Buckliballs, Origami Lobsters and The Science Of Instability
Traditional engineering teaches students to avoid mechanical instability, or collapse, in layman's terms. But a new field of study is emerging known as "extreme mechanics." Scientists, engineers and researchers are examining the way cabbage leaves ripple, paper crumples and pollen travels. They say that by studying the way these elements react and collapse scientists can develop more effective medicines and advanced engineering structures.
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"In civil engineering, buckling is commonly associated with failure that must be avoided. For example, one typically wants to calculate the buckling criterion for columns and apply an additional safety factor, to ensure that a building stands," Pedro Reis, the Esther and Harold E. Edgerton Assistant Professor of Civil and Environmental Engineering and Mechanical Engineering at MIT told MIT News. "We are trying to change this paradigm by turning failure into functionality in soft mechanical structures. For us, the buckliball is the first such object, but there will be many others."
The buckliball, at first glance, looks like a ball deflating. But the rate of collapse, and the shape of the contracted ball, are precisely engineered. Two separate research teams coordinated on the buckliball; one team focused on digital fabrication techniques, like 3-D printing, while the other focused on analyzing the mechanics of the design and performance. Engineers design the buckliball according to dimple size, thickness of the thin shell inside the dimple and the stiffness of the material from which the buckliball is made. Buckilballs are modeled, in part, off of viruses, which undergo reversible structure transformations in response to changes in environment. The technology used to create buckliballs is being heralded as a new approach to engineering and could be used to create gadgets, such as a tent that springs automatically from a backpack, to micro-scale projects such as drug-delivery capsules.
Another extreme mechanics project on the horizon is a radical new 3-D printer being developed by Christian Santangelo, a physicist at the University of Massachusetts Amherst, and a team of researchers including two origami artists and an origami mathematician. Computer programs that print complex origami patterns, such as lobsters, are only the basic first step for Santangelo's team. Santangelo, who recently published a paper on the behavior of elastic materials, is working on a 3-D printer that would create a 2-D sheet inscribed with a pattern of instabilities that would then automatically fold itself into the desired shape. The goal is to create patterns that are far beyond human dexterity. His team is studying the way cells in leaves replicate to observe how the cells organize themselves to form ripples.
From viruses to leaves, the science of extreme mechanics continually looks to nature for answers. ""We are trying to learn from nature," Reis told Nature. "How it evolved to deal with these problems for which we have no intuition is very inspiring."
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