Nominal limit state factor and dimension reduction method in reliability optimization for turbine disk

Computing intensity and cost consuming are two important difficulties in reliability-based design optimization(RBDO).the single-looping optimization (SLO) methods and the double-looping optimization(DLO) methods cannot deal with them.Some based on the inverse most probable point(MPP) transforms the probabi listic constraints to deterministic constraints,but they cannot decouple the two procedures including reliability analysis and optimization,in additional,there are too large errors because of using the first order reliability methods(FORM) in the methods to be adaptive in aero-engine design.The nominal limit state fact or method was proposed that can decouple the two procedures of reliability analy sis and optimization and can make the reliability analysis become a pre-procedur e before optimization.Moreover,the uni-variate dimension reduction method was us ed to obtain accurate probability of failure that only requires the results of F ORM in previous reliability analysis.Finally,an example on structure optimizatio n for turbine disk was given to illustrate that the proposed methods are more ef ficient than the DLP method and are close to the deterministic optimization in e fficiency.