SMA Pre-Loaded Deployment Hinge for Spacecraft
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Solution Overview
Problem
Spacecraft deployable structures, such as antenna booms, face significant performance issues due to small misalignments at hinge interfaces, which can cause substantial system performance degradation, particularly at large distances, necessitating a low-compliance hinge solution.
Innovation Solution
The implementation of a latching hinge with a shape-memory alloy (SMA) pre-load device that induces a pre-load perpendicular to the hinge pivot axis when closed, using a one-way SMA and an electrical heating element to expand and load the latch mechanism, ensuring gapless contact and minimizing compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hinge is used to connect deployable structures to the spacecraft main body, then the hinge allows rotation for deployment, but the hinge exhibits compliance and misalignment that significantly degrade system performance at large distances
Solution Approach 1:
The SMA pre-load device is pre-configured in a compressed state during manufacturing and installed in the hinge assembly. When activated by heating, it automatically generates the pre-load force to close gaps and align contact surfaces, performing the alignment action in advance before the hinge is fully operational, thereby eliminating the need for post-deployment adjustment and ensuring precise alignment from the outset
Solution Approach 2:
The invention utilizes the phase transformation temperature parameter of the shape memory alloy to control the pre-load generation. By heating the SMA material above its transformation temperature, the material undergoes a phase change that causes it to expand and generate mechanical pre-load force, thereby dynamically adjusting the hinge alignment based on temperature parameter changes rather than relying on fixed mechanical tolerances
2Manufacturing precision
If the hinge interface is designed with tight tolerances to minimize misalignment, then alignment precision improves, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The invention replaces the traditional mechanical pre-load mechanism (such as springs, adjustables, or complex latch systems) with a shape memory alloy-based pre-load device. The SMA element uses its inherent phase transformation properties to generate pre-load force, substituting complex mechanical components with a simpler, intelligent material-based solution that automatically adapts to thermal conditions
Solution Approach 2:
The hinge assembly incorporates a composite structure combining the shape memory alloy pre-load device with the traditional hinge mechanical components. This composite approach integrates the adaptive pre-load generation capability of SMA materials with the robust mechanical linkage of the hinge, creating a unified system that achieves precise alignment without requiring separate adjustment mechanisms or overly tight manufacturing tolerances
3Manufacturing precision
If a shape-memory alloy pre-load device is added to the hinge to reduce compliance, then alignment precision improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The SMA pre-load device is designed to serve multiple functions within the hinge assembly: it provides pre-load force to close gaps, generates alignment force to position contact surfaces, and acts as a damping element to reduce compliance. By integrating one component that performs multiple functions, the invention avoids the need for separate pre-load springs, alignment adjustables, and damping elements, thereby simplifying the overall manufacturing process despite the introduction of SMA material
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 SMA pre-load device effectively reduces compliance and ensures precise alignment of deployable structures, enhancing system performance by maintaining contact and preventing misalignment-induced performance degradation.
Implementation Method 1
The SMA pre-load device may be configured to transition from a first phase to a second phase when heated to a transformation temperature
Implementation Method 2
When the SMA pre-load device is transitioned from the first phase to the second phase while the latching hinge is in the hinge-closed condition, expansion of the SMA pre-load device may load the latch mechanism
Implementation Method 3
The SMA pre-load device may include a thick-wall tube of SMA and an electrical heating element configured to heat the SMA to the transformation temperature
Data Source
AI summary
Latching or locking deployment hinges are provided that include a shape-memory alloy (SMA) pre-load device configured to induce a pre-load across a contact interface of the latching hinge in a direction substantially perpendicular to the hinge pivot axis when the latching hinge is in a closed condition. The hinges may be sprung or actuated using a powered drive mechanism. Some implementations may feature a sprung latch/hook that is tensioned using the SMA pre-load device. Some other implementations may feature a multi-bar linkage that is tensioned using the SMA pre-load device.