Metal SLM forming anti-deformation and support reducing design method

Abstract

The present application relates to the technical fields of additive manufacturing design, in particular to a metal SLM forming anti-deformation and support-reducing conformal control thin plate design method, comprising: collecting target thin plate part geometric model data and SLM forming process parameter data, the geometric model data containing thin plate thickness distribution field and curved surface curvature distribution diagram. An improved thin shell finite element analysis algorithm based on the classical thin shell theory balance differential equation is used to generate the thermal force coupling deformation prediction field of the part layer-by-layer scanning. According to the node displacement amount and element warping angle of the prediction field, the easy-to-deform region coordinate set and the support-required region boundary line are determined, the topology configuration parameters containing the reinforcing rib layout track, the thin plate thickness gradual change mapping table are generated, and the original model is embedded to form a composite thin plate model. The method can accurately deduce the thin plate forming deformation law, match the component deformation characteristics to complete the structure optimization, weaken the forming distortion, and simplify the support structure layout.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing design technology, and in particular to a method for designing thin plates with anti-deformation and support reduction in metal SLM forming. Background Technology

[0002] Metal sheet metal forming technology (SLM) is widely used in the processing and manufacturing of thin sheet metal parts. Current thin sheet shape control design often employs a combination of conventional finite element simulation and empirical configuration design. Conventional simulations typically use general solid finite element solution models, failing to build a dedicated analysis system based on thin shell theory. This allows for only a rough assessment of the overall forming deformation of the thin sheet, and cannot accommodate the differences in mechanical response caused by the thickness distribution field and surface curvature distribution of the thin sheet, nor can it adapt to the mechanical changes characteristic of layer-by-layer forming in the SLM process.

[0003] Conventional analysis methods struggle to fully reconstruct the coupled changes in temperature and stress fields during the forming process, failing to generate a comprehensive and refined thermo-mechanical coupling deformation prediction field. Existing designs cannot accurately define the coordinate range of easily deformable areas and the boundaries of support areas in thin plates based on deformation data; wall thickness settings and support layouts are all standardized. Traditional design methods cannot match corresponding structural configuration parameters based on local deformation differences in parts, easily leading to dimensional deviations and morphological distortions in the formed structure. Redundant support structures increase the processing load. The industry lacks dedicated finite element analysis tools adapted to thin plate components, as well as standardized design methods for generating conformal topological configuration parameters based on deformation characteristics. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and propose a design method for metal SLM forming of anti-deformation and support-reducing conformal shape control thin plates.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for designing a conformal shape control thin plate with anti-deformation and reduced support in metal SLM forming, comprising: Collect geometric model data and SLM forming process parameter data of the target thin plate part. The geometric model data includes the thickness distribution field and surface curvature distribution map of the thin plate. An improved thin-shell finite element analysis algorithm is executed on the geometric model data. The improved thin-shell finite element analysis algorithm is constructed based on the equilibrium differential equation of classical thin-shell theory to generate the thermo-mechanical coupling deformation prediction field of the target thin-plate part during the layer-by-layer scanning process. Based on the nodal displacement and unit warping angle in the thermo-coupled deformation prediction field, the coordinate set of the easily deformable region and the boundary line of the region requiring support of the target thin plate part are determined. Based on the coordinate set of the easily deformable region and the boundary line of the region requiring support, the topological configuration parameters of the conformal control thin plate are generated. The topological configuration parameters include the spatial layout trajectory of the stiffeners and the thickness gradient mapping table of the thin plate. The topological configuration parameters of the conformal control sheet are embedded into the original geometric model of the target sheet part to generate a composite sheet model containing conformal control features.

[0006] As a further aspect of the present invention, an improved thin-shell finite element analysis algorithm is executed on the geometric model data. This improved algorithm is based on the equilibrium differential equations of classical thin-shell theory and generates a predicted thermo-mechanical coupling deformation field for the target thin-plate part during the layer-by-layer scanning process, including: The neutral surface geometric parameters and the thickness distribution field of the target thin plate part are extracted from the geometric model data. The neutral surface geometric parameters include the neutral surface spatial coordinates and the neutral surface normal vector. Based on the neutral surface geometric parameters and the thin plate thickness distribution field, the target thin plate part is discretized into multiple thin shell elements, each of which contains three corner nodes and one thickness integration point; For each thin-shell unit, the laser scanning path and laser energy density value are extracted from the SLM forming process parameter data, and the transient temperature load of the thin-shell unit in the time series is calculated based on the laser scanning path and laser energy density value. The transient temperature load is applied to the three corner nodes of the thin shell element. By solving the equilibrium differential equation in the improved thin shell finite element analysis algorithm, the displacement components of each corner node in three spatial directions are obtained. The displacement components of all corner nodes of all thin-shell units are assembled into field quantities to generate a node displacement cloud map covering the entire geometric region of the target thin-plate part, which serves as the thermo-mechanical coupling deformation prediction field.

[0007] As a further aspect of the present invention, by solving the equilibrium differential equations in the improved thin-shell finite element analysis algorithm, the displacement components of each corner node in three spatial directions are obtained, including: For the current thin-shell unit, extract the initial coordinates of the three corner nodes of the current thin-shell unit and the temperature gradient value at the thickness integration point of the current thin-shell unit; Based on the temperature gradient value and the material thermal expansion coefficient of the target thin plate part, calculate the thermal strain tensor components inside the current thin shell unit; The thermal strain tensor components are converted into equivalent nodal thermal load vectors, and the equivalent nodal thermal load vectors are superimposed on the external force load terms of the equilibrium differential equation. The Kirchhoff assumption of thin shell theory is introduced into the geometric equation of the equilibrium differential equation. The Kirchhoff assumption stipulates that the normal to the neutral surface remains straight and perpendicular to the neutral surface after deformation during the deformation of the thin shell. Based on the Kirchhoff assumption, the equilibrium differential equation is discretized using Galerkin weighted residuals to form a system of linear algebraic equations between the element stiffness matrix and the nodal displacement column vectors. The displacement components of the three corner nodes are obtained by solving the system of linear algebraic equations.

[0008] As a further aspect of the present invention, the coordinate set of the easily deformable region and the boundary line of the region requiring support of the target thin plate part are determined based on the nodal displacement and element warping angle in the thermo-coupled deformation prediction field, including: Scan the displacement of each node in the thermo-coupled deformation prediction field, and mark the nodes whose absolute value of the node displacement exceeds the preset warping threshold as a high deformation node candidate set. For each high deformation node in the candidate set of high deformation nodes, extract the thin shell element to which the high deformation node belongs and calculate the relative displacement difference between the three corner nodes of the thin shell element; The unit warpage angle of the thin shell unit is calculated based on the relative displacement difference, and the thin shell unit whose absolute value of the unit warpage angle exceeds the preset warpage angle threshold is marked as a deformable unit. The spatial coordinate regions covered by all deformable units are merged into an initial deformable region. A morphological closing operation is performed on the initial deformable region to fill the internal holes of the region, generating the final set of coordinates of the deformable region. Extract the convex hull boundary line of the coordinate set of the easily deformable region, and offset the convex hull boundary line outward by a preset support safety distance to obtain the boundary line of the region that needs support.

[0009] As a further aspect of the present invention, the step of merging the spatial coordinate regions covered by all deformable units into an initial deformable region, performing a morphological closing operation on the initial deformable region to fill the internal holes of the region, and generating a final set of coordinates for the deformable region includes: Extract the spatial coordinate information of all easily deformable elements, and connect the spatial coordinates of the three corner nodes of each easily deformable element to form a triangular patch; Perform a union Boolean operation on the triangular facets in three-dimensional space to form a three-dimensional volume region that includes the coverage of all deformable units, and mark the three-dimensional volume region as the initial deformable region; A two-dimensional discrete mesh is constructed on the surface of the initial deformable region, wherein the unit size of the two-dimensional discrete mesh is smaller than the preset hole recognition resolution; Traverse each grid cell in the two-dimensional discrete grid and calculate whether the center point of the grid cell is located inside the initial deformable region. If the center point is located outside the initial deformable region but the center points of the adjacent grid cells in its preset neighborhood are all located inside, then the grid cell is identified as an internal hole cell. The coordinates of the center points of all identified internal hole units are added to the initial coordinate set of the easily deformable region, and the updated coordinate set is defined as the final coordinate set of the easily deformable region.

[0010] As a further aspect of the present invention, based on the coordinate set of the easily deformable region and the boundary line of the region requiring support, the topological configuration parameters of the conformal control thin plate are generated, including: The area enclosed by the boundary line of the area to be supported is taken as the core area for the arrangement of reinforcing ribs. Within the core area, a set of candidate reinforcing rib trajectory lines is generated according to the preset initial rib spacing. For each candidate stiffener trajectory line in the set of candidate stiffener trajectory lines, calculate the spatial overlap length between the candidate stiffener trajectory line and the coordinate set of the easily deformable region; Candidate reinforcing rib trajectory lines whose spatial overlap length exceeds a preset overlap threshold are retained as valid reinforcing rib trajectory lines, while candidate reinforcing rib trajectory lines whose spatial overlap length does not exceed the preset overlap threshold are deleted. A gradually varying rib thickness is provided along the extension direction of the effective reinforcing rib trajectory line. The gradually varying rib thickness takes the maximum value in the overlapping section of the effective reinforcing rib trajectory line and the coordinate set of the easily deformable area, and takes the minimum value at the end of the effective reinforcing rib trajectory line away from the coordinate set of the easily deformable area. The spatial coordinate sequence of the effective stiffener trajectory line and the corresponding gradient stiffener thickness value are stored in a structured manner to generate the spatial layout trajectory of the stiffener and the thickness gradient mapping table of the thin plate.

[0011] As a further aspect of the present invention, a gradually varying rib thickness is provided along the extension direction of the effective reinforcing rib trajectory line, including: For the current effective stiffener trajectory line, extract the original substrate thickness value of the target thin plate part at the location of the current effective stiffener trajectory line from the geometric model data; Based on the spatial range of the coordinate set of the easily deformable region, high deformation section, transition section and low deformation section are divided on the trajectory line of the current effective stiffener; Within the high deformation zone, the rib thickness is set to the result of multiplying the original substrate thickness by a thickness multiplication factor, wherein the value of the thickness multiplication factor is proportional to the average value of the node displacement within the high deformation zone. Within the low-deformation zone, the rib thickness is set to be equal to the original substrate thickness value; Within the transition zone, the rib thickness is determined using linear interpolation. The starting thickness of the linear interpolation is the rib thickness at the end of the high deformation zone, and the ending thickness is the rib thickness at the beginning of the low deformation zone.

[0012] As a further aspect of the present invention, the topological configuration parameters of the conformal-shaped thin plate are embedded into the original geometric model of the target thin plate part to generate a composite thin plate model containing conformal-shaped features, including: Read the spatial layout trajectory of the reinforcing ribs and the thickness gradient mapping table of the thin plate from the topological configuration parameters of the conformal control thin plate; Based on the spatial layout trajectory of the reinforcing ribs, a solid sweeping body of the reinforcing ribs is generated at the corresponding spatial position of the original geometric model of the target thin plate part. The cross-sectional shape of the solid sweeping body of the reinforcing ribs is a trapezoidal cross-section, and the ratio of the width of the upper base to the width of the lower base of the trapezoidal cross-section is determined by the local curvature of the target thin plate part. Based on the thickness values ​​in the thin plate thickness gradient mapping table, a thickness replacement operation is performed on a local area of ​​the original geometric model of the target thin plate part. The thickness replacement operation is used to update the original thickness values ​​to the thickness values ​​in the thin plate thickness gradient mapping table. Perform a Boolean union operation on the geometric model of the target thin plate part after thickness replacement and the solid swept body of the reinforcing rib to generate a composite thin plate model with conformal shape control features that is expressed as an integrated whole. A model repair check is performed on the composite thin plate model, which includes overlapping surface deletion and non-manifold edge repair operations.

[0013] As a further aspect of the present invention, based on the spatial layout trajectory of the reinforcing ribs, a solid swept body of the reinforcing ribs is generated at the corresponding spatial position of the original geometric model of the target thin plate part, including: Extract the spatial coordinate sequence of the trajectory control points and the rib thickness value at the trajectory control points from the spatial layout trajectory of the reinforcing ribs; The rib thickness at each trajectory control point is used as the median length of the trapezoidal cross section, and the upper and lower base widths of the trapezoidal cross section are determined based on the local curvature of the target thin plate part. Using the spatial coordinates of the trajectory control point as the section positioning point, and the tangent direction of the spatial layout trajectory of the reinforcing rib as the section normal direction, a corresponding trapezoidal section profile is placed at each trajectory control point. The 3D sweep modeling kernel is invoked to perform linear skinning on the trapezoidal cross-sectional contours between adjacent trajectory control points, generating multi-segment prism entities. The multiple prism entities are sequentially subjected to Boolean union and set-up operations to form a continuously extending baffle body of the reinforcing rib entity.

[0014] As a further aspect of the present invention, the method further includes a process of performing interlayer stress optimization iteration on the composite thin plate model containing conformal shape control features: The composite thin plate model containing conformal shape control features is imported into the slicing data processing software to generate a layer-by-layer slicing image sequence containing the outline of the part and the outline of the reinforcing rib. Calculate the ratio of the area of ​​the reinforcing rib region to the area of ​​the main body region of the part in each slice layer based on the layer-by-layer slice image sequence; The ratio value is compared with a preset ratio threshold layer by layer. When the ratio value of a certain layer is lower than the preset ratio threshold, the layer is marked as a potential stress concentration layer. Extract the layer number of the potential stress concentration layer, and locate the reinforcing rib segment that intersects with the potential stress concentration layer from the spatial layout trajectory of the reinforcing ribs; Increase the rib thickness value of the reinforcing rib section, and repeat the step of generating a composite thin plate model with conformal shape control features until the proportion value of all slice layers is not lower than the preset proportion threshold.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: An improved finite element analysis algorithm for thin shells is built based on the equilibrium differential equations of classical thin shell theory. This algorithm performs analytical calculations on geometric model data, including the thickness distribution field and surface curvature distribution map of the thin plate, to deduce the thermo-mechanical coupling deformation prediction field during the layer-by-layer scanning process of metal SLM forming. This analysis method closely matches the mechanical structural properties of thin plate components, adapts to the mechanical response laws of different thickness regions and surface curvature positions, and aligns with the process characteristics of SLM layer-by-layer cumulative forming. It can fully present the deformation evolution state under thermo-mechanical coupling throughout the forming process, achieving complete analysis and quantitative output of the full-domain deformation information of the part.

[0016] Based on the nodal displacements and element warping angles within the thermo-coupled deformation prediction field, the coordinate set of easily deformable regions and the boundary lines of support-required regions of the thin-plate component are defined. Topological configuration parameters, including the spatial layout trajectory of stiffeners and a thin-plate thickness gradient mapping table, are generated. These parameters are then embedded into the original geometric model to construct a composite thin-plate model. Functional regions are divided based on the actual deformation characteristics of the forming process. The structural configuration parameters conform to the actual deformation patterns of each region, abandoning the uniform structural design model. This ensures that the thin-plate thickness variation and stiffener arrangement conform to its own deformation distribution characteristics, and that the shape control structure and support layout conform to the geometric and mechanical properties of the part itself, thus adapting to the structural optimization design requirements of SLM forming of thin-plate components. Attached Figure Description

[0017] Figure 1 This is a flowchart of a metal SLM forming anti-deformation and support reduction conformal shape control thin plate design method according to the present invention; Figure 2 A flowchart for obtaining the displacement components of corner nodes by solving the equilibrium differential equation; Figure 3 A flowchart for determining the coordinate set of easily deformable regions and the boundary lines of regions requiring support. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] See Figure 1 This invention provides a method for designing conformal shape control thin plates with deformation prevention and support reduction in metal SLM forming. The specific method includes: Geometric model data and SLM forming process parameter data of the target thin-plate part are collected. The geometric model data includes the thickness distribution field and surface curvature distribution map of the thin plate. An improved thin-shell finite element analysis algorithm is executed on the geometric model data. This improved algorithm is based on the equilibrium differential equations of classical thin-shell theory to generate a thermo-mechanical coupling deformation prediction field of the target thin-plate part during the layer-by-layer scanning process. Based on the nodal displacements and element warping angles in the thermo-mechanical coupling deformation prediction field, the coordinate set of the easily deformable regions and the boundary lines of the support-required regions of the target thin-plate part are determined. Based on the coordinate set of the easily deformable regions and the boundary lines of the support-required regions, the topological configuration parameters of the conformal control thin plate are generated. These topological configuration parameters include the spatial layout trajectory of the stiffeners and the thin plate thickness gradient mapping table. The topological configuration parameters of the conformal control thin plate are embedded into the original geometric model of the target thin-plate part to generate a composite thin-plate model with conformal control features.

[0021] In one embodiment of the present invention, the process of performing an improved thin-shell finite element analysis algorithm on geometric model data is described in detail. Neutral surface geometric parameters and the thickness distribution field of the target thin-plate part are extracted from the geometric model data. The neutral surface geometric parameters include the neutral surface spatial coordinates and the neutral surface normal vector. Based on the neutral surface geometric parameters and the thickness distribution field, the target thin-plate part is discretized into multiple thin-shell elements, each containing three corner nodes and one thickness integration point. For each thin-shell element, the laser scanning path and laser energy density value are extracted from the SLM forming process parameter data. The transient temperature load of the thin-shell element in the time series is calculated based on the laser scanning path and laser energy density value. The transient temperature load is applied to the three corner nodes of the thin-shell element, and the displacement components of each corner node in three spatial directions are obtained by solving the equilibrium differential equations in the improved thin-shell finite element analysis algorithm. See also... Figure 2 For the current thin-shell element, the initial coordinates of the three corner nodes and the temperature gradient at the thickness integration point of the current thin-shell element are extracted. Based on the temperature gradient and the thermal expansion coefficient of the target thin-plate part, the thermal strain tensor components inside the current thin-shell element are calculated. The thermal strain tensor components are converted into equivalent nodal thermal load vectors, which are then superimposed on the external force load terms of the equilibrium differential equation. The Kirchhoff assumption of thin-shell theory is introduced into the geometric equation of the equilibrium differential equation. This assumption stipulates that the normal to the neutral surface remains straight and perpendicular to the deformed neutral surface during the deformation process of the thin-shell. Based on the Kirchhoff assumption, the equilibrium differential equation is discretized using Galerkin weighted residuals to form a system of linear algebraic equations between the element stiffness matrix and the nodal displacement column vectors. The displacement components of the three corner nodes are obtained by solving the system of linear algebraic equations. The displacement components of all corner nodes of all thin-shell elements are assembled into a field quantity to generate a nodal displacement cloud map covering the entire geometric region of the target thin-plate part, which serves as the thermo-mechanical coupling deformation prediction field.

[0022] In specific implementations, an improved thin-shell finite element analysis algorithm is applied to the geometric model data to generate a thermo-coupled deformation prediction field. The execution of this improved algorithm begins with extracting the neutral surface geometric parameters and the plate thickness distribution field of the target thin-plate part from the geometric model data. In an example scenario, the target thin-plate part is a curved skin component of an aero-engine. Its geometric model data comes from 3D CAD software. The neutral surface geometric parameters are obtained using a surface offset algorithm, containing the spatial coordinates of all discrete points on the neutral surface and the unit normal vector at each point. The plate thickness distribution field is attached to the neutral surface model in the form of a thickness contour map, recording the plate thickness value at each location. Based on the extracted neutral surface geometric parameters and the plate thickness distribution field, the continuous geometry of the target thin-plate part is discretized into multiple thin-shell elements. The discretization process uses triangular mesh generation, with each thin-shell element containing three corner nodes on the neutral surface and one thickness direction integration point for integration calculation. In some embodiments, the size of the thin-shell elements is adaptively adjusted according to the surface curvature distribution, with a denser mesh generation used in high curvature regions.

[0023] In practice, for each generated thin-shell element, the laser scanning path and laser energy density value are extracted from the SLM forming process parameter data. The laser scanning path is defined by a series of ordered spatial coordinate points, and the laser energy density value is associated with each segment of the scanning path. Based on the laser scanning path and laser energy density value, the transient temperature load of the thin-shell element over time is calculated. During the calculation, it is assumed that the laser heat source is a moving Gaussian surface heat source, with the center of the heat source moving along the scanning path. The laser energy density value is converted into heat flux density input, and combined with the thermal properties of the material, the transient heat conduction equation is solved analytically or numerically to obtain the temperature history curve of the thin-shell element at the thickness integration point over time. The calculated transient temperature load is applied to the three corner nodes of the corresponding thin-shell element. Typically, the temperature value at the thickness integration point is distributed to the three corner nodes through shape function interpolation. By solving the equilibrium differential equations in the improved thin-shell finite element analysis algorithm, the displacement components of each corner node in three spatial directions are obtained.

[0024] In practice, solving the equilibrium differential equations to obtain the corner nodal displacement components involves multiple computational steps. For the thin-shell element being processed, the initial coordinates of the three corner nodes and the temperature gradient values ​​at the thickness integration points of the current thin-shell element are extracted. The temperature gradient values ​​are calculated from the transient temperature field, reflecting the rate of temperature change in the element's thickness direction and in-plane direction. Based on the temperature gradient values ​​and the material's thermal expansion coefficient of the target thin-plate part, the thermal strain tensor components inside the current thin-shell element are calculated. During calculation, the temperature gradient is multiplied by the material's thermal expansion coefficient to obtain the linear strain caused by temperature changes, and the total strain tensor is calculated using the Poisson effect. The thermal strain tensor components are converted into equivalent nodal thermal load vectors. This conversion process is based on the principle of virtual work, transforming the distributed thermal strain into concentrated forces acting on the element's corner nodes. The equivalent nodal thermal load vectors are then superimposed onto the external force load terms of the equilibrium differential equations. Kirchhoff's assumption from thin-shell theory is introduced into the geometric equations of the equilibrium differential equations. This assumption stipulates that during the deformation of the thin shell, a straight line segment perpendicular to the mid-surface before deformation remains a straight line after deformation, with its length unchanged, and remains perpendicular to the deformed mid-surface. Based on Kirchhoff's assumption, the equilibrium differential equations are discretized using Galerkin weighted residuals, forming a system of linear algebraic equations between the element stiffness matrix and the nodal displacement column vectors. This discretization process transforms the continuous partial differential governing equations into a set of algebraic equations concerning the nodal unknowns. The displacement components of the three corner nodes are obtained by solving the system of linear algebraic equations. Direct methods such as LU decomposition or iterative methods are used for the solution. The system of linear algebraic equations can be expressed as:

[0025] in: The element stiffness matrix representing the current thin shell element. This represents the column vector of nodal displacements composed of the displacement components of the three corner nodes of the current thin-shell element. This represents the column vector of element nodal forces containing the equivalent nodal thermal loads. In some embodiments, the element stiffness matrix... The design takes into account the material's elastic modulus, Poisson's ratio, and element geometry. It can be understood that the above calculation process is performed independently for each thin-shell element in the model. In specific implementation, after solving for the displacements of all thin-shell elements, the displacement components of all corner nodes of all thin-shell elements are assembled into a field. The assembly process follows the standard procedure of the finite element method, integrating the displacement components contributed by each element into the global displacement vector according to the node number, and considering node sharing relationships. Finally, a node displacement cloud map covering the entire geometric region of the target thin-plate part is generated. This node displacement cloud map serves as the output of the thermo-coupled deformation prediction field, used to identify the predicted deformation displacement of the part at different locations caused by the SLM forming process. In a data comparison example, the input is the original continuous surface model and process parameter file, and the output is a digital field containing thousands to tens of thousands of node displacement values, which directly maps the deformation trend of each point on the part's geometry during the manufacturing process.

[0026] In one embodiment of the present invention, the process of determining the coordinate set of easily deformable regions and the boundary line of regions requiring support based on the thermo-coupled deformation prediction field is described in detail. See also... Figure 3 The process involves scanning the displacement of each node in the thermo-coupled deformation prediction field and marking nodes whose absolute displacement exceeds a preset warping threshold as high-deformation node candidates. For each high-deformation node in the candidate set, the thin-shell element to which the high-deformation node belongs is extracted, and the relative displacement difference between the three corner nodes of the thin-shell element is calculated. Based on the relative displacement difference, the element warping angle of the thin-shell element is calculated, and thin-shell elements whose absolute warping angle exceeds a preset warping angle threshold are marked as easily deformable elements. The spatial coordinate regions covered by all easily deformable elements are merged into an initial easily deformable region. Morphological closing operations are performed on the initial easily deformable region to fill the internal holes, generating the final easily deformable region coordinate set. The spatial coordinate information of all easily deformable elements is extracted, and the spatial coordinates of the three corner nodes of each easily deformable element are connected to form triangular patches. The triangular patches are then subjected to a union Boolean operation in three-dimensional space to form a three-dimensional volume region containing the coverage of all easily deformable elements, and this three-dimensional volume region is marked as the initial easily deformable region. A two-dimensional discrete mesh is constructed on the surface of the initial deformable region, with the cell size of the two-dimensional discrete mesh being smaller than a preset hole identification resolution. Each mesh cell in the two-dimensional discrete mesh is traversed, and it is calculated whether the center point of the mesh cell is located inside the initial deformable region. If the center point is located outside the initial deformable region but the center points of its adjacent mesh cells within a preset neighborhood are all located inside, then the mesh cell is identified as an internal hole cell. The coordinates of the center points of all identified internal hole cells are added to the coordinate set of the initial deformable region, and the updated coordinate set is defined as the final deformable region coordinate set. The convex hull boundary line of the deformable region coordinate set is extracted, and the boundary line of the region requiring support is obtained by offsetting the convex hull boundary line outward by a preset support safety distance.

[0027] In practical implementation, the coordinate set of easily deformable regions and the boundary lines of regions requiring support are determined based on the thermo-coupled deformation prediction field. The initial step in this process is to scan the displacement of each node in the thermo-coupled deformation prediction field. In an example scenario, the target thin-plate part is an aircraft wing skin component with complex curvature. Its thermo-coupled deformation prediction field is a collection of 100,000 node displacement data points, each containing a node number and its displacement components in the X, Y, and Z directions. The displacement vector magnitude of each node, i.e., the absolute value of the node displacement, is compared with a preset warpage threshold, which is set based on the material yield strength and process stability. Nodes whose absolute displacement values ​​exceed the preset warpage threshold are marked, forming a candidate set of high-deformation nodes. This set may contain thousands of spatial node coordinates. In some embodiments, the preset warpage threshold is set to one percent of the average plate thickness.

[0028] In practical implementation, for each high-deformation node in the candidate set, it is necessary to extract the thin-shell element to which the high-deformation node belongs. Since nodes in the finite element model are shared by multiple elements, it is necessary to query all triangular thin-shell elements containing the current high-deformation node based on the topological connection relationship. For each such thin-shell element, the relative displacement difference between the three corner nodes of the thin-shell element is calculated. The calculation method is to obtain the displacement vectors of the three corner nodes of the thin-shell element under the current load step, then subtract them pairwise to obtain the vector difference, and calculate the magnitude of these vector differences. Based on the calculated relative displacement difference, the element warpage angle of the thin-shell element is calculated. Element warpage angle It can be estimated using the following formula:

[0029] in: Represents the unit warp angle. This represents the displacement difference vector from node j to node i. This represents the displacement difference vector from node k to node i. This represents the unit normal vector of the thin-shell element before deformation. This formula reflects the out-of-plane rotation angle of the element plane due to non-uniform displacement. The absolute value of the calculated element warpage angle is compared with a preset warpage angle threshold. Thin-shell elements whose absolute warpage angle exceeds the preset threshold are marked as easily deformable elements.

[0030] In practical implementation, it is necessary to merge the spatial coordinate regions covered by all deformable elements into an initial deformable region. The spatial coordinate information of all marked deformable elements is extracted, and the spatial coordinates of the three corner nodes of each deformable element are connected to form triangular patches in three-dimensional space. These triangular patches are then subjected to a union Boolean operation in three-dimensional space. This operation is performed in the computer graphics kernel, generating one or more continuous or discrete three-dimensional volume regions that include all spatial ranges covered by the deformable elements. This result is marked as the initial deformable region. In some embodiments, the union Boolean operation is implemented by constructing solid geometry or boundary representations. A two-dimensional discrete mesh is constructed on the surface of the initial deformable region. The element size of the two-dimensional discrete mesh is smaller than a preset hole recognition resolution, which is typically set to half the side length of the smallest thin-shell element. Each mesh element in the two-dimensional discrete mesh is traversed, the coordinates of the center point of the mesh element are calculated, and it is determined whether the center point is located inside the initial deformable region. The determination method uses a ray method, emitting a ray from the center point and calculating the number of intersections with the boundary of the initial deformable region. If the center point is located outside the initial deformable region, but checking the center points of all adjacent grid cells within its preset neighborhood reveals that these adjacent grid cell center points are all located inside the initial deformable region, then the currently traversed grid cell is identified as an internal hole cell. The preset neighborhood is typically defined as a 3x3 grid region centered on the current grid cell. Adding the coordinates of the center points of all identified internal hole cells to the coordinate set of the initial deformable region essentially fills the hole region as part of the solid region. The updated coordinate set, containing the original deformable cell coordinates and the fill point coordinates, is defined as the final deformable region coordinate set. In a data comparison example, the initial deformable region coordinate set contains 15234 points; after internal hole identification and filling, the final deformable region coordinate set contains 15987 points, with the additional 753 points being the coordinates of the filled internal holes.

[0031] In practice, the final step is to extract the convex hull boundary line of the coordinate set of the easily deformable region. Optionally, the two-dimensional projection of the final coordinate set of the easily deformable region in three-dimensional space is calculated, and then its convex hull is calculated on the projection plane. The convex hull is the smallest convex polygon containing all coordinate points. The calculated convex hull boundary line is offset outward by a preset support safety distance, which is determined based on the design width and machining allowance of the support structure. The offset operation is achieved by translating each point on the convex hull boundary line along its outward normal direction by the preset support safety distance. Connecting these translated points forms a new closed polygon curve, which is the boundary line of the region requiring support. It can be understood that the boundary line of the region requiring support defines the key contour area where external support structures need to be added or internal reinforcement needs to be performed during the SLM forming process.

[0032] In one embodiment of the present invention, the process of generating the topological configuration parameters of the conformal control sheet is described in detail. The area enclosed by the boundary line of the region to be supported is designated as the core area for the arrangement of reinforcing ribs. Within the core area, a set of candidate reinforcing rib trajectory lines is generated according to a preset initial rib spacing. For each candidate reinforcing rib trajectory line in the set, the spatial overlap length between the candidate reinforcing rib trajectory line and the coordinate set of the easily deformable region is calculated. Candidate reinforcing rib trajectory lines whose spatial overlap length exceeds a preset overlap threshold are retained as valid reinforcing rib trajectory lines, while those whose spatial overlap length does not exceed the preset overlap threshold are deleted. A gradient rib thickness is set along the extension direction of the valid reinforcing rib trajectory line. The gradient rib thickness has a maximum value within the overlap section between the valid reinforcing rib trajectory line and the coordinate set of the easily deformable region, and a minimum value at the end of the valid reinforcing rib trajectory line away from the coordinate set of the easily deformable region. For the current valid reinforcing rib trajectory line, the original substrate thickness value of the target sheet part at the location of the current valid reinforcing rib trajectory line is extracted from the geometric model data. Based on the spatial range of the coordinate set of the easily deformable region, high-deformation, transition, and low-deformation sections are divided along the current effective stiffener trajectory. In the high-deformation section, the stiffener thickness is set to the original substrate thickness multiplied by a thickness multiplication factor, where the value of the thickness multiplication factor is proportional to the average nodal displacement within the high-deformation section. In the low-deformation section, the stiffener thickness is set equal to the original substrate thickness. In the transition section, linear interpolation is used to determine the stiffener thickness. The starting thickness of the linear interpolation is the stiffener thickness at the end of the high-deformation section, and the ending thickness is the stiffener thickness at the beginning of the low-deformation section. The spatial coordinate sequence of the effective stiffener trajectory and the corresponding gradually changing stiffener thickness values ​​are structured and stored to generate a stiffener spatial layout trajectory and a thin plate thickness gradient mapping table.

[0033] In specific implementations, the topological configuration parameters of the conformal control thin plate are generated. Based on the determined boundary line of the support area and the coordinate set of the easily deformable area, the closed region enclosed by the boundary line of the support area is used as the core area for rib arrangement. In one example scenario, the target thin plate part is a thin-walled component of a satellite antenna reflector, and its support area boundary line is an approximately elliptical closed planar curve. Within the core area, a set of candidate rib trajectory lines is generated according to a preset initial rib spacing, which is set based on the overall size of the part and the typical deformation wavelength. The generation method involves generating a set of parallel straight lines or curves as candidate trajectories within the core area boundary along two orthogonal principal directions, with the initial rib spacing as the interval. This set of candidate rib trajectory lines may contain dozens of spatial curves. In some embodiments, the value of the initial rib spacing is proportional to the average thickness of the target thin plate part.

[0034] For each candidate stiffener trajectory in the candidate stiffener trajectory set, the spatial overlap length between the candidate stiffener trajectory and the coordinate set of the deformable region needs to be calculated. During calculation, the candidate stiffener trajectory is discretized into a series of dense points, and then it is determined whether each discrete point is located inside or on the surface of the 3D spatial point cloud defined by the coordinate set of the deformable region. The approximate spatial overlap length is obtained by counting the number of discrete points falling within the deformable region and multiplying it by the point spacing. Candidate stiffener trajectories with a spatial overlap length exceeding a preset overlap threshold are retained as valid stiffener trajectories. The preset overlap threshold is typically set to 20% of the total length of the candidate stiffener trajectories. Candidate stiffener trajectories with a spatial overlap length not exceeding the preset overlap threshold are deleted. This can be understood as a screening process to ensure that the retained stiffeners mainly cover the predicted deformable region. See Table 1 for a simplified data comparison example of the screening process.

[0035] Table 1: Candidate Reinforcing Rib Trajectory Line Screening Data Table ; In practical implementation, a gradually changing stiffener thickness is set along the extension direction of the finally determined effective stiffener trajectory line. The gradually changing stiffener thickness takes its maximum value within the overlapping section of the effective stiffener trajectory line and the coordinate set of the easily deformable region, and its minimum value at the end of the effective stiffener trajectory line away from the coordinate set of the easily deformable region. For each effective stiffener trajectory line, the original substrate thickness value of the target thin plate part at the location of the effective stiffener trajectory line is extracted from the geometric model data. This value can be obtained from the thin plate thickness distribution field through spatial interpolation. Based on the spatial range of the coordinate set of the easily deformable region, high deformation section, transition section, and low deformation section are divided along the effective stiffener trajectory line. The high deformation section is defined as the continuous part of the trajectory line that is completely inside the coordinate set of the easily deformable region, the low deformation section is defined as the continuous part of the trajectory line that is completely outside the coordinate set of the easily deformable region, and the transition section is the section connecting the two.

[0036] Within the high-deformation zone, the stiffener thickness is set to the original substrate thickness multiplied by a thickness multiplication factor. The thickness multiplication factor is proportional to the average nodal displacement within the high-deformation zone, and this relationship is defined by the following formula:

[0037] in: Represents the thickness multiplication factor. It is a proportionality coefficient. This represents the average displacement of the finite element nodes covered by the high deformation section. This represents the original substrate thickness value. It can be understood that the more severe the deformation, the larger the thickness multiplication factor, and the thicker the ribs. In low-deformation sections, the rib thickness is set equal to the original substrate thickness value, i.e., no additional thickening is applied. In transition sections, linear interpolation is used to determine the rib thickness. The starting thickness of the linear interpolation is the rib thickness value at the end of the high-deformation section, and the ending thickness is the rib thickness value at the beginning of the low-deformation section. Optionally, interpolation can be performed along the arc length parameter of the trajectory line. In some embodiments, for complex curved trajectories, the thickness change in the transition section can use smooth spline interpolation instead of nonlinear interpolation. The spatial coordinate sequence of the effective stiffener trajectory line (i.e., a series of ordered three-dimensional points) and the corresponding gradual rib thickness value for each point are structured and stored, for example, as a list containing coordinates and thickness attributes, generating two parts of topological configuration parameters: the stiffener spatial layout trajectory and the thin plate thickness gradient mapping table.

[0038] In one embodiment of the present invention, the process of generating a composite thin plate model containing conformal shaping features is described in detail. The spatial layout trajectory of the stiffeners and the thin plate thickness gradient mapping table are read from the topological configuration parameters of the conformal shaping thin plate. Based on the spatial layout trajectory of the stiffeners, a solid sweep body of the stiffeners is generated at the corresponding spatial position of the original geometric model of the target thin plate part. The cross-sectional shape of the solid sweep body of the stiffeners is a trapezoidal cross-section, and the ratio of the upper base width to the lower base width of the trapezoidal cross-section is determined by the local curvature of the target thin plate part. The spatial coordinate sequence of the trajectory control points and the stiffener thickness values ​​at the trajectory control points are extracted from the spatial layout trajectory of the stiffeners. The stiffener thickness value at each trajectory control point is used as the median length of the trapezoidal cross-section, and the upper and lower base widths of the trapezoidal cross-section are determined based on the local curvature of the target thin plate part. Using the spatial coordinates at the trajectory control points as the cross-section positioning points and the tangent direction of the stiffener spatial layout trajectory as the cross-section normal direction, a corresponding trapezoidal cross-section profile is placed at each trajectory control point. The 3D sweep modeling kernel is invoked to perform linear skinning on the trapezoidal cross-sectional contours between adjacent trajectory control points, generating multi-segment prism entities. These multi-segment prism entities are then sequentially subjected to a Boolean union operation to form a continuously extending reinforcing rib entity sweep body. Based on the thickness values ​​in the thin plate thickness gradient mapping table, a thickness replacement operation is performed on a local region of the original geometric model of the target thin plate part, updating the original thickness values ​​to those in the thin plate thickness gradient mapping table. A Boolean union operation is then performed between the reinforcing rib entity sweep body and the thickness-replaced target thin plate part geometric model to generate a unified composite thin plate model containing conformal shape control features. A model repair check is then performed on the composite thin plate model, including overlapping surface deletion and non-manifold edge repair operations.

[0039] In a specific implementation, the fourth embodiment of a metal SLM forming anti-deformation and support-reducing conformal control thin plate design method involves generating a composite thin plate model with conformal control features. In this implementation, the spatial layout trajectory of the stiffeners and the thin plate thickness gradient mapping table are read from the topological configuration parameters of the conformal control thin plate. In an example scenario, the target thin plate part is an aircraft wing with double curvature characteristics. Its stiffener spatial layout trajectory file contains a sequence of control point coordinates for multiple three-dimensional spline curves, and the thin plate thickness gradient mapping table stores the design thickness values ​​at multiple sampling points along each trajectory line in list form. Based on the read stiffener spatial layout trajectory, a stiffener solid swept body is generated at the corresponding spatial position of the original geometric model of the target thin plate part. The cross-sectional shape of the stiffener solid swept body is designed as a trapezoidal cross-section, and the ratio of the upper base width to the lower base width of the trapezoidal cross-section is determined by the local curvature of the target thin plate part at the stiffener position. The greater the local curvature, the greater the difference in width between the upper and lower bases of the trapezoidal cross-section is usually to adapt to surface fitting. In some embodiments, the specific dimensional parameters of the trapezoidal cross section are calculated by querying the surface properties of the original geometric model and combining them with process constraints.

[0040] In practice, the process of generating a solid swept body of the stiffener based on the spatial layout trajectory of the stiffeners involves a series of geometric modeling operations. The spatial coordinate sequence of the trajectory control points and the stiffener thickness values ​​at the control points are extracted from the stiffener spatial layout trajectory. The stiffener thickness values ​​are derived from a thin plate thickness gradient mapping table. The stiffener thickness value at each trajectory control point is used as the median length of the trapezoidal cross-section. The upper and lower base widths of the trapezoidal cross-section are determined based on the local curvature of the target thin plate part. The local curvature is obtained by calculating the average principal curvature of the surface at the trajectory control points. The upper base width of the trapezoidal cross-section... It can be calculated using the following formula:

[0041] in: Represents the width of the upper base of the trapezoidal cross section. The value of the rib thickness (i.e., the length of the median line) at the trajectory control point. This represents the local curvature value of the target thin-plate part at the trajectory control point. The curvature influence coefficient is a normal constant related to materials and processes. This formula ensures that at high curvature locations, the top surface of the trapezoidal cross-section is narrower to better fit the curved surface. The width of the lower base of the trapezoidal cross-section... It is usually set to be longer than the median line length. Larger than a fixed value, that is ,in This is a preset bottom increment. Using the spatial coordinates of the trajectory control points as the cross-section positioning points, and the tangent direction of the stiffener spatial layout trajectory at the positioning points as the cross-section normal direction, the calculated trapezoidal cross-section profile is placed at each trajectory control point. The 3D sweep modeling kernel in the 3D CAD system is called to perform a linear skinning operation on the trapezoidal cross-section profiles between adjacent trajectory control points, generating a multi-segment prism solid connecting the two cross-sections. Optionally, the skinning operation can be implemented using lofting or sweep functions. All multi-segment prism solids generated between multiple trajectory control points are sequentially subjected to a Boolean union operation to form a continuous, smoothly extending stiffener solid sweep body.

[0042] In practice, based on the thickness values ​​in the thin plate thickness gradient mapping table, a thickness replacement operation is performed on a local area of ​​the original geometric model of the target thin plate part. The thickness replacement operation updates the original thickness values ​​of the original geometric model in a specific region to the thickness values ​​specified in the thin plate thickness gradient mapping table. This operation is typically achieved in parametric CAD systems by modifying surface thickening features or directly editing the voxel model. A Boolean union operation is performed between the stiffener solid sweep and the target thin plate part's geometric model after thickness replacement. This operation merges the stiffener and the substrate into a single solid model, generating a composite thin plate model with conformal shape control features. In some embodiments, after the Boolean union operation, the geometry of the joint area is automatically rounded to eliminate sharp edges. A model repair check is performed on the composite thin plate model, including overlapping surface deletion and non-manifold edge repair operations, ensuring that the model is a closed, watertight solid that meets the input requirements of subsequent slicing software. Refer to Table 2, which shows the parameters for generating a trapezoidal section at a specific location.

[0043] Table 2: Calculation Table of Cross-sectional Parameters for Reinforcing Ribs ; In one embodiment of the present invention, the process of performing interlayer stress optimization iteration on a composite thin plate model with conformal shape control features is described in detail. The composite thin plate model with conformal shape control features is imported into slicing data processing software to generate a sequence of layer-by-layer slice images containing the outline of the part and the outline of the reinforcing ribs. The ratio of the area of ​​the reinforcing rib region to the area of ​​the main body region of the part in each slice layer is calculated based on the layer-by-layer slice image sequence. The ratio is compared layer by layer with a preset ratio threshold. When the ratio of a certain layer is lower than the preset ratio threshold, that layer is marked as a potential stress concentration layer. The layer number of the potential stress concentration layer is extracted, and the reinforcing rib segment intersecting with the potential stress concentration layer is located from the spatial layout trajectory of the reinforcing ribs. The rib thickness value of the reinforcing rib segment is increased, and the step of generating the composite thin plate model with conformal shape control features is repeated until the ratio values ​​of all slice layers are not lower than the preset ratio threshold.

[0044] In practical implementation, the process involves iterative optimization of interlayer stress on a composite thin-plate model with conformal shape control features. This optimization process begins by importing the composite thin-plate model with conformal shape control features into the slice data processing software. In an example scenario, the composite thin-plate model is a complex thin-walled shell for a medical device, in a standard STL file format. In the slice data processing software, layer thickness parameters matching the target SLM device are set, for example, 50 micrometers, generating a sequence of layer-by-layer slice images containing the part outline and stiffener outlines. Each slice image is essentially a set of two-dimensional vector data of the geometric outline of that layer. Based on the generated layer-by-layer slice image sequence, the ratio of the area of ​​the stiffener region to the area of ​​the main part region in each slice layer is calculated. During the calculation, for each slice image, the outline polygons belonging to the stiffeners and the outline polygons belonging to the main part are extracted, and the area of ​​the stiffener region is calculated using the polygon area calculation formula. and the area of ​​the main body of the part Then follow the formula Calculate the area ratio of the current layer .

[0045] In practice, the calculated area ratio of each floor will be used. With a preset ratio threshold Perform layer-by-layer comparison. Preset ratio threshold. The value is set based on material properties, historical process data, and empirical values ​​for preventing interlayer cracking; for example, it might be set to 0.15. This applies to the area ratio of a particular layer. Below the preset ratio threshold At this point, this layer is marked as a potential stress concentration layer. It's understandable that a low area ratio means the reinforcement provided by the stiffeners in this layer is relatively weak, potentially becoming the starting point of stress concentration during the thermal cycling of layer-by-layer manufacturing. The layer numbers of all marked potential stress concentration layers are extracted; these are consecutive integer sequences identifying the specific height position of the model in the construction direction. The stiffener segments intersecting with the potential stress concentration layers are located from the stored stiffener spatial layout trajectories. The location method involves comparing the three-dimensional coordinates of the stiffener spatial layout trajectory with the Z-axis height range corresponding to the potential stress concentration layer, filtering out all stiffener trajectory segments that pass through this height range.

[0046] In some embodiments, the thickness of the reinforcing rib in the located stiffener section is increased. Thickness increase amount The calculation can be performed based on the difference between the area ratio of this layer and the threshold. One feasible calculation formula is as follows:

[0047] in: This represents the required increase in stiffener thickness. It is the gain coefficient. It is a preset ratio threshold. This is the area ratio of the current potential stress concentration layer. This is the current stiffener thickness value for the stiffener section. It's understandable that a larger difference indicates a greater increase in thickness. Update the thickness value of the corresponding stiffener section in the thin plate thickness gradient mapping table. Then, re-execute the step of generating a composite thin plate model with conformal shape control features, i.e., regenerate the stiffener entity based on the updated topology parameters and perform Boolean merging to obtain a new, optimized composite thin plate model. Slice this new model again and calculate the area ratio of each layer, repeating the above process of comparison, marking, positioning, thickening, and model reconstruction until the area ratio values ​​of all sliced ​​layers are calculated. All are not lower than the preset ratio threshold Optionally, a maximum number of iterations can be set to prevent infinite loops. In a data comparison example, the initial model had area ratios of 0.12, 0.10, 0.11, 0.13, 0.09, and 0.14 in regions numbered 120 to 125 (Z height 6.0-6.25mm), all below the threshold of 0.15. After one iteration of optimization, by thickening the three main reinforcing ribs passing through this region, the area ratios of each layer in this region increased to 0.16, 0.17, 0.18, 0.19, 0.16, and 0.20, all meeting the requirements.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for designing conformal shape control thin plates with anti-deformation and reduced support in metal SLM forming, characterized in that, The method includes: Collect geometric model data and SLM forming process parameter data of the target thin plate part. The geometric model data includes the thickness distribution field and surface curvature distribution map of the thin plate. An improved thin-shell finite element analysis algorithm is executed on the geometric model data. The improved thin-shell finite element analysis algorithm is constructed based on the equilibrium differential equation of classical thin-shell theory to generate the thermo-mechanical coupling deformation prediction field of the target thin-plate part during the layer-by-layer scanning process. Based on the nodal displacement and unit warping angle in the thermo-coupled deformation prediction field, the coordinate set of the easily deformable region and the boundary line of the region requiring support of the target thin plate part are determined. Based on the coordinate set of the easily deformable region and the boundary line of the region requiring support, the topological configuration parameters of the conformal control thin plate are generated. The topological configuration parameters include the spatial layout trajectory of the stiffeners and the thickness gradient mapping table of the thin plate. The topological configuration parameters of the conformal control sheet are embedded into the original geometric model of the target sheet part to generate a composite sheet model containing conformal control features.

2. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 1, characterized in that, An improved thin-shell finite element analysis algorithm is executed on the geometric model data. This algorithm, based on the equilibrium differential equations of classical thin-shell theory, generates a predicted thermo-mechanical coupling deformation field for the target thin-plate part during the layer-by-layer scanning process, including: The neutral surface geometric parameters and the thickness distribution field of the target thin plate part are extracted from the geometric model data. The neutral surface geometric parameters include the neutral surface spatial coordinates and the neutral surface normal vector. Based on the neutral surface geometric parameters and the thin plate thickness distribution field, the target thin plate part is discretized into multiple thin shell elements, each of which contains three corner nodes and one thickness integration point; For each thin-shell unit, the laser scanning path and laser energy density value are extracted from the SLM forming process parameter data, and the transient temperature load of the thin-shell unit in the time series is calculated based on the laser scanning path and laser energy density value. The transient temperature load is applied to the three corner nodes of the thin shell element. By solving the equilibrium differential equation in the improved thin shell finite element analysis algorithm, the displacement components of each corner node in three spatial directions are obtained. The displacement components of all corner nodes of all thin-shell units are assembled into field quantities to generate a node displacement cloud map covering the entire geometric region of the target thin-plate part, which serves as the thermo-mechanical coupling deformation prediction field.

3. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 2, characterized in that, By solving the equilibrium differential equations in the improved thin-shell finite element analysis algorithm, the displacement components of each corner node in three spatial directions are obtained, including: For the current thin-shell unit, extract the initial coordinates of the three corner nodes of the current thin-shell unit and the temperature gradient value at the thickness integration point of the current thin-shell unit; Based on the temperature gradient value and the material thermal expansion coefficient of the target thin plate part, calculate the thermal strain tensor components inside the current thin shell unit; The thermal strain tensor components are converted into equivalent nodal thermal load vectors, and the equivalent nodal thermal load vectors are superimposed on the external force load terms of the equilibrium differential equation. The Kirchhoff assumption of thin shell theory is introduced into the geometric equation of the equilibrium differential equation. The Kirchhoff assumption stipulates that the normal to the neutral surface remains straight and perpendicular to the neutral surface after deformation during the deformation of the thin shell. Based on the Kirchhoff assumption, the equilibrium differential equation is discretized using Galerkin weighted residuals to form a system of linear algebraic equations between the element stiffness matrix and the nodal displacement column vectors. The displacement components of the three corner nodes are obtained by solving the system of linear algebraic equations.

4. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 1, characterized in that, Based on the nodal displacements and element warping angles in the thermo-coupled deformation prediction field, the coordinate set of the easily deformable regions and the boundary lines of the support-required regions of the target thin plate part are determined, including: Scan the displacement of each node in the thermo-coupled deformation prediction field, and mark the nodes whose absolute value of the node displacement exceeds the preset warping threshold as a high deformation node candidate set. For each high deformation node in the candidate set of high deformation nodes, extract the thin shell element to which the high deformation node belongs and calculate the relative displacement difference between the three corner nodes of the thin shell element; The unit warpage angle of the thin shell unit is calculated based on the relative displacement difference, and the thin shell unit whose absolute value of the unit warpage angle exceeds the preset warpage angle threshold is marked as a deformable unit. The spatial coordinate regions covered by all deformable units are merged into an initial deformable region. A morphological closing operation is performed on the initial deformable region to fill the internal holes of the region, generating the final set of coordinates of the deformable region. Extract the convex hull boundary line of the coordinate set of the easily deformable region, and offset the convex hull boundary line outward by a preset support safety distance to obtain the boundary line of the region that needs support.

5. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 4, characterized in that, The process of merging the spatial coordinate regions covered by all deformable units into an initial deformable region, performing a morphological closing operation on the initial deformable region to fill the internal holes, and generating the final set of deformable region coordinates includes: Extract the spatial coordinate information of all easily deformable elements, and connect the spatial coordinates of the three corner nodes of each easily deformable element to form a triangular patch; Perform a union Boolean operation on the triangular facets in three-dimensional space to form a three-dimensional volume region that includes the coverage of all deformable units, and mark the three-dimensional volume region as the initial deformable region; A two-dimensional discrete mesh is constructed on the surface of the initial deformable region, wherein the unit size of the two-dimensional discrete mesh is smaller than the preset hole recognition resolution; Traverse each grid cell in the two-dimensional discrete grid and calculate whether the center point of the grid cell is located inside the initial deformable region. If the center point is located outside the initial deformable region but the center points of the adjacent grid cells in its preset neighborhood are all located inside, then the grid cell is identified as an internal hole cell. The coordinates of the center points of all identified internal hole units are added to the initial coordinate set of the easily deformable region, and the updated coordinate set is defined as the final coordinate set of the easily deformable region.

6. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 1, characterized in that, Based on the coordinate set of the easily deformable region and the boundary line of the region requiring support, the topological configuration parameters of the conformal control thin plate are generated, including: The area enclosed by the boundary line of the area to be supported is taken as the core area for the arrangement of reinforcing ribs. Within the core area, a set of candidate reinforcing rib trajectory lines is generated according to the preset initial rib spacing. For each candidate stiffener trajectory line in the set of candidate stiffener trajectory lines, calculate the spatial overlap length between the candidate stiffener trajectory line and the coordinate set of the easily deformable region; Candidate reinforcing rib trajectory lines whose spatial overlap length exceeds a preset overlap threshold are retained as valid reinforcing rib trajectory lines, while candidate reinforcing rib trajectory lines whose spatial overlap length does not exceed the preset overlap threshold are deleted. A gradually varying rib thickness is provided along the extension direction of the effective reinforcing rib trajectory line. The gradually varying rib thickness takes the maximum value in the overlapping section of the effective reinforcing rib trajectory line and the coordinate set of the easily deformable area, and takes the minimum value at the end of the effective reinforcing rib trajectory line away from the coordinate set of the easily deformable area. The spatial coordinate sequence of the effective stiffener trajectory line and the corresponding gradient stiffener thickness value are stored in a structured manner to generate the spatial layout trajectory of the stiffener and the thickness gradient mapping table of the thin plate.

7. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 6, characterized in that, The thickness of the reinforcing rib is gradually varied along the extension direction of the effective reinforcing rib trajectory line, including: For the current effective stiffener trajectory line, extract the original substrate thickness value of the target thin plate part at the location of the current effective stiffener trajectory line from the geometric model data; Based on the spatial range of the coordinate set of the easily deformable region, high deformation section, transition section and low deformation section are divided on the trajectory line of the current effective stiffener; Within the high deformation zone, the rib thickness is set to the result of multiplying the original substrate thickness by a thickness multiplication factor, wherein the value of the thickness multiplication factor is proportional to the average value of the node displacement within the high deformation zone. Within the low-deformation zone, the rib thickness is set to be equal to the original substrate thickness value; Within the transition zone, the rib thickness is determined using linear interpolation. The starting thickness of the linear interpolation is the rib thickness at the end of the high deformation zone, and the ending thickness is the rib thickness at the beginning of the low deformation zone.

8. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 1, characterized in that, The topological configuration parameters of the conformal-shaped thin plate are embedded into the original geometric model of the target thin plate part to generate a composite thin plate model containing conformal-shaped features, including: Read the spatial layout trajectory of the reinforcing ribs and the thickness gradient mapping table of the thin plate from the topological configuration parameters of the conformal control thin plate; Based on the spatial layout trajectory of the reinforcing ribs, a solid sweeping body of the reinforcing ribs is generated at the corresponding spatial position of the original geometric model of the target thin plate part. The cross-sectional shape of the solid sweeping body of the reinforcing ribs is a trapezoidal cross-section, and the ratio of the width of the upper base to the width of the lower base of the trapezoidal cross-section is determined by the local curvature of the target thin plate part. Based on the thickness values ​​in the thin plate thickness gradient mapping table, a thickness replacement operation is performed on a local area of ​​the original geometric model of the target thin plate part. The thickness replacement operation is used to update the original thickness values ​​to the thickness values ​​in the thin plate thickness gradient mapping table. Perform a Boolean union operation on the geometric model of the target thin plate part after thickness replacement and the solid swept body of the reinforcing rib to generate a composite thin plate model with conformal shape control features that is expressed as an integrated whole. A model repair check is performed on the composite thin plate model, which includes overlapping surface deletion and non-manifold edge repair operations.

9. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 8, characterized in that, Based on the spatial layout trajectory of the reinforcing ribs, a solid swept body of the reinforcing ribs is generated at the corresponding spatial position of the original geometric model of the target thin plate part, including: Extract the spatial coordinate sequence of the trajectory control points and the rib thickness value at the trajectory control points from the spatial layout trajectory of the reinforcing ribs; The rib thickness at each trajectory control point is used as the median length of the trapezoidal cross section, and the upper and lower base widths of the trapezoidal cross section are determined based on the local curvature of the target thin plate part. Using the spatial coordinates of the trajectory control point as the section positioning point, and the tangent direction of the spatial layout trajectory of the reinforcing rib as the section normal direction, a corresponding trapezoidal section profile is placed at each trajectory control point. The 3D sweep modeling kernel is invoked to perform linear skinning on the trapezoidal cross-sectional contours between adjacent trajectory control points, generating multi-segment prism entities. The multiple prism entities are sequentially subjected to Boolean union and set-up operations to form a continuously extending baffle body of the reinforcing rib entity.

10. The method for designing a conformal shape-controlled thin plate with anti-deformation and reduced support in metal SLM forming according to claim 1, characterized in that, The method also includes an iterative process of optimizing interlayer stress on the composite thin plate model containing conformal shape control features: The composite thin plate model containing conformal shape control features is imported into the slicing data processing software to generate a layer-by-layer slicing image sequence containing the outline of the part and the outline of the reinforcing rib. Calculate the ratio of the area of ​​the reinforcing rib region to the area of ​​the main body region of the part in each slice layer based on the layer-by-layer slice image sequence; The ratio value is compared with a preset ratio threshold layer by layer. When the ratio value of a certain layer is lower than the preset ratio threshold, the layer is marked as a potential stress concentration layer. Extract the layer number of the potential stress concentration layer, and locate the reinforcing rib segment that intersects with the potential stress concentration layer from the spatial layout trajectory of the reinforcing ribs; Increase the rib thickness value of the reinforcing rib section, and repeat the step of generating a composite thin plate model with conformal shape control features until the proportion value of all slice layers is not lower than the preset proportion threshold.

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