区间干涉模型下的非概率可靠性应用研究

Application of non-probabilistic reliability based on interval interference model

针对可靠性分析中不确定参数的分布类型难以精确获得的情况,采用非概率方法进行可靠性分析.用区间模型描述不确定参数,结合应力-强度非概率集合干涉理论,建立了不同情况下的非概率可靠性指标,分析了某传动轴在概率模型和区间模型下的可靠性指标以及不确定参数的离差与非概率可靠性之间的关系.结果表明:当传动轴外径为50mm时,二者均认为结构可靠,外径为48mm时,概率可靠度为0.999 803,非概率可靠度为0.982 110,两种结论是一致的,但非概率方法更保守,同时传动轴的非概率可靠度随着不确定参数离差的增加而逐渐减低,其中强度离差对可靠度影响最大,扭矩离差最小.说明增加壁厚以及减小不确定参数的离差可以提高传动轴的可靠度,表明非概率可靠性分析方法的工程适用性.

The non-probabilistic method was proposed according to the distribution pattern of uncertain parameters inaccurately acquired from the reliability analysis. Interval model was used to describe the uncertain parameters, and based on non-probabilistic set-based stress- strength interference theory, the non-probabilistic reliability index was studied under different conditions. Meanwhile the reliability index under probabilistie model of a propeller shaft was compared with that of interval model and the changes of the non-probabilistic reliability were also observed with different deviation of the uncertain parameters. The result shows that when the outer diameter of the propeller shaft is 50 mm the structure was reliable under probabilistic model and interval model, but when the outer diameter is 48 mm the probabilistic and non- probabilistic reliabilities were 0. 999 803 and 0. 982 110, respectively. Therefore, conclusions were consistent under probabilistic and interval models, but the non-probabilistic method was more conservative. Meanwhile with increase of deviation for the uncertain parameters, the non- probabilistic reliability of propeller shaft gradually reduced. Therefore, the strength of deviation is the main factor affecting non-probabilistic reliability, while the torque of deviation is the least. Consequently the reliability of propeller shaft increased with the increase of the thickness and decrease of the deviation of uncertain parameters. The method of non-probabilistic reliability analysis was feasible.