Taking inspiration from the Velcro brand hook-and-loop fastener that lines shoes, secures camping equipment and fastens medical aids, German engineers have designed a steel version for extreme loads and environments that can support 35 tons and withstand 800 degrees Celsius (or 1,472 degrees Fahrenheit).
You may not have known that a 2-inch square piece of Velcro can support 175 pounds. But a square meter of the new steel fastener, called Metaklett, is capable of supporting 400 times that, according to Josef Mair, a research associate who led a team at the Technical University in Munich, Germany.
Like conventional Velcro, Metaklett can be opened up without specialized tools and used again. Mair says his spring-steel fastener is tough enough for use in building facades or car assembly — anywhere standard synthetic hook and loop fasteners can’t hold up, such as in extreme heat or aggressive chemicals.
“A car parked in direct sunlight can reach temperatures of 80 °C, and temperatures of several hundred °C can arise around the exhaust manifold. Aggressive disinfectants are used for cleaning purposes in hospitals, and traditional hook, and loop fasteners are too weak for use in the construction of building façades,” Mair said in a statement, adding that Metaklett can operate in such extreme environments.
Metaklett is constructed from perforated steel strips 0.2 millimeters thick and comprised of one strip of springy steel brushes and another of jagged spikes.
Two of the team’s tested models were successful: a spring lock version called the “Flamingo,” and a hook-and-loop system known as the “Entenknopf,” or “duck’s head.”
The Entenknopf model (pictured, top right) is based on the traditional synthetic hook and loop system, and its delicate steel hooks can attach at any angle to the loops in the perforated metal loop tape.
The Flamingo model (pictured, bottom right) is even more stable, and consists of wider hook elements that snap into the openings in a perforated tape, bent in such a way that they deform elastically under light pressure and glide into the holes “like the synthetic buckles on backpack straps.” Once inserted, they return immediately to their original form and, thanks to their sprung splaying arms, resist back pull like an expanding rivet.