Cam-Lock Expandable Fastener for Honeycomb Panel Attachment
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Solution Overview
Problem
Current fastener systems for attaching components to honeycomb panels in aircraft are costly, labor-intensive, and have suboptimal reliability and strength, particularly when subjected to varying temperatures and vibrations, with existing locking mechanisms providing limited structural integrity.
Innovation Solution
A bolt-lock fastener system with a radially-expandable split collar assembly that includes a bolt-lock with an internal bore, anti-rotator assembly, and collars that expand radially to secure the fastener in place, allowing for secure attachment and easy removal from honeycomb panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing panel attachment systems (threaded fasteners, U-shaped clips, nut riveted to structural member) are used, then components can be attached to honeycomb panels, but the systems are costly, labor-intensive, and have suboptimal reliability and strength
Solution Approach 1:
The fastener system is divided into distinct functional components: a fastener body with a first end for insertion and a second end for tool engagement, a separate locking mechanism, and an optional retaining collar. This segmentation allows each component to be optimized for its specific function while simplifying the overall assembly process and improving reliability through specialized design of each element.
Solution Approach 2:
The locking mechanism is positioned within the fastener body, with the retaining collar fitting over the fastener body. This nested arrangement consolidates multiple functions into a compact structure, reducing the number of separate parts and assembly steps while maintaining high reliability and strength characteristics.
2Reliability
If locking mechanisms are added to maintain torque tolerance in varying temperatures and vibrations, then reliability improves, but device complexity and cost increase
Solution Approach 1:
The locking mechanism is designed to automatically engage and maintain torque tolerance without requiring additional operational steps or complex control systems. The mechanism self-adjusts to maintain proper torque levels despite varying temperatures and vibrations, eliminating the need for manual intervention or complex external locking systems.
Solution Approach 2:
The locking mechanism utilizes material properties and geometric parameters that respond to environmental conditions (temperature and vibration) to maintain consistent torque tolerance. By designing the locking features with appropriate clearance, elasticity, and friction characteristics, the system automatically compensates for environmental variations without adding complexity.
3Ease of manufacture
If current fastener systems are used, then attachment function is achieved, but cost and labor intensity are high
Solution Approach 1:
The fastener body is designed as a simple, easily manufactured component that can be produced cost-effectively through standard manufacturing processes. The simplified geometry and use of common materials reduce production costs and manufacturing complexity while maintaining adequate structural integrity for the application.
Solution Approach 2:
The fastener system may utilize composite material construction, particularly for the retaining collar and locking mechanism components, combining materials with different properties to achieve optimal strength-to-cost ratio. This allows high reliability where needed while keeping overall manufacturing costs low.
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 and strength while maintaining cost-effectiveness, enabling secure attachment and easy removal from panels under varying conditions.
Implementation Method 1
collars that expand radially to secure the fastener in place
Implementation Method 2
Expandable diameter fastener with cam-lock feature
Data Source
AI summary
The present disclosure relates to 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 may be provided with a radially-expandable collar assembly, an anti-rotator assembly, a shaft, and a bolt-lock.