Open AccessTime-variant rule-based reliability of corroded structures by Monte Carlo simulation
Author(s) -
K M Neumann,
Bernt J. Leira,
Ole Tom Vårdal,
Sören Ehlers
Publication year - 2019
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/700/1/012036
Subject(s) - monte carlo method , hazard , reliability (semiconductor) , corrosion , reliability engineering , limit state design , failure rate , function (biology) , hazard ratio , importance sampling , computer science , reliability theory , statistics , engineering , structural engineering , mathematics , materials science , confidence interval , physics , chemistry , power (physics) , organic chemistry , quantum mechanics , evolutionary biology , metallurgy , biology
General widespread corrosion is of increasing concern for structural reliability of ageing marine structures, particularly for semi-submersible pontoons. Conditional failure rate, also termed hazard function is sought to describe the increasing maintenance required with age. Literature is reviewed connecting corrosion degradation to hazard rate, either through a time degrading limit state function, or statistical data for time to failure. Here, a rule based failure definition is applied based on corrosion tolerance levels, together with a linear corrosion degradation model to make a time variant limit state function. Monte Carlo simulation is applied based on statistical models for the basic variables including importance sampling, to obtain the time to failure distribution from which the hazard curve is deduced. A more realistic hazard function is also produced, requiring average of 3 simulations to exceed the tolerance in order to fail. It is seen that this approach delays the increase of the hazard curve, at the expense of higher failure rates.