CFRP-aluminum alloy sandwich control arm with topological optimization design and manufacturing method of CFRP-aluminum alloy sandwich control arm

Abstract

The invention discloses a CFRP-aluminum alloy sandwich control arm adopting topological optimization design and a manufacturing method of the CFRP-aluminum alloy sandwich control arm, and belongs to the technical field of lightweight structural design of automobile chassis. In order to solve the problems that a traditional metal control arm is large in weight and insufficient in light weight, the control arm adopts an upper carbon fiber reinforced composite (CFRP) panel, a lower carbon fiber reinforced composite (CFRP) panel and a middle aluminum alloy core layer to form a sandwich structure, optimal rib distribution in the core layer is obtained through topological optimization, and structural rigidity and quality control are both considered. The carbon fiber panels are formed by laying 16 layers of 3K plain cloth prepregs according to the laying angle of [0 degree / 45 degrees / -45 degrees / 90 degrees], the aluminum alloy core layer is subjected to CNC machining to form a rib structure with topological optimization design, and the rib structure and the panels are assembled through a glue-screw mixed connection technology. Compared with a traditional metal control arm, on the premise that the mechanical property requirement is met, the mass is reduced by about 46.6%, and the control arm is suitable for a new energy automobile and a light-weight finished automobile platform.

Description

Technical Field

[0001] The present invention relates to the technical field of lightweight structural design of automobile chassis, and in particular to a CFRP-aluminum alloy sandwich control arm with topologically optimized design and a manufacturing method thereof. Background Art

[0002] As the automotive industry moves toward energy conservation, consumption reduction, and performance optimization, the demand for lightweight chassis structures is becoming increasingly significant. Control arms are key components in the suspension system that transmit force and guide tire movement. Their quality and mechanical properties directly impact the vehicle's fuel economy, handling stability, and ride comfort.

[0003] Traditional control arms are typically made of high-strength steel or aluminum alloy, offering a simple structure and low manufacturing costs. However, due to their high density, they struggle to meet the stringent "lightweight, high-strength" requirements of new energy vehicles and high-performance vehicles.

[0004] Carbon fiber reinforced plastics (CFRP) have low density, high specific strength, and long fatigue life, and have been widely used in high-end car bodies, panels, and other components. However, the overall stiffness control of CFRP structures is relatively complex, making it difficult to withstand multi-directional coupled loads alone.

[0005] Sandwich structures, a classic lightweight solution that balances structural performance and mass, combine high-strength facesheet materials with lightweight core materials, achieving a balance between out-of-plane stability and overall stiffness. However, most current sandwich structure designs rely on empirical design, resulting in crude structural layouts and a failure to balance dynamic performance, manufacturing costs, and connection stability. Summary of the Invention

[0006] To address these issues, the present invention provides a topologically optimized CFRP-aluminum alloy sandwich control arm and its manufacturing method. The core structure is derived from a topologically optimized solution to the control arm's operating conditions. This automatically generates an optimal aluminum alloy rib layout while satisfying multiple performance constraints. A hybrid rubber-screw connection process achieves stable integration of the carbon fiber reinforced composite faceplate and the aluminum alloy core. This creates a lightweight, high-strength control arm structure and provides a manufacturing method to meet the demands of current new energy vehicles and lightweight vehicle platforms.

[0007] To achieve the above object, the present invention provides a technical solution:

[0008] A topologically optimized CFRP-aluminum alloy sandwich control arm is constructed from an upper carbon fiber reinforced composite panel, an aluminum alloy sandwich layer, and a lower carbon fiber reinforced composite panel, connected in sequence from top to bottom. The aluminum alloy core layer of the sandwich control arm has three ends: two for bushing mounting and an outer end for ball joint connection.

[0009] The carbon fiber reinforced composite material panel is made of carbon fiber and thermosetting epoxy resin through molding, and has a thickness of about 4mm; the aluminum alloy core layer is 24mm thick, and the rib thickness is 2mm, and is made through precision CNC processing; the carbon fiber reinforced composite material panel and the aluminum alloy core layer are connected to form a whole through a hybrid glue-screw connection.

[0010] The adhesive-screw hybrid connection should be made by drilling six holes at the bolt connection points of the aluminum alloy core layer and the carbon fiber reinforced composite panel, and then connecting them with bolts. At the same time, adhesive should be filled between the carbon fiber reinforced composite panel and the aluminum alloy core layer.

[0011] A method for manufacturing a topologically optimized CFRP-aluminum alloy sandwich control arm comprises the following steps:

[0012] S1: Constructing a topology optimization model of a sandwich control arm; taking minimizing the weighted strain energy under two stiffness conditions as the optimization goal, taking the cell density in the thick plate area of ​​the aluminum alloy core layer of the sandwich control arm as the design variable, optimizing the topology optimization model to obtain an optimized design value of the aluminum alloy core layer cell density, and representing the result as a two-dimensional topological pattern;

[0013] S2: In the 2D topological pattern obtained in S1, the cell density in light-colored areas approaches 1, representing the primary retained structure; the cell density in darker areas approaches 0, representing areas that can be deleted; and the transition between 0 and 1 can be adjusted based on design requirements. A cell density threshold of 0.5 is set, and considering manufacturing requirements, the model is reconstructed based on the topology optimization results.

[0014] S3: Based on the topological optimization structure of the aluminum alloy core layer obtained in S2, a three-dimensional model of the aluminum alloy core layer of the sandwich control arm is constructed and manufactured through precision CNC processing.

[0015] S4: Prepare carbon fiber plain weave prepreg, using a thermosetting epoxy resin matrix. Place the plain weave prepreg in an aluminum mold and lay it in a 4-ply sequence of [0° / 45° / -45° / 90°], with a single layer thickness of 0.25 mm, for a total of 16 layers. Encapsulate with release cloth and a breathable cotton layer, then pre-press in a vacuum bag.

[0016] S5: High temperature curing, using the following temperature and pressure curve: first stage: 80℃, -0.96MPa, hold for 0.5 hour; second stage: 120℃, -0.96MPa, hold for 2 hours; naturally cool to room temperature and then demould.

[0017] S6: Cut the formed carbon fiber reinforced composite panel to the core layer design contour, trim the flash, polish the surface, and drill bolt holes at the connection position. Assemble the aluminum alloy core layer and the CFRP panel structure in position, apply adhesive at the interface, and tighten high-strength bolts at the same time. After curing, the overall structure is formed.

[0018] In step S4, 3K plain weave prepreg carbon fiber is used for molding.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The total mass of the carbon fiber composite material-aluminum alloy core control arm is approximately 46.6% lower than that of traditional steel structures, achieving lightweighting of the entire vehicle. The optimal rib distribution layout of the aluminum alloy core layer was designed through topology optimization methods, taking into account dynamic performance, manufacturing costs and connection stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following is a brief description of the contents expressed in the drawings and the symbols in the drawings of this specification:

[0022] Figure 1 The aluminum alloy core layer of the sandwich control arm of the present invention is optimized in topology;

[0023] Figure 2 The aluminum alloy core layer of the sandwich control arm of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the sandwich control arm of the present invention;

[0025] Figure 4 An exploded view of the sandwich control arm of the present invention;

[0026] Figure 5 A schematic diagram of the manufacturing process of the sandwich control arm provided by the present invention;

[0027] Description of reference numerals:

[0028] 1. Sandwich control arm body;

[0029] 2. Sandwich control arm carbon fiber panel;

[0030] 3. Aluminum alloy core layer of sandwich control arm;

[0031] 4-6. End of the aluminum alloy core layer of the sandwich control arm. DETAILED DESCRIPTION

[0032] To further illustrate the technical content of the present invention, the sandwich structure control arm of the present invention is described in detail below with reference to the accompanying drawings and specific structural dimensions.

[0033] like Figure 3As shown, a CFRP-aluminum alloy sandwich control arm (1) with a topologically optimized design is provided. The control arm is a sandwich composite structure, consisting of an aluminum alloy core layer (3) and upper and lower carbon fiber composite material panels (2). Connecting structural members (4) and (6) are provided at both ends of the aluminum alloy core material, which are connected to the subframe through front and rear bushings. A ball head connector (5) is provided at the outer end and connected to the steering knuckle through a ball joint, resulting in a three-point suspension connection structure as a whole.

[0034] The carbon fiber composite material panel (2) is a laminated structure, formed by stacking multiple layers of 3K plain weave carbon fiber prepreg, the resin system is a thermosetting epoxy matrix, the ply angles are symmetrically arranged as follows: [0° / 45° / -45° / 90°]4, the thickness of a single layer is 0.25 mm, and a total thickness of 16 layers is 4 mm.

[0035] The aluminum alloy core material (3) is made of 6061-T6 aluminum material through precision CNC processing, the thickness of the aluminum alloy core layer is 24mm, and the thickness of the ribs is 2mm. Bolt holes are drilled at the connection position to facilitate docking and installation with the carbon fiber composite material panel. The bolt size is M6, and the number is 2 per end.

[0036] The manufacturing method of the sandwich structure control arm of the present invention is as follows, and the specific steps are as follows:

[0037] S1: Establishment of the topological pattern of the two-dimensional control arm core layer

[0038] Determine the two-dimensional design domain of the control arm core layer; determine the physical properties of the core layer material, construct a topology optimization model of the control arm core layer, and input it into the topology optimization software; adopt the same loading conditions as the steel control arm, use the unit density in the core layer thick plate area (excluding the three ends) as the design variable, and take the minimization of weighted strain energy under two stiffness conditions as the optimization goal. Through the above topology optimization model, optimize the unit density of the control arm core layer and obtain the optimized design value of the aluminum alloy core layer unit density. The result represents the two-dimensional topological pattern of the control arm core layer.

[0039] S2: Establishment of the 3D model of the control arm core layer

[0040] Based on the two-dimensional topological pattern obtained in S1, the cell density of the light-colored area tends to 1, which is the main retained structure; the cell density of the dark-colored area tends to 0, which is the area that can be deleted; and the transition between 0 and 1 can be selected according to design requirements. Taking the cell density threshold as 0.5, the topological optimization structure of the aluminum core layer is obtained. From the optimization results, the longitudinal and transverse rib structures distributed outside and inside the core layer are the main retained structures, which can reduce the weight of the core layer while ensuring the performance of the control arm. Taking into account the processing and manufacturing requirements, the model is reconstructed based on the topological optimization results to obtain the topological optimization structure of the aluminum alloy core layer. Through stretching and cutting using 3D modeling software such as Solid Works, a 3D model of the aluminum alloy core layer with reinforcing ribs and three ends is formed.

[0041] S3: Based on S2, a three-dimensional model of the aluminum alloy core layer of the sandwich control arm is obtained, where the aluminum alloy core layer is 24 mm thick and the rib thickness is 2 mm, and is made by precision CNC processing.

[0042] S4: 3K carbon cloth prepreg is used with a thermosetting epoxy matrix. Layered production is performed with symmetrical ply angles of [0° / 45° / -45° / 90°], with a single layer thickness of 0.25mm. Sixteen layers are laid, totaling 4mm. The laminate is encapsulated with release cloth and breathable cotton and pre-pressed in a vacuum bag. The entire laminate is then placed in a hot press mold, ensuring continuous corner transitions and no overlap or misalignment.

[0043] S5: Place the above preform into a hot pressing mold and apply the following temperature-pressing curve: first stage: 80°C, -0.96 MPa, holding pressure for 0.5 hour (preheating and exhaust); second stage: heating to 120°C, -0.96 MPa, constant temperature curing for 2 hours; after cooling the mold to room temperature, demoulding is carried out to obtain a carbon fiber reinforced composite material panel.

[0044] S6: Cut the formed carbon fiber reinforced composite panel to the core layer design contour, trim the burrs, and polish the surface; drill M6 bolt holes at the corresponding positions of the connection ends; align the aluminum alloy core layer and the carbon fiber reinforced composite panel, apply epoxy structural adhesive, insert the bolts, and tighten the nuts; after the adhesive cures for 24 hours, complete the connection assembly.

[0045] This invention utilizes a sandwich control arm structure composed of a carbon fiber reinforced composite panel and an aluminum alloy core. Using topology optimization, the optimal rib layout within the aluminum alloy core is designed, resulting in a lightweight, high-strength, and excellent vibration damping control arm structure. The entire control arm weighs approximately 1.426 kg, a 46.6% reduction compared to the original steel control arm. This achieves a balance between lightweight and high performance, making it suitable for use in the chassis systems of new energy vehicles and high-performance passenger cars.

[0046] The above embodiment is only one of the preferred specific embodiments of the present invention. Any modifications, replacements and equivalent changes made to the structure, materials and connection methods by those skilled in the art without departing from the principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A topologically optimized CFRP-aluminum alloy sandwich control arm, characterized by: It includes an upper carbon fiber reinforced composite material panel, an aluminum alloy core layer and a lower carbon fiber reinforced composite material panel; the aluminum alloy core layer is constructed based on the topological optimization design results under typical working conditions of the control arm to form a lightweight structure with rib distribution; the upper and lower carbon fiber reinforced composite material panels are fixedly connected to the aluminum alloy core layer by a hybrid connection method combining adhesive and bolts to form an integrated structure.

2. The topologically optimized CFRP-aluminum alloy sandwich control arm according to claim 1, characterized in that The carbon fiber reinforced composite panel adopts 3K plain cloth prepreg, and is laid in the order of [0° / 45° / -45° / 90°], with a total of 16 layers.

3. The topologically optimized CFRP-aluminum alloy sandwich control arm according to claim 1, characterized in that The aluminum alloy sandwich layer is made of 6061-T6 aluminum material and is processed by CNC to form a multi-directional rib structure with a rectangular cross-section.

4. The topologically optimized CFRP-aluminum alloy sandwich control arm according to claim 1, characterized in that : The connection uses 6 M6 bolts, and the bolt holes are respectively set at the connection positions between the aluminum alloy core layer and the upper and lower carbon fiber panels, and epoxy structural adhesive is used to achieve a mixed connection between the panel and the core layer.

5. The topologically optimized CFRP-aluminum alloy sandwich control arm according to claim 1, characterized in that The aluminum alloy core layer of the sandwich structure control arm has three ends, two ends of which are used for bushing installation connection and the outer end is used for ball head connection.

6. A method for manufacturing a topologically optimized CFRP-aluminum alloy sandwich control arm, characterized in that: The steps include: S1: Establish a topology optimization model for the control arm sandwich region, with the objective function being to minimize the weighted strain energy under typical loading conditions. The design variable is the unit density of the aluminum alloy core region, and output a two-dimensional topological pattern. S2: Based on the topological pattern, extract the structural retention area and reconstruct the rib distribution, build a three-dimensional geometric model, and process it into 6061-T6 aluminum material through CNC processing technology; S3: Prepare a carbon fiber prepreg laminate structure with a layup angle of [0° / 45° / -45° / 90°], lay a total of 16 layers, load it into a mold, and package it in a vacuum bag; S4: performing hot pressing curing process, the curing curve is: holding pressure at 80°C for 0.5 hours in the first stage, holding pressure at 120°C for 2 hours in the second stage, and finally natural cooling and demoulding; S5: Trim the formed CFRP panels and drill connection holes, align and assemble them with the core layer, apply epoxy structural adhesive and tighten the bolts to complete the hybrid connection, and form the overall structure after curing.

7. The manufacturing method according to claim 6, characterized in that The topology optimization model is based on the SIMP density method, with a unit density threshold of 0.

5. Structures with a density higher than the threshold are retained, while those with a density lower than the threshold are removed.

8. The manufacturing method according to claim 6, characterized in that After the carbon fiber prepreg is laid, it is pressed at a vacuum pressure of -0.96 MPa, and is assisted by mold release cloth and breathing cotton for packaging to remove excess gas and resin.

9. The manufacturing method according to claim 6, characterized in that The bolts used for the bolt connection are of high-strength M6 specification, and combined with end face cleaning and curing adhesive, stable and reliable force transmission of the control arm under multiple working conditions can be achieved.

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