Coil Spring Induction Heating for Shape-Memory Alloy Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Shape-memory alloys (SMAs) face challenges in fully transitioning back to their original shape after heating, particularly in applications where mechanical assistance is needed to ensure precise shape recovery.
Innovation Solution
A coil spring configuration that encompasses the SMA member, providing mechanical assistance and induction heating to facilitate shape changes, storing energy during heating and applying a return force during cooling to aid in shape recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate heating element and mechanical spring are used to assist SMA shape transition, then the SMA member can achieve reliable shape recovery, but the device weight and complexity increase
Solution Approach 1:
The patent combines the heating element and mechanical spring into a single integrated coil spring component. The coil spring serves dual functions: it generates heat through electrical current to trigger SMA phase transition, and it provides mechanical force to assist the SMA member in returning to its original shape during cooling. This merging eliminates the need for separate heating elements and springs, thereby reducing overall apparatus weight while maintaining reliable shape recovery functionality.
Solution Approach 2:
The coil spring is designed as a multi-functional component that simultaneously performs three roles: (1) as an induction coil to generate heat for SMA actuation, (2) as a mechanical spring to store and release elastic energy during shape transitions, and (3) as a structural support element. This multi-functionality reduces the total number of components needed, leading to weight reduction while ensuring reliable shape recovery through the combined thermal and mechanical assistance.
2Ease of manufacture
If separate heating element and mechanical spring are used, then each component can be optimized for its specific function, but the device becomes more complex and larger
Solution Approach 1:
The patent merges the heating element and mechanical spring into a single coil spring component, reducing the number of discrete parts from two to one. This integration simplifies the overall device structure and reduces assembly complexity, while the coil spring can still be manufactured with optimized properties for both heating efficiency and mechanical performance through material selection and geometric design.
Solution Approach 2:
The coil spring is designed as a multi-functional component that simultaneously performs heating, mechanical assistance, and structural support functions. This multi-functionality reduces the total component count and simplifies the device architecture, making it easier to manufacture and assemble while maintaining the ability to optimize performance through careful design of the coil spring's material properties, geometry, and electrical characteristics.
3Reliability
If the coil spring is electrically isolated from the SMA member, then electrical safety is improved, but the induction heating efficiency may be reduced
Solution Approach 1:
The coil spring acts as an intermediary between the electrical power source and the SMA member. Electrical current flows through the coil spring windings, which generate an alternating magnetic field that induces eddy currents in the conductive SMA member, thereby heating it through electromagnetic induction. This intermediary arrangement ensures electrical isolation between the power source and SMA member (improving safety) while maintaining efficient energy transfer through the magnetic field coupling.
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 configuration enables lighter, more compact SMA apparatuses that efficiently transition between high-temperature and low-temperature shapes, ensuring accurate shape recovery and extending the usability of SMAs in various applications.
Implementation Method 1
The coil spring is configured to conduct current from a power source to generate a magnetic field that induces heat in the SMA member
Implementation Method 2
SMAs, such as Nickel-Titanium (Ni—Ti), display two distinct crystal structures or phases. Martensite form exists at lower temperatures, and austenite form exists at higher temperatures. When the SMA is in martensite form at lower temperatures, it can be easily formed to a desired shape. When the SMA is in austenite form at higher temperatures, it can be 'trained' to transition into another shape
Implementation Method 3
the coil spring is configured to load when the SMA member transforms from one shape to another, and to release and apply a return force to the SMA member to assist in transforming back to the previous shape
Data Source
AI summary
Apparatus that use Shape-Memory Alloy (SMA) materials. An exemplary apparatus includes an SMA member that transforms between a first shape and a second shape based on temperature. The apparatus also includes a coil spring that encompasses the SMA member. The coil spring conducts current from a power source to generate a magnetic field that induces heat in the SMA member. The coil spring also stores mechanical energy as the SMA member transforms from the first shape to the second shape when heated to a transition temperature, and exerts force on the SMA member from the mechanical energy to assist the SMA member in transforming from the second shape to the first shape when cooling below the transition temperature.