模糊变量与随机变量组合时的模糊可靠度计算方法

模糊安全事件隶属函数的确定，是模糊变量和随机变量组合时模糊可靠性设计中有待解决的关键问题。基于模糊概率理论与可靠性设计原理，提出了一种应力为常量、强度为模糊量时的模糊可靠度计算方法。在此基础上，提出了模糊强度和随机应力组合时模糊安全事件隶属函数的确定原理，给出了具体确定方法，进而解决了如何直接用L．A．Zateh提出的模糊概率公式计算该情况下的模糊可靠度问题。通过模糊可靠度计算实例，验证了其原理和方法的正确性。所提出的原理和方法同样适用于直接计算随机强度和模糊应力组合时的模糊可靠度，亦可推广应用于研究稳健设计中由广义应力和广义强度组成的模糊约束条件的可行稳健性问题，因而具有实用价值和普遍意义。

METHOD FOR CALCULATING THE FUZZY RELIABILITY WITH FUZZY VARIABLE AND RANDOM VARIABLE

How to determine the membership function of the fuzzy safety event is a key problem to be solved in the reliability design with fuzzy variable and random variable. According to the fuzzy probability theory and the reliability design principle, the method used for calculating the fuzzy reliability with fuzzy strength and constant stress was put forward. On the basis of the calculating method put forward , the principle of determining the membership function of the fuzzy safety event was proposed and the complete and detailed method was given. As a result, the problem how to calculate the fuzzy reliability directly by the formula of fuzzy probability, which was put forward by L.A.Zateh, was resolved. The calculating example of the fuzzy reliability with fuzzy strength and random stress made clear that the principle and the method proposed are correct. At the same time, the principle put forward in this paper is suitable for directly calculating the fuzzy reliability with random strength and fuzzy stress and it can also be popularized to be used in discussing the feasibility robustness problem of the fuzzy restriction conditions which are composed of generalized stress and generalized strength in robust optimal design, so it possesses practical value and universal significance.