Stacked Composite Interior Part Noise Reduction
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Solution Overview
Problem
Conventional laminated composite interior parts with cushioning properties due to elastic deformation of multiple protrusions often generate abnormal noise when pressed with a finger or hand due to stick-slip friction.
Innovation Solution
A laminated composite interior part design featuring a first member made of synthetic resin with a mating surface and a second member with elastically deformable protrusions, where the surface roughness of the mating surface is less than 0.20, and the protrusions are anisotropically flexurally deformed, reducing friction and allowing smooth sliding to prevent abnormal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protrusions are made to slide on the mating surface to provide cushioning properties, then the cushioning performance is improved, but abnormal noise is generated due to stick-slip friction
Solution Approach 1:
The invention changes the surface roughness parameter of the mating surface to less than 0.20 µm, which fundamentally alters the friction characteristics between the protrusions and the mating surface. This parameter change eliminates stick-slip friction while preserving the sliding motion necessary for cushioning, thereby resolving the noise problem without sacrificing cushioning performance
Solution Approach 2:
The protrusions are designed with asymmetric cross-sections having different dimensions in the sliding direction versus the direction perpendicular to sliding. This asymmetry creates anisotropic flexural rigidity that guides the protrusions to slide preferentially in one direction, stabilizing the motion and preventing the oscillatory stick-slip behavior that generates noise
2Object-generated harmful factors
If the surface roughness is reduced to prevent abnormal noise, then the friction is reduced and sliding is smoothed, but the cushioning effect may be compromised
Solution Approach 1:
The invention uses a composite structure consisting of the first member (providing the mating surface) and the second member (containing the protrusions), where each component is optimized for its specific function. The first member provides a smooth sliding surface while the second member provides the elastic deformation capability, achieving both low noise and effective cushioning through material and structural composition
Solution Approach 2:
The invention applies different surface quality requirements to different locations: the mating surface is engineered with very low roughness (Ra < 0.20 µm) to enable smooth sliding, while the protrusions maintain their elastic deformability. This localized optimization of surface quality allows the system to achieve both low noise and effective cushioning
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 solution effectively reduces friction and prevents abnormal noise generation by ensuring the protrusions slide smoothly in one direction, enhancing the tactile feel and cushioning performance while maintaining the anisotropic flexural deformation.
Implementation Method 1
cushioning properties provided by elastic deformation of the protrusions, which is to be caused as the distal end portions of the protrusions are relatively pressed against the mating surface
Implementation Method 2
surface roughness Ra of the mating surface is less than 0.20, and the protrusion is flexurally deformed in one direction about its axis with the distal end portion thereof sliding on the mating surface
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
In a stacked composite interior part to which cushioning properties are imparted by elastic deformation of multiple projections, the present invention limits the generation of strange noises when pressed with fingers or hands. Because microprojections 20 are provided in slanted orientations so as to bend in one direction around the axes thereof and the surface roughness Ra of the surface 22 of a base material 14 is less than 0.20, friction between said surface 22 and the microprojections 20 is reduced, causing the microprojections 20 to slide smoothly in one direction and effectively limiting the generation of strange noises arising from stick-slipping.