NEW APPROXIMATIONS FOR SORM INTEGRALS

New and simple closed form approximations for SORM integrals which can be used for reliability estimations of rare and common events are proposed and compared with exact results, Breitung's asymptotic and Tvedt's three-term formulas. In numerical examples, it is shown that the proposed approximations are yielding very good results and better than the available ones for all values of beta and for all curvatures. Thus SORM reliability estimations can be performed more accurately using the developed formulas even in the case of small or negative beta values.