Staggered Nitinol Wire Actuator Array for High Linear Displacement and Force-to-Mass Ratio

Area of Science:

• Materials Science
• Mechanical Engineering
• Biomedical Engineering

Background:

• Development of lightweight, high-performance actuators is crucial for advanced prosthetics.
• Nitinol (NiTi) shape memory alloys offer unique properties for actuation but require optimized designs for high strain and force.
• Existing actuators often face limitations in achieving both high displacement and force-to-mass ratios.

Purpose of the Study:

• To design and evaluate a novel Nitinol (NiTi) actuator array for high linear displacement and force generation.
• To investigate the relationship between the number of staggered NiTi wires and achievable strain levels.
• To determine the force-to-mass ratio of the developed actuator system.

Main Methods:

• A unique staggered linear array configuration of Nitinol (NiTi) wires was designed.
• Joule heating was employed to induce phase change and linear displacement in the NiTi wires.
• Strain levels were measured for arrays with three to seven staggered NiTi wires.
• Force generated by the actuator was measured and compared to its mass to calculate the force-to-mass ratio.

Main Results:

• The NiTi actuator design achieved strain levels of 20.4%, comparable to biological muscles.
• Increasing the number of staggered wires (three to seven) demonstrated varying strain capabilities.
• The actuator system exhibited an effective force-to-mass ratio exceeding 5500 with a seven-wire array.

Conclusions:

• A lightweight, high-strain actuator utilizing a staggered Nitinol (NiTi) wire array has been successfully developed.
• The design demonstrates significant potential for applications requiring high linear displacement and force generation.
• This research highlights the actuator's suitability for use in advanced prosthetic systems.