Frangible Fastener Assembly for Torque-Limited Secure Release
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Solution Overview
Problem
Frangible fasteners are limited by the amount of torque that can be applied during installation, which can lead to premature failure if excessive torque is applied, and existing torque control bolts do not effectively prevent damage to components when torque exceeds a set value.
Innovation Solution
A frangible fastener system comprising a first fastener with a head portion, 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 frangible portion to separate and releasing the second retained member from the first retained member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If torque control bolts are used to limit installation torque, then component damage is prevented, but the fastening reliability is reduced due to premature failure
Solution Approach 1:
The fastening system is divided into two separate fasteners: a first fastener that provides permanent structural attachment, and a second frangible fastener that provides controlled, reversible attachment. This segmentation allows each fastener to be optimized for its specific function, resolving the contradiction between preventing damage and maintaining reliability.
Solution Approach 2:
The frangible portion of the second fastener acts as an intermediary torque-limiting element that protects the retained member from damage while allowing the first fastener to provide reliable permanent attachment. The frangible portion breaks at a predetermined torque threshold, serving as a protective mediator between the tightening tool and the retained member.
2Object-affected harmful factors
If frangible fasteners are designed to break at low torque, then component damage is prevented, but the fastening strength is insufficient for secure attachment
Solution Approach 1:
The system merges a first fastener designed for high-strength permanent attachment with a second frangible fastener designed for controlled attachment and release. Together, they provide both the strength needed for secure attachment and the torque limitation needed to prevent damage.
Solution Approach 2:
The second frangible fastener is designed to break under excessive torque conditions, providing partial attachment strength that is sufficient for normal operation but intentionally insufficient to prevent breaking under overload, thus protecting the retained member.
3Device complexity
If a single fastener is used for both permanent and removable attachment, then device complexity is reduced, but the ease of operation is compromised due to inability to control release
Solution Approach 1:
The fastening system is segmented into a first fastener for permanent attachment and a second frangible fastener for controlled attachment and release. This segmentation enables independent optimization of each fastener's properties, allowing the second fastener to be specifically designed with a frangible portion that breaks at a predetermined force, providing ease of controlled release.
4Ease of operation
If torque limitation is built into a single fastener, then ease of operation is improved, but the reliability is reduced due to premature failure
Solution Approach 1:
The system segments the fastening function into two independent fasteners, allowing the second fastener to incorporate torque limitation features for ease of operation while the first fastener provides reliable permanent attachment that is not subject to premature failure.
Solution Approach 2:
The frangible portion of the second fastener serves as an intermediary element that limits torque during installation, protecting the retained member while allowing the first fastener to provide reliable attachment. This intermediary approach resolves the contradiction between ease of torque control and fastening reliability.
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 system ensures secure retention of components until a targeted breaking force is reached, preventing premature failure and damage by allowing controlled separation of the fasteners, suitable for applications like securing inflatable safety equipment on aircraft.
Implementation Method 1
Frangible fasteners break when subjected to forces above threshold levels. The frangible portion is configured to separate responsive to receiving a breaking force
Data Source
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AI summary
This disclosure relates to a frangible fastener system configured to secure a second retained member to a first retained member until the frangible fastener system receives a breaking force. The frangible fastener system may comprise a first fastener and a second fastener. The first fastener may comprise a flange configured to cause retention of the first retained member toward a base member. The first fastener may be configured to engage the base member and to receive the second fastener along a first axis of the frangible faster system. The second fastener may comprise a frangible portion configured to separate responsive to receiving the breaking force, and a head portion connected to the frangible portion. The head portion may be configured to cause retention of the second retained member toward the first retained member until the frangible portion separates responsive to receiving the breaking force.