Expandable Split-Collar Fastener for Honeycomb Panel Attachment
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Solution Overview
Problem
Current fastener systems for attaching components to honeycomb panels in aircraft are unsatisfactory due to high costs, labor-intensive assembly, suboptimal reliability, and limited structural integrity, particularly under varying temperatures and vibrations.
Innovation Solution
A bolt-lock fastener system with a radially-expandable split collar assembly that securely attaches honeycomb panels by expanding and compressing collars to maintain structural integrity and facilitate easy assembly and disassembly, utilizing a combination of collars and an anti-rotator assembly to ensure secure locking and ease of removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If existing panel attachment systems use threaded nuts and bolts or U-shaped clips, then the fastening function is achieved, but the assembly process becomes labor-intensive and alignment is difficult
Solution Approach 1:
The fastener is divided into distinct functional segments: a collar portion that interfaces with the panel, a shaft portion that provides structural support, and a head portion that enables tool engagement. This segmentation allows each part to be optimized independently and simplifies the overall assembly process
Solution Approach 2:
The fastener incorporates self-aligning features including a self-centering collar design and integrated alignment elements that automatically position the fastener correctly during insertion, eliminating the need for manual alignment operations
2Device complexity
If existing fasteners use simple bolt and nut configurations, then the structure is simple, but reliability and strength are suboptimal under varying temperatures and vibrations
Solution Approach 1:
The collar is designed with variable wall thickness and optimized geometric parameters that allow it to maintain structural integrity across a wide range of temperatures while absorbing vibration through controlled deformation
Solution Approach 2:
The fastener combines materials with different properties - the collar portion uses material optimized for thermal stability and vibration damping, while the shaft and head use materials optimized for strength and rigidity, creating a composite structure that performs reliably under varying conditions
3Ease of manufacture
If panel inserts are potted in with glue to hold position, then the insert is retained, but structural integrity is limited and torque tolerance cannot be maintained under vibration
Solution Approach 1:
The invention replaces the chemical bonding mechanism (glue/potting) with a mechanical locking system featuring a collar with external threading that engages with a nut or threaded hole, providing maintainable torque and vibration resistance through mechanical engagement rather than adhesive bonding
4Reliability
If retaining collars are made of resilient material like Dupont Vespel, then floating inserts are retained, but the system becomes expensive and labor-intensive to implement
Solution Approach 1:
The collar serves multiple functions simultaneously: it provides structural support as part of the fastener, acts as a retention mechanism through its threading engagement, and enables alignment during installation. This multi-functionality eliminates the need for separate retaining collars made of specialized resilient materials
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The bolt-lock fastener system enhances structural integrity, reduces assembly complexity, and improves reliability while maintaining cost-effectiveness, enabling secure attachment of honeycomb panels across varying environmental conditions.
Implementation Method 1
a radially-expandable split collar assembly that securely attaches honeycomb panels by expanding and compressing collars
Data Source
AI summary
A fastener system for use in securing objects, such as stress skinned panels, to a structural support, such as an aircraft spar or cross member. The fastener system includes a radially-expandable collar assembly.