CFRP equipment compartment composite material part structure optimization design method

Abstract

The invention belongs to the technical field of railway vehicle material optimization, and particularly relates to a CFRP equipment compartment composite material part structure optimization design method, systematic three-level optimization design is achieved, a tandem type three-level optimization process of free size optimization, laying layer shape finishing, size optimization and laying layer sequence optimization is achieved, the process logic is strict, and the design efficiency is high. The method has the advantages that the material distribution concept design and the micro manufacturing detail design are organically combined, the limitation of a single optimization stage is overcome, and the whole-process optimization from the concept to the product is realized.

Description

Technical Field

[0001] This invention relates to the field of rail vehicle material optimization technology, specifically to a structural optimization design method for CFRP equipment compartment composite material components. Background Technology

[0002] With the continuous development of lightweight technology for rail transit equipment, carbon fiber composites have been widely used in large components such as equipment compartments due to their advantages such as high specific strength, high specific modulus, and strong designability. However, the performance of CFRP structures is highly dependent on their layup design, including layup angle, layup thickness, layup shape, and layup sequence.

[0003] Traditional composite material design methods rely heavily on engineers' experience, employing trial-and-error layup design. This approach is not only time-consuming and costly but also fails to fully realize the material's performance potential, often resulting in structural redundancy or insufficient performance. While existing optimization techniques can assist design to some extent, they still have significant limitations: for example, free-size optimization can find the optimal material distribution, but the result is often discontinuous material distribution and complex, unusual layup shapes that cannot be directly used for manufacturing; while simple size optimization or layup sequence optimization, without scientific conceptual design guidance, has limited optimization potential and struggles to achieve significant weight reduction.

[0004] Therefore, there is an urgent need in this field for a systematic, manufacturing-oriented CFRP equipment compartment structure optimization design method that can seamlessly integrate idealized topological concepts with manufacturable manufacturing details, achieve significant weight reduction of the equipment compartment structure while ensuring structural stiffness, strength and other performance requirements, and ensure that the design scheme has good manufacturability. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] Therefore, the purpose of this invention is to provide a structural optimization design method for CFRP equipment cabin composite material components, realizing a systematic three-level optimization design, which is a series of three-level optimization processes: free size optimization → layup shape trimming → size optimization → layup sequence optimization. The process is logically rigorous and progressively advances, organically combining the macroscopic material distribution concept design with the microscopic manufacturing detail design, overcoming the limitations of a single optimization stage, and realizing full-process optimization from concept to product.

[0007] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution: A method for optimizing the structural design of CFRP (composite material reinforced plastic) equipment compartment components includes the following steps: S1: Free dimension optimization, using one or more ply angle groups of each composite material component in the equipment compartment as design variables, and minimizing structural flexibility as the objective function, performs free dimension optimization to obtain the discrete thickness distribution and initial ply shape of each ply angle group; S2: Ply shape trimming, geometrically trimming the initial ply shape obtained in S1 to meet manufacturability requirements, and obtaining the trimmed ply shape; S3: Size optimization, using the modified ply shape obtained in S2 as the design variable, minimizing the equipment compartment's overall mass as the objective function, and using the maximum displacement of the overall structure of the equipment compartment as the constraint, size optimization is performed to determine the final ply thickness of each modified ply shape. S4: Ply sequence optimization. Using the ply shape with the final ply thickness determined in S3 as the design variable, the objective function is to minimize the structural flexibility, and the maximum displacement of the overall structure of the equipment compartment is used as the constraint condition to optimize the ply sequence and determine the optimal ply sequence for each ply.

[0008] As a preferred embodiment of the CFRP equipment compartment composite material component structure optimization design method of the present invention, wherein: in step S1, the composite material components of the equipment compartment include sandwich panel structure and laminated plate structure; For sandwich panel structures, the free dimension optimization is performed only on one or more ply angle groups of the inner panel; For laminated slab structures, the free dimension optimization is performed on all ply angle groups.

[0009] As a preferred embodiment of the CFRP equipment compartment composite material component structural optimization design method described in this invention, wherein: step S2, geometrical trimming of the initial layup shape includes: For initial ply shapes of different ply angle groups with strong geometric similarity, ply shape sharing processing is performed; Unfold the layers of a three-dimensional curved surface into a two-dimensional planar graphic.

[0010] As a preferred embodiment of the CFRP equipment compartment composite material component structural optimization design method described in this invention, the layup shape commonality treatment specifically includes: If the second and third ply shapes generated after optimization of different ply angle groups have geometric similarity, then the different ply angle groups can share the adjusted second and third ply shapes.

[0011] As a preferred embodiment of the CFRP equipment compartment composite material component structure optimization design method described in this invention, in step S3, the size optimization process decomposes each ply angle group into a single ply and constrains the thickness of the single ply to be an integer multiple of the thickness of a single layer of carbon fiber fabric, wherein the thickness of the single layer of carbon fiber fabric is 0.2 mm.

[0012] As a preferred embodiment of the CFRP equipment cabin composite material component structure optimization design method of the present invention, wherein in steps S1 and S3, the maximum displacement of the overall structure of the constrained equipment cabin is less than or equal to 5mm.

[0013] As a preferred embodiment of the CFRP equipment compartment composite material component structure optimization design method of the present invention, in step S2, for components whose free-size optimized layup shapes are not significantly different and have strong geometric similarity, their original geometric shapes are used as the only modified layup shapes.

[0014] As a preferred embodiment of the CFRP equipment compartment composite material component structural optimization design method described in this invention, after step S4 of the layup sequence optimization, the method further includes: S5: Performance verification. Finite element analysis is performed on the overall structure of the equipment compartment after optimization by S1-S4 to verify whether its stiffness and strength under the target working conditions meet the preset requirements. The stiffness is evaluated by the maximum displacement value of the equipment compartment, and the strength is evaluated by the damage factor of the composite material layer and the equivalent stress of the metal connector.

[0015] According to any one of the above-mentioned methods for optimizing the structure of composite material parts for CFRP equipment compartments, the overall mass of the equipment compartment is reduced by at least 10% compared to the original design after the three-level optimization of S1-S4, and the maximum displacement value is reduced by at least 20%.

[0016] A rail vehicle equipment compartment includes at least one composite material component selected from the compartment's skirt, floor, curved beam, crossbeam, and longitudinal beam, which is optimized and manufactured using the method described in any one of the above descriptions.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: A systematic three-level optimization design is achieved, which is a series of three-level optimization processes: free size optimization → layup shape adjustment → size optimization → layup sequence optimization. The process is logically rigorous and progressive, organically combining macro-level material distribution concept design with micro-level manufacturing detail design, overcoming the limitations of a single optimization stage, and realizing full-process optimization from concept to product. Through the above system optimization, under the premise of meeting strict stiffness requirements (such as maximum displacement ≤ 5mm), the overall weight of the equipment compartment structure is reduced by more than 10%, while the maximum displacement is reduced by more than 20%. It has outstanding effectiveness in weight reduction and structural stiffness improvement, and outstanding economic and performance benefits. The "layout shape trimming" step modifies the manufacturability of the free-size optimization results, including layout shape commonality processing and three-dimensional surface unfolding into two-dimensional plane, etc., to improve the engineering practicality of the optimization results. The generated layout shape is regular and continuous, which can be directly used to guide production cutting and avoid the dilemma that the ideal design cannot be processed. By using parametric modeling and optimization algorithms, engineers are freed from tedious trial-and-error work, shortening the design cycle. In particular, the common processing of ply shapes reduces the number of independent ply shapes, simplifies subsequent ply manuals and process documents, and reduces the complexity of production management. By embedding performance verification steps into the optimization process, the stiffness and strength of the final optimized solution are fully verified, ensuring the safety and reliability of the design results and forming a complete "design-optimization-verification" closed loop, thereby reducing product development risks. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a block diagram of the method of the present invention; Figure 2 This is a diagram showing the thickness distribution of the skirt panel in this invention; Figure 3 This is a geometric model diagram of the ply shape of the present invention; Figure 4 This is a geometric model diagram of the ply shape after modification according to the present invention; Figure 5 This is a thickness distribution diagram of the base plate of the present invention; Figure 6 This is a geometric model diagram of the ply shape of the present invention; Figure 7 This is a geometric model diagram of the ply shape after modification according to the present invention; Figure 8 This is a diagram showing the thickness distribution of the curved beam in this invention; Figure 9 This is a geometric model diagram of the ply shape of the present invention; Figure 10 This is a geometric model diagram of the ply shape after modification according to the present invention. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0023] This invention provides a method for optimizing the structural design of CFRP (Chemical Reinforced Plastic) equipment compartment composite material components. Please refer to [link / reference]. Figure 1-10 It includes the following steps: S1: Free dimension optimization, using one or more ply angle groups of each composite material component in the equipment compartment as design variables, and minimizing structural flexibility as the objective function, performs free dimension optimization to obtain the discrete thickness distribution and initial ply shape of each ply angle group; S2: Ply shape trimming, geometrically trimming the initial ply shape obtained in S1 to meet manufacturability requirements, and obtaining the trimmed ply shape; S3: Size optimization, using the modified ply shape obtained in S2 as the design variable, minimizing the equipment compartment's overall mass as the objective function, and using the maximum displacement of the overall structure of the equipment compartment as the constraint, size optimization is performed to determine the final ply thickness of each modified ply shape. S4: Ply sequence optimization. Using the ply shape with the final ply thickness determined in S3 as the design variable, the objective function is to minimize the structural flexibility, and the maximum displacement of the overall structure of the equipment compartment is used as the constraint condition to optimize the ply sequence and determine the optimal ply sequence for each ply. In step S1, the composite material components of the equipment compartment include sandwich panel structures and laminated plate structures; For sandwich panel structures, the free dimension optimization is performed only on one or more ply angle groups of the inner panel; For laminated plate structures, the free dimension optimization is performed on all ply angle groups; Step S2, geometric trimming of the initial ply shape includes: For initial ply shapes of different ply angle groups with strong geometric similarity, ply shape sharing processing is performed; Unfold the layers of a three-dimensional curved surface into a two-dimensional planar graphic; The specific process for sharing ply shapes is as follows: If the second and third ply shapes generated after optimization of different ply angle groups have geometric similarity, then the different ply angle groups shall share the adjusted second and third ply shapes. In step S3, the size optimization process decomposes each ply angle group into a single ply and constrains the thickness of the single ply to be an integer multiple of the thickness of the single layer of carbon fiber fabric, which is 0.2 mm. In steps S1 and S3, the maximum displacement of the overall structure of the restraint equipment cabin is less than or equal to 5 mm; In step S2, for components whose ply shapes are not significantly different after free-size optimization and have strong geometric similarity, their original geometric shape is used as the only modified ply shape. After optimizing the layup sequence in step S4, the following steps are also included: S5: Performance verification. Finite element analysis is performed on the overall structure of the equipment compartment after optimization by S1-S4 to verify whether its stiffness and strength under the target working conditions meet the preset requirements. The stiffness is evaluated by the maximum displacement value of the equipment compartment, and the strength is evaluated by the damage factor of the composite material layer and the equivalent stress of the metal connector. After the three-level optimization of S1-S4, the overall mass of the equipment compartment is reduced by at least 10% compared to the original design, and the maximum displacement value is reduced by at least 20%.

[0024] Example: (1) Skirt Because the parts of the freely dimensionally optimized component have varying thicknesses, it's impossible to simultaneously guarantee smoothness on both sides of the structure. As the component in contact with the outside, the outer side of the skirt panel must be smooth to meet the train's aerodynamic requirements. The skirt panel is also composed of a foam core carbon fiber sandwich panel, and the inner side of the outer panel is connected to the foam, requiring a smooth contact surface as well. Therefore, free-dimensional optimization of the skirt panel can only be performed on its inner panel, with four superlayers (0°, 45°, 90°, and -45°) used as design variables. The optimized skirt panel thickness distribution is as follows: Figure 2 As shown in the figure, this stage is only a conceptual design stage, so specific thickness values ​​are not displayed. As can be seen from the figure, different areas of the skirt panel have different thicknesses after free-size optimization, fully utilizing the advantages of the material. OptiStruct generates four layup shapes for each superlayer at each angle. However, due to the extremely low continuity of the fourth shape, which significantly increases operational difficulty and production costs, only three layup shapes are applied. Specific layup shapes are as follows: Figure 3 As shown in the figure, the 0-degree ply has been thickened at the connection with the curved beam and in the vertical center area. The ply shape at ±45 degrees is a star-shaped structure, and the ply shape at 90 degrees is an inverted Y-shaped structure. Because the ply shape optimized for free dimensions exhibits material discontinuities and geometric irregularities, it significantly increases production difficulty. This section modifies the ply shape to meet manufacturability requirements. The modified ply shape is as follows: Figure 4 As shown; (2) Base plate Similar to the skirt panels, the base plate is also a foam core carbon fiber sandwich panel structure and is in contact with the train's exterior. The smoothness of its surface affects the train's aerodynamic performance; therefore, only the four superlayers of its inner panel were optimized for free-size design. The optimized thickness distribution of each layer is as follows: Figure 5 As shown in the figure, the differences in thickness between the total ply thickness and the 90 ply thickness are obvious in different areas, while the thickness differences between the 0 degree and ±45 degree ply thicknesses are not significant. After free-size optimization, three discrete layup shapes were generated, such as... Figure 6 As shown in the figure, the connection between the base plate and the crossbeam has a relatively large thickness. The ply shapes at 0 degrees, ±45 degrees, and 90 degrees are highly similar, therefore only the ply shape at one angle needs to be adjusted. The shapes of the second and third plies after modification are as follows: Figure 7 As shown in the figure, this ply shape is shared by four ply angles and will be used as a design variable for subsequent dimensional and ply sequence optimization. The figure shows that the material of the third ply shape is mainly concentrated near the longitudinal beams; (3) Curved beam The curved beam is a carbon fiber laminate structure composed of four superlayers at 0 degrees, 45 degrees, -45 degrees, and 90 degrees. This section will optimize the free-size of these four superlayers. The optimized ply thickness at each angle is as follows: Figure 8 As shown in the figure, the contact surface between the curved beam and the skirt plate, as well as its opposite side, has a larger thickness, while the side surface of the curved beam has a smaller thickness. The shape of each angle of the ply after free-size optimization is as follows Figure 9 As shown in the figure, each ply at a specific angle generates three ply shapes. The first ply shape represents the complete structural shape of the curved beam, while the second and third ply shapes represent the shapes of the main load-bearing areas. As can be seen from the figure, the second and third shapes of the ply at each angle exhibit strong geometric similarity. The second and third shapes of the four angle ply types are highly similar, therefore it was decided to use both the second and third shapes for all four angle ply types. Furthermore, to facilitate production operations, the modified three-dimensional geometric model of the curved beam was unfolded into a planar graphic, as shown below. Figure 10 As shown in the diagram, the unfolded image provides a clear visual understanding of the fabric shape that should be cut during production. (4) Horizontal beams and longitudinal beams After free-size optimization, the thickness of each region of the crossbeam and longitudinal beam is not significantly different, and the generated first, second, and third ply shapes have extremely strong geometric similarity. Therefore, it was decided to use a single ply shape for both the crossbeam and longitudinal beam, with the shape being their original geometry. In the software, the following operation is required: delete the second and third ply shapes generated for the crossbeam and longitudinal beam, retaining only the first ply shape as the design variable for subsequent size optimization; Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A CFRP equipment cabin composite material part structure optimization design method, characterized in that, The method comprises the following steps: S1: free size optimization, taking one or more ply angle groups of each composite part in the equipment cabin as design variables, taking the minimum structural flexibility as the objective function, performing free size optimization to obtain the thickness distribution and initial ply shape of each ply angle group; S2: ply shape trimming, geometrically trimming the initial ply shape obtained in S1 to meet the manufacturability requirements to obtain the trimmed ply shape; S3: size optimization, taking the trimmed ply shape obtained in S2 as the design variable, taking the minimum overall weight of the equipment cabin as the objective function, and taking the maximum displacement of the overall structure of the equipment cabin as the constraint condition, performing size optimization to determine the final ply thickness of each trimmed ply shape; S4: ply sequence optimization, taking the ply shape with the final ply thickness determined in S3 as the design variable, taking the minimum structural flexibility as the objective function, and taking the maximum displacement of the overall structure of the equipment cabin as the constraint condition, performing ply sequence optimization to determine the optimal stacking sequence of each ply.

2. The method according to claim 1, wherein, In the step S1, the composite parts of the equipment cabin include sandwich panel structures and laminated plate structures; For the sandwich panel structure, only one or more ply angle groups of the inner plate thereof are subjected to the free size optimization; For the laminated plate structure, all ply angle groups thereof are subjected to the free size optimization.

3. The method of claim 1, wherein the method further comprises: In the step S2, the geometric trimming of the initial ply shape comprises: For the initial ply shapes of different ply angle groups with strong geometric similarity, performing ply shape common processing; Expanding the three-dimensional curved surface shape of the ply into a two-dimensional planar graph.

4. The method of claim 3, wherein the method further comprises: The ply shape common processing specifically comprises: If the second ply shape and the third ply shape generated after optimization of different ply angle groups have geometric similarity, the different ply angle groups share the second ply shape and the third ply shape after trimming.

5. The method of claim 1, wherein the method is characterized by: In the step S3, the size optimization process decomposes each ply angle group into a single ply and constrains the thickness of the single ply to be an integer multiple of the thickness of a single layer of carbon fiber cloth, and the thickness of a single layer of carbon fiber cloth is 0.2 mm.

6. The method of claim 1, wherein the method is characterized by: In the steps S1 and S3, the maximum displacement of the overall structure of the equipment cabin is constrained to be less than or equal to 5 mm.

7. The method of claim 1, wherein the method further comprises: In the step S2, for the parts with no obvious difference in the ply shape after free size optimization and strong geometric similarity, the original geometric shape thereof is adopted as the only trimmed ply shape.

8. The method of claim 1, wherein the method further comprises: After the ply sequence optimization in the step S4, the method further comprises: S5: performance verification, performing finite element analysis on the overall structure of the equipment cabin after optimization in S1-S4 to verify whether the stiffness and strength of the overall structure of the equipment cabin under the target working condition meet the preset requirements; Wherein, the stiffness is evaluated by the maximum displacement value of the equipment cabin, and the strength is evaluated by the damage factor of the composite layer and the equivalent stress of the metal connecting piece.

9. The method of claim 1-8, wherein, After the three-level optimization in S1-S4, the overall weight of the equipment cabin is reduced by at least 10% compared with the original design, and the maximum displacement value is reduced by at least 20%.

10. A rail vehicle equipment compartment, characterized in that At least one composite part of the skirt, the floor, the curved beam, the cross beam and the longitudinal beam of the equipment cabin is designed and manufactured by the method of any one of claims 1-9.

Images