A Multifunctional Characterization Test Bench for Shape Memory Alloy Micro-Wires—Design, Implementation and Validation

Abstract

Most relevant to predicting the behavior of shape-memory-alloy (SMA)-based actuator-sensor applications activated by Joule heating are the electro-mechanical characteristics of the material under consideration. For a comprehensive characterization, a single setup that is able to provide all relevant data and information is desirable. This work covers the design, implementation and validation of such a high-end test bench for the holistic characterization of SMA micro-wires. In addition, the setup provides the possibility of application simulation experiments. Key elements of the design are the clamping mechanism guided on air bearings, a linear direct drive, a high-resolution load cell, a high-precision constant current source and a stress-controlled in-line wire sample installation. All measurements take place inside an isolated, temperature-controlled chamber. With the presented setup, the electro-mechanical and thermal characteristics of SMA wire samples with diameters from 20 µm to 100 µm can be determined. Via hardware-in-the-loop (HiL) implementation, the outputs with different biasing mechanisms and additional end-stops can be simulated even at high ambient temperatures. The generated results facilitate the prediction of the exact characteristics of SMA-driven actuator-sensor systems in a variety of applications and lead to a better general understanding of the alloy’s properties. All functionalities and features of the setup are presented by discussing the results of exemplary experiments.

Electro–Thermo–Mechanical Characterization of Shape Memory Alloy Wires for Actuator and Sensor Applications, Part 2: High‐Ambient‐Temperature Behavior

“…The experiments described in the following were carried out using a single setup meticulously detailed by Scholtes et al [ 2 ] For comprehensive information regarding the experiments and test setup beyond the descriptions provided here, please refer to that publication for exhaustive details on design, implementation, and validation.…”

“…(Reproduced under terms of the CC‐BY license Copyright 2023, Scholtes et al published by MDPI). [ 2 ]…”

“…Nonetheless, the whole picture with all facets is painted by also taking into account the previous articles on the characterization method [ 1 ] and the custom designed test rig. [ 2 ]…”

“…[ 11,29–31 ] Consequently, this study is centered on a commercially available NiTi wire measuring 72 μm in diameter. The experimental setup, detailed in another study [ 2 ] by Scholtes et al is purpose built for these microwires. In this article's experiments, two differently conditioned wires are investigated: one conditioned by the manufacturer and another subjected to additional thermoelectrical training.…”

Design, Modeling, and Experimental Validation of an Active Microcatheter Driven by Shape Memory Effects

“…In this study, a combination of two different materials is proposed for the design of active microcatheters. Shape memory alloys are widely used in different situations due to their remarkable shape memory effects, as well as their biocompatibility [19][20][21]. Once being heated beyond its austenite finish temperature, proper annealed SMA would regain its memorized shape at a much higher annealing temperature, eliminating its macroscopic deformation occurring in the martensitic phase.…”