Shape Memory Alloy Joint for Satellite Panel Positioning
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Solution Overview
Problem
Existing moveable joints in space applications, such as those used in smaller satellites, face issues with non-adjustable panel positions, limited adjustability, and mechanical hinge lubrication challenges in vacuum environments, leading to potential damage from oscillations and suboptimal solar energy harnessing.
Innovation Solution
A moveable joint incorporating a shape-memory-alloy member that changes shape with heat to limit and control the biasing force provided by a torsion spring, allowing for adjustable panel positions and damping of vibrations, eliminating the need for lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical hinge with lubrication is used to enable panel movement, then the panel can be adjusted to different positions, but the lubrication may fail in vacuum environments and extreme temperatures causing oscillations and damage
Solution Approach 1:
The patent replaces the traditional mechanical hinge with a shape-memory-alloy-based joint mechanism. The SMA wire acts as both the actuator and the positioning mechanism, eliminating the need for mechanical hinges with lubrication. When the SMA wire is heated, it contracts to pull the panel to a specific position determined by its deformed shape, providing reliable position control without mechanical contact points that require lubrication.
Solution Approach 2:
The patent changes the physical state of the SMA wire through temperature control. By heating the SMA wire above its transformation temperature, it transitions from a deformed state to a recovered state, causing contraction that moves the panel. This parameter change (temperature) controls the mechanical behavior without requiring mechanical hinges or lubrication, solving the reliability issue in vacuum environments.
2Reliability
If a fixed pre-determined position is used for the panel, then the mechanism is simple and reliable, but the panel cannot be adjusted to optimize solar energy harnessing
Solution Approach 1:
The patent makes the panel positioning system dynamic by using SMA wire that can be repeatedly deformed and recovered. The deformed shape of the SMA wire determines a specific panel position, and by changing the deformed shape (e.g., through controlled deformation or selecting different SMA configurations), different positions can be achieved. This allows the system to adapt to different operational requirements while maintaining the simplicity and reliability of the SMA-based mechanism.
Solution Approach 2:
The patent utilizes the temperature-dependent shape memory effect to enable position adjustment. By controlling the temperature of the SMA wire, the panel can be positioned at different locations determined by the SMA's deformed shape at different temperatures. This provides adaptability for optimizing solar energy harnessing while maintaining system reliability through the inherent simplicity of the SMA mechanism.
3Ease of manufacture
If a wire with low melting point is used to restrain spring force, then the panel deployment is simple, but the wire must be melted to deploy which is not reversible and lacks precision
Solution Approach 1:
The patent replaces the melting wire mechanism with an SMA-based mechanical restraint system. The SMA wire is deformed to a specific shape that physically blocks the torsion spring from actuating the hinge. This mechanical blocking mechanism provides precise and reversible control - the panel can be deployed by heating the SMA wire to cause it to contract and unblock the spring, and this process is fully reversible without material degradation.
Solution Approach 2:
The patent utilizes the phase transition of the SMA wire between martensite and austenite phases through temperature control. When heated above the transformation temperature, the SMA wire transitions phase and changes shape, contracting to unblock the torsion spring and deploy the panel. This phase transition provides precise, reversible, and controllable deployment without the need to melt the wire, overcoming the limitations of the low-melting-point wire approach.
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
Enables adjustable panel positions, reduces vibrations, and operates effectively in vacuum environments without lubrication, enhancing the satellite's ability to harness solar energy and maintain mechanical stability.
Implementation Method 1
a shape-memory-alloy member connected to the first member and engageable with the second member, the shape-memory-alloy member being configured to change shape when heated
Data Source
AI summary
A moveable joint including a first member and a second member moveably connected to the first member, a shape-memory-alloy member coupled to the first member and engageable with the second member, and a biasing member configured to bias the second member from a first position relative to the first member towards a second position relative to the first member. Movement of the second member between the first position and the second position is limited by the shape-memory-alloy member such that the position of the second member relative to the first member is determined by the shape of the shape-memory-alloy member.