The authors are developing a cost- and weight-effective means for achieving an improved low- and mid-frequency acoustic environment in payload fairings for rockets at lift-off. The solution will be an active noise control system with an optimum selection of distributed active vibration absorbers (DAVAs) and acoustic actuators. High sound pressure inside a launch vehicle fairing during lift-off can damage delicate equipment in the payload. Space launch vehicle payload noise is a very important problem in the successful launch and deployment of space instruments and equipment. Measurements taken during the first few seconds of launch show very high sound pressure level (SPL) in the low frequency range of 60 to 250 Hz. High SPL is a severe problem because interior noise impinges on the instruments and equipment in the payload and can lead to their vibrational failure. Engineers have made moderate progress in addressing this problem by strengthening the instruments and by applying passive noise control treatment to the fairing. Both strategies incur significant penalties of added weight and financial cost and reduced allowable payload size. For further progress in suppressing low-mid frequency noise, another way is needed. The authors are developing a hybrid passive/active noise control system based on emerging technology of distributed active vibration absorbers (DAVAs). DAVAs are constructed from acoustic foam and area-distributed actuators. Passively it behaves as a tuned mass damper at low frequencies and a viscous damper at high frequencies. Actively a DAVA produces mechanical forces that are directed to reduce fairing vibrations.
A proof of concept for the applicability of active structural control on a Vertical Turning Lathe was demonstrated. The effort proved that active damping can reduce chatter in a production machine tool when machining tough materials like nickel. Significant vibration reductions and surface roughness improvements were achieved.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.