Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150793

150793 - Spontaneous Snapping-Induced Jet Flows for Fast, Maneuverable Soft Swimmer 

Manta rays and other batoid fish are notable for achieving high speeds (1 - 3 body length per second) despite their operation at low frequencies (  2 Hertz). Recent attention has focused on the development of high-performance soft swimmers capable of navigating diverse aquatic environments, including both the water surface and underwater scenarios. In this work, we draw inspiration from the flapping motion observed in batoids, and present an approach that harnesses spontaneous snapping instabilities to develop fast and maneuverable soft pneumatic swimmers. Characterized by a body length of 23 mm and a self-weight of 1.95 grams, this swimmer achieves an impressive speed of 6.8 body lengths per second when actuated at 1.67 Hertz, surpassing our previous record, and demonstrating a speed increase of 0.81 times compared to the bistable counterpart. The weighted soft swimmer, featuring versatile swimming modes, exhibits adaptability and maneuverability across various tasks in both air-water interface and underwater scenarios. Furthermore, with a payload of 190 grams, including a circuit board, battery, and air pump, the untethered soft swimmer successfully navigates outdoors, swimming distances exceeding 1 meter within 30 seconds.

Here, we propose a design approach for soft flapping swimmer, aiming to achieve spontaneous snapping for high-speed and highly maneuverable swimming performance both near the air-water interface and underwater. The soft flapping swimmer having spontaneous snapping consists of a unidirectional bending soft actuator and thermally treated precurved flexible wings. The thermal treatment applied to the bistable flexible wings releases a certain amount of prestored energy, transforming them into flapping wing structures. The slight inflation of the soft actuator triggers a passive snap-through motion of the wings, resulting in amplified flapping and rotational motions. Upon deflation of the pneumatic soft actuator, the flexible wings spontaneously snap back without requiring additional energy input. The soft flapping swimmer, featuring an attached weight at the bottom of its soft body to regulate the buoyancy while maintaining optimal swimming performance, demonstrates the ability to navigate both the air-water interface and underwater environments. Additionally, we demonstrate an autonomous and untethered soft swimmer integrated with the power unit, enabling outdoor swimming scenarios. Using a comprehensive approach involving experimental characterization, theoretical modeling, computational fluid dynamics (CFD) simulation, and particle image velocimetry (PIV) technology, we systematically assessed the working principle and swimming performance of soft flapping swimmers. Building upon this understanding, we leverage the principle of consecutive snapping to design fast and maneuverable soft swimmers capable of functioning near the air-water interface and underwater.

Presenting Author: Haitao Qing North Carolina State University

Presenting Author Biography: Mr. Haitao Qing is a current Ph.D. student in Mechanical Engineering in North Carolina State University. He received B.S. and M.S. in Mechanical Engineering from Hanyang University in 2019 and 2021. His research interests include mechanics guided soft robotics and mechanics and design of mechanical metamaterials.

Authors:

Haitao Qing North Carolina State University
Jie Yin North Carolina State University