Composite Tube Joint with Undulated Interfaces for Bending Loads

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Solution Overview

Problem

Typical wedge joint designs for composite cylindrical elements are prone to excessive slipping under bending loads, leading to stress re-distribution and potential damage or separation.

Innovation Solution

A composite tube joint design featuring an end of a composite tube, an inner member with a complementary outer surface, and an outer member with a concentric undulated surface to physically restrict movement and mitigate slipping under bending loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a typical wedge joint design is used to handle axial loads, then the joint can effectively transfer axial forces, but the joint experiences excessive slipping between the composite tube and wedge parts under bending loads

Engineering Contradiction:
Improveaxial load transferVSAvoidslipping resistance under bending loads
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent applies curvature by replacing the traditional flat wedge joint interface with a curved or contoured interface geometry. The curved surface allows for better load distribution and mechanical interlocking under bending loads, preventing excessive slipping while maintaining axial load transfer capability. The curvature enables the joint to accommodate both axial and bending load conditions more effectively.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Device complexity

If a typical wedge joint design is used, then the joint structure is simple, but the joint experiences stress re-distribution and potential damage or tube/joint separation under bending loads

Engineering Contradiction:
Improvejoint structure simplicityVSAvoidresistance to stress re-distribution and separation
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The patent divides the joint into multiple functional segments: an inner member, an outer member, and a composite tube with distinct interface regions. This segmentation allows each component to be optimized for specific functions - the inner member for axial load transfer, the outer member for bending load resistance, and the composite tube for structural integrity. The segmented design prevents stress concentration and redistribution while maintaining overall structural strength.

Inventive Principle:
Principle #1Segmentation

3Stability of the object's composition

If the composite tube end is constrained between inner and outer members, then movement restriction is achieved, but the joint requires additional components increasing complexity

Engineering Contradiction:
Improvemovement restriction under bending loadsVSAvoidnumber of joint components
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent employs a nested configuration where the inner member is positioned inside the composite tube, which is in turn surrounded by the outer member. This nested arrangement creates a compact, space-efficient joint structure that restricts tube end movement effectively. The nested design allows the components to work together synergistically without requiring additional external fastening elements, thus achieving stability without excessive complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Data Source

PatentEP3486503B1Designs and methods of making of joints for composite components under dominant bending load
Publication Date: 2025.02.19 GOODRICH CORP
  • EP3486503B1 patent drawingFigure 1~2
  • EP3486503B1 patent drawingFigure 3A
  • EP3486503B1 patent drawingFigure 3B

AI summary

A composite tube joint (401) may comprise an end of a composite tube (410), an inner member (420) disposed within the end, wherein an outer surface of the inner member has a complementary shape to an inner surface of the end, an outer member (431) concentrically surrounding the end of the composite tube, and an undulated surface (422,432) configured to mitigate movement of the end of the composite tube relative to at least one of the inner member (420) and the outer member (431).