A bionic impact-resistant sandwich panel based on Bouligand structure and its preparation method and application

Abstract

The present invention discloses a bionic impact-resistant sandwich panel based on a Bouligand structure, comprising a Bouligand spiral stacking matrix structure, wherein the Bouligand spiral stacking matrix structure is formed by stacking a plurality of elementary structures in the same direction in sequence and rotating at a preset angle, wherein the elementary structures include upper and lower partitions and asymmetric walls uniformly distributed between the upper and lower partitions and perpendicular to the planes of the upper and lower partitions, wherein the asymmetric walls are in the shape of trigonometric functions with different upper and lower amplitudes and the same period. The present invention also discloses a preparation method and application of the bionic impact-resistant sandwich panel based on the Bouligand structure. The bionic impact-resistant sandwich panel of the present invention has excellent impact resistance, can achieve excellent energy absorption, significantly improve specific energy absorption and specific strength, and thus protect objects from high-speed impacts.

Description

Technical Field

[0001] The present invention relates to the technical field of impact resistance protection, and in particular to a bionic impact-resistant sandwich panel based on a Bouligand structure, and a preparation method and application thereof. Background Art

[0002] Lightweight, high-strength materials and structures are finding applications in aerospace, automotive, biomedical, and other fields. Sandwich structural design plays a crucial role in this, allowing for a higher mass-bending stiffness ratio compared to monolithic structures. Sandwich structures typically consist of two very thin skins and a lightweight core. The upper and lower skins are subject to significant bending moments, while the core serves to separate the skins, increase bending strength, and withstand transverse shear loads and compressive loads perpendicular to the sandwich surfaces.

[0003] In fields such as aerospace and biomedicine, many catastrophic failures are caused by impacts of varying energies. Sandwich structures can experience four types of damage when subjected to impacts of varying energies: delamination between the skin and core, compression of the core beneath the impacting object, shear failure between the compressed core and the boundary layer, and vertical through-hole cracks at the base.

[0004] Traditional sandwich structures are primarily constructed by bonding the skin to the core. When subjected to impact, the primary damage is delamination between the skin and core, followed by damage to the skin and core. This is because the skin and core are bonded using an adhesive, which is significantly weaker than the strength of the skin and core materials. This creates significant stress, severely limiting the sandwich structure's energy absorption.

[0005] Additive manufacturing, based on digital models, utilizes powdered metal and polymer filaments to construct complex structures layer by layer. This process results in uniform material strength and minimal stress at the interface, effectively resolving the delamination issue between the skin and core of traditional sandwich structures.

[0006] In traditional sandwich structures represented by honeycombs, the middle core layer is composed of vertical straight walls. Under the action of impact, the compression area will buckle and delaminate, and vertical brittle cracks will occur in the vertical crack area. Vertical cracks penetrate the sandwich structure, absorb less energy, have low specific energy absorption, and have poor toughness.

[0007] Patent document CN 115846687 A discloses a Bouligand spiral stacking structure, comprising a Bouligand spiral stacking matrix structure and a honeycomb structure with a gradient change; the Bouligand spiral stacking matrix structure comprises a plurality of elementary structures stacked in sequence and rotated in the same direction by a preset angle; the elementary structures comprise a plurality of hollow cylindrical tubes tightly arranged in the same direction; and a honeycomb structure with a gradient change is filled in each of the hollow cylindrical tubes.

[0008] Patent document with announcement number CN 110329551 B discloses a bionic multifunctional thermal protection structure based on SLM forming. The structure is formed using SLM technology and consists of a panel layer and a functional layer. The functional layer includes several large hollow tubular structural tubes. The large structural tubes are stacked and connected to form a honeycomb structure. The tubes in adjacent layers are cross-linked to a certain size to ensure that the structure is firmly connected.

[0009] The Bouligand structure, composed of helically stacked thin layers of unidirectional fibers, is widely found in natural biomaterials and exhibits exceptional mechanical properties. Its unique helical structure and discontinuities enable synergistic toughening between materials through crack distortion and fiber bridging. The Bouligand structure deflects through-going vertical cracks, generating twisted cracks that increase energy absorption, toughness, and impact resistance. Summary of the Invention

[0010] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a bionic impact-resistant sandwich panel based on the Bouligand structure. The bionic impact-resistant sandwich panel has excellent impact resistance, can achieve excellent energy absorption effect, greatly improve specific energy absorption and specific strength, thereby protecting objects under high-speed impact.

[0011] A bionic impact-resistant sandwich panel based on a Bouligand structure includes a Bouligand spiral stacking matrix structure, wherein the Bouligand spiral stacking matrix structure is formed by stacking a plurality of elementary structures in sequence and rotating in the same direction according to a preset angle. The elementary structures include upper and lower partitions and asymmetric walls uniformly distributed parallel to and perpendicular to the planes of the upper and lower partitions. The asymmetric walls are in the shape of a trigonometric function with different upper and lower amplitudes and the same frequency.

[0012] The present invention optimizes the Bouligand structure by combining different toughening mechanisms with bionic structures in nature. The bionic impact-resistant sandwich plate structure can deflect the crack path and fold and buckle the asymmetric walls through asymmetric walls with gradient amplitudes and Bouligand structures at different angles, fully absorbing impact energy, improving specific energy absorption and specific strength, and providing excellent protective effects.

[0013] Preferably, the height of the asymmetric wall is H1, and the center lines S1 and S2 of the top and bottom surface profile functions satisfy the following equations:

[0014] S1=A1sin(ω1x)

[0015] S2=A2sin(ω2x)

[0016] Among them, A1 and A2 are the amplitudes of the top and bottom of the asymmetric wall respectively, ω1 and ω2 are the frequencies of the top and bottom of the asymmetric wall respectively, D1 is the width of the asymmetric wall, A1:A2:D1:H1=(1~4):(1~4):(2~4):(8~16), and the value range of ω1 and ω2 is 0.2π~2π (π is pi).

[0017] Within this range, the asymmetric wall exhibits ductile failure, changing the brittle failure behavior seen in other ranges. The crack path shifts from vertical penetration to oblique torsional fracture, increasing energy absorption. Under drop-weight impact testing, the peak load increased by nearly 50% and the platform width increased by nearly 10%.

[0018] Preferably, the number N1 of asymmetric walls in the elementary structure is determined according to actual needs.

[0019] Preferably, the distance between adjacent asymmetric walls is D2, and the thickness of the upper and lower bottom plates is D3, wherein 1≤D2:D1≤6, and 1≤H1:D3≤4.

[0020] The filling rate of the elementary structure is controlled by the width of the asymmetric wall and the spacing between the asymmetric walls. When the filling rate of the elementary structure is below 30%, the specific energy absorption of the elementary structure is increased by more than 30% compared with other ranges. Therefore, the above parameters are preferred.

[0021] Preferably, the number N2 of the elementary structures in the Bouligand spiral stacking matrix structure is determined according to actual use.

[0022] Preferably, the preset angle α is in the range of 5°≤α≤15°.

[0023] Preferably, the material of the Bouligand spiral stacking matrix structure is polylactic acid PLA, thermoplastic polyurethane TPU or acrylonitrile butadiene styrene plastic ABS.

[0024] Preferably, the material of the Bouligand spiral stacking matrix structure is in a filamentous form with a diameter of 1.75 to 2.85 mm.

[0025] Preferably, the bionic impact-resistant sandwich panel has an impact resistance of more than 1.4 J / g, and its energy absorption is increased by more than 50% compared with the traditional sandwich panel structure.

[0026] The present invention also provides a method for preparing a bionic impact-resistant sandwich panel based on the Bouligand structure, which is manufactured using an additive manufacturing method.

[0027] Preferably, the steps of preparing the bionic impact-resistant sandwich panel based on the Bouligand structure by using the additive manufacturing method are:

[0028] (1) establishing a three-dimensional digital model of the Bouligand spiral stacking matrix structure model;

[0029] (2) converting the three-dimensional digital model into two-dimensional slice data;

[0030] (3) Inputting the two-dimensional slice data into the melt extrusion additive manufacturing equipment for calculation to obtain the printer's running path;

[0031] (4) Perform printing preparation work in a melt extrusion additive manufacturing device to obtain the target structure.

[0032] The present invention also provides applications of the Bouligand-structured bionic impact-resistant sandwich panel in aerospace, automotive protection, or biomedical applications. The Bouligand-structured bionic impact-resistant sandwich panel has excellent impact resistance, excellent energy absorption, and significantly improved specific energy absorption and specific strength, thereby protecting objects from high-speed impacts. The panel can be applied in aerospace, automotive protection, or biomedical applications.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] The present invention optimizes the Bouligand structure by combining different toughening mechanisms with bionic structures in nature. The bionic impact-resistant sandwich plate structure can deflect the crack path and fold and buckle the asymmetric walls through asymmetric walls with gradient amplitudes and Bouligand structures at different angles, fully absorbing impact energy, improving specific energy absorption and specific strength, and providing excellent protective effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the preparation process of the biomimetic functional gradient material structure in the embodiment;

[0036] Figure 2 Schematic diagram of the Bouligand spiral stacking structure provided in Example 1;

[0037] Figure 3 This is a schematic diagram of the elementary structure provided in Example 1;

[0038] Figure 4 Schematic diagram of the bionic asymmetric wall provided in Example 1. DETAILED DESCRIPTION

[0039] The following further illustrates the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] The preparation process of the biomimetic functional gradient material in the following embodiment is as follows: Figure 1 As shown:

[0041] (1) Establishing a three-dimensional digital model of the Bouligand spiral stacking matrix structure model,

[0042] The asymmetric wall structure is created in Solidworks with a height of H1. The center lines S1 and S2 of the top and bottom surface contour functions satisfy the following equations:

[0043] S1=A1sin(ω1x)

[0044] S2=A2sin(ω2x)

[0045] Among them, A1 and A2 are the amplitudes of the top and bottom of the asymmetric wall, ω1 and ω2 are the vibration frequencies of the top and bottom of the asymmetric wall, D1 is the width of the asymmetric wall, and the contour line is translated to both sides according to the center line. The distance between the upper and lower contour lines is generated, and then the truncated cone function in Solidworks modeling is used to create the truncated cone. The truncated cone height is H1; A1:A2:D1:H1=(1~4):(1~4):(2~4):(8~16), and the value range of ω1 and ω2 is 0.2π~2π;

[0046] Use the array function to copy the asymmetric energy-absorbing wall in a direction parallel to the bottom plate, set the number and spacing of the arrays, and obtain an asymmetric wall array;

[0047] Set the thickness of the upper and lower base plates;

[0048] The asymmetric wall array is combined with the upper and lower base plates to obtain a basic structure. The number of basic structures is set and they are stacked in sequence by rotating in the same direction according to a preset angle α, where the range of α is 5°≤α≤15°.

[0049] (2) The three-dimensional digital model is converted into two-dimensional slice data.

[0050] (3) The two-dimensional slice data is input into the melt extrusion additive manufacturing equipment for calculation to obtain the printer's running path.

[0051] (4) Drying the filament, adjusting the process parameters, and preparing for printing in the melt extrusion additive manufacturing equipment to obtain the target structure.

[0052] The mechanical properties of the prepared bionic functional gradient material were tested.

[0053] Example 1

[0054] The bionic structure was modeled using SOLIDWORKS. The schematic diagram of the Bouligand spiral stacking structure of the obtained model is shown in the figure below. Figure 2 As shown, the basic structure is as Figure 3 The model consists of a four-layer elementary structure, where the upper and lower plates have a radius of 60 mm and a thickness of 0.8 mm. The height of the asymmetric wall is 1.6 mm. The top centerline function is A1 = 0.2*sin(0.8*π*x), the bottom centerline function is S2 = 0.6*sin(0.8*π*x), the asymmetric wall width is 0.4 mm, the spacing between adjacent asymmetric walls is 1.2 mm, and the number of asymmetric walls is 37. The structural diagram of the asymmetric wall in this embodiment is shown in FIG. Figure 4 The four groups of primitive structures were rotated and stacked in sequence at 15° around the center of the circle to obtain the overall model, which was then exported as an STL model. Slicing software was used to obtain the slice and print path Gcode with a layer height of 0.2 mm.

[0055] (2) Place the PLA filament in a vacuum drying oven at 60 degrees Celsius and vacuum dry it for 8 hours to remove the absorbed moisture. Then take it out for later use.

[0056] (3) Start the FDM printer, set the base plate to 55°C, the nozzle to 200°C, tighten the bottom nut to level it, and the spacing is 0.1-0.4mm. Set the basic parameters: nozzle temperature 180-205°C, nozzle diameter 0.4mm, layer height 0.2mm, and speed 30-60mm / min.

[0057] (4) Use Gcode to prepare the designed additively manufactured bionic structure energy-absorbing components.

[0058] The samples obtained in (4) were subjected to a drop weight impact test according to the ISO 6603-2 test standard to obtain their impact resistance data, which are listed in Table 1.

[0059] Example 2

[0060] (1) Use SOLIDWORKS to model the bionic structure. The model consists of four layers of primitive structures, where the radius of the upper and lower layers is 60mm, the thickness is 0.8mm, the height of the asymmetric wall is 1.6mm, the top centerline function is S1 = 0.4*sin(1.2*π*x), the bottom centerline function is S2 = 0.8*sin(1.2*π*x), the asymmetric wall width is 0.4mm, the spacing between adjacent asymmetric walls is 2mm, and the number of asymmetric walls is 25. The four groups of primitive structures are rotated and stacked in sequence at 5° around the center of the circle to obtain the overall model, which is then exported as an STL model. Slicing software is used to obtain the slice and print path Gcode, with a layer height of 0.1mm.

[0061] (2) Place the TPU filament in a vacuum drying oven at 80 degrees Celsius and vacuum dry it for 8 hours to remove the absorbed moisture, then take it out for later use.

[0062] (3) Start the FDM printer, set the base plate to 80°C, the nozzle to 220°C, tighten the bottom nut to level it, and the spacing is 0.1-0.4mm. Set the basic parameters: nozzle temperature 205-230°C, nozzle diameter 0.4mm, layer height 0.1mm, and speed 20-40mm / min.

[0063] (4) Use Gcode to prepare the designed additively manufactured bionic structure energy-absorbing components.

[0064] Comparative Example 1

[0065] A traditional sandwich panel structure was modeled using SOLIDWORKS. The model consists of four layers of primitive sandwich panels. The upper and lower panels have a radius of 60 mm, a thickness of 0.8 mm, a straight arm height of 1.6 mm, a width of 0.4 mm, a spacing of 1.2 mm between adjacent straight walls, and 37 straight walls. The four groups of primitive structures were stacked to create the overall model, which was then exported as an STL model. Slicing software was used to generate the slice and print path Gcode, with a layer height of 0.2 mm.

[0066] (2) Place the PLA filament in a vacuum drying oven at 60 degrees Celsius and vacuum dry it for 8 hours to remove the absorbed moisture. Then take it out for later use.

[0067] (3) Start the FDM printer, set the base plate to 55°C, the nozzle to 200°C, tighten the bottom nut to level it, and the spacing is 0.1-0.4mm. Set the basic parameters: nozzle temperature 180-205°C, nozzle diameter 0.4mm, layer height 0.2mm, and speed 30-60mm / min.

[0068] (4) Use Gcode to prepare the designed additively manufactured bionic structure energy-absorbing components.

[0069] The samples obtained in (4) were subjected to a drop weight impact test according to the ISO 6603-2 test standard to obtain their impact resistance data, which are listed in Table 1.

[0070] Table 1 Impact performance test data of the bionic structure energy-absorbing components of the embodiment and the comparative example

[0071] serial number Impact performance (J / g) Example 1 1.4 Example 2 1.6 Comparative Example 1 0.8

[0072] As can be seen from Table 1, the impact resistance of the additively manufactured bionic impact-resistant sandwich panel based on the Bouligand structure is greatly improved compared with the traditional sandwich panel structure.

Claims

1. A bionic impact-resistant sandwich panel based on a Bouligand structure, characterized in that: The Bouligand spiral stacking matrix structure is formed by stacking a plurality of elementary structures in sequence according to a preset angle and rotating in the same direction. The elementary structures include upper and lower partitions and asymmetric walls evenly distributed parallel to and perpendicular to the planes of the upper and lower partitions. The asymmetric walls are in the shape of a trigonometric function with different upper and lower amplitudes and the same period. The height of the asymmetric wall is H1, and the center lines S1 and S2 of the top and bottom surface profile functions satisfy the following equations: S1=A1sin(ω1x) S2=A2sin(ω2x) Among them, A1 and A2 are the amplitudes of the top and bottom of the asymmetric wall respectively, ω1 and ω2 are the vibration frequencies of the top and bottom of the asymmetric wall respectively, D1 is the width of the asymmetric wall, A1:A2:D1:H1=(1~4):(1~4):(2~4):(8~16), and the value range of ω1 and ω2 is 0.2π~2π.

2. The bionic impact-resistant sandwich panel based on the Bouligand structure according to claim 1, characterized in that: The distance between adjacent asymmetric walls is D2, and the thickness of the upper and lower partitions is D3, where 1≤D2:D1≤6, and 1≤H1:D3≤4.

3. The bionic impact-resistant sandwich panel based on the Bouligand structure according to claim 1, characterized in that: The preset angle α is in the range of 5°≤α≤15°.

4. The bionic impact-resistant sandwich panel based on the Bouligand structure according to claim 1, characterized in that: The material of the Bouligand spiral stacking matrix structure is polylactic acid, thermoplastic polyurethane or acrylonitrile-butadiene-styrene plastic.

5. The bionic impact-resistant sandwich panel based on the Bouligand structure according to claim 4, characterized in that: The material of the Bouligand spiral stacking matrix structure is in a filamentous form with a diameter of 1.75 to 2.85 mm.

6. The bionic impact-resistant sandwich panel based on the Bouligand structure according to claim 1, characterized in that: The impact resistance of the bionic impact-resistant sandwich panel is higher than the energy absorption of 1.4 J / g.

7. The method for preparing a bionic impact-resistant sandwich panel based on a Bouligand structure according to any one of claims 1 to 6, characterized in that: Manufactured using additive manufacturing methods.

8. The method for preparing the bionic impact-resistant sandwich panel based on the Bouligand structure according to claim 7, characterized in that: The steps of preparing the bionic impact-resistant sandwich panel based on the Bouligand structure by using the additive manufacturing method are as follows: (1) establishing a three-dimensional digital model of the Bouligand spiral stacking matrix structure according to any one of claims 1 to 6; (2) converting the three-dimensional digital model into two-dimensional slice data; (3) Inputting the two-dimensional slice data into the melt extrusion additive manufacturing equipment for calculation to obtain the printer's running path; (4) Perform printing preparation work in a melt extrusion additive manufacturing device to obtain the target structure.

9. Application of the bionic impact-resistant sandwich panel based on the Bouligand structure according to any one of claims 1 to 6 in the fields of aerospace, automobile protection or biomedicine.

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