Shape Memory Alloy Ring Size Adjustment Stability
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Solution Overview
Problem
Existing shape-memory alloy jewelry items are prone to unstable size changes when worn due to transition temperatures close to body temperature, leading to unwanted deformation or loss.
Innovation Solution
Designing a ring with a shape memory alloy portion that has a transition temperature Af significantly higher than body temperature, allowing for reversible size adjustment without instability when worn, using alloys like palladium, platinum, or gold with Af temperatures above 80°C, enabling stable sizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If shape memory alloy jewelry items use transition temperatures close to body temperature, then easy size adjustment is achieved, but stability of the jewelry size when worn deteriorates
Solution Approach 1:
The patent changes the critical parameter of transition temperature from close to body temperature to significantly higher than body temperature (Af > 80°C). This parameter change allows the jewelry to maintain stable size when worn while still enabling easy size adjustment through controlled heating, thus resolving the contradiction between ease of operation and stability.
2Ease of operation
If plastic deformation is applied to change jewelry size, then size adjustment is achieved, but risk of irreversible damage increases
Solution Approach 1:
The patent replaces the mechanical plastic deformation system with a thermally-induced phase transformation system. Instead of applying mechanical stress to plastically deform the material, the invention uses controlled heating to induce martensitic phase transformation, allowing reversible size change without the risk of irreversible damage associated with plastic deformation.
Solution Approach 2:
The patent utilizes the martensitic phase transition of shape memory alloys, where heating above the Af temperature transforms the material from martensitic to austenitic phase, enabling reversible shape and size changes. This phase transition mechanism allows size adjustment without permanent deformation, resolving the contradiction between ease of operation and reliability.
3Manufacturing precision
If conventional resizing procedures are used, then precise size control is achieved, but manufacturing complexity and time increase
Solution Approach 1:
The patent replaces complex mechanical resizing procedures (cutting, material removal/addition, resoldering, polishing) with a simple thermal treatment process. By applying controlled heating to induce phase transformation, the jewelry can be resized precisely without requiring multiple complex operations, thus reducing manufacturing complexity while maintaining precision.
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 ring maintains its adjusted size stably when worn, preventing unwanted deformation and ensuring durability through higher transition temperatures, facilitating easy size changes without heat-induced instability.
Implementation Method 1
A shape memory alloy (SMA) is a metallic alloy possessing several properties: the ability to retain an initial shape and recover it even after deformation (one-way shape memory effect)
Implementation Method 2
The transition from one phase to the other occurs either through a change in temperature or through the application of stress. The advantage of AMFs is that the phase transformation is displacive
Implementation Method 3
Among the alloying materials (AMFs), so-called superelastic alloys have the capacity to deform significantly (up to 10%) reversibly under stress, creating a stress-induced phase. When the stress is removed, this new phase becomes unstable, and the alloy returns to its original shape.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to a piece of jewelry, in particular a ring (1) comprising at least one portion (20) made of a shape-memory alloy. The final phase transition temperature of the shape-memory alloy from martensitic to austenitic is higher than and sufficiently far from body temperature or wearing temperature so that said portion (20) does not change phase when the piece of jewelry is worn.