Lightweight vehicle body integrated manufacturing process based on additive manufacturing

Abstract

This invention relates to the field of automotive body manufacturing technology, specifically to a lightweight integrated manufacturing process for automotive body structures based on additive manufacturing. The process involves first preparing a nanocomposite reinforcing material containing an aluminum alloy matrix, surface-modified silicon carbide nanoparticles, graphene sheets, and MOF-derived carbon materials; then employing multi-beam synergistic laser powder bed melting molding, controlling laser parameters and scanning strategies; optimizing the microstructure through electric field-assisted gradient heat treatment; preparing a self-healing coating using micro-arc oxidation-electrophoresis composite technology; and incorporating a multi-level porous structure based on biomechanical biomimetic design. Furthermore, it can integrate sensors and perform surface strengthening and drag reduction treatments to achieve lightweight and high-performance vehicle bodies. This invention improves vehicle body strength and reduces weight through innovative technologies such as nanocomposite reinforcing materials, multi-beam molding, and electric field heat treatment; optimizes mechanical properties through biomimetic structural design; enhances corrosion resistance through a self-healing coating; and enables intelligent monitoring through sensor integration.

Description

Technical Field

[0001] This invention relates to the field of automotive body manufacturing technology, specifically to an integrated manufacturing process for lightweight body structures based on additive manufacturing. Background Technology

[0002] With the rapid development of the automotive industry, lightweighting has become a key technological direction for improving vehicle fuel efficiency and reducing emissions. Traditional vehicle body manufacturing mainly relies on processes such as die casting and stamping, which suffers from problems such as low material utilization and limited structural design. For example, traditional processes make it difficult to achieve complex hollow structures and variable cross-section designs, resulting in difficulty in further reducing vehicle weight. At the same time, the shortcomings of lightweight materials such as aluminum alloys in terms of strength, corrosion resistance, and fatigue performance restrict their widespread application in vehicle body structures. In addition, in traditional manufacturing processes, material preparation, forming, and surface treatment are relatively independent, making it difficult to achieve integrated and coordinated optimization, leading to bottlenecks in improving vehicle body structural performance.

[0003] The emergence of additive manufacturing technology has provided a new approach to vehicle lightweighting, but it still faces many challenges in practical applications. Existing aluminum alloy materials used in additive manufacturing lack sufficient strength, and the addition of traditional reinforcing particles easily leads to uneven dispersion and weak interfacial bonding, affecting the overall material performance. In terms of forming processes, laser powder bed melting technology suffers from high residual stress and insufficient forming precision, resulting in a high rate of internal defects in the vehicle body structure. Furthermore, traditional heat treatment processes struggle to effectively control the gradient microstructure unique to additive manufacturing, failing to fully realize the material's potential. Regarding surface treatment and functional integration, existing technologies lack coating preparation methods that synergize with additive manufacturing processes, resulting in limited improvements in the vehicle body's corrosion and wear resistance, while also hindering the integrated integration of functional components such as sensors.

[0004] With the development of intelligent and electric vehicles, higher demands are being placed on vehicle body structures, requiring not only extreme lightweighting and high strength, but also self-monitoring and self-repair capabilities. However, current technologies have made slow progress in the multi-functional integration of vehicle body structures, failing to meet the safety, reliability, and intelligence requirements of next-generation vehicles. Therefore, there is an urgent need to develop a vehicle body manufacturing technology that integrates material innovation, molding process optimization, structural design innovation, and functional integration to break through traditional process bottlenecks and achieve a comprehensive improvement in vehicle body performance. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides an integrated manufacturing process for lightweight vehicle body structures based on additive manufacturing.

[0007] (II) Technical Solution

[0008] The integrated manufacturing process for lightweight vehicle body structures based on additive manufacturing includes the following steps:

[0009] S1: Preparation of nanocomposite reinforcing materials, by mass ratio, comprising 76-80% Al-Zn-Mg-Cu alloy matrix, with 0.8-1.2% scandium Sc and 0.5-0.8% yttrium Y added for grain refinement; 10-13% surface-modified silicon carbide nanoparticles, treated with KH560 silane coupling agent, achieving a grafting rate of 18-22%; 7-9% graphene oxide, formed into graphene sheets through in-situ chemical reduction; and 5-7% MOF-derived carbon material, generated by pyrolysis of ZIF-8 at 900℃ under a nitrogen atmosphere, with a specific surface area of ​​1800-2000 m². 2 / g; An in-situ reaction occurs during material preparation: 4Al + 3C → Al4C3, forming 50-150nm reinforcing whiskers;

[0010] S2: Employs multi-beam synergistic laser powder bed melting technology. The main laser beam has a power of 400-450W and a wavelength of 1070nm for complete powder melting; the auxiliary laser beam has a power of 80-120W and a wavelength of 532nm for real-time remelting of the molten pool; the scanning speed is 1400-1600mm / s, the layer thickness is 40μm, and the construction chamber is filled with high-purity helium for protection, with the oxygen content controlled below 30ppm;

[0011] S3: Implement electric field-assisted gradient heat treatment. Place the molded part in a DC electric field of 3-5V / cm, first perform solution treatment at 430-450℃ for 2.5 hours, then water cool and age at 170℃ for 10 hours. Under the action of the electric field, promote the uniform distribution of Al3Sc and Al3Zr nano-precipitates and form a gradient structure.

[0012] S4: A composite coating was prepared using a micro-arc oxidation-electrophoresis composite technology. First, micro-arc oxidation was performed in an electrolyte containing 18 g / L sodium silicate, 8 g / L sodium hydroxide, and 4 g / L sodium tungstate at a voltage of 450 V and a frequency of 800 Hz for 20 minutes to form a ceramic underlayer. Then, electrophoretic deposition was performed in an epoxy electrophoresis solution containing carbon nanotubes at a voltage of 80 V for 3 minutes to form a self-healing coating.

[0013] S5: Based on biomechanical biomimetic optimization design, it takes the honeycomb-truss composite structure of bird skeleton as the prototype and combines topology optimization algorithm to build a multi-level porous structure in key parts of the vehicle body; the outer layer is a honeycomb structure with a pore diameter of 2-5mm, and the inside is a truss support with a rod diameter of 1.2-1.8mm, with the overall porosity controlled at 45-55%.

[0014] Preferably, the nanocomposite reinforcing material in S1 further includes 0.3-0.5% of nano boron nitride particles with a particle size of 20-40 nm, forming a three-dimensional thermally conductive network in the material, thereby increasing the thermal conductivity of the material to 180-220 W / (m·K).

[0015] Preferably, the multi-beam collaborative laser powder bed melting technology described in S2 adopts an asymmetric scanning strategy, with the scanning direction angle between adjacent layers being 67°, and the scanning path using variable spacing filling. The filling spacing in critical stress areas is 0.08-0.1 mm, and in non-critical areas it is 0.12-0.15 mm, resulting in a reduction of residual stress by more than 40%.

[0016] Preferably, in the electric field-assisted gradient heat treatment process described in S3, the direction of the electric field is at a 45° angle to the direction of the heat treatment temperature gradient, which promotes the directional migration of solute atoms and forms a layered precipitation strengthening phase, thereby increasing the yield strength of the material to 580-620 MPa.

[0017] Preferably, the self-healing coating in S4 contains a microencapsulated epoxy resin repair agent with a microcapsule particle size of 5-15 μm and a content of 8-12% of the coating mass. When cracks appear in the coating, the microcapsules rupture and release the repair agent, thereby achieving self-healing of the coating.

[0018] Preferably, the honeycomb cell walls and truss members of the multi-level porous structure in S5 adopt a variable thickness design, with the thickness increasing by 20-30% in the stress concentration area and decreasing by 15-20% in the non-concentration area, to achieve the optimal match between weight and strength.

[0019] Preferably, it also includes S6: integrating a fiber optic sensor network inside the vehicle body structure, using embedded 3D printing technology to embed distributed fiber optic sensors with a diameter of 0.2-0.5mm into the structure, with a sensor spacing of 20-50mm, to achieve a strain monitoring accuracy of ±5με.

[0020] Preferably, it also includes S7: supercritical fluid treatment of the vehicle body structure, impregnating nano-silica particles in the supercritical state of CO2, so that the particles penetrate into the surface layer of the material by 50-100μm, and the surface hardness is increased by 15-20%.

[0021] Preferably, it also includes S8: using laser shock peening technology to treat key parts of the vehicle body, with a laser energy density of 5-8 J / cm². 2 The pulse width is 10-20ns, the coverage is 100-150%, and a compressive stress layer with a depth of 0.3-0.5mm is formed, which improves fatigue life by 60-80%.

[0022] Preferably, it also includes S9: preparing a biomimetic coupling drag reduction structure on the surface of the vehicle body structure, and preparing a groove structure that resembles dolphin skin by laser micro-nano processing technology. The groove depth is 50-100μm, the width is 100-200μm, and the spacing is 200-300μm, thereby reducing fluid resistance by 8-12%.

[0023] (III) Beneficial Effects

[0024] Compared with existing technologies, the beneficial effects of this invention are:

[0025] 1. The lightweight integrated manufacturing process for vehicle body structures based on additive manufacturing proposed in this invention significantly improves vehicle body performance through multi-dimensional innovation. In the material preparation stage, nanocomposite reinforcement technology is employed to introduce silicon carbide nanoparticles, graphene sheets, and MOF-derived carbon materials into the aluminum alloy matrix. Through in-situ reaction, a high-strength reinforcing phase is generated, effectively improving the material's tensile strength, fatigue life, and thermal conductivity. This composite material, while maintaining lightweight properties, solves the problem of insufficient strength in traditional aluminum alloys, laying the material foundation for lightweight vehicle bodies.

[0026] 2. Multi-beam synergistic laser powder bed melting technology, combined with an asymmetric scanning strategy, achieves precise control of the molten pool and effective reduction of residual stress, improving forming accuracy and internal quality. Electric field-assisted gradient heat treatment, through the synergistic effect of the electric and temperature fields, promotes the uniform distribution of nano-precipitates, forming a gradient-strengthened structure and further optimizing the material's mechanical properties. These process innovations result in vehicle body structures with significantly superior density, strength, and fatigue resistance compared to traditional manufacturing methods.

[0027] 3. Based on a biomechanically inspired multi-level porous structure, such as the honeycomb-truss composite structure of bird skeletons, optimal material distribution is achieved in key areas, ensuring structural strength while significantly reducing weight. This design allows the vehicle body to effectively absorb energy during a collision, while also reducing the drag coefficient and improving aerodynamic performance. The surface treatment process employs micro-arc oxidation-electrophoresis composite technology to prepare a self-healing composite coating, significantly improving the vehicle body's corrosion resistance and wear resistance, and extending its service life.

[0028] 4. The integrated fiber optic sensor network and biomimetic coupling drag reduction structure in the process endow the vehicle body structure with real-time stress monitoring and low wind resistance characteristics, driving the development of vehicle bodies towards intelligence and functionality. The application of technologies such as supercritical fluid processing and laser shock peening further improves the surface properties and fatigue life of materials. Overall, this process achieves full-process optimization from material preparation to structural forming, surface treatment, and functional integration. While ensuring high strength and lightweight body, it improves corrosion resistance, fatigue resistance, and intelligence level, meeting the urgent needs of the automotive industry for high-performance body structures and possessing significant economic and technical value. Attached Figure Description

[0029] Figure 1 This is a flowchart of the integrated manufacturing process for lightweight vehicle body structures based on additive manufacturing.

[0030] Figure 2 This is a bar chart comparing the tensile strength and yield strength of the examples and comparative examples;

[0031] Figure 3 This is a line graph comparing the thermal conductivity and surface hardness of the examples and comparative examples;

[0032] Figure 4 This is a bar chart comparing the weight and drag coefficient of the embodiment and the comparative example. Detailed Implementation

[0033] according to Figures 1 to 4 The specific embodiments of the present invention are as follows:

[0034] Example 1

[0035] S1: Preparation of nanocomposite reinforcing materials. By mass percentage, the following components were prepared: 78% Al-Zn-Mg-Cu alloy powder (containing 1.0% Sc and 0.6% Y), 12% silicon carbide nanoparticles (average particle size 40 nm, treated with KH560 silane coupling agent, grafting rate 20%), 8% graphene oxide (sheet diameter 2 μm, thickness 8 nm), and 5% MOF-derived carbon material (ZIF-8 pyrolyzed at 900℃ under a nitrogen atmosphere, specific surface area 1900 m²). 2 0.4% boron nitride nanoparticles (30 nm in diameter) were added to a high-energy ball mill. The ball-to-particle ratio was 10:1, the ball milling speed was 300 r / min, and the ball milling time was 6 hours to obtain a uniformly mixed composite powder.

[0036] S2: Forming is performed using a multi-beam synergistic laser powder bed melting system. The main laser beam power is 420W, wavelength 1070nm; the auxiliary laser beam power is 100W, wavelength 532nm. The scanning speed is 1500mm / s, the layer thickness is 40μm, and the scanning spacing is 0.1mm. The scanning angle between adjacent layers is 67°, the filling spacing in critical stress areas is 0.09mm, and in non-critical areas it is 0.13mm. The build chamber is filled with high-purity helium, and the oxygen content is controlled at 25ppm.

[0037] S3: Perform electric field-assisted gradient heat treatment. Place the molded part in a 4V / cm DC electric field, with the electric field direction at 45° to the temperature gradient direction. First, perform solution treatment at 440℃ for 2.5 hours, followed by water cooling and aging treatment at 170℃ for 10 hours.

[0038] S4: Preparation of the composite coating. First, micro-arc oxidation was performed in an electrolyte containing 18 g / L sodium silicate, 8 g / L sodium hydroxide, and 4 g / L sodium tungstate at 450 V and 800 Hz for 20 minutes to form a ceramic underlayer. Then, electrophoretic deposition was performed in an epoxy electrophoresis solution containing carbon nanotubes at 80 V for 3 minutes to form a self-healing coating containing 10% microencapsulated epoxy resin repair agent (microcapsule particle size 10 μm).

[0039] S5: Based on biomechanical biomimetic optimization design, a multi-level porous structure is constructed. The outer honeycomb structure has a pore diameter of 3mm, the internal truss members have a diameter of 1.5mm, and the overall porosity is 50%. The cell wall and member thickness is increased by 25% in stress concentration areas and decreased by 20% in non-stress concentration areas.

[0040] S6: Integrated fiber optic sensor network. Distributed fiber optic sensors with a diameter of 0.3mm are embedded in the structure using embedded 3D printing technology, with a sensor spacing of 30mm.

[0041] S7: Supercritical fluid treatment. Impregnate nano-silica particles for 30 minutes under supercritical CO2 conditions (temperature 45℃, pressure 10MPa).

[0042] S8: Laser shock peening treatment. This treatment is applied to key areas of the vehicle body, such as the B-pillar, using a laser energy density of 6 J / cm². 2 The pulse width is 15ns, and the coverage is 120%.

[0043] S9: Fabrication of a biomimetic coupling drag-reducing structure. A groove structure resembling dolphin skin was fabricated using laser micro-nano fabrication technology. The grooves were 70 μm deep, 150 μm wide, and 250 μm apart.

[0044] Example 2

[0045] S1: Preparation of nanocomposite reinforcing materials. By mass percentage, the following components were prepared: 76% Al-Zn-Mg-Cu alloy powder (containing 0.8% Sc and 0.5% Y), 13% silicon carbide nanoparticles (average particle size 30 nm, treated with KH560 silane coupling agent, grafting rate 18%), 9% graphene oxide (sheet diameter 1 μm, thickness 5 nm), and 7% MOF-derived carbon material (ZIF-8 pyrolyzed at 900℃ under nitrogen atmosphere, specific surface area 1800 m²). 2 0.3% boron nitride nanoparticles (20 nm in diameter) were added to a high-energy ball mill. The ball-to-particle ratio was 12:1, the ball milling speed was 350 r / min, and the ball milling time was 5 hours to obtain a uniformly mixed composite powder.

[0046] S2: Forming is performed using a multi-beam synergistic laser powder bed melting system. The main laser beam power is 400W with a wavelength of 1070nm; the auxiliary laser beam power is 80W with a wavelength of 532nm. The scanning speed is 1400mm / s, the layer thickness is 40μm, and the scanning spacing is 0.08mm. The scanning direction angle between adjacent layers is 65°, the filling spacing in critical stress areas is 0.08mm, and in non-critical areas it is 0.12mm. The build chamber is filled with high-purity helium, and the oxygen content is controlled at 30ppm.

[0047] S3: Perform electric field-assisted gradient heat treatment. Place the molded part in a 3V / cm DC electric field, with the electric field direction at 40° to the temperature gradient direction. First, perform solution treatment at 430℃ for 3 hours, followed by water cooling and aging treatment at 165℃ for 12 hours.

[0048] S4: Preparation of the composite coating. First, micro-arc oxidation was performed in an electrolyte containing 15 g / L sodium silicate, 7 g / L sodium hydroxide, and 3 g / L sodium tungstate at 420 V and 700 Hz for 25 minutes to form a ceramic underlayer. Then, electrophoretic deposition was performed in an epoxy electrophoresis solution containing carbon nanotubes at 75 V for 4 minutes to form a self-healing coating containing 8% microencapsulated epoxy resin repair agent (microcapsule particle size 8 μm).

[0049] S5: Based on biomechanical biomimetic optimization design, a multi-level porous structure is constructed. The outer honeycomb structure has a pore diameter of 2mm, the internal truss members have a diameter of 1.2mm, and the overall porosity is 45%. The cell wall and member thickness is increased by 20% in stress concentration areas and decreased by 15% in non-concentration areas.

[0050] S6: Integrated fiber optic sensor network. Distributed fiber optic sensors with a diameter of 0.2 mm are embedded in the structure using embedded 3D printing technology, with a sensor spacing of 40 mm.

[0051] S7: Supercritical fluid treatment. Nano-silica particles were impregnated for 40 minutes under supercritical CO2 conditions (temperature 40℃, pressure 8MPa).

[0052] S8: Laser shock peening treatment. This treatment is applied to key areas of the vehicle body, such as the A-pillar, using a laser energy density of 5 J / cm². 2 The pulse width is 12ns, and the coverage is 100%.

[0053] S9: Fabrication of a biomimetic coupling drag-reducing structure. A groove structure resembling dolphin skin was fabricated using laser micro-nano fabrication technology. The grooves were 50 μm deep, 120 μm wide, and 220 μm apart.

[0054] Example 3

[0055] S1: Preparation of nanocomposite reinforcing materials. By mass percentage, 80% Al-Zn-Mg-Cu alloy powder (containing 1.2% Sc and 0.8% Y), 10% silicon carbide nanoparticles (average particle size 50 nm, treated with KH560 silane coupling agent, grafting rate 22%), 7% graphene oxide (sheet diameter 3 μm, thickness 10 nm), and 5% MOF-derived carbon material (ZIF-8 pyrolyzed at 900℃ under nitrogen atmosphere, specific surface area 2000 m²) were prepared. 2 0.5% boron nitride nanoparticles (40 nm in diameter) were added to a high-energy ball mill. The ball-to-particle ratio was 8:1, the ball milling speed was 280 r / min, and the ball milling time was 7 hours to obtain a uniformly mixed composite powder.

[0056] S2: Forming is performed using a multi-beam synergistic laser powder bed melting system. The main laser beam power is 450W, wavelength 1070nm; the auxiliary laser beam power is 120W, wavelength 532nm. The scanning speed is 1600mm / s, the layer thickness is 40μm, and the scanning spacing is 0.12mm. The scanning direction angle between adjacent layers is 70°, the filling spacing in critical stress areas is 0.1mm, and in non-critical areas it is 0.15mm. The build chamber is filled with high-purity helium, and the oxygen content is controlled at 20ppm.

[0057] S3: Perform electric field-assisted gradient heat treatment. Place the molded part in a 5V / cm DC electric field, with the electric field direction at 50° to the temperature gradient direction. First, perform solution treatment at 450℃ for 2 hours, followed by water cooling and aging treatment at 175℃ for 8 hours.

[0058] S4: Preparation of the composite coating. First, micro-arc oxidation was performed in an electrolyte containing 20 g / L sodium silicate, 10 g / L sodium hydroxide, and 5 g / L sodium tungstate at 480 V and 900 Hz for 15 minutes to form a ceramic underlayer. Then, electrophoretic deposition was performed in an epoxy electrophoresis solution containing carbon nanotubes at 85 V for 2 minutes to form a self-healing coating containing 12% microencapsulated epoxy resin repair agent (microcapsule particle size 15 μm).

[0059] S5: Based on biomechanical biomimetic optimization design, a multi-level porous structure is constructed. The outer honeycomb structure has a pore diameter of 5mm, the internal truss members have a diameter of 1.8mm, and the overall porosity is 55%. The cell wall and member thickness is increased by 30% in stress concentration areas and decreased by 25% in non-stress concentration areas.

[0060] S6: Integrated fiber optic sensor network. Distributed fiber optic sensors with a diameter of 0.5mm are embedded in the structure using embedded 3D printing technology, with a sensor spacing of 20mm.

[0061] S7: Supercritical fluid treatment. Impregnate nano-silica particles for 20 minutes under supercritical CO2 conditions (temperature 50℃, pressure 12MPa).

[0062] S8: Laser shock peening treatment. This treatment is applied to critical areas such as the vehicle's door sills, using a laser energy density of 8 J / cm². 2 The pulse width is 20ns, and the coverage is 150%.

[0063] S9: Fabrication of a biomimetic coupling drag-reducing structure. A groove structure resembling dolphin skin was fabricated using laser micro-nano fabrication technology. The grooves were 100 μm deep, 200 μm wide, and 300 μm apart.

[0064] Comparative Example

[0065] The aluminum alloy body structure is manufactured using a traditional die-casting process. A356 aluminum alloy is used, melted at 720℃ and injected into a mold under a die-casting pressure of 50 MPa. After forming, it undergoes T6 heat treatment (solution treatment at 540℃ for 6 hours, followed by aging treatment at 160℃ for 8 hours). The body structure is a solid design with a thickness of 3-5 mm. The surface is anodized, with a coating thickness of 15 μm.

[0066] The performance comparison between the examples and the comparative examples is shown in the table below:

[0067] Table 1

[0068] Test Project Example 1 Example 2 Example 3 Comparative Example <![CDATA[Density (g / cm 3 )]]> 2.78 2.76 2.80 2.70 Tensile strength (MPa) 685 650 710 320 Yield strength (MPa) 605 580 620 280 Elongation (%) 12.5 11.8 10.5 8.2 Elastic modulus (GPa) 78 76 80 70 Fatigue life (cycles) <![CDATA[1.2×10 6 ]]> <![CDATA[1.0×10 6 ]]> <![CDATA[1.3×10 6 ]]> <![CDATA[3.5×10 5 ]]>

[0069] In summary, the comprehensive test data shows that the materials prepared in Examples 1-3 have significantly better performance than the comparative examples. Regarding density, the differences between the examples and the comparative examples are not significant, both approaching 2.7-2.8 g / cm³. 3 In terms of strength, the tensile strength of the examples was 650-710 MPa, and the yield strength was 580-620 MPa, significantly higher than the 320 MPa and 280 MPa of the comparative examples; the elongation and elastic modulus also performed well. Regarding fatigue life, the examples achieved a maximum of 1.3 × 10⁻⁶. 6 The cycle is far greater than the comparative example of 3.5 × 10⁻⁶. 5 Cyclic testing demonstrates that the materials in the embodiments exhibit superior performance. A comparison of the thermal conductivity, surface hardness, and drag coefficient between the embodiments and the comparative examples is shown in the table below:

[0070] Table 2

[0071]

[0072] In summary, the test results show that Examples 1-3 are significantly superior to the comparative examples in terms of thermal management, mechanical properties, and aerodynamics. Thermal conductivity (205-215 W / m·K) is improved by 28%-34% compared to the comparative examples, surface hardness (175-195 HV) is increased by 45%-63%, the coefficient of friction (0.14-0.16) is reduced by 50%, and the drag coefficient (0.27-0.29) is optimized by 17%-20%. Meanwhile, the weight is controlled at 120-130 kg, 39% lighter than the comparative examples, demonstrating a significant improvement in overall performance, making them particularly suitable for automotive lightweighting and thermal management optimization needs.

[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their likenesses.

Claims

1. A lightweight vehicle body structure integrated manufacturing process based on additive manufacturing, characterized in that, Includes the following steps: S1: Preparation of nanocomposite reinforcing materials, by mass ratio, comprising 76-80% Al-Zn-Mg-Cu alloy matrix, with 0.8-1.2% scandium Sc and 0.5-0.8% yttrium Y added for grain refinement; 10-13% surface-modified silicon carbide nanoparticles, treated with KH560 silane coupling agent, with a grafting rate of 18-22%; 7-9% graphene oxide, formed into graphene sheets through in-situ chemical reduction; and 5-7% MOF-derived carbon material, generated by pyrolysis of ZIF-8 at 900℃ under a nitrogen atmosphere, with a specific surface area of ​​1800-2000 m² / g. During the material preparation process, an in-situ reaction occurs: 4Al + 3C → Al4C3, forming reinforcing whiskers of 50-150 nm. S2: Employs multi-beam synergistic laser powder bed melting technology. The main laser beam has a power of 400-450W and a wavelength of 1070nm, used for complete powder melting. The auxiliary laser beam has a power of 80-120W and a wavelength of 532nm, used for real-time remelting of the molten pool. The scanning speed is 1400-1600mm / s, the layer thickness is 40μm, and the construction chamber is filled with high-purity helium for protection, with the oxygen content controlled below 30ppm. S3: Implement electric field-assisted gradient heat treatment. Place the molded part in a DC electric field of 3-5V / cm, first perform solution treatment at 430-450℃ for 2.5 hours, then water cool and age at 170℃ for 10 hours. Under the action of the electric field, promote the uniform distribution of Al3Sc and Al3Zr nano-precipitates. S4: A composite coating was prepared using a micro-arc oxidation-electrophoresis composite technology. First, micro-arc oxidation was performed in an electrolyte containing 18 g / L sodium silicate, 8 g / L sodium hydroxide, and 4 g / L sodium tungstate at a voltage of 450 V and a frequency of 800 Hz for 20 minutes to form a ceramic underlayer. Then, electrophoretic deposition was performed in an epoxy electrophoresis solution containing carbon nanotubes at a voltage of 80 V for 3 minutes to form a self-healing coating. S5: Based on biomechanical biomimetic optimization design, it takes the honeycomb-truss composite structure of bird skeleton as the prototype and combines topology optimization algorithm to build a multi-level porous structure in key parts of the vehicle body; the outer layer is a honeycomb structure with a pore diameter of 2-5mm, and the inside is a truss support with a rod diameter of 1.2-1.8mm.

2. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, The nanocomposite reinforcing material described in S1 also includes 0.3-0.5% of nano-boron nitride particles with a particle size of 20-40 nm, forming a three-dimensional thermally conductive network in the material.

3. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, The multi-beam collaborative laser powder bed melting technology described in S2 adopts an asymmetric scanning strategy, with an angle of 67° between the scanning directions of adjacent layers. The scanning path uses variable spacing filling, with a filling spacing of 0.08-0.1 mm in critical stress areas and 0.12-0.15 mm in non-critical areas.

4. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, In the electric field-assisted gradient heat treatment process described in S3, the direction of the electric field forms a 45° angle with the direction of the heat treatment temperature gradient.

5. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, The self-healing coating described in S4 contains a microencapsulated epoxy resin repair agent with a microcapsule particle size of 5-15 μm and a content of 8-12% of the coating mass.

6. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, The honeycomb cell walls and truss members of the multi-level porous structure described in S5 adopt a variable thickness design, with the thickness increasing by 20-30% in stress concentration areas and decreasing by 15-20% in non-concentration areas.

7. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, It also includes S6: integrating a fiber optic sensor network inside the vehicle body structure, using embedded 3D printing technology to embed distributed fiber optic sensors with a diameter of 0.2-0.5mm into the structure, with a sensor spacing of 20-50mm.

8. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, It also includes S7: supercritical fluid treatment of the vehicle body structure, impregnating nano-silica particles in the supercritical state of CO2, so that the particles penetrate into the surface layer of the material by 50-100μm.

9. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, It also includes S8: using laser shock peening technology to treat key parts of the vehicle body, with a laser energy density of 5-8 J / cm², a pulse width of 10-20 ns, a coverage of 100-150%, and forming a compressive stress layer with a depth of 0.3-0.5 mm.

10. The integrated manufacturing process for lightweight vehicle body structure based on additive manufacturing according to claim 1, characterized in that, It also includes S9: fabricating a biomimetic coupling drag reduction structure on the surface of the vehicle body structure, and fabricating a groove structure that resembles dolphin skin through laser micro-nano processing technology. The groove depth is 50-100μm, the width is 100-200μm, and the spacing is 200-300μm.

Images