NOTE ON CYCLE COUNTS IN IRREGULAR LOADS

In this paper we discuss cycle counting methods, such as rainflow-, crest-to-trough-, positive peak-count and different damage accumulation rules, for irregular random loads, which have an infinite number of local extremes in finite intervals, e.g. the fourth spectral moment is infinite. We present conservative bounds for the expected damage for such loads from the upcrossing intensity. These results are illustrated by examples of Gaussian, xz-, and Morison-loads. NOMENCLATURE E(X) = mathematical expectation of the random variable X E(X I Y = y) = conditional expectation of X given Y = y Var(X) = variance of the random variable X a E A = a is an element of the set A {f; . } = the set of points t fulfilling the condition . # { . } = the number of elements in the set { . } 1 {. ,(x) = the indicator function of the set { . } sup{ . } = the supremum (least upper bound) of elements in the set { . } inf{ } = the infimum (greatest lower bound) of elements in the set { . 1