Composite Fastener Strap Joint for Quick Shell Assembly
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Solution Overview
Problem
The challenge lies in the assembly, disassembly, and fixing of extremely lightweight composite shell structures using conventional fastening techniques, which create stress raisers and increase assembly and disassembly time due to the need for multiple fasteners, while also adding weight and complexity.
Innovation Solution
A lightweight, flexible composite fastener strap with stiffening ribs that locks into channels on composite shell structures, allowing for a load-bearing connection without stress raisers, enabling quick assembly and disassembly, and maintaining a flush interface for aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional fastening techniques (multiple fasteners) are used to connect composite shell structures, then the connection strength is improved, but the weight increases and assembly/disassembly time increases
Solution Approach 1:
The fastening system is segmented into a strap component and multiple discrete fasteners distributed along the strap. This segmentation allows the load to be distributed across multiple attachment points while using a single continuous strap element, reducing assembly time compared to installing multiple separate fasteners while maintaining connection strength.
Solution Approach 2:
Multiple fastening functions are merged into a single strap assembly that incorporates both the strap body and multiple integrated fasteners. This merging allows the entire fastening system to be installed as one unit rather than requiring sequential installation of multiple separate fasteners, significantly reducing assembly and disassembly time while maintaining the strength benefits of multiple attachment points.
2Strength
If conventional fastening techniques (multiple fasteners) are used to connect composite shell structures, then the connection strength is improved, but the device complexity increases
Solution Approach 1:
The strap and multiple fasteners are merged into a single integrated assembly. This reduces device complexity by eliminating the need to handle, position, and secure multiple separate fastener components independently. The integrated design simplifies the fastening system while maintaining the distributed load-bearing capacity of multiple attachment points.
Solution Approach 2:
The strap serves multiple functions simultaneously: it acts as the structural element that distributes load, as the mounting mechanism for fasteners, and as the connecting element between composite shell structures. This multi-functionality reduces the number of separate components needed, thereby reducing overall system complexity while maintaining connection strength.
3Strength
If conventional fastening techniques are used to connect composite shell structures, then the connection strength is improved, but the weight increases
Solution Approach 1:
The strap is designed with non-uniform properties: wider and stiffer sections at fastener attachment locations to handle concentrated loads, and narrower, more flexible sections between fasteners to reduce weight and allow conformability to the shell surface. This local quality optimization maintains connection strength at critical points while minimizing overall weight.
Solution Approach 2:
The strap's physical parameters (width, thickness, material composition) are varied along its length to optimize the strength-to-weight ratio. By adjusting these parameters locally based on load requirements, the design achieves adequate connection strength with minimum necessary weight, avoiding the excess weight that would result from uniformly thick or oversized fasteners.
4Strength
If conventional fastening techniques are used to connect composite shell structures, then the connection strength is improved, but stress raisers are created along the joint
Solution Approach 1:
The connection is segmented into multiple discrete fastener attachment points along the strap rather than using a single continuous rigid connector. This segmentation distributes the stress along the joint line, preventing stress concentration at any single location and reducing the formation of stress raisers that would compromise the composite shell structure.
Solution Approach 2:
The strap is designed with localized flexibility and compliance at fastener attachment points, allowing slight deformation to accommodate thermal expansion and contraction of the composite shells. This local quality adjustment prevents rigid constraint-induced stress raisers while maintaining overall connection strength through the distributed fastener system.
Data Source
AI summary
A system may include a fastener strap, a first component, and a second component. The fastener strap may include a strap section, at least one first stiffening rib section, and at least one second stiffening rib section. The first component may include a first strap section channel and at least one first stiffening rib section channel positioned along the first strap section channel. The second component may include 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 may be formed between the first component and the second component.