Ni-Ti Alloy Two-Way Shape Memory Training Process
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for inducing a two-way shape memory effect (TWSME) in shape memory alloys (SMAs) used in medical devices, such as endovascular stents, fail to achieve sufficient two-way recovery strain and temperature stability, particularly in the range of 10° C.-37° C., and degrade when heated above the austenite finish temperature.
Innovation Solution
A process involving reorienting deformation of Ni-Ti alloys in the R-phase or B2-phase, followed by thermomechanical cycling, to stabilize the two-way memory effect within the B2R temperature range, achieving a maximum recovery strain of about 1.2% and maintaining stability through R-phase transformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional training methods are used to induce TWSME, then the device can be deformed and heated to achieve shape recovery, but the two-way recovery strain is insufficient and the temperature stability degrades when heated above Af
Solution Approach 1:
The patent applies parameter changes by modifying the training process parameters: performing deformation in the R-phase or B2-phase, controlling the temperature range (TR-30°C to TR+30°C), and specifying the number of training cycles (3-10 cycles). These parameter adjustments enable achieving sufficient two-way recovery strain (≥0.2%) while maintaining temperature stability within the required range (10°C-37°C), resolving the contradiction between recovery strain magnitude and temperature stability.
2Stability of the object's composition
If the device is subjected to repeated thermocycling to stabilize TWSME, then the temperature range stability improves, but the processing time and complexity increase
Solution Approach 1:
The patent implements continuity of useful action by performing multiple training cycles (3-10 cycles) of thermomechanical loading and unloading within the R-phase or B2-phase temperature range. Each cycle contributes to stabilizing the TWSME parameters, and the continuous repetition ensures that the temperature range stability is achieved without requiring excessive time. The process efficiently stabilizes the two-way recovery strain and temperature range through systematic, repeated action.
3Reliability
If the device is deformed in the R-phase or B2-phase and subjected to thermomechanical cycling, then the two-way memory effect is stabilized within the B2R temperature range, but the process complexity increases
Solution Approach 1:
The patent simplifies the training process by defining specific parameter ranges: deformation temperature (TR-30°C to TR+30°C), number of cycles (3-10), and phase state (R-phase or B2-phase). These parameter specifications reduce the complexity by providing clear guidelines for achieving stable TWSME. The process becomes more manageable and reproducible when these parameters are standardized, resolving the contradiction between functional stability and process complexity.
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 process effectively induces a two-way shape memory effect in SMAs, ensuring high recovery strain and thermal stability within the required temperature range, even after repeated thermal cycling, enhancing the functionality and reliability of medical devices like stents.
Implementation Method 1
A two-way shape memory effect (TWSME) can be induced in a device formed of a SMA by a single or repeated deformations of the device in conjunction with thermocycling through a temperature range over which martensitic and austenitic transformations occur
Implementation Method 2
A plastically deformed device formed of a SMA when heated over a certain temperature range will 'remember' its original shape and return to it
Implementation Method 3
thermocycling through a temperature range over which martensitic and austenitic transformations occur
Data Source
AI summary
A process for inducing a two-way shape memory effect in a device forward of a shape memory alloy and a device made by the process are disclosed. The two-way memory effect occurs in the device in a temperature range of between about 5° C. to 25° C. wherein the training process is based on B2R phrase transformations. An R-phase formation or reorientation takes place in the device under stress whereupon the R-phase transforms into stress induced martenite. The device is subjected to thermocycling.