Fastener Strap Connection for Lightweight Composite Shell Joints

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Solution Overview

Problem

The challenge lies in the assembly, disassembly, and fixing of extremely lightweight composite shell structures with equivalent strong and lightweight fastening solutions, as conventional methods create stress raisers and add weight, complexity, and time to the assembly and maintenance processes.

Innovation Solution

A fastener strap system with stiffening ribs that lock into channels of composite shell structures, providing a lightweight, flexible connection capable of transmitting compressive and tensile loads without stress raisers, and allowing for quick assembly and disassembly, using a support frame for additional load-bearing support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional fastening techniques (rows of fasteners, bolts, nuts) are used to connect composite shell structures, then strong load-bearing connection is achieved, but weight increases significantly and point stress-loadings create stress raisers

Engineering Contradiction:
Improveload-bearing connection strengthVSAvoidfastening system weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The fastening system is segmented into a strap portion that distributes load across multiple discrete attachment points (first and second attachment structures) rather than using continuous rows of fasteners. This segmentation allows the load to be transferred through multiple localized connections, maintaining strength while reducing overall weight compared to traditional multi-fastener approaches.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention replaces the traditional mechanical fastening system (multiple bolts, nuts, and washers) with a strap-based tensioning system that uses friction and geometric interlocking at attachment points. This substitution eliminates the need for heavy threaded fasteners while maintaining load-bearing capacity through distributed stress transfer.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If rows of fasteners are used to ensure strong connection, then load-bearing capacity is improved, but assembly and disassembly complexity increases significantly

Engineering Contradiction:
Improvejoint load-bearing capacityVSAvoidfastening system complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The complex fastening system is segmented into modular attachment structures integrated into the composite shell components themselves. The strap portion interacts with these pre-formed attachment points, eliminating the need for multiple discrete fasteners and simplifying both the design and assembly/disassembly processes while maintaining strong load-bearing connections.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The attachment structures are self-contained features of the composite shell components, with the strap portion serving as both the connecting element and the tensioning mechanism. The system is self-adjusting through friction at the attachment points, eliminating the need for complex fastening procedures and multiple components.

Inventive Principle:
Principle #25Self-service

3Strength

If multiple fasteners are used to create strong connections, then connection strength is improved, but assembly and maintenance time increases significantly

Engineering Contradiction:
Improveconnection strengthVSAvoidassembly and maintenance time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The connection system is segmented into a single strap portion that interacts with multiple integrated attachment points, allowing the entire connection to be made or released by manipulating one component rather than multiple fasteners. This dramatically reduces assembly and maintenance time while maintaining connection strength through distributed load transfer at the attachment points.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3581483B1Load-transferring connection between structurally loaded components
Publication Date: 2021.05.12 ROCKWELL COLLINS INC
  • EP3581483B1 patent drawingFigure 1
  • EP3581483B1 patent drawingFigure 2
  • EP3581483B1 patent drawingFigure 3

AI summary

A system may include a fastener strap, a first component, and a second component. The fastener strap includes a strap section, at least one first stiffening rib section, and at least one second stiffening rib section. The first component includes a first strap section channel and at least one first stiffening rib section channel positioned along the first strap section channel. The second component includes a second strap section channel and at least one second stiffening rib section channel positioned along the second strap section channel. When the fastener strap is installed in the first strap section channel, the at least one first stiffening rib section channel, the second strap section channel, and the at least one second stiffening rib section channel, a load-bearing connection are formed between the first component and the second component.