A biomimetic design-based two-parameter function-controlled gradient lattice material and its filling structure

Abstract

This invention provides a biomimetic design-based two-parameter function-controlled gradient material and its filling structure, comprising variant CFCB lattice unit cells arranged in an array along the X, Y, and Z directions, wherein the amplitude A of the variant CFCB lattice unit cells along the Z direction is... z Controlled by a two-parameter function, and with the variant CFCB lattice unit cell arrangement symmetrical along the midline of the X-Z plane, this invention, based on biomimetic design principles, applies a gradient control strategy to the geometric description and control of complex lattice materials. The resulting gradient lattice material can be used as a filler in thin-walled square tube structures. Experimental results show that the gradient lattice proposed in this invention can effectively improve the filling structure's resistance to lateral bending loads, effectively delay fiber breakage in thin-walled square tubes, and thus significantly improve the structure's bending resistance and energy absorption performance.

Description

Technical Field

[0001] This invention relates to the field of lattice structure design technology, specifically to a gradient lattice material and its filling structure based on a biomimetic design using a two-parameter function control. Background Technology

[0002] In the field of vehicle engineering, while ensuring the strength and safety performance of automobiles, lightweight design of body components can not only improve the handling and power of automobiles, but also effectively reduce the fossil fuel consumption of traditional automobiles and increase the driving range and energy efficiency of new energy vehicles.

[0003] To achieve lightweighting of vehicle body parts, advanced structural design using lightweight materials is an extremely important approach. This involves applying materials such as lattice and fiber composite materials to the design of advanced structures such as thin-walled and infilled structures, thereby achieving weight reduction while ensuring structural strength.

[0004] Lattice materials are porous, ordered, and periodically arranged multifunctional advanced materials widely used in mechanical, aerospace, and biomedical engineering fields due to their high specific strength, specific energy absorption, and excellent vibration reduction, noise reduction, and impact resistance. Academically, optimizing the unit cell of lattice materials can significantly improve their overall performance. Therefore, a series of studies have optimized and improved the unit cell of traditional lattices to achieve superior mechanical properties. Among them, a cosine function cell-base (CFCB) lattice structure, evolved from the body-centered cubic (BCC) lattice, has proven to have significant mechanical advantages and is gradually attracting attention.

[0005] like Figure 1 As shown in (a), this is a typical CFCB lattice unit cell. Figure 1 (b) and Figure 1 As shown in (c), this lattice unit cell structure is designed based on the cosine function, and the specific geometric constraints include the unit cell height. unit cell diameter single cell amplitude For a typical CFCB lattice unit cell, the unit cell height is [value missing] in any direction. and unit cell diameter All are constants, and along and Unit amplitude in direction They are equal and constant, that is .

[0006] Infill structures are advanced structures formed by filling different types of thin-walled structures with materials such as lattice or porous materials. The most significant characteristic of this type of infill structure is the interactive effect between the internal filler and the external thin wall; that is, the overall performance parameters of the infill structure are greater than the sum of the performance parameters of the individual filler and the individual thin wall. This superior mechanical energy absorption characteristic, resulting from the interactive effect, leads to the widespread application of infill structures in vehicle body design. In particular, for infill structures made of carbon fiber reinforced resin (CFRP) thin-walled composites, lattice materials can effectively improve their flexural strength and significantly enhance their energy absorption performance.

[0007] Although the CFCB lattice-filled structure formed by using the above-mentioned typical CFCB lattice material as filler has improved bending resistance compared to the thin-walled structure, it still cannot meet the higher requirements in some situations. Summary of the Invention

[0008] To further improve the bending resistance of thin-walled structures under lateral loads, this invention proposes a biomimetic design-based dual-parameter function-controlled gradient material and its filling structure.

[0009] This invention is achieved through the following technical solution:

[0010] A biomimetic design-based two-parameter function-controlled gradient lattice material, comprising along... , , A variant CFCB lattice unit cell arranged in three directions, the variant CFCB lattice unit cell along... Amplitude in direction Controlled by a two-parameter function, and the variant CFCB lattice unit cell arrangement along... Symmetrical along the midline of the plane;

[0011] The two-parameter function is:

[0012]

[0013]

[0014]

[0015] in, The constant represents the gradient lattice material along the path. Total length in the direction; Representative along Direction, distance Plane centerline The amplitude of each variant CFCB lattice unit cell; This means that it is located in Both sides of the plane centerline and the distance The two nearest sets of variant CFCB lattice unit cells along the plane midline Amplitude in direction; It's about the gradient parameters. and quantity parameters A two-parameter control function; where the quantity parameter is... The value of is a positive integer, and the maximum value is... equal The number of variant CFCB lattice unit cells on one side of the midline in the plane.

[0016] Preferably, the height of the variant CFCB lattice unit cell It is a constant.

[0017] Furthermore, the height of all variant CFCB lattice unit cells They are all equal.

[0018] Preferably, the diameter of the variant CFCB lattice unit cell is... It is a constant.

[0019] Furthermore, the diameter of all variant CFCB lattice unit cells They are all equal.

[0020] Preferably, the variant CFCB lattice unit cell is along Amplitude in direction It is a constant.

[0021] Furthermore, all variant CFCB lattice unit cells along Amplitude in direction They are all equal.

[0022] Preferably, gradient parameters .

[0023] A filling structure includes a thin-walled square tube structure and a biomimetic design-based two-parameter function-controlled gradient lattice material filled in the thin-walled square tube structure.

[0024] Preferably, the thin-walled square tube structure is made of carbon fiber reinforced resin matrix composite material.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention, based on biomimetic design principles, applies a gradient control strategy to the geometric description and control of complex lattice materials. The resulting gradient lattice material can be used as a filler in thin-walled square tube structures. Experimental results show that the gradient lattice proposed in this invention can effectively improve the infill structure's resistance to lateral bending loads and effectively delay fiber breakage in the thin-walled square tube, thereby significantly improving the structure's bending resistance and energy absorption performance. The structure described in this invention achieves lightweight design while improving mechanical structural strength, and has significant potential applications in fields such as automotive body component design.

[0027] Furthermore, when the gradient parameter hour, Take a positive integer. The value of exactly satisfies the Fibonacci sequence. The variation law of many structural parameters of plants and animals in nature satisfies the characteristics of the Fibonacci sequence and shows excellent performance. That is, the gradient lattice material of this invention contains rich biomimetic design ideas and has great application potential. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a typical CFCB lattice unit cell.

[0029] Figure 2 A schematic diagram of a variant CFCB lattice unit cell designed for this invention.

[0030] Figure 3 This is a schematic diagram of the gradient lattice material of the present invention.

[0031] Figure 4 This is a schematic diagram of the filling structure of the gradient lattice material of the present invention.

[0032] Figure 5 The images show physical images of the uniform CFCB lattice filling structure (a) and the gradient CFCB lattice filling structure (b) prepared for embodiments of the present invention.

[0033] Figure 6 Images of a three-point bending experiment.

[0034] Figure 7 and Figure 8 The results of three-point bending experiments for each CFCB lattice-filled structure are presented. Detailed Implementation

[0035] To further understand the present invention, the present invention will be described below with reference to embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0036] like Figure 2 As shown in (a), in order to realize gradient lattice materials, this invention designed and obtained a variant CFCB lattice unit cell. Figure 2 (b) and Figure 2 As shown in (c), the height of the variant CFCB lattice unit cell in any direction. and diameter All are constants; along directional variants of CFCB lattice unit cell amplitude As a variable, it is controlled by a two-parameter function, along All variants of CFCB lattice unit cell amplitude in the direction It is a constant, that is .

[0037] like Figure 3 As shown in (a), along , , Gradient CFCB lattice materials are obtained by arranging multiple sets of variant CFCB lattice unit cells in a linear array along three directions. For example... Figure 3 As shown in (b), the unit cell diameter of all variant CFCB lattice All are equal and constant, along In terms of direction, the height of the variant CFCB lattice unit cell All are equal and constant; along In terms of direction, the amplitude of all variant CFCB lattice units All are equal and constant. For example... Figure 3 As shown in (c), along Orientation variant CFCB lattice unit cell amplitude Controlled by a two-parameter function, and the arrangement follows... The plane is symmetrical along the midline, the closer to Unit amplitude of the midline of the plane The smaller.

[0038] Among them, control variables The two-parameter function satisfies the following relationship:

[0039]

[0040]

[0041]

[0042] in, The constant represents the gradient of the CFCB lattice structure along... Total length in the direction; Representative along Direction, distance Plane centerline The amplitude of a (including itself) variant CFCB lattice unit cell; This means that it is located in Both sides of the plane centerline and the distance The two nearest sets of variant CFCB lattice unit cells along the plane midline Amplitude in direction; It's about the gradient parameters. and quantity parameters A two-parameter control function. The quantity parameter... The value of is a positive integer, and the maximum value is... Exactly equal to The number of variant CFCB lattice unit cells on one side of the midline in the plane.

[0043] It should be noted that when the gradient parameter At that time, quantity parameters Take a positive integer. The values ​​of exactly satisfy the Fibonacci sequence. The Fibonacci sequence, also known as the golden ratio sequence, has a close connection with nature. Many structural parameters of plants and animals in nature exhibit the characteristics of the Fibonacci sequence and demonstrate excellent performance. Furthermore, gradient structures are widely found in nature; for example, the porous structure inside the human femur is a gradient distribution with excellent mechanical properties. Therefore, this type of gradient lattice contains rich biomimetic design ideas and has great application potential.

[0044] To further enhance the applicability and widespread use of gradient CFCB lattice materials, this invention proposes applying such gradient CFCB lattice materials to the filling of thin-walled square tube structures. For example... Figure 4 (a) Figure 4 (b) and Figure 4 As shown in (c), the gradient CFCB lattice structure 2 is embedded in the thin-walled square tube structure 1. The overall size of the gradient CFCB lattice structure 2 is approximately equal to the inner size of the thin-walled square tube structure 1, ensuring complete filling. The arrangement pattern of the variant CFCB lattice unit cell 3 is consistent with the arrangement pattern of the gradient CFCB lattice material described above.

[0045] To verify the superior performance of the gradient CFCB lattice-filled structure compared to the uniform CFCB lattice-filled structure, the following embodiments of the present invention conducted a related three-point bending experiment.

[0046] Example

[0047] The gradient CFCB lattice-filled structure and the uniform CFCB lattice-filled structure designed in this embodiment of the invention have the same overall dimensions, similar overall mass, and are manufactured in the same way. The outer thin-walled square tubes are all carbon fiber reinforced resin matrix composites (CFRP), with a length of [missing information]. The inner diameter is It is entirely molded from 6 layers of woven carbon fiber prepreg. The inner lattice structure is manufactured using additive manufacturing, with 316L stainless steel as the selected material.

[0048] To enhance the reliability of the experiment, this embodiment of the invention designed and fabricated 5 sets of gradient CFCB lattice-filled structures and 1 set of uniform CFCB lattice-filled structures. Regarding these 6 sets of lattice structures, the height of all unit cells... All unit cell diameters ,along All unit cell amplitudes in the direction and along 5 groups of unit cells in the directional array, along 5 groups of unit cells in the directional array, along The directional array consists of 22 groups of single cells.

[0049] For the five sets of gradient CFCB lattice structures, along Unit cell amplitude in direction The values ​​of satisfy a specific two-parameter function. For this specific two-parameter function, ,and , and The values ​​are respectively ; ; ; ; For a set of uniform CFCB lattice structures, .

[0050] like Figure 5 The images show samples of a uniform CFCB lattice-filled structure and a gradient CFCB lattice-filled structure, both designed and manufactured. Figure 6 As shown, a three-point bending test was conducted on the above six groups of samples.

[0051] like Figure 7 and Figure 8 As shown, the experimental results indicate that the total energy absorption of the five gradient CFCB lattice-filled structures is significantly better than that of the uniform CFCB lattice-filled structure. Furthermore, the fracture time of the outer carbon fibers in the five gradient CFCB lattice-filled structures is delayed compared to the uniform CFCB lattice-filled structure. This demonstrates that the gradient CFCB lattice structure proposed in this invention can more effectively disperse external impacts, enabling the overall filling structure to withstand higher impact forces and delaying the fracture of the outer CFRP. These experimental results sufficiently prove that the gradient CFCB lattice structure can more effectively improve the bending resistance and energy absorption performance of the outer thin-walled structure, exhibiting superior performance.

[0052] In addition, regarding gradient parameters and quantity parameters Different values ​​of the gradient parameter will also lead to different experimental results. The peak force in the experimental results is significantly affected by the quantitative parameters. The force-displacement curve and gradient parameters significantly affect the fracture time of fibers in CFRP. Therefore, an ideal force-displacement curve and gradient parameters are used to determine this. Quantity parameters By adjusting the composition, a more reasonable gradient CFCB lattice filling structure can be designed in reverse, which has strong applicability.

Claims

1. A gradient lattice material based on biomimetic design with a two-parameter function control, characterized in that, Including along , , A variant CFCB lattice unit cell arranged in three directions, the variant CFCB lattice unit cell along... cosine function amplitude in direction Controlled by a two-parameter function, and the variant CFCB lattice unit cell arrangement along... The plane is symmetrical along the midline; the variant CFCB lattice unit cell is a cosine function unit basis lattice structure evolved from a body-centered cubic lattice. The two-parameter function is: in, The constant represents the gradient lattice material along the path. Total length in the direction; Representative along Direction, distance Plane centerline The amplitude of each variant CFCB lattice unit cell; This means that it is located in Both sides of the plane centerline and the distance The two nearest sets of variant CFCB lattice unit cells along the plane midline Amplitude in direction; It's about the gradient parameters. and quantity parameters A two-parameter control function; where the quantity parameter is... The value of is a positive integer, and the maximum value is... Along the Z direction The number of variant CFCB lattice unit cells on one side of the midline in the plane.

2. The biomimetic design-based dual-parameter function-controlled gradient lattice material according to claim 1, characterized in that, The height of the variant CFCB lattice unit cell It is a constant.

3. The biomimetic design-based dual-parameter function-controlled gradient lattice material according to claim 2, characterized in that, Height of all variant CFCB lattice unit cells They are all equal.

4. The biomimetic design-based dual-parameter function-controlled gradient lattice material according to claim 1, characterized in that, The diameter of the variant CFCB lattice unit cell It is a constant.

5. The biomimetic design-based dual-parameter function-controlled gradient lattice material according to claim 4, characterized in that, Diameter of all variant CFCB lattice unit cells They are all equal.

6. The biomimetic design-based dual-parameter function-controlled gradient lattice material according to claim 1, characterized in that, The variant CFCB lattice unit cell along Amplitude in direction It is a constant.

7. The biomimetic design-based dual-parameter function-controlled gradient lattice material according to claim 6, characterized in that, All variants of CFCB lattice unit cell along Amplitude in direction They are all equal.

8. The biomimetic design-based dual-parameter function-controlled gradient lattice material according to claim 1, characterized in that, gradient parameters .

9. A filling structure, characterized in that, The material includes a thin-walled square tube structure and a biomimetic design-based dual-parameter function-controlled gradient lattice material filled in the thin-walled square tube structure, as described in any one of claims 1-8.

10. The filling structure according to claim 9, characterized in that, The thin-walled square tube structure is made of carbon fiber reinforced resin matrix composite material.

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