Six-node equal-truss multi-stage lattice barrel shell structure and preparation method thereof

Abstract

The invention discloses a six-node equal-truss multi-stage lattice barrel shell structure and a preparation method thereof, belongs to the field of barrel structure design, and can show better mechanical properties under axial compression load. The structure is composed of a shell and an end flange, wherein the shell is formed by annularly and axially arraying six-node equal-truss unit cells; the six-node equal-truss unit cells are composed of longitudinal bars and spiral bars; the longitudinal ribs extend in the generatrix direction of the shell, the spiral ribs are annularly arrayed in the unit cells according to a certain angle, then the formed unit cells are annularly arrayed along the shell, the end flanges are connected with the end dot matrix rod pieces, and the problem of end stress concentration can be well solved. The six-node equal-truss lattice barrel shell is uniform in stress, good in product stability and short in manufacturing time, the defects that a traditional metal structure needs to be cut, welding is tedious, and stress is concentrated are overcome, and design and application of the lattice barrel shell under complex working conditions are facilitated.

Description

Technical Field

[0001] The invention belongs to the field of cylinder structures, and in particular relates to a six-node equal-truss multi-level lattice cylinder shell structure and a preparation method thereof. Background Art

[0002] The lattice cylindrical shell structure has broad application prospects in aerospace satellite bearing cylinders, aircraft fuselages, high-speed rail bodies, shipbuilding and civil engineering due to its light weight, high strength and large porosity. At present, the pure lattice shell design is mainly in the form of pyramid and grid, and its axial bending stiffness is weak, and increasing its bending stiffness will inevitably increase its mass.

[0003] The unit cell structure of the six-node equal truss shell is a shell with a high degree of discreteness. After the axial and circumferential arrays, a multi-level lattice shell structure is formed, which further improves its mechanical properties such as pressure bearing, bending resistance and torsion resistance. At present, the six-node equal truss structure is mainly based on carbon fiber winding, which leads to its unstable mechanical properties. Even the six-node lattice truss shell has not been studied yet. Summary of the invention

[0004] The present invention provides a six-node equal-truss multi-level lattice cylindrical shell structure and a preparation method thereof. The six-node equal-truss cells are arrayed to form a multi-level cylindrical shell structure, which further improves the bearing capacity of the structure while ensuring the porosity.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A six-node equal-truss multi-stage lattice cylindrical shell structure, which is composed of a shell and end flanges formed by annular and axial arrays of six-node equal-truss unit cells;

[0007] The six-node equal truss unit cell is composed of longitudinal reinforcement and spiral reinforcement. The longitudinal reinforcement is arranged at intervals of 60° along the central angle of the circle, with a total of 6 reinforcements. The spiral reinforcement forms a certain angle with the horizontal plane and is arranged at intervals of 60° along the circumferential direction, with a total of 12 reinforcements. The longitudinal reinforcement and the spiral reinforcement are both round straight rods, and the radius of the longitudinal reinforcement is consistent with that of the spiral reinforcement. The angle θ between the spiral reinforcement and the horizontal plane is 0° to 90°.

[0008] The six-node equal truss unit cells are arrayed in a circumferential direction at a circumferential angle of 3° to 12°, and are arrayed in the direction of the shell generatrix. The number of unit cells in the circumferential array is N=2π / α, where α is the circumferential angle. The structural stiffness is adjusted by changing the radius of the longitudinal reinforcement and the spiral reinforcement, the inclination angle of the spiral reinforcement, the thickness of the cylindrical shell and other parameters. The circumferential array is connected by spiral reinforcement, and the array in the direction of the shell generatrix is ​​connected by longitudinal reinforcement. The end flange is connected to the end longitudinal reinforcement and spiral reinforcement, which can better solve the problem of end stress concentration.

[0009] The circumferential curvature of the six-node equal truss unit cell is kept the same as the curvature of the lattice cylinder shell; the height H of the six-node equal truss unit cell is determined by the inclination angle of the spiral rib and the radius R' of the circle formed by the node of the single-cell spiral rib,

[0010] The method for preparing the above-mentioned six-node equal-truss multi-level lattice cylindrical shell structure comprises the following steps:

[0011] S1: Catia modeling software is used to establish a six-node equal truss multi-level lattice shell model;

[0012] S2: Prepare the above structure model by electron beam melting technology;

[0013] S3: Immerse the integrally formed lattice cylindrical shell structure in the end flange mold, pour the resin, and repeat the flange production at the other end after one end is cured;

[0014] S4: taking out the mold to complete the preparation of the lattice shell.

[0015] Beneficial effects: The present invention provides a six-node equal-truss multi-level lattice shell structure and a preparation method thereof. Compared with the prior art, the present invention has the following advantages:

[0016] 1. The cylindrical shell structure is formed by a six-node equal truss unit cell array. The multi-level design effectively improves the anti-buckling capacity of the structure while ensuring the porosity. The longitudinal reinforcement and spiral reinforcement are arranged at an interval of 60° in the annular direction in the unit cell structure, so that the structure has good mechanical properties under axial compression, bending, torsion and other working conditions. The longitudinal reinforcement runs through the intersection of the spiral reinforcement. The longitudinal reinforcement mainly bears the axial pressure load, while the spiral reinforcement can improve the annular stiffness;

[0017] 2. The six-node equal truss lattice shell structure of the present invention adopts electron beam 3D printing integrated molding technology, using powder as support, and can achieve printing molding at any angle without considering the relationship between the spiral ribs and the horizontal plane. At the same time, the use of metal 3D printing integrated molding process can not only avoid the performance instability of composite material molding, but also avoid the stress concentration problem at the node of traditional metal welding and other processes, ensuring the consistency of the process;

[0018] 3. The six-node equal-truss lattice shell of the present invention has uniform force, good product stability and short manufacturing time, which solves the disadvantages of traditional metal configurations such as cumbersome cutting and welding and stress concentration, and is conducive to the design and application of lattice shells under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is an overall schematic diagram of a six-node equal-truss multi-stage lattice cylinder shell structure in an embodiment of the present invention;

[0020] Figure 2 It is a side view of a six-node equal-truss multi-stage lattice cylinder shell structure in an embodiment of the present invention;

[0021] Figure 3 It is a horizontal cross-sectional view of a six-node equal-truss multi-stage lattice cylinder shell structure in an embodiment of the present invention;

[0022] Figure 4 It is an overall schematic diagram of a six-node equal truss lattice cell in an embodiment of the present invention;

[0023] Figure 5 Schematic diagram of spiral reinforcement of a six-node equal truss lattice cell in an embodiment of the present invention;

[0024] Figure 6 Schematic diagram of two spiral bars at the same angle of a six-node equal truss lattice cell in an embodiment of the present invention;

[0025] Figure 7 It is a top view of a six-node equal-truss lattice cell in an embodiment of the present invention;

[0026] Figure 8 The force displacement curve of the six-node equal-truss multi-level lattice cylindrical shell structure in the embodiment of the present invention;

[0027] Among them, 1-flange; 2-spiral reinforcement; 3-longitudinal reinforcement. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] like Figure 1-3 As shown in FIG. 1 , a lightweight and high-strength six-node equal-truss multi-level lattice cylindrical shell structure is composed of a six-node lattice truss cell array containing longitudinal reinforcement and spiral reinforcement along the circumferential and axial directions. The six-node lattice truss cell has a 12° circumferential angle and a total of 30 cells in the circumferential direction. The six-node lattice truss cells are connected in the cylindrical shell circumferential direction through the spiral reinforcement in the cell, and are connected in the shell generatrix direction through the longitudinal reinforcement array. The cylindrical shell wall thickness t and the unit cell radius R' are determined by the cylindrical shell radius R and the center angle of the cell, as shown in FIG. Figure 4 As shown, the six-node lattice truss cell is composed of a spiral rib 2 and a longitudinal rib 3; the height of the six-node lattice truss cell is determined by the inclination angle of the spiral rib and the radius of the circle formed by the spiral rib nodes in the unit cell; Figure 5 As shown, the angle between the intersection nodes of the spiral reinforcement of the six-node lattice truss cell is 60°, each spiral reinforcement is connected at the end, and the angle between the spiral reinforcement and the horizontal plane is 45°; Figure 6 As shown in FIG. 1 , multiple pairs of spiral ribs with the same central angle form a planar X-shaped structure, and the X-shaped structure is rotated once every 60° to form a layout diagram of the spiral ribs; Figure 7As shown, the spiral reinforcement of the six-node lattice truss cell is a transverse rod in the top view, and the longitudinal reinforcement of the six-node lattice truss cell is arranged at the intersection of the spiral reinforcement in the top view.

[0030] Titanium alloy powder is used in the preparation, and electron beam melting technology is used for manufacturing. The structure is integrally formed, and then heat treatment is performed to remove residual stress during the printing process. Finally, the size is scanned and the model is reconstructed for subsequent analysis. The above six-node equal truss lattice shell structure is assembled according to the following steps:

[0031] 1. Use Catia modeling software to establish a six-node equal truss lattice shell model;

[0032] 2. Prepare the above structural model using 3D printing technology;

[0033] 3. Immerse the integrally formed lattice cylindrical shell structure in the end flange mold, pour the resin, and repeat the flange production at the other end after one end is cured;

[0034] 4. Take out the mold and complete the preparation of the lattice shell.

[0035] The following defines the size and material parameters of the lattice structure cells: the radius R of the lattice cylindrical shell is 50mm, the thickness t is 8.5mm, the circumferential angle of the six-node truss lattice cell is 12°, and there are 30 circumferential cells; the height of the six-node truss lattice cell is 8.5mm, and there are 10 cells in the longitudinal direction; the angle between the spiral ribs and the horizontal plane in the six-node truss lattice cell is 45°, and the diameters of the longitudinal ribs and spiral ribs in the six-node truss lattice cell are consistent, both 1.5mm; the flange radius is 52mm, and the thickness is 2mm. The metal material selected is titanium alloy, which has a Young's modulus of 206GPa, a Poisson's ratio of 0.3, and a density of 7850Kg / m 3 ; The end flange is cast with resin; the weight of a single test piece is 221.19g, the maximum axial bearing capacity is 134.4kN, and it exhibits good mechanical properties under axial compression load.

[0036] The above are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A six-node equal truss multi-level lattice shell structure, characterized in that: The multi-level lattice cylindrical shell structure consists of a shell and end flanges formed by circumferential and axial arrays of six-node equal truss cells, the circumferential array is connected by spiral ribs, and the axial array is connected by longitudinal ribs; the end flanges are connected to both ends of the shell.

2. The six-node equal-truss multi-level lattice shell structure according to claim 1 is characterized in that: The six-node equal truss unit cells are arranged circumferentially at a circumferential angle of 3° to 12°, and are arranged axially along the generatrix direction of the shell.

3. The six-node equal-truss multi-level lattice shell structure according to claim 1 or 2, characterized in that: The annular curvature of the six-node equal truss unit cell is kept the same as the curvature of the lattice cylindrical shell structure.

4. The six-node equal-truss multi-level lattice shell structure according to claim 2 is characterized in that: The number of six-node equal truss units in the annular array is N=2π / α, where α is the annular angle.

5. The six-node equal-truss multi-level lattice shell structure according to claim 1 or 2, characterized in that: The six-node equal truss unit cell is composed of longitudinal reinforcement and spiral reinforcement. The longitudinal reinforcement is arranged every 60° along the central angle of the circle, and the spiral reinforcement is arranged at an angle of 0° to 90° with the horizontal plane and 2 are arranged every 60° along the circumferential direction.

6. The six-node equal-truss multi-level lattice shell structure according to claim 5 is characterized in that: The longitudinal reinforcement and the spiral reinforcement are both round straight bars, and the radius of the longitudinal reinforcement and the spiral reinforcement are consistent.

7. The six-node equal-truss multi-level lattice shell structure according to claim 5 is characterized in that: The angle between the intersection nodes of the spiral ribs is 60°, and each spiral rib is connected at the end.

8. The six-node equal-truss multi-level lattice shell structure according to claim 7 is characterized in that: The longitudinal reinforcement is placed at the intersection of the spiral reinforcement.

9. The six-node equal-truss multi-level lattice shell structure according to claim 5 is characterized in that: The height H of the six-node equal truss unit cell is determined by the inclination angle of the spiral reinforcement. The radius R of the circle formed by the node of the single-cell spiral rib is determined by the angle θ between the spiral rib and the horizontal plane.

10. The method for preparing the six-node equal-truss multi-level lattice shell structure according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Catia modeling software is used to establish a six-node equal truss multi-level lattice shell model; S2: using electron beam melting technology to prepare the six-node equal truss multi-level lattice shell; S3: Immerse the integrally formed lattice cylindrical shell structure in the end flange mold, pour the resin, and repeat the flange production at the other end after one end is cured; S4: taking out the mold to complete the preparation of the lattice shell.

Images