No abstract

This paper explains how piezoelectric devices can be used to control vibrations in a snowboard. Furthermore the details of the approach, testing, design and analysis of a piezoelectric damper applied to a production snowboard are described here. The approach consisted of determining the principal modes of vibration of a snowboard during its operation (on-slope). This information was used to develop a finite element model of the structure. The finite element model was used to find the areas of higher strain energy where a piezoelectric device could be applied and be effective in reducing undesired vibrations. Several prototype piezoelectric dampers were built, applied to snowboards and tested on snow. The proper amount of damping was selected by the test riders, so that a configuration could be selected for production of the 1998 K2 Electra snowboard. The piezoelectric damper selected reduced the snowboard vibration by 75% at the mode to which it was tuned, allowing for a smoother ride and a more precise control of the snowboard in any kind of snow condition.

A comparison of different commercially available packaged piezoelectric actuators is presented. The comparisons are based on force, stress and strain performance at similar field densities. A new metric of comparison, based on energy efficiency, is introduced. This paper provides designers with useful information on actuators and actuator performance for industrial applications. The QuickPack® and PowerAct™ actuators remain the only packaged piezoelectric actuators to be produced in high volume and to feature in commercial applications.

The use of piezoelectric elements as a means for implementing broadband, low authority structural control with passive and active electrical impedance matching is investigated. Passive techniques are shown to be ineffective for truly broadband problems due to the relatively large inherent )J,eLue,ebLr,b ba)Jab'La"be. n b L I Y e ,eb,,luq"e> a!= U~.YcilU)JGU usllly ,,IC >IIII"lla.lle""D sensing and actuation (SSA) circuit. Detailed analysis of circuit tuning issues in conjunction with mechanical boundary conditions of the piezoelectric element is presented. The result is a set of guidelines for SSA component selection to enable the implementation of guaranteed stable positive real feedback for damping enhancement. Examples and experimental results on the SERC Interferometer Testbed are presented. Difficulties in implementation presented by the unmodeled piezoelectric losses and non-linearities, which prove to be significant when using axially stacked elements, are discussed.

Modem high-performance aircraft can experience severe buffeting vibrations of the tail empennage during high angle of attack maneuvers, which negatively impacts fatigue life and controllability. ACX and the US Air Force have developed a system to control these vibrations, using piezoelectric strain actuators and active feedback control.This paper details the design, fabrication, and ground-testing of a full-scale prototype Buffet Load Alleviation system for the F/A-18, with an emphasis on ground-test results. In these tests, attenuation of greater than 50% of the RMS buffet response was demonstrated using two channels of control.