General parameterized three-dimensional geometric modeling method for grid reinforced cylindrical shell structure containing material characteristics

Abstract

In order to overcome the defect that a large difference exists between an established grid reinforced cylindrical shell structure and an actual structure during modeling analysis of an existing grid reinforced cylindrical shell structure, the invention provides a general parameterized three-dimensional geometric modeling method for a grid reinforced cylindrical shell structure containing material characteristics. The method comprises the following steps: firstly, creating a reference coordinate system of the grid reinforced cylindrical shell structure; secondly, basic parameters required for constructing the grid reinforced cylindrical shell structure are determined, and key parameters required for establishing a three-dimensional geometric model of the grid reinforced cylindrical shell structure are solved according to the basic parameters; thirdly, based on the key parameters, basic components such as ribs and skin of the grid reinforced cylindrical shell structure are created through methods such as stretching and rotating; 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 a three-dimensional geometric model of the grid reinforced cylindrical shell structure; and finally, endowing the skin, the ribs and the weld joints with respective material properties, and completing the construction of the three-dimensional model of the grid reinforced cylindrical shell structure containing the material properties.

Description

Technical Field

[0001] The invention belongs to the field related to geometric modeling of launch vehicle structures, and relates to a universal parameterized three-dimensional geometric modeling method for a grid-reinforced cylindrical shell structure. Background Art

[0002] The grid-reinforced cylindrical shell structure is mainly composed of two structures, skin and ribs, to form wall panels, which are then connected by welding to form welds to form barrel sections. It is a common structural form of launch vehicles. At present, most of the key load-bearing sections such as interstages, fuel tanks and fairings of launch vehicles in service and under development adopt this structural form, accounting for more than 80% of the rocket body structure compartment. The grid-reinforced cylindrical shell structure will be subjected to internal pressure, bending moment and axial force. Among them, the main service condition is axial pressure, and its main instability form is buckling instability. In order to efficiently analyze the typical failure forms such as local instability of ribs or skins, plastic instability of local materials and overall instability of reinforced structures, as well as to optimize the grid-reinforced cylindrical shell structure to enhance its bearing performance, it is usually necessary to establish a high-fidelity finite element model for analysis. As the basis of finite element analysis, it is necessary to propose a general, fast and high-precision parametric three-dimensional geometric modeling method for grid-reinforced cylindrical shell structures to improve the modeling efficiency of such structures.

[0003] The paper "Optimization Design of Mesh-Integrated Reinforced Tank Cylindrical Shell Structure [J]. Journal of Nanjing University of Aeronautics and Astronautics, 2010." uses Hypermesh as a parametric modeling development platform and proposes a parametric modeling method for mesh-integrated reinforced tank cylindrical shell structure. However, this method does not consider the creation of structures such as welds and reinforced frames in the actual mesh-reinforced cylindrical shell structure, and can only consider mesh-reinforced cylindrical shell structures with an integer number of grids, which is quite different from the actual mesh-reinforced cylindrical shell structure. Therefore, it is necessary to propose a general parametric three-dimensional geometric modeling method for mesh-reinforced cylindrical shell structures that is more in line with reality. Summary of the invention

[0004] In order to overcome the disadvantage that there is a large difference between the created grid reinforced cylindrical shell structure and the actual structure during the current modeling and analysis of the grid reinforced cylindrical shell structure, the present invention proposes a universal parametric three-dimensional geometric modeling method for the grid reinforced cylindrical shell structure including material properties.

[0005] The technical solution of the present invention is:

[0006] The general parametric 3D geometric modeling method of mesh-reinforced cylindrical shell structure with material properties is special in that it includes the following steps:

[0007] Step 1: Create a reference coordinate system O-xyz for describing the relative positions of components in the grid-reinforced cylindrical shell structure;

[0008] Step 2: Determine the basic parameters required for parametric 3D geometric modeling of 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 barrel section, the diameter D0 of the barrel section, the number S of barrel sections s 、Number of spliced ​​wall panels in a single cylinder section W and weld type; local geometric parameters include rib height j d , rib thickness j t , spacing of diagonal reinforcement b x , Angle between oblique reinforcement and longitudinal reinforcement θ s , weld width w w , weld thickness w t and skin thickness S t ;

[0010] Step 3: solving the key parameters required for parametric three-dimensional geometric modeling of the grid-reinforced cylindrical shell structure based on the basic parameters;

[0011] The key parameters include the longitudinal reinforcement spacing b z 、Angle spacing of oblique rib annular array θ a , the angular spacing of the longitudinal reinforcement annular array θ b , the lead S of the cylindrical helix for constructing the oblique reinforcement y 、The angle θ corresponding to the width of a single weld in the circumferential direction of the barrel y , the angle θ corresponding to the single grid reinforcement area in the circumferential direction of the barrel z 、Annular deviation angle θ o and the axial offset grid size H o ;

[0012] Step 4: Establishing basic structural components of ribs and skin based on the basic parameters and key parameters;

[0013] Step 5: Based on the key parameters and the ribs and skin basic structural components, and according to the positions of the basic structural components in the grid-reinforced cylindrical shell structure, the basic structural components are combined to establish a three-dimensional geometric model of the grid-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, the reference coordinate system O-xyz described in step 1 has its coordinate origin O coincident with the center of the lower end surface of the grid-reinforced cylindrical shell structure three-dimensional model, the xOy plane coincident with the lower end surface of the grid-reinforced cylindrical shell structure three-dimensional model, the z-axis direction coincident with the axis of the grid-reinforced cylindrical shell structure three-dimensional model and the positive direction is vertically upward, the x-axis direction points to the boundary of the first wall panel of the bottom layer of the grid-reinforced cylindrical shell structure three-dimensional model, and the y-axis is determined by the right-hand rule.

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

[0017]

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

[0019]

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

[0021]

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

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

[0024]

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

[0026]

[0027] Among them, R H =(L0-w w )%(0.5×H c ), % is the remainder operator; H c Indicates the axial distance between the intersections of adjacent oblique bars on the same longitudinal bar.

[0028] Furthermore, step 4 is specifically as follows:

[0029] Step 4.1: Create the diagonal rib foundation components;

[0030] In the reference coordinate system O-xyz, D0 is the diameter, S y is the lead, (0,D0 / 2,0) is the starting point to create a right-handed spiral, and then intercept 0 to L0-w in the z direction w +z1 part; based on the intercepted part, stretch j along the main normal direction of the helix dlength, and obtain a right-handed helical surface as the basic component of the forward oblique reinforcement; change the direction of the helix, and create a left-handed helical surface in the same way as the basic component of the reverse oblique reinforcement; z1 is the allowance;

[0031] Step 4.2: Establish the longitudinal reinforcement foundation components;

[0032] In the reference coordinate system O-xyz, (0,D0 / 2,0) is taken as the starting point, (0,D0 / 2-j d ,0) creates a straight line segment as the end point, and then stretches L0-w along the positive direction of the z axis w Get a plane as the base component of the longitudinal reinforcement;

[0033] Step 4.3: Create the skin base component;

[0034] In the reference coordinate system O-xyz, a circle with O as the center and D0 as the diameter is created, and then a length L0 is stretched along the positive direction of the z-axis to obtain the skin basic component of a single barrel segment;

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

[0036] Furthermore, step 5 is specifically as follows:

[0037] Step 5.1: Create the skin base structure;

[0038] Based on the skin base components created in step 4.3, s The axes of the skin basic components are aligned and connected end to end along the top and bottom ends of the z-axis to form the skin basic structure of the entire barrel section;

[0039] Step 5.2: Determine the wall panel position of the entire grid-reinforced cylindrical shell structure;

[0040] According to the number of tube sections S s , the number of panels and weld types in a single cylinder section, and determine the panel positions of the entire grid-reinforced cylinder shell structure;

[0041] Step 5.3: Create welds and skin structure;

[0042] According to the panel positions divided in step 5.2, select any panel and create a weld and skin structure for the panel;

[0043] Step 5.4: Create 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 frame ribs of the mesh reinforcement area on the inner boundary of the weld;

[0045] Step 5.5: Establish a local coordinate system O1x1y1z1 for describing the position of the ribs in a single panel;

[0046] Step 5.6: Create longitudinal reinforcement structure;

[0047] According to the angular spacing θ of the longitudinal reinforcement annular array b Determine the phase angle θ of the projection of the longitudinal reinforcement foundation component on x1O1y1 zi They are 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 the value that satisfies n·θ b -θ o <θ z The largest integer under the condition;

[0048] The longitudinal reinforcement foundation components of the wall panel established in step 4.2 are placed at a phase angle θ zi After laying, symmetrical stretching t Generate all longitudinal reinforcements;

[0049] Step 5.7: Create diagonal reinforcement structure;

[0050] Determine the position of the lower end point of the initial positive diagonal reinforcement, which is located at the intersection of the left and lower boundaries of the mesh reinforcement area arranged in step 5.4 and offset downward by H o , deviates to the right by θ o location;

[0051] The base component of the forward diagonal ribs established in step 4.1 is placed at an angle interval of θ in the diagonal rib annular array. a is the spacing, and the angle with the x1O1y1 plane is θ s After laying, symmetrical stretching t Generate all forward diagonal reinforcements;

[0052] The reverse diagonal rib foundation component created in step 4.1 is placed at an angle interval of θ in the diagonal rib annular array. a The spacing is 180°-θ with the x1O1y1 plane. s After laying, symmetrical stretching t Generate all reverse diagonal bars;

[0053] Cut off all diagonal reinforcement beyond the mesh reinforcement area;

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

[0055] According to the position of the wall panel determined in step 5.2, step 5.3 is repeated for each of the remaining wall panels to create the weld and skin structure of each wall panel, and then steps 5.4-5.7 are repeated for each of the remaining wall panels to construct the frame rib structure, longitudinal rib structure and diagonal rib structure of each wall panel to complete the creation of the three-dimensional geometric model of the grid-reinforced cylindrical shell structure.

[0056] Furthermore, step 5.3 is specifically as follows:

[0057] Take the edge of the wall panel as the outer boundary of the weld and 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 reinforcement area and the weld area, the inner normal offset S t Generate skin structure;

[0059] In the weld area, the inner and outer surfaces of the skin are stretched by 0.5 (w t -S t ) to create the weld structure.

[0060] Furthermore, in the local coordinate system O1x1y1z1 in step 5.5, its coordinate origin O1 is 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 direction 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 is determined by the right-hand rule.

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

[0062] The beneficial effects of the present invention are:

[0063] 1. The present invention first creates a reference coordinate system for a grid-reinforced cylindrical shell structure; secondly, determines the basic parameters required to construct the grid-reinforced cylindrical shell structure and solves the key parameters required to establish its three-dimensional geometric model; thirdly, based on the key parameters, creates basic components such as ribs and skins of the grid-reinforced cylindrical shell structure by stretching, rotating, etc.; then, according to the positions of each component in the grid-reinforced cylindrical shell structure in the spatial coordinate system, combines the basic components to establish a three-dimensional geometric model of the grid-reinforced cylindrical shell structure; finally, assigns the skin, ribs, and welds their own material properties, and completes the construction of a three-dimensional model of the grid-reinforced cylindrical shell structure containing material properties. The method of the present invention solves the problem of difficulty in parametric three-dimensional geometric modeling of a grid-reinforced cylindrical shell structure considering structures such as welds and frames, and optimizes the overall symmetry of the rib mesh of a grid-reinforced cylindrical shell structure with a non-integer number of meshes based on set parameters, providing a fast and accurate three-dimensional geometric model construction method for mechanical analysis of various types of grid-reinforced cylindrical shell structures.

[0064] 2. The present invention can realize rapid three-dimensional modeling of grid-reinforced cylindrical shell structures that is in line with engineering practice based on different parameters, avoiding the inconvenience caused by the cumbersome and complex three-dimensional geometric modeling of grid-reinforced cylindrical shell structures when performing load analysis on grid-reinforced cylindrical shell structures with different parameters, thereby improving modeling accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0067] Figure 3 It is a schematic diagram of local parameters of the grid-reinforced cylindrical shell structure.

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

[0069] Figure 5 It is the basic component of longitudinal reinforcement.

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

[0071] Figure 7 is the local coordinate system of the mesh reinforcement area.

[0072] Figure 8 It is a three-dimensional geometric model of a grid-reinforced cylindrical shell structure established through parametric modeling. DETAILED DESCRIPTION

[0073] The present invention proposes a parametric three-dimensional geometric modeling method for grid-reinforced cylindrical shell structures, which takes into account actual structures such as welds and frames, includes material properties, and optimizes the overall symmetry of the reinforced grid based on set parameters. The method of the present invention is described in detail below with reference to the accompanying drawings.

[0074] The general parameterized three-dimensional geometric modeling method of a grid-reinforced cylindrical shell structure including material properties proposed in the present invention comprises the following steps:

[0075] Step 1: Create a reference coordinate system for describing the relative positions of components in the grid-reinforced cylindrical shell structure;

[0076] like Figure 1 As shown, a spatial rectangular coordinate system O-xyz is created with a point in space as the coordinate origin, so as to describe the relative positions of the components (rib basic structure components, skin basic structure components and each wall panel) in the grid-reinforced cylindrical shell structure in three-dimensional space. Among them, the coordinate origin O coincides with the center of the circle of the lower end face of the three-dimensional model of the grid-reinforced cylindrical shell structure, the xOy plane coincides with the lower end face of the three-dimensional model of the grid-reinforced cylindrical shell structure, the z-axis direction coincides with the axis of the three-dimensional model of the grid-reinforced cylindrical shell structure and the positive direction is vertically upward, the x-axis direction points to the boundary of the first wall panel of the bottom layer of the three-dimensional model of the grid-reinforced cylindrical shell structure, and the y-axis, x-axis and z-axis form a right-handed rectangular coordinate system.

[0077] Step 2: Determine the basic parameters required for parametric 3D geometric modeling of 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] Length of a single barrel section L0: the distance between the top plane of the barrel section and the bottom plane of the barrel section;

[0081] Cylinder diameter D0: the maximum chord length of the outer circular section of the cylinder;

[0082] Number of barrel sections S s : The number of axial frame segments separated by welds;

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

[0084] Weld type: The wall panel combination between two adjacent cylinder sections. The specific forms include "cross" weld and "T" weld.

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

[0086] Rib height j d : radial height of rib;

[0087] Thickness of rib j t ;

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

[0089] Angle between oblique reinforcement and longitudinal reinforcement θ s : The angle between the oblique reinforcement and the central symmetry plane of the longitudinal reinforcement;

[0090] Weld width w w ;

[0091] Weld thickness w t ;

[0092] Skin thickness S t .

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

[0094] Key parameters include:

[0095] Spacing of longitudinal reinforcement b z , that is, the distance between the central symmetric planes of two adjacent longitudinal reinforcements after unfolding;

[0096] Angular spacing of the oblique rib annular array θ a , that is, the angular interval between the central symmetry planes of two adjacent oblique bars;

[0097] Angular spacing of longitudinal reinforcement annular array θ b , that is, the angle interval between the central symmetry planes of two adjacent longitudinal reinforcements;

[0098] The lead S of the cylindrical helix for constructing the oblique reinforcement y ;

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

[0100] Angle θ of a single mesh reinforcement area z , refers to the circumferential angle corresponding to the mesh reinforcement area on a single spliced ​​wall panel in a complete barrel section;

[0101] Circumferential deviation angle θ o , which is used to optimize the radial angle offset of the symmetry of the reinforcement grid, making the force transmission more uniform and suppressing the maximum stress;

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

[0103] The key parameters are calculated according to the following formula:

[0104]

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

[0106]

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

[0108]

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

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

[0111]

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

[0113]

[0114] Among them, R H =(L0-w w )%(0.5×H c ), % is the remainder operator; H c Indicates the axial distance between the intersections of adjacent oblique bars on the same longitudinal bar.

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

[0116] Step 4.1: Create the diagonal rib foundation components;

[0117] In the reference coordinate system O-xyz, D0 is the diameter, S y For the lead, (0, D0 / 2, 0) is used as the starting point to create a right-handed spiral, and then intercept 0 to L0-w in the z direction w +z1 part (here z1 is used as margin). Based on the intercepted part, stretch j along the main normal direction of the helix dlength, and a right helical surface is obtained as the basic component of the positive inclined rib, such as Figure 4 Change the helical direction and create a left-hand helical surface as the base part of the reverse rib in the same way.

[0118] Step 4.2: Establish the longitudinal reinforcement foundation components;

[0119] In the reference coordinate system O-xyz, (0,D0 / 2,0) is taken as the starting point, (0,D0 / 2-j d ,0) creates a straight line segment as the end point, and then stretches L0-w along the positive direction of the z axis w Get a plane as the base component of the longitudinal reinforcement, such as Figure 5 shown.

[0120] Step 4.3: Create the skin base component;

[0121] In the reference coordinate system O-xyz, create a circle with O as the center and D0 as the diameter, and then stretch the length L0 along the positive direction of the z-axis to obtain the skin basic component of a single barrel segment, such as Figure 6 shown.

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

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

[0124] Step 5.1: Create the skin base structure;

[0125] Based on the skin base components created in step 4.3, s The axes of the skin basic components are aligned and connected end to end along the top and bottom ends of the z-axis to form the skin basic structure of the entire barrel section.

[0126] Step 5.2: Determine the wall panel position of the entire grid-reinforced cylindrical shell structure;

[0127] Step 5.1 has determined the position of each cylinder section. Since the number of wall panels in each cylinder section is the same, it is only necessary to determine the distribution of the wall panels of one cylinder section to determine the wall panel distribution of the entire grid-reinforced cylinder shell structure. For a single cylinder section, the position of each wall panel can be determined based on the number of wall panels. For multiple cylinder sections, if the weld type is a "cross" weld, the wall panels between adjacent cylinder sections are aligned; if the weld type is a "T" weld, in two adjacent cylinder sections, the boundary of the wall panel of one cylinder section is aligned with the center line of the wall panel of the other cylinder section, such as Figure 2 Therefore, according to the number of barrel sections S s The position of the wall panels of the entire grid-reinforced shell structure can be determined by the number of wall panels and the type of welds in a single cylinder segment.

[0128] Step 5.3: According to the panel positions divided in step 5.2, select any panel and create a weld and skin structure for the panel;

[0129] like Figure 3 As shown in the figure, the weld is located on the outer circle of the wall panel and is used to connect two wall panels. The edge of the wall panel is used as the outer boundary of the weld and is offset 0.5w inward. w , and the inner boundary of the weld is obtained. The area between the inner and outer boundaries is the weld area, and the panel area surrounded by the weld is the mesh reinforcement area. Based on the outer surface of the skin foundation structure in the mesh reinforcement area and the weld area, the inner normal offset S t Generate the skin structure. Then, the inner and outer surfaces of the skin in the weld area are stretched by 0.5 (w t -S t ) to create the weld structure.

[0130] Step 5.4: Create the frame 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, arrange the frame ribs of the mesh reinforcement area on the inner boundary of the weld to increase the strength. Figure 3 As shown, based on the inner boundary of the weld, the normal stretching j is applied to the inner surface of the skin. d , get the base surface of the frame ribs, and then stretch symmetrically with the base surface t Generate border ribs.

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

[0133] In order to conveniently describe the position of the ribs in a single panel, we create a local coordinate system O1-x1y1z1. Figure 7 As shown, according to the mesh reinforcement area divided in step 5.3, the coordinate origin O1 is 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 direction 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 longitudinal reinforcement structure;

[0135] The longitudinal reinforcement is located on the inner side of the skin, in the mesh reinforcement area divided in step 5.3, with an interval of θ b Arrangement can be based on the interval θ b Determine the phase angle θ of the projection of the longitudinal reinforcement foundation component of the wall panel established in step 4.2 on x1O1y1 zi They are θ b -θo ,2θ b -θ o ,3θ b -θ o ,……,(n-1)·θ b -θ o ,n·θ b -θ o ; where n is a value that satisfies n·θ b -θ o <θ z Then, the longitudinal reinforcement foundation component established in step 4.2 is converted into the largest integer under the condition. zi Lay out, and finally stretch all the laid longitudinal reinforcement foundation components symmetrically t Generate all longitudinal reinforcement.

[0136] Step 5.7: Create diagonal reinforcement structure;

[0137] The diagonal ribs are arranged on the inner side of the skin. The angle between the base component of the positive diagonal ribs established in step 4.1 and the x1O1y1 plane is the same and is θ. s ; First, determine that the lower end point of the initial positive diagonal reinforcement is at the intersection of the left and lower boundaries of the mesh reinforcement area divided in step 5.3 and offset downward by H o , deviates to the right by θ o The position of a is the spacing, and the angle with the x1O1y1 plane is θ s Arrange the foundation components of the forward diagonal reinforcement established in step 4.1 until they exceed the mesh reinforcement area. Then, stretch the foundation components of the forward diagonal reinforcement symmetrically. t , generate all forward diagonal reinforcements.

[0138] Create all reverse diagonal ribs in the same way, but because the rotation direction is opposite, the angle between the reverse diagonal rib base component and the x1O1y1 plane is 180°-θ s That is, with θ a is the spacing, with an angle of 180°-θ with the x1O1y1 plane s Arrange the reverse diagonal reinforcement base components created in step 4.1 until they exceed the mesh reinforcement area. Then, stretch the reverse diagonal reinforcement base components symmetrically. t , generate all reverse diagonal bars.

[0139] Finally, trim away any diagonal reinforcement that extends beyond the mesh reinforcement area.

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

[0141] Based on step 5.2, the positions of the various wall panels of the entire structure can be known. Since the structures of all the wall panels of the cylinder section are generally exactly the same (the load-bearing characteristics are good at this time, and it is convenient for efficient manufacturing), the method of creating the weld structure, skin structure, frame rib structure, longitudinal rib structure and diagonal rib structure for all wall panels is the same. Therefore, according to the wall panel position determined in step 5.2, step 5.3 can be repeated for each of the remaining wall panels to create the weld and skin structure of each wall panel, and then steps 5.4-5.7 can be repeated for each of the remaining wall panels to construct the frame rib structure, longitudinal rib structure and diagonal rib structure of each wall panel, and complete the creation of the three-dimensional geometric model of the grid-reinforced cylindrical shell structure.

[0142] Step 6: Assign material properties to the ribs, skins, and welds to facilitate the subsequent establishment of a finite element model of the grid-reinforced cylindrical shell structure;

[0143] Assign material properties of each component to the three-dimensional geometric model of the grid-reinforced shell structure established in step 5, including the density ρ1, elastic modulus E1, Poisson's ratio ν1, yield stress σ s1 , ultimate stress σ b1 and the ultimate strain ε u1 ; and the density ρ2, elastic modulus E2, Poisson's ratio ν2, yield stress σ of all reinforcements (including longitudinal reinforcement, oblique reinforcement and border reinforcement) s2 , ultimate stress σ b2 and the ultimate strain ε u2 ; Reduction factor of weld material That is, the percentage by which the weld reduces the yield stress and ultimate stress based on the properties of the skin material.

[0144] Example:

[0145] The method of the present invention is used to model a three-dimensional geometric model of a grid-reinforced cylindrical shell structure:

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

[0147] like Figure 1 As shown in the figure, a spatial rectangular coordinate system O-xyz is created with a point in space as the coordinate origin to describe the relative positions of various components in the grid-reinforced cylindrical shell structure in three-dimensional space.

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

[0149] The overall structural parameters are:

[0150] The length of a single barrel section is L0 = 600 mm, the diameter of the barrel section is D0 = 2000 mm, and the number of barrel sections is S s =2, number of spliced ​​wall panels N W= 4 pieces and the weld type is "T" 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 between oblique reinforcement and longitudinal reinforcement θ s =55°, weld width w w =60mm, weld thickness w t =8mm and skin thickness S t =2.5mm.

[0153] Step 3: Solve the key parameters in the parametric modeling of the grid-reinforced cylindrical shell structure;

[0154] According to the solution formulas of the above key parameters, the calculation results of the key parameters are:

[0155] Spacing of longitudinal reinforcement

[0156] Angular spacing of the oblique rib annular array

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

[0158] Lead of cylindrical helix with inclined ribs

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

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

[0161] Circumferential deviation angle

[0162] Axial offset grid size

[0163]

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

[0165] Step 4.1: Create the diagonal rib foundation components;

[0166] In the coordinate system O-xyz, with D0 = 2000 mm as the diameter, S y=4399.5337mm is the lead, (0,1000mm,0) is the starting point to create a right-handed spiral, and then intercept the z direction from 0 to L0-w w +z1=800mm, here there is an extra z1=260mm as a margin. Based on this, stretch j along the main normal direction of the helix d = 10mm in length, a right-hand spiral surface is obtained as the basic component of the positive inclined rib, such as Figure 4 Then change the direction of the helix and use the same method to create a left-hand helical surface as the base part for the reverse bevel ribs.

[0167] Step 4.2: Establish the longitudinal reinforcement foundation components;

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

[0169] Step 4.3: Create the skin base component;

[0170] In the coordinate system O-xyz, create a circle with O as the center and D0 = 2000mm as the diameter, and then stretch L0 = 600mm along the positive z-axis to obtain the skin basic component of a single barrel segment, such as Figure 6 shown.

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

[0172] Step 5.1: Create the skin base structure;

[0173] Based on the skin base components created in step 4.3, s =The axes of the two skin basic components are aligned and connected end to end along the top and bottom ends of the z-axis to form the skin basic structure of the entire barrel section.

[0174] Step 5.2: Determine the wall panel position of the entire grid-reinforced cylindrical shell structure;

[0175] Step 5.1 has determined the position of each cylinder section. Since the number of wall panels in each cylinder section is the same, it is only necessary to determine the distribution of the wall panels of one cylinder section to determine the wall panel distribution of the entire grid-reinforced cylinder shell structure. For a single cylinder section, the position of each wall panel can be determined based on the number of wall panels. According to the "T"-shaped weld type, in two adjacent cylinder sections, the boundary of the wall panel of one cylinder section is aligned with the center line of the wall panel of the other cylinder section, such as Figure 2 shown.

[0176] Step 5.3: According to the panel positions divided in step 5.2, select any panel and create a weld and skin structure for the panel;

[0177] like Figure 3 As shown in the figure, the weld is located on the outer circle of the wall panel and is used to connect two wall panels. The edge of the wall panel is used as the outer boundary of the weld and is offset 0.5w inward. w =30mm, and 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 foundation structure in the mesh reinforcement area and the weld area, the inner normal offset S t =2.5mm to generate the skin structure. Then, the inner and outer surfaces of the skin in the weld area are stretched by 0.5 (w t -S t )=2.75mm, creating the weld structure.

[0178] Step 5.4 Create the frame rib structure;

[0179] Based on the weld structure of each wall panel created in step 5.3, arrange the frame ribs of the mesh reinforcement area on the inner boundary of the weld to increase the strength. Figure 3 As shown, based on the inner boundary of the weld, the normal direction of the skin is stretched d =10mm, get the base surface of the frame ribs, and then stretch 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 ribs in a single panel;

[0181] After step 5.2, the positions of all the wall panels of the entire structure are known. Since the structures of all the barrel section 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, according to the mesh reinforcement area divided in step 5.3, the coordinate origin O1 is 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 direction 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.

[0183] Step 5.6: Create longitudinal reinforcement structure;

[0184] The longitudinal reinforcement is on the inner side of the skin, at intervals of θ in the mesh reinforcement area. b =4.9946°. The phase angle of the projection of the longitudinal reinforcement foundation component of each wall panel on x1O1y1 is θzi =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 stretch based on the longitudinal reinforcement foundation components t =5mm to generate all longitudinal reinforcements.

[0185] Step 5.7: Create diagonal reinforcement structure;

[0186] The oblique ribs are arranged on the inner side of the skin, and the angles between the base components of all positive oblique ribs and the x1O1y1 plane are the same and are all θ s =55°, the initial positive oblique reinforcement lower end point is the intersection of the left boundary and the lower boundary of the mesh reinforcement area, offset downward by H o =35.1936mm, deviated to the right by θ o =1.6703°. Then, with θ a = 9.9892° as the spacing, arrange the positive diagonal reinforcement until it exceeds the grid reinforcement area. Then, based on the basic components of the positive diagonal reinforcement, symmetrically stretch j t =5mm generates all positive diagonal reinforcements.

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

[0188] Finally, trim away any diagonal reinforcement that extends beyond the mesh reinforcement area.

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

[0190] After step 5.2, the positions of all wall panels of the entire structure are known. Since the structures of all cylinder wall panels are generally exactly the same, the methods for creating welds and skin structures for all wall panels and the methods for creating longitudinal, oblique and frame ribs are the same. Therefore, according to the wall panel structure divided in step 5.2, step 5.3 is repeated for each of the remaining wall panels to create the welds and skin structures of each wall panel; then steps 5.4-5.7 are repeated for each of the remaining wall panels to construct the longitudinal, oblique and frame ribs of each wall panel, completing the creation of the three-dimensional geometric model of the grid-reinforced cylindrical shell structure, as shown in the figure. Figure 8 shown.

[0191] Step 6: Assign material properties to the ribs, skins, and welds to facilitate the subsequent establishment of a finite element model of the grid-reinforced cylindrical shell structure;

[0192] Assign material properties of each component to the three-dimensional geometric model of the grid-reinforced cylindrical shell structure established in step 5, including the density of the skin ρ1 = 2.7 × 10 -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 of all ribs (including longitudinal ribs, oblique ribs and border ribs) is ρ2 = 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 of weld material

Claims

1. A general parametric 3D geometric modeling method for mesh-reinforced cylindrical shell structures with material properties, characterized in that: The following steps are involved: Step 1: Create a reference coordinate system O-xyz for describing the relative positions of components in the grid-reinforced cylindrical shell structure; Step 2: Determine the basic parameters required for parametric 3D geometric modeling of 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 barrel section, the diameter D0 of the barrel section, the number S of barrel sections s 、Number of spliced ​​wall panels in a single cylinder section W and weld type; local geometric parameters include rib height j d , rib thickness j t , spacing of diagonal reinforcement b x , Angle between oblique reinforcement and longitudinal reinforcement θ s , weld width w w , weld thickness w t and skin thickness S t ; Step 3: solving the key parameters required for parametric three-dimensional geometric modeling of the grid-reinforced cylindrical shell structure based on the basic parameters; The key parameters include the longitudinal reinforcement spacing b z 、Angle spacing of oblique rib annular array θ a , the angular spacing of the longitudinal reinforcement annular array θ b , the lead S of the cylindrical helix for constructing the oblique reinforcement y 、The angle θ corresponding to the width of a single weld in the circumferential direction of the barrel y , the angle θ corresponding to the single grid reinforcement area in the circumferential direction of the barrel z 、Annular deviation angle θ o and the axial offset grid size H o ; Step 4: Establishing basic structural components of ribs and skin based on the basic parameters and key parameters; Step 5: Based on the key parameters and the ribs and skin basic structural components, and according to the positions of the basic structural components in the grid-reinforced cylindrical shell structure, the basic structural components are combined to establish a three-dimensional geometric model of the grid-reinforced cylindrical shell structure; 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.

2. The universal parameterized three-dimensional geometric modeling method of a grid-reinforced cylindrical shell structure with material properties according to claim 1 is characterized in that: The reference coordinate system O-xyz described in step 1 has its coordinate origin O coincident with the center of the lower end face of the mesh reinforced cylindrical shell structure three-dimensional model, the xOy plane coincident with the lower end face of the mesh reinforced cylindrical shell structure three-dimensional model, the z-axis direction coincident with the axis of the mesh reinforced cylindrical shell structure three-dimensional model and the positive direction is vertically upward, the x-axis direction points to the boundary of the first wall panel of the bottom layer of the mesh reinforced cylindrical shell structure three-dimensional model, and the y-axis is determined by the right-hand rule.

3. The universal parameterized three-dimensional geometric modeling method of grid-reinforced cylindrical shell structure with material properties according to claim 1 is characterized by: The key parameters in step 3 are calculated using the following formula: When the parameter R A ≤0.8×θ b hour: When the parameter R A >0.8×θ b hour: Among them, R A =θ z %θ b , % is the remainder operator; Indicates the rounding up symbol; When the parameter R H ≤0.4×H c hour: When the parameter R H >0.4×H c hour Among them, R H =(L0-w w )%(0.5×H c ), % is the remainder operator; H c Indicates the axial distance between the intersections of adjacent oblique bars on the same longitudinal bar.

4. The universal parameterized three-dimensional geometric modeling method of a grid-reinforced cylindrical shell structure with material properties according to any one of claims 1 to 3, characterized in that: Step 4 is as follows: Step 4.1: Create the diagonal rib foundation components; In the reference coordinate system O-xyz, D0 is the diameter, S y is the lead, (0,D0 / 2,0) is the starting point to create a right-handed spiral, and then intercept 0 to L0-w in the z direction w +z1 part; based on the intercepted part, stretch j along the main normal direction of the helix d length, and obtain a right-handed helical surface as the basic component of the forward oblique reinforcement; change the direction of the helix, and create a left-handed helical surface in the same way as the basic component of the reverse oblique reinforcement; z1 is the allowance; Step 4.2: Establish the longitudinal reinforcement foundation components; In the reference coordinate system O-xyz, (0,D0 / 2,0) is taken as the starting point, (0,D0 / 2-j d ,0) creates a straight line segment as the end point, and then stretches L0-w along the positive direction of the z axis w Get a plane as the base component of the longitudinal reinforcement; Step 4.3: Create the skin base component; In the reference coordinate system O-xyz, a circle with O as the center and D0 as the diameter is created, and then a length L0 is stretched along the positive direction of the z-axis to obtain the skin basic component of a single barrel segment; The order of steps 4.1-4.3 can be interchanged arbitrarily.

5. The universal parameterized three-dimensional geometric modeling method of a grid-reinforced cylindrical shell structure with material properties according to claim 4 is characterized in that: Step 5 is as follows: Step 5.1: Create the skin base structure; Based on the skin base components created in step 4.3, s The axes of the skin basic components are aligned and connected end to end along the top and bottom ends of the z-axis to form the skin basic structure of the entire barrel section; Step 5.2: Determine the wall panel position of the entire grid-reinforced cylindrical shell structure; According to the number of tube sections S s , the number of panels and weld types in a single cylinder section, and determine the panel positions of the entire grid-reinforced cylinder shell structure; Step 5.3: Create welds and skin structure; According to the panel positions divided in step 5.2, select any panel and create a weld and skin structure for the panel; Step 5.4: Create 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 frame ribs of the mesh reinforcement area on the inner boundary of the weld; Step 5.5: Establish a local coordinate system O1x1y1z1 for describing the position of the ribs in a single panel; Step 5.6: Create longitudinal reinforcement structure; According to the angular spacing θ of the longitudinal reinforcement annular array b Determine the phase angle θ of the projection of the longitudinal reinforcement foundation component on x1O1y1 zi They are 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 the value that satisfies n·θ b -θ o <θ z The largest integer under the condition; The longitudinal reinforcement foundation components of the wall panel established in step 4.2 are placed at a phase angle θ zi After laying, symmetrical stretching t Generate all longitudinal reinforcements; Step 5.7: Create diagonal reinforcement structure; Determine the position of the lower end point of the initial positive diagonal reinforcement, which is located at the intersection of the left and lower boundaries of the mesh reinforcement area arranged in step 5.4 and offset downward by H o , deviates to the right by θ o location; The base component of the forward diagonal ribs established in step 4.1 is placed at an angle interval of θ in the diagonal rib annular array. a is the spacing, and the angle with the x1O1y1 plane is θ s After laying, symmetrical stretching t Generate all forward diagonal reinforcements; The reverse diagonal rib foundation component created in step 4.1 is placed at an angle interval of θ in the diagonal rib annular array. a The spacing is 180°-θ with the x1O1y1 plane. s After laying, symmetrical stretching t Generate all reverse diagonal bars; Cut off all diagonal reinforcement beyond the mesh reinforcement area; Step 5.8: Create a grid-reinforced cylindrical shell structure; According to the position of the wall panel determined in step 5.2, step 5.3 is repeated for each of the remaining wall panels to create the weld and skin structure of each wall panel, and then steps 5.4-5.7 are repeated for each of the remaining wall panels to construct the frame rib structure, longitudinal rib structure and diagonal rib structure of each wall panel to complete the creation of the three-dimensional geometric model of the grid-reinforced cylindrical shell structure.

6. The universal parameterized three-dimensional geometric modeling method of grid-reinforced cylindrical shell structure with material properties according to claim 5 is characterized in that: Step 5.3 is as follows: Take the edge of the wall panel as the outer boundary of the weld and 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 reinforcement area and the weld area, the inner normal offset S t Generate skin structure; In the weld area, the inner and outer surfaces of the skin are stretched by 0.5 (w t -S t ) to create the weld structure.

7. The universal parameterized three-dimensional geometric modeling method of a grid-reinforced cylindrical shell structure with material properties according to claim 6 is characterized in that: The local coordinate system O1x1y1z1 in step 5.5 has its origin O1 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 direction 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 is determined by the right-hand rule.

8. The universal parameterized three-dimensional geometric modeling method of a grid-reinforced cylindrical shell structure with material properties according to claim 7 is characterized in that: The material properties described in step 6 include the skin's density ρ1, elastic modulus E1, Poisson's ratio ν1, yield stress σ s1 , ultimate stress σ b1 and the ultimate strain ε u1 , the density ρ2, elastic modulus E2, Poisson's ratio ν2, yield stress σ of all ribs s2 , ultimate stress σ b2 and the ultimate strain ε u2 , and the reduction factor of the weld material

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