Cambridge, MA--Far out, man--a snowboard that gives a smoother ride while allowing tighter, higher-speed turns, all while under control! The secret of K2 Corp's (Vashon Island, WA) new Electra snowboards is two vibration-eating piezoelectric dampers from Active Control eXperts (ACX). These are mounted near the left and right edges at the front of the board between the front boot binding and the nose--the area predicted to have the greatest vibrational displacement (strain).
The principle is the same as on K2's Smart Ski introduced two years ago (DN 2/5/96, p. 53). Piezoceramic dampers convert mechanical vibration energy into electrical energy, which is applied across a shunt for dissipation as heat. An LED indicator lights when the board is vibrating so the rider knows the damper is operating.
ACX ran on-slope tests to determine the major snowboard vibration mode frequencies--the largest and most noticeable of which is the second mode. "The beauty of the technology is that it allows us to nail specific modes electronically, with no batteries required," says Adam Bogue, ACX vice president. "And the faster you go, the better it works." That is because the 80% vibration amplitude reduction gives more of a difference in absolute level with the greater amplitude vibrations that come as speed increases.
ACX says key to the snowboard system design was damper placement. Using finite element models with MSC/NASTRAN(TM) from MacNeal-Schwendler (Los Angeles, CA), designers predicted induced strain across the board. These predictions were verified by strain-gage instrumented snowboard runs. Since strain produces vibrations, positioning the dampers in the highest strain areas has the greatest damping effect. The piezo dampers have a high mechanical stiffness, similar to the board materials, thus the dampers did not change the board characteristics and allowed efficient energy transfer to the damper. Cameron , senior design engineer at K2 comments, "Many professional riders say it's the best board they've ever used."