A method for modeling a lost layer structure based on process simulation

Abstract

This invention relates to a method for modeling delaminated structures based on process simulation, belonging to the field of composite material structure modeling and numerical simulation technology. The method first establishes a two-dimensional ply finite element model, obtaining the cross-sectional geometry of the ply after compaction by simulating the forming process of the ply under compaction pressure load. Then, node data is extracted from the simulation results, and penetration detection and reconstruction processing are performed on the ply interface nodes to eliminate gaps and penetrations between ply layers. Based on this, the geometric features of the delaminated region are extracted, the ply boundaries are optimized, and continuous geometric boundaries are formed through curve reconstruction. Finally, a finite element input file is generated based on the optimized two-dimensional geometric model, and a three-dimensional solid model is generated by stretching along a direction perpendicular to the two-dimensional cross-section for subsequent finite element analysis. This invention can establish a delaminated model that more closely resembles the actual structure based on process simulation results, improving the accuracy of composite material structure simulation.

Description

Technical Field

[0001] This invention relates to the field of composite material structure modeling and numerical simulation technology, and in particular to a method for modeling layer-loss structures based on process simulation. Background Technology

[0002] Fiber-reinforced resin matrix composite structures, especially carbon fiber-reinforced resin matrix composite structures, possess advantages such as high specific strength, high specific stiffness, good fatigue resistance, and strong designability, and have been widely used in aerospace, energy equipment, high-end manufacturing, and rail transportation. In composite structure design, to achieve structural weight reduction, thickness transition, and optimization of local load-bearing capacity, the delamination design method is often used. This involves gradually terminating some layers in specific areas of the structure, thereby forming a laminated structure that transitions from thick to thin regions.

[0003] However, delaminated structures do not perfectly maintain their ideal geometry during actual manufacturing. Layups typically consist of multiple layers of fiber prepreg laid sequentially according to a predetermined order, undergoing compaction deformation under conditions such as mold constraints, vacuum bag pressure, compaction pressure, and curing pressure. For composite structures with delaminated layers, stepped transitions, or complex mold surfaces, differences in layup length, local termination positions, and uneven compaction deformation can lead to geometric features such as resin-rich areas, local voids, layup adhesion, interlaminar penetration, or boundary misalignment. These manufacturing-induced geometric morphologies directly affect the stress distribution, interlaminar damage prediction, and strength assessment results in subsequent finite element analysis of the structure.

[0004] Existing finite element modeling methods for composite material delaminated structures mostly employ idealized geometric modeling, directly establishing ply boundaries and thickness transition regions based on design dimensions. While this method is relatively simple, it typically fails to reflect the true cross-sectional morphology of the ply under mold and compaction pressure, and also struggles to describe issues such as localized adhesion, voids, penetration, and boundary deformation caused by process compaction in the delaminated regions. Therefore, the finite element model based on ideal geometry may deviate from the actual molded composite material structure, thus affecting the accuracy of subsequent simulation analyses.

[0005] To more realistically reflect the geometric evolution of composite plywood structures during manufacturing, process simulation methods can be used to simulate the forming process of the ply under the action of mold and compaction pressure, and to obtain the cross-sectional geometry, nodal displacement, and interlayer contact state of the ply after compaction. However, process simulation results are usually in the form of finite element result files or nodal data, and cannot be directly used as subsequent three-dimensional solid structure analysis models. Especially when converting process simulation results into structural finite element models, directly extracting the nodes of each ply and reconstructing the geometric boundaries can easily lead to problems such as non-shared nodes between adjacent plies, interface discontinuities, local geometric gaps, ply penetration, and unclosed end boundaries of plywood, which in turn affect the mesh generation quality and computational stability of the model.

[0006] Therefore, there is an urgent need to propose a modeling method for lost-layer structures based on process simulation. Based on obtaining the cross-sectional geometry after ply compaction, the ply interface nodes are subjected to penetration judgment and reconstruction processing. The local interlayer bonding area and point overlap area are supplemented and closed by nodes. Furthermore, the geometric features of the lost-layer area are extracted, the boundary is optimized and the curve is reconstructed, thereby generating a finite element model of the lost-layer structure that is closer to the actual forming state and can be used for subsequent finite element analysis. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems in existing composite material plywood modeling processes, such as difficulty in reflecting actual ply deformation during the manufacturing process, inaccurate handling of interlayer geometric relationships, easy occurrence of ply penetration or voids, and deviations between the model and the actual forming state due to direct modeling based on ideal geometry. This invention provides a plywood structure modeling method based on process simulation. This method obtains the cross-sectional geometry of the plywood after compaction under the action of a mold and compaction pressure load through process simulation. Based on this, it performs penetration determination, interface reconstruction, node supplementation, boundary closure, and curve reconstruction on the ply interface nodes, thereby obtaining a plywood structure finite element model that more closely approximates the actual forming state and can be used for subsequent finite element analysis.

[0008] The objective of this invention can be achieved through the following technical solutions: This invention provides a method for modeling layer-loss structures based on process simulation, comprising the following steps: S1: Based on the layup design information of the fiber-reinforced resin matrix composite structure (experiment), each layup is modeled as a shell element, and a mold is set under the layup to establish a two-dimensional layup finite element model; S2: Based on the two-dimensional ply finite element model established in step S1, a compaction pressure load is applied to the surface of the top ply. At the same time, contact relationships are established between adjacent plies and between the ply and the mold. Process simulation calculations are performed to obtain the cross-sectional geometry, nodal displacement, and interlayer contact state of the ply after compaction, and the process simulation results are obtained. S3: Extract the node information and unit connection relationship from the process simulation results obtained in step S2, distinguish the upper surface nodes and lower surface nodes of each ply according to the ply number, and perform penetration judgment and reconstruction processing on the ply interface nodes so that adjacent plies share the same set of nodes at the contact interface to eliminate gaps and penetration between plies. S4: After penetration determination and reconstruction in step S3, geometric features are extracted from the lost layer area, and the ply boundary is geometrically simplified and optimized. Then, the upper and lower surfaces of the ply are reconstructed using the curve reconstruction method to form a continuous two-dimensional geometric boundary, thus obtaining the optimized two-dimensional geometric model. S5: The optimized two-dimensional geometric model is stretched along the width direction of the fiber-reinforced resin matrix composite structure (test piece) to generate a three-dimensional solid model, and the three-dimensional solid model is meshed to obtain the finite element model of the layered structure.

[0009] Further, in step S1, the two-dimensional ply finite element model is established using a script parameterization method. Each ply is modeled as an independent rectangular shell element Part, and is assigned ply material properties, ply thickness, material orientation, and mesh information respectively. The ply material properties include density, elastic parameters, and Poisson's ratio.

[0010] Furthermore, in step S1, the mold is introduced in the form of an analytical rigid body and assembled and positioned with each layer. The mold is used to define the forming contour during the compaction process of the layers.

[0011] Furthermore, in step S2, the compaction pressure load is a uniformly distributed pressure load applied to the surface of the uppermost ply, while displacement constraints are applied to the ply boundary or mold to simulate the constrained forming state of the ply during the compaction process.

[0012] Furthermore, in step S2, contact relationships are established between adjacent plies and between plies and the mold. The normal contact of the contact relationship adopts the hard contact model, and the tangential contact adopts the Coulomb friction model.

[0013] Furthermore, in step S3, the process of extracting the node information and unit connection relationship from the process simulation results obtained in step S2 includes: after the process simulation calculation is completed, exporting the process simulation result file as an input file format, and extracting the node information and unit connection relationship of each layer from the input file format.

[0014] Furthermore, the node information includes node number and node coordinates, and the unit connection relationship includes unit number and node number constituting the unit.

[0015] Furthermore, the process simulation result file is an ODB file, and the input file format is an INP file format; by re-importing the ODB file into the modeling environment and exporting it as an INP file, the extraction of each layer node information and the unit connection relationship is realized.

[0016] Furthermore, in step S3, the process of performing penetration determination and reconstruction processing on the ply interface nodes includes: S3.1: Based on the upper and lower surface nodes of each ply, compare the node projection positions and boundary lengths of the contact interfaces of adjacent plies along the ply cross-section direction to determine whether there is a geometric overlap area between adjacent plies; S3.2: When the local boundary of the upper ply exceeds the projection range of the lower ply, the area exceeding the projection range is determined as a potential penetration area; S3.3: Only the areas where potential penetration is determined are processed by interface node reconstruction, so that the contact interface between adjacent plies retains only one set of common nodes, and the upper surface nodes of the lower ply are replaced with the lower surface nodes of the corresponding upper ply, thereby avoiding interlayer penetration. S3.4: Perform node supplementation and closure treatment on the local interlayer bonding area and the point overlap area to eliminate geometric gaps; wherein, the interlayer bonding area is the area where non-adjacent plies are bonded or in contact in a local area due to the termination of the intermediate ply at the drop position.

[0017] Furthermore, the node supplementation includes the following process: in the local interlayer bonding area and the point overlap area, supplementary nodes are generated according to the endpoints of adjacent ply boundaries, bonding boundary positions and missing ply end positions, and the supplementary nodes are added to the boundary node sequence of the corresponding ply, so that the locally disconnected ply boundaries are geometrically connected.

[0018] Furthermore, the closure process includes the following steps: sorting the ply boundary nodes after node supplementation, and sequentially connecting the upper surface nodes, lower surface nodes and end boundary nodes of the ply to form a closed two-dimensional cross-sectional profile of the ply, so as to ensure the interlayer transition continuity of the local interlayer bonding area and the point overlap area.

[0019] Further, in step S4, the geometric features of the lost layer region include the vertices of the lost layer triangle region, the boundary points of the ply end, the node sequence of the upper surface of the ply, the node sequence of the lower surface of the ply, and the ply boundary length.

[0020] Furthermore, in step S4, the geometric simplification and optimization process includes retaining feature points of the lost-layer triangular region, deleting redundant nodes, and deleting approximately collinear nodes.

[0021] Furthermore, in step S4, the curve reconstruction method includes a spline curve reconstruction method, which connects the retained nodes through spline curves to form a continuous two-dimensional geometric boundary.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1) The layer-drop structure modeling method based on process simulation provided by the present invention simulates the compaction process of the layup under the action of mold and compaction pressure load through a two-dimensional layup finite element model. It can obtain the cross-sectional geometry, nodal displacement and interlayer contact state of the layup after compaction, so that the subsequently established layer-drop structure finite element model is closer to the actual forming state.

[0023] 2) This invention extracts node information and element connection relationships from process simulation result files and input files, thereby realizing the conversion of process simulation results into structural finite element models, and providing a data foundation for establishing layered structure finite element models based on actual process deformation results.

[0024] 3) By performing penetration determination and reconstruction processing on the ply interface nodes, the present invention enables adjacent ply layers to share the same set of nodes at the contact interface, which can effectively eliminate the interlayer gaps and ply penetration problems that may occur when directly reconstructing the model based on the process simulation results, and improve the geometric continuity of the model and the quality of mesh generation.

[0025] 4) This invention performs node supplementation and closure processing on the local interlayer bonding area and the point overlap area, which can ensure the boundary integrity of the missing layer end and the local bonding area, and avoid the failure of 3D solid model generation or the degradation of mesh generation quality due to unclosed boundaries.

[0026] 5) By extracting the geometric features of the lost layer region, simplifying and optimizing the boundary, and reconstructing the curve, this invention can reduce redundant nodes while retaining the key lost layer geometric features, making the two-dimensional geometric boundary more continuous and smooth, which is beneficial for subsequent three-dimensional solid extrusion modeling and finite element mesh generation.

[0027] 6) This invention is applicable to modeling fiber-reinforced resin matrix composite structures with missing layers, stepped transition structures, and complex laminated structures with local layup termination characteristics, and can provide a more realistic finite element model for subsequent structural strength analysis, damage analysis, and reliability assessment. Attached Figure Description

[0028] Figure 1 This is a schematic diagram comparing the gap and penetration treatment effects before and after the reconstruction of the layup interface in the layer loss structure modeling method based on process simulation in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of a two-dimensional ply finite element model established by script parameterization in an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram comparing the finite element model of the layer-loss structure based on process simulation with the image of the test piece in an embodiment of the present invention. Figure 3 Image (a) is an image of the actual delaminated structure test specimen. Figure 3 (b) is a three-dimensional solid geometric model generated by stretching along the width direction of the test piece based on the optimized two-dimensional geometric boundary. Figure 3 (c) is for Figure 3 (b) shows the layered structure finite element model obtained after the three-dimensional solid geometric model is meshed. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0032] It should be noted that the layer loss structure modeling method based on process simulation in this invention can be adjusted according to actual needs, and the specific implementation steps and parameter settings may differ.

[0033] This invention provides an automated parametric finite element modeling method for composite material delamination design, belonging to the field of composite material structure modeling and numerical simulation technology. The method first establishes a two-dimensional ply finite element model, obtaining the cross-sectional geometry of the ply after compaction by simulating the forming process of the ply under compaction pressure load. Then, node data is extracted from the simulation results, and penetration detection and reconstruction processing are performed on the ply interface nodes to eliminate gaps and penetrations between ply layers. Based on this, the geometric features of the delamination region are extracted, the ply boundaries are optimized, and continuous geometric boundaries are formed through curve reconstruction. Finally, the two-dimensional geometric model is stretched along the thickness direction to generate a three-dimensional solid model for subsequent finite element analysis. This invention can establish a delamination model that more closely resembles the actual structure based on process simulation results, improving the accuracy of composite material structure simulation.

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1 This embodiment provides a method for modeling layer-loss structures based on process simulation, including the following steps: S1: Based on the layup design information of the fiber-reinforced resin matrix composite structure, each layup is modeled as a shell element, and a mold is set under the layup to establish a two-dimensional layup finite element model.

[0036] Specifically, based on the layup design information of the fiber-reinforced resin matrix composite structure, a two-dimensional layup finite element model is established using a script-parametric approach. Each layup is modeled as an independent rectangular shell element (Part), and is assigned material properties, layup thickness, material orientation, and mesh information. The layup material properties include density, elastic parameters, and Poisson's ratio. Subsequently, a mold is imported as an analytical rigid body and assembled and positioned with each layup. The mold is used to define the forming contour during the layup compaction process.

[0037] S2: Based on the two-dimensional ply finite element model established in step S1, a compaction pressure load is applied to the surface of the uppermost ply. At the same time, contact relationships are established between adjacent plies and between the ply and the mold. Process simulation calculations are performed to obtain the cross-sectional geometry, nodal displacement, and interlayer contact state of the ply after compaction.

[0038] Specifically, the compaction pressure load is a uniformly distributed pressure load applied to the surface of the uppermost ply, while displacement constraints are applied to the ply boundaries or the die to simulate the constrained forming state of the ply during the compaction process. Contact relationships are established between adjacent plies and between the ply and the die. The normal contact uses a hard contact model, and the tangential contact uses a Coulomb friction model. By establishing analysis steps and progressively applying the compaction pressure load, the ply compaction process simulation calculation is completed, obtaining the cross-sectional geometry, nodal displacements, and interlayer contact state after ply compaction, and generating a process simulation result file to obtain the process simulation results.

[0039] S3: Extract the node information and unit connection relationship from the process simulation results obtained in step S2, distinguish the upper and lower surface nodes of each ply according to the ply number, and perform penetration judgment and reconstruction processing on the ply interface nodes so that adjacent plies share the same set of nodes at the contact interface to eliminate gaps and penetration between plies.

[0040] Specifically, after the process simulation calculation is completed, the process simulation result file is exported as an input file format, and the node information and element connection relationships of each ply are extracted from the input file format. The process simulation result file is an ODB file, and the input file format is an INP file format. By re-importing the ODB file into the modeling environment and exporting it as an INP file, the extraction of node information and element connection relationships of each ply is achieved. Further, the node information and element connection relationships in the INP file are read using a data processing script, which includes MATLAB scripts, Python scripts, or other script programs capable of reading INP files. In this embodiment, a MATLAB data processing script is preferably used to read the node information and element connection relationships in the INP file. The node information includes node number and node coordinates, and the element connection relationship includes element number and the node number constituting the element.

[0041] The process of performing penetration detection and reconstruction on ply interface nodes includes: S3.1: Based on the upper and lower surface nodes of each ply, compare the node projection positions and boundary lengths of the contact interfaces of adjacent plies along the ply cross-section direction to determine whether there is a geometric overlap area between adjacent plies; S3.2: When the local boundary of the upper ply exceeds the projection range of the lower ply, the area exceeding the projection range is determined as a potential penetration area; S3.3: Only the areas where potential penetration is determined are processed by interface node reconstruction, so that the contact interface between adjacent plies retains only one set of common nodes, and the upper surface nodes of the lower ply are replaced with the lower surface nodes of the corresponding upper ply, thereby avoiding interlayer penetration. S3.4: Perform node supplementation and closure treatment on the local interlayer bonding area and the point overlap area to eliminate geometric gaps; wherein, the interlayer bonding area is the area where non-adjacent plies are bonded or in contact in a local area due to the termination of the intermediate ply at the drop position.

[0042] The node supplementation includes the following process: in the local interlayer bonding area and the point overlap area, supplementary nodes are generated according to the endpoints of adjacent ply boundaries, bonding boundary positions and missing ply end positions, and the supplementary nodes are added to the boundary node sequence of the corresponding ply, so that the locally disconnected ply boundaries are geometrically connected.

[0043] The closure process includes the following steps: sorting the ply boundary nodes after node supplementation, and sequentially connecting the upper surface nodes, lower surface nodes and end boundary nodes of the ply to form a closed two-dimensional cross-sectional profile of the ply, so as to ensure the interlayer transition continuity of the local interlayer bonding area and the point overlap area.

[0044] S4: After penetration determination and reconstruction in step S3, geometric features are extracted from the lost layer area, and the ply boundary is geometrically simplified and optimized. Then, the upper and lower surfaces of the ply are reconstructed using the curve reconstruction method to form a continuous two-dimensional geometric boundary, thus obtaining the optimized two-dimensional geometric model.

[0045] Specifically, the geometric features of the lost-layer region include the vertices of the lost-layer triangle region, the boundary points at the ply ends, the node sequence on the upper surface of the ply, the node sequence on the lower surface of the ply, and the ply boundary length. The geometric simplification and optimization process includes retaining the feature points of the lost-layer triangle region, deleting redundant nodes, and deleting approximately collinear nodes. The curve reconstruction method includes a spline curve reconstruction method, which connects the retained nodes through spline curves to form a continuous two-dimensional geometric boundary.

[0046] S5: The optimized two-dimensional geometric model is stretched along the width direction of the test piece to generate a three-dimensional solid model, and the three-dimensional solid model is meshed to obtain the layered structure finite element model.

[0047] Specifically, a two-dimensional geometric model is reconstructed based on the continuous two-dimensional geometric boundary obtained in step S4, and the two-dimensional geometric model is stretched along the width direction of the test piece to generate a three-dimensional solid geometric model. Subsequently, the three-dimensional solid geometric model is meshed to obtain a layered structure finite element model that can be used for finite element analysis.

[0048] Example 2 This embodiment, based on Embodiment 1, provides a specific application example of a composite material delamination structure modeling method based on process simulation. The object used in this embodiment is a fiber-reinforced resin matrix composite tenon-shaped structure test specimen, which has overall stepped transition characteristics and local delamination characteristics. Figure 3 (a) shows an actual photograph of the tenon structure test piece, which shows that its shape has obvious thickness transition and layer loss area characteristics.

[0049] The steps correspond to S1 to S5 in Example 1, and the specific settings are as follows: S1: Based on the ply design information of the fiber-reinforced resin matrix composite tenon structure test specimen, each ply is modeled as a shell element, and a mold is set below the ply to establish a two-dimensional ply finite element model. Specifically, the initial geometric model of each ply is established using a Python script parametric method. Each ply is modeled as an independent shell element (Part) and assembled and positioned with the analytical rigid body mold. Figure 2 As shown, this embodiment generates a two-dimensional layup finite element model for process simulation.

[0050] S2: Based on the two-dimensional ply finite element model established in step S1, apply a compaction pressure load to the surface of the top ply, and establish contact relationships between adjacent plies and between the ply and the mold. Perform process simulation calculations to obtain the cross-sectional geometry, nodal displacements, and interlayer contact states of the ply after compaction, and output the process simulation result file.

[0051] S3: Extract the node information and unit connection relationships from the process simulation results obtained in step S2. Distinguish the upper and lower surface nodes of each ply according to the ply number. Then, perform penetration detection, interface reconstruction, node supplementation, and boundary closure processing on the ply interface nodes according to the method in Example 1 to eliminate gaps and penetrations between ply layers. For example... Figure 1 As shown, after processing, the interfaces of adjacent layers can form a continuous bonding state.

[0052] S4: After processing in step S3, geometric features are extracted from the lost layer region, and the ply boundary is geometrically simplified and optimized. Then, the upper and lower surfaces of the ply are reconstructed using spline curves to obtain the optimized two-dimensional geometric model.

[0053] S5: The optimized two-dimensional geometric model obtained in step S4 is stretched along the width direction of the test piece to generate a three-dimensional solid geometric model, and the three-dimensional solid geometric model is meshed to obtain a layered structure finite element model. For example... Figure 3 As shown, Figure 3 (a) is a photograph of the actual tenon structure test piece. Figure 3 (b) is a three-dimensional solid geometric model generated based on the optimized two-dimensional geometric model. Figure 3 (c) is for Figure 3 The finite element mesh model (layerless structure finite element model) obtained after dividing the three-dimensional solid geometric model shown in (b) into solid meshes.

[0054] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] The embodiments of the method of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any parameter changes or calculation simplifications made based on the principle of the technical solution of the present invention, as long as they meet the purpose of the invention and do not deviate from the principle and concept of the method for modeling layer-loss structures based on process simulation, shall fall within the protection scope of the present invention.

[0056] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for modeling a missing layer structure based on process simulation, characterized in that, Includes the following steps: S1: Based on the layup design information of the fiber-reinforced resin matrix composite structure, each layup is modeled as a shell element, and a mold is set under the layup to establish a two-dimensional layup finite element model; S2: Based on the two-dimensional ply finite element model established in step S1, a compaction pressure load is applied to the surface of the top ply. At the same time, contact relationships are established between adjacent plies and between the ply and the mold. Process simulation calculations are performed to obtain the cross-sectional geometry, nodal displacement, and interlayer contact state of the ply after compaction, and the process simulation results are obtained. S3: Extract the node information and unit connection relationship from the process simulation results obtained in step S2, distinguish the upper surface nodes and lower surface nodes of each ply according to the ply number, and perform penetration judgment and reconstruction processing on the ply interface nodes so that adjacent plies share the same set of nodes at the contact interface to eliminate gaps and penetration between plies. S4: After penetration determination and reconstruction in step S3, geometric features are extracted from the lost layer area, and the ply boundary is geometrically simplified and optimized. Then, the upper and lower surfaces of the ply are reconstructed using the curve reconstruction method to form a continuous two-dimensional geometric boundary, thus obtaining the optimized two-dimensional geometric model. S5: The optimized two-dimensional geometric model is stretched along the width direction of the fiber-reinforced resin matrix composite structure to generate a three-dimensional solid model, and the three-dimensional solid model is meshed to obtain the finite element model of the layered structure.

2. The process simulation based modeling method of a missing layer structure according to claim 1, wherein, In step S1, the two-dimensional ply finite element model is established using a script parameterization method. Each ply is modeled as an independent rectangular shell element Part, and is assigned ply material properties, ply thickness, material orientation, and mesh information. The ply material properties include density, elastic parameters, and Poisson's ratio.

3. The process simulation based modeling method of missing layer structure according to claim 1, wherein, In step S1, the mold is imported in the form of an analytical rigid body and assembled and positioned with each layer. The mold is used to define the forming contour during the compaction process of the layers.

4. The process simulation based modeling method of missing layer structure according to claim 1, wherein, In step S2, the compaction pressure load is a uniformly distributed pressure load applied to the surface of the uppermost ply, while displacement constraints are applied to the ply boundary or mold to simulate the constrained forming state of the ply during the compaction process.

5. The process simulation based modeling method of missing layer structure according to claim 1, wherein, In step S2, contact relationships are established between adjacent plies and between plies and the mold. The normal contact of the contact relationship adopts the hard contact model, and the tangential contact adopts the Coulomb friction model.

6. The method for modeling layer-loss structures based on process simulation according to claim 1, characterized in that, Step S3, the process of extracting node information and unit connection relationships from the process simulation results obtained in step S2, includes: After the process simulation calculation is completed, the process simulation result file is exported as an input file format, and the node information and unit connection relationship of each layer are extracted from the input file format. The node information includes the node number and node coordinates; The unit connection relationship includes the unit number and the node number that constitutes the unit.

7. The process simulation based modeling method of a missing layer structure according to claim 6, wherein, The process simulation result file is an ODB file, and the input file format is an INP file format. By re-importing the ODB file into the modeling environment and exporting it as an INP file, the information of each layup node and the connection relationship of the unit can be extracted.

8. The process simulation based modeling method of missing layer structure according to claim 1, wherein, Step S3, the process of performing penetration determination and reconstruction on the ply interface nodes includes: S3.1: Based on the upper and lower surface nodes of each ply, compare the node projection positions and boundary lengths of the contact interfaces of adjacent plies along the ply cross-section direction to determine whether there is a geometric overlap area between adjacent plies; S3.2: When the local boundary of the upper ply exceeds the projection range of the lower ply, the area exceeding the projection range is determined as a potential penetration area; S3.3: Only the areas where potential penetration is determined are processed by interface node reconstruction, so that the contact interface between adjacent plies retains only one set of common nodes, and the upper surface nodes of the lower ply are replaced with the lower surface nodes of the corresponding upper ply, thereby avoiding interlayer penetration. S3.4: Perform node supplementation and closure treatment on the local interlayer bonding area and the point overlap area to eliminate geometric gaps; wherein, the interlayer bonding area is the area where non-adjacent plies are bonded or in contact in a local area due to the termination of the intermediate ply at the drop position.

9. The process simulation based modeling method of a missing layer structure according to claim 8, wherein, The node supplementation includes the following process: in the local interlayer bonding area and the point overlap area, supplementary nodes are generated according to the endpoints of adjacent ply boundaries, bonding boundary positions and missing ply end positions, and the supplementary nodes are added to the boundary node sequence of the corresponding ply, so that the locally disconnected ply boundaries are geometrically connected.

10. The process simulation based modeling method of a missing layer structure according to claim 8, wherein, The closure process includes the following steps: sorting the ply boundary nodes after node supplementation, and sequentially connecting the upper surface nodes, lower surface nodes and end boundary nodes of the ply to form a closed two-dimensional cross-sectional profile of the ply, so as to ensure the continuity of interlayer transition in the local interlayer bonding area and the point overlap area.

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