Experimental and Analytical Investigation of Nonlinear Coupled Oscillators under Random Excitation

Summary

The nonlinear interaction of a two degree-of-freedom oscillator subjected to a wide band random excitation is investigated analytically and experimentally. The analytical investigation employs the Fokker-Planck equation together with a non-Gaussian closure scheme. The solution predicts response statistics in terms of system parameters and excitation spectral density level. In the experimental study, tests are conducted for long time intervals which are enough to reveal all possible dynamic characteristics of the system. The measured signals are processed to estimate response statistics such as mean squares, spectral densities, and probability density functions. The results show a qualitative agreement between predicted and measured response statistics. Both approaches give common features such as the autoparametric vibration absorbing effect, and nonstationarity in the coupled oscillator statistics. The measured probability density functions show a slight deviation from Gaussian curves.