An official website of the United States government
Abstract Mechanical metamaterials are architected manmade materials that allow for unique behaviors not observed in nature, making them promising candidates for a wide range of applications. Existing metamaterials lack tunability as their properties can only be changed to a limited extent after the fabrication. Herein, a new magneto‐mechanical metamaterial is presented that allows great tunability through a novel concept of deformation mode branching. The architecture of this new metamaterial employs an asymmetric joint design using hard‐magnetic soft active materials that permits two distinct actuation modes (bending and folding) under opposite‐direction magnetic fields. The subsequent application of mechanical compression leads to the deformation mode branching where the metamaterial architecture transforms into two distinctly different shapes, which exhibit very different deformations and enable great tunability in properties such as mechanical stiffness and acoustic bandgaps. Furthermore, this metamaterial design can be incorporated with magnetic shape memory polymers with global stiffness tunability, which also allows for the global shift of the acoustic behaviors. The combination of magnetic and mechanical actuations, as well as shape memory effects, impart wide tunable properties to a new paradigm of metamaterials.
more »
« less
Reprogrammable Mechanics via Individually Switchable Bistable Unit Cells in a Prestrained Chiral Metamaterial
Abstract Architected materials exhibit unique properties and functionalities based on the geometric arrangement of their constituent materials. In most cases, these parameters are fixed, requiring that the system be redesigned and reconstructed if different properties are desired. Both stimuli‐responsive materials and modular designs have been used to enable re‐programmable properties in the past, but often have limitations, such as the need for a continuous application of external stimuli or power, or unwanted global morphing. In this study, a locally stable anti‐tetra chiral (LSAT) metamaterial is introduced consisting of independently multistable units that can deform and change state without inducing changes in the global morphology. Adjacent cells are only weakly coupled, allowing the collective metamaterial to be switched between many different possible states. Local bistability enables re‐programmable heterogeneity, such as the snapping of cells along an edge or diagonally within the architected material. Utilizing finite element analysis (FEA), the influence of key geometric parameters on the re‐programmability of the metamaterials is systematically investigated. The effect of these parameters on properties such as shear stiffness, Poisson's ratio, and vibration are also investigated using experimental prototypes. This re‐programmable metamaterial promises to expand the design space for mechanical systems, with potential applications in non‐traditional computation, robotic actuation, and adaptive structures.
more »
« less
- Award ID(s):
- 2239308
- PAR ID:
- 10510747
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 9
- Issue:
- 17
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Origami, the ancient Japanese art of paper folding, is not only an inspiring technique to create sophisticated shapes, but also a surprisingly powerful method to induce nonlinear mechanical properties. Over the last decade, advances in crease design, mechanics modeling, and scalable fabrication have fostered the rapid emergence of architected origami materials. These materials typically consist of folded origami sheets or modules with intricate 3D geometries, and feature many unique and desirable material properties like auxetics, tunable nonlinear stiffness, multistability, and impact absorption. Rich designs in origami offer great freedom to design the performance of such origami materials, and folding offers a unique opportunity to efficiently fabricate these materials at vastly different sizes. Here, recent studies on the different aspects of origami materials—geometric design, mechanics analysis, achieved properties, and fabrication techniques—are highlighted and the challenges ahead discussed. The synergies between these different aspects will continue to mature and flourish this promising field.more » « less
-
Abstract Architected materials typically maintain their properties throughout their lifetime. However, there is growing interest in the design and fabrication of responsive materials with properties that adapt to their environment. Toward this goal, a versatile framework to realize thermally programmable lattice architectures capable of exhibiting a broader range of mechanical responses is reported. The lattices are composed of two polymeric materials with disparate glass transition temperatures, which are deterministically arranged via 3D printing. By tailoring the local composition and structure, architected lattices with tunable stiffness, Poisson's ratio, and deformation modes controlled through changes in the thermal environment are generated. The platform yields lightweight polymer lattices with programmable composition, architecture, and mechanical response.more » « less
-
Abstract Mechanically programmable, reconfigurable micro/nanoscale materials that can dynamically change their mechanical properties or behaviors, or morph into distinct assemblies or swarms in response to stimuli have greatly piqued the interest of the science community due to their unprecedented potentials in both fundamental research and technological applications. To date, a variety of designs of hard and soft materials, as well as actuation schemes based on mechanisms including chemical reactions and magnetic, acoustic, optical, and electric stimuli, have been reported. Herein, state‐of‐the‐art micro/nanostructures and operation schemes for multimodal reconfigurable micro/nanomachines and swarms, as well as potential new materials and working principles, challenges, and future perspectives are discussed.more » « less
-
Abstract Programmable mechanically active materials (MAMs) are defined as materials that can sense and transduce external stimuli into mechanical outputs or conversely that can detect mechanical stimuli and respond through an optical change or other change in the appearance of the material. Programmable MAMs are a subset of responsive materials and offer potential in next generation robotics and smart systems. This review specifically focuses on hydrogel‐based MAMs because of their mechanical compliance, programmability, biocompatibility, and cost‐efficiency. First, the composition of hydrogel MAMs along with the top‐down and bottom‐up approaches used for programming these materials are discussed. Next, the fundamental principles for engineering responsivity in MAMS, which includes optical, thermal, magnetic, electrical, chemical, and mechanical stimuli, are considered. Some advantages and disadvantages of different responsivities are compared. Then, to conclude, the emerging applications of hydrogel‐based MAMs from recently published literature, as well as the future outlook of MAM studies, are summarized.more » « less
