CN111255838A

CN111255838A - Hierarchical lattice structure

Info

Publication number: CN111255838A
Application number: CN202010054432.6A
Authority: CN
Inventors: 柏龙; 龚程; 陈晓红; 孙圆喜; 胡明金; 蒲华燕
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2020-06-09

Abstract

The invention discloses a hierarchical lattice structure, which comprises an external thin-wall structure and an internal lattice structure filled in the external thin-wall structure; the external thin-wall structure is in a macroscopic size, and the internal lattice structure is in a mesoscopic size; the invention creatively provides a hierarchical lattice structure formed by filling the lattice structure of mesoscopic size level under macroscopic size, which not only further enhances the mechanical property of the lattice structure, but also keeps the high specific surface area and the opening characteristic of the lattice structure, so that the hierarchical lattice structure has good application value in functional bearing application.

Description

Hierarchical lattice structure

Technical Field

The invention relates to the technical field of material structures, in particular to a lattice structure. The lattice structure comprises an internal filling lattice material and an external enhanced thin-wall structure, has the characteristics of high bearing capacity, high specific surface area, hole opening and the like, and has good structural and functional characteristics.

Background

At present, the requirements for light weight and high performance of aircrafts and aircraft engines are higher and higher, and the structure and the function need to be considered in the design of the traditional spacecraft, namely, on one hand, a structural member with high bearing capacity is needed, and on the other hand, special requirements for heat insulation, vibration reduction and the like need to be met. Therefore, development of functional materials having excellent structural and functional characteristics has been inevitably demanded. The lattice structure has great potential in application in the field of aviation due to the characteristics of high porosity, high specific surface area and open pores. For example, CN201710335220.3, a method for preparing a sector sealing block with a lattice cooling structure, utilizes the excellent heat dissipation characteristic of the lattice structure due to its high specific surface area to prepare a sector sealing block with good heat dissipation and cooling. However, this structure is limited to the embodiment of heat dissipation property, and the load-bearing capacity of the structure needs to be further improved. In contrast, CN201510500428.7, a sandwich structure with a mesh reinforced honeycomb core, discloses a method for reinforcing a honeycomb structure by using a mesh structure, which improves the mechanical properties of the structure. However, due to the existence of thin-walled features, the two-dimensional plane-stretched honeycomb structure has a relatively single open-cell form and a relatively small specific surface area compared with the three-dimensional lattice structure. In addition, due to the limitation of the current preparation technology, the existing lattice structure mainly exists in macroscopic and mesoscopic sizes, the functional representation of the lattice structure is mainly based on the application of a new material, and the excellent structural characteristics of the lattice structure cannot be fully represented.

Disclosure of Invention

In view of the above, in order to realize excellent structural load-bearing characteristics and functional characteristics of high specific surface area, the functions of the structural member are diversified. The invention creatively provides a hierarchical lattice structure formed by filling the lattice structure of mesoscopic size level under macroscopic size, which not only further enhances the mechanical property of the lattice structure, but also keeps the high specific surface area and the opening characteristic of the lattice structure, so that the hierarchical lattice structure has good application value in functional bearing application.

The hierarchical lattice structure comprises an external thin-wall structure and an internal lattice structure filled in the external thin-wall structure; the external thin-wall structure is in macroscopic size, and the internal lattice structure is in mesoscopic size.

Furthermore, the connection between the external thin-wall structure and the internal lattice structure is formed by combining entities through Boolean operation;

further, the external thin-wall structure is a honeycomb structure obtained by stretching a two-dimensional plane;

further, the external thin-wall structure is a square structure, and the internal lattice structure is a body-centered cubic lattice structure or a face-centered cubic lattice structure;

furthermore, the outer thin-wall structure of the square structure and the inner lattice structure filled in the square structure form a hierarchical lattice structure unit cell; the hierarchical lattice structure unit cells are arranged along two directions, and adjacent unit cells are tightly combined and are combined through entities in Boolean operation, so that a hierarchical lattice structure with a larger size is formed.

The invention has the beneficial effects that:

1. compared with the traditional lattice structure, the hierarchical lattice structure provided by the invention has the advantage that the mechanical property is obviously improved.

2. The hierarchical lattice structure of the present invention has relatively high specific surface area and opening characteristic.

3. The invention can realize the change of the functional characteristics of the hierarchical lattice structure by changing the lattice structure filled inside, and further, the lattice structures with different topological forms are filled in different areas, and the gradient change of the hierarchical lattice structure can be realized.

Drawings

The invention is further described below with reference to the following figures and examples:

FIG. 1 is a schematic view of an outer thin-walled structure;

FIG. 2 is a schematic representation of a body centered cubic lattice structure;

FIG. 3 is a schematic diagram of a hierarchical lattice structure unit cell;

FIG. 4 is a front view of a large-scale hierarchical lattice structure;

FIG. 5 is an isometric view of a large-scale hierarchical lattice structure (internally a body-centered cubic lattice);

FIG. 6 is a schematic illustration of a face centered cubic lattice structure;

FIG. 7 is an isometric view of a large-scale hierarchical lattice structure (internally a face-centered cubic lattice);

FIG. 8 is a graph comparing compressive stress strain curves.

Detailed Description

The embodiment discloses a hierarchical lattice structure, which is characterized in that a thin-wall structure 1 is added on the basis of a traditional lattice, so that the mechanical property of the lattice structure can be greatly improved. In addition, the hierarchical lattice structure still maintains the high specific surface area and the opening characteristics of the lattice structure, so that the functions of the lattice structure, such as heat conductivity, a catalyst carrier and the like, are ensured, and a new reference is provided for the design of various functional structural members with special functions at present.

Preferably, the internal lattice structure is chosen to be simple in structure, with a widely representative Body Centered Cubic (BCC) lattice structure 2, and the external thin-walled structure 1 is chosen to be Square (Square) in structure. The internal dimension of the Square structure is 5 multiplied by 5mm³External dimensions of 5.5X 5mm³(thin-walled structure 1 thickness 0.25mm), see FIG. 1; the inner BCC lattice structure has a 2-rod diameter of 0.25mm and a unit cell size of 1 × 1 × 1mm³FIG. 2 shows a BCC lattice block with three directional numbers, each bit 5, and an overall size of 5 × 5 × 5mm³(ii) a The resulting hierarchical lattice structure is shown in FIG. 3, with overall dimensions of 5.5X 5mm³。

Preferably, the hierarchical lattice structure unit cells are arranged along two directions, tightly combined, and combined by the entities in the boolean operation to form the hierarchical lattice structure with a larger size, see fig. 4 and 5, whose overall size is 16 × 16 × 5mm³. Fig. 4 shows a front view of a hierarchical lattice structure, and fig. 5 is a top and bottom isometric view of the structure.

More preferably, to enlarge the surface area of the hierarchical lattice structure, the BCC lattice structure 2 inside the hierarchical lattice structure is replaced with a Face Centered Cubic (FCC) lattice structure 3, see FIG. 6, having a rod diameter of 0.2mm and unit cell size of 1X 1mm³The resulting overall hierarchical lattice structure is shown in FIG. 7.

Preferably, the BCC structure, the Square structure and the composite Square + BCC hierarchical lattice structure are subjected to finite element analysis, the titanium alloy TC4 is taken as a material, and the compressive stress-strain curve is shown in figure 8. The elastic modulus of the BCC lattice structure is 2.3GPa, the compressive strength is 75MPa, the relative elastic modulus and the relative compressive strength can be obtained by taking the influence of the relative density in the lattice structure into consideration and making the ratio of the modulus to the strength to the relative density, and the BCC lattice structure is 8.73GPa and 284.1MPa in sequence. The elastic modulus of the hierarchical lattice structure with the thin-wall structure is 23.6GPa, the compressive strength is 311MPa, and the relative modulus and the relative strength are 60.39GPa and 795.4MPa respectively. The relative elastic modulus is increased by 591.8%, and the relative compressive strength is increased by 180%.

In addition, the specific surface areas of the BCC structure, the Square structure and the composite Square + BCC hierarchical lattice structure are respectively as follows: 3.74,0.73,3.67. Therefore, the hierarchical lattice structure has higher specific surface area, and the specific surface area is greatly increased compared with that of a two-dimensional honeycomb structure. Further, by observing the simulated destruction form, it was found that: the independent square structure thin wall has obvious fold under large deformation, the three-dimensional lattice structure has obvious shear band, but the composite hierarchical lattice structure has bulging phenomenon, and the change of the damage form leads to the great improvement of the bearing capacity of the lattice structure.

More preferably, the FCC lattice structure 3 is selected as the inner lattice structure replacing the BCC, and the specific surface area of the formed hierarchical lattice structure is up to 4.05.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and those skilled in the art can make various modifications and variations; any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A hierarchical lattice structure characterized by: the device comprises an outer thin-wall structure and an inner lattice structure filled in the outer thin-wall structure; the external thin-wall structure is in macroscopic size, and the internal lattice structure is in mesoscopic size.

2. The hierarchical lattice structure of claim 1, wherein: and the joint between the external thin-wall structure and the internal lattice structure is formed by combining entities through Boolean operation.

3. The hierarchical lattice structure of claim 1, wherein: the outer thin-wall structure is a honeycomb structure obtained by stretching a two-dimensional plane.

4. The hierarchical lattice structure of claim 1, wherein: the external thin-wall structure is a square structure, and the internal lattice structure is a body-centered cubic lattice structure or a face-centered cubic lattice structure.

5. The hierarchical lattice structure of claim 1, wherein: the outer thin-wall structure of the square structure and the inner lattice structure filled in the square structure form a hierarchical lattice structure unit cell together; the hierarchical lattice structure unit cells are arranged along two directions, and adjacent unit cells are tightly combined and are combined through entities in Boolean operation, so that a hierarchical lattice structure with a larger size is formed.