Shape Memory Hold-Release Assembly for Low-Shock Tie Rod Release
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Solution Overview
Problem
Existing devices for holding and releasing stacking tie rods generate shock during release, are not reusable without dismantling, and are not suited for the size requirements of nanosatellites.
Innovation Solution
A reusable device comprising a tightening component, a hold and release component with multiple segments, and a loosening component made of single-acting shape memory material, which switches from holding to release configuration without shock by compensating tightening pressure with loosening pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnic means are used to release the stacking tie rod, then the release function is achieved, but shock is generated during release
Solution Approach 1:
The patent replaces the pyrotechnic release mechanism with a shape memory alloy-based mechanical system. The shape memory alloy wire (NiTi alloy) transforms from austenite phase to martensite phase under thermal or electrical stimulus, generating controlled mechanical force to release the tie rod without combustion or explosion, thereby eliminating shock while maintaining reliable release function.
Solution Approach 2:
The patent utilizes phase transformation parameters of the shape memory alloy material. By changing the temperature or electrical stimulus parameters, the alloy transitions between austenite (high strength, locked state) and martensite (low strength, released state) phases, enabling controlled release without shock generation.
2Reliability
If conventional tightening elements are used to hold the tie rod, then the holding function is achieved, but the device cannot be reset in situ
Solution Approach 1:
The shape memory alloy wire serves both as the tightening element and the release mechanism. After release, the wire can be reactivated by applying thermal or electrical stimulus to restore its austenite phase and regaining its high strength, allowing the device to reset itself in situ without dismantling or replacement.
Solution Approach 2:
The patent employs reversible phase transitions of the shape memory alloy between austenite and martensite states. The alloy remains in austenite phase during holding, transitions to martensite for release, and can be reactivated by reversing the phase transition, enabling multiple reuse cycles without dismantling.
3Reliability
If existing release devices are used, then the release function is achieved, but the size is not suited for nanosatellites
Solution Approach 1:
The patent uses a thin wire-shaped shape memory alloy as the core release mechanism, replacing bulky pyrotechnic charges or complex mechanical release systems. This wire-based approach enables compact integration into nanosatellite constraints while maintaining reliable release function.
Solution Approach 2:
The shape memory alloy wire performs multiple functions: it acts as the tightening element, the release actuator, and the sensing element. This multi-functionality reduces the number of separate components needed, thereby minimizing device volume for nanosatellite applications.
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 device effectively switches from holding to release configuration without generating shock, is reusable by replacing the deformed tightening component, and is compact enough for use with nanosatellites.
Implementation Method 1
The material is configured so that from a transition temperature, each end of the at least one loosening component exerts, on the second bearing surface of each segment of the at least two other segments, a loosening pressure
Implementation Method 2
The at least one loosening component is made of a first single-acting shape memory material
Implementation Method 3
the deformation of the tightening component is a plastic deformation, the tightening component being made of a second material capable of being plastically deformed
Data Source
AI summary
A reusable device for holding and releasing a bar. The device includes a tightening component, a hold and release component, and at least one loosening component. The hold and release component includes a plurality of segments, each segment includes a first bearing surface configured to bear on part of the bar, when the plurality of segments is in a holding configuration under the effect of a tightening pressure generated by the tightening component. The plurality of segments includes a second bearing surface configured to bear on one end of the at least one loosening component. The at least one loosening component is made from a first single-acting shape memory material. Each end of the at least one loosening component exerting a loosening pressure compensating for the tightening pressure, so as to place the hold and release component in a configuration in which the part of the arm is released.