G101084 An Analysis of the Nonlinear Mode Coupling Oscillation of Bifilar Pendulum : Two Swinging Modes

Abstract

A bifilar suspension pendulum,a uniform density bar suspended at its two points by two strings of same length,may swing in a vertical plane or make torsional oscillation about a vertical axis.The swinging in a co-plane of the strings and the bar is called Mode 1,and the swinging in a vertical plane perpendicular to the bar is Mode 2.Mode 3 is the torsional oscillation about a vertical axis.Typical features of Mode 1 are studied here using the method of multiple scales and method of harmonic balance.It is shown that the configuration of strings supporting the pendulum leads to the nonlinear softening/hardening,which may be applicable to mitigation technology.