of a 2.5-dimensional woven composite material with squeezed weft yarns, specifically, saves the weft projection diagram as a file in dwg format, and converts its version into AutoCAD2007 version, opens the converted projection diagram by UG NX 10.0, selects four boundaries of the projection diagram in UG NX10.0 software, sets the stretching length to the weft length of the unit cell model, forms a three-dimensional framework diagram, and exports the three-dimensional framework diagram as a file in igs format.

[0015] The present invention is further configured as follows: the step 3) establishes a standard model of a 2.5-dimensional woven composite material according to the three-dimensional framework diagram, specifically, imports the three-dimensional framework diagram in the igs format into the Hypermesh software, performs mesh division, and modifies the mesh to remove the deformed mesh to obtain new surface mesh units, performs volume mesh division on the new surface mesh units to obtain volume units, and divides the volume units into components, thereby obtaining a standard model.

[0016] The present invention is further configured as follows: the step 4) extracts the original geometric block of the target position of the standard model, separately establishes the weft yarn geometric block considering the influence of the factors, and replaces and assembles it to obtain the new model as a whole. Specifically, the original geometric block of the weft yarn target position is extracted on the standard model, and the original geometric block is modified according to the relationship between the two cross sections of the surface weft yarn and the weft yarn squeezed into the matrix in the weft yarn connection section in the overall model, so as to separately establish the weft yarn geometric block considering extrusion at the corresponding position, and replace the weft yarn geometric block considering extrusion with the original geometric block position.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This method helps to further standardize the finite element analysis process and improve the precision and accuracy of finite element analysis.

[0019] 2. For the local features of other yarns, and even the local features of composite materials woven in other ways, the actual modeling of the direction of composite yarns can be achieved through the process of "establishing a non-influence model - establishing a local feature block - replacing the original block at the target position - structural coupling". Therefore, the influence restriction range of the factors of the present invention is wide and has great universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 These are the weft CT images of three lining warp twill 2.5D woven composite materials, where a is the weft image of the warp and weft yarns, and b is the weft image of the lining warp and weft yarns;

[0021] Figure 2 It is the warp CT image of three lining warp twill 2.5D woven composite materials;

[0022] Figure 3 It is a weft projection diagram of three lining warp twill 2.5D woven composite materials;

[0023] Figure 4 It is a three-dimensional frame diagram of a 2.5-dimensional woven composite material with three-dimensional lining warp twill;

[0024] Figure 5 It is a standard model of three-warp twill 2.5-dimensional woven composite material;

[0025] Figure 6 It is a main body model of three warp twill 2.5D woven composite materials;

[0026] Figure 7 It is a geometric model of a 2.5-dimensional woven composite material that replaces three lining warp twills after assembly;

[0027] Figure 8 It is an overall model of a three-warp twill 2.5-dimensional woven composite material considering weft extrusion;

[0028] Fig. 9 It is the weft yarn connection section model;

[0029] Fig.10 It is a real CT weft yarn connection section diagram;

[0030] Fig.11 It is the latitudinal view of the model;

[0031] Fig.12 It is a real CT latitudinal view. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] The present invention provides a method for geometric modeling of a 2.5-dimensional braided composite material yarn, comprising the following steps:

[0034] 1) Establish the weft projection diagram of the 2.5D woven composite material with squeezed weft yarns, specifically,

[0035] 1-1) Scan the 2.5-dimensional woven composite material test piece using non-destructive testing technology to obtain the scanned image and the internal structural characteristics of the test piece; use software to measure the size of each component on the scanned image;

[0036] 1-2) Establish a weft projection diagram of the composite material considering weft yarn extrusion according to the size of each component.

[0037] 2) According to the weft projection diagram, a three-dimensional framework diagram of the 2.5-dimensional woven composite material with squeezed weft yarn is established. Specifically, the weft projection diagram is saved as a dwg format file and its version is converted to AutoCAD2007 version. The converted projection diagram is opened by UG NX 10.0. The four boundaries of the projection diagram are selected in UG NX 10.0 software, and the stretching length is set to the weft length of the unit cell model to form a three-dimensional framework diagram, and the three-dimensional framework diagram is exported as an igs format file.

[0038] 3) A standard model of a 2.5-dimensional woven composite material is established based on the three-dimensional framework diagram. Specifically, the three-dimensional framework diagram in igs format is imported into the Hypermesh software, meshed, and the mesh is modified to remove the deformed mesh to obtain a new surface mesh unit, and then the volume mesh is divided to obtain the volume unit, and the volume unit is divided into components to obtain a standard model.

[0039] 4) Extract the original geometric block of the target position of the standard model, establish a weft yarn geometric block considering extrusion, and replace and assemble it to obtain the new model as a whole. Specifically, extract the original geometric block of the weft yarn target position on the standard model, and modify the geometric block according to the relationship between the two cross sections of the surface weft yarn and the weft yarn squeezed into the matrix in the weft yarn connection section in the overall model, so as to establish a weft yarn geometric block considering extrusion at the corresponding position, and replace and assemble the weft yarn geometric block considering extrusion to the original geometric block position.

[0040] 5) Structural coupling is performed on the new model as a whole to make it a complete whole with closely connected units.

[0041] Example

[0042] 1. Establish the weft projection diagram of the three-warp twill 2.5D woven composite material with squeezed weft yarns:

[0043] (1) X-CT and other non-destructive testing technologies were used to scan three warp twill 2.5D woven composite test pieces to obtain their internal structural characteristics; AutoCAD 2018 software was used to measure the dimensions of each component on the CT image, such as Figure 1 (a) Figure 1 (b) and Figure 2 The measured unit cell boundary dimensions are: longitudinal length 6.045 mm, latitudinal length 7.8 mm, and height 4.5906 mm.

[0044] (2) The weft projection diagram of the composite material considering weft yarn extrusion was established on AutoCAD 2018 software, as shown in Figure 3 .

[0045] 2. Establish a three-dimensional framework diagram of a 2.5-dimensional woven composite material with three warp twills and squeezed weft yarns:

[0046] (1) Save the above projection as a dwg file and convert it to AutoCAD 2007. Open the converted projection in UG NX 10.0. Select the four boundaries of the projection in this software, set the stretch length to 7.8 mm, save it, and export the model as an igs file, such as Figure 4 .

[0047] 3. Establish a standard model of three-warp twill 2.5D woven composite materials:

[0048] (1) Import the above igs format file into Hypermesh software, click surface edit in the Geom interface; after entering the trim with lines interface, click surfs, select the projection surface, click free lines, select the projection surface again, and click trim.

[0049] (2) Press F12 on the keyboard to enter the surface meshing interface. Select the projection surface in the details interface below, set the mesh size and mesh type, and click mesh. The meshing is complete.

[0050] (3) Hold the surface mesh straight in front of you and carefully observe whether the mesh is deformed and whether the edges are offset compared to the AutoCAD drawing. If so, click delete in the Tool interface to enter the deletion interface, set the deletion type to elems, select the local surface mesh with errors in the figure, and click delete entity to delete it. Then, exit the current interface and enter the Geom interface, click nodes, and click the method of generating nodes by crossing straight lines to generate new nodes in the area where the mesh is deleted. Then, enter the 2D interface and click planes to enter the surface mesh modification details page, click trimmed on the left, select the mesh generation method as nodes, and click create once every 3 mesh nodes are selected to generate new surface mesh units.

[0051] (4) After the surface mesh is modified, perform volume mesh division. Enter the 3D interface, click solid map, and enter the volume mesh division details page. Click line drag on the left to enter the volume mesh division interface along the line; click elems to select the surface mesh; click lines to select a division path line in the figure, and in the two numerical columns on the right: elem size sets the volume mesh thickness size, and linear intensity sets the volume mesh variation range. Generally, the former size is 0.1mm, and the latter is set to 0; click mesh to complete the volume mesh division and obtain the volume unit.

[0052] (5) Next, divide the volume unit into components. Click mask on the Tool interface to hide the parts that are not divided temporarily, then return to the Tool interface and click organize. Enter the component division interface. Click Model in the left operation bar, select Components, create several new component names in this column, and set different colors for future use. On the component division details page at the bottom of the page, click dest component, select the name of the component to be divided, and select the unit in the volume grid above. After the selection of several units is completed, click move on the right to complete the volume grid component division of a certain component. Follow the same operation to complete the division of all components and obtain the standard model. The corresponding results are as follows Figure 5 .

[0053] 4. Establish a separate weft geometry block considering extrusion

[0054] (1) Copy a standard model to extract the original block. Open the copied standard model in the new Hypermesh interface. It should be made clear that when the surface weft yarn is squeezed by the external mold, its cross section will be rectangular in the part not squeezed by the warp yarn; and it will be convex lens-shaped on the side where the weft yarn contacts the warp yarn. The section where the surface weft yarn contacts the surface warp yarn will be squeezed into the matrix. As a result, some sections of the weft yarn connect the surface weft yarn section and the section embedded in the matrix. This section will establish this connection section separately.

[0055] (2) Based on the above description, and deleting the part to be replaced, we get Figure 6 The main model shown is for standby use.

[0056] (3) Open the extracted original block in the new Hypermesh interface. According to the relationship between the two sections of the surface weft yarn and the weft yarn squeezed into the matrix in the weft yarn connection section in the overall model, make the following modifications: click faces in the Tool interface, select the entire original block, click find faces, and extract the face mesh of the original block; return to the Tool interface, click mask to hide the face mesh, return to the Tool interface again and click delete to delete the volume mesh of the original block. As a result, there is only the face mesh in the original block. According to the geometric relationship between the two sections mentioned above, connect the straight lines at the corresponding points of the two sections. For the curved part of the weft yarn section, click several nodes on the mesh in Geom→lines to form a smooth arc. Similarly, the remaining connection lines are also completed one after another. Set cross lines on these connection lines, thereby setting nodes, and click 2D→planes to manually divide the surface mesh. The same is true for the other interfaces, thereby dividing the original block into three parts. At the same time, in order to make the unit of the target block in contact with the matrix part of the overall model fit, the shape of the side unit of the target block must be modified so that the unit shapes of the two faces coincide.

[0057] (4) In the edges of the Tool interface, select the coupling unit type as elems, set the coupling size to 0.0001, and click find edges to couple the modified surface mesh. Return to the tetramesh of the 3D interface, select Tetramesh on the left, select elems for the two middle unit types, select nodes for Anchor nodes, select the three parts respectively, and click mesh to generate a tetrahedral mesh inside each part. Then couple the three parts through Tool→edges→findedges→preview equiv→equivalence. At this point, the target block is established. Figure 7 .

[0058] 5. Replace the assembly part

[0059] (1) After completing the block model, open the Figure 7 Import the above block model. The initial position of the block model is not the target position. You need to use Tool→reflect, Tool→rotate or Tool→position to assemble each target block at the target position to complete the overall model. Figure 8 .

[0060] 6. Structural coupling

[0061] (1) After the target blocks are assembled at the target positions, they look like a whole. In fact, there is no connection between the blocks and the main model. This will cause huge rigid body displacements in the finite element calculation, resulting in calculation errors. Therefore, you need to click Tool→edges→find edges→preview equiv→equivalence to complete the coupling of the target blocks and the main model to form a real whole. After the unit is coupled, the overall model looks almost the same as before the coupling, so the state after coupling remains the same. Figure 8 .

[0062] 7. Comparison of modeling results and CT images

[0063] The weft yarn connection section model is as follows Fig. 9 , the actual CT weft yarn connection section is shown in the figure Fig.10 ;

[0064] The model zonal view is as follows Fig.11 , the latitudinal view of the real object CT is as follows Fig.12 .

[0065] 8. Evaluation results

[0066] according to Figure 9-12 The comparative analysis shows that the weft yarn is dislocated under the action of external force, and the weft yarn direction is bent due to the inward extrusion of the warp yarn. The weft yarn connection section just shows this feature. The model diagram is consistent with the actual diagram. Therefore, this embodiment proves that the present invention can better show the situation where the weft yarn changes due to the influence of the processing technology.

[0067] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A geometric modeling method for 2.5-dimensional braided composite yarn, characterized in that: The following steps are involved: 1) Establish the weft projection diagram of the 2.5D woven composite material with squeezed weft yarns; Specifically, 1-1) Use non-destructive testing technology to scan the 2.5D braided composite material test piece, obtain the scanned image and the internal structural characteristics of the test piece, and use software to measure the size of each component on the scanned image; 1-2) establishing a weft projection diagram of the composite material considering weft yarn extrusion according to the size of each component; 2) Based on the weft projection diagram, a three-dimensional frame diagram of the 2.5-dimensional woven composite material with squeezed weft yarn is established; Specifically, Save the latitudinal projection map as a dwg file and convert it to AutoCAD 2007. Open the converted projection map in UG NX 10.

0. Select the four boundaries of the projection map in UG NX 10.0 software, set the stretching length to the latitudinal length of the unit cell model, form a three-dimensional frame map, and export the three-dimensional frame map to an igs file. 3) Establish a standard model of 2.5D woven composite materials based on the three-dimensional frame diagram; Specifically, Import the stereoscopic frame image in igs format into Hypermesh software, perform mesh division, modify the mesh to remove the deformed mesh, obtain new surface mesh units, perform volume mesh division on the new surface mesh units, obtain volume units, divide the volume units into components, and thus obtain a standard model; 4) Extract the original geometric block of the target position of the standard model, establish a weft geometric block considering extrusion, and perform replacement assembly to obtain the new model as a whole; Specifically, Extract the original geometric block of the weft yarn target position on the standard model, and modify the original geometric block according to the relationship between the surface weft yarn and the weft yarn squeezed into the matrix at the weft yarn connection section in the overall model, so as to establish a weft yarn geometric block considering extrusion at the corresponding position, and replace the weft yarn geometric block considering extrusion with the original geometric block position; 5) Structural coupling is performed on the new model as a whole to make it a complete whole with closely connected units.

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