Complex curved surface body three-dimensional weaving flat torsion displacement method and system

Abstract

The invention relates to the field of three-dimensional weaving digital design, in particular to a complex curved surface body three-dimensional weaving flat torsion conversion method and system. The method comprises the following steps: acquiring a three-dimensional model, a warp direction, a weft width, a warp width and a yarn thickness of the complex curved surface body; segmenting the three-dimensional model along the warp direction by taking the weft width as an interval to obtain a plurality of initial sections and corresponding upper boundary line segments and lower boundary line segments; determining an initial reference point of the initial section based on the upper boundary line segment and the lower boundary line segment; layering the initial section by using the yarn thickness and the initial reference point based on the upper boundary line segment and the lower boundary line segment to obtain a plurality of layered structures; and constructing a flattened datum line by using the initial datum point. Based on the layered structure and the flattening datum line, yarn path points are extracted with the warp width as the step length, and a tiled-state three-dimensional weaving path point model is generated. The problems that in the prior art, three-dimensional weaving flat torsion of a complex curved surface body is low in efficiency and poor in precision are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of three-dimensional weaving digital design, and particularly relates to a complex curved surface three-dimensional weaving flat-twist conversion method and system. BACKGROUND

[0002] In the design and production process of complex curved surface three-dimensional woven composites, flat-twist conversion is a key link to realize the conversion of curved surface structure to flat state and guide the implementation of weaving process. At present, the commonly used flat-twist conversion method in the industry takes finite element simulation as the core, and its typical process is as follows: first, the material properties such as elastic modulus and Poisson's ratio of the three-dimensional woven preform are measured through experiments, and then these property parameters are imported into the simulation model, and at the same time, the constraint conditions and the preset flat direction are applied to the model, and finally the complex curved surface structure is realized on the specified plane.

[0003] However, this kind of method has many significant defects in practical application: first, the material properties of the three-dimensional woven preform are directly related to the yarn arrangement, weaving density, fabric structure and other factors, and the material parameters corresponding to different weaving structures differ significantly. This leads to the need to repeat the material property measurement work when adapting to different weaving structures even for the same type of curved surface model, which not only increases the preparation cost, but also greatly prolongs the conversion period; second, the flat-twist conversion precision of finite element simulation is highly dependent on the grid quality, and the grid division needs to be repeatedly debugged in combination with the specific curved surface structure and weaving characteristics, which is tedious and requires high technical experience. Once the grid has distortion, unevenness and other problems, it is easy to cause deviation in the flat expansion result, and even cannot meet the process requirements.

[0004] In summary, the existing finite element flat-twist conversion method has the problems of limited application scenarios, high operation complexity, difficult to balance conversion efficiency and precision, and other problems, which cannot meet the efficient and accurate design and production requirements of complex curved surface three-dimensional woven composites, and there is an urgent need for a more efficient and accurate flat-twist conversion method. SUMMARY

[0005] In view of the defects in the prior art, the present application provides a complex curved surface three-dimensional weaving flat-twist conversion method and system, which solves the problem of low conversion efficiency and poor precision of complex curved surface three-dimensional weaving flat-twist conversion in the prior art.

[0006] To achieve the above object, the application provides a complex curved surface three-dimensional weaving flat twist conversion method, which comprises the following steps: obtaining a three-dimensional model of a complex curved surface, warp yarn direction, weft yarn width, warp yarn width and yarn thickness; cutting the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections and corresponding upper boundary line segments and lower boundary line segments; determining initial reference points of the initial cross sections based on the upper boundary line segments and the lower boundary line segments; determining a plurality of layered structures by layering the initial cross sections based on the upper boundary line segments and the lower boundary line segments by using the yarn thickness and the initial reference points; and constructing a flat reference line by using the initial reference points. Based on the layered structures and the flat reference line, yarn path points are extracted at a step length of the warp yarn width to generate a flat three-dimensional weaving path point model.

[0007] The application obtains the three-dimensional model of the complex curved surface and the key parameters of the warp yarn direction, the weft yarn width, the warp yarn width and the yarn thickness, cuts the model along the warp yarn direction to obtain the initial cross sections and the boundary line segments, determines the initial reference points after layering according to the yarn thickness, constructs the flat reference line and extracts the yarn path points to generate the flat model, without relying on material attribute measurement and grid debugging, thereby avoiding the limitation of the finite element method and improving the efficiency and accuracy of the flat twist conversion of the complex curved surface.

[0008] Optionally, the step of cutting the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections and corresponding upper boundary line segments and lower boundary line segments comprises the following steps: cutting the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections; extracting intersection lines of upper and lower surface boundaries and planes of the initial cross sections in the three-dimensional model; and determining the upper boundary line segments and the lower boundary line segments according to the spatial position relationship between the intersection lines and the initial cross sections.

[0009] The application cuts the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain the uniformly arranged initial cross sections, extracts the intersection lines of the upper and lower surface boundaries of the model and the planes of the initial cross sections, and determines the upper and lower boundary line segments in combination with the spatial position relationship between the intersection lines and the initial cross sections, so as to ensure that the cross section cutting and the boundary identification strictly match the weaving yarn arrangement rule, avoid the problems of uneven cutting interval or boundary confusion, and improve the accuracy of the initial cross sections and the corresponding boundary line segments.

[0010] Optionally, the step of determining the initial reference points of the initial cross sections based on the upper boundary line segments and the lower boundary line segments comprises the following steps: judging the thickness type of the initial cross sections based on the upper boundary line segments and the lower boundary line segments; and determining the initial reference points of the initial cross sections based on the thickness type.

[0011] The application determines the thickness type of the initial section according to the upper and lower boundary line segments first, and then determines the initial reference point, thereby avoiding the problem that the unified reference point setting cannot adapt to different thickness sections, and ensuring that the reference point can accurately reflect the geometric center or key boundary feature of the different thickness sections, thereby improving the adaptability and accuracy of the initial reference point.

[0012] Optionally, the determining the initial reference point of the initial section based on the thickness type comprises: determining the center line of the upper boundary line segment and the lower boundary line segment based on the thickness type being an equal-thickness section; and calculating the center point of the center line to obtain the initial reference point of the initial section.

[0013] For the equal-thickness section, the application determines the center line of the upper and lower boundary line segments first, and then calculates the center point of the center line as the initial reference point, thereby avoiding the problem that the reference point of the equal-thickness section deviates from the geometric center, enabling the reference point to accurately represent the core position of the equal-thickness section, and further improving the positioning accuracy of the initial reference point corresponding to the equal-thickness section.

[0014] Optionally, the layering the initial section based on the upper boundary line segment and the lower boundary line segment using the yarn thickness and the initial reference point to obtain a plurality of layering structures comprises: determining a layering mode based on the upper boundary line segment and the lower boundary line segment; and layering the initial section according to the layering mode to obtain a plurality of layering structures in the normal vector direction of the yarn thickness and the initial reference point.

[0015] The application determines the adaptive layering mode according to the upper and lower boundary line segments, and then layers the initial section in the fixed interval of the yarn thickness and the uniform direction of the normal vector of the initial reference point according to the mode, thereby avoiding the problem that the layering mode does not match the boundary feature of the section or the layering direction is chaotic, enabling the layering structure to accurately fit the actual laying specifications of the yarn and the geometric shape of the section, and improving the rationality of the layering structure.

[0016] Optionally, the determining the layering mode based on the upper boundary line segment and the lower boundary line segment comprises: judging the line segment type of the upper boundary line segment and the lower boundary line segment; determining a layering line based on the line segment type, and determining the layering mode according to the layering line.

[0017] The application first judges the line segment type of the upper and lower boundary line segments, and then determines the corresponding layering line and the layering mode according to the line segment type, thereby avoiding the problem that the uniform layering mode leads to the incompatibility between the layering line and the boundary shape without considering the line segment type, enabling the layering mode to accurately match the geometric features of the boundary line segment, and improving the accuracy of the layering mode.

[0018] Optionally, the constructing the flat reference line by using the initial reference points comprises: sorting the initial reference points according to the initial cross section; correcting the sorted initial reference points to obtain optimized reference points by taking the warp width as a target interval; and connecting the optimized reference points to form the flat reference line.

[0019] The present application sorts the initial reference points according to the initial cross section, corrects the reference points to obtain optimized reference points by taking the warp width as a target interval, and finally connects the optimized reference points to form the flat reference line, thereby avoiding the deviation of the reference line caused by the disordered arrangement or the interval deviation of the reference points from the warp specification, making the flat reference line strictly adhere to the arrangement rule of the warp direction, and improving the orderliness and accuracy of the flat reference line.

[0020] Optionally, the correcting the sorted initial reference points to obtain optimized reference points by taking the warp width as a target interval comprises: selecting two adjacent initial reference points as a front initial reference point and a rear initial reference point based on the sorted initial reference points; projecting the front initial reference point to a line segment of the rear initial reference point to obtain a projection point; calculating the length of the projection point and the rear initial reference point on the line segment of the rear initial reference point; calculating the difference between the length and the warp width to obtain an adjustment amount and an adjustment direction of the rear initial reference point; and adjusting the rear initial reference point based on the adjustment amount and the adjustment direction to obtain an optimized reference point.

[0021] The present application selects adjacent reference points from the sorted initial reference points, projects the front reference point to the line segment of the rear reference point, calculates the length of the projection point and the rear reference point and the difference between the length and the warp width, and adjusts the rear reference point according to the difference to obtain an optimized reference point, thereby avoiding the problem of interval deviation between adjacent reference points from the warp width, accurately matching the optimized reference point interval to the warp specification, and improving the scientificity of the reference point correction and the positioning accuracy of the optimized reference point.

[0022] Optionally, the three-dimensional weaving method for converting a complex curved surface body into a flat twist further comprises: calculating the path point column density along the flat direction in the flat state three-dimensional weaving path point model; multiplying the path point column density by the yarn thickness to obtain thickness distribution data, and generating a thickness distribution cloud map according to the thickness distribution data.

[0023] The present application calculates the path point column density along the flat direction in the flat state model, multiplies the path point column density by the yarn thickness to obtain thickness distribution data, and generates a thickness distribution cloud map, thereby intuitively presenting the thickness difference of different regions after flatting, avoiding the limitation that it is difficult to quickly identify the uneven thickness problem only by the path point model, and improving the reliability of the thickness distribution cloud map of the thickness distribution.

[0024] Another aspect of the present application also provides a complex curved surface three-dimensional weaving flat twist conversion system, comprising: a processor, an input device, an output device and a memory, the processor, the input device, the output device and the memory are connected with each other, wherein the memory is used for storing a computer program, the computer program comprises program instructions, the processor is configured to call the program instructions, and the complex curved surface three-dimensional weaving flat twist conversion method of any one of the previous aspect of the present application is executed.

[0025] The complex curved surface three-dimensional weaving flat twist conversion system of the present application has compact structure, stable performance, high integration and simple structure, can stably execute the complex curved surface three-dimensional weaving flat twist conversion method provided in the previous aspect of the present application, and further improves the overall applicability and practical application ability of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A complex curved surface three-dimensional weaving flat twist conversion method flow chart for an embodiment of the present application; Figure 2 An equal-thickness cross-section flat expansion reference point extraction optimization diagram for an embodiment of the present application; Figure 3 A non-equal-thickness cross-section flat expansion reference point extraction optimization diagram for an embodiment of the present application.

[0027] Figure 4 A thickness distribution cloud chart for an embodiment of the present application; Figure 5 A complex curved surface three-dimensional weaving flat twist conversion system structure schematic diagram for an embodiment of the present application. DETAILED DESCRIPTION

[0028] The specific embodiments of the present application will be described in detail below, and it should be noted that the embodiments described herein are only used for illustration and do not limit the present application. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application does not have to be implemented by using these specific details. In other examples, in order to avoid obscuring the present application, well-known circuits, software or methods are not specifically described.

[0029] Reference throughout this specification to "one embodiment", "an embodiment", "one example", or "an example", means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the application. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" or "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics can be combined in any suitable

[0030] Referring to Figure 1 To solve the problems in the prior art, a three-dimensional weaving flat-twist conversion method for a complex curved surface body as shown in the figure includes the following steps: Step S1, obtaining a three-dimensional model of the complex curved surface body, warp yarn direction, weft yarn width, warp yarn width, and yarn thickness.

[0031] In this embodiment, first, a three-dimensional model of the complex curved surface body is obtained. The three-dimensional model is constructed in advance by professional three-dimensional design software. To adapt to the algorithm requirements for subsequent cross-section segmentation and boundary recognition, the model needs to be exported in STL format. This format can completely retain the spatial geometric characteristics of the curved surface body, including the upper and lower surface profiles, thickness distribution, curved surface curvature, and other key information, avoiding the loss of geometric data caused by non-standard formats. Subsequently, the warp yarn direction and weft yarn direction are determined. According to the yarn laying rules of the actual three-dimensional weaving process, such as the warp yarn extending along the length direction of the curved surface body, the weft yarn extending along the width distribution direction of the curved surface body, or the structure stress optimization target of the curved surface body, the direction coordinate axis is manually labeled in the three-dimensional model operation interface through an input device, or a preset weaving process direction template is called, such as the direction template corresponding to plain weaving or twill weaving, to automatically match. Finally, the weft yarn width, warp yarn width, and yarn thickness parameters are obtained. The weft yarn width needs to be determined according to the fabric density design requirements of the composite material to be prepared, such as the number of weft yarn arrangements per unit length, and the occupied width of a single weft yarn is calculated inversely. The warp yarn width needs to be determined according to the warp fabric density design requirements, such as the number of warp yarn arrangements per unit length, and the occupied width of a single warp yarn is calculated inversely. The yarn thickness needs to be measured by a yarn thickness measuring instrument according to the physical specifications of the actual selected yarn, such as the diameter of a round yarn or the thickness of a flat yarn.

[0032] Step S2, dividing the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain multiple initial cross-sections and corresponding upper and lower boundary line segments.

[0033] The splitting the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections and corresponding upper boundary line segments and lower boundary line segments specifically includes the following sub-steps: Step S201: The three-dimensional model is split along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections.

[0034] In this embodiment, according to a professional software (such as MeshLab) supporting STL format model geometry processing, after importing a complex curved surface three-dimensional model, an equal interval plane splitting function is called in the software operation interface, the warp yarn direction is set as the splitting direction, the software coordinate system is aligned with the warp yarn direction axis to ensure that all splitting planes extend parallel to the warp yarn direction and perpendicular to the weft yarn direction, the weft yarn width is taken as the splitting interval parameter and input to the splitting interval setting item of the software, the software will automatically calculate the number of splitting planes according to the total length of the three-dimensional model along the warp yarn direction and the weft yarn width, the number of splitting planes is the total length of the model along the warp yarn direction divided by the weft yarn width, if there is a remainder, the last cross section which is less than the weft yarn width is reserved to completely cover the model, each splitting plane intersects with the grid surface of the three-dimensional model to form a closed intersection contour, and the plane area corresponding to each intersection contour is an initial cross section, and finally a plurality of initial cross sections uniformly arranged along the warp yarn direction and with a spacing between adjacent cross sections strictly equal to the weft yarn width are obtained.

[0035] Step S202: Intersection lines of upper and lower surface boundaries and the plane of the initial cross section are extracted in the three-dimensional model.

[0036] In this embodiment, relying on a professional geometry analysis software for processing three-dimensional models, spatial coordinate parameters (such as plane equation, vertex coordinates) of each initial cross section are imported to accurately lock the specific position of each initial cross section in the three-dimensional model coordinate system, and then based on the topological structure of the three-dimensional model (such as the difference in grid normal direction of the upper and lower surfaces, the upper surface normal upward and the lower surface normal downward), the upper surface boundary and the lower surface boundary of the three-dimensional model are automatically identified and separated to form two independent continuous contour curves, and then for the plane of each initial cross section, the “plane and curve intersection” calculation function of the software is called to take the plane of the initial cross section as the intersection reference plane and sequentially perform geometry intersection operation with the upper surface boundary contour curve and the lower surface boundary contour curve; during the operation process, the software will automatically calculate the intersection point coordinates of the reference plane and the contour curve, and connect the adjacent intersection points in sequence to form continuous line segments, and finally obtain two intersection lines corresponding to the upper surface boundary and the lower surface boundary of the three-dimensional model respectively for the plane of each initial cross section.

[0037] Step S203: Upper boundary line segments and lower boundary line segments are determined according to the spatial position relationship of the intersection lines and the initial cross sections.

[0038] In the embodiment, a unified spatial orientation reference is set, the direction perpendicular to the plane where the initial section lies is taken as the orientation judgment axis (denoted as Z axis), and the positive direction of the Z axis is defined as up and the negative direction is defined as down. The reference axis is consistent with the thickness distribution direction of the complex curved surface body, ensuring the uniqueness of the up and down orientation judgment. Then, for a single initial section, from the two intersection lines, a plurality of feature points (such as the two end points, the midpoint and the point with obvious curvature change of the intersection line) are selected respectively. The coordinate values of these feature points on the Z axis are obtained by using a coordinate measuring tool. Then, the average value of the Z axis coordinates of all feature points of each intersection line is calculated. The intersection line with a larger average value of the Z axis coordinates is determined as the intersection line corresponding to the upper surface boundary of the three-dimensional model. The intersection line is the upper boundary line segment of the initial section. The intersection line with a smaller average value of the Z axis coordinates is determined as the intersection line corresponding to the lower surface boundary of the three-dimensional model. The intersection line is the lower boundary line segment of the initial section. The feature point selection, Z axis coordinate measurement, average value calculation and orientation judgment operations are repeated for all initial sections in sequence. Finally, the upper boundary line segment and the lower boundary line segment of each initial section are determined.

[0039] In step S3, an initial reference point of the initial section is determined based on the upper boundary line segment and the lower boundary line segment.

[0040] In step S3, an initial reference point of the initial section is determined based on the upper boundary line segment and the lower boundary line segment. In step S301, the thickness type of the initial section is judged based on the upper boundary line segment and the lower boundary line segment.

[0041] In the embodiment, the normal vector direction of each point of the lower boundary line segment is first determined. For the lower boundary line segment (a straight line segment or a curved line segment), a plurality of feature points on the line segment are selected. The normal vector of each feature point is set to be perpendicular to the lower boundary line segment and to point to the direction of the upper boundary line segment, so as to ensure that the normal vector direction is uniformly the direction of the lower boundary line segment to the upper boundary line segment. Then, the perpendicular distances of each feature point to the upper boundary line segment along the corresponding normal vector direction are calculated by using a distance measuring tool. Then, it is judged whether all the calculated perpendicular distances are consistent. If the deviations of all the distance values are within a preset process allowable threshold (such as 0.01 mm), it is determined that the normal vector direction of the lower boundary line segment to the upper boundary line segment is equal in distance, and the thickness type of the initial section is an equal-thickness section. If the deviations of at least two distance values exceed the preset threshold, it is determined that the normal vector direction of the lower boundary line segment to the upper boundary line segment is not equal in distance, and the thickness type of the initial section is a non-equal-thickness section.

[0042] In step S302, an initial reference point of the initial section is determined based on the thickness type.

[0043] In the embodiment, when the thickness type is a non-equal-thickness section, the center point of the lower boundary line segment of the initial section is selected as the initial reference point.

[0044] The determining the initial reference point of the initial cross section based on the thickness type specifically comprises the following sub-steps: In step S30201, the center line of the upper boundary line segment and the lower boundary line segment is determined based on the thickness type being an equal-thickness cross section.

[0045] In this embodiment, when the thickness type is an equal-thickness cross section, a plurality of feature points are selected on the lower boundary line segment, a normal vector of each feature point in the direction of the upper boundary line segment is determined, the total distance of the feature point in the direction of the normal vector to the upper boundary line segment is calculated, half of the total distance is taken as the offset length, and the intermediate point corresponding to the offset length is marked in the direction of the normal vector of each feature point. Finally, all the marked intermediate points are sequentially connected in order, and the continuous line segment formed is the center line maintaining equal distance with the upper boundary line segment and the lower boundary line segment.

[0046] In step S30202, the center point of the center line is calculated to obtain the initial reference point of the initial cross section.

[0047] In this embodiment, the type of the determined center line (straight line segment or curved line segment) is first judged. If the center line is a straight line segment, the midpoint of the line connecting the two endpoints of the straight line segment is directly measured and determined. If the center line is a curved line segment, a plurality of points are uniformly selected along the length direction of the curved line, and after the total length of the curved line is calculated, the point corresponding to the half position of the total length is found. The midpoint or the point corresponding to the half position of the total length is the center point of the center line, that is, the initial reference point of the initial cross section.

[0048] In step S4, the initial cross section is layered based on the upper boundary line segment and the lower boundary line segment using the yarn thickness and the initial reference point to obtain a plurality of layered structures.

[0049] The layering of the initial cross section based on the upper boundary line segment and the lower boundary line segment using the yarn thickness and the initial reference point to obtain a plurality of layered structures comprises: In step S401, the layering manner is determined based on the upper boundary line segment and the lower boundary line segment.

[0050] The determining the layering manner based on the upper boundary line segment and the lower boundary line segment specifically comprises the following sub-steps: In step S40101, the line segment type of the upper boundary line segment and the lower boundary line segment is judged.

[0051] In the embodiment, for the upper boundary line segment and the lower boundary line segment, feature points are selected along the respective line segment length direction, the spatial coordinates of the feature points are obtained by using a coordinate measuring tool, if the coordinates of all feature points on a line segment satisfy that the extension line of the connecting line of any two points can cover all other feature points (i.e. the line segment as a whole has no bending, and the curvature is zero), it is determined that the line segment is a straight line segment, if the feature points on a line segment cannot be collinear, or the direction of the connecting line of adjacent feature points has a significant change (i.e. the line segment has bending, and the curvature is non-zero), it is determined that the line segment is a curved line segment, and then the line segment type of the upper boundary line segment and the lower boundary line segment is respectively determined.

[0052] In step S40102, the layered line is determined based on the line segment type, and the layering manner is determined according to the layered line.

[0053] In the embodiment, the line segment type of the upper boundary line segment and the lower boundary line segment is handled in different cases, if there is a straight line segment in the two line segments (including the case that both are straight line segments, at this time one straight line segment can be selected), the straight line segment is determined as the starting layered line, and the corresponding layered line type is a straight line, and the layering manner is to set a straight line parallel to the starting straight line segment as the layered line in the direction towards the other boundary line segment, to realize layering in the straight line direction, if both line segments are curved line segments, the bending direction of each curved line is first judged, and the line segment with the bending direction towards the other curved line is selected as the starting layered line, and the corresponding layered line is the same as the starting layered line (i.e. a curved line), and the layering manner is to set a curved line with the same shape as the starting curved line segment as the layered line in the direction towards the other curved line segment (consistent with the normal vector direction of the initial reference point), to realize layering in the curved line direction.

[0054] In step S402, the initial cross section is layered to obtain a plurality of layered structures according to the layered manner, the yarn thickness and the normal vector direction of the initial reference point.

[0055] In the embodiment, according to the determined layering manner and the starting layered line, the normal vector direction of the initial reference point is determined as the layering advancing direction (to ensure that the layering direction is always towards the other boundary line segment of the initial cross section), if it is a straight line layering manner, the starting straight line segment is taken as the reference, a plurality of straight lines parallel to the starting straight line segment are generated in sequence as the layered lines in the initial reference point normal vector direction with a fixed interval of the yarn thickness, until the outermost layered line reaches the other boundary line segment of the initial cross section, if it is a curved line layering manner, the starting curved line segment is taken as the reference, a plurality of curved lines with the same shape as the starting curved line segment are generated in sequence as the layered lines in the initial reference point normal vector direction with a fixed interval of the yarn thickness, until the outermost layered line reaches the other boundary line segment of the initial cross section, finally, the independent area surrounded between all adjacent layered lines in the initial cross section is the plurality of layered structures.

[0056] The normal vector direction of the initial reference point is perpendicular to the line segment (the center line corresponding to the equal-thickness section, or the lower boundary line segment corresponding to the non-equal-thickness section) on which the reference point is located and is directed towards the other boundary line segment of the initial section, which is the unified advancing direction of the layering operation.

[0057] In step S5, a flat reference line is constructed using the initial reference points.

[0058] The construction of the flat reference line using the initial reference points specifically includes the following sub-steps: In step S501, the initial reference points are sorted according to the order of the initial sections.

[0059] In this embodiment, the inherent order of the initial sections is extracted. Since the initial sections are divided along the warp direction at intervals of the weft width, the initial sections are sequentially numbered according to the arrangement order along the warp direction in the division process (from the starting end to the end of the warp direction). Since each initial reference point corresponds to a single initial section (one initial section corresponds to one initial reference point), each initial reference point is then labeled with the number of the corresponding initial section. Finally, all the initial reference points are arranged in ascending order of the initial section numbers from 1 to n, completing the sorting of the initial reference points.

[0060] In step S502, the sorted initial reference points are corrected to obtain optimized reference points with the warp width as the target interval.

[0061] The correction of the sorted initial reference points to obtain optimized reference points with the warp width as the target interval specifically includes the following sub-steps: In step S50201, based on the sorted initial reference points, two adjacent initial reference points are selected as a front initial reference point and a rear initial reference point.

[0062] In this embodiment, the two reference points immediately adjacent in position are sequentially selected from the sorted reference point sequence, where the reference point with the smaller sorting number is the front initial reference point, and the reference point with a sorting number only one greater than it is the rear initial reference point. In this way, each group of adjacent front initial reference points and rear initial reference points is determined one by one.

[0063] In step S50202, the front initial reference point is projected onto the line segment on which the rear initial reference point is located to obtain a projection point.

[0064] In the embodiment, the line segment on which the back initial reference point lies is determined, if the back initial reference point corresponds to an equal-thickness cross section, the line segment is the center line of the upper and lower boundary line segments of the equal-thickness cross section, if the back initial reference point corresponds to a non-equal-thickness cross section, the line segment is the lower boundary line segment of the non-equal-thickness cross section, then the front initial reference point is projected to the line segment on which the back initial reference point lies along a straight line parallel to the warp yarn direction, the intersection of the straight line and the line segment on which the back initial reference point lies is the projection point.

[0065] In step S50203, the length of the projection point and the back initial reference point on the line segment on which the back initial reference point lies is calculated.

[0066] In the embodiment, the line segment on which the back initial reference point lies is determined, if the back initial reference point corresponds to an equal-thickness cross section, the line segment is the center line of the cross section, if the back initial reference point corresponds to a non-equal-thickness cross section, the line segment is the lower boundary line segment of the cross section, the target line segment (the center line or the lower boundary line segment, which can be a straight line segment or an arc line segment) is determined, and the two end points of the target line segment are marked to determine the measurement reference and the line segment extension direction, then the length measurement tool is used to measure the distance between the projection point and the back initial reference point along the profile of the target line segment (the distance between two points is directly measured for a straight line segment, and the arc length calculation rule is used for a curve segment), and the obtained result is the length of the projection point and the back initial reference point on the line segment on which the back initial reference point lies.

[0067] In step S50204, the difference between the length and the warp yarn width is calculated to obtain the adjustment amount and the adjustment direction of the back initial reference point.

[0068] In the embodiment, the difference between the length of the projection point and the back initial reference point on the target line segment and the fixed warp yarn width is calculated, the absolute value of the difference is the adjustment amount of the back initial reference point, and the adjustment direction is the warp yarn starting end if the difference is positive, or the warp yarn ending end if the difference is negative, so that the adjustment amount and the direction are determined. The warp yarn width is the fixed step length for extracting the yarn path points, and the distance between adjacent optimization reference points along the line segment on which the adjacent optimization reference points lie should be consistent with the warp yarn width, while the length of the projection point and the back initial reference point is the actual distance, and the difference between the two is the deviation between the actual distance and the ideal distance.

[0069] In step S50205, the back initial reference point is adjusted based on the adjustment amount and the adjustment direction to obtain an optimization reference point.

[0070] In the embodiment, based on the adjustment amount and the adjustment direction, the back initial reference point is moved by the adjustment amount towards the warp yarn starting end or the warp yarn ending end on the target line segment (the center line for an equal-thickness cross section, or the lower boundary line segment for a non-equal-thickness cross section) corresponding to the back initial reference point, and the point obtained after the movement is the optimization reference point.

[0071] As Figure 2As shown, for a cross-sectional region of uniform thickness, with the 28th-30th ( Figure 2 Taking the extraction of the planar baseline of the cross-sectional region (j=28,29,30) as an example, As the initial point of the "section region", yes The normal vector at point A intersects the upper and lower edges at points B and C respectively. and . Move this point and its normal vector along the Y-axis direction... Projecting the "section region" yields... , as well as Intersection with the top and bottom edges and .based on Based on the X-value, its center point needs to be shifted to the right by the warp width. The distance. Soon Along the Y-axis Projecting the "section region" yields... Then Move along the arc until the distance moved is equal to the width of the warp yarn. Thus obtain .

[0072] .

[0073] like Figure 3 As shown, for cross-sectional regions of non-uniform thickness, the initial set of flattened reference points is the center of the lower boundary segment, with points 16-18 ( Figure 3 Taking the extraction of the planar baseline of the cross-sectional regions (j=16,17,18) as an example, As the initial point of the "section region", yes The normal vector at point , and its intersection with the upper edge line is . Similar to the concept of a "cross-sectional region" with uniform thickness, based on... Based on the X-value, its center point needs to be shifted to the left by the warp width. The distance. Soon Along the Y-axis Projecting the "section region" yields... Then... Move along the arc until the distance moved is equal to the width of the warp yarn. Thus obtain .

[0074] .

[0075] Step S503, connecting the optimized reference points to form a flat reference line.

[0076] In this embodiment, after the adjustment amount and adjustment direction of all initial cross-section corresponding post-initial reference points are optimized, the full sequence of optimized reference points is obtained, which still follows the order of the initial cross-section along the warp direction, i.e. arranged in sequence from the starting end to the end of the warp, then according to the type of the target line segment where the optimized reference point is located (if the target line segment is a straight line segment, such as the straight line type center line of the equal thickness cross-section, the straight line type lower boundary line segment of the non-equal thickness cross-section, the corresponding optimized reference points are also distributed in a straight line; if the target line segment is a curve segment, such as the curve type center line of the equal thickness cross-section, the curve type lower boundary line segment of the non-equal thickness cross-section, the corresponding optimized reference points are distributed in a curve), the connection mode is selected. For the straight line distribution of the optimized reference points, the straight line is used to connect the adjacent optimized reference points in sequence. For the curve distribution of the optimized reference points, the curve fitting method (such as smooth connection according to the curvature trend of adjacent reference points) is used to connect the adjacent optimized reference points in sequence, to ensure that the connected line segment is continuous and fits the contour characteristics of the target line segment. Finally, the continuous line segment formed by the connection mode is the flat reference line which can guide the subsequent initial cross-section layering and flattening operation. Since the optimized reference points have been corrected for deviation, the interval along the warp direction can meet the width requirement of the warp, avoiding structural deviation after flattening.

[0077] Step S6, based on the layering structure and the flat reference line, extracting yarn path points with the warp width as the step size to generate a flat three-dimensional weaving path point model.

[0078] In this embodiment, each layering structure in the initial cross-section layering structure corresponds to the distribution area of a layer of yarn. With the generated flat reference line as the spatial reference, the position accuracy in the warp direction is ensured. Then, with the warp width as the fixed step size, the extraction nodes are set along the extension direction of the flat reference line (from the starting end to the end of the warp). At each node, the contour feature points in the vertical direction of the flat reference line (i.e. the weft direction) are extracted for all layering structures that pass through the node, and the three-dimensional coordinates (including layering height, warp direction step position, and weft direction contour position) of each point are recorded. Subsequently, all extracted yarn path points are classified and arranged in the order of warp direction step size and layering order, to ensure that each step size corresponds to a continuous yarn path. Finally, the arranged three-dimensional path point data is imported into a modeling tool to generate a flat three-dimensional weaving path point model that can intuitively reflect the flat distribution state of the yarn. This model can directly provide accurate coordinate reference for the yarn laying track of subsequent weaving equipment.

[0079] Step S7, statistics the path point column density along the flattening direction in the flat three-dimensional weaving path point model.

[0080] In the embodiment, a fixed length which is an integer multiple of the warp width is selected as a statistical unit along the extension direction of the flat reference line, the tiled three-dimensional weaving path point model is traversed, a plurality of non-overlapping statistical intervals are divided along the flat direction according to the statistical unit, a set of path points corresponding to one warp width step is defined as a path point column perpendicularly to the flat direction, the total number of path point columns perpendicularly to the flat direction is counted in each statistical interval, the path point column density along the flat direction of the interval is calculated by dividing the total number of path point columns in the interval by the actual length of the interval, and the density results of all statistical intervals are summarized to calculate the average density value or draw a density distribution curve, so as to reflect the distribution tightness of the path point column along the flat direction in the model, and verify whether the yarn arrangement meets the weaving density design requirement, thereby providing a basis for subsequent model optimization.

[0081] The path point column density is a key parameter for quantifying the yarn distribution density in the tiled model and further calculating the thickness. The path point column density is specifically defined as: the number of path point columns contained in a unit length interval along the extension direction of the flat reference line. One path point column refers to a set of all layered yarn path points distributed perpendicularly to the flat direction at the same extraction position with a warp width step in the tiled three-dimensional weaving path point model.

[0082] In step S8, the path point column density is multiplied by the yarn thickness to obtain thickness distribution data, and a thickness distribution cloud map is generated according to the thickness distribution data.

[0083] In the embodiment, the path point column density of each statistical interval is directly multiplied by the yarn thickness, and the obtained result is the actual thickness value corresponding to the interval. The thickness values of all intervals are summarized to form complete thickness distribution data (including the coordinate information of each interval along the flat direction and the corresponding thickness value), and then the thickness distribution data is imported into a visualization modeling tool. A color mapping rule is set (for example, a larger thickness value corresponds to a darker color, and a smaller thickness value corresponds to a lighter color), and a thickness distribution cloud map which can intuitively present the thickness difference of different regions is generated by taking the statistical interval along the flat direction as the horizontal axis and the thickness value as the vertical axis (or by mapping the space coordinates). The cloud map can clearly show the continuous distribution of the thickness in the tiled three-dimensional weaving model, and facilitate quick identification of the regions with uneven thickness, thereby providing a visual basis for subsequent weaving process parameter adjustment or model optimization.

[0084] The thickness distribution cloud map is shown in FIG. 8. Figure 4 The number of fiber path points in a single column in a cross section is taken as an example to present the cloud map. Figure 4The X direction marked in the figure is the weft direction, the Y direction is the warp direction, and the Z direction is the thickness direction, which together constitute the spatial dimension reference in the figure, and the yarn path point distribution in a single section in the column direction is displayed, and the layer number markers are also marked in the figure (representing the layer number of the layer structure), the target layer currently displayed corresponds to , the layer number of the layer structure, and the adjacent lower layer corresponds to These markers clearly show the layer attribution of the yarn path points in the figure, and the number of yarn path points in a small column in the section (covering layers such as to ) is also marked in the figure Based on this, the thickness of the small column can be calculated by the formula (wherein is the yarn thickness data input during the flattening process, which is the associated basic parameter for calculation), and the thickness distribution cloud map after flattening can be obtained by traversing and calculating all columns of the yarn path point model.

[0085] It should be noted that the term "line segment" in the present application includes both straight line segments and arc line segments. Complex structure three-dimensional woven composites are formed by molding, and the cross-section type is defined as: equal thickness cross-section, non-equal thickness cross-section. Among them, non-equal thickness cross-section can be classified as non-equal thickness / twisted cross-section and non-equal thickness / non-twisted cross-section, and in the field of three-dimensional woven composites, the characteristic is that the upper and lower boundary line segments are usually straight line segments or arc line segments. The present application is applicable to the above two cases.

[0086] As shown in Figure 5 , in another aspect, the present application also provides a complex curved surface three-dimensional weaving flat-twist conversion system, comprising: a processor, an input device, an output device and a memory, the processor, the input device, the output device and the memory are connected with each other, wherein the memory is used for storing a computer program, the computer program includes program instructions, the processor is configured to call the program instructions, and the related steps of the related embodiments of the complex curved surface three-dimensional weaving flat-twist conversion method of the present application are executed.

[0087] The complex curved surface three-dimensional weaving flat-twist conversion system provided by the present application can integrate each functional component in one processing component, or each component can exist physically alone, or two or more components can be integrated in one component. The above integrated components can be realized in the form of hardware or in the form of software functions.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application.

Claims

1. A method of converting a complex curved surface body three-dimensional woven flat twist into a flat sheet, characterized in that, The method comprises: acquiring a three-dimensional model of a complex curved surface body, a warp yarn direction, a weft yarn width, a warp yarn width, and a yarn thickness; segmenting the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections and corresponding upper boundary line segments and lower boundary line segments; determining initial reference points of the initial cross sections based on the upper boundary line segments and the lower boundary line segments; layering the initial cross sections based on the upper boundary line segments and the lower boundary line segments using the yarn thickness and the initial reference points to obtain a plurality of layered structures; constructing a flat reference line using the initial reference points; extracting yarn path points based on the layered structures and the flat reference line at a step length of the warp yarn width to generate a flat three-dimensional weaving path point model.

2. The method of claim 1, wherein the complex curved surface is a three-dimensional woven flat twist conversion method. The segmentation of the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections and corresponding upper boundary line segments and lower boundary line segments comprises: segmenting the three-dimensional model along the warp yarn direction at intervals of the weft yarn width to obtain a plurality of initial cross sections; extracting intersection lines of upper and lower surface boundaries and planes in which the initial cross sections are located in the three-dimensional model; determining upper boundary line segments and lower boundary line segments according to spatial positional relationships of the intersection lines and the initial cross sections.

3. The method of claim 1, wherein the complex curved surface is a three-dimensional woven flat twist conversion method. The determination of initial reference points of the initial cross sections based on the upper boundary line segments and the lower boundary line segments comprises: judging thickness types of the initial cross sections based on the upper boundary line segments and the lower boundary line segments; determining initial reference points of the initial cross sections based on the thickness types.

4. The method of claim 3, wherein the complex curved surface is a three-dimensional woven flat twist conversion method. The determination of initial reference points of the initial cross sections based on the thickness types comprises: when the thickness type is an equal-thickness cross section, determining a center line of the upper boundary line segment and the lower boundary line segment; calculating a center point of the center line to obtain the initial reference point of the initial cross section.

5. The method of claim 1, wherein the complex curved surface is a three-dimensional woven flat twist conversion method. The layering of the initial cross sections based on the upper boundary line segments and the lower boundary line segments using the yarn thickness and the initial reference points to obtain a plurality of layered structures comprises: determining a layering mode based on the upper boundary line segments and the lower boundary line segments; layering the initial cross sections based on the layering mode in a normal vector direction of the yarn thickness and the initial reference point to obtain a plurality of layered structures.

6. The method of claim 5, wherein the complex curved surface is a three-dimensional woven flat twist conversion method. The determination of the layering mode based on the upper boundary line segments and the lower boundary line segments comprises: judging line segment types of the upper boundary line segment and the lower boundary line segment; determining a layering line based on the line segment type and determining the layering mode according to the layering line.

7. The method of claim 1, wherein the complex curved surface is a three- dimensional woven flat twist conversion method. The construction of the flat reference line using the initial reference points comprises: sorting the initial reference points in an order of the initial cross sections; correcting the sorted initial reference points at a target interval of the warp yarn width to obtain optimized reference points; connecting the optimized reference points to form the flat reference line.

8. The method of claim 7, wherein the complex curved surface is a three- dimensional woven flat twist conversion method. The correction of the sorted initial reference points at a target interval of the warp yarn width to obtain optimized reference points comprises: selecting two adjacent initial reference points as a front initial reference point and a rear initial reference point based on the sorted initial reference points; Projecting the front initial reference point to the line segment of the rear initial reference point obtains a projection point; Calculating the length of the projection point and the rear initial reference point on the line segment of the rear initial reference point obtains a length; Calculating the difference between the length and the yarn width obtains an adjustment amount and an adjustment direction of the rear initial reference point; Adjusting the rear initial reference point based on the adjustment amount and the adjustment direction obtains an optimized reference point.

9. The method of claim 1, wherein the complex curved surface is a three- dimensional woven flat twist conversion method. The three-dimensional weaving method of the complex curved surface body further comprises: Statistically obtaining the path point column density along the flat development direction in the flat development three-dimensional weaving path point model; Multiplying the path point column density by the yarn thickness to obtain thickness distribution data, and generating a thickness distribution cloud chart according to the thickness distribution data.

10. A complex curved body three-dimensional woven flat-to-twist conversion system, characterized by, It comprises: A processor, an input device, an output device and a memory, which are connected with each other, wherein the memory is used for storing a computer program, the computer program comprises program instructions, and the processor is configured to invoke the program instructions to execute the three-dimensional weaving method of the complex curved surface body as claimed in any one of claims 1 to 9.

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