Frangible Nut Radial Expansion Separation Fastener
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Solution Overview
Problem
Existing pyrotechnically released separation fastener assemblies face challenges in efficiently releasing secured components due to limitations in radial expansion mechanisms, which can lead to increased assembly complexity and reduced reliability.
Innovation Solution
A separation fastener assembly featuring a frangible nut with interconnected segments and a movable piston that restrains and then allows radial expansion, activated by a pyrotechnic charge or torque, facilitating the release of secured components by fracturing the nut into discrete segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pyrotechnic charge is used to release secured components, then the release function is achieved, but the assembly complexity increases
Solution Approach 1:
The patent extracts the pyrotechnic charge from the traditional nut structure and relocates it to a separate initiator positioned adjacent to the nut. This separation allows the nut to be a simpler frangible structure without embedded pyrotechnics, while the initiator handles the pyrotechnic function independently, thereby reducing overall assembly complexity while maintaining reliable release functionality.
2Ease of operation
If discrete nut segments are used for radial expansion, then component release is enabled, but the manufacturing precision requirements increase
Solution Approach 1:
The nut is divided into multiple frangible segments connected by fracture lines, allowing controlled radial expansion when the frangible material fails. This segmentation enables the nut to transition from a rigid closed structure to an expanded state that releases the bolt, improving ease of operation while the fracture lines provide predetermined failure paths that reduce manufacturing precision requirements compared to fully discrete segments.
Solution Approach 2:
The nut transitions from a static closed structure to a dynamic expanded state through controlled fracture of the frangible material. This dynamic transformation allows the nut segments to move radially outward in response to pyrotechnic actuation, enabling component release while the frangible design provides a predictable failure mode that simplifies manufacturing tolerances.
3Reliability
If a movable element is added to restrain and release the nut, then the separation process reliability is enhanced, but the device complexity increases
Solution Approach 1:
A movable element acts as an intermediary between the pyrotechnic initiator and the frangible nut. This element is positioned to be displaced by pyrotechnic gas pressure, which then allows the nut segments to radially expand and release the bolt. The intermediary converts the pyrotechnic energy into controlled mechanical motion, enhancing separation reliability while keeping the mechanism relatively simple through direct force transmission.
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 solution enables reliable and efficient release of secured components by allowing radial expansion of the nut segments in response to an axial load, reducing assembly complexity and enhancing the reliability of the separation process.
Implementation Method 1
A pyrotechnic charge that is actuated to release the components
Implementation Method 2
Fracturing of the nut may occur in response to torque introduced by the bolt during assembly or upon actuation of the separation fastener
Data Source
AI summary
A separation fastener assembly includes a housing defining a cavity. A frangible nut is disposed in the cavity. The nut includes a plurality of nut segments. The one-piece frangible nut greatly reduces existing assembly problems and difficulties. Adjacent nut segments are interconnected at fracture lines. A bolt has an end coupled to the nut. A movable element is disposed in the housing and movable from a first position to a second position. In the first position, the nut segments are restrained from radial expansion. In the second position the nut segments are permitted to radially expand for releasing the fastener assembly.