Gradient framework, structural materials, and applications of materials mimicking the shell of Sapindus mukorossi.

Abstract

This invention provides a gradient framework for a soapberry-like shell, a structural material, and the application of the structural material, belonging to the field of biomimetic industrial design technology. The gradient framework for the soapberry-like shell includes a toughening layer and a supporting layer. The toughening layer is suitable for the inner thick-walled cell region of the soapberry-like shell to provide toughness for the gradient framework; the supporting layer is formed on the toughening layer and is suitable for the outer fibrous region of the soapberry-like shell to provide strength and rigidity for the gradient framework.

Description

Technical Field

[0001] At least one embodiment of the present invention belongs to the field of biomimetic industrial design technology, specifically relating to a gradient skeleton, structural material, and application of a structure material that mimics the shell of a soapberry plant. Background Technology

[0002] The complex, multi-level structure of biomaterials allows them to balance strength and toughness, enabling the use of ordinary materials to achieve powerful performance. Many plants in nature have evolved hard shells to protect their seeds; for example, edible nuts such as walnuts, pistachios, and macadamia nuts have had their shell structures extensively studied. The soapberry tree is a perennial deciduous tree whose seeds are nearly spherical, dark brown, and have a hard, wear-resistant shell, but the structure of this shell has not yet been studied. Summary of the Invention

[0003] In view of this, in order to at least partially solve at least one of the aforementioned technical problems, the present invention provides a gradient skeleton mimicking the shell of Sapindus mukorossi, a structural material, and an application of the structural material.

[0004] According to one embodiment of the present invention, a gradient framework mimicking the shell of a Sapindus mukorossi plant is provided, comprising: a toughening layer and a supporting layer. The toughening layer is applied to the inner thick-walled cell region of the Sapindus mukorossi shell to provide toughness for the gradient framework; the supporting layer is formed on the toughening layer and is applied to the outer fibrous region of the Sapindus mukorossi shell to provide strength and rigidity for the gradient framework.

[0005] According to another aspect of the present invention, a structural material is provided, comprising: the aforementioned gradient skeleton and a protective layer; wherein the protective layer is formed on a support layer of the gradient skeleton.

[0006] According to another aspect of the present invention, an application of the above-described structural material is provided, including its use as a shell for any of aircraft, aviation equipment, marine equipment, and construction equipment.

[0007] According to embodiments of the present invention, a gradient skeleton mimicking the shell of the soapberry tree is provided, comprising a toughening layer and a supporting layer. The toughening layer mimics the inner structure of the soapberry shell to provide toughness to the entire gradient skeleton; the supporting layer mimics the outer structure of the soapberry shell to provide strength and rigidity to the entire gradient skeleton. The gradient skeleton provided by this embodiment of the invention imitates the structure of the soapberry shell. When subjected to external forces, the supporting layer can effectively disperse and resist these external forces, while the toughening layer can absorb them. The two layers work together to prevent the gradient skeleton from deforming or breaking, thereby protecting the safety of internal components. Furthermore, the gradient skeleton mimicking the soapberry shell provided by this invention can be used as a structural material for further use in the manufacture of shells for aircraft, aviation equipment, marine equipment, construction equipment, etc. Attached Figure Description

[0008] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0009] Figure 1 An optical photograph showing the overall morphology and cross-section of a Sapindus mukorossi seed;

[0010] Figure 2 A partial scanning electron microscope image of the outer shell of a soapberry plant;

[0011] Figure 3 A scanning electron microscope image of the outer fibrous region of the Sapindus mukorossi shell;

[0012] Figure 4 A scanning electron microscope image of the cross-section of the outer fibrous region of the Sapindus mukorossi shell;

[0013] Figure 5 Micro-CT image of the outer fibrous region of the Sapindus mukorossi shell;

[0014] Figure 6 A simulated schematic diagram of the outer fibrous region of the Sapindus mukorossi shell;

[0015] Figure 7 A scanning electron microscope image of the inner thick-walled cell region of the Sapindus mukorossi shell;

[0016] Figure 8 A scanning electron microscope image showing the connection between two adjacent cells in the inner thick-walled cell region of the Sapindus mukorossi shell;

[0017] Figure 9 A schematic diagram simulating the inner thick-walled cell region of the Sapindus mukorossi shell;

[0018] Figure 10 A simulated schematic diagram of the cross-section of the inner thick-walled cell region of the Sapindus mukorossi shell;

[0019] Figure 11 A diagram showing the variation in the aspect ratio of thick-walled cells in the inner layer of the Sapindus mukorossi shell at different depths from the epidermis;

[0020] Figure 12 A schematic diagram showing the division of the inner and outer shells of Sapindus mukorossi during the three-point bend test;

[0021] Figure 13 The graphs obtained from the three-point bending test on the inner and outer layers of the Sapindus mukorossi shell;

[0022] Figure 14 The graphs obtained from hardness tests performed on the inner and outer layers of the Sapindus mukorossi shell are shown.

[0023] Figure 15 The image shows a magnified scanning electron microscope image of the entire inner thick-walled cell region of the Sapindus mukorossi shell near the outer layer, as well as a localized area A.

[0024] Figure 16 The image shows a magnified scanning electron microscope image of the entire thick-walled cell region of the inner layer of the Sapindus mukorossi shell near the center of the shell, as well as a localized area B.

[0025] Figure 17 The image shows a magnified scanning electron microscope image of the outer fibrous region of the Sapindus mukorossi shell and a localized area of ​​region C.

[0026] Figure 18 This is a three-dimensional schematic diagram of a gradient skeleton according to an embodiment of the present invention;

[0027] Figure 19 This is a side view schematic diagram of a gradient skeleton according to an embodiment of the present invention;

[0028] Figure 20 for Figure 19 A schematic diagram of the decomposition process;

[0029] Figure 21 A three-dimensional schematic diagram of the support layer, transition layer and buffer layer of the gradient skeleton according to an embodiment of the present invention;

[0030] Figure 22 This is a schematic diagram of the gradient skeleton design according to an embodiment of the present invention;

[0031] Figure 23 This is a side view of the buffer layer and the first substrate of a gradient skeleton according to an embodiment of the present invention;

[0032] Figure 24 This is a top view of the buffer layer and the first substrate of a gradient skeleton according to an embodiment of the present invention;

[0033] Figure 25This is a partially enlarged schematic diagram of the buffer layer of the gradient skeleton according to an embodiment of the present invention;

[0034] Figure 26 This is a three-dimensional schematic diagram of a buffer subunit of a gradient skeleton according to an embodiment of the present invention;

[0035] Figure 27 This is a side view schematic diagram of the transition layer of the gradient skeleton according to an embodiment of the present invention;

[0036] Figure 28 This is a top view schematic diagram of the transition layer of the gradient skeleton according to an embodiment of the present invention;

[0037] Figure 29 This is a partially enlarged schematic diagram of the transition layer of a gradient skeleton according to an embodiment of the present invention;

[0038] Figure 30 This is a two-dimensional simulation diagram of a transition subunit according to an embodiment of the present invention;

[0039] Figure 31 This is a three-dimensional simulation diagram of a transition subunit according to an embodiment of the present invention;

[0040] Figure 32 This is a three-dimensional schematic diagram of the transition subunit of the gradient skeleton according to an embodiment of the present invention;

[0041] Figure 33 This is a top view schematic diagram of the support layer of a gradient skeleton according to an embodiment of the present invention;

[0042] Figure 34 This is a partially enlarged schematic diagram of the support layer of a gradient skeleton according to an embodiment of the present invention;

[0043] Figure 33 This is a top view schematic diagram of the support layer of a gradient skeleton according to an embodiment of the present invention;

[0044] Figure 34 This is a partially enlarged schematic diagram of the support layer of a gradient skeleton according to an embodiment of the present invention;

[0045] Figure 35 This is a schematic diagram of the compression failure process of a 3D printed gradient skeleton in a compression experiment according to an embodiment of the present invention;

[0046] Figure 36 Based on Figure 35 The stress-strain curve obtained from the compression experiment.

[0047] Symbol explanation:

[0048] 100. Sapindus mukorossi outer shell;

[0049] 101, Outer fiber region; 1011, Fiber bundle;

[0050] 102. Inner thick-walled cell region; 1021. Thick-walled cells;

[0051] 103. The inner thick-walled cell region near the outer layer; 1031. The thick-walled cells in the inner thick-walled cell region near the outer layer;

[0052] 104. The inner thick-walled cell region near the center of the outer shell; 1041. The thick-walled cells in the inner thick-walled cell region near the center of the outer shell;

[0053] 200. Gradient skeleton;

[0054] 201. First substrate;

[0055] 202, Buffer layer; 2021, Buffer sub-unit; 20211, Cylindrical section; 20212, Frustum section;

[0056] 203, Transition Layer; 2031, Transition Subunit; 20311, Columnar Section; 20312, Frustum Section;

[0057] 204. Second substrate;

[0058] 205. Support layer; 2051. Cylinder body;

[0059] 300, 3D printed gradient skeleton;

[0060] 400. Pressure components. Detailed Implementation

[0061] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0062] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0063] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0064] The concept of this invention lies in revealing the layered microstructure of the Sapindus mukorossi shell and designing a gradient framework with a multi-level sub-gradient structure that mimics the shell of the Sapindus mukorossi. The inventors discovered that Sapindus mukorossi, a perennial deciduous tree, has nearly spherical, dark brown seeds with a hard, wear-resistant shell exhibiting strong compressive strength and toughness. Therefore, the inventors conducted various research tests and analyses on the properties of Sapindus mukorossi seeds, which contributes to the understanding and design of strong and tough protective shell materials.

[0065] Figure 1 Optical photographs showing the overall morphology and cross-section of Sapindus mukorossi seeds. The seeds are nearly spherical, with a shell thickness of 2-3 mm. Figure 2 This is a partial scanning electron microscope image of the Sapindus mukorossi shell. The Sapindus mukorossi shell 100 can be mainly divided into two parts: the outer fibrous region 101 (~500 μm) and the inner thick-walled cell region 102 (~1500 μm).

[0066] Figure 3 This is a scanning electron microscope image of the outer fibrous region of the Sapindus mukorossi plant's outer shell. Figure 4 This is a scanning electron microscope image of a cross-section of the outer fibrous region of the Sapindus mukorossi shell. Figure 5 This is a micro-computed tomography (Micro-CT) image of the outer fibrous region of the Sapindus mukorossi plant. From... Figures 3-5 It can be seen that the outer fiber region 101 is composed of vertically arranged hollow fiber bundles 1011, which can provide strength and hardness to the Sapindus mukorossi shell 100. Therefore, the outer fiber region 101 of the Sapindus mukorossi shell 100 was simulated. Figure 6 This is a simulated schematic diagram of the outer fibrous region of the Sapindus mukorossi shell.

[0067] Figure 7 This is a scanning electron microscope image of the inner thick-walled cell region of the Sapindus mukorossi shell. Figure 8 This is a scanning electron microscope image showing the connection between two adjacent cells in the inner thick-walled cell region of the Sapindus mukorossi shell. Figures 7-8 It can be seen that the inner thick-walled cell region 102 is composed of thick-walled cells 1021 with varying sizes, which can enhance the overall toughness of the Sapindus mukorossi shell 100. Therefore, the inner thick-walled cell region 102 of the Sapindus mukorossi shell 100 was simulated. Figure 9 This is a simulated schematic diagram of the inner thick-walled cell region of the Sapindus mukorossi shell. Figure 10 This is a simulated schematic diagram of the cross-section of the inner thick-walled cell region of the Sapindus mukorossi shell. Figure 11 This diagram illustrates the variation in the aspect ratio of thick-walled cells in the inner layer of the Sapindus mukorossi shell at different depths from the epidermis. Thick-walled cells 1021 gradually transition from a long cylindrical shape to a spherical shape, with the aspect ratio decreasing linearly from the outer layer to the inner layer, gradually approaching 1. Thick-walled cells 1021 consist of multiple layers of cell walls and internal inclusions. The inclusions within adjacent cells are connected by channels in the cell walls, resulting in a tighter bond between adjacent cells.

[0068] The inventor conducted a three-point bending experiment on the inner and outer layers of the Sapindus mukorossi shell 100. Figure 12 This is a schematic diagram showing the division of the inner and outer shells of Sapindus mukorossi during the three-point bend test. Figure 13 The graphs are obtained from a three-point bend test performed on the inner and outer layers of the Sapindus mukorossi shell. From... Figures 12-13 It can be seen that the outer fibrous region 101 has a higher flexural modulus and flexural strength, and the bending curve indicates that this part is more prone to brittle fracture; the curve of the inner thick-walled cell region 102 shows a longer deformation process, indicating that this part is more prone to ductile fracture. At the same time, hardness tests were performed on the inner thick-walled cell region 102 and the outer fibrous region 101 of the Sapindus mukorossi shell 100. Figure 14 The graphs are obtained from hardness tests performed on the inner and outer layers of the Sapindus mukorossi shell. From... Figure 14 It can be seen that the vertical fiber bundles 1011 in the outer fibrous region 101 are harder and can resist stronger indentation and damage, while the thick-walled cells 1021 in the inner thick-walled cell region 102 are less hard. Therefore, the structure of the inner and outer layers of the Sapindus mukorossi shell makes different mechanical contributions to the overall shell structure, with the outer fibrous region mainly providing strength and hardness, while the inner thick-walled cell region mainly increasing toughness.

[0069] The inventors also studied the inner thick-walled cell region 102 of the Sapindus mukorossi shell 100. Figure 15 This is a magnified scanning electron microscope image of the entire inner thick-walled cell region of the Sapindus mukorossi shell, near the outer layer, and a localized area A. Figure 16 This is a magnified scanning electron microscope image of the entire thick-walled cell region of the inner layer of the Sapindus mukorossi shell near the center of the shell, and a localized area B. From Figures 15-16It can be seen that the thick-walled cells 1031 in the inner layer of the Sapindus mukorossi shell 100 near the outer layer 103 are long columnar, arranged in columns and multiple columns side by side; the thick-walled cells 1041 in the inner layer of the Sapindus mukorossi shell 100 near the center of the shell 104 are similar to spheres, arranged in layers and stacked, but the cells are compressed during the stacking process, so they present an irregular shape.

[0070] The inventors also studied the outer fibrous region 101 of the Sapindus mukorossi shell 100. Figure 17 This is a magnified scanning electron microscope image of the entire outer fibrous region of the Sapindus mukorossi shell and a localized area of ​​region C. From Figure 17 It can be seen that the outer fibrous region 101 of the Sapindus mukorossi shell 100 is composed of vertically arranged hollow fiber bundles 1011.

[0071] Based on the above research, if the outer shell of Sapindus mukorossi 100 has only one layer of vertically arranged fiber bundles 1011, it can resist pressure but is easy to split; if the outer shell of Sapindus mukorossi 100 has only one layer of isotropic thick-walled cells 1021, it will have a stronger ability to resist crack propagation, good toughness, but low hardness and weak compressive strength.

[0072] Based on cross-sectional observations of numerous Sapindus mukorossi shells 100, the inventors divided them into an outer fibrous region 101 and an inner thick-walled cell region 102. They further observed and analyzed the microscopic structure of the outer fibrous region 101 and the inner thick-walled cell region 102, and experimentally tested their mechanical properties. Based on the results of these observations and experiments, the gradient skeleton of this invention was proposed. This invention provides a gradient skeleton mimicking the Sapindus mukorossi shell, a structural material, and its application. By imitating the structure of the Sapindus mukorossi shell, a gradient skeleton possessing strength, hardness, and toughness is constructed, providing a new solution for shell reinforcement structures in high-performance structural materials.

[0073] Figure 18 This is a three-dimensional schematic diagram of a gradient skeleton according to an embodiment of the present invention; Figure 19 This is a side view schematic diagram of a gradient skeleton according to an embodiment of the present invention; Figure 20 for Figure 19 Schematic diagram of the decomposition Figure 21 A three-dimensional schematic diagram of the support layer, transition layer and buffer layer of the gradient skeleton according to an embodiment of the present invention; Figure 22 This is a schematic diagram of the gradient skeleton design according to an embodiment of the present invention.

[0074] Specifically, see Figures 18-22According to one embodiment of the present invention, a gradient framework 200 mimicking the shell of a Sapindus mukorossi plant is provided, comprising a toughening layer and a supporting layer 205. The toughening layer is applied to the inner thick-walled cell region 102 of the mimicking the shell of a Sapindus mukorossi plant 100 to provide toughness for the gradient framework 200; the supporting layer 205 is formed on the toughening layer and is applied to the outer fibrous region 101 of the mimicking the shell of a Sapindus mukorossi plant 100 to provide strength and rigidity for the gradient framework 200.

[0075] In an embodiment of the present invention, a gradient skeleton 200 mimicking the structural features of a Sapindus mukorossi shell is provided, comprising a toughening layer and a supporting layer 205. The toughening layer mimics the structure of the inner thick-walled cell region 102 of the Sapindus mukorossi shell 100, providing toughness to the entire gradient skeleton 200; the supporting layer 205 mimics the structure of the outer fibrous region 101 of the Sapindus mukorossi shell 100, providing strength and rigidity to the entire gradient skeleton 200. The gradient skeleton provided in this embodiment of the present invention imitates the structure of the Sapindus mukorossi shell. When subjected to external forces, the supporting layer effectively disperses and resists these external forces, while the toughening layer absorbs them. The two layers work together to prevent the gradient skeleton from deforming or breaking, thereby protecting the safety of the internal components.

[0076] Figure 23 This is a side view of the buffer layer and the first substrate of a gradient skeleton according to an embodiment of the present invention; Figure 24 This is a top view of the buffer layer and the first substrate of a gradient skeleton according to an embodiment of the present invention; Figure 25 This is a partially enlarged schematic diagram of the buffer layer of the gradient skeleton according to an embodiment of the present invention; Figure 26 This is a three-dimensional schematic diagram of a buffer subunit of a gradient skeleton according to an embodiment of the present invention; Figure 27 This is a side view schematic diagram of the transition layer of the gradient skeleton according to an embodiment of the present invention; Figure 28 This is a top view schematic diagram of the transition layer of the gradient skeleton according to an embodiment of the present invention; Figure 29 This is a partially enlarged schematic diagram of the transition layer of a gradient skeleton according to an embodiment of the present invention; Figure 30 This is a two-dimensional simulation diagram of a transition subunit according to an embodiment of the present invention; Figure 31 This is a three-dimensional simulation diagram of a transition subunit according to an embodiment of the present invention; Figure 32 This is a three-dimensional schematic diagram of the transition subunit of the gradient skeleton according to an embodiment of the present invention.

[0077] According to an embodiment of the present invention, see Figures 23-32 The gradient framework 200 further includes a first substrate 201 and a second substrate 204. A toughening layer is formed on the first substrate 201, which provides support for the entire gradient framework 200. The second substrate 204 is formed between the toughening layer and the support layer 205, providing support for the support layer 205.

[0078] According to an embodiment of the present invention, the toughness layer of the gradient framework 200 includes a buffer layer 202 and a transition layer 203. The buffer layer 202 includes a plurality of buffer sub-units 2021, which are arranged in a layered structure at intervals in a direction parallel to the gradient framework 200, and the multiple layered structures are stacked to form a multi-layer stacked structure. The transition layer 203 is formed on the buffer layer 202 and includes a plurality of transition sub-units 2031, which are arranged in a columnar structure in a direction perpendicular to the gradient framework 200, and the multiple columns of columnar structures are arranged side by side at intervals to form a multi-column stacked structure.

[0079] In an embodiment of the present invention, the buffer subunits 2021 and transition subunits 2031 in the gradient framework 200 are configured to resemble the arrangement of two thick-walled cells in the Sapindus mukorossi shell 100. The buffer subunits 2021 are arranged isotropically, which can resist external forces and increase the toughness of the gradient framework; the transition subunits 2031 are arranged vertically, which can resist sharp damage and provide strength and rigidity to the gradient framework.

[0080] According to an embodiment of the present invention, both the buffer subunit 2021 and the transition subunit 2031 include: a cylindrical portion 20211 / 20311 and two frustum portions 20212 / 20312. The two frustum portions 20212 / 20312 are respectively formed at both ends of the cylindrical portion 20211 / 20311, and the area of ​​the end face of each frustum portion 20212 / 20312 away from the cylindrical portion 20211 / 20311 is smaller than the cross-sectional area of ​​the cylindrical portion 20211 / 20311; preferably, the cylindrical portion 20211 / 20311 is a regular prism, the frustum portions 20212 / 20312 are regular frustums, and the number of lateral faces of the regular prism and the regular frustums are the same.

[0081] In embodiments of the present invention, the buffer subunit 2021 and the transition subunit 2031 are constructed in a shape similar to the two thick-walled cells in the Sapindus mukorossi shell 100, and are formed by stacking columnar portions 20211 / 20311 and frustum portions 20212 / 20312, including stacks of right cylinders and right frustums, and stacks of right prisms and right frustums. In some embodiments, the columnar portions 20211 / 20311 can be any one of square prisms, pentagonal prisms, hexagonal prisms, cylinders, elliptical cylinders, etc., or a combination of at least two of them, and the frustum portions 20212 / 20312 can be any one of square frustums, pentagonal frustums, hexagonal frustums, truncated cones, elliptical frustums, etc., or a combination of at least two of them.

[0082] According to embodiments of the present invention, the buffer subunits 2021 are the same, similar, or different in size and shape; the frustum portions 20212 belonging to two adjacent buffer subunits 2021 in the buffer layer 202 are arranged in a staggered manner in height. The height of the columnar portions 20311 in at least some of the transition subunits 2031 gradually decreases along the direction close to the buffer layer 202 to approximate the shape of the thick-walled cells of the actual Sapindus mukorossi shell; the heights of adjacent frustum portions 20312 in two adjacent rows of transition subunits 2031 in the transition layer 203 are different. This ensures that the gradient skeleton has compressive strength and toughness in the thickness direction.

[0083] In embodiments of the present invention, the structure of the buffer subunit 2021 and the transition subunit 2031 is modeled after the structure of the inner thick-walled cell region 102 in the Sapindus mukorossi shell 100. The aspect ratio of the thick-walled cells 1031 in the inner thick-walled cell region of the Sapindus mukorossi shell 100 near the outer layer 103 gradually decreases, and adjacent rows of thick-walled cells are staggered in height. The thick-walled cells 1041 in the inner thick-walled cell region of the Sapindus mukorossi shell 100 near the center 104 of the shell are arranged in a staggered pattern in height between the upper and lower layers. Based on this, the buffer subunit 2021 and the transition subunit 2031 in the gradient framework 200 of the present invention are configured with a size structure similar to the arrangement of the two thick-walled cells in the Sapindus mukorossi shell 100.

[0084] According to an embodiment of the present invention, both the buffer subunit 2021 and the transition subunit 2031 have through holes at their center positions; the cylindrical portions 20211 / 20311 have openings on their sides, and the openings on the sides of two adjacent cylindrical portions 20211 / 20311 in the same layer are connected by a hollow cylinder; preferably, a filling material is filled between adjacent buffer subunits 2021 and between adjacent transition subunits 2031.

[0085] In embodiments of the present invention, considering the interconnection between the thick-walled cells 1021 of the Sapindus mukorossi outer shell 100, it facilitates the flow of intracellular inclusions and stabilizes the connection between adjacent cells. The gradient framework 200 of the present invention has openings on the side surfaces of the columnar portions 20211 / 20311 of the buffer sub-units 2021 and transition sub-units 2031 to allow communication between adjacent buffer sub-units 2021 and adjacent transition sub-units 2031. Simultaneously, filling material is used to fill the openings and between adjacent buffer sub-units 2021 and adjacent transition sub-units 2031, enabling the gradient framework 200 to withstand stronger external forces and possessing bending toughness.

[0086] Furthermore, the present invention has designed the specific structure of the support layer 205 as follows. Figure 33 This is a top view schematic diagram of the support layer of a gradient skeleton according to an embodiment of the present invention; Figure 34This is a partially enlarged schematic diagram of the support layer of a gradient skeleton according to an embodiment of the present invention.

[0087] According to an embodiment of the present invention, see Figures 33-34 The support layer 205 includes a plurality of cylindrical bodies 2051 arranged side by side at intervals in a direction parallel to the gradient skeleton; preferably, the height-to-outer diameter ratio of the cylindrical bodies 2051 is 10-50:1; more preferably, the inner-outer diameter ratio of the cylindrical bodies 2051 is 1-3:4.

[0088] In an embodiment of the present invention, the structural features of the outer fiber region 101 and fiber bundle 1011 in the outer shell 100 of Sapindus mukorossi are simulated. The gradient skeleton 200 of the present invention is provided with a support layer 205 composed of parallel and spaced cylindrical bodies 2051, and the size and shape of the cylindrical bodies 2051 are simulated to represent the fiber bundle 1011.

[0089] According to an embodiment of the present invention, the height ratio of the support layer 205, transition layer 203, and buffer layer 202 is 2.5-3.5: 4.5-5.5: 1.5-2.5. The diameter ratio of the cylinder 2051, transition sub-unit 2031, and buffer sub-unit 2021 is 1-2: 4-6: 8-12. The height ratio of different parts of the gradient skeleton 200 and the size ratio of the sub-units of different parts are set according to the size distribution between different layers of the Sapindus mukorossi shell 100.

[0090] In embodiments of the present invention, the gradient framework 200 can be prepared by 3D printing. First, a model of the gradient framework is established, then a suitable material for 3D printing is selected, such as resin materials (e.g., BIO resin, GR resin, HTL resin, ST1400 resin, RG resin, HT-200, TOUGH, sacrificial resin, Formula1μ, Loctite 3D 3955), and finally the gradient framework is printed. Alternatively, it can be constructed by layering units of different shapes and aspect ratios; in this case, the first substrate 201 and the second substrate 204 can be omitted as needed. Furthermore, the self-assembly of different nanomaterials can be controlled. First, a layer of columnar material is arranged vertically, then units of different lengths are arranged to form the gradient framework, and finally, the gradient framework is fixed using chemical means; in this case, the first substrate 201 and the second substrate 204 can be omitted as needed. Here, the implementation method of the gradient framework is not limited, and users can choose according to their needs.

[0091] According to another aspect of the present invention, a structural material is provided, comprising: the aforementioned gradient skeleton 200 and a protective layer; wherein the protective layer is formed on the support layer 205 of the gradient skeleton 200. The protective layer provides a smooth outer surface to the gradient skeleton, while also preventing corrosion and facilitating cleaning.

[0092] According to embodiments of the present invention, powders, granules, melts, etc., with relatively low viscosity and flexibility can be selected to fill the voids within the gradient skeleton. For example, the gaps between buffer sub-units, transition sub-units, cylinders, cylindrical parts, frustums, etc., and various holes (e.g., through holes and openings) can be filled to further improve the strength and toughness of the gradient skeleton. After filling, these powders, granules, melts, etc., are subjected to solidification treatment.

[0093] In some embodiments, the support layer of the gradient skeleton of the present invention can be directly adhered to the prefabricated housing of the relevant equipment (e.g., construction equipment) without the need for a protective layer.

[0094] According to another aspect of the present invention, an application of the above-described structural material is provided, including its use as a shell for any of aircraft, aviation equipment, marine equipment, and construction equipment.

[0095] As an example, an embodiment of the present invention provides a 3D printed gradient skeleton 300 prepared by 3D printing, the preparation method of which includes: establishing a gradient skeleton model, selecting materials, and printing the gradient skeleton, as detailed below.

[0096] First, the dimensions of each part in the gradient skeleton 200 are established. The height ratio of the support layer 205, transition layer 203, and buffer layer 202 is 1:3:1. The height-to-outer diameter ratio of the cylinder 2051 is 10:1; the height-to-outer diameter ratio of the transition subunit 2031 includes 3.6:1, 3.2:1, 2.8:1, and 2.4:1, and the diameters of the transition subunits 2031 are all the same; the height-to-outer diameter ratio of the buffer subunit 2021 is 1:1. The cylindrical portions 20211 / 20311 of the buffer subunit 2021 and the transition subunit 2031 are designed to be regular hexagonal prisms, and the frustum portions 20212 / 20312 are also regular hexagonal frustums.

[0097] The specific dimensions of the cylinder 2051 are as follows: inner diameter is 0.2mm, outer diameter is 0.4mm, height is 3.8mm, the interval between adjacent cylinders 2051 is 0.1mm, and a second base plate 204 of 0.2mm is provided under the cylinder 2051 as support.

[0098] The specific dimensions of the transition subunit 2031 are as follows: The total length of the transition subunit 2031 is available in several types: 3.6mm, 3.2mm, 2.8mm, 2.4mm, and 1.2mm. Each transition subunit 2031 has two regular hexagonal frustums at both ends and a section in the middle consisting of regular hexagonal prisms of varying lengths. The height of the regular hexagonal frustums at both ends is 0.36mm, the side length of the top face is 0.35mm, and the side length of the bottom face is 0.58mm. A through hole with a side length of 0.12mm is opened at the center of the assembled transition subunit 2031. Adjacent transition subunits 2031 are spaced 0.1mm apart. Each side of the regular hexagonal prism has an opening with a diameter of 0.2mm, connected by a pipe with an outer diameter of 0.4mm and an inner diameter of 0.2mm. Each transition subunit 2031 is arranged in a staggered manner in the longitudinal direction. Since the regular hexagonal prism in the transition subunit 2031 has six sides, the columnar structure formed by six rows of transition subunits 2031 can surround the columnar structure formed by one row of transition subunits 2031. At this time, the height of the regular hexagonal frustum of the transition subunit 2031 in the central columnar structure near the support layer is lower than the height of the regular hexagonal frustum of the adjacent transition subunits 2031.

[0099] The specific dimensions of the buffer subunit 2021 are as follows: the height of the two end hexagonal frustums of the buffer subunit 2021 is 0.4 mm, the side length of the top surface is 0.5 mm, the side length of the bottom surface is 1.15 mm, and the height of the middle hexagonal prism is 1.2 mm. A through hole with a side length of 0.12 mm is opened at the center of the assembled buffer subunit 2021. Adjacent buffer subunits 2021 are spaced 0.2 mm apart. Each side of the hexagonal prism has an opening with a diameter of 0.2 mm, connected by a pipe with an outer diameter of 0.4 mm and an inner diameter of 0.2 mm. Because the hexagonal prism in the buffer subunit 2021 has six sides, in a layered structure composed of one layer of buffer subunits 2021, the outer side of a transition subunit 2031 can surround six buffer subunits 2021. The hexagonal frustums in adjacent layers of the layered structure are arranged at the same height in a staggered pattern.

[0100] At the junction of transition layer 203 and buffer layer 202, the columnar structure of transition subunit 2031 in transition layer 203, which is lower than the surrounding hexagonal frustum of transition subunit 2031, is located at the gap between two adjacent hexagonal frustums of buffer subunit 2021 in buffer layer 202; the columnar structure of transition subunit 2031 in transition layer 203, which is higher than the central hexagonal frustum of transition subunit 2031, is located at the top surface of two adjacent hexagonal frustums of buffer subunit 2021 in buffer layer 202.

[0101] Next, the material for 3D printing is selected. In some embodiments, a material with a certain degree of hardness and flexibility can be selected to prepare the gradient skeleton 200. For example, a photocurable biocompatible resin (BIO resin) can be selected as the 3D printing material.

[0102] Finally, a 3D-printed gradient skeleton 300 is created using BIO resin. Powders, granules, or melts with relatively low viscosity and flexibility can be selected to fill the gaps between the buffer sub-units, transition sub-units, cylinders, cylindrical parts, and frustums of the 3D-printed gradient skeleton 300, as well as various holes (such as through holes and openings), to further improve the strength and toughness of the gradient skeleton. After filling, these powders, granules, and melts are cured.

[0103] Furthermore, a compression experiment was conducted on the 3D-printed gradient skeleton 300. Specifically, the 3D-printed gradient skeleton 300 was placed between pressure members 400, and external force was applied to the 3D-printed gradient skeleton 300 by the pressure members 400.

[0104] Figure 35 This is a schematic diagram of the compression failure process of a 3D printed gradient skeleton in a compression experiment according to an embodiment of the present invention; Figure 36 Based on Figure 35 The stress-strain curve obtained from the compression experiment.

[0105] from Figure 35 It can be seen that when the 3D printed gradient skeleton 300 of the present invention is subjected to external forces, the support layer can effectively disperse and resist these external forces, and the toughness layer can absorb these external forces. The two layers work together to make the 3D printed gradient skeleton 300 less prone to deformation or breakage. From Figure 36 It can be calculated that the density of the 3D printed gradient skeleton 300 is 0.46 g / cm³. 3 The compressive elastic modulus is 23.5 MPa, and the maximum stress before failure is 3.65 MPa.

[0106] It should be noted that the embodiments of the present invention provide a gradient skeleton that mimics the shell of a Sapindus mukorossi plant. Although the shape, outline, structure, size, and / or material of each part (e.g., the toughening layer, support layer, buffer layer, transition layer, buffer sub-unit, transition sub-unit, support layer cylinder, etc.) have been described in the above embodiments, these are exemplary and not intended to limit the present invention. Those skilled in the art will understand that, based on the inventive concept of the present invention, in order to mimic the shell of a Sapindus mukorossi plant as closely as possible, modifications, substitutions, and deformations can be made to the shape, outline, structure, size, and material of each part without departing from the scope of protection of the present invention.

[0107] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gradient skeleton mimicking the shell of a soapberry tree, comprising: A tough layer in the thick-walled cell region of the inner shell of the soapberry plant is used to provide toughness for the gradient skeleton. as well as A support layer, mimicking the outer fibrous region of the Sapindus mukorossi shell, is formed on the tough layer to provide strength and rigidity to the gradient skeleton; The toughness layer includes: A buffer layer includes multiple buffer sub-units, which are arranged in a layered structure at intervals in a direction parallel to the gradient skeleton, and multiple layers of the layered structure are stacked to form a multi-layered structure; and A transition layer is formed on the buffer layer. The transition layer includes multiple transition sub-units. The transition sub-units are arranged in a columnar structure in a direction perpendicular to the gradient skeleton. Multiple columns of the columnar structures are arranged side by side with intervals to form a multi-column stacked structure. The support layer includes a plurality of cylindrical bodies arranged side by side at intervals in a direction parallel to the gradient skeleton.

2. The gradient skeleton according to claim 1, wherein, The gradient skeleton also includes: A first substrate, wherein the toughening layer is formed on the first substrate; and A second substrate is formed between the tough layer and the support layer.

3. The gradient skeleton according to claim 2, wherein, Both the buffer subunit and the transition subunit include: Columnar part; and Two frustum portions are formed at both ends of the cylindrical portion, and the area of ​​the end face of each frustum portion away from the cylindrical portion is smaller than the cross-sectional area of ​​the cylindrical portion.

4. The gradient skeleton according to claim 3, wherein, The cylindrical part is a regular prism, the frustum part is a regular frustum, and the number of lateral faces of the regular prism and the regular frustum are the same.

5. The gradient skeleton according to claim 4, wherein, The buffer subunits are identical in size and shape; The frustum portions belonging to adjacent buffer sub-units in the buffer layer are arranged in a staggered manner in height; and / or The height of the cylindrical portion in at least a portion of the transition subunit gradually decreases along the direction close to the buffer layer; In the transition layer, the heights of adjacent frustum sections in two adjacent columns of transition sub-units are different.

6. The gradient skeleton according to claim 4, wherein, Both the buffer subunit and the transition subunit have through holes at their center. The side of the cylindrical part is provided with an opening, and the openings on the side of two adjacent cylindrical parts on the same layer are connected by a hollow cylinder.

7. The gradient skeleton according to claim 6, wherein, Filler material is used to fill the spaces between adjacent buffer sub-units and between adjacent transition sub-units.

8. The gradient skeleton according to claim 1, wherein, The ratio of the height to the outer diameter of the cylinder is 10-50:

1.

9. The gradient skeleton according to claim 8, wherein, The ratio of the inner to outer diameter of the cylinder is 1-3:

4.

10. The gradient skeleton according to any one of claims 2-9, wherein, The height ratio of the support layer, transition layer, and buffer layer is 2.5-3.5: 4.5-5.5: 1.5-2.5; and / or The diameter ratio of the cylinder, transition subunit, and buffer subunit is 1-2:4-6:8-12.

11. The gradient skeleton according to claim 1, wherein, The height-to-outer-diameter ratio of the buffer subunit is 1:1; and / or The height-to-outer diameter ratio of the transition subunit is 1-8:

1.

12. A structural material mimicking the shell of a soapberry tree, comprising: The gradient skeleton as described in any one of claims 1-11; as well as A protective layer is formed on the support layer.

13. The application of a structural material mimicking the shell of Sapindus mukorossi as described in claim 12, wherein, The structural material is used as the outer shell of any of the following: aviation equipment, marine equipment, and construction equipment.

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