On the Probability Densities of the Output of Some Random Systems

Abstract

The probability density, mean, and variance of the displacement of simple linear one-degree-of-freedom systems are investigated when the spring constants and the initial conditions are random variables. The ensemble mean motion is found to be considerably different from the “mean” motion obtained by first averaging over the spring constants. Furthermore, it is found that only the first and second moments of the initial conditions affect the first and second moments of the displacement.