Ronald L. Spangler

Use of piezoelectric devices to control snowboard vibrations

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.

TESTING OF AN ACTIVE SMART MATERIAL SYSTEM FOR BUFFET LOAD ALLEVIATION

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.

Wavelength stabilization in an excimer laser source using piezoelectric active vibration control

Excimer laser light sources for photolithography are subject to a cycle of ever-tightening precision requirements, dictated by the design-rule shrinks planned into the industry roadmap. But pulse-to-pulse stability of the center wavelength of the emitted light is limited by the presence of vibration in key components and structures. This paper covers the application of Active Vibration Control (AVC) technology to an excimer laser to mitigate the effects unwanted vibration, and enable compliance with anticipated future stability specifications. The laser system is described, from a structural-dynamics point of view. A systematic approach to vibration diagnostics is presented, with experimental results to support key conclusions regarding the types and sources of vibrations. Next, analytical assessment of active control performance is discussed, followed by breadboard-type implementation results showing reductions of > 30% in a key stability performance metric.

High-performance beam stabilization for next-generation ArF scanner systems

With the advent of 193 nm systems processing 300 mm wafers, the production lithography cell is about to undergo a technology shift. The mechanism for delivering the beam from the light source to the illumination system, here referred to as a Beam Delivery Unit (BDU), must change to meet the challenges imposed by this shift. To support these changes, Cymer is developing a BDU that will guarantee a stable beam at the scanner entrance during exposure. The beam stabilization control system has been implemented in a test BDU. We shall present results from experiments that demonstrate our ability to significantly improve short and long term “Beam Stability”.