Frangible Fastener Assembly for Torque-Independent Release
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Solution Overview
Problem
Frangible fasteners are limited by the torque applied during installation, which can prevent them from breaking when subjected to forces above the threshold, compromising their ability to securely separate structural components under high pressure.
Innovation Solution
A frangible fastener system comprising a first fastener with a head, body, and threaded portion, and a second fastener with a frangible portion, tool engagement portion, and threaded portion, designed to secure a second retained member to a first retained member until a breaking force is applied, causing the second fastener to separate and release the second retained member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single frangible fastener is used to secure structural components, then the device complexity is reduced, but the reliability of secure retention under high force conditions deteriorates because the fastener may break during installation due to torque limitations
Solution Approach 1:
The fastener system is divided into two distinct fasteners: a first fastener that provides primary secure retention by engaging the first retained member to the base member, and a second frangible fastener that provides secondary retention for the second retained member. This segmentation allows each fastener to be optimized for its specific function, with the first fastener designed for high torque resistance and the second fastener designed for controlled breaking at a specific force threshold, thereby resolving the contradiction between device complexity and reliability.
2Ease of operation
If the torque applied during installation is limited to prevent fastener breaking, then the ease of operation is improved, but the strength of retention under normal conditions deteriorates because the fastener cannot securely hold components under high pressure
Solution Approach 1:
The retention function is segmented between two fasteners with different mechanical properties. The first fastener is designed with high torque capacity to provide strong retention during installation and under normal operating conditions, while the second frangible fastener is designed with lower torque capacity to break at a predetermined force threshold. This allows the system to achieve both ease of installation (limited torque required) and strong retention (first fastener provides primary securing) simultaneously.
Solution Approach 2:
Different fasteners are applied to different locations in the fastening system based on local requirements. The first fastener location requires high strength and torque resistance for primary structural retention, while the second fastener location requires frangible properties for controlled separation. This local differentiation of fastener properties resolves the contradiction between installation ease and retention strength.
Data Source
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AI summary
There is described a frangible fastener system comprising a first fastener configured to secure a first retained member to a base member, and a second fastener configured to couple with the first fastener along a first axis of the fastener system and secure a second retained member to the first retained member until receiving a breaking force such that a first end of the second fastener separates from the first fastener, and the second retained member separates from the first retained member responsive to the fastener system receiving the breaking force. The second fastener comprises: (a) a frangible portion located toward the first end of the second fastener configured to separate responsive to receiving the breaking force; and (b) a tool engagement portion configured to engage a tightening tool, the tool engagement portion located adjacent to the frangible portion toward a second end of the second fastener along the first axis, the tool engagement portion and the second end of the second fastener remaining coupled with the first fastener after the first end of the second fastener separates from the first fastener.