Reliability analysis model of time-dependent multi-mode system under fuzzy uncertainty: Applied to undercarriage structures

There lacks fuzzy reliability analysis model to assess the reliability level of time-dependent multi-mode system (T-sys) under fuzzy uncertainty, thus this paper defines T-sys failure possibility firstly to address this problem. Then fuzzy simulation is proposed for estimating the failure possibility of T-sys (T-sys-FS), in which the failure possibility estimation of T-sys is transformed into searching fuzzy design point, a failure point with the largest joint membership degree. To improve the efficiency of T-sys-FS for searching fuzzy design point, adaptive Kriging is inserted into T-sys-FS to establish a more efficient method shorten as T-sys-AK-FS. By use of the relationship between the failure state of T-sys and that of transient single mode, a new learning function is proposed in T-sys-AK-FS, on which the critical mode and critical instant may be selected for efficiently updating Kriging model of T-sys performance function. Additionally, based on the partial correct information provided by the current Kriging model and the properties of the fuzzy design point, an improved T-sys-AK-FS version (T-sys-AK-FSi) is proposed by combining the candidate sample pool reduction strategy, then the computational efficiency is enhanced further for searching the T-sys fuzzy design point. Several examples are presented to illustrate the accuracy and efficiency of the proposed methods.