Shape Memory Wire Anchor With Multi-Loop Fastening
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Solution Overview
Problem
Shape memory alloy actuators face detachment issues due to the high pulling force of the contraction, exceeding the holding force of the attachment mechanism, leading to functional failure.
Innovation Solution
An anchoring system for shape memory material members using a housing and fastener configuration that secures the member in multiple loops around an aperture, with a fastener sandwiched between the structure and the fastener, and a deformed housing to prevent separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple attachment mechanism is used to secure the shape memory alloy wire, then the device complexity is reduced, but the holding force is insufficient to withstand the high pulling force during contraction
Solution Approach 1:
The attachment mechanism is divided into multiple independent components: a housing with aperture, a fastener, and a deformed housing section. The wire is segmented into multiple loops around the aperture rather than a single attachment point. This segmentation distributes the high pulling force across multiple attachment points, increasing total holding force while keeping each individual component relatively simple.
Solution Approach 2:
The wire is routed through the housing aperture and back through the housing, creating nested loops where the wire passes through itself multiple times. The deformed housing section is nested within the housing structure, creating a compact multi-layered attachment arrangement that maximizes holding force within a small volume.
2Strength
If the wire is secured in multiple loops around the aperture, then the holding force is increased to withstand contraction forces, but the device complexity increases due to the housing and fastener configuration
Solution Approach 1:
Multiple functional elements are merged into a single integrated housing component: the aperture for wire routing, the fastener reception area, and the deformed housing section for additional securing are all combined in one piece. This merging reduces the number of separate parts while maintaining the multi-loop wire configuration and high holding force capability.
Solution Approach 2:
The deformed housing section serves dual functions: it acts as both the housing structure and the securing mechanism. The deformation of the housing itself creates the anchoring effect, eliminating the need for separate complex fastening components while maintaining high holding force.
3Reliability
If the housing is deformed around the wire to prevent separation, then the reliability is improved by preventing detachment, but the manufacturing precision requirements increase due to the deformation process
Solution Approach 1:
The housing is pre-formed with the aperture and deformation characteristics before final assembly. The deformed section is prepared in advance during housing manufacturing, so that during wire installation, the housing simply needs to be positioned and secured without requiring complex real-time deformation operations, reducing manufacturing precision requirements during assembly.
Solution Approach 2:
The housing material properties are selected and adjusted to enable controlled deformation at specific stress thresholds. By changing the material parameters (ductility, yield strength), the housing can be deformed to predetermined shapes that provide reliable wire retention without requiring extremely precise deformation control during manufacturing.
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 system effectively prevents separation of the shape memory material during actuation, ensuring reliable actuator function by withstanding over 200 Newton of force and maintaining attachment.
Implementation Method 1
Shape memory materials change shape when an activation input is provided to the material. When the activation input is discontinued, the shape memory material returns to its original shape.
Data Source
AI summary
A system can be used to anchor a contracting member (e.g., a shape memory material member). The system can include a structure including a surface and defining an aperture, a housing, and a contracting member. An end portion of the contracting member can extend through the housing, on the surface of the structure in more than one loop about the aperture, and back through the housing. The housing can be deformed around the contracting member extending through the housing. The system can also include a fastener received in the aperture such that a portion of the contracting member is secured between the surface of the structure and the fastener.