Composite Tube Connecting Rod Threaded Insert Design
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Solution Overview
Problem
Existing connecting rods with composite material tubes in the aeronautical field face insufficient breaking stresses and expansion issues due to differential material coefficients, particularly with aluminum inserts, leading to weakened connections and high implementation costs.
Innovation Solution
A connecting rod design featuring a threaded mechanical hook between the composite tube and insert, allowing for high breaking stresses and mitigating expansion issues through complementary threaded parts, along with a method of manufacturing that includes machining a thread directly into the tube's extra thickness for precise fitting and non-destructive quality control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal insert is used to connect to the composite tube, then the connection strength is improved, but the differential thermal expansion between metal and composite material causes connection weakening
Solution Approach 1:
The patent changes the connection mechanism from direct rigid bonding to a threaded mechanical engagement that accommodates dimensional changes. The threaded connection allows the metal insert and composite tube to expand and contract independently while maintaining secure engagement, resolving the conflict between connection strength and thermal expansion compatibility.
2Ease of manufacture
If an extra thickness is added to the tube end, then the threading is facilitated, but the material usage increases
Solution Approach 1:
The patent applies local quality by adding material thickness only at the specific location where threading is required (the tube end), rather than uniformly throughout the entire tube. This localized material addition minimizes overall material consumption while providing sufficient material for the threading operation.
Data Source
Figure 1
Figure 2~3
AI summary
The rod has a tube (10) made of composite material with plastic material matrix, and an end fitting arranged at a longitudinal end (11) of the tube. A mechanical connection insert between the tube and the end fitting has a threaded bore (31) adjustable with the end fitting. The insert is screwed inside the end of the tube by making an outer thread (33) of the insert to cooperate with an inner thread (12) of the end of the tube. An independent claim is also included for a method of fabricating a rod.