Stress release expansion path design method used before additive manufacturing of large-size thin-wall long and narrow asymmetric structural member

Abstract

The invention discloses a stress release expansion path design method used before additive manufacturing of a large-size thin-wall long and narrow asymmetric structural member, and belongs to the technical field of 3D printing, and the method comprises the following steps: S1, determining a forming direction according to geometrical characteristics of the structural member, performing simulation analysis to predict a deformation risk area, and obtaining an initial analysis result; s2, forming a symmetric reinforced post-structure according to the asymmetric structure, the symmetric reinforced structure and a reinforcing rib structure determined by the deformation risk area, and performing simulation analysis; s3, determining whether the deformation amount and the stress level conform to a preset tolerance or not; s4, a surrounding type flow guide structure is additionally arranged, the surrounding type flow guide structure and the symmetrically-reinforced post-structure type are connected through an interface connection structure to form a connected and reinforced post-structure, and simulation analysis is carried out; s5, judging whether the stress concentration phenomenon is eliminated or not; by means of the mode, the forming risk caused by stress generated during subsequent forming of the large-size thin-wall long and narrow asymmetric structural part is reduced.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and more specifically to a stress relief and expansion path design method for additive manufacturing of large-sized, thin-walled, narrow, and asymmetric structural parts. Background Technology

[0002] Laser powder bed fusion (LBD) is an advanced metal additive manufacturing technology. It uses a high-precision laser beam to selectively melt metal powder based on 3D model slice data, depositing it layer by layer to directly create dense metal structural components. The core advantage of this technology lies in its extremely high degree of design freedom, enabling the one-time forming of structural components with complex internal flow channels and lightweight lattice structures, overcoming the limitations of traditional manufacturing methods. The formed parts have a dense microstructure and excellent mechanical properties. Furthermore, it achieves moldless rapid manufacturing from digital models to finished products, possessing irreplaceable advantages in fields such as aerospace, medical implants, and innovative component manufacturing.

[0003] However, during the forming process, the rapid heating of the laser and the rapid cooling of the molten pool generate a severe temperature gradient and uneven thermal expansion and contraction within the material, leading to significant accumulation of thermal and residual stress. Such stress can easily cause deformation of structural components, and even cracks during or after forming, severely restricting forming accuracy and structural reliability. With the increasing demands for the size and performance of structural components in aerospace and other fields, the application of large-size, asymmetric, and thin-walled structural components is becoming more and more common. The stress concentration and deformation control problems during the forming process are becoming increasingly prominent, and have become a key bottleneck restricting the further development of this technology towards larger size and higher performance. Therefore, developing effective methods for active stress control and release is of great significance for breaking through the technical barriers of laser powder bed fusion forming of large-size structural components and promoting the wider application of this technology in high-end manufacturing. Summary of the Invention

[0004] The technical problem to be solved by this invention is to reduce the forming risk caused by stress during the subsequent forming of large-sized, thin-walled, narrow, and asymmetrical structural parts.

[0005] The technical solution adopted by this invention to solve the technical problem is: a method for designing stress relief and expansion paths before additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components, comprising the following steps:

[0006] S1: Based on the geometric characteristics of the structural component, determine the additive forming direction of the structural component, and use force-thermal coupling numerical simulation analysis to predict the deformation risk area during additive forming of the structural component and obtain the initial analysis results;

[0007] S2: Based on the asymmetric geometric features of the asymmetric structure in the structural component, a symmetrical reinforcement structure mirroring the asymmetric structure is determined. The asymmetric structure, the symmetrical reinforcement structure, and the stiffening rib structure for reinforcing the deformation risk area determined by the deformation risk area constitute the symmetrical reinforcement structure. The analysis results of the symmetrical reinforcement are obtained by force-thermal coupling numerical simulation analysis.

[0008] S3: Compare the analysis results after symmetrical reinforcement with the initial analysis results. If the deformation and stress levels do not meet the preset tolerance, repeat S2 until the deformation and stress levels meet the preset tolerance and then proceed to the next step.

[0009] S4: Round the corners of the intersection lines of adjacent surfaces and the outer contour of the structure in the symmetrically reinforced structure, and add a corresponding enclosed flow guiding structure. Use the interface connection structure to connect the enclosed flow guiding structure and the symmetrically reinforced structure to form a connected reinforced structure, and use force-thermal coupling numerical simulation analysis to obtain the analysis results of the connected reinforced structure.

[0010] S5: Based on the analysis results after the connection reinforcement, if the stress concentration phenomenon in the analysis results is eliminated, the design ends. If the stress concentration phenomenon in the analysis results is not eliminated, stress relief hole structures are added to the area corresponding to the stress concentration phenomenon and the non-functional area of ​​the structural component until the stress concentration phenomenon is eliminated.

[0011] As a preferred embodiment of the present invention, the step S1, which utilizes force-thermal coupling numerical simulation analysis to predict the deformation risk area during additive forming of the structural component and obtain initial analysis results, specifically includes:

[0012] Using a mesh size of not less than 5 mm, force-thermal coupling numerical simulation analysis was used to predict the deformation risk area of ​​the structural component during additive forming and obtain initial analysis results.

[0013] As a preferred embodiment of the present invention, the step S2, which determines the symmetrical reinforcement structure mirror-symmetrical to the asymmetrical structure based on the asymmetrical geometric features of the asymmetrical structure in the structural member, specifically includes:

[0014] Based on the asymmetrical geometric features of the asymmetrical structure in the structural component, a structural symmetry plane is determined to be mirror-symmetrical to the asymmetrical structure. Based on the structural symmetry plane, a symmetrical reinforcement structure mirror-symmetrical to the asymmetrical structure is determined. The structural symmetry plane is determined by the overall symmetry plane of the overall structure formed by the asymmetrical structure and the symmetrical reinforcement structure. The extension direction of the overall symmetry plane is consistent with the elongated extension direction of the structural component, and the overall structure is symmetrical with respect to the overall symmetry plane. Based on the geometric features of the structural component, the structural symmetry plane is formed by deflecting the overall symmetry plane by α° with one end as the deflection point, where α≤5.

[0015] As a preferred embodiment of the present invention, the deformation risk area is the region where the deformation stress during additive forming is predicted to be higher than 1000 MPa through force-thermal coupling numerical simulation analysis.

[0016] As a preferred embodiment of the present invention, the reinforcing rib structure includes a single reinforcing rib structure and a grid reinforcing rib structure. When the dimension of the deformation risk area in a single direction is greater than three times the thickness of the single reinforcing rib structure, the grid reinforcing rib structure is selected. The thickness of the single reinforcing rib structure is 0.8%-1.2% of the maximum length of the structural member.

[0017] As a preferred embodiment of the present invention, preferably, the thickness of the single reinforcing rib structure is 1% of the maximum length of the structural member.

[0018] As a preferred embodiment of the present invention, the rounding treatment includes rounding corner treatment and rounded corner edge treatment.

[0019] As a preferred embodiment of the present invention, the enclosed flow guiding structure includes a concentric circle structure and a concentric arc structure. The concentric circle structure is composed of a plurality of concentric annular steel bar structures, and the concentric arc structure is composed of a plurality of concentric arc-shaped steel bar structures.

[0020] As a preferred embodiment of the present invention, the interface connection structure includes a strong connection structure and a weak connection structure. The strong connection structure is suitable for regions where the stress level to be transmitted during additive manufacturing is ≥1000MPa, or regions where the thickness of the structural component is ≤6mm, corresponding to asymmetric structural parts, using force-thermal coupling numerical simulation analysis to predict the stress level to be transmitted during additive manufacturing. The strong connection structure is a rib structure. The weak connection structure is suitable for regions where the stress level to be transmitted during additive manufacturing is <1000MPa, using force-thermal coupling numerical simulation analysis to predict the stress level to be transmitted during additive manufacturing. The weak connection structure is a body-centered cubic lattice structure.

[0021] As a preferred embodiment of the present invention, the stress relief hole structure includes an arch bridge structure, a circular hole structure, an elliptical hole structure, and a triangular hole structure.

[0022] The beneficial effects of this invention are reflected in:

[0023] 1. Achieving a shift from passive resistance to active guidance in stress control: Unlike existing technologies that only locally resist or compensate for forming stress, this invention, through the pre-design of an enclosed stress propagation path and an integrated active release structure, can systematically guide and dissipate heat stress during subsequent forming processes. This significantly reduces the accumulation of residual stress in large-size structural parts during laser powder bed melting manufacturing, effectively suppressing defects such as deformation, cracking, and stress concentration that are easily caused by asymmetric structures, thereby greatly improving the dimensional accuracy and internal structure consistency of additively formed components.

[0024] 2. Possesses good structural adaptability and process versatility: The stress relief design method provided by this invention does not depend on the shape of a specific structural component. Its core lies in the design and optimization of the auxiliary structure. Therefore, it can be applied to a variety of laser powder bed melting forming tasks with complex geometric features, and has strong engineering promotion value and industrial application prospects. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a large-sized, thin-walled, narrow, and asymmetrical structural component.

[0026] Figure 2 This is a schematic diagram of the large, thin-walled, narrow, and asymmetrical structural component after symmetrical reinforcement.

[0027] Figure 3 This is a schematic diagram of the large, thin-walled, narrow, and asymmetrical structural component after being reinforced with an enclosed design.

[0028] Figure 4 This is a schematic diagram of the interface connection reinforcement of this large, thin-walled, narrow, and asymmetrical structural component.

[0029] Figure 5 This is a schematic diagram illustrating an example of a stress relief hole structure. Detailed Implementation

[0030] The invention will now be described in further detail with reference to the accompanying drawings.

[0031] Combined with appendix Figure 1-5 As shown, a method for designing stress relief and expansion paths for additive manufacturing of large-sized, thin-walled, narrow, and asymmetric structural components includes the following steps:

[0032] S1: Based on the geometric characteristics of the structural component, determine the additive forming direction of the structural component, use force-thermal coupling numerical simulation analysis to predict the deformation risk area of ​​the structural component during additive forming and obtain the initial analysis results. Preferably, the additive forming direction can also be determined in combination with the functional requirements of the structural component. The structures involved below are all based on the finite element model for mechanical analysis.

[0033] Specifically:

[0034] Using a mesh size of not less than 5 mm, the deformation risk area of ​​the structural component during additive forming is predicted by force-thermal coupling numerical simulation analysis, and the initial analysis results are obtained. The initial analysis results are based on the stress level and deformation distribution during the forming process. The deformation risk area is the area where the deformation stress during additive forming is predicted to be higher than 1000 MPa by force-thermal coupling numerical simulation analysis.

[0035] S2: Based on the asymmetric geometric features of the asymmetric structure in the structural component, a symmetrical reinforcement structure mirroring the asymmetric structure is determined. The asymmetric structure, the symmetrical reinforcement structure, and the reinforcing rib structure for strengthening the deformation risk area are determined by the deformation risk area to form the symmetrical reinforcement structure. The analysis results of the symmetrical reinforcement are obtained by force-thermal coupling numerical simulation analysis, wherein the analysis results of the symmetrical reinforcement are based on the stress level and deformation distribution during the forming process.

[0036] Specifically:

[0037] Based on the asymmetrical geometric features of the asymmetrical structure in the structural component, a structural symmetry plane is determined to be mirror-symmetrical with the asymmetrical structure. A symmetrical reinforcement structure mirror-symmetrical with the asymmetrical structure is then determined based on this structural symmetry plane. The structural symmetry plane is determined by the overall symmetry plane of the entire structure formed by the asymmetrical structure and the symmetrical reinforcement structure. The extension direction of the overall symmetry plane is consistent with the elongated extension direction of the structural component, and the entire structure is symmetrical with respect to the overall symmetry plane. Based on the geometric features of the structural component, a deflection of α° is made using one end of the overall symmetry plane as the deflection point to form the structural symmetry plane, where α≤5. The symmetrical reinforcement structure is determined through mirror symmetry. After symmetrical reinforcement, the overall configuration of the entire structure tends to or achieves complete symmetry, thereby improving the uniformity of stress distribution on a global scale and significantly reducing local stress concentration caused by structural asymmetry.

[0038] The reinforcing rib structure includes a single reinforcing rib structure and a grid reinforcing rib structure. When the dimension of the deformation risk area in a single direction is greater than three times the thickness of the single reinforcing rib structure, the grid reinforcing rib structure is selected. The thickness of the single reinforcing rib structure is 0.8%-1.2% of the maximum length of the structural component. Preferably, the thickness of the single reinforcing rib structure is 1% of the maximum length of the structural component. The maximum length of the structural component ranges from 800mm to 1200mm. The grid reinforcing rib structure is formed by splicing several single reinforcing rib structures in a grid pattern. The spacing between two adjacent single reinforcing rib structures is 0.8%-1.2% of the maximum length of the structural component. Preferably, the spacing between two adjacent single reinforcing rib structures is 1% of the maximum length of the structural component. By adding single reinforcing rib structures or grid reinforcing rib structures, targeted reinforcement is further achieved. At the same time, the increase in material weight and weight after forming are controlled while ensuring the reinforcement effect. The single reinforcing rib structure in the single reinforcing rib structure and the grid reinforcing rib structure is selected as either a circular cross-section or a rectangular cross-section, depending on the specific situation. If the cross-section is circular, the thickness is the circumferential dimension. If the cross-section is rectangular, the thickness is the direction perpendicular to the connection interface.

[0039] When using force-thermal coupling numerical simulation analysis to analyze the structure after symmetrical reinforcement, it is preferable to refine the mesh of the symmetrical reinforcement structure and the position of the stiffener structure by half the mesh size of the structural component. For example, if the structural component is divided into 2mm meshes, then the refinement process is performed using 1mm meshes.

[0040] By introducing symmetrical reinforcement design in the above way, the internal stress distribution caused by asymmetrical structure is balanced, the reinforcement position is determined, an efficient structural form is adopted and an appropriate reinforcement volume is controlled, thereby fundamentally improving the overall rigidity of the structural components and enhancing their ability to resist stress deformation.

[0041] S3: Compare the analysis results after symmetrical reinforcement with the initial analysis results. If the deformation and stress levels do not meet the preset tolerance, repeat S2 until the deformation and stress levels meet the preset tolerance and then proceed to the next step.

[0042] S4: The intersection lines of adjacent surfaces and the outer contour edges of the structure in the symmetrically reinforced structure are rounded, and a surrounding flow guiding structure is added accordingly. The surrounding flow guiding structure and the symmetrically reinforced structure are connected by an interface connection structure to form a connected reinforced structure. The analysis results of the connected reinforced structure are obtained by force-thermal coupling numerical simulation analysis. The analysis results of the connected reinforced structure are based on the stress concentration during the forming process.

[0043] Specifically, the intersection lines of adjacent surfaces and the outer contour edges of the structure are considered sharp features. Specifically, this includes all sharp edges, corners, edges, connecting edges between surfaces, and the connection points between the structural component and the substrate during printing. The rounding treatment includes rounding and rounded edge treatment. Specifically, sharp edges are rounded, connecting edges between surfaces are rounded for transition, and the connection points between the structural component and the substrate are rounded. The specific treatment selection depends on the actual sharp features. The rounding and rounded edge treatments are based on existing treatment methods with size adjustments for compatibility. For example, the rounded edge specifications for sharp edges are 0.5mm-2mm, the rounded transition specifications for connecting edges between surfaces are 1mm-4mm, and the rounded edge specifications for the connection points between the structural component and the substrate are 2mm-10mm. Rounding treatment ensures a smooth transition between the two surfaces and avoids stress concentration.

[0044] The enclosed flow guiding structure includes a concentric circle structure and a concentric arc structure. The concentric circle structure is composed of several concentric ring-shaped steel reinforcement structures, and the concentric arc structure is composed of several concentric arc-shaped steel reinforcement structures. The maximum radius of the ring-shaped steel reinforcement structures is taken as the maximum distance from the intersection line of the adjacent surfaces for enclosed reinforcement and the outermost point of the outer contour of the structure to the asymmetrical structural contour. Similarly, the maximum radius of the arc-shaped steel reinforcement structures is taken as the maximum distance from the intersection line of the adjacent surfaces for enclosed reinforcement and the outermost point of the outer contour of the structure to the asymmetrical structural contour. The thickness of the ring-shaped steel reinforcement structure and the arc-shaped steel reinforcement structure is 0.8%-1.2% of the maximum length of the structural member. Preferably, the thickness of the ring-shaped steel reinforcement structure and the arc-shaped steel reinforcement structure is 1% of the maximum length of the structural member. The ring-shaped steel reinforcement structure and the arc-shaped steel reinforcement structure can be steel reinforcement structures with circular cross-sections and rectangular cross-sections. If the cross-section is circular, the thickness is the circumferential dimension; if the cross-section is rectangular, the thickness is the direction perpendicular to the connection interface.

[0045] The enclosed flow guiding structure also includes a spherical structure, the radius of which is taken as the intersection line of the adjacent surfaces for enclosed reinforcement and the maximum distance from the outermost point of the outer contour of the structure to the contour of the asymmetric structure.

[0046] By adding an enclosing flow-guiding structure to surround the original features in a smooth shape, it is placed in a continuous smooth transition environment, providing uniform external rigid support and a clear stress transmission path for the core structural components, so as to guide the stress flow lines to diffuse evenly. By defining the enclosing area, optimizing the internal skeleton form (such as grid density and shape) and reasonably controlling its volume, the support stiffness and heat dissipation performance can be precisely controlled, and the thermo-mechanical behavior during the forming process can be precisely controlled to suppress overall deformation, further weaken local stress peaks, and strengthen the rigidity of the structural components, increasing their ability to resist deformation and cracking.

[0047] The interface connection structure includes a strong connection structure and a weak connection structure. The strong connection structure is suitable for areas where the stress level to be transmitted during additive manufacturing is predicted to be ≥1000MPa using force-thermal coupling numerical simulation analysis, or for areas corresponding to asymmetrical structural parts with a structural component thickness ≤6mm. The strong connection structure is a rib structure. Preferably, the rib structure has a circular cross-section, and its radial cross-section dimension is consistent with the radial cross-section of the annular or arc-shaped steel reinforcement structure in the enclosed flow guide structure when using circular steel reinforcement. The thickness is 0.8%-1.2% of the maximum length of the structural component, preferably 1% of the maximum length of the structural component, to ensure a stable integral connection with the body and the enclosing structure. The weak connection structure is suitable for areas where the stress level to be transmitted during additive manufacturing is predicted to be <1000MPa using force-thermal coupling numerical simulation analysis. The weak connection structure is a body-centered cubic lattice structure. Preferably, the body-centered cubic lattice structure is a three-dimensional lattice to balance lightweight and load-bearing requirements. The unit cell is a cubic unit with a size of 2mm×2mm×2mm. By arranging the unit cell in a three-dimensional array in the connection interface area, a lattice transition layer with a thickness of 0.8%-1.2% of the maximum length of the structural component is filled and generated. Preferably, a lattice transition layer with a thickness of 1% of the maximum length of the structural component is filled and generated, thus forming a body-centered cubic lattice structure of the weak connection structure. This allows for effective connection while using the deformation capability of the lattice structure to soften the interface stress. As a result, the connection interface can ensure the stability of the overall structure and optimize the stress distribution through structural form adjustment, further improving the deformation resistance and crack resistance of the structural component in the additive manufacturing process.

[0048] By setting up interface connection structures, stress can be smoothly extended. By designing reasonable interface transition structures (such as lattices and ribs) and adjusting their connection density, a low-resistance stress transfer path can be constructed from structural components to auxiliary structures, ensuring effective dissipation of internal stress and preventing deformation or cracking caused by stress concentration.

[0049] After the addition of the enclosed flow guide structure, the force-thermal coupling numerical simulation analysis of the added structure shows that the stress concentration phenomenon of the structural components has been effectively eliminated, the overall stress distribution is more uniform, and the maximum equivalent stress and deformation are significantly reduced.

[0050] S5: Based on the analysis results after the connection reinforcement, if the stress concentration phenomenon in the analysis results is eliminated, the design ends; if the stress concentration phenomenon in the analysis results is not eliminated, stress relief hole structures are added to the area corresponding to the stress concentration phenomenon and the non-functional area of ​​the structural component until the stress concentration phenomenon is eliminated.

[0051] The stress relief hole structure includes arch bridge structure, circular hole structure, elliptical hole structure and triangular hole structure. The stress relief hole structure is configured in the additive manufacturing process. Through its own preferential plastic deformation or preset local deformation, it actively absorbs and releases the accumulated thermal stress and residual stress, thereby avoiding the uncontrollable concentration and release of stress in the structural part body during forming, further reducing the risk of overall cracking and deformation, and ensuring the stability of the structural part forming process. The radius of the top arc of the cavity of the stress relief hole structure along the forming direction does not exceed 0.25% of the maximum length of the structural part. The specific shape and layout can be designed according to the characteristics of the local stress field. The non-functional area of ​​the structural part is the process allowance. The process allowance is set to ensure the smooth forming of large-size structural parts.

[0052] For large-sized, thin-walled, elongated, asymmetric structural components, the main risks in laser powder bed fusion forming are concentrated on deformation and crack control. Specifically, these risks can be explained from two dimensions: In terms of size, the enormous forming volume and extremely long forming time lead to a strong heat accumulation effect, causing the structural component to generate huge internal stresses during cooling, which easily triggers macroscopic deformation and cracks. In terms of structure, the extremely thin wall thickness results in weak rigid constraints on the structural component, and the uneven thermal-mechanical distribution caused by the asymmetric design together determine the inherent instability of the structural component, making it significantly prone to deformation and tensile cracking under residual stress.

[0053] By starting with structural optimization, the above methods address the issue that asymmetric structures, during additive manufacturing, suffer from uneven heating and cooling rates in different regions. Regions that cool quickly experience greater shrinkage, which in turn generates tensile stress in slower-cooling regions, making them prone to deformation and even cracking. Therefore, it is necessary to add symmetrical reinforcement features to provide more balanced constraints on the thermal deformation of the structural components. This allows for a more uniform distribution of internal stress generated during the solidification and cooling of the molten pool, effectively reducing stress concentration in weak areas of the asymmetric structure. This significantly improves structural stability during the forming process and reduces the risk of deformation and cracking.

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for designing stress relief and expansion paths before additive manufacturing of large-sized, thin-walled, narrow, asymmetric structural components, characterized in that, Includes the following steps: S1: Based on the geometric characteristics of the structural component, determine the additive forming direction of the structural component, and use force-thermal coupling numerical simulation analysis to predict the deformation risk area during additive forming of the structural component and obtain the initial analysis results; S2: Based on the asymmetric geometric features of the asymmetric structure in the structural component, a symmetrical reinforcement structure mirroring the asymmetric structure is determined. The asymmetric structure, the symmetrical reinforcement structure, and the stiffening rib structure for reinforcing the deformation risk area determined by the deformation risk area constitute the symmetrical reinforcement structure. The analysis results of the symmetrical reinforcement are obtained by force-thermal coupling numerical simulation analysis. S3: Compare the analysis results after symmetrical reinforcement with the initial analysis results. If the deformation and stress levels do not meet the preset tolerance, repeat S2 until the deformation and stress levels meet the preset tolerance and then proceed to the next step. S4: Round the corners of the intersection lines of adjacent surfaces and the outer contour of the structure in the symmetrically reinforced structure, and add a corresponding enclosed flow guiding structure. Use the interface connection structure to connect the enclosed flow guiding structure and the symmetrically reinforced structure to form a connected reinforced structure, and use force-thermal coupling numerical simulation analysis to obtain the analysis results of the connected reinforced structure. S5: Based on the analysis results after the connection reinforcement, if the stress concentration phenomenon in the analysis results is eliminated, the design ends. If the stress concentration phenomenon in the analysis results is not eliminated, stress relief hole structures are added to the area corresponding to the stress concentration phenomenon and the non-functional area of ​​the structural component until the stress concentration phenomenon is eliminated.

2. The method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 1, characterized in that: The S1 section utilizes force-thermal coupled numerical simulation analysis to predict the deformation risk area during additive forming of the structural component and obtain initial analysis results, specifically including: Using a mesh size of not less than 5 mm, force-thermal coupling numerical simulation analysis was used to predict the deformation risk area of ​​the structural component during additive forming and obtain initial analysis results.

3. The method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 1, characterized in that: In step S2, determining the symmetrical reinforcement structure that is mirror-symmetrical to the asymmetrical structure based on the asymmetrical geometric features of the asymmetrical structure in the structural component specifically includes: Based on the asymmetrical geometric features of the asymmetrical structure in the structural component, a structural symmetry plane is determined to be mirror-symmetrical to the asymmetrical structure. Based on the structural symmetry plane, a symmetrical reinforcement structure mirror-symmetrical to the asymmetrical structure is determined. The structural symmetry plane is determined by the overall symmetry plane of the overall structure formed by the asymmetrical structure and the symmetrical reinforcement structure. The extension direction of the overall symmetry plane is consistent with the elongated extension direction of the structural component, and the overall structure is symmetrical with respect to the overall symmetry plane. Based on the geometric features of the structural component, the structural symmetry plane is formed by deflecting the overall symmetry plane by α° with one end as the deflection point, where α≤5.

4. The method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 1, characterized in that: The deformation risk area is the region where the deformation stress during additive manufacturing is predicted to be higher than 1000 MPa through force-thermal coupling numerical simulation analysis.

5. The method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 4, characterized in that: The reinforcing rib structure includes a single reinforcing rib structure and a grid reinforcing rib structure. When the dimension of the deformation risk area in a single direction is greater than three times the thickness of the single reinforcing rib structure, the grid reinforcing rib structure is selected. The thickness of the single reinforcing rib structure is 0.8%-1.2% of the maximum length of the structural member.

6. The method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 5, characterized in that: Preferably, the thickness of the single reinforcing rib structure is 1% of the maximum length of the structural member.

7. The method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 1, characterized in that: The rounding process includes rounding the corners and rounding the edges.

8. The method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 1, characterized in that: The enclosed flow guiding structure includes a concentric circle structure and a concentric arc structure. The concentric circle structure is composed of several concentric ring-shaped steel reinforcement structures, and the concentric arc structure is composed of several concentric arc-shaped steel reinforcement structures.

9. A method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, asymmetric structural components according to claim 8, characterized in that: The interface connection structure includes a strong connection structure and a weak connection structure. The strong connection structure is suitable for regions where the stress level to be transmitted during additive manufacturing is ≥1000MPa, or regions where the thickness of the structural component is ≤6mm, corresponding to asymmetric structural parts, using force-thermal coupling numerical simulation analysis to predict the stress level to be transmitted during additive manufacturing. The strong connection structure is a rib structure. The weak connection structure is suitable for regions where the stress level to be transmitted during additive manufacturing is <1000MPa, using force-thermal coupling numerical simulation analysis to predict the stress level to be transmitted during additive manufacturing. The weak connection structure is a body-centered cubic lattice structure.

10. A method for designing stress relief and expansion paths for additive manufacturing of large-size, thin-walled, narrow, and asymmetric structural components according to claim 1, characterized in that: The stress relief hole structure includes an arch bridge structure, a circular hole structure, an elliptical hole structure, and a triangular hole structure.

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