基于模糊随机变量的机械零件广义可靠性设计

GENERAL RELIABILITY DESIGN FOR MECHANICAL PARTS BASED ON FUZZY-RANDOMNESS VARIABLE

机械零件的强度和所受外载具有模糊、随机不确定性 .对于可靠性设计一般只考虑模糊性、随机性或者两者共时存在的情形 ,没有考虑模糊性、随机性相互融合的情形 .本文根据模糊随机规划理论、机械零件可靠性设计原理 ,提出了机械零件模糊随机广义可靠性的概念 ,把机械零件的可靠度和失效概率表示成条件概率 ,建立了模糊随机可靠性设计的一般模型 ,传统的随机变量可靠性设计以及模糊可靠性设计模型都是该模型的特例 .模糊随机可靠度计算模型可以在考虑设计人员的经验的情况下降低零件的失效概率 ,该模型不需要强度或应力的隶属函数转化为安全事件的隶属函数 .给出设计计算的公式 。

Both the strength and the applied load possed randomness and fuzziness. Only randomness or fuzziness or both two concurrence were considered for the classic reliability design or fuzzy reliability design, but amalgamation both fuzziness and randomness was not considered.Based on the fuzzy-randomness programming theory and principle of reliability design for mechanical parts,the concept of general reliability with fuzzy-random variables for mechanical parts was put forward and the general reliability calculation model was established. The reliability or failure probability could be described as a conditional probability in this model when the boundary between the safety and the failure was determined.The general reliability design considering not only randomness and fuzziness of variables but fuzzy-randomness was higher than the classic & fuzzy reliability only considering randomness & randomness of variables and the classic reliability design or fuzzy reliability design model was special instance of the general fuzzy-randomness reliability model. The other general reliability calculation model for mechanical parts was also set up based on the boundary between the safety and failure, and which could more objectively reflect the degree of the safety of a mechanical parts system. These models were confirmed by illustrative examples and contradistinctive analysis was done.