Aircraft structural member design modeling system

Abstract

The invention provides an aircraft structural member design modeling system, which belongs to the technical field of structural modeling, and comprises a wireframe model construction module used for completing the generation of a skeleton model according to the spatial position information of a fuselage structure; the skin segmentation module is used for segmenting the fuselage appearance curved surface into small pieces of skin by using frame and stringer elements according to the arranged fuselage structure, and each piece of skin is a natural grid; the node generation module is used for generating intersection points between the transverse elements and the longitudinal elements and respective end points of the transverse elements and the longitudinal elements according to the arranged fuselage structure, the intersection points and the end points form nodes, and after the nodes are generated, the coordinate value attribute editing module corresponding to each node is exported through node coordinates; the natural grid editing module is used for editing natural grids and assigning values to attributes of all structures of the airplane. According to the method, the problem of modeling from zero is avoided, the whole modeling process is clear in hierarchy, the reusability of the skeleton model is high, and the modeling efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of structural modeling, and in particular relates to an aircraft structural component design modeling system. Background Art

[0002] The new model of aircraft has unique innovative structural features. The layout design, topology optimization and parameter optimization of the entire aircraft's flat fusion body are arduous. It is urgent to study the rapid modeling and analysis and optimization design methods of the aircraft's flat body structural parts, and develop a rapid design module for flat fusion body structural parts to support the rapid design of the aircraft's flat fusion body structural parts.

[0003] After decades of development, computer-aided design software has achieved great application in the market, but the current design software still has serious deficiencies in the design and modeling of aircraft flat fusion bodies. Currently, the modeling of aircraft flat fusion bodies needs to be built from scratch in the design software. The design and modeling process is cumbersome and has many repeated steps. The reusability of model parts is low, and there is a lack of standardized design templates and design processes. The design and modeling efficiency is low and the R&D cycle is long. Summary of the invention

[0004] In order to solve the above problems, the present invention focuses on the processes of aircraft flat fusion body layout design, topology optimization, parameter optimization design, etc., studies the rapid modeling and analysis optimization method of aircraft flat fusion body structural parts, and conducts secondary development based on CAD and CAE software (CATIA and HyperWorks) to construct a rapid modeling and simulation optimization module library for aircraft flat fusion body structural parts, realizes functions such as rapid parametric modeling, automatic cleaning of geometric models, rapid finite element modeling of typical structural parts features and template definition, and customized material properties, supports rapid modeling and analysis optimization of aircraft flat fusion body structural parts, speeds up the iterative efficiency of design and analysis verification, improves the quality of simulation models, provides technical support for shortening the development cycle, and specifically provides an aircraft structural parts design modeling system.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: An aircraft structural component design modeling system, comprising: A wireframe model building module is used to establish different geometric graphics sets according to different structural parts of the aircraft, and to build an aircraft skeleton model according to the structural elements and process elements stored in the geometric graphics sets, wherein the aircraft skeleton model includes a frame skeleton model, a beam skeleton model, a floor skeleton model, a long stringer skeleton model, a rib skeleton model and a skin skeleton model; A skin segmentation module is used to segment the fuselage outer surface into multiple skins using frame and stringer elements according to the aircraft skeleton model constructed by the wireframe model construction module, wherein each skin is a natural grid; A node generation module is used to generate the intersection points between the horizontal elements and the vertical elements in the natural grid and the endpoints of the horizontal elements and the vertical elements according to the segmented fuselage structure. Multiple intersection points and endpoints constitute nodes, and the coordinate value corresponding to each node is derived; The attribute editing module is used to edit the natural grid after the nodes are generated, assign the attributes of each aircraft structure according to the coordinate values, and generate the aircraft structure model.

[0006] Preferably, the wireframe model building module includes: A geometry building unit, used to create different geometry sets required for structural arrangement according to different structural parts, wherein the geometry sets are used to store generated skeleton model elements; the skeleton model elements include structural elements corresponding to frames, long girders, beams, floor beams, skins and nodes, and process elements generated during the skin segmentation process; A long truss skeleton model building unit is used to build a long truss skeleton structure by direct generation and occupation surface generation; A frame skeleton model building unit, used to build a frame skeleton structure by direct generation and placeholder surface generation; The skeleton model position adjustment unit is used to modify the spacing of the long stringers or frames according to the surface conditions after the long stringers or frames are generated, find the process elements of the long stringers or frames in the model tree, select the offset plane under the corresponding process element geometry set, and modify the parameters of the offset plane to complete the adjustment of the position of the long stringers or frames and adjust the structural layout of the surface; The skeleton model element naming unit is used to call the rename command before attribute assignment to reorder the elements in the geometry set.

[0007] Preferably, the steps of the geometric figure construction unit to establish a geometric figure set are as follows: Traverse the number of all geometrical sets. If the number of geometrical sets is 1, the geometrical set only contains the "surface" geometrical set. Create the geometrical set of the fuselage structural elements and name the geometrical set as frame, long stringer, and beam. If the number of geometric sets is 9, the geometric sets include 1 "surface" geometric set and 8 fuselage structure element geometric sets; if the number of geometric sets is not equal to 1 or 9, the geometric sets do not meet the requirements.

[0008] Preferably, the construction of the long truss skeleton structure by direct generation and space-occupying surface generation specifically includes: Direct generation: select the reference plane of the placeholder surface according to the name of the long stringer, set the offset and number of offsets of the placeholder surface, select the fuselage shape surface, generate the placeholder surface according to the selected reference plane and the set offset, and then generate the long stringer curve by intersecting the placeholder surface with the fuselage shape surface; Generation of placeholder surfaces: Select the required placeholder surfaces in turn, and then select the fuselage outer surface. The intersection line is generated by intersecting the picked placeholder surface with the fuselage outer surface, which is the long stringer curve.

[0009] Preferably, the attribute editing module includes an attribute creation unit, an attribute importing unit and an attribute exporting unit.

[0010] Preferably, the construction of the frame skeleton structure by direct generation and placeholder surface generation specifically includes: Direct generation: select the reference plane of the placeholder surface according to the frame name, generate the frame width according to the offset and number of offsets of the placeholder surface, first generate an intersection line with the fuselage shape surface where the frame is located, offset the intersection line to generate an offset curve of the intersection line, and finally bridge the intersection line and the offset curve to generate a bridge surface to complete the layout of the frame; Generate placeholder surface: Select an existing placeholder surface, then select the fuselage outer surface where the frame is located, and generate intersection lines with the fuselage outer surface through the picked placeholder surface in turn. Offset the intersection line to generate an offset curve for the intersection line, and finally bridge the intersection line and the offset curve to generate a bridge surface to complete the layout of the frame.

[0011] Preferably, the skin segmentation module includes a segmentation inspection unit, a skin segmentation unit and a subsequent hole opening and surface repair unit. When the skin is segmented, the segmentation inspection unit is used to select and inspect the elements to be segmented, wherein the elements to be segmented are the fuselage outer shape surfaces to be segmented. The skin segmentation unit is used to segment elements longitudinally and transversely. The elements arranged along the fuselage direction are longitudinal segmentation elements, and the elements arranged perpendicular to the fuselage direction are transverse segmentation elements. The hole opening and surface repair unit is used to repair and open holes in the segmented surfaces.

[0012] Preferably, the node generation module is used to select the transverse elements and longitudinal elements of the generated nodes according to the prompts, generate the intersections between the transverse elements and the longitudinal elements in the natural grid and the endpoints of the transverse elements and the longitudinal elements respectively; the transverse dividing elements and the longitudinal dividing elements are fuselage structural elements, among which the elements arranged along the fuselage direction are longitudinal dividing elements, and the elements arranged perpendicular to the fuselage direction are transverse dividing elements.

[0013] Preferably, the property editing module includes a property creation unit, a property import unit and a property export unit. The property creation unit is used to assign section properties and material property parameters to the created elements. The property export unit is used to export the created properties to a property file, which is subsequently transferred to the finite element analysis software together with the model file for subsequent finite element analysis. The property import unit is used to re-import the user-edited property file into CATIA to update the property parameters of each structural element.

[0014] Preferably, it also includes an analysis and simulation module and a structural optimization design module. The analysis and simulation module is used to realize the generation of finite element meshes of aircraft structural parts, complete the loading of loads and perform solution calculations, and optimize corresponding parameters according to the calculation results. The structural optimization design module is used to complete the cross-sectional size optimization, geometric shape optimization and topology optimization of structural parts.

[0015] The aircraft structural component design modeling system provided by the present invention has the following beneficial effects: The present invention is aimed at the modeling characteristics and requirements of the flat fusion body of the aircraft. The wireframe model construction module first establishes different geometric sets according to the different structural parts of the aircraft, and constructs the aircraft skeleton model according to the structural elements and process elements stored in the geometric sets. The skeleton model includes multiple structural part models, which provides a model database for subsequent design and avoids the problem of modeling from scratch. At the same time, the fuselage outer surface is divided into multiple skins through the skin segmentation module, and the block processing improves the processing speed of the computer. Under the premise that the node generation module generates multiple intersections and endpoints, the attribute editing module is used to assign the attributes of each structure of the aircraft to generate an aircraft structural part model. The entire modeling process has a clear hierarchy and the skeleton model has high reusability, which greatly improves the efficiency of modeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiment of the present invention and its design scheme, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 The overall architecture diagram of the aircraft structural component design and modeling system according to Embodiment 1 of the present invention; Figure 2 Flowchart for building a geometrical set; Figure 3 The figure is a classification diagram of fuselage structure types; (a) is a three-dimensional curve structure type, and (b) is a curved surface structure type; Figure 4 A flowchart for constructing a long-truss skeleton structure by direct generation; Figure 5 To construct a long truss skeleton structure flow chart by generating a placeholder surface; Figure 6 A flowchart for constructing a frame skeleton structure by direct generation; Figure 7 A flowchart for constructing a frame skeleton structure by generating a placeholder surface; Figure 8 It is a bidirectional box; Fig. 9Rename the flowchart for the order of element generation process; Fig.10 Check the flow chart for skin segmentation; Fig.11 This is the schematic diagram of skin segmentation; Fig.12 is the node numbering rule; Fig.13 Create a flow chart for the property; Fig.14 Import and export inspection flow chart; Fig.15 To export the attribute flow chart; Fig.16 To import the attribute flow chart; Fig.17 It is the system module hierarchy diagram; Fig.18 The simulation flow chart for analysis. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0019] Example 1 Currently, the modeling of the flat fusion body of the aircraft needs to be built from scratch in the design software. The design and modeling process is cumbersome and has many repeated steps. The reusability of model parts is low, and there is a lack of standardized design templates and design processes, and the design and modeling efficiency is low. Based on this, the present invention provides an aircraft structural part design and modeling system to provide technical support for shortening the development cycle. The structural layout part of the modeling system provided by the present invention completes the generation of the fuselage structure skeleton model, the conversion of the skeleton model to the wireframe model, and the natural grid generation, regional editing, node generation, and attribute import and export. According to the functional characteristics of the structural layout part, the structural layout part is further refined into four functional modules. The first functional module is the wireframe model construction module, which completes the generation of the skeleton model according to the spatial position information of the fuselage structure; the second functional module is the skin segmentation module, which generates a natural grid according to the arranged main fuselage structure; the third functional module is the node generation and editing module, which completes the generation and numbering of node elements; the fourth functional module is the attribute editing module, which completes the natural grid editing, the attribute assignment of each structure of the aircraft, and the attribute import and export. The following is combined with Figure 1 The functions of the system are described in detail.

[0020] The system mainly includes three parts: structural parameter definition module, analysis and simulation module and structural optimization design module.

[0021] Among them, the structural parameter definition module of the first part includes a wireframe model building module, a skin segmentation module, a node generation module and a property editing module.

[0022] First, the wireframe model building module is used to establish different geometric sets according to different structural parts of the aircraft, and to build an aircraft skeleton model according to the structural elements and process elements stored in the geometric sets. The aircraft skeleton model includes a frame skeleton model, a beam skeleton model, a floor skeleton model, a truss skeleton model, a rib skeleton model and a skin skeleton model.

[0023] Specifically, the common structural types involved in the flat fusion body of the fuselage mainly include frames, floor beams, long stringers and ribs. The function of the wireframe model construction module is to complete the layout of the main structure of the fuselage. Before the structural layout, in order to standardize the design process and optimize the model organization structure, it is necessary to first establish the geometric graphics set of each structure, and put the completed geometric elements into the corresponding geometric graphics set. For the frame element, all generated frame structures are finally placed under the frame geometric graphics set, and the remaining elements are also placed under their corresponding geometric graphics sets. According to the structural characteristics of each element, the common structural types of the fuselage are divided into two categories. One is the three-dimensional curve represented by the long stringer, which is generated by the intersection of the reference plane and the fuselage shape surface; the other is the surface represented by the frame, which first generates the intersection line by the intersection of the reference plane and the fuselage shape surface, and then makes a parallel curve of the intersection line, and bridges the two curves to generate the frame surface. Skin segmentation can only be performed after the layout of the main structure of the fuselage is completed.

[0024] The wireframe model building module includes the establishment of geometric figure sets, the arrangement of structural elements such as frames, long girders, beams, floor beams, etc. The wireframe model building module includes a geometric figure building unit, a long girder skeleton model building unit, a frame skeleton model building unit, a skeleton model position adjustment unit, and a skeleton model element naming unit.

[0025] (1) The geometry construction unit is used to create different geometry sets required for structural layout according to different structural parts, and the geometry sets are used to store the generated skeleton model elements; the skeleton model elements include structural elements corresponding to frames, girders, beams, floor beams, skins and nodes, as well as procedural elements generated during the skin segmentation process.

[0026] The function of the Create Geometry Set button is to create the geometry set required for the structural layout. The skeleton model elements generated during the subsequent operation will be placed in the corresponding geometry sets. Before creating the geometry set, each Part should only contain one "surface" geometry set. The elements contained in the "surface" geometry set are the fuselage shape surfaces, that is, the initial model. After clicking the "Create Geometry Set" button, 8 geometry sets will be added under Part, including frame, long stringer, beam, floor beam, skin, node, miscellaneous and unprocessed geometry sets. The frame, long stringer, beam, floor beam, skin and node geometry sets are used to store the corresponding structural elements respectively, and the miscellaneous geometry set is used to store the process elements generated during the skin segmentation process. Click the "Create Geometry Set" button to complete the creation of the geometry set. Different types of geometry sets can be created according to different structural parts. Users can click to complete the creation of the corresponding geometry set according to the actual operation object.

[0027] Figure 2 To establish a geometric set flow chart, the process of establishing a geometric set is as follows: first, traverse the number of all geometric sets under the Part part, hybridBodies1.Count is the number of geometric sets under the Part part, if the number of geometric sets is 1, that is, hybridBodies1.Count=1, then the Part geometric set only contains the "surface" geometric set, then use the Add method of HybridBodies to sequentially establish the geometric sets of the fuselage structural elements, and name the geometric sets as frame, long stringer, beam, etc., and the parent of each newly established geometric set is Part. If hybridBodies1.Count=9, it proves that the geometric sets under the Part at this time include 1 "surface" geometric set and 8 fuselage structural element geometric sets, and the geometric sets have been created, so there is no need to create them. At this time, click the "Create Geometric Set" button repeatedly, and the system will pop up a warning window "Do not create geometric sets repeatedly" and terminate the program. If the program determines that the number of geometric sets is not equal to 1 or 9, it proves that the geometric sets under the Part node do not meet the requirements. At this time, the system pops up a warning window of "Delete useless geometric sets" and terminates the program.

[0028] In the wireframe model building module, except for the button for creating a geometric set, the other buttons are used to arrange the main structure of the fuselage. According to the characteristics of each structure, the common fuselage structure types are divided into two categories: one is the three-dimensional curve represented by the long stringer, Figure 3 It is a classification diagram of fuselage structure types, such as Figure 3 As shown in (a), it is generated by the intersection of the selected reference plane and the fuselage shape surface; the other type is a surface represented by a frame, such as Figure 3As shown in (b), the selected reference plane is first intersected with the fuselage outer surface to generate an intersection line, and then a curve parallel to the intersection line is drawn to bridge the two curves to generate a bridging surface. Frames and floor beams belong to this category.

[0029] (2) The long truss skeleton model construction unit is used to construct the long truss skeleton structure through direct generation and occupation surface generation.

[0030] There are two ways to generate the long truss skeleton model: direct generation and generation through the placeholder surface.

[0031] The first generation method is direct generation. First, you need to enter the name of the long stringer, select the base plane of the placeholder surface, set the offset and number of offsets of the placeholder surface, select the fuselage shape surface, and generate the placeholder surface based on the selected base plane and the set offset. Then, the long stringer curve is generated by intersecting the placeholder surface with the fuselage shape surface. The second generation method is to generate through the placeholder surface. The premise of this method is that all the placeholder surfaces have been arranged. Select the required placeholder surfaces in turn, and then select the fuselage shape surface. The intersection line is generated by intersecting the picked placeholder surface with the fuselage shape surface, which is the long stringer curve. In order to check the accuracy of the generation process operation, before confirming the generation of the long stringer, a preview button is set. Click the preview button to confirm whether the plane, offset and number of the long stringer meet the requirements, observe and preview the generation of the long stringer element. If it meets the requirements, click the "OK" button to complete the generation of the long stringer element; if it does not meet the requirements, choose to reverse the direction of the placeholder surface according to the actual situation, or enter new parameters in the unit that needs to be modified.

[0032] Figure 4 This is a flowchart for building a long truss skeleton structure by direct generation. In the direct generation method, first select the reference plane of the placeholder surface, and then enter the offset distance and number. N, and the required placeholders are generated in an array in sequence. Because all the placeholders are the same datum, the datum plane selection function is a single selection function. The SelectElement2 method of the Selection object in CATIA VBA is used to implement the mouse single selection operation. After calling the SelectElement2 method, the program waits for the user's picking operation. When the mouse completes the datum plane selection on the model structure tree or the model, the selection instruction ends, and the object of the selected element is added to the Selection collection. There are three parameters in the SelectElement2 function. The first parameter is the selection filter, which limits the element type selected by the user during the interactive operation. The element type of the datum plane is a plane, so the present invention sets the filter type to "Plane". At this time, only when the user's mouse moves to the plane type element will the mouse become a "hand shape", indicating that the user can pick up the current element. When the mouse moves to other types of geometric elements, the mouse will become a "forbidden selection" icon, indicating that the current element cannot be selected. The second parameter of the SelectElement2 function is the prompt information, which indicates the prompt information displayed in the CATIA window status bar during the mouse interactive selection. This parameter is set to "Please select a plane" to prompt the user to select a plane element. The third parameter is a Boolean variable, indicating whether the user is allowed to use the pre-selected geometric elements. In order to prevent the user from making a mistaken selection, the present invention sets this parameter to False, and does not allow the user to use the pre-selected geometric elements.

[0033] There is more than one fuselage shape surface where the long stringer is located, so the surface selection function is a multi-selection function, and the mouse multi-selection operation is implemented through the SelectionElement3 method of the Selection object in CATIA VBA. After calling this method, CATIA automatically pops up the "Tool Control Panel". The user can use the mouse to select multiple elements on the model structure tree, or press the Ctrl or Shift key to select multiple elements. After the selection is completed, click the "End Selection" button on the "Tool Control Panel". The system adds the user's multiple selection features to the Selection collection. The aircraft shape surface is a HybridShapes feature in CATIA, so the filter is "HybridShapes", which only allows users to select shape surfaces and does not allow the selection of other types of elements. The prompt message is "Please select a surface", prompting the user to select the element type as a surface.

[0034] After the selection is completed, the first offset plane is generated according to the input offset using the AddNewPlaneOffset method array in HybridShapeFactory. The AddNewPlaneOffset method contains three parameters, namely the reference plane, the offset dThe selected base plane is used as the reference plane of the offset plane, and the first offset plane is generated according to the input offset. After the plane is generated, the generated plane is used as reference plane (reference) 1, and the first selected contour surface is used as reference plane (reference) 2. The first intersection line of the first long stringer is generated by the AddNewIntersection method in HybridShapeFactory. Then, plane 1 is used as reference plane (reference) 1 again, and the second selected contour surface is used as reference plane (reference) 2. The second intersection line of the first long stringer is generated by the AddNewIntersection method in HybridShapeFactory. Repeat the above process until plane 1 and the surface are i The intersection line of plane 1 and the fuselage outer surface is generated. Move all the intersection lines of plane 1 and the fuselage outer surface to the same HybridBody. The name of the HybridBody is the name of the input stringer. Move this HybridBody to the "Stringer" geometry set, and the first stringer is arranged. Use the selected reference plane as the reference plane of the AddNewPlaneOffset method in HybridShapeFactory, and set the offset distance to n × d , n =2, the array generates the second offset plane, and the second stringer is generated in the same way. The above process is repeated until the number of stringers reaches the set number of stringers, and the program ends.

[0035] The flow chart of constructing the long truss skeleton structure by generating the space-occupying surface is as follows Figure 5 First select the existing placeholder surface and complete NThe selection function is a multiple selection function. The mouse multiple selection operation is implemented through the SelectionElement3 method of the Selection object, and the filter is "Plane". Then select the aircraft shape surface where the long stringer is located. The SelectionElement3 method of the Selection object is also used to implement it. The first selected placeholder surface is used as reference surface (reference) 1, and the first selected shape surface is used as reference surface (reference) 2. The AddNewIntersection method in HybridShapeFactory is used to generate the first intersection line of the first long stringer. Then the first selected placeholder surface is used as reference surface (reference) 1 again, and the second selected shape surface is used as reference surface (reference) 2. The AddNewIntersection method in HybridShapeFactory is used to generate the second intersection line of the first long stringer. Repeat the above process until the placeholder surface 1 and the surface i The intersection lines of the stringers are generated, and all the intersection lines of the stringers are moved to the same HybridBody. The name of the HybridBody is the name of the input stringer. Move this HybridBody to the "Stringers" geometry set, and the first stringer is arranged. Select the placeholder surface 2 as the reference surface (reference) 1, and move the selected surface 1 to i Use the AddNewIntersection method to generate the second stringer, use the reference surface 2 as reference surface, move all the intersection lines of the stringers to the same HybridBody, and move this HybridBody to the "Stringer" geometry set. The second stringer is arranged. Repeat the above process until the n The generation of a long stringer is completed and the program ends.

[0036] (3) The frame skeleton model construction unit is used to construct the frame skeleton structure through direct generation and occupancy surface generation.

[0037] There are two ways to generate the frame skeleton model: direct generation and generation based on existing placeholder surfaces.

[0038] The first generation method is direct generation. First, you need to enter the name of the frame, select the reference plane of the placeholder surface, enter the offset of the placeholder surface, the width of the frame generated by the number of offsets, and click the fuselage shape surface where the frame is located. The placeholder surface first generates an intersection line with the fuselage shape surface, and then the program executes the offset command to generate the offset curve of the intersection line. Finally, the intersection line and the offset curve are bridged to generate a bridge surface to complete the layout of the frame. The second generation method is to generate through existing placeholder surfaces. The premise of this method is that the placeholder surfaces required for generating the frame have been arranged. By selecting the existing placeholder surface, and then selecting the fuselage shape surface where the frame is located, the placeholder surface picked up is sequentially generated with the fuselage shape surface. Then the program executes the offset command to generate the offset curve of the intersection line. Finally, the intersection line and the offset curve are bridged to generate a bridge surface to complete the layout of the frame. In order to check the accuracy of the frame generation process, a preview function is added before confirming the generation of the frame. Click the "Preview" button to preview whether the offset, number and width of the frame meet the requirements. If so, click the "OK" button to complete the generation of the frame. If not, you can modify the direction of the placeholder surface of the generated frame, the direction of the generated frame, or re-determine the values ​​of the parameters required to generate the frame according to the actual situation.

[0039] Figure 6This is a flowchart for building a frame skeleton structure by direct generation. First, select the reference plane of the placeholder surface, select the function as a single selection function, and implement the mouse single selection operation through the SelectionElement2 method of the Selection object. The filter is "Plane", and then select the aircraft shape surface where the frame is located, and use the SelectionElement3 method of the Selection object to implement it. The first selected shape surface (surface 1) is used as reference surface (reference) 1. Then, the AddNewPlaneOffset method in HybridShapeFactory is used to generate the first offset plane (plane 1) according to the selected reference plane and the input offset. The generated plane 1 is used as reference surface (reference) 2. The AddNewIntersection method in HybridShapeFactory is used to generate the intersection line (intersection 1) of frame 1. After completion, plane 1 is used as reference surface (reference) 1, and intersection 1 is used as reference surface (reference) 2. The parallel curves of the intersection lines are generated through the AddNewCurvePar method of HybridShapeFactory. The spacing of the parallel curves is the width entered by the user. Finally, use the AddNewBlend method of HybridShapeFactory to bridge the intersection 1 and the parallel curve to complete the creation of frame 1. Then use the second shape surface (surface 2) as reference surface 1 and the first offset plane (plane 1) as reference surface 2. Repeat the above process until the shape surface i The frame 1 is generated with the offset plane 1. Then the offset plane 2 is generated according to the offset distance and other parameters, and used as the reference plane 2 to move the fuselage shape surface 1 to the i As reference plane (reference) 1 to complete the frame generation; repeat the above process until the number of offset planes n >Total number N , that is, all the boxes on the surface have been generated and the program ends.

[0040] Figure 7 This is a flowchart for building a frame skeleton structure by generating a placeholder surface. First, select the generated placeholder surface. The selection function is a multi-selection function. The mouse multi-selection operation is implemented through the SelectionElement3 method of the Selection object. The filter is "Plane". By clicking, the plane is selected. NPlaceholder surfaces. Then select the aircraft shape surface where the frame is located, and use the SelectionElement3 method of the Selection object to implement it. Use the first selected shape surface as reference surface (reference) 1, and the selected placeholder surface 1 as reference surface (reference) 2. Use the AddNewIntersection method in HybridShapeFactory to generate the intersection line (intersection 1) of frame 1. After the intersection line is generated, use placeholder surface 1 as reference surface (reference) 1, and intersection 1 as reference surface (reference) 2. Use the AddNewCurvePar method of HybridShapeFactory to generate the parallel curve (parallel 1) of intersection 1. The spacing of the parallel curves is the width entered by the user. Finally, use the AddNewBlend method of HybridShapeFactory to bridge intersection 1 and parallel 1 to complete the generation of frame 1. Then, the selected placeholder surface 1 is used as reference surface (reference) 2 again, and the selected second shape surface is used as reference surface (reference) 1. The AddNewIntersection method in HybridShapeFactory is used to generate the intersection line (intersection 2) of frame 2. The placeholder surface 2 is used as reference surface (reference) 1, and the generated intersection 2 is used as reference surface (reference) 2. The parallel curve (parallel 2) of intersection 2 is generated through the AddNewCurvePar method of HybridShapeFactory. The generation of frame 2 is completed by bridging intersection 2 and parallel 2. Repeat the above process until the surface is completed. i Repeat the above process to generate a box with the selected k Placeholders k =2 to n ) as reference surface 1, and respectively place the selected fuselage shape surface 1 to i As reference surface 2, until the surface i All the above boxes are generated and the program ends.

[0041] In the subsequent program testing phase, new requirements were put forward for the generation of frames. The phenomenon of frames crossing the curved surface of the fuselage appeared. That is, frames were required to be arranged at both the upper and lower ends of the same curved surface. Figure 8 For this working condition, the existing program is expanded to realize the parametric generation of the bidirectional box.

[0042] The generation of a bidirectional box also provides two generation methods: direct generation and generation using an existing placeholder surface.

[0043] The first generation method is direct generation. First, you need to enter the name of the frame, select the reference plane of the placeholder surface, enter the offset of the placeholder surface, the width of the frame generated by the number of offsets, and click the fuselage shape surface where the two-way frame is located. The placeholder surface first generates an intersection line with the fuselage shape surface, and then the program executes the offset command to generate offset curves of the intersection line in both the inner and outer directions, curve 1 and curve 2, and executes the bridge command to bridge the intersection line with offset curve 1 and offset curve 2 respectively, generate a bridge surface, and complete the layout of the two-way frame. The second generation method is to generate through an existing placeholder surface. The premise of this method is that the placeholder surfaces required to generate the two-way frame have been arranged. By selecting the existing placeholder surface, and then selecting the fuselage shape surface where the two-way frame is located, the picked placeholder surface generates intersection lines with the fuselage shape surface in turn, and then the program executes the offset command to generate offset curves of the intersection line in both the inner and outer directions of the fuselage shape surface, curve 1 and curve 2, and finally bridge the intersection line with offset curve 1 and offset curve 2 to generate a bridge surface, and complete the layout of the two-way frame. In order to check the accuracy of the bidirectional frame generation process, a preview function is added before confirming the generation of the bidirectional frame. Click the "Preview" button to preview whether the offset, number, and width of the upper and lower frames of the bidirectional frame meet the requirements. If they meet the requirements, click the "OK" button to complete the generation of the bidirectional frame; if they do not meet the requirements, you can modify the direction of the placeholder surface of the generated bidirectional frame, the direction of the generated bidirectional frame, or re-determine the values ​​of the parameters required to generate the bidirectional frame according to the actual situation.

[0044] The generation process of the bidirectional frame is similar to that of the frame, except that there are some differences in the offset curve of the intersection line. During the frame generation process, the offset curve is generated only on one side of the selected fuselage shape surface according to the width parameter of the defined frame to complete the subsequent frame surface generation; the generation process of the bidirectional frame requires the inner and outer sides of the selected fuselage shape surface to be offset according to the width of the defined inner and outer frames. W 1 ，W 2 Generate two inner and outer offset curves. Therefore, the generation process of the bidirectional box will not be described in detail here.

[0045] (4) The skeleton model position adjustment unit is used to modify the spacing of the stringers or frames according to the surface conditions after the stringers or frames are generated. The process element of the stringers or frames is found in the model tree, and the offset plane is selected under the corresponding process element geometry set. The parameters of the offset plane are modified to complete the adjustment of the position of the stringers or frames and adjust the structural layout of the surface.

[0046] After the long stringer or frame is generated, you need to modify the spacing of the long stringer or frame according to the surface conditions. You can find the respective process elements in the model tree, select the offset plane under the corresponding process element geometry set, and double-click to modify the parameters of the offset plane to complete the adjustment of the position of the long stringer or frame and adjust the structural layout of the surface.

[0047] (5) The skeleton model element naming unit is used to call the rename command before the attribute is assigned to reorder the elements in the geometric set.

[0048] During the generation process, the structural elements such as frames and long stringers are renamed and sorted accordingly, so that under normal layout, the structural elements contained in the geometric sets such as "frames" and "long stringers" have a certain sequence number. For example, if the whole model needs to arrange 100 long stringers, under normal layout, the automatic numbering of elements is realized during the generation of long stringers, from "changhang_001" to "changhang_100". Fig. 9 The implementation process of sequential naming of element generation process is given. After the relevant elements are generated, before they are placed into the corresponding geometric set, the internal elements of the geometric set are first traversed to obtain the number of elements in the geometric set. N = hybridBodies.Count. If the number of elements inside the geometric set N =0, it indicates that no structural element of the corresponding type has been generated before this operation. The generated element is placed in the corresponding geometric set through the AppendHybridShape method of HybridShapeFactory and the element is renamed using the .Name method. The element numbering starts from "***_001"; if the number of elements in the geometric set is N >0, it indicates that an element of the corresponding type has been generated before this operation. At this time, the program will extract the last element in the geometry set, extract the name of the element and obtain its naming number from it. k , use the AppendHybridShape method of HybridShapeFactory to put the generated element into the geometry set and rename it to "***_ k +1", to achieve the orderly arrangement of the numbers of the same type of structural elements. The program runs until i If it is greater than the number ns that the user wants to generate, the program stops.

[0049] When completing the arrangement of structural elements of the same type, you may need to delete some generated elements. This operation will cause discontinuity in the element numbering under the geometric set, resulting in a "broken number" phenomenon. At this time, you need to call the rename command assigned by the attribute to reorder the elements in the geometric set. The function for selecting the named element is a single-select function. The selected element is the geometric set where the long stringer or frame is located, and the naming prefix is ​​the name of the selected element. The sorting method of the renamed elements is "Name Prefix_000". Calling this command will not affect the position of the already arranged frames, long stringers and other structures.

[0050] Second, the skin segmentation module is used to segment the fuselage outer surface into multiple skins using frame and stringer elements based on the aircraft skeleton model constructed by the wireframe model building module, where each skin is a natural mesh.

[0051] Skin segmentation is to divide the fuselage outer surface into small pieces of skin based on the arranged fuselage structure using elements such as frames and long spars. Each piece of skin is a natural grid, and each skin is generated by four elements. Skin segmentation needs to be performed after all fuselage structural elements are arranged. Therefore, skin segmentation check is required before skin segmentation, and each geometric set is traversed to ensure that all elements required for segmentation have been established. After skin segmentation is completed, the fuselage outer surface is divided into small pieces of surfaces, and the arrangement of fuselage structural elements can no longer be performed. Attribute editing can only be performed after skin segmentation is completed.

[0052] The skin segmentation module includes segmentation inspection, skin segmentation and subsequent hole opening and surface repair functions, specifically including a segmentation inspection unit, a skin segmentation unit and a subsequent hole opening and surface repair unit. When the skin is segmented, the segmentation inspection unit is used to select and inspect the elements to be segmented, where the elements to be segmented are the fuselage outer shape surfaces to be segmented. The skin segmentation unit is used to segment elements longitudinally and transversely. The elements arranged along the fuselage direction are longitudinal segmentation elements, and the elements arranged perpendicular to the fuselage direction are transverse segmentation elements. The hole opening and surface repair unit is used to repair and open holes in the segmented surfaces.

[0053] The split check traverses all geometric sets under the part to ensure that the model has generated corresponding structural elements and the executability of the subsequent skin splitting operation. If the corresponding structural elements have been arranged, a prompt window "You can perform skin splitting" will pop up; otherwise, a corresponding prompt window will pop up according to the actual situation, for example, "The long stringer has not been arranged, please arrange the long stringer first", until the splitting conditions are met, and the skin splitting operation will be performed.

[0054] Fig.10Check the flow chart for skin segmentation. First, traverse all geometric sets under Part and determine the number of geometric sets under Part. If hybridBodies1.Count is 1, it means that no elements have been established yet, and a warning pop-up window "Please establish geometric sets first" will pop up. If hybridBodies1.Count is 9, it means that geometric sets have been established. At this time, traverse the number of elements under each geometric set in turn. If the number of elements under the "box" geometric set is 0, it means that the box has not been established yet. A warning pop-up window "Please establish the box first" will pop up to end the program. If it is not 0, traverse the number of elements under the long stringer, beam and other geometric sets in turn. If the number is zero, a corresponding warning pop-up window will pop up. If none of them are zero, the user is prompted to perform skin segmentation. If the number of geometric sets under Part is not 1 or 9, it means that the user has not operated according to the operating rules, and a warning window will pop up to terminate the program.

[0055] When splitting the skin, the user needs to select the element to be split, which is the fuselage outer surface to be split, and then select the longitudinal split element and the transverse split element. The longitudinal split element and the transverse split element are the generated fuselage structural elements. The elements arranged along the fuselage direction are longitudinal split elements, and the elements arranged perpendicular to the fuselage direction are transverse split elements.

[0056] Fig.11 This is the skin segmentation schematic. When the skin is segmented, first select the fuselage shape surface to be segmented. The selection function is a single selection function. Then select the longitudinal segmentation element and the transverse segmentation element. The selection function is a multi-selection function. The mouse multi-selection operation is implemented through the SelectionElement3 method of the Selection object. Because the segmentation element is the intersection of the box or the intersection element such as the long stringer, the filter element type is HybridShapeIntersection. Take the fuselage surface as reference surface (reference) 1, and the longitudinal segmentation element 1 as reference surface (reference) 2. Use the AddNewHybridSplit method of HybridShapeFactory to split the surface into HybridShapeSplit1 and HybridShapeSplit2. Then use HybridShapeSplit1 as reference surface (reference) 1, and transverse segmentation elements 1 to n as reference surfaces (reference) 2 respectively. Use the AddNewHybridSplit method of HybridShapeFactory to split HybridShapeSplit1 into skins. Use HybridShapeSplit2 as the split element and repeat the above splitting process to complete the skin splitting.

[0057] After CATIA completes the structure layout, skin segmentation and attribute creation and export, import the model into HyperMesh to divide the mesh. Depending on the quality of the mesh, the size of the skin may need to be adjusted locally. Re-import the model with attributes assigned to all geometric sets into CATIA, select the skin unit that needs to be adjusted in the model, find the serial number of this skin in the skin geometric set, use the surface fill function, select the replacement element and click it in the model tree to generate a new skin.

[0058] The surface filling function selection function is a single selection function. The mouse single selection operation is implemented through the SelectionElement2 method of the Selection object. The filter element type is HybridShapeSplit. The selected skin surface is used as reference surface (reference) 1, and the boundary hybridshapeBoundary1 of the skin surface is extracted through the AddNewBoundaryOfSurface method of hybridShapeFactory. Then hybridshapeBoundary1 is used as reference surface (reference) 2, and the surface filling is implemented through the AddNewFill method of hybridShapeFactory to generate the surface hybridshapeFill1. The name of hybridshapeFill1 is made consistent with the original skin surface through the surface name attribute modification command, and the original skin surface is hidden to replace the original skin surface.

[0059] Third, the node generation module is used to generate the intersection points between the horizontal elements and the vertical elements in the natural grid and the endpoints of the horizontal elements and the vertical elements according to the segmented fuselage structure. Multiple intersection points and endpoints constitute nodes, and the coordinate value corresponding to each node is exported.

[0060] Node generation is to generate the intersection points between the transverse elements and the longitudinal elements and the endpoints of the transverse elements and the longitudinal elements according to the arranged fuselage structure. Multiple intersection points and endpoints constitute nodes. After the nodes are generated, the coordinate values ​​corresponding to each node are derived through the node coordinates. The coordinate file is transferred to the finite element analysis software together with the model file for subsequent finite element analysis.

[0061] The node generation module includes the generation of nodes and the export of node coordinates.

[0062] The user needs to select the horizontal and vertical elements of the generated node according to the prompts; the horizontal and vertical split elements are fuselage structural elements, among which the elements arranged along the fuselage direction are vertical split elements, and the elements arranged perpendicular to the fuselage direction are horizontal split elements. The selection function in this process is a multi-selection function, and the mouse multi-selection operation is realized through the SelectionElement3 method of the Selection object. Because the horizontal and vertical elements of the generated node are intersection elements such as boxes or long beams, the selection filter element type is set to HybridShapeIntersection, corresponding to the intersection element. During the program running process, the selected vertical element 1 is first used as reference surface (reference) 1, and the selected horizontal elements 1 to n are used as reference surface (reference) 2. The intersection of the horizontal and vertical elements is obtained through the AddNewIntersection method of HybridShapeFactory. At the same time, the endpoints of the horizontal and vertical elements are generated through the AddNewPointOnCurveFromPercent of HybridShapeFactory. Subsequently, the vertical element 2 is used as the reference surface (reference) 1, and the horizontal elements 1 to n are used as the reference surface (reference) 2. Repeat the above operation to complete the generation of all nodes.

[0063] For the convenience of subsequent analysis, it is required to be able to quickly locate the structural elements such as the long stringer and frame where the node is located based on the node number, so as to facilitate the rapid positioning of the long stringer and frame elements that need to be adjusted according to the force deformation after the subsequent load is applied. Therefore, during the node generation process, the program numbers the nodes according to the numbers of the long stringer and frame of the generated node and certain numbering and naming rules, so that each node strictly corresponds to the structural element that generates the node. Fig.12 The node numbering rules are given, and the meaning of the numbers corresponding to the corresponding positions in the node numbering is given. The one-to-one correspondence between the nodes and the frames and stringers is reflected in the 4th to 6th positions being the frame numbers and the 7th to 9th positions being the stringer numbers.

[0064] The subsequent finite element analysis process requires the nodes generated in the above process for mesh division and load application. Therefore, multiple intersections and endpoints form nodes. After the nodes are generated, the node numbers and spatial position coordinates between the nodes need to be exported to facilitate the subsequent import of the model into the finite element software. Click the "node coordinate export" button to export the node coordinates as a .csv file and save it to the folder where the model is located.

[0065] Fourth, the attribute editing module is used to edit the natural grid after the nodes are generated, assign the attributes of each aircraft structure according to the coordinate values, and generate the aircraft structure model.

[0066] The property editing module includes a property creation unit, a property import unit and a property export unit. The property creation unit is used to assign section properties and material property parameters to the created elements. The property export unit is used to export the created properties to a property file, which is subsequently transferred to the finite element analysis software together with the model file for subsequent finite element analysis. The property import unit is used to re-import the user-edited property file into CATIA to update the property parameters of each structural element.

[0067] The attribute editing module can complete the layout of all fuselage structures and the setting of attributes after the skin segmentation. This module includes the following functions: attribute creation, attribute import, and attribute export. Attribute creation assigns parameters such as section attributes and material attributes to the created elements. Attribute export is to export the created attributes to an attribute file, which is then transferred to the finite element analysis software along with the model file for subsequent finite element analysis. The attribute file can be edited or modified and then imported into CATIA to update the attributes of the structure. Table 1 shows the meaning of each parameter in the attribute editing module.

[0068] Table 1 Basic parameters

[0069] The purpose of attribute import and export check is to check whether the conditions for importing and exporting attributes are met before exporting and importing attributes, so as to ensure the smooth progress of subsequent attribute import and export operations. The attribute export operation exports the attributes of elements such as frames, stringers and skins to .csv attribute files for manual editing or finite element analysis by users. The attribute import operation re-imports the attribute file edited by the user into CATIA to update the attribute parameters of each structural element. To create an attribute, first select the geometric set to which the attribute element is to be assigned, and all elements under the geometric set are displayed on the panel. There are three operation functions: select all, deselect and reset, which can realize one-click selection of attribute-assigned elements or click on the elements to be assigned attributes, and then select material parameters, etc. According to the prompts, complete the input of information such as section parameters to complete the creation of attributes. Table 2 gives the types and meanings of section parameters, and explains the corresponding interface shape parameters accordingly.

[0070] Table 2 Extended attribute parameters

[0071] Fig.13Create a flow for the attribute. The process of attribute creation is as follows: first select the geometric set of the element where the attribute is to be created, and select the function as a single-select function; after selecting the element, select the parameters according to the attribute creation interface or enter the parameters according to the diagram; after all parameters are entered, create all parameters according to the CreateString method of Parameters to generate a parameter set. At this time, all parameters are under the Parameter node. To move them to the geometric set of the selected element, add all parameters under the Parameter node to the Selection collection using the Add method of Selection, then use the Cut method of Selection to cut all parameters, and finally use the Paste method of Selection to paste them to the target element geometric set, and the attribute creation is completed.

[0072] Fig.14 This is a flowchart for import and export checks. The purpose of import and export checks is to ensure that all structural elements and skins are assigned attributes and that the attribute parameters are complete before exporting or importing attributes, so as to avoid program errors when importing and exporting attributes and interrupting import and export. For example, when importing and exporting checks, first traverse all box elements under the "box" geometry set, then extract the parameter list under each box element through the Sublist method of Parameters, and obtain the number of parameters. If the number of parameters is 14, that is, parameters2.Count=14, it means that all parameters of this box element have been created, and then extract the parameter list of the next box element, until the parameter list of all elements under the "box" geometry set is traversed and the parameters are complete, the system prompts that the attributes can be exported. If the number of parameters is 0, it means that the attribute parameters have not been created yet, and a corresponding pop-up window warning will pop up to prompt the user to complete the attribute creation first. If the number of parameters is other values, it means that the attribute parameters are created incorrectly, and a corresponding pop-up window warning will pop up and the program will terminate.

[0073] After the operation of batch-assigning attributes to the girder, frame or skin is completed, the names of all subset elements under the three corresponding geometric sets are the same. Call the rename function, select the function as a single-select function, select the element as a geometric set such as the girder, frame or skin, enter the corresponding name prefix, and the corresponding subset element sorting method is "Name Prefix_000". Associate the subset elements with the attributes to achieve unified names, which is convenient for subsequent HyperMesh import and one-to-one correspondence of associated attributes. Fig.15This is the process of exporting properties. Before exporting properties, perform an import and export check. If the system prompts that properties can be imported and exported, you can start exporting properties. When exporting properties, first use the CreateObject method to call the Excel com component, and then use the Open method of Workbooks to open the property file. In order to avoid the influence of the previous property file on the exported properties, you need to use the Delete method to clear the contents of the property file. Write the parameter name to the first line of the property file, then traverse each element under Part, use the Sublist method of Parameters to extract the parameter set under each element, and write them to the same line of the property file in sequence. After traversing the parameter sets of all elements, write each line of the property file in sequence to export all property parameters. When all properties are written, use the Save method to save the file, use the Close method to close the file, and save it to the folder where the model is located. At this time, the system interface prompts that the properties have been exported and the export is complete.

[0074] Fig.16 This is the flow chart for importing properties. Importing properties means importing the manually modified property file into CATIA to update the parameters of each element. Since only the value of the parameter is changed, the order and name of the parameter remain unchanged, so when importing properties, you only need to overwrite the previous parameters with the property parameters. The process of importing properties is: use the CreateObject method to call the ExcelCOM component, then use the Open method of Workbooks to open the property file, select the first element under Part and use the Sublist method of Parameters to extract the parameter set of this element, then assign the first row of parameter values ​​in the property file to the parameter set of the first element, and the parameters of the first element are imported. Next, select the second element under Part and use the Sublist method of Parameters to extract the parameter set of this element, and assign the second row of parameter values ​​in the property file to the parameter set of the second element. Repeat the above process until the parameter values ​​of all elements are updated. Finally, use the Save method and the Close method to save and close the property file. The above process can be automatically completed by clicking the "Property Import" button with the mouse.

[0075] The main purpose of the modification function of the material library is to meet the needs of users to update the material library during use, including adding materials, modifying materials and deleting materials. The operation process is as follows: first, select the operation to be performed (adding materials, modifying materials or deleting materials) in the "Modification Type" drop-down menu. The operation of adding materials requires the name of the added material and the relevant performance parameters to be entered into the specified position of the interface. The program establishes a link with the material library and completes the update of the newly added materials in the material library based on the input parameters; the operation of modifying materials requires selecting the required modified material in the "Material Name" drop-down menu of the interface. Users can modify the relevant performance parameters of the material by themselves, and the program automatically updates the specified position of the material library; finally, the operation of deleting materials also requires selecting the name of the element to be deleted in the "Material Name" drop-down menu. The program executes the delete command, deletes the relevant content of the specified material, and completes the update of the material library.

[0076] On the basis of the above-mentioned design modules, the present invention can also expand the modules. In the subsequent program testing phases, the relevant modules are expanded in combination with the existing models. For the models with arranged frames, long girders, beams and other structural elements, it is no longer necessary to repeat the arrangement of the frames, long girders and other structural elements. A corresponding expansion module is provided to extract the existing structural elements and automatically identify them under the corresponding geometric graphics set. During the extraction process, the structural elements are renamed to ensure the sequential arrangement of the elements under the same geometric graphics set.

[0077] According to the actual situation of the existing structural elements in the model, select the corresponding frames, long girders, beams and other structural elements, and click the fuselage outer surface where they are located to complete the extraction operation of the corresponding elements.

[0078] The extraction process principles and processes of each element are similar. Here we only list the extraction process of the existing frame elements for discussion. First, select the existing frame surface element of the model. The selection function is a multi-selection function. The mouse multi-selection operation is implemented through the SelectionElement3 method of the Selection object. The filter is set to "HybridShape". Then select the aircraft shape surface where the frame is located. The SelectionElement2 method of the Selection object is used to implement the mouse single selection operation. The selected aircraft shape surface is used as reference surface (reference) 1. Then, the AddNewPlaneOffset method in HybridShapeFactory is used to set the offset to 0 according to the selected frame surface, and the offset plane (plane 1) of the frame surface is generated. The generated plane 1 is used as reference surface (reference) 2. The AddNewIntersection method in HybridShapeFactory is used to generate the intersection line (intersection 1) between frame surface 1 and the selected fuselage shape surface, and the generated offset plane and intersection line are placed in the process element geometry set of the corresponding frame. The selected frame surface is renamed and placed in the corresponding geometry set to complete the extraction process of this frame surface. Repeat the above operation until all the selected frame surfaces are extracted into the "Frame" geometry set, thus completing the extraction process of frame surface elements.

[0079] The second part is the analysis and simulation module, specifically the HyperMesh analysis and simulation module. Finite element modeling and analysis is generally based on the HyperMesh CAE process automation system. This system uses the HyperWorks Process Manager tool software to achieve standardization and automation of CAE analysis, and improve the quality and efficiency of enterprise product analysis. Finite element modeling and analysis is generally based on the HyperMesh CAE process automation system. This system uses the HyperWorks Process Manager tool software to condense the professional knowledge of engineers into the enterprise's modeling process and solidify its process, ultimately achieving standardization and automation of CAE analysis, and improving the quality and efficiency of enterprise product analysis.

[0080] Analyze user needs and determine the functional requirements of the CAE process automation system: 1. Users can easily call system files and enter the process automation system.

[0081] 2. When using the system, users can easily import natural mesh models and natural mesh properties from CATIA.

[0082] 3. Users can perform geometry cleanup, automatic mesh generation, and load import.

[0083] 4. Users can use the system to perform static analysis, modal analysis and size optimization on the model.

[0084] According to the above functional requirements, the modeling module structure diagram is designed. By further studying the relationship between the functional modules, the hierarchical diagram between the system modules is obtained as follows: Fig.17 This hierarchical diagram illustrates the logical relationship between the functional modules, among which the size optimization module, static analysis module, and modal analysis module are parallel modules.

[0085] The main steps of finite element analysis using HyperWorks are pre-processing, solving, and post-processing. Therefore, the analysis process of modules such as static analysis, modal analysis, and dimensional optimization is as follows: Fig.18 As shown in the figure, these modules have the same module parts: model / attribute import, geometry cleaning, meshing, load / constraint loading, but the analysis settings are different. First, the design and implementation of the common module are studied, and then the development of each analysis module is realized.

[0086] The simulation optimization module is mainly used to realize the generation of finite element mesh, complete the loading of loads and perform solution calculations, and optimize the corresponding parameters. Comprehensively use Tcl / Tk programming technology, use Process Studio as a template to create tools, and combine HyperMesh to realize file import and attribute import, automatic feature surface processing, automatic attribute assignment, automatic mesh unit generation, load processing and automatic loading, optimization and solution, etc.; combine OptiStruct and HyperView to optimize the main structural parameters of the model.

[0087] The finite element mesh model is mainly used to complete the development of the simulation analysis module of the flat fusion structure of the aircraft. Based on the finite element theory, the model is analyzed and solved. The designer can design the finite element mesh model in detail according to the design requirements of the model. When constructing the finite element mesh model, the natural mesh model and natural mesh properties created by CATIA must be imported first, and the geometry and unit set, and material / property cards must be automatically created. Secondly, the imported natural mesh model is geometrically processed to remove the redundant curves on the characteristic surface of the natural mesh model to improve the quality of finite element mesh division, and the optimal mesh unit division method is found through a cyclic iteration method. Finally, different finite element mesh models are assembled according to the corresponding finite element mesh assembly rules. If the finite element mesh quality meets the requirements, the load processing preloading, solution calculation, solution post-processing and other functions are run. Structural optimization analysis is performed by optimizing the structure through the analysis and optimization environment built based on the secondary development of Altair OptiStruct. In this environment, the skin thickness of the model can be optimized according to the design variables, objective functions and constraints.

[0088] The third part is the structural optimization design module. Currently, structural optimization is mainly divided into three types: cross-sectional size optimization, geometric shape optimization and topological optimization. The aircraft skin discussed in this invention is a thin-walled part. In order to ensure its basic function, there is little room for structural and shape optimization, so it is more reasonable to use size optimization.

[0089] Size optimization is the most classic type of optimization design and is mainly used in the detailed design stage. Since it mainly modifies and optimizes the size or parameters of the model, the shape of the overall structure will not change. The objects of size optimization can be the cross-sectional dimensions of the beam, the length or diameter of the rod, the thickness of the plate, the material properties of the optimization object, the ply angle and thickness of the composite material, etc. Select the above optimization objects as design variables, and find a set of optimal data under the premise of considering the set constraints, so that the objective function of the optimization object can be optimized. The biggest feature of size optimization is that designers can more conveniently set the optimized design variables, and at the same time support the optimization method of data discretization. An optimization model is mainly divided into three parts: design variables, constraints and objective functions.

[0090] 1. Design variables Design variables are a set of parameters related to structural features that can be continuously changed during the optimization process. By adjusting the design variables, the optimization can obtain the optimal solution. According to the different design variables, the optimization model can be divided into size optimization model, shape optimization model and topology optimization model. The research object of this invention is the aircraft body, whose main structural feature is the skin thickness, so size optimization is the most appropriate.

[0091] The design variables can be represented by a set of column vectors: ; in, n is the number of design variables.

[0092] 2. Constraints Since some design solutions do not conform to the actual situation or cannot meet the engineering requirements, it is necessary to set some restrictions to constrain them. These restrictions are called constraints.

[0093] According to the different forms of expression, the constraints can be divided into inequality constraints and equality constraints. The expressions are as follows: ; ; in, l is the number of inequality constraints, m is the number of equality constraints.

[0094] 3. Objective Function The objective function is the evaluation standard of the entire optimization scheme and the ultimate goal of structural optimization, which can be the deformation, quality, etc. of the structure. According to the number of objective functions, the optimization model can be divided into a single-objective optimization model and a multi-objective optimization model.

[0095] The objective function can be expressed as: ; From the above formula, we can see that the objective function is n The design variables are functions of the independent variables.

[0096] According to the above three parts, the optimization model can be established as follows: Design variables: ; Constraints: ; ; Objective function: min F(X) ; This optimization model seeks the minimum value of the objective function by adjusting the design variables while satisfying the constraints.

[0097] It also includes optimization algorithm design, using the software OptiStruct to perform static linear optimization of aircraft skin. OptiStruct uses a gradient-based optimization algorithm to solve the optimization problem. The default optimization algorithm is called the method of feasible directions (MFD). Other optimization algorithms include: sequential quadratic programming (SQP), dual method (DUAL), etc.

[0098] As the default optimization algorithm of OptiStruct, the feasible direction method can be used to solve large constrained optimization problems. Like many optimization algorithms, the feasible direction method also requires continuous iteration to find the optimal solution. Its basic principle is to start from an initial point in the feasible domain. X 0 To begin, move the initial point to a constraint surface and determine the search direction D k With step length α , iteratively calculate the next feasible point according to the following formula X k+1 : ; Search Direction D k In the feasible direction method, it is also called the feasible direction. The feasible direction needs to meet the two conditions of feasibility and descent so that the next point obtained by the search can be a feasible point and the objective function value is close to the optimal value.

[0099] The feasible conditions are as follows: ; in, Indicates feasible point X k The gradient of the constraint surface. If the feasible point is on several constraint surfaces at the same time, the above conditions must be satisfied at the same time.

[0100] The descent conditions are as follows: ; in, Indicates that the objective function is at a feasible point X k The gradient of the objective function is used to ensure that the objective function of the present invention has a downward trend.

[0101] Determine the feasible direction D k After that, you need to determine the step length α There are usually two methods to determine the step size using the feasible direction method: the first is to perform one-dimensional optimization search according to the feasible direction. If the point is within the constraint area at this time, the optimal step size is taken; the second is to change the step size so that the point searched according to the above method is outside the feasible domain and is exactly on the constraint surface.

[0102] After determining the feasible direction and step size, you can continue to iterate. In order to terminate the iteration, you also need to determine the final convergence condition. Common convergence conditions are as follows: ; in, ε and ε 2 is the convergence accuracy; δ is the constraint tolerance, which means that the feasible point X k Out of Constraint Function Within a certain range, if the above formula is satisfied after iteration, the iteration is considered to have converged, and the optimization model at this time has reached the optimal solution.

[0103] In summary, the aircraft structural component design and modeling system provided by the present invention mainly completes the following functions: 1) The construction principles of common fuselage structural parts such as frames, beams, and long stringers are proposed. According to the needs of designers and the skeleton model, the fuselage wireframe model is quickly and automatically generated, including wireframe model generation, natural mesh generation, natural mesh editing, and natural mesh attribute import and export.

[0104] 2) Based on the natural grid model, a finite element model with the grid scale required for body analysis is established, the finite element model is assembled, and the automatic loading of the load and the corresponding calculation settings can be realized. After the calculation is completed, the required results can be automatically extracted.

[0105] 3) After the structural layout is determined, the main structural parameters are optimized. After the parameter optimization is completed, the optimized results are updated to the original model.

[0106] 4) It can provide design templates for rapid modeling and simulation optimization modules of aircraft flat fusion bodies, and standardize the design process.

[0107] It should be noted that the above-described specific implementations can enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope disclosed in the present invention belong to the protection scope of the present invention.

Claims

1. An aircraft structural component design modeling system, characterized in that: include A wireframe model building module is used to establish different geometric graphics sets according to different structural parts of the aircraft, and to build an aircraft skeleton model according to the structural elements and process elements stored in the geometric graphics sets, wherein the aircraft skeleton model includes a frame skeleton model, a beam skeleton model, a floor skeleton model, a long stringer skeleton model, a rib skeleton model and a skin skeleton model; A skin segmentation module is used to segment the fuselage outer surface into multiple skins using frame and stringer elements according to the aircraft skeleton model constructed by the wireframe model construction module, wherein each skin is a natural grid; A node generation module is used to generate the intersection points between the horizontal elements and the vertical elements in the natural grid and the endpoints of the horizontal elements and the vertical elements according to the segmented fuselage structure. Multiple intersection points and endpoints constitute nodes, and the coordinate value corresponding to each node is derived; The attribute editing module is used to edit the natural grid after the nodes are generated, assign the attributes of each aircraft structure according to the coordinate values, and generate the aircraft structure model.

2. The aircraft structure design modeling system according to claim 1, characterized in that: The wireframe model building module includes: A geometry building unit, used to create different geometry sets required for structural arrangement according to different structural parts, wherein the geometry sets are used to store generated skeleton model elements; the skeleton model elements include structural elements corresponding to frames, long girders, beams, floor beams, skins and nodes, and process elements generated during the skin segmentation process; A long truss skeleton model building unit is used to build a long truss skeleton structure by direct generation and occupation surface generation; A frame skeleton model building unit, used to build a frame skeleton structure by direct generation and placeholder surface generation; The skeleton model position adjustment unit is used to modify the spacing of the long stringers or frames according to the surface conditions after the long stringers or frames are generated, find the process elements of the long stringers or frames in the model tree, select the offset plane under the corresponding process element geometry set, and modify the parameters of the offset plane to complete the adjustment of the position of the long stringers or frames and adjust the structural layout of the surface; The skeleton model element naming unit is used to call the rename command before attribute assignment to reorder the elements in the geometry set.

3. The aircraft structural component design modeling system according to claim 2, characterized in that: The steps of the geometric graphics building unit to establish a geometric graphics set are as follows: Traverse the number of all geometrical sets. If the number of geometrical sets is 1, the geometrical set only contains the "surface" geometrical set. Create the geometrical set of the fuselage structural elements and name the geometrical set as frame, long stringer, and beam. If the number of geometric sets is 9, the geometric sets include 1 "surface" geometric set and 8 fuselage structure element geometric sets; if the number of geometric sets is not equal to 1 or 9, the geometric sets do not meet the requirements.

4. The aircraft structure design modeling system according to claim 3, characterized in that: The construction of the long truss skeleton structure by direct generation and occupation surface generation specifically includes: Direct generation: select the reference plane of the placeholder surface according to the name of the long stringer, set the offset and number of offsets of the placeholder surface, select the fuselage shape surface, generate the placeholder surface according to the selected reference plane and the set offset, and then generate the long stringer curve by intersecting the placeholder surface with the fuselage shape surface; Generation of placeholder surfaces: Select the required placeholder surfaces in turn, and then select the fuselage outer surface. The intersection line is generated by intersecting the picked placeholder surface with the fuselage outer surface, which is the long stringer curve.

5. The aircraft structure design modeling system according to claim 3, characterized in that: The attribute editing module includes an attribute creation unit, an attribute importing unit and an attribute exporting unit.

6. The aircraft structure design modeling system according to claim 3, characterized in that: The construction of the frame skeleton structure by direct generation and placeholder surface generation specifically includes: Direct generation: select the reference plane of the placeholder surface according to the frame name, generate the frame width according to the offset and number of offsets of the placeholder surface, first generate an intersection line with the fuselage shape surface where the frame is located, offset the intersection line to generate an offset curve of the intersection line, and finally bridge the intersection line and the offset curve to generate a bridge surface to complete the layout of the frame; Generate placeholder surface: Select an existing placeholder surface, then select the fuselage outer surface where the frame is located, and generate intersection lines with the fuselage outer surface through the picked placeholder surface in turn. Offset the intersection line to generate an offset curve for the intersection line, and finally bridge the intersection line and the offset curve to generate a bridge surface to complete the layout of the frame.

7. The aircraft structure design modeling system according to claim 3, characterized in that: The skin segmentation module includes a segmentation inspection unit, a skin segmentation unit and a subsequent hole opening and surface repair unit. When the skin is segmented, the segmentation inspection unit is used to select and inspect the elements to be segmented, wherein the elements to be segmented are the fuselage outer shape surfaces to be segmented. The skin segmentation unit is used to segment elements longitudinally and transversely. The elements arranged along the fuselage direction are longitudinal segmentation elements, and the elements arranged perpendicular to the fuselage direction are transverse segmentation elements. The hole opening and surface repair unit is used to repair and open holes in the segmented surfaces.

8. The aircraft structure design modeling system according to claim 1, characterized in that: The node generation module is used to select the horizontal elements and the vertical elements of the generated nodes according to the prompts, and generate the intersection points between the horizontal elements and the vertical elements in the natural grid and the endpoints of the horizontal elements and the vertical elements respectively; the horizontal dividing elements and the vertical dividing elements are fuselage structural elements, among which the elements arranged along the fuselage direction are the vertical dividing elements, and the elements arranged perpendicular to the fuselage direction are the horizontal dividing elements.

9. The aircraft structure design modeling system according to claim 1, characterized in that: The attribute editing module includes an attribute creation unit, an attribute import unit and an attribute export unit. The attribute creation unit is used to assign section attributes and material attribute parameters to the created elements. The attribute export unit is used to export the created attributes to an attribute file, which is subsequently transferred to the finite element analysis software together with the model file for subsequent finite element analysis. The attribute import unit is used to re-import the attribute file edited by the user into CATIA to update the attribute parameters of each structural element.

10. The aircraft structure design modeling system according to claim 1, characterized in that: It also includes an analysis and simulation module and a structural optimization design module. The analysis and simulation module is used to realize the generation of finite element meshes of aircraft structural parts, complete the loading of loads and perform solution calculations, and optimize corresponding parameters according to the calculation results. The structural optimization design module is used to complete the cross-sectional size optimization, geometric shape optimization and topology optimization of structural parts.

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