A method and apparatus for micro-modeling of stitched preform composites

Abstract

This invention relates to the field of yarn modeling technology, and more particularly to a method and apparatus for microscopic modeling of stitched prefabricated composite materials. The invention searches for the first contact pair range between the virtual fibers of the stitching yarn and the geometric model of the fiber prefabricated structure to be stitched in each load step; while expanding the radius of the virtual fibers of the stitching yarn to a target size, a second contact pair range is determined based on the first contact pair range; within the second contact pair range, the contact force of each contact pair is determined; within the second contact pair range, the corresponding contact force is applied to the corresponding nodes of each contact pair to perform deformation simulation, obtaining the geometric model of the stitched fiber prefabricated structure; the geometric model of the stitched fiber prefabricated structure is then transformed to obtain a finite element micromechanical model. Thus, this invention can improve the prediction accuracy of the mechanical properties of stitched prefabricated composite materials.

Description

Technical Field

[0001] This invention relates to the field of yarn modeling technology, and in particular to a method and apparatus for microscopic modeling of stitched prefabricated composite materials. Background Technology

[0002] Three-dimensional stitched prefabricated structures utilize stitching yarns along the thickness direction to lock multiple layers of fiber fabric into a single unit. They possess advantages such as high interlayer strength, resistance to delamination, impact resistance, and the ability to be integrally molded, making them key reinforcements for aerospace main load-bearing structures and highly reliable lightweight components. The micro-geometry of the stitched prefabricated structure directly determines the mechanical properties and failure modes of the composite material. Constructing a high-fidelity micro-geometric model that can be directly used for finite element simulation is an important approach to achieving multi-scale calculations of composite materials and optimizing process parameters.

[0003] Existing geometric modeling methods for stitched precast structures mostly assume the stitching yarn path is an ideal geometric curve with a fixed cross-sectional shape. This makes it difficult to realistically reflect the actual process effects such as yarn compression, displacement, and cross-sectional shape changes during stitching yarn piercing. The resulting model geometry deviates significantly from the actual precast structure, making it difficult to accurately predict the mechanical properties of the actual component and providing reliable model support for optimizing stitching process parameters. Furthermore, while modeling methods based on experimental observations such as CT scans to obtain microstructural information can reconstruct the true geometry of the precast structure to some extent, these methods require sophisticated experimental equipment, are complex and time-consuming, and cannot provide early prediction capabilities.

[0004] Based on this, the present invention proposes a microscopic modeling method and apparatus for stitched preform composite materials to address the problem of how to improve the prediction accuracy of the mechanical properties of stitched preform composite materials. Summary of the Invention

[0005] To address the problem of improving the prediction accuracy of the mechanical properties of stitched precast composite materials, this invention provides a method and apparatus for microscopic modeling of stitched precast composite materials.

[0006] In a first aspect, embodiments of the present invention provide a method for microscopic modeling of stitched prefabricated composite materials, including: The geometric models of the fiber prefabricated bodies to be sewn are superimposed, and the sewing yarn path is determined using a sine function; The sewing yarn path is divided into a first preset number of load steps, and the sewing yarn path is split into a second preset number of sewing yarn virtual fibers; wherein each load step corresponds to multiple sub-load steps; In each load step, search for the range of the first contact pair between the virtual fibers of the stitching yarn and the geometric model of the fiber preform to be stitched; During the process of expanding the radius of the virtual fiber of the sewing yarn to the target size, the range of the second contact pair is determined based on the range of the first contact pair; Within the range of the second contact pair, determine the contact force of each contact pair; Within the range of the second contact pair, a corresponding contact force is applied to each node of the contact pair to perform deformation simulation and obtain the geometric model of the stitched fiber preform. The geometric model of the stitched fiber preform is transformed to obtain a finite element micromechanical model; the finite element micromechanical model is used to predict the mechanical properties of the stitched preform composite material.

[0007] Secondly, embodiments of the present invention provide a microscopic modeling apparatus for stitched prefabricated composite materials, comprising: The first data processing module is used to superimpose the geometric models of the fiber prefabricated body to be sewn and use a sine function to determine the sewing yarn path; The second data processing module is used to divide the sewing yarn path into a first preset number of load steps and split the sewing yarn path into a second preset number of sewing yarn virtual fibers; wherein each load step corresponds to multiple sub-load steps. The third data processing module is used to search for the first contact pair range between the virtual fibers of the sewing yarn and the geometric model of the fiber preform to be sewn in each load step; The fourth data processing module is used to determine the range of the second contact pair based on the range of the first contact pair during the process of expanding the radius of the virtual fiber of the sewing yarn to the target size. The fifth data processing module is used to determine the contact force of each contact pair within the range of the second contact pair. The sixth data processing module is used to apply corresponding contact force to each corresponding node of the second contact pair within the range of the second contact pair in order to perform deformation simulation and obtain the geometric model of the stitched fiber preform. The seventh data processing module is used to convert the geometric model of the stitched fiber preform into a finite element micromechanical model; the finite element micromechanical model is used to predict the mechanical properties of the stitched preform composite material.

[0008] Thirdly, embodiments of the present invention also provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the method described in any embodiment of the present invention.

[0009] Fourthly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the methods described in any embodiment of the present invention.

[0010] This invention provides a method and apparatus for microscopic modeling of stitched prefabricated composite materials. First, at least two geometric models of fiber prefabricated structures to be stitched are superimposed. Simultaneously, the stitching yarn path is obtained based on a sine function. Then, the complete stitching yarn path is decomposed into a first preset number of load steps. A single stitching yarn path generates a second preset number of virtual stitching yarn fibers, and each load step is further subdivided into multiple sub-load steps. During the simulation calculation of each load step, the contact area between the virtual stitching yarn fibers and the geometric model of the fiber prefabricated structure to be stitched is first searched globally to initially define the first contact pair range. Subsequently, during the dynamic process of the virtual stitching yarn fiber radius gradually expanding to the target process size, the initial first contact pair range is iteratively corrected to determine the second contact pair range that conforms to the actual contact state. Based on this, the contact force of all contact pairing units within the second contact pair range is calculated to clarify the force value of each contact node. For all corresponding nodes within the second contact pair range, matching contact forces are applied to complete the dynamic deformation simulation, simulating the actual stitching compression and bonding deformation process, ultimately obtaining the geometric model of the stitched fiber prefabricated structure. Finally, the geometric model of the stitched prefabricated body obtained from the simulation is transformed to construct a high-precision finite element micromechanical model. This invention effectively avoids the problem of insufficient accuracy in traditional simulation models by using step-by-step refined simulation and dynamic contact correction, thereby improving the prediction accuracy of the mechanical properties of the stitched prefabricated composite material. Attached Figure Description

[0011] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A flowchart of a microscopic modeling method for stitched prefabricated composite materials according to one embodiment is shown; Figure 2 This is a hardware architecture diagram of an electronic device provided in an embodiment of the present invention; Figure 3 A structural diagram of a microscopic modeling apparatus for stitched preform composite materials according to one embodiment is shown; Figure 4 A schematic diagram of the geometric model of the stitched fiber preform according to one embodiment is shown; Figure 5 A schematic diagram of the centroid of the sewing yarn at any two cross sections is shown according to one embodiment; Figure 6 A schematic diagram of contact pair lookup according to one embodiment is shown; Figure 7 A schematic diagram illustrating the relative relationships of contact forces according to one embodiment is shown; Figure 8 A schematic diagram illustrating the gradual expansion and fission of virtual fibers in a stitching yarn according to one embodiment is shown. Figure 9 A schematic diagram of the geometric model of the stitched fiber preform according to one embodiment is shown. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0014] Please refer to Figure 1 This invention provides a method for microscopic modeling of stitched prefabricated composite materials, including: Step 100: Superimpose the geometric models of the fiber prefabricated bodies to be sewn and use a sine function to determine the sewing yarn path; Step 102: Divide the sewing yarn path into a first preset number of load steps, and split the sewing yarn path into a second preset number of sewing yarn virtual fibers; wherein, each load step corresponds to multiple sub-load steps; Step 104: In each load step, search for the first contact pair range between the virtual fibers of the stitching yarn and the geometric model of the fiber preform to be stitched; Step 106: During the process of expanding the radius of the stitching yarn virtual fiber to the target size, determine the range of the second contact pair based on the range of the first contact pair; Step 108: Within the range of the second contact pair, determine the contact force of each contact pair; Step 110: Within the range of the second contact pair, apply the corresponding contact force to each corresponding node of the contact pair to perform deformation simulation and obtain the geometric model of the stitched fiber preform. Step 112: Transform the geometric model of the stitched fiber preform to obtain a finite element micromechanical model; the finite element micromechanical model is used to predict the mechanical properties of the stitched preform composite material.

[0015] In this embodiment, at least two fiber prefabricated geometric models to be sewn are first superimposed. Simultaneously, the sewing yarn path is obtained based on a sine function. Then, the complete sewing yarn path is decomposed into a first preset number of load steps. A single sewing yarn path generates a second preset number of virtual sewing yarn fibers, and each load step is further subdivided into multiple sub-load steps. During the simulation calculation of each load step, the contact area between the virtual sewing yarn fibers and the geometric model of the fiber prefabricated body to be sewn is first searched globally to initially define the first contact pair range. Subsequently, during the dynamic process of the virtual sewing yarn fiber radius gradually expanding to the target process size, the initial first contact pair range is iteratively corrected to determine the second contact pair range that conforms to the actual contact state. Based on this, the contact force of all contact pairing units within the second contact pair range is calculated to clarify the force value of each contact node. For all corresponding nodes within the second contact pair range, matching contact forces are applied to complete the dynamic deformation simulation, simulating the actual sewing compression and bonding deformation process, ultimately obtaining the sewn fiber prefabricated geometric model. Finally, the simulated sewn prefabricated geometric model is converted to construct a high-precision finite element micromechanical model. This invention effectively avoids the problem of insufficient accuracy in traditional simulation models by using step-by-step refined simulation and dynamic contact correction, thereby improving the prediction accuracy of the mechanical properties of stitched precast composite materials.

[0016] like Figure 4 As shown, in this embodiment, the geometric model of the fiber prefabricated bodies to be sewn (prefabricated body 1 and prefabricated body 2 in the figure) is input. This model refines the spatial path, cross-sectional shape, and interwoven topological relationships of the yarns at a microscale. A discretization modeling method is used, discretizing each yarn into an assembly of virtual fibers. Each virtual fiber consists of several node-connected rod units. Furthermore, the model construction follows non-penetrating geometric constraints, ensuring no interference between yarns or fibers. The rod units and nodes in the model are numbered to form a set of unit numbers and a set of node numbers. The two fiber prefabricated body geometric models to be sewn are then sewn together using sewing yarn (sewing thread in the figure) to obtain the sewn fiber prefabricated body geometric model (the sewn prefabricated body in the figure).

[0017] In one embodiment of the present invention, the geometric model of the stitched fiber prefabricated body is transformed to obtain a finite element micromechanical model, including: The overall space of the geometric model of the stitched fiber prefabrication is divided into multiple cubic meshes. Based on the preset unit fiber volume fraction threshold, the cubic mesh is divided into yarn units and matrix units; Among them, yarn elements and matrix elements are used to construct the finite element micromechanical model.

[0018] In this embodiment, the overall space is divided into n x ×n y ×n z Each cubic mesh is divided into yarn units and matrix units based on a preset fiber volume fraction threshold (e.g., 10%). The fiber volume fraction of a yarn unit is determined by the total volume of all virtual fibers passing through that unit, as shown in the following formula: In the formula, It is the fiber volume fraction of yarn unit k. It is the volume of virtual fiber i. It is the size of the space occupied by the yarn unit k.

[0019] Establish a unit coordinate system for each unit. In the unit coordinate system of the yarn unit, direction 1 is determined by the weighted average of the orientation vectors of all virtual fibers passing through the unit, based on their volume fraction within the unit. The specific formula is as follows. In the formula, It is the direction vector of the unit coordinate system 1 of yarn unit k. It is the direction vector of virtual fiber i. After all yarn units are calculated in the unit coordinate system, a complete Voxel unit coordinate system can be established. The three directions are obtained by cross-multiplying the first direction by the second direction. The matrix can be directly discretized through the Voxel mesh, and its unit coordinate system adopts the global coordinate system. The yarn is assumed to be a transversely anisotropic material, and the yarn elastic constants are calculated by the Chamis model.

[0020] In one embodiment of the present invention, the contact force includes a first contact force and a second contact force; The contact force is determined by the following formula: In the formula, For the first contact force, For the second contact force, For contact stiffness, The distance between the two rod elements. It is the direction vector; The relationship between the load step and the virtual fiber radius of the stitching yarn is determined by the following formula: In the formula, For the virtual fiber radius of the sewing yarn, The preset sewing yarn radius, For radius coefficient, M is the second preset quantity, and M is the first preset quantity.

[0021] In this embodiment, the virtual fiber is gradually expanded to the target yarn specification size in N load steps to form the spatial path of the suture yarn. During the expansion process, further contact confirmation is required for each pair of rod elements in the numbered set of potential contact pairs at each load step. The specific method is: for a determined set of rod elements of potential contact pairs (such as Figure 6 AB and CD therein), m discrete points are interpolated between the two rod elements. To improve calculation efficiency, the value of m should not be too large, and m=3 can be taken. Assuming that the radii of the two rod elements are r1 and r2 respectively, the distances between every two discrete points of the two rod elements are calculated to obtain the two nodes (a1 and b1) with the minimum distance (d1); then, the segments adjacent to these two nodes are discretized into m nodes again, and a more accurate minimum distance (d2), which is the distance between the two nodes (a2 and b2), is calculated; the minimum distance (d3) obtained after three times of discretization, which is the distance between the two nodes (a3 and b3), is taken as the final distance between the two rod elements. When the distance d3 < d0, it is confirmed that there is contact between the two, forming a numbered set of rod element contact pairs. When the distance d3 > d0, there is no contact, where d0 = r1 + r2. If there is contact between the rod elements, the magnitude of the contact force is calculated, and the magnitude of the contact force can be calculated by the following formula: where k is the contact stiffness, d is the distance between the two rod elements, is the direction vector.

[0022] In this embodiment, the virtual fibers in the suture yarn are subjected to expansion and fission in M load steps to form a plurality of virtual fibers. The detailed fission process can be described as follows: the suture yarn is initially discretized into one virtual fiber with a radius of 0, and this fiber continuously expands. When the fiber radius expands to α1R1, it fissions into 2 virtual fibers with a radius of α1R1 / 2. Then, the 2 virtual fibers with a radius of α1R1 / 2 continue to expand. When the fiber radius expands to α2R2, each fiber fissions into 2 virtual fibers with a radius of α2R2 / 2. Subsequently, the 4 virtual fibers with a radius of α2R2 / 2 continue to expand. When the fiber radius expands to α3R3, each fiber fissions into 2 virtual fibers with a radius of α3R3 / 2. By analogy, after M times of expansion and fission, 2 (M-1) virtual fibers with a radius of α M R M are formed, where R M corresponds to the radius of each virtual fiber after M times of fission, which can be calculated from the preset suture yarn radius R, and the calculation formula is: In the formula, is the radius of the virtual fiber of the suture yarn, The preset sewing yarn radius, The radius coefficient takes values ​​in the range [0.5, 1] ​​and is monotonically increasing. M is the second preset quantity, and M is the first preset quantity.

[0023] In one embodiment of the invention, the search in each load step identifies the first contact pair range between the virtual fibers of the stitching yarn and the geometric model of the fiber preform to be stitched, including: The contact determination between the preset fibers is set as a threshold D. In each load step, the virtual fiber rod unit number and node number of the sewing yarn are extracted sequentially, and the distance d between the centroid of each rod unit on the sewing yarn and the centroid of the virtual fiber rod unit of the sewing yarn in the geometric model of the fiber prefabricated body to be sewn is calculated. If d>D, it is assumed that there will be no contact between the sewing yarn path and the geometric model of the fiber prefabricated body to be sewn, and the search for potential contact pairs of all rod elements on the sewing yarn is completed in sequence. If d≤D, it is assumed that the stitching yarn path may come into contact with the geometric model of the fiber preform to be stitched. The corresponding two stitching yarn virtual fiber rod unit numbers are matched as a pair of possible contact pairs to determine the range of the first contact pair.

[0024] In this embodiment, a global search is conducted to find potential contact pairs between the sewing yarn and the virtual fiber rod units in the geometric model of the fiber prefabricated body to be sewn. Specifically, a contact determination threshold D is set between preset fibers. The virtual fiber rod unit numbers and node numbers of the sewing yarn are extracted sequentially. The distance d between the centroid of each rod unit on the sewing yarn and the centroid of the virtual fiber rod unit in the geometric model of the fiber prefabricated body to be sewn is calculated. If d ≤ D, it is considered that the two may be in contact, and the corresponding two virtual fiber rod unit numbers are matched as a pair of potential contact pairs to form a set of potential contact pair numbers of rod units. If d > D, it is considered that the two will not be in contact. The search for potential contact pairs of all rod units on the sewing yarn is completed sequentially.

[0025] In one embodiment of the present invention, during the process of expanding the radius of the virtual fibers of the sewing yarn to a target size, the moving speed of the virtual fibers on the prefabricated body to be sewn is determined by the following formula: In the formula, The moving speed of the virtual fibers on the prefabricated body to be stitched. The distance from the virtual fiber node on the prefabricated body to be sewn to the virtual fiber of the sewing yarn is denoted as 'N'. It is a constant.

[0026] In this embodiment, the virtual fibers in the sewing yarn exert a squeezing effect on other fibers during the expansion process, causing the virtual fibers of the original preform yarn to shift, based on the distance between the virtual fiber nodes on the preform yarn to be sewn and the virtual fibers of the sewing yarn. d2 calculates the moving speed of nodes. The closer the nodes are, the greater the moving speed. This can be expressed as: α is a constant. This adjusts the spatial position of the original yarn's virtual fibers, and the virtual fibers of the stitching yarn itself continuously adjust their arrangement during expansion to avoid self-interference. Each load step re-confirms the contact of potential contact pairs and iteratively updates the spatial position of all fiber nodes to ensure that all fibers satisfy non-penetrating constraints and there is no geometric interference from mutual penetration. This improves the geometric model of the stitched fiber preform, thereby enhancing the accuracy of predicting the mechanical properties of the stitched preform composite material.

[0027] In one embodiment of the present invention, within the range of the second contact pair, a corresponding contact force is applied to each corresponding node of the contact pair to perform deformation simulation and obtain a geometric model of the stitched fiber preform, including: When the line connecting the centroids of the sewing yarns in two cross sections is not parallel to the line connecting the centroids of the virtual fibers of a single sewing yarn in the same cross section, the fiber node positions are corrected until the iterative calculation of all virtual fiber nodes of the sewing yarns converges and the spatial positions no longer change, thus obtaining the geometric model of the sewn fiber prefabricated body.

[0028] In this embodiment, to prevent distortion of the virtual fiber paths in the stitching yarn, fiber arrangement adjustments are added during the calculation in the first M-1 load steps, and no further control is applied in subsequent load steps. Specifically, it is determined whether the line connecting the centroids of the stitching yarn at two cross-sections is parallel to the line connecting the centroids of a single virtual fiber at the same cross-section. If they are not parallel, the fiber node positions are corrected to ensure that the direction of the single virtual fiber aligns with the overall path trend of the stitching yarn, thereby eliminating the risk of twisting. Once the iterative calculation of all virtual fiber nodes converges and their spatial positions no longer change, the fiber geometry model of the stitched prefabricated body is obtained. Figure 5 As shown, assume the centroids of the sewing yarn at any two cross-sections are O1(X1,Y1,Z1) and O2(X2,Y2,Z2), respectively, and the centroids of a virtual fiber in the sewing yarn at the same cross-sections are o1(x1,y1,z1) and o2(x2,y2,z2), respectively. The distance between the two cross-sections is H, and the vector connecting the centroids of the sewing yarn as a whole is given by... The vector connecting the centroids of a single virtual fiber is To determine if two vectors are parallel, if they are not, keep the coordinates of the virtual fiber nodes in section 1 unchanged, and adjust the coordinates of the virtual fiber nodes in section 2. The calculation formula is as follows: in, , , To eliminate the coordinates of the virtual fiber centroid of section 2 after torsion.

[0029] In one embodiment of the present invention, the stitching yarn path is determined by the following formula: In the formula, The coordinates represent the direction in which the yarn will be sewn. For amplitude, The coordinates are for the direction of yarn thickness.

[0030] In this embodiment, the geometric models of the fiber prefabricated bodies to be sewn are superimposed, and a regular sewing yarn path is generated using a sine function. The amplitude of the function is constrained according to the superposition thickness. Assuming the superposition thickness of the fiber prefabricated geometric models is H, when y≥H / 2, y=H / 2; when y≤-H / 2, y=-H / 2, except for... .

[0031] In this embodiment, a deformation simulation is performed on the geometric model of the fiber prefabricated body with stitching yarn by applying contact force to the contact nodes. Before performing the deformation simulation, periodic boundary conditions are applied to the nodes on the virtual fibers of the model to ensure that the displacements at both ends of each virtual fiber remain consistent. Through the deformation simulation calculation of the virtual fibers, the spatial positions of the fiber nodes are iteratively updated until the interference between the virtual fibers is completely eliminated, and finally an interference-free prefabricated body model is obtained.

[0032] In this embodiment, the prefabricated body adopts a two-layer plain weave structure, with both warp and weft yarns of 24K, a warp density of 5 threads / cm, and a weft density of 3 threads / cm. There are two layers, and each yarn is simulated using 20 virtual fibers. Regular prefabricated unit cells are stacked together, and then regular seam paths are established as the starting positions for the stitching yarns. The model of the stitching yarns and the prefabricated body is as follows: Figure 4 As shown, the stitching yarn fibers undergo staged fission as follows: Figure 8 As shown, the spatial positions of all fiber nodes are updated iteratively multiple times to ensure that all fibers satisfy the non-penetrating constraint and there is no interference problem of mutual penetration. After the iterative calculation of all virtual fiber nodes converges and the spatial positions no longer change, the fiber geometry model of the stitched prefabricated body can be obtained, as shown. Figure 9 As shown. A voxel mesh is divided within the overall space of the prefabricated body, the fiber volume fraction of each yarn unit is calculated, a unit coordinate system is established, and the material properties of the yarn units are calculated based on their fiber volume fraction. A microstructural geometric model of the stitched prefabricated body (the geometric model of the stitched fiber prefabricated body) is then established.

[0033] like Figure 2 , Figure 3 As shown, this embodiment of the invention provides a microscopic modeling device for stitched prefabricated composite materials. The device embodiment can be implemented via software, hardware, or a combination of both. From a hardware perspective, as... Figure 2 The diagram shown is a hardware architecture diagram of an electronic device for microscopic modeling of stitched prefabricated composite materials provided in an embodiment of the present invention, except for... Figure 2 In addition to the processor, memory, network interface, and non-volatile memory shown, the electronic device in the embodiment may also include other hardware, such as a forwarding chip responsible for processing packets. Taking software implementation as an example, such as... Figure 3 As shown, a device in a logical sense is formed by the CPU of the electronic device in which it is located reading the corresponding computer program from the non-volatile memory into the memory for execution.

[0034] like Figure 3 As shown, this embodiment provides a microscopic modeling device for stitched prefabricated composite materials, comprising: The first data processing module 300 is used to superimpose the geometric model of the fiber prefabricated body to be sewn and use a sine function to determine the sewing yarn path; The second data processing module 302 is used to divide the sewing yarn path into a first preset number of load steps and split the sewing yarn path into a second preset number of sewing yarn virtual fibers; wherein each load step corresponds to multiple sub-load steps. The third data processing module 304 is used to search for the first contact pair range between the virtual fibers of the sewing yarn and the geometric model of the fiber preform to be sewn in each load step. The fourth data processing module 306 is used to determine the range of the second contact pair based on the range of the first contact pair during the process of expanding the radius of the virtual fiber of the sewing yarn to the target size. The fifth data processing module 308 is used to determine the contact force of each contact pair within the range of the second contact pair. The sixth data processing module 310 is used to apply corresponding contact force to each corresponding node of the second contact pair within the range of the second contact pair in order to perform deformation simulation and obtain the geometric model of the stitched fiber preform. The seventh data processing module 312 is used to convert the geometric model of the stitched fiber preform to obtain a finite element micromechanical model; wherein, the finite element micromechanical model is used to predict the mechanical properties of the stitched preform composite material.

[0035] In one embodiment of the present invention, the seventh data processing module 312 is configured to perform the following operations: The overall space of the geometric model of the stitched fiber prefabrication is divided into multiple cubic meshes. Based on the preset unit fiber volume fraction threshold, the cubic mesh is divided into yarn units and matrix units; Among them, yarn elements and matrix elements are used to construct the finite element micromechanical model.

[0036] In one embodiment of the present invention, the contact force includes a first contact force and a second contact force; The contact force is determined by the following formula: In the formula, For the first contact force, For the second contact force, For contact stiffness, The distance between the two rod elements. It is the direction vector; The relationship between the load step and the virtual fiber radius of the stitching yarn is determined by the following formula: In the formula, For the virtual fiber radius of the sewing yarn, The preset sewing yarn radius, For radius coefficient, M is the second preset quantity, and M is the first preset quantity.

[0037] In one embodiment of the present invention, the fourth data processing module 306 is configured to perform the following operations: The contact determination between the preset fibers is set as a threshold D. In each load step, the virtual fiber rod unit number and node number of the sewing yarn are extracted sequentially, and the distance d between the centroid of each rod unit on the sewing yarn and the centroid of the virtual fiber rod unit of the sewing yarn in the geometric model of the fiber prefabricated body to be sewn is calculated. If d>D, it is assumed that there will be no contact between the sewing yarn path and the geometric model of the fiber prefabricated body to be sewn, and the search for potential contact pairs of all rod elements on the sewing yarn is completed in sequence. If d≤D, it is assumed that the stitching yarn path may come into contact with the geometric model of the fiber preform to be stitched. The corresponding two stitching yarn virtual fiber rod unit numbers are matched as a pair of possible contact pairs to determine the range of the first contact pair.

[0038] In one embodiment of the present invention, during the process of expanding the radius of the virtual fibers of the sewing yarn to a target size, the moving speed of the virtual fibers on the prefabricated body to be sewn is determined by the following formula: In the formula, The moving speed of the virtual fibers on the prefabricated body to be stitched. The distance from the virtual fiber node on the prefabricated body to be sewn to the virtual fiber of the sewing yarn is denoted as 'N'. It is a constant.

[0039] In one embodiment of the present invention, the sixth data processing module 310 is configured to perform the following operations: When the line connecting the centroids of the sewing yarns in two cross sections is not parallel to the line connecting the centroids of the virtual fibers of a single sewing yarn in the same cross section, the fiber node positions are corrected until the iterative calculation of all virtual fiber nodes of the sewing yarns converges and the spatial positions no longer change, thus obtaining the geometric model of the sewn fiber prefabricated body.

[0040] In one embodiment of the present invention, the stitching yarn path is determined by the following formula: In the formula, The coordinates represent the direction in which the yarn will be sewn. For amplitude, The coordinates are for the direction of yarn thickness.

[0041] It is understood that the structures illustrated in the embodiments of the present invention do not constitute a specific limitation on a microscopic modeling device for stitched prefabricated composite materials. In other embodiments of the present invention, a microscopic modeling device for stitched prefabricated composite materials may include more or fewer components than illustrated, or combine certain components, or split certain components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0042] The information interaction and execution process between the modules in the above-mentioned device are based on the same concept as the method embodiment of the present invention, and the specific details can be found in the description of the method embodiment of the present invention, and will not be repeated here.

[0043] This invention also provides an electronic device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a microscopic modeling method for stitched prefabricated composite materials according to any embodiment of this invention.

[0044] This invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform a microscopic modeling method for stitched prefabricated composite materials according to any embodiment of this invention.

[0045] Specifically, a system or apparatus equipped with a storage medium may be provided, on which software program code implementing the functions of any of the embodiments described above is stored, and the computer (or CPU or Mpu) of the system or apparatus may read and execute the program code stored in the storage medium.

[0046] In this case, the program code read from the storage medium can itself implement the function of any of the above embodiments, and therefore the program code and the storage medium storing the program code constitute part of the present invention.

[0047] Examples of storage media used to provide program code include floppy disks, hard disks, magneto-optical disks, optical disks (such as Cd-ROM, Cd-R, Cd-Rw, DVD-ROM, DVD-Ram, DVD-Rw, DVD+Rw), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, program code can be downloaded from a server computer via a communication network.

[0048] Furthermore, it should be clear that not only can the program code read by the computer be executed, but also the operating system or other components operating on the computer can be instructed based on the program code to perform some or all of the actual operations, thereby realizing the function of any of the embodiments described above.

[0049] Furthermore, it is understood that the program code read from the storage medium is written to the memory set in the expansion board inserted into the computer or to the memory set in the expansion module connected to the computer. Then, based on the instructions of the program code, the CPU or other device installed on the expansion board or expansion module executes some and all of the actual operations, thereby realizing the function of any of the embodiments described above.

[0050] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0051] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as ROM, RAM, magnetic disk, or optical disk.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for microscopic modeling of stitched prefabricated composite materials, characterized in that, include: The geometric models of the fiber prefabricated bodies to be sewn are superimposed, and the sewing yarn path is determined using a sine function; The sewing yarn path is divided into a first preset number of load steps, and the sewing yarn path is split into a second preset number of sewing yarn virtual fibers; wherein each load step corresponds to multiple sub-load steps; In each load step, search for the range of the first contact pair between the virtual fibers of the stitching yarn and the geometric model of the fiber preform to be stitched; During the process of expanding the radius of the virtual fiber of the sewing yarn to the target size, the range of the second contact pair is determined based on the range of the first contact pair; Within the range of the second contact pair, determine the contact force of each contact pair; Within the range of the second contact pair, a corresponding contact force is applied to each node of the contact pair to perform deformation simulation and obtain the geometric model of the stitched fiber preform. The geometric model of the stitched fiber preform is transformed to obtain a finite element micromechanical model; the finite element micromechanical model is used to predict the mechanical properties of the stitched preform composite material. The contact force includes a first contact force and a second contact force; The contact force is determined by the following formula: In the formula, For the first contact force, For the second contact force, For contact stiffness, The distance between the two rod elements. It is the direction vector; The relationship between the load step and the virtual fiber radius of the stitching yarn is determined by the following formula: In the formula, For the virtual fiber radius of the sewing yarn, The preset sewing yarn radius, For radius coefficient, M is the second preset quantity, and M is the first preset quantity.

2. The method according to claim 1, characterized in that, The process of converting the geometric model of the stitched fiber prefabricated body to obtain a finite element micromechanical model includes: The overall space of the geometric model of the stitched fiber prefabrication is divided into multiple cubic meshes. Based on the preset unit fiber volume fraction threshold, the cubic mesh is divided into yarn units and matrix units; Among them, yarn elements and matrix elements are used to construct the finite element micromechanical model.

3. The method according to claim 1, characterized in that, The search for the first contact pair range between the virtual fibers of the stitching yarn and the geometric model of the fiber prefabrication to be stitched in each load step includes: The contact determination between the preset fibers is set as a threshold D. In each load step, the virtual fiber rod unit number and node number of the sewing yarn are extracted sequentially, and the distance d between the centroid of each rod unit on the sewing yarn and the centroid of the virtual fiber rod unit of the sewing yarn in the geometric model of the fiber prefabricated body to be sewn is calculated. If d>D, it is assumed that there will be no contact between the sewing yarn path and the geometric model of the fiber prefabricated body to be sewn, and the search for potential contact pairs of all rod elements on the sewing yarn is completed in sequence. If d≤D, it is assumed that the stitching yarn path may come into contact with the geometric model of the fiber preform to be stitched. The corresponding two stitching yarn virtual fiber rod unit numbers are matched as a pair of possible contact pairs to determine the range of the first contact pair.

4. The method according to claim 1, characterized in that, During the process of expanding the radius of the virtual fibers of the stitching yarn to the target size, the moving speed of the virtual fibers on the prefabricated body to be stitched is determined by the following formula: In the formula, The moving speed of the virtual fibers on the prefabricated body to be stitched. The distance from the virtual fiber node on the prefabricated body to be sewn to the virtual fiber of the sewing yarn is denoted as 'N'. It is a constant.

5. The method according to claim 1, characterized in that, Within the range of the second contact pair, a corresponding contact force is applied to each node of the contact pair to perform deformation simulation, resulting in a geometric model of the stitched fiber prefabricated body, including: When the line connecting the centroids of the sewing yarns in two cross sections is not parallel to the line connecting the centroids of the virtual fibers of a single sewing yarn in the same cross section, the fiber node positions are corrected until the iterative calculation of all virtual fiber nodes of the sewing yarns converges and the spatial positions no longer change, thus obtaining the geometric model of the sewn fiber prefabricated body.

6. The method according to claim 1, characterized in that, The stitching yarn path is determined by the following formula: In the formula, The coordinates represent the direction in which the yarn will be sewn. For amplitude, The coordinates are for the direction of yarn thickness.

7. A microscopic modeling device for stitched prefabricated composite materials, characterized in that, For performing the method as described in any one of claims 1-6, comprising: The first data processing module is used to superimpose the geometric models of the fiber prefabricated body to be sewn and use a sine function to determine the sewing yarn path; The second data processing module is used to divide the sewing yarn path into a first preset number of load steps and split the sewing yarn path into a second preset number of sewing yarn virtual fibers; wherein each load step corresponds to multiple sub-load steps. The third data processing module is used to search for the first contact pair range between the virtual fibers of the sewing yarn and the geometric model of the fiber preform to be sewn in each load step; The fourth data processing module is used to determine the range of the second contact pair based on the range of the first contact pair during the process of expanding the radius of the virtual fiber of the sewing yarn to the target size. The fifth data processing module is used to determine the contact force of each contact pair within the range of the second contact pair. The sixth data processing module is used to apply corresponding contact force to each corresponding node of the second contact pair within the range of the second contact pair in order to perform deformation simulation and obtain the geometric model of the stitched fiber preform. The seventh data processing module is used to convert the geometric model of the stitched fiber preform into a finite element micromechanical model; the finite element micromechanical model is used to predict the mechanical properties of the stitched preform composite material.

8. An electronic device, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed in a computer, causes the computer to perform the method described in any one of claims 1-6.

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