29 Jun 7 July: Talk by Mont Hubbard (USA) ‘making snow park jumps safer’
Tuesday, July 7, 2015, 12:30-13:30 h.
Making Snow Park Jumps Safer: Controlling Equivalent Fall Height.
Location: Room G, 3ME
In the USA more than 90% of ski resorts now have terrain parks, most including jumps. Injured skiers and snowboarders are twice as likely to have sustained a spine or head injury if they were hurt inside a terrain park vs. outside. There is significant cost, morbidity, and mortality associated with ski/snowboard injuries, especially spinal cord injuries. Similar safety problems exist in elite downhill skiing at the World Cup and Olympic level. Both likelihood and severity of injury are directly related to impact at landing. The snow impulse acting on the landing jumper is directly proportional to the component of velocity perpendicular to the landing surface. Previous research has showed how to shape the landing surface y(x) so that equivalent fall height h, a measure of mass specific energy dissipation in landing, can be controlled to pre-specified levels for all take off speeds and jump lengths. The shape y(x) satisfies a first order differential equation with an infinite number of solutions, all of which limit landing impact. The solution requiring minimum snow budget to fabricate is found by limiting jumper take off and landing transition accelerations. Although easy to build, tabletop jumps with flat decks and straight landing areas do not limit EFH. Such controlled-landing-impact jumps have been designed, constructed and measured to perform as designed, using accelerometers mounted to the snowboards of jumpers. Present day trends favor the integration of real time information in the terrain park creation process. Computer-aided design software has also been developed that simplifies and automates the design process and will serve as basis for snow park construction using real time GPS position information.
About the speaker
Mont Hubbard received the B.S. degree in Engineering Science from the U.S. Military Academy, West Point, NY, in 1964, the M.S. in Mechanical Engineering from the Massachusetts Institute of Technology, Cambridge, MA in 1965, and the Ph.D. in Aeronautics and Astronautics from Stanford University, Palo Alto, CA in 1975. Since 1974, he has been a Professor in the Department of Mechanical and Aerospace Engineering, at the University of California, Davis. During 1982 and 1996 he was a Visiting Scholar in the Engineering Department at Cambridge University, England. During 1988 he spent a Sabbatical Leave in the Division of Applied Sciences, at Harvard University. He is presently Professor Emeritus in the Department. His research includes applications of modeling, estimation and control in mechanical and biomechanical systems. A special research interest is sport mechanics and optimization. Professor Hubbard has been supported by the U.S. Olympic Committee with grants for the study of javelin throwing, ski jumping and the dynamics of the bobsled. He is the author of 150 papers including more than 50 in the area of sports mechanics and biomechanics.