Fatigue life evaluation model for high-strength steel wire considering
different levels of corrosion
Abstract
Corrosion of steel wires is one of the most severe causes in the
deterioration of cables for cable-supported bridges. This paper studies
the quantitative influences of corrosion on the fatigue life of
high-strength steel wires, considering a wide variation in the degree of
corrosion. First, the multi-parameter Weibull model for
corrosion-stress-life (C-S-N) proposed by the authors of this paper is
introduced briefly, and the Goodman relation is employed to deal with
the dependences of stress ranges on positive stress ratios for
tension-tension fatigue. Fatigue data for high-strength steel wires are
collected from the literature for three groups with different ultimate
tensile strengths and the degree of corrosion ranging from 0.18% to
18.67%. This data is then used to estimate the parameters of the
Weibull model; subsequently, quantitative influences of corrosion on
fatigue life for steel wires with a wide range in the degree of
corrosion are illustrate and discussed in detail. The results indicate
that the influence of ultimate tensile strengths on fatigue life for
corroded high-strength steel wire can be ignored, because corrosion
causes crack nucleation more quickly, especially at lower stress ranges.
The fatigue life decreases more quickly with the increase in the
corrosion, and reduction on fatigue life caused by corrosion is more
pronounced under a lower stress range, which indicates that the fatigue
life is more sensitive to corrosion at lower stress ranges. Negative
correlation of fatigue life and corrosion increases as the stress range
decreases, which further confirms that corrosion has a higher influence
at lower stress ranges. The proposed Weibull model for C-S-N can provide
quantitative evaluation of the survival probability of high-strength
steel wires, defined in terms of their fatigue life, considering a wide
range in the degree of corrosion; these results can be used by
engineering designers to ensure the safety for cable-supported bridges
during their lifetime.