CN-121980637-A - Dot matrix model processing method and system based on additive manufacturing constraint

CN121980637ACN 121980637 ACN121980637 ACN 121980637ACN-121980637-A

Abstract

The invention relates to the technical field of additive manufacturing, and discloses a lattice model processing method and system based on additive manufacturing constraint. The method comprises the steps of firstly reading an initial lattice model, discretizing the initial lattice model into a combination of nodes and rod elements to construct bidirectional association mapping of a topological layer and a spatial layer, abstracting constraints such as a suspension angle, a minimum size and the like into a geometric constraint model according to additive manufacturing scenes and performance requirements, quantifying the violation degree through a cost function, identifying the rod elements to be corrected, and finally sequentially executing topology integrity correction, additive manufacturing constraint correction and performance target optimization by adopting a hierarchical scheduling strategy, and combining a correction operator library to realize accurate correction. The invention takes the rod element as the minimum correction unit, breaks through the limitation of the traditional cell configuration, solves the problems of low design freedom degree, insufficient constraint correction universality and low efficiency in the prior art, ensures the process compliance, simultaneously reserves the original structural performance to the greatest extent, and realizes the high-efficiency and high-quality manufacturability treatment of the large-scale lattice structure.

Inventors

ZHANG KAIXIANG
JIA XINJIAN
LI XIN
LIU BINGSHAN
WANG GONG

Assignees

中国科学院空间应用工程与技术中心

Dates

Publication Date: 20260505
Application Date: 20260128

Claims (10)

1.A lattice model processing method based on additive manufacturing constraints, the method comprising: reading an initial lattice model, and performing discretization on the initial lattice model to obtain a discretization lattice structure consisting of nodes and rod elements; Constructing a geometric constraint model matched with the discretized lattice structure according to the additive manufacturing scene and the performance requirement; traversing the rod elements in the discretization lattice structure based on the geometric constraint model, and identifying the rod elements to be corrected and the corresponding correction types; And performing correction operation on the rod elements to be corrected by adopting a hierarchical scheduling strategy to obtain a target lattice model meeting additive manufacturing constraint and performance requirements.
2. The method according to claim 1, wherein the reading the initial lattice model, and performing discretization on the initial lattice model, to obtain a discretized lattice structure composed of nodes and rods, includes: Reading the geometric information of an initial lattice model, wherein the file format of the geometric information comprises STL, INP or a parameterized node-rod list; recording connection relations of all the rod elements in the initial lattice model in a topology layer, wherein the connection relations comprise node identifiers at two ends of each rod element; Recording the space distribution range of the initial lattice model and the three-dimensional coordinate information of all nodes in a space layer; and discretizing the initial lattice model into a combination of nodes and rod elements through bidirectional association mapping of the topological layer and the spatial layer to form a discretized lattice structure.
3. The method of claim 1, wherein constructing a geometric constraint model adapted to the discretized lattice structure for additive manufacturing scenarios and performance requirements comprises: Determining constraint types corresponding to a target additive manufacturing scene, wherein the constraint types comprise a suspension angle constraint, a minimum size constraint, a node connectivity constraint, a heat accumulation constraint and a performance adaptation constraint; Extracting geometric parameters of the discretized lattice structure, wherein the geometric parameters comprise endpoint coordinates, section radius, length, direction vector and node connectivity of rod elements; Establishing a mapping relation between constraint types and geometric parameters, and converting each constraint type into a geometric constraint expression: and fusing the geometric constraint expressions of all constraint types to obtain a geometric constraint model.
4. The method of claim 1, wherein traversing the stem elements in the discretized lattice structure based on the geometric constraint model, identifying stem elements to be corrected and corresponding correction types, comprises: constructing cost functions aiming at different constraint types, wherein the cost functions are positively correlated with the violation amplitude of the rod element: Calculating the weighted total cost of each rod element according to cost functions of different constraint types; judging the rod element with the weighted total cost larger than the cost threshold value as the rod element to be corrected, and determining the corresponding correction type; the calculation formula of the weighted total cost C total is as follows: C total =w 1 ×C dang +w 2 ×C ang +w 3 ×C len +w 4 ×C deg ; w 1 、w 2 、w 3 、w 4 is a weight coefficient, w 1 ＞w 2 ＞w 3 ＞w 4 ,C dang is a suspension rod cost function value, the suspension rod cost function value is a preset maximum value when a suspension rod exists, otherwise 0;C ang is a suspension cost function value, when the rod element angle is smaller than a critical angle threshold value theta limit , the suspension cost function value is a normalized deviation of the angle relative to theta limit , otherwise 0;C len is a length cost function value, the length cost function value is a normalized maximum deviation of the length from a manufacturable interval, and C deg is a connectivity cost function value, and the connectivity cost function value is a difference value of node degree exceeding a physical upper limit D max .
5. The method of claim 1, wherein performing a correction operation on the rod elements to be corrected using a hierarchical scheduling strategy results in a target lattice model that meets additive manufacturing constraints and performance requirements, comprising: Performing topology integrity correction on the rod elements to be corrected preferentially, eliminating geometrical singularities and connectivity defects of the lattice structure, and obtaining a middle lattice model with complete topology; performing additive manufacturing constraint correction on the intermediate lattice model with complete topology, and enabling the model to meet additive manufacturing process constraint through geometric perturbation or topology reconstruction to obtain an intermediate lattice model with process compliance, wherein the priority of the geometric perturbation is greater than that of the topology reconstruction; performing performance target optimization on the intermediate lattice model of the process compliance, and optimizing structural mechanical or thermal performance in a process constraint feasible domain to obtain a target lattice model; after each stage of scheduling execution is completed, checking whether the current model meets a preset correction standard, wherein the preset correction standard is that topology has no geometric singularity and connectivity defect, additive manufacturing process constraint is met or performance index reaches a preset threshold, and if not, returning to a corresponding scheduling link to execute again until the preset correction standard is met.
6. The method of claim 5, wherein the performing topology integrity correction preferentially on the rod elements to be corrected, eliminating geometric singularities and connectivity defects of the lattice structure, and obtaining a topology-complete intermediate lattice model, comprises: traversing the discretized lattice structure, identifying non-manifold nodes and non-manifold edges, and completing normalized repair by adjusting node connection relations; performing topology collapse operation on independent nodes with the spatial distance smaller than a distance threshold value, and merging the independent nodes into a single node so as to eliminate pseudo disconnection or overlapping nodes caused by factor value precision errors; adopting breadth-first searching or merging algorithm to identify isolated subgraphs and suspension rods which are not connected with the main stress path or boundary constraint, and performing physical deletion; and detecting the crossing condition of the non-node position of the rod element, inserting a new node in the crossing point position, breaking the cross rod element into four short rod elements connected with the crossing point, and obtaining the intermediate lattice model with complete topology.
7. The method of claim 5, wherein performing additive manufacturing constraint correction on the topologically complete intermediate lattice model to satisfy additive manufacturing process constraints by geometric perturbation or topological reconstruction to obtain a process-compliant intermediate lattice model comprises: Determining illegal rod elements according to overhang constraint detection, feature size detection and topology connectivity detection corresponding to a target additive manufacturing process; on the premise of locking the topological relation, the node coordinates are subjected to micro-movement, the suspension angle or the length of the rod elements is corrected, and when one node movement affects a plurality of rod elements, the balance positions meeting the requirements of all the connecting rod elements are automatically searched; And calling a correction operator library to execute operations, wherein the operations comprise executing a subdivision operator on rod elements with the length being larger than a preset length value or with the overhang being smaller than a critical angle threshold value theta limit , executing a collapse operator on the rod elements with the length being smaller than or equal to the preset length, executing a node splitting operator on a high connectivity node, and executing a support generating operator on stubborn suspension rod elements, wherein the high connectivity node is defined as a node with the number of rod elements connected by the node being larger than the preset connectivity threshold value, and the stubborn suspension rod elements are rod elements with the overhang angle still being smaller than the critical angle threshold value theta limit and free of the rod elements which can be supported by adjacent structures after the geometric perturbation and the subdivision operator correction, so that an intermediate lattice model with the process compliance is obtained.
8. The method of claim 5, wherein performing performance objective optimization on the intermediate lattice model of process compliance optimizes structural mechanical or thermal properties within a process constraint feasible to obtain a target lattice model, comprising: Based on a stress field or a temperature field obtained by finite element analysis, a mapping function of the radius of the cross section of the rod element and the physical response is built, and the radius of the rod element is adjusted on the premise of meeting the constraint of additive manufacturing; Executing rod element subdivision or lattice splitting in a high stress gradient region to increase local rod element density, executing edge collapse in a low stress region to reduce redundant rod elements, wherein the region with stress gradient larger than a preset gradient threshold is a high stress gradient region, and the region with stress gradient smaller than or equal to the preset gradient threshold and with stress value lower than the preset stress threshold is a low stress gradient region; And feeding the topology change generated after performance target optimization is executed back to additive manufacturing constraint correction, executing constraint compliance check on the newly generated rod element, triggering additive manufacturing constraint correction if violations exist, and obtaining a target lattice model if violations do not exist.
9. A lattice model processing system based on additive manufacturing constraints, the system comprising: The discretization processing module is used for reading the initial lattice model, and discretizing the initial lattice model to obtain a discretization lattice structure consisting of nodes and rod elements; the constraint model construction module is used for constructing a geometric constraint model matched with the discretized lattice structure according to the additive manufacturing scene and the performance requirement; the correction term identification module is used for traversing the rod elements in the discretization lattice structure based on the geometric constraint model and identifying the rod elements to be corrected and the corresponding correction types; and the rod element correction module is used for performing correction operation on the rod elements to be corrected by adopting a hierarchical scheduling strategy to obtain a target lattice model meeting additive manufacturing constraint and performance requirements.
10. An electronic device, comprising: A memory for storing instructions executable by the processor; Wherein the processor is configured to execute the instructions to implement the additive manufacturing constraint-based lattice model processing method of any one of claims 1-8.

Description

Dot matrix model processing method and system based on additive manufacturing constraint Technical Field The invention relates to the technical field of additive manufacturing, in particular to a lattice model processing method and system based on additive manufacturing constraint. Background With the rapid development of additive manufacturing technology to high precision and complexity, the dot matrix structure has been increasingly widely applied to the fields of high-end equipment such as aerospace, biomedical and the like by virtue of excellent light-weight characteristics and mechanical properties. The model processing of the structure needs to realize mechanical property optimization and manufacturing process adaptation simultaneously, so that the core performances such as structural strength, rigidity and the like are guaranteed through reasonable topological form and geometric parameter design, and process constraints such as overhang angle, minimum wall thickness and the like in the additive manufacturing process are met, however, the lattice structure comprises a large number of nodes and rods, the complex topological relation and the process specificity of the additive manufacturing process make the cooperation of performance optimization and process adaptation an outstanding challenge for the industry. In order to cope with the challenge, a lattice model optimization scheme based on a density method (SIMP) is generally adopted in the prior art, the scheme firstly completes optimization of topological morphology and geometric parameters of a lattice structure by adjusting material density distribution in a design domain, an initial model meeting the requirement of mechanical properties is obtained, then a third-party tool is used for carrying out additive manufacturing process compatibility inspection on the model, and areas which are out of compliance with the process requirements, such as an excessive overhang angle, an excessive thin wall thickness and the like are identified, so that manual correction is carried out. The method has the core defects that the constraint depth of the additive manufacturing process is not integrated into the whole model processing flow, and only the passive verification and correction are carried out after the optimization, so that a large number of process incompatible areas exist in the optimization result, the performance advantage of original optimization is easy to damage due to later manual adjustment, the design period is obviously prolonged, meanwhile, the method lacks an efficient bottom data organization and incremental updating mechanism, serious redundant calculation exists when the query and the modification of massive lattice data are faced, the model processing efficiency is further reduced, and finally the lattice model is difficult to adapt to the additive manufacturing process requirement quickly and accurately, so that the engineering floor application of the lattice model is restricted. Disclosure of Invention The embodiment of the invention provides a lattice model processing method and system based on additive manufacturing constraint, which can solve the problems that the additive manufacturing constraint correction of a lattice model in the prior art has insufficient universality and imperfect correction system, cannot cover various process constraints such as a suspension angle, a minimum size and the like, is limited by a specific cell structure, so that the degree of freedom of design is low, and the manufacturability correction of a large-scale lattice structure is difficult to realize efficiently and comprehensively. In order to achieve the above purpose, the embodiment of the present invention adopts the following technical scheme: A first aspect provides a lattice model processing method based on additive manufacturing constraint, which comprises the steps of reading an initial lattice model, carrying out discretization processing on the initial lattice model to obtain a discretization lattice structure composed of nodes and rods, constructing a geometric constraint model adaptive to the discretization lattice structure according to additive manufacturing scenes and performance requirements, traversing the rods in the discretization lattice structure based on the geometric constraint model, identifying rods to be corrected and corresponding correction types, and carrying out correction operation on the rods to be corrected by adopting a hierarchical scheduling strategy to obtain a target lattice model meeting the additive manufacturing constraint and performance requirements. The method provided by the invention adopts a hierarchical scheduling strategy of topology integrity correction, additive manufacturing constraint correction and performance target optimization, the geometric perturbation priority is definitely higher than that of topology reconstruction, and a preset correction standard verification and circulation correction