Sandwiched structure bionic friction pad and preparation method thereof

Abstract

The application discloses a sandwiched structure bionic friction pad, which comprises a plane base, an intermediate supporting layer and a terminal contact layer, the intermediate supporting layer is connected with the plane base and the terminal contact layer, and the intermediate supporting layer is an asymmetric linear array. The application further discloses a preparation method of the sandwiched structure bionic friction pad. The sandwiched structure bionic friction pad reduces the normal rigidity of the structure, so that the deformation can be realized under a small pre-pressure, the surface rigidity of the structure is reduced, the effective contact area between interfaces is increased, and then the tangential friction is increased. The sandwiched structure bionic friction pad designed by the application can effectively meet the application scene requirement of a kind of low-power tangential high-friction.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of friction pads, and particularly relates to a sandwich structure bionic friction pad and a preparation method thereof. BACKGROUND

[0002] The efficiency and versatility of several attachment systems in nature, such as geckos, beetles, spiders, or snails, have always been a source of inspiration for materials scientists and engineers: in many cases, they have excellent movement and adhesion capabilities on various smooth and rough surfaces, due to the patterned micro-nano structures on their contact organs.

[0003] US009340708B2 obtains a large adhesion force and tangential friction force by imitating tree frogs and setting up small protrusions on a large pillar array. The product of the invention can obtain a large adhesion force and tangential friction force, but the selection of deformable materials and the design of small protrusion structures make the product more prone to wear and tear, and it does not have the ability to be used multiple times, and the cost performance is low. US008524092B2 designs a dry adhesion material composed of dumbbell-shaped pillar arrays. This material can achieve a large tangential friction, and the structure has small rigidity, i.e. the normal pressure required for the structure to deform is small, and high tangential friction can be achieved under low pre-pressure. However, this structure has poor self-cleaning ability, and its performance decreases more after being contaminated, and the applicable field is limited. Therefore, scholars have proposed the idea of a multi-level bionic friction pad.

[0004] The multi-level bionic friction pad is a technical innovation inspired by the principles of natural design. It is inspired by the adhesion observed on the feet of geckos and other climbing animals. Geckos have millions of tiny hairs on their feet called setae, which generate intermolecular forces called van der Waals forces. These forces enable geckos to adhere to smooth or vertical surfaces. This advanced friction pad incorporates bionic principles in its design, mimicking the hierarchical structure of gecko feet to enhance its adhesion and friction capabilities, enabling the designed product to adhere to various surfaces. The friction pad is composed of multiple sandwich structures. The top and bottom layers are made of flexible and elastic materials, while the middle layer contains a series of small pillars. These pillars mimic the setae on gecko feet, increasing the contact surface area, and the interaction between the micro-pillars and the contact surface generates van der Waals forces, enhancing adhesion.

[0005] The intermediate support layer in this study has a large dry friction effect due to its excellent fully conformal contact. However, the microstructure in this study has relatively large rigidity, which is not easy to achieve high friction under low pre-pressure. Scholars Hamed Shahsavan designed and prepared a hybrid adhesive structure composed of an elastic biomimetic microcolumn array and a viscoelastic terminal film (see Biologically inspired enhancement of pressure-sensitive adhesives using a thin film-terminated fibrillar interface, Hamed Shahsavan and Boxin Zhao, Soft Matter 2012 8). This hybrid design makes the material have strong adhesion and controlled interface deformation. However, it is relatively easy to deform, has poor repeat use performance, and has high use cost. SUMMARY

[0006] The purpose of the present application is to provide a sandwich sandwich structure biomimetic friction pad to solve the problems raised in the background art.

[0007] To achieve the above purpose, the present application provides the following technical solution: a sandwich sandwich structure biomimetic friction pad, comprising a planar substrate, an intermediate support layer, and a terminal contact layer, the intermediate support layer connecting the planar substrate and the terminal contact layer, and the intermediate support layer being a non-symmetric linear array.

[0008] The intermediate support layer and the terminal contact layer are made of elastomeric organic polymer materials, such as silicone rubber, etc.

[0009] The intermediate support layer can be various structures with friction-enhancing effect, including but not limited to L-shaped, S-shaped, wedge-shaped, drum-shaped array structures.

[0010] The intermediate support layer is a non-straight column structure, and the intermediate layer structures do not interfere with each other after full buckling.

[0011] The ratio of the thickness of the end contact layer to the thickness of the intermediate support layer is between 0.4 and 0.7.

[0012] A preparation method of a sandwich structure biomimetic friction pad, comprising the following steps:

[0013] Pouring, adding silicone rubber into the mold;

[0014] Curing and demolding to form a planar substrate and an intermediate support layer;

[0015] The planar substrate and the intermediate support layer are adhered to the end contact layer, and the friction pad is formed after curing and demolding.

[0016] The sandwich structure biomimetic friction pad prepared by the present application provides several potential applications. It can be used in robots and automation, enabling robots to climb walls or work in challenging terrain. It can also be applied to industries that require safe gripping, such as manufacturing, logistics and healthcare, with a wide range of applications.

[0017] The sandwich structure biomimetic friction pad prepared by the present application and the ordinary planar structureless polymer friction pad with the same material and thickness of the straight cylindrical intermediate support layer are subjected to friction performance experiments. The experimental results show that the sandwich structure biomimetic friction pad prepared by the present application can obtain greater friction under the same pre-pressure, achieving the effect of low power to achieve high friction.

[0018] Technical effects and advantages of the present application: The sandwich structure biomimetic friction pad reduces the normal stiffness of the structure, enabling it to deform under smaller pre-pressure, reducing the surface stiffness of the structure, increasing the effective contact area between the interfaces, and thus increasing the tangential friction. The sandwich structure biomimetic friction pad designed by the present application can effectively meet the needs of a class of low-power tangential high-friction application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The structure of the present application is shown in the figure;

[0020] Figure 2 The microstructure of the physical object of the present application is shown in the figure;

[0021] Figure 3 The sandwich structure biomimetic friction pad with different intermediate layers in Examples 2, 3, 4 and 5 is shown in the figure;

[0022] Figure 4 The physical object of the sandwich structure biomimetic friction pad with different intermediate layers in Examples 2, 3, 4 and 5 is shown in the figure;

[0023] Figure 5The test results show the friction performance of the sandwich-structured biomimetic friction pad and the flat pad in the example.

[0024] Figure 6 This is a flowchart illustrating the preparation method of the biomimetic friction pad with sandwich structure of the present invention.

[0025] In the diagram: 10, end contact layer; 20, intermediate support layer; 30, planar substrate. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0029] Example 1:

[0030] like Figure 1 As shown, the sandwich-structured biomimetic friction pad provided in this embodiment consists of three parts: a planar base, an intermediate support layer, and an end contact layer. The intermediate support layer connects the planar base and the end contact layer. The intermediate support layer is a solid L-shaped non-vertical structure with a width of 250 μm, a height of 838 μm, and a spacing of 400 μm. After complete buckling, the non-vertical structure of the intermediate support layer does not interfere with each other. The thickness of the planar base is 200 μm. The thickness of the end contact layer is 595 μm. The ratio of the thickness of the end contact layer to the thickness of the intermediate support layer is 0.7. The material of this embodiment is 40A silicone rubber.

[0031] Friction force was tested using a friction and wear tester. The test results are as follows:Figure 5 As shown.

[0032] Test data shows that, under the same preload, the friction performance of the unstructured planar 40A silicone rubber pad is significantly lower than that of the biomimetic friction pad with an L-shaped non-column structure as the intermediate support layer. This is because, under normal load, the asymmetric design of the intermediate support layer makes it more prone to deformation, reducing surface stiffness and thus ensuring an effective contact area between interfaces, resulting in a larger tangential friction force.

[0033] In Example 1, the fabrication method of the biomimetic friction pad with a solid L-shaped non-vertical sandwich structure as the intermediate support layer is shown in the figure below. It includes three steps: fabricating an integrally formed intermediate support layer and a planar substrate, fabricating a semi-cured end contact layer, and bonding the intermediate support layer and the end contact layer.

[0034] Example 2:

[0035] The sandwich-structured biomimetic friction pad provided in Embodiment 2 is based on Embodiment 1, but with a change in the ratio of the end contact layer thickness to the intermediate support layer thickness. The intermediate support layer remains a solid L-shaped non-straight column structure, and after complete buckling, the intermediate layer structures do not interfere with each other. The material used is still 40A silicone rubber. The planar substrate thickness of this biomimetic friction pad is 382 μm. The height of the intermediate support layer is 872 μm, the width is 250 μm, and the spacing is 400 μm. The end contact layer thickness is 204 μm. The ratio of the end contact layer thickness to the intermediate support layer thickness is 0.4.

[0036] Friction force was tested using a friction and wear tester. The test results are as follows: Figure 5 As shown.

[0037] The test data shows that, under the same preload, the friction performance of the 40A silicone rubber unstructured flat pad is significantly lower than that of the 40A silicone rubber biomimetic friction pad with an L-shaped non-straight column structure in the middle support layer.

[0038] Example 3:

[0039] The sandwich-structured biomimetic friction pad provided in Embodiment 3 is based on Embodiment 2, but with a change in the shape of the intermediate support layer. It still ensures that the intermediate layers do not interfere with each other after full buckling. The material used is still 40A silicone rubber. The ratio of the end contact layer thickness to the intermediate support layer thickness remains 0.4. The planar substrate thickness of this biomimetic friction pad is 382 μm. The intermediate layer height is 1 mm, the width is 350 μm, and the spacing is 400 μm. The end contact layer thickness is 400 μm. The intermediate support layer is a solid S-shaped non-linear structure.

[0040] Friction force was tested using a friction and wear tester. The test results are as follows: Figure 5 As shown.

[0041] From the test data, it can be seen that the friction performance of the 40A silicone rubber unstructured flat pad is obviously less than that of the bionic friction pad with the S-shaped non-straight column structure of the intermediate support layer under the same pre-pressure.

[0042] Example Four:

[0043] The sandwiched bionic friction pad provided in this embodiment four is based on the embodiment three, and the shape of the intermediate support layer is changed. It is still ensured that the intermediate layer structures do not interfere with each other after complete buckling. The manufacturing material is still 40A silicone rubber. The ratio of the thickness of the terminal contact layer to the thickness of the intermediate support layer is still 0.4. The planar base thickness of the bionic friction pad is 380 μm. The intermediate layer has a height of 700 μm, a width of 620 μm, and a spacing of 400 μm. The thickness of the terminal contact layer is 281 μm. The intermediate support layer has a drum-shaped non-straight column structure.

[0044] The friction force test is performed using the friction and wear tester. The test results are shown in Table 4. Figure 5

[0045] From the test data, it can be seen that the friction performance of the 40A silicone rubber unstructured flat pad is obviously less than that of the bionic friction pad with the drum-shaped non-straight column structure of the intermediate support layer under the same pre-pressure.

[0046] Example Five:

[0047] The sandwiched bionic friction pad provided in this embodiment five is based on the embodiment four, and the shape of the intermediate support layer is changed. It is still ensured that the intermediate layer structures do not interfere with each other after complete buckling. The manufacturing material is still 40A silicone rubber. The ratio of the thickness of the terminal contact layer to the thickness of the intermediate support layer is still 0.4. The planar base thickness of the bionic friction pad is 380 μm. The intermediate layer has a height of 1 mm, an upper width of 1.48 mm, a lower width of 430 μm, and a spacing of 400 μm. The thickness of the terminal contact layer is 400 μm. The intermediate support layer has a solid wedge-shaped non-straight column structure.

[0048] The friction force test is performed using the friction and wear tester. The test results are shown in Table 5. Figure 5

[0049] From the test data, it can be seen that the friction performance of the 40A silicone rubber unstructured flat pad is obviously less than that of the bionic friction pad with the drum-shaped non-straight column structure of the intermediate support layer under the same pre-pressure.

[0050] The introduced "non-straight column intermediate support layer" for preparing friction materials provided in the present application provides a new method for friction research and material design, and can better meet the requirements of the industry.

[0051] ​​A method for preparing a sandwiched structure biomimetic friction pad, comprising the following steps:

[0052] Pouring, adding silicone rubber into the mold;

[0053] Curing and demolding to form a planar base 30 and an intermediate support layer 20;

[0054] Bonding the planar base 30 and the intermediate support layer 20 with the terminal contact layer 10, and curing and demolding to form a friction pad.

[0055] Although the embodiments of the present application have been shown and described above, it should be understood by those skilled in the art that the above embodiments are exemplary and cannot be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for preparing a sandwich-structured biomimetic friction pad, characterized in that: The sandwich-structured biomimetic friction pad includes: Planar base (30), intermediate support layer (20), end contact layer (10); The intermediate support layer (20) connects the planar base (30) and the end contact layer (10); The intermediate support layer (20) is a linear array; The intermediate support layer (20) and the end contact layer (10) are made of elastomeric organic polymers; The elastomeric organic polymer includes silicone rubber; The planar base (30) and the intermediate support layer (20) are integrally formed; The intermediate support layer (20) includes an L-shaped, S-shaped, or drum-shaped array structure; After complete buckling, the intermediate support layer (20) does not interfere with each other. The thickness ratio of the end contact layer (10) to the thickness of the intermediate support layer (20) is 0.4 to 0.7; The preparation method includes the following steps: Casting: Add silicone rubber to the mold; Curing and demolding form a planar base (30) and an intermediate support layer (20); The planar base (30) is bonded to the intermediate support layer (20) and the end contact layer (10), and after curing and demolding, a friction pad is formed.

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