Time-dependent Reliability Analysis For Mechanical Structure And Its Application

Structural reliability is closely related with the quality of mechanical products.Most of the traditional reliability analysis methods are based on uncertain modelswhich are delicate and ignore deterioration in material properties and dynamic loaduncertainty. But real engineer practical is more complex：1, Deterioration in materialproperties, dynamic load uncertainty are widespread among practical engineering;2,For some practical engineering problems, enough samples can’t be got to constructprecise random distribution. These all require reliability analysis algorithm of th eability to cope with more complex situation as to solve practical problems better.Based on the above ideas, we studied reliability analysis method for time-dependentmechanical structures, which provides an effective analytical tool for assessing designreliability over the whole lifecycle, the main contents are as follows:1, A probability-interval hybrid reliability analysis method for time-variantstructures is proposed. In this method, the stochastic process of the limit-state functionwith interval parameters is firstly simplified into the problem of reliability analysis forstructures with probability-interval uncertainty. An efficient scheme of sequentialiteration is also used to solve the two-layer nesting optimization, and finally the upperand lower bound of time-dependent reliability is obtained.2, A time-variant reliability analysis method for non-linear limit-state functions isexamined. In this method, the stochastic process in the limit-state function is firstdiscretized. Each discretized limit-state function is linearized at the Most ProbablePoint, and it is further simplified into a time-invariant reliability analysis problemwhich is then solved by using the traditional FORM.3, A time-variant reliability analysis method based on stochastic processdiscretization(TRPD) is proposed. Using time discretization, a stochastic process canbe converted into random variables, thereby transforming a time-variant reliabilityproblem into a conventional time-invariant system reliability problem. By linearizingthe limit-state function using the first-order reliability method (FORM) andfurthermore introducing a new random variable, the converted system reliabilityproblem can be efficiently solved.