Toughening stretchable fibers via serial fracturing of a metallic core

↵† Present address: Department of Aerospace Engineering, Auburn University, Auburn, AL 36849-5338, USA. Tough, biological materials (e.g., collagen or titin) protect tissues from irreversible damage caused by external loads. Mimicking these protective properties is important in packaging and in emerging applications such as durable electronic skins and soft robotics. This paper reports the formation of tough, metamaterial-like core-shell fibers that maintain stress at the fracture strength of a metal throughout the strain of an elastomer. The shell experiences localized strain enhancements that cause the higher modulus core to fracture repeatedly, increasing the energy dissipated during extension. Normally, fractures are catastrophic. However, in this architecture, the fractures are localized to the core. In addition to dissipating energy, the metallic core provides electrical conductivity and enables repair of the fractured core for repeated use. The fibers are 2.5 times tougher than titin and hold more than 15,000 times their own weight for a period 100 times longer than a hollow elastomeric fiber. Tough materials found in nature maintain the structural integrity of many biol...

Agritechnica 2015 preview: Celebrating innovation as this year’s winners are announced – NEWS

With over 300 entries registered in the show’s innovation awards, next month’s Agritechnica looks set to live up to its reputation as an innovation launch pad. Steven Vale details some of the gold and silver medal winners. Operating at pressures of up to 2,000 bar, Krone’s Premos 5000 processes straw swaths into 16mm-diameter pellets. Capable of outputs up to 5,000kg/hr, pellets are transferred to a five-tonne capacity hopper (up to 9cu.m.). Potential uses for the pellets include animal bedding and as livestock feedstuff. Also, with a density of 600-700kg/cu.m (three to four times that of straw bales), 2.5kg of pellets substitutes about 1kg of heating oil. With a tractor power requirement of about 400hp, Krone is keen to test the gold-medal winning machine in hay and lucerne next year, ahead of a possible launch sometime in 2017. John Deere won a gold medal for its ProCut, a technique designed to ensure the knives of its self-propelled forage harvester’s chopping drum are kept sharp. The system uses an inductive method and two sensors to control the gap between the knives and the shearbar. Automatically measuring the sharpness of all knives, the system not only indicates the be...