CN112483569B

CN112483569B - Buffer energy-absorbing bionic light sandwich structure

Info

Publication number: CN112483569B
Application number: CN202011263950.5A
Authority: CN
Inventors: 陈光明; 郭策; 马玉秋; 戴宁
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2020-11-12
Filing date: 2020-11-12
Publication date: 2021-11-26
Anticipated expiration: 2040-11-12
Also published as: CN112483569A

Abstract

The invention discloses a buffering energy-absorbing bionic light sandwich structure which can be used for lightweight parts which are easy to punch, such as aerospace vehicle skins, automobile bodies and the like. The invention has the characteristics of buffering, energy absorption and light weight in multiple directions, when a panel is vertically stamped, the cylinder mainly plays a role in bearing pressure, the filler in the cylinder plays a role in absorbing energy, and meanwhile, the curved-surface blades generate larger deformation to facilitate stress transmission, compared with a hexagonal honeycomb structure with the same mass, the capacity of the upper bionic structure for resisting deformation damage is improved by about 1.5 times when the upper and lower plate surfaces are pressed, and when any side surface is sheared, the capacity for resisting deformation damage is improved by about 35 percent compared with the honeycomb structure.

Description

Buffer energy-absorbing bionic light sandwich structure

Technical Field

The invention relates to the technical field of light functional structures, in particular to a buffering energy-absorbing bionic light sandwich structure.

Background

In order to further improve the energy-saving index of the industries such as aerospace, automobile and the like, new requirements are put forward for developing lightweight components meeting specific mechanical properties. Such as the skin of an aircraft or the pressure of different environments of airflow, vibration and collision, the research and development of the design of the buffering energy-absorbing light structure become an important research target of the parts. In recent years, researchers verify that the bionic sandwich light-weight structure can meet the mechanical property and light-weight requirements, and can be used for the components.

In the aspect of sandwich structure research, the honeycomb-like hexagonal structure has good energy absorption characteristics and can be widely applied to engineering components. Scholars also study the structure of the beetle coleoptera and design a better energy-absorbing buffering light structure. In addition, the scholars save materials and ensure mechanical properties through topology optimization. At present, due to the improvement of energy absorption buffering and light weight requirements of various components, a bionic sandwich structure which meets more engineering requirements is expected to be designed.

In addition to the lightweight structure of honeycombs and coleoptera, many other biological tissues have lightweight and specific mechanical properties. Such as enamel, is a higher hardness cylinder distributed in a lower hardness viscous protein matrix. The cylinder plays a bearing role, and the adhesion of the protein matrix and the cylinder can effectively absorb energy when being compressed. In addition, the helical curved blade (such as a plant blade) in the nature can generate large deformation and is not damaged when being pressed, which shows that the curved blade can effectively transfer stress. Therefore, the enamel structural characteristics and the spiral curved blades provide important references for the design of the novel buffering and energy-absorbing structure.

Disclosure of Invention

The invention discloses a buffering and energy-absorbing bionic light sandwich structure inspired from mechanical unit structures of different biological tissues. The bionic light sandwich structure integrates the mechanical characteristics of an enamel cylinder and a plant helical blade (Gyroid minimum curved surface), and has the characteristics of energy absorption, buffering and light weight.

The specific technical scheme is as follows:

the utility model provides a bionical light sandwich structure of buffering energy-absorbing, includes top panel, lower panel and sets up the sandwich column piece structure between top panel, lower panel, its characterized in that, sandwich column piece structure comprises a plurality of cylinders and curved surface blade, and equidistant parallel distribution between the adjacent cylinder, curved surface blade links to each other and centers on the cylinder.

The cylinder is a column-shaped structure imitating an enamel structure, and the curved-surface leaf is plant-leaf-shaped and is formed by continuous tiny curved surfaces.

In the buffering energy-absorbing bionic light sandwich structure, the curved surface blades surround the column body along the spiral rising direction.

The bionic light sandwich structure with buffering and energy absorption is characterized in that the cylinder body is a hollow cylinder body.

According to the buffering energy-absorbing bionic light sandwich structure, the inside of the hollow cylinder is uniformly filled with polyacrylamide polymers.

The buffering and energy-absorbing bionic light sandwich structure has the advantages that the extremely small curved surface extends and expands in order in the three-dimensional direction, and the curved surface equation is A (cos x · sin x + cos y · sin z + cos z · sin x).

The invention has the beneficial effects that:

the invention discloses a buffering energy-absorbing bionic light sandwich structure which can be used for aerospace craft skins, automobile bodies and other easily-stamped light parts and comprises an upper panel, a lower panel and a sandwich column structure, wherein the sandwich column structure is composed of a plurality of columns and curved surface blades, and the curved surface blades are plant blade-shaped and are composed of continuous extremely-small curved surfaces. Due to the spiral extension characteristic of the curved surface, the curved surface is contacted with the cylindrical surface in the deformation process, and the cylindrical surface is prevented from being bent and folded under pressure to a certain extent. Compared with a hexagonal honeycomb structure with the same mass, the capacity of the bionic structure for resisting deformation damage is improved by about 1.5 times when the upper plate surface and the lower plate surface are pressed, and the capacity for resisting deformation damage is improved by about 35% compared with the honeycomb structure when any side surface is pressed.

Drawings

FIG. 1 is a schematic view of the present invention.

FIG. 2 is a schematic view of a column.

FIG. 3 is a schematic view of a cambered vane.

Fig. 4 is a cross-sectional view of the present invention at an intermediate position.

Fig. 5 is a schematic view of a honeycomb structure.

FIG. 6 is a graph of the compression test of the present invention.

FIG. 7 is a schematic view of the shear test of the present invention.

FIG. 8 is a graph showing the equivalent stress variation of the honeycomb structure under compression according to the present invention.

FIG. 9 is the equivalent stress variation curve when two sides of the present invention are respectively sheared.

Fig. 10 is a graph showing the equivalent stress variation when both sides of the honeycomb structure are respectively sheared.

Detailed Description

In order to make the technical solution of the present invention clearer and clearer, the present invention is further described below with reference to embodiments, and any solution obtained by substituting technical features of the technical solution of the present invention with equivalents and performing conventional reasoning falls within the scope of the present invention.

Example one

The bionic light sandwich structure capable of absorbing energy in a buffering mode comprises an upper panel 1, a lower panel 2 and a sandwich column piece structure arranged between the upper panel 1 and the lower panel 2, and is characterized in that the sandwich column piece structure is composed of a plurality of columns 3 and curved surface blades 4, the adjacent columns 3 are distributed in parallel at equal intervals, the curved surface blades 4 are connected and surround the columns, and filling polymers 5 are arranged in the columns.

The cylinder 3 is a cylindrical structure imitating an enamel structure, and the curved surface blades 4 are plant-blade-shaped and are formed by continuous tiny curved surfaces; and the outer surface of the cylinder is adjacent to the curved blade;

the bionic light sandwich structure with the buffering and energy absorbing functions can be used for light parts which are easy to punch, such as skins of aerospace aircrafts and automobile bodies, and when an upper panel and a lower panel are punched, blades uniformly deform greatly, stress transmission is achieved, and therefore concentrated force borne by a cylinder is reduced;

as shown in fig. 1, when the sandwich column sheet structure extends vertically, the columns extend in the same vertical direction (z-axis direction, as shown in fig. 2), and the curved vanes are continuous (as shown in fig. 3); in the horizontal direction (x-axis and y-axis), the adjacent columns are parallel to each other, and the blade body is continuous and adjacent to the columns (as shown in fig. 4).

Example two

The bionic light sandwich structure with buffering and energy absorbing functions is characterized in that the cylinder 3 is a hollow cylinder, and Polyacrylamide (PAM) polymers 5 are uniformly filled in the cylinder; the polymer absorbs mechanical energy based on the viscoelastic property, so that a better energy absorption effect is obtained when the column body is pressed.

EXAMPLE III

The energy-absorbing bionic light sandwich structure comprises a small curved surface, a core and a core layer, wherein the small curved surface extends and expands in order in the three-dimensional direction, and the curved surface equation of the small curved surface is A (cos x · sin x + cos y · sin z + cos z · sin x);

based on the embodiment, the bionic light sandwich modeling is carried out by taking aluminum alloy as a material, the bionic light sandwich is provided with an upper panel, a lower panel and a sandwich column structure, and the sandwich column structure is provided with a plurality of columns and curved surface blades with complete periods;

the inner radius of the cylinder is set to be 9.5mm, the thickness of the cylinder and the cambered blade is set to be 0.6mm, the blade body is established on the basis of the following model formula A, namely cos x · sin x + cos y · sin z + cos z · sin x, the lengths of the blade body in the x, y and z directions are all 3 pi (by taking the coordinate system of the figure 1 as reference), and the volume of the blade body is 1.1 multiplied by 10⁵mm³Corresponding mass is 357 mg;

performing compression and shear tests on the bionic light sandwich model, and constructing a honeycomb structure (shown in figure 7) under the same quality for comparison;

the compression test flow comprises the following steps: fixing the lower end face of the bionic light sandwich, setting the loading speed to be 10m/s, and performing a mechanical test in the vertical direction, as shown in FIG. 6; stopping loading when the vertical height of the bionic light sandwich is compressed to 72mm (60% of the total height), thereby obtaining a stress-displacement curve shown in figure 8, wherein the stress is increased rapidly in the initial stage, and the initial elastic deformation of the cylinder and the curved blade occurs at the moment; when the bionic light sandwich is loaded to about 20mm, the equivalent stress growth of the bionic light sandwich is slowed down because the cylinder and the curved surface blade are both subjected to large deformation; when the loading is continued, the middle part of the column body is folded after certain deformation, and meanwhile, the curved surface blade is greatly deformed to disperse the pressure on the structure.

The honeycomb was subjected to a compression test under the same loading conditions, and the loading was stopped when the honeycomb was compressed in the horizontal direction to 72mm (60% total height); the results show that the honeycomb structure is severely wrinkled during the compression process, the maximum equivalent stress of the honeycomb structure is 1.5 times larger than that of the bionic structure (as shown in figure 8), and the result shows that the honeycomb structure can prematurely fail in material failure under the same conditions; therefore, compared with the sandwich with the honeycomb structure, the bionic light sandwich has better buffering and energy absorbing effects and better bearing capacity.

Shear test procedure: fixing the lower end face of the bionic light sandwich, applying a fixed baffle plate on the lower half part of one side face of the bionic light sandwich, setting the loading speed to be 10m/s, and carrying out a mechanical test in the horizontal direction, as shown in fig. 7; and stopping loading when the bionic light sandwich is compressed to 72mm (60 percent of total width) in the horizontal direction. Accordingly, a shear test was carried out by loading on one side of the bionic light sandwich to obtain a stress-displacement curve as shown in fig. 9. It can be seen that during loading, the cambered vanes are uniformly deformed by contact with the shear plate first, and then the cylinders are bent by compression.

The honeycomb was subjected to shear testing under the same loading conditions. The results show that large buckling deformation occurs on both sides of the honeycomb structure during shearing, and the equivalent stress is 35% greater than that of the bionic light sandwich structure (as shown in figure 10), which indicates that the honeycomb structure can be subjected to premature material failure under the shearing condition. Therefore, the bionic light sandwich has better buffering and energy absorbing effects than the honeycomb sandwich;

meanwhile, the thickness of the cylinder and the blade body and the diameter of the cylinder are adjustable, the thickness of the cylinder or the thickness of the blade body are increased, the energy absorption and bearing characteristics of the bionic light sandwich are enhanced, and the materials of the cylinder and the curved surface blade provided by the invention can be the same or the cylinder and the curved surface blade are made of different materials.

In summary, the invention has the following advantages:

(1) the bionic sandwich structure is provided by combining two biological structure characteristics, and has the characteristics of buffering and energy absorption when being pressed or sheared;

(2) the aerospace craft skin and the aerospace craft body adopting the bionic light sandwich can effectively resist unstable airflow impact and vibration;

(3) the parameters of the cylinder and the blade body are adjusted, so that the requirements of bearing or energy absorption under different stress environments can be met;

(4) the invention can select the cylinder, the curved surface and the filler material in the cylinder according to the requirement, and can be completed at one time by an industrial 3D printing technology, or the cylinder and the curved surface are printed separately and then are adhered with the panel to complete the whole.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are also included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A buffering energy-absorbing bionic light sandwich structure comprises an upper panel, a lower panel and a sandwich column piece structure arranged between the upper panel and the lower panel, and is characterized in that the sandwich column piece structure is composed of a plurality of columns and curved surface blades, the adjacent columns are distributed in parallel at equal intervals, and the curved surface blades are connected and surround the columns;

the cylinder is of a cylindrical structure imitating an enamel structure, and the curved surface blade is in a plant blade shape and is formed by continuous tiny curved surfaces;

wherein the cambered vanes surround the cylinder along the spiral rising direction;

the extremely-small curved surface extends and expands orderly in the three-dimensional direction, and the curved surface equation is A ═ cos x · sin x + cos y · sin z + cos z · sin x.

2. The bionic light sandwich structure capable of absorbing energy according to claim 1, wherein the column body is a hollow column body.

3. The bionic light sandwich structure capable of absorbing energy according to claim 2, wherein the column body in the form of a hollow column body is uniformly filled with polyacrylamide polymer.