Composite Shaft Joint Structure That Preserves Reinforcement Fibers
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Solution Overview
Problem
Joining a composite member made of fiber-containing composite material to another member without cutting reinforcement fibers, which typically results in a decrease in strength due to the cutting of reinforcement fibers during the formation of bolt holes.
Innovation Solution
A joining structure where a shaft member made of fiber-containing composite material is inserted into a hole of a first member, with varying widths and orientations to fit snugly and restrict movement, allowing for secure attachment without cutting the reinforcement fibers, and optionally using a hollow or non-circular section for weight reduction and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bolt hole is formed in the composite member to insert a bolt for joining, then the composite member can be joined to another member, but the reinforcement fibers are cut and the strength of the composite member is decreased
Solution Approach 1:
A shaft member made of fiber-containing composite material is introduced as an intermediary component. Instead of forming a hole through the composite member and using a separate bolt, the shaft member itself serves as the joining element that fits into a hole formed in the other member (the metal member), thereby joining the two members without cutting the reinforcement fibers of the composite member.
Solution Approach 2:
The conventional approach is inverted: instead of passing a fastening member through a hole in the composite member, the composite member's shaft is inserted into a hole in the other member. This reverses which member contains the hole, protecting the composite member's fibers from being cut.
2Strength
If the shaft member has varying widths to fit snugly in the hole for secure joining, then the joining strength is improved, but the manufacturing complexity increases
Solution Approach 1:
The shaft member has different widths at different positions along its length. The first width at the first position and the second width at the second position (closer to the distal end) are different, with the second width being larger. This local variation in geometry creates interference fit features at specific locations, providing secure joining without requiring complex geometry throughout the entire shaft.
Solution Approach 2:
The width parameter of the shaft member is changed at different positions along its length. By varying the width parameter locally (first width vs. second width), the shaft member achieves both secure fitting (through interference at the wider section) and simplified manufacturing (comparatively simple geometry overall).
Data Source
AI summary
A joining structure according to one embodiment of the present invention includes a first member and a second member, the first member having a hole extending along an axis direction, the second member including a shaft member, the shaft member being formed of a fiber-containing composite material and having a shape to fit in the hole, the second member being joined to the first member via the shaft member so that movement thereof in the axis direction is restricted.