随机模型参数不确定时结构失效概率的区间估计

Interval Estimation of Failure Probability of Structures In UncertainParameters of Stochastic Model

在缺乏足够数据或信息不完整的情况下,给出失效概率的界限,比给出一确定的单值具有更高的可信度。本文用区间变量描述随机可靠性模型参数的不确定性,提出了考虑随机模型分布参数不确定性时,机械结构失效概率的区间估计方法。实际算例表明:结构的失效概率对随机模型参数的偏差非常敏感。说明在进行可靠性建模时,对模型的可靠性必须给予足够的重视。

Uncertainties present everywhere in the physical and mathematical models. In most cases, it is difficult to describe the performance of systems using a precisely single number. But it is easy to describe the condition by using a range or an interval to represent it. In the reliability computation, when insufficient accurate data are available or the information is incomplete, a range representation of probability of failure may be more confident than the representation by a single number. In this paper, uncertainties of the parameters of stochastic model of reliability are described by intervals. A procedure is presented for the interval estimation of failure probability of mechanical structures when the distribution parameters are uncertain. It is shown by a numerical example that the probability of failure may be very sensitive to the possible errors of stochastic model. So enough attention must be paid to the reliability of stochastic modeling.