Shape Memory Winding Actuator for Compact High-Power Design
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Solution Overview
Problem
Existing shape memory material actuators face limitations in mechanical power, size, weight, and reactivity, making them unsuitable for compact and efficient applications, particularly in aerospace and autonomous systems, due to the use of compressed springs and large heating resistors, which result in vibrations, sudden energy release, and long deformation times.
Innovation Solution
A compact and lightweight actuator design utilizing a winding with electrically insulated contiguous turns made of shape memory material, which deforms in bending to provide mechanical power, allowing for efficient heating and quick transformation between shapes, thereby achieving higher mechanical power with reduced energy input and minimizing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a compressed spring is used as a driving member to provide mechanical energy, then the actuator can achieve sufficient mechanical power, but the actuator body becomes heavy and large due to the need to withstand permanent mechanical tension
Solution Approach 1:
The patent removes the compressed spring from the actuator system entirely, extracting the source of permanent mechanical tension. Instead, it uses shape memory alloy wire that can be heated to generate mechanical force only when needed, eliminating the need for a heavy spring mechanism and reducing the actuator body weight and size.
Solution Approach 2:
The patent replaces the mechanical spring-based energy storage system with a thermal-field-based system using shape memory alloy. The mechanical force is generated through phase transformation of the SMA wire when heated, substituting a mechanical energy storage mechanism with a thermally-actuated material system.
2Power
If a compressed spring is used to store and release mechanical energy, then the actuator can achieve sufficient mechanical power, but vibrations and shocks occur during energy release
Solution Approach 1:
The patent replaces the sudden mechanical energy release of a spring with a controlled thermal-actuated phase transformation process. The shape memory alloy wire gradually transforms from martensite to austenite phase when heated, producing smooth, continuous mechanical force without the sudden release and associated vibrations of spring-based systems.
Solution Approach 2:
The patent utilizes the solid-solid phase transition of the shape memory alloy between martensite and austenite phases. This phase transformation occurs progressively when the material is heated through its transformation temperature range, enabling controlled, vibration-free mechanical actuation compared to sudden spring release.
3Power
If larger quantities of shape memory material in block form are used to increase mechanical power, then greater mechanical energy can be provided, but heating becomes difficult and reactivity decreases
Solution Approach 1:
The patent segments the shape memory material into thin wire form rather than using large blocks. This segmentation increases the surface area to volume ratio, enabling much faster and more efficient heating. The wire can be uniformly heated by resistive heating or external sources, achieving rapid phase transformation and high reactivity while maintaining sufficient mechanical power output.
Solution Approach 2:
The patent uses thin wire form of shape memory alloy instead of bulky blocks. This thin-film/wire geometry allows for rapid heat penetration and uniform temperature distribution, dramatically reducing heating time and improving reactivity. The flexible wire can also be configured in various mechanical arrangements to achieve the desired actuation force.
4Weight of stationary object
If shape memory material actuators are designed to be compact and lightweight, then they are suitable for aerospace applications, but the mechanical power developed is limited
Solution Approach 1:
The patent optimizes key parameters of the shape memory alloy system including wire diameter, length, coil configuration, and transformation temperature range. By carefully selecting and adjusting these parameters, the actuator achieves high mechanical power output relative to its weight, optimizing the power-to-weight ratio for aerospace applications where both compactness and sufficient force are critical.
Solution Approach 2:
The patent employs shape memory alloy wire with specific compositional ratios (e.g., nickel-titanium alloys with optimized Ni:Ti ratios) to achieve desirable combinations of strength, ductility, and transformation characteristics. These composite material properties enable the lightweight actuator to generate sufficient mechanical power for demanding 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 actuator achieves higher mechanical power with reduced energy consumption, is compact and lightweight, and operates with minimal vibrations, enabling efficient and rapid shape transformation suitable for applications in aerospace and autonomous systems.
Implementation Method 1
The shape of such a material is modified by solid-solid phase transformation (called austenitic-martensitic compared to steels in particular) when it is subjected to a modification of its environment, in particular when it is heated above - or cooled below - a temperature, called the transformation temperature
Implementation Method 2
heating by Joule effect requires a very high intensity
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3a~3b
AI summary
The invention relates to an actuator comprising a body (1), a unit (2) that is able to move with respect to the body, two end stops, at least one of which is able to move with respect to the body and carries along the mobile unit under the effect of its own movement, a motor winding (41, 42) made of shape memory material and having at least one stable form, known as the memorized shape, being interposed between the two end stops which are spaced apart from one another at a different spacing depending on the shape of the motor winding, said mobile unit being moved under the effect of a variation in this spacing, characterized in that the motor winding is a winding having contiguous turns that are deformed from a first shape different from a memorized shape to a memorized shape by flexural deformation common to all the turns.