A bionic saddle-shaped unit and a lattice structure derived therefrom

Abstract

The present invention discloses a bionic saddle-shaped unit and a lattice structure derived from it. It belongs to the field of bionics and material structure technology; the specific steps are: designing a standard unit through the ridge, ribs and skirt structure of the bionic saddle algae truncated body, including five nodes and eight rods, connected in a specific order; the rods include straight rods and curved rods; the lattice structure includes a plurality of unit cells, and the plurality of unit cells are repeated in space and interconnected to form a lattice; the lattice structure involved is light in weight, has controllable mechanical properties, and has excellent shape memory properties. The present invention effectively regulates the load-bearing performance, deformation performance and energy absorption performance of the unit by combining different external frame structures and internal support structures; in addition, the lattice structure exhibits excellent deformation performance and moderate load-bearing capacity in one direction, and excellent load-bearing capacity and stiffness in another direction. Its characteristics enable it to meet more complex component designs, avoid the selection, modeling and filling of multiple lattice structures, and reduce costs.

Description

Technical Field

[0001] The invention belongs to the technical field of bionics and material structure, and relates to a design process of a bionic saddle-shaped unit, in particular, to a bionic saddle-shaped unit and a lattice structure derived therefrom. Background Art

[0002] In the field of structural engineering, the integration of high-performance and multifunctional components leads to an undesirable increase in the available space, assembly difficulty, allowable cost and weight of related equipment, requiring more complex and optimized structures to meet the requirements of lightweight, integrated and large-scale components. Lattice structures composed of periodically arranged units often have excellent properties and functions that large solid structures do not have, such as high stiffness / weight ratio, high specific strength, excellent energy absorption performance, etc., and have been applied to aerospace, automobile manufacturing, biomedicine and other fields. At present, the widely studied lattice structures include BCC, BCCZ, FCC, FCCZ, pyramid structure, octahedral structure, etc., and it is shown that the relevant properties of the lattice structure show a strong dependence on its configuration, size and other parameters. On this basis, a more adaptable structural design is required for higher requirements of a certain performance, such as gradient structures perform better in energy absorption than homogeneous structures, and minimal surface structures have more stable deformation and destruction processes than spherical structures. In addition, some functions of the lattice structure are given by the material, such as nickel-based high-temperature alloys, low-expansion Invar alloys and shape memory alloys; the performance of material properties also depends on the structural morphology to a certain extent. However, there are few unique designs to take advantage of specific materials, such as the Z-axis of the BCCZ structure, which greatly limits the shape memory performance of NiTi shape memory alloy. Therefore, more unique designs are needed to expand the database of lattice structure design to meet the needs of more material systems and application environments.

[0003] In order to achieve the optimal energy solution, naturally evolved structures often have suitable features, light weight, adaptability to the environment, and optimal performance / function. Therefore, bionic strategies are an effective way to design and optimize structures, such as mantis shrimp corrugated plate structures and water spider diving bell shell structures. As a representative of natural micro / nano structures, the unique diatom frustum structure has good mechanical stability and can effectively disperse stress concentration caused by external forces, making it an ideal target for bionic structure design. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a bionic saddle-shaped unit and its lattice structure, so as to provide more options for the structural design of related devices and better play the advantages of specific materials.

[0005] Technical solution: The bionic saddle-shaped unit described in the present invention is in the shape of a saddle, and includes four peripheral nodes, one central node and eight contour lines; the design process is as follows:

[0006] The first step is to extract four surrounding nodes 2, 3, 4, 5 on the skirt and a central node 1 where the ridge and rib intersect, a total of five nodes, according to the structural characteristics of the ridge, rib and skirt of the saddle algae frustum;

[0007] Determine a total of 8 connecting lines between nodes 1, 2, 3, 4 and 5;

[0008] Step 2: Mark the five nodes 1, 2, 3, 4 and 5 in the cube respectively;

[0009] The central node 1 is placed at the center of the cube, the surrounding nodes 2 and 4 are placed at the midpoints of the parallel edges of the upper surface of the cube, and the surrounding nodes 3 and 5 are placed at the midpoints of the parallel edges of the lower surface of the cube;

[0010] And the connecting line through connecting 2-3 and the connecting line through connecting 4-5 are vertical in the space of the cube;

[0011] Step 3: Connect the surrounding nodes 2-3-4-5 to form the outer frame contour of the unit, and connect the nodes 2-1-4 and 3-1-5 to form the inner support contour of the unit;

[0012] Step 4: Combine the outer frame contour line with the inner support contour line through Boolean operation to form a bionic saddle-shaped unit.

[0013] Furthermore, in the third step of the design process, the outer frame contour and the inner support contour of the forming unit are both rod structures with the same diameter and circular cross-section, namely the outer frame structure and the inner support structure;

[0014] The rod structure includes a straight rod and a curved rod, and the diameter of each rod is 0.8 mm.

[0015] Furthermore, the external frame structure is divided into a straight rod external frame structure and a curved rod external frame structure;

[0016] The internal support structure is divided into a straight rod internal support structure and a curved rod internal support structure.

[0017] Furthermore, in the fourth step of the design process, the constructed bionic saddle-shaped unit specifically refers to: through Boolean operations, the bionic unit of the curved rod external frame structure and the curved rod internal support structure, the bionic unit of the curved rod external frame structure and the straight rod internal support structure, the bionic unit of the straight rod external frame structure and the curved rod internal support structure, and the bionic unit of the straight rod external frame structure and the straight rod internal support structure are respectively formed.

[0018] Furthermore, a lattice structure is derived by using the bionic saddle-shaped unit of the design as a filling unit cell;

[0019] The lattice structure is specifically formed by periodic arrangement of bionic saddle-shaped unit cells.

[0020] Furthermore, the lattice structure is formed by a periodic arrangement of bionic units of an external frame structure of the curved rod and an internal supporting structure of the curved rod.

[0021] Furthermore, the lattice structure is formed by a periodic arrangement of bionic units of a curved rod external frame structure and a straight rod internal support structure.

[0022] Furthermore, the lattice structure is formed by a periodic arrangement of bionic units of a straight rod external frame structure and a curved rod internal support structure.

[0023] Furthermore, the lattice structure is formed by a periodic arrangement of bionic units of a straight rod external frame structure and a straight rod internal support structure.

[0024] Furthermore, the lattice structure is formed by laser powder bed melting technology.

[0025] Beneficial effects: Compared with the prior art, the present invention is characterized by: 1) The bionic saddle-shaped unit proposed in the present invention has good controllability. By combining different external frame structures and internal support structures, the unit's load-bearing performance, deformation performance and energy absorption performance can be effectively regulated to meet different application requirements. In addition, the bionic saddle-shaped unit has a relatively small dead weight and model data volume, which can reduce the cost of components during processing and use, and save database storage space; 2) The lattice structure proposed in the present invention exhibits beneficial anisotropy. The lattice structure exhibits excellent deformation performance and moderate load-bearing capacity in one direction, and excellent load-bearing capacity and stiffness in another direction. This characteristic enables it to meet more complex component designs, thereby avoiding the selection, modeling, and filling of multiple lattice structures, reducing costs, and improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the bionic design of the present invention;

[0027] Figure 2 It is a schematic diagram of a straight rod external frame structure and a curved rod external frame structure of the present invention;

[0028] Figure 3 It is a schematic diagram of the internal support structure of the straight rod and the internal support structure of the curved rod of the present invention;

[0029] Figure 4It is a schematic diagram of a bionic saddle-shaped unit 1 composed of a straight rod external frame structure and a straight rod internal support structure of the present invention;

[0030] Figure 5 It is a schematic diagram of a bionic saddle-shaped unit 2 composed of a straight rod external frame structure and a curved rod internal support structure of the present invention;

[0031] Figure 6 It is a schematic diagram of a bionic saddle-shaped unit 3 composed of a curved rod external frame structure and a straight rod internal support structure of the present invention;

[0032] Figure 7 Schematic diagram of a bionic saddle-shaped unit 4 composed of a curved bar external frame structure and a curved bar internal support structure of the present invention;

[0033] Figure 8 It is a schematic diagram of a lattice structure 1 composed of a periodic arrangement of bionic saddle-shaped units 1 of the present invention;

[0034] Fig. 9 It is a schematic diagram of a lattice structure 2 composed of a periodic arrangement of bionic saddle-shaped units 2 of the present invention;

[0035] Fig.10 It is a schematic diagram of a lattice structure 3 composed of 3 periodically arranged bionic saddle-shaped units of the present invention;

[0036] Fig.11 It is a schematic diagram of a lattice structure 4 composed of 4 periodically arranged bionic saddle-shaped units of the present invention;

[0037] Fig.12 It is a side view of the sandwich structure formed by the lattice structure 1-Y direction of the present invention;

[0038] Fig.13 It is a side view of the sandwich structure formed by the lattice structure 1-Z direction of the present invention;

[0039] Fig.14 It is a force-displacement curve diagram in two directions obtained by a quasi-static compression test of the present invention. DETAILED DESCRIPTION

[0040] In order to more clearly illustrate the technical solution of the present invention, the technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings:

[0041] As shown in the figure, on the one hand, the present invention proposes a bionic saddle-shaped unit, which is in the shape of a saddle and specifically includes 4 surrounding nodes, a central node and 8 contour lines. The design process is specifically as follows:

[0042] The first step is to extract four peripheral nodes on the skirt and a central node where the ridge and ribs intersect, a total of five nodes, based on the structural characteristics of the ridge, ribs, and skirt of the truncated body of the saddle algae.

[0043] Determine a total of 8 connecting lines between nodes 1, 2, 3, 4 and 5;

[0044] Step 2: Mark the five nodes 1, 2, 3, 4 and 5 in the cube respectively;

[0045] Among them, the central node 1 is placed at the center of the body, the surrounding nodes 2 and 4 are placed at the midpoints of the parallel edges of the upper surface, the surrounding nodes 3 and 5 are placed at the midpoints of the parallel edges of the lower surface, the surrounding nodes 2-3 and the surrounding nodes 4-5 are perpendicular in space; and the connecting line through connection 2-3 and the connecting line through connection 4-5 are perpendicular in the space of the cube;

[0046] Step 3: Connect the surrounding nodes 2-3-4-5 to form the outer frame contour of the unit, and connect the nodes 2-1-4 and 3-1-5 to form the inner contour of the unit;

[0047] Step 4: Through Boolean operations, the outer frame contour line is combined with the inner support contour line to form a bionic saddle-shaped unit.

[0048] Preferably, in the third step of the design process, the eight contour lines of the bionic saddle-shaped unit (the outer frame contour lines and inner support contour lines forming the unit) all adopt rod structures with the same diameter and circular cross-section, namely the outer frame structure and the inner support structure.

[0049] Preferably, the rod structure constituting the unit is divided into a straight rod and a curved rod, and the curvature of the curved rod is adjustable.

[0050] Preferably, the external frame structure is divided into a straight rod external frame structure and a curved rod external frame structure;

[0051] The internal support structure is divided into a straight rod internal support structure and a curved rod internal support structure.

[0052] Preferably, in the fourth step of the design process, the constructed bionic saddle-shaped unit specifically refers to: through Boolean operations, a bionic unit of a curved rod external frame structure and an internal support structure of a curved rod, a bionic unit of a curved rod external frame structure and an internal support structure of a straight rod, a bionic unit of a straight rod external frame structure and an internal support structure of a curved rod, and a bionic unit of a straight rod external frame structure and an internal support structure of a straight rod are formed respectively.

[0053] Preferably, in the bionic saddle-shaped unit, the diameter of the rod structure is 0.8 mm, but it can be adjusted according to actual conditions, and the minimum size is not less than the minimum forming size of the laser powder bed melting (LPBF) technology.

[0054] Preferably, the size (length×width×height) of the bionic saddle-shaped unit is 5.8×5.8×5.8 mm. 3 , but it can be adjusted according to actual conditions.

[0055] On the other hand, the present invention provides a lattice structure, which is derived from a bionic saddle-shaped unit as a filling unit cell;

[0056] The lattice structure is specifically formed by periodic arrangement of bionic saddle-shaped unit cells.

[0057] Preferably, the lattice structure is formed by a periodic arrangement of bionic units of a curved rod external frame structure and a curved rod internal support structure.

[0058] Preferably, the lattice structure is formed by a periodic arrangement of bionic units of a curved rod external frame structure and a straight rod internal support structure.

[0059] Preferably, the lattice structure is formed by a periodic arrangement of bionic units of a straight rod external frame structure and a curved rod internal support structure.

[0060] Preferably, the lattice structure is formed by a periodic arrangement of bionic units of a straight rod external frame structure and a straight rod internal support structure.

[0061] Preferably, the lattice structure is integrally formed by laser powder bed melting (LPBF) technology.

[0062] Embodiment 1

[0063] See also Figures 1 to 7 As shown, the bionic saddle-shaped unit of the present invention is inspired by the frustum structure of Campylodiscus. Nodes 1 to 5 are extracted. The lines connecting nodes 2, 3, 4, and 5 correspond to the skirt structure of the bionic object. The lines connecting nodes 3, 1, and 5 correspond to the ridge structure of the bionic object. The lines connecting nodes 2, 1, and 4 correspond to the rib structure of the bionic object. The extracted nodes and line elements are placed in a cube to form the wire frame structure of the bionic saddle-shaped unit. It is worth noting that the line segments between nodes are only one of the connection methods.

[0064] Furthermore, rods with the same diameter and circular cross-section are used to replace the wire frame structure to form a straight rod external support structure, a curved rod external support structure, a straight rod internal support structure and a curved rod internal support structure based on the rod structure; in this embodiment, the angle between the axes of two adjacent rods in the straight rod external frame structure is 131.8°, the angle between the rod 12 and the rod 14 in the straight rod internal support structure is 45°, the curved rod external frame structure and the curved rod internal support structure are generated by trigonometric cosine functions, and the diameter of the rod is 0.8 mm.

[0065] Furthermore, through Boolean operations, the external frame structure and the internal support structure are combined, and the corresponding nodes overlap to form four bionic saddle-shaped units. In this embodiment, the size of the bionic unit is 5.8×5.8×5.8mm 3 .

[0066] Embodiment 2

[0067] See also Figures 8 to 11 The figure shows the lattice structure of the present invention; the lattice structure is formed by periodically arranging bionic saddle-shaped units.

[0068] Furthermore, multiple bionic saddle-shaped units are arranged in a head (tail)-head (tail) connection to form a one-dimensional structure (Z axis) of the lattice structure, and the central nodes 1 of different bionic saddle-shaped units are in a straight line. The one-dimensional structure is expanded in another direction to form a two-dimensional plate structure (XZ plane), and further expanded to form a three-dimensional lattice structure (XYZ space). During the expansion process, the surrounding nodes of adjacent bionic saddle-shaped units overlap with each other and form constraints of the lattice structure, thereby regulating the mechanical properties of the structure.

[0069] Furthermore, in this embodiment, the lattice structure is composed of 6×6×6 bionic saddle-shaped cells, and 6 boundary bionic saddle-shaped units of a cube facing the lattice structure are trimmed to obtain a standard unit with a size of 30×30×30 mm3.

[0070] It is worth noting that other embodiments of the present invention can be obtained by adjusting the arrangement, quantity, size, etc. of the bionic saddle-shaped units.

[0071] Embodiment 3

[0072] See also Figure 12-13 , the lattice structure of the present invention is used for the design of the sandwich structure, and different mechanical properties are obtained by controlling the position of the thin plate. The design process can be briefly described as follows:

[0073] Step S1, selecting a desired lattice structure from the lattice structures of the present invention and determining a loading direction. In this embodiment, lattice structure 1 is selected;

[0074] Step S2, according to the size of the selected lattice structure, determine the thickness of the thin plate used. In this embodiment, the thickness of the thin plate is set to 3mm and the transverse area is 30×30mm. 2 ;

[0075] Step S3, placing a thin plate on the upper and lower surfaces of the lattice structure, with the lattice structure and the thin plate in surface contact without sliding;

[0076] Step S4, using relevant software to design the model and perform quality inspection.

[0077] The specific implementation of the embodiment is as follows:

[0078] The lattice structures 1 to 4 of the present invention are designed and characterized by the following methods:

[0079] Step 1, building a model; completing the model design of lattice structure 1 to lattice structure 4 by using Creo 6.0 modeling software, and the structural dimensions are as described in the embodiment;

[0080] Step 2: Structural forming: import the model into the slicing software Magics for discrete layering, and import the sliced ​​model data into the metal 3D printer for laser powder bed melting forming. Specifically, the powder spreading arm completes a single layer of powder spreading, selectively scans the metal powder according to the model data, completes the printing of a layer, the forming cylinder descends, the powder cylinder rises, and re-powdering is repeated until the structure is printed.

[0081] Step 3, performance characterization; quasi-static compression test was performed on lattice structures 1 to 4, the test was performed on a universal testing machine, and the compression rate was set to 1 mm / min; the obtained data was imported into Origin software to obtain the force-displacement curve of the lattice structure, as shown in the attached figure. Fig.14 shown.

[0082] In summary, the bionic saddle-shaped unit and its lattice structure proposed in the present invention can be integrated into a single unit by laser powder bed melting technology, and have adjustable performance, beneficial anisotropy, light weight and small model data volume, and have great potential for engineering applications.

[0083] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A bionic saddle-shaped unit, characterized in that: The bionic saddle-shaped unit is in the shape of a saddle, and includes four peripheral nodes, one central node and eight contour lines; the design process is as follows: The first step is to extract four surrounding nodes 2, 3, 4, 5 on the skirt and a central node 1 where the ridge and rib intersect, a total of five nodes, according to the structural characteristics of the ridge, rib and skirt of the saddle algae frustum; Determine a total of 8 connecting lines between nodes 1, 2, 3, 4 and 5; Step 2: Mark the five nodes 1, 2, 3, 4 and 5 in the cube respectively; The central node 1 is placed at the center of the cube, the surrounding nodes 2 and 4 are placed at the midpoints of the parallel edges of the upper surface of the cube, and the surrounding nodes 3 and 5 are placed at the midpoints of the parallel edges of the lower surface of the cube; And the connecting line through connecting 2-3 and the connecting line through connecting 4-5 are vertical in the space of the cube; Step 3: Connect the surrounding nodes 2-3-4-5 to form the outer frame contour of the unit, and connect the nodes 2-1-4 and 3-1-5 to form the inner support contour of the unit; Step 4: Combine the outer frame contour line and the inner support contour line through Boolean operation to form a bionic saddle-shaped unit; In the fourth step of the design process, the bionic saddle-shaped unit constructed specifically refers to: through Boolean operations, the bionic unit of the curved rod external frame structure and the curved rod internal support structure, the bionic unit of the curved rod external frame structure and the straight rod internal support structure, the bionic unit of the straight rod external frame structure and the curved rod internal support structure, and the bionic unit of the straight rod external frame structure and the straight rod internal support structure are respectively formed.

2. A bionic saddle-shaped unit according to claim 1, characterized in that: In the third step of the design process, the outer frame contour and the inner support contour of the forming unit are both made of rod structures with the same diameter and circular cross-section, namely, the outer frame structure and the inner support structure; The rod structure includes a straight rod and a curved rod, both of which have a diameter of 0.8 mm.

3. A lattice structure derived from the bionic saddle-shaped unit designed according to claim 1 as a filling unit cell; in, The lattice structure is specifically formed by periodic arrangement of bionic saddle-shaped unit cells.

4. A lattice structure as claimed in claim 3, characterized in that: The lattice structure is formed by the periodic arrangement of bionic units of the external frame structure of the curved rod and the internal supporting structure of the curved rod.

5. A dot matrix structure as claimed in claim 3, characterized in that: The lattice structure is formed by the periodic arrangement of bionic units of a curved rod external frame structure and a straight rod internal support structure.

6. A lattice structure as claimed in claim 3, characterized in that: The lattice structure is formed by the periodic arrangement of bionic units of a straight rod external frame structure and a curved rod internal support structure.

7. A dot matrix structure as claimed in claim 3, characterized in that: The lattice structure is formed by the periodic arrangement of bionic units of a straight rod external frame structure and a straight rod internal support structure.

8. The lattice structure according to any one of claims 3, characterized in that: The lattice structure is formed by laser powder bed fusion technology.

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