Elastomer Surface Structure for Friction Control
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Solution Overview
Problem
Existing surfaces, both dry and liquid-wetted, suffer from inadequate friction leading to issues like gear spinning in liquids and the stick-slip effect causing vibrations and noise in dry conditions, such as squeaking rail vehicles and rattling windshield wipers.
Innovation Solution
A surface structure with elevations and channels is integrated into an elastomeric body, allowing liquids to be displaced and drained, maintaining friction on liquid surfaces and reducing the stick-slip effect on dry surfaces by independent elevation movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a smooth surface is used on liquid-wetted surfaces, then the surface is simple to manufacture, but friction force decreases significantly causing gear spinning
Solution Approach 1:
The surface is segmented into numerous elevations (protrusions) and channels (grooves) that work together to manage liquid. The elevations provide friction-generating contact areas while the channels drain liquid away, resolving the contradiction between maintaining friction and managing liquid contamination.
Solution Approach 2:
Different regions of the surface have different functions: the elevations are designed to maintain contact and generate friction, while the channels are designed to drain liquid. This local differentiation allows the surface to simultaneously provide high friction and liquid management capabilities.
2Object-affected harmful factors
If dry surfaces are used, then friction force is sufficient, but the stick-slip effect occurs causing vibrations and noise
Solution Approach 1:
The surface is divided into many small, independently movable elevations. When stick-slip occurs on one elevation, the adjacent elevations can move independently, preventing the propagation of vibrations and noise across the entire surface.
Solution Approach 2:
The elevations are designed to be elastically deformable and independently movable, allowing them to adapt dynamically to contact conditions. This dynamic behavior prevents the rigid stick-slip phenomenon by allowing gradual deformation and energy dissipation.
3Object-affected harmful factors
If elevations are made movable independently to reduce stick-slip, then vibrations are reduced, but friction force may decrease
Solution Approach 1:
The dimensions of the elevations (height, width, spacing) are optimized to balance independence of movement with friction generation. By carefully controlling these parameters, the elevations can move independently enough to reduce stick-slip while maintaining sufficient contact area to generate required friction force.
Solution Approach 2:
The surface structure combines elastomeric material properties with the geometric elevation-channel pattern. The elastomeric material provides elastic deformation capability that allows independent movement while maintaining continuous contact and friction force.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The surface structure ensures sufficient friction on liquid-covered surfaces and eliminates the stick-slip effect on dry surfaces, providing consistent frictional force and noise reduction.
Implementation Method 1
Elastomers are dimensionally stable but elastically deformable polymers whose glass transition point is below room temperature and whose long-chain macromolecules are networked in a wide-meshed and randomly distributed manner. The elastomers can deform under tensile and/or compressive loads, but then return to their original, undeformed shape.
Implementation Method 2
a liquid is displaced from the surface of the elevations by the surface of a body that meshes with the elastomeric body and is drained away via the channels. With the help of the surface structure according to the invention, areas are provided on the surface of the elastomeric body which remain essentially liquid-free even when in contact with a liquid-wetted surface and therefore still provide sufficient frictional force
Data Source
Figure 1a~2
Figure 3~4
Figure 5~6
AI summary
The body (14) such as wind screen wiper or elastic sealing comprises an elastomer material or an external elastomer layer, where a surface structure (1) improving the friction behavior is formed in an area of the body in the surface of the elastomer body or in the external elastomer layer of the body. The surface structure comprises elevations (11) that are prismatic, pyramid-stump shaped, cylindrical, cone-shaped or gill-shaped form and are distanced from one another through a channel (12). The abutting face of the elevations stretches a joint plain. The body (14) such as wind screen wiper or elastic sealing comprises an elastomer material or an external elastomer layer, where a surface structure (1) improving the friction behavior is formed in an area of the body in the surface of the elastomer body or in the external elastomer layer of the body. The surface structure comprises elevations (11) that are prismatic, pyramid-stump shaped, cylindrical, cone-shaped or gill-shaped form and are distanced from one another through a channel (12). The abutting face of the elevations stretches a joint plain. The maximum surface extent of the abutting face of the elevations is 100 nm to 5 mm. The maximum dimension of the abutting face of the elevations is less than 300 mu m. The abutting faces of the elevations of the surface structure are uniformly formed and the form possesses a square, isosceles triangle, regular hexagon or polygon. The elevations are arranged in hierarchic plain and have rectangular, trapezoidal or gill-shaped longitudinal sections. The height of the elevations is 1-100% of the maximum dimension of the abutting face of the respective elevations. The surface portion of the abutting face of the elevation on the total area of the abutting face of the elevation and the channel is 20-99%. The channel comprises a hexagonal, rectangular, triangular, trapezoidal or polygonal cross-section. The channel has a circular or elliptical cross-section. The body is a transfer film or laminating film.