Composite Bicycle Frame Joint Structure
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Solution Overview
Problem
Conventional carbon fiber bicycle frames face issues with anisotropic properties, leading to complex manufacturing processes, high costs, and lengthy production times due to the need for meticulous layup of unidirectional fiber prepregs and high-cost injection molding.
Innovation Solution
A joint structure for composite bicycle frames comprising a base layer with random fiber orientation and a reinforcing layer with single fiber orientation, where the base layer is at least twice as thick as the reinforcing layer, made of polymeric matrix materials doped with fibers, simplifying the manufacturing process and reducing costs by using fewer layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If unidirectional fiber prepreg stacking is used to achieve strength and rigidity, then the mechanical properties are improved, but the manufacturing complexity and time increase significantly
Solution Approach 1:
The patent combines multiple unidirectional fiber layers (with different orientations) into a single multidirectional fiber mat layer. This merging approach maintains the strength and rigidity benefits of layered construction while eliminating the complex manual stacking process, thereby reducing manufacturing complexity and time.
Solution Approach 2:
The patent uses a composite structure consisting of a base layer (made from multidirectional fiber mat) and a reinforcing layer (made from unidirectional fiber prepreg). This composite material approach allows the base layer to provide isotropic strength while the reinforcing layer provides directional strength, achieving high mechanical properties without complex manufacturing.
2Stability of the object's composition
If multiple unidirectional fiber layers are stacked to achieve isotropic properties, then the mechanical isotropy is improved, but the manufacturing time and cost increase
Solution Approach 1:
The patent merges multiple unidirectional fiber layers into a single multidirectional fiber mat layer that provides isotropic mechanical properties in the plane of the layer. This eliminates the need for time-consuming manual stacking of multiple layers while maintaining mechanical isotropy.
Solution Approach 2:
The patent changes the fiber orientation parameter from unidirectional (single orientation) to multidirectional (random or quasi-random orientations) in the base layer. This parameter change enables isotropic mechanical properties to be achieved with a single layer rather than multiple stacked layers, significantly reducing manufacturing time.
3Productivity
If injection molding with fabric reinforcement is used, then mass production is enabled, but the joint strength is significantly lower than continuous-fiber composites
Solution Approach 1:
The patent merges the advantages of injection molding (mass production capability) with continuous-fiber reinforcement (high strength) by using a hybrid manufacturing approach. The base layer can be manufactured via injection molding with embedded continuous or long fibers, while the reinforcing layer provides additional directional strength, achieving both high productivity and high joint strength.
4Strength
If a thick base layer is used to provide isotropic strength, then the mechanical properties are improved, but the manufacturing cost and time increase
Solution Approach 1:
The patent applies local quality by using a thinner base layer combined with a strategically designed reinforcing layer. Instead of uniformly thickening the entire structure to achieve isotropic strength, the reinforcing layer is applied only where additional directional strength is needed, optimizing material usage while maintaining mechanical properties.
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 proposed joint structure achieves isotropic properties, reduces manufacturing time, and lowers costs by simplifying the layup process, enabling automation and mass production while maintaining strength and stiffness requirements.
Implementation Method 1
The reinforcing layer is adhesively connected to the base layer
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A joint structure of a composite bicycle frame, comprising: a base layer (110a, 210a, 310a) made of a first polymeric matrix material doped with a plurality of first fibers (112), wherein the first fibers (112) have random fiber orientation, and the base layer (110a, 210a, 310a) has a first thickness (T1); and at least one reinforcing layer (120a, 220a, 320a) adhesively connected to the base layer (110a, 210a, 310a), wherein the reinforcing layer (120a, 220a, 320a) is made of a second polymeric matrix material doped with a plurality of second fibers (122), the second fibers (122) have a single fiber orientation, and the reinforcing layer (120a, 220a, 320a) has a second thickness (T2) which is smaller than the first thickness (T1) of the base layer (110a, 210a, 310a).