Method for predicting behavior of carbon fiber composite material in consideration of fiber draping effect

Abstract

The present invention relates to a method for predicting the behavior of carbon fiber composite material having a multi-lamina stacking structure, comprising the steps of: preparing a carbon fiber composite material having a multi-lamina stacking structure; modeling the carbon fiber composite material; inputting information to a carbon fiber composite material model; and interpreting the behavior of the carbon fiber composite material model.

Description

A method for predicting the behavior of carbon fiber composites considering the fiber draping effect.

[0001] This invention was made possible with the support of the Academic-Research Cooperation Platform Construction Pilot Project [Project Unique Number: 1711200460, Project Number: RS-2023-00304729, Research Project Name: Academic-Research Cooperation Platform for Eco-Friendly Advanced Mobility Materials and Components] supported by the Science and Technology Job Promotion Agency Foundation of the Ministry of Science and ICT.

[0002] The present invention relates to a method for predicting the behavior of a carbon fiber composite material considering the fiber draping effect, and more particularly, to a method for predicting the behavior of a carbon fiber composite material having a multiple laminar stacking structure by modeling the shape of a carbon fiber composite material having multiple geometric curvatures and analyzing the behavior of the carbon fiber composite material by inputting information for each mesh of the carbon fiber composite model.

[0003] Cross-reference to related applications

[0004] This application claims priority to Republic of Korea Patent Application No. 10-2024-0028642, filed February 28, 2024, and Republic of Korea Patent Application No. 10-2024-0118961, filed September 3, 2024, the entire contents of which are incorporated herein by reference.

[0005] Carbon fiber composites are important engineering materials widely used in engineering fields and have broad development prospects.

[0006] For example, fan blades, one of the products utilizing carbon fiber composite materials, are widely used in marine and aerospace applications because they can provide excellent mechanical properties while maintaining a lightweight design.

[0007] However, these blades have different airfoil shapes in each cross-section in the longitudinal direction, have a twist angle of a certain angle, so that the thickness of each section continuously changes, and have multiple curvatures, so that the direction of the fibers included in the composite material continuously changes according to the geometric characteristics of the structure.

[0008] Because of this, there is a problem that it is very difficult to predict the behavior of the final designed blade, as it must be filled by laminating anisotropic composite materials whose mechanical properties vary greatly depending on the direction of the fibers.

[0009] In addition, even if the laminated design of the blade is completed, changes in fiber direction that occur during the manufacturing process depending on the geometric characteristics of the blade have a significant impact on the structural performance of the composite blade.

[0010] Therefore, a method for predicting blade behavior that takes into account the direction of fibers is needed for blade structures with multiple geometric curvatures.

[0011] [Prior Art Literature]

[0012] [Patent Document]

[0013] (Patent Document 1) Korean Patent Application Publication No. 10-2001-0049923

[0014] For example, as illustrated in FIG. 8, the patent document discloses a method for modeling the orientation angle distribution of a carbon fiber composite material using image processing, but this method models only the distribution of the orientation angle of the carbon fiber composite material itself, and from this, it is impossible to predict the change in fiber direction of the composite material according to geometric characteristics.

[0015] As mentioned above, the performance of a structure utilizing carbon fiber composites is closely related to the direction of the fibers, so predicting the fiber orientation in the molding of carbon fiber composites is very important.

[0016] In particular, fiber draping analysis of composite materials is essential to accurately predict fiber path distortion during the lamination process and manufacturing of blades.

[0017] Therefore, the present invention aims to provide a simulation capable of accurately predicting the fiber path distortion of carbon fiber composites and a method for predicting the behavior of carbon fiber composites.

[0018] The present invention can provide a method for predicting the behavior of a carbon fiber composite material having a plurality of laminar laminate structures, characterized by including the steps of: preparing a carbon fiber composite material having a plurality of laminar laminate structures; modeling the carbon fiber composite material; inputting information into the carbon fiber composite material model; and analyzing the behavior of the carbon fiber composite material model.

[0019] In addition, the step of modeling the carbon fiber composite material of the present invention may include a step of modeling the profiles of the upper surface and the lower surface of the carbon fiber composite material, respectively, to generate an upper mesh model and a lower mesh model; and a step of generating an intermediate layer mesh model, which is a target of behavior prediction, from the upper mesh model and the lower mesh model.

[0020] In addition, the step of inputting information into the carbon fiber composite material model of the present invention may include a step of inputting thickness information of the carbon fiber composite material for each mesh of the intermediate layer mesh model; a step of inputting layer number information of the carbon fiber composite material for each mesh of the intermediate layer mesh model; and a step of inputting fiber draping information of the carbon fiber composite material for each mesh of the intermediate layer mesh model.

[0021] Additionally, the step of analyzing the behavior of the carbon fiber composite material model of the present invention may include a step of analyzing the behavior of the carbon fiber composite material for each mesh of the intermediate layer mesh model.

[0022] In addition, the thickness information of the carbon fiber composite material of the present invention can be calculated by calculating the distance between each node of the upper mesh and each node of the lower mesh.

[0023] In addition, information on the number of layers of the carbon fiber composite material of the present invention can be calculated from the average thickness of each layer of the carbon fiber composite material and the nominal thickness of the laminar layer.

[0024] In addition, the laminated shape of the carbon fiber composite material of the present invention can be calculated through the result of combining the thickness distribution and nominal thickness of each layer.

[0025] In addition, the fiber draping information of the carbon fiber composite material of the present invention can be obtained by calculating the covariant tangent vector from the normal vector of each intermediate layer mesh.

[0026] In addition, the behavior of the carbon fiber composite material of the present invention may include at least one of mechanical behavior and thermal behavior.

[0027] In addition, the carbon fiber composite material of the present invention may include at least one of a propeller blade and a fan blade.

[0028] The present invention constructs a finite element mesh from upper and lower models of a composite material having a geometrically multi-curvature shape, and designs a shape code and a laminated structure and a laminated structure according to the same based on the thickness of the composite material and the thickness distribution of the blade.

[0029] In addition, the present invention can predict the distortion of fiber orientation of a composite material system by calculating the covariant tangent vector at the center of each element mesh having multiple curvatures.

[0030] In addition, the present invention can analyze the behavior of a composite material system by introducing the structural performance of a distorted anisotropic composite material into each element according to the distortion of the calculated fiber orientation.

[0031] In addition, the present invention can accurately analyze fiber orientation distortion with high feasibility compared to an actually manufactured product, thereby manufacturing a blade with improved prediction of mechanical and thermal behavior.

[0032] Figure 1 schematically illustrates a step of modeling by configuring finite mesh elements according to a composite material shape according to one embodiment of the present invention.

[0033] FIG. 2 schematically illustrates a step of modeling an intermediate layer mesh model from an upper mesh model and a lower mesh model and inputting thickness information for each mesh according to one embodiment of the present invention.

[0034] FIG. 3 schematically illustrates a step of inputting layer shape and layer number information into an intermediate layer mesh model according to one embodiment of the present invention.

[0035] Figure 4 schematically illustrates a smoothing step of an intermediate layer mesh model according to one embodiment of the present invention.

[0036] FIG. 5 schematically illustrates a step of calculating fiber draping information from an intermediate layer mesh model according to one embodiment of the present invention.

[0037] Figure 6 is a graph showing the analysis of the fiber draping effect of a composite material according to one embodiment of the present invention.

[0038] Figure 7 is a graph analyzing the behavior of a composite material considering the fiber draping effect of the composite material according to one embodiment of the present invention.

[0039] Figure 8 schematically illustrates a simulation diagram of fiber orientation of a conventional composite material.

[0040] Hereinafter, a method for predicting the behavior of a carbon fiber composite material having a multiple laminar stacking structure according to an embodiment of the present invention will be described through a preferred embodiment of the present invention based on the attached drawings.

[0041] Before explaining, when it is said that a part "includes" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless specifically stated otherwise.

[0042] In addition, in various embodiments, components having the same configuration are representatively described in one embodiment using the same symbols, and in other embodiments, only different components are described.

[0043] In addition, although embodiments of the present invention have been described with reference to the attached drawings, these are described for illustrative purposes, and the technical idea of ​​the present invention and its configuration and application are not limited thereby.

[0044] According to one embodiment of the present invention, the present invention proposes a method for predicting the behavior of a carbon fiber composite material by modeling a carbon fiber composite material having a plurality of laminar stacked structures, inputting information into the carbon fiber composite material model, and analyzing the behavior of the carbon fiber composite material model from the information.

[0045] Therefore, by designing a laminated structure based on shell finite element mesh modeling of a composite intermediate layer with multiple geometric curvatures, the mesh-based composite laminate shape code boundary can be perfectly matched with the actual manufacturing process, while directly considering the curvature of each design element mesh, significantly reducing the calculation time and providing a highly feasible fiber draping analysis method for actual manufactured products.

[0046] More specific details of the present invention will be explained through the specific examples below.

[0047] Figure 1 schematically illustrates a step of modeling by configuring finite mesh elements according to a composite material shape according to one embodiment of the present invention.

[0048] As illustrated in Fig. 1, starting from a three-dimensional shape model of a blade structure made of carbon fiber composite material, a cross-sectional profile can be generated through consistent discretization applied to both the upper and lower surfaces.

[0049] These upper and lower surface profiles are important for generating high-quality shell finite element meshes during the design phase, and the middle shell mesh, which is the target of blade structural behavior prediction, can be obtained through interpolation between the upper and lower mesh models generated previously.

[0050] FIG. 2 schematically illustrates a step of modeling an intermediate layer mesh model from an upper mesh model and a lower mesh model and inputting thickness information for each mesh according to one embodiment of the present invention.

[0051] As shown in Fig. 2, the thickness distribution of the blade is converted into the nodal thickness of the intermediate layer mesh, and the thickness of each node can be calculated by calculating the distance between the corresponding nodal coordinates of the upper surface mesh and the lower surface mesh.

[0052] FIG. 3 schematically illustrates a step of inputting layer shape and layer number information into an intermediate layer mesh model according to one embodiment of the present invention.

[0053] As shown in Fig. 3, the average thickness (h) of the shell elements e ) and the nominal thickness of the laminar ply (h 0 ply ) can be used to calculate the stacking shape and number of stacks of shell elements.

[0054] Specifically, when calculating the number of layers of shell elements, in order to prevent residual stress and deformation occurring during composite material manufacturing, each lamina is assumed to be symmetrically layered, and the calculated number of layers can be adjusted for symmetrical layering.

[0055] Figure 4 schematically illustrates a smoothing step of an intermediate layer mesh model according to one embodiment of the present invention.

[0056] As illustrated in FIG. 4, one embodiment of the present invention may include a smoothing step for actual composite material manufacturing, for example, if there are discontinuous angular boundaries within a group of elements, problems may arise when cutting the composite laminae layers during the manufacturing process.

[0057] Therefore, the continuous smooth manufacturing shape code (i) has an equivalent thickness (h i ) can be created based on the modified field (Φ i ) and the shell mesh, a smooth-shaped model can be completed.

[0058] FIG. 5 schematically illustrates a step of calculating fiber draping information from an intermediate layer mesh model according to one embodiment of the present invention.

[0059] As illustrated in Fig. 5, fiber draping analysis can be performed using a mid-layer shell finite element mesh to evaluate fiber draping behavior within a composite blade structure.

[0060] Specifically, the geometric curvature can be represented by a normal vector at the center of each mesh, and by utilizing this normal vector, the covariant tangent vector can be calculated and projected onto the in-plane surface of the shell element.

[0061] Additionally, the distortion of fiber orientation can be determined by calculating the angle (Draping shear angle) formed between the fiber draping system coordinates and the reference material system coordinates.

[0062] Figure 6 is a graph showing the analysis of the fiber draping effect of a composite material according to one embodiment of the present invention.

[0063] For example, without considering fiber draping analysis for each mesh of a composite model, the shell finite element mesh is nothing more than a layered structure defined by the thickness distribution of the blade.

[0064] However, as illustrated in Fig. 6, considering the fiber draping analysis, the material structural performance of each shell element changes depending on the fiber draping direction, which can have the effect of accurately considering the influence of fiber draping on the behavior prediction and analysis process of the composite blade structure.

[0065] Figure 7 is a graph analyzing the behavior of a composite material considering the fiber draping effect of the composite material according to one embodiment of the present invention.

[0066] Specifically, Fig. 7 shows the simulation results according to the presence or absence of fiber draping analysis of the composite blade and the thermal deformation test results of the actually manufactured composite blade.

[0067] As shown in Fig. 7, the simulation results including fiber draping analysis are consistent with the thermal deformation results of the actually manufactured composite blade, whereas the simulation results without fiber draping analysis do not accurately predict the thermal deformation due to the process of the laminated composite fan blade.

[0068] Therefore, it can be confirmed that the simulation through fiber draping analysis according to one embodiment of the present invention can accurately predict the mechanical and thermal behavior, including thermal deformation, of the composite material.

[0069] By referring to the above description, those skilled in the art to which the present invention pertains will be able to understand that the present invention can be implemented in other specific forms without changing the technical idea or essential characteristics thereof.

[0070] Therefore, it should be understood that the embodiments described so far are exemplary in all respects and are not intended to limit the present invention to the embodiments described above, and the scope of the present invention is indicated by the claims described below rather than the detailed description described above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present invention.

[0071] According to a method for predicting the behavior of a carbon fiber composite material having a plurality of laminar laminate structures according to embodiments of the present invention, a finite element mesh can be constructed from upper and lower models of a composite material having a geometrically multi-curvature shape, and a shape code and laminate structure and a laminate structure according to the same can be designed based on the thickness of the composite material and the thickness distribution of the blade.

Claims

1. A step of preparing a carbon fiber composite material having a multiple laminar stacking structure; A step of modeling the above carbon fiber composite material; A step of inputting information into the above carbon fiber composite material model; and A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized by including a step of analyzing the behavior of the above carbon fiber composite material model.

2. In paragraph 1, The steps of modeling the above carbon fiber composite material are: A step of creating an upper mesh model and a lower mesh model by modeling the profiles of the upper surface and the lower surface of the carbon fiber composite material, respectively; and A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized by comprising the step of generating an intermediate layer mesh model that is a target of behavior prediction from the upper mesh model and the lower mesh model.

3. In paragraph 2, The step of entering information into the above carbon fiber composite material model is: A step of inputting thickness information of the carbon fiber composite for each mesh of the intermediate layer mesh model; A step of inputting information on the number of layers of the carbon fiber composite material for each mesh of the intermediate layer mesh model; and A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized by including a step of inputting fiber draping information of the carbon fiber composite material for each mesh of the intermediate layer mesh model.

4. In paragraph 2, The steps for analyzing the behavior of the above carbon fiber composite material model are: A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized in that it includes a step of analyzing the behavior of the carbon fiber composite material for each mesh of the intermediate layer mesh model.

5. In paragraph 3, The thickness information of the above carbon fiber composite material is: A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized in that the distance between each node of the upper mesh and each node of the lower mesh is calculated.

6. In paragraph 3, The information on the number of layers of the above carbon fiber composite material is: A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized in that the thickness is calculated from the average thickness of each layer of the carbon fiber composite material and the nominal thickness of the laminar layer.

7. In paragraph 3, The fiber draping information of the above carbon fiber composite material is: A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized in that the covariant tangent vector is calculated from the normal vector of each of the intermediate layer meshes.

8. In paragraph 4, The behavior of the above carbon fiber composite material is: A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar stacked structures, characterized in that it includes at least one of mechanical behavior and thermal behavior.

9. In paragraph 1, The above carbon fiber composite material is, A method for predicting the behavior of a carbon fiber composite material having a plurality of laminar laminate structures, characterized in that the carbon fiber composite material includes at least one of a propeller blade and a fan blade.

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