Full-size finite element modeling method for multi-angle plain laying composite material

Abstract

The invention relates to a full-size finite element modeling method of a multi-angle plain ply composite material, which aims to overcome the limitation of the existing modeling method, and comprises the following steps of: establishing a geometric model according to the actual size of a test piece; calculating a center point coordinate of each unit in the grid model; establishing division standards of warp yarn and weft yarn areas under the global coordinate system of the model; traversing the center point coordinates of all units, and judging the area to which each unit belongs by combining the boundary point coordinates of the warp and weft areas; according to the areas to which the units belong, two unit sets are created for each laying layer, and the units with the central points located in the warp yarn area and the units with the central points located in the weft yarn area are stored; the units of the warp yarn area and the units of the weft yarn area of each laying layer are endowed with corresponding material performance and material direction, and follow-up finite element simulation calculation continues to be conducted. According to the invention, the accuracy of damage analysis is improved. The invention belongs to the technical field of composite material simulation and modeling.

Description

Technical Field

[0001] The present invention relates to a modeling method, specifically to a full - scale finite - element modeling method for multi - angle plain - weave laminated composites, and belongs to the technical field of composite material simulation and modeling. Background Art

[0002] Plain - weave laminated composites are a unique structure formed by the interweaving of warp and weft fiber bundles. This material has important applications in the composite field and exhibits excellent mechanical properties due to its unique weaving structure. However, due to the complex interweaving pattern of the fiber bundles, traditional finite - element modeling methods face many challenges when dealing with this material.

[0003] Currently, for the finite - element modeling of plain - weave laminated composites, the unit - cell modeling method is usually adopted. This method selects a periodic region of the plain - weave structure, constructs geometric models of the fiber bundles and the matrix respectively, divides a fine mesh on this basis, and then applies periodic boundary conditions to obtain homogenized material parameters. However, the unit - cell modeling method exposes obvious limitations when applied to the full - scale modeling of specimens. First, due to the highly complex weaving structure of plain - weave laminated composites, a large number of meshes are required to accurately describe the geometric features of the structure during full - scale modeling. This leads to a significant increase in the amount of calculation. Especially when the size of the material is large, the number of meshes in the model is huge, and the calculation difficulty is significantly increased, even exceeding the capabilities of conventional computing resources. Second, for a plain - weave structure with multiple - angle plies, it is difficult to find a unified periodic region suitable for the entire structure. The yarn directions of plain - weave plies are variable, and traditional unit - cell modeling methods cannot effectively handle the yarn distribution characteristics under multiple - direction plies. Therefore, although such methods can obtain certain homogenized parameters in a small - size periodic region, their applicability is limited in practical applications, especially for large - size models.

[0004] In addition, to simplify the calculation, existing full - scale finite - element modeling methods usually directly perform mesh division based on the geometric model of the specimen and assign homogenized parameters to the meshes. Although this method reduces the number of meshes and the computational complexity to a certain extent, it does not distinguish between warp and weft yarns in the plain - weave structure. This simplified treatment ignores the different damage modes between the yarns, especially the mesoscopic damage that may occur during the use of composite materials. Under this modeling method, the mechanical behavior differences between warp and weft yarns cannot be accurately described, resulting in insufficient accuracy in damage behavior analysis.

[0005] Therefore, the existing full - scale finite - element modeling methods for multi - angle plain - weave laminated composites lack accurate division of the warp and weft regions and are difficult to accurately analyze material damage. Summary of the Invention

[0006] To overcome the limitations of existing modeling methods and solve the problem that the full-scale finite element modeling method for multi-angle plain weave laminated composites in the prior art lacks accurate division of warp and weft regions and is difficult to accurately analyze material damage, a full-scale finite element modeling method for multi-angle plain weave laminated composites is proposed.

[0007] The technical solution adopted by the present invention to solve the above problems is as follows:

[0008] A full-scale finite element modeling method for multi-angle plain weave laminated composites according to the present invention includes the following steps:

[0009] Step 1: Establish a geometric model according to the actual size of the specimen;

[0010] Step 2: Calculate the central point coordinates of each element in the mesh model;

[0011] Step 3: Establish the division criteria for the warp and weft regions in the global coordinate system of the model;

[0012] Step 4: Traverse the central point coordinates of all elements, and combine with the boundary point coordinates of the warp and weft regions to determine the region to which each element belongs;

[0013] Step 5: According to the region to which the element belongs, create two element sets for each ply, respectively storing the elements with the central point located in the warp region and the weft region;

[0014] Step 6: Assign corresponding material properties and material directions to the elements in the warp region and the weft region of each ply, and continue with the subsequent finite element simulation calculation.

[0015] Further, in Step 1, the established geometric model is meshed so that each ply contains upper and lower two layers of meshes in the thickness direction, and the region positions of the warp and weft in the upper and lower two layers of meshes are opposite.

[0016] Further, in Step 2, the calculation formula for the element central point coordinates is as follows:

[0017]

[0018] where n is the number of element nodes, x i , y i , z i are the coordinates of the element nodes.

[0019] Further, in Step 3, for each layer of plain weave composite material, first set the initial point (x 0 , y 0), for the two layers of units corresponding to this layer, the positions of the warp and weft regions are opposite. The central point coordinates corresponding to the warp and weft regions of the first layer of units are generated through Formula 2, and the central point coordinates corresponding to the warp and weft regions of the second layer of units are generated through Formula 3.

[0020]

[0021]

[0022] where i = 0, 1, 2,..., N rows -1, j = 0, 1, 2,..., N cols -1, N rows and N cols are respectively the array numbers of the plain weave structure unit cells along the x and y directions; (x wrap1 , y wrap1 ), (x wrap2 , y wrap2 ) are the central coordinate sets of the warp regions of the first layer of units corresponding to each layer of plain weave composites, (x weft1 , y weft1 ), (x weft2 , y weft2 ) are the central coordinate sets of the weft regions of the first layer of units, and s is the yarn width in the plain weave structure.

[0023] Furthermore, in Step 4,

[0024] Based on the central point coordinates of the warp and weft regions, calculate the boundary point coordinates of the warp and weft regions through Formula 4:

[0025]

[0026] For the plies with the ply direction inconsistent with the global coordinate system of the model, calculate the boundary point coordinates of the warp and weft regions under this ply through Formula 5:

[0027]

[0028] where θ is the ply angle, (x k , y k ) are the boundary point coordinates of the warp and weft regions of the ply with the ply direction consistent with the global coordinate system, (x′ k , y′ k ) are the boundary point coordinates of the warp and weft regions of the ply with the ply direction inconsistent with the global coordinate system, and k = 1, 2, 3, 4.

[0029] Traverse the central point coordinates of the units obtained in Step 2, use the boundary coordinates of the yarn regions obtained in Steps 4 and 5, and sequentially determine the yarn regions where the central points of each unit are located through Formula 6;

[0030]

[0031] where (x i , y i ), i = 1, 2, 3, 4 are the boundary point coordinates of the yarn area, and (x p , y p ) are the coordinates of the unit center point. When the signs of cross(1, 2, p), cross(2, 3, p), cross(3, 4, p) and cross(4, 1, p) are the same, the unit is assigned to this yarn area.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. By accurately distinguishing the warp and weft areas in the plain weave structure, the present invention establishes a more realistic and accurate full-scale finite element model. This model can comprehensively capture the yarn damage information in materials and structures during the simulation process, including local damage, fiber fracture, interlayer slip, etc., thus significantly improving the accuracy of damage analysis and having higher reliability especially in the performance prediction under high loads and complex loads.

[0034] 2. The modeling method adopted by the present invention not only improves the simulation accuracy but also effectively reduces the number of redundant elements in mesh generation. Through reasonable area division and simplified mesh generation, the computational complexity and time cost are significantly reduced, ensuring the efficiency of the model in large-scale finite element simulations. Compared with traditional methods, the present invention greatly reduces the consumption of computing resources and improves the computing efficiency, especially suitable for the simulation analysis of large-size and multi-layer composite materials.

[0035] 3. The method of the present invention has strong adaptability and can handle various plain weave laminated composites with different ply angles and yarn arrangements. Whether in the aerospace, automotive manufacturing or wind power generation industries, accurate structural performance analysis can be carried out through this method, optimizing material design and improving the overall performance and safety of the structure. Description of the Drawings

[0036] Figure 1 is a flowchart of a full-scale finite element modeling method for a multi-angle plain weave laminated composite material proposed by the present invention;

[0037] Figure 2 is a distribution schematic diagram of the warp and weft areas of each ply in the present invention;

[0038] Figure 3 is a schematic diagram of the division of the warp and weft areas corresponding to two layers of meshes in the 0° ply of the plain weave open-hole specimen in the embodiment of the present invention;

[0039] Figure 4 In the embodiment of the present invention, it is a schematic diagram of the division of the warp and weft yarn areas corresponding to two layers of grids in the 45° ply of the plain weave open-hole specimen. Detailed implementation manner

[0040] Detailed implementation manner: This implementation manner will be described in conjunction with the accompanying drawings. This implementation manner establishes a full-scale finite element model for the plain weave open-hole test piece with a ply angle of [0° / 45°] 8 , and the process is as Figure 1 shown, including the following steps:

[0041] Step 1: According to the actual size of the specimen, establish its geometric model. In the finite element simulation software, perform mesh division according to the number of layers of the plain weave composite material to ensure that each layer of the composite material contains two layers of grids in the thickness direction. Establish an element set for each layer of elements, and export the node, mesh, and element set information as a text file.

[0042] Step 2: Use a Python program to read the exported text file, traverse each element, and calculate its center point coordinates. The calculation formula for the center point coordinates of the element is as follows:

[0043]

[0044] where n is the number of element nodes, x i , y i , z i are the coordinates of the element nodes.

[0045] Step 3: For each ply, set the initial plane point, and calculate the boundary point coordinates of the warp and weft yarn areas respectively. The elements of each ply are divided into upper and lower layers, and the positions of the warp and weft yarn areas of the upper and lower layers are opposite. As Figure 2 shown, it is a schematic diagram of the distribution of the warp and weft yarn areas of the two layers of elements corresponding to each ply.

[0046] For each layer of plain weave composite material, first set the initial point (x 0 , y 0 ). For the two layers of elements corresponding to this layer, the positions of the warp and weft yarn areas are opposite. The center point coordinates corresponding to the warp and weft yarn areas of the first layer of elements are generated through formula 2, and the center point coordinates corresponding to the warp and weft yarn areas of the second layer of elements are generated through formula 3.

[0047]

[0048]

[0049] where i = 0, 1, 2,..., N rows -1, j = 0, 1, 2,..., Ncols -1, N rows and N cols are the number of arrays of the plain weave structure unit cells along the x and y directions respectively; (x wrap1 , y wrap1 ), (x wrap2 , y wrap2 ) are the central coordinate sets of the warp regions of the first layer units corresponding to each layer of plain weave composites, (x weft1 , y weft1 ), (x weft2 , y weft2 ) are the central coordinate sets of the weft regions of the first layer units, and s is the yarn width in the plain weave structure.

[0050] Step 4, based on the central point coordinates of the warp region and the weft region, calculate the boundary point coordinates of the warp and weft regions through Formula 4:

[0051]

[0052] Step 5, for the plies with the ply direction inconsistent with the global coordinate system of the model, calculate the boundary point coordinates of the warp and weft regions under this ply through Formula 5:

[0053]

[0054] where θ is the ply angle, (x k , y k ) are the boundary point coordinates of the warp and weft regions of the ply with the ply direction consistent with the global coordinate system, (x′ k , y′ k ) are the boundary point coordinates of the warp and weft regions of the ply with the ply direction inconsistent with the global coordinate system, and k = 1, 2, 3, 4.

[0055] The regional division results of the 0° ply are as shown in Figure 3 and those of the 45° ply are as shown in Figure 4 .

[0056] Step 6, traverse the central point coordinates of the units obtained in Step 2, and use the boundary coordinates of the yarn regions obtained in Steps 4 and 5 to sequentially determine the yarn regions where the central points of each unit are located through Formula 6

[0057]

[0058] where (x i , y i ), i = 1, 2, 3, 4 are the boundary point coordinates of the yarn regions, (x p , y p) is the coordinate of the unit center point. When the signs of cross(1,2,p), cross(2,3,p), cross(3,4,p), and cross(4,1,p) are the same, this unit is classified into this yarn area.

[0059] Step 7: Create two unit sets for each ply in the text file, storing the units with the center points located in the warp area and the weft area respectively. Subsequently, re-import the text file into the finite element simulation software, assign different material properties and directions to the warp area and the weft area of each ply respectively, and continue with the subsequent finite element simulation calculations.

[0060] The above description is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention and is based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims

1. A full-scale finite element modeling method for multi-angle flat-ply composite materials, characterized in that: The method comprises the following steps: Step 1: Establish a geometric model based on the actual size of the specimen; Step 2: Calculate the center point coordinates of each unit in the grid model; Step 3: Establish the division standard of warp and weft areas in the global coordinate system of the model; Step 4: traverse the center point coordinates of all units, and combine the boundary point coordinates of the warp and weft areas to determine the area to which each unit belongs; Step 5: Create two unit sets for each layer according to the area to which the unit belongs, storing the units whose center points are located in the warp area and the units in the weft area respectively; Step 6: Assign corresponding material properties and material directions to the units in the warp yarn area and the weft yarn area of ​​each layer, and continue with subsequent finite element simulation calculations.

2. A full-scale finite element modeling method for a multi-angle flat-ply composite material according to claim 1, characterized in that: In step 1, the established geometric model is meshed so that each ply includes an upper and a lower layer of meshes in the thickness direction, and the regional positions of the warp yarns and the weft yarns in the upper and lower layers of meshes are opposite.

3. The full-scale finite element modeling method of a multi-angle flat-ply composite material according to claim 1, characterized in that: In step 2, the calculation formula of the unit center point coordinates is as follows: Where n is the number of unit nodes, x i ,y i ,z i are the coordinates of the element nodes.

4. The full-scale finite element modeling method of a multi-angle flat-ply composite material according to claim 1, characterized in that: In step 3, for each layer of plain weave composite material, the initial point (x0, y0) is first set, and the positions of the warp and weft regions of the two layers of units corresponding to the layer are opposite. The center point coordinates of the warp and weft regions of the first layer unit are generated by formula 2, and the center point coordinates of the warp and weft regions of the second layer unit are generated by formula 3; Warp Area: Weft area: Warp Area: Weft area: where i=0,1,2,...,N rows -1, j = 0, 1, 2, ..., N cols -1, N rows and N cols are the array numbers of the plain weave unit cells along the x and y directions respectively; (x wrap1 ,y wrap1 ),(x wrap2 ,y wrap2 ) is the center coordinate set of the warp yarn area of ​​the first layer unit corresponding to each layer of plain weave composite material, (x weft1 ,y weft1 ),(x weft2 ,y weft2 ) is the center coordinate set of the weft yarn area of ​​the first layer unit, and s is the yarn width in the plain weave structure.

5. The full-scale finite element modeling method of a multi-angle flat-ply composite material according to claim 1, characterized in that: In step four, Based on the center point coordinates of the warp yarn area and the weft yarn area, the boundary point coordinates of the warp yarn area and the weft yarn area are calculated by formula 4: For plies whose ply directions are inconsistent with the global coordinate system of the model, the coordinates of the boundary points of the warp and weft regions under the ply are calculated using Formula 5: Where θ is the ply angle, (x k ,y k ) is the boundary point coordinate of the warp and weft regions of the ply in the ply direction consistent with the global coordinate system, (x′ k ,y′ k ) are the boundary point coordinates of the warp and weft regions of the ply where the ply direction is inconsistent with the global coordinate system, k = 1, 2, 3, 4; Traverse the unit center point coordinates obtained in step 2, use the yarn area boundary coordinates obtained in steps 4 and 5, and use formula 6 to determine the yarn area where the center point of each unit is located in turn; Where (x i ,y i ),i=1,2,3,4 are the coordinates of the boundary points of the yarn area, (x p ,y p ) are the coordinates of the unit center point. When cross(1,2,p), cross(2,3,p), cross(3,4,p) and cross(4,1,p) have the same signs, the unit is assigned to the yarn area.

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