Composite material fiber laying path planning method based on stress information and electronic device

Abstract

The present application relates to the technical field of automatic fiber placement of composite materials, and particularly relates to a composite material fiber placement path planning method based on stress information and an electronic device, which comprises the following steps: performing finite element analysis on a component to obtain node stress components, coordinates and connection relationships, calculating a main laying angle of each ply according to the stress components, coordinates and connection relationships, and reconstructing a target surface; generating a cluster of equidistant parallel straight lines in a two-dimensional projection plane corresponding to the main laying angle of each ply, mapping the cluster of equidistant parallel straight lines to the target surface, and obtaining an effective three-dimensional path through boundary interception; detecting a local curvature of the effective path and comparing the local curvature with a preset process threshold value to determine a final fiber placement path. The present application determines a laying angle based on stress distribution, so that the fiber direction is adapted to the main bearing direction, and the stress rationality and material utilization rate are improved; the path is generated through two-dimensional projection mapping, so that the accumulated deviation of surface deviation is avoided; the boundary interception simplifies the processing procedure; the curvature detection ensures that the path meets the laying process requirements, and the scientificity and practicality of the planning are improved as a whole.

Description

Technical Field

[0001] This invention relates to the field of automated fiber placement technology for composite materials, and particularly to a method and electronic device for composite fiber placement path planning based on stress information. Background Technology

[0002] Carbon fiber reinforced composites, with their high specific strength, high specific stiffness, and excellent designability, have become core structural materials in high-end fields such as aerospace, rail transportation, energy equipment, and high-end manufacturing. Consequently, the demand for high-quality and high-efficiency molding of complex curved surface composite components is constantly increasing. Automated fiber placement and automated tape placement processes, as the mainstream molding methods for complex curved surface composite components, directly determine the molding quality, material utilization rate, and overall mechanical properties of the components through the planning and design of the fiber placement path. These are core and critical aspects of composite material molding processes.

[0003] Existing composite material fiber placement path planning methods mostly rely on the component's geometric characteristics as the core design basis. Mainstream approaches include fixed ply angle planning, geometric boundary offset generation, and geodesic trajectory construction. However, these methods fail to incorporate the stress distribution information of the component under actual service conditions into the fiber placement direction design process, resulting in significant mechanical compatibility defects. When composite components are subjected to loads, the principal stress directions differ significantly in different regions. Fiber placement paths designed solely based on geometric characteristics cannot accurately match the fiber placement direction with the component's principal load-bearing direction, easily leading to insufficient local material utilization, exacerbated stress concentration, and severely limiting the full realization of the comprehensive mechanical properties of composite structures.

[0004] In terms of path generation, traditional methods generally adopt the strategy of first generating a single initial path and then offsetting it one by one along the surface to form a full-coverage path. When applied to complex surfaces, this method is prone to introducing path accumulation deviations, and the boundary processing process is cumbersome and complicated. Problems such as path gaps, overlaps or invalid extensions are likely to occur in local areas, making it impossible to achieve stable control of the laying quality of complex surfaces and greatly increasing the cost of subsequent process adjustments and corrections.

[0005] Meanwhile, the feasibility of automated fiber placement and automated tape placement processes places strict requirements on path curvature. When the local curvature of the path is too large or the curvature changes drastically, the prepreg tape is prone to process defects such as wrinkles, bridging, local buckling, or even delamination during the placement process, directly affecting the forming accuracy and structural integrity of the component. Existing path planning methods rely solely on geometric projection to generate trajectories, without establishing a constraint relationship between path curvature and placement process. This makes it difficult to balance the actual load-bearing requirements of composite material structures with the feasibility of automated placement, resulting in poor process adaptability and low finished product qualification rates in actual production.

[0006] In summary, current composite material fiber placement path planning methods have significant shortcomings in terms of mechanical property adaptation, path generation accuracy, boundary treatment efficiency, and consideration of process constraints. There is an urgent need to develop a composite material fiber placement path planning method that can comprehensively integrate structural stress field information, realize the overall path generation of complex curved surfaces, and optimize the path in combination with process constraints, so as to solve the pain points of existing technologies and improve the molding quality and mechanical properties of complex composite material components. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems existing in the prior art, such as the lack of stress distribution in the design of the fiber placement path, the easy accumulation of deviations in the generation of complex curved surface paths, the cumbersome boundary treatment and insufficient consideration of process constraints, and to provide a composite material fiber placement path planning method and electronic device based on stress information.

[0008] In a first aspect, the present invention provides a composite material fiber placement path planning method based on stress information, comprising:

[0009] Finite element analysis is performed on the composite material component to obtain the in-plane stress components, nodal coordinates, and element connection relationships of each node in the composite material component; the dominant layup angle of each ply of the composite material component is calculated based on the in-plane stress components of each node, and the target surface of the composite material component is reconstructed based on the nodal coordinates and element connection relationships; Based on the dominant layup angle of each ply, an equidistant cluster of parallel straight lines corresponding to each ply is generated in the two-dimensional projection plane of the target surface. The equidistant cluster of parallel straight lines is mapped onto the target surface of the composite material component to obtain the initial three-dimensional fiber placement path of each ply. The initial three-dimensional fiber placement path is truncated by combining the boundary of the target surface to obtain the effective three-dimensional fiber placement path of each ply. Calculate the local curvature of the effective three-dimensional fiber placement path of each layer, compare the local curvature with a preset process threshold, and determine the final fiber placement path of each layer based on the comparison result.

[0010] Preferably, the calculation of the dominant layup angle of each ply of the composite material specifically includes: A two-dimensional stress tensor is constructed based on the in-plane stress components of each node. The two-dimensional stress tensor is then decomposed into eigenvalues ​​to obtain the maximum principal stress value and the direction vector of the maximum principal stress of each node. Calculate the orientation angle of each node based on the maximum principal stress direction vector of each node, and map the orientation angle of each node to the interval [0,π). Based on the absolute value of the maximum principal stress at each node and the orientation angle at each node, calculate the weighted cosine component and weighted sine component of each ply. Based on the weighted cosine and weighted sine components, the dominant layup angle of each ply is calculated.

[0011] Preferably, based on the node coordinates and the unit connection relationship, a surface interpolation method based on scattered node data is used to reconstruct the target surface of the composite material component.

[0012] Furthermore, the method for obtaining the initial three-dimensional fiber placement path for each layup specifically includes: Based on the target surface of the composite material component, a spatial interpolation function is established; The equidistant parallel line clusters corresponding to each ply are discretized into several planar discrete points. The coordinates of each planar discrete point are substituted into the spatial interpolation function to calculate the three-dimensional coordinates of each planar discrete point on the target surface. Remove planar discrete points from which effective three-dimensional coordinates cannot be obtained, retain the three-dimensional coordinate points corresponding to the planar discrete points from which effective three-dimensional coordinates can be obtained, and connect the three-dimensional coordinate points corresponding to each layup to form the initial three-dimensional fiber layup path of each layup.

[0013] Furthermore, the method for obtaining the effective three-dimensional fiber placement path of each layup specifically includes: The occurrence frequency of each element edge in the target surface of the composite material component is counted, and the element edges that occur at a first preset frequency are determined as the boundary edges of the target surface. A boundary closed loop is constructed based on the boundary edge, and the three-dimensional coordinate projection of the boundary closed loop is converted into a two-dimensional polygon in the two-dimensional projection plane of the target surface; Project each discrete point of the initial three-dimensional filament laying path onto the two-dimensional projection plane to obtain the corresponding planar projection points; Draw a ray from each planar projection point into any direction within the two-dimensional projection plane, and count the number of intersections between the ray and the boundary of the two-dimensional polygon; if the number of intersections is odd, the corresponding planar projection point is determined to be inside the polygon; if the number of intersections is even, the corresponding planar projection point is determined to be outside the polygon. Remove the discrete points of the initial three-dimensional filament layup path corresponding to the planar projection points located outside the polygon, retain the discrete points of the initial three-dimensional filament layup path corresponding to the planar projection points located inside the polygon, and connect the retained discrete points in the original order to form the effective three-dimensional filament layup path of each layer.

[0014] Preferably, the method for calculating the local curvature of the effective three-dimensional fiber placement path of each layup includes: Each effective three-dimensional filament laying path is discretized into several discrete points to form a discrete point sequence; each discrete point in the discrete point sequence, except for the two endpoints, and its two adjacent discrete points are selected to construct a triangle. Calculate the lengths of the three sides of the triangle based on the coordinates of three discrete points, and calculate the area of ​​the triangle based on the two side vectors of the triangle. Calculate the local curvature at the corresponding discrete point based on the lengths of the three sides and the area of ​​the triangle.

[0015] Furthermore, it also includes: setting the curvature of the two endpoints of the discrete point sequence to a second preset value; when the difference between the length of any side of the triangle and the second preset value is within a preset range, setting the curvature of the corresponding discrete point to the second preset value.

[0016] Furthermore, it also includes using a moving average method to smooth the local curvature of each effective three-dimensional filament laying path.

[0017] Preferably, the method further includes performing progressive damage analysis on the final fiber placement path using the Hashin failure criterion to verify the mechanical performance improvement effect of the final fiber placement path.

[0018] In a second aspect, the present invention provides an electronic device including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the composite material fiber placement path planning method based on stress information as described in the first aspect.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a composite material fiber layup path planning method based on stress information. It determines the dominant layup angle of the ply based on the stress distribution of the composite material component, ensuring that the fiber layup direction matches the main load-bearing direction of the component, thus improving the structural stress rationality and material utilization efficiency. An initial path is generated by creating an equidistant cluster of parallel straight lines on a two-dimensional projection plane and mapping it to the target surface, avoiding the cumulative deviation caused by the offset path of complex curved surface strips, and improving the path generation accuracy. The initial path is truncated by combining the boundary of the target surface, accurately retaining path segments within the effective layup area, simplifying the path boundary processing process. Simultaneously, the final path is screened through local curvature detection and process threshold comparison, ensuring that the planned fiber layup path meets the requirements of the automatic layup process, effectively avoiding process defects during layup, and comprehensively improving the scientificity and practicality of composite material fiber layup path planning. 2. This invention provides an electronic device that executes a program stored in a memory via a processor to implement the aforementioned composite material fiber placement path planning method based on stress information. Leveraging the computing power of the electronic device, it efficiently completes a series of path planning processes for composite material components, including stress analysis, dominant layup angle calculation, path generation, boundary interception, and curvature detection, significantly improving the efficiency and accuracy of fiber placement path planning. Simultaneously, it achieves the programmed and automated execution of this fiber placement path planning method, effectively reducing errors and workload associated with manual planning. It can stably and reliably output the final fiber placement path that meets the structural load-bearing requirements and layup process requirements, providing efficient equipment support for the industrial application of automated fiber placement molding of composite materials. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall process of the composite material fiber placement path planning method based on stress information in the embodiment. Figure 2 This is a detailed implementation flowchart of the composite material fiber placement path planning method based on stress information in the embodiments; Figure 3 This is a schematic diagram of the finite element model of the composite laminate in the embodiment; Figure 4 The stress cloud diagram and damage cloud diagram of the composite laminate in the embodiment are shown. Figure 5 This is a diagram showing the principal stress direction of the nodes in the embodiment; Figure 6 This is an angle diagram showing the direction of the maximum principal stress at the ply node in the embodiment. Figure 7 This is a schematic diagram of the projection of the planar straight line cluster onto the target curved surface in the embodiment; Figure 8 This is a curvature detection diagram from an embodiment; Figure 9 This is a visualization of the path in the example; Figure 10 This is a comparison chart of mechanical properties before and after stress information-based planning in the embodiment. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0022] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer," etc., used in the description of specific embodiments of the present invention to indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0023] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0024] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0025] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0026] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0027] The technical solution described in this invention can be applied to automated fiber placement processes for composite materials, particularly for complex curved carbon fiber reinforced composite components used in aerospace, rail transportation, energy equipment, and high-end manufacturing. In actual manufacturing, to balance the structural load-bearing capacity of the component with the feasibility of automated placement, it is necessary to combine finite element stress analysis results with path geometry generation methods to plan a fiber placement path that conforms to both the principal stress direction distribution and curvature process constraints.

[0028] The specific embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] Figure 1 and Figure 2 The diagrams show the overall process and detailed implementation flowchart of a composite material fiber placement path planning method based on stress information. S1: Perform finite element analysis on the composite material component to obtain the in-plane stress components, node coordinates, and element connection relationships of each node in the composite material component; calculate the dominant layup angle of each ply of the composite material component based on the in-plane stress components of each node, and reconstruct the target surface of the composite material component based on the node coordinates and element connection relationships.

[0030] For example, this invention uses a specific composite laminate component as an example for illustration. The laminate consists of 16 layers, each 0.125 mm thick, with a layup sequence of 45° / -45° / 90° / 0° / 0° / 90° / -45° / 45° / 45° / -45° / 90° / 0° / 0° / 90° / -45° / 45°. First, a finite element model (e.g., [model name missing]) is established based on the laminate's geometry, neutral plane model, layup sequence, single-layer thickness, and load boundary conditions. Figure 3 As shown in the figure, a quasi-static tensile load is applied to the laminate. In one possible implementation, a finite element model can be established using Abaqus finite element software, with the reduced integral shell element S4R selected as the element type. After the calculation is completed, the stress and damage distribution results of the laminate under the load are obtained, as shown in the figure. Figure 4As shown, this can be used to characterize stress concentration areas and potential failure areas. Subsequently, the nodal coordinates, quadrilateral element topology, and stress component data for each node are exported, and the nodal stress results are written to a CSV file for subsequent path planning. Since shell elements are used for modeling, the nodal stress component data mainly includes in-plane normal stress components S11 and S22 and in-plane shear stress component S12; the shell element adopts a plane stress assumption, and the thickness direction normal stress component S33 can be ignored. To calculate the nodal principal stresses and their directions, the classical plane stress constitutive relation of a single-layer orthotropic laminate in the material principal direction coordinate system is first given. Since this embodiment uses the shell element S4R and satisfies the plane stress assumption, the plane stress form in classical laminate theory is used for description. Based on this plane stress state, combined with the plane stress constitutive relation and stress transformation relation of the orthotropic laminate, the magnitude and direction of the principal stresses at each node are obtained as the basis for subsequent path planning.

[0031] The plane stress constitutive relation of the laminate in the principal directions of the material is:

[0032] in:

[0033] and

[0034] When there is an angle between the ply direction and the global coordinate system XY season , Then, the equivalent stiffness relationship in the global coordinate system after coordinate transformation is:

[0035] Where the shear strain is the engineering shear strain, ) The stiffness transformation coefficient in classical laminate theory is:

[0036] in, and These are the normal stresses at points 1 and 2 along the principal directions of the material, respectively. The in-plane shear stress is defined in the principal direction coordinate system of the material. and These represent the normal strain along the principal direction of the material; For engineering shear strain; , , , These are the coefficients of the reduced stiffness matrix for a single-layer plate; This refers to the elastic modulus along the principal direction of the fiber. The elastic modulus is the modulus perpendicular to the fiber direction. Poisson's ratio is the primary factor. It is the reciprocal Poisson ratio; It is the in-plane shear modulus; Single-layer ply direction and global coordinate system The angle between the axes; and These are the normal stresses in the x and y directions of the material, respectively; The in-plane shear stress in the xy coordinate system of the material's principal direction; and These represent the normal strains in the x and y directions of the material, respectively; The engineering shear strain is defined in the xy coordinate system along the principal direction of the material. , , , , , The equivalent stiffness coefficients in the global coordinate system after coordinate transformation; m and n are the direction cosines, respectively. and ; The angle between the material's principal direction axis 1 and the global X-axis.

[0037] After obtaining the above data, it is necessary to calculate the dominant layup angle of each ply. Specifically, firstly, a two-dimensional stress tensor is constructed based on the in-plane stress components of each node, and then eigenvalue decomposition is performed on the two-dimensional stress tensor to obtain the maximum principal stress value and the direction vector of the maximum principal stress of each node.

[0038] For example, for the i-th node, based on its in-plane stress components , and Constructing a two-dimensional stress tensor, since the S4R shell element satisfies the plane stress assumption, the stress components in the thickness direction... Since it does not participate in the solution of principal stress directions, the two-dimensional stress tensor is written as:

[0039] in, The number of nodes can be 1~ N Indicates the common surface on the mesh N Each node. For the first The two-dimensional stress tensor of each node, and The first The two in-plane normal stress components of each node in the global coordinate system. For the first The in-plane shear stress components of each node in the global coordinate system.

[0040] No. The two principal stresses at each node can be expressed as:

[0041] in The two principal stresses of the i-th node and The abbreviation of the two values ​​is used, and the larger value is taken as the maximum principal stress of the node. ,Right now:

[0042] The principal direction angle corresponding to the maximum principal stress is expressed using the standard direction formula under plane stress:

[0043] in, The direction of the maximum principal stress at this node relative to the global direction. The direction angle of the axis.

[0044] This step is used to process the stress results of the composite laminate after quasi-static tension to obtain the principal load-bearing direction information for each node (e.g., Figure 5 As shown in the figure, it provides directional input for subsequent ply dominance angle statistics and planar projection path generation.

[0045] Since the wire-laying direction is axial data, the direction... and In terms of the laying process, they are considered equivalent, so the orientation angles are uniformly mapped to the semi-circular interval. : Then, the aforementioned direction angles are uniformly mapped to the semicircular interval [0, π):

[0046] in, The direction of the maximum principal stress at this node relative to the global direction. The direction angle of the axis, This represents the mapped node orientation angle. This eliminates the influence of the orientation sign on the statistical results.

[0047] Then, based on the absolute value of the maximum principal stress at each node and the orientation angle at each node, the weighted cosine component and weighted sine component of each ply are calculated.

[0048] To enhance the contribution of high-load regions to the statistical results of the ply direction, the absolute value of the maximum principal stress at the nodes is used as the weight. That is, high-stress nodes contribute more to the dominant direction:

[0049] in, For the first The weight of each node, For the first The maximum principal stress at each node.

[0050] For a certain ply For each node, the dominant direction parameter is calculated using a bi-angle weighted statistical method:

[0051]

[0052] in, and These are the weighted cosine and weighted sine components in the biangular space, respectively; This represents the total number of nodes participating in the statistics for the current ply. For the first The weight of each node; This represents the orientation angle of the mapped node.

[0053] Therefore, the dominant layup angle of this layer can be determined:

[0054] Indicates the current dominant placement angle, such as Figure 6 As shown, Figure 6 The horizontal axis represents angles, and the vertical axis represents the number of nodes, indicating the angle corresponding to the direction of the maximum principal stress at the most nodes. At that time, map it to The interval. Wherein, The dominant layup angle for the current layer. and These are the weighted cosine and weighted sine components in the biangular space, respectively. Using the aforementioned biangular statistical method can avoid... and In vector statistics, mutual cancellation occurs, resulting in a dominant layup angle that conforms to the axial direction characteristics of the fiber layup. The above steps are repeated for each layup to obtain the independent dominant layup angle for each layup, and the carbon fiber layup orientation of the corresponding layer is determined according to the dominant layup angle.

[0055] Furthermore, the target surface of the composite material component is reconstructed based on the node coordinates and element connection relationships. In one possible implementation, a surface interpolation method based on scattered node data is used to reconstruct the target surface of the composite material component.

[0056] Through the above process, the present invention directly incorporates finite element stress field information into the fiber layup direction design, so that the carbon fiber layup direction matches the main load-bearing direction of the component, thereby improving the structural stress rationality and material utilization efficiency.

[0057] S2: Based on the dominant layup angle of each ply, generate an equidistant parallel line cluster corresponding to each ply in the two-dimensional projection plane of the target surface. Map the equidistant parallel line cluster to the target surface of the composite material component to obtain the initial three-dimensional fiber placement path of each ply. Combine the boundary of the target surface to truncate the initial three-dimensional fiber placement path to obtain the effective three-dimensional fiber placement path of each ply.

[0058] For example, for a given ply with a calculated dominant layup angle Generate a cluster of equidistant parallel lines corresponding to the dominant layup angle in the global XY plane. First, with This serves as the reference line for generating the orientation angle. Let the unit orientation vector of the dominant laying direction be:

[0059] Where d is the unit direction vector of the reference line along the dominant laying direction; The dominant layup angle for the current layer.

[0060] Suppose that the reference line passes through a point on the plane. Then the parametric equation of the reference line can be written as:

[0061] in, The parameters on the reference straight line are point; It serves as a reference point on the baseline line; For linear parameters; and , respectively, represent the upper and lower limits of the discrete interval, and d is the unit direction vector of the reference line along the dominant laying direction.

[0062] Discretize the baseline line into n discrete points, then the distance from the walk... for:

[0063] The i-th discrete parameter for:

[0064] The corresponding discrete point coordinates are:

[0065] in, n The total number of discrete points; For a long walk; and These are the upper and lower limits of the discrete interval, respectively; For the first A discrete parameter; Let i be the i-th discrete point on the reference line. d is the reference point on the baseline; d is the unit direction vector of the baseline along the dominant laying direction.

[0066] To create a tiling path, a family of parallel lines that are translated at equal intervals is directly generated in the XY plane. The normal unit vector perpendicular to the reference line is defined as:

[0067] in Let be the normal unit vector perpendicular to the reference line. The dominant layup angle for the current layer.

[0068] Let the offset distance between adjacent parallel lines be h, then the offset of the k-th translation line relative to the reference line is: Its parametric equation can be written as:

[0069] in, Let be a point on the k-th translation line; is the reference point on the baseline; k is the translation line number; h is the offset distance between adjacent parallel lines; t is the normal unit vector perpendicular to the reference line; d is the discrete parameter; and d is the unit direction vector of the reference line along the dominant laying direction.

[0070] Instead of using the traditional surface offset strategy, a cluster of equidistant parallel lines distributed along the dominant tiling angle is generated at once in the two-dimensional projection plane of the target surface, which reduces the amount of computation and the cumulative offset error.

[0071] After generating a cluster of equidistant parallel lines, map it onto the target surface (e.g., Figure 7 As shown in the figure, the initial three-dimensional fiber placement path is obtained. The method for obtaining the initial three-dimensional fiber placement path for each layer specifically includes: (1) Based on the target surface of the composite material component, establish a spatial interpolation function; (2) Discretize the equidistant parallel line clusters corresponding to each ply into several planar discrete points, substitute the coordinates of each planar discrete point into the spatial interpolation function, and calculate the three-dimensional coordinates of each planar discrete point on the target surface. (3) Remove the planar discrete points that cannot obtain effective three-dimensional coordinates, retain the three-dimensional coordinate points corresponding to the planar discrete points that can obtain effective three-dimensional coordinates, and connect the three-dimensional coordinate points corresponding to each ply to form the initial three-dimensional fiber laying path of each ply.

[0072] For example, based on the target surface mesh node coordinates ( , , Establishing a spatial interpolation function, i.e.

[0073] in, is the spatial interpolation function constructed from the discrete mesh nodes of the target surface; (x,y) are the planar coordinates of any point in the two-dimensional projection plane of the target surface; z is the corresponding elevation value of that point on the target surface; ) represents the three-dimensional coordinates of the j-th grid node.

[0074] Let the i-th discrete point in the plane obtained after discretizing the k-th translation line be...

[0075] Then the three-dimensional point projected onto the target surface by the discrete point can be represented as:

[0076] Among them, Let i be the i-th discrete point in the two-dimensional plane on the k-th translation line; and Let x and y be the x and y coordinates of the discrete point in the XY plane, respectively. This is the corresponding three-dimensional projection point of the discrete point on the target surface; is the spatial interpolation function constructed from the discrete mesh nodes of the target surface; k is the translation line number; i is the discrete point number on the translation line.

[0077] Only the projection points corresponding to the effective point set are retained, and then the projection points corresponding to each ply are connected in discrete order to form the initial three-dimensional fiber placement path of each ply.

[0078] In one possible implementation, node coordinates, element connection relationships, and CSV stress data can be read in MATLAB, an interpolation function can be constructed, and multiple parallel lines generated in the two-dimensional projection plane of the target surface can be projected as a whole to obtain multiple initial three-dimensional wire-laying paths planned based on stress information.

[0079] This overall projection method avoids the cumulative errors caused by the traditional method of generating paths line by line, and improves the accuracy and efficiency of generating wire-laying paths for complex curved surfaces.

[0080] After obtaining the initial 3D wire placement path, it is necessary to truncate it based on the boundary of the target surface to obtain the path segment (i.e., the effective 3D wire placement path) located within the effective placement area. The specific method is as follows: (1) Count the number of occurrences of each element edge in the target surface of the composite material component, and determine the element edge with the number of occurrences of the first preset value as the boundary edge of the target surface; (2) Construct a boundary closed loop based on the boundary edge, and convert the three-dimensional coordinate projection of the boundary closed loop into a two-dimensional polygon in the two-dimensional projection plane of the target surface; (3) Project each discrete point of the initial three-dimensional filament laying path onto the two-dimensional projection plane to obtain the corresponding planar projection points; (4) Draw a ray from each plane projection point into any direction in the two-dimensional projection plane, and count the number of intersections between the ray and the boundary of the two-dimensional polygon; if the number of intersections is odd, it is determined that the corresponding plane projection point is inside the polygon; if the number of intersections is even, it is determined that the corresponding plane projection point is outside the polygon. (5) Remove the discrete points of the initial three-dimensional filament laying path corresponding to the planar projection points located outside the polygon, retain the discrete points of the initial three-dimensional filament laying path corresponding to the planar projection points located inside the polygon, and connect the retained discrete points in the original order to form the effective three-dimensional filament laying path of each layer.

[0081] For example, the node number of the e-th cell in the quadrilateral grid is denoted as... The corresponding four edges are represented as follows:

[0082] in, , , , These are the four sides of the e-th quadrilateral unit. , , , These are the four node numbers for the unit. After counting all unit edges, if an edge appears only once, it means that the edge belongs to only one unit and should be identified as the boundary edge of the target surface; if an edge appears twice, it means that the edge is a shared edge between adjacent units and should be identified as an internal common edge. By first standardizing and sorting the edges and then counting the number of repetitions, consistent identification of boundary edges and common edges can be achieved.

[0083] After identifying the boundary edges, a boundary closed loop is constructed based on the adjacency relationship between the nodes at both ends of the boundary edge. Let the node sequence of the m-th boundary closed loop be ;

[0084] in, This is the m-th boundary closed loop; Let j be the j-th boundary node in the closed loop. This represents the total number of nodes in the closed loop. Projecting the three-dimensional coordinates of each node in the boundary closed loop onto the two-dimensional projection plane XY of the target surface yields the corresponding two-dimensional boundary polygon.

[0085] For any discrete point on the initial three-dimensional filament laying path Its corresponding point in the two-dimensional projection plane is denoted as To determine whether a point is within the valid tiling area, the ray casting method is used to determine if the point lies within the polygon: from the point... Draw a ray in any fixed direction and count the number of intersections with the boundary polygon. If the number of intersections is odd, the point is determined to be inside the polygon; if the number of intersections is even, the point is determined to be outside the polygon.

[0086] Therefore, for any initial 3D filament-laying path, simply retaining the discrete points located inside the boundary polygon and connecting them sequentially in the original order yields continuous path segments within the effective laying area, thus forming an effective 3D filament-laying path. When a path segment crosses a boundary, to improve boundary trimming accuracy, the intersection points between the path segment and the boundary edge can be further calculated. Let the path segment be...

[0087] Boundary edge is

[0088] in,

[0089] Define the cross product of two-dimensional vectors as ,in , ; when The time intersection parameters are respectively

[0090] when and When the path segment intersects the boundary edge, the intersection point can be represented as...

[0091] The corresponding intersection elevation is calculated using linear interpolation of the elevations of the two endpoints of the path segment, i.e.

[0092] Thus, the coordinates of the three-dimensional intersection point are obtained.

[0093] in A two-dimensional parameter point vector on the path segment. A two-dimensional parameter point vector on the boundary edge. and These are the starting and ending points of the path segment, respectively; when This indicates that two line segments are parallel or collinear, and can be handled according to the strategy of "no intersection" or "collinear overlap is handled separately"; and are the two endpoints of the boundary edge; r and s are the direction vectors of the path segment and the boundary edge, respectively; t and u For parameter variables; and It is any two-dimensional vector; For two-dimensional intersection point variables; The elevation of the intersection point of the path segments; and For vector a x and y Quantity; and For vector b x and y Quantity; and These are the elevation values ​​corresponding to the two endpoints of the path segment; The coordinates of the three-dimensional intersection point; , , For the three-dimensional intersection point x and y and z The directional components; through the above boundary identification, closed loop construction, internal and external determination, and intersection point interpolation and trimming when necessary, only continuous path segments located within the effective layup area can be retained, thereby obtaining the effective three-dimensional fiber layup path of each layer.

[0094] By employing the aforementioned boundary identification, closed loop construction, and intersection point interpolation pruning methods, only continuous path segments located within the effective paving area are retained. In the program implementation, precise pruning of the projected path can be achieved through boundary edge extraction, closed loop construction, inpolygon determination, and line segment intersection point interpolation, thereby avoiding the boundary extension processing commonly seen in traditional path planning.

[0095] S3: Calculate the local curvature of the effective three-dimensional fiber placement path of each layer, compare the local curvature with the preset process threshold, and determine the final fiber placement path of each layer based on the comparison result.

[0096] To evaluate the feasibility of the projection path and avoid defects such as wrinkles, bridging, and local buckling during fiber placement, it is necessary to perform curvature detection on the effective three-dimensional fiber placement path (e.g., Figure 8 (As shown), the specific methods include: For example, this invention uses discrete three-point Menger curvature to calculate the local curvature of an effective three-dimensional fiber placement path. Assume that a certain effective three-dimensional fiber placement path, after being discretized, yields a point sequence.

[0097] The cumulative arc length of the path can then be expressed as:

[0098] in, Let i be the i-th discrete point on the path. This represents the cumulative arc length corresponding to the first discrete point; Let n be the cumulative arc length corresponding to the i-th discrete point; n is the total number of discrete points; for internal discrete points... Take its three adjacent points , and The edge vectors that form a local triangle are defined as follows:

[0099] The corresponding three side lengths are as follows:

[0100] The area of ​​the local triangle formed by the three points is

[0101] The Menger curvature at the i-th discrete point is

[0102] The corresponding radius of curvature is

[0103] in, and These are the direction vectors of the adjacent line segments on both sides of the i-th discrete point; and and Let be the lengths of the three sides of the local triangle; Let be the area of ​​the local triangle; Let be the local curvature at the i-th discrete point; Let be the radius of curvature corresponding to that point. , or Any one of them is less than the preset length threshold At that time, to avoid numerical instability, take The value is 0. For the two endpoints of the discrete point sequence, take... ,in, A preset length threshold is used to avoid numerical amplification in curvature calculations when the distance between adjacent points is too small.

[0104] To improve the stability of the curvature curve, a moving average method is also used to smooth the local curvature of each effective three-dimensional fiber placement path, as shown in the following formula:

[0105] in, Let L be the smoothed curvature value of the i-th discrete point; L is the moving average window length. Let be the local curvature at the j-th discrete point.

[0106] After obtaining the local curvature of each path point, it is compared with a preset process threshold. Let the maximum allowable process curvature be... Then when the following conditions are met

[0107] This indicates that the path at that point meets the requirements of the automated placement process; conversely, it indicates that the curvature of the path at that point exceeds the allowable range of the process and cannot be directly used for automated placement operations. If all discrete points on a valid three-dimensional fiber placement path meet the above conditions, then the path can be used as the final fiber placement path; if some discrete points exceed the threshold, then the corresponding path segments should be corrected, deleted, or replanned.

[0108] After calculating the local curvature of the effective three-dimensional fiber placement path of each layup, the method further includes comparing the local curvature with a preset process threshold, and determining the final fiber placement path of each layup based on the comparison result (e.g., ...). Figure 9 (As shown). This process threshold is preset based on the ultimate bending performance (e.g., lower limit of the radius of curvature) of the prepreg material used. If the local curvature at a point on the path exceeds the preset threshold, the path segment is determined not to meet the requirements of the automatic placement process and needs to be corrected, deleted, or replanned. Conversely, if the curvature of all points does not exceed the threshold, the effective three-dimensional fiber placement path can be directly used as the final fiber placement path.

[0109] By using this curvature detection and process constraint determination, high-risk areas such as wrinkles, bridging, and local buckling that may occur during the actual yarn laying process can be predicted in the path planning stage, providing a basis for path correction and process parameter adjustment; in one embodiment, the center projection line and its adjacent projection lines can be selected to compare and analyze the curvature variation with arc length.

[0110] To verify the mechanical performance improvement effect of the planned path of this invention, optionally, a progressive damage analysis of the final fiber placement path is performed using the Hashin failure criterion. Specifically, the final fiber placement path generated according to the above method is re-imported into the finite element model, and progressive damage analysis is performed using the Hashin failure criterion. The Hashin failure criterion includes four failure modes: fiber tensile failure, fiber compressive failure, matrix tensile failure, and matrix compressive failure, and their criterion formulas are as follows: when At that time, the fiber tensile failure criterion is:

[0111] when At that time, the fiber compression failure criterion is:

[0112] when At that time, the matrix tensile failure criterion is

[0113] when At that time, the matrix compression failure criterion is

[0114] in, This represents the normal stress component along the principal direction 1 of the material. This represents the normal stress component along the principal direction 2 of the material; The in-plane shear stress components are defined in the principal direction coordinate system of the material. and These are the tensile strength and compressive strength in the fiber direction, respectively. and These are the transverse tensile strength and compressive strength, respectively. It is the in-plane shear strength; This is the influence coefficient of shear stress; , , and These are the failure functions corresponding to fiber tension, fiber compression, matrix tension, and matrix compression, respectively. If the value of any of these failure functions reaches or exceeds 1, it signifies the onset of damage in that mode. Since this embodiment uses a two-dimensional plane stress model, the above criteria are no longer introduced. or Shear stress and its strength parameters in the uniform thickness direction.

[0115] The improvement effect of the path planning method of this invention on the mechanical properties of laminates can be verified by performing progressive damage analysis in Abaqus. Figure 10As shown, the cross-sectional area of ​​the curved surface is 115.12 mm. 2 In one embodiment, the failure strength of the optimized layup scheme is increased from 740.51 MPa to 906.19 MPa compared to the initial layup scheme, representing an improvement of 22.43%. This indicates that the path planning method provided by the present invention has good potential for optimizing structural performance.

[0116] Based on the same inventive concept, the present invention also provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the composite material fiber laying path planning method based on stress information as described in any of the above implementations.

[0117] For example, a processor may include one or more processing units, such as a neural network processing unit (NPU), an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a digital signal processor (DSP), a baseband processor, etc. The different processing units may be independent devices or integrated into one or more processors. The controller can generate operation control signals based on the instruction opcode and timing signals to control instruction fetching and execution.

[0118] The memory can be used to store executable program code, including instructions. Internal memory may include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function, etc. The data storage area may store data created during the use of the electronic device (such as input data, output data, etc.). Furthermore, internal memory may include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory device, universal flash storage (UFs), etc. The processor executes various functional applications and data processing of the electronic device by running instructions stored in the internal memory and / or instructions stored in memory located within the processor.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite material fiber placement path planning method based on stress information, characterized in that, include: Finite element analysis is performed on the composite material component to obtain the in-plane stress components, node coordinates, and element connection relationships of each node of the composite material component. The dominant layup angle of each ply of the composite component is calculated based on the stress components in the surface of each node, and the target surface of the composite component is reconstructed based on the node coordinates and the element connection relationship. Based on the dominant layup angle of each ply, an equidistant cluster of parallel straight lines corresponding to each ply is generated in the two-dimensional projection plane of the target surface. The equidistant cluster of parallel straight lines is mapped onto the target surface of the composite material component to obtain the initial three-dimensional fiber placement path of each ply. The initial three-dimensional fiber placement path is truncated by combining the boundary of the target surface to obtain the effective three-dimensional fiber placement path of each ply. Calculate the local curvature of the effective three-dimensional fiber placement path of each layer, compare the local curvature with a preset process threshold, and determine the final fiber placement path of each layer based on the comparison result; Specifically, the calculation of the dominant layup angle of each ply of the composite material includes: A two-dimensional stress tensor is constructed based on the in-plane stress components of each node. The two-dimensional stress tensor is then decomposed into eigenvalues ​​to obtain the maximum principal stress value and the direction vector of the maximum principal stress of each node. Calculate the orientation angle of each node based on the maximum principal stress direction vector of each node, and map the orientation angle of each node to the interval [0,π). Based on the absolute value of the maximum principal stress at each node and the mapped orientation angle of each node, calculate the weighted cosine component and weighted sine component of each ply. Based on the weighted cosine and weighted sine components, the dominant layup angle of each ply is calculated. The absolute values ​​of the maximum principal stresses at each node are as follows: in, For the first The absolute value of the maximum principal stress at each node. For the first The maximum principal stress at each node; The weighted cosine component and the weighted sine component are respectively: in, and These are the weighted cosine and weighted sine components in the biangular space, respectively; This represents the total number of nodes participating in the statistics for the current ply. For the first The absolute value of the maximum principal stress at each node; For the mapped first Each node's orientation angle; Therefore, the dominant layup angle of this layer can be determined: Indicates the dominant laying angle.

2. The composite material fiber placement path planning method based on stress information according to claim 1, characterized in that, Based on the node coordinates and element connection relationship, the target surface of the composite material component is reconstructed using a surface interpolation method based on scattered node data.

3. The composite material fiber placement path planning method based on stress information according to claim 2, characterized in that, The method for obtaining the initial three-dimensional fiber placement path of each layer specifically includes: Based on the target surface of the composite material component, a spatial interpolation function is established; The equidistant parallel line clusters corresponding to each ply are discretized into several planar discrete points. The coordinates of each planar discrete point are substituted into the spatial interpolation function to calculate the three-dimensional coordinates of each planar discrete point on the target surface. Remove planar discrete points from which effective three-dimensional coordinates cannot be obtained, retain the three-dimensional coordinate points corresponding to the planar discrete points from which effective three-dimensional coordinates can be obtained, and connect the three-dimensional coordinate points corresponding to each layup to form the initial three-dimensional fiber layup path of each layup.

4. The composite material fiber placement path planning method based on stress information according to claim 3, characterized in that, The method for obtaining the effective three-dimensional fiber placement path of each layer specifically includes: The occurrence frequency of each element edge in the target surface of the composite material component is counted, and the element edges that occur at a first preset frequency are determined as the boundary edges of the target surface. A boundary closed loop is constructed based on the boundary edge, and the three-dimensional coordinate projection of the boundary closed loop is converted into a two-dimensional polygon in the two-dimensional projection plane of the target surface; Project each discrete point of the initial three-dimensional filament laying path onto the two-dimensional projection plane to obtain the corresponding planar projection points; Draw a ray from each planar projection point into any direction within the two-dimensional projection plane, and count the number of intersections between the ray and the boundary of the two-dimensional polygon; if the number of intersections is odd, the corresponding planar projection point is determined to be inside the polygon; if the number of intersections is even, the corresponding planar projection point is determined to be outside the polygon. Remove the discrete points of the initial three-dimensional filament layup path corresponding to the planar projection points located outside the polygon, retain the discrete points of the initial three-dimensional filament layup path corresponding to the planar projection points located inside the polygon, and connect the retained discrete points in the original order to form the effective three-dimensional filament layup path of each layer.

5. The composite material fiber placement path planning method based on stress information according to claim 1, characterized in that, The method for calculating the local curvature of the effective three-dimensional fiber layup path for each layer includes: Each effective three-dimensional filament laying path is discretized into several discrete points to form a discrete point sequence; each discrete point in the discrete point sequence, except for the two endpoints, and its two adjacent discrete points are selected to construct a triangle. Calculate the lengths of the three sides of the triangle based on the coordinates of three discrete points, and calculate the area of ​​the triangle based on the two side vectors of the triangle. Calculate the local curvature at the corresponding discrete point based on the lengths of the three sides and the area of ​​the triangle.

6. The composite material fiber placement path planning method based on stress information according to claim 5, characterized in that, Also includes: Set the curvature of the two endpoints of the discrete point sequence to the second preset value; When the difference between the length of any side of the triangle and the second preset value is within the preset range, the curvature of the corresponding discrete point is set to the second preset value.

7. The composite material fiber placement path planning method based on stress information according to claim 6, characterized in that, It also includes using the moving average method to smooth the local curvature of each effective three-dimensional wire laying path.

8. The composite material fiber placement path planning method based on stress information according to claim 1, characterized in that, It also includes using the Hashin failure criterion to perform progressive damage analysis on the final fiber placement path to verify the mechanical performance improvement effect of the final fiber placement path.

9. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the composite material fiber placement path planning method based on stress information as described in any one of claims 1 to 8.

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