Nested SMA Torque Tubes for Compact High-Power Rotary Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional rotary actuators in aerospace and other applications face inefficiencies due to high mass, footprint, and power requirements, leading to design constraints such as air drag, fuel consumption, noise, and complexity, which limit their scalability and reliability.
Innovation Solution
The use of nested Shape Memory Alloy (SMA) torque tubes, which can provide high force and power density through thermal or mechanical stimuli, allowing for compact, lightweight, and efficient rotary actuation systems by integrating SMA materials in concentric configurations within actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rotary actuators (hydraulic, pneumatic, electric, or mechanical) are used, then reliable actuation can be achieved, but the mass, footprint, and power requirements become excessive
Solution Approach 1:
The patent employs nested SMA torque tubes where multiple SMA elements are arranged concentrically within each other. This nesting configuration allows multiple actuation functions to be integrated in a compact radial space, significantly reducing the overall actuator footprint and mass while maintaining reliable actuation through the combined action of nested SMA elements
Solution Approach 2:
The patent utilizes Shape Memory Alloy (SMA) materials with superelastic and shape memory properties as the primary actuating mechanism. These composite material properties enable the actuator to achieve reliable actuation through phase transformation and elastic recovery, eliminating the need for heavy conventional actuator components while maintaining operational reliability
2Ease of operation
If conventional rotary actuators are used, then actuation can be provided, but the footprint and complexity increase
Solution Approach 1:
The nested configuration of SMA torque tubes allows the actuator to provide full rotary actuation capability within a minimal radial footprint. Each nested SMA element contributes to the overall actuation function, enabling compact integration while maintaining complete actuation capability through the coordinated deformation of nested elements
Solution Approach 2:
The nested SMA torque tube structure provides multiple functions within a single compact assembly: actuation through SMA phase transformation, mechanical coupling between nested elements, and integrated return mechanism through superelastic recovery. This multi-functionality eliminates the need for separate components, reducing overall footprint while maintaining full actuation capability
3Power
If conventional actuators are used, then power can be delivered, but the power density is limited
Solution Approach 1:
The patent exploits the unique properties of Shape Memory Alloy materials, particularly their high energy density during phase transformation and superelastic recovery. These composite material characteristics enable the actuator to deliver high power output relative to its mass, achieving superior power density by converting thermal and mechanical energy directly into rotational motion through SMA phase changes
Solution Approach 2:
The actuator utilizes SMA phase transitions (austenite-martensite transformation) as the primary mechanism for power delivery. During phase transition, the SMA material absorbs and releases large amounts of energy, enabling high power density actuation. The phase transition mechanism allows the actuator to deliver substantial power in a compact mass by leveraging the inherent energy storage and release capabilities of the phase-changing material
4Ease of operation
If conventional actuators are used, then actuation can be achieved, but the design complexity and component count increase
Solution Approach 1:
The patent merges multiple actuation functions and mechanical elements into a single integrated nested SMA torque tube assembly. The nested SMA elements, coupling mechanisms, and return paths are combined into one compact structure, eliminating the need for separate housings, lubrication systems, and maintenance components associated with conventional actuators, thereby reducing design complexity while maintaining full actuation function
Solution Approach 2:
The nesting arrangement inherently simplifies the overall design by integrating multiple functional elements within each other. The nested SMA torque tubes serve as both the actuating elements and the structural framework, eliminating the need for separate mounting structures, alignment mechanisms, and external biasing elements, thus reducing design complexity while preserving actuation capability
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
This solution enables lighter, more reliable, and higher power density actuation with reduced complexity and size, suitable for applications where space and weight are critical, such as in aircraft, spacecraft, and automotive systems, while also improving actuation reliability and reducing the need for external biasing elements.
Implementation Method 1
SMAs that have the unique ability to recover large deformations in response to thermal, mechanical and/or magnetic stimuli. As is known in the art, SMA behavior occurs by virtue of a crystallographically reversible martensitic phase transformation between a high symmetry parent austenite phase and a low symmetry martensite phase.
Implementation Method 2
The inner tube is made of a mechanically activated shape memory alloy (superelastic)
Data Source
AI summary
A plurality of shape memory alloy tubes (SMTs) of one or more shape memory alloy (SMA) types is configured as an element in a rotary actuator system in a nested manner. In various configurations, the nested SMTs provide one or more modes of multiplication (torque output or angular displacement), rotation reversibility and bias loading. The innovation provides for leveraging the modes for reductions in the rotary actuator system size, weight, or complexity or combinations thereof, or providing improved and more stable actuation capabilities in a given envelope.