A lightweight externally-arc-shaped damped beam-type passive vibration isolation lattice structure based on selective laser melting forming

Abstract

The present invention relates to a lightweight externally-added arc-shaped damping beam type passive vibration isolation lattice structure based on selective laser melting forming. Each lattice cell includes four body-centered cubic straight bars and 36 arc-shaped damping beam bars. Each arc-shaped damping beam bar is placed within the diagonal plane of the cube, and both ends are connected to the body-centered cubic straight bars. The outer diameter endpoints of the outermost arc-shaped damping beam bars are located at the quarter points of the body-centered cubic straight bars, and the outer diameter is tangent to the cube surface; both ends of the middle-layer arc-shaped damping beam are connected to the outermost-layer arc-shaped damping beam, and its inner diameter is tangent to the surface of the body-centered cubic straight bars; the outer diameter of the inner-layer arc-shaped beam passes through the center line of the middle-layer arc-shaped beam, and both ends are located at the sixteenth points of the body-centered cubic straight bars. The arc-shaped damping beams of this structure can reduce the transmission of vibration through deformation, and the deformation at the nodes and the deformation of the damping beams can absorb the mechanical energy of vibration, having good vibration isolation and damping performance.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering vibration reduction and isolation, and particularly to a lightweight externally damped beam-type passive vibration reduction and isolation lattice structure based on selective laser melting forming. Background Art

[0002] Nowadays, the development of the aerospace industry has put forward more urgent requirements for the lightweight and vibration reduction and isolation performance of materials. Due to its excellent characteristics such as high specific stiffness, high specific strength, and small relative density, lattice structure is a very effective lightweight solution design that is widely used in various fields at present. It is estimated that if the components of a spacecraft adopt lattice structure sandwich materials, the spacecraft will be reduced to half of its original weight under the condition of unchanged mechanical properties. The application of lattice structure will also be greatly improved in terms of energy absorption and vibration reduction. When the spacecraft is running at high speed, a large amount of vibration noise will be generated, which may cause the fracture and failure of internal components of the spacecraft, the drift of precision instrument indicators, and the injury of astronauts' bodies. The main solutions to reduce vibration disturbances are as follows: one is to reduce the energy output of the vibration source, such as optimizing the design of aeroengines to reduce the vibration generated during operation; the second is to suppress the vibration during the transmission process, such as using methods such as local stiffness modification and local damping optimization; the third is to use vibration reduction and isolation devices to reduce vibration excitation for vibration-sensitive equipment.

[0003] As a new manufacturing method of layer-by-layer powder spreading and layer-by-layer irradiation forming, the SLM selective laser melting technology can customize and form any complex lattice structure, which provides the possibility for designing and forming a lightweight lattice structure with high vibration reduction and isolation performance. However, the current research on the vibration reduction and isolation performance of lattice structures is still in its initial stage, and no effective lattice vibration reduction and isolation design has been proposed. Some of the existing designs are not suitable for SLM selective laser melting forming of metal materials; some designs still use the truss structure design composed of body-centered cubic straight bars. When this structure is excited, the stress is concentrated at the connection points of the bars, and the high stress concentration is extremely likely to cause the array structure to shear and fail in advance at the connection points of the bars; some designs adopt the principle of mass resonator, and this design has a relatively large relative density and cannot meet the lightweight requirements of the aerospace industry. Summary of the Invention

[0004] In order to overcome the problems described in the background art, the present invention proposes a new lattice structure design of an externally damped beam ( Figure 7 ).

[0005] The purpose of the present invention is to provide a lattice structure that can be periodically arrayed, and by using the basic theory of damping generation, a periodic structure that is lightweight and has good mechanical properties and vibration reduction and isolation performance is designed.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A lattice structure with externally added damping beams is formed by multiple cell arrays. The arrays are arranged in a periodic pattern in the Cartesian rectangular space coordinate system. The lattice cells are physically connected to each other. The lattice is a centrosymmetric structure composed of four straight rod members and a total of 36 arc-shaped damping beams in three layers.

[0008] The four straight rod members are cross-placed to form a body-centered cubic structure within a cube. Arc-shaped damping beams are placed within each diagonal plane of the cube. The outer diameter of the outermost layer of damping beams is just tangent to the cube surface. The two ends of the damping beams are connected to the straight rod members of the body-centered cubic. The inner diameter of the middle layer of damping beams is tangent to the straight rod members of the body-centered cubic and connected to the inner diameter of the outermost layer of damping beams at both ends. The two ends are connected to the straight rod members of the body-centered cubic. The inner layer of damping beams intersects with the middle layer of damping beams. Its outer diameter intersects with the center line of the middle layer of damping beams at a point. The two ends are connected to the straight rod members of the body-centered cubic at the sixteenth points of the straight rod members.

[0009] Preferably, the cross-sectional radius of the straight rod members of the body-centered cubic is adjustable.

[0010] Preferably, the size of the lattice cell is adjustable.

[0011] Preferably, the cross-section of the arc-shaped damping beam can be selected as an ellipse or a polygon.

[0012] Preferably, the relative positions of the arc-shaped damping beam and the straight rod members of the body-centered cubic are changed.

[0013] Preferably, the cross-sectional radius and the center line radius of the arc-shaped damping beam are adjustable, which can change the stiffness and damping ratio of the structure.

[0014] Preferably, by adding or reducing the number of damping beams, the stiffness and damping ratio of the structure can be changed.

[0015] Preferably, the cross-sectional area of the straight rod members of the body-centered cubic gradually changes from the center of the straight rod members of the body-centered cubic to both ends

[0016] Preferably, the cross-sectional area of the arc-shaped damping beam changes from the center of the straight rod to both ends.

[0017] Preferably, the structure is formed using a high-damping alloy to obtain a lattice device with better high vibration isolation and damping performance.

[0018] The method for preparing the above lattice structure is SLM selective laser melting.

[0019] Compared with the prior art, the significant advantages of the present invention are as follows:

[0020] (1) When the lattice structure provided by the present invention is subjected to vibration excitation, it can actively deform to reduce the transmission of the amplitude, and a large number of externally added damping beams can absorb a large amount of vibration energy, thereby achieving the effect of energy absorption and vibration reduction.

[0021] (2) The lattice structure provided by the present invention solves the stress concentration problem when the structure is subjected to a load because the number of rods and rod connection points in a single lattice cell is increased, and the arc-shaped rods achieve uniform stress distribution. While being less likely to fail, there are more plastic hinges and load-bearing structures to absorb energy, resulting in a significant improvement in the modulus, strength, and energy absorption of the lattice structure.

[0022] (3) The lattice structure provided by the present invention can reduce weight, enhance the specific stiffness and specific strength of parts, increase the reliability of parts, and greatly strengthen the vibration isolation and damping capacity of parts in application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the front view of the outer arc-shaped damping beam structure of the lattice structure of the present invention.

[0024] Figure 2 is the schematic diagram of the outer arc-shaped damping beam structure of the lattice structure of the present invention.

[0025] Figure 3 is the front view of the middle arc-shaped damping beam structure of the lattice structure of the present invention.

[0026] Figure 4 is the front view of the inner arc-shaped damping beam structure of the lattice structure of the present invention.

[0027] Figure 5 is the schematic diagram of the middle and inner arc-shaped damping beam structures of the lattice structure of the present invention.

[0028] Figure 6 is the front view of the entire arc-shaped damping beam structure of the lattice structure of the present invention.

[0029] Figure 7 is the schematic diagram of the entire arc-shaped damping beam structure of the lattice structure of the present invention.

[0030] Figure 8 is the 5×5×5 array of the lattice structure of the present invention.

[0031] Figure 9 (a) is the stress distribution nephogram of the present invention under compression load, and (b) is the stress nephogram of the body-centered cubic structure under compression.

[0032] Figure 10 The frequency response curves of the lattice structure and the body-centered cubic structure proposed by the present invention.

[0033] Figure 11 (a) Schematic diagram of the structure with gradually increasing cross-sectional area on both sides of the center of the arc-shaped damping beam and (b) the straight rod of the body-centered cubic. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings.

[0035] See Figures 1-9 As shown, the embodiment of the present invention provides a lattice structure that can be periodically arrayed, formed by a plurality of cell arrays. The array method is that the lattice cells are periodically arranged in a Cartesian rectangular space coordinate system, and the lattice cells are physically connected.

[0036] The lattice cell is a centrosymmetric structure, including four straight rod members and three layers of a total of 36 arc-shaped damping beams. The four straight rod members intersect to form a body-centered cubic structure of a cube:

[0037] As Figure 1 shown, arc-shaped damping beams are placed in each diagonal plane of the cube. The outer diameter of the outermost layer of damping beams is just tangent to the surface of the cube. The two ends of the damping beams are connected to the straight members of the body-centered cubic. The outer diameter connection points are located at the quarter points of the straight members of the body-centered cubic. The construction rule of the arc-shaped damping beams is to determine the arc with the face center of the cube and the quarter points of the straight members of the two body-centered cubes.

[0038] As Figure 2 shown, two arc-shaped damping beams are located in mutually perpendicular diagonal planes and intersect at a point, and the intersection point is also the tangent point to the surface of the cube. Such a design will not produce a suspended structure during the array, which is beneficial to the use of SLM selective laser melting for unsupported one-piece rapid prototyping.

[0039] As Figure 3 shown, the inner diameter of the middle layer of damping beams is tangent to the straight members of the body-centered cubic and connected to the inner diameter of the outermost layer of damping beams, and the two ends are connected to the straight members of the body-centered cubic.

[0040] As Figure 4 shown, the inner layer of damping beams intersects with the middle layer of damping beams, and its outer diameter intersects with the center line of the middle layer of damping beams at a point, and the two ends are connected to the straight members of the body-centered cubic.

[0041] As Figure 5 shown, the middle layer of damping beams and the inner layer of damping beams in two mutually perpendicular diagonal planes intersect to form a node, which can support the upper layer of arc-shaped damping beams when the model is formed. Such a design is beneficial to SLM laser selective melting forming without support, and at the same time greatly improves the mechanical properties of the structure and the vibration isolation and damping ability of the structure.

[0042] As Figure 6 shown, the structural design proposed by the present invention is a centrosymmetric figure, and there is no difference in the static and dynamic mechanical properties in each symmetric direction.

[0043] As Figure 7Compared with the body-centered cubic structure, this structure adds 36 damping beams and 81 nodes in each lattice space. When the excitation load is applied, the damping beams can evenly bear the stress and can also deform to reduce the transmission of vibration. The added damping beams and nodes can provide more stress support points and absorb energy through deformation at the same time.

[0044] The present invention discloses a theory and method for vibration isolation and optimization of lattice cell structures, and the main steps are as follows:

[0045] S1. Use CAD software to model the lattice structure;

[0046] S2. Use abaqus for finite element simulation to obtain the frequency response performance and stress distribution nephogram of the lattice structure under vibration excitation load;

[0047] S3. Analyze the structure optimization direction according to the stress distribution nephogram, select the shape, position, size and quantity of the rods. It is found through the nephogram that the stress of the body-centered cubic is concentrated at the body-centered node, and the straight rods of the body-centered cubic do not bend during deformation. Therefore, an optimization idea of adding damping beams is proposed. The addition of damping beams can increase two types of deformation energy absorption structures, namely rods and nodes. Since the circular ring-shaped rods can evenly bear the stress, finally a circular shape is selected, and three layers of arc-shaped damping beams are arranged in the cube using the principle of fractal geometry to achieve the optimization of SLM selective laser melting forming and mechanical properties.

[0048] As Figure 8 shown, an array of 5×5×5 is made for the lattice structure proposed by the present invention. In the three-dimensional Cartesian space coordinate system, the array is carried out at intervals of the side length of the cell cube along the X, Y, and Z directions. The morphology of the array can be adjusted according to specific engineering applications, or gradient arrays can be used to make the structure exhibit better energy absorption and vibration damping performance.

[0049] By adjusting various parameters, the modulus and damping ratio of the structure can be adjusted within a large range.

[0050] The straight rods of the body-centered cubic with the same specifications without adding arc-shaped damping beams are used as a comparison with the results of the body-centered cubic in the abaqus software to verify the optimization effect of the structure performance after adding damping beams.

[0051] As Figure 9 (a) shown, in the first vibration mode, the straight rods of the body-centered cubic will deform and move, while the arc-shaped damping beams can more evenly bear the stress and can deform to absorb the energy generated by vibration. As Figure 9 (b) shown, the added nodes will play a role similar to that of a damper, and use the internal friction of the material to absorb vibration energy.

[0052] As Figure 10As shown, the amplitude of the structural output has been significantly reduced compared to the input amplitude, and the natural frequency of the structure with the arc-shaped damping beam added is lower than that of the body-centered cubic structure. This is due to the increase in structural density. If the structural parameters are adjusted so that the relative density of the structure proposed in the present invention is the same as that of the body-centered cubic structure without the arc-shaped damping beam, then the amplitude transmission can be reduced under the condition that the relative frequencies are not much different. In the aerospace field, the working frequency during operation often does not exceed 2000 Hz, generally below 200 Hz. Therefore, this structure can be fully applied to the vibration isolation and reduction field in aerospace.

[0053] As Figure 11 (a) shows that the cross-sectional area of the arc-shaped damping beam gradually increases from the center to both sides. As Figure 11 (b) shows, it is a schematic diagram of the structure where the cross-sectional area of the straight bars of the body-centered cubic structure gradually increases from the center to both sides.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it, because the embodiments do not elaborate on all details. Various solutions can be combined in any way to form other embodiments that can be well understood and utilized by those skilled in the art of the relevant technical field. The present invention is only limited by the claims and the full scope and equivalents thereof.

Claims

1. A lightweight externally damped beam-type passive vibration isolation lattice structure based on selective laser melting forming is a lattice structure with a periodic array. Each lattice cell includes four body-centered cubic straight rods and 36 arc-shaped beam rods. Each arc-shaped beam rod is placed in the diagonal plane of the cube, and both ends are connected to the body-centered cubic straight rods; the two end points of the outer arc-shaped beam are located at the quarter points of the body-centered cubic straight rods, and the outer diameter is tangent to the cube surface; the two ends of the middle arc-shaped damping beam are connected to the outer arc-shaped damping beam, and the inner diameter is tangent to the surface of the body-centered cubic straight rod; the outer diameter of the inner arc-shaped beam passes through the center line of the middle arc-shaped beam, and both ends are located at the sixteenth points of the body-centered cubic straight rods; its characteristics are The cross-sectional area of the straight bar with a body-centered cubic structure increases from the center of the straight bar to both ends.

2. The lattice structure according to claim 1, characterized in that The cross-sectional area of the arc-shaped damping beam increases from the center of the arc-shaped damping beam to both ends.

3. A method for preparing the lattice structure according to any one of claims 1-2, characterized in that, It is formed and prepared by the SLM selective laser melting method.

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