VIBRATION CONTROL OF BEAMS BY BEAM-TYPE DYNAMIC VIBRATION ABSORBERS

Dynamic vibration absorbers with one degree of freedom are generally applied to the passive control of beam vibration. These absorbers are useful to control a single mode of vibration under harmonic excitation. In this paper, a beam-type dynamic vibration absorber is presented and is composed of a beam (dynamic absorbing beam) under the same boundary conditions as the main beam and uniformly distributed, connecting spring and damper between the main beam and absorbing beam. Equations of motion of the system in modal coordinates of the main beam become equal to those of the two-degrees-of-freedom system with two masses and three springs. Formulas for optimum design of the beam-type dynamic vibration absorber are proposed by using the optimum design method of a dynamic absorber in two degrees of freedom, obtained by Den Hartog’s method. Numerical calculations indicated the response of the main beam without damping is reduced with the exception of the response of the second, and the one with damping is remarkably reduced.