模糊-随机混合参数的机构运动可靠度计算方法

在目前机构产品的参数当中普遍存在着模糊变量和随机变量混合的情况，而现有的模糊-随机可靠度求解方法一般针对静态问题进行分析，不能有效描述具有混合不确定性的机构运动时变问题。基于机构运动误差分析，同时考虑失效判据和变量的模糊性，提出了基于改进包络函数的模糊-随机时变机构可靠性建模及计算方法。首先，将模糊判据转化为极限状态方程中的随机变量；其次，利用模糊论中的截集法处理模糊-随机混合变量，建立机构产品的模糊-随机时变可靠性模型；再次，利用改进的包络函数计算机构的运动时变可靠度；最后，结合四连杆机构的运动误差问题，验证了本文方法的可行性，结果表明该方法具有较高的计算精度。 

Computation method on motional reliability of mechanism under mixed parameters with fuzziness and randomness

Mixed uncertainties of random variables and fuzzy variables are ubiquitous in the parameters of the current mechanism products, but the existing fuzzy reliability model mainly aims at static problems, which cannot describe the time-dependent problem with mixed uncertainty. This paper proposes a reliability modeling and computation method of the fuzzy time-dependent mechanism based on the advanced envelope function through the kinematic error analysis of mechanism and considering the fuzziness of failure criterion and the variables. First, fuzzy criterion can be transferred into random variables in the limit state function. Then, the cut set of fuzzy theory can be used to deal with the fuzzy and random variables, and thus the fuzzy time-dependent reliability model is built. After that, the advanced envolope function is used to calculate the time-dependent reliability of the mechanism. Finally, the feasibility of the method is verified by the motion error issue of four-bar linkage. The results show that the method has high computational accuracy.