Preparation method of large-scale structural parts with locally reinforced short carbon fiber orientation editing

Abstract

The present invention provides a method for preparing large-format structural parts with locally reinforced short carbon fiber orientation editing, which belongs to the technical field of thermoplastic composite materials. The method studies the changes in the local mechanical properties of the material, performs sensitivity analysis on the structural parts, adopts local vector analysis clustering, and uses a uniformly spaced streamline algorithm to generate a placement path for short carbon fiber thermoplastic reinforced materials. The LFT-D or SMC process is used to prepare a fiber-reinforced structure with spatial orientation, thereby solving the problem of overall structural failure caused by insufficient local load-bearing capacity of the structural parts.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoplastic composite materials, and specifically discloses a method for preparing a large-scale structural component by locally reinforcing the component through orientation editing of short carbon fibers. Background Art

[0002] Carbon fiber reinforced thermoplastic composites are widely used in aerospace, new energy, sports, and medical fields. Thermoplastic composites with a fiber aspect ratio of more than 100 not only have high functional integration, but also have high mechanical and plastic properties. They have huge advantages in economy, effectiveness, and processing efficiency. They have been widely promoted and applied in drones, automobiles, new energy, sports equipment and other fields.

[0003] Like conventional load-bearing components, one-piece molding or modular assembly of multiple smaller one-piece components is the current conventional method for preparing thermoplastic fiber reinforced composite structural parts. The thermoplastic fiber reinforced composite structural parts prepared by conventional methods are made of isotropic homogeneous materials throughout the structural parts, and the load-bearing capacity of each part is the same. However, in actual use, depending on factors such as location and working conditions, each part of the structural part often bears loads of different sizes and directions, which results in the structural part only partially reaching the yield limit, but causing the entire part to fail and be scrapped. Currently, the failure of thermoplastic fiber reinforced composite structural parts is almost entirely due to local failure. This problem can only be solved by replacing the entire structural part or locally reinforcing it. Conventional local reinforcement methods include physical thickening or external reinforcement, which results in a huge waste of material. There is no precedent for research on changing the local mechanical properties of the material.

[0004] Finally, currently thermoplastic fiber reinforced composite structural parts are all produced in batches. There are few manufacturers of special customized structural parts, the cycle is long, and the process development cost is high, which cannot meet the differentiated market needs. Summary of the Invention

[0005] The present invention provides a method for preparing a large-format structural member with locally reinforced short carbon fiber orientation editing, which solves at least one of the following technical problems:

[0006] 1. The problem of overall failure caused by insufficient local bearing capacity of structural parts;

[0007] 2. The problem of being unable to quickly customize production according to the specific working conditions of structural parts.

[0008] The method for preparing the above-mentioned short carbon fiber orientation-edited locally reinforced large-format structural member comprises the following steps:

[0009] S1, obtain the dimensional data of the target structural part and the stress data under specific working conditions, build a model based on the dimensional data and stress data of the target structural part, complete the meshing of the target structural part, and output the file;

[0010] S2, importing the file output in step S1 into CAE analysis software to obtain the orientation angle of each unit in the target structural part;

[0011] S3, using CAE analysis software to analyze the orientation angles of each unit in the target structural part, and calculate the ideal placement path streamline diagram;

[0012] S4, using CAD software to draw a specific laying path diagram according to the trend of the laying path streamline diagram;

[0013] S5, according to the specific placement path diagram, short carbon fiber thermoplastic reinforced material is used to lay out the structural component preform;

[0014] S6, compression molding the structural component preform to obtain a target structural component.

[0015] In step S1 , the stress data of the target structural component under specific working conditions include stress point, stress surface, stress direction, stress cycle, stress duration, ultimate load form and ultimate load magnitude.

[0016] In step S1, the dimensional data and force data of the target structural part are obtained through CAD software, the dimensional data and force data are imported into the Abaqus software for modeling, and the meshing of the target structural part is completed through the triangular unit mesh.

[0017] If the target structural part is an assembly part, step S1 further obtains assembly data of the target structural part through CAD software, and imports the size data, force data, and assembly data into abaqus software for modeling.

[0018] In step S2, the file output from step S1 is imported into CAE analysis software. The maximum force and maximum stiffness of the target structural component are set in the CAE analysis software, the material properties and fiber display of the target structural component are defined, the sensitivity analysis calculation form is defined, and the minimum compliance method is used to calculate the minimum strain energy of the fiber of each unit in the target structural component from an energy perspective. The orientation angle of each unit in the target structural component is obtained by derivation of the fiber orientation sensitivity analysis.

[0019] Step S3 includes the following steps:

[0020] t1, the orientation angles of all units in the target structural part are used as the initial vector field, and a clustering algorithm is used to obtain a candidate angle set of the initial vector field. The optimal orientation angle in the candidate angle set is filtered and the unit corresponding to the optimal orientation angle is removed to avoid the local optimal problem;

[0021] t2, the orientation angles corresponding to the units retained after filtering and the coordinates of the unit center in the plane are combined to form a data set. The units with similar positions, orientation angles and amplitudes in the data set are clustered using a secondary clustering algorithm to form clusters. The orientation angles corresponding to the units in each cluster are averaged to ensure that the directions of the units in the same cluster are parallel. All clusters are integrated to form a cluster vector field;

[0022] t3. The cluster vector field is processed using the uniformly spaced streamline algorithm. The cells in the cluster vector field are used as path seed points. Based on the relationship between the magnitudes of the local stresses in the target structural parts, a stress-first strategy is adopted to sort the path seed points in descending order. The path seed point corresponding to the maximum stress is used as the starting point of the placement path to generate an ideal placement path streamline diagram.

[0023] In step S5, the short carbon fiber thermoplastic reinforced material is prepared by LFT-D technology or SMC technology.

[0024] In step S5, the short carbon fiber thermoplastic reinforced material molten sheet prepared by LFT-D technology or the short carbon fiber thermoplastic reinforced material sheet prepared by SMC technology is deposited in parallel and without gaps on a constant temperature placement platform according to a specific placement path diagram, and fixed placement of the structural component preform is achieved through multiple tracking splicing.

[0025] In step S6, the laid-out structural component preform is transferred to an isothermal molding machine for compression molding. The structural component preform is kept in a molten state by the isothermal molding machine, and a preset pressure is applied. The structural component preform is then cooled at a preset temperature drop rate until the temperature of the structural component preform drops to room temperature, thereby obtaining the target structural component.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention studies how to modify the local mechanical properties of materials, performs sensitivity analysis on structural components, and uses local vector analysis and clustering to generate a uniformly spaced streamline algorithm to create a placement path for short carbon fiber thermoplastic reinforcements. LFT-D or SMC processes are then used to fabricate spatially oriented fiber-reinforced structures, addressing the problem of overall structural failure caused by insufficient local load-bearing capacity.

[0028] 2. Suitable for small-batch rapid customized production of structural parts with special working requirements. The structural parts have strong design freedom, high processing efficiency, short cycle, high process reliability, high market adaptability and low overall processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 Flowchart of the method for preparing locally reinforced large-format structural parts for short carbon fiber orientation editing;

[0031] Figure 2 is the size data and stress data of the L beam;

[0032] Figure 3 This is the mesh division diagram of the L beam;

[0033] Figure 4 is the fiber orientation prediction diagram of the L beam;

[0034] Figure 5 This is the streamline diagram of the laying path of the L beam;

[0035] Figure 6 The specific laying path diagram of the L beam;

[0036] Figure 7 This is the finished picture of the L beam. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing large-format structural parts with local reinforcement edited by short carbon fiber orientation, which is guided by the actual structural part size and stress conditions of the project and serves as a reference for special path planning in the later stage; the CAE analysis software calculates the orientation vector field under the conditions of maximum force and maximum stiffness, and displays the fiber orientation status under load, so that the areas of the structural parts with greater stress can obtain enhanced bearing capacity through orientation regulation; through secondary clustering analysis and streamline algorithm, high stress areas are prioritized for planning, ensuring the bearing capacity of the structural parts and scientific, smooth and efficient path planning; then, the LFT-D or SMC process is used to realize the production of oriented sheets of short carbon fiber thermoplastic reinforced materials, ensuring the fiber content, orientation degree and fiber length; laying the sheets on a constant temperature laying platform can give play to the advantages of material design, improve the efficiency and accuracy of laying, and ensure the effect of the finished part; finally, an isothermal molding process is performed to form customized high-strength target structural parts, giving play to the advantages of the local fluidity of the material, fully ensuring the molding effect and target strength of the structural parts, and achieving high online production efficiency.

[0040] like Figure 1 As shown, the specific steps include the following.

[0041] S1, obtain the dimensional data of the target structural part and the force data under specific working conditions, model the target structural part based on the dimensional data and force data, complete the meshing of the target structural part, and output the file.

[0042] In step S1 , the stress data of the target structural component under specific working conditions include stress point, stress surface, stress direction, stress cycle, stress duration, ultimate load form and ultimate load magnitude.

[0043] In step S1, the dimensional data and force data of the target structural part are obtained through CAD software, the dimensional data and force data are imported into the Abaqus software for modeling, and the meshing of the target structural part is completed through the triangular unit mesh.

[0044] If the target structural part is an assembly part, step S1 further obtains assembly data of the target structural part through CAD software, and imports the size data, force data, and assembly data into abaqus software for modeling.

[0045] S2, importing the file output in step S1 into CAE analysis software to obtain the orientation angle of each unit in the target structural part. The specific steps include:

[0046] In the CAE analysis software, the maximum force and maximum stiffness of the target structural component are set, the material properties and fiber display of the target structural component are defined, and the sensitivity analysis calculation form is defined. The minimum compliance method is used to calculate the minimum fiber strain energy of each unit in the target structural component from an energy perspective. The orientation angle of each unit in the target structural component is obtained by derivation of the fiber orientation sensitivity analysis.

[0047] S3: Use CAE analysis software to analyze the orientation angles of each unit in the target structural part and calculate the ideal placement path streamline diagram. The specific steps include:

[0048] t1, the orientation angles of all units in the target structural part are used as the initial vector field, and a clustering algorithm is used to obtain a candidate angle set of the initial vector field. The optimal orientation angle in the candidate angle set is filtered and the unit corresponding to the optimal orientation angle is removed to avoid the local optimal problem;

[0049] t2, the orientation angles corresponding to the units retained after filtering and the coordinates of the unit center in the plane are combined to form a data set. The units with similar positions, orientation angles and amplitudes in the data set are clustered using a secondary clustering algorithm to form clusters. The orientation angles corresponding to the units in each cluster are averaged to ensure that the directions of the units in the same cluster are parallel. All clusters are integrated to form a cluster vector field;

[0050] t3. The cluster vector field is processed using the uniformly spaced streamline algorithm. The cells in the cluster vector field are used as path seed points. Based on the relationship between the magnitudes of the local stresses in the target structural parts, a stress-first strategy is adopted to sort the path seed points in descending order. The path seed point corresponding to the maximum stress is used as the starting point of the placement path to generate an ideal placement path streamline diagram.

[0051] S4, using CAD software to draw a specific laying path diagram according to the trend of the laying path streamline diagram.

[0052] S5, according to the specific placement path diagram, short carbon fiber thermoplastic reinforced materials are used to lay the preforms of the structural parts. Specifically, the molten sheet of short carbon fiber thermoplastic reinforced materials prepared by LFT-D technology or the sheet of short carbon fiber thermoplastic reinforced materials prepared by SMC technology are deposited in parallel and without gaps on a constant temperature placement platform according to the specific placement path diagram, and the fixed placement of the structural part preform is achieved through multiple tracking splicing. LFT-D technology or SMC technology can set the fiber content, fiber length, sheet width and thickness in advance to quickly produce short carbon fiber thermoplastic reinforced materials.

[0053] S6, transferring the laid-out structural component preform to an isothermal molding machine for molding, maintaining the structural component preform in a molten state through the isothermal molding machine, applying a preset pressure, and then cooling the structural component preform at a preset temperature drop rate until the temperature of the structural component preform drops to room temperature, thereby obtaining the target structural component.

[0054] Example 2

[0055] This embodiment uses an L-beam as a target structural component to specifically illustrate a method for preparing a large-scale structural component with local reinforcement by editing the orientation of short carbon fibers.

[0056] S1: If Figure 2 As shown, the dimensional data and force data of the L beam are obtained by CAD software. The dimensional data include the overall length m1=200mm, the overall width m2=200mm, a groove is opened on the right side, the groove length n1=100mm, and the groove width n2=100mm. The force data include three fixed points a, b, and c set at equal intervals on the upper edge, and a force point d set at the right end of the groove, with a force of 10N. The dimensional data and force data are imported into the abaqus software for modeling. The mesh division of the L beam is realized by the triangular unit mesh. The mesh size can be set according to the length of the short carbon fiber, the display clarity, and the computing speed. In this embodiment, the mesh size is set to 5. Figure 3 As shown, the final output file is in the ".inp" format.

[0057] S2, open the edited SFCANA version of CAE analysis software in the Linux system environment, import the file output in step S1 into the CAE analysis software, set the basic information such as unit display, model boundary and display fiber orientation. According to the steps of setting "initial fiber orientation → input material parameters → set boundary conditions → establish analysis model → perform optimization settings → calculate virtual strain → start optimization", the orientation optimization prediction is performed, where the initial fiber orientation angle is set to 0°, the material parameters are set to orthogonal materials, the boundary conditions are set to 16-23, the transverse and longitudinal displacements are 0, and the force is applied at 39 points with a point force of 10N. The optimization settings set the number of operations to 250, the speed to 0.1, and the area to 0.5, such as Figure 4 shown.

[0058] S3, same as in Example 1, generates a streamline diagram of the laying path under ideal conditions, such as Figure 5 shown.

[0059] S4, as in Example 1, using CAD software to draw a specific laying path diagram according to the trend of the laying path streamline diagram, such as Figure 6 shown.

[0060] S5, set the fiber content to 10%, the fiber length to 0.5mm, and the sheet size to 1cm×0.1cm (width×thickness) in advance, and use LFT-D technology to prepare short carbon fiber thermoplastic reinforced material molten sheets of different lengths according to the specific placement path diagram, and then fix them on a constant temperature placement platform at 230°C.

[0061] S6, transfer the laid-up preform of the structural component to an isothermal molding machine for molding. The isothermal molding machine keeps the preform of the structural component in a molten state at 230-250°C. Under the principle of maintaining minimal influence on the fiber orientation, a pressure of 2mp is applied to give full play to the advantages of the fluidity and filling properties of the short carbon fiber thermoplastic reinforced material, reduce the porosity of the structural component and improve the strength. Then, the temperature of the structural component is reduced at a temperature drop rate of 5-10°C / H, which reduces the warping of the structural component and improves the reliability of the structural component, thereby obtaining a locally reinforced structural component, such as Figure 7 shown.

[0062] Example 3

[0063] This embodiment uses an L-beam as a target structural component to specifically illustrate a method for preparing a large-scale structural component with local reinforcement by editing the orientation of short carbon fibers.

[0064] The difference between this embodiment and embodiment 2 is that in step S5, the fiber content is set to 10%, the fiber length is set to 0.5 mm, and the sheet size is set to 1 cm × 0.1 cm (width × thickness) in advance, and short carbon fiber thermoplastic reinforced material sheets of different lengths are prepared according to a specific placement path diagram using SMC technology, and then fixedly placed on a constant temperature placement platform at room temperature.

[0065] In step S6, the laid-up structural component preform is transferred to an isothermal molding machine for molding. The structural component preform is heated to 230-250°C by the isothermal molding machine to maintain a molten state. Under the principle of maintaining minimal influence on fiber orientation, a pressure of 2mp is applied to give full play to the advantages of the fluidity and filling properties of the short carbon fiber thermoplastic reinforced material, reduce the porosity of the structural component and increase the strength. Then, the temperature of the structural component is reduced at a temperature drop rate of 5-10°C / H, the warping of the structural component is reduced, the reliability of the structural component is improved, and a locally reinforced structural component is obtained.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a large-format structural member with locally reinforced short carbon fiber orientation editing, characterized in that: The steps include: S1, obtain the dimensional data of the target structural part and the force data under specific working conditions, build a model based on the dimensional data and force data of the target structural part, complete the meshing of the target structural part, and output the file; S2, importing the file output in step S1 into CAE analysis software, setting the maximum force and maximum stiffness of the target structural component in the CAE analysis software, defining the material properties and fiber display of the target structural component, defining the sensitivity analysis calculation form, using the minimum compliance method, calculating the minimum strain energy of the fiber of each unit in the target structural component from the energy perspective, and obtaining the orientation angle of each unit in the target structural component by derivation of the fiber orientation sensitivity analysis; S3, using CAE analysis software to analyze the orientation angles of each unit in the target structural part, and calculate the ideal placement path streamline diagram, including the following steps: t1, the orientation angles of all units in the target structural part are used as the initial vector field, and a clustering algorithm is used to obtain a candidate angle set of the initial vector field. The optimal orientation angle in the candidate angle set is filtered and the unit corresponding to the optimal orientation angle is removed to avoid the local optimal problem; t2, the orientation angles corresponding to the units retained after filtering and the coordinates of the unit center in the plane are combined to form a data set. The units with similar positions, orientation angles and amplitudes in the data set are clustered using a secondary clustering algorithm to form clusters. The orientation angles corresponding to the units in each cluster are averaged to ensure that the directions of the units in the same cluster are parallel. All clusters are integrated to form a cluster vector field; t3, using the uniformly spaced streamline algorithm to process the clustered vector field, using the cells in the clustered vector field as path seed points. Based on the relationship between the magnitudes of the local stresses in the target structural component, a stress-first strategy is adopted to sort the path seed points in descending order. The path seed point corresponding to the maximum stress is used as the starting point of the placement path to generate a placement path streamline diagram under ideal conditions; S4, using CAD software to draw a specific laying path diagram according to the trend of the laying path streamline diagram; S5, according to the specific placement path diagram, short carbon fiber thermoplastic reinforced material is used to lay out the structural component preform; S6, compression molding the structural component preform to obtain a target structural component.

2. The method for preparing a large-format structural member with locally reinforced short carbon fiber orientation editing according to claim 1, characterized in that: In step S1 , the stress data of the target structural component under specific working conditions include stress point, stress surface, stress direction, stress cycle, stress duration, ultimate load form and ultimate load magnitude.

3. The method for preparing a large-format structural member with locally reinforced short carbon fiber orientation editing according to claim 2, characterized in that: In step S1, the dimensional data and force data of the target structural part are obtained through CAD software, the dimensional data and force data are imported into the Abaqus software for modeling, and the meshing of the target structural part is completed through the triangular unit mesh.

4. The method for preparing a large-format structural member with locally reinforced short carbon fiber orientation editing according to claim 3, characterized in that: If the target structural part is an assembly part, step S1 further obtains assembly data of the target structural part through CAD software, and imports the size data, force data, and assembly data into abaqus software for modeling.

5. The method for preparing a large-format structural member with locally reinforced short carbon fiber orientation editing according to claim 1, characterized in that: In step S5, the short carbon fiber thermoplastic reinforced material is prepared by LFT-D technology or SMC technology.

6. The method for preparing a large-format structural member with locally reinforced short carbon fiber orientation editing according to claim 5, characterized in that: In step S5, the short carbon fiber thermoplastic reinforced material molten sheet prepared by LFT-D technology or the short carbon fiber thermoplastic reinforced material sheet prepared by SMC technology is deposited in parallel and without gaps on a constant temperature placement platform according to a specific placement path diagram, and fixed placement of the structural component preform is achieved through multiple tracking splicing.

7. The method for preparing a large-format structural member partially reinforced by short carbon fiber orientation editing according to claim 6, characterized in that: In step S6, the laid-out structural component preform is transferred to an isothermal molding machine for compression molding. The structural component preform is kept in a molten state by the isothermal molding machine, and a preset pressure is applied. The structural component preform is then cooled at a preset temperature drop rate until the temperature of the structural component preform drops to room temperature, thereby obtaining the target structural component.

Images