SPECTRAL RESPONSE FOR N RANDOM EXCITATIONS OF A NONLINEAR OSCILLATOR WITH NON-LINEAR DAMPING CHARACTERISTIC IN THE FLUID MEDIUM

Abstract

Abstract: In nuclear power plant reactors, the mechanical components are surrounded by heat-conducting fluid in steady motion. Some of them, such as fuel-rod assemblies, are separated by very small clearances. Non-linear vibratory behavoir can be induced either by the steady excitation or accidentally, due to seismic excitation for example. An approximate analytical procedure is presented to estimate the power spectral density of response of n random excitation of non-linear oscillator with non-linear damping characteristic in the fluid medium. A natural method of attacking non-linear problems ist a replace the governing set of non-linear differential equations by an equivalent set of linear equations. The method will be briefly discussed in the following sections. Fundamental theory of this linearization procedure can be found in Caughey, Roberts and Spanos.