Design method for steel plate crack damage additive manufacturing single-face repair

Abstract

The invention relates to a design method for steel plate crack damage additive manufacturing single-side repair, which comprises the following steps of: setting geometric and material parameters of a crack damage steel plate and a repair body, and determining a load state to calculate von Mises stress distribution of the steel plate under an undamaged condition; then, calculating the maximum reference semi-elliptical section of the restoration body in the direction perpendicular to the crack based on the thickness, the strength ratio and the crack width of the steel plate; determining the overall length of the restoration body along the crack direction according to the crack length; and finally, in combination with the maximum reference section and the stress distribution, calculating the variable cross-section size distribution of the restoration in the crack direction through a stress ratio function, and generating a semi-elliptical variable cross-section three-dimensional restoration model matched with the internal stress of the steel plate. Compared with the prior art, the method solves the problems that when the crack damage of the steel structure is repaired through metal additive manufacturing, a restoration body lacks a unified geometric description model, and calculation and design are not reliable.

Description

Technical Field

[0001] This invention relates to the fields of steel structure damage repair and metal additive manufacturing, and in particular to a design method for single-sided additive manufacturing repair of steel plate crack damage. Background Technology

[0002] Steel structures are susceptible to fatigue loads, corrosion, and accidental impacts during long-term service, leading to localized cracks or defects. If such damage is not repaired promptly, it can reduce the load-bearing capacity of components and even jeopardize the overall structural safety and durability. As described in prior art document CN119622892A, traditional crack propagation prediction methods primarily rely on laboratory tests, empirical formulas, and finite element analysis. These methods suffer from limitations such as laboratory tests failing to fully simulate actual working environments, empirical formulas having limited accuracy due to data representativeness, and finite element analysis being computationally intensive and time-consuming. These issues result in inaccurate crack predictions, further increasing the difficulty and uncertainty of repair.

[0003] Currently used repair methods include welding reinforcement, hole unloading (crack arresting holes), steel plate bonding, and carbon fiber reinforced composite material reinforcement. Although the above repair technologies have been applied to some extent in engineering practice, they generally suffer from problems such as poor geometric adaptability to complex cracks, insufficient on-site workability, low level of automation, and difficulty in in-situ repair.

[0004] With the development of metal additive manufacturing technology, its high geometrical freedom, excellent material compatibility, and in-situ forming capabilities have provided a new solution for repairing crack damage in steel structures. However, due to the high cost of metal additive manufacturing materials, improving material utilization efficiency while ensuring repair effectiveness remains a challenge. Furthermore, while its high geometrical freedom allows for the creation of complex surface morphologies and designs that match the stress distribution in the cracked area, the geometric design of additively manufactured repair components is still in the exploratory stage. A universally applicable unified three-dimensional geometric model has not yet been established, and corresponding calculation formulas and design methods are lacking, hindering the application and widespread adoption of this technology in engineering.

[0005] Therefore, how to solve the problem of the lack of a unified geometric description model for the repair body and the unreliability of calculation and design when repairing crack damage in steel structures using metal additive manufacturing has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a design method for single-sided repair of steel plate crack damage using additive manufacturing. This method solves the problem that the repair body lacks a unified geometric description model and the calculation and design are unreliable when repairing crack damage in steel structures using metal additive manufacturing.

[0007] The objective of this invention can be achieved through the following technical solutions: This invention provides a design method for single-sided repair of crack damage in steel plates using additive manufacturing, comprising the following steps: S1. Set the geometric parameters and material parameters of the cracked steel plate and the material parameters of the repair body. The geometric parameters include the steel plate thickness, crack length and crack width. The material parameters include the yield strength and tensile strength of the steel plate and the yield strength and tensile strength of the repair body. S2. Based on the parameters set in S1, set the load state of the cracked steel plate and calculate the von Mises stress distribution inside the steel plate under the assumption of no damage. S3. Based on the geometric and material parameters of the cracked steel plate set in S1, calculate the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction. The height semi-axis length of the maximum reference semi-elliptical cross section is calculated based on the steel plate thickness and strength ratio, and the width semi-axis length is calculated based on the steel plate thickness, strength ratio and crack width. S4. Calculate the overall length of the repair body along the crack direction based on the crack length in S1; S5. Based on the maximum reference semi-elliptical cross section calculated in S3 and the von Mises stress distribution calculated in S2, calculate the cross-sectional dimension variation distribution of the repair body along the crack direction, and combine it with the overall length of the repair body along the crack direction obtained in S4 to generate a design scheme.

[0008] Furthermore, in S2, the von Mises stress distribution is calculated using finite element analysis or based on fundamental mechanical principles.

[0009] Furthermore, in S2, the von Mises stress distribution inside the steel plate is calculated under the assumption of no damage, and the process includes: Based on the set load state, when using elastic design, the elastic stress distribution is calculated based on the yield strength of the steel plate; When using plastic design, the plastic stress distribution is calculated based on the tensile strength of the steel plate; the stress distribution is calculated using the finite element method or an analytical method based on fundamental mechanical principles.

[0010] Furthermore, in S3, the height semi-axis length of the maximum reference semi-elliptical section is specifically calculated by multiplying the product of the steel plate thickness and the strength ratio by a first preset coefficient. The width and semi-axis length of the maximum reference semi-elliptical section are specifically calculated by multiplying the product of the steel plate thickness and the strength ratio to a power by a second preset coefficient and then adding half of the crack width. Furthermore, in S3, the strength ratio is defined as the ratio of the yield strength of the steel plate to the yield strength of the repair body in elastic design, and as the ratio of the tensile strength of the steel plate to the tensile strength of the repair body in plastic design.

[0011] Furthermore, in S4, the overall length of the repair body along the crack direction is calculated based on the crack length in S1. The specific process includes multiplying the crack length by a predetermined coefficient greater than 1 to obtain the overall length of the repair body.

[0012] Furthermore, in S5, based on the maximum reference semi-elliptical cross section calculated in S3 and the von Mises stress distribution calculated in S2, the cross-sectional dimension variation distribution of the repaired body along the crack direction is calculated. The specific process includes: Based on the local and maximum von Mises stresses at various locations along the crack direction obtained from S2, the stress ratios at each location are calculated, and the minimum stress ratio is set to 0.6. Then, the stress ratio at each location is multiplied by the height semi-axis length and width semi-axis length of the maximum reference semi-elliptical section determined by S3, to obtain the actual height semi-axis length and actual width semi-axis length of the section at each corresponding position along the crack direction of the repair body, thereby determining the continuous variation distribution law of the section size.

[0013] Furthermore, in S5, and combining the overall length of the repair body along the crack direction obtained in S4, a design scheme is generated. The specific process includes: Based on the maximum reference semi-elliptical cross-sectional shape determined by S3, the cross-sectional dimension variation law calculated by the stress distribution obtained by S2, and the overall length determined by S4, a three-dimensional columnar structure model of a semi-elliptical variable cross-section extending along the crack direction and with continuously varying cross-sectional dimensions is constructed. This model is the final design scheme.

[0014] Furthermore, in S5, a three-dimensional geometric model of the repair body is finally generated. The three-dimensional geometric model is a semi-elliptical variable cross-section columnar structure extending along the crack direction, whose cross-sectional dimensions change continuously and match the stress distribution inside the steel plate.

[0015] Furthermore, the design method is applicable to various stress states and various structural conditions, wherein the various stress states include at least one of uniformly distributed stress and gradient stress, and the various structural conditions include at least one of tensile conditions and bending conditions.

[0016] In a preferred embodiment of the present invention, the first preset coefficient is used to calculate the height semi-axis length of the maximum reference semi-elliptical cross section of the repair body, and its value is fixed at 1.8; the second preset coefficient is used to calculate the width semi-axis length, and its value is fixed at 1.6. These coefficients are combined with the steel plate thickness and strength ratio to determine the cross-sectional dimensions. In a preferred embodiment of the present invention, a predetermined coefficient is used to calculate the overall length of the repair body along the crack direction, and its value is fixed at 1.1. The repair range is expanded by multiplying it by the crack length. The minimum value of the stress ratio is limited to 0.6, which is used to control the distribution of cross-sectional size changes.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1) The method of this invention first calculates the von Mises stress distribution of the undamaged steel plate, and then designs the variable cross-sectional dimensions of the repair body along the crack direction based on this stress distribution, so that the geometry of the repair body precisely matches the actual stress state inside the steel plate. This stress-directed design can ensure that the repair body can more effectively transfer and redistribute the load when under load, significantly reducing stress concentration at the edge of the repair area, thereby fundamentally improving the fatigue life and static load-bearing capacity of the repair joint.

[0018] 2) The entire design process of this invention is based on quantitative calculations using clearly defined geometric and material parameters. From the maximum reference cross-section to continuous variations along the length, there is a clear mathematical basis, replacing traditional empirical, constant-section repair designs. This not only makes the repair structure more rational, achieving optimized material distribution while meeting strength requirements, saving expensive additive manufacturing materials, and reducing costs, but also forms a systematic, universal, and repeatable design process applicable to various stress conditions. It can directly output three-dimensional models for manufacturing, greatly improving the scientific rigor, reliability, and engineering application efficiency of single-sided repair design. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a cracked steel plate and its working condition in an embodiment of the present invention; Figure 2 This is a schematic diagram of the repair structure model construction and design method for single-sided additive manufacturing repair of steel plate crack damage provided by the present invention; Figure 3 This is a schematic diagram illustrating the stress condition of a crack-damaged steel plate under elastic design in an embodiment of the present invention. Figure 4 This is a schematic diagram illustrating the stress condition of a crack-damaged steel plate under plastic design in an embodiment of the present invention. Figure 5 This is a schematic diagram of the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction under the elastic design in an embodiment of the present invention; Figure 6 This is a schematic diagram of the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction under plastic design in an embodiment of the present invention; Figure 7 This is a schematic diagram of a cross-section of the repair body parallel to the crack direction under the elastic design in an embodiment of the present invention; Figure 8 This is a three-dimensional schematic diagram of the entire steel plate after repair under the elastic design in an embodiment of the present invention; Figure 9 This is a schematic diagram of a cross-section of the repair body parallel to the crack direction under plastic design in an embodiment of the present invention; Figure 10 This is a three-dimensional schematic diagram of the entire steel plate after repair under plastic design in an embodiment of the present invention. Detailed Implementation

[0020] Overall, this invention aims to address the shortcomings of existing technologies in repairing cracks in steel structures using metal additive manufacturing, which lack a unified geometric description model for the repair body and suffer from unreliable computational design. By providing a systematic single-sided repair design method, the core of which lies in dynamically adjusting the geometry of the repair body based on the stress distribution inside the steel plate, thereby achieving a precise match between the stress state of the repair body and the parent material.

[0021] The method of this invention first sets the geometric parameters of the cracked steel plate, such as plate thickness, crack length, and crack width, as well as the material parameters, such as the yield strength and tensile strength of the steel plate and the corresponding strength values ​​of the repair body. Then, based on the load state of the steel plate, the von Mises stress distribution inside the steel plate is calculated under the assumption of no damage. This stress distribution can be obtained through finite element calculation or basic mechanical principles. In elastic design, the elastic stress distribution is calculated based on the yield strength, and in plastic design, the plastic stress distribution is calculated based on the tensile strength. Next, based on the geometric and material parameters, the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction is calculated. The height semi-axis length of this cross section is calculated by multiplying the product of the steel plate thickness and the strength ratio by a first preset coefficient, and the width semi-axis length is calculated by multiplying the product of the steel plate thickness and the strength ratio raised to a power by a second preset coefficient and adding half of the crack width. The strength ratio is the ratio of the yield strength of the steel plate and the repair body in elastic design and the ratio of the tensile strength in plastic design, thereby ensuring that the cross-sectional dimensions match the material strength.

[0022] Subsequently, the overall length of the repair body along the crack direction is calculated by multiplying the crack length by a predetermined coefficient greater than 1 to cover the crack area and provide sufficient repair range. Finally, the cross-sectional size variation distribution of the repair body along the crack direction is calculated based on the maximum reference semi-elliptical cross section and the von Mises stress distribution. The stress ratio is obtained by using the ratio of the local von Mises stress at each location to the maximum stress and limiting the minimum value. Then, the stress ratio is multiplied by the height semi-axis length and width semi-axis length of the maximum reference cross section to obtain the actual cross-sectional size at each location, thereby generating a three-dimensional columnar structure model of a semi-elliptical variable cross section that extends along the crack direction and has continuously changing cross-sectional size.

[0023] The stress-directed design mechanism in this invention enables the geometry of the repair body to respond in real time to the complex stress state inside the steel plate, more effectively transferring and redistributing loads during load-bearing, significantly reducing stress concentration at the edges of the repair area, thereby improving the fatigue life and static load-bearing capacity of the repair joint. At the same time, the entire design process is based on quantitative calculation to replace empirical design, achieving optimized material distribution, saving additive manufacturing material costs, and forming a universal and repeatable design process applicable to various stress states such as uniformly distributed stress and gradient stress, as well as various structural conditions such as tensile and bending conditions. Finally, the direct output of a three-dimensional model is used to guide actual operation, improving the scientific nature of the design and the efficiency of engineering applications.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0025] Example 1 This embodiment proposes a three-dimensional geometric model and its design method for single-sided repair of cracked steel plates using additive manufacturing, based on the structural morphology calculated by topology optimization. This method has undergone comprehensive finite element simulation verification. By proposing a three-dimensional geometric model and its design method, this embodiment achieves accurate calculation of the geometric parameters of the repair body, significantly improves material utilization efficiency, and ensures that the repair component matches the complex stress distribution in the cracked region, thereby enhancing the reliability and scalability of metal additive manufacturing repair design.

[0026] See Figure 1 The model design method in this embodiment includes the following five steps: Set the geometric and material parameters of the cracked steel plate and the material parameters of the repair body; Define the load state of the crack-damaged steel plate and calculate the internal stress distribution of the steel plate; Calculate the maximum reference semi-elliptical cross section perpendicular to the crack direction based on geometric and material parameters; Calculate the overall length of the three-dimensional repair structure based on the length of the crack in the steel plate; The variation distribution of the cross-sectional dimensions of the repair structure parallel to the crack direction is calculated based on the maximum reference semi-elliptical cross section and the internal stress distribution of the steel plate.

[0027] Step (1) further comprises: setting the thickness of the crack-damaged steel plate according to the actual damage to the steel structure. T、 Crack length l c Crack width b c Yield strength ,tensile strength The yield strength of the repair is determined based on the selected metal additive manufacturing material. and tensile strength .

[0028] Step (2) further involves: determining the von Mises stress distribution of the cracked steel plate under the assumed undamaged condition based on the actual load state of the damaged steel structure; calculating the elastic stress distribution using elastic design and the plastic stress distribution using plastic design. The stress distribution can be obtained from basic mechanical principles or finite element analysis.

[0029] Step (3) further comprises: constructing the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction based on the geometric and material parameters of the damaged steel plate and the material parameters of metal additive manufacturing. The mathematical expression of this cross section is defined as: In the formula, R h,max The maximum reference section height is the semi-axis length. R b,max The maximum reference section width and semi-axis length y Let these be the coordinates of a point perpendicular to the plane. z Let be the coordinates of a point within the plate surface perpendicular to the crack direction. R h,max and R b,max The calculation formula is defined as follows: In the formula, t For the thickness of the steel plate that will cause cracks, μ The strength ratio of the steel plate to the repair structure. b c The crack width is... μ The calculation formula is defined as follows: In the formula, when performing elastic design, and Yield strength of cracked steel plates and repair materials and When performing plastic design, and Tensile strength of cracked steel plates and repair materials and .

[0030] Step (4) further comprises: calculating the overall length of the three-dimensional repair structure along the crack direction based on the crack length of the steel plate, using the following formula: in, l c The crack length is given.

[0031] Step (5) further comprises: at any position perpendicular to the crack length direction, the cross-sectional shape of the repair body is always a scaling of the maximum reference semi-elliptical cross-section, the size of which can be calculated by the von Mises stress under the undamaged condition at that position obtained in step (2), and its cross-sectional mathematical expression is defined as: in, R hx For any position x Half-axis of the section height R bx For any position x The width of the cross section is half of the axis. R hx and R bx Defined as: in, The cross-sectional stress ratio is defined as: in, Location of the crack x At the point where the cracked plate is assumed to have local von Mises stress under undamaged conditions, The maximum von Mises stress is assumed to be under the condition of no damage for the cracked plate.

[0032] The three-dimensional geometric model established in this embodiment is based on parameters such as steel plate thickness, material strength ratio, and stress distribution. It can quantitatively determine the height and width semi-axis of the repair body section, avoiding the uncertainty caused by relying on empirical design.

[0033] This embodiment establishes a semi-elliptical cross-section configuration based on a topology optimization geometric model and introduces a stress ratio function ψ to control the cross-sectional changes of the repair body along the crack direction, thereby achieving preferential material distribution in the stress concentration region. This significantly reduces the amount of additive manufacturing material used while ensuring the repair effect and fully utilizes the geometric freedom advantage of metal additive manufacturing technology.

[0034] The three-dimensional geometric repair structure established in this embodiment can match the complex crack morphology and stress field, effectively avoiding local stress concentration and improving the coordination between the repair component and the base material.

[0035] The three-dimensional geometric repair model and design method established in this embodiment have been verified by a large number of finite element simulations, which can ensure that the strength of the repaired steel plate is restored to the strength of the steel plate before the damage, and has structural reliability and safety.

[0036] The three-dimensional geometric repair model established in this embodiment is applicable to various stress states such as uniformly distributed stress and gradient stress, and corresponds to various structural conditions such as tensile and bending resistance. The resulting repair structure has a clear shape and controllable parameters, and has good feasibility for additive manufacturing and promotion and application value.

[0037] Application Example 1 This application example uses a steel plate with crack damage subjected to in-plane bending moment as a design problem, such as... Figure 1 As shown, the damaged steel plate is 400mm long, 200mm wide, and 10mm thick, with a strength grade of Q355. The damage crack is 0.6mm wide and 50mm long, extending from the edge of the plate along its width towards the center. The design utilizes additively manufactured steel with a strength grade of ER70-S for structural repair. Ignoring second-order effects, a repair model is constructed under simple elastic and plastic design conditions, and calculation formulas are provided.

[0038] Please see Figure 2 The model construction and design method provided by this invention mainly includes the following steps: Step 1: Set the length of the steel plate damaged by cracks L = 400mm, width B = 200mm, thickness t = 10mm 、 Crack length l c =50mm, crack width b c = 0.6mm, yield strength = 355MPa, tensile strength = 490MPa and the yield strength of the restoration = 400MPa and tensile strength = 490MPa; Step Two: Establish a coordinate system centered on the crack initiation point, where x The axis is along the width of the plate. y The axis is the axis along the length of the plate. z The axis is perpendicular to the plane of the plate.

[0039] Further as Figure 3As shown, for a cracked steel plate subjected to in-plane bending moment, the internal stress of the corresponding undamaged steel plate under simple elastic conditions can be simplified to a linear gradient distribution, which can be represented by the following formula: like Figure 4 As shown, for a cracked steel plate subjected to in-plane bending moment, the internal stress of the corresponding undamaged steel plate under simple plastic conditions can be conservatively estimated as a bidirectional uniform distribution, and its distribution state can be expressed by the following formula: Step 3: like Figure 5 As shown, the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction under elastic design can be calculated using the following set of formulas: The formula for calculating the maximum reference semi-elliptical cross-sectional profile under elastic design is then obtained (unit: mm): like Figure 6 As shown, the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction under plastic design can be calculated using the following set of formulas: The formula for calculating the maximum reference semi-elliptical cross-sectional profile under plastic design is then obtained (unit: mm): Step Four: The cross-section of the repair parallel to the crack direction is continuously formed by a semi-elliptical cross-section perpendicular to the crack direction, and its length can be calculated by the following formula (unit: mm): Step 5: The stress ratio of any section of the repair body parallel to the crack direction under elastic design can be calculated over the length of the repair body as follows: The arbitrary semi-elliptical cross section of the repair body perpendicular to the crack direction under elastic design can be calculated using the following set of formulas (unit: mm): The calculation formula for the prosthesis model under elastic design can then be obtained as follows (unit: mm): Figure 7 This is a schematic diagram of a cross-section of the repair body parallel to the crack direction, based on the above formula. Figure 8 This is a three-dimensional schematic diagram of the entire repaired steel plate based on the above formula.

[0040] The stress ratio of any section of the repair body parallel to the crack direction under plastic design can be calculated over the length of the repair body as follows: Then, any semi-elliptical cross section of the repair body perpendicular to the crack direction under plastic design can be calculated by the following set of formulas (unit: mm): The calculation formula for the prosthesis model under plastic design can then be obtained as follows (unit: mm): Figure 9 This is a schematic diagram of a cross-section of the repair body parallel to the crack direction, based on the above formula. Figure 10 This is a three-dimensional schematic diagram of the entire repaired steel plate based on the above formula.

[0041] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A design method for single-sided repair of crack damage in steel plates using additive manufacturing, characterized in that, Includes the following steps: S1. Set the geometric parameters and material parameters of the cracked steel plate and the material parameters of the repair body. The geometric parameters include the steel plate thickness, crack length and crack width. The material parameters include the yield strength and tensile strength of the steel plate and the yield strength and tensile strength of the repair body. S2. Based on the parameters set in S1, set the load state of the cracked steel plate and calculate the von Mises stress distribution inside the steel plate under the assumption of no damage. S3. Based on the geometric and material parameters of the cracked steel plate set in S1, calculate the maximum reference semi-elliptical cross section of the repair body perpendicular to the crack direction. The height semi-axis length of the maximum reference semi-elliptical cross section is calculated based on the steel plate thickness and strength ratio, and the width semi-axis length is calculated based on the steel plate thickness, strength ratio and crack width. S4. Calculate the overall length of the repair body along the crack direction based on the crack length in S1; S5. Based on the maximum reference semi-elliptical cross section calculated in S3 and the von Mises stress distribution calculated in S2, calculate the cross-sectional dimension variation distribution of the repair body along the crack direction, and combine it with the overall length of the repair body along the crack direction obtained in S4 to generate a design scheme.

2. The design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, In S2, the von Mises stress distribution is calculated using finite element analysis or based on fundamental mechanical principles.

3. The design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 2, characterized in that, In S2, the calculation of the von Mises stress distribution inside the steel plate under the assumption of no damage includes the following process: Based on the set load state, when using elastic design, the elastic stress distribution is calculated based on the yield strength of the steel plate; When using plastic design, the plastic stress distribution is calculated based on the tensile strength of the steel plate; the stress distribution is calculated using the finite element method or an analytical method based on fundamental mechanical principles.

4. The design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, In S3, the height of the semi-elliptical section of the maximum reference section is specifically calculated by multiplying the product of the steel plate thickness and the strength ratio by a first preset coefficient. The width and semi-axis length of the maximum reference semi-elliptical section are specifically calculated by multiplying the product of the steel plate thickness and the strength ratio to the power of the product by a second preset coefficient and then adding half of the crack width.

5. The design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, In S3, the strength ratio is defined as the ratio of the yield strength of the steel plate to the yield strength of the repair body in elastic design, and as the ratio of the tensile strength of the steel plate to the tensile strength of the repair body in plastic design.

6. The design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, In S4, the overall length of the repair body along the crack direction is calculated based on the crack length in S1. The specific process includes multiplying the crack length by a predetermined coefficient greater than 1 to obtain the overall length of the repair body.

7. The design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, In S5, based on the maximum reference semi-elliptical cross section calculated in S3 and the von Mises stress distribution calculated in S2, the cross-sectional dimension variation distribution of the repaired body along the crack direction is calculated. The specific process includes: Based on the local and maximum von Mises stresses at various locations along the crack direction obtained from S2, the stress ratios at each location are calculated, and the minimum stress ratio is set to 0.

6. Then, the stress ratio at each location is multiplied by the height semi-axis length and width semi-axis length of the maximum reference semi-elliptical section determined by S3, to obtain the actual height semi-axis length and actual width semi-axis length of the section at each corresponding position along the crack direction of the repair body, thereby determining the continuous variation distribution law of the section size.

8. A design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, In S5, and combining the overall length of the repair body along the crack direction obtained in S4, a design scheme is generated. The specific process includes: Based on the maximum reference semi-elliptical cross-sectional shape determined by S3, the cross-sectional dimension variation law calculated by the stress distribution obtained by S2, and the overall length determined by S4, a three-dimensional columnar structure model of a semi-elliptical variable cross-section extending along the crack direction and with continuously varying cross-sectional dimensions is constructed. This model is the final design scheme.

9. A design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, In S5, a three-dimensional geometric model of the repair body is finally generated. The three-dimensional geometric model is a semi-elliptical variable cross-section columnar structure extending along the crack direction. Its cross-sectional dimensions change continuously and match the stress distribution inside the steel plate.

10. A design method for single-sided repair of steel plate crack damage in additive manufacturing according to claim 1, characterized in that, The design method is applicable to various stress states and various structural conditions, wherein the various stress states include at least one of uniformly distributed stress and gradient stress, and the various structural conditions include at least one of tensile conditions and bending conditions.

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