MS Thesis Presentation by Anne-Marie Albanese Lerner
Tuesday, May 24, 2005
(Dr. Kenneth A. Cunefare, Chair)
"The Design and Implementation of a Magnetorheological Silicone Composite State-Switched Absorber"
Tuned vibration absorbers (TVAs) are spring-mass-damper devices used to minimize energy in a vibrating body. TVAs decrease in efficiency when the vibrating body is subjected to variable, broadband, or random excitation. A state-switched absorber (SSA) can be used in these variable, broadband, or random excitation cases to more effectively reduce excitation. An SSA is a mass-spring-damper where one or more of these elements can instantaneously and discretely change. An SSA was designed, built and tested to fit the specifications for TVAs found on ATR 72 and 42 airplane fuselages. A magnetorheological elastomer (MRE), an elastomer with imbedded iron particles, was selected as a variable spring. Flux lines concentrated through all MREs in absorber configurations. MREs containing 35% iron by volume yielded the largest frequency shift.
A 35% MRE based absorber had a frequency range of 45-183 Hz, which corresponds to a 360% frequency increase. Transient absorber behavior was observed by recording rise and drop times to step field intensity changes. The 35% MRE absorber yielded a 0.20 second rise time and a 0.03 second drop time. Future work will determine whether a modified input signal can generate an appropriate transient response