Composite Shaft Joining Structure Without Fiber Cutting

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

When joining a composite member made of fiber-containing composite material to another member using a bolt, the reinforcement fibers in the composite member are cut, leading to a decrease in the strength of the composite member.

Innovation Solution

A joining structure is developed where a shaft member made of fiber-containing composite material is inserted into a hole of another member, allowing for secure joining without cutting the reinforcement fibers, and the shaft member is designed with varying widths and a hollow structure for enhanced support and weight reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a solid shaft member is used for joining, then the joining strength is improved, but the weight of the joining structure increases

Engineering Contradiction:

Improvejoining strengthVSAvoidweight of joining structure

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The invention employs a hollow shaft member instead of a solid shaft member for joining. The hollow structure reduces the weight of the joining component while maintaining sufficient structural strength for the joining function. This application of porous/hollow material principle directly addresses the weight reduction objective while preserving joining capability.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The shaft member is made of fiber-containing composite material, which provides high strength-to-weight ratio. This composite material selection allows the hollow shaft member to maintain adequate joining strength while significantly reducing weight compared to a solid shaft member made of conventional materials.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the shaft member has uniform width, then the manufacturing process is simplified, but the support and joining firmness is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidjoining firmness

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The shaft member features non-uniform width with different sections having different diameters. The first section has a first width, the second section has a second width larger than the first, and the third section has a third width smaller than the second. This local variation in geometry provides enhanced support and joining firmness at critical locations while maintaining manufacturability through conventional forming processes.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The shaft member is pre-formed with a specific non-uniform width profile before insertion into the hole. This preliminary shaping ensures that when the shaft member is inserted, the varying widths provide optimal support and joining characteristics without requiring additional machining or modification after insertion.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12222008B2Joining of fiber-containing composite material

Publication Date: 2025.02.11 NABTESCO CORP

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.