CN113623347B

CN113623347B - Sandwich thin-wall combined energy absorption structure

Info

Publication number: CN113623347B
Application number: CN202110917720.4A
Authority: CN
Inventors: 程伟; 谢清平; 李名
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2021-08-11
Filing date: 2021-08-11
Publication date: 2022-11-04
Anticipated expiration: 2041-08-11
Also published as: CN113623347A

Abstract

The invention relates to a sandwich thin-wall combined energy absorption structure which consists of a frustum, an inner expansion pipe, a sandwich metal pipe and an outer wall, wherein the frustum is provided with a plurality of conical surfaces; wherein the frustum is a rotating body structure with a small bottom diameter and a gradually increasing middle diameter along a certain angle; the inner expansion pipe is a metal round pipe with the diameter smaller than the maximum diameter of the frustum; the sandwich metal pipes are uniformly arranged around the inner expansion pipe, and the round pipe is selected as a sandwich structure; the outer wall is sleeved outside the sandwich metal pipe to limit the movement of the sandwich metal pipe. When the invention works, the cone is axially compressed to ensure that the inner circular tube expands and deforms, and the inner circular tube deforms and absorbs energy due to the expansion and extrusion of the surrounding sandwich metal tube, so the invention has the advantages of small peak impact force, stable buffer force and large buffer stroke, can buffer and absorb energy of transverse loads of an eccentric shaft, and can be used for overload protection of missile-borne equipment, collision prevention of trains, landing of landers and the like.

Description

Sandwich thin-wall combined energy absorption structure

Technical Field

The invention relates to a buffering energy-absorbing structure, in particular to a sandwich thin-wall combined energy-absorbing structure.

Background

The metal thin-wall structure absorbs energy through irreversible plastic deformation, and has a lot of applications in the field of impact collision, the common forms are axial crushing forms such as round tubes, square tubes and star-shaped tubes, but the buffer force is not stable in the energy absorption process of the structural form, and the energy absorption efficiency is low. The buffer force in the energy absorption process can be stable by utilizing the radial expansion and expansion mode of the metal round pipe, but the structure has a single deformation form and low energy absorption capacity.

In order to improve the energy absorption efficiency of the expansion pipe type buffer, a scholars fills foamed aluminum or honeycomb aluminum and the like in the inner part of a round pipe, so that the energy absorption capacity of a combined structure is effectively improved, but the foamed aluminum becomes dense in the later stage of buffer compression by a method for filling the foamed aluminum in the inner part, so that the effective stroke of the buffer is shortened, and the transverse impact cannot be buffered and absorbed.

The sandwich structure has the advantages of high specific strength, large specific modulus and the like, can absorb a large amount of energy through plastic deformation and relieve impact force, is widely applied to packaging, protection of important equipment and military engineering, but has a single deformation form, short buffer stroke and low energy absorption capacity when being used as a buffer.

Disclosure of Invention

The invention solves the problems: the defects of the prior art are overcome, the sandwich thin-wall combined energy absorption structure is provided, stable buffering force is provided under the condition of ensuring a large buffering stroke, the combined deformation of the expansion pipe and the sandwich metal pipe effectively improves the energy absorption efficiency of the structure, and meanwhile, the energy absorption is buffered by transverse impact of a certain off-axis (the off-axis angle is smaller than 10 degrees).

The technical scheme adopted by the invention is as follows: a sandwich thin-wall combined energy absorption structure comprises a frustum, an inner expansion pipe, a sandwich metal pipe and an outer wall; wherein the frustum is a rotating body structure with a small bottom diameter and a gradually increasing middle diameter along a certain angle (the angle range is between 15 and 45 degrees); the inner expansion pipe is a metal round pipe with the diameter smaller than the maximum diameter of the frustum; the sandwich metal pipes are uniformly arranged outside the inner expansion pipe, and the circular pipe is used as a sandwich structure; the outer wall is arranged outside the sandwich metal pipe to limit the movement of the sandwich metal pipe.

The frustum moves axially during working, so that the inner expansion pipe with the inner diameter smaller than the outer diameter of the frustum expands and deforms radially, and absorbs energy through plastic deformation and friction between the frustum and the inner expansion pipe, and the plastic deformation buffer is verified to have stable buffer force and high buffer efficiency.

The sandwich metal pipe is assembled between the inner expansion pipe and the outer wall, and no gap is reserved between the sandwich metal pipe and the inner expansion pipe and between the sandwich metal pipe and the outer wall; the inner expansion pipe expands and then extrudes the sandwich metal pipe, so that the sandwich metal pipe generates transverse extrusion deformation, and the structure can buffer and absorb energy for axial load and can also buffer and absorb energy for transverse load with a certain off-axis (the off-axis angle is less than 10 degrees).

The sandwich thin-wall combined energy absorption structure determines the final buffering force by changing the inclined plane inclination angle of the frustum non-diameter section, the diameter of the diameter-fixed section, the wall thickness of the inner expansion pipe, the wall thickness of the sandwich metal pipe and other parameters and the arrangement mode of the sandwich metal pipe; in order to make the buffer force more stable, circular arc transition is adopted between the frustum constant diameter section and the non-constant diameter section.

The frustum is made of high-strength steel with yield strength larger than 1370MPa, and the Mohs hardness of the high-strength steel is larger than 5.5; the inner expansion pipe and the sandwich metal pipe are made of materials with good plasticity, and the elongation is more than 25 percent.

The beneficial effects of the invention are: the invention combines the traditional expansion pipe type buffer and the sandwich structure, and simultaneously utilizes the diameter expansion plastic deformation of the expansion pipe and the transverse compression plastic deformation of the sandwich metal pipe to improve the buffer force stability and the energy absorption efficiency. Compared with the mode of filling foam metal in the traditional expansion pipe, the mode that the sandwich structure is arranged around the inner circular pipe does not shorten the action stroke of the buffer on the basis of improving the energy absorption capacity. The sandwich thin-wall combined energy absorption structure can realize the control of the buffering force by changing the geometric parameters and materials of the frustum, the circular tube and the sandwich metal tube, and has strong design, simple structure, convenient processing and low cost. Through reasonable design, the buffering energy-absorbing structure can be used for overload protection, train collision prevention, lander landing and the like of missile-borne equipment, and effectively reduces overload of protected equipment under impact.

Drawings

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

FIG. 2 is a cross-sectional view of an energy absorbing structure of the present invention;

FIG. 3 is a schematic view of the combined structure of the inner expansion pipe, the sandwich metal pipe and the outer wall (12 sandwich metal pipes) of the present invention;

FIG. 4 is a schematic view of the combined structure of the inner expansion pipe, the sandwich metal pipe and the outer wall (20 sandwich metal pipes) of the present invention;

FIG. 5 is a load-displacement curve showing a typical loading curve of a sandwich thin-wall composite structure during operation.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As shown in figure 1, the sandwich thin-wall combined energy absorption structure comprises a frustum 1, an inner expansion pipe 2, a sandwich metal pipe 3 and an outer wall 4; wherein the frustum 1 is a rotary body structure with small bottom diameter and gradually increased middle diameter along a certain angle (the angle range is between 15 and 45 degrees), high-strength steel with yield strength larger than 1370MPa is selected, quenching treatment is carried out after processing, stress annealing is carried out after quenching treatment, and the internal stress of the frustum is eliminated; the inner expansion pipe 2 is a metal round pipe with the diameter smaller than the maximum diameter of the frustum, and as the inner expansion pipe is subjected to large deformation, the elongation of the selected material is more than 25 percent, and the size of the inner expansion pipe is adjusted according to the required buffering force; the sandwich metal tube 3 is subjected to transverse compression after being expanded by the expansion tube and also undergoes large deformation, the high-strength steel with yield strength larger than 1370MPa is selected as the material of the inner expansion tube, the thickness of the sandwich metal tube is larger than 5mm, so that the movement of the inner sandwich metal tube is limited, the support can be provided for the transverse load of the off-axis load, and meanwhile, the deformation of the sandwich metal tube is ensured to be small so as not to influence the equipment around the buffer.

As shown in fig. 2, 3 and 4, the inner expansion pipe 2, the sandwich metal pipe 3 and the outer wall 4 are matched in a clearance fit manner, and the three parts are respectively processed, wherein the outer wall 4 is firstly fixed at the collision-resistant part of the equipment, and the mounting part is preferably arranged on a plane. Then the inner expansion pipe 2 is put into the inner expansion pipe, and is not fixed firstly. Then the sandwich metal pipe 3 is embedded into the space between the inner expansion pipe 2 and the outer wall 4, when the sandwich metal pipe 3 is placed at the beginning, the placing process is smoother because the inner expansion pipe 2 can move, and when the metal pipe at the back is placed, the positions of the inner expansion pipe and the sandwich metal pipe 3 are required to be slowly adjusted and prevented in advance. The inner expansion pipes 2 are uniformly distributed, and the amount of the buffer force actually required by installation is determined. After all the components are assembled, the contact part of the inner expansion pipe 2 and the circular pipe can be welded and reinforced as required.

As shown in figure 2, the frustum 1 is connected with a protected device or an impact body at the other end, the frustum 1 moves along the axial direction, so that the inner expansion pipe 2 with the inner diameter smaller than the outer diameter of the frustum 1 expands and deforms in the radial direction, the inner expansion pipe 2 generates plastic deformation and the friction work between the frustum 1 and the inner expansion pipe 2 absorbs energy, the inner expansion pipe 2 extrudes the sandwich metal pipe 3 after expanding, and the sandwich metal pipe 3 generates transverse extrusion deformation.

The magnitude of the buffer force is determined by parameters such as the inclined plane inclination angle of the frustum non-constant diameter section, the diameter of the constant diameter section, the wall thickness of the inner expansion pipe, the wall thickness of the sandwich metal pipe and the like and the arrangement mode of the sandwich metal pipe; in order to make the buffer force more stable, circular arc transition is adopted between the fixed diameter section and the non-fixed diameter section of the frustum. By changing the geometric characteristic parameters and the material plasticity, the sandwich thin-wall combined energy absorption structure can be suitable for different working occasions.

As shown in FIG. 5, the load-displacement curve is a typical loading curve of the sandwich thin-wall composite structure during operation. The process can be continued until the frustum is pressed to the bottom of the inner expansion pipe, and a very long buffer stroke is realized. The traditional expansion tube buffer has long buffer stroke but low energy absorption capacity, and the foamed aluminum filled metal tube has strong energy absorption capacity but short buffer stroke. The combined energy-absorbing structure has the same buffering stroke as the expansion pipe buffer, and the energy-absorbing capacities of the expansion pipe and the sandwich structure are overlapped through the plastic deformation of the combination of the expansion pipe and the sandwich structure, so that the energy-absorbing capacity is effectively improved. When the off-axis angle of the axial impact load is less than 10 degrees, the sandwich metal pipe can buffer and absorb energy of transverse load components.

Claims

1. A sandwich thin-wall combined energy absorption structure is characterized by comprising: a frustum (1), an inner expansion pipe (2), a sandwich metal pipe (3) and an outer wall (4);

the frustum (1) is a rotating body structure with small bottom diameter and gradually increased middle diameter along a certain angle, and is arranged on an impact object, and the axis of the frustum (1) is superposed with the axis of the inner expansion pipe (2);

the inner expansion pipe (2) is a metal round pipe with the diameter smaller than the maximum diameter of the frustum (1);

the sandwich metal pipes (3) are uniformly arranged between the inner expansion pipe (2) and the outer wall (4);

the outer wall (4), the inner expansion pipe (2) and the sandwich metal pipe (3) are in clearance fit to form a whole, and one end of the whole is connected with the collision-resistant part of the protected equipment;

the frustum is divided into an indefinite diameter section with variable diameter and a definite diameter section with invariable diameter;

the frustum diameter fixing section and the frustum diameter unfixed section are in arc transition;

the frustum material is high-strength steel with yield strength larger than 1370MPa, and the Mohs hardness of the high-strength steel at least reaches 5.5;

the inner expansion pipe (2) is plastically deformed when working, and the elongation of the selected material is more than 25%;

the outer wall (4) is made of high-strength steel with yield strength larger than 1370MPa, and the thickness of the high-strength steel is larger than 5mm.

2. The sandwich thin-wall combination energy absorbing structure of claim 1, wherein: the sandwich metal pipe (3) adopts a circular pipe sandwich structure.

3. The sandwich thin-wall combination energy absorbing structure of claim 1, wherein: the frustum (1) is a rotating body structure with a small bottom diameter and a middle diameter gradually increasing along a certain angle, namely the angle range of 15-45 degrees.

4. The sandwich thin-wall combination energy absorbing structure of claim 1, wherein: the magnitude of the buffering force of the energy absorption structure is adjusted by changing the slope angle of the frustum (1), the diameter of the sizing section, the wall thickness of the inner expansion pipe (2), the wall thickness parameter of the sandwich metal pipe (3) and the arrangement mode of the sandwich metal pipe (3).