FORCED VIBRATION OF TIP-MASSED CANTILEVER WITH NONLINEAR MAGNETIC INTERACTIONS

Abstract

This paper predicts the nonlinear relative motion of a cantilever with a tip mass and magnets based on a distributed-parameter model. The Kelvin viscoelastic model is used to account for the damping in the cantilever. Under the harmonic base excitation, the governing equation is deduced via a coordinate transformation linked to its static equilibrium. To qualitatively validate those results captured from the approximate methods, the finite difference method and the multi-scale method are respectively employed to determine the natural frequency and the steady-state response of forced vibration. It is analytically demonstrated that those modes uninvolved in a certain resonance actually have no effect on the response amplitude of the stable steady-state motion. The effects of forcing amplitude, viscoelastic damping, and tip mass on the steady-state response are detailed via the amplitude–frequency response curves. For the first time, the current works theoretically illustrated the conversion from the hardening-type behavior to the softening-type versus the augmenting magnetic force, as well as the opposing effect of different tip masses on the first mode and the higher modes.