UMass Amherst researchers develop a way to use curved creases to give thin curved shells a fast, programmable snapping motion
Inspired by natural "snapping" systems like Venus flytrap leaves and hummingbird beaks, a team led by physicist Christian Santangelo at the University of Massachusetts Amherst has developed a way to use curved creases to give thin curved shells a fast, programmable snapping motion. The new technique avoids the need for complicated materials and fabrication methods when creating structures with fast dynamics.
Until now, there has not been a general geometric design rule for creating a snap between stable states of arbitrarily curved surfaces. The advance should help materials scientists and engineers who wish to design structures that can rapidly switch shape and properties.
Credit: Beatrice Murch/Wikimedia Image 1 and Image 2 with Creative Commons Attribution-Share Alike 2.0 Generic license.
The advance should help materials scientists and engineers who wish to design structures that can rapidly switch shape and properties, says Santangelo. He and colleagues, including polymer scientist Ryan Hayward, point out that until now, there has not been a general geometric design rule for creating a snap between stable states of arbitrarily curved surfaces.
"A lot of plants and animals take advantage of elasticity to move rapidly, yet we haven't really known how to use this in artificial devices," says Santangelo. "This gives us a way of using geometry to design ultrafast, mechanical switches that can be used, for example, in robots." Details of the new geometry appear in an early online issue of Proceedings of the National Academy of Sciences.
The authors point out, "While the well known rules and mechanisms behind folding a flat surface have been used to create deployable structures and shape transformable materials, folding of curved shells is still not fundamentally understood." Though the simultaneous coupling of bending and stretching that deforms a shell naturally gives items "great stability for engineering applications," they add, it makes folding a curved surface not a trivial task.
Santangelo and colleagues' paper outlines the geometry of folding a creased shell and demonstrates the conditions under which it may fold smoothly. They say the new technique "will find application in designing structures over a wide range of length scales, including self-folding materials, tunable optics and switchable frictional surfaces for microfluidics," such as are used in inkjet printer heads and lab-on-a-chip technology.
The authors explain, "Shape programmable structures have recently used origami to reconfigure using a smooth folding motion, but are hampered by slow speeds and complicated material assembly." They say the fast snapping motion they developed "represents a major step in generating programmable materials with rapid actuation capabilities."
Their geometric design work "lays the foundation for developing non-Euclidean origami, in which multiple folds and vertices combine to create new structures," write Santangelo and colleagues, and the principles and methods "open the door for developing design paradigms independent of length-scale and material system."
Other members of the team at UMass Amherst are Nakul Bende, Arthur Evans, Sarah Innes-Gold and Luis Marin, with physicist Itai Cohen at Cornell University. This work is funded by the National Science Foundation.
Janet Lathrop | EurekAlert!
New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State
Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy