Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 148152

148152 - Highly Tunable Dry Adhesion Through Constrained Buckling 

Dynamically tunable interfacial dry adhesion plays a significant role in numerous biological functions and industrial applications. Among various strategies, pneumatics-activated adhesive devices draw much attention due to their distinct advantages such as fast speed, reliable performance, large adhesion tunability and easily accessible materials. To understand and predict adhesion strength of pneumatics-activated adhesives, it is necessary to examine their interfacial mechanics that is nonlinearly coupled with the large deformation of the devices under pressure. 

In this work, I first introduce a novel way to achieve tunable adhesion using low pressure by inducing sidewall bulging or buckling in soft hollow pillars (SHPs). Through a combination of experiments and simulations, it is shown that the dry adhesion of these SHPs can be changed by more than two orders of magnitude using low activating pressure, both positive and negative ones. We demonstrate that a single SHP can be activated by a micro-pump to manipulate various lightweight objects with different curvatures and surface textures. It is also demonstrated that an array of SHPs can realize selective pick-and-place of an array of objects. These demonstrations and the underlying fundamental mechanics illustrate the simplicity and versatility of these SHPs with highly tunable dry adhesion.

Next, we study the effect of various geometrical parameters, including the cross-section shape of the SHPs, on tunable dry adhesion of pressure-activated soft hollow pillars. Specifically, elliptical, square, and rectangular contact shapes are considered and their effects on tunable adhesion of the soft hollow pillars are compared to that of circular contact geometry thoroughly. The results show that soft hollow pillars with elliptical, square, and rectangular contact surfaces demonstrate rich interfacial delamination behaviors that depend on the contact outline geometry and internal pressure. Among all contact geometries, elliptical contact has the highest adhesion tunability yet requires lowest activating pressure owing to the non-uniform curvature distribution of the contact outline. However, when the eccentricity increases, the elliptical contact has reduced tunability of adhesion caused by the contact of opposing sides of the sidewall upon buckling. For square and rectangular contacts, they have the lowest adhesion tunability and need higher activating pressure than those of circular and elliptical contact since the 90-degree edges of the sidewall prohibit buckling instability. Our findings greatly broaden the design space of pneumatics-activated adhesive devices by adding the contact geometry of the soft hollow pillars as a new design parameter, which can provide valuable guidance to tunable adhesive design for various applications in manufacturing and robotics.

Presenting Author: Wanliang Shan Syracuse University

Presenting Author Biography: Dr. Shan joined the Department of Mechanical and Aerospace Engineering (MAE) at Syracuse University (SU) in July 2019. Before that, he was assistant professor of Mechanical Engineering (ME) at University of Nevada, Reno (UNR) for five years, after finishing a two-year postdoctoral research fellowship at ME Department at Carnegie Mellon University. He completed his Ph.D. study from MAE Department at Princeton University in 2012 and graduated with B.E. in Thermal Science and Energy Engineering from University of Science and Technology of China in 2006. His research group currently focuses on interdisciplinary research in Smart, Hybrid, Active and Nature-inspired Materials, Mechanics, and Machines. Fundamental insights from solid mechanics, materials engineering, machine learning, and thermal science are emphasized for the design and fabrication of soft multifunctional materials and high-performance robotic mechanisms, which impact critical application domains such as soft robotics and biomedical devices. His research, innovation and educational efforts have been funded by SU, UNR, NASA, and NSF through many initiatives and programs. In particular, Dr. Shan is a recipient of the prestigious NSF Career Award (2023). He is currently serving as associate editor on soft robotics for IEEE Robotics and Automation Letters (RA-L).

Authors:

Wanliang Shan Syracuse University