Self-Aligning Memory Alloy Wire Terminal for Stress Relief
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Solution Overview
Problem
Current memory alloy wire actuators face limitations due to shape memory strain being limited to 5%, resulting in a small usable stroke and sensitivity to fatigue at stress concentration points, particularly at the electrical termination, which reduces their operational life and volumetric efficiency.
Innovation Solution
The introduction of self-aligning terminals for memory alloy wire actuators, which reduce bending stress and allow direct mounting to the container body, enabling improved alignment and increased operational life by decoupling mechanical and electrical termination functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a memory alloy wire is rigidly fixed at both ends, then the wire can maintain structural stability, but the wire cannot undergo shape change when actuated
Solution Approach 1:
The termination structure is divided into a fixed portion (rigidly attached to the substrate) and a movable portion (capable of movement relative to the fixed portion). This segmentation allows the system to simultaneously achieve structural stability through the fixed portion and shape change capability through the movable portion, resolving the contradiction between stability and adaptability.
2Adaptability or versatility
If the wire is allowed to move freely to enable shape change, then the wire can be actuated, but the wire cannot maintain proper alignment with the substrate
Solution Approach 1:
The movable portion acts as an intermediary between the substrate and the memory alloy wire. It provides a controlled interface that allows the wire to move and change shape while maintaining proper alignment with the substrate. The movable portion mediates between the fixed substrate and the actuating wire, enabling both alignment precision and shape change capability.
3Manufacturing precision
If the termination structure is rigid and fixed, then the alignment is precise, but the wire cannot self-align during actuation
Solution Approach 1:
The termination structure transitions from a static, rigid design to a dynamic design where the movable portion can move relative to the fixed portion. This dynamic capability enables the wire to self-align during actuation while the fixed portion maintains precise alignment with the substrate, resolving the contradiction between alignment precision and self-alignment capability.
4Strength
If a rigid termination structure is used, then the structural integrity is maintained, but stress concentration occurs at the termination points
Solution Approach 1:
The termination structure employs different local qualities: the fixed portion provides rigid structural integrity where strength is needed, while the movable portion provides flexibility to reduce stress concentration. This local differentiation of structural properties allows the system to simultaneously achieve structural integrity and minimize harmful stress concentration at the termination points.
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 self-aligning terminals enhance the operational life and usable stroke of memory alloy wire actuators by reducing stress concentrations and assembly tolerances, leading to a more robust and reliable actuation mechanism.
Implementation Method 1
The artificial muscle includes a memory alloy wire that can be actuated to change shape
Data Source
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AI summary
A self-aligning memory alloy wire actuator has a memory alloy wire having first and second ends with at least one terminal coupled to one end of the memory alloy wire. The terminal includes two wings and an extended piece connected in the shape of a T. The two wings are disposed on opposite sides of the extended piece and perpendicular to the extended piece. Each wing comprises top and bottom surfaces, a front surface, and an outside end. The top surfaces of the two wings lie on a common top plane and the front surfaces of the two wings lie on a common front plane. The memory alloy wire is coupled to the extended piece of the terminal.