General parametric 3d geometric modeling method for grid-reinforced cylindrical shell structure with material properties

Abstract

In order to overcome the deficiency that the grid reinforced cylindrical shell structure created in the modeling analysis of the current grid reinforced cylindrical shell structure has a large difference with the actual structure, a universal parameterized three-dimensional geometric modeling method of the grid reinforced cylindrical shell structure containing material characteristics is provided.The reference coordinate system of the grid reinforced cylindrical shell structure is first created;secondly, the basic parameters required for constructing the grid reinforced cylindrical shell structure are determined, and the key parameters required for establishing the three-dimensional geometric model are solved;thirdly, based on the key parameters, the basic components such as the rib and the skin of the grid reinforced cylindrical shell structure are created through stretching, rotating and other methods;then, according to the position of each component in the grid reinforced cylindrical shell structure in the space coordinate system, the basic components are combined to establish the three-dimensional geometric model of the grid reinforced cylindrical shell structure;finally, the material properties of the skin, the rib and the weld are given, and the construction of the three-dimensional model of the grid reinforced cylindrical shell structure containing material characteristics is completed.

Description

Technical Field

[0001] This invention belongs to the field of geometric modeling of launch vehicle structures, and relates to a general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures. Background Technology

[0002] The mesh-stiffened shell structure mainly consists of two types of structural panels: skin and ribs. These panels are then welded together to form the shell sections. It is a common structural form for launch vehicles. Currently, most in-service and under-development launch vehicles use this structural form for critical load-bearing components such as interstage sections, fuel tanks, and fairings, accounting for more than 80% of the rocket body structural sections. Mesh-stiffened shell structures are subjected to internal pressure, bending moment, and axial force, with axial compression being the primary service condition and buckling instability being the main instability mode. To efficiently analyze typical failure modes such as local instability of ribs or skin, local plastic instability of materials, and overall instability of the stiffened structure, and to optimize mesh-stiffened shell structures to enhance their load-bearing capacity, it is usually necessary to establish a high-fidelity finite element model for analysis. As the foundation of finite element analysis, it is necessary to propose a general, fast, and high-precision parametric three-dimensional geometric modeling method for mesh-stiffened shell structures to improve the modeling efficiency of such structures.

[0003] The literature "Optimization Design of Mesh-Integrated Stiffened Storage Tank Cylindrical Shell Structure [J]. Journal of Nanjing University of Aeronautics and Astronautics, 2010" proposes a parametric modeling method for mesh-integrated stiffened storage tank cylindrical shell structures using Hypermesh as the parametric modeling development platform. However, this method does not consider the creation of structures such as welds and reinforcing borders in the stiffened areas of actual mesh-stiffened cylindrical shell structures, and can only consider mesh-stiffened cylindrical shell structures with an integer number of meshes, which differs significantly from actual mesh-stiffened cylindrical shell structures. Therefore, it is necessary to propose a more realistic and universal parametric 3D geometric modeling method for mesh-stiffened cylindrical shell structures. Summary of the Invention

[0004] To overcome the shortcomings of current methods for modeling and analyzing mesh-reinforced cylindrical shell structures, which often result in significant differences between the created mesh-reinforced cylindrical shell structure and the actual structure, this invention proposes a general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures that incorporates material properties.

[0005] The technical solution of this invention is:

[0006] A general parametric 3D geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties, characterized by the following steps:

[0007] Step 1: Create a reference coordinate system O-xyz to describe the relative positions of the components in the mesh-stiffened cylindrical shell structure;

[0008] Step 2: Determine the basic parameters required for parametric 3D geometric modeling of the mesh-reinforced cylindrical shell structure;

[0009] The basic parameters include overall structural parameters and local geometric parameters; the overall structural parameters include the length L0 of a single cylinder segment, the diameter D0 of a cylinder segment, and the number of cylinder segments S. s The number of spliced ​​wall panels in a single tube section, N W and weld type; local geometric parameters include stiffener height j d , Rib thickness j t , spacing of diagonal reinforcement b x Angle θ between diagonal and longitudinal reinforcement s weld width w w weld thickness w t and skin thickness S t ;

[0010] Step 3: Solve for the key parameters required for parametric 3D geometric modeling of the mesh-reinforced cylindrical shell structure based on the aforementioned basic parameters;

[0011] The key parameters include the longitudinal reinforcement spacing b. z Angular spacing θ of the diagonal rib circumferential array a Angular spacing θ of the longitudinal rib circumferential array b The lead S of the cylindrical helix for constructing the inclined ribs y The angle θ corresponding to the width of a single weld seam in the circumferential direction of the cylinder section. y The angle θ corresponding to the circumferential direction of a single mesh-reinforced region in the tube segment. z Circumferential offset angle θ o and axial offset grid size H o ;

[0012] Step 4: Based on the aforementioned basic and key parameters, establish the basic structural components for the ribs and skin;

[0013] Step 5: Based on the key parameters and the ribs and skin basic structural components, according to the position of each basic structural component in the mesh-reinforced cylindrical shell structure, combine the basic structural components to establish a three-dimensional geometric model of the mesh-reinforced cylindrical shell structure.

[0014] Step 6: Assign material properties to each component of the three-dimensional geometric model of the mesh-reinforced cylindrical shell structure established in Step 5.

[0015] Furthermore, in step 1, the reference coordinate system O-xyz has its origin O coinciding with the center of the circle on the lower end face of the three-dimensional model of the mesh-reinforced cylindrical shell structure, the xOy plane coinciding with the lower end face of the three-dimensional model of the mesh-reinforced cylindrical shell structure, the z-axis coinciding with the axis of the three-dimensional model of the mesh-reinforced cylindrical shell structure and pointing vertically upward, the x-axis pointing to the boundary of the first wall panel at the bottom layer of the three-dimensional model of the mesh-reinforced cylindrical shell structure, and the y-axis determined by the right-hand rule.

[0016] Furthermore, the key parameters in step 3 are calculated using the following formulas:

[0017]

[0018] When parameter R A ≤0.8×θ b hour:

[0019]

[0020] When parameter R A >0.8×θ b hour:

[0021]

[0022] Among them, R A =θ z %θ b %, is the modulo operator; Indicates the rounding up symbol;

[0023] When parameter R H ≤0.4×H c hour:

[0024]

[0025] When parameter R H >0.4×H c hour

[0026]

[0027] Among them, R H =(L0-w w )%(0.5×H c ), % is the modulo operator; H c This indicates the axial distance between the intersection points of adjacent diagonal bars on the same longitudinal bar.

[0028] Furthermore, step 4 specifically involves:

[0029] Step 4.1: Construct the diagonal reinforcement foundation components;

[0030] In the reference coordinate system O-xyz, with D0 as the diameter, S y As the lead, create a right-handed helix starting at (0,D0 / 2,0), and then intercept the path from 0 to L0-w in the z-direction. w The +z1 portion; based on the truncated portion, stretched j along the principal normal direction of the spiral. dLength, to obtain a right-hand helical surface as the base component of the positive diagonal rib; change the direction of the helix, and create a left-hand helical surface as the base component of the reverse diagonal rib in the same way; z1 is the margin;

[0031] Step 4.2: Construct longitudinal reinforcement foundation components;

[0032] In the reference coordinate system O-xyz, with (0,D0 / 2,0) as the starting point, (0,D0 / 2-j d Create a straight line segment with L0-w as the endpoint, and then stretch it along the positive z-axis. w A plane is obtained as the basic component for the longitudinal reinforcement;

[0033] Step 4.3: Establish the basic skin components;

[0034] Create a circle with O as the center and D0 as the diameter in the reference coordinate system O-xyz, and then stretch the length L0 along the positive z-axis to obtain the skin base component of a single cylinder segment.

[0035] The order of steps 4.1-4.3 can be interchanged arbitrarily.

[0036] Furthermore, step 5 specifically includes:

[0037] Step 5.1: Create the basic skinning structure;

[0038] Based on the skin base component created in step 4.3, S is respectively... s The skin base components are aligned along their axes and connected end to end along the top and bottom of the z-axis to form the skin base structure of the entire cylindrical section.

[0039] Step 5.2: Determine the location of the wall panels for the entire grid-reinforced cylindrical shell structure;

[0040] Based on the number of cylinder segments S s The number of wall panels and the type of weld in a single cylindrical section determine the location of the wall panels in the entire grid-reinforced cylindrical shell structure.

[0041] Step 5.3: Create the weld and skin structure;

[0042] Based on the wall panel positions defined in step 5.2, arbitrarily select one of the wall panels and create weld seams and skin structures for that wall panel;

[0043] Step 5.4: Create the border ribs;

[0044] Based on the weld and skin structure created in step 5.3, for the wall panel selected in step 5.3, arrange the border ribs of the mesh-reinforced area at the inner boundary of the weld;

[0045] Step 5.5: Establish a local coordinate system O1x1y1z1 to describe the position of the stiffeners in a single panel;

[0046] Step 5.6: Create the longitudinal reinforcement structure;

[0047] According to the angular interval θ of the longitudinal rib circumferential array b Determine the phase angle θ of the projection of the longitudinal reinforcement foundation component onto x1O1y1. zi θ b -θ o ,2θ b -θ o ,3θ b -θ o ,……,(n-1)·θ b -θ o ,n·θ b -θ o , n is a definite expression that satisfies n·θ b -θ o <θ z The largest integer under the given conditions;

[0048] The longitudinal reinforcement foundation components of the wall panel established in step 4.2 are arranged according to the phase angle θ. zi After deployment, symmetrical stretching j t Generate all longitudinal reinforcement bars;

[0049] Step 5.7: Create the diagonal reinforcement structure;

[0050] Determine the position of the lower endpoint of the initial positive diagonal reinforcement, which is offset downwards by H from the intersection of the left and lower boundaries of the mesh reinforcement area arranged in step 5.4. o θ deflection to the right o Location;

[0051] The foundation components of the positive inclined ribs established in step 4.1 are arranged at angular intervals θ in the circumferential array of the inclined ribs. a Let θ be the spacing and the angle between the x1O1y1 plane and the x1O1y1 plane. s After deployment, symmetrical stretching j t Generate all positive diagonal reinforcements;

[0052] The base components of the reverse diagonal reinforcement established in step 4.1 are arranged at angular intervals θ in the circumferential array of diagonal reinforcements. a The spacing is θ, with an angle of 180°-θ with the x1O1y1 plane. s After deployment, symmetrical stretching j t Generate all reverse diagonal reinforcements;

[0053] Remove all diagonal reinforcement bars that extend beyond the mesh-reinforced area;

[0054] Step 5.8: Create a mesh-reinforced cylindrical shell structure;

[0055] Based on the wall panel positions determined in step 5.2, repeat step 5.3 for each remaining wall panel to create the weld and skin structure of each wall panel. Then repeat steps 5.4-5.7 for each remaining wall panel to construct the frame rib structure, longitudinal rib structure and diagonal rib structure of each wall panel, thus completing the creation of the three-dimensional geometric model of the mesh-reinforced shell structure.

[0056] Furthermore, step 5.3 specifically includes:

[0057] Using the edge of the wall panel as the outer boundary of the weld, offset it inward by 0.5w. w The inner boundary of the weld is obtained; the area between the inner and outer boundaries is the weld area, and the wall panel area surrounded by the weld is the mesh reinforcement area;

[0058] Based on the outer surface of the skin base structure in the mesh-reinforced area and weld area, an S-shaped offset is set along the inner normal direction. t Generate skin structure;

[0059] Within the weld area, stretch the inner and outer surfaces of the skin by 0.5 (w) along the inner and outer normal directions of the skin's mid-surface, respectively. t -S t ), thus creating the weld structure.

[0060] Furthermore, in step 5.5, the local coordinate system O1x1y1z1 has its origin O1 at the center of the arc segment where the lower boundary of the mesh reinforcement region is located, the z1 axis is perpendicular to the plane where the lower boundary of the reinforcement region is located and points upwards, the x1 axis is from the origin O1 to the starting point of the arc segment where the lower boundary of the mesh reinforcement region is located, and the y1 axis is determined by the right-hand rule.

[0061] Furthermore, the material properties mentioned in step 6 include the skin's density ρ1, elastic modulus E1, Poisson's ratio ν1, and yield stress σ. s1 Ultimate stress σ b1 and ultimate strain ε u1 The density ρ2, elastic modulus E2, Poisson's ratio ν2, and yield stress σ of all reinforcing bars s2 Ultimate stress σ b2 and ultimate strain ε u2 and the reduction factor of weld material

[0062] The beneficial effects of this invention are:

[0063] 1. This invention first establishes a reference coordinate system for a mesh-reinforced shell structure; second, it determines the basic parameters required for constructing the mesh-reinforced shell structure and uses these parameters to solve for the key parameters needed to establish its three-dimensional geometric model; third, based on the key parameters, it creates basic components such as ribs and skin of the mesh-reinforced shell structure through methods such as stretching and rotation; then, according to the positions of each component in the spatial coordinate system within the mesh-reinforced shell structure, it combines the basic components to establish the three-dimensional geometric model of the mesh-reinforced shell structure; finally, it assigns material properties to the skin, ribs, and welds, completing the construction of the three-dimensional model of the mesh-reinforced shell structure with material properties. This invention solves the problem of difficult parametric three-dimensional geometric modeling of mesh-reinforced shell structures considering welds, borders, and other structures. Furthermore, based on set parameters, it optimizes the overall symmetry of the rib mesh in mesh-reinforced shell structures with non-integer mesh numbers, providing a fast and accurate method for constructing three-dimensional geometric models for the mechanical analysis of various mesh-reinforced shell structures.

[0064] 2. This invention can achieve rapid 3D modeling of mesh-reinforced cylindrical shell structures that are in line with engineering practice based on different parameters, avoiding the inconvenience caused by the cumbersome and complex 3D geometric modeling of mesh-reinforced cylindrical shell structures when performing load analysis on mesh-reinforced cylindrical shell structures with different parameters, thus improving modeling accuracy and efficiency. Attached Figure Description

[0065] Figure 1 It is the reference coordinate system for the grid-reinforced cylindrical shell structure.

[0066] Figure 2 This is a schematic diagram of the overall parameters of the grid-reinforced cylindrical shell structure, where (a) is the side view of the "cross" shaped weld model and (b) is the side view of the "T" shaped weld model.

[0067] Figure 3 This is a schematic diagram of local parameters of a mesh-reinforced cylindrical shell structure.

[0068] Figure 4 It is a component of the diagonal reinforcement foundation.

[0069] Figure 5 It is a longitudinal reinforcement foundation component.

[0070] Figure 6 It is a basic component of the skin.

[0071] Figure 7 It is the local coordinate system of the mesh-reinforced region.

[0072] Figure 8 It is a three-dimensional geometric model of a mesh-reinforced cylindrical shell structure established through parametric modeling. Detailed Implementation

[0073] This invention proposes a parametric 3D geometric modeling method for mesh-reinforced cylindrical shell structures. This method considers actual structural elements such as welds and borders, incorporates material properties, and optimizes the overall symmetry of the reinforced mesh based on set parameters. The method of this invention will be described in detail below with reference to the accompanying drawings.

[0074] The present invention proposes a general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties, comprising the following steps:

[0075] Step 1: Create a reference coordinate system to describe the relative positions of the components in the mesh-stiffened shell structure;

[0076] like Figure 1 As shown, a spatial rectangular coordinate system O-xyz is created with a point in space as the origin to describe the relative positions of the components (stiffening base structure components, skin base structure components, and wall panels) in the mesh-reinforced shell structure in three-dimensional space. The origin O coincides with the center of the circle on the lower end face of the mesh-reinforced shell structure 3D model; the xOy plane coincides with the lower end face of the mesh-reinforced shell structure 3D model; the z-axis direction coincides with the axis of the mesh-reinforced shell structure 3D model and is vertically upward; the x-axis direction points to the boundary of the first wall panel at the bottom of the mesh-reinforced shell structure 3D model; and the y-axis, x, and z axes form a right-handed rectangular coordinate system.

[0077] Step 2: Determine the basic parameters required for parametric 3D geometric modeling of the mesh-reinforced cylindrical shell structure;

[0078] The basic parameters required for parametric 3D geometric modeling of mesh-reinforced cylindrical shell structures mainly include overall structural parameters and local geometric parameters.

[0079] like Figure 2 As shown, the overall structural parameters are:

[0080] The length L0 of a single cylinder segment: the distance between the top plane of the cylinder segment and the bottom plane of the cylinder segment;

[0081] D0: The maximum chord length of the outer circular cross-section of the cylinder section;

[0082] Number of cylinder sections S s The number of axial frame segments spaced apart by welds;

[0083] Number of spliced ​​wall panels N W : Refers to the number of wall panels in a single cylinder section, separated by welds;

[0084] Weld type: The combination form of the wall panels between two adjacent cylinder sections, specifically the "cross" shaped weld and the "T" shaped weld.

[0085] like Figure 3 As shown, the local geometric parameters are:

[0086] Rib height j d : Radial height of the rib;

[0087] Rib thickness j t ;

[0088] Diagonal reinforcement spacing b x : The distance between the central symmetrical planes of two adjacent diagonal reinforcements after unfolding;

[0089] Angle θ between diagonal and longitudinal reinforcement s The angle between the central planes of symmetry of the diagonal and longitudinal reinforcement bars;

[0090] weld width w w ;

[0091] weld thickness w t ;

[0092] Skin thickness S t .

[0093] Step 3: Solve for key parameters in the parametric modeling of the mesh-stiffened cylindrical shell structure based on the basic parameters;

[0094] Key parameters include:

[0095] Longitudinal reinforcement spacing b z , which is the distance between the central symmetrical planes of two adjacent longitudinal reinforcements after unfolding;

[0096] Angular spacing θ of the inclined rib circumferential array a That is, the angular interval between the central symmetrical planes of two adjacent diagonal reinforcement bars;

[0097] Angular spacing θ of longitudinal rib circumferential array b That is, the angular interval between the central symmetrical planes of two adjacent longitudinal bars;

[0098] The lead S of the cylindrical helix for constructing the inclined rib y ;

[0099] The angle θ corresponding to the width of a single weld in the circumferential direction of the cylinder section y ;

[0100] Angle θ of a single mesh reinforced region z , refers to the circumferential angle corresponding to the grid-reinforced area on a single spliced ​​wall panel in a complete tube segment;

[0101] Circumferential offset angle θ o The radial angle offset used to optimize the symmetry of the stiffened mesh makes the force transmission more uniform and suppresses the maximum stress.

[0102] Axial offset grid size H o , represents the axial dimension offset used to optimize the symmetry of the stiffened mesh;

[0103] Each key parameter is calculated using the following formula:

[0104]

[0105] When parameter R A ≤0.8×θ b hour:

[0106]

[0107] When parameter R A >0.8×θ b hour:

[0108]

[0109] Among them, R A =θ z %θ b %, is the modulo operator; Indicates the rounding up symbol;

[0110] When parameter R H ≤0.4×H c hour:

[0111]

[0112] When parameter R H >0.4×H c hour

[0113]

[0114] Among them, R H =(L0-w w )%(0.5×H c ), % is the modulo operator; H c This indicates the axial distance between the intersection points of adjacent diagonal bars on the same longitudinal bar.

[0115] Step 4: Establish the basic structural components of ribs and skin based on the basic and key parameters;

[0116] Step 4.1: Construct the diagonal reinforcement foundation components;

[0117] In the reference coordinate system O-xyz, with D0 as the diameter, S y As the lead, create a right-handed helix starting at (0,D0 / 2,0), and then intercept the path from 0 to L0-w in the z-direction. w The +z1 portion (z1 is added here as a margin). Based on the truncated portion, j is stretched along the principal normal direction of the spiral. dThe length is used to obtain a right-hand helical surface as the basic component of the positive diagonal rib, such as... Figure 4 As shown. Change the direction of the helix and create a left-hand helical surface as the base component for the reverse-angled rib using the same method.

[0118] Step 4.2: Construct longitudinal reinforcement foundation components;

[0119] In the reference coordinate system O-xyz, with (0,D0 / 2,0) as the starting point, (0,D0 / 2-j d Create a straight line segment with L0-w as the endpoint, and then stretch it along the positive z-axis. w Obtain a plane as the basic component for the longitudinal reinforcement, such as Figure 5 As shown.

[0120] Step 4.3: Establish the basic skin components;

[0121] Create a circle centered at O ​​and with diameter D0 in the reference coordinate system O-xyz, then extrude it along the positive z-axis by a length L0 to obtain the skin base component for a single cylindrical segment, as shown below. Figure 6 As shown.

[0122] The order of steps 4.1-4.3 above can be interchanged arbitrarily.

[0123] Step 5: Based on the key parameters and the basic components established in Step 4, establish a three-dimensional geometric model of the mesh-reinforced cylindrical shell structure;

[0124] Step 5.1: Create the basic skinning structure;

[0125] Based on the skin base component created in step 4.3, S is respectively... s The skin base components are aligned along their axes and connected end-to-end along the top and bottom of the z-axis to form the skin base structure of the entire cylindrical section.

[0126] Step 5.2: Determine the location of the wall panels for the entire grid-reinforced cylindrical shell structure;

[0127] Step 5.1 has determined the position of each cylindrical segment. Since the number of wall panels in each segment is the same, determining the distribution of the wall panels in only one segment is sufficient to determine the wall panel distribution of the entire grid-reinforced cylindrical shell structure. For a single cylindrical segment, the position of each wall panel can be determined based on the number of wall panels. For multiple cylindrical segments, if the weld type is a "cross" weld, the wall panels between adjacent segments are aligned; if the weld type is a "T" weld, in two adjacent cylindrical segments, the boundary of the wall panel of one segment is aligned with the centerline of the wall panel of the other segment, such as... Figure 2 As shown. Therefore, based on the number of cylinder segments S s The number of wall panels and the type of weld in a single cylindrical section can determine the location of the wall panels in the entire grid-reinforced cylindrical shell structure.

[0128] Step 5.3: Based on the wall panel positions defined in Step 5.2, arbitrarily select one of the wall panels and create the weld and skin structure for that wall panel;

[0129] like Figure 3 As shown, the weld is located on the outer ring of the wall panel, used for the connection between two wall panels. The edge of the wall panel is taken as the outer boundary of the weld, and it is offset inwards by 0.5w. w The inner boundary of the weld is obtained. The area between the inner and outer boundaries is the weld area, and the wall panel area surrounded by the weld is the mesh-reinforced area. Based on the outer surface of the skin base structure of the mesh-reinforced area and the weld area, an offset S is set along the inner normal direction. t Generate the skin structure. Then, stretch the inner and outer surfaces of the skin within the weld area by 0.5 (w) along the inner and outer normal directions of the skin's mid-surface, respectively. t -S t ), thus creating the weld structure.

[0130] Step 5.4: Create the border rib structure;

[0131] Based on the weld structure of the wall panel created in step 5.3, for the wall panel selected in step 5.3, border ribs of the mesh-reinforced area are arranged at the inner boundary of the weld to increase strength. For example... Figure 3 As shown, based on the inner boundary of the weld, the normal tension j is applied to the inner surface of the skin. d Obtain the base surface of the frame ribs, and then extrude symmetrically about the base surface. t Generate border ribs.

[0132] Step 5.5: Establish a local coordinate system O1x1y1z1 to describe the position of the stiffeners in a single panel;

[0133] To facilitate describing the position of the stiffeners in a single panel, we create a local coordinate system O1-x1y1z1. For example... Figure 7 As shown, based on the mesh reinforcement area divided in step 5.3, the origin O1 is located at the center of the arc segment where the lower boundary of the mesh reinforcement area is located, the z1 axis is perpendicular to the plane where the lower boundary of the reinforcement area is located, the x1 axis is from the origin O1 to the starting point of the arc segment where the lower boundary of the mesh reinforcement area is located, and the y1 axis forms a right-handed coordinate system with the x1 and z1 axes.

[0134] Step 5.6: Create the longitudinal reinforcement structure;

[0135] The longitudinal ribs are on the inside of the skin, at intervals of θ in the mesh reinforcement area defined in step 5.3. b The arrangement can be based on the interval θ. b Determine the phase angle θ of the projection of the longitudinal reinforcement base component of the wall panel established in step 4.2 onto x1O1y1. zi θ b -θo ,2θ b -θ o ,3θ b -θ o ,……,(n-1)·θ b -θ o ,n·θ b -θ o Where n satisfies n·θ b -θ o <θ z Under the given conditions, the largest integer. Then, the longitudinal reinforcement foundation component established in step 4.2 is set with a phase angle θ. zi The layout is completed, and finally, all longitudinal reinforcement foundation components are symmetrically stretched. t Generate all longitudinal reinforcement bars.

[0136] Step 5.7: Create the diagonal reinforcement structure;

[0137] The diagonal ribs are arranged on the inner side of the skin. The base components of the positive diagonal ribs established in step 4.1 have the same angle with the x1O1y1 plane, which is θ. s First, determine that the lower endpoint of the initial positive inclined reinforcement is offset downwards by H from the intersection of the left and lower boundaries of the mesh reinforcement region defined in step 5.3. o θ deflection to the right o The position. Then, with θ a The spacing is θ, with the angle between it and the x1O1y1 plane being θ. s Arrange the foundation components of the positive diagonal reinforcement established in step 4.1 until they extend beyond the reinforced area of ​​the grid. Then, symmetrically stretch all the arranged foundation components of the positive diagonal reinforcement. t Generate all positive diagonal reinforcements.

[0138] All reverse diagonal ribs are created using the same method, but because the rotation direction is opposite, the angle between the base component of the reverse diagonal rib and the x1O1y1 plane is 180°-θ. s That is to say, with θ a The spacing is such that the angle between the x1O1y1 plane and the x1O1y1 plane is 180° - θ. s Arrange the foundation components of the reverse diagonal reinforcement established in step 4.1 until they extend beyond the reinforced area of ​​the grid. Then, symmetrically stretch all the arranged foundation components of the reverse diagonal reinforcement. t Generate all reverse diagonal reinforcements.

[0139] Finally, remove all diagonal reinforcements that extend beyond the mesh reinforcement area.

[0140] Step 5.8: Create a mesh-reinforced cylindrical shell structure;

[0141] Based on step 5.2, the positions of all wall panels in the entire structure are known. Since the structures of all cylindrical wall panels are generally identical (which ensures good load-bearing characteristics and facilitates efficient manufacturing), the methods for creating weld structures, skin structures, frame rib structures, longitudinal rib structures, and diagonal rib structures for all wall panels are the same. Therefore, based on the wall panel positions determined in step 5.2, step 5.3 can be repeated for each remaining wall panel to create the weld and skin structures for each panel. Then, steps 5.4-5.7 can be repeated for each remaining wall panel to construct the frame rib structure, longitudinal rib structure, and diagonal rib structure for each panel, thus completing the creation of the three-dimensional geometric model of the mesh-stiffened cylindrical shell structure.

[0142] Step 6: Assign material properties to the stiffeners, skin, and welds to facilitate the subsequent creation of a finite element model of the mesh-stiffened shell structure;

[0143] Assign material properties to each component of the three-dimensional geometric model of the mesh-stiffened cylindrical shell structure established in step 5, including the skin density ρ1, elastic modulus E1, Poisson's ratio ν1, and yield stress σ. s1 Ultimate stress σ b1 and ultimate strain ε u1 ; and the density ρ2, elastic modulus E2, Poisson's ratio ν2, and yield stress σ of all reinforcing bars (including longitudinal bars, diagonal bars, and edge bars). s2 Ultimate stress σ b2 and ultimate strain ε u2 ; reduction factor of weld material This refers to the percentage reduction of yield stress and ultimate stress in the weld seam based on the properties of the skin material.

[0144] Example:

[0145] The following describes the modeling of a three-dimensional geometric model of a mesh-reinforced cylindrical shell structure using the method of this invention:

[0146] Step 1: Create a reference coordinate system to describe the mesh-stiffened cylindrical shell structure;

[0147] like Figure 1 As shown, a spatial rectangular coordinate system O-xyz is created with a point in space as the origin, in order to describe the relative positions of each component in the mesh-stiffened cylindrical shell structure in three-dimensional space.

[0148] Step 2: Determine the basic parameters for parametric 3D geometric modeling of the mesh-reinforced cylindrical shell structure;

[0149] The overall structural parameters are:

[0150] The length of a single cylinder segment is L0 = 600 mm, the diameter of the cylinder segment is D0 = 2000 mm, and the number of cylinder segments is S. s =2, Number of spliced ​​wall panels N W= 4 pieces and the weld type is "T" shaped weld.

[0151] The local geometric parameters are:

[0152] Rib height j d =10mm, rib thickness j t =5mm, diagonal reinforcement spacing b x =100mm, angle θ between diagonal and longitudinal reinforcement s =55°, weld width w w =60mm, weld thickness w t =8mm and skin thickness S t =2.5mm.

[0153] Step 3: Solve for the key parameters in the parametric modeling of the mesh-stiffened cylindrical shell structure;

[0154] Based on the aforementioned formulas for solving each key parameter, the calculation results for the key parameters are as follows:

[0155] Longitudinal reinforcement spacing

[0156] Angular spacing of the diagonal rib circumferential array

[0157] Angular spacing θ of longitudinal rib circumferential array b =0.5 × 9.9892° = 4.9946°;

[0158] inclined cylindrical helical lead

[0159] The angle corresponding to the width of a single weld in the circumferential direction of the cylinder section

[0160] Angle θ of a single mesh reinforced region z =360° / 4 - 3.4377° = 86.5623°;

[0161] Circumferential offset angle

[0162] Axial offset grid size

[0163]

[0164] Step 4: Establish the basic structural components of ribs and skin based on the basic and key parameters;

[0165] Step 4.1: Construct the diagonal reinforcement foundation components;

[0166] In the coordinate system O-xyz, with D0 = 2000mm as the diameter, S y=4399.5337mm is the lead, and a right-handed helix is ​​created starting from (0,1000mm,0). Then, the z-axis from 0 to L0-w is intercepted. w The portion with +z1 = 800mm has an extra z1 = 260mm as a margin. Based on this, j is stretched along the principal normal direction of the helix. d =10mm in length, resulting in a right-hand helical surface as the base component for the positive diagonal rib, such as Figure 4 As shown. Then change the direction of the helix and create a left-hand helical surface as the base component for the reverse diagonal rib using the same method.

[0167] Step 4.2: Construct longitudinal reinforcement foundation components;

[0168] Create a straight line segment in the coordinate system O-xyz with (0,1000mm,0) as the starting point and (0,990mm,0) as the ending point, and then stretch it along the positive z-axis L0-w. w =540mm to obtain a plane as the basic component for longitudinal reinforcement, such as Figure 5 As shown.

[0169] Step 4.3: Establish the basic skin components;

[0170] Create a circle centered at O ​​with a diameter of D0 = 2000 mm in the coordinate system O-xyz, and then extrude it along the positive z-axis for a length of L0 = 600 mm to obtain the skin base component for a single cylinder segment, as shown below. Figure 6 As shown.

[0171] Step 5: Establish a three-dimensional geometric model of the mesh-reinforced cylindrical shell structure based on key parameters;

[0172] Step 5.1: Create the basic skinning structure;

[0173] Based on the skin base component created in step 4.3, S is respectively... s = Two skin base components are aligned on their axes and connected end to end along the top and bottom of the z-axis to form the skin base structure of the whole tube segment.

[0174] Step 5.2: Determine the location of the wall panels for the entire grid-reinforced cylindrical shell structure;

[0175] Step 5.1 has determined the position of each cylinder segment. Since the number of wall panels in each cylinder segment is the same, determining the distribution of the wall panels in only one cylinder segment is sufficient to determine the wall panel distribution of the entire grid-reinforced shell structure. For a single cylinder segment, the position of each wall panel can be determined based on the number of wall panels. Based on the "T" weld type, in two adjacent cylinder segments, the boundary of the wall panel of one segment is aligned with the centerline of the wall panel of the other segment, such as... Figure 2 As shown.

[0176] Step 5.3: Based on the wall panel positions defined in Step 5.2, arbitrarily select one of the wall panels and create the weld seam and skin structure for that wall panel;

[0177] like Figure 3 As shown, the weld is located on the outer ring of the wall panel, used for the connection between two wall panels. The edge of the wall panel is taken as the outer boundary of the weld, and it is offset inwards by 0.5w. w =30mm, thus obtaining the inner boundary of the weld. The area between the inner and outer boundaries is the weld area, and the wall panel area surrounded by the weld is the mesh-reinforced area. Based on the outer surface of the skin base structure of the mesh-reinforced area and the weld area, offset S along the inner normal direction. t =2.5mm to generate the skin structure. Then, stretch the inner and outer surfaces of the skin by 0.5 (w) along the inner and outer normals of the skin's mid-surface, respectively, within the weld area. t -S t =2.75mm, creating the weld structure.

[0178] Step 5.4 Create the border rib structure;

[0179] Based on the weld structure of each wall panel created in step 5.3, border ribs are arranged in the mesh-reinforced area at the inner boundary of the weld to increase strength. For example... Figure 3 As shown, based on the inner boundary of the weld, tension j is applied along the inner normal direction of the skin. d =10mm, obtain the base surface of the frame rib, and then stretch it symmetrically with its base surface. t =5mm to generate border ribs.

[0180] Step 5.5: Establish a local coordinate system O1x1y1z1 to describe the position of the stiffeners in a single panel;

[0181] After step 5.2, the positions of each wall panel in the entire structure are known. Since the structures of all the cylindrical wall panels are exactly the same, a local coordinate system O1-x1y1z1 is created to describe the structural composition of a single wall panel.

[0182] like Figure 7 As shown, based on the mesh reinforcement area divided in step 5.3, the origin O1 is located at the center of the arc segment where the lower boundary of the mesh reinforcement area is located. The z1 axis is perpendicular to the plane where the lower boundary of the reinforcement area is located and points upward. The x1 axis is from the origin O1 to the starting point of the arc segment where the lower boundary of the mesh reinforcement area is located. The y1 axis forms a right-handed coordinate system with the x1 and z1 axes.

[0183] Step 5.6: Create the longitudinal reinforcement structure;

[0184] The longitudinal reinforcement is on the inside of the skin, at intervals of θ in the mesh-reinforced area. b =4.9946° arrangement. The phase angle of the projection of the longitudinal reinforcement base component of each wall panel onto x1O1y1 is θ.zi =3.3243°, 8.3189°, 13.3135°, 18.3081°, 23.3027°, 28.2973°, 33.2919°, 38.2865°, 43.2811°, 48.2757°, 53.2703°, 58.5649°, 63.2595°, 68.2541°, 73.2487°, 78.2433°, 83.2379°, and then symmetrically stretched based on the longitudinal reinforcement foundation component. t =5mm to generate all longitudinal reinforcement.

[0185] Step 5.7: Create the diagonal reinforcement structure;

[0186] The diagonal ribs are arranged on the inside of the skin, and the base components of all positive diagonal ribs have the same angle with the x1O1y1 plane, which is θ. s =55°, the initial positive diagonal reinforcement lower endpoint is offset downwards by H from the intersection of the left and lower boundaries of the mesh reinforcement region. o = 35.1936mm, deflected to the right by θ o = 1.6703°. Then, with θ a With a spacing of 9.9892°, arrange positive diagonal ribs until they extend beyond the reinforced area of ​​the grid. Then, based on the foundation component of the positive diagonal ribs, symmetrically stretch j... t =5mm to generate all positive diagonal reinforcements.

[0187] Create all reverse diagonal ribs in the same way, but because the rotation direction is opposite, the base component of the reverse diagonal rib makes an angle of 180°-θ with the x1O1y1 plane. s =125°.

[0188] Finally, remove all diagonal reinforcements that extend beyond the mesh reinforcement area.

[0189] Step 5.8: Create a mesh-reinforced cylindrical shell structure;

[0190] After step 5.2, the positions of all wall panels in the entire structure are known. Since the structures of all cylindrical wall panels are generally identical, the methods for creating weld seams and skin structures, as well as the methods for creating longitudinal, diagonal, and edge stiffeners, are the same for all wall panels. Therefore, based on the wall panel structure divided in step 5.2, step 5.3 is repeated for each remaining wall panel to create the weld seams and skin structure for each panel; then, steps 5.4-5.7 are repeated for each remaining wall panel to construct the longitudinal, diagonal, and edge stiffeners for each panel, completing the creation of the three-dimensional geometric model of the mesh-stiffened cylindrical shell structure, as follows. Figure 8 As shown.

[0191] Step 6: Assign material properties to the stiffeners, skin, and welds to facilitate the subsequent creation of a finite element model of the mesh-stiffened shell structure;

[0192] Assign material properties to each component of the three-dimensional geometric model of the mesh-reinforced cylindrical shell structure established in step 5, including the density of the skin ρ1 = 2.7 × 10⁻⁶. -9 t / mm 3 Elastic modulus E1 = 70000 MPa, Poisson's ratio ν1 = 0.27, yield stress σ s1 =350MPa, ultimate stress σ b1 =440MPa and ultimate strain ε u1 =0.08; and the density ρ2 of all reinforcing bars (including longitudinal bars, diagonal bars, and edge bars) = 2.7 × 10 -9 t / mm 3 Elastic modulus E2 = 70000 MPa, Poisson's ratio ν2 = 0.27, yield stress σ s2 =350MPa, ultimate stress σ b2 =440MPa and ultimate strain ε u2 =0.08; Reduction factor for weld material

Claims

1. A general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties, characterized in that, Includes the following steps: Step 1: Create a reference coordinate system O-xyz to describe the relative positions of the components in the mesh-stiffened cylindrical shell structure; Step 2: Determine the basic parameters required for parametric 3D geometric modeling of the mesh-reinforced cylindrical shell structure; The basic parameters include overall structural parameters and local geometric parameters; the overall structural parameters include the length L0 of a single cylinder segment, the diameter D0 of a cylinder segment, and the number of cylinder segments S. s The number of spliced ​​wall panels in a single tube section, N W and weld type; local geometric parameters include stiffener height j d , Rib thickness j t , spacing of diagonal reinforcement b x Angle θ between diagonal and longitudinal reinforcement s weld width w w weld thickness w t and skin thickness S t ; Step 3: Solve for the key parameters required for parametric 3D geometric modeling of the mesh-reinforced cylindrical shell structure based on the aforementioned basic parameters; The key parameters include the longitudinal reinforcement spacing b. z Angular spacing θ of the diagonal rib circumferential array a Angular spacing θ of the longitudinal rib circumferential array b The lead S of the cylindrical helix for constructing the inclined ribs y The angle θ corresponding to the width of a single weld seam in the circumferential direction of the cylinder section. y The angle θ corresponding to the circumferential direction of a single mesh-reinforced region in the tube segment. z Circumferential offset angle θ o and axial offset grid size H o Among them, the circumferential offset angle θ o and axial offset grid size H o Calculate using the following formula: When parameter R A ≤0.8×θ b hour: When parameter R A >0.8×θ b hour: Among them, R A =θ z %θ b %, is the modulo operator; Indicates the rounding up symbol; When parameter R H ≤0.4×H c hour: When parameter R H >0.4×H c hour Among them, R H =(L0-w w )%(0.5×H c ), % is the modulo operator; H c This indicates the axial distance between the intersection points of adjacent diagonal bars on the same longitudinal reinforcement. ; Step 4: Based on the aforementioned basic and key parameters, establish the reinforcing bar foundation structure component and the skin foundation structure component of a single tube segment in the reference coordinate system O-xyz; the reinforcing bar foundation structure component includes the foundation component of the forward diagonal reinforcement, the foundation component of the reverse diagonal reinforcement, and the foundation component of the longitudinal reinforcement; Step 5: Based on the key parameters, the ribbed basic structural components and the skin basic structural components of a single cylindrical segment, and according to the position of each basic structural component in the mesh-reinforced cylindrical shell structure, combine the basic structural components to establish a three-dimensional geometric model of the mesh-reinforced cylindrical shell structure. Step 5.1: Create the basic skinning structure; Based on the skin base structure component created in step 4, S s The skin base structure components are aligned along their axes and connected end to end along the top and bottom of the z-axis to form the skin base structure of the entire cylindrical section. Step 5.2: Determine the location of the wall panels for the entire grid-reinforced cylindrical shell structure; Based on the number of cylinder segments S s The number of wall panels and the type of weld in a single cylindrical section determine the location of the wall panels in the entire grid-reinforced cylindrical shell structure. Step 5.3: Create the weld and skin structure; Based on the wall panel positions defined in step 5.2, arbitrarily select one of the wall panels and create weld seams and skin structures for that wall panel; Step 5.4: Create the border ribs; Based on the weld and skin structure created in step 5.3, for the wall panel selected in step 5.3, arrange the border ribs of the mesh-reinforced area at the inner boundary of the weld; Step 5.5: Establish a local coordinate system O1x1y1z1 to describe the position of the stiffeners in a single panel; Step 5.6: Create the longitudinal reinforcement structure; According to the angular interval θ of the longitudinal rib circumferential array b Determine the phase angle θ of the projection of the longitudinal reinforcement foundation component onto x1O1y1. zi θ b -θ o , 2θ b -θ o , 3θ b -θ o , ……, (n-1)·θ b -θ o , n·θ b -θ o , n is a definite expression that satisfies n·θ b -θ o <θ z The largest integer under the given conditions; The longitudinal reinforcement foundation components of the wall panel established in step 4 are arranged according to the phase angle θ. zi After deployment, symmetrical stretching j t Generate all longitudinal reinforcement bars; Step 5.7: Create the diagonal reinforcement structure; Determine the position of the lower endpoint of the initial positive diagonal reinforcement, which is offset downwards by H from the intersection of the left and lower boundaries of the mesh reinforcement area arranged in step 5.

4. o θ deflection to the right o Location; The foundation components of the positive diagonal ribs established in step 4 are arranged at angular intervals θ in the circumferential array of diagonal ribs. a Let θ be the spacing and the angle between the x1O1y1 plane and the x1O1y1 plane. s After deployment, symmetrical stretching j t Generate all positive diagonal reinforcements; The base components of the reverse diagonal ribs established in step 4 are arranged at angular intervals θ in the circumferential array of diagonal ribs. a The spacing is θ, with an angle of 180°-θ with the x1O1y1 plane. s After deployment, symmetrical stretching j t Generate all reverse diagonal reinforcements; Remove all diagonal reinforcement bars that extend beyond the mesh-reinforced area; Step 5.8: Create a mesh-reinforced cylindrical shell structure; Based on the wall panel positions determined in step 5.2, repeat step 5.3 for each remaining wall panel to create the weld and skin structure of each wall panel. Then repeat steps 5.4-5.7 for each remaining wall panel to construct the frame rib structure, longitudinal rib structure and diagonal rib structure of each wall panel, thus completing the creation of the three-dimensional geometric model of the mesh-reinforced cylindrical shell structure. Step 6: Assign material properties to each component of the 3D geometric model of the mesh-reinforced shell structure established in Step 5, including the skin's density ρ1, elastic modulus E1, Poisson's ratio ν1, and yield stress σ. s1 Ultimate stress σ b1 and ultimate strain ε u1 The density ρ2, elastic modulus E2, Poisson's ratio ν2, and yield stress σ of all reinforcing bars s2 Ultimate stress σ b2 and ultimate strain ε u2 And the reduction factor φ of the weld material.

2. The general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties according to claim 1, characterized in that: The reference coordinate system O-xyz mentioned in step 1 has its origin O coinciding with the center of the circle on the lower end face of the 3D model of the mesh-reinforced cylindrical shell structure. The xOy plane coincides with the lower end face of the 3D model of the mesh-reinforced cylindrical shell structure. The z-axis direction coincides with the axis of the 3D model of the mesh-reinforced cylindrical shell structure and is vertically upward. The x-axis direction points to the boundary of the first wall panel at the bottom layer of the 3D model of the mesh-reinforced cylindrical shell structure. The y-axis is determined by the right-hand rule.

3. The general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties according to claim 1, characterized in that: The remaining key parameters in step 3 are calculated using the following formulas: 。 4. The general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties according to any one of claims 1-3, characterized in that: Step 4 specifically involves: Step 4.1: Construct the diagonal reinforcement foundation components; In the reference coordinate system O-xyz, with D0 as the diameter, S y Create a right-handed helix with (0, D0 / 2, 0) as the lead and then intercept the path from 0 to L0-w in the z-direction. w The +z1 portion; based on the truncated portion, stretched j along the principal normal direction of the spiral. d Length, to obtain a right-hand helical surface as the base component of the positive diagonal rib; change the direction of the helix, and create a left-hand helical surface as the base component of the reverse diagonal rib in the same way; z1 is the margin; Step 4.2: Construct longitudinal reinforcement foundation components; In the reference coordinate system O-xyz, starting from (0, D0 / 2, 0), (0, D0 / 2-j d Create a straight line segment with the endpoint L0-w (0) as the endpoint, and then stretch it along the positive z-axis. w A plane is obtained as the basic component for the longitudinal reinforcement; Step 4.3: Establish the basic skin components; Create a circle with O as the center and D0 as the diameter in the reference coordinate system O-xyz, and then stretch the length L0 along the positive z-axis to obtain the skin base component of a single cylinder segment. The order of steps 4.1-4.3 can be interchanged arbitrarily.

5. The general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties according to claim 1, characterized in that: Step 5.3 specifically involves: Using the edge of the wall panel as the outer boundary of the weld, offset it inward by 0.5w. w The inner boundary of the weld is obtained; the area between the inner and outer boundaries is the weld area, and the wall panel area surrounded by the weld is the mesh reinforcement area; Based on the outer surface of the skin base structure in the mesh-reinforced area and weld area, an S-shaped offset is set along the inner normal direction. t Generate skin structure; Within the weld area, stretch the inner and outer surfaces of the skin by 0.5 (w) along the inner and outer normal directions of the skin's mid-surface, respectively. t -S t ), thus creating the weld structure.

6. The general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures containing material properties according to claim 1, characterized in that: In step 5.5, the local coordinate system O1x1y1z1 has its origin O1 at the center of the arc segment where the lower boundary of the mesh reinforcement region is located. The z1 axis is perpendicular to the plane where the lower boundary of the reinforcement region is located and points upward. The x1 axis points from the origin O1 to the starting point of the arc segment where the lower boundary of the mesh reinforcement region is located. The y1 axis is determined by the right-hand rule.

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