An Intermetallic NiTi-Based Shape Memory Coil Spring for Actuator Technologies

Abstract

Amongst various intermetallic shape memory alloys (SMAs), nickel–titanium-based SMAs (NiTi) are known for their unique elastocaloric property. This widely used shape remembering material demonstrates excellent mechanical and electrical properties with superior corrosion resistance and super-long fatigue life. The straight-drawn wire form of NiTi has a maximum restorable strain limit of ~4%. However, a maximum linear strain of ~20% can be attained in its coil spring structure. Various material/mechanical engineers have widely exploited this superior mechanic characteristic and stress-triggered heating/cooling efficiency of NiTi to design smart engineering structures, especially in actuator technologies. This short technical note reflects the characteristics of the NiTi coil spring structure with its phase transformations and thermal transformation properties. The micro-actuators based on NiTi have been found to be possible, suggesting uses from biomedical to advanced high-tech applications. In recent years, the technical advancements in modular robotic systems involving NiTi-based SMAs have gained speculative commercial interest.

A Novel Alveolar Distractor Incorporating Nickel–Titanium Alloy Springs: A Preliminary In Vitro Study

“…Upon deactivation, a rapid drop in force occurred between 8 and 7.7 mm. From 7.7 mm onwards, the Highland springs showed a more gradual reduction in the unloading force, similar to that of stainless-steel springs [ 14 ]. Conversely, the ORMCO spring displayed a constant force level until approximately 3 mm of displacement, after which another drop to the original levels occurred.…”

“…Superelastic NiTi open-coil springs have been commonly used in fixed appliance orthodontic treatment to create space between teeth. Their performance has been attributed to the austenite to martensite phase transformation, which occurs when tensile stress is applied [ 14 ]. When the energy stored from the stress-induced martensite phase is released during deactivation, a relatively constant force is produced during the martensite to austenite phase transformation.…”

Titanium Alloys and Titanium-Based Matrix Composites

“…The most popular among them is nitinol (NiTi), which in fact is a nickelbased alloy, but is quite often described together with functional titanium alloys. Shimoga et al, in their technical report [20], reflected on the characteristics of the NiTi coil spring structure with its phase transformations and thermal transformation properties. It was postulated that the micro-actuators based on NiTi could be used for advanced high-tech applications.…”

The Study of New NiTi Actuators to Reinforce the Wing Movement of Aircraft Systems

“…The widespread use of NiTi is due to its fatigue behavior and mechanical strength. Depending on the customized application, NiTi is furnished commercially in several forms: spring, wire, thin films, powder particles, and nanoparticles [ 11 ]. Many research activities stem from actuator processing, involving NiTi-based materials, especially wire and spring units to construct linear and rotary actuators [ 12 , 13 ].…”

“…Different applications of NiTi have contributed to developing new c ators. The widespread use of NiTi is due to its fatigue behavior and mech Depending on the customized application, NiTi is furnished commerc forms: spring, wire, thin films, powder particles, and nanoparticles [11] activities stem from actuator processing, involving NiTi-based materials and spring units to construct linear and rotary actuators [12,13]. The drawn wire of commercial NiTi has a maximum recovery strain limit of ~4 linear strain of ~20% can be achieved using coiled NiTi wires by successiv shape memory properties in the linear coil prototype [14,15], which is t for the movement exerted by the spring on the prototype parts, according properties of the spring (Figure 1).…”