Alleviating vibrations along a harmonically driven nonuniform Euler–Bernoulli beam by imposing nodes

A passive approach is developed to quench excess vibration along a harmonically driven, arbitrarily supported, nonuniform Euler–Bernoulli beam with constant thickness (height) and varying width. Vibration suppression is achieved by attaching properly tuned vibration absorbers to enforce nodes, or points of zero vibration, along the beam. An efficient hybrid method is proposed whereby the finite element method is used to model the nonuniform beams, and a formulation based on the assumed modes method is used to determine the required attachment force supplied by each absorber to induce the desired nodes. Knowing the attachment forces needed to induce nodes, design plots are generated for the absorber parameters as a function of the tolerable vibration amplitude for each absorber mass. When the node locations are judiciously chosen, it is possible to dramatically suppress the vibration along a selected region of the beam. As such, sensitive instruments can be placed in this region and will remain nearly stationary. Numerical studies illustrate the application to several systems with various types of nonuniformity, boundary conditions, and attachment and node locations; these examples validate the proposed method to passively control excess vibration by inducing nodes on nonuniform beams subjected to harmonic excitations.