Design of morphing patterns in knitted SMA textile actuators via knitting codes

Area of Science:

• Materials Science
• Textile Engineering
• Robotics

Background:

• Shape memory alloys (SMAs) are effective soft actuators due to their unique properties and ease of actuation via Joule heating.
• Integrating SMA wires into textiles creates compliant, conformable, and human-friendly actuators using conventional manufacturing.
• Limited research exists on the modal behavior of SMA-based textile actuators, hindering broader applications.

Purpose of the Study:

• To investigate the modal behavior and morphing capabilities of knitted SMA-based textile actuators.
• To explore the relationship between knitting patterns, structural design, and actuator deformation.
• To demonstrate the scalability and performance tuning of these novel actuators.

Main Methods:

• Designed and fabricated nine distinct knitted SMA textile actuator patterns (six plane-based, three band-based) using knitting codes.
• Analyzed the relationship between loop transition boundaries and deformation axes to control bending angles in plane-based patterns.
• Quantitatively evaluated actuation forces in horizontal and vertical directions.

Main Results:

• Knitted SMA actuators successfully exhibited predicted deformations across various morphing patterns.
• The study identified key relationships between structural design elements (loop transitions) and bending angles.
• Actuation forces were quantitatively measured, confirming performance tunability via structural modifications.

Conclusions:

• Knitted SMA textile actuators offer predictable and tunable deformations through structural design.
• The findings provide a foundation for developing advanced SMA-based textile actuators with controlled modal behavior.
• Demonstrations of morphing flowers highlight the potential for scalable and versatile applications.