A stress-optimized method for generating printed slice images

Abstract

This application relates to the technical field of printing slice optimization, and discloses a stress-optimized method for generating printing slice images. The steps include: acquiring a three-dimensional model to be printed; slicing the three-dimensional model to generate a printing path for each printing layer; performing layer-by-layer printing based on the printing path, and collecting strain data of the printing substrate and process parameters of the current printing layer; solving for stress distribution data of the current printing layer based on the strain data of the printing substrate and the process parameters of the current printing layer; identifying stress conduction zones and stress maintenance zones in the current printing layer based on the stress distribution data; adjusting the printing path of the printing layer to be printed based on the positional distribution of the stress conduction zones and stress maintenance zones, and generating corresponding printing slice images. This application effectively solves the stress accumulation problem in large-scale concrete 3D printing through slice image generation optimization.

Description

Technical Field

[0001] This application relates to the technical field of print slice optimization, specifically to a stress-optimized print slice image generation method. Background Technology

[0002] 3D printing creates customized parts with complex structures by layer-by-layer material deposition. Planning the printing path and generating slice images are core preliminary steps. The 3D model to be printed must first be sliced, dividing it into several layers of 2D images, and a specific printing path is generated based on these slice images. The rationality of the printing path directly affects the structural accuracy, surface quality, and internal mechanical properties of the finished product. Existing methods for generating printing slice images have some shortcomings.

[0003] Existing slice image generation methods primarily focus on the geometric visualization of the printing path, neglecting interlayer stress changes during the printing process. This makes it difficult to monitor and respond to stress changes in a timely and accurate manner. In actual printing, factors such as thermal stress, material shrinkage, and unstable process parameters can easily lead to residual stress and defect areas within the printed structure, resulting in structural deformation, cracking, or a decline in mechanical properties. However, traditional slice image generation methods struggle to achieve coordinated optimization of the printing path and internal stress state. Existing slice images also have limitations in representing functional areas and designing differentiated paths. Printing complex structures often involves critical areas of stress concentration or functional reinforcement zones, but traditional slice images fail to clearly distinguish the path layout and performance differences between different areas. Path strategy designs are often based on uniform templates, lacking the ability to differentiate image representation and path adjustments according to structural functional requirements and stress distribution results.

[0004] For example, Chinese Patent CN113421203B discloses an image processing method, a printing method, a printing-related device, and a readable storage medium, relating to the field of printing technology. The image processing method includes: acquiring N layer slice images of a target model, where N is an integer greater than 1; performing spatial filtering on the pixels in the N layer slice images; and performing image enhancement processing on the pixels in the spatially filtered N layer slice images to obtain a target slice image of the target model. In this way, spatial filtering can be performed on the pixels in the N layer slice images, allowing the grayscale values ​​of the spatially filtered pixels to be adjusted based on the grayscale values ​​of spatially adjacent pixels. Then, image enhancement processing is performed on the spatially filtered N layer slice images to control the degree of resin curing at the corresponding positions of edge pixels, thus effectively reducing pixel layer textures in the target model and improving the printing quality of the target model.

[0005] For example, Chinese patent application CN117934755A discloses a 3D printing slice generation method, which includes the following steps: preset three-dimensional model parameters; form a spatial mesh set according to the three-dimensional model parameters; traverse the spatial mesh set, obtain triangular facets in all spatial meshes to form a triangular facet set, and analyze the triangular facet set to obtain line segment groups; traverse each segmentation layer, obtain line segment group data according to the segmentation layer, and traverse the line segment group data to form contour lines; perform closure processing on the contour lines of each segmentation layer, and output the 3D printed filled contour; by optimizing the slice generation method, only one traversal of triangular facets is needed, reducing the time and space complexity of the entire slice generation method and improving the generation efficiency of contour lines in the slice.

[0006] All of the above technical solutions suffer from the problem mentioned in the background of this application: it is difficult to monitor and respond to stress changes during the printing process in a timely and accurate manner.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The technical problem to be solved by this application is to overcome the defects of the prior art and provide a stress-optimized method for generating printed slice images. By optimizing the generation of slice images, the stress accumulation problem in large-scale concrete 3D printing can be effectively solved.

[0009] To solve the above-mentioned technical problems, this application provides the following technical solution:

[0010] A stress-optimized method for generating printed slice images includes the following steps:

[0011] Obtain the 3D model to be printed; slice the 3D model to generate the printing path for each printing layer;

[0012] Layered printing is performed based on the printing path, and strain data of the printing substrate and process parameters of the current printing layer are collected.

[0013] The stress distribution data of the current printed layer is calculated based on the strain data of the printed substrate and the process parameters of the current printed layer.

[0014] Based on the stress distribution data, identify the stress transmission zone and stress maintenance zone in the current printed layer;

[0015] Based on the positional distribution of the stress transmission zone and the stress maintenance zone, the printing path of the printing layer to be printed is adjusted, and the corresponding printing slice image is generated.

[0016] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the strain data is acquired based on strain gauges arranged on the printing substrate; the process parameters of the current printing layer include printing path geometric features, printing layer process features, and printing material features.

[0017] The stress distribution data of the current printed layer is calculated based on the strain data of the printing substrate and the process parameters of the current printed layer. Specifically, this includes: identifying the stress distribution pattern of the current printed layer based on the process parameters; and calculating the stress distribution data of the current printed layer based on the stress distribution pattern and the strain data of the printing substrate. The method for identifying the stress distribution pattern of the current printed layer is as follows:

[0018] Set different process parameters and conduct printing experiments; record the stress distribution data corresponding to each set of process parameters; establish a reference database, wherein any reference data in the reference database includes a set of process parameters and the corresponding stress distribution data;

[0019] Based on the stress distribution data of each set of process parameters, determine the stress distribution pattern of each reference data point;

[0020] Calculate the similarity between the process parameters of the current printing layer and the process parameters of each reference data;

[0021] The stress distribution pattern of the reference data with the highest similarity is taken as the stress distribution pattern of the current printing layer.

[0022] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the method involves: solving for the stress distribution data of the current printed layer based on the stress distribution pattern and the strain data of the printed substrate, specifically including:

[0023] Obtain the strain parameters of the printing material; the strain parameters include elastic modulus and Poisson's ratio.

[0024] Based on the generalized Hooke's law and the strain parameters, a strain-stress transfer matrix is ​​constructed.

[0025] Based on the strain-stress transfer matrix and the strain data of the printed substrate, a set of strain-stress transfer equations is constructed.

[0026] Construct constraints based on the stress distribution pattern of the current printed layer;

[0027] Solving the strain-stress transfer equations using Tikhonov regularization yields stress distribution data for the current printed layer that satisfies the constraints.

[0028] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the method includes: identifying stress conduction zones in the current printed layer based on the stress distribution data, specifically including:

[0029] Based on the stress distribution data, calculate the stress gradient value and stress gradient direction at each position in the current printing layer; obtain the printing path direction at each position in the current printing layer; the printing path direction is the direction in which the print head moves at the corresponding position;

[0030] If the stress gradient value at any position in the current printed layer is greater than the preset stress gradient threshold, and the angle between the stress gradient direction at the corresponding position and the printing path direction is less than the preset direction angle threshold, then the corresponding position is a stress transmission point.

[0031] Record the location of each stress transmission point, and connect the stress transmission points into a connected stress transmission region using a region connection algorithm.

[0032] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the method includes: identifying stress-maintaining regions in the current printed layer based on the stress distribution data, specifically including:

[0033] Based on the stress distribution data, the elastic strain energy density at each location in the current printed layer is calculated;

[0034] If the ratio of the elastic strain energy density at any position in the current printed layer to the average elastic strain energy density of the current printed layer is greater than the preset energy threshold coefficient, and the rate of change of the elastic strain energy density at the corresponding position is less than the preset energy rate of change threshold, then the corresponding position is a stress maintenance point.

[0035] Record the location of each stress sustaining point, and connect the stress sustaining points into a connected stress sustaining region using a region connection algorithm.

[0036] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the step of adjusting the printing path of the printing layer to be printed includes a path strategy for generating stress transmission zones; the path strategy for stress transmission zones specifically includes:

[0037] The path intersection angle of the stress transmission zone is adjusted from a first angle to a second angle; wherein, the first angle is a preset basic path intersection angle; and the second angle is a preset dispersion angle.

[0038] Calculate the average stress value at each stress transmission point in the stress transmission zone based on the stress distribution data of the current printed layer;

[0039] The number of delay layers is calculated based on the average stress value, wherein the number of delay layers is positively correlated with the average stress value;

[0040] Based on the number of delay layers, delayed printing is performed on the stress transmission zone.

[0041] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the adjustment of the printing path of the printing layer to be printed further includes a path strategy for generating a stress-maintaining region; the path strategy for the stress-maintaining region specifically includes:

[0042] Calculate the mean elastic strain energy density at each stress maintenance point in the stress maintenance zone; calculate the dispersion of the stress gradient direction at each stress maintenance point in the stress maintenance zone based on the stress distribution data of the current printed layer;

[0043] The fractal level is determined based on the mean of the elastic strain energy density and the dispersion of the stress gradient direction;

[0044] Based on the fractal level, fractal path filling is performed on the stress maintenance region.

[0045] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the step of adjusting the printing path of the printing layer to be printed further includes path planning for the overlapping area; the overlapping area is the overlapping region of the stress transmission area and the stress maintenance area.

[0046] Path planning for the overlapping area specifically includes: marking the location of the overlapping area between the stress transmission area and the stress maintenance area based on the location distribution of the stress transmission area and the stress maintenance area, and calculating the area of ​​the overlapping area;

[0047] Set an area threshold for the overlapping region; if the area of ​​the overlapping region is less than or equal to the area threshold, then simulate the path strategy of the stress conduction region for the overlapping region and obtain the first energy release amount; simulate the path strategy of the stress maintenance region for the overlapping region and obtain the second energy release amount; if the first energy release amount is greater than the second energy release amount, then execute the path strategy of the stress conduction region for the overlapping region, otherwise execute the path strategy of the stress maintenance region for the overlapping region; if the area of ​​the overlapping region is greater than the area threshold, then generate at least N sets of hybrid path strategies; any set of hybrid path strategies includes the path strategy of the stress conduction region and the path strategy of the stress maintenance region; N is a positive integer; simulate and execute each set of hybrid path strategies for the overlapping region respectively, and obtain the third energy release amount corresponding to each set of hybrid path strategies, and select the hybrid path strategy with the highest third energy release amount as the path strategy of the overlapping region.

[0048] As a preferred embodiment of the stress-optimized printed slice image generation method described in this application, the step of obtaining the first energy release specifically includes: establishing a finite element simulation model for three-dimensional model printing, and marking the stress distribution data and elastic strain energy density distribution data of the current printed layer; simulating the execution of the path strategy for the stress conduction zone through the finite element simulation model, and obtaining the distribution data of the elastic strain energy density of the current printed layer after executing the path strategy for the stress conduction zone; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the path strategy for the stress conduction zone over the volume of the printed layer to obtain the first energy release.

[0049] The acquisition of the second energy release amount specifically includes: simulating the execution of the path strategy of the stress maintenance zone through a finite element simulation model, and acquiring the distribution data of the elastic strain energy density of the current printed layer after executing the path strategy of the stress maintenance zone; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the path strategy of the stress maintenance zone over the volume of the printed layer to obtain the second energy release amount.

[0050] The process of obtaining the third energy release amount corresponding to each group of hybrid path strategies specifically includes: simulating any group of hybrid path strategies using a finite element simulation model, obtaining the distribution data of the elastic strain energy density of the current printed layer after executing the hybrid path strategy; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the hybrid path strategy over the volume of the printed layer to obtain the third energy release amount corresponding to the hybrid path strategy.

[0051] As a preferred embodiment of the stress-optimized printing slice image generation method described in this application, the method involves slicing the three-dimensional model to generate a printing path for each printing layer, specifically including:

[0052] The 3D model is sliced ​​using a slicing engine to generate path data files for each printing layer. The path data files include contour information, fill information, and printing path for each printing layer. The contour information describes the boundary contour of the corresponding printing layer. The fill information describes the fill area inside the boundary contour of the corresponding printing layer. The printing path includes a coordinate sequence describing the movement trajectory of the print head within the boundary contour and the fill area.

[0053] The process of generating the corresponding print slice image specifically includes: visualizing the path data file to generate the print slice image of the corresponding print layer; and visually annotating the stress transmission area and stress maintenance area of ​​the current print layer in the print slice image.

[0054] Compared with the prior art, the beneficial effects achieved by this application are as follows:

[0055] This application optimizes and adjusts the printing path by incorporating real-time stress distribution data during the generation of slice images. The optimization results are directly reflected in the final slice images, achieving closed-loop control between path adjustment and image regeneration. This significantly improves the rationality of the printing path design and the overall performance of the finished structure. By distinguishing between stress transmission and stress maintenance zones in the slice images and combining the region division results, the corresponding path layout and parameter settings are flexibly adjusted to generate differentiated and targeted printing paths, effectively improving the structural performance and mechanical response of different functional areas. Attached Figure Description

[0056] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0057] Figure 1 A flowchart of a stress-optimized method for generating printed slice images provided in this application;

[0058] Figure 2 A flowchart of the method for identifying the stress distribution pattern of the current printed layer based on process parameters provided in this application;

[0059] Figure 3 This is a schematic diagram of a partial path direction for concrete 3D printing provided in this application. Detailed Implementation

[0060] The technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of this application, rather than limitations thereof. In the absence of conflict, the embodiments and technical features in the embodiments can be combined with each other.

[0061] This embodiment introduces a stress-optimized method for generating printed slice images, which can be applied to the 3D printing of large-scale concrete. (Refer to...) Figure 1 , the method comprises the following steps:

[0062] Obtain the 3D model to be printed; in this embodiment, an STL (stereolithography) file is preferred as the format for saving the 3D model; the STL file is used to describe the external contour and internal structure of the 3D model to be printed;

[0063] The 3D model is sliced ​​to generate a printing path for each printing layer; specifically, this includes slicing the 3D model using a slicing engine to generate a path data file for each printing layer.

[0064] In this embodiment, the slicing engine is preferably used to slice the STL file. Specifically, the slicing parameters are set using a preset configuration file, the slicing command is executed, and a path data file for each printing layer is generated. The path data file is in standard G-code format.

[0065] The path data file includes contour information, fill information, and print path for each print layer; wherein, the contour information is used to describe the boundary contour of the corresponding print layer; the fill information is used to describe the fill area inside the boundary contour of the corresponding print layer; and the print path includes a coordinate sequence for describing the movement trajectory of the print head in the boundary contour and the fill area.

[0066] The slicing engine reads the STL file, places the 3D model in a coordinate system, and then cuts the model using a series of planes parallel to the XY plane according to the set layer height, resulting in different 2D slices. Each 2D slice corresponds to a printing layer. The slicing engine uses a 2D graphics processing library to divide each 2D slice into different components, such as exterior walls, interior walls, infill areas, top and bottom surfaces, and supports, and generates printing paths based on these components. For example, for exterior and interior walls, the outlines are repeatedly drawn to improve surface quality; for infill areas, infill paths are generated according to the set infill rate and pattern; and for top and bottom surfaces, complete planar infill paths are generated.

[0067] Layered printing is performed based on the printing path, and strain data of the printing substrate and process parameters of the current printing layer are collected.

[0068] The strain data is acquired based on strain gauges arranged on a printed substrate;

[0069] The process parameters of the current printing layer include printing path geometric features, printing layer process features, and printing material features. In this embodiment, the preferred printing path geometric features include the radius of curvature of the printing path. The mean value of the radius of curvature of the printing path is statistically analyzed segment by segment to form the geometric features of the entire printing path. This embodiment also preferably includes printing layer process features such as path intersection angle and infill spacing. The path intersection angle is the angle between the current printing layer and the previous layer; the infill spacing is the distance between adjacent printing paths in the current printing layer. This embodiment also preferably includes printing material features such as extrusion rate and printing layer thickness. Furthermore, the process parameters of the current printing layer are normalized and encoded into a fixed-length feature vector to provide a data foundation for identifying stress distribution patterns.

[0070] The stress distribution data of the current printed layer is calculated based on the strain data of the printing substrate and the process parameters of the current printed layer; specifically, this includes: identifying the stress distribution pattern of the current printed layer based on the process parameters, and calculating the stress distribution data of the current printed layer based on the stress distribution pattern and the strain data of the printing substrate; (Refer to...) Figure 2 The method for identifying the stress distribution pattern of the current printed layer is as follows:

[0071] Different process parameters are set and concrete 3D printing experiments are conducted; each set of process parameters includes the geometric features of the printing path, the process features of the printing layer, and the features of the printing material; stress distribution data corresponding to each set of process parameters is recorded; a reference database is established, and any reference data in the reference database includes a set of process parameters and the corresponding stress distribution data; in this embodiment, the preferred storage structure of the reference database is indexed storage.

[0072] Based on the stress distribution data of each set of process parameters, determine the stress distribution pattern of each reference data point;

[0073] The stress distribution pattern is the stress distribution law of the printed layer determined based on stress distribution data. Under the same or highly similar process parameters, the stress distribution of the printed layer follows a similar stress distribution law. By collecting and summarizing stress distribution data of typical path patterns (such as circular printing paths, spiral printing paths, etc.), a mapping relationship between typical path patterns and stress distribution patterns is established. If the process parameters of the current printed layer are highly similar to those of a certain typical path pattern, then the printing load of the current printed layer and that typical path pattern are similar, and the stress distribution has a similar law. Some preferred stress distribution patterns in this embodiment are as follows: For a circular printing path, the stress distribution pattern includes: radial stress symmetry error less than 5%; for a spiral printing path, the stress distribution pattern includes: tangential stress attenuation rate less than 15% per millimeter; for Z-shaped filling, the stress distribution pattern includes: fluctuation range of the ratio of transverse stress to longitudinal stress less than 30%, etc.

[0074] Calculate the similarity between the process parameters of the current printing layer and the process parameters of each reference data; in this embodiment, the process parameters of each reference data are preferably normalized and encoded into a feature vector of fixed length, and the Euclidean distance is further calculated as the similarity between the process parameters.

[0075] The stress distribution pattern of the reference data with the highest similarity is taken as the stress distribution pattern of the current printing layer. In this embodiment, if the similarity between the process parameters of the current printing layer and the process parameters of each reference data is low, for example, all are below a preset similarity threshold, then the sub-vector corresponding to the geometric features of the printing path is extracted from the feature vector of each process parameter to replace the original feature vector, and the similarity is recalculated.

[0076] The method for solving the stress distribution data of the current printed layer based on the stress distribution pattern and the strain data of the printed substrate is as follows:

[0077] Obtain the strain parameters of the printing material; the strain parameters include elastic modulus and Poisson's ratio.

[0078] Based on the generalized Hooke's law and the strain parameters, a strain-stress transfer matrix is ​​constructed. The strain-stress transfer matrix is ​​used to map the strain data of the printing substrate to the stress distribution data of the current printing layer, reflecting the linear relationship between strain and stress. The matrix elements are uniquely determined by the strain parameters (elastic modulus, Poisson's ratio) of the printing material, reflecting the stiffness characteristics of the material.

[0079] Based on the strain-stress transfer matrix and the strain data of the printed substrate, a system of strain-stress transfer equations is constructed; by substituting the discrete strain data into the strain-stress transfer matrix, a system of strain-stress transfer equations is formed, as follows:

[0080] σ=Kε;

[0081] Where K is the strain-stress transfer matrix; σ represents the tensor composed of the stress distribution data of the current printing layer; and ε represents the tensor composed of the strain data of the printing substrate.

[0082] Constraints are constructed based on the stress distribution pattern of the current printed layer; for example, the tangential stress attenuation rate per millimeter is less than 15%.

[0083] The strain-stress transfer equations are solved using Tikhonov regularization to obtain stress distribution data for the current printed layer that satisfies the constraints. Traditional constraints only consider rigid physical laws and fail to account for the stress distribution pattern under current process parameters. This application treats the constraints as extended regularization terms and employs constrained optimization algorithms (such as interior point method and projected gradient method) to solve the equations, improving the physical rationality of the solution.

[0084] This application uses strain data from a limited number of measurement points on a printed substrate to inversely extrapolate the stress distribution of the printed layer. A mathematical mapping relationship between local strain and global stress is established, allowing stress distribution data to be acquired without densely arranging sensors on the printed layer surface. The strategy of arranging a limited number of substrate strain gauges satisfies the feasibility of installation in industrial settings, while the constraints of the strain-stress transfer equations and stress distribution patterns compensate for the sparseness of observation points. The regularization parameters of the Tikhonov regularization are calibrated using historical experimental data, balancing computational efficiency and accuracy.

[0085] Based on the stress distribution data, identify the stress transmission zone and stress maintenance zone in the current printed layer;

[0086] The method for identifying stress conduction zones in the current printed layer is as follows:

[0087] Based on the stress distribution data, calculate the stress gradient value and stress gradient direction at each position in the current printing layer; obtain the printing path direction at each position in the current printing layer; the printing path direction is the direction in which the print head moves at the corresponding position;

[0088] If the stress gradient value at any location in the current printed layer is greater than a preset stress gradient threshold, and the angle between the stress gradient direction at that location and the printing path direction is less than a preset orientation angle threshold, then that location is a stress transmission point. The stress transmission zone is the area where stress can be efficiently transmitted through the printing path. A stress gradient value greater than the preset stress gradient threshold indicates that the stress changes rapidly at that location; if the stress gradient is insufficient, an effective stress transmission channel cannot be formed. In this embodiment, the preferred orientation angle threshold is 15 degrees. If the angle between the stress gradient direction and the printing path direction is less than 15 degrees, the stress transmission direction is consistent with the path designed in the process. If the angle is too large, the stress will deviate from the expected path, leading to stress transmission failure.

[0089] The location of each stress transmission point is recorded, and these points are connected into connected stress transmission regions using a region connectivity algorithm. This embodiment preferably uses the DBSCAN clustering algorithm to connect stress transmission points into stress transmission regions, enabling rapid output of connected regions and ensuring real-time concrete printing.

[0090] The method for identifying stress-maintaining zones in the current printed layer is as follows:

[0091] Based on the stress distribution data, the elastic strain energy density at each location in the current printed layer is calculated;

[0092] If the ratio of the elastic strain energy density at any position in the current printed layer to the mean elastic strain energy density of the current printed layer is greater than the preset energy threshold coefficient, and the rate of change of the elastic strain energy density at the corresponding position is less than the preset energy rate change threshold, then the corresponding position is a stress maintenance point; the energy threshold coefficient and the energy rate change threshold are determined based on expert experience or statistical analysis of a large amount of experimental data.

[0093] The preferred method for calculating the rate of change of elastic strain energy density in this embodiment is as follows: the elastic strain energy density is calculated every t milliseconds, and the change in elastic strain energy density is divided by the time interval t to obtain the rate of change of elastic strain energy density. Stress concentration or residual stress accumulation results in a high elastic strain energy density in the stress-maintaining zone, and the stress cannot be effectively transmitted and released, leading to a high risk of structural damage. Identifying potential damage areas through elastic strain energy density captures weak points where the stress gradient is not significant but energy has accumulated, overcoming the limitations of traditional single stress parameter analysis and improving the comprehensiveness of defect detection.

[0094] Record the location of each stress sustaining point, and connect the stress sustaining points into a connected stress sustaining region using a region connection algorithm.

[0095] Based on the positional distribution of the stress transmission zone and the stress maintenance zone, the printing path of the printing layer to be printed is adjusted, and the corresponding printing slice image is generated.

[0096] The adjustment of the printing path of the printing layer to be printed includes a path strategy for generating stress transmission zones; the path strategy for stress transmission zones specifically includes:

[0097] The path intersection angle of the stress transmission zone is adjusted from a first angle to a second angle; wherein, the first angle is a preset basic path intersection angle; the second angle is a preset dispersion angle; in this embodiment, the first angle is preferably 30 degrees and the second angle is 60 degrees. (Refer to...) Figure 3 Parallel lines intersecting with directional arrows on the surface of the concrete print indicate the partial printing path of the current print layer that has been printed; a set of hollow arrows intersecting with them indicate the direction of the next print path in the normal area that is neither a stress transmission zone nor a stress maintenance zone, and the angle between this print path and the print path of the current print layer is A1, where A1 is the first angle, i.e., 30 degrees. Figure 3 A set of gray solid arrows indicates the printing path direction of the stress transmission zone. The included angle of the printing path of the current printing layer is A2, which is the second angle, i.e., 60 degrees.

[0098] Calculate the average stress value at each stress transmission point in the stress transmission zone based on the stress distribution data of the current printed layer;

[0099] The number of delay layers is calculated based on the average stress value, wherein the number of delay layers is positively correlated with the average stress value;

[0100] Based on the number of delay layers, delayed printing is performed on the stress transmission zone.

[0101] In this embodiment, the preferred method for calculating the number of delay layers is as follows: a reference stress value is set; the difference between the average stress value of the stress conduction zone and the reference stress value is calculated; the number of delay layers is set according to the magnitude of the difference, with a larger difference resulting in a higher number of delay layers, and the maximum number of delay layers is 3 to prevent excessive delay. Furthermore, a ring-shaped region extending m centimeters outward from the boundary of the stress conduction zone is used as a transition zone; m is a positive integer; the path angle of the transition zone gradually changes from a second angle to a first angle to avoid abrupt stress changes.

[0102] By delaying printing, for example, postponing the printing of the stress conduction zone by one layer, the peak value of interlayer shear stress is reduced, which is beneficial to the setting of the underlying concrete and improves its shear strength. This avoids printing when the underlying concrete is not fully cured, as the shear stress may exceed the interlayer bond strength, causing interlayer delamination. Increasing the path intersection angle increases the interlayer shear contact area, thereby dispersing the stress direction to some extent and preventing shear stress concentration in the same direction from exacerbating local stress concentration. Delaying the printing of the stress conduction zone by one layer involves deleting the printing path of the stress conduction zone in the next printed layer and adding it to the corresponding position in the next subsequent printed layer.

[0103] The adjustment of the printing path of the printing layer to be printed also includes a path strategy for generating the stress-maintaining zone; the path strategy for the stress-maintaining zone specifically includes:

[0104] Calculate the mean elastic strain energy density at each stress maintenance point in the stress maintenance zone; calculate the dispersion of the stress gradient direction at each stress maintenance point in the stress maintenance zone based on the stress distribution data of the current printed layer;

[0105] The fractal level is determined based on the mean of the elastic strain energy density and the dispersion of the stress gradient direction;

[0106] Based on the fractal level, fractal path filling is performed on the stress maintenance region.

[0107] In this embodiment, the Koch curve is preferred as the fractal path for the stress sustaining zone. Further, the standard deviation of the stress gradient direction at all stress sustaining points is calculated as the dispersion; a reference value is set for the mean of the elastic strain energy density; the fractal level, i.e., the iteration level of the Koch curve, is set based on the ratio of the mean elastic strain energy density to its reference value and the dispersion; the larger the ratio of the mean elastic strain energy density to its reference value, the greater the dispersion, and the higher the iteration level of the Koch curve, with a maximum iteration level of 3. Microcracks are placed at the corners of the fractal path to assist in energy dissipation.

[0108] By disrupting the stress transmission path using fractal paths, energy dissipation in the stress maintenance zone is promoted, while maintaining a high filling rate to avoid structural loosening.

[0109] The adjustment of the printing path of the printing layer to be printed also includes path planning for the overlapping area; the overlapping area is the overlapping region of the stress transmission area and the stress maintenance area; path planning for the overlapping area specifically includes:

[0110] Based on the location distribution of the stress conduction zone and the stress maintenance zone, mark the location of the overlapping area of ​​the stress conduction zone and the stress maintenance zone, and calculate the area of ​​the overlapping area;

[0111] Set an area threshold for the overlapping region; if the area of ​​the overlapping region is less than or equal to the area threshold, then simulate the path strategy of the stress conduction region for the overlapping region and obtain the first energy release amount; simulate the path strategy of the stress maintenance region for the overlapping region and obtain the second energy release amount; if the first energy release amount is greater than the second energy release amount, then execute the path strategy of the stress conduction region for the overlapping region, otherwise execute the path strategy of the stress maintenance region for the overlapping region.

[0112] The process of obtaining the first energy release amount specifically includes: establishing a finite element simulation model of concrete 3D printing and marking the stress distribution data and elastic strain energy density distribution data of the current printing layer; simulating the execution of the path strategy of the stress conduction zone through the finite element simulation model to obtain the distribution data of the elastic strain energy density of the current printing layer after executing the path strategy of the stress conduction zone; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the path strategy of the stress conduction zone over the volume of the printing layer to obtain the first energy release amount;

[0113] The acquisition of the second energy release amount specifically includes: simulating the execution of the path strategy of the stress maintenance zone through a finite element simulation model, and acquiring the distribution data of the elastic strain energy density of the current printed layer after executing the path strategy of the stress maintenance zone; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the path strategy of the stress maintenance zone over the volume of the printed layer to obtain the second energy release amount.

[0114] If the area of ​​the overlapping region is greater than the area threshold, at least N sets of hybrid path strategies are generated; each set of hybrid path strategies includes a path strategy for the stress transmission region and a path strategy for the stress maintenance region; N is a positive integer; each set of hybrid path strategies is simulated and executed for the overlapping region, and the third energy release corresponding to each set of hybrid path strategies is obtained, specifically including: simulating any set of hybrid path strategies through a finite element simulation model, obtaining the distribution data of the elastic strain energy density of the current printed layer after executing the hybrid path strategy; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the hybrid path strategy over the volume of the printed layer to obtain the third energy release corresponding to the hybrid path strategy; selecting the hybrid path strategy with the highest third energy release as the path strategy for the overlapping region.

[0115] When the stress conduction zone and the stress maintenance zone spatially overlap, path strategies also conflict. The stress conduction zone requires delayed printing to improve interlayer strength, while the stress maintenance zone needs immediate processing to prevent energy accumulation. The path strategies for both the stress conduction and stress maintenance zones are essentially designed to assist in stress release and reduce elastic strain energy. When the overlapping area is less than or equal to an area threshold, the path strategy that best reduces elastic strain energy is prioritized. When the overlapping area is greater than the area threshold, this embodiment preferably optimizes and explores a hybrid path strategy that releases the most elastic strain energy as the path planning result for the overlapping area, avoiding the situation where a single path strategy cannot meet the control objectives of the overlapping area.

[0116] The preferred hybrid path strategy in this embodiment is as follows: When printing the next layer, Koch fractal filling is first applied to the corresponding positions of the overlapping area, with a fractal level of 2, and microcracks with a length of 0.5 mm are set at the fractal corners; after delaying one layer, the path intersection angle at the corresponding positions of the overlapping area is adjusted to 60 degrees. By implementing the hybrid path strategy, the influence of fractal level and microcrack length on the contact area between printed layers is avoided, the execution effect of the path strategy in the stress transmission area is reduced, and the accumulation of new energy caused by the increase in the path intersection angle is avoided.

[0117] The process of generating the corresponding print slice image specifically includes: visualizing the path data file to generate the print slice image of the corresponding print layer; and visually annotating the stress transmission area and stress maintenance area of ​​the current print layer in the print slice image.

[0118] Print slice images are used to visualize the outline, infill, and print path of the printed layer, as well as the stress transmission and stress maintenance zones of the current printed layer. The path data file in G-code format is visualized on the software interface as print slice images, facilitating the viewing of printing results and manual adjustment of the print path. In particular, the coverage areas of the stress transmission and stress maintenance zones are clearly marked, making it easy for personnel to view and adjust the print path for different stress areas.

[0119] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0120] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of protection of this application, and these forms are all within the protection scope of this application.

Claims

1. A stress-optimized method for generating printed slice images, characterized in that: Includes the following steps: Obtain the 3D model to be printed; slice the 3D model to generate the printing path for each printing layer; Layered printing is performed based on the printing path, and strain data of the printing substrate and process parameters of the current printing layer are collected. The process involves solving the stress distribution data of the current printed layer based on the strain data of the printing substrate and the process parameters of the current printed layer, including: identifying the stress distribution pattern of the current printed layer based on the process parameters; and solving the stress distribution data of the current printed layer based on the stress distribution pattern and the strain data of the printing substrate. The stress distribution data of the current printed layer is calculated based on the stress distribution pattern and the strain data of the printed substrate, specifically including: Obtain the strain parameters of the printing material; the strain parameters include elastic modulus and Poisson's ratio. Based on the generalized Hooke's law and the strain parameters, a strain-stress transfer matrix is ​​constructed. Based on the strain-stress transfer matrix and the strain data of the printed substrate, a set of strain-stress transfer equations is constructed. Construct constraints based on the stress distribution pattern of the current printed layer; The strain-stress transfer equations are solved using Tikhonov regularization to obtain the stress distribution data of the current printed layer that satisfies the constraints. Based on the stress distribution data, the stress conduction zone and stress sustaining zone in the current printed layer are identified, specifically including: Based on the stress distribution data, calculate the stress gradient value and stress gradient direction at each position in the current printing layer; obtain the printing path direction at each position in the current printing layer; the printing path direction is the direction in which the print head moves at the corresponding position; If the stress gradient value at any position in the current printed layer is greater than the preset stress gradient threshold, and the angle between the stress gradient direction at the corresponding position and the printing path direction is less than the preset direction angle threshold, then the corresponding position is a stress transmission point. Record the location of each stress conduction point, and connect the stress conduction points into a connected stress conduction region using a region connection algorithm; Based on the stress distribution data, the elastic strain energy density at each location in the current printed layer is calculated; If the ratio of the elastic strain energy density at any position in the current printed layer to the average elastic strain energy density of the current printed layer is greater than the preset energy threshold coefficient, and the rate of change of the elastic strain energy density at the corresponding position is less than the preset energy rate of change threshold, then the corresponding position is a stress maintenance point. Record the location of each stress sustaining point, and connect the stress sustaining points into a connected stress sustaining region using a region connection algorithm; Based on the positional distribution of the stress transmission zone and the stress maintenance zone, the printing path of the printing layer to be printed is adjusted, and the corresponding printing slice image is generated.

2. The stress-optimized method for generating printed slice images as described in claim 1, characterized in that: The strain data is acquired based on strain gauges arranged on the printing substrate; the process parameters of the current printing layer include printing path geometry, printing layer process characteristics, and printing material characteristics; The method for identifying the stress distribution pattern of the current printed layer is as follows: Set different process parameters and conduct printing experiments; record the stress distribution data corresponding to each set of process parameters; Establish a reference database, wherein any reference data in the reference database includes a set of process parameters and corresponding stress distribution data; Based on the stress distribution data of each set of process parameters, determine the stress distribution pattern of each reference data point; Calculate the similarity between the process parameters of the current printing layer and the process parameters of each reference data; The stress distribution pattern of the reference data with the highest similarity is taken as the stress distribution pattern of the current printing layer.

3. The stress-optimized method for generating printed slice images as described in claim 2, characterized in that: The adjustment of the printing path of the printing layer to be printed includes a path strategy for generating stress transmission zones; The path strategy for stress transfer zones specifically includes: The path intersection angle of the stress transmission zone is adjusted from a first angle to a second angle; wherein, the first angle is a preset basic path intersection angle; and the second angle is a preset dispersion angle. Calculate the average stress value at each stress transmission point in the stress transmission zone based on the stress distribution data of the current printed layer; The number of delay layers is calculated based on the average stress value, wherein the number of delay layers is positively correlated with the average stress value; Based on the number of delay layers, delayed printing is performed on the stress transmission zone.

4. The stress-optimized method for generating printed slice images as described in claim 3, characterized in that: The adjustment of the printing path of the printing layer to be printed also includes a path strategy for generating a stress-maintaining zone; The path strategy for the stress sustaining zone specifically includes: Calculate the mean elastic strain energy density at each stress maintenance point in the stress maintenance zone; calculate the dispersion of the stress gradient direction at each stress maintenance point in the stress maintenance zone based on the stress distribution data of the current printed layer; The fractal level is determined based on the mean of the elastic strain energy density and the dispersion of the stress gradient direction; Based on the fractal level, fractal path filling is performed on the stress maintenance region.

5. The stress-optimized method for generating printed slice images as described in claim 4, characterized in that: The adjustment of the printing path of the printing layer to be printed also includes path planning for the overlapping area; the overlapping area is the area where the stress transmission area and the stress maintenance area overlap. Path planning for the overlapping area specifically includes: marking the location of the overlapping area between the stress transmission area and the stress maintenance area based on the location distribution of the stress transmission area and the stress maintenance area, and calculating the area of ​​the overlapping area; Set an area threshold for the overlapping region; if the area of ​​the overlapping region is less than or equal to the area threshold, then simulate the path strategy of the stress conduction region for the overlapping region and obtain the first energy release amount; simulate the path strategy of the stress maintenance region for the overlapping region and obtain the second energy release amount; if the first energy release amount is greater than the second energy release amount, then execute the path strategy of the stress conduction region for the overlapping region, otherwise execute the path strategy of the stress maintenance region for the overlapping region; if the area of ​​the overlapping region is greater than the area threshold, then generate at least N sets of hybrid path strategies; any set of hybrid path strategies includes the path strategy of the stress conduction region and the path strategy of the stress maintenance region; N is a positive integer; simulate and execute each set of hybrid path strategies for the overlapping region respectively, and obtain the third energy release amount corresponding to each set of hybrid path strategies, and select the hybrid path strategy with the highest third energy release amount as the path strategy of the overlapping region.

6. The stress-optimized method for generating printed slice images as described in claim 5, characterized in that: The process of obtaining the first energy release amount specifically includes: establishing a finite element simulation model for three-dimensional model printing, and marking the stress distribution data and elastic strain energy density distribution data of the current printed layer; simulating the execution of the path strategy for the stress conduction zone through the finite element simulation model, and obtaining the distribution data of the elastic strain energy density of the current printed layer after executing the path strategy for the stress conduction zone; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the path strategy for the stress conduction zone over the volume of the printed layer to obtain the first energy release amount; The acquisition of the second energy release amount specifically includes: simulating the execution of the path strategy of the stress maintenance zone through a finite element simulation model, and acquiring the distribution data of the elastic strain energy density of the current printed layer after executing the path strategy of the stress maintenance zone; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the path strategy of the stress maintenance zone over the volume of the printed layer to obtain the second energy release amount. The process of obtaining the third energy release amount corresponding to each group of hybrid path strategies specifically includes: simulating any group of hybrid path strategies using a finite element simulation model, obtaining the distribution data of the elastic strain energy density of the current printed layer after executing the hybrid path strategy; integrating the difference between the current elastic strain energy density and the elastic strain energy density after executing the hybrid path strategy over the volume of the printed layer to obtain the third energy release amount corresponding to the hybrid path strategy.

7. The stress-optimized method for generating printed slice images as described in claim 6, characterized in that: The 3D model is sliced ​​to generate the printing path for each printing layer, specifically including: The 3D model is sliced ​​using a slicing engine to generate path data files for each printing layer. The path data files include contour information, fill information, and printing path for each printing layer. The contour information describes the boundary contour of the corresponding printing layer. The fill information describes the fill area inside the boundary contour of the corresponding printing layer. The printing path includes a coordinate sequence describing the movement trajectory of the print head within the boundary contour and the fill area. The process of generating the corresponding print slice image specifically includes: visualizing the path data file to generate the print slice image of the corresponding print layer; and visually annotating the stress transmission area and stress maintenance area of ​​the current print layer in the print slice image.

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