Events Calendar

TITLE: MECHANICS OF HEAD-CARRYING RINGS, THREADING, AND KIRIGAMI BIOMIXERS: FUNCTIONAL TWISTS, CUTS, AND FOLDS IN TEXTILES AND SHEETS

ABSTRACT: Elastic instabilities in sheets and fibers enable shape-shifting and energy storing capabilities. Techniques like kirigami and origami, the Japanese arts of paper cutting and folding, have been extensively used to achieve 3-dimensional geometries from 2-dimensional materials and tune effective material properties. Similarly, twisting fibers and woven textiles results in the storage of strain energy. These strategic deformations in sheets and textiles have been utilized to engineer multi-functional soft robotic graspers, centuries old load bearing textile structures, and fiber-based transection tools. Here we design, understand, and explore the structure and applications of kirigami biomixers, head-carrying textile rings, and threading techniques. In the first half of this prospectus, we discuss the development of soft, scalable, and packable mixing mechanisms comprised of a kirigami end-effector connected in series with an origami actuator. The kirigami end-effectors consist of a co-linear cut pattern on a thin elastic shell with varying appendage shapes and the origami actuators are made of a rigid skeleton component sealed within a thin elastic sleeve. We determine the load and displacement requirements for end-effector closure and design requirement-specific, fluid-driven origami actuators by varying skeleton hinge parameters. We evaluate and demonstrate the mixing efficiency of these mechanisms through experimentation and image analysis. These kirigami end-effector - origami actuator mechanism units have versatile applications ranging from fluid and granular mixing to grasping objects of differing stiffness and shape. In the second half of this prospectus, we investigate the mechanics of multi-functional head-carrying textile rings and threading techniques used for transection and extraction. Throughout human history, the practice of using textile rings to facilitate the transport of goods (e.g. pots of water; harvested produce) atop the head has surfaced in cultures spanning vast time scales and geographic length scales. This technique is still used today predominantly by women in rural, agricultural communities. Textile rings are often fabricated by bending, twisting, and wrapping readily available materials (e.g. natural fibers in a plain weave), to form structures that distribute complex loads and conform to arbitrarily shaped objects. In this work, we study the mechanics of textile rings constructed from different fabrics and different wrapping strategies. We examine the effects of material (i.e. weaving pattern, fabric composition) and design (i.e. twists, folds) on the stiffness, conformability, and behavior of textile rings under quasistatic and dynamic loading conditions that mimic uneven terrain. We find that ring stiffness increases with the number of twists resulting in more rigid designs with low conformability which may be favorable for transporting solid objects with a curved base (e.g. baskets, containers). Softer ring designs exhibit increased conformability, which may be preferable for carrying and stabilizing non-uniform loads (e.g. sugar cane, wood). These findings provide a mechanistic understanding of head-carrying textile rings and illustrate the mechanical intuition and human ingenuity that enable women to carry up to 60% of their body weight atop their head. Finally, we outline our continuing study on the mechanics of threading. Threading is an ancient hair removal, beauty technique predominantly used by women, that originates from South Asia and the Middle East. It comprises of a single thread or fiber, of varying composition – often cotton or polyester, whose ends are twisted together and abruptly pulled apart resulting in the extraction or transection of the material in contact at the apex of the twisted fiber. We plan to investigate the effect of fiber composition on the storage of strain energy and friction during fiber contact, as well as the relationship of contact angle and extraction or transection capability.

COMMITTEE: ADVISOR/CHAIR Professor Douglas Holmes, ME/MSE; Professor Paul Barbone, ME/MSE; Professor Sheila Russo, ME/MSE