EXPERIMENTAL-STUDY OF STEADY-STATE LOCALIZATION IN COUPLED BEAMS WITHACTIVE NONLINEARITIES

Steady-state nonlinear motion confinement is experimentally studied in a system of weakly coupled cantilever beams with active stiffness non linearities. Quasistatic swept-sine tests are performed by periodicall y forcing one of the beams at frequencies close to the first two close ly spaced modes of the system, and experimental nonlinear frequency re sponse curves for certain nonlinearity levels are generated. Of partic ular interest is the detection of strongly localized steady-state moti ons, wherein vibrational energy becomes spatially confined mainly to t he directly excited beam. Such motions exist in neighborhoods of stron gly localized antiphase nonlinear normal modes (NNMs) which bifurcate from a spatially extended NNM of the system. Steady-state nonlinear mo tion confinement is an essentially nonlinear phenomenon with no counte rpart in linear theory, and can be implemented in vibration and shock isolation designs of mechanical systems.